From james.p.lux at jpl.nasa.gov  Mon Dec  1 00:23:29 2008
From: james.p.lux at jpl.nasa.gov (Lux, James P)
Date: Sun, 30 Nov 2008 16:23:29 -0800
Subject: [time-nuts] Voltage standards
In-Reply-To: <20081130.151328.1120076896.imp@bsdimp.com>
Message-ID: <C5586E81.2FF3%James.P.Lux@jpl.nasa.gov>

Exactly.. I'm sure I'm not the only one on this list that has contemplated home use of liquid helium or even making the stuff.  Hey, if Onnes could do it 100 years ago, so can we.

I assume the cryogen isn't being used for superconductivity in this case, but for just being cold.  In which case, perhaps LH2 or LN2 would serve almost as well.  The latter, particularly, is pretty manageable (i.e. You don't have to make it yourself).

Cost wise, I like the snippet I read in Scientific American a decade or so ago.. LN2 is the cost of milk, LHe is the cost of fine scotch whisky
Is a obsessive precision worth a bottle of scotch?

Jim

On 11/30/08 2:13 PM, "M. Warner Losh" <imp at bsdimp.com> wrote:

In message: <49330CF9.5040205 at xtra.co.nz>
            Bruce Griffiths <bruce.griffiths at xtra.co.nz> writes:
: Cryogenic standards arent really feasible for home use as most require
: liquid helium coolant.

This has got to be one of the best lines in a time-nuts email :)

Warner

From imp at bsdimp.com  Mon Dec  1 00:27:54 2008
From: imp at bsdimp.com (M. Warner Losh)
Date: Sun, 30 Nov 2008 17:27:54 -0700 (MST)
Subject: [time-nuts] Voltage standards
In-Reply-To: <C5586E81.2FF3%James.P.Lux@jpl.nasa.gov>
References: <20081130.151328.1120076896.imp@bsdimp.com>
	<C5586E81.2FF3%James.P.Lux@jpl.nasa.gov>
Message-ID: <20081130.172754.-1540392776.imp@bsdimp.com>

The thing that got me was the word 'really' in Bruce's statement.  It
read like someone who had tried it, had limited success, but in the
end wound up believing that while possible, it wasn't really
practical.  After thinking that, I couldn't imagine that somebody on
the list hadn't tried it for some reason or another over the years.

After all, as you say, a fine bottle of scotch isn't that expensive
when it comes to the pursuit of your obsessions :)

Warner


In message: <C5586E81.2FF3%James.P.Lux at jpl.nasa.gov>
            "Lux, James P" <james.p.lux at jpl.nasa.gov> writes:
: Exactly.. I'm sure I'm not the only one on this list that has contemplated home use of liquid helium or even making the stuff.  Hey, if Onnes could do it 100 years ago, so can we.
: 
: I assume the cryogen isn't being used for superconductivity in this case, but for just being cold.  In which case, perhaps LH2 or LN2 would serve almost as well.  The latter, particularly, is pretty manageable (i.e. You don't have to make it yourself).
: 
: Cost wise, I like the snippet I read in Scientific American a decade or so ago.. LN2 is the cost of milk, LHe is the cost of fine scotch whisky
: Is a obsessive precision worth a bottle of scotch?
: 
: Jim
: 
: On 11/30/08 2:13 PM, "M. Warner Losh" <imp at bsdimp.com> wrote:
: 
: In message: <49330CF9.5040205 at xtra.co.nz>
:             Bruce Griffiths <bruce.griffiths at xtra.co.nz> writes:
: : Cryogenic standards arent really feasible for home use as most require
: : liquid helium coolant.
: 
: This has got to be one of the best lines in a time-nuts email :)
: 
: Warner
: _______________________________________________
: time-nuts mailing list -- time-nuts at febo.com
: To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
: and follow the instructions there.
: 
: 


From james.p.lux at jpl.nasa.gov  Mon Dec  1 00:45:34 2008
From: james.p.lux at jpl.nasa.gov (Lux, James P)
Date: Sun, 30 Nov 2008 16:45:34 -0800
Subject: [time-nuts] Voltage standards
In-Reply-To: <20081130.172754.-1540392776.imp@bsdimp.com>
Message-ID: <C55873AE.2FF8%James.P.Lux@jpl.nasa.gov>




On 11/30/08 4:27 PM, "M. Warner Losh" <imp at bsdimp.com> wrote:

> The thing that got me was the word 'really' in Bruce's statement.  It
> read like someone who had tried it, had limited success, but in the
> end wound up believing that while possible, it wasn't really
> practical.  After thinking that, I couldn't imagine that somebody on
> the list hadn't tried it for some reason or another over the years.
>
> After all, as you say, a fine bottle of scotch isn't that expensive
> when it comes to the pursuit of your obsessions :)
>
> Warner

And surely, with these grim economic times, liquid helium dewars are going
to be popping up on the surplus market. Then, at least, you'll have a place
to store that liquid helium.

And speaking of cryogens, has anyone on the list done cryogenic sapphire
ring oscillators? (at home)  After all, folks at JPL are doing this
" We present design progress and subsystem test results for a new short-term
frequency standard, the Voltage Controlled Sapphire Oscillator (VCSO).
Included are sapphire resonator and coupling design, cryocooler
environmental sensitivity tests, Q measurement results, and turnover
temperature results. A previous report presented history of the design
related to resonator frequency and frequency compensation [1]. Performance
goals are a frequency stability of 1?10-14 (1 second ? ? ?100 seconds) and
two years or more continuous operation. Long-term operation and small size
are facilitated by use of a small Stirling cryo-cooler (160W wall power)
with an expected 5 year life." http://hdl.handle.net/2014/39769

Seems that running a cryocooler is probably a bit easier than pouring liters
of liquid helium into a cryostat.


Jim



From richiem at hughes.net  Mon Dec  1 00:58:40 2008
From: richiem at hughes.net (Richard Moore)
Date: Sun, 30 Nov 2008 16:58:40 -0800
Subject: [time-nuts] V refs -- Bruce
In-Reply-To: <mailman.484.1228088343.2542.time-nuts@febo.com>
References: <mailman.484.1228088343.2542.time-nuts@febo.com>
Message-ID: <20A0DA18-ED7F-4DA5-AE99-F568F001ED79@hughes.net>

On Nov 30, 2008, at 3:39 PM, tBruce wrote:

> Message: 6
> Date: Mon, 01 Dec 2008 11:53:32 +1300
> From: Bruce Griffiths <bruce.griffiths at xtra.co.nz>
> Subject: Re: [time-nuts] V refs
>
> The uA714 is claimed to be an OP07 equivalent.
> A chopper stabilised amplifier would have lower drift and flicker  
> noise,
> however the zener drift and flicker noise probably dominates.
>
> Stacking LTZ1000's in the same way is a little tricky.
> The only satisfactory method I have devised so far uses a PJFET as a
> voltage controlled resistor to sink the zener current whilst  
> allowing it
> to be reused to bias lower LTZ1000s in the series stack.
>
> Bruce

Bruce, The 714 opamp provides gain in the Datron 1082, and I would  
use one LTZ1000 (or two in parallel, rather than try to use them in  
series). A while back I tried using two LM399s in series in a Fluke  
895, and really didn't like the results -- a single 399 with an amp  
was better in every way I could measure. As an alternative to a  
chopper like the 1151, I might consider an OPA27. I have used the now  
unobtainable OPA111 in the past, and that was a superb DC amp; they  
(TI) claim the OPA27 is as good.

Dick Moore


From dforbes at dakotacom.net  Mon Dec  1 01:12:56 2008
From: dforbes at dakotacom.net (David Forbes)
Date: Sun, 30 Nov 2008 18:12:56 -0700
Subject: [time-nuts] Voltage standards
In-Reply-To: <C5586E81.2FF3%James.P.Lux@jpl.nasa.gov>
References: <C5586E81.2FF3%James.P.Lux@jpl.nasa.gov>
Message-ID: <a06240501c558e99fe33f@[192.168.0.24]>

At 4:23 PM -0800 11/30/08, Lux, James P wrote:
>Exactly.. I'm sure I'm not the only one on this list that has 
>contemplated home use of liquid helium or even making the stuff. 
>Hey, if Onnes could do it 100 years ago, so can we.
>
>I assume the cryogen isn't being used for superconductivity in this 
>case, but for just being cold.  In which case, perhaps LH2 or LN2 
>would serve almost as well.  The latter, particularly, is pretty 
>manageable (i.e. You don't have to make it yourself).
>
>Cost wise, I like the snippet I read in Scientific American a decade 
>or so ago.. LN2 is the cost of milk, LHe is the cost of fine scotch 
>whisky
>Is a obsessive precision worth a bottle of scotch?
>
>Jim

I work in a lab where LHe is around much of the time. So it's not 
that far of a stretch for me to contemplate using it, although I 
don't personally handle the stuff.

We also have a few obsolete receiver Dewars lying around... one of 
them could be retrofitted to hold a cryogenic standard if we felt 
like it.

But there's the "rent" of regularly buying that LHe to keep the 
standard cold. Kinda like being a drunkard on fine Scotch whisky 
without the buzz.

-- 

--David Forbes, Tucson, AZ
http://www.cathodecorner.com/


From stijena at tapko.de  Mon Dec  1 01:24:39 2008
From: stijena at tapko.de (Predrag Dukic)
Date: Mon, 01 Dec 2008 02:24:39 +0100
Subject: [time-nuts] VRefs - I'm a bigger Voltnut than a timenut..
In-Reply-To: <4932AEB6.30905@freenet.de>
References: <4932AEB6.30905@freenet.de>
Message-ID: <7.0.1.0.1.20081201021258.01e20760@tapko.de>


Obsession for precision is the same whether one is after Hertz, 
Volts, or Degrees of Celsius (Or Fahrenheit).

The methods and technology are similar...

I am now trying to fix two HP2804A quarz thermometers, thet are 
giving some error codes, and do not work.

More or less they are oscillators, and measure of temperature is 
measured by frequency shift  between reference and external oscillator.

Reference frequency is unusual 10.000.000,8 in one of them (marked 
exactly so)  and 10.000.001  in the other.

(Yes, yes, not a typo: it is 10MHz plus 0.8 Hz or plus 1.0 Hz)

So precise temperature and precise frequency cross their ways...


By the way, does anybody have op/serv manual for this thermometer?


Predrag Dukic






At 16:18 30.11.2008, you wrote:
>Hello,
>
>there's currently no easy way to convert a frequency into Volt, i.e.
>other than by cryo Josephson junction array or realizing Ohm by a
>Klitzing quantum hall effect device. Otherwise, FLUKE would have
>implemented that already in their Calibrators/Standards. They still rely
>on Artefact Calibration, i.e. ovenized longterm stable Zener References
>and Reference Resistors.
>
>The 5720A uses a stacked double Zener reference on a proprietary hybrid
>circuitry, giving 1-2 ppm/year stability, the 7001 and 732B use the
>LTZ1000 (Zener above BE junction), as the 3458A, the 732A uses the
>Motorola device (Zener below BE junction), and the elder 332D and 335D
>use similar, but less longterm stable references.
>The LM199, AD587 and I think also the Geller device may only be used as
>transfer standards, having poor longterm stabilities of 20ppm/yr. or more.
>
>Therefore, the LTZ1000 only may serve as a really affordable standard,
>i.e. below 8ppm longterm stability, for private use.
>
>I was lucky to get some LTZ1000 samples, and used the standard circuit
>from the LT datasheet for creating a small PCB. I purchased commercially
>available wire wound resistors (TK 3, 25ppm/yr) for the 5 necessary
>reference resistors and two OP07. Those resistors should give less than
>TK 1 and 1ppm/yr additional drifts.
>
>Compared to my HP34401A, the circuitry showed quite good short term
>stability below 1ppm, but shielding still has to be improved, as the
>LTZ1000 circuit is susceptible to external EMC disturbances. This Volt
>reference then costs less than 100 Euros/Dollars in total.
>
>I designed further circuitry (with TK 0.3 and TK 0.1 precision metal
>foil resistors from Alpha and Vishay, chopper amp, precision switches
>and Teflon insulated wires) to have the possibility for precision
>transfers of the 7,2V reference voltage to 100mV, 1V, 10V, 100V, 1000V
>level.
>Only then, a Volt Standard is complete.
>
>All this stuff will emulate or replace the commonly needed 732A (ref),
>720A (Kelvin Varley), 752A (Reference Divider) and 834B (Null Detector).
>
>Got no time yet to finish and improve the system, and to do the repair
>on an old 332B standard, but would like to share my knowledge, if
>anyone's interested.
>
>Frank Stellmach
>
>_______________________________________________
>time-nuts mailing list -- time-nuts at febo.com
>To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>and follow the instructions there.



From kirbybq at bellsouth.net  Mon Dec  1 01:29:29 2008
From: kirbybq at bellsouth.net (Brian Kirby)
Date: Sun, 30 Nov 2008 19:29:29 -0600
Subject: [time-nuts] Voltage standards
In-Reply-To: <C5586E81.2FF3%James.P.Lux@jpl.nasa.gov>
References: <C5586E81.2FF3%James.P.Lux@jpl.nasa.gov>
Message-ID: <49333DF9.9060804@bellsouth.net>

A cryo may  be hard to put togather  (and maintain - from experience) 
but there are plenty of peltier junctions/devices out there...

Brian KD4FM

Lux, James P wrote:
> Exactly.. I'm sure I'm not the only one on this list that has contemplated home use of liquid helium or even making the stuff.  Hey, if Onnes could do it 100 years ago, so can we.
> 
> I assume the cryogen isn't being used for superconductivity in this case, but for just being cold.  In which case, perhaps LH2 or LN2 would serve almost as well.  The latter, particularly, is pretty manageable (i.e. You don't have to make it yourself).
> 
> Cost wise, I like the snippet I read in Scientific American a decade or so ago.. LN2 is the cost of milk, LHe is the cost of fine scotch whisky
> Is a obsessive precision worth a bottle of scotch?
> 
> Jim
> 
> On 11/30/08 2:13 PM, "M. Warner Losh" <imp at bsdimp.com> wrote:
> 
> In message: <49330CF9.5040205 at xtra.co.nz>
>             Bruce Griffiths <bruce.griffiths at xtra.co.nz> writes:
> : Cryogenic standards arent really feasible for home use as most require
> : liquid helium coolant.
> 
> This has got to be one of the best lines in a time-nuts email :)
> 
> Warner
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
> 


From bruce.griffiths at xtra.co.nz  Mon Dec  1 01:48:25 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Mon, 01 Dec 2008 14:48:25 +1300
Subject: [time-nuts] V refs -- Bruce
In-Reply-To: <20A0DA18-ED7F-4DA5-AE99-F568F001ED79@hughes.net>
References: <mailman.484.1228088343.2542.time-nuts@febo.com>
	<20A0DA18-ED7F-4DA5-AE99-F568F001ED79@hughes.net>
Message-ID: <49334269.6050909@xtra.co.nz>

Richard Moore wrote:
> Bruce, The 714 opamp provides gain in the Datron 1082, and I would  
> use one LTZ1000 (or two in parallel, rather than try to use them in  
> series). A while back I tried using two LM399s in series in a Fluke  
> 895, and really didn't like the results -- a single 399 with an amp  
> was better in every way I could measure. As an alternative to a  
> chopper like the 1151, I might consider an OPA27. I have used the now  
> unobtainable OPA111 in the past, and that was a superb DC amp; they  
> (TI) claim the OPA27 is as good.
>
> Dick Moore
>   
Dick

Replacing the 120 ohm resistor with a PJFET  (source connected to Zener
- Q1 base junction, drain connected to ground) the gate of which is
driven by an opamp to regulate the collector base voltage of Q1 at zero
volts, whilst using the standard zener bootstrap circuit to provide the
zener current can reduce the effect of lead resistance variations by a
factor of 10 or more over the standard LTZ1000 circuit.

Bruce


From warrensjmail-one at yahoo.com  Mon Dec  1 02:28:25 2008
From: warrensjmail-one at yahoo.com (WarrenS)
Date: Sun, 30 Nov 2008 18:28:25 -0800
Subject: [time-nuts] Voltage standards
References: <050701c9525d$dd015ce0$6401a8c0@WSOffice><4931AA86.4090804@xtra.co.nz><4931EBF4.7030700@xtra.co.nz>
	<D489674BFEBB4A77AF5A503AF16A4FA6@cyrus>
Message-ID: <008201c9535c$7daebcb0$6401a8c0@WSOffice>


Bill Hawkins


From bruce.griffiths at xtra.co.nz  Mon Dec  1 03:02:36 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Mon, 01 Dec 2008 16:02:36 +1300
Subject: [time-nuts] Voltage standards
In-Reply-To: <008201c9535c$7daebcb0$6401a8c0@WSOffice>
References: <050701c9525d$dd015ce0$6401a8c0@WSOffice><4931AA86.4090804@xtra.co.nz><4931EBF4.7030700@xtra.co.nz>	<D489674BFEBB4A77AF5A503AF16A4FA6@cyrus>
	<008201c9535c$7daebcb0$6401a8c0@WSOffice>
Message-ID: <493353CC.3090607@xtra.co.nz>

WarrenS wrote:
> Bill Hawkins
>
> >From a theoretical standpoint, Zero Volts is the lower noise limit 
>
> If you want to reduce the measurement noise of a system you need to do one or more of the following:
>
> Lower the source impedance, by reducing the resistance of the thing you are measuring
> Lower the Bandwidth, by filtering over a longer time period
> Lower the temperature, by making it colder.
>
> Doing even any one of these things enough will in theory let the noise approach zero, When you do two (or all three) at once the noise will approach zero sooner.
> see "Johnson-Nyquist noise" for the details
>
> >From a practical standpoint, 1 nV of resolution is doable by comparing the difference between two voltage sources if one uses a lot of care and applies some form of extra filtering. 
> A  1nV  (1e-9) is way below the noise level of any voltage standard that puts out volts.
> This means reference measurements are not limited by the noise level when using a good but simple setup until the references gets to be in the 3e-10 precision range.
>
>   
Modern voltage references are somewhat noisier than standard cells and
batteries (at zero load current).
For the adventurous, recipes for constructing stable Weston standard
cells are readily available.
> The answer to "What can an amateur do to get a good low noise reference for less than, say, $500"
> IS shop at the US eBay site.
>
> WarrenS
>
>   
Bruce


From james.p.lux at jpl.nasa.gov  Mon Dec  1 03:33:58 2008
From: james.p.lux at jpl.nasa.gov (Lux, James P)
Date: Sun, 30 Nov 2008 19:33:58 -0800
Subject: [time-nuts] Voltage standards
In-Reply-To: <49333DF9.9060804@bellsouth.net>
Message-ID: <C5589B26.3005%James.P.Lux@jpl.nasa.gov>




On 11/30/08 5:29 PM, "Brian Kirby" <kirbybq at bellsouth.net> wrote:

> A cryo may  be hard to put togather  (and maintain - from experience)
> but there are plenty of peltier junctions/devices out there...
>
> Brian KD4FM
>
> Lux, James P wrote:
>> Cost wise, I like the snippet I read in Scientific American a decade or so
>> ago.. LN2 is the cost of milk, LHe is the cost of fine scotch whisky
>> Is a obsessive precision worth a bottle of scotch?
>>
>> Jim

Can't get that cold with Peltiers.. Even 77K is a stretch. You run into a
problem with the maximum delta T from one device, and then having to suck up
the heat from that one.  You wind up with a pyramid shaped stack with
terrible efficiency.

The Melcor website has details.



From namichie at gmail.com  Mon Dec  1 04:25:47 2008
From: namichie at gmail.com (Neville Michie)
Date: Mon, 1 Dec 2008 15:25:47 +1100
Subject: [time-nuts] VRefs - I'm a bigger Voltnut than a timenut..
In-Reply-To: <7.0.1.0.1.20081201021258.01e20760@tapko.de>
References: <4932AEB6.30905@freenet.de>
	<7.0.1.0.1.20081201021258.01e20760@tapko.de>
Message-ID: <2E521B94-0111-47BA-B0C7-80E4E308CF6E@gmail.com>

Hi,
Temperature is one quantity that is (or was) determined by physical  
properties of substances.
I have a platinum resistance thermometer, but alone it is useless.
The simplest way of using it is to connect it in 4 wire mode to a HP  
3468A multimeter,
and it measures the resistance with a resolution of about 1mK.
Connect it to another HP 3468A and it varies by less than 1mK.
So the HP 3468A measurement is robust.
Use a widely disseminated formula for the resistance of thermal pure  
platinum
and it seems to measure temperature.
Construct an ice-point cell with a dewar flask, shaved ice, a  
stirring rod and a syphon tube
and we seem to have calibration to better than 10mK.
I then built a hypsometer to boil water in.
The temperature of the steam did not shift 1mK in several hours.
But you have to use a barometer (Fortin pattern) to find the  
atmospheric pressure,
correct for the density of mercury,
correct for the expansion of the scale,
get an estimate for local gravity from
the Geoid, apply an altitude correction.
The result was that a $10 platinum resistance thermometer seems to be  
accurate to 1mK
but the ice-point calibration uncertainty may add plus or minus 5mK.

The big difficulty with temperature measurement is that you need  
circulating thermostat
baths to immerse things in to compare temperatures to any accuracy.  
You only need
one or two of those in your shack to have no room for your time  
standards, voltage standards etc.
cheers, Neville Michie










On 01/12/2008, at 12:24 PM, Predrag Dukic wrote:

>
> Obsession for precision is the same whether one is after Hertz,
> Volts, or Degrees of Celsius (Or Fahrenheit).
>
> The methods and technology are similar...
>
> I am now trying to fix two HP2804A quarz thermometers, thet are
> giving some error codes, and do not work.
>
> More or less they are oscillators, and measure of temperature is
> measured by frequency shift  between reference and external  
> oscillator.
>
> Reference frequency is unusual 10.000.000,8 in one of them (marked
> exactly so)  and 10.000.001  in the other.
>
> (Yes, yes, not a typo: it is 10MHz plus 0.8 Hz or plus 1.0 Hz)
>
> So precise temperature and precise frequency cross their ways...
>
>
> By the way, does anybody have op/serv manual for this thermometer?
>
>
> Predrag Dukic
>
>
>
>
>
>
> At 16:18 30.11.2008, you wrote:
>> Hello,
>>
>> there's currently no easy way to convert a frequency into Volt, i.e.
>> other than by cryo Josephson junction array or realizing Ohm by a
>> Klitzing quantum hall effect device. Otherwise, FLUKE would have
>> implemented that already in their Calibrators/Standards. They  
>> still rely
>> on Artefact Calibration, i.e. ovenized longterm stable Zener  
>> References
>> and Reference Resistors.
>>
>> The 5720A uses a stacked double Zener reference on a proprietary  
>> hybrid
>> circuitry, giving 1-2 ppm/year stability, the 7001 and 732B use the
>> LTZ1000 (Zener above BE junction), as the 3458A, the 732A uses the
>> Motorola device (Zener below BE junction), and the elder 332D and  
>> 335D
>> use similar, but less longterm stable references.
>> The LM199, AD587 and I think also the Geller device may only be  
>> used as
>> transfer standards, having poor longterm stabilities of 20ppm/yr.  
>> or more.
>>
>> Therefore, the LTZ1000 only may serve as a really affordable  
>> standard,
>> i.e. below 8ppm longterm stability, for private use.
>>
>> I was lucky to get some LTZ1000 samples, and used the standard  
>> circuit
>> from the LT datasheet for creating a small PCB. I purchased  
>> commercially
>> available wire wound resistors (TK 3, 25ppm/yr) for the 5 necessary
>> reference resistors and two OP07. Those resistors should give less  
>> than
>> TK 1 and 1ppm/yr additional drifts.
>>
>> Compared to my HP34401A, the circuitry showed quite good short term
>> stability below 1ppm, but shielding still has to be improved, as the
>> LTZ1000 circuit is susceptible to external EMC disturbances. This  
>> Volt
>> reference then costs less than 100 Euros/Dollars in total.
>>
>> I designed further circuitry (with TK 0.3 and TK 0.1 precision metal
>> foil resistors from Alpha and Vishay, chopper amp, precision switches
>> and Teflon insulated wires) to have the possibility for precision
>> transfers of the 7,2V reference voltage to 100mV, 1V, 10V, 100V,  
>> 1000V
>> level.
>> Only then, a Volt Standard is complete.
>>
>> All this stuff will emulate or replace the commonly needed 732A  
>> (ref),
>> 720A (Kelvin Varley), 752A (Reference Divider) and 834B (Null  
>> Detector).
>>
>> Got no time yet to finish and improve the system, and to do the  
>> repair
>> on an old 332B standard, but would like to share my knowledge, if
>> anyone's interested.
>>
>> Frank Stellmach
>>
>> _______________________________________________
>> time-nuts mailing list -- time-nuts at febo.com
>> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/ 
>> listinfo/time-nuts
>> and follow the instructions there.
>
>
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/ 
> time-nuts
> and follow the instructions there.



From technoid_tim at comcast.net  Mon Dec  1 04:43:41 2008
From: technoid_tim at comcast.net (Tim Schulz)
Date: Sun, 30 Nov 2008 21:43:41 -0700
Subject: [time-nuts] My 5062C tale
Message-ID: <49336B7D.1040301@comcast.net>

Greetings, I thought I would update the list on the repair progress on 
my 5062C.  Some of you might recall that I had queried the list several 
months ago for troubleshooting help.  I would like to really thank Corby 
for the troubleshooting tips and Stan for the power supply page scans 
from the service manual.  It turns out that I had a dead ion pump high 
voltage power supply, but it took me a while to get the diagnosis.  I 
had thought it was the 18v power supply card.  This particular unit is a 
Navy 1695A/U badged model with the battery backup and all the optional 
features.  I got it off ebay about a year ago, and had been working 
pretty well for 8 months prior to the failure.  I had made an assumption 
that the 18V regulator card was bad because it looked seriously 
overheated, but the only way to know was to pull the bottom cover and 
probe the motherboard from below.  HP used these damn tinnerman nuts on 
the brackets to secure the sides of the cover and all of my screws were 
over torqued and the threads cut such that there was no way that the 
bottom was coming off without a fight.  In the mean time I won another 
5062C carcass of ebay missing its Cs tube but otherwise powering up and 
putting out signals.  I think that "I'll just swap 18V modules", but 
predictably that doesn't work and I have to drill out rivets holding the 
brackets and eventually figure out that the enabling signal from the ion 
pump power supply is not active.  The carcass has a ion pump power 
supply present, but it too is dead.  These are in little soldered shut, 
deep-drawn cans, so I carefully cut them open with a dremel moto tool 
and cut off wheels.  The innards look like a 17KHz switcher driving a 
pulse engineering transformer module and then a final (I assume) potted 
voltage multiplier.  I think the voltage multiplier is dead.  Anyway, I 
have a 2.5Kv 50ma power supply from an old IR scope tube and I wired 
that up though an old 100uA FS meter movement to the connector of the 
power supply module.  I also jumpered a resistor bridge onto the 18V PS 
enable signal line and reinstalled the module into the 5062C.  I had to 
put a variac on the input to the HV supply because it turned out to be 
too lightly loaded and the voltage was at 6Kv, arcing over to a near by 
cap.  There was an initial pretty high current reading, but it very 
quickly dropped to what looks like close to zero.  I powered the 
standard up and it and would give me a green light, and would stay green 
as long as I was in the shop, but the alarm light comes on and the green 
light goes out overnight.  All of the meter readings seemed to be normal 
for the 1st two days though the 2nd harmonic reading bounces between +25 
and +35 at about a 2hz rate.  Yesterday when I checked on it, the ion 
beam current had crept up past 50, so I turned it down to 30 and made a 
1st attempt to tweek the frequency adjustment.  Can't say that it made 
any difference, still got an alarm on the overnight run. I did find a 
smallish ionizer power supply that is flyback based and runs on 5v in 
the junk box that I was thinking about as a substitute.  The original 
standard says 2.6Kv on the PCB, and the newer model carcass says 3Kv - 
is the ion pump voltage critical?  Also, my Cs tube, PN 05062-60500, has 
an SN of 1516A0596.  I am assuming that its an old tube and that the 
only replacements will come from other machines... I looked at the FTS 
web site, didn't see any indication that they support it.  I was 
wondering what the remaining tube life might be and should I just keep 
the standard powered down most of the time with only the ion pump 
active.  Anyway, thanks again for the help!  tim


From holrum at hotmail.com  Mon Dec  1 06:03:42 2008
From: holrum at hotmail.com (Mark Sims)
Date: Mon, 1 Dec 2008 06:03:42 +0000
Subject: [time-nuts] V standards
In-Reply-To: <mailman.488.1228096118.2542.time-nuts@febo.com>
References: <mailman.488.1228096118.2542.time-nuts@febo.com>
Message-ID: <BLU125-W45AF44DDC86805172CE9DCE010@phx.gbl>


I just snagged a 3457A for $250...  a 3458A would be nice,  but at $4K+ that extra digit is not worth it.   I once (briefly) owned a 3458A.  Got it for REAL cheap on Ebay (seller did not know what it was and mispellified everything in the listing title,  I was the only bidder that found it).  Powered it up,  yep it worked,  sold it the next day to a local cal lab for the proper value...  gotta love illiterate/ignorant sellers.
_________________________________________________________________
Proud to be a PC? Show the world. Download the ?I?m a PC? Messenger themepack now.
hthttp://clk.atdmt.com/MRT/go/119642558/direct/01/

From stephan at rrsg.ee.uct.ac.za  Mon Dec  1 06:57:40 2008
From: stephan at rrsg.ee.uct.ac.za (Stephan Sandenbergh)
Date: Mon, 1 Dec 2008 08:57:40 +0200
Subject: [time-nuts] A better oscillator for the M12+T
Message-ID: <ca708d410811302257i29d9f391ud73a8f696babdd40@mail.gmail.com>

Hi,

What will prevent me from de-soldering the oscillator on the M12+T and feed
it a stable, synthesized version (other words, same frequency as the current
oscillator) of my GPS steered OCXO? (This will be a heavily filtered, low
jitter signal of course) It seems to me I could improve timing performance
by quite a bit, without that much difficulty. I'm aware that the GPS
receiver includes some sort of temperature compensation inside the
controller, but what if I keep it at constant temperature?

I've heard of people trying this with other receivers. The theory says that
a better clock will improve the carrier to noise ratio, and thus also the
GPS measurements. Are there people around here that has tried it before?

Regards,

Stephan.

From richiem at hughes.net  Mon Dec  1 08:04:18 2008
From: richiem at hughes.net (Richard Moore)
Date: Mon, 1 Dec 2008 00:04:18 -0800
Subject: [time-nuts] Thunderbolt settings -- one more time
Message-ID: <D5FDEEAF-75B2-4D19-8268-C8DACDE215E6@hughes.net>

Dear nuts --

Let me see if I can ask this in a way that will prompt you to supply  
some input:

What is the maximum Loop time constant the TBolt (or perhaps the  
TBolt monitor sw) will accept as input?
What TCs are you TBolt owners using?

Thx,
Dick Moore


From cdelect at juno.com  Mon Dec  1 08:07:13 2008
From: cdelect at juno.com (Corby Dawson)
Date: Mon, 1 Dec 2008 00:07:13 -0800
Subject: [time-nuts] thoughts on cesium tube failure modes
Message-ID: <20081201.000841.436.6.cdelect@juno.com>

John,

You can manually de-gas the ionizer and oven filaments.

It looks like you had already brought the oven up to temp so just work on
the ionizer.

You can bring the voltage up slowly and keep watch on the ion pump
current so it does not get too high.

Once you have got it up to the rated voltage and the pump current is low
you can bring up the oven.

You do not need to provide the RF to test and see if the tube has a
response.

Once you have the oven and ionizer up and running and applied a DC
C-field current, 

(I'd have to look up the current you need), the adjustable mass
spectrometer voltage 

(the ionizer supply floats on this), and the -2000VDC EM voltage you can 
apply a 1/2 zeeman frequency

signal to the flop coil and while adjusting the freq and voltage look for
the peak. Once you see it 

adjust the mass spectrometer voltage (max +18VDC) for a peak.

If you see the peaks during this portion you can then remove the 1/2
zeeman frequency signal

and start trying to input some RF.

Good Luck!

Corby
____________________________________________________________
Click here to learn more about nursing jobs.
http://thirdpartyoffers.juno.com/TGL2141/fc/PnY6rw2bVNXskC2QqZapymUmiigw1hCMYMFBPyE8ZaGYNuZa5smqt/


From cdelect at juno.com  Mon Dec  1 08:08:41 2008
From: cdelect at juno.com (Corby Dawson)
Date: Mon, 1 Dec 2008 00:08:41 -0800
Subject: [time-nuts] My 5062C tale
Message-ID: <20081201.000841.436.7.cdelect@juno.com>


Tim,

I do have a schematic of the voltage multiplier block in the 5062C ion
pump supply.  If I 

remember its 3 diodes and 3 caps. If you'd like I'll dig it up for you so
you

can repair your module.  

Corby Dawson
____________________________________________________________
Click here for free information on how to reduce your debt by filing for bankruptcy.
http://thirdpartyoffers.juno.com/TGL2141/fc/PnY6rw22U57D2SvzUwlK0GmNfZKFtn8PpvDpiOEFrvLD2czGP3dKJ/


From phk at phk.freebsd.dk  Mon Dec  1 08:22:01 2008
From: phk at phk.freebsd.dk (Poul-Henning Kamp)
Date: Mon, 01 Dec 2008 08:22:01 +0000
Subject: [time-nuts] Voltage standards
In-Reply-To: Your message of "Sun, 30 Nov 2008 19:29:29 CST."
	<49333DF9.9060804@bellsouth.net> 
Message-ID: <89671.1228119721@critter.freebsd.dk>

In message <49333DF9.9060804 at bellsouth.net>, Brian Kirby writes:

>A cryo may  be hard to put togather  (and maintain - from experience) 
>but there are plenty of peltier junctions/devices out there...

You need LHe for superconductivity and a cryo is damn hard to put
together, if you don't want to spend a lot of money buying LHe.

This is the size of cryo used by the metro labs:

	http://www.ipht-jena.de/photonische-instrumentierung/abteilungen/quantendetektion/anwendungen/voltage-standard.html

-- 
Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk at FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.


From bill at iaxs.net  Mon Dec  1 08:43:47 2008
From: bill at iaxs.net (Bill Hawkins)
Date: Mon, 1 Dec 2008 02:43:47 -0600
Subject: [time-nuts] Voltage standards
In-Reply-To: <49330CF9.5040205@xtra.co.nz>
References: <050701c9525d$dd015ce0$6401a8c0@WSOffice><4931AA86.4090804@xtra.co.nz>	<4931EBF4.7030700@xtra.co.nz><D489674BFEBB4A77AF5A503AF16A4FA6@cyrus>
	<49330CF9.5040205@xtra.co.nz>
Message-ID: <A430C421D03245A582D3E66297BAF542@cyrus>

Bruce,

Thank you for being one of the lowest sources of noise on this list.

Bill Hawkins



From jmiles at pop.net  Mon Dec  1 08:49:22 2008
From: jmiles at pop.net (John Miles)
Date: Mon, 1 Dec 2008 00:49:22 -0800
Subject: [time-nuts] My 5062C tale
In-Reply-To: <20081201.000841.436.7.cdelect@juno.com>
Message-ID: <PKEGJHPHLLBACEOICCBJMEEKPHAB.jmiles@pop.net>

I went ahead and bought the 5062C service manual from Manuals Plus.  I'll
contact Dave at Artek Media next week sometime to see if he's interested in
scanning the whole thing...

-- john, KE5FX


> -----Original Message-----
> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com]On
> Behalf Of Corby Dawson
> Sent: Monday, December 01, 2008 12:09 AM
> To: time-nuts at febo.com
> Cc: time-nuts at febo.com
> Subject: Re: [time-nuts] My 5062C tale
>
>
>
> Tim,
>
> I do have a schematic of the voltage multiplier block in the 5062C ion
> pump supply.  If I
>
> remember its 3 diodes and 3 caps. If you'd like I'll dig it up for you so
> you
>
> can repair your module.
>
> Corby Dawson
> ____________________________________________________________
> Click here for free information on how to reduce your debt by
> filing for bankruptcy.
> http://thirdpartyoffers.juno.com/TGL2141/fc/PnY6rw22U57D2SvzUwlK0G
> mNfZKFtn8PpvDpiOEFrvLD2czGP3dKJ/
>
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>



From jmiles at pop.net  Mon Dec  1 09:03:28 2008
From: jmiles at pop.net (John Miles)
Date: Mon, 1 Dec 2008 01:03:28 -0800
Subject: [time-nuts] thoughts on cesium tube failure modes
In-Reply-To: <20081201.000841.436.6.cdelect@juno.com>
Message-ID: <PKEGJHPHLLBACEOICCBJMEELPHAB.jmiles@pop.net>

Actually your earlier advice proved golden.  I believe I've been able to
verify that the tube is at least within throwing distance of its factory
spec (see test results at http://www.ke5fx.com/cs.htm including the
configuration details).

I haven't tried playing with the low-frequency test coil at all but it
doesn't appear that it'll be necessary to mess with it.  Much appreciate the
help.  Any objection to posting copies of your two emails on the web page?

-- john, KE5FX



> John,
>
> You can manually de-gas the ionizer and oven filaments.
>
> It looks like you had already brought the oven up to temp so just work on
> the ionizer.
>
> You can bring the voltage up slowly and keep watch on the ion pump
> current so it does not get too high.
>
> Once you have got it up to the rated voltage and the pump current is low
> you can bring up the oven.
>
> You do not need to provide the RF to test and see if the tube has a
> response.
>
> Once you have the oven and ionizer up and running and applied a DC
> C-field current,
>
> (I'd have to look up the current you need), the adjustable mass
> spectrometer voltage
>
> (the ionizer supply floats on this), and the -2000VDC EM voltage you can
> apply a 1/2 zeeman frequency
>
> signal to the flop coil and while adjusting the freq and voltage look for
> the peak. Once you see it
>
> adjust the mass spectrometer voltage (max +18VDC) for a peak.
>
> If you see the peaks during this portion you can then remove the 1/2
> zeeman frequency signal
>
> and start trying to input some RF.
>
> Good Luck!
>
> Corby



From XDE-L2G3 at myamail.com  Mon Dec  1 09:58:14 2008
From: XDE-L2G3 at myamail.com (Mike Monett)
Date: Mon, 01 Dec 2008 04:58:14 -0500
Subject: [time-nuts] Voltage standards
References: <mailman.492.1228114664.2542.time-nuts@febo.com>
Message-ID: <mailman.24.1228125527.2539.time-nuts@febo.com>

  Warren wrote:

  > If you  want to reduce the measurement noise of a system  you need
  > to do one or more of the following:

  > Lower the  source  impedance, by reducing  the  resistance  of the
  > thing you are measuring

  > Lower the Bandwidth, by filtering over a longer time period

  > Lower the temperature, by making it colder.

  > Doing even  any one of these things enough will in theory  let the
  > noise approach  zero, When you do two (or all three)  at  once the
  > noise will approach zero sooner.

  > see "Johnson-Nyquist noise" for the details

  >> From a  practical  standpoint, 1 nV of  resolution  is  doable by
  >> comparing the difference between two voltage sources if  one uses
  >> a lot of care and applies some form of extra filtering.

  > A 1nV (1e-9) is way below the noise level of any  voltage standard
  > that puts out volts.

  > This means  reference  measurements are not limited  by  the noise
  > level when using a good but simple setup until the references gets
  > to be in the 3e-10 precision range.

  > The answer  to  "What can an amateur do to get  a  good  low noise
  > reference for less than, say, $500" IS shop at the US eBay site.

  >WarrenS

  The Keithley  Low  Level Measurements Handbook,  Sixth  Edition, has
  some nice graphs that illustrate the limit due to noise. Figure 1-2,
  on page  1-4, shows the theoretical limits  of  voltage measurements
  due to  noise. The next figure, 1-3 on page 1-5,  shows  the typical
  limits of measurement with various source resistances:

  https://www.keithley.com/servlet/Data?id=9538

  The EM  Electronics D.C. Picovoltmeter, Model P12, has  a resolution
  better than 5 picovolts, dependent on response time. From  their web
  page:

  "The noise performance is such that, using a source impedance  of 30
  milliohms or  higher,  the detection level will  be  limited  by the
  Johnson noise of the source. The equivalent noise resistance  of the
  P12 is only 30 milliohms. To put this figure into  perspective, this
  is the  noise  generated by 30cm of 0.5mm diameter  copper  wire! To
  make full  use of the noise performance, it is desirable  to  use it
  with very  low source impedance. While the P12 can be  operated with
  source impedance  of  ten ohms or more, its  characteristic  will be
  overwhelmed by  the  source  noise if the  source  impedance  is too
  high."

  http://www.emelectronics.co.uk/spec/P12.html

  The EM DC Picovoltmeter Model P13 only goes down to 20 picovolts:

  http://www.emelectronics.co.uk/spec/P13.html

  For the  creme de la creme, the Keithley Model 1801  Nanovolt Preamp
  gives 1 picovolt resolution when used with the Model 2001 DMM.

  This extends  the  range by a factor of 1,000, so  the  20 millivolt
  range becomes 20 microvolts. The Model 2001 DMM is 7 1/2  digits, so
  the least significant digit becomes 1 picovolt (1e-12 volts.)  It is
  interesting to  note  the Model 1801  input  connection  uses copper
  nuts.

  From the brochure:

  "The 1801's  chopper-based  design  offers  several  advantages over
  traditional preamps  designed for high-frequency  amplification. For
  example, most DMMs and lock-in amplifiers are designed to filter out
  random noise by averaging."

  "However, low-level  measurements are also subject  to  (1/f) noise,
  which cannot be filtered out in this way. The chopper design cancels
  out (1/f)  noise  completely, which lock-in  preamps  and  most DMMs
  can't. By  continuously  inverting the DC input  and  amplifying the
  resulting AC  waveform,  the 1801's chopper  measures  the  DC input
  amplitude precisely, exclusive of voltage offsets and (1/f) noise in
  the amplifier circuitry. Carefully designed feedback circuitry makes
  the 1801  capable  of rise times as fast as 500us 10  -  90%  and DC
  input resistance  of  up  to  1GOhm.  A  one-eighth-inch-thick steel
  shield and an internal mu-metal shield prevent magnetic  coupling of
  noise to the amplifier."

  http://www.teknetelectronics.com/DataSheet/KEITHLEY/WEBKEITH1801.pdf

  The 1801 web page is at:

  http://www.keithley.com/products/lovoltloresist/?mn=1801

  For those  interested in making your own  nanovoltmeter,  the Analog
  Devices AD8571  offers  Rail-to-Rail Input and Output,  20  pA input
  bias current, 1uV input offset, and 5 nanovolt/C input offset drift:

 
http://www.analog.com/static/imported-files/data_sheets/AD8571_8572_8574.pdf

  Regards,

  Mike Monett


From XDE-L2G3 at myamail.com  Mon Dec  1 10:41:10 2008
From: XDE-L2G3 at myamail.com (Mike Monett)
Date: Mon, 01 Dec 2008 05:41:10 -0500
Subject: [time-nuts] V standards
References: <mailman.466.1228017535.2542.time-nuts@febo.com>
Message-ID: <mailman.25.1228128090.2539.time-nuts@febo.com>

  >Mike

  > In testing  high resolution DACs (20+ bits) used in  GPSDOs  etc a
  > high resolution DVM (or equivalent) with low noise and  good short
  > term stability is useful if not essential.

  > Monotonicity and  perhaps linearity together with good  short term
  > stability are generally more important than absolute accuracy.

  > Higher resolution is usually accompanied with higher accuracy.

  > DVMs like the 3457A. 3456A etc dont have sufficiently low noise or
  > good enough  short  term stability for testing  DACs  with  24 bit
  > resolution.

  >Bruce

  I wonder if 20+ bits is even realistic for a frequency reference.

  That would  give a LSB of 1/2^20=9.53e-7, or 1ppm, and  none  of the
  voltage references  discussed will maintain this accuracy  over long
  periods.

  And what would a 24-bit DAC be used for? From  previous discussions,
  high accuracy sources, like H-Masers are not adjusted. And  it would
  seem silly to put such a high resolution DAC on a OCXO.  That leaves
  Cesium, which  I understand are used in GPS satellites  and  do need
  adjustment, but  I  don't   have   any   information  on  the tuning
  sensitivity to figure the effect 1 LSB would have on the frequency.

  I haven't had much luck finding a true 24-bit DAC. There  are plenty
  of stereo dacs, but they can have gain drifts of 100ppm/C,  which is
  useless for a reference.

  With a  5V reference, a 24-bit DAC would give a LSB  of 5e9/2^24=298
  nanovolts. If  I had to test one, and didn't have a  3458A,  I could
  use a 3456A. It has a resolution of 100nV on the 100mV range,  so it
  could verify the bottom portion of the DAC from zero to  100mV. Once
  the lower  8 bits are confirmed good, the rest of the  DAC  could be
  checked by  exercising each high-order bit singly,  then  in various
  combinations with the other bits.

  Another method  would  be  to use two 24-bit DACs  and  a  AD8571 to
  measure the  difference between them. The AD8571 could be  set  to a
  gain of  100,  so  298nV becomes 29.8uV  which  is  well  within the
  capability of a 3456A.

  The test  would  be  to  set  both  DACs  to  zero  and  measure the
  difference in output voltage. It should be close to zero.

  Next, set  the LSB of the reference DAC to 1. The 3456A  should read
  close to 29.8uV.

  Then set  the LSB of the test DAC to 1. The 3456A should  read close
  to zero.

  Follow this  procedure  with   each   bit   in  turn  to  verify the
  functionality, then  test various combinations to check  for  two or
  more bits  that  are  stuck  together.  The  LSB  could  be  used in
  conjunction with  the  bit being tested  to  prevent  saturating the
  AD8571.

  The above tests are not as good as a dedicated test for  a precision
  DAC, but might serve in lieu of spending $4k to $7k for a 3568A.

  Regards,

  Mike Monett


From bruce.griffiths at xtra.co.nz  Mon Dec  1 11:38:20 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Tue, 02 Dec 2008 00:38:20 +1300
Subject: [time-nuts] V standards
In-Reply-To: <E1L76Da-0006tb-Op@meow.febo.com>
References: <mailman.466.1228017535.2542.time-nuts@febo.com>
	<E1L76Da-0006tb-Op@meow.febo.com>
Message-ID: <4933CCAC.1080808@xtra.co.nz>

Mike
>   >Mike
>
>   > In testing  high resolution DACs (20+ bits) used in  GPSDOs  etc a
>   > high resolution DVM (or equivalent) with low noise and  good short
>   > term stability is useful if not essential.
>
>   > Monotonicity and  perhaps linearity together with good  short term
>   > stability are generally more important than absolute accuracy.
>
>   > Higher resolution is usually accompanied with higher accuracy.
>
>   > DVMs like the 3457A. 3456A etc dont have sufficiently low noise or
>   > good enough  short  term stability for testing  DACs  with  24 bit
>   > resolution.
>
>   >Bruce
>
>   I wonder if 20+ bits is even realistic for a frequency reference.
>
>   That would  give a LSB of 1/2^20=9.53e-7, or 1ppm, and  none  of the
>   voltage references  discussed will maintain this accuracy  over long
>   periods.
>
>   
24 bit resolution isnt required when using a 10811A class OCXO with a
total EFC adjustment range of about 1E-7.
Even 20 bits is a bit more resolution than actually required in this case.
However there are low noise OCXOs with EFC adjustment ranges of 1E-6 or
more.
In a GPSDO long term stability of the EFC DAC offset and gain isnt
critical except when the GPSDO is in holdover.
>   And what would a 24-bit DAC be used for? From  previous discussions,
>   high accuracy sources, like H-Masers are not adjusted. And  it would
>   seem silly to put such a high resolution DAC on a OCXO.  That leaves
>   Cesium, which  I understand are used in GPS satellites  and  do need
>   adjustment, but  I  don't   have   any   information  on  the tuning
>   sensitivity to figure the effect 1 LSB would have on the frequency.
>
>   I haven't had much luck finding a true 24-bit DAC. There  are plenty
>   of stereo dacs, but they can have gain drifts of 100ppm/C,  which is
>   useless for a reference.
>
>   
No you have to build your own.
The trick is doing it without requiring impossibly accurate and stable
resistors or resistor ratios etc.
Since the DAC update rate is relatively slow in such applications
(GPSDO) indirect techniques that are inherently monotonic can be used.
The FS725 rubidium standard has an internal 22 bit DAC.
Hydrogen masers usually include similarly high resolution DACs.
Such DACs are usually constructed by combining the outputs of 2 lower
resolution DACs with some overlap.
The drawback being the relatively large differential nonlinearity when
the MSDAC output changes.
This increases the settling time of the discipling loop in the vicinity
of such changes.
However such MSDAC output changes don't occur very often.
Another application for such high resolution DACs is in accelerator beam
steering.
In this case frequent calibration is used together with suitable
software to avoid such large differential nonlinearities.

>   With a  5V reference, a 24-bit DAC would give a LSB  of 5e9/2^24=298
>   nanovolts. If  I had to test one, and didn't have a  3458A,  I could
>   use a 3456A. It has a resolution of 100nV on the 100mV range,  so it
>   could verify the bottom portion of the DAC from zero to  100mV. Once
>   the lower  8 bits are confirmed good, the rest of the  DAC  could be
>   checked by  exercising each high-order bit singly,  then  in various
>   combinations with the other bits.
>
>   
I had such techniques in mind for checking the monotonicity.
Could also check against a KVD (e.g. Fluke 720A).
However the shipping charges are rather high.
It is possible to achieve a readout resolution of 100nV using a 3457A on
the 3V range.
However this is only available via the GPIB.
Similarly even a 34401A can achieve a resolution of 100nV on the 10V
range but only via either the GPIB or its serial interface.
However the 300nV LSB is uncomfortably close to the DVM noise level and
DVM drift isn't insignificant.
For this application the DAC transfer function only has to be monotonic
so testing requirements are somewhat relaxed.
>   Another method  would  be  to use two 24-bit DACs  and  a  AD8571 to
>   measure the  difference between them. The AD8571 could be  set  to a
>   gain of  100,  so  298nV becomes 29.8uV  which  is  well  within the
>   capability of a 3456A.
>
>   
The LTC1151 is perhaps a better choice in some respects in that it  can
use -15V and +15V supplies allowing a greater input voltage range
simplifying the input overvoltage protection.
Although the AD8571 power supply could be bootstrapped to achieve a much
larger input range.
Even lower drift and noise is possible if one builds one's own chopper
stabilised preamp.
>   The test  would  be  to  set  both  DACs  to  zero  and  measure the
>   difference in output voltage. It should be close to zero.
>
>   Next, set  the LSB of the reference DAC to 1. The 3456A  should read
>   close to 29.8uV.
>
>   Then set  the LSB of the test DAC to 1. The 3456A should  read close
>   to zero.
>
>   Follow this  procedure  with   each   bit   in  turn  to  verify the
>   functionality, then  test various combinations to check  for  two or
>   more bits  that  are  stuck  together.  The  LSB  could  be  used in
>   conjunction with  the  bit being tested  to  prevent  saturating the
>   AD8571.
>
>   The above tests are not as good as a dedicated test for  a precision
>   DAC, but might serve in lieu of spending $4k to $7k for a 3568A.
>
>   Regards,
>
>   Mike Monett
>
>   
Bruce


From didier at cox.net  Mon Dec  1 12:49:35 2008
From: didier at cox.net (Didier)
Date: Mon, 1 Dec 2008 06:49:35 -0600
Subject: [time-nuts] Commercial copies of manuals on the ko4bb.com web site
Message-ID: <F22B2F1B5BF64EC7A77039402175BA61@didierhp>

Manual contributors:
 
It has been brought to my attention that a recently uploaded manual on my
web site was a "cleaned up" copy of an Artek Media scan.
 
I will not get into the legality of doing that, but I have my own policy
regarding commercial scans, and if in doubt, you are invited to check it at:
 
http://www.ko4bb.com/dokuwiki/doku.php?id=test_equipment:my_philosophy_about
_test_equipment_manuals
 
In essence, commercial ventures like Artek Media and others provide a very
valuable service at a reasonable price, and it is our interest that they
stay in business.
Therefore I do not knowingly post manuals that come from such businesses,
and when I am notified of one, I remove it immediately.
 
Thanks to everyone for your support, reflected in the over 18,000 files
(hopefully all of them legitimate) in the current Manuals section of my web
site.
 
Didier KO4BB
 
 

From cfharris at erols.com  Mon Dec  1 14:02:33 2008
From: cfharris at erols.com (Chuck Harris)
Date: Mon, 01 Dec 2008 09:02:33 -0500
Subject: [time-nuts] Thunderbolt settings -- one more time
In-Reply-To: <D5FDEEAF-75B2-4D19-8268-C8DACDE215E6@hughes.net>
References: <D5FDEEAF-75B2-4D19-8268-C8DACDE215E6@hughes.net>
Message-ID: <4933EE79.2070602@erols.com>

Hi Dick,

The T-Bolt is designed to be a turn key system, and is already
set up for the best operation the factory knew how to achieve.
I doubt that anyone has spent much time diddling the time constants.

-Chuck Harris

Richard Moore wrote:
> Dear nuts --
> 
> Let me see if I can ask this in a way that will prompt you to supply  
> some input:
> 
> What is the maximum Loop time constant the TBolt (or perhaps the  
> TBolt monitor sw) will accept as input?
> What TCs are you TBolt owners using?
> 
> Thx,
> Dick Moore
> 
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
> 


From df6jb at ulrich-bangert.de  Mon Dec  1 15:08:44 2008
From: df6jb at ulrich-bangert.de (Ulrich Bangert)
Date: Mon, 1 Dec 2008 16:08:44 +0100
Subject: [time-nuts] Thunderbolt settings -- one more time
In-Reply-To: <4933EE79.2070602@erols.com>
Message-ID: <9A1F1DEC0CA54907B69AB9413680B293@athlon>

Chuck and Dick,

> The T-Bolt is designed to be a turn key system, and is 
> already set up for the best operation the factory knew how to 
> achieve. 

Yes and no! Clearly the factory settings have to be so that a lock of
the pll is possible within a reasonable time, say minutes to hours or
so. With a freshly powered OCXO the initial aging effects can be that
large that really short time constants as the default 100 s of the
Thunderbolt are necessary. 

I attach a measurement that I made on a freshly powered up HP10811 some
years ago. Note: This was by no means a new device but one that had
already thousands of hours lifetime. Clearly any regulation loop will
need short time constants to follow this initial aging. Note that the
aging effects are that big that frequency changes due to diurnal
temperature changes in my flat are not visible! Temperature has
otherwise the biggest impact of all environmental parameters on
oscillator stability.

After some weeks of continuous (!) operation the time constant of the
Thunderbolt loop may be set to higher values. Mine currently runs at
500.0 s. Some tests indicate that the time constant may even be set a
bit higher. I have made experiments on time constants with a number of
different gps receivers and different OCXOs (including RBs). As an
overall result it turned out that TCs > 1500 s are impraticcal in a
normal living environment. With some degrees Centigrade temperature
changes in a typical center European environment along the day that is
the maximum time that allows the loop to follow the temperature changes.
This includes RBs which have an measurable coefficient of temperature
too.

Best regards
Ulrich

> -----Ursprungliche Nachricht-----
> Von: time-nuts-bounces at febo.com 
> [mailto:time-nuts-bounces at febo.com] Im Auftrag von Chuck Harris
> Gesendet: Montag, 1. Dezember 2008 15:03
> An: Discussion of precise time and frequency measurement
> Betreff: Re: [time-nuts] Thunderbolt settings -- one more time
> 
> 
> Hi Dick,
> 
> The T-Bolt is designed to be a turn key system, and is 
> already set up for the best operation the factory knew how to 
> achieve. I doubt that anyone has spent much time diddling the 
> time constants.
> 
> -Chuck Harris
> 
> Richard Moore wrote:
> > Dear nuts --
> > 
> > Let me see if I can ask this in a way that will prompt you to supply
> > some input:
> > 
> > What is the maximum Loop time constant the TBolt (or perhaps the
> > TBolt monitor sw) will accept as input?
> > What TCs are you TBolt owners using?
> > 
> > Thx,
> > Dick Moore
> > 
> > _______________________________________________
> > time-nuts mailing list -- time-nuts at febo.com
> > To unsubscribe, go to 
> > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> > and follow the instructions there.
> > 
> 
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to 
> https://www.febo.com/cgi-> bin/mailman/listinfo/time-nuts
> and 
> follow the instructions there.
> 
-------------- next part --------------
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From holrum at hotmail.com  Mon Dec  1 16:37:56 2008
From: holrum at hotmail.com (Mark Sims)
Date: Mon, 1 Dec 2008 16:37:56 +0000
Subject: [time-nuts] Voltage standards
In-Reply-To: <mailman.507.1228144139.2542.time-nuts@febo.com>
References: <mailman.507.1228144139.2542.time-nuts@febo.com>
Message-ID: <BLU125-W3110EF4BBFABE1A2508807CE010@phx.gbl>


On the subject of precision converters,  how about 24-27 bit mass-to-digital converters?  I have a Mettler AT21 balance that resolves a 20 gram weight to 1 microgram.  Also a Mettler mass comparator that does 100 grams to a microgram.  I also did some work on a balance that (theoretically) measured up to a gram with nanogram resolution (30 bit mass/digital conversion).  At that level it gets hard to separate wishful thinking from reality...
_________________________________________________________________
Windows Live Hotmail now works up to 70% faster.
http://windowslive.com/Explore/Hotmail?ocid=TXT_TAGLM_WL_hotmail_acq_faster_112008

From brad at shinji.net  Mon Dec  1 17:35:03 2008
From: brad at shinji.net (Brad Stockdale)
Date: Mon, 01 Dec 2008 12:35:03 -0500
Subject: [time-nuts] Heathkit GC-1000
Message-ID: <mailman.26.1228152920.2539.time-nuts@febo.com>

Hello all,

    Back 'in the day', when I was about 14 or 15, I went to a local 
computer/technology meeting... This was back around 94 or 95, and 
there was an underground group of computer users in the area that got 
together once a month and traded knowledge, etc... After the meeting, 
I was taken to a friend-of-a-friends house. This guy, named Doc, was 
about 60 years old or so. Lived alone (except for his cat and dog)... 
His 'living room' was nothing short of a combination of a datacenter, 
hamfest, and video editing suite.  Three or four Commodore Amiga's, a 
betacam editing system, a huge front projection TV. Walls lined with 
random equipment. His kitchen table was stacked with computers of 
various vintages...

    In any case, on his mantle sat a Heathkit GC-1000 quietly ticking 
away, sync'd to one of the WWV stations... This was my earliest 
contact with 'accurate time', and is what prompted my fascination 
with it. That little 1 PPS LED made me fall in love...

    For years I had no clue what that clock was. Years later, I 
finally identified the make/model. I looked around online randomly 
over the past decade and never found one... Recently I added 
'Heathkit GC-1000' to my eBay saved searches... Well, today I got an 
email that someone listed one. It appears to be in good working 
order, complete with manuals.

    I bid on it, but was promptly outbid by the original bidder. I 
didn't figure I would get it for what I offered anyway, but I figured 
I would try. No harm in that, right?

    Anyway, I digress. I apologize for the trip down memory lane that 
I subjected you all to... I'll get to my questions...

	1) How prevelant are Heathkit GC-1000's? Are they a common find, or
	   are they fairly rare?

	2) What would be considered a reasonable price for one in working
	   order?

Thanks,
Brad



From gbusg at comcast.net  Mon Dec  1 19:19:20 2008
From: gbusg at comcast.net (Greg Burnett)
Date: Mon, 1 Dec 2008 12:19:20 -0700
Subject: [time-nuts] V standards
References: <mailman.466.1228017535.2542.time-nuts@febo.com>
	<E1L76Da-0006tb-JR@meow.febo.com>
Message-ID: <005901c953e9$b72dfea0$6501a8c0@gb02>

Mike wrote:
--clip--
The above tests are not as good as a dedicated test for  a precision DAC, but might serve in lieu of spending $4k to $7k for a 3458A.
--clip--

---------------------------

The 3458A *is* a nice way to go for DAC testing, though, because of its 0.02ppm differential linearity (which must be verified via a JJ array because Fluke's 720A KVD linearity spec is higher than that).

Greg

From warrensjmail-one at yahoo.com  Mon Dec  1 19:22:42 2008
From: warrensjmail-one at yahoo.com (WarrenS)
Date: Mon, 1 Dec 2008 11:22:42 -0800
Subject: [time-nuts] V standards
References: <mailman.466.1228017535.2542.time-nuts@febo.com><E1L76Da-0006tb-Op@meow.febo.com>
	<4933CCAC.1080808@xtra.co.nz>
Message-ID: <001d01c953ea$2f52ad90$6401a8c0@WSOffice>


Concerning the Need for very high resolution Dacs in GPSDO.

>Bruce said: "However there are low noise OCXOs with EFC adjustment 
>ranges of 1E-6 or more, (that would benefit from >20 bit Dacs)


From gretchendenisebaxter at gmail.com  Mon Dec  1 19:33:41 2008
From: gretchendenisebaxter at gmail.com (Gretchen Baxter)
Date: Mon, 1 Dec 2008 14:33:41 -0500
Subject: [time-nuts] What are the important features to look for in an time
	sync piece of hardware?
Message-ID: <4fdb424f0812011133n35d53470ve208bea9c1e44ce3@mail.gmail.com>

Hi,


What are the important features to look for in an time sync piece of
hardware?

Anyone have a list of the good/required/nice to have features?

thanx!

 Gretchen

From jdb at lartmaker.nl  Mon Dec  1 19:43:34 2008
From: jdb at lartmaker.nl (J.D. Bakker)
Date: Mon, 1 Dec 2008 20:43:34 +0100
Subject: [time-nuts] What are the important features to look for in an
 time sync piece of hardware?
In-Reply-To: <4fdb424f0812011133n35d53470ve208bea9c1e44ce3@mail.gmail.com>
References: <4fdb424f0812011133n35d53470ve208bea9c1e44ce3@mail.gmail.com>
Message-ID: <p0624056bc559ee1b6b6a@[10.1.5.33]>

>What are the important features to look for in an time sync piece of
>hardware?

Does that not depend a lot on your intended application? I would 
expect to look for different things in a one-off time server for a 
lab than if I had a network of cell towers in need of sync.

JDB.
-- 
LART. 250 MIPS under one Watt. Free hardware design files.
http://www.lartmaker.nl/


From gretchendenisebaxter at gmail.com  Mon Dec  1 19:52:36 2008
From: gretchendenisebaxter at gmail.com (Gretchen Baxter)
Date: Mon, 1 Dec 2008 14:52:36 -0500
Subject: [time-nuts] What are the important features to look for in an
	time sync piece of hardware?
In-Reply-To: <p0624056bc559ee1b6b6a@10.1.5.33>
References: <4fdb424f0812011133n35d53470ve208bea9c1e44ce3@mail.gmail.com>
	<p0624056bc559ee1b6b6a@10.1.5.33>
Message-ID: <4fdb424f0812011152i44a4273bh9528c39209e55fcf@mail.gmail.com>

very true!

but looking for a basic feature set.




On Mon, Dec 1, 2008 at 2:43 PM, J.D. Bakker <jdb at lartmaker.nl> wrote:

> >What are the important features to look for in an time sync piece of
> >hardware?
>
> Does that not depend a lot on your intended application? I would
> expect to look for different things in a one-off time server for a
> lab than if I had a network of cell towers in need of sync.
>
> JDB.
> --
> LART. 250 MIPS under one Watt. Free hardware design files.
> http://www.lartmaker.nl/
>
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>

From bill at iaxs.net  Mon Dec  1 20:09:29 2008
From: bill at iaxs.net (Bill Hawkins)
Date: Mon, 1 Dec 2008 14:09:29 -0600
Subject: [time-nuts] What are the important features to look for in an
	timesync piece of hardware?
In-Reply-To: <4fdb424f0812011133n35d53470ve208bea9c1e44ce3@mail.gmail.com>
References: <4fdb424f0812011133n35d53470ve208bea9c1e44ce3@mail.gmail.com>
Message-ID: <D1F5C6CC0B8D49F19C0AC43357C2DAE4@cyrus>

Gretchen Baxter asks,

"What are the important features to look for in an time sync piece of
hardware?"

Here's an 'off the top of my head' list:

1. Cost - If you can't afford it, nothing else matters.

2. Availability - If you can't get it in time for your project, don't
bother.

3. Size and weight - Will it fit where you want to put it? And not
collapse the floor?

4. Power - Do you have enough utility power, with the right voltage and
frequency?

5. External hardware requirements - Can you get antennas, displays,
other stuff?

6. Computer requirements - Do you have an adequate computer with the
right connections?

7. Accuracy and precision - Do they meet project requirements?

8. Reliability and lifetime - Will it be available for the life of the
project?

9. Human interface - If one is needed, is it adequate?

10. Resale value - A consideration if the project life is less than the
equipment life.

Hope that's useful.

Bill Hawkins





From tvb at LeapSecond.com  Mon Dec  1 20:11:53 2008
From: tvb at LeapSecond.com (Tom Van Baak)
Date: Mon, 1 Dec 2008 12:11:53 -0800
Subject: [time-nuts] What are the important features to look for in
	antime sync piece of hardware?
References: <4fdb424f0812011133n35d53470ve208bea9c1e44ce3@mail.gmail.com><p0624056bc559ee1b6b6a@10.1.5.33>
	<4fdb424f0812011152i44a4273bh9528c39209e55fcf@mail.gmail.com>
Message-ID: <590D1F4C6CEE4F239511008B621A2561@pc52>

> but looking for a basic feature set.

But define basic; a stopwatch for timing sports will have a different
feature set from an instrument that times network packets. Telecom
will also have different features, etc.

Also, Gretchen, it would be kind to the group if you tell us who you
work for and why you have been asking these kinds of open-ended
questions for the past few months. You can reply off-line if you wish.

Thanks,
/tvb  tvb at LeapSecond.com




From hmurray at megapathdsl.net  Mon Dec  1 20:12:13 2008
From: hmurray at megapathdsl.net (Hal Murray)
Date: Mon, 01 Dec 2008 12:12:13 -0800
Subject: [time-nuts] V standards
In-Reply-To: Message from "Mike Monett" <XDE-L2G3@myamail.com> 
	of "Mon, 01 Dec 2008 05:41:10 EST." <E1L76Da-0006tb-Iw@meow.febo.com> 
Message-ID: <20081201201214.ACC5CBCD7@ip-64-139-1-69.sjc.megapath.net>


>   I haven't had much luck finding a true 24-bit DAC. There  are plenty
>   of stereo dacs, but they can have gain drifts of 100ppm/C,  which is
>   useless for a reference. 

I've been watching ADCs more than DACs, but I'll bet they follow the same 
pattern.

For ADCs, there seem to be two markets with two sets of features.  One type 
has DC specifications that are interesting for this discussion, things like 
drift and linearity.

The other type focuses on AC specifications.  The typical application is 
audio or radar.  The data sheet usually includes FFT pictures.  Specs include 
things like ENOB, effective number of bits.  (It's usually better at less 
than max frequency.)


-- 
These are my opinions, not necessarily my employer's.  I hate spam.





From gretchendenisebaxter at gmail.com  Mon Dec  1 20:28:23 2008
From: gretchendenisebaxter at gmail.com (Gretchen Baxter)
Date: Mon, 1 Dec 2008 15:28:23 -0500
Subject: [time-nuts] What are the important features to look for in
	antime sync piece of hardware?
In-Reply-To: <590D1F4C6CEE4F239511008B621A2561@pc52>
References: <4fdb424f0812011133n35d53470ve208bea9c1e44ce3@mail.gmail.com>
	<p0624056bc559ee1b6b6a@10.1.5.33>
	<4fdb424f0812011152i44a4273bh9528c39209e55fcf@mail.gmail.com>
	<590D1F4C6CEE4F239511008B621A2561@pc52>
Message-ID: <4fdb424f0812011228k7dc5fa90ude95e20d4a1c5591@mail.gmail.com>

got it.

as for me, just an average ordinary sys admin who has been tasked to do a
lot of these time related functions, in my ever shrinking group.




On Mon, Dec 1, 2008 at 3:11 PM, Tom Van Baak <tvb at leapsecond.com> wrote:

> > but looking for a basic feature set.
>
> But define basic; a stopwatch for timing sports will have a different
> feature set from an instrument that times network packets. Telecom
> will also have different features, etc.
>
> Also, Gretchen, it would be kind to the group if you tell us who you
> work for and why you have been asking these kinds of open-ended
> questions for the past few months. You can reply off-line if you wish.
>
> Thanks,
> /tvb  tvb at LeapSecond.com
>
>
>
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>

From bill at iaxs.net  Mon Dec  1 20:40:02 2008
From: bill at iaxs.net (Bill Hawkins)
Date: Mon, 1 Dec 2008 14:40:02 -0600
Subject: [time-nuts] What are the important features to look for in
	antime sync piece of hardware?
In-Reply-To: <4fdb424f0812011152i44a4273bh9528c39209e55fcf@mail.gmail.com>
References: <4fdb424f0812011133n35d53470ve208bea9c1e44ce3@mail.gmail.com><p0624056bc559ee1b6b6a@10.1.5.33>
	<4fdb424f0812011152i44a4273bh9528c39209e55fcf@mail.gmail.com>
Message-ID: <A6FCFFFF5B654B48AD4125E0FC0DF201@cyrus>

Perhaps you mean those features that are defined by the functionality
of the equipment? As if you were talking to a salesman in a high-end
audio store, or a car salesman?

Are you the person who was asking about time sync requirements for
government regulation agencies?

If so, that narrows the field a bit, but the functionality you need
is still not clear. Different equipment would be needed for power
line frequency regulation, transportation station clocks, broadcast
time signals (voice?), master clock for other regulatory clocks, etc.
Perhaps you want to synchronize time on a network of computers. If so,
how many computers?

Sometimes the features "required" are gathered from magazine articles
written by people who want to sell things by offering the most stuff.

In short, no one is going to be able to help you without knowing the
intended application for your hardware. "Time sync" only differentiates
your hardware from cars and audio-visual hardware, for example.

Is "Plug and Play" a feature?

Bill Hawkins
 

-----Original Message-----
From: Gretchen Baxter

very true!

but looking for a basic feature set.




From richiem at hughes.net  Mon Dec  1 20:59:43 2008
From: richiem at hughes.net (Richard Moore)
Date: Mon, 1 Dec 2008 12:59:43 -0800
Subject: [time-nuts] Thunderbolt settings
In-Reply-To: <mailman.507.1228144139.2542.time-nuts@febo.com>
References: <mailman.507.1228144139.2542.time-nuts@febo.com>
Message-ID: <C0096F46-CD13-40AC-BDFD-0E1D6DC8085C@hughes.net>


On Dec 1, 2008, at 7:08 AM, Chuck and Ulrich  wrote:

> ------------------------------
>
> Message: 2
> Date: Mon, 01 Dec 2008 09:02:33 -0500
> From: Chuck Harris <cfharris at erols.com>
> Subject: Re: [time-nuts] Thunderbolt settings -- one more time
>
> The T-Bolt is designed to be a turn key system, and is already
> set up for the best operation the factory knew how to achieve.
> I doubt that anyone has spent much time diddling the time constants.
>
> -Chuck Harris

Thx, Chuck for your reply.
>
> ------------------------------
>
> Message: 3
> Date: Mon, 1 Dec 2008 16:08:44 +0100
> From: "Ulrich Bangert" <df6jb at ulrich-bangert.de>
> Subject: Re: [time-nuts] Thunderbolt settings -- one more time
>
> Chuck and Dick,
>
>> The T-Bolt is designed to be a turn key system, and is
>> already set up for the best operation the factory knew how to
>> achieve.
>
> Yes and no! Clearly the factory settings have to be so that a lock of
> the pll is possible within a reasonable time, say minutes to hours or
> so. With a freshly powered OCXO the initial aging effects can be that
> large that really short time constants as the default 100 s of the
> Thunderbolt are necessary.
>
> I attach a measurement that I made on a freshly powered up HP10811  
> some
> years ago. Note: This was by no means a new device but one that had
> already thousands of hours lifetime. Clearly any regulation loop will
> need short time constants to follow this initial aging. Note that the
> aging effects are that big that frequency changes due to diurnal
> temperature changes in my flat are not visible! Temperature has
> otherwise the biggest impact of all environmental parameters on
> oscillator stability.
>
> After some weeks of continuous (!) operation the time constant of the
> Thunderbolt loop may be set to higher values. Mine currently runs at
> 500.0 s. Some tests indicate that the time constant may even be set a
> bit higher. I have made experiments on time constants with a number of
> different gps receivers and different OCXOs (including RBs). As an
> overall result it turned out that TCs > 1500 s are impraticcal in a
> normal living environment. With some degrees Centigrade temperature
> changes in a typical center European environment along the day that is
> the maximum time that allows the loop to follow the temperature  
> changes.
> This includes RBs which have an measurable coefficient of temperature
> too.
>
> Best regards
> Ulrich
>
>>
>> Richard Moore wrote:
>>> Dear nuts --
>>>
>>> Let me see if I can ask this in a way that will prompt you to supply
>>> some input:
>>>
>>> What is the maximum Loop time constant the TBolt (or perhaps the
>>> TBolt monitor sw) will accept as input?
>>> What TCs are you TBolt owners using?
>>>
>>> Thx,
>>> Dick Moore
>>>
>>> -------------- next part --------------
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> f7077c5e/attachment.pdf
>
> ------------------------------

Thanks Ulrich. The default TC on my used TBolt was 100.0s. I ran it  
for a couple of days and it was stable with a very low level of total  
DAC change -- about +10mV. After a few more days, and after looking a  
various ADEV plots, particularly yours, Ulrich, I set the TC to  
1000.0 sec. It refuses to take 10,000 sec, but I haven't explored the  
limits of what it will accept, and was hoping, since Trimble won't  
tell me in the docs the acceptable ranges of anything you can adjust,  
that one of you would know.

Dick Moore


From james.p.lux at jpl.nasa.gov  Mon Dec  1 21:11:22 2008
From: james.p.lux at jpl.nasa.gov (Lux, James P)
Date: Mon, 1 Dec 2008 13:11:22 -0800
Subject: [time-nuts] What are the important features to look for
	in	antime sync piece of hardware?
In-Reply-To: <A6FCFFFF5B654B48AD4125E0FC0DF201@cyrus>
References: <4fdb424f0812011133n35d53470ve208bea9c1e44ce3@mail.gmail.com><p0624056bc559ee1b6b6a@10.1.5.33>
	<4fdb424f0812011152i44a4273bh9528c39209e55fcf@mail.gmail.com>
	<A6FCFFFF5B654B48AD4125E0FC0DF201@cyrus>
Message-ID: <ECE7A93BD093E1439C20020FBE87C47FEB55C30CC6@ALTPHYEMBEVSP20.RES.AD.JPL>

> -----Original Message-----
> From: Gretchen Baxter
>
> very true!
>
> but looking for a basic feature set.
>
>

Single most important thing.. Is there an accurate description of what the hardware does, what its performance is, and how that is verified?  That's what separates "real" gear from consumer electronics.

This is my standard comment when review articles in the consumer literature talk about things being "lab grade" (usually implying rugged, expensive, precise, or something else.. Maybe lots of knobs?).. My first question: "Does it have a uncertainty statement?"... You could have a foot ruler (scale, really) with 1/64th inch marks on it, but if it doesn't also say "accurate to X % at Y temperature", it's not lab grade.  On the other hand, you could have a foot long hunk of wood that says (1 foot +/- 1 inch) on it, and that would be "lab grade".. If I measured something with it, I could make a meaningful statement about the precision of my measurement (100,000 ppm, roughly). Granted, it's pretty imprecise, but at least it's known.

Take a "atomic clock" (referring here to the things that receive the 60kHz WWVB signal and set themselves).. The consumer gear (which meets many needs.. I have more than one at home) just says "atomic accuracy" and words like that, and might come with a few paragraphs explaining how to set the time zone.  On the other hand, a professional piece of equipment that does essentially the same thing (has an oscillator and clock inside that is disciplined or set by the WWVB signal) will come with a manual that tells you just how much you can expect it to drift when it doesn't get a signal, over what temperature ranges it will work, how much signal strength it needs to function, etc.

So, rather than comparing the consumer clock to the time displayed on your cell phone to tell if it's working, and going, "yep, looks about right".. You could look at the pro gear and say, it's "16:46 on 1 December 2008 plus or minus 10 seconds" and have reasonable confidence that you "trust" the time to the same accuracy over the next days, weeks, or months, and that if it failed, it might tell you that.


From bruce.griffiths at xtra.co.nz  Mon Dec  1 21:11:47 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Tue, 02 Dec 2008 10:11:47 +1300
Subject: [time-nuts] V standards
In-Reply-To: <001d01c953ea$2f52ad90$6401a8c0@WSOffice>
References: <mailman.466.1228017535.2542.time-nuts@febo.com><E1L76Da-0006tb-Op@meow.febo.com>	<4933CCAC.1080808@xtra.co.nz>
	<001d01c953ea$2f52ad90$6401a8c0@WSOffice>
Message-ID: <49345313.9040209@xtra.co.nz>

WarrenS wrote:
> Concerning the Need for very high resolution Dacs in GPSDO.
>
>   
>> Bruce said: "However there are low noise OCXOs with EFC adjustment 
>> ranges of 1E-6 or more, (that would benefit from >20 bit Dacs)
>>     
>
> >From what I have seen so far,  the higher the accuracy of the OSC 
> used in a GPSDO the LESS there is the need to use a high resolution Dac.
> The FS725 rubidium with it's 2e-9 external EFC range, would not seem 
> to need more than the most simple 12 to 16 bit EXTERNAL tracking Dac. 
> True that its internal Dac needs to have very high resolution if it is used 
> to lock an internal VCXO that has a range of say 1e-6.
>
> Question:  Is the Aging rate of these low noise OCXO units poor enough  
> that you could not use a couple of fixed precision resistor and/or a pot 
> for course adjustment and reduce the EFC range of the DAC by say 1/100 ?. 
> Are there low noise OCXO (that are being used in GPSDO) whose long term 
> drift over say 6 months would need more than 1E-8 or so of  'automatic' turning?
>
> And concerning the 10811A. Should one consider reducing its EFC 
> tuning range by say 2 to 20 to ease the requirements of the Dac? 
> Even if the EFC tuning range was reduced by just a factor of two, 
> It could then be done with just a standard 0 to 5 volt Dac  
> instead of the -5 to +5 that I saw suggested by its spec.
> I would think that a well aged unit would be much better than its worse case 
> spec of 1E-7 per year, And even if not, I'm guessing  that many of the time-nuts, 
> would be very welling to trade off  it needing a have few extra manual adjustments 
> in order to get better performance.
>
> WarrenS
>
>   
Warren

Using a pot plus a relatively low resolution DAC is a classical
technique which can be quite useful if the pot is readily accessible and
one doesn't have too many OCXOs etc to adjust.
Sometimes its cheaper and more convenient to build a high resolution DAC
than use a pot and a conventional DAC.
This is particularly true if the OCXO is inaccessible or at least
relatively inaccessible.

Bruce


From rk at timing-consultants.com  Mon Dec  1 21:19:23 2008
From: rk at timing-consultants.com (Rob Kimberley)
Date: Mon, 1 Dec 2008 21:19:23 -0000
Subject: [time-nuts] What are the important features to look for in
	antime sync piece of hardware?
In-Reply-To: <4fdb424f0812011152i44a4273bh9528c39209e55fcf@mail.gmail.com>
References: <4fdb424f0812011133n35d53470ve208bea9c1e44ce3@mail.gmail.com><p0624056bc559ee1b6b6a@10.1.5.33>
	<4fdb424f0812011152i44a4273bh9528c39209e55fcf@mail.gmail.com>
Message-ID: <335660A0A96347CF9A67BD608CBDFBA8@Robin>

How long is a piece of string?

Rob K 

-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of Gretchen Baxter
Sent: 01 December 2008 19:53
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] What are the important features to look for in
antime sync piece of hardware?

very true!

but looking for a basic feature set.




On Mon, Dec 1, 2008 at 2:43 PM, J.D. Bakker <jdb at lartmaker.nl> wrote:

> >What are the important features to look for in an time sync piece of 
> >hardware?
>
> Does that not depend a lot on your intended application? I would 
> expect to look for different things in a one-off time server for a lab 
> than if I had a network of cell towers in need of sync.
>
> JDB.
> --
> LART. 250 MIPS under one Watt. Free hardware design files.
> http://www.lartmaker.nl/
>
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com To unsubscribe, go to 
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>
_______________________________________________
time-nuts mailing list -- time-nuts at febo.com To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.



From robert8rpi at yahoo.co.uk  Mon Dec  1 21:31:46 2008
From: robert8rpi at yahoo.co.uk (Robert Atkinson)
Date: Mon, 1 Dec 2008 21:31:46 +0000 (GMT)
Subject: [time-nuts] CRYO  Voltage standards
In-Reply-To: <C55873AE.2FF8%James.P.Lux@jpl.nasa.gov>
Message-ID: <1900.22727.qm@web27107.mail.ukl.yahoo.com>

I've played with cryogenically coolled Thermal imagers (yes as a hobby, but work too). and LN2 has a lot going for it. It's cheap and does not wear out (as stirling cycle and peltier coolers do) and is safer than high pressure pure air. That reminds me I've a source for some 24V pure air compressors that were used?for TOW?sights ;-) 
?
Robert G8RPI.????

--- On Mon, 1/12/08, Lux, James P <james.p.lux at jpl.nasa.gov> wrote:

From: Lux, James P <james.p.lux at jpl.nasa.gov>
Subject: Re: [time-nuts] Voltage standards
To: "M. Warner Losh" <imp at bsdimp.com>, "time-nuts at febo.com" <time-nuts at febo.com>
Date: Monday, 1 December, 2008, 12:45 AM



On 11/30/08 4:27 PM, "M. Warner Losh" <imp at bsdimp.com> wrote:

> The thing that got me was the word 'really' in Bruce's
statement.  It
> read like someone who had tried it, had limited success, but in the
> end wound up believing that while possible, it wasn't really
> practical.  After thinking that, I couldn't imagine that somebody on
> the list hadn't tried it for some reason or another over the years.
>
> After all, as you say, a fine bottle of scotch isn't that expensive
> when it comes to the pursuit of your obsessions :)
>
> Warner

And surely, with these grim economic times, liquid helium dewars are going
to be popping up on the surplus market. Then, at least, you'll have a place
to store that liquid helium.

And speaking of cryogens, has anyone on the list done cryogenic sapphire
ring oscillators? (at home)  After all, folks at JPL are doing this
" We present design progress and subsystem test results for a new
short-term
frequency standard, the Voltage Controlled Sapphire Oscillator (VCSO).
Included are sapphire resonator and coupling design, cryocooler
environmental sensitivity tests, Q measurement results, and turnover
temperature results. A previous report presented history of the design
related to resonator frequency and frequency compensation [1]. Performance
goals are a frequency stability of 1?10-14 (1 second ? ? ?100 seconds)
and
two years or more continuous operation. Long-term operation and small size
are facilitated by use of a small Stirling cryo-cooler (160W wall power)
with an expected 5 year life." http://hdl.handle.net/2014/39769

Seems that running a cryocooler is probably a bit easier than pouring liters
of liquid helium into a cryostat.


Jim


_______________________________________________
time-nuts mailing list -- time-nuts at febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.



      

From richiem at hughes.net  Mon Dec  1 21:41:48 2008
From: richiem at hughes.net (Richard Moore)
Date: Mon, 1 Dec 2008 13:41:48 -0800
Subject: [time-nuts] DAC resolution in GPSDO
In-Reply-To: <mailman.510.1228162172.2542.time-nuts@febo.com>
References: <mailman.510.1228162172.2542.time-nuts@febo.com>
Message-ID: <CB89F168-F331-46C4-8894-CF5C21C9372A@hughes.net>


On Dec 1, 2008, at 12:09 PM, Warren wrote:

> Message: 4
> Date: Mon, 1 Dec 2008 11:22:42 -0800
> From: "WarrenS" <warrensjmail-one at yahoo.com>
> Subject: Re: [time-nuts] V standards
>
> Concerning the Need for very high resolution Dacs in GPSDO.
>
>> Bruce said: "However there are low noise OCXOs with EFC adjustment
>> ranges of 1E-6 or more, (that would benefit from >20 bit Dacs)

>> Question:  Is the Aging rate of these low noise OCXO units poor  
>> enough
> that you could not use a couple of fixed precision resistor and/or  
> a pot
> for course adjustment and reduce the EFC range of the DAC by say  
> 1/100 ?.
> Are there low noise OCXO (that are being used in GPSDO) whose long  
> term
> drift over say 6 months would need more than 1E-8 or so of   
> 'automatic' turning?

I'm using an Isotemp 134 OCXO that has an EFC sensitivity of around  
1.62E-6 Hz/V near the 10MHz point. It is very stable and also well- 
aged, and its non-adjustable EFC V for 10MHz is near 3.318V. I'm  
running it in Bert Zauhar's FLL GPSDO, which has a PWM DAC with 14- 
bit resolution and an output range of 0 to +5V. This DAC resolution  
is not enough for tight frequency control of the Isotemp, given its  
very coarse Hz/V sensitivity. Combined with the DAC resolution, the  
system granularity is roughly 4.9E-11 Re 10MHz for it's finest step.  
This just isn't quite enough.

> And concerning the 10811A. Should one consider reducing its EFC
> tuning range by say 2 to 20 to ease the requirements of the Dac?
> Even if the EFC tuning range was reduced by just a factor of two,
> It could then be done with just a standard 0 to 5 volt Dac
> instead of the -5 to +5 that I saw suggested by its spec.
> I would think that a well aged unit would be much better than its  
> worse case
> spec of 1E-7 per year, And even if not, I'm guessing  that many of  
> the time-nuts,
> would be very welling to trade off  it needing a have few extra  
> manual adjustments
> in order to get better performance.
>
> WarrenS

Warren, that's exactly what I'm doing with the Isotemp, aiming for a  
division of about 6-10x. It's no problem for folks like us to tweak  
stuff when needed, so that's an effective solution. I'd like to have  
a higher resolution DAC to preserve a large tuning range, but the  
whole idea of this GPSDO was a simple, inexpensive, yet effective DIY  
GPSDO. See www.moorepage.net/gps2.html

Dick Moore

From n3izn at aol.com  Mon Dec  1 21:59:45 2008
From: n3izn at aol.com (n3izn at aol.com)
Date: Mon, 01 Dec 2008 16:59:45 -0500
Subject: [time-nuts] Wenzel Associates 100 Mhz osc
Message-ID: <8CB2217415E3E1F-AD4-16D6@webmail-dd03.sysops.aol.com>

I stumbled across a 100 Mhz oscillator. It comes from a Harris Constellation RX/TX.

According to the website part number is proprietary. So I thought I would ask here or any info.

Here is what is printed on it from top to bottom.

500-06769D
ISSUE 02
PPD 786-020590-053
100 Mhz
+12 VDC
0105-0201SSRG

It has a SMA female or 100 Mhz out and 4 pins for power and AFC?


From peterawson at earthlink.net  Mon Dec  1 22:18:48 2008
From: peterawson at earthlink.net (Pete)
Date: Mon, 1 Dec 2008 15:18:48 -0700
Subject: [time-nuts] Wenzel Associates 100 Mhz osc
References: <8CB2217415E3E1F-AD4-16D6@webmail-dd03.sysops.aol.com>
Message-ID: <BB4AB002B4FB4D15BC4905DC4ED6FEF1@BASE1>

The 500-xxxx number is a Wenzel custom P/N.
If you give them a call they *might* tell you the
specs on that part.

Pete Rawson


From wje at quackers.net  Mon Dec  1 21:35:13 2008
From: wje at quackers.net (wje)
Date: Mon, 01 Dec 2008 16:35:13 -0500
Subject: [time-nuts] Heathkit GC-1000
In-Reply-To: <E1L7Cg5-00037H-54@meow.febo.com>
References: <E1L7Cg5-00037H-54@meow.febo.com>
Message-ID: <49345891.5050305@quackers.net>

I don't really know how rare they are, but they're reliable.
I have mine that I built many many years ago (20+), and it's still 
ticking. It's been on continuously for all that time.

There's one listed on EBay now, item 160302101690. It's already up to $150.

Bill Ezell
----------
They said 'Windows or better'
so I used Linux.



Brad Stockdale wrote:
> Hello all,
>
>     Back 'in the day', when I was about 14 or 15, I went to a local 
> computer/technology meeting... This was back around 94 or 95, and 
> there was an underground group of computer users in the area that got 
> together once a month and traded knowledge, etc... After the meeting, 
> I was taken to a friend-of-a-friends house. This guy, named Doc, was 
> about 60 years old or so. Lived alone (except for his cat and dog)... 
> His 'living room' was nothing short of a combination of a datacenter, 
> hamfest, and video editing suite.  Three or four Commodore Amiga's, a 
> betacam editing system, a huge front projection TV. Walls lined with 
> random equipment. His kitchen table was stacked with computers of 
> various vintages...
>
>     In any case, on his mantle sat a Heathkit GC-1000 quietly ticking 
> away, sync'd to one of the WWV stations... This was my earliest 
> contact with 'accurate time', and is what prompted my fascination 
> with it. That little 1 PPS LED made me fall in love...
>
>     For years I had no clue what that clock was. Years later, I 
> finally identified the make/model. I looked around online randomly 
> over the past decade and never found one... Recently I added 
> 'Heathkit GC-1000' to my eBay saved searches... Well, today I got an 
> email that someone listed one. It appears to be in good working 
> order, complete with manuals.
>
>     I bid on it, but was promptly outbid by the original bidder. I 
> didn't figure I would get it for what I offered anyway, but I figured 
> I would try. No harm in that, right?
>
>     Anyway, I digress. I apologize for the trip down memory lane that 
> I subjected you all to... I'll get to my questions...
>
> 	1) How prevelant are Heathkit GC-1000's? Are they a common find, or
> 	   are they fairly rare?
>
> 	2) What would be considered a reasonable price for one in working
> 	   order?
>
> Thanks,
> Brad
>
>
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>
>
>   


From stanley_reynolds at yahoo.com  Mon Dec  1 22:31:33 2008
From: stanley_reynolds at yahoo.com (Stanley Reynolds)
Date: Mon, 1 Dec 2008 14:31:33 -0800 (PST)
Subject: [time-nuts] DAC resolution in GPSDO
References: <mailman.510.1228162172.2542.time-nuts@febo.com>
	<CB89F168-F331-46C4-8894-CF5C21C9372A@hughes.net>
Message-ID: <315866.23247.qm@web30306.mail.mud.yahoo.com>


________________________________


On Dec 1, 2008, at 12:09 PM, Warren wrote:

> Message: 4
> Date: Mon, 1 Dec 2008 11:22:42 -0800
> From: "WarrenS" <warrensjmail-one at yahoo.com>
> Subject: Re: [time-nuts] V standards
>
> Concerning the Need for very high resolution Dacs in GPSDO.
>
>> Bruce said: "However there are low noise OCXOs with EFC adjustment
>> ranges of 1E-6 or more, (that would benefit from >20 bit Dacs)

>> Question:? Is the Aging rate of these low noise OCXO units poor? 
>> enough
> that you could not use a couple of fixed precision resistor and/or? 
> a pot
> for course adjustment and reduce the EFC range of the DAC by say? 
> 1/100 ?.
> Are there low noise OCXO (that are being used in GPSDO) whose long? 
> term
> drift over say 6 months would need more than 1E-8 or so of? 
> 'automatic' turning?

I'm using an Isotemp 134 OCXO that has an EFC sensitivity of around? 
1.62E-6 Hz/V near the 10MHz point. It is very stable and also well- 
aged, and its non-adjustable EFC V for 10MHz is near 3.318V. I'm? 
running it in Bert Zauhar's FLL GPSDO, which has a PWM DAC with 14- 
bit resolution and an output range of 0 to +5V. This DAC resolution? 
is not enough for tight frequency control of the Isotemp, given its? 
very coarse Hz/V sensitivity. Combined with the DAC resolution, the? 
system granularity is roughly 4.9E-11 Re 10MHz for it's finest step.? 
This just isn't quite enough.

> And concerning the 10811A. Should one consider reducing its EFC
> tuning range by say 2 to 20 to ease the requirements of the Dac?
> Even if the EFC tuning range was reduced by just a factor of two,
> It could then be done with just a standard 0 to 5 volt Dac
> instead of the -5 to +5 that I saw suggested by its spec.
> I would think that a well aged unit would be much better than its? 
> worse case
> spec of 1E-7 per year, And even if not, I'm guessing? that many of? 
> the time-nuts,
> would be very welling to trade off? it needing a have few extra? 
> manual adjustments
> in order to get better performance.
>
> WarrenS

Warren, that's exactly what I'm doing with the Isotemp, aiming for a? 
division of about 6-10x. It's no problem for folks like us to tweak? 
stuff when needed, so that's an effective solution. I'd like to have? 
a higher resolution DAC to preserve a large tuning range, but the? 
whole idea of this GPSDO was a simple, inexpensive, yet effective DIY? 
GPSDO. See www.moorepage.net/gps2.html

Dick Moore
From: Richard Moore <richiem at hughes.net>
To: time-nuts at febo.com
Sent: Monday, December 1, 2008 3:41:48 PM
Subject: Re: [time-nuts] DAC resolution in GPSDO


The oscillator I think has a manual adjustment. You could be using the 5 volt provided on board or the 8 volt provided by the OCXO for the ECC op amp. Note the ECC voltage is dependent on the control board regulation some what even using an external reference. You may want to manually adjust the OCXO closer to zero and set the upper limit lower as well. By?using a external voltage divider on the ECC voltage or lowering the gain (R7 & R8). 

Bert's site:
" 
Another contributing factor to stability/accuracy is voltage regulation as a function of load current on the +5V regulator. A +5V variation will impact the PWM output amplitude on the PIC micro. It will also impact the offset applied to the operational amplifier to shift the tuning voltage negative in the case where you control a VCXO with a -5V to +5V tuning range.
The single biggest contributor to load variation on the 7805 regulator is change to the 10MHz output terminations. I have seen variations of a few parts in 10-10 when disconnecting instruments form the system. The workaround to this (assuming this variation affects you) is to always put 50 ohm terminations on unused outputs. When adding an instrument, remove the BNC termination and connect the instrument. This will maintain a nominal current consumption on the output driver chip. Obviously, you will want to set the controller so that the outputs are always on. Other current consumers, such as the LED, the input driver and the decade counter do not affect stability in a meaningful manner."
...
"That being said, those of you who operate a tuning voltage from -5V to +5V (and this is the case with the HP oscillators) - should try to center the tuning voltage at or close to 0V. It can be mathematically demonstrated that this is where the effects of the +5V voltage variations cancel out. For applications that require a 0 to +5V tuning voltage, obviously, the closest to 0V, the better."

From slburris at gmail.com  Mon Dec  1 22:33:41 2008
From: slburris at gmail.com (Scott Burris)
Date: Mon, 01 Dec 2008 14:33:41 -0800
Subject: [time-nuts] Heathkit GC-1000
In-Reply-To: <49345891.5050305@quackers.net>
References: <E1L7Cg5-00037H-54@meow.febo.com> <49345891.5050305@quackers.net>
Message-ID: <49346645.40105@gmail.com>

I'll second that.  I built mine when they first came out and it's still 
going strong.  Come to think
of it, pretty much all the Heathkits I build still work today.

Only thing I've done to it is replace the resistor - 5V regulator combo 
with a drop in
switching regulator. See: http://www.amug.org/~jthomas/gc1000.html

It now runs much cooler.

Don't use it for any serious timekeeping though if you have any 
alternatives.  The computer
interface (if it has one) isn't the most accurate.
Scott


wje wrote:
> I don't really know how rare they are, but they're reliable.
> I have mine that I built many many years ago (20+), and it's still 
> ticking. It's been on continuously for all that time.
>
> There's one listed on EBay now, item 160302101690. It's already up to $150.
>
> Bill Ezell
> ----------
> They said 'Windows or better'
> so I used Linux.
>
>
>
> Brad Stockdale wrote:
>   
>> Hello all,
>>
>>     Back 'in the day', when I was about 14 or 15, I went to a local 
>> computer/technology meeting... This was back around 94 or 95, and 
>> there was an underground group of computer users in the area that got 
>> together once a month and traded knowledge, etc... After the meeting, 
>> I was taken to a friend-of-a-friends house. This guy, named Doc, was 
>> about 60 years old or so. Lived alone (except for his cat and dog)... 
>> His 'living room' was nothing short of a combination of a datacenter, 
>> hamfest, and video editing suite.  Three or four Commodore Amiga's, a 
>> betacam editing system, a huge front projection TV. Walls lined with 
>> random equipment. His kitchen table was stacked with computers of 
>> various vintages...
>>
>>     In any case, on his mantle sat a Heathkit GC-1000 quietly ticking 
>> away, sync'd to one of the WWV stations... This was my earliest 
>> contact with 'accurate time', and is what prompted my fascination 
>> with it. That little 1 PPS LED made me fall in love...
>>
>>     For years I had no clue what that clock was. Years later, I 
>> finally identified the make/model. I looked around online randomly 
>> over the past decade and never found one... Recently I added 
>> 'Heathkit GC-1000' to my eBay saved searches... Well, today I got an 
>> email that someone listed one. It appears to be in good working 
>> order, complete with manuals.
>>
>>     I bid on it, but was promptly outbid by the original bidder. I 
>> didn't figure I would get it for what I offered anyway, but I figured 
>> I would try. No harm in that, right?
>>
>>     Anyway, I digress. I apologize for the trip down memory lane that 
>> I subjected you all to... I'll get to my questions...
>>
>> 	1) How prevelant are Heathkit GC-1000's? Are they a common find, or
>> 	   are they fairly rare?
>>
>> 	2) What would be considered a reasonable price for one in working
>> 	   order?
>>
>> Thanks,
>> Brad
>>
>>
>> _______________________________________________
>> time-nuts mailing list -- time-nuts at febo.com
>> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>> and follow the instructions there.
>>
>>
>>   
>>     
>
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>   


From brooke at pacific.net  Mon Dec  1 22:35:48 2008
From: brooke at pacific.net (Brooke Clarke)
Date: Mon, 01 Dec 2008 14:35:48 -0800
Subject: [time-nuts] Heathkit GC-1000
In-Reply-To: <E1L7Cg5-00037H-3p@meow.febo.com>
References: <E1L7Cg5-00037H-3p@meow.febo.com>
Message-ID: <493466C4.7010004@pacific.net>

Hi Brad:

The GC-1000 has an error of some number of hours when displaying DST if you 
don't live in the Colorado time zone twice a year.  For more about it see:
http://www.prc68.com/I/timefreq.shtml#WWV

Have Fun,

Brooke Clarke
http://www.prc68.com

Brad Stockdale wrote:
> Hello all,
> 
>     Back 'in the day', when I was about 14 or 15, I went to a local 
> computer/technology meeting... This was back around 94 or 95, and 
> there was an underground group of computer users in the area that got 
> together once a month and traded knowledge, etc... After the meeting, 
> I was taken to a friend-of-a-friends house. This guy, named Doc, was 
> about 60 years old or so. Lived alone (except for his cat and dog)... 
> His 'living room' was nothing short of a combination of a datacenter, 
> hamfest, and video editing suite.  Three or four Commodore Amiga's, a 
> betacam editing system, a huge front projection TV. Walls lined with 
> random equipment. His kitchen table was stacked with computers of 
> various vintages...
> 
>     In any case, on his mantle sat a Heathkit GC-1000 quietly ticking 
> away, sync'd to one of the WWV stations... This was my earliest 
> contact with 'accurate time', and is what prompted my fascination 
> with it. That little 1 PPS LED made me fall in love...
> 
>     For years I had no clue what that clock was. Years later, I 
> finally identified the make/model. I looked around online randomly 
> over the past decade and never found one... Recently I added 
> 'Heathkit GC-1000' to my eBay saved searches... Well, today I got an 
> email that someone listed one. It appears to be in good working 
> order, complete with manuals.
> 
>     I bid on it, but was promptly outbid by the original bidder. I 
> didn't figure I would get it for what I offered anyway, but I figured 
> I would try. No harm in that, right?
> 
>     Anyway, I digress. I apologize for the trip down memory lane that 
> I subjected you all to... I'll get to my questions...
> 
> 	1) How prevelant are Heathkit GC-1000's? Are they a common find, or
> 	   are they fairly rare?
> 
> 	2) What would be considered a reasonable price for one in working
> 	   order?
> 
> Thanks,
> Brad
> 
> 
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
> 


From james.p.lux at jpl.nasa.gov  Mon Dec  1 22:39:20 2008
From: james.p.lux at jpl.nasa.gov (Lux, James P)
Date: Mon, 1 Dec 2008 14:39:20 -0800
Subject: [time-nuts] Wenzel Associates 100 Mhz osc
In-Reply-To: <8CB2217415E3E1F-AD4-16D6@webmail-dd03.sysops.aol.com>
References: <8CB2217415E3E1F-AD4-16D6@webmail-dd03.sysops.aol.com>
Message-ID: <ECE7A93BD093E1439C20020FBE87C47FEB55C30CF2@ALTPHYEMBEVSP20.RES.AD.JPL>

Just send Wenzel an email and ask them.  Yes, the part # indicates it's a "custom", but they probably can tell you what performance it has.  Not all the pins might be connected (e.g. Wenzel uses a standard package for these things).



James Lux, P.E.
Task Manager, SOMD Software Defined Radios
Flight Communications Systems Section
Jet Propulsion Laboratory
4800 Oak Grove Drive, Mail Stop 161-213
Pasadena, CA, 91109
+1(818)354-2075 phone
+1(818)393-6875 fax

> -----Original Message-----
> From: time-nuts-bounces at febo.com
> [mailto:time-nuts-bounces at febo.com] On Behalf Of n3izn at aol.com
> Sent: Monday, December 01, 2008 2:00 PM
> To: time-nuts at febo.com
> Subject: [time-nuts] Wenzel Associates 100 Mhz osc
>
> I stumbled across a 100 Mhz oscillator. It comes from a
> Harris Constellation RX/TX.
>
> According to the website part number is proprietary. So I
> thought I would ask here or any info.
>
> Here is what is printed on it from top to bottom.
>
> 500-06769D
> ISSUE 02
> PPD 786-020590-053
> 100 Mhz
> +12 VDC
> 0105-0201SSRG
>
> It has a SMA female or 100 Mhz out and 4 pins for power and AFC?
>
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com To unsubscribe,
> go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>


From bruce.griffiths at xtra.co.nz  Mon Dec  1 22:41:34 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Tue, 02 Dec 2008 11:41:34 +1300
Subject: [time-nuts] DAC resolution in GPSDO
In-Reply-To: <315866.23247.qm@web30306.mail.mud.yahoo.com>
References: <mailman.510.1228162172.2542.time-nuts@febo.com>	<CB89F168-F331-46C4-8894-CF5C21C9372A@hughes.net>
	<315866.23247.qm@web30306.mail.mud.yahoo.com>
Message-ID: <4934681E.1000501@xtra.co.nz>

Stanley Reynolds wrote:
> ________________________________
>
>
> On Dec 1, 2008, at 12:09 PM, Warren wrote:
>
>   
>> Message: 4
>> Date: Mon, 1 Dec 2008 11:22:42 -0800
>> From: "WarrenS" <warrensjmail-one at yahoo.com>
>> Subject: Re: [time-nuts] V standards
>>
>> Concerning the Need for very high resolution Dacs in GPSDO.
>>
>>     
>>> Bruce said: "However there are low noise OCXOs with EFC adjustment
>>> ranges of 1E-6 or more, (that would benefit from >20 bit Dacs)
>>>       
>
>   
>>> Question:  Is the Aging rate of these low noise OCXO units poor  
>>> enough
>>>       
>> that you could not use a couple of fixed precision resistor and/or  
>> a pot
>> for course adjustment and reduce the EFC range of the DAC by say  
>> 1/100 ?.
>> Are there low noise OCXO (that are being used in GPSDO) whose long  
>> term
>> drift over say 6 months would need more than 1E-8 or so of  
>> 'automatic' turning?
>>     
>
> I'm using an Isotemp 134 OCXO that has an EFC sensitivity of around  
> 1.62E-6 Hz/V near the 10MHz point. It is very stable and also well- 
> aged, and its non-adjustable EFC V for 10MHz is near 3.318V. I'm  
> running it in Bert Zauhar's FLL GPSDO, which has a PWM DAC with 14- 
> bit resolution and an output range of 0 to +5V. This DAC resolution  
> is not enough for tight frequency control of the Isotemp, given its  
> very coarse Hz/V sensitivity. Combined with the DAC resolution, the  
> system granularity is roughly 4.9E-11 Re 10MHz for it's finest step.  
> This just isn't quite enough.
>
>   
>> And concerning the 10811A. Should one consider reducing its EFC
>> tuning range by say 2 to 20 to ease the requirements of the Dac?
>> Even if the EFC tuning range was reduced by just a factor of two,
>> It could then be done with just a standard 0 to 5 volt Dac
>> instead of the -5 to +5 that I saw suggested by its spec.
>> I would think that a well aged unit would be much better than its  
>> worse case
>> spec of 1E-7 per year, And even if not, I'm guessing  that many of  
>> the time-nuts,
>> would be very welling to trade off  it needing a have few extra  
>> manual adjustments
>> in order to get better performance.
>>
>> WarrenS
>>     
>
> Warren, that's exactly what I'm doing with the Isotemp, aiming for a  
> division of about 6-10x. It's no problem for folks like us to tweak  
> stuff when needed, so that's an effective solution. I'd like to have  
> a higher resolution DAC to preserve a large tuning range, but the  
> whole idea of this GPSDO was a simple, inexpensive, yet effective DIY  
> GPSDO. See www.moorepage.net/gps2.html
>
> Dick Moore
> From: Richard Moore <richiem at hughes.net>
> To: time-nuts at febo.com
> Sent: Monday, December 1, 2008 3:41:48 PM
> Subject: Re: [time-nuts] DAC resolution in GPSDO
>
>
> The oscillator I think has a manual adjustment. You could be using the 5 volt provided on board or the 8 volt provided by the OCXO for the ECC op amp. Note the ECC voltage is dependent on the control board regulation some what even using an external reference. You may want to manually adjust the OCXO closer to zero and set the upper limit lower as well. By using a external voltage divider on the ECC voltage or lowering the gain (R7 & R8). 
>
> Bert's site:
> " 
> Another contributing factor to stability/accuracy is voltage regulation as a function of load current on the +5V regulator. A +5V variation will impact the PWM output amplitude on the PIC micro. It will also impact the offset applied to the operational amplifier to shift the tuning voltage negative in the case where you control a VCXO with a -5V to +5V tuning range.
> The single biggest contributor to load variation on the 7805 regulator is change to the 10MHz output terminations. I have seen variations of a few parts in 10-10 when disconnecting instruments form the system. The workaround to this (assuming this variation affects you) is to always put 50 ohm terminations on unused outputs. When adding an instrument, remove the BNC termination and connect the instrument. This will maintain a nominal current consumption on the output driver chip. Obviously, you will want to set the controller so that the outputs are always on. Other current consumers, such as the LED, the input driver and the decade counter do not affect stability in a meaningful manner."
> ...
> "That being said, those of you who operate a tuning voltage from -5V to +5V (and this is the case with the HP oscillators) - should try to center the tuning voltage at or close to 0V. It can be mathematically demonstrated that this is where the effects of the +5V voltage variations cancel out. For applications that require a 0 to +5V tuning voltage, obviously, the closest to 0V, the better."
> _______________________________________________
>   
Its far better to use the PWM output to drive a fast SPDT analog
switch(eg 1/3 of a 74HC4053) that switches between a precision reference
and ground and low pass filter the SPDT switch output.
Alternatively one can power the micro from a precision reference based
low noise regulator.

Bruce


From steve at borisone.demon.co.uk  Mon Dec  1 22:47:53 2008
From: steve at borisone.demon.co.uk (S J Roberts)
Date: Mon, 1 Dec 2008 22:47:53 -0000
Subject: [time-nuts] help identifying connections of marconi oscillator
Message-ID: <FFD5C8F397AE4A5AA7AF56D84CCDA239@vistalaptop2>



Greetings all,

I have recently purchased what looks like an unused crystal oscillator from the ubiquitous ebay.
marconi crystal oscillator
identity : FQ-3121-11
Freq : 4960khz
Serial no : H14730
Temp range: -10 to +55
Operating voltage 20vdc

cylindrical approx 10cm x 5cm
0.75cm coarse(?) screw flush with top
weight  approx 500g
spring mounted fine(?) adjustment screw central top - allowing adjustment once pushed down
hermetically sealed case 
valve type connector on base with 8 connectors - wires are threaded through 10mm x 2mm tubes
colour coding yellow/yellow/blue/green/yellow/yellow/red/white

Apologies for the long description

Does anyone know what the connections might be?
Seems a shame to dremel open the case yet...

I have attached a pic if that helps

Cheers

Steve Roberts
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From richiem at hughes.net  Mon Dec  1 22:53:23 2008
From: richiem at hughes.net (Richard Moore)
Date: Mon, 1 Dec 2008 14:53:23 -0800
Subject: [time-nuts] time-nuts Digest, Vol 53, Issue 8
In-Reply-To: <mailman.515.1228170831.2542.time-nuts@febo.com>
References: <mailman.515.1228170831.2542.time-nuts@febo.com>
Message-ID: <EB528D92-72A0-43B4-82AA-C068746F584B@hughes.net>

On Dec 1, 2008, at 2:33 PM, Stanley Reynolds wrote:

> Message: 6
> Date: Mon, 1 Dec 2008 14:31:33 -0800 (PST)
> From: Stanley Reynolds <stanley_reynolds at yahoo.com>
> Subject: Re: [time-nuts] DAC resolution in GPSDO
>
> The oscillator I think has a manual adjustment. You could be using  
> the 5 volt provided on board or the 8 volt provided by the OCXO for  
> the ECC op amp. Note the ECC voltage is dependent on the control  
> board regulation some what even using an external reference. You  
> may want to manually adjust the OCXO closer to zero and set the  
> upper limit lower as well. By?using a external voltage divider on  
> the ECC voltage or lowering the gain (R7 & R8).

Nope, this Isotemp was made for OFC, labeled OSC092, or maybe OFC/ 
McCoy sold out to Isotemp. There's no external adjustment available.  
I used a 78L05 to make the +8V reference supply for the OCXO and it  
works quite well. I don't use the BertBoard's signal output chip at  
all, nor the RS-232 chip, so loading hasn't been a problem. Compared  
to my recently purchased Thunderbolt, running off the same antenna,  
the Zauhar GPSDO moves around by a few parts in 10E-10 to 10E-11.  
Using the +8V ref supply to make a larger range of DAC output makes  
the problem worse, not better. A 16-bit DAC would help, but this  
project has gotten more complicated than I wanted already -- see my  
webpage. The best solution now would be a good 10811A...

Dick Moore


From danrae at verizon.net  Mon Dec  1 22:55:25 2008
From: danrae at verizon.net (Dan Rae)
Date: Mon, 01 Dec 2008 14:55:25 -0800
Subject: [time-nuts] Wenzel Associates 100 Mhz osc
In-Reply-To: <ECE7A93BD093E1439C20020FBE87C47FEB55C30CF2@ALTPHYEMBEVSP20.RES.AD.JPL>
References: <8CB2217415E3E1F-AD4-16D6@webmail-dd03.sysops.aol.com>
	<ECE7A93BD093E1439C20020FBE87C47FEB55C30CF2@ALTPHYEMBEVSP20.RES.AD.JPL>
Message-ID: <49346B5D.8010007@verizon.net>

Lux, James P wrote:
> Just send Wenzel an email and ask them.  
James, they might answer you with your email address, but when I 
e-mailed them, several times, to ask the price of one of the OCXOs they 
advertised as being in stock, I never got an answer...  I suspect they 
have anti individual time nut spam filters :^(

What I did when faced with one of their custom 10 MHz ovens, was to find 
the stock model that it most resembled, and then a bit of Ohmmeter 
measuring confirmed that it indeed had the same pin out.  This may not 
be possible if it is an older one of course. 

Good luck!

Dan




From warrensjmail-one at yahoo.com  Mon Dec  1 22:58:40 2008
From: warrensjmail-one at yahoo.com (WarrenS)
Date: Mon, 1 Dec 2008 14:58:40 -0800
Subject: [time-nuts] V standards
Message-ID: <012401c95408$5abeb910$6401a8c0@WSOffice>


>Bruce Wrote: 
> "Sometimes its cheaper and more convenient to build  a high 
> resolution DAC than use a pot and a conventional DAC. ...

Very true, And don't forget also more fun, more challenging, and more better!
which all very import  requirements in this field, maybe more so than performance.

Assuming  100 to 1000 seconds are the typical max tracking times 
practical in the standard GPSDO's due to temperature changes, 
initial aging, etc  as stated by Ulrich in the posting  
http://www.febo.com/pipermail/time-nuts/2008-December/034823.html 
and IF IE-10 is the best you get from the GPS signal in these same 
time averages as stated on Page #3 of  
http://www.thinksrs.com/downloads/PDFs/Catalog/PRS10c.pdf

Doesn't this imply that a Dac with more than about 12 bits becomes 
an overkill at 100 seconds tracking when using a 1E-7 turning range OSC, 
and around 18 bits for the same Osc when tracking at 1000 Sec? 

WarrenS
**********************
WarrenS wrote:
> Concerning the Need for very high resolution Dacs in GPSDO.
>
>   
>> Bruce said: "However there are low noise OCXOs with EFC adjustment 
>> ranges of 1E-6 or more, (that would benefit from >20 bit Dacs)
>>     
>
> >From what I have seen so far,  the higher the accuracy of the OSC 
> used in a GPSDO the LESS there is the need to use a high resolution Dac.
> The FS725 rubidium with it's 2e-9 external EFC range, would not seem 
> to need more than the most simple 12 to 16 bit EXTERNAL tracking Dac. 
> True that its internal Dac needs to have very high resolution if it is used 
> to lock an internal VCXO that has a range of say 1e-6.
>
> Question:  Is the Aging rate of these low noise OCXO units poor enough  
> that you could not use a couple of fixed precision resistor and/or a pot 
> for course adjustment and reduce the EFC range of the DAC by say 1/100 ?. 
> Are there low noise OCXO (that are being used in GPSDO) whose long term 
> drift over say 6 months would need more than 1E-8 or so of  'automatic' turning?
>
> And concerning the 10811A. Should one consider reducing its EFC 
> tuning range by say 2 to 20 to ease the requirements of the Dac? 
> Even if the EFC tuning range was reduced by just a factor of two, 
> It could then be done with just a standard 0 to 5 volt Dac  
> instead of the -5 to +5 that I saw suggested by its spec.
> I would think that a well aged unit would be much better than its worse case 
> spec of 1E-7 per year, And even if not, I'm guessing  that many of the time-nuts, 
> would be very welling to trade off  it needing a have few extra manual adjustments 
> in order to get better performance.
>
> WarrenS
>
>   
Warren

Using a pot plus a relatively low resolution DAC is a classical
technique which can be quite useful if the pot is readily accessible and
one doesn't have too many OCXOs etc to adjust.
Sometimes its cheaper and more convenient to build a high resolution DAC
than use a pot and a conventional DAC.
This is particularly true if the OCXO is inaccessible or at least
relatively inaccessible.

Bruce

From wa9msd at ggnet.net  Mon Dec  1 23:12:18 2008
From: wa9msd at ggnet.net (Joseph Grossbauer)
Date: Mon, 1 Dec 2008 17:12:18 -0600
Subject: [time-nuts] Heathkit GC-1000
In-Reply-To: <493466C4.7010004@pacific.net>
Message-ID: <00B9EFFFA17843F3BF2B7A272B0D9355@joesworkstation>

I don't think these are too rare.  When I was in the market for one I did a
saved search on eBay and over the course of 3-6 months I picked a couple of
them.  They ran about $250 each in overall very good condition.  Both worked
"out of the box" but I recently had them aligned and some caps replaced.

Joe

-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of Brooke Clarke
Sent: Monday, December 01, 2008 16:36
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Heathkit GC-1000

Hi Brad:

The GC-1000 has an error of some number of hours when displaying DST if you 
don't live in the Colorado time zone twice a year.  For more about it see:
http://www.prc68.com/I/timefreq.shtml#WWV

Have Fun,

Brooke Clarke
http://www.prc68.com

Brad Stockdale wrote:
> Hello all,
> 
>     Back 'in the day', when I was about 14 or 15, I went to a local 
> computer/technology meeting... This was back around 94 or 95, and 
> there was an underground group of computer users in the area that got 
> together once a month and traded knowledge, etc... After the meeting, 
> I was taken to a friend-of-a-friends house. This guy, named Doc, was 
> about 60 years old or so. Lived alone (except for his cat and dog)... 
> His 'living room' was nothing short of a combination of a datacenter, 
> hamfest, and video editing suite.  Three or four Commodore Amiga's, a 
> betacam editing system, a huge front projection TV. Walls lined with 
> random equipment. His kitchen table was stacked with computers of 
> various vintages...
> 
>     In any case, on his mantle sat a Heathkit GC-1000 quietly ticking 
> away, sync'd to one of the WWV stations... This was my earliest 
> contact with 'accurate time', and is what prompted my fascination 
> with it. That little 1 PPS LED made me fall in love...
> 
>     For years I had no clue what that clock was. Years later, I 
> finally identified the make/model. I looked around online randomly 
> over the past decade and never found one... Recently I added 
> 'Heathkit GC-1000' to my eBay saved searches... Well, today I got an 
> email that someone listed one. It appears to be in good working 
> order, complete with manuals.
> 
>     I bid on it, but was promptly outbid by the original bidder. I 
> didn't figure I would get it for what I offered anyway, but I figured 
> I would try. No harm in that, right?
> 
>     Anyway, I digress. I apologize for the trip down memory lane that 
> I subjected you all to... I'll get to my questions...
> 
> 	1) How prevelant are Heathkit GC-1000's? Are they a common find, or
> 	   are they fairly rare?
> 
> 	2) What would be considered a reasonable price for one in working
> 	   order?
> 
> Thanks,
> Brad
> 
> 
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
> 

_______________________________________________
time-nuts mailing list -- time-nuts at febo.com
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.



From bruce.griffiths at xtra.co.nz  Mon Dec  1 23:15:26 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Tue, 02 Dec 2008 12:15:26 +1300
Subject: [time-nuts] V standards
In-Reply-To: <012401c95408$5abeb910$6401a8c0@WSOffice>
References: <012401c95408$5abeb910$6401a8c0@WSOffice>
Message-ID: <4934700E.4090308@xtra.co.nz>

WarrenS wrote:
>> Bruce Wrote: 
>> "Sometimes its cheaper and more convenient to build  a high 
>> resolution DAC than use a pot and a conventional DAC. ...
>>     
>
> Very true, And don't forget also more fun, more challenging, and more better!
> which all very import  requirements in this field, maybe more so than performance.
>
> Assuming  100 to 1000 seconds are the typical max tracking times 
> practical in the standard GPSDO's due to temperature changes, 
> initial aging, etc  as stated by Ulrich in the posting  
> http://www.febo.com/pipermail/time-nuts/2008-December/034823.html 
> and IF IE-10 is the best you get from the GPS signal in these same 
> time averages as stated on Page #3 of  
> http://www.thinksrs.com/downloads/PDFs/Catalog/PRS10c.pdf
>
> Doesn't this imply that a Dac with more than about 12 bits becomes 
> an overkill at 100 seconds tracking when using a 1E-7 turning range OSC, 
> and around 18 bits for the same Osc when tracking at 1000 Sec? 
>
> WarrenS
> **********************
>   
Warren

In principle, but this precludes such improvements as correcting for
ambient temperature variations in software etc., without upgrading the
DAC resolution.
Also (as many have discovered) when one is testing various oscillators
of unknown performance its very convenient to have somewhat more EFC DAC
resolution than 12bits or even 14bits.
it is also useful to have a relatively stable low noise reference for
the high resolution DAC.

Also a low resolution DAC precludes (or at least makes more difficult)
using carrier phase disciplining techniques which can have around 2
orders less noise than PPS tracking GPSDOs.
A relatively inexpensive 20 bit DAC can make such experimentation much
easier.


Bruce


From stanley_reynolds at yahoo.com  Mon Dec  1 23:16:55 2008
From: stanley_reynolds at yahoo.com (Stanley Reynolds)
Date: Mon, 1 Dec 2008 15:16:55 -0800 (PST)
Subject: [time-nuts] time-nuts Digest, Vol 53, Issue 8
References: <mailman.515.1228170831.2542.time-nuts@febo.com>
	<EB528D92-72A0-43B4-82AA-C068746F584B@hughes.net>
Message-ID: <706776.57600.qm@web30306.mail.mud.yahoo.com>





________________________________

From: Richard Moore <richiem at hughes.net>
To: time-nuts at febo.com
Sent: Monday, December 1, 2008 4:53:23 PM
Subject: Re: [time-nuts] time-nuts Digest, Vol 53, Issue 8


Yes my suggestion was to reduce the range not increase it. I was not sure if you were using the 8 volt reference inside the OCXO or the on board 5V now or as you say an external 8 volts. In any case using a lower reference voltage does decrease the range and?step size. With no way to adjust the 10Mhz voltage point you could raise the lower limit by modifying the op amp to offset above ground. If using Bruce's suggestion then switch between two different positive regulated voltages and not regulated and ground with the analog switch.

I have several 10811's just don't know how good they are yet ... 

_______________________________________________
time-nuts mailing list -- time-nuts at febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

On Dec 1, 2008, at 2:33 PM, Stanley Reynolds wrote:

> Message: 6
> Date: Mon, 1 Dec 2008 14:31:33 -0800 (PST)
> From: Stanley Reynolds <stanley_reynolds at yahoo.com>
> Subject: Re: [time-nuts] DAC resolution in GPSDO
>
> The oscillator I think has a manual adjustment. You could be using? 
> the 5 volt provided on board or the 8 volt provided by the OCXO for? 
> the ECC op amp. Note the ECC voltage is dependent on the control? 
> board regulation some what even using an external reference. You? 
> may want to manually adjust the OCXO closer to zero and set the? 
> upper limit lower as well. By?using a external voltage divider on? 
> the ECC voltage or lowering the gain (R7 & R8).

Nope, this Isotemp was made for OFC, labeled OSC092, or maybe OFC/ 
McCoy sold out to Isotemp. There's no external adjustment available.? 
I used a 78L05 to make the +8V reference supply for the OCXO and it? 
works quite well. I don't use the BertBoard's signal output chip at? 
all, nor the RS-232 chip, so loading hasn't been a problem. Compared? 
to my recently purchased Thunderbolt, running off the same antenna,? 
the Zauhar GPSDO moves around by a few parts in 10E-10 to 10E-11.? 
Using the +8V ref supply to make a larger range of DAC output makes? 
the problem worse, not better. A 16-bit DAC would help, but this? 
project has gotten more complicated than I wanted already -- see my? 
webpage. The best solution now would be a good 10811A...

Dick Moore

From james.p.lux at jpl.nasa.gov  Mon Dec  1 23:24:54 2008
From: james.p.lux at jpl.nasa.gov (Lux, James P)
Date: Mon, 1 Dec 2008 15:24:54 -0800
Subject: [time-nuts] Wenzel Associates 100 Mhz osc
In-Reply-To: <49346B5D.8010007@verizon.net>
References: <8CB2217415E3E1F-AD4-16D6@webmail-dd03.sysops.aol.com>
	<ECE7A93BD093E1439C20020FBE87C47FEB55C30CF2@ALTPHYEMBEVSP20.RES.AD.JPL>
	<49346B5D.8010007@verizon.net>
Message-ID: <ECE7A93BD093E1439C20020FBE87C47FEB55C30D0A@ALTPHYEMBEVSP20.RES.AD.JPL>



> -----Original Message-----
> From: time-nuts-bounces at febo.com
> [mailto:time-nuts-bounces at febo.com] On Behalf Of Dan Rae
> Sent: Monday, December 01, 2008 2:55 PM
> To: Discussion of precise time and frequency measurement
> Subject: Re: [time-nuts] Wenzel Associates 100 Mhz osc
>
> Lux, James P wrote:
> > Just send Wenzel an email and ask them.
> James, they might answer you with your email address, but
> when I e-mailed them, several times, to ask the price of one
> of the OCXOs they advertised as being in stock, I never got
> an answer...  I suspect they have anti individual time nut
> spam filters :^(
>



More likely, since they're not a huge company, they get busy and forget.  Calling them on the phone is also a possibility.  Yes, they're in Texas, which is kind of like making a foreign phone call, but they're in Austin, and Austin *is* different. (At least so my Texan cousins tell me).

Jim


From bruce.griffiths at xtra.co.nz  Mon Dec  1 23:26:38 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Tue, 02 Dec 2008 12:26:38 +1300
Subject: [time-nuts] time-nuts Digest, Vol 53, Issue 8
In-Reply-To: <706776.57600.qm@web30306.mail.mud.yahoo.com>
References: <mailman.515.1228170831.2542.time-nuts@febo.com>	<EB528D92-72A0-43B4-82AA-C068746F584B@hughes.net>
	<706776.57600.qm@web30306.mail.mud.yahoo.com>
Message-ID: <493472AE.4050807@xtra.co.nz>

Stanley Reynolds wrote:
> From: Richard Moore <richiem at hughes.net>
> To: time-nuts at febo.com
> Sent: Monday, December 1, 2008 4:53:23 PM
> Subject: Re: [time-nuts] time-nuts Digest, Vol 53, Issue 8
>
>
> Yes my suggestion was to reduce the range not increase it. I was not sure if you were using the 8 volt reference inside the OCXO or the on board 5V now or as you say an external 8 volts. In any case using a lower reference voltage does decrease the range and step size. With no way to adjust the 10Mhz voltage point you could raise the lower limit by modifying the op amp to offset above ground. If using Bruce's suggestion then switch between two different positive regulated voltages and not regulated and ground with the analog switch.
>
> I have several 10811's just don't know how good they are yet ... 
>
>   
If you have 3 or more then you could use the 3 (or N) cornered hat
technique to identify the best of them.

However this requires a significant amount of phase comparison equipment
and adequate isolation between all the OCXOs.
Its all too easy to have one or more of the oscillators injection lock
if the OCXO buffer reverse isolation is inadequate.

Bruce


From hmurray at megapathdsl.net  Mon Dec  1 23:59:47 2008
From: hmurray at megapathdsl.net (Hal Murray)
Date: Mon, 01 Dec 2008 15:59:47 -0800
Subject: [time-nuts] CRYO Voltage standards
In-Reply-To: Message from Robert Atkinson <robert8rpi@yahoo.co.uk> of "Mon,
	01 Dec 2008 21:31:46 GMT." <1900.22727.qm@web27107.mail.ukl.yahoo.com> 
Message-ID: <20081201235948.2EC01BCD8@ip-64-139-1-69.sjc.megapath.net>

[Context is LN2]

> It's cheap and does not wear out (as stirling cycle and peltier coolers do)

What's the wear-out mechanism for peltier coolers?


-- 
These are my opinions, not necessarily my employer's.  I hate spam.





From stanley_reynolds at yahoo.com  Tue Dec  2 00:00:31 2008
From: stanley_reynolds at yahoo.com (Stanley Reynolds)
Date: Mon, 1 Dec 2008 16:00:31 -0800 (PST)
Subject: [time-nuts] NOT digest,
	I forget the subject not sure why the digest received Richard's
	reply and not me ? Oh well, never mind.
References: <mailman.515.1228170831.2542.time-nuts@febo.com>
	<EB528D92-72A0-43B4-82AA-C068746F584B@hughes.net>
	<706776.57600.qm@web30306.mail.mud.yahoo.com>
	<493472AE.4050807@xtra.co.nz>
Message-ID: <471654.87149.qm@web30301.mail.mud.yahoo.com>





________________________________

From: Bruce Griffiths <bruce.griffiths at xtra.co.nz>
To: Discussion of precise time and frequency measurement <time-nuts at febo.com>
Sent: Monday, December 1, 2008 5:26:38 PM
Subject: Re: [time-nuts] time-nuts Digest, Vol 53, Issue 8


Guess that would be the case of too good to believe performance unless the lock was intermittent and was not recognized. Guessing that the phase comparison equipment should be fairly equal in precision and accuracy as well, maybe a rapid switch of the measuring by only one device would help the equal part if the sample and?recording could be rapid enough. Otherwise some type of rotation to qualify differences in the measuring equipment. Or as I suspect most use better precision and accuracy in the testing equipment?than the DUT, once you reach the upper limit of better measurement then use the N cornered hat to cull the bad ones and id the good ones.

Stanley

_______________________________________________
time-nuts mailing list -- time-nuts at febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

>
> I have several 10811's just don't know how good they are yet ... 
>
>? 
If you have 3 or more then you could use the 3 (or N) cornered hat
technique to identify the best of them.

However this requires a significant amount of phase comparison equipment
and adequate isolation between all the OCXOs.
Its all too easy to have one or more of the oscillators injection lock
if the OCXO buffer reverse isolation is inadequate.

Bruce

From bruce.griffiths at xtra.co.nz  Tue Dec  2 00:05:34 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Tue, 02 Dec 2008 13:05:34 +1300
Subject: [time-nuts] CRYO Voltage standards
In-Reply-To: <20081201235948.2EC01BCD8@ip-64-139-1-69.sjc.megapath.net>
References: <20081201235948.2EC01BCD8@ip-64-139-1-69.sjc.megapath.net>
Message-ID: <49347BCE.6070005@xtra.co.nz>

Hal Murray wrote:
> [Context is LN2]
>
>   
>> It's cheap and does not wear out (as stirling cycle and peltier coolers do)
>>     
>
> What's the wear-out mechanism for peltier coolers?
>
>
>   
One wear out mechanism is mechanical fatigue due to thermal cycling.

Bruce


From bruce.griffiths at xtra.co.nz  Tue Dec  2 00:19:34 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Tue, 02 Dec 2008 13:19:34 +1300
Subject: [time-nuts] NOT digest,
 I forget the subject not sure why the digest received
 Richard's	reply and not me ? Oh well, never mind.
In-Reply-To: <471654.87149.qm@web30301.mail.mud.yahoo.com>
References: <mailman.515.1228170831.2542.time-nuts@febo.com>	<EB528D92-72A0-43B4-82AA-C068746F584B@hughes.net>	<706776.57600.qm@web30306.mail.mud.yahoo.com>	<493472AE.4050807@xtra.co.nz>
	<471654.87149.qm@web30301.mail.mud.yahoo.com>
Message-ID: <49347F16.1040704@xtra.co.nz>

Stanley Reynolds wrote:
> Guess that would be the case of too good to believe performance unless the lock was intermittent and was not recognized. Guessing that the phase comparison equipment should be fairly equal in precision and accuracy as well, maybe a rapid switch of the measuring by only one device would help the equal part if the sample and recording could be rapid enough. Otherwise some type of rotation to qualify differences in the measuring equipment. Or as I suspect most use better precision and accuracy in the testing equipment than the DUT, once you reach the upper limit of better measurement then use the N cornered hat to cull the bad ones and id the good ones.
>
> Stanley
>
>   
Injection locking can lead to an unbelievably low phase noise, ADEV etc.
The insidious part is that the closer the OCXO resonator frequencies
become the lower the injected signal has to be to achieve injection lock.
ie as the frequencies get closer more and more reverse isolation is
required.
One limiting mechanism is the intrinsic fluctuation in resonator parameters.

Ideally the phase comparisons should be made simultaneously.
Deadtime can confound the results depending on the phase noise processes
that are significant.
If more than one type of phase noise process (white phase, flicker
phase, white FM, flicker FM etc) is present/significant, correcting for
deadtime effects can be problematic.

One method is to use very high reverse isolation (>120dB) buffers
between each OCXO and the phase comparison gear.
If one uses mixers (eg in dual mixer systems), then high isolation
mixers can help.
Minicircuits have a few (2??) level 17 mixers with 80dB LO to RF
isolation (RF to LO isolation should be similar) at 10MHz.

One could use N dual mixer systems together with N high end sound cards
(plus software) and a suitable offset oscillator to make the phase
comparisons.

Bruce


From warrensjmail-one at yahoo.com  Tue Dec  2 00:22:16 2008
From: warrensjmail-one at yahoo.com (WarrenS)
Date: Mon, 1 Dec 2008 16:22:16 -0800
Subject: [time-nuts]  V standards
Message-ID: <01d901c95414$08a10820$6401a8c0@WSOffice>

Bruce 

Does this mean that by "using carrier phase disciplining techniques"  
One could get two orders less noise than  is shown 
on the SRS page#3  graph http://www.thinksrs.com/downloads/PDFs/Catalog/PRS10c.pdf

Is this also better than you get when using the 1PPS correction sawtooth?
Do you know of a posted plot that shows the noise you get using the Carrier phase techniques?

Do please understand that my questions about using pots etc, 
are to get a better understand about what is going on, 
Not suggestions on how to make one.

Thanks,
WarrenS
************************

WarrenS wrote:
>> Bruce Wrote: 
>> "Sometimes its cheaper and more convenient to build  a high 
>> resolution DAC than use a pot and a conventional DAC. ...
>>     
>
> Very true, And don't forget also more fun, more challenging, and more better!
> which all very import  requirements in this field, maybe more so than performance.
>
> Assuming  100 to 1000 seconds are the typical max tracking times 
> practical in the standard GPSDO's due to temperature changes, 
> initial aging, etc  as stated by Ulrich in the posting  
> http://www.febo.com/pipermail/time-nuts/2008-December/034823.html 
> and IF IE-10 is the best you get from the GPS signal in these same 
> time averages as stated on Page #3 of  
> http://www.thinksrs.com/downloads/PDFs/Catalog/PRS10c.pdf
>
> Doesn't this imply that a Dac with more than about 12 bits becomes 
> an overkill at 100 seconds tracking when using a 1E-7 turning range OSC, 
> and around 18 bits for the same Osc when tracking at 1000 Sec? 
>
> WarrenS
> **********************
>   
Warren

In principle, but this precludes such improvements as correcting for
ambient temperature variations in software etc., without upgrading the
DAC resolution.
Also (as many have discovered) when one is testing various oscillators
of unknown performance its very convenient to have somewhat more EFC DAC
resolution than 12bits or even 14bits.
it is also useful to have a relatively stable low noise reference for
the high resolution DAC.

Also a low resolution DAC precludes (or at least makes more difficult)
using carrier phase disciplining techniques which can have around 2
orders less noise than PPS tracking GPSDOs.
A relatively inexpensive 20 bit DAC can make such experimentation much
easier.


Bruce

From billj at ieee.org  Tue Dec  2 00:34:42 2008
From: billj at ieee.org (Bill Janssen)
Date: Mon, 01 Dec 2008 16:34:42 -0800
Subject: [time-nuts] Unknown GPSDO
In-Reply-To: <A6FCFFFF5B654B48AD4125E0FC0DF201@cyrus>
References: <4fdb424f0812011133n35d53470ve208bea9c1e44ce3@mail.gmail.com><p0624056bc559ee1b6b6a@10.1.5.33>	<4fdb424f0812011152i44a4273bh9528c39209e55fcf@mail.gmail.com>
	<A6FCFFFF5B654B48AD4125E0FC0DF201@cyrus>
Message-ID: <493482A2.5050709@ieee.org>

Do any of you know any details of an unknown GPS DO. Visual GPS 
identifies it as
a Motorola VP/GT. It fas a Motorola 5 MHz. packaged oscillator and a 
Motorola GPS receiver.
The receiver is apparently a 6 channel model. One of the circuit boards 
are marked 1991-1994.

It has 1 Hz, pulse and 5 MHz. on the back and front . but the back is 
only activated when it
is "in service" It also has a RS232 interface on the back and two 
connectors I don't understand. One is a two row 10 pin header the other 
connector  is a "RJ" (similar to telephone) connector.

It apparently works, but even when the "in service" light is on it  it 
is still not locked when I compare
it to anther GPSDO

Any source of information on this unit is appreciated

Bill K7NOM



From bruce.griffiths at xtra.co.nz  Tue Dec  2 00:57:31 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Tue, 02 Dec 2008 13:57:31 +1300
Subject: [time-nuts] V standards
In-Reply-To: <01d901c95414$08a10820$6401a8c0@WSOffice>
References: <01d901c95414$08a10820$6401a8c0@WSOffice>
Message-ID: <493487FB.6000101@xtra.co.nz>

WarrenS wrote:
> Bruce 
>
> Does this mean that by "using carrier phase disciplining techniques"  
> One could get two orders less noise than  is shown 
> on the SRS page#3  graph http://www.thinksrs.com/downloads/PDFs/Catalog/PRS10c.pdf
>
> Is this also better than you get when using the 1PPS correction sawtooth?
> Do you know of a posted plot that shows the noise you get using the Carrier phase techniques?
>
> Do please understand that my questions about using pots etc, 
> are to get a better understand about what is going on, 
> Not suggestions on how to make one.
>
> Thanks,
> WarrenS
> ************************
>
>   
Warren

Yes the carrier phase technique does have a noise level about 2 or more
orders of magnitude lower for an averaging time of 10 seconds.
At averaging times of around 1 day or so the noise levels are limited by
the SV oscillator instabilities and are comparable with the noise level
of a PPS based system.

Some of the complications are:

1) not all GPS receivers make the carrier phase observable accessible to
the user

2) The GPS receiver local oscillators have to be phase locked to the
OCXO being disciplined as the the carrier phase observables are actually
measures of the GPS LO phase errors.
This introduces some complexity except for receivers like the Novatel
Superstar that use a 10MHz local oscillator.
Most geodetic class GPS receivers require a 5MHz, 10Mhz or 20MHz
external frequency standard input (the input frequency depends on the
receiver model).

3) Extracting timing data from carrier phase observables is somewhat
complex due to an unknown offset that has to be determined.
Extracting useful information for disciplining the OCXO frequency is
somewhat easier and doesn't need the the extensive post processing and
precise orbits etc required for time and position comparisons when using
a geodetic receiver.

4) GPS carrier cycle slips also have to be accounted for.

5) The GPS reciver LO has to be phase locked to the OCXO unless the
realtive phase of the GPS LO and the OCXO is measured, however this
requires additional hardware.

Some of the advantages are:

1) All the required measurement hardware is built in to the GPS
receiver, no add on phase comparators etc are required.
However a DAC is still required to drive the OCXO EFC input.

2) The measurement resolution and phase are much lower.

Posted plots are hard to find but some idea of the performance can be
gleaned from the commercial carrier phase disciplined OCXO performance
specs and from data extracted from survey data obtained using arrays of
carrier phase tracking receivers (~ 3E-11 noise for an averaging time of
1 sec when using the TCXO embedded in a Novatel Superstar receiver).

Your questions are useful in that they (or at least the replies
generated in response to them) help clarify various points/issues.
One point that I should have mentioned with pots is that cermet, carbon
and conductive plastic pots are fine when there is no dc current flowing
in them.
However they produce significant flicker noise when significant dc
current is flowing in them.
Wire wound and thin film pots are much quieter.
However precision thin film pots tend to degrade/wear out after a
relatively low number of adjustments.
Wire wound pots are more durable but have limited resolution.

Bruce



From bruce.griffiths at xtra.co.nz  Tue Dec  2 01:22:01 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Tue, 02 Dec 2008 14:22:01 +1300
Subject: [time-nuts] GPS carrier phase
Message-ID: <49348DB9.3050209@xtra.co.nz>

The following papers give some idea of the potential performance of the
carrier phase technique for disciplining an OCXO:

http://tycho.usno.navy.mil/ptti/ptti2001/paper19.pdf

https://gra103.aca.ntu.edu.tw/gdoc/F88921021a.pdf


Bruce


From tvb at LeapSecond.com  Tue Dec  2 01:23:27 2008
From: tvb at LeapSecond.com (Tom Van Baak)
Date: Mon, 1 Dec 2008 17:23:27 -0800
Subject: [time-nuts] V standards
References: <01d901c95414$08a10820$6401a8c0@WSOffice>
Message-ID: <110BF700D749446F82318D90B81E8567@pc52>

> Does this mean that by "using carrier phase disciplining techniques"  
> One could get two orders less noise than  is shown 
> on the SRS page#3  graph http://www.thinksrs.com/downloads/PDFs/Catalog/PRS10c.pdf

Warren,

Yes, high-end survey equipment and metrology-level GPS timing
receivers are based on carrier phase rather than code phase.

But you'll rarely see this implemented as a GPSDO (I know of one
and it's obsolete). Instead, for this class of receiver the local lab
frequency standard (e.g., cesium or maser) is used to drive the
receiver's clock and what you get out are a series of internal phase
measurements. These are often batched up daily and then other
non-realtime corrections are applied. What you get in the end is
a precise measure of how good your local standard *was*.

There's no reason in principal that a carrier phase GPSDO would
not work. But I think you quickly run into other limitations that
dominate the net accuracy. Like SV clock errors, orbit errors,
and ionospheric corrections, etc. For fullest accuracy these all
have to be applied after-the-fact (because they are not known
well enough in realtime).

Remember also that the GPS signal, as received by you (no
matter how fancy the receiver), is not a perfect copy of UTC
time as transmitted by the satellites, which in turn is not a perfect
copy of UTC(USNO), which in turn is not a perfect copy of UTC.

/tvb



From bruce.griffiths at xtra.co.nz  Tue Dec  2 01:25:50 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Tue, 02 Dec 2008 14:25:50 +1300
Subject: [time-nuts] GPS carrier phase
In-Reply-To: <49348DB9.3050209@xtra.co.nz>
References: <49348DB9.3050209@xtra.co.nz>
Message-ID: <49348E9E.5040308@xtra.co.nz>

Bruce Griffiths wrote:
> The following papers give some idea of the potential performance of the
> carrier phase technique for disciplining an OCXO:
>
> http://tycho.usno.navy.mil/ptti/ptti2001/paper19.pdf
>
> https://gra103.aca.ntu.edu.tw/gdoc/F88921021a.pdf
>
>
> Bruce
>
>   
Additional paper:

http://www.pttimeeting.org/archivemeetings/2000papers/poster14.pdf

Bruce


From stanley_reynolds at yahoo.com  Tue Dec  2 01:29:59 2008
From: stanley_reynolds at yahoo.com (Stanley Reynolds)
Date: Mon, 1 Dec 2008 17:29:59 -0800 (PST)
Subject: [time-nuts] NOT digest,
	I forget the subject not sure why the digest received Richard's
	reply and not me ? Oh well, never mind.
References: <mailman.515.1228170831.2542.time-nuts@febo.com>
	<EB528D92-72A0-43B4-82AA-C068746F584B@hughes.net>
	<706776.57600.qm@web30306.mail.mud.yahoo.com>
	<493472AE.4050807@xtra.co.nz>
	<471654.87149.qm@web30301.mail.mud.yahoo.com>
	<49347F16.1040704@xtra.co.nz>
Message-ID: <423091.49026.qm@web30308.mail.mud.yahoo.com>



http://www.unusualresearch.com/AppNotes/TimeNuts/OptDualMixer.pdf



Fig 1 shows a phase shift of OSC 1 is this required ? Or is it just a indication of the difference in phase of the two OCS's ? Or is this a way to prevent injection lock ?

Further on they say:

"Interference may cause an undesired phase lock by an injection locking process between the measured oscillators. Fortunately these undesired phase locks can be easily detected. The more dangerous are near-false phase locks where the phase is only disturbed."

Maybe that is the propose of the phase shifter on one of the two oscillators ?

Stanley

PS when I attached the pdf it bounced (> 128 KB) so this is a copy with no attachment just the link.

From bruce.griffiths at xtra.co.nz  Tue Dec  2 01:49:37 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Tue, 02 Dec 2008 14:49:37 +1300
Subject: [time-nuts] NOT digest,
 I forget the subject not sure why the digest received
 Richard's	reply and not me ? Oh well, never mind.
In-Reply-To: <423091.49026.qm@web30308.mail.mud.yahoo.com>
References: <mailman.515.1228170831.2542.time-nuts@febo.com>	<EB528D92-72A0-43B4-82AA-C068746F584B@hughes.net>	<706776.57600.qm@web30306.mail.mud.yahoo.com>	<493472AE.4050807@xtra.co.nz>	<471654.87149.qm@web30301.mail.mud.yahoo.com>	<49347F16.1040704@xtra.co.nz>
	<423091.49026.qm@web30308.mail.mud.yahoo.com>
Message-ID: <49349431.7010903@xtra.co.nz>

Stanley Reynolds wrote:
> http://www.unusualresearch.com/AppNotes/TimeNuts/OptDualMixer.pdf
>
>
>
> Fig 1 shows a phase shift of OSC 1 is this required ? Or is it just a indication of the difference in phase of the two OCS's ? Or is this a way to prevent injection lock ?
>
> Further on they say:
>
> "Interference may cause an undesired phase lock by an injection locking process between the measured oscillators. Fortunately these undesired phase locks can be easily detected. The more dangerous are near-false phase locks where the phase is only disturbed."
>
> Maybe that is the propose of the phase shifter on one of the two oscillators ?
>
> Stanley
>
> PS when I attached the pdf it bounced (> 128 KB) so this is a copy with no attachment just the link.
>
>   
Stanley

The purpose of the phase shifter is to approximately align the zero
crossings of the 2 bat frequency signals being compared.
This reduces the sensitivity to the phase noise of the offset oscillator.
It has little or no effect on injection locking.
Other measurement methods can be used that have high rejection of the
offset oscillator phase noise without requiring approximate alignment of
the zero crossings of the 2 beat frequency signals.

Some injection locking paths are:

1) from the RF port of one mixer to its LO port and thence to the LO
port of the other mixer to its Rf port.

2) from the RF port of either mixer to its LO port and hence to the LO
via its output buffer.

As depicted in the circuit diagrams this particular implementation has
significant coupling from the RF port of the mixer to the RF port of the
other mixer.

The coupling from the RF port of either mixer to the LO port will be
even higher.

The reverse isolation of the output amplifiers of both the OCXOs and the
offset oscillator will need to be very high to avoid injection locking.

The statement that injection locking can easily be detected is somewhat
glib and brushes over the detail.
Its not always easy to detect especially if you don't know what to look for.

Bruce



From SAIDJACK at aol.com  Tue Dec  2 02:37:25 2008
From: SAIDJACK at aol.com (SAIDJACK at aol.com)
Date: Mon, 1 Dec 2008 21:37:25 EST
Subject: [time-nuts] V standards
Message-ID: <d2a.3b4df63b.3665f965@aol.com>

Hi Warren,
 
as Bruce mentioned, you will want much more resolution than 12 bits to  
properly correct for tempco, and more importantly aging.
 
Having only 4096 steps for adjustment is definitely not enough, it will  give 
you a huge offset of 2.44E-011 per step for your 1E-07 OCXO.
 
That may not seem like much, but it actually is for a phase locked  system 
(2.44E-011 is 24.4ns over 1000s).
 
As an example, we have a unit running in Mexico that has an average EFC  
tracking range of less than +/-20 Microvolts over the period of a typical day,  
meaning the control voltage remains within a 40 microvolt window over the  
entire day. See the plots at:
 
   _http://resco.ucol.mx/Fury/gpsstat.htm_ 
(http://resco.ucol.mx/Fury/gpsstat.htm) 
 
If you only have 12 bits - 4096 steps, into a 5V control range, then  this 
gives you a step size of 1.22mV, a huge difference of 61 to 1 between the  
maximum control window range on this particular OCXO, and your minimum 12 bit  step 
size.
 
Your system would be constantly switching between two steps, and generate  a 
massive amount of phase drift.
 
Also, it is fairly simple to cascade DACs to get say 24 bits resolution out  
of two inexpensive 16 bit DAC's etc.
 
There was a recent Design Idea in EDN or Electronic Design (don't remember  
which one) where someone claimed 32 bit resolution out of two 16 bit dacs. That 
 claim is ridiculous of course due to noise and matching etc, but you can  
probably get 20 - 24 bits resolution and accuracy out of a cascaded system with  
some care.
 
bye,
Said
 
 
 
 
In a message dated 12/1/2008 14:58:47 Pacific Standard Time,  
warrensjmail-one at yahoo.com writes:


Doesn't this imply that a Dac with more than about 12 bits becomes  
an overkill at 100 seconds tracking when using a 1E-7 turning range OSC,  
and around 18 bits for the same Osc when tracking at 1000 Sec?  

WarrenS


From sar10538 at gmail.com  Tue Dec  2 03:28:52 2008
From: sar10538 at gmail.com (Steve Rooke)
Date: Tue, 2 Dec 2008 16:28:52 +1300
Subject: [time-nuts] What are the important features to look for in
	antime sync piece of hardware?
In-Reply-To: <335660A0A96347CF9A67BD608CBDFBA8@Robin>
References: <4fdb424f0812011133n35d53470ve208bea9c1e44ce3@mail.gmail.com>
	<p0624056bc559ee1b6b6a@10.1.5.33>
	<4fdb424f0812011152i44a4273bh9528c39209e55fcf@mail.gmail.com>
	<335660A0A96347CF9A67BD608CBDFBA8@Robin>
Message-ID: <1231b6a80812011928t3da4d9cbgcb451f9730d1027c@mail.gmail.com>

2008/12/2 Rob Kimberley <rk at timing-consultants.com>:
> How long is a piece of string?

Twice the distance from the middle to the end.

73, Steve - ZL3TUV

>
> Rob K
>
> -----Original Message-----
> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
> Behalf Of Gretchen Baxter
> Sent: 01 December 2008 19:53
> To: Discussion of precise time and frequency measurement
> Subject: Re: [time-nuts] What are the important features to look for in
> antime sync piece of hardware?
>
> very true!
>
> but looking for a basic feature set.
>
>
>
>
> On Mon, Dec 1, 2008 at 2:43 PM, J.D. Bakker <jdb at lartmaker.nl> wrote:
>
>> >What are the important features to look for in an time sync piece of
>> >hardware?
>>
>> Does that not depend a lot on your intended application? I would
>> expect to look for different things in a one-off time server for a lab
>> than if I had a network of cell towers in need of sync.
>>
>> JDB.
>> --
>> LART. 250 MIPS under one Watt. Free hardware design files.
>> http://www.lartmaker.nl/
>>
>> _______________________________________________
>> time-nuts mailing list -- time-nuts at febo.com To unsubscribe, go to
>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>> and follow the instructions there.
>>
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com To unsubscribe, go to
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>
>
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>



-- 
Steve Rooke - ZL3TUV & G8KVD
Omnium finis imminet


From stanley_reynolds at yahoo.com  Tue Dec  2 04:17:09 2008
From: stanley_reynolds at yahoo.com (Stanley Reynolds)
Date: Mon, 1 Dec 2008 20:17:09 -0800 (PST)
Subject: [time-nuts] Picking a good HP 10811
References: <mailman.515.1228170831.2542.time-nuts@febo.com>
	<EB528D92-72A0-43B4-82AA-C068746F584B@hughes.net>
	<706776.57600.qm@web30306.mail.mud.yahoo.com>
	<493472AE.4050807@xtra.co.nz>
	<471654.87149.qm@web30301.mail.mud.yahoo.com>
	<49347F16.1040704@xtra.co.nz>
	<423091.49026.qm@web30308.mail.mud.yahoo.com>
	<49349431.7010903@xtra.co.nz>
Message-ID: <908800.88540.qm@web30307.mail.mud.yahoo.com>



The HP10811 has about +- 10Hz coarse adjustment would it be a good idea to make sure they don't have the same frequency by adjusting them in opposite directions from 10 Mhz before the test, like 10Mhz+4hz, 10Mhz, and 10Mhz-4hz for three. Would assume the common oscillator would be 10 to 20 Khz above or below the DUT.

Or does the sound card method work better with small differences ?

The manual recommends grounding the ECC line during tests. Maybe the test rig could set the ECC different on each one in the test. This would result in a much smaller difference and maybe no difference depending on each oscillator zero volt ECC frequency. ECC is listed as 1Hz range for -5 to +5 volts.

Would attenuation of the DUT signal physically separated from the mixer but after and buffer amp help ? 

From bruce.griffiths at xtra.co.nz  Tue Dec  2 04:36:57 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Tue, 02 Dec 2008 17:36:57 +1300
Subject: [time-nuts] Picking a good HP 10811
In-Reply-To: <908800.88540.qm@web30307.mail.mud.yahoo.com>
References: <mailman.515.1228170831.2542.time-nuts@febo.com>	<EB528D92-72A0-43B4-82AA-C068746F584B@hughes.net>	<706776.57600.qm@web30306.mail.mud.yahoo.com>	<493472AE.4050807@xtra.co.nz>	<471654.87149.qm@web30301.mail.mud.yahoo.com>	<49347F16.1040704@xtra.co.nz>	<423091.49026.qm@web30308.mail.mud.yahoo.com>	<49349431.7010903@xtra.co.nz>
	<908800.88540.qm@web30307.mail.mud.yahoo.com>
Message-ID: <4934BB69.9050909@xtra.co.nz>

Stanley Reynolds wrote:
> The HP10811 has about +- 10Hz coarse adjustment would it be a good idea to make sure they don't have the same frequency by adjusting them in opposite directions from 10 Mhz before the test, like 10Mhz+4hz, 10Mhz, and 10Mhz-4hz for three. Would assume the common oscillator would be 10 to 20 Khz above or below the DUT.
>
> Or does the sound card method work better with small differences ?
>
> The manual recommends grounding the ECC line during tests. Maybe the test rig could set the ECC different on each one in the test. This would result in a much smaller difference and maybe no difference depending on each oscillator zero volt ECC frequency. ECC is listed as 1Hz range for -5 to +5 volts.
>
> Would attenuation of the DUT signal physically separated from the mixer but after and buffer amp help ? 
>   
Stanley

Adjusting the oscillators in opposite directions is helpful at least in
trouble shooting.
However AFAIK it wont have much effect on the susceptibility to
injection locking as that depends on the degree of mismatch between the
resonator natural frequencies.
There no real substitute for a high reverse isolation buffer.

The classical sound card technique works best with small frequency
differences.
There are variants that work better with larger frequency offsets,
however as yet they are not yet fully debugged/tested.
Grounding the EFC line minimises noise contributions from the EFC
voltage source.

Attenuating the DUT will increase the system noise level.

High level mixers like the Minicircuits ZP3H and the TUF3HSM+ level 17
mixers which have high LO to Rf isolation at 10MHz are well suited.
Operating the RF port below saturation level will minimise the mixer
phase shift tempco.
Terminating the mixer IF port in a capacitor will reduce the mixer noise.

A classical buffer amp with transformer input and output that cascades 3
or more common base stages can have high reverse isolation as well as
low input and output VSWR.
At 10MHz 2N3904's are suitable - they also have less tendency to break
into VHF/UHF oscillation than higher frequency transistors.

Shielding everything well also helps.
Build the buffer/isolation amplifiers in individual shielded enclosures.

Bruce


From warrensjmail-one at yahoo.com  Tue Dec  2 05:47:52 2008
From: warrensjmail-one at yahoo.com (WarrenS)
Date: Mon, 1 Dec 2008 21:47:52 -0800
Subject: [time-nuts]  V standards
Message-ID: <02c101c95441$84bb13b0$6401a8c0@WSOffice>


to Said
 Thanks for the information and response and pointing out some errors.

It sounds like the Mexico unit must not be runing a 100 SECONDS tracking
 loop as I used in my example. 

I did not really mean it to be the trick question it turned out to be.
I messed up on my seconds and minuties.  

As stated, the 12 bit Dac example assumed a 100 SECOND tracking time as 
I thought ULRICH meant with his "s" notation. So what did ULRICH's "100 s" mean?
With a 100 SECOND tracking time the noise on the GPS signal is close to 1E-9, 
so it appears that a 12 bit Dac would be a giant Overkill by almost 5 bits.  
A 100 second control loop just does not need anything nearly as fine as 
a 2.44E-11 step size to track a 1E-9 noise signal near prefect. 

The Root Allian noise of the GPS at 100 Minuties plot is about 1E-11.
So the question is: 
What is the minimun Dac resolution it would take so as not to degrade the 
noise performance by more than 3 dB for a 100 minute control loop?

BTW I've  head from others that a 2.44E-11 resolution Dac works OK for 
most applications.  More is better of course. Maybe there is some 
additional filtering going on or maybe it is they just can't measure short 
time period noise very well. That comes out to about 10 ps or so of 1 sec 
phase noise.Not many instruments are going to be able to measure that!
What is it you use using to measure the 2.44E-11 freq noise 
at 1 second? 

Warren 
********************************** 

Hi Warren,
 
as Bruce mentioned, you will want much more resolution than 12 bits to  
properly correct for tempco, and more importantly aging.
 
Having only 4096 steps for adjustment is definitely not enough, it will  give 
you a huge offset of 2.44E-011 per step for your 1E-07 OCXO.
 
That may not seem like much, but it actually is for a phase locked  system 
(2.44E-011 is 24.4ns over 1000s).
 
As an example, we have a unit running in Mexico that has an average EFC  
tracking range of less than +/-20 Microvolts over the period of a typical day,  
meaning the control voltage remains within a 40 microvolt window over the  
entire day. See the plots at:
 
   _http://resco.ucol.mx/Fury/gpsstat.htm_ 
(http://resco.ucol.mx/Fury/gpsstat.htm) 
 
If you only have 12 bits - 4096 steps, into a 5V control range, then  this 
gives you a step size of 1.22mV, a huge difference of 61 to 1 between the  
maximum control window range on this particular OCXO, and your minimum 12 bit  step 
size.
 
Your system would be constantly switching between two steps, and generate  a 
massive amount of phase drift.
 
Also, it is fairly simple to cascade DACs to get say 24 bits resolution out  
of two inexpensive 16 bit DAC's etc.
 
There was a recent Design Idea in EDN or Electronic Design (don't remember  
which one) where someone claimed 32 bit resolution out of two 16 bit dacs. That 
 claim is ridiculous of course due to noise and matching etc, but you can  
probably get 20 - 24 bits resolution and accuracy out of a cascaded system with  
some care.
 
bye,
Said
 
  
In a message dated 12/1/2008 14:58:47 Pacific Standard Time,  
warrensjmail-one at yahoo.com writes:

Doesn't this imply that a Dac with more than about 12 bits becomes  
an overkill at 100 seconds tracking when using a 1E-7 turning range OSC,  
and around 18 bits for the same Osc when tracking at 1000 Sec?  

**********************************
>Bruce Wrote: 
> "Sometimes its cheaper and more convenient to build  a high 
> resolution DAC than use a pot and a conventional DAC. ...

Very true, And don't forget also more fun, more challenging, and more better!
which all very import  requirements in this field, maybe more so than performance.

Assuming  100 to 1000 seconds are the typical max tracking times 
practical in the standard GPSDO's due to temperature changes, 
initial aging, etc  as stated by Ulrich in the posting  
http://www.febo.com/pipermail/time-nuts/2008-December/034823.html 
and IF IE-10 is the best you get from the GPS signal in these same 
time averages as stated on Page #3 of  
http://www.thinksrs.com/downloads/PDFs/Catalog/PRS10c.pdf

Doesn't this imply that a Dac with more than about 12 bits becomes 
an overkill at 100 seconds tracking when using a 1E-7 turning range OSC, 
and around 18 bits for the same Osc when tracking at 1000 Sec? 

WarrenS

From bruce.griffiths at xtra.co.nz  Tue Dec  2 06:46:47 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Tue, 02 Dec 2008 19:46:47 +1300
Subject: [time-nuts] V standards
In-Reply-To: <d2a.3b4df63b.3665f965@aol.com>
References: <d2a.3b4df63b.3665f965@aol.com>
Message-ID: <4934D9D7.8050401@xtra.co.nz>

SAIDJACK at aol.com wrote:
> Hi Warren,
>  
> as Bruce mentioned, you will want much more resolution than 12 bits to  
> properly correct for tempco, and more importantly aging.
>  
> Having only 4096 steps for adjustment is definitely not enough, it will  give 
> you a huge offset of 2.44E-011 per step for your 1E-07 OCXO.
>  
> That may not seem like much, but it actually is for a phase locked  system 
> (2.44E-011 is 24.4ns over 1000s).
>  
> As an example, we have a unit running in Mexico that has an average EFC  
> tracking range of less than +/-20 Microvolts over the period of a typical day,  
> meaning the control voltage remains within a 40 microvolt window over the  
> entire day. See the plots at:
>  
>    _http://resco.ucol.mx/Fury/gpsstat.htm_ 
> (http://resco.ucol.mx/Fury/gpsstat.htm) 
>  
> If you only have 12 bits - 4096 steps, into a 5V control range, then  this 
> gives you a step size of 1.22mV, a huge difference of 61 to 1 between the  
> maximum control window range on this particular OCXO, and your minimum 12 bit  step 
> size.
>  
> Your system would be constantly switching between two steps, and generate  a 
> massive amount of phase drift.
>  
> Also, it is fairly simple to cascade DACs to get say 24 bits resolution out  
> of two inexpensive 16 bit DAC's etc.
>  
> There was a recent Design Idea in EDN or Electronic Design (don't remember  
> which one) where someone claimed 32 bit resolution out of two 16 bit dacs. That 
>  claim is ridiculous of course due to noise and matching etc, but you can  
> probably get 20 - 24 bits resolution and accuracy out of a cascaded system with  
> some care.
>  
> bye,
> Said
>  
>   
Said

If you build this circuit using the values shown in the schematic you
won't actually achieve 20 bits performance.
One of the resistor values is incorrect.
The resistor matching requirements aren't anywhere near as stringent as
one may think on first glance.
With some subtle alterations to the operating mode the resistor ratio
matching tolerances can be relaxed considerably.
In closed loop digital control systems the circuit noise should be at
least 1LSB or so to maximise performance.
The trick is to increase the DAC resolution until this condition is
achieved and not increase the noise to meet the condition.
20 bit resolution performance is easy to achieve, 24 bit performance
requires 2 a little more work.

Actually monotonicity to about 26 bits was claimed with noise a bit
below 1ppm.
However since the noise varies with the DAC output such claims are
perhaps a little too simplistic.
The noise can be reduced when required by using a better reference.
Any drift in DAC gain and offset could be compensated by a Kalman filter
should they become significant.

The major advantage of such a DAC is the inherent monotonicity which
cannot be achieved and maintained (around coarse DAC transitions)
without frequent calibration when the outputs of 2 16 bit DACs are combined.

Bruce


From phk at phk.freebsd.dk  Tue Dec  2 06:49:39 2008
From: phk at phk.freebsd.dk (Poul-Henning Kamp)
Date: Tue, 02 Dec 2008 06:49:39 +0000
Subject: [time-nuts] CRYO Voltage standards
In-Reply-To: Your message of "Tue, 02 Dec 2008 13:05:34 +1300."
	<49347BCE.6070005@xtra.co.nz> 
Message-ID: <1780.1228200579@critter.freebsd.dk>

In message <49347BCE.6070005 at xtra.co.nz>, Bruce Griffiths writes:
>Hal Murray wrote:

>> What's the wear-out mechanism for peltier coolers?
>>   
>One wear out mechanism is mechanical fatigue due to thermal cycling.

And, if you run them at too high current, material migration.

-- 
Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk at FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.


From bruce.griffiths at xtra.co.nz  Tue Dec  2 06:58:55 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Tue, 02 Dec 2008 19:58:55 +1300
Subject: [time-nuts] Picking a good HP 10811
In-Reply-To: <4934BB69.9050909@xtra.co.nz>
References: <mailman.515.1228170831.2542.time-nuts@febo.com>	<EB528D92-72A0-43B4-82AA-C068746F584B@hughes.net>	<706776.57600.qm@web30306.mail.mud.yahoo.com>	<493472AE.4050807@xtra.co.nz>	<471654.87149.qm@web30301.mail.mud.yahoo.com>	<49347F16.1040704@xtra.co.nz>	<423091.49026.qm@web30308.mail.mud.yahoo.com>	<49349431.7010903@xtra.co.nz>	<908800.88540.qm@web30307.mail.mud.yahoo.com>
	<4934BB69.9050909@xtra.co.nz>
Message-ID: <4934DCAF.5000606@xtra.co.nz>

Bruce Griffiths wrote:
> Stanley Reynolds wrote:
>   
>> The HP10811 has about +- 10Hz coarse adjustment would it be a good idea to make sure they don't have the same frequency by adjusting them in opposite directions from 10 Mhz before the test, like 10Mhz+4hz, 10Mhz, and 10Mhz-4hz for three. Would assume the common oscillator would be 10 to 20 Khz above or below the DUT.
>>
>> Or does the sound card method work better with small differences ?
>>
>> The manual recommends grounding the ECC line during tests. Maybe the test rig could set the ECC different on each one in the test. This would result in a much smaller difference and maybe no difference depending on each oscillator zero volt ECC frequency. ECC is listed as 1Hz range for -5 to +5 volts.
>>
>> Would attenuation of the DUT signal physically separated from the mixer but after and buffer amp help ? 
>>   
>>     
> Stanley
>
> Adjusting the oscillators in opposite directions is helpful at least in
> trouble shooting.
> However AFAIK it wont have much effect on the susceptibility to
> injection locking as that depends on the degree of mismatch between the
> resonator natural frequencies.
> There no real substitute for a high reverse isolation buffer.
>
> The classical sound card technique works best with small frequency
> differences.
> There are variants that work better with larger frequency offsets,
> however as yet they are not yet fully debugged/tested.
> Grounding the EFC line minimises noise contributions from the EFC
> voltage source.
>
> Attenuating the DUT will increase the system noise level.
>
> High level mixers like the Minicircuits ZP3H and the TUF3HSM+ level 17
> mixers which have high LO to Rf isolation at 10MHz are well suited.
> Operating the RF port below saturation level will minimise the mixer
> phase shift tempco.
> Terminating the mixer IF port in a capacitor will reduce the mixer noise.
>
> A classical buffer amp with transformer input and output that cascades 3
> or more common base stages can have high reverse isolation as well as
> low input and output VSWR.
> At 10MHz 2N3904's are suitable - they also have less tendency to break
> into VHF/UHF oscillation than higher frequency transistors.
>
> Shielding everything well also helps.
> Build the buffer/isolation amplifiers in individual shielded enclosures.
>
> Bruce
>
>   
Correction:
Offsetting the injected signal frequency will actually decrease the
required isolation by an amount that depends on the operating Q of the
resonator.
With an operating Q of 1E6 and an offset of 0.5ppm the ratio of the
injected signal to the oscillator signal will need to be near  unity for
injection locking to occur.
It is relatively easy to ensure that this doesn't occur.
Thus it may well be worthwhile doing this as one then (in principle)
only needs 3 mixers (plus 3 simultaneously sampled sound card input
channels) and no offset source, however the maximum achievable offset
will probably result in beat frequencies that are a little too low for a
sound card ADC.

Bruce


From bruce.griffiths at xtra.co.nz  Tue Dec  2 07:00:37 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Tue, 02 Dec 2008 20:00:37 +1300
Subject: [time-nuts] CRYO Voltage standards
In-Reply-To: <1780.1228200579@critter.freebsd.dk>
References: <1780.1228200579@critter.freebsd.dk>
Message-ID: <4934DD15.9010704@xtra.co.nz>

Poul-Henning Kamp wrote:
> In message <49347BCE.6070005 at xtra.co.nz>, Bruce Griffiths writes:
>   
>> Hal Murray wrote:
>>     
>
>   
>>> What's the wear-out mechanism for peltier coolers?
>>>   
>>>       
>> One wear out mechanism is mechanical fatigue due to thermal cycling.
>>     
>
> And, if you run them at too high current, material migration.
>
>   
Yet another wearout mechanism is excited when the Peltier device ripple
current is too high.

Bruce



From SAIDJACK at aol.com  Tue Dec  2 07:18:45 2008
From: SAIDJACK at aol.com (SAIDJACK at aol.com)
Date: Tue, 2 Dec 2008 02:18:45 EST
Subject: [time-nuts] V standards
Message-ID: <bef.38541c00.36663b55@aol.com>

Hi Bruce,
 
yup, I thought that circuit and it's claim to 32 bit resolution was over  the 
top too, I didn't actually read the details.
 
Coarsedac changes are an issue as you mentioned, but one can get around  them 
by scaling the two dacs in a way to only use a couple of bits from the  
coarsedac, and operate most of the time using just the fine dac.

This is similar to a mechanical coarse adjustment (such as on the  10811A) 
setting the approximate voltage range, with the EFC done by  the fine dac.
 
If you use a 16 - 18 bit fine dac, and 6 - 8 bits of a coarse dac then  this 
works quite well, and with a low aging SC-cut crystal you may never see a  
coarsedac change, while still having over 21+ bits of overall resolution.
 
It's fairly straight forward to improve the resolution of a good Dac by 2,  3 
or even 4 bits using PWM, see Tom's description of how this is done in a  
Z3801A on leapsecond.com.
 
So in short, one could use two identical 16 bit dacs, scale the resistors  so 
that only the upper 6 - 7 bits are used as a coarsedac, and use the fine dac  
as a 20 bit dac with PWM resolution-enhancement (16 to 20 bits). This would  
yield more than 26 bits theoretically from 2 inexpensive 16 bit dacs, and the  
noise could be removed by low pass filtering using an analog filter with  say 
less than 0.3Hz cutoff frequency similar to the Z3801A circuitry. In this  
case the coarsedac can probably even be exchanged for a simple high-stability  
pot.
 
It does require a bit of real time firmware to do the PWM enhancement of  
course.
 
bye,
Said
 
 
In a message dated 12/1/2008 22:47:29 Pacific Standard Time,  
bruce.griffiths at xtra.co.nz writes:

The  major advantage of such a DAC is the inherent monotonicity which
cannot be  achieved and maintained (around coarse DAC transitions)
without frequent  calibration when the outputs of 2 16 bit DACs are  combined.

Bruce



From SAIDJACK at aol.com  Tue Dec  2 07:57:00 2008
From: SAIDJACK at aol.com (SAIDJACK at aol.com)
Date: Tue, 2 Dec 2008 02:57:00 EST
Subject: [time-nuts] V standards
Message-ID: <cd1.40d61f99.3666444c@aol.com>

Hi Warren,
 
actually, we need to differentiate between phase and frequency errors;  Allan 
variance is typically a measure of phase drift over time. It's not quite  the 
same as a spectral power plot on a spectrum analyzer, but it's  related.
 
Some things to keep in mind:
 
* A 12 bit DAC may have an error of 1/2, 1, or even more than a couple  of 
LSB noise/monotonicity error/etc. Every DAC has a minimum quantization error  of 
1/2 LSB.
 
* On a 5V 12 bit DAC, you are going to switch the OCXO with a massive  1.22mV 
jolt when the dac LSB changes (if the DAC doesn't have any other errors).  
Most Euro-can OCXO's have about 8Hz/V frequency sensitivity, or even more than  
this, so 1.22mV could actually result in 9.76E-010, or almost 1ppb  frequency 
change!
 
On a Micro Crystal DIP-14 OCXO the change would be closer to 15Hz/V, so  
almost 2ppb steps per LSB. Not good.
 
When controlling a Rubidium with only +/-0.2Hz overall control range this  is 
a totally different story of course.
 
* GPSDO's don't really have "tracking times", they rather just use low-pass  
filters with natural cutoff-frequencies around 100s to 1000s (1/100Hz or  1
/1000Hz). Meaning they measure the phase error, low-pass filter this phase  
error, and apply the result to the DAC (oversimplified of course).
 
* The overall error of the system is a combination of the DAC quantization  
error (1/2 LSB) PLUS the error of the OCXO PLUS the error of the DAC voltage  
reference PLUS the inherent DAC errors.
 
All noise sources add since they are typically stochastic, so to expect an  
Allan variance to be the same as just the DAC quantization noise won't work 
out,  since we need to take all of the other noise sources into account too.
 
Lastly, to measure Allan variance down to xE-011 per second, we can use  
Agilent 53132A counters, TSC5110A or TSC5120A measurement systems, CNT-90  
counters,  Wavecrest DTS series counters, or other 12-digit per-second  resolution 
time intervall measurement systems. Most of these would work by  measuring phase 
drift between two oscillators.
 
So there is no easy answer to your problem, but yes - depending on your  
requirements a 12 bit DAC may just work out ok if you have a very good OCXO  with 
less than +/-0.5Hz overall adjustment range (1E-07 at 10MHz).
 
Hope that helps,
bye,
Said
 
 
 
 
 
 
 
In a message dated 12/1/2008 21:48:01 Pacific Standard Time,  
warrensjmail-one at yahoo.com writes:


BTW  I've  head from others that a 2.44E-11 resolution Dac works OK for  
most applications.  More is better of course. Maybe there is some  
additional filtering going on or maybe it is they just can't measure short  
time period noise very well. That comes out to about 10 ps or so of 1 sec  
phase noise.Not many instruments are going to be able to measure  that!
What is it you use using to measure the 2.44E-11 freq noise 
at 1  second? 



From bruce.griffiths at xtra.co.nz  Tue Dec  2 08:14:39 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Tue, 02 Dec 2008 21:14:39 +1300
Subject: [time-nuts] V standards
In-Reply-To: <bef.38541c00.36663b55@aol.com>
References: <bef.38541c00.36663b55@aol.com>
Message-ID: <4934EE6F.4040604@xtra.co.nz>

SAIDJACK at aol.com wrote:
> Hi Bruce,
>  
> yup, I thought that circuit and it's claim to 32 bit resolution was over  the 
> top too, I didn't actually read the details.
>  
> Coarsedac changes are an issue as you mentioned, but one can get around  them 
> by scaling the two dacs in a way to only use a couple of bits from the  
> coarsedac, and operate most of the time using just the fine dac.
>
>   
In principle embedded calibration of the errors at coarse DAC
transitions should be possible.
> This is similar to a mechanical coarse adjustment (such as on the  10811A) 
> setting the approximate voltage range, with the EFC done by  the fine dac.
>  
> If you use a 16 - 18 bit fine dac, and 6 - 8 bits of a coarse dac then  this 
> works quite well, and with a low aging SC-cut crystal you may never see a  
> coarsedac change, while still having over 21+ bits of overall resolution.
>  
> It's fairly straight forward to improve the resolution of a good Dac by 2,  3 
> or even 4 bits using PWM, see Tom's description of how this is done in a  
> Z3801A on leapsecond.com.
>   
Yes this can be made to work well, as can using sigma delta modulation
however one then needs a good random number generator for dithering the
loop quantiser to eliminate idle tones which are otherwise somewhat
problematic. The effect is very easy to simulate using Matlab or even by
writing some simple code.
Using a synchronous filtering technique simplifies the filtering
considerably. The usual sigma delta modulation techniques advocated to
increase DAC resolution don't work that well due to the idle tones they
generate.
>  
> So in short, one could use two identical 16 bit dacs, scale the resistors  so 
> that only the upper 6 - 7 bits are used as a coarsedac, and use the fine dac  
> as a 20 bit dac with PWM resolution-enhancement (16 to 20 bits). This would  
> yield more than 26 bits theoretically from 2 inexpensive 16 bit dacs, and the  
> noise could be removed by low pass filtering using an analog filter with  say 
> less than 0.3Hz cutoff frequency similar to the Z3801A circuitry. In this  
> case the coarsedac can probably even be exchanged for a simple high-stability  
> pot.
>  
>   
Synchronous filtering of the DAC output would result in much faster
settling times with low modulation artifacts.
> It does require a bit of real time firmware to do the PWM enhancement of  
> course.
>  
> bye,
> Said
>  
>  
>   
The technique advocated in the article may have fewer artifacts due to
DAC settling time issues.
Its also a lot cheaper since very tight tolerance stable components
aren't required.
The output should also be somewhat quieter.

Bruce


From phk at phk.freebsd.dk  Tue Dec  2 08:25:00 2008
From: phk at phk.freebsd.dk (Poul-Henning Kamp)
Date: Tue, 02 Dec 2008 08:25:00 +0000
Subject: [time-nuts] V standards
In-Reply-To: Your message of "Tue, 02 Dec 2008 02:18:45 EST."
	<bef.38541c00.36663b55@aol.com> 
Message-ID: <2194.1228206300@critter.freebsd.dk>

In message <bef.38541c00.36663b55 at aol.com>, SAIDJACK at aol.com writes:

>Coarsedac changes are an issue as you mentioned, but one can get around  them 
>by scaling the two dacs in a way to only use a couple of bits from the  
>coarsedac, and operate most of the time using just the fine dac.

If you are controlling this with a microcontroller, there is an alternative
you should consider:

Use only a single DAC and then PWM modulate its output, followed
by a low-pass filter.

-- 
Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk at FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.


From richiem at hughes.net  Tue Dec  2 08:43:51 2008
From: richiem at hughes.net (Richard Moore)
Date: Tue, 2 Dec 2008 00:43:51 -0800
Subject: [time-nuts] V standards
In-Reply-To: <mailman.532.1228206303.2542.time-nuts@febo.com>
References: <mailman.532.1228206303.2542.time-nuts@febo.com>
Message-ID: <58C70987-017E-44ED-BF07-D578679C03C2@hughes.net>

On Dec 2, 2008, at 12:25 AM, Bruce and PHK wrote:

>> <clip>
>> There was a recent Design Idea in EDN or Electronic Design (don't  
>> remember
>> which one) where someone claimed 32 bit resolution out of two 16  
>> bit dacs. That
>>  claim is ridiculous of course due to noise and matching etc, but  
>> you can
>> probably get 20 - 24 bits resolution and accuracy out of a  
>> cascaded system with
>> some care.
>>
>> bye,
>> Said
>>
> If you build this circuit using the values shown in the schematic you
> won't actually achieve 20 bits performance.
> One of the resistor values is incorrect.
> The resistor matching requirements aren't anywhere near as  
> stringent as
> one may think on first glance.
> With some subtle alterations to the operating mode the resistor ratio
> matching tolerances can be relaxed considerably.
> In closed loop digital control systems the circuit noise should be at
> least 1LSB or so to maximise performance.
> The trick is to increase the DAC resolution until this condition is
> achieved and not increase the noise to meet the condition.
> 20 bit resolution performance is easy to achieve, 24 bit performance
> requires 2 a little more work.
>
> Actually monotonicity to about 26 bits was claimed with noise a bit
> below 1ppm.
> However since the noise varies with the DAC output such claims are
> perhaps a little too simplistic.
> The noise can be reduced when required by using a better reference.
> Any drift in DAC gain and offset could be compensated by a Kalman  
> filter
> should they become significant.
>
> The major advantage of such a DAC is the inherent monotonicity which
> cannot be achieved and maintained (around coarse DAC transitions)
> without frequent calibration when the outputs of 2 16 bit DACs are  
> combined.
>
> Bruce

Bruce, is there a way for non-subscribers to see this article?

Dick Moore

> ------------------------------
>
> Message: 8
> Date: Tue, 02 Dec 2008 08:25:00 +0000
> From: "Poul-Henning Kamp" <phk at phk.freebsd.dk>
> Subject: Re: [time-nuts] V standards
>
>> Coarsedac changes are an issue as you mentioned, but one can get  
>> around  them
>> by scaling the two dacs in a way to only use a couple of bits from  
>> the
>> coarsedac, and operate most of the time using just the fine dac.
>
> If you are controlling this with a microcontroller, there is an  
> alternative
> you should consider:
>
> Use only a single DAC and then PWM modulate its output, followed
> by a low-pass filter.
>
> -- 
> Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
> phk at FreeBSD.ORG         | TCP/IP since RFC 956
> FreeBSD committer       | BSD since 4.3-tahoe
> Never attribute to malice what can adequately be explained by  
> incompetence.
>

Poul, how do I PWM a DAC that is itself a PWM device? This question  
is prompted by the DAC I'm using in Bert Zauhar's FLL GPSDO, which is  
a dithered 10-bit DAC in a PIC chip that results in 14-bit  
resolution. I'd like to have a simple way to get 2 to 4 extra bits of  
resolution out of this. Can you recommend some design resources to do  
this?

Dick Moore


From phk at phk.freebsd.dk  Tue Dec  2 08:47:26 2008
From: phk at phk.freebsd.dk (Poul-Henning Kamp)
Date: Tue, 02 Dec 2008 08:47:26 +0000
Subject: [time-nuts] V standards
In-Reply-To: Your message of "Tue, 02 Dec 2008 00:43:51 PST."
	<58C70987-017E-44ED-BF07-D578679C03C2@hughes.net> 
Message-ID: <2364.1228207646@critter.freebsd.dk>

In message <58C70987-017E-44ED-BF07-D578679C03C2 at hughes.net>, Richard Moore wri
tes:

>> If you are controlling this with a microcontroller, there is an  
>> alternative
>> you should consider:
>>
>> Use only a single DAC and then PWM modulate its output, followed
>> by a low-pass filter.
>
>Poul, how do I PWM a DAC that is itself a PWM device? This question  
>is prompted by the DAC I'm using in Bert Zauhar's FLL GPSDO, which is  
>a dithered 10-bit DAC in a PIC chip that results in 14-bit  
>resolution. I'd like to have a simple way to get 2 to 4 extra bits of  
>resolution out of this. Can you recommend some design resources to do  
>this?

I would simply cummutate the DAC output with a PWM controlled fet or
CMOS switch.

-- 
Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk at FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.


From bruce.griffiths at xtra.co.nz  Tue Dec  2 09:05:15 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Tue, 02 Dec 2008 22:05:15 +1300
Subject: [time-nuts] V standards
In-Reply-To: <2194.1228206300@critter.freebsd.dk>
References: <2194.1228206300@critter.freebsd.dk>
Message-ID: <4934FA4B.6040707@xtra.co.nz>

Poul-Henning Kamp wrote:
> In message <bef.38541c00.36663b55 at aol.com>, SAIDJACK at aol.com writes:
>
>   
>> Coarsedac changes are an issue as you mentioned, but one can get around  them 
>> by scaling the two dacs in a way to only use a couple of bits from the  
>> coarsedac, and operate most of the time using just the fine dac.
>>     
>
> If you are controlling this with a microcontroller, there is an alternative
> you should consider:
>
> Use only a single DAC and then PWM modulate its output, followed
> by a low-pass filter.
>
>   
The trouble with this approach is the very long filter time constants
with  24 bit PWM.
Combining 2 16 bit PWM outputs requires relatively close tolerance
components.
A synchronous filter is far more effective.

Bruce


From bruce.griffiths at xtra.co.nz  Tue Dec  2 09:09:13 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Tue, 02 Dec 2008 22:09:13 +1300
Subject: [time-nuts] V standards
In-Reply-To: <2364.1228207646@critter.freebsd.dk>
References: <2364.1228207646@critter.freebsd.dk>
Message-ID: <4934FB39.6030604@xtra.co.nz>

Poul-Henning Kamp wrote:
> In message <58C70987-017E-44ED-BF07-D578679C03C2 at hughes.net>, Richard Moore wri
> tes:
>
>   
>>> If you are controlling this with a microcontroller, there is an  
>>> alternative
>>> you should consider:
>>>
>>> Use only a single DAC and then PWM modulate its output, followed
>>> by a low-pass filter.
>>>       
>> Poul, how do I PWM a DAC that is itself a PWM device? This question  
>> is prompted by the DAC I'm using in Bert Zauhar's FLL GPSDO, which is  
>> a dithered 10-bit DAC in a PIC chip that results in 14-bit  
>> resolution. I'd like to have a simple way to get 2 to 4 extra bits of  
>> resolution out of this. Can you recommend some design resources to do  
>> this?
>>     
>
> I would simply cummutate the DAC output with a PWM controlled fet or
> CMOS switch.
>
>   
You can either do this with the filtered DAC output and filter the
result, or with some ingenuity just combine the unfiltered PWM outputs
and then filter the result with a single low pass filter.

Bruce


From bruce.griffiths at xtra.co.nz  Tue Dec  2 09:15:00 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Tue, 02 Dec 2008 22:15:00 +1300
Subject: [time-nuts] V standards
In-Reply-To: <58C70987-017E-44ED-BF07-D578679C03C2@hughes.net>
References: <mailman.532.1228206303.2542.time-nuts@febo.com>
	<58C70987-017E-44ED-BF07-D578679C03C2@hughes.net>
Message-ID: <4934FC94.3060409@xtra.co.nz>

Richard Moore wrote:
> On Dec 2, 2008, at 12:25 AM, Bruce and PHK wrote:
>
>   
>>> <clip>
>>> There was a recent Design Idea in EDN or Electronic Design (don't  
>>> remember
>>> which one) where someone claimed 32 bit resolution out of two 16  
>>> bit dacs. That
>>>  claim is ridiculous of course due to noise and matching etc, but  
>>> you can
>>> probably get 20 - 24 bits resolution and accuracy out of a  
>>> cascaded system with
>>> some care.
>>>
>>> bye,
>>> Said
>>>
>>>       
>> If you build this circuit using the values shown in the schematic you
>> won't actually achieve 20 bits performance.
>> One of the resistor values is incorrect.
>> The resistor matching requirements aren't anywhere near as  
>> stringent as
>> one may think on first glance.
>> With some subtle alterations to the operating mode the resistor ratio
>> matching tolerances can be relaxed considerably.
>> In closed loop digital control systems the circuit noise should be at
>> least 1LSB or so to maximise performance.
>> The trick is to increase the DAC resolution until this condition is
>> achieved and not increase the noise to meet the condition.
>> 20 bit resolution performance is easy to achieve, 24 bit performance
>> requires 2 a little more work.
>>
>> Actually monotonicity to about 26 bits was claimed with noise a bit
>> below 1ppm.
>> However since the noise varies with the DAC output such claims are
>> perhaps a little too simplistic.
>> The noise can be reduced when required by using a better reference.
>> Any drift in DAC gain and offset could be compensated by a Kalman  
>> filter
>> should they become significant.
>>
>> The major advantage of such a DAC is the inherent monotonicity which
>> cannot be achieved and maintained (around coarse DAC transitions)
>> without frequent calibration when the outputs of 2 16 bit DACs are  
>> combined.
>>
>> Bruce
>>     
>
> Bruce, is there a way for non-subscribers to see this article?
>
> Dick Moore
>
>   
It should be publicly available by now, just use google with search
terms like: EDN PWM 32 bit DAC.
However there are some design errors some of which are relatively benign
others which may result in component destruction.

Bruce



From df6jb at ulrich-bangert.de  Tue Dec  2 09:59:05 2008
From: df6jb at ulrich-bangert.de (Ulrich Bangert)
Date: Tue, 2 Dec 2008 10:59:05 +0100
Subject: [time-nuts] Thunderbolt settings
In-Reply-To: <C0096F46-CD13-40AC-BDFD-0E1D6DC8085C@hughes.net>
Message-ID: <5AEA96C9C37B43C6B1F19697C5B5F546@athlon>

Dick,

to be honest, I did even some more things concerning the TBolt. Find
attached the results of an measurement where the oscillator disciplining
has been disabled and the internal PPS comparison has been logged over
some time. So it is free running OCXO vs. GPS. The falling slope in the
left is much due to GPS jitter averaging out with longer observation
times. The ascending slope is much due to the OCXO reacting to
environmental conditions. This measurement would indicate that 1000-2000
s is a good value for the time constant. However, I did not have the
heart yet to use such a big value. Neveretheless I use 1200 s TC in my
DIY GPSDO made from an M12+ and an FTS1200. 

I think that also an clarification is necessary what exactly different
manufactures mean by "time constant". I am using the term "time
constant" in the same sense as Stanford Research do in their PRS10
manual, where they talk about the pll's "natural time constant". When a
sudden step in OCXO frequency is noticed by the pll it will react to it
by changing the EFC voltage. It is exactly the "natural time constant"
that the pll needs to bring the OCXO frequency to its original value.
The pll reaction as a whole lasts much longer since it wants to bring
the phase difference back to zero.

Best regards
Ulrich   

> -----Ursprungliche Nachricht-----
> Von: time-nuts-bounces at febo.com 
> [mailto:time-nuts-bounces at febo.com] Im Auftrag von Richard Moore
> Gesendet: Montag, 1. Dezember 2008 22:00
> An: time-nuts at febo.com
> Betreff: Re: [time-nuts] Thunderbolt settings
> 
> 
> 
> On Dec 1, 2008, at 7:08 AM, Chuck and Ulrich  wrote:
> 
> > ------------------------------
> >
> > Message: 2
> > Date: Mon, 01 Dec 2008 09:02:33 -0500
> > From: Chuck Harris <cfharris at erols.com>
> > Subject: Re: [time-nuts] Thunderbolt settings -- one more time
> >
> > The T-Bolt is designed to be a turn key system, and is 
> already set up 
> > for the best operation the factory knew how to achieve. I 
> doubt that 
> > anyone has spent much time diddling the time constants.
> >
> > -Chuck Harris
> 
> Thx, Chuck for your reply.
> >
> > ------------------------------
> >
> > Message: 3
> > Date: Mon, 1 Dec 2008 16:08:44 +0100
> > From: "Ulrich Bangert" <df6jb at ulrich-bangert.de>
> > Subject: Re: [time-nuts] Thunderbolt settings -- one more time
> >
> > Chuck and Dick,
> >
> >> The T-Bolt is designed to be a turn key system, and is 
> already set up 
> >> for the best operation the factory knew how to achieve.
> >
> > Yes and no! Clearly the factory settings have to be so that 
> a lock of 
> > the pll is possible within a reasonable time, say minutes 
> to hours or 
> > so. With a freshly powered OCXO the initial aging effects 
> can be that 
> > large that really short time constants as the default 100 s of the 
> > Thunderbolt are necessary.
> >
> > I attach a measurement that I made on a freshly powered up HP10811
> > some
> > years ago. Note: This was by no means a new device but one that had
> > already thousands of hours lifetime. Clearly any regulation 
> loop will
> > need short time constants to follow this initial aging. 
> Note that the
> > aging effects are that big that frequency changes due to diurnal
> > temperature changes in my flat are not visible! Temperature has
> > otherwise the biggest impact of all environmental parameters on
> > oscillator stability.
> >
> > After some weeks of continuous (!) operation the time 
> constant of the 
> > Thunderbolt loop may be set to higher values. Mine 
> currently runs at 
> > 500.0 s. Some tests indicate that the time constant may 
> even be set a 
> > bit higher. I have made experiments on time constants with 
> a number of 
> > different gps receivers and different OCXOs (including RBs). As an 
> > overall result it turned out that TCs > 1500 s are impraticcal in a 
> > normal living environment. With some degrees Centigrade temperature 
> > changes in a typical center European environment along the 
> day that is 
> > the maximum time that allows the loop to follow the temperature
> > changes.
> > This includes RBs which have an measurable coefficient of 
> temperature
> > too.
> >
> > Best regards
> > Ulrich
> >
> >>
> >> Richard Moore wrote:
> >>> Dear nuts --
> >>>
> >>> Let me see if I can ask this in a way that will prompt 
> you to supply 
> >>> some input:
> >>>
> >>> What is the maximum Loop time constant the TBolt (or perhaps the 
> >>> TBolt monitor sw) will accept as input? What TCs are you TBolt 
> >>> owners using?
> >>>
> >>> Thx,
> >>> Dick Moore
> >>>
> >>> -------------- next part --------------
> > A non-text attachment was scrubbed...
> > Name: HP10811.pdf
> > Type: application/pdf
> > Size: 17055 bytes
> > Desc: not available
> > Url : http://www.febo.com/pipermail/time-nuts/attachments/20081201/
> > f7077c5e/attachment.pdf
> >
> > ------------------------------
> 
> Thanks Ulrich. The default TC on my used TBolt was 100.0s. I ran it  
> for a couple of days and it was stable with a very low level 
> of total  
> DAC change -- about +10mV. After a few more days, and after 
> looking a  
> various ADEV plots, particularly yours, Ulrich, I set the TC to  
> 1000.0 sec. It refuses to take 10,000 sec, but I haven't 
> explored the  
> limits of what it will accept, and was hoping, since Trimble won't  
> tell me in the docs the acceptable ranges of anything you can 
> adjust,  
> that one of you would know.
> 
> Dick Moore
> 
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to 
> https://www.febo.com/cgi-> bin/mailman/listinfo/time-nuts
> and 
> follow the instructions there.
> 
-------------- next part --------------
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From warrensjmail-one at yahoo.com  Tue Dec  2 12:24:03 2008
From: warrensjmail-one at yahoo.com (WarrenS)
Date: Tue, 2 Dec 2008 04:24:03 -0800
Subject: [time-nuts]  V standards
Message-ID: <040b01c95478$ddb42830$6401a8c0@WSOffice>

Dick

Here is one way to add 2 LS  bits (or more) to any Dac no matter how it is made.
This assumes that the Dac that you are adding these bits to is 0 to 5 volts Fullscale 
and accurate enough to justify adding LS bits.

To add 2 LS bits to a 14 bit Dac.
An easy ways to do it is NOT to use PWM.
That way it needs no filtering and no PWM 
and few software resources, maybe none. 
The added 15th Bit wants to add  1 / 32,768 of 5 volts 
The added bit #16 wants to add 1 / 65,536 of 5 volts 

As a universal solution, Add a small resistor at the output of the 14 bit Dac 
of Value R (say 10  to 100 ohms).

From james.p.lux at jpl.nasa.gov  Tue Dec  2 13:34:20 2008
From: james.p.lux at jpl.nasa.gov (Lux, James P)
Date: Tue, 2 Dec 2008 05:34:20 -0800
Subject: [time-nuts] Soundcard sampling Re:  Picking a good HP 10811
In-Reply-To: <4934DCAF.5000606@xtra.co.nz>
Message-ID: <C55A795C.30E8%James.P.Lux@jpl.nasa.gov>




On 12/1/08 10:58 PM, "Bruce Griffiths" <bruce.griffiths at xtra.co.nz> wrote:


> Thus it may well be worthwhile doing this as one then (in principle)
> only needs 3 mixers (plus 3 simultaneously sampled sound card input
> channels) and no offset source, however the maximum achievable offset
> will probably result in beat frequencies that are a little too low for a
> sound card ADC.

Most sound cards roll off below around 10-20 Hz, or, at least, you're
starting to get into the roll off filter characteristic where the phase is
changing rapidly.

Re: "simultaneously sampled"...  I would assume that sample jitter here
affects the measurement.  Granted, one can do a fit of many samples to a
sine wave, and get a sqrt(N) improvement (if it's random jitter, and not
systematic), but what's a typical spec for channel/channel jitter on a sound
card?  Or, more properly, if you're measuring an Allan deviation of, say,
1E-15 over 100 seconds for a couple 10MHz sources beaten down to, say, 100
Hz or thereabouts.. How good does it need to be?



From phk at phk.freebsd.dk  Tue Dec  2 13:48:55 2008
From: phk at phk.freebsd.dk (Poul-Henning Kamp)
Date: Tue, 02 Dec 2008 13:48:55 +0000
Subject: [time-nuts] V standards
In-Reply-To: Your message of "Tue, 02 Dec 2008 22:05:15 +1300."
	<4934FA4B.6040707@xtra.co.nz> 
Message-ID: <9264.1228225735@critter.freebsd.dk>

In message <4934FA4B.6040707 at xtra.co.nz>, Bruce Griffiths writes:

>> Use only a single DAC and then PWM modulate its output, followed
>> by a low-pass filter.
>>   
>The trouble with this approach is the very long filter time constants
>with  24 bit PWM.

You don't want 24bit PWM, you want to combine a normal DAC with
PWM modulation.

The disadvantage is that the result is not linear.  But it is
monotonic and approximately the lower 4/5th of the distinct
combinations are practically useful.

Take the Analog Devices ADUC7026 ARM7 microcontroller as example:

It has a 12bit DAC of pretty decent quality and a 16 bit PWM running
at 42 MHz.

If you just use 10 PWM bits, that gives you a PWM frequency of 20kHz,
easily filtered to DC by simple means.

Modulate the DAC output with the PWM and you get 1,353,354 unique
settings of which about the first million is usable.

That's about 6 additional DAC bits with the added advantage, that
if you prioritize the PWM for the low bits, you will get better
step regularity than the DAC would give you.

(Didn't somebody say that Fluke used PWM methods in their voltage
calibrators ?  Would make a lot of sense if they did...)

If you use 14 bit PWM you get a 1281 Hz PWM frequency,
requiring more careful filtering, but giving you 20,384,526
distinct output combinations, with usable linearity up to about
for the first 16 million combinations, so that is approximately
a 24 bit DAC.

Full 16 bit PWM results in 321 Hz PWM frequency which means tricky
and likely impractical filtering, but you get 86,616,948 distinct
output combinations of which you can use approximately 65 million,
so that is around a 26bit dac.

Or 12-20 nanovolts between steps, if you prefer.

The _real_ trouble with this aproach, is that you get "interleaved
gears" like on a bike: you need either a (huge) table or a bit of
code to tell you what the neighboring codes are.

Fortunately, finding a neighboring code is pretty easy, as the
relevant searchspace is pretty limited, so for EFC control of
an OCXO this is not a practical problem.

Poul-Henning

-- 
Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk at FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.


From aceamusements at mchsi.com  Tue Dec  2 14:15:34 2008
From: aceamusements at mchsi.com (aceamusements at mchsi.com)
Date: Tue, 02 Dec 2008 14:15:34 +0000
Subject: [time-nuts] Thoughts on Cs tube failure modes
Message-ID: <120220081415.16775.493543060003C53100004187219792676103010CD2079C080C03BF9C9B020A030A9C9A030E0A0C0E@mchsi.com>

hi,

I sent u a few emails back about a year ago when I purchased my brand new 5071a
and had a strange continuous drop in the emult voltage since power up(on jan 2
of this year)about 1-2 volts per day,I later found out this was normal with a
new tube and it should level off and then start to rise before it dies 5-6 years
form now

 so far the emult has stabilized at 1203v and has not started to rise after a
slow fall(over 6 months,started when new at over 1550v).


what I have also noticed though is the ion pump has risen slowly in this period
from .2UA to 4.8UA  slowly over time,I have tried both unplugging the unit for a
few days and restarting it in standby which lowers it a small amount (to about
3.2 but when I turn the unit on into operate it just goes back up to about 4.5
to 5.5ua..Is this normal or possibly a contaminated tube?I still have two years
warranty on the tube,but this unit was sitting in storage over 3 years since I
purchased it new and unopened carton..(one interesting note the pump current
which I have checked every few days has very slowly risen since power on 11
months ago and even after reset will always go back up to about 5Ua (even though
this tube never, when new, was over .6ua in standby( usually.2ua operate
.6ua?)any ideas why this would occur?

Other than the rise in pump current the unit has worked fine since unpacking out
of the box..Thanks David..



----------------------  Original Message:  ---------------------
From:    Corby Dawson <cdelect at juno.com>
To:      time-nuts at febo.com
Cc:      time-nuts at febo.com
Subject: Re: [time-nuts] Thoughts on Cs tube failure modes
Date:    Sun, 30 Nov 2008 18:35:27 +0000

> John,
> 
> What you describe with the ion pump curent is normal if the tube has been
> powerd off for a long time.
> 
> Th mainframe normally would turn the oven and ionizer filaments off when
> the ion pump current pegged.
> 
> After minutes (can be quite a few minutes) the ion pump current will drop
> as it pumps the surge of outgassing from the heated filaments.
> 
> The cycle repeats and can take a couple days on a stubborn tube.
> 
> You bypassed that circuit so I'm not sure how much gas you introduced.
> 
> If after a couple days the current is still pegged try connecting an
> external high voltage supply of around +3000VDC that can provide at least
> 5ma. (turn unit off)
> 
> Let it run overnight and if the current comes down reconnect the internal
> power supply and turn the mainframe back on.
> 
> You probably will see it peg again and the see the oven shut down (it
> happens fast!), just leave it on and it should start cycling and
> eventually the filaments will reach the oven set points and have
> outgassed enough so that the protective circuit will not trip.
> 
> Then you can try to see if the rest of the tube has any life. (you may
> have to reduce the oven set resistor to 130 ohms as well as reducing its
> companion overtemp resistor. This is the value the Navy uses to get the
> last bit of life out of the tube, don't do it if you can get the rated
> beam current at the original value!)
> 
> If you email me I can give you my evening phone number if you need some
> more info.
> 
> Corby Dawson
> cdelect at juno.com
> 
> 
> 
> 
>  
> ____________________________________________________________
> Click here to find the perfect picture with our powerful photo search features.
> http://thirdpartyoffers.juno.com/TGL2141/fc/PnY6rw1aBm8XXBA9eC72NBG9alhmVMe3ZD9u
> ri8B4mlt3xxDXctvb/
> 
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.


From dibene at usa.net  Tue Dec  2 14:17:16 2008
From: dibene at usa.net (Alberto di Bene)
Date: Tue, 02 Dec 2008 15:17:16 +0100
Subject: [time-nuts] V standards
In-Reply-To: <040b01c95478$ddb42830$6401a8c0@WSOffice>
References: <040b01c95478$ddb42830$6401a8c0@WSOffice>
Message-ID: <4935436C.9070609@usa.net>

WarrenS wrote:
> Dick
> 
> Here is one way to add 2 LS  bits (or more) to any Dac no matter how it is made.
> This assumes that the Dac that you are adding these bits to is 0 to 5 volts Fullscale 
> and accurate enough to justify adding LS bits.
> 
> To add 2 LS bits to a 14 bit Dac.
> An easy ways to do it is NOT to use PWM.
> That way it needs no filtering and no PWM 
> and few software resources, maybe none. 
> The added 15th Bit wants to add  1 / 32,768 of 5 volts 
> The added bit #16 wants to add 1 / 65,536 of 5 volts 
   ----- snip -----

In a GPSDO I designed and built about 4 - 5 years ago, I obtained almost 20-bit resolution without using any DAC,
I used the PWM of the Atmel AVR AT90S8535, which has a resolution of 10 bits. Then I changed the limits on the voltage 
ramp that define the switch over points of the PWM, subdividing them into 1024 intervals, which means another 10 bits.
I used the DDA (Digital Dithering Algorithm) method to minimize the amplitude of the about 4 Hz ripple generated on the 
EFC voltage by this technique. A low pass filter with a theoretical attenuation of 120dB at 3.9 Hz was then used before 
applying the EFC voltage to the Isotemp OCXO 134 I used in the project.  It worked.  I still have the Atmel assembly 
code, should someone be interested.

73  Alberto  I2PHD
P.S. The square wave produced by the PWM was conditioned with an MC1503U so to make it independent of the supply voltage 
of the Atmel processor.




From bruce.griffiths at xtra.co.nz  Tue Dec  2 18:39:18 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Wed, 03 Dec 2008 07:39:18 +1300
Subject: [time-nuts] Soundcard sampling Re:  Picking a good HP 10811
In-Reply-To: <C55A795C.30E8%James.P.Lux@jpl.nasa.gov>
References: <C55A795C.30E8%James.P.Lux@jpl.nasa.gov>
Message-ID: <493580D6.3030005@xtra.co.nz>

Lux, James P wrote:
>
> On 12/1/08 10:58 PM, "Bruce Griffiths" <bruce.griffiths at xtra.co.nz> wrote:
>
>
>   
>> Thus it may well be worthwhile doing this as one then (in principle)
>> only needs 3 mixers (plus 3 simultaneously sampled sound card input
>> channels) and no offset source, however the maximum achievable offset
>> will probably result in beat frequencies that are a little too low for a
>> sound card ADC.
>>     
>
> Most sound cards roll off below around 10-20 Hz, or, at least, you're
> starting to get into the roll off filter characteristic where the phase is
> changing rapidly.
>
> Re: "simultaneously sampled"...  I would assume that sample jitter here
> affects the measurement.  Granted, one can do a fit of many samples to a
> sine wave, and get a sqrt(N) improvement (if it's random jitter, and not
> systematic), but what's a typical spec for channel/channel jitter on a sound
> card?  Or, more properly, if you're measuring an Allan deviation of, say,
> 1E-15 over 100 seconds for a couple 10MHz sources beaten down to, say, 100
> Hz or thereabouts.. How good does it need to be?
>
>   
The differential sampling jitter between channels would probably have to
be less than a 100ps or so a little more if its random.
Preliminary tests with a high end sound card appear to demonstrate a
system noise level below 1E-15 at tau = 100 sec.

Bruce


From bruce.griffiths at xtra.co.nz  Tue Dec  2 19:04:29 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Wed, 03 Dec 2008 08:04:29 +1300
Subject: [time-nuts] V standards
In-Reply-To: <9264.1228225735@critter.freebsd.dk>
References: <9264.1228225735@critter.freebsd.dk>
Message-ID: <493586BD.80002@xtra.co.nz>

Poul-Henning Kamp wrote:
> In message <4934FA4B.6040707 at xtra.co.nz>, Bruce Griffiths writes:
>
>   
>>> Use only a single DAC and then PWM modulate its output, followed
>>> by a low-pass filter.
>>>   
>>>       
>> The trouble with this approach is the very long filter time constants
>> with  24 bit PWM.
>>     
>
> You don't want 24bit PWM, you want to combine a normal DAC with
> PWM modulation.
>
>   
24 bit PWM can work well with synchronous filtering and a high frequency
PWM clock.
> The disadvantage is that the result is not linear.  But it is
> monotonic and approximately the lower 4/5th of the distinct
> combinations are practically useful.
>
> Take the Analog Devices ADUC7026 ARM7 microcontroller as example:
>
> It has a 12bit DAC of pretty decent quality and a 16 bit PWM running
> at 42 MHz.
>
> If you just use 10 PWM bits, that gives you a PWM frequency of 20kHz,
> easily filtered to DC by simple means.
>
> Modulate the DAC output with the PWM and you get 1,353,354 unique
> settings of which about the first million is usable.
>
> That's about 6 additional DAC bits with the added advantage, that
> if you prioritize the PWM for the low bits, you will get better
> step regularity than the DAC would give you.
>
> (Didn't somebody say that Fluke used PWM methods in their voltage
> calibrators ?  Would make a lot of sense if they did...)
>
>   
eg Fluke 5700A etc.
Fluke have a string of patents relating to PWM as used in their calibrators.
e.g.
US5402082
US4716398
One of which shows how to virtually eliminate integral nonlinearity due
to analog switch on resistance mismatch and on resistance modulation.
Improvements to these techniques are possible. However in an EFC DAC
integral nonlinearity isnt particularly critical, monotonicity is.
> If you use 14 bit PWM you get a 1281 Hz PWM frequency,
> requiring more careful filtering, but giving you 20,384,526
> distinct output combinations, with usable linearity up to about
> for the first 16 million combinations, so that is approximately
> a 24 bit DAC.
>
> Full 16 bit PWM results in 321 Hz PWM frequency which means tricky
> and likely impractical filtering, but you get 86,616,948 distinct
> output combinations of which you can use approximately 65 million,
> so that is around a 26bit dac.
>
>   
Adequate filtering relatively easy and practical if one uses a
synchronous filter.
> Or 12-20 nanovolts between steps, if you prefer.
>
> The _real_ trouble with this aproach, is that you get "interleaved
> gears" like on a bike: you need either a (huge) table or a bit of
> code to tell you what the neighboring codes are.
>
> Fortunately, finding a neighboring code is pretty easy, as the
> relevant searchspace is pretty limited, so for EFC control of
> an OCXO this is not a practical problem.
>
> Poul-Henning
>
>   
There is a transient EFC voltage error at coarse DAC transitions whilst
the fine DAC is adjusted to compensate for DAC mismatch error.

The reference noise and drift (not important if its slow enough) will
limit the achievable resolution.
In principle software compensation of thermal drift and aging is
possible however flicker noise will still be a limiting factor.
A quieter reference may be needed in critical cases where the OCXO noise
isn't dominant.

Bruce


From biwa at att.net  Tue Dec  2 19:26:34 2008
From: biwa at att.net (Burt I. Weiner)
Date: Tue, 02 Dec 2008 11:26:34 -0800
Subject: [time-nuts] Tektronix DC-5010 DVM...
Message-ID: <7.0.0.16.2.20081202112202.037b5470@att.net>

Since we're on the subject of Digital Voltmeters, accuracy and such, 
I'm wondering if anyone in the group has an opinion regarding the 
Tektronix DC-5010 DVM.  I just want a good, reliable bench DVM and 
would like to be able to stuff it in my TM-5006 frame.  Any thoughts 
or suggestions?

Burt, K6OQK

Burt I. Weiner Associates
Broadcast Technical Services
Glendale, California  U.S.A.
biwa at att.net
K6OQK 



From bruce.griffiths at xtra.co.nz  Tue Dec  2 19:28:18 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Wed, 03 Dec 2008 08:28:18 +1300
Subject: [time-nuts] Soundcard sampling Re:  Picking a good HP 10811
In-Reply-To: <C55A795C.30E8%James.P.Lux@jpl.nasa.gov>
References: <C55A795C.30E8%James.P.Lux@jpl.nasa.gov>
Message-ID: <49358C52.9070600@xtra.co.nz>

Lux, James P wrote:
>
> On 12/1/08 10:58 PM, "Bruce Griffiths" <bruce.griffiths at xtra.co.nz> wrote:
>
>
>   
>> Thus it may well be worthwhile doing this as one then (in principle)
>> only needs 3 mixers (plus 3 simultaneously sampled sound card input
>> channels) and no offset source, however the maximum achievable offset
>> will probably result in beat frequencies that are a little too low for a
>> sound card ADC.
>>     
>
> Most sound cards roll off below around 10-20 Hz, or, at least, you're
> starting to get into the roll off filter characteristic where the phase is
> changing rapidly.
>
> Re: "simultaneously sampled"...  I would assume that sample jitter here
> affects the measurement.  Granted, one can do a fit of many samples to a
> sine wave, and get a sqrt(N) improvement (if it's random jitter, and not
> systematic), but what's a typical spec for channel/channel jitter on a sound
> card?  Or, more properly, if you're measuring an Allan deviation of, say,
> 1E-15 over 100 seconds for a couple 10MHz sources beaten down to, say, 100
> Hz or thereabouts.. How good does it need to be?
>
>
>   
Being a consumer item the sampling jitter of a sound card isn't usually
specified however 100ps jitter should have a very noticeable effect on
the performance of a high end 24 bit sound card.

Bruce


From biwa at att.net  Tue Dec  2 19:29:38 2008
From: biwa at att.net (Burt I. Weiner)
Date: Tue, 02 Dec 2008 11:29:38 -0800
Subject: [time-nuts] Tektronix DM-5010 DVM...
Message-ID: <7.0.0.16.2.20081202112758.00f00620@att.net>

Sorry, I meant the DM-5010 DVM.

Burt, K6OQK

Since we're on the subject of Digital Voltmeters, accuracy and such, 
I'm wondering if anyone in the group has an opinion regarding the 
Tektronix DC-5010 DVM.  I just want a good, reliable bench DVM and 
would like to be able to stuff it in my TM-5006 frame.  Any thoughts 
or suggestions?

Burt, K6OQK

Burt I. Weiner Associates
Broadcast Technical Services
Glendale, California  U.S.A.
biwa at att.net
K6OQK  



From bruce.griffiths at xtra.co.nz  Tue Dec  2 20:08:43 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Wed, 03 Dec 2008 09:08:43 +1300
Subject: [time-nuts] Soundcard sampling Re:  Picking a good HP 10811
In-Reply-To: <493580D6.3030005@xtra.co.nz>
References: <C55A795C.30E8%James.P.Lux@jpl.nasa.gov>
	<493580D6.3030005@xtra.co.nz>
Message-ID: <493595CB.6080407@xtra.co.nz>

Bruce Griffiths wrote:
> Lux, James P wrote:
>   
>> On 12/1/08 10:58 PM, "Bruce Griffiths" <bruce.griffiths at xtra.co.nz> wrote:
>>
>>
>>   
>>     
>>> Thus it may well be worthwhile doing this as one then (in principle)
>>> only needs 3 mixers (plus 3 simultaneously sampled sound card input
>>> channels) and no offset source, however the maximum achievable offset
>>> will probably result in beat frequencies that are a little too low for a
>>> sound card ADC.
>>>     
>>>       
>> Most sound cards roll off below around 10-20 Hz, or, at least, you're
>> starting to get into the roll off filter characteristic where the phase is
>> changing rapidly.
>>
>> Re: "simultaneously sampled"...  I would assume that sample jitter here
>> affects the measurement.  Granted, one can do a fit of many samples to a
>> sine wave, and get a sqrt(N) improvement (if it's random jitter, and not
>> systematic), but what's a typical spec for channel/channel jitter on a sound
>> card?  Or, more properly, if you're measuring an Allan deviation of, say,
>> 1E-15 over 100 seconds for a couple 10MHz sources beaten down to, say, 100
>> Hz or thereabouts.. How good does it need to be?
>>
>>   
>>     
> The differential sampling jitter between channels would probably have to
> be less than a 100ps or so a little more if its random.
> Preliminary tests with a high end sound card appear to demonstrate a
> system noise level below 1E-15 at tau = 100 sec.
>
> Bruce
>
>   
Oops I omitted a factor of 100.
The differential sampling jitter would need to be less than about 10ns.
Practically all high end sound cards should easily meet this spec.

The sampling clock jitter spec for a given SNR and oversampling ration is

 jitter < SQRT(OSR)/(2*PI*SNR)
OSR = oversampling ratio
SNR = signal to noise ratio

e.g. with a 100dB SNR a 10KHz input and an OSR of 9.6 (192kHz)
The sampling jitter needs to be < 500ps rms.

with a 100dB SNR a 1kHz input and an OSR of 96
the sampling jitter needs to be < 15.6 ns rms.

Bruce



From cdelect at juno.com  Tue Dec  2 20:13:28 2008
From: cdelect at juno.com (Corby Dawson)
Date: Tue, 2 Dec 2008 12:13:28 -0800
Subject: [time-nuts] Thoughts on Cs tube failure modes
	(aceamusements@mchsi.com)
Message-ID: <20081202.121328.3280.0.cdelect@juno.com>

What you describe could be "whiskers"  growing in the ion pump. 

They do not affect the pumping until they grow big enough to load the
supply past its current capability.

You can sometimes remove them using a hand held brush discharge tester.
(Remove tube from chassis before doing this!)

I would not try this until the current rises enough to cut off the ovens.

Your current is still quite low.

Corby Dawson
____________________________________________________________
Click for online loan, fast & no lender fee, approval today
http://thirdpartyoffers.juno.com/TGL2141/fc/PnY6rw2P5sfvOI6bGtiN2n7zim31rTbaVcvHcKkQJU7GhZyFH6zWB/


From richiem at hughes.net  Tue Dec  2 20:27:45 2008
From: richiem at hughes.net (Richard Moore)
Date: Tue, 2 Dec 2008 12:27:45 -0800
Subject: [time-nuts] Thunderbolt settings
In-Reply-To: <mailman.535.1228211958.2542.time-nuts@febo.com>
References: <mailman.535.1228211958.2542.time-nuts@febo.com>
Message-ID: <0F2C9FB0-B0E1-43BB-A412-04E7722E9229@hughes.net>

On Dec 2, 2008, at 1:59 AM, Ulrich wrote:

> Message: 6
> Date: Tue, 2 Dec 2008 10:59:05 +0100
> From: "Ulrich Bangert" <df6jb at ulrich-bangert.de>
> Subject: Re: [time-nuts] Thunderbolt settings
>
> Dick,
> to be honest, I did even some more things concerning the TBolt. Find
> attached the results of an measurement where the oscillator  
> disciplining
> has been disabled and the internal PPS comparison has been logged over
> some time. So it is free running OCXO vs. GPS. The falling slope in  
> the
> left is much due to GPS jitter averaging out with longer observation
> times. The ascending slope is much due to the OCXO reacting to
> environmental conditions. This measurement would indicate that  
> 1000-2000
> s is a good value for the time constant. However, I did not have the
> heart yet to use such a big value. Neveretheless I use 1200 s TC in my
> DIY GPSDO made from an M12+ and an FTS1200.
>
> I think that also an clarification is necessary what exactly different
> manufactures mean by "time constant". I am using the term "time
> constant" in the same sense as Stanford Research do in their PRS10
> manual, where they talk about the pll's "natural time constant".  
> When a
> sudden step in OCXO frequency is noticed by the pll it will react  
> to it
> by changing the EFC voltage. It is exactly the "natural time constant"
> that the pll needs to bring the OCXO frequency to its original value.
> The pll reaction as a whole lasts much longer since it wants to bring
> the phase difference back to zero.
>
> Best regards
> Ulrich

Ulrich, thanks so much. I have upped the Loop TC using the TBolt  
monitor sw to 4000.0 secs, a bit over an hour. I really have no idea  
what that actually means, but the TBolt seems to be happy. I have no  
way that I know of to do an Allan Var measurement, so I don't know if  
this is a sweet spot or not. In the plot (thanks for that) can I  
assume that disciplining will keep the right end of the slope falling  
for a while?

Dick Moore


From bruce.griffiths at xtra.co.nz  Tue Dec  2 20:46:52 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Wed, 03 Dec 2008 09:46:52 +1300
Subject: [time-nuts] Soundcard sampling Re:  Picking a good HP 10811
In-Reply-To: <493595CB.6080407@xtra.co.nz>
References: <C55A795C.30E8%James.P.Lux@jpl.nasa.gov>	<493580D6.3030005@xtra.co.nz>
	<493595CB.6080407@xtra.co.nz>
Message-ID: <49359EBC.5060207@xtra.co.nz>

Bruce Griffiths wrote:
> Bruce Griffiths wrote:
>   
>> Lux, James P wrote:
>>   
>>     
>>> On 12/1/08 10:58 PM, "Bruce Griffiths" <bruce.griffiths at xtra.co.nz> wrote:
>>>
>>>
>>>   
>>>     
>>>       
>>>> Thus it may well be worthwhile doing this as one then (in principle)
>>>> only needs 3 mixers (plus 3 simultaneously sampled sound card input
>>>> channels) and no offset source, however the maximum achievable offset
>>>> will probably result in beat frequencies that are a little too low for a
>>>> sound card ADC.
>>>>     
>>>>       
>>>>         
>>> Most sound cards roll off below around 10-20 Hz, or, at least, you're
>>> starting to get into the roll off filter characteristic where the phase is
>>> changing rapidly.
>>>
>>> Re: "simultaneously sampled"...  I would assume that sample jitter here
>>> affects the measurement.  Granted, one can do a fit of many samples to a
>>> sine wave, and get a sqrt(N) improvement (if it's random jitter, and not
>>> systematic), but what's a typical spec for channel/channel jitter on a sound
>>> card?  Or, more properly, if you're measuring an Allan deviation of, say,
>>> 1E-15 over 100 seconds for a couple 10MHz sources beaten down to, say, 100
>>> Hz or thereabouts.. How good does it need to be?
>>>
>>>   
>>>     
>>>       
>> The differential sampling jitter between channels would probably have to
>> be less than a 100ps or so a little more if its random.
>> Preliminary tests with a high end sound card appear to demonstrate a
>> system noise level below 1E-15 at tau = 100 sec.
>>
>> Bruce
>>
>>   
>>     
> Oops I omitted a factor of 100.
> The differential sampling jitter would need to be less than about 10ns.
> Practically all high end sound cards should easily meet this spec.
>
> The sampling clock jitter spec for a given SNR and oversampling ration is
>
>  jitter < SQRT(OSR)/(2*PI*SNR)
> OSR = oversampling ratio
> SNR = signal to noise ratio
>
> e.g. with a 100dB SNR a 10KHz input and an OSR of 9.6 (192kHz)
> The sampling jitter needs to be < 500ps rms.
>
> with a 100dB SNR a 1kHz input and an OSR of 96
> the sampling jitter needs to be < 15.6 ns rms.
>
> Bruce
>
>
>   
Correction:
After rereading the ADC chip datasheet I realised that the actual OSR
for 192kHz output sample rate is 128 (independent of the input signal
frequency).

Thus
for a 1kHz input and 100dB SNR the input clock jitter should be < 18ns rms.

for a 10kHz input and 100dB SNR the input clock jitter should be < 1.8ns
rms.

It is very likely that the differential sampling clock jitter
contribution of a high end sound card to the ADEV noise floor will in
around 1E-15 or less at Tau = 100sec.

Bruce


From bruce.griffiths at xtra.co.nz  Tue Dec  2 21:00:52 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Wed, 03 Dec 2008 10:00:52 +1300
Subject: [time-nuts] Thunderbolt settings
In-Reply-To: <0F2C9FB0-B0E1-43BB-A412-04E7722E9229@hughes.net>
References: <mailman.535.1228211958.2542.time-nuts@febo.com>
	<0F2C9FB0-B0E1-43BB-A412-04E7722E9229@hughes.net>
Message-ID: <4935A204.6060700@xtra.co.nz>

Richard Moore wrote:
> On Dec 2, 2008, at 1:59 AM, Ulrich wrote:
>
>   
>> Message: 6
>> Date: Tue, 2 Dec 2008 10:59:05 +0100
>> From: "Ulrich Bangert" <df6jb at ulrich-bangert.de>
>> Subject: Re: [time-nuts] Thunderbolt settings
>>
>> Dick,
>> to be honest, I did even some more things concerning the TBolt. Find
>> attached the results of an measurement where the oscillator  
>> disciplining
>> has been disabled and the internal PPS comparison has been logged over
>> some time. So it is free running OCXO vs. GPS. The falling slope in  
>> the
>> left is much due to GPS jitter averaging out with longer observation
>> times. The ascending slope is much due to the OCXO reacting to
>> environmental conditions. This measurement would indicate that  
>> 1000-2000
>> s is a good value for the time constant. However, I did not have the
>> heart yet to use such a big value. Neveretheless I use 1200 s TC in my
>> DIY GPSDO made from an M12+ and an FTS1200.
>>
>> I think that also an clarification is necessary what exactly different
>> manufactures mean by "time constant". I am using the term "time
>> constant" in the same sense as Stanford Research do in their PRS10
>> manual, where they talk about the pll's "natural time constant".  
>> When a
>> sudden step in OCXO frequency is noticed by the pll it will react  
>> to it
>> by changing the EFC voltage. It is exactly the "natural time constant"
>> that the pll needs to bring the OCXO frequency to its original value.
>> The pll reaction as a whole lasts much longer since it wants to bring
>> the phase difference back to zero.
>>
>> Best regards
>> Ulrich
>>     
>
> Ulrich, thanks so much. I have upped the Loop TC using the TBolt  
> monitor sw to 4000.0 secs, a bit over an hour. I really have no idea  
> what that actually means, but the TBolt seems to be happy. I have no  
> way that I know of to do an Allan Var measurement, so I don't know if  
> this is a sweet spot or not. In the plot (thanks for that) can I  
> assume that disciplining will keep the right end of the slope falling  
> for a while?
>
> Dick Moore
>   
You would need a statistically independent frequency standard
(preferably 2 or more) of comparable or better stability to the GPS SVs
to make meaningful ADEV measurements.
Typically a hydrogen maser is required for ADEV measurements for long
Tau, for shorter Tau a very high quality OCXO (preferably 2 or more)
will suffice.
The best you can do is repeat Ulrich's test with your own Thunderbolt,
the OCXO noise characteristics will differ for each OCXO as will the
optimum loop time constant.
All the software tools for logging, analysing and plotting the data are
readily available for free.

Bruce


From holrum at hotmail.com  Tue Dec  2 21:01:24 2008
From: holrum at hotmail.com (Mark Sims)
Date: Tue, 2 Dec 2008 21:01:24 +0000
Subject: [time-nuts] Tektronix DM-5010 DVM...
In-Reply-To: <mailman.539.1228244674.2542.time-nuts@febo.com>
References: <mailman.539.1228244674.2542.time-nuts@febo.com>
Message-ID: <BLU125-W302210842AF1D988D910D7CE000@phx.gbl>


I have both 5010's (4.5 digit, 2 wide) and 5120's (6.5 digit, 3 wide) modules (and just about all other TM50x modules).  Both meters will get the job done.  The 5010 is nice because it only takes up two slots.  The 5120 is nice because it is 6.5 digits.  One big difference is in calibration.  The 5010 stores the cal values in RAM backed up by a nicad battery.  When the battery goes bad,  you need to replace it and recalibrate the unit.  This requires a calibrator that can produce specific values (mine can't).  The 5120 stores calibration data in EEPROM.  If you cal from the front panel program,  your calibrator must generate specific values.  If you cal via GPIB,  you can specify the values used.  If you are interested in either module,  contact me offline...
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From richiem at hughes.net  Tue Dec  2 21:28:29 2008
From: richiem at hughes.net (Richard Moore)
Date: Tue, 2 Dec 2008 13:28:29 -0800
Subject: [time-nuts] DM5010
In-Reply-To: <mailman.541.1228251687.2542.time-nuts@febo.com>
References: <mailman.541.1228251687.2542.time-nuts@febo.com>
Message-ID: <8806BDAA-63A5-4F75-96E8-1D709A736C65@hughes.net>

On Dec 2, 2008, at 1:01 PM, time-nuts-request at febo.com wrote:

> Message: 1
> Date: Tue, 02 Dec 2008 11:26:34 -0800
> From: "Burt I. Weiner" <biwa at att.net>
> Subject: [time-nuts] Tektronix DC-5010 DVM...
>
> Since we're on the subject of Digital Voltmeters, accuracy and such,
> I'm wondering if anyone in the group has an opinion regarding the
> Tektronix DC-5010 DVM.  I just want a good, reliable bench DVM and
> would like to be able to stuff it in my TM-5006 frame.  Any thoughts
> or suggestions?
>
> Burt, K6OQK
>
> Burt I. Weiner Associates
> Broadcast Technical Services
> Glendale, California  U.S.A.
> biwa at att.net
> K6OQK

Burt, if you don't need autoranging, then I recommend a DM501A,  
readily available on fleaBay. 4-1/2 digits in a single-wide chassis,  
and easy to cal, too.

Dick Moore


From aceamusements at mchsi.com  Tue Dec  2 21:42:08 2008
From: aceamusements at mchsi.com (aceamusements at mchsi.com)
Date: Tue, 02 Dec 2008 21:42:08 +0000
Subject: [time-nuts] Thoughts on Cs tube failure modes
	(aceamusements@mchsi.com)
Message-ID: <120220082142.25312.4935ABAF0009BE07000062E0219791336303010CD2079C080C03BF9C9B020A030A9C9A030E0A0C0E@mchsi.com>

Corby,
never heard of that before.

might be due to long storage before I opened the box for the first time?

even stranger is the fact the pump current started out real low at first power
on .2 or .4 and has steadily risen over time (11 months)

unit has been online pretty much 24/7 and I was just curious if anyone has seen
a rise in pump current(in continuous operation) as described although I got a
ways to go before shutdown.

30ua I think?


----------------------  Original Message:  ---------------------
From:    Corby Dawson <cdelect at juno.com>
To:      time-nuts at febo.com
Subject: Re: [time-nuts] Thoughts on Cs tube failure modes (aceamusements at mchsi.com)
Date:    Tue, 2 Dec 2008 20:13:22 +0000

> What you describe could be "whiskers"  growing in the ion pump. 
> 
> They do not affect the pumping until they grow big enough to load the
> supply past its current capability.
> 
> You can sometimes remove them using a hand held brush discharge tester.
> (Remove tube from chassis before doing this!)
> 
> I would not try this until the current rises enough to cut off the ovens.
> 
> Your current is still quite low.
> 
> Corby Dawson
> ____________________________________________________________
> Click for online loan, fast & no lender fee, approval today
> http://thirdpartyoffers.juno.com/TGL2141/fc/PnY6rw2P5sfvOI6bGtiN2n7zim31rTbaVcvH
> cKkQJU7GhZyFH6zWB/
> 
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.


From holrum at hotmail.com  Tue Dec  2 22:04:42 2008
From: holrum at hotmail.com (Mark Sims)
Date: Tue, 2 Dec 2008 22:04:42 +0000
Subject: [time-nuts] DM5010
In-Reply-To: <mailman.541.1228251687.2542.time-nuts@febo.com>
References: <mailman.541.1228251687.2542.time-nuts@febo.com>
Message-ID: <BLU125-W29C2C7C48FF7AFF26DDE6CE000@phx.gbl>


The DM501/501A/502/502A are nice if you don't want GPIB support (which is why one would be using a TM5006 mainframe in the first place).  I prefer twirly knobs over pushy buttons on my meters,  so I use the non-A versions.  Also the non-A versions do current measurements through the same pair of input jacks as voltage (no swapping test leads to measure current).
_________________________________________________________________
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From stanley_reynolds at yahoo.com  Tue Dec  2 22:48:24 2008
From: stanley_reynolds at yahoo.com (Stanley Reynolds)
Date: Tue, 2 Dec 2008 14:48:24 -0800 (PST)
Subject: [time-nuts] Soundcard sampling Re:  Picking a good HP 10811
References: <C55A795C.30E8%James.P.Lux@jpl.nasa.gov>
	<493580D6.3030005@xtra.co.nz> <493595CB.6080407@xtra.co.nz>
	<49359EBC.5060207@xtra.co.nz>
Message-ID: <843943.62160.qm@web30303.mail.mud.yahoo.com>

<snip>
Thus
for a 1kHz input and 100dB SNR the input clock jitter should be < 18ns rms.

for a 10kHz input and 100dB SNR the input clock jitter should be < 1.8ns
rms.

It is very likely that the differential sampling clock jitter
contribution of a high end sound card to the ADEV noise floor will in
around 1E-15 or less at Tau = 100sec.

Bruce

So offset each DUT to prevent injection lock within the 20 Hz range, and get relaxed spec on mixers and buffers. The retail was about 12 US$?for the surface mount and 50 US$ for the BNC mini-circuit mixers. Home made buffer amps and mixers sounds possible for me.

Use a 10Mhz +-10Khz offset common oscillator to put beat in the sound card range, just because jitter of 1.8ns sounds better than 18ns.

Slave two cards to one oscillator for 4 channels run test, post data / wave files.

Any reason to upgrade the sound card sample clock, I have a clock-block?? 

What would be a reasonable common LO oscillator,?sine wave XO?module ?

Stanley

I have several HP-8708a NOS that are full of parts they have a 20Mhz XO that would phase lock to the lab standard and provide a voltage of 1 volt per Mhz for an input signal that was the result of another mixer from the Ghz range which I do not have. Thinking of using them one for each DUT. They use the same connector for the backplane as the 10811 but each board is in a smaller compartment, could take three of the six slots but it would require much work and the front part of the case has space. 

Does anyone have any info on this 8709A option HU8 Synchronizer ? Think it was made about 1987.

From james.p.lux at jpl.nasa.gov  Tue Dec  2 23:15:47 2008
From: james.p.lux at jpl.nasa.gov (Lux, James P)
Date: Tue, 2 Dec 2008 15:15:47 -0800
Subject: [time-nuts] Soundcard sampling Re:  Picking a good HP 10811
In-Reply-To: <843943.62160.qm@web30303.mail.mud.yahoo.com>
References: <C55A795C.30E8%James.P.Lux@jpl.nasa.gov>
	<493580D6.3030005@xtra.co.nz> <493595CB.6080407@xtra.co.nz>
	<49359EBC.5060207@xtra.co.nz>
	<843943.62160.qm@web30303.mail.mud.yahoo.com>
Message-ID: <ECE7A93BD093E1439C20020FBE87C47FEB55C30E5F@ALTPHYEMBEVSP20.RES.AD.JPL>

> So offset each DUT to prevent injection lock within the 20 Hz
> range, and get relaxed spec on mixers and buffers. The retail
> was about 12 US$ for the surface mount and 50 US$ for the BNC
> mini-circuit mixers. Home made buffer amps and mixers sounds
> possible for me.
>

Get the mixers with SMA, not BNC. Less mechanical uncertainty. Same price (or maybe even less)
SMA semirigid/hardline is fairly straightforward, if tedious, to hand assemble. Or, you can buy premade high quality cables from somewhere like RF Coax. (they'll cost as much as the mixer, though)  Or, for initial checkout, you can get inexpensive SMA jumpers from a variety of sources. (aka "pigtails" in the wireless trade)



> Use a 10Mhz +-10Khz offset common oscillator to put beat in
> the sound card range, just because jitter of 1.8ns sounds
> better than 18ns.
>
> Slave two cards to one oscillator for 4 channels run test,
> post data / wave files.

Most decent pro cards are already 4 channels with a Firewire (1394) interface. Lots have balanced inputs as well (check to see if they're really balanced or pseudo balanced)
PreSonus Firebox is $300 with 6 inputs
Presonus Inspire is $200 with 4 inputs
Mackie Onyx Satellite

The Edirol FA66 is very popular for amateurs running software radios where they use two channels (of 6) for I/Q digitizing. It runs about $280 these days.

You might also be able to use a high performance audio recorder to capture the data, then load it into a PC for post processing (that way, you won't have the noisy PC in the system while recording)



>


From bruce.griffiths at xtra.co.nz  Tue Dec  2 23:36:02 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Wed, 03 Dec 2008 12:36:02 +1300
Subject: [time-nuts] Soundcard sampling Re:  Picking a good HP 10811
In-Reply-To: <843943.62160.qm@web30303.mail.mud.yahoo.com>
References: <C55A795C.30E8%James.P.Lux@jpl.nasa.gov>	<493580D6.3030005@xtra.co.nz>
	<493595CB.6080407@xtra.co.nz>	<49359EBC.5060207@xtra.co.nz>
	<843943.62160.qm@web30303.mail.mud.yahoo.com>
Message-ID: <4935C662.3060809@xtra.co.nz>

Stanley Reynolds wrote:
> <snip>
> Thus
> for a 1kHz input and 100dB SNR the input clock jitter should be < 18ns rms.
>
> for a 10kHz input and 100dB SNR the input clock jitter should be < 1.8ns
> rms.
>
> It is very likely that the differential sampling clock jitter
> contribution of a high end sound card to the ADEV noise floor will in
> around 1E-15 or less at Tau = 100sec.
>
> Bruce
>
> So offset each DUT to prevent injection lock within the 20 Hz range, and get relaxed spec on mixers and buffers. The retail was about 12 US$ for the surface mount and 50 US$ for the BNC mini-circuit mixers. Home made buffer amps and mixers sounds possible for me.
>
>   
2N3904's are more than adequate for very high reverse isolation buffer
amplifiers at 10MHz.
You should use a design similar to the NIST 5 and 10MHz distribution
amplifiers not the 100MHz design.
Opamps have considerably higher phase noise.
MMICs have too much gain to be useful.
> Use a 10Mhz +-10Khz offset common oscillator to put beat in the sound card range, just because jitter of 1.8ns sounds better than 18ns.
>   
No, 1 kHz or so is probably better, the above calculation was used to
infer a likely maximum for the sound card sampling clock jitter from the
specifications.
It is probably much better as other effects contribute to the SNR.
> Slave two cards to one oscillator for 4 channels run test, post data / wave files.
>
>   
Making the wave files available would indeed be useful in that they
would be useful for algorithm development.
Matlab, for example, can read wave files.
The same data can be analysed using various algorithms ranging from
calculating the zero crossing time stamps to a implementing a dual
Channel Costas receiver.

However use an application that actually saves 24 bit data.
A lot of applications only save 16 bit data even if you have a 24 bit
sound card.
You often need to use a hex editor to examine the files to find this out.
Start with a simple test using 2 mixers and one sound card.
Drive the RF port of each mixer from the same OCXO.
The resultant data can be used to establish the system noise level
provided the offset oscillator and the OCXO don't injection lock.
Then do a test using to separate OCXOs.
Finally when all appears to be working well test the 2 sound card 4
mixer system.
You will need to use high end sound cards like the M-Audio AP192 for
good performance.
This particular one has balanced 4VrmsFS inputs which will be useful in
reducing the effect of low frequency ground loops.
If necessary (to break LF ground loops) the mixer preamp could drive an
Audio output transformer such as the Lundahl LL2811 with mumetal
magnetic screens and internal shielding.
Hybrid feedback can be used to reduce the distortion and extend the low
frequency response.
> Any reason to upgrade the sound card sample clock, I have a clock-block ? 
>
>   
Don't use that it will probably have too much jitter.
> What would be a reasonable common LO oscillator, sine wave XO module ?
>
>   
Dont forget to have an individual isolation amplifiers between each LO
port and the LO itself.
The easiest method is to use a DDS system to generate the required
offset LO frequency.
However bandpass filtering of the output is necessary and care must be
taken to select the DDS clock frequency to ensure that the principal
phase truncation spur as well as other spurs are sufficiently far from
the desired output that they can easily be filtered out. Use the DDS
tools on the Analog Devices site to help with this.
The DDS clock itself needs to have relatively low noise either divide
10MHz by 2 and then multiply by 9 to get 45MHz which appears appropriate
for the AD9850 series chips, or build a low noise discrete 45MHz LO.
> Stanley
>
> I have several HP-8708a NOS that are full of parts they have a 20Mhz XO that would phase lock to the lab standard and provide a voltage of 1 volt per Mhz for an input signal that was the result of another mixer from the Ghz range which I do not have. Thinking of using them one for each DUT. They use the same connector for the backplane as the 10811 but each board is in a smaller compartment, could take three of the six slots but it would require much work and the front part of the case has space. 
>
> Does anyone have any info on this 8709A option HU8 Synchronizer ? Think it was made about 1987.
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>
>   

Bruce


From stanley_reynolds at yahoo.com  Wed Dec  3 00:03:24 2008
From: stanley_reynolds at yahoo.com (Stanley Reynolds)
Date: Tue, 2 Dec 2008 16:03:24 -0800 (PST)
Subject: [time-nuts] Soundcard sampling Re:  Picking a good HP 10811
References: <C55A795C.30E8%James.P.Lux@jpl.nasa.gov>
	<493580D6.3030005@xtra.co.nz> <493595CB.6080407@xtra.co.nz>
	<49359EBC.5060207@xtra.co.nz>
	<843943.62160.qm@web30303.mail.mud.yahoo.com>
	<ECE7A93BD093E1439C20020FBE87C47FEB55C30E5F@ALTPHYEMBEVSP20.RES.AD.JPL>
Message-ID: <562899.17240.qm@web30303.mail.mud.yahoo.com>





________________________________

From: "Lux, James P" <james.p.lux at jpl.nasa.gov>
To: Discussion of precise time and frequency measurement <time-nuts at febo.com>
Sent: Tuesday, December 2, 2008 5:15:47 PM
Subject: Re: [time-nuts] Soundcard sampling Re: Picking a good HP 10811


Maybe you all missed the part where I was complaining about the $15 mixers so my investment in sound cards must be less than that, would think that at $300 you should be able to get a real?A/D card that would allow a beat frequency down to DC. 

Should I even try with my cheap no name cards ?

Bruce looks like the?M-audio is $179 the specs look great if almost too good, guess I should save my pennies.?
http://www.digitalconnection.com/products/audio/ap192.asp? ( first site goggle turned up, did not look further )

Assume the one card would be 4 channels they do say multi card support but with an * and the clock problem would need a fix not sure I would take the solder?to it?till the 1 year warranty is gone but then 4 channels would work.

Stanley?

_______________________________________________
time-nuts mailing list -- time-nuts at febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

> So offset each DUT to prevent injection lock within the 20 Hz
> range, and get relaxed spec on mixers and buffers. The retail
> was about 12 US$ for the surface mount and 50 US$ for the BNC
> mini-circuit mixers. Home made buffer amps and mixers sounds
> possible for me.
>

Get the mixers with SMA, not BNC. Less mechanical uncertainty. Same price (or maybe even less)
SMA semirigid/hardline is fairly straightforward, if tedious, to hand assemble. Or, you can buy premade high quality cables from somewhere like RF Coax. (they'll cost as much as the mixer, though)? Or, for initial checkout, you can get inexpensive SMA jumpers from a variety of sources. (aka "pigtails" in the wireless trade)



> Use a 10Mhz +-10Khz offset common oscillator to put beat in
> the sound card range, just because jitter of 1.8ns sounds
> better than 18ns.
>
> Slave two cards to one oscillator for 4 channels run test,
> post data / wave files.

Most decent pro cards are already 4 channels with a Firewire (1394) interface. Lots have balanced inputs as well (check to see if they're really balanced or pseudo balanced)
PreSonus Firebox is $300 with 6 inputs
Presonus Inspire is $200 with 4 inputs
Mackie Onyx Satellite

The Edirol FA66 is very popular for amateurs running software radios where they use two channels (of 6) for I/Q digitizing. It runs about $280 these days.

You might also be able to use a high performance audio recorder to capture the data, then load it into a PC for post processing (that way, you won't have the noisy PC in the system while recording)



>

From james.p.lux at jpl.nasa.gov  Wed Dec  3 00:03:39 2008
From: james.p.lux at jpl.nasa.gov (Lux, James P)
Date: Tue, 2 Dec 2008 16:03:39 -0800
Subject: [time-nuts] Soundcard sampling Re:  Picking a good HP 10811
In-Reply-To: <4935C662.3060809@xtra.co.nz>
References: <C55A795C.30E8%James.P.Lux@jpl.nasa.gov>
	<493580D6.3030005@xtra.co.nz>	<493595CB.6080407@xtra.co.nz>
	<49359EBC.5060207@xtra.co.nz>	<843943.62160.qm@web30303.mail.mud.yahoo.com>
	<4935C662.3060809@xtra.co.nz>
Message-ID: <ECE7A93BD093E1439C20020FBE87C47FEB55C30E79@ALTPHYEMBEVSP20.RES.AD.JPL>


> You will need to use high end sound cards like the M-Audio
> AP192 for good performance.

If you're using that particular card , I'd definitely build a new cable for it.  You can probably do better than 1/4" TRS phone plugs.



> >
> >
> Dont forget to have an individual isolation amplifiers
> between each LO port and the LO itself.
> The easiest method is to use a DDS system to generate the
> required offset LO frequency.
> However bandpass filtering of the output is necessary and
> care must be taken to select the DDS clock frequency to
> ensure that the principal phase truncation spur as well as
> other spurs are sufficiently far from the desired output that
> they can easily be filtered out. Use the DDS tools on the
> Analog Devices site to help with this.
> The DDS clock itself needs to have relatively low noise
> either divide 10MHz by 2 and then multiply by 9 to get 45MHz
> which appears appropriate for the AD9850 series chips, or
> build a low noise discrete 45MHz LO.


You might want to look at the 99xx series DDSes. If nothing else, they run cooler than the 985x  series(AD9854, used in a variety of quadrature schemes, draws 1.2A @3.3V.. Yep, it gets mighty toasty warm, and needs serious heatsinking and a fan or it gets intermittent)

The newer DDSes have lower power, faster clocks, lower spurs, more bits in the DAC, etc.  Although, I'm not sure how important all these things would be in this application.

There are also some very low phase noise, low jitter XO available that can drive these things (not temperature compensated, though, so as the XO temp changes, so does the frequency)


From bruce.griffiths at xtra.co.nz  Wed Dec  3 00:15:17 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Wed, 03 Dec 2008 13:15:17 +1300
Subject: [time-nuts] Soundcard sampling Re:  Picking a good HP 10811
In-Reply-To: <ECE7A93BD093E1439C20020FBE87C47FEB55C30E79@ALTPHYEMBEVSP20.RES.AD.JPL>
References: <C55A795C.30E8%James.P.Lux@jpl.nasa.gov>	<493580D6.3030005@xtra.co.nz>	<493595CB.6080407@xtra.co.nz>	<49359EBC.5060207@xtra.co.nz>	<843943.62160.qm@web30303.mail.mud.yahoo.com>	<4935C662.3060809@xtra.co.nz>
	<ECE7A93BD093E1439C20020FBE87C47FEB55C30E79@ALTPHYEMBEVSP20.RES.AD.JPL>
Message-ID: <4935CF95.5080403@xtra.co.nz>

Lux, James P wrote:
>> You will need to use high end sound cards like the M-Audio
>> AP192 for good performance.
>>     
>
> If you're using that particular card , I'd definitely build a new cable for it.  You can probably do better than 1/4" TRS phone plugs.
>
>   
I use XLR to TRS cables with it.
>
>   
>>>       
>> Dont forget to have an individual isolation amplifiers
>> between each LO port and the LO itself.
>> The easiest method is to use a DDS system to generate the
>> required offset LO frequency.
>> However bandpass filtering of the output is necessary and
>> care must be taken to select the DDS clock frequency to
>> ensure that the principal phase truncation spur as well as
>> other spurs are sufficiently far from the desired output that
>> they can easily be filtered out. Use the DDS tools on the
>> Analog Devices site to help with this.
>> The DDS clock itself needs to have relatively low noise
>> either divide 10MHz by 2 and then multiply by 9 to get 45MHz
>> which appears appropriate for the AD9850 series chips, or
>> build a low noise discrete 45MHz LO.
>>     
>
>
> You might want to look at the 99xx series DDSes. If nothing else, they run cooler than the 985x  series(AD9854, used in a variety of quadrature schemes, draws 1.2A @3.3V.. Yep, it gets mighty toasty warm, and needs serious heatsinking and a fan or it gets intermittent)
>
> The newer DDSes have lower power, faster clocks, lower spurs, more bits in the DAC, etc.  Although, I'm not sure how important all these things would be in this application.
>
> There are also some very low phase noise, low jitter XO available that can drive these things (not temperature compensated, though, so as the XO temp changes, so does the frequency)
>
>   

Using a low phase noise XO with a suitable frequency would probably be
preferable as there would be fewer potential problems with spurs.
With appropriate algorithms the drift in beat frequency with temperature
shouldn't be too much of a problem.

Bruce




From bruce.griffiths at xtra.co.nz  Wed Dec  3 00:26:29 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Wed, 03 Dec 2008 13:26:29 +1300
Subject: [time-nuts] Soundcard sampling Re:  Picking a good HP 10811
In-Reply-To: <562899.17240.qm@web30303.mail.mud.yahoo.com>
References: <C55A795C.30E8%James.P.Lux@jpl.nasa.gov>	<493580D6.3030005@xtra.co.nz>
	<493595CB.6080407@xtra.co.nz>	<49359EBC.5060207@xtra.co.nz>	<843943.62160.qm@web30303.mail.mud.yahoo.com>	<ECE7A93BD093E1439C20020FBE87C47FEB55C30E5F@ALTPHYEMBEVSP20.RES.AD.JPL>
	<562899.17240.qm@web30303.mail.mud.yahoo.com>
Message-ID: <4935D235.8090200@xtra.co.nz>

Stanley Reynolds wrote:
>
>
> ________________________________
>
> From: "Lux, James P" <james.p.lux at jpl.nasa.gov>
> To: Discussion of precise time and frequency measurement <time-nuts at febo.com>
> Sent: Tuesday, December 2, 2008 5:15:47 PM
> Subject: Re: [time-nuts] Soundcard sampling Re: Picking a good HP 10811
>
>
> Maybe you all missed the part where I was complaining about the $15 mixers so my investment in sound cards must be less than that, would think that at $300 you should be able to get a real A/D card that would allow a beat frequency down to DC. 
>
> Should I even try with my cheap no name cards ?
>
> Bruce looks like the M-audio is $179 the specs look great if almost too good, guess I should save my pennies. 
> http://www.digitalconnection.com/products/audio/ap192.asp  ( first site goggle turned up, did not look further )
>
> Assume the one card would be 4 channels they do say multi card support but with an * and the clock problem would need a fix not sure I would take the solder to it till the 1 year warranty is gone but then 4 channels would work.
>
> Stanley 
>
>   
Stanley

You can certainly start with a cheap no name card although the noise
floor will be somewhat higher (typically a 16 bit motherboard sound
system is at least 10x noiser than the AP192, some have lots of spurs
others are quieter). For a long enough averaging time the system noise
level even with a cheap card will be somewhat lower than any OCXO you
are likely to have.
A cheap card will at least establish that in principle the technique works.
You can then decide whether to upgrade it.

The AP192 cards only have 2 input channels.

Real AD cards with adequate performance are usually far more expensive
than $300.
In principle, one could build an ADC card with adequate performance
using 4 AD7760 ADCs.

Bruce


From james.p.lux at jpl.nasa.gov  Wed Dec  3 00:46:24 2008
From: james.p.lux at jpl.nasa.gov (Lux, James P)
Date: Tue, 2 Dec 2008 16:46:24 -0800
Subject: [time-nuts] Soundcard sampling Re:  Picking a good HP 10811
In-Reply-To: <562899.17240.qm@web30303.mail.mud.yahoo.com>
References: <C55A795C.30E8%James.P.Lux@jpl.nasa.gov>
	<493580D6.3030005@xtra.co.nz> <493595CB.6080407@xtra.co.nz>
	<49359EBC.5060207@xtra.co.nz>	<843943.62160.qm@web30303.mail.mud.yahoo.com>
	<ECE7A93BD093E1439C20020FBE87C47FEB55C30E5F@ALTPHYEMBEVSP20.RES.AD.JPL>
	<562899.17240.qm@web30303.mail.mud.yahoo.com>
Message-ID: <ECE7A93BD093E1439C20020FBE87C47FEB55C30E8C@ALTPHYEMBEVSP20.RES.AD.JPL>

>
> Maybe you all missed the part where I was complaining about
> the $15 mixers so my investment in sound cards must be less
> than that, would think that at $300 you should be able to get
> a real A/D card that would allow a beat frequency down to DC.

I think you'd have a hard time finding a very high performance A/D card with DC coupling.  The high end audio recording market is where it's at for performance, because they have economies of scale. You might be able to get an eval board from Wolfson or TDK or whoever makes these hotstuff ADCs, but by the time you lash em up, and deal with the inevitable clunky interface, you might be better off just finding a used FA66 or something.  I see M-audio Delta 44 Pro's for $75-80 on Ebay right now or used for $50 (I also see one for $15, but that's too cheap, so it must be just the manual or something.. )



>
> Should I even try with my cheap no name cards ?

Sure.. Why not.

>
> Bruce looks like the M-audio is $179 the specs look great if
> almost too good, guess I should save my pennies.
> http://www.digitalconnection.com/products/audio/ap192.asp  (
> first site goggle turned up, did not look further )
http://www.m-audio.com/ is the mfr website.

Well.. The data sheet claims 100+dB SNR, but one might want to see some independent testing.  But, in general, this is a plausible and practical level of performance.  At this level, pretty subtle stuff like wiring layout and connectors starts to be an issue.  The amateur software radio folks have been obsessing about this kind of thing, since the dynamic range of the ADC determines the ultimate performance of the receiver in a mixed signal environment (e.g. A figure of merit for receivers is how strong can a signal 2 kHz away be from the desired signal that's right at the noise floor).  The popular design for the receiver is a direct conversion scheme using a 4 way mux driven by a quadrature LO from a DDS, generating an I/Q audio output.


>
> Assume the one card would be 4 channels they do say multi
> card support but with an * and the clock problem would need a
> fix not sure I would take the solder to it till the 1 year
> warranty is gone but then 4 channels would work.



The AP192 is a 2 channel card, but it might have a word clock input or similar.


From james.p.lux at jpl.nasa.gov  Wed Dec  3 00:56:08 2008
From: james.p.lux at jpl.nasa.gov (Lux, James P)
Date: Tue, 2 Dec 2008 16:56:08 -0800
Subject: [time-nuts] Soundcard sampling
In-Reply-To: <4935CF95.5080403@xtra.co.nz>
References: <C55A795C.30E8%James.P.Lux@jpl.nasa.gov>
	<493580D6.3030005@xtra.co.nz>	<493595CB.6080407@xtra.co.nz>
	<49359EBC.5060207@xtra.co.nz>	<843943.62160.qm@web30303.mail.mud.yahoo.com>
	<4935C662.3060809@xtra.co.nz>
	<ECE7A93BD093E1439C20020FBE87C47FEB55C30E79@ALTPHYEMBEVSP20.RES.AD.JPL>
	<4935CF95.5080403@xtra.co.nz>
Message-ID: <ECE7A93BD093E1439C20020FBE87C47FEB55C30E8F@ALTPHYEMBEVSP20.RES.AD.JPL>

> > The newer DDSes have lower power, faster clocks, lower
> spurs, more bits in the DAC, etc.  Although, I'm not sure how
> important all these things would be in this application.
> >
> > There are also some very low phase noise, low jitter XO
> available that
> > can drive these things (not temperature compensated,
> though, so as the
> > XO temp changes, so does the frequency)
> >
> >
>
> Using a low phase noise XO with a suitable frequency would
> probably be preferable as there would be fewer potential
> problems with spurs.
> With appropriate algorithms the drift in beat frequency with
> temperature shouldn't be too much of a problem.
>

There's low phase noise oscillators intended for the SONET market from Valpey Fisher, etc. that have fairly good performance. A VF161 is a <$50 sort of part and is speced at 1ps jitter (1 sigma, fj>1kHz).  VF has "jitter attenuators" too, which are a low jitter pll with <0.18ps jitter (RMS 12kHz-20MHz)..

Pick a XO at 200-300 MHz or so (whatever frequency is readily available), then set your DDS for a "spur free" frequency (where it divides nicely into the SIN table size)  (on the AD9584 running at 200MHz which has a 48 bit phase accumulator, 17 bit phase table, and a 12 bit DAC, these are about every 3 kHz or so)


From james.p.lux at jpl.nasa.gov  Wed Dec  3 01:06:45 2008
From: james.p.lux at jpl.nasa.gov (Lux, James P)
Date: Tue, 2 Dec 2008 17:06:45 -0800
Subject: [time-nuts] Soundcard sampling Re:  Picking a good HP 10811
In-Reply-To: <4935D235.8090200@xtra.co.nz>
References: <C55A795C.30E8%James.P.Lux@jpl.nasa.gov>
	<493580D6.3030005@xtra.co.nz>	<493595CB.6080407@xtra.co.nz>
	<49359EBC.5060207@xtra.co.nz>	<843943.62160.qm@web30303.mail.mud.yahoo.com>
	<ECE7A93BD093E1439C20020FBE87C47FEB55C30E5F@ALTPHYEMBEVSP20.RES.AD.JPL>
	<562899.17240.qm@web30303.mail.mud.yahoo.com>
	<4935D235.8090200@xtra.co.nz>
Message-ID: <ECE7A93BD093E1439C20020FBE87C47FEB55C30E92@ALTPHYEMBEVSP20.RES.AD.JPL>

>
> You can certainly start with a cheap no name card although
> the noise floor will be somewhat higher (typically a 16 bit
> motherboard sound system is at least 10x noiser than the
> AP192, some have lots of spurs others are quieter). For a
> long enough averaging time the system noise level even with a
> cheap card will be somewhat lower than any OCXO you are
> likely to have.
> A cheap card will at least establish that in principle the
> technique works.
> You can then decide whether to upgrade it.
>
> The AP192 cards only have 2 input channels.
>
> Real AD cards with adequate performance are usually far more
> expensive than $300.
> In principle, one could build an ADC card with adequate
> performance using 4 AD7760 ADCs.
>
> Bruce
>

http://www.hpsdr.com/ Janus module is available built and PCB from TAPR (http://www.tapr.org/)  Has a AKM AK5394 ADC on it, as well as a lower quality DAC. $163 assembled and tested.

http://hpsdr.org/wiki/index.php?title=JANUS

Claiming 120dB SNR, 20bit ENOB at 192ksps


From bruce.griffiths at xtra.co.nz  Wed Dec  3 01:16:33 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Wed, 03 Dec 2008 14:16:33 +1300
Subject: [time-nuts] Soundcard sampling Re:  Picking a good HP 10811
In-Reply-To: <ECE7A93BD093E1439C20020FBE87C47FEB55C30E8C@ALTPHYEMBEVSP20.RES.AD.JPL>
References: <C55A795C.30E8%James.P.Lux@jpl.nasa.gov>	<493580D6.3030005@xtra.co.nz>
	<493595CB.6080407@xtra.co.nz>	<49359EBC.5060207@xtra.co.nz>	<843943.62160.qm@web30303.mail.mud.yahoo.com>	<ECE7A93BD093E1439C20020FBE87C47FEB55C30E5F@ALTPHYEMBEVSP20.RES.AD.JPL>	<562899.17240.qm@web30303.mail.mud.yahoo.com>
	<ECE7A93BD093E1439C20020FBE87C47FEB55C30E8C@ALTPHYEMBEVSP20.RES.AD.JPL>
Message-ID: <4935DDF1.3080706@xtra.co.nz>

Lux, James P wrote:
>> Maybe you all missed the part where I was complaining about
>> the $15 mixers so my investment in sound cards must be less
>> than that, would think that at $300 you should be able to get
>> a real A/D card that would allow a beat frequency down to DC.
>>     
>
> I think you'd have a hard time finding a very high performance A/D card with DC coupling.  The high end audio recording market is where it's at for performance, because they have economies of scale. You might be able to get an eval board from Wolfson or TDK or whoever makes these hotstuff ADCs, but by the time you lash em up, and deal with the inevitable clunky interface, you might be better off just finding a used FA66 or something.  I see M-audio Delta 44 Pro's for $75-80 on Ebay right now or used for $50 (I also see one for $15, but that's too cheap, so it must be just the manual or something.. )
>
>
>
>   
>> Should I even try with my cheap no name cards ?
>>     
>
> Sure.. Why not.
>
>   
>> Bruce looks like the M-audio is $179 the specs look great if
>> almost too good, guess I should save my pennies.
>> http://www.digitalconnection.com/products/audio/ap192.asp  (
>> first site goggle turned up, did not look further )
>>     
> http://www.m-audio.com/ is the mfr website.
>
> Well.. The data sheet claims 100+dB SNR, but one might want to see some independent testing.  But, in general, this is a plausible and practical level of performance.  At this level, pretty subtle stuff like wiring layout and connectors starts to be an issue.  The amateur software radio folks have been obsessing about this kind of thing, since the dynamic range of the ADC determines the ultimate performance of the receiver in a mixed signal environment (e.g. A figure of merit for receivers is how strong can a signal 2 kHz away be from the desired signal that's right at the noise floor).  The popular design for the receiver is a direct conversion scheme using a 4 way mux driven by a quadrature LO from a DDS, generating an I/Q audio output.
>
>   
The noise level with nothing connected to the inputs appears consistent
with the specifications.

>> Assume the one card would be 4 channels they do say multi
>> card support but with an * and the clock problem would need a
>> fix not sure I would take the solder to it till the 1 year
>> warranty is gone but then 4 channels would work.
>>     
>
>
>
> The AP192 is a 2 channel card, but it might have a word clock input or similar.
>
>   
The AP192 can lock to an SPDIF input, other than that there is no direct
means of synchronising 2 or more cards.
However locking to the SPDIF input tends to degrade the performance.
For more than 2 channels other cards may be a better choice unless one
modifies the card.
For a single dual mixer system this isnt an issue.

As part of the algorithm testing/development process one can forgo the
RF mixers and just feed a couple of audio signals into the sound card.
Once the algorithms are working the RF mixers LO synthesizer etc can
then be added to the system for the next round of testing.

Bruce


From james.p.lux at jpl.nasa.gov  Wed Dec  3 01:23:08 2008
From: james.p.lux at jpl.nasa.gov (Lux, James P)
Date: Tue, 2 Dec 2008 17:23:08 -0800
Subject: [time-nuts] Soundcard sampling Re:  Picking a good HP 10811
In-Reply-To: <4935D235.8090200@xtra.co.nz>
References: <C55A795C.30E8%James.P.Lux@jpl.nasa.gov>
	<493580D6.3030005@xtra.co.nz>	<493595CB.6080407@xtra.co.nz>
	<49359EBC.5060207@xtra.co.nz>	<843943.62160.qm@web30303.mail.mud.yahoo.com>
	<ECE7A93BD093E1439C20020FBE87C47FEB55C30E5F@ALTPHYEMBEVSP20.RES.AD.JPL>
	<562899.17240.qm@web30303.mail.mud.yahoo.com>
	<4935D235.8090200@xtra.co.nz>
Message-ID: <ECE7A93BD093E1439C20020FBE87C47FEB55C30E95@ALTPHYEMBEVSP20.RES.AD.JPL>



>
> Real AD cards with adequate performance are usually far more
> expensive than $300.
> In principle, one could build an ADC card with adequate
> performance using 4 AD7760 ADCs.
>
> Bruce
>
> ____

The AD7760 eval board is $150, and I think you need another board to hook it up to a computer.  However, if you have a couple kilobuck budget (i.e. you're doing this for work), then stacking up 4 of these eval boards might be a decent way to get started.

The AD7760s themselves are $36 each (Qty:1000).. The eval board is 4 layers, so that's within the realm of inexpensive prototyping, if you were to lay out a board.  Scrounging, etc., you could probably put something together for a few hundred bucks with pretty decent performance.

If it were me, though, I'd look at the high quality pro widgets already assembled, and spend my precious hours writing software to do the data reduction from the captured WAV files.

( I note that the DMTD box they have here at JPL (Greenhall, Kirk, and Tjoelker) is reported as having a noise floor Allan dev of <1E-17 at 1000s, driving the commercial synthesizer offset generator and two inputs with the same H-maser.. And it is a straight counter style measurement (123Hz))



From bruce.griffiths at xtra.co.nz  Wed Dec  3 01:40:23 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Wed, 03 Dec 2008 14:40:23 +1300
Subject: [time-nuts] Soundcard sampling Re:  Picking a good HP 10811
In-Reply-To: <ECE7A93BD093E1439C20020FBE87C47FEB55C30E95@ALTPHYEMBEVSP20.RES.AD.JPL>
References: <C55A795C.30E8%James.P.Lux@jpl.nasa.gov>	<493580D6.3030005@xtra.co.nz>	<493595CB.6080407@xtra.co.nz>	<49359EBC.5060207@xtra.co.nz>	<843943.62160.qm@web30303.mail.mud.yahoo.com>	<ECE7A93BD093E1439C20020FBE87C47FEB55C30E5F@ALTPHYEMBEVSP20.RES.AD.JPL>	<562899.17240.qm@web30303.mail.mud.yahoo.com>	<4935D235.8090200@xtra.co.nz>
	<ECE7A93BD093E1439C20020FBE87C47FEB55C30E95@ALTPHYEMBEVSP20.RES.AD.JPL>
Message-ID: <4935E387.3000403@xtra.co.nz>

Lux, James P wrote:
>   
>> Real AD cards with adequate performance are usually far more
>> expensive than $300.
>> In principle, one could build an ADC card with adequate
>> performance using 4 AD7760 ADCs.
>>
>> Bruce
>>
>> ____
>>     
>
> The AD7760 eval board is $150, and I think you need another board to hook it up to a computer.  However, if you have a couple kilobuck budget (i.e. you're doing this for work), then stacking up 4 of these eval boards might be a decent way to get started.
>
> The AD7760s themselves are $36 each (Qty:1000).. The eval board is 4 layers, so that's within the realm of inexpensive prototyping, if you were to lay out a board.  Scrounging, etc., you could probably put something together for a few hundred bucks with pretty decent performance.
>
> If it were me, though, I'd look at the high quality pro widgets already assembled, and spend my precious hours writing software to do the data reduction from the captured WAV files.
>
> ( I note that the DMTD box they have here at JPL (Greenhall, Kirk, and Tjoelker) is reported as having a noise floor Allan dev of <1E-17 at 1000s, driving the commercial synthesizer offset generator and two inputs with the same H-maser.. And it is a straight counter style measurement (123Hz))
>
>
>   
The mixer RF input frequency is 100MHz for that system.
The beat frequency slope amplifier/limiters in previous incarnations had
a performance some way from that of a more optimum design.
Achieving an equivalent performance with 10MHz inputs would be somewhat
challenging.
I wouldn't expect to do quite as well with a sound card based system
perhaps an order of magnitude or so worse (at least for Tau< 100s).
When comparing such systems it is necessary to know the system noise
bandwidth.

Bruce


From stanley_reynolds at yahoo.com  Wed Dec  3 02:22:05 2008
From: stanley_reynolds at yahoo.com (Stanley Reynolds)
Date: Tue, 2 Dec 2008 18:22:05 -0800 (PST)
Subject: [time-nuts] Soundcard sampling Re:  Picking a good HP 10811
References: <C55A795C.30E8%James.P.Lux@jpl.nasa.gov>
	<493580D6.3030005@xtra.co.nz> <493595CB.6080407@xtra.co.nz>
	<49359EBC.5060207@xtra.co.nz>
	<843943.62160.qm@web30303.mail.mud.yahoo.com>
	<ECE7A93BD093E1439C20020FBE87C47FEB55C30E5F@ALTPHYEMBEVSP20.RES.AD.JPL>
	<562899.17240.qm@web30303.mail.mud.yahoo.com>
	<4935D235.8090200@xtra.co.nz>
	<ECE7A93BD093E1439C20020FBE87C47FEB55C30E95@ALTPHYEMBEVSP20.RES.AD.JPL>
	<4935E387.3000403@xtra.co.nz>
Message-ID: <900027.19405.qm@web30303.mail.mud.yahoo.com>

Found a basic common base amp would need to adjust values for 10Mhz

<a href="http://s307.photobucket.com/albums/nn306/stanleyreynolds/?action=view&current=commonbaseamp2.jpg" target="_blank"><img src="http://i307.photobucket.com/albums/nn306/stanleyreynolds/commonbaseamp2.jpg" border="0" alt="Photobucket"></a>

and this common emitter :

<a href="http://s307.photobucket.com/albums/nn306/stanleyreynolds/?action=view&current=JPLCEtwostage.jpg" target="_blank"><img src="http://i307.photobucket.com/albums/nn306/stanleyreynolds/JPLCEtwostage.jpg" border="0" alt="Photobucket"></a>

Links if the html doesn't work :
http://i307.photobucket.com/albums/nn306/stanleyreynolds/commonbaseamp2.jpg
http://i307.photobucket.com/albums/nn306/stanleyreynolds/JPLCEtwostage.jpg

Did not find the circuit for the NIST design just a article that mentions it.

Stanley

From bruce.griffiths at xtra.co.nz  Wed Dec  3 02:31:50 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Wed, 03 Dec 2008 15:31:50 +1300
Subject: [time-nuts] Soundcard sampling Re:  Picking a good HP 10811
In-Reply-To: <900027.19405.qm@web30303.mail.mud.yahoo.com>
References: <C55A795C.30E8%James.P.Lux@jpl.nasa.gov>	<493580D6.3030005@xtra.co.nz>
	<493595CB.6080407@xtra.co.nz>	<49359EBC.5060207@xtra.co.nz>	<843943.62160.qm@web30303.mail.mud.yahoo.com>	<ECE7A93BD093E1439C20020FBE87C47FEB55C30E5F@ALTPHYEMBEVSP20.RES.AD.JPL>	<562899.17240.qm@web30303.mail.mud.yahoo.com>	<4935D235.8090200@xtra.co.nz>	<ECE7A93BD093E1439C20020FBE87C47FEB55C30E95@ALTPHYEMBEVSP20.RES.AD.JPL>	<4935E387.3000403@xtra.co.nz>
	<900027.19405.qm@web30303.mail.mud.yahoo.com>
Message-ID: <4935EF96.90701@xtra.co.nz>

Stanley Reynolds wrote:
> Found a basic common base amp would need to adjust values for 10Mhz
>
> <a href="http://s307.photobucket.com/albums/nn306/stanleyreynolds/?action=view&current=commonbaseamp2.jpg" target="_blank"><img src="http://i307.photobucket.com/albums/nn306/stanleyreynolds/commonbaseamp2.jpg" border="0" alt="Photobucket"></a>
>
> and this common emitter :
>
> <a href="http://s307.photobucket.com/albums/nn306/stanleyreynolds/?action=view&current=JPLCEtwostage.jpg" target="_blank"><img src="http://i307.photobucket.com/albums/nn306/stanleyreynolds/JPLCEtwostage.jpg" border="0" alt="Photobucket"></a>
>
> Links if the html doesn't work :
> http://i307.photobucket.com/albums/nn306/stanleyreynolds/commonbaseamp2.jpg
> http://i307.photobucket.com/albums/nn306/stanleyreynolds/JPLCEtwostage.jpg
>
> Did not find the circuit for the NIST design just a article that mentions it.
>
> Stanley
>
>   
Stanley

Most of those amplifiers would have poor close in phase noise performance.

The following page illustrates several isolation amplifier designs and
has links to most of the relevant papers from NIST and elsewhere.

http://www.ko4bb.com/~bruce/IsolationAmplifiers.html
<http://www.ko4bb.com/%7Ebruce/IsolationAmplifiers.html>

Bruce


From stanley_reynolds at yahoo.com  Wed Dec  3 02:32:27 2008
From: stanley_reynolds at yahoo.com (Stanley Reynolds)
Date: Tue, 2 Dec 2008 18:32:27 -0800 (PST)
Subject: [time-nuts] Soundcard sampling Re: Picking a good HP 10811
Message-ID: <844997.19904.qm@web30307.mail.mud.yahoo.com>

Found a basic common base amp would need to adjust values for 10Mhz
http://i307.photobucket.com/albums/nn306/stanleyreynolds/commonbaseamp2.jpg
and this common emitter :
http://i307.photobucket.com/albums/nn306/stanleyreynolds/JPLCEtwostage.jpg

Did not find the circuit for the NIST design just a article that mentions it.

Stanley

From stanley_reynolds at yahoo.com  Wed Dec  3 02:40:35 2008
From: stanley_reynolds at yahoo.com (Stanley Reynolds)
Date: Tue, 2 Dec 2008 18:40:35 -0800 (PST)
Subject: [time-nuts] Soundcard sampling Re: Picking a good HP 10811
References: <844997.19904.qm@web30307.mail.mud.yahoo.com>
Message-ID: <385223.33012.qm@web30303.mail.mud.yahoo.com>

Thanks Bruce,

Found it and reading ...

Stanley




________________________________
From: Stanley Reynolds <stanley_reynolds at yahoo.com>
To: time-nuts at febo.com
Sent: Tuesday, December 2, 2008 8:32:27 PM
Subject: Re: [time-nuts] Soundcard sampling Re: Picking a good HP 10811

Found a basic common base amp would need to adjust values for 10Mhz
http://i307.photobucket.com/albums/nn306/stanleyreynolds/commonbaseamp2.jpg
and this common emitter :
http://i307.photobucket.com/albums/nn306/stanleyreynolds/JPLCEtwostage.jpg

Did not find the circuit for the NIST design just a article that mentions it.

Stanley
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From kyrrin at bluefeathertech.com  Wed Dec  3 03:31:02 2008
From: kyrrin at bluefeathertech.com (Bruce Lane)
Date: Tue, 02 Dec 2008 19:31:02 -0800
Subject: [time-nuts] Odetics 325/425 owners, rejoice!
Message-ID: <200812021931020879.158F931B@192.168.42.129>

Fellow clock-tickers,

	Thanks to the generous assistance of a customer service rep at Magellan Navigation, I have received a full .PDF manual covering the Magellan OEM5000 receiver module used in many of the Odetics SatSync 325 and 425 GPS clock units.

	This manual contains full details on both ASCII and Magellan Binary outputs from the receiver, including that previously-elusive PMGLK sentence that was driving me nuts.

	The information in that manual, combined with a bit of hardware ingenuity in the microcontroller world and the Odetics equipment manual, should be enough to produce a hardware translation device which will (hopefully) allow the use of a standard (and much more readily available) NMEA-output receiver module. That's going to be a long-term project for me in the coming year.

	Anyone who wants to try and beat me to it is, of course, welcome. ;-)

	The manual may be found on the Blue Feather FTP archive.

	ftp.bluefeathertech.com

	Sign in as user ftp and the password can be anything you want (though I prefer an E-mail for logging purposes).

	The path is /electronics/radio/GPS/receivers/OEM/Magellan/oem5000

	The file name is OEM5K.pdf

	Happy reading.


-=-=-=-=-=-=-=-=-=-=-=-
Bruce Lane, Owner & Head Hardware Heavy,
Blue Feather Technologies -- http://www.bluefeathertech.com
kyrrin (at) bluefeathertech do/t c=o=m
"Quid Malmborg in Plano..."



From jim77742 at gmail.com  Wed Dec  3 04:56:37 2008
From: jim77742 at gmail.com (Jim Palfreyman)
Date: Wed, 3 Dec 2008 15:56:37 +1100
Subject: [time-nuts] Cesium vs H Maser clocks
In-Reply-To: <20081129121239.C74691165C3@hamburg.alientech.net>
References: <KB2L9L$F725B2677CC405A0E8CF71C9A05A75B2@libero.it>
	<DA795DE5C8AF4A17A671A30171BACAE3@pc52>
	<20081129014129.181471165C3@hamburg.alientech.net>
	<9FB14428535B4E0EAE3C34C33EE617F6@pc52>
	<20081129121239.C74691165C3@hamburg.alientech.net>
Message-ID: <f616e0f80812022056u7e2f62e8ra992cb079ec55a07@mail.gmail.com>

2008/11/29 Mike S <mikes at flatsurface.com>

> At 01:30 AM 11/29/2008, Tom Van Baak wrote...
> >Note also that clocks at NIST run about 1.8e-13 fast due to the high
> >elevation of Boulder, CO (general relativity), which is yet another
> >factor that has to be corrected for compared to the official sea-level
> >definition of the second.
>
> Do they really adjust to sea level on earth? That isn't part of the
> definition. Within that convention, as the mean sea level rises (~20 cm
> in the last 100 years), does the length of the second change
> (relatively)?
>
> A clock will run faster the lower the strength of the gravitational field.
Even though the mean sea level might rise 20cm in 100 years, it doesn't mean
the gravitational field is changing in any meaningful way in that time.
Daily tidal variations would be far greater.

One would assume the definition of the second is in reference to the
gravitational field at the surface of the mean geoid and has nothing to do
with sea level.

Jim

From namichie at gmail.com  Wed Dec  3 05:29:41 2008
From: namichie at gmail.com (Neville Michie)
Date: Wed, 3 Dec 2008 16:29:41 +1100
Subject: [time-nuts] Cesium vs H Maser clocks
In-Reply-To: <f616e0f80812022056u7e2f62e8ra992cb079ec55a07@mail.gmail.com>
References: <KB2L9L$F725B2677CC405A0E8CF71C9A05A75B2@libero.it>
	<DA795DE5C8AF4A17A671A30171BACAE3@pc52>
	<20081129014129.181471165C3@hamburg.alientech.net>
	<9FB14428535B4E0EAE3C34C33EE617F6@pc52>
	<20081129121239.C74691165C3@hamburg.alientech.net>
	<f616e0f80812022056u7e2f62e8ra992cb079ec55a07@mail.gmail.com>
Message-ID: <4E14ADF1-9A05-40C8-A670-9ADF0A1E5252@gmail.com>

Someone asked what a frequency time standard cam calibrate besides a  
clock.
Gravity is, or was, measured by throwing a corner cube into the air  
(vacuum)
and using a laser interferometer, timing its acceleration as it fell  
back.
All of that can be calibrated from a frequency standard, so unlike  
volts and things
gravity is one variable that frequency/time  can be used to define.
Although I dont think you will find a frequency/gravity transducer on  
fleabay.
cheers, Neville Michie




On 03/12/2008, at 3:56 PM, Jim Palfreyman wrote:

> 2008/11/29 Mike S <mikes at flatsurface.com>
>
>> At 01:30 AM 11/29/2008, Tom Van Baak wrote...
>>> Note also that clocks at NIST run about 1.8e-13 fast due to the high
>>> elevation of Boulder, CO (general relativity), which is yet another
>>> factor that has to be corrected for compared to the official sea- 
>>> level
>>> definition of the second.
>>
>> Do they really adjust to sea level on earth? That isn't part of the
>> definition. Within that convention, as the mean sea level rises  
>> (~20 cm
>> in the last 100 years), does the length of the second change
>> (relatively)?
>>
>> A clock will run faster the lower the strength of the  
>> gravitational field.
> Even though the mean sea level might rise 20cm in 100 years, it  
> doesn't mean
> the gravitational field is changing in any meaningful way in that  
> time.
> Daily tidal variations would be far greater.
>
> One would assume the definition of the second is in reference to the
> gravitational field at the surface of the mean geoid and has  
> nothing to do
> with sea level.
>
> Jim
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/ 
> time-nuts
> and follow the instructions there.



From hmurray at megapathdsl.net  Wed Dec  3 08:59:13 2008
From: hmurray at megapathdsl.net (Hal Murray)
Date: Wed, 03 Dec 2008 00:59:13 -0800
Subject: [time-nuts] Cesium vs H Maser clocks
In-Reply-To: Message from Neville Michie <namichie@gmail.com> of "Wed,
	03 Dec 2008 16:29:41 +1100."
	<4E14ADF1-9A05-40C8-A670-9ADF0A1E5252@gmail.com> 
Message-ID: <20081203085914.7DDEBBCD7@ip-64-139-1-69.sjc.megapath.net>


> Someone asked what a frequency time standard cam calibrate besides a
> clock. Gravity is, or was, measured by throwing a corner cube into the
> air (vacuum) and using a laser interferometer, timing its
> acceleration as it fell back. All of that can be calibrated from a
> frequency standard, so unlike volts and things gravity is one
> variable that frequency/time can be used to define. Although I dont
> think you will find a frequency/gravity transducer on fleabay. 

My head hurts.    What does relativity do to a laser interferometer?

Clocks are already good enough that they need to correct for 
elevation/gravity.  Is this getting circular?


In case anybody hasn't read it recently...

      Time Too Good to Be True, Daniel Kleppner
      Physics Today, March 2006, page 10

http://scitation.aip.org/journals/doc/PHTOAD-ft/vol_59/iss_3/10_1.shtml
http://www.physicstoday.org/vol-59/iss-3/pdf/vol59no3p10_11.pdf

The html version needs cookies.  The pdf version needs a non-old pdf reader.



-- 
These are my opinions, not necessarily my employer's.  I hate spam.





From hmurray at megapathdsl.net  Wed Dec  3 10:40:31 2008
From: hmurray at megapathdsl.net (Hal Murray)
Date: Wed, 03 Dec 2008 02:40:31 -0800
Subject: [time-nuts] V standards
In-Reply-To: Message from "Poul-Henning Kamp" <phk@phk.freebsd.dk> of "Tue,
	02 Dec 2008 13:48:55 GMT." <9264.1228225735@critter.freebsd.dk> 
Message-ID: <20081203104032.E3F3FBCD7@ip-64-139-1-69.sjc.megapath.net>


> You don't want 24bit PWM, you want to combine a normal DAC with PWM
> modulation.

> The disadvantage is that the result is not linear.  But it is
> monotonic and approximately the lower 4/5th of the distinct
> combinations are practically useful. 

Where is the non linearity coming from?

Why is only the bottom 4/5s useful?


> If you use a 16 - 18 bit fine dac, and 6 - 8 bits of a coarse dac then
> this works quite well, and with a low aging SC-cut crystal you may
> never see a coarsedac change, while still having over 21+ bits of
> overall resolution. 

How does the stability of a course DAC compare with a pot?


-- 
These are my opinions, not necessarily my employer's.  I hate spam.





From df6jb at ulrich-bangert.de  Wed Dec  3 10:45:48 2008
From: df6jb at ulrich-bangert.de (Ulrich Bangert)
Date: Wed, 3 Dec 2008 11:45:48 +0100
Subject: [time-nuts] Soundcard sampling Re: Picking a good HP 10811
In-Reply-To: <385223.33012.qm@web30303.mail.mud.yahoo.com>
Message-ID: <40AD965B34004FF8A9E5B8BA16D73BB9@athlon>

James and Stanley,

Bruce is already aware that I am doing sound card experiments since a
few years but you are not. 

That is why I would like to enter the discussion and encourage you to
perform some preliminary experiments on the topic that don't need the
real world existence of a suited sound card because you will generate
your "input" signals yourself the artificial way. This will enable you
to give your signals some known technical properties that are to be
found in real world signals too. 

I encourage you to test your algos for phase/frequency detection on
these artififial signals because if you discover problems with your algo
you will have an immediate understanding of the sources of your problems
(not necessarily a solution) because you made the signal in exactly this
way.

First generate yourself a sinusoidal signal at 1000 Hz and Amplitude 1
and a second at 1000.125 Hz and 80 dB down against the first signal. 

Const RunTime=1000;
      SampleRate=48000;
      f1=1000.0;
      f2=1000.125;
Var   I:Integer;
      Time:Double=0;
      Signal1,Signal2,Signal3:Double;

For I:=0 to (RunTime*SampleRate) do
begin;
  Time:=Time+1.0/SampleRate;
  Signal1:=Sin(2.0*Pi*f1*Time);
  Signal2:=1.0/10000.0*Sin(2.0*Pi*f2*Time);
  Signal3:=Signal1+Signal2;
end.

I write this down in a Pascalish style of language but it is easily
translated into any language of your choice. The thing modelled here are
two signals coming from a double mixer system with slightly different
frequencies. Typical cheap sound cards exhibit a crosstalk of -70 to -80
dB between the two channels. So Signal2 represents what is leaking from
channel 2 of the sound card into channel 1 of the soundcard and Signal3
repesents what you really find in channel 1 due to the crosstalk. 

Assumption is that the amplitude in channel 2 is close to "1" too.
Signal3 may be handled online or stored in a file or whatever you like.
Apply your algos to Signal3 and feed the results into an Tau-sigma
diagram, say on a second to second base (Tau0=1). The better your Algo
is the more you will see why I suggested this experiment.

Even -100 dB of crosstalk does not get you completely rid of this nasty
effect. You may even change the signals to integer entities and scale
not to "1" but to 32767 (for 16 bit resolution) to study the influence
of bit resolution of real world sound cards. After that experiment
decide yourself whether a cheap sound card with 80 dB channel separation
does the job.

After having understood that crosstalk is a limiting factor in using a
sound card for stability measurements I would like to draw your
attention to a case that has nothing to do with crosstalk at all but is
a fundamental property of ALL sampled systems with amplitude/time
quantization. Using something like:

Const RunTime=1000;
      SampleRate=48000;
      f1=1000.125;
Var   I:Integer;
      Time:Double=0;
      Signal1:Double;

For I:=0 to (RunTime*SampleRate) do
begin;
  Time:=Time+1.0/SampleRate;
  Signal1:=Round(32767.0*Sin(2.0*Pi*f1*Time)/32767.0;
end.

generate yourself a SINGLE signal of odd frequency and 16 bit
resolution. Apply your Algos to that and try to explain the small phase
modulation (similar to the crosstalk case) that you will find at a
repetition rate of 8 s. I know, the effect IS SMALL but after putting
your results into a tau-sigma diagram you notice how nasty it is
nevertheless.

I am writing you this because the real problems of a method are
sometimes to be found at places where one would not have expected them
at all.

Best regards
Ulrich Bangert
   

> -----Ursprungliche Nachricht-----
> Von: time-nuts-bounces at febo.com 
> [mailto:time-nuts-bounces at febo.com] Im Auftrag von Stanley Reynolds
> Gesendet: Mittwoch, 3. Dezember 2008 03:41
> An: Discussion of precise time and frequency measurement
> Betreff: Re: [time-nuts] Soundcard sampling Re: Picking a 
> good HP 10811
> 
> 
> Thanks Bruce,
> 
> Found it and reading ...
> 
> Stanley
> 
> 
> 
> 
> ________________________________
> From: Stanley Reynolds <stanley_reynolds at yahoo.com>
> To: time-nuts at febo.com
> Sent: Tuesday, December 2, 2008 8:32:27 PM
> Subject: Re: [time-nuts] Soundcard sampling Re: Picking a 
> good HP 10811
> 
> Found a basic common base amp would need to adjust values for 
> 10Mhz 
> http://i307.photobucket.com/albums/nn306/stanleyreynolds/commo
nbaseamp2.jpg
and this common emitter :
http://i307.photobucket.com/albums/nn306/stanleyreynolds/JPLCEtwostage.j
pg

Did not find the circuit for the NIST design just a article that
mentions it.

Stanley
_______________________________________________
time-nuts mailing list -- time-nuts at febo.com
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
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To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.



From phk at phk.freebsd.dk  Wed Dec  3 13:40:01 2008
From: phk at phk.freebsd.dk (Poul-Henning Kamp)
Date: Wed, 03 Dec 2008 13:40:01 +0000
Subject: [time-nuts] V standards
In-Reply-To: Your message of "Wed, 03 Dec 2008 02:40:31 PST."
	<20081203104032.E3F3FBCD7@ip-64-139-1-69.sjc.megapath.net> 
Message-ID: <37508.1228311601@critter.freebsd.dk>

In message <20081203104032.E3F3FBCD7 at ip-64-139-1-69.sjc.megapath.net>, Hal Murr
ay writes:

>> You don't want 24bit PWM, you want to combine a normal DAC with PWM
>> modulation.
>
>> The disadvantage is that the result is not linear.  But it is
>> monotonic and approximately the lower 4/5th of the distinct
>> combinations are practically useful. 
>
>Where is the non linearity coming from?
>
>Why is only the bottom 4/5s useful?

Because the DAC and PWM multiply instead of add:

Run this script and plot the '_f' file:

	#!/bin/sh
	echo | awk '
		{
		for (i = 0; i < 4096; i++) {
			for (j = 0; j < 1024; j++) {
				x = 3.3 * (i / 4096.) * (j / 1024.)
				printf "%12.9f\n", x
			}
		}
		}
	' | sort -u | tee /tmp/_f | wc -l

-- 
Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk at FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.


From pabloalvarezsanchez at gmail.com  Wed Dec  3 15:50:16 2008
From: pabloalvarezsanchez at gmail.com (pablo alvarez)
Date: Wed, 3 Dec 2008 16:50:16 +0100
Subject: [time-nuts] DMTD mixer question
Message-ID: <2ae26e4e0812030750i1e8b0af4x4e99ccafcfcf7812@mail.gmail.com>

Hi,

I have been looking at several Dual Mixer Time Difference designs. As
far as I know the basic architecture is based on generating a tone
with an small frequency offset respect to the nominal clocks
frequency, analogue mixing of the clocks, low pass filtering, then a
slow zero crossing detector and finally a time interval counter or
time stamp unit.

I have this na?f question: would not it be better and simpler to use
directly an ECL D flip-flop as a mixer instead of an analogue one? I
suppose analogue mixers are preferred because they provide with a
better "differential tempco", but using ECL logic can provide also
with a good tempco.

What is your experience?


Cheers

Pablo


From n3izn at aol.com  Wed Dec  3 18:33:35 2008
From: n3izn at aol.com (n3izn at aol.com)
Date: Wed, 03 Dec 2008 13:33:35 -0500
Subject: [time-nuts] Wenzel Associates 100 Mhz osc
In-Reply-To: <ECE7A93BD093E1439C20020FBE87C47FEB55C30CF2@ALTPHYEMBEVSP20.RES.AD.JPL>
References: <8CB2217415E3E1F-AD4-16D6@webmail-dd03.sysops.aol.com>
	<ECE7A93BD093E1439C20020FBE87C47FEB55C30CF2@ALTPHYEMBEVSP20.RES.AD.JPL>
Message-ID: <8CB238CC76F13B0-177C-E2@WEBMAIL-DY18.sysops.aol.com>

I have some drive time so I might give Wenzel a call and see how it goes.

Meanwhile I looked around some more and found some with PTI oscillators. The pins are laid out in a square where as the Wenzel unit is in a straight row. The attached cable is the same with the same colors so I'm going to guess I can find the power and control leads. I'll make a test set up and start playing. 

Got a few questions.

When it says 12 volts, most times 13.8~ 14 should be fine? These are labeled 12 volts.
Will that 12 volts need to be regulated?

Do the specs look?decent?

Here is a link to the PTI unit.?

http://www.mtronpti.com/pdf/xo5051_datasheet51607.pdf

Thanks
Chris





> -----Original Message-----
> From: time-nuts-bounces at febo.com
> [mailto:time-nuts-bounces at febo.com] On Behalf Of n3izn at aol.com
> Sent: Monday, December 01, 2008 2:00 PM
> To: time-nuts at febo.com
> Subject: [time-nuts] Wenzel Associates 100 Mhz osc
>
> I stumbled across a 100 Mhz oscillator. It comes from a
> Harris Constellation RX/TX.
>
> According to the website part number is proprietary. So I
> thought I would ask here or any info.
>
> Here is what is printed on it from top to bottom.
>
> 500-06769D
> ISSUE 02
> PPD 786-020590-053
> 100 Mhz
> +12 VDC
> 0105-0201SSRG
>
> It has a SMA female or 100 Mhz out and 4 pins for power and AFC?
>
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com To unsubscribe,
> go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>

_______________________________________________
time-nuts mailing list -- time-nuts at febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.


From james.p.lux at jpl.nasa.gov  Wed Dec  3 18:36:50 2008
From: james.p.lux at jpl.nasa.gov (Lux, James P)
Date: Wed, 3 Dec 2008 10:36:50 -0800
Subject: [time-nuts] DMTD mixer question
In-Reply-To: <2ae26e4e0812030750i1e8b0af4x4e99ccafcfcf7812@mail.gmail.com>
References: <2ae26e4e0812030750i1e8b0af4x4e99ccafcfcf7812@mail.gmail.com>
Message-ID: <ECE7A93BD093E1439C20020FBE87C47FEB55DA848F@ALTPHYEMBEVSP20.RES.AD.JPL>


> -----Original Message-----
> From: time-nuts-bounces at febo.com
> [mailto:time-nuts-bounces at febo.com] On Behalf Of pablo alvarez
> Sent: Wednesday, December 03, 2008 7:50 AM
> To: Discussion of precise time and frequency measurement
> Subject: [time-nuts] DMTD mixer question
>
> Hi,
>
> I have been looking at several Dual Mixer Time Difference
> designs. As far as I know the basic architecture is based on
> generating a tone with an small frequency offset respect to
> the nominal clocks frequency, analogue mixing of the clocks,
> low pass filtering, then a slow zero crossing detector and
> finally a time interval counter or time stamp unit.
>
> I have this na?f question: would not it be better and simpler
> to use directly an ECL D flip-flop as a mixer instead of an
> analogue one? I suppose analogue mixers are preferred because
> they provide with a better "differential tempco", but using
> ECL logic can provide also with a good tempco.
>

That's an interesting question. I know that some folks building microwave synthesizers for radio science applications (where very low phase noise and Allan deviation are of concern) are using the Phase Frequency Detector (basically a flip flop) in parts like the Peregrine PE9701 or PE3236, as opposed to a standard mixer.

Mind you, the data sheet
http://www.peregrine-semi.com/pdf/datasheets/pe9701ds.pdf

Says "ultra low phase noise" but doesn't actually give any numbers.

But the PE3236 does give at least one number, however it's for the full PLL, not just  the PFD contribution, which will be very small)
http://www.psemi.com/pdf/datasheets/pe3236ds.pdf

One reference (Cook, et al., 2004)  gives numbers of (at some unknown offset or measurement condition)
-165 dBc/Hz for TTL
-150 dBc/Hz for ECL
-130 dBc/Hz for CMOS

But those are easily 10 year old numbers, if not more, and may not be representative of modern technology (particularly the new CMOS processes).

I seem to recall seeing a number like -190dBc/Hz or -200dBc/Hz for these hot stuff PFDs, but I can't recall where, maybe Banerjee's PLL book?


From james.p.lux at jpl.nasa.gov  Wed Dec  3 18:38:31 2008
From: james.p.lux at jpl.nasa.gov (Lux, James P)
Date: Wed, 3 Dec 2008 10:38:31 -0800
Subject: [time-nuts] Wenzel Associates 100 Mhz osc
In-Reply-To: <8CB238CC76F13B0-177C-E2@WEBMAIL-DY18.sysops.aol.com>
References: <8CB2217415E3E1F-AD4-16D6@webmail-dd03.sysops.aol.com>
	<ECE7A93BD093E1439C20020FBE87C47FEB55C30CF2@ALTPHYEMBEVSP20.RES.AD.JPL>
	<8CB238CC76F13B0-177C-E2@WEBMAIL-DY18.sysops.aol.com>
Message-ID: <ECE7A93BD093E1439C20020FBE87C47FEB55DA8490@ALTPHYEMBEVSP20.RES.AD.JPL>

> -----Original Message-----
> From: time-nuts-bounces at febo.com
> [mailto:time-nuts-bounces at febo.com] On Behalf Of n3izn at aol.com
> Sent: Wednesday, December 03, 2008 10:34 AM
> To: time-nuts at febo.com
> Subject: Re: [time-nuts] Wenzel Associates 100 Mhz osc
>
> I have some drive time so I might give Wenzel a call and see
> how it goes.
>
> Meanwhile I looked around some more and found some with PTI
> oscillators. The pins are laid out in a square where as the
> Wenzel unit is in a straight row. The attached cable is the
> same with the same colors so I'm going to guess I can find
> the power and control leads. I'll make a test set up and
> start playing.
>
> Got a few questions.
>
> When it says 12 volts, most times 13.8~ 14 should be fine?
> These are labeled 12 volts.
> Will that 12 volts need to be regulated?


Depends on what sort of internal regulation there is in the box. There's almost certainly some, but, on the other hand, you're looking for high performance, and there's inevitably going to be some effect from changes in the supply (noise, etc.)


From jmfranke at cox.net  Wed Dec  3 18:46:24 2008
From: jmfranke at cox.net (John Franke)
Date: Wed, 3 Dec 2008 13:46:24 -0500
Subject: [time-nuts] Wenzel Associates 100 Mhz osc
References: <8CB2217415E3E1F-AD4-16D6@webmail-dd03.sysops.aol.com><ECE7A93BD093E1439C20020FBE87C47FEB55C30CF2@ALTPHYEMBEVSP20.RES.AD.JPL>
	<8CB238CC76F13B0-177C-E2@WEBMAIL-DY18.sysops.aol.com>
Message-ID: <62EE1EB6ACE04FEBA8C4AAD3C2FAAFB4@youre7075dc078>

If labeled 12V, that means 12V, not 12V automobile.

----- Original Message ----- 
From: <n3izn at aol.com>
To: <time-nuts at febo.com>
Sent: Wednesday, December 03, 2008 1:33 PM
Subject: Re: [time-nuts] Wenzel Associates 100 Mhz osc


>I have some drive time so I might give Wenzel a call and see how it goes.
>
> Meanwhile I looked around some more and found some with PTI oscillators. 
> The pins are laid out in a square where as the Wenzel unit is in a 
> straight row. The attached cable is the same with the same colors so I'm 
> going to guess I can find the power and control leads. I'll make a test 
> set up and start playing.
>
> Got a few questions.
>
> When it says 12 volts, most times 13.8~ 14 should be fine? These are 
> labeled 12 volts.
> Will that 12 volts need to be regulated?
>
> Do the specs look?decent?
>
> Here is a link to the PTI unit.?
>
> http://www.mtronpti.com/pdf/xo5051_datasheet51607.pdf
>
> Thanks
> Chris
>
>
>
>
>
>> -----Original Message-----
>> From: time-nuts-bounces at febo.com
>> [mailto:time-nuts-bounces at febo.com] On Behalf Of n3izn at aol.com
>> Sent: Monday, December 01, 2008 2:00 PM
>> To: time-nuts at febo.com
>> Subject: [time-nuts] Wenzel Associates 100 Mhz osc
>>
>> I stumbled across a 100 Mhz oscillator. It comes from a
>> Harris Constellation RX/TX.
>>
>> According to the website part number is proprietary. So I
>> thought I would ask here or any info.
>>
>> Here is what is printed on it from top to bottom.
>>
>> 500-06769D
>> ISSUE 02
>> PPD 786-020590-053
>> 100 Mhz
>> +12 VDC
>> 0105-0201SSRG
>>
>> It has a SMA female or 100 Mhz out and 4 pins for power and AFC?
>>
>> _______________________________________________
>> time-nuts mailing list -- time-nuts at febo.com To unsubscribe,
>> go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>> and follow the instructions there.
>>
>
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to 
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>
> _______________________________________________
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> To unsubscribe, go to 
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
> 



From bruce.griffiths at xtra.co.nz  Wed Dec  3 19:07:03 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Thu, 04 Dec 2008 08:07:03 +1300
Subject: [time-nuts] DMTD mixer question
In-Reply-To: <2ae26e4e0812030750i1e8b0af4x4e99ccafcfcf7812@mail.gmail.com>
References: <2ae26e4e0812030750i1e8b0af4x4e99ccafcfcf7812@mail.gmail.com>
Message-ID: <4936D8D7.70204@xtra.co.nz>

pablo alvarez wrote:
> Hi,
>
> I have been looking at several Dual Mixer Time Difference designs. As
> far as I know the basic architecture is based on generating a tone
> with an small frequency offset respect to the nominal clocks
> frequency, analogue mixing of the clocks, low pass filtering, then a
> slow zero crossing detector and finally a time interval counter or
> time stamp unit.
>
> I have this na?f question: would not it be better and simpler to use
> directly an ECL D flip-flop as a mixer instead of an analogue one? I
> suppose analogue mixers are preferred because they provide with a
> better "differential tempco", but using ECL logic can provide also
> with a good tempco.
>
> What is your experience?
>
>
> Cheers
>
> Pablo
>
>   
Pablo

Flipflop mixers tend to produce glitches at the beat frequency transitions.
A digital PFD in a PLL doesnt produce a beat frequency output when
locked so such glitches arent a problem,

Bruce


From james.p.lux at jpl.nasa.gov  Wed Dec  3 19:19:31 2008
From: james.p.lux at jpl.nasa.gov (Lux, James P)
Date: Wed, 3 Dec 2008 11:19:31 -0800
Subject: [time-nuts] DMTD mixer question
In-Reply-To: <4936D8D7.70204@xtra.co.nz>
References: <2ae26e4e0812030750i1e8b0af4x4e99ccafcfcf7812@mail.gmail.com>
	<4936D8D7.70204@xtra.co.nz>
Message-ID: <ECE7A93BD093E1439C20020FBE87C47FEB55DA84B2@ALTPHYEMBEVSP20.RES.AD.JPL>


> >
> > Cheers
> >
> > Pablo
> >
> >
> Pablo
>
> Flipflop mixers tend to produce glitches at the beat
> frequency transitions.
> A digital PFD in a PLL doesnt produce a beat frequency output
> when locked so such glitches arent a problem,
>

I don't know that this is the case with modern PLL PFDs.. If only because glitches at the transitions would cause other problems, so there's an incentive to get rid of them.


Jim


From hmurray at megapathdsl.net  Wed Dec  3 19:20:25 2008
From: hmurray at megapathdsl.net (Hal Murray)
Date: Wed, 03 Dec 2008 11:20:25 -0800
Subject: [time-nuts] Wenzel Associates 100 Mhz osc
In-Reply-To: Message from "John Franke" <jmfranke@cox.net> of "Wed,
	03 Dec 2008 13:46:24 EST."
	<62EE1EB6ACE04FEBA8C4AAD3C2FAAFB4@youre7075dc078> 
Message-ID: <20081203192026.0949EBCD7@ip-64-139-1-69.sjc.megapath.net>

> If labeled 12V, that means 12V, not 12V automobile.

It depends.

The data sheet at
> http://www.mtronpti.com/pdf/xo5051_datasheet51607.pdf
Doesn't say "12V".  It says
  Supply Voltage  Vs  12 to 15 Volts  Consult Factory

I don't know if that data sheet applies to the unit being considered.  If I 
was working without a good data sheet, I'd probably limit it to 12 V.

On the other hand, if the supply is primarily power for the oven, the voltage 
range is often fairly wide, at least on the data sheets I'm remembering right 
now.


-- 
These are my opinions, not necessarily my employer's.  I hate spam.





From bruce.griffiths at xtra.co.nz  Wed Dec  3 19:26:33 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Thu, 04 Dec 2008 08:26:33 +1300
Subject: [time-nuts] Soundcard sampling Re: Picking a good HP 10811
In-Reply-To: <40AD965B34004FF8A9E5B8BA16D73BB9@athlon>
References: <40AD965B34004FF8A9E5B8BA16D73BB9@athlon>
Message-ID: <4936DD69.3010003@xtra.co.nz>

Ulrich Bangert wrote:
> James and Stanley,
>
> Bruce is already aware that I am doing sound card experiments since a
> few years but you are not. 
>
> That is why I would like to enter the discussion and encourage you to
> perform some preliminary experiments on the topic that don't need the
> real world existence of a suited sound card because you will generate
> your "input" signals yourself the artificial way. This will enable you
> to give your signals some known technical properties that are to be
> found in real world signals too. 
>
> I encourage you to test your algos for phase/frequency detection on
> these artififial signals because if you discover problems with your algo
> you will have an immediate understanding of the sources of your problems
> (not necessarily a solution) because you made the signal in exactly this
> way.
>
> First generate yourself a sinusoidal signal at 1000 Hz and Amplitude 1
> and a second at 1000.125 Hz and 80 dB down against the first signal. 
>
> Const RunTime=1000;
>       SampleRate=48000;
>       f1=1000.0;
>       f2=1000.125;
> Var   I:Integer;
>       Time:Double=0;
>       Signal1,Signal2,Signal3:Double;
>
> For I:=0 to (RunTime*SampleRate) do
> begin;
>   Time:=Time+1.0/SampleRate;
>   Signal1:=Sin(2.0*Pi*f1*Time);
>   Signal2:=1.0/10000.0*Sin(2.0*Pi*f2*Time);
>   Signal3:=Signal1+Signal2;
> end.
>
> I write this down in a Pascalish style of language but it is easily
> translated into any language of your choice. The thing modelled here are
> two signals coming from a double mixer system with slightly different
> frequencies. Typical cheap sound cards exhibit a crosstalk of -70 to -80
> dB between the two channels. So Signal2 represents what is leaking from
> channel 2 of the sound card into channel 1 of the soundcard and Signal3
> repesents what you really find in channel 1 due to the crosstalk. 
>
> Assumption is that the amplitude in channel 2 is close to "1" too.
> Signal3 may be handled online or stored in a file or whatever you like.
> Apply your algos to Signal3 and feed the results into an Tau-sigma
> diagram, say on a second to second base (Tau0=1). The better your Algo
> is the more you will see why I suggested this experiment.
>
> Even -100 dB of crosstalk does not get you completely rid of this nasty
> effect. You may even change the signals to integer entities and scale
> not to "1" but to 32767 (for 16 bit resolution) to study the influence
> of bit resolution of real world sound cards. After that experiment
> decide yourself whether a cheap sound card with 80 dB channel separation
> does the job.
>
> After having understood that crosstalk is a limiting factor in using a
> sound card for stability measurements I would like to draw your
> attention to a case that has nothing to do with crosstalk at all but is
> a fundamental property of ALL sampled systems with amplitude/time
> quantization. Using something like:
>
> Const RunTime=1000;
>       SampleRate=48000;
>       f1=1000.125;
> Var   I:Integer;
>       Time:Double=0;
>       Signal1:Double;
>
> For I:=0 to (RunTime*SampleRate) do
> begin;
>   Time:=Time+1.0/SampleRate;
>   Signal1:=Round(32767.0*Sin(2.0*Pi*f1*Time)/32767.0;
> end.
>
> generate yourself a SINGLE signal of odd frequency and 16 bit
> resolution. Apply your Algos to that and try to explain the small phase
> modulation (similar to the crosstalk case) that you will find at a
> repetition rate of 8 s. I know, the effect IS SMALL but after putting
> your results into a tau-sigma diagram you notice how nasty it is
> nevertheless.
>
> I am writing you this because the real problems of a method are
> sometimes to be found at places where one would not have expected them
> at all.
>
> Best regards
> Ulrich Bangert
>    
>
>   
Ulrich

If the crosstalk is sufficiently stable to cause a significant problem,
then in principle the crosstalk transfer function can be measured and
used to mathematically cancel the crosstalk before extracting the
desired beat frequency phases.

Bruce


From bruce.griffiths at xtra.co.nz  Wed Dec  3 19:54:28 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Thu, 04 Dec 2008 08:54:28 +1300
Subject: [time-nuts] DMTD mixer question
In-Reply-To: <2ae26e4e0812030750i1e8b0af4x4e99ccafcfcf7812@mail.gmail.com>
References: <2ae26e4e0812030750i1e8b0af4x4e99ccafcfcf7812@mail.gmail.com>
Message-ID: <4936E3F4.8090309@xtra.co.nz>

pablo alvarez wrote:
> Hi,
>
> I have been looking at several Dual Mixer Time Difference designs. As
> far as I know the basic architecture is based on generating a tone
> with an small frequency offset respect to the nominal clocks
> frequency, analogue mixing of the clocks, low pass filtering, then a
> slow zero crossing detector and finally a time interval counter or
> time stamp unit.
>
> I have this na?f question: would not it be better and simpler to use
> directly an ECL D flip-flop as a mixer instead of an analogue one? I
> suppose analogue mixers are preferred because they provide with a
> better "differential tempco", but using ECL logic can provide also
> with a good tempco.
>
> What is your experience?
>
>
> Cheers
>
> Pablo
>
>   
Pablo

In principle one could use the metastability characteristics of a D
flipflop to produce high resolution timestamps of the coincidence
between transitions at the D input and the active clock edge.
For example, assemble a long flipflop based  shift register (only the
first few flipflops of which need be ECL or equivalent fast devices and
clock them at 10MHz whilst driving the input flipflop D input at 10MHz
-10Hz.
The phase of the clock advances by 100fs with respect to the D input
ever 10MHz period.
Ideally the probability the the input flipflop will change state
increases smoothly as the D and clock input transitions approach
coincidence.
Thus a high resolution timestamp of the coincidence between the D and
CLK input signal transitions could, in principle, be derived from the
sequence of flipflop transitions captured by the flipflops in the shift
register.
In practice crosstalk and other non ideal effects will reduce the
achievable resolution.

Bruce


From bruce.griffiths at xtra.co.nz  Wed Dec  3 20:01:52 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Thu, 04 Dec 2008 09:01:52 +1300
Subject: [time-nuts] DMTD mixer question
In-Reply-To: <ECE7A93BD093E1439C20020FBE87C47FEB55DA84B2@ALTPHYEMBEVSP20.RES.AD.JPL>
References: <2ae26e4e0812030750i1e8b0af4x4e99ccafcfcf7812@mail.gmail.com>	<4936D8D7.70204@xtra.co.nz>
	<ECE7A93BD093E1439C20020FBE87C47FEB55DA84B2@ALTPHYEMBEVSP20.RES.AD.JPL>
Message-ID: <4936E5B0.2070201@xtra.co.nz>

Lux, James P wrote:
>>> Cheers
>>>
>>> Pablo
>>>
>>>
>>>       
>> Pablo
>>
>> Flipflop mixers tend to produce glitches at the beat
>> frequency transitions.
>> A digital PFD in a PLL doesnt produce a beat frequency output
>> when locked so such glitches arent a problem,
>>
>>     
>
> I don't know that this is the case with modern PLL PFDs.. If only because glitches at the transitions would cause other problems, so there's an incentive to get rid of them.
>
>
> Jim
>
>   
Surely metastability may occur when the mixer flipflop D input
transitions occur close to its active clock transitions?

There is at least one patent (US5053651) that claims to eliminate such
glitches in a digital mixer, however its output beat frequency is half
the difference between the input frequencies.

Bruce


From bruce.griffiths at xtra.co.nz  Wed Dec  3 21:54:05 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Thu, 04 Dec 2008 10:54:05 +1300
Subject: [time-nuts] Soundcard sampling
In-Reply-To: <ECE7A93BD093E1439C20020FBE87C47FEB55C30E8F@ALTPHYEMBEVSP20.RES.AD.JPL>
References: <C55A795C.30E8%James.P.Lux@jpl.nasa.gov>	<493580D6.3030005@xtra.co.nz>	<493595CB.6080407@xtra.co.nz>	<49359EBC.5060207@xtra.co.nz>	<843943.62160.qm@web30303.mail.mud.yahoo.com>	<4935C662.3060809@xtra.co.nz>	<ECE7A93BD093E1439C20020FBE87C47FEB55C30E79@ALTPHYEMBEVSP20.RES.AD.JPL>	<4935CF95.5080403@xtra.co.nz>
	<ECE7A93BD093E1439C20020FBE87C47FEB55C30E8F@ALTPHYEMBEVSP20.RES.AD.JPL>
Message-ID: <4936FFFD.5090400@xtra.co.nz>

Lux, James P wrote:
>
> There's low phase noise oscillators intended for the SONET market from Valpey Fisher, etc. that have fairly good performance. A VF161 is a <$50 sort of part and is speced at 1ps jitter (1 sigma, fj>1kHz).  VF has "jitter attenuators" too, which are a low jitter pll with <0.18ps jitter (RMS 12kHz-20MHz)..
>
> Pick a XO at 200-300 MHz or so (whatever frequency is readily available), then set your DDS for a "spur free" frequency (where it divides nicely into the SIN table size)  (on the AD9584 running at 200MHz which has a 48 bit phase accumulator, 17 bit phase table, and a 12 bit DAC, these are about every 3 kHz or so)
>   

An AD9835 based synthesizer clocked at 50MHz (conveniently generated by multiplying a low phase noise 10MHz source by 5 using a diode or equivalent performance odd order frequency multiplier) is readily available at relatively low cost.

Since the phase is truncated to 12 bits within the AD9835, phase
truncation spur free outputs are available at harmonics of 50MHz/4096
(12207.03125Hz).
Conveniently the 819 harmonic of 50MHz/4096 (9.997558.59375MHz) produces
a beat frequency of about 2441.40625 Hz when mixed with a 10MHz signal.
When the input frequencies to be compared are 5MHz then either the above
frequency can be divided by 2 to produce a nominal 1220.703125 Hz beat
frequency or the 410th harmonic of 12207.03125 Hz can be employed to
produce a 4882.8125Hz beat frequency.

All of these beat frequencies are well within the frequency range of a
sound card.

Bruce


From cdelect at juno.com  Wed Dec  3 22:12:25 2008
From: cdelect at juno.com (Corby Dawson)
Date: Wed, 3 Dec 2008 14:12:25 -0800
Subject: [time-nuts] Cesium tube ion pumps
Message-ID: <20081203.141226.3192.4.cdelect@juno.com>

David,

The long storage is not the cause. Extended operation of the ion pump
causes the "whiskers" to grow. They can give rise to field emission
leakage currents.

This manifests as a raised ion pump current but does not inhibit proper
operation unless the current gets too high.

I don't remember at what current a 5071A will shut down at but I can take
a look in the manual.

Corby
____________________________________________________________
Click here for free information on how to reduce your debt by filing for bankruptcy.
http://thirdpartyoffers.juno.com/TGL2141/fc/PnY6rw22U6KSiqbzGnzo8ijTIrFXhPWyQU8EVhPuk3kNAOgi96JqR/

From aceamusements at mchsi.com  Wed Dec  3 23:27:45 2008
From: aceamusements at mchsi.com (aceamusements at mchsi.com)
Date: Wed, 03 Dec 2008 23:27:45 +0000
Subject: [time-nuts] Cesium tube ion pumps
Message-ID: <120320082327.11382.493715F0000939D600002C76219791299503010CD2079C080C03BF9C9B020A030A9C9A030E0A0C0E@mchsi.com>

Corby,

AT what point would be approp to call symmetricom and complain about defective
tube?I still have 2 years on the 5 yr warranty left, but how do u explain this
(defect),,(I assume it will just keep rising and eventually ruin the tube within
a few yrs?)last I checked they wanted about 28k for a new tube.

the unit with high perf tube has 5 yr warr from date of manuf. and cost 59k new.


----------------------  Original Message:  ---------------------
From:    Corby Dawson <cdelect at juno.com>
To:      time-nuts at febo.com
Subject: [time-nuts] Cesium tube ion pumps
Date:    Wed, 3 Dec 2008 22:11:16 +0000

> David,
> 
> The long storage is not the cause. Extended operation of the ion pump
> causes the "whiskers" to grow. They can give rise to field emission
> leakage currents.
> 
> This manifests as a raised ion pump current but does not inhibit proper
> operation unless the current gets too high.
> 
> I don't remember at what current a 5071A will shut down at but I can take
> a look in the manual.
> 
> Corby
> ____________________________________________________________
> Click here for free information on how to reduce your debt by filing for 
> bankruptcy.
> http://thirdpartyoffers.juno.com/TGL2141/fc/PnY6rw22U6KSiqbzGnzo8ijTIrFXhPWyQU8E
> VhPuk3kNAOgi96JqR/
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.


From pabloalvarezsanchez at gmail.com  Wed Dec  3 23:48:35 2008
From: pabloalvarezsanchez at gmail.com (pablo alvarez)
Date: Thu, 4 Dec 2008 00:48:35 +0100
Subject: [time-nuts] DMTD mixer question
In-Reply-To: <4936E5B0.2070201@xtra.co.nz>
References: <2ae26e4e0812030750i1e8b0af4x4e99ccafcfcf7812@mail.gmail.com>
	<4936D8D7.70204@xtra.co.nz>
	<ECE7A93BD093E1439C20020FBE87C47FEB55DA84B2@ALTPHYEMBEVSP20.RES.AD.JPL>
	<4936E5B0.2070201@xtra.co.nz>
Message-ID: <2ae26e4e0812031548te0e935awcd007815ccc490a4@mail.gmail.com>

thanks for the positive feedback,

In xilinx fpgas, for example, the recovery time after a metastability
issue is quite fast as reported in this paper

http://www.xilinx.com/support/documentation/application_notes/xapp094.pdf

The capture window of metastable state is 0.01fm (page 2). Probably
this window is moving around a bit, but this 0.01fm sounds promising.

In page 3 "When granted 2 ns of extra settling delay, the problems
caused by metastability are almost eliminated, as their MTBF exceeds
millions of years."

So we can just solve the glitch problem by adding a shift register as
Bruce suggested.  I think the major concern may be crosstalk, but
using lvds or ecl logic and placing the IOs far away one from each
other may help to reduce it a bit.


Now a DMTD architecture can be almost completely based on a FPGA where
some LVDS  IOs would contain the D flip-flop mixers, with their clock
input connected to the reference frequency and the D input to the
clocks under test. The FPGA would contain a 32 bit free running
counter clocked by the reference clock. Every time I detect a
transition on my LVDS IOs the free running counter is latched and
passed to a FIFO. Then the work can be passed to a data analysis
program (of course through an LVDS serial link)  to do all sort of
funny calculations.

I wonder how good this system could eventually be if we reduce
crosstalk to a minimum.


Pablo



On Wed, Dec 3, 2008 at 9:01 PM, Bruce Griffiths
<bruce.griffiths at xtra.co.nz> wrote:
> Lux, James P wrote:
>>>> Cheers
>>>>
>>>> Pablo
>>>>
>>>>
>>>>
>>> Pablo
>>>
>>> Flipflop mixers tend to produce glitches at the beat
>>> frequency transitions.
>>> A digital PFD in a PLL doesnt produce a beat frequency output
>>> when locked so such glitches arent a problem,
>>>
>>>
>>
>> I don't know that this is the case with modern PLL PFDs.. If only because glitches at the transitions would cause other problems, so there's an incentive to get rid of them.
>>
>>
>> Jim
>>
>>
> Surely metastability may occur when the mixer flipflop D input
> transitions occur close to its active clock transitions?
>
> There is at least one patent (US5053651) that claims to eliminate such
> glitches in a digital mixer, however its output beat frequency is half
> the difference between the input frequencies.
>
> Bruce
>
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>


From imp at bsdimp.com  Wed Dec  3 23:47:39 2008
From: imp at bsdimp.com (M. Warner Losh)
Date: Wed, 03 Dec 2008 16:47:39 -0700 (MST)
Subject: [time-nuts] Cesium tube ion pumps
In-Reply-To: <120320082327.11382.493715F0000939D600002C76219791299503010CD2079C080C03BF9C9B020A030A9C9A030E0A0C0E@mchsi.com>
References: <120320082327.11382.493715F0000939D600002C76219791299503010CD2079C080C03BF9C9B020A030A9C9A030E0A0C0E@mchsi.com>
Message-ID: <20081203.164739.1474627791.imp@bsdimp.com>

In message: <120320082327.11382.493715F0000939D600002C76219791299503010CD2079C080C03BF9C9B020A030A9C9A030E0A0C0E at mchsi.com>
            aceamusements at mchsi.com writes:
: Corby,
: 
: AT what point would be approp to call symmetricom and complain about defective
: tube?I still have 2 years on the 5 yr warranty left, but how do u explain this
: (defect),,(I assume it will just keep rising and eventually ruin the tube within
: a few yrs?)last I checked they wanted about 28k for a new tube.
: 
: the unit with high perf tube has 5 yr warr from date of manuf. and cost 59k new.

You should call them and find what their replacement policy for tubes
is.  They might not define it as defective now, but can tell you when
they will define it as such...

Warner


From wb6bnq at cox.net  Thu Dec  4 00:01:05 2008
From: wb6bnq at cox.net (WB6BNQ)
Date: Wed, 03 Dec 2008 16:01:05 -0800
Subject: [time-nuts] Cesium tube ion pumps
References: <120320082327.11382.493715F0000939D600002C76219791299503010CD2079C080C03BF9C9B020A030A9C9A030E0A0C0E@mchsi.com>
Message-ID: <49371DC1.B87BFAF6@cox.net>

David,

It would seem to me that while you have a warranty it would be prudent to exercise
such a warranty.  Otherwise, you will be fooling around till the last minute and be
out of luck.

If it sat "off" for three years and you have only had it operating for a short while,
unless I misunderstand something, it seems that there may have been a problem with
tube from the start ?  Out of curiousity, perhaps Corby can enlighten us on that
aspect ?

Bill....WB6BNQ


aceamusements at mchsi.com wrote:

> Corby,
>
> AT what point would be approp to call symmetricom and complain about defective
> tube?I still have 2 years on the 5 yr warranty left, but how do u explain this
> (defect),,(I assume it will just keep rising and eventually ruin the tube within
> a few yrs?)last I checked they wanted about 28k for a new tube.
>
> the unit with high perf tube has 5 yr warr from date of manuf. and cost 59k new.
>
> ----------------------  Original Message:  ---------------------
> From:    Corby Dawson <cdelect at juno.com>
> To:      time-nuts at febo.com
> Subject: [time-nuts] Cesium tube ion pumps
> Date:    Wed, 3 Dec 2008 22:11:16 +0000
>
> > David,
> >
> > The long storage is not the cause. Extended operation of the ion pump
> > causes the "whiskers" to grow. They can give rise to field emission
> > leakage currents.
> >
> > This manifests as a raised ion pump current but does not inhibit proper
> > operation unless the current gets too high.
> >
> > I don't remember at what current a 5071A will shut down at but I can take
> > a look in the manual.
> >
> > Corby
> > ____________________________________________________________
> > Click here for free information on how to reduce your debt by filing for
> > bankruptcy.
> > http://thirdpartyoffers.juno.com/TGL2141/fc/PnY6rw22U6KSiqbzGnzo8ijTIrFXhPWyQU8E
> > VhPuk3kNAOgi96JqR/
> > _______________________________________________
> > time-nuts mailing list -- time-nuts at febo.com
> > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> > and follow the instructions there.
>
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.



From bruce.griffiths at xtra.co.nz  Thu Dec  4 01:04:38 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Thu, 04 Dec 2008 14:04:38 +1300
Subject: [time-nuts] DMTD mixer question
In-Reply-To: <2ae26e4e0812031548te0e935awcd007815ccc490a4@mail.gmail.com>
References: <2ae26e4e0812030750i1e8b0af4x4e99ccafcfcf7812@mail.gmail.com>	<4936D8D7.70204@xtra.co.nz>	<ECE7A93BD093E1439C20020FBE87C47FEB55DA84B2@ALTPHYEMBEVSP20.RES.AD.JPL>	<4936E5B0.2070201@xtra.co.nz>
	<2ae26e4e0812031548te0e935awcd007815ccc490a4@mail.gmail.com>
Message-ID: <49372CA6.3000407@xtra.co.nz>

pablo alvarez wrote:
> thanks for the positive feedback,
>
> In xilinx fpgas, for example, the recovery time after a metastability
> issue is quite fast as reported in this paper
>
> http://www.xilinx.com/support/documentation/application_notes/xapp094.pdf
>
> The capture window of metastable state is 0.01fm (page 2). Probably
> this window is moving around a bit, but this 0.01fm sounds promising.
>
> In page 3 "When granted 2 ns of extra settling delay, the problems
> caused by metastability are almost eliminated, as their MTBF exceeds
> millions of years."
>
> So we can just solve the glitch problem by adding a shift register as
> Bruce suggested.  I think the major concern may be crosstalk, but
> using lvds or ecl logic and placing the IOs far away one from each
> other may help to reduce it a bit.
>
>
> Now a DMTD architecture can be almost completely based on a FPGA where
> some LVDS  IOs would contain the D flip-flop mixers, with their clock
> input connected to the reference frequency and the D input to the
> clocks under test. The FPGA would contain a 32 bit free running
> counter clocked by the reference clock. Every time I detect a
> transition on my LVDS IOs the free running counter is latched and
> passed to a FIFO. Then the work can be passed to a data analysis
> program (of course through an LVDS serial link)  to do all sort of
> funny calculations.
>
> I wonder how good this system could eventually be if we reduce
> crosstalk to a minimum.
>
>
> Pablo
>
>
>
> On Wed, Dec 3, 2008 at 9:01 PM, Bruce Griffiths
> <bruce.griffiths at xtra.co.nz> wrote:
>   
>> Lux, James P wrote:
>>     
>>>>> Cheers
>>>>>
>>>>> Pablo
>>>>>
>>>>>
>>>>>
>>>>>           
>>>> Pablo
>>>>
>>>> Flipflop mixers tend to produce glitches at the beat
>>>> frequency transitions.
>>>> A digital PFD in a PLL doesnt produce a beat frequency output
>>>> when locked so such glitches arent a problem,
>>>>
>>>>
>>>>         
>>> I don't know that this is the case with modern PLL PFDs.. If only because glitches at the transitions would cause other problems, so there's an incentive to get rid of them.
>>>
>>>
>>> Jim
>>>
>>>
>>>       
>> Surely metastability may occur when the mixer flipflop D input
>> transitions occur close to its active clock transitions?
>>
>> There is at least one patent (US5053651) that claims to eliminate such
>> glitches in a digital mixer, however its output beat frequency is half
>> the difference between the input frequencies.
>>
>> Bruce
>>
>>     
Pablo

You could also run several such digital mixers in parallel to exploit
statistical process variations and increase the number of transitions
associated with each coincidence of the clock and D input transitions.
Crosstalk in this case may be even more problematic, however statistical
process variations have been exploited to improve the resolution of
arbiters by driving several of them in parallel.

An FPGA based DMTD should reduce costs considerably and would perhaps
put such systems within the financial reach of more time nuts.

Bruce



From bruce.griffiths at xtra.co.nz  Thu Dec  4 01:18:41 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Thu, 04 Dec 2008 14:18:41 +1300
Subject: [time-nuts] DMTD mixer question
In-Reply-To: <2ae26e4e0812031548te0e935awcd007815ccc490a4@mail.gmail.com>
References: <2ae26e4e0812030750i1e8b0af4x4e99ccafcfcf7812@mail.gmail.com>	<4936D8D7.70204@xtra.co.nz>	<ECE7A93BD093E1439C20020FBE87C47FEB55DA84B2@ALTPHYEMBEVSP20.RES.AD.JPL>	<4936E5B0.2070201@xtra.co.nz>
	<2ae26e4e0812031548te0e935awcd007815ccc490a4@mail.gmail.com>
Message-ID: <49372FF1.5020608@xtra.co.nz>

pablo alvarez wrote:
> thanks for the positive feedback,
>
> In xilinx fpgas, for example, the recovery time after a metastability
> issue is quite fast as reported in this paper
>
> http://www.xilinx.com/support/documentation/application_notes/xapp094.pdf
>
> The capture window of metastable state is 0.01fm (page 2). Probably
> this window is moving around a bit, but this 0.01fm sounds promising.
>
> In page 3 "When granted 2 ns of extra settling delay, the problems
> caused by metastability are almost eliminated, as their MTBF exceeds
> millions of years."
>
> So we can just solve the glitch problem by adding a shift register as
> Bruce suggested.  I think the major concern may be crosstalk, but
> using lvds or ecl logic and placing the IOs far away one from each
> other may help to reduce it a bit.
>
>
> Now a DMTD architecture can be almost completely based on a FPGA where
> some LVDS  IOs would contain the D flip-flop mixers, with their clock
> input connected to the reference frequency and the D input to the
> clocks under test. The FPGA would contain a 32 bit free running
> counter clocked by the reference clock. Every time I detect a
> transition on my LVDS IOs the free running counter is latched and
> passed to a FIFO. Then the work can be passed to a data analysis
> program (of course through an LVDS serial link)  to do all sort of
> funny calculations.
>
> I wonder how good this system could eventually be if we reduce
> crosstalk to a minimum.
>
>
> Pablo
>
>
>
> On Wed, Dec 3, 2008 at 9:01 PM, Bruce Griffiths
> <bruce.griffiths at xtra.co.nz> wrote:
>   
>> Lux, James P wrote:
>>     
>>>>> Cheers
>>>>>
>>>>> Pablo
>>>>>
>>>>>
>>>>>
>>>>>           
>>>> Pablo
>>>>
>>>> Flipflop mixers tend to produce glitches at the beat
>>>> frequency transitions.
>>>> A digital PFD in a PLL doesnt produce a beat frequency output
>>>> when locked so such glitches arent a problem,
>>>>
>>>>
>>>>         
>>> I don't know that this is the case with modern PLL PFDs.. If only because glitches at the transitions would cause other problems, so there's an incentive to get rid of them.
>>>
>>>
>>> Jim
>>>
>>>
>>>       
>> Surely metastability may occur when the mixer flipflop D input
>> transitions occur close to its active clock transitions?
>>
>> There is at least one patent (US5053651) that claims to eliminate such
>> glitches in a digital mixer, however its output beat frequency is half
>> the difference between the input frequencies.
>>
>> Bruce
>>
>>     
Pablo

A DMTD system implemented largely in an FPGA should reduce cost
considerably and perhaps place such systems within the reach of more
time nuts.

One can also exploit process variations by using several such systems in
parallel to produce even more information in the vicinity of a
coincidence between active clock and D input transitions.
However crosstalk may be even more problematic in this case. despite
potential crosstalk problems arrays of arbiters driven in parallel have
successfully exploited statistical process variations to increase the
effective resolution.

Bruce


From grant at ghengineering.co.uk  Thu Dec  4 10:14:10 2008
From: grant at ghengineering.co.uk (Grant Hodgson)
Date: Thu, 04 Dec 2008 10:14:10 +0000
Subject: [time-nuts] DMTD mixer question
In-Reply-To: <mailman.1.1228332030.2499.time-nuts@febo.com>
References: <mailman.1.1228332030.2499.time-nuts@febo.com>
Message-ID: <4937AD72.2070905@ghengineering.co.uk>

Jim

Figures such as -200dBc/Hz probably relate to the phase noise figure of 
merit which some PLL suppliers like Nat. Semi, Hittite and AD use to 
compare various PLL offerings.  These figures are normalised to a 1Hz 
comparison frequency and unity division ratio; to get a prediction of 
PLL phase noise within the loop bandwidth you need to scale for both 
comparison frequency and division ratio.  This FOM is somewhat crude, as 
it doesn't take into account flicker noise, amongst other things, and 
loses accuracy with very high comparison frequencies.  Banerjee goes 
into more detail about this subject.

regards

Grant

--snip--

I seem to recall seeing a number like -190dBc/Hz or -200dBc/Hz for these 
hot stuff PFDs, but I can't recall where, maybe Banerjee's PLL book?

--snip--


From aceamusements at mchsi.com  Thu Dec  4 12:04:22 2008
From: aceamusements at mchsi.com (aceamusements at mchsi.com)
Date: Thu, 04 Dec 2008 12:04:22 +0000
Subject: [time-nuts] Cesium tube ion pumps
Message-ID: <120420081204.13478.4937C7460009B9F8000034A6219791299503010CD2079C080C03BF9C9B020A030A9C9A030E0A0C0E@mchsi.com>

That is my whole point,symmetricom will not come out and say it is defective
because it still is in within its operating parameters.

I checked with them on the warr before i bought this new old stock unit from a
surplus dealer.

at first they said I had no warranty because I did not buy it new but after
several calls they said they would go from the tube manuf date if I did not have
a receipt,

I then flew down to Florida to look at these units all still sealed in vac
pacs.new old stock from agilent,not symetricom.All sequential serial # manuf in
2005.I new all 8 of them were in storage 3 yrs and wanted to see the pump
currents in person upon power up for first time,The seller only wanted to unseal
two units to choose from so we set the two on a bench and plugged them in and I
immediately went to ion pump menu on both and was shocked they were both very
low upon initial power up.

I was surprised both started out below 5uA and both dropped to .2uA and .4ua
within seconds.even showing 0.2 after 5 minutes.

This must be due to them being brand new as I have seen several others,even a
gov liquidation unit that I flew to Texas to preview.This was a hp high
perf,manuf about 96 or 97.bad chassis.unknown tube.when I first powered it
up(this one has been in long term storage also) the ion pump overloaded and shut
down with a fatal error,so after 3 retries I got it to fall from 100uA down to
.2 and then 0.0 (but the unit was in standby due to the other problems)

this was a high perf tube from 1996 and the old style with only 5 years life (5
grams) the newer agilent tubes such as mine have more ceasum 8 grams instead of
five and say they last much longer..

I have looked at several other used 5071a also and all were after warm up and in
operate at about .2uA to .4uA..

One other change I have noticed in my tube since last year when it was brand
new.when I restart(power down overnight) the current starts out high up to 70-80
uA and falls in about two minutes to about 5.0 uA and then will dip down to
about 3.6 and back up to 5.0 even 5.6 yesterday.

when the tube was new it always stated out low 1.0 then dropped to .4 or .2,even
with the oven on, never over .4uA..


----------------------  Original Message:  ---------------------
From:    WB6BNQ <wb6bnq at cox.net>
To:      Discussion of precise time and frequency measurement <time-nuts at febo.com>
Subject: Re: [time-nuts] Cesium tube ion pumps
Date:    Thu, 4 Dec 2008 00:01:45 +0000

> David,
> 
> It would seem to me that while you have a warranty it would be prudent to 
> exercise
> such a warranty.  Otherwise, you will be fooling around till the last minute and 
> be
> out of luck.
> 
> If it sat "off" for three years and you have only had it operating for a short 
> while,
> unless I misunderstand something, it seems that there may have been a problem 
> with
> tube from the start ?  Out of curiousity, perhaps Corby can enlighten us on that
> aspect ?
> 
> Bill....WB6BNQ
> 
> 
> aceamusements at mchsi.com wrote:
> 
> > Corby,
> >
> > AT what point would be approp to call symmetricom and complain about defective
> > tube?I still have 2 years on the 5 yr warranty left, but how do u explain this
> > (defect),,(I assume it will just keep rising and eventually ruin the tube 
> within
> > a few yrs?)last I checked they wanted about 28k for a new tube.
> >
> > the unit with high perf tube has 5 yr warr from date of manuf. and cost 59k 
> new.
> >
> > ----------------------  Original Message:  ---------------------
> > From:    Corby Dawson <cdelect at juno.com>
> > To:      time-nuts at febo.com
> > Subject: [time-nuts] Cesium tube ion pumps
> > Date:    Wed, 3 Dec 2008 22:11:16 +0000
> >
> > > David,
> > >
> > > The long storage is not the cause. Extended operation of the ion pump
> > > causes the "whiskers" to grow. They can give rise to field emission
> > > leakage currents.
> > >
> > > This manifests as a raised ion pump current but does not inhibit proper
> > > operation unless the current gets too high.
> > >
> > > I don't remember at what current a 5071A will shut down at but I can take
> > > a look in the manual.
> > >
> > > Corby
> > > ____________________________________________________________
> > > Click here for free information on how to reduce your debt by filing for
> > > bankruptcy.
> > > 
> http://thirdpartyoffers.juno.com/TGL2141/fc/PnY6rw22U6KSiqbzGnzo8ijTIrFXhPWyQU8E
> > > VhPuk3kNAOgi96JqR/
> > > _______________________________________________
> > > time-nuts mailing list -- time-nuts at febo.com
> > > To unsubscribe, go to 
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> > > and follow the instructions there.
> >
> > _______________________________________________
> > time-nuts mailing list -- time-nuts at febo.com
> > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> > and follow the instructions there.
> 
> 
> _______________________________________________
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> and follow the instructions there.


From james.p.lux at jpl.nasa.gov  Thu Dec  4 13:28:54 2008
From: james.p.lux at jpl.nasa.gov (Lux, James P)
Date: Thu, 4 Dec 2008 05:28:54 -0800
Subject: [time-nuts] DMTD mixer question
In-Reply-To: <4937AD72.2070905@ghengineering.co.uk>
Message-ID: <C55D1B16.328C%James.P.Lux@jpl.nasa.gov>




On 12/4/08 2:14 AM, "Grant Hodgson" <grant at ghengineering.co.uk> wrote:

> Jim
>
> Figures such as -200dBc/Hz probably relate to the phase noise figure of
> merit which some PLL suppliers like Nat. Semi, Hittite and AD use to
> compare various PLL offerings.  These figures are normalised to a 1Hz
> comparison frequency and unity division ratio; to get a prediction of
> PLL phase noise within the loop bandwidth you need to scale for both
> comparison frequency and division ratio.  This FOM is somewhat crude, as
> it doesn't take into account flicker noise, amongst other things, and
> loses accuracy with very high comparison frequencies.  Banerjee goes
> into more detail about this subject.
>
> regards
>
> Grant
>

I found my copy of Banerjee and you're right.  The next thing I have to do
is track down Sal Kayalar at JPL and find out where he came up with the
other numbers I cited (from the IPN progress report by Cook in 2004.. The
footnote references an internal JPL memo, from my section, no less, but I
haven't found it yet) and see if they're directly comparable. (i.e. Has
technology really improved by 40dB in 15 years?)  I'm pretty sure they're
not directly comparable.



From robert8rpi at yahoo.co.uk  Thu Dec  4 19:54:19 2008
From: robert8rpi at yahoo.co.uk (Robert Atkinson)
Date: Thu, 4 Dec 2008 19:54:19 +0000 (GMT)
Subject: [time-nuts] Odetics 325/425 owners, rejoice!
In-Reply-To: <200812021931020879.158F931B@192.168.42.129>
Message-ID: <637951.31477.qm@web27103.mail.ukl.yahoo.com>

Hi Bruce,
That's great! I doubt I'll beat you to it but I'll have a look. I've 3 325's one with an OEM-5000
?
Robert G8RPI.

--- On Wed, 3/12/08, Bruce Lane <kyrrin at bluefeathertech.com> wrote:

From: Bruce Lane <kyrrin at bluefeathertech.com>
Subject: [time-nuts] Odetics 325/425 owners, rejoice!
To: time-nuts at febo.com
Date: Wednesday, 3 December, 2008, 3:31 AM

Fellow clock-tickers,

	Thanks to the generous assistance of a customer service rep at Magellan
Navigation, I have received a full .PDF manual covering the Magellan OEM5000
receiver module used in many of the Odetics SatSync 325 and 425 GPS clock units.

	This manual contains full details on both ASCII and Magellan Binary outputs
from the receiver, including that previously-elusive PMGLK sentence that was
driving me nuts.

	The information in that manual, combined with a bit of hardware ingenuity in
the microcontroller world and the Odetics equipment manual, should be enough to
produce a hardware translation device which will (hopefully) allow the use of a
standard (and much more readily available) NMEA-output receiver module.
That's going to be a long-term project for me in the coming year.

	Anyone who wants to try and beat me to it is, of course, welcome. ;-)

	The manual may be found on the Blue Feather FTP archive.

	ftp.bluefeathertech.com

	Sign in as user ftp and the password can be anything you want (though I prefer
an E-mail for logging purposes).

	The path is /electronics/radio/GPS/receivers/OEM/Magellan/oem5000

	The file name is OEM5K.pdf

	Happy reading.


-=-=-=-=-=-=-=-=-=-=-=-
Bruce Lane, Owner & Head Hardware Heavy,
Blue Feather Technologies -- http://www.bluefeathertech.com
kyrrin (at) bluefeathertech do/t c=o=m
"Quid Malmborg in Plano..."


_______________________________________________
time-nuts mailing list -- time-nuts at febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.



      

From warrensjmail-one at yahoo.com  Fri Dec  5 04:39:55 2008
From: warrensjmail-one at yahoo.com (WarrenS)
Date: Thu, 4 Dec 2008 20:39:55 -0800
Subject: [time-nuts] Sub Pico Second Phase logger
Message-ID: <01f801c95693$85b913d0$6401a8c0@WSOffice>


Building a Sub Pico Second phase detector.

I was inspired to build this project yesterday after downloading and trying   
Ulrich Bangert's 'DF6JB's Plotter 2008-10-10' program with its unbelievable 
 flexible user Interface capabilities.  http://www.ulrich-bangert.de/html/downloads.html
What I needed was a Phase detector to use with the 'Plotter' program.
I decided to see what it takes to build a simple high resolution, sub Pico second, 
linear phase logging detector using standard off the self IC's.
 
How If works:
The 5 or 10 MHz signal to be measured is buffered and toggles a 
synchronous divide by two or four FF. This gives a 2.5MHz square wave and its complement. 
Each side of the flip-flop connects to two of four XOR gates.

The 10 MHz reference signal goes thru a matching buffer and then to a pair of synchronous 
Flip-Flops that provide a zero and a 90 deg phase shifted 2.5MHz square wave.
Each of these goes to two inputs of the XOR gates. The four XOR phase detectors 
are connected to give four PWM type XOR phase detectors, each separate by 90 deg.

Each of the four XOR outputs are buffered by a cmos buffer gate 
that has been powered by it's own 5 volt reference supply.
The buffer outputs then goes thru a multi-stage passive RC filter set up to 
give two differential filtered PASSIVE + - 5 volt outputs, 90 deg apart.

Logging  Data:
For the most flexible and best  performance, two differential 16 plus bit ADC's 
should be used, each connected to one of the dual differential Phase detectors.
After using the appropriate Analog RC filters, oversampling, digital filters, and digital 
scaling, you get a file with a single column of data to feed "Plotter" the phase 
difference of the two 10 MHz signals. 

The Data scaling and processing:
For simple controlled short term or lower resolution data taking a PC Multimeter, 
if it is isolated so that you can use it differentially will work.  If not you need to add a differential amp. 
For best performance, process the phase data from the two differential phase detectors 
through two identical digital filter algorithms.
Doing this real time on a PC or after all the data is recorder on a XL spread sheet both work for me.
Besides the filtering, the spread sheet or PC needs to also do the linearizing by 
( K1* Phase1_Data) + (K2 * Phase2_Data).   
K1 and K2 are the sine value of their respective Phase detectors.

One of the several tricks to why this can provide orders of magnitude better 
performance than is generally obtained from similar type phase detectors 
is because of the four matched Phase detectors that are added, subtracted 
and combined and linerized in such a way as to cancel the type of errors 
found in single XOR phase detectors.

Preliminary Performance
The noise floor that I have seen while feeding the same low noise osc, to both inputs, 
is around 10 uv peak to peak at low Bandwidths, at zero phase,  using a 6 digit DVM 
with a slow filter which corresponds to <<1 ps. Test are still underway to see what the 
lower limit is, and what the sensitivity to the environment is.

This is just the start of an on going learning project, It is just at the breadboard stage and 
needs to be verified, critiqued, cleaned up and packaged up. 
Noted that when working with sub ps resolution, extra care needs to be taken.
Although it looks to be a standard digital circuit, It is not. It is a very sensitive Analog circuit 
capable of giving 1 part in a million type of resolution. It can resolve path distance changes 
in the 1/100 to 1/1000 of an inch, and needs to be built with care and 'respect'.   

Another use (beside watching just how noisy your "GOOD " osc is),
It can be used to compare and adjust the freq differences between two osc 
very quickly and with more resolution than most can use.
1 E-12 freq difference gave several counts per second change on 
the DVM, and with the DVM updating at several times a second, 
it made fine freq adjustments much easer than slower monitoring ways.


If you know of other simple high resolution phase detectors, 
or see any problems or improvements 
with the idea, I'd like to hear from you.

Have fun
WarrenS

From bruce.griffiths at xtra.co.nz  Fri Dec  5 05:09:53 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Fri, 05 Dec 2008 18:09:53 +1300
Subject: [time-nuts] Sub Pico Second Phase logger
In-Reply-To: <01f801c95693$85b913d0$6401a8c0@WSOffice>
References: <01f801c95693$85b913d0$6401a8c0@WSOffice>
Message-ID: <4938B7A1.1070701@xtra.co.nz>

WarrenS wrote:
> Building a Sub Pico Second phase detector.
>
> I was inspired to build this project yesterday after downloading and trying   
> Ulrich Bangert's 'DF6JB's Plotter 2008-10-10' program with its unbelievable 
>  flexible user Interface capabilities.  http://www.ulrich-bangert.de/html/downloads.html
> What I needed was a Phase detector to use with the 'Plotter' program.
> I decided to see what it takes to build a simple high resolution, sub Pico second, 
> linear phase logging detector using standard off the self IC's.
>  
> How If works:
> The 5 or 10 MHz signal to be measured is buffered and toggles a 
> synchronous divide by two or four FF. This gives a 2.5MHz square wave and its complement. 
> Each side of the flip-flop connects to two of four XOR gates.
>
> The 10 MHz reference signal goes thru a matching buffer and then to a pair of synchronous 
> Flip-Flops that provide a zero and a 90 deg phase shifted 2.5MHz square wave.
> Each of these goes to two inputs of the XOR gates. The four XOR phase detectors 
> are connected to give four PWM type XOR phase detectors, each separate by 90 deg.
>
> Each of the four XOR outputs are buffered by a cmos buffer gate 
> that has been powered by it's own 5 volt reference supply.
> The buffer outputs then goes thru a multi-stage passive RC filter set up to 
> give two differential filtered PASSIVE + - 5 volt outputs, 90 deg apart.
>
> Logging  Data:
> For the most flexible and best  performance, two differential 16 plus bit ADC's 
> should be used, each connected to one of the dual differential Phase detectors.
> After using the appropriate Analog RC filters, oversampling, digital filters, and digital 
> scaling, you get a file with a single column of data to feed "Plotter" the phase 
> difference of the two 10 MHz signals. 
>
> The Data scaling and processing:
> For simple controlled short term or lower resolution data taking a PC Multimeter, 
> if it is isolated so that you can use it differentially will work.  If not you need to add a differential amp. 
> For best performance, process the phase data from the two differential phase detectors 
> through two identical digital filter algorithms.
> Doing this real time on a PC or after all the data is recorder on a XL spread sheet both work for me.
> Besides the filtering, the spread sheet or PC needs to also do the linearizing by 
> ( K1* Phase1_Data) + (K2 * Phase2_Data).   
> K1 and K2 are the sine value of their respective Phase detectors.
>
> One of the several tricks to why this can provide orders of magnitude better 
> performance than is generally obtained from similar type phase detectors 
> is because of the four matched Phase detectors that are added, subtracted 
> and combined and linerized in such a way as to cancel the type of errors 
> found in single XOR phase detectors.
>
> Preliminary Performance
> The noise floor that I have seen while feeding the same low noise osc, to both inputs, 
> is around 10 uv peak to peak at low Bandwidths, at zero phase,  using a 6 digit DVM 
> with a slow filter which corresponds to <<1 ps. Test are still underway to see what the 
> lower limit is, and what the sensitivity to the environment is.
>
> This is just the start of an on going learning project, It is just at the breadboard stage and 
> needs to be verified, critiqued, cleaned up and packaged up. 
> Noted that when working with sub ps resolution, extra care needs to be taken.
> Although it looks to be a standard digital circuit, It is not. It is a very sensitive Analog circuit 
> capable of giving 1 part in a million type of resolution. It can resolve path distance changes 
> in the 1/100 to 1/1000 of an inch, and needs to be built with care and 'respect'.   
>
> Another use (beside watching just how noisy your "GOOD " osc is),
> It can be used to compare and adjust the freq differences between two osc 
> very quickly and with more resolution than most can use.
> 1 E-12 freq difference gave several counts per second change on 
> the DVM, and with the DVM updating at several times a second, 
> it made fine freq adjustments much easer than slower monitoring ways.
>
>
> If you know of other simple high resolution phase detectors, 
> or see any problems or improvements 
> with the idea, I'd like to hear from you.
>
> Have fun
> WarrenS
>   
Warren

Since HCMOS buffers typically have about 4ps of random propagation delay
jitter and ACMOS devices typically have about 1ps of RJ this isnt too
surprising.
Newer logic families may have even lower random jitter.

Doesn't this phase detector, like all digital phase detectors, have
significant non linearity at the ends of its range?
In the case of an XOR gate phase detector this is caused by the finite
slew rate of the gate output.

With the quadrature phased outputs at least 2 of the phase detectors
will be operating in the linear part of their range.
The particular pair that are linear depends on the relative phase of the
2 inputs.

One or more of the ubiquitous 24 bit resolution sigma delta ADCs with
differential inputs and a reference derived from the XOR power supply,
will for CMOS XOR gates probably be a relatively inexpensive replacement
for the DVM int he final system.

If one used an FPGA or CPLD for this as the internal crosstalk may limit
performance to a few tens of picosec noise for 1 sec averaging unless
differential I/O logic such as LDVS, ECL etc are used.
Although the circuit is simple enough not to warrant an FPGA it would be
useful to have programmable dividers for each input to allow comparison
of input frequencies that arent either nominally equal or have a
frequency ratio of 2:1. Using external retiming flipflops should cure
the crosstalk problem with such a divider.
In practice such a divider should perhaps be an external device with its
own power supply and enclosure.

Such a divider can be used to increase the effective range of the phase
detector at the expense of its resolution.

Bruce


From tvb at LeapSecond.com  Fri Dec  5 08:32:37 2008
From: tvb at LeapSecond.com (Tom Van Baak)
Date: Fri, 5 Dec 2008 00:32:37 -0800
Subject: [time-nuts] M12 100 Hz vs. 1PPS measurements
Message-ID: <F3D4DB1872C84B8AAD666A0DFBBB5BC0@pc52>

I know a number of you have been waiting for the results of
this M12 experiment. I compared the performance of a 100 Hz
output vs. a 1PPS output vs. a 1PPS with sawtooth correction.

http://www.leapsecond.com/pages/m12-adev/

I think it came out quite well and it may surprise some of you.

/tvb




From pvince at theiet.org  Fri Dec  5 09:06:05 2008
From: pvince at theiet.org (Peter Vince)
Date: Fri, 05 Dec 2008 09:06:05 +0000
Subject: [time-nuts] M12 100 Hz vs. 1PPS measurements
Message-ID: <49844.1228467965@uk2.net>

Tom,

Interesting results - thank you.  Is there a small problem with the graph plotting routine though?  On the left of the 100Hz 
plots, at some tau there are two points above each other (5 + 7 * 10^-2), and other tau have no data points (4, 6, + 8 * 10^-
2).

Peter


On Fri Dec  5  8:32 , 'Tom Van Baak' <tvb at LeapSecond.com> sent:

>I know a number of you have been waiting for the results of
>this M12 experiment. I compared the performance of a 100 Hz
>output vs. a 1PPS output vs. a 1PPS with sawtooth correction.
>
>http://www.leapsecond.com/pages/m12-adev/
>
>I think it came out quite well and it may surprise some of you.
>
>/tvb




From stijena at tapko.de  Fri Dec  5 10:47:38 2008
From: stijena at tapko.de (Predrag Dukic)
Date: Fri, 05 Dec 2008 11:47:38 +0100
Subject: [time-nuts] M12 100 Hz vs. 1PPS measurements
In-Reply-To: <F3D4DB1872C84B8AAD666A0DFBBB5BC0@pc52>
References: <F3D4DB1872C84B8AAD666A0DFBBB5BC0@pc52>
Message-ID: <7.0.1.0.1.20081205114638.01e72460@tapko.de>


Nice and useful....

What about Jupiter's 10 KHz output under same conditions?

Predrag Dukic






At 09:32 5.12.2008, you wrote:
>I know a number of you have been waiting for the results of
>this M12 experiment. I compared the performance of a 100 Hz
>output vs. a 1PPS output vs. a 1PPS with sawtooth correction.
>
>http://www.leapsecond.com/pages/m12-adev/
>
>I think it came out quite well and it may surprise some of you.
>
>/tvb
>
>
>
>_______________________________________________
>time-nuts mailing list -- time-nuts at febo.com
>To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>and follow the instructions there.



From warrensjmail-one at yahoo.com  Fri Dec  5 11:04:48 2008
From: warrensjmail-one at yahoo.com (WarrenS)
Date: Fri, 5 Dec 2008 03:04:48 -0800
Subject: [time-nuts] M12 100 Hz vs. 1PPS measurements
References: <F3D4DB1872C84B8AAD666A0DFBBB5BC0@pc52>
Message-ID: <02c801c956c9$4aa089a0$6401a8c0@WSOffice>

/tvb

Nice work, I was afraid you had dropped the subject.

There is a chance that the Allen noise ripple using the 100Hz can be reduced or eliminated 
if you have a processor in the system.
The short of it is that every once in a while the 100 Hz syncs up for a short time to the 1 Hz 
which itself has synced up to something else and is at the wrong value. The sawtooth correction 
knows that the 1 Hz is at the wrong value and reports it as such so this does not effect the 
anything if using the Sawtooth correction.

When this does happen the 100 Hz is at the wrong value also and becomes no better than 
using the one Hz signal during this short period, and so during this time it reverts back to the 
basic performance of the 1 Hz. You can see this sync effect happening on your 100 Hz 
phase data at the 9 seconds

This condition is very easy to detect and correct for, and if the processor did compensate for it, 
I have found that it helps a lot with fast loops, probable no big  deal with the slower loops. 

One other thing,  If someone where using a really crappy OSC with noise so bad that it that needed 
an update rate at was greater than 1 Hz, then the 100 Hz will give far better performance than either the 
1 sec or the corrected sawtooth.  Of course no one in there right mind would use that poor of an osc, 
that is unless they had some weird and different reason for doing it.

IT would be interesting to see how much improvement could be obtained in some GPSDO, if  the phase 
detectors errors where eliminated.


Have Fun, You sure do nice work and make nice plots.
WarrenS

*******************

----- Original Message ----- 
From: "Tom Van Baak" <tvb at LeapSecond.com>
To: "Discussion of precise time and frequency measurement" <time-nuts at febo.com>
Sent: Friday, December 05, 2008 12:32 AM
Subject: [time-nuts] M12 100 Hz vs. 1PPS measurements


>I know a number of you have been waiting for the results of
> this M12 experiment. I compared the performance of a 100 Hz
> output vs. a 1PPS output vs. a 1PPS with sawtooth correction.
> 
> http://www.leapsecond.com/pages/m12-adev/
> 
> I think it came out quite well and it may surprise some of you.
> 
> /tvb
> 
> 
> 
> 
>


From warrensjmail-one at yahoo.com  Fri Dec  5 11:09:29 2008
From: warrensjmail-one at yahoo.com (WarrenS)
Date: Fri, 5 Dec 2008 03:09:29 -0800
Subject: [time-nuts]  Sub Pico Second Phase logger
Message-ID: <02e501c956c9$f225f980$6401a8c0@WSOffice>

Bruce

asked)  
Doesn't this phase detector, like all digital phase detectors, have
significant non linearity at the ends of its range?
In the case of an XOR gate phase detector this is caused by the finite
slew rate of the gate output.

Thanks for all the ideas and Information. 
True, XORs don't work good at the end of their range for several reasions. 
This is why I had to put in the second pair of detectors.
K1 and K2 are used in the example as a sort of "smooth linear demulplexer" 
to switch between the phase detectors.  As one set of differential 
phase detectors gets near its nonlinear and troublesome range at their zero 
and 180 phase point their output change contribution is COMPLETELY shut down 
by the a "sin" like function product of K and Phase#. Not really a sin 
function and not really done as K's. The function of the sum of the two 
phase detectors will be dependent on the voltages themself. 
That is their modified voltage out will have less effect the farther away 
from zero their phase voltage is.  A  smooth clipper function. 
For a given detector pair the farther from zero it is the less its change 
will contrubute. When both the zero and 90 degree phase detectors 
are half way between zero and rail, their outputs gets summed together 
with a weighing factor of 1/2 each. 
One disadvantage of  the quad phase detectors,  is to work good and 
allow the digital processing functions I want to have, there has to be two 
seperate data paths, one from each Pair of phase detectors. 
The data rate is slow enough even with the desired oversampling 
that a multiplexed ADC my be OK.
Is there anything that cares about faster than about 10Hz high resolution
phase update times, that a simple analog XOR phase detector could handle? 

Also I do not think that the linearity has to be very good. I was thinking if 
it stays within say 90% it would be good enough for what I know of. The important 
thing is Just so it stays monotonic and glitch free with no hysteresis etc which 
it seems to do. It is not 1 million to one accurate as you know, maybe more like 
within 1% or 0.1%. The one I build only has a  million to one resolution 
around 90, 270 degs, zero and 180 deg. which is the only place I generally using it. 
At the moment the accuracy and noise performance with the detector away 
from its zero output value is limited by the accuracy of the reference along 
with a lot of other gain error things. 
Is there any use for a truly linear and accurate simple phase detector?  
I supose it could be done, in a similar mater, but may have to add a couple parts.

You also said HCMOS buffers have 4ps or so of jitter. Is this the kind of jitter noise 
that can be filtered down into the mud with the present 100ms analog Bandwidth 
and the 250K samples that are effectively being averaging?  
Do you have any knowledge or guess on ICs NON tracking delay change with Temp? 
I've tried to match all delays in the four loops, by always having a part from the same 
IC in each loop, so mostly, as long as all like parts in any single IC track well then their 
zero errors should cancel.
I have not tested it much below 1ps except to see what I think was more like 0.1 ps resolution.
The test I did for that was to move my hand near the center of one channel's shielded 
signal cable the watched the phase output smoothly change like a proximity detector 
as my hand approached the shielded cable, not due to cap to ground but due to the 
cable delay changing. Thoses electrons just don't get very far in 100fs
I am considering using a faster famly, but I do want to say away from anything that 
produces any heat. It looks like temperture offsets and changes are going to be the 
limiting factor for zero stability. 
I use the same dual detector design to phase lock now, but I never have checked or 
cared how good it can get. 

Thanks for the review and feedback, I've added several questions, please comment where you can? 
I'm planning to make another pass at it and clean it up for thermos etc. and see how low it will go. 

************
Concerning other uses of the single differential XOR phase detector.
If anyone wants to improve the performance of an existing crappy XOR phase detector
they may want to consider the differential XOR detector. Just be sure to include a good differential 
integrator (with a zero pole) at its output before driving the EFC so that the phase detector's 
output always stays at zero. The differential detector can reduce phase detector errors 
by many orders of magnitude. 

WarrenS

*************************
Bruce Griffiths bruce.griffiths at xtra.co.nz 
Fri Dec 5 05:09:53 UTC 2008 

  a.. Previous message: [time-nuts] Sub Pico Second Phase logger 
  b.. Messages sorted by: [ date ] [ thread ] [ subject ] [ author ] 

--------------------------------------------------------------------------------

WarrenS wrote:
> Building a Sub Pico Second phase detector.
>
> I was inspired to build this project yesterday after downloading and trying   
> Ulrich Bangert's 'DF6JB's Plotter 2008-10-10' program with its unbelievable 
>  flexible user Interface capabilities.  http://www.ulrich-bangert.de/html/downloads.html
> What I needed was a Phase detector to use with the 'Plotter' program.
> I decided to see what it takes to build a simple high resolution, sub Pico second, 
> linear phase logging detector using standard off the self IC's.
>  
> How If works:
> The 5 or 10 MHz signal to be measured is buffered and toggles a 
> synchronous divide by two or four FF. This gives a 2.5MHz square wave and its complement. 
> Each side of the flip-flop connects to two of four XOR gates.
>
> The 10 MHz reference signal goes thru a matching buffer and then to a pair of synchronous 
> Flip-Flops that provide a zero and a 90 deg phase shifted 2.5MHz square wave.
> Each of these goes to two inputs of the XOR gates. The four XOR phase detectors 
> are connected to give four PWM type XOR phase detectors, each separate by 90 deg.
>
> Each of the four XOR outputs are buffered by a cmos buffer gate 
> that has been powered by it's own 5 volt reference supply.
> The buffer outputs then goes thru a multi-stage passive RC filter set up to 
> give two differential filtered PASSIVE + - 5 volt outputs, 90 deg apart.
>
> Logging  Data:
> For the most flexible and best  performance, two differential 16 plus bit ADC's 
> should be used, each connected to one of the dual differential Phase detectors.
> After using the appropriate Analog RC filters, oversampling, digital filters, and digital 
> scaling, you get a file with a single column of data to feed "Plotter" the phase 
> difference of the two 10 MHz signals. 
>
> The Data scaling and processing:
> For simple controlled short term or lower resolution data taking a PC Multimeter, 
> if it is isolated so that you can use it differentially will work.  If not you need to add a differential amp. 
> For best performance, process the phase data from the two differential phase detectors 
> through two identical digital filter algorithms.
> Doing this real time on a PC or after all the data is recorder on a XL spread sheet both work for me.
> Besides the filtering, the spread sheet or PC needs to also do the linearizing by 
> ( K1* Phase1_Data) + (K2 * Phase2_Data).   
> K1 and K2 are the sine value of their respective Phase detectors.
>
> One of the several tricks to why this can provide orders of magnitude better 
> performance than is generally obtained from similar type phase detectors 
> is because of the four matched Phase detectors that are added, subtracted 
> and combined and linerized in such a way as to cancel the type of errors 
> found in single XOR phase detectors.
>
> Preliminary Performance
> The noise floor that I have seen while feeding the same low noise osc, to both inputs, 
> is around 10 uv peak to peak at low Bandwidths, at zero phase,  using a 6 digit DVM 
> with a slow filter which corresponds to <<1 ps. Test are still underway to see what the 
> lower limit is, and what the sensitivity to the environment is.
>
> This is just the start of an on going learning project, It is just at the breadboard stage and 
> needs to be verified, critiqued, cleaned up and packaged up. 
> Noted that when working with sub ps resolution, extra care needs to be taken.
> Although it looks to be a standard digital circuit, It is not. It is a very sensitive Analog circuit 
> capable of giving 1 part in a million type of resolution. It can resolve path distance changes 
> in the 1/100 to 1/1000 of an inch, and needs to be built with care and 'respect'.   
>
> Another use (beside watching just how noisy your "GOOD " osc is),
> It can be used to compare and adjust the freq differences between two osc 
> very quickly and with more resolution than most can use.
> 1 E-12 freq difference gave several counts per second change on 
> the DVM, and with the DVM updating at several times a second, 
> it made fine freq adjustments much easer than slower monitoring ways.
>
>
> If you know of other simple high resolution phase detectors, 
> or see any problems or improvements 
> with the idea, I'd like to hear from you.
>
> Have fun
> WarrenS
>   
Warren

Since HCMOS buffers typically have about 4ps of random propagation delay
jitter and ACMOS devices typically have about 1ps of RJ this isnt too
surprising.
Newer logic families may have even lower random jitter.

Doesn't this phase detector, like all digital phase detectors, have
significant non linearity at the ends of its range?
In the case of an XOR gate phase detector this is caused by the finite
slew rate of the gate output.

With the quadrature phased outputs at least 2 of the phase detectors
will be operating in the linear part of their range.
The particular pair that are linear depends on the relative phase of the
2 inputs.

One or more of the ubiquitous 24 bit resolution sigma delta ADCs with
differential inputs and a reference derived from the XOR power supply,
will for CMOS XOR gates probably be a relatively inexpensive replacement
for the DVM int he final system.

If one used an FPGA or CPLD for this as the internal crosstalk may limit
performance to a few tens of picosec noise for 1 sec averaging unless
differential I/O logic such as LDVS, ECL etc are used.
Although the circuit is simple enough not to warrant an FPGA it would be
useful to have programmable dividers for each input to allow comparison
of input frequencies that arent either nominally equal or have a
frequency ratio of 2:1. Using external retiming flipflops should cure
the crosstalk problem with such a divider.
In practice such a divider should perhaps be an external device with its
own power supply and enclosure.

Such a divider can be used to increase the effective range of the phase
detector at the expense of its resolution.

Bruce


From jgd at johngsbbq.com  Fri Dec  5 11:32:03 2008
From: jgd at johngsbbq.com (Neon John)
Date: Fri, 05 Dec 2008 06:32:03 -0500
Subject: [time-nuts] position determination over short distance
In-Reply-To: <C54F6D0D.2CED%James.P.Lux@jpl.nasa.gov>
References: <492A25D5.6080900@xtra.co.nz>
	<C54F6D0D.2CED%James.P.Lux@jpl.nasa.gov>
Message-ID: <nr3ij4hje87c3512ujrq9e8d0pkjaqj8l9@4ax.com>

On Sun, 23 Nov 2008 20:26:52 -0800, "Lux, James P" <james.p.lux at jpl.nasa.gov>
wrote:

>There's a fair amount of F/OSS software from JPL available to do this sort of calibration. It's used to calibrate cameras used on Mars rovers, among other things. The target pattern for calibration is a bunch of big circular dots on a background.

URLs?

I recently found this freeware open source on the net.  

http://tim-jackson.co.uk/area/index.html

Caution: I've encountered this guy on Usenet where he has a bad tendency to
substitute abject BS in place of fact when it's too much trouble to dig up the
facts.  I'd inspect the sources closely before using, looking for shortcuts
that don't work and pure old logic errors.

It would do the job in this instance but I'm interested in a more generalized
solution (without having to write it myself or buy anything) to pulling
measurements from photos.

I'd like to be able to take a photograph in which an object of known
dimensions is included and pull other dimensions from the photo, including
areas.

Any suggestions?

John
--
John De Armond
See my website for my current email address
http://www.neon-john.com
http://www.johndearmond.com <-- best little blog on the net!
Tellico Plains, Occupied TN
What do you call a blonde's cranial cavity?  Vacuum chamber?



From phk at phk.freebsd.dk  Fri Dec  5 11:38:29 2008
From: phk at phk.freebsd.dk (Poul-Henning Kamp)
Date: Fri, 05 Dec 2008 11:38:29 +0000
Subject: [time-nuts] M12 100 Hz vs. 1PPS measurements
In-Reply-To: Your message of "Fri, 05 Dec 2008 03:04:48 PST."
	<02c801c956c9$4aa089a0$6401a8c0@WSOffice> 
Message-ID: <20399.1228477109@critter.freebsd.dk>

In message <02c801c956c9$4aa089a0$6401a8c0 at WSOffice>, "WarrenS" writes:

>The short of it is that every once in a while the 100 Hz syncs up
>for a short time to the 1 Hz

As far as I have ever been able to tell, that is not how it
works.

The 100Hz and 1Hz are generated with the same hardware and same
behaviour relative to software.

Back when I got my first 100Hz capable Oncore, I measured the
100Hz output against 100Hz generated by the TVB PPSDIV driven by
my Cs using my HP5370B and GPIB to collect all samples.

The conclusion was that the 100Hz was kicked not once per second
but much more often.

If the 100Hz had been synched once per second, both FFT and
ADEV/MDEV would flag the 1Hz signal resulting from that, and
they didn't, and neither does Toms data.

I also found, as Tom did, that using the 100Hz was as good as doing
the saw-tooth correction, and without getting into a long-winded
treaties about the finer points of modulus arithmetic, this also
indicates that the 100Hz tickled more often than 1/s and quite
likely at every period.

I tried to determine if the 100Hz indeed was tickled every period,
I expected it to show up in a histogram of the 100Hz signals absolute
or relative periods, but there were too much noise to confirm that.

Maybe Tom can try to repeat that experiment ?

Simply measure a sequence of zero-deadtime period widths of the
100Hz and make a histogram of the absolute widths and relative
widths, (the difference in width between period N and N-1.)

If we can confirm that the 100Hz signal is updated every cycle,
then that explains why Toms and my measurement found the averaged
100Hz to be as good as the negative sawtooth: sqrt(100 - ) ~= 10

Poul-Henning

-- 
Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk at FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.


From jgd at johngsbbq.com  Fri Dec  5 11:48:46 2008
From: jgd at johngsbbq.com (Neon John)
Date: Fri, 05 Dec 2008 06:48:46 -0500
Subject: [time-nuts] 10 MHz over optical fiber?
In-Reply-To: <2BFB5AF2EF724F709CC612D2AF20876A@pc52>
References: <C54F6D0D.2CED%James.P.Lux@jpl.nasa.gov>	<492AB812.4050403@cembreros.jazztel.es><20081124152247.DCDB0E91529@mail.ebirds.it>
	<492B54EA.5070301@rubidium.dyndns.org>
	<2BFB5AF2EF724F709CC612D2AF20876A@pc52>
Message-ID: <5r4ij4pf433v8lh72r41lpuv4nf78deib3@4ax.com>

On Mon, 24 Nov 2008 17:33:25 -0800, "Tom Van Baak" <tvb at LeapSecond.com> wrote:

>> Yes. I know of several commecial systems. If you only need to do a short 
>> jump, then using fairly basic E/O-O/E equipment should work well 
>> enought. It all depends if you want/can to roll your own or need to buy 
>> a finished product (aka "buy this, and you will be fine!").
>
>Magnus, what's the typical noise floor, tempco or drift of cheap
>(i.e., non JPL-level) fiber distribution systems like this? Is it less
>than regular coax, or phase stabilized heliax? At 100 m lengths?

OK, tom, you got me with another one.  WTF is phase stabilized heliax?  Is
that a hunk of ordinary heliax that has been characterized or is it made
special in some way?

re: original problem

check out B&B Electronics

http://www.bandbelectronics.com/

sorry, I'm off-line right now and can't browse but they specialize in really
inexpensive implementations of stuff like this.

John
--
John De Armond
See my website for my current email address
http://www.neon-john.com
http://www.johndearmond.com <-- best little blog on the net!
Tellico Plains, Occupied TN
Save the whales, collect the whole set!



From pabloalvarezsanchez at gmail.com  Fri Dec  5 11:57:09 2008
From: pabloalvarezsanchez at gmail.com (pablo alvarez)
Date: Fri, 5 Dec 2008 12:57:09 +0100
Subject: [time-nuts] DMTD mixer question
In-Reply-To: <49372FF1.5020608@xtra.co.nz>
References: <2ae26e4e0812030750i1e8b0af4x4e99ccafcfcf7812@mail.gmail.com>
	<4936D8D7.70204@xtra.co.nz>
	<ECE7A93BD093E1439C20020FBE87C47FEB55DA84B2@ALTPHYEMBEVSP20.RES.AD.JPL>
	<4936E5B0.2070201@xtra.co.nz>
	<2ae26e4e0812031548te0e935awcd007815ccc490a4@mail.gmail.com>
	<49372FF1.5020608@xtra.co.nz>
Message-ID: <2ae26e4e0812050357l2bfc5ae0ubbeda1299004aee6@mail.gmail.com>

Hi,

Perhaps the most apropiate solution for the time-nuts world is to use
an standard development kit and add a custom mezzanine with the extra
required logic.

Unfortunately the one I have in my lab is based on a Virtex5 fpga
which is rather expensive, but one can find excelent solutions for
200$
For example:
http://www.xilinx.com/products/devkits/HW-SPAR3AN-SK-UNI-G.htm

The mezaninne card would contain SMA connectors,  an array of ECL
registers and the PLL that should generate the reference frequency.

In the FPGA we will just do the PLL control, counting and external
world interface (probably the simplest is to go for the good old
rs232).
In principle I will do all the code in VHDL so you will not have any
problem in porting it to any device.

Cheers

pablo


On Thu, Dec 4, 2008 at 2:18 AM, Bruce Griffiths
<bruce.griffiths at xtra.co.nz> wrote:
> pablo alvarez wrote:
>> thanks for the positive feedback,
>>
>> In xilinx fpgas, for example, the recovery time after a metastability
>> issue is quite fast as reported in this paper
>>
>> http://www.xilinx.com/support/documentation/application_notes/xapp094.pdf
>>
>> The capture window of metastable state is 0.01fm (page 2). Probably
>> this window is moving around a bit, but this 0.01fm sounds promising.
>>
>> In page 3 "When granted 2 ns of extra settling delay, the problems
>> caused by metastability are almost eliminated, as their MTBF exceeds
>> millions of years."
>>
>> So we can just solve the glitch problem by adding a shift register as
>> Bruce suggested.  I think the major concern may be crosstalk, but
>> using lvds or ecl logic and placing the IOs far away one from each
>> other may help to reduce it a bit.
>>
>>
>> Now a DMTD architecture can be almost completely based on a FPGA where
>> some LVDS  IOs would contain the D flip-flop mixers, with their clock
>> input connected to the reference frequency and the D input to the
>> clocks under test. The FPGA would contain a 32 bit free running
>> counter clocked by the reference clock. Every time I detect a
>> transition on my LVDS IOs the free running counter is latched and
>> passed to a FIFO. Then the work can be passed to a data analysis
>> program (of course through an LVDS serial link)  to do all sort of
>> funny calculations.
>>
>> I wonder how good this system could eventually be if we reduce
>> crosstalk to a minimum.
>>
>>
>> Pablo
>>
>>
>>
>> On Wed, Dec 3, 2008 at 9:01 PM, Bruce Griffiths
>> <bruce.griffiths at xtra.co.nz> wrote:
>>
>>> Lux, James P wrote:
>>>
>>>>>> Cheers
>>>>>>
>>>>>> Pablo
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>> Pablo
>>>>>
>>>>> Flipflop mixers tend to produce glitches at the beat
>>>>> frequency transitions.
>>>>> A digital PFD in a PLL doesnt produce a beat frequency output
>>>>> when locked so such glitches arent a problem,
>>>>>
>>>>>
>>>>>
>>>> I don't know that this is the case with modern PLL PFDs.. If only because glitches at the transitions would cause other problems, so there's an incentive to get rid of them.
>>>>
>>>>
>>>> Jim
>>>>
>>>>
>>>>
>>> Surely metastability may occur when the mixer flipflop D input
>>> transitions occur close to its active clock transitions?
>>>
>>> There is at least one patent (US5053651) that claims to eliminate such
>>> glitches in a digital mixer, however its output beat frequency is half
>>> the difference between the input frequencies.
>>>
>>> Bruce
>>>
>>>
> Pablo
>
> A DMTD system implemented largely in an FPGA should reduce cost
> considerably and perhaps place such systems within the reach of more
> time nuts.
>
> One can also exploit process variations by using several such systems in
> parallel to produce even more information in the vicinity of a
> coincidence between active clock and D input transitions.
> However crosstalk may be even more problematic in this case. despite
> potential crosstalk problems arrays of arbiters driven in parallel have
> successfully exploited statistical process variations to increase the
> effective resolution.
>
> Bruce
>
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>


From warrensjmail-one at yahoo.com  Fri Dec  5 12:00:57 2008
From: warrensjmail-one at yahoo.com (WarrenS)
Date: Fri, 5 Dec 2008 04:00:57 -0800
Subject: [time-nuts]  M12 100 Hz vs. 1PPS measurements
Message-ID: <033401c956d1$2278b760$6401a8c0@WSOffice>



 
In message <02c801c956c9$4aa089a0$6401a8c0 at WSOffice>, "WarrenS" writes:

>The short of it is that every once in a while the 100 Hz syncs up
>for a short time to the 1 Hz

As far as I have ever been able to tell, that is not how it
works.

The 100Hz and 1Hz are generated with the same hardware and same
behaviour relative to software.

Back when I got my first 100Hz capable Oncore, I measured the
100Hz output against 100Hz generated by the TVB PPSDIV driven by
my Cs using my HP5370B and GPIB to collect all samples.

The conclusion was that the 100Hz was kicked not once per second
but much more often.

If the 100Hz had been synched once per second, both FFT and
ADEV/MDEV would flag the 1Hz signal resulting from that, and
they didn't, and neither does Toms data.

I also found, as Tom did, that using the 100Hz was as good as doing
the saw-tooth correction, and without getting into a long-winded
treaties about the finer points of modulus arithmetic, this also
indicates that the 100Hz tickled more often than 1/s and quite
likely at every period.

I tried to determine if the 100Hz indeed was tickled every period,
I expected it to show up in a histogram of the 100Hz signals absolute
or relative periods, but there were too much noise to confirm that.

Maybe Tom can try to repeat that experiment ?

Simply measure a sequence of zero-deadtime period widths of the
100Hz and make a histogram of the absolute widths and relative
widths, (the difference in width between period N and N-1.)

If we can confirm that the 100Hz signal is updated every cycle,
then that explains why Toms and my measurement found the averaged
100Hz to be as good as the negative sawtooth: sqrt(100 - ) ~= 10

Poul-Henning

-- 
Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk at FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.

Poul
BTW 
>"The The short of it is that every once in a while the 100 Hz syncs up
>for a short time to the 1 Hz

BTW the 3 times a day or so sync up the above is referring to is the reason 
that every once in a while the 100 Hz is only as good as the 1 Hz signal 
for a short while. The 100 Hz is defiantly update or at least different on every cycle, 
and has about the same peak to peak noise, which is why if nothing but just 
average the 100 Hz before using it for the 1Hz update, things would get a better.
WarrenS

From wje at quackers.net  Fri Dec  5 09:26:06 2008
From: wje at quackers.net (wje)
Date: Fri, 05 Dec 2008 04:26:06 -0500
Subject: [time-nuts] 10 MHz over optical fiber?
In-Reply-To: <5r4ij4pf433v8lh72r41lpuv4nf78deib3@4ax.com>
References: <C54F6D0D.2CED%James.P.Lux@jpl.nasa.gov>	<492AB812.4050403@cembreros.jazztel.es><20081124152247.DCDB0E91529@mail.ebirds.it>	<492B54EA.5070301@rubidium.dyndns.org>	<2BFB5AF2EF724F709CC612D2AF20876A@pc52>
	<5r4ij4pf433v8lh72r41lpuv4nf78deib3@4ax.com>
Message-ID: <4938F3AE.2070308@quackers.net>


   It's actually [1]http://www.bb-elec.com for those looking.
Bill Ezell
----------
They said 'Windows or better'
so I used Linux.

   Neon John wrote:

On Mon, 24 Nov 2008 17:33:25 -0800, "Tom Van Baak" [2]<tvb at LeapSecond.com> wrot
e:



Yes. I know of several commecial systems. If you only need to do a short
jump, then using fairly basic E/O-O/E equipment should work well
enought. It all depends if you want/can to roll your own or need to buy
a finished product (aka "buy this, and you will be fine!").


Magnus, what's the typical noise floor, tempco or drift of cheap
(i.e., non JPL-level) fiber distribution systems like this? Is it less
than regular coax, or phase stabilized heliax? At 100 m lengths?


OK, tom, you got me with another one.  WTF is phase stabilized heliax?  Is
that a hunk of ordinary heliax that has been characterized or is it made
special in some way?

re: original problem

check out B&B Electronics

[3]http://www.bandbelectronics.com/

sorry, I'm off-line right now and can't browse but they specialize in really
inexpensive implementations of stuff like this.

John
--
John De Armond
See my website for my current email address
[4]http://www.neon-john.com
[5]http://www.johndearmond.com <-- best little blog on the net!
Tellico Plains, Occupied TN
Save the whales, collect the whole set!


_______________________________________________
time-nuts mailing list -- [6]time-nuts at febo.com
To unsubscribe, go to [7]https://www.febo.com/cgi-bin/mailman/listinfo/time-nut
s
and follow the instructions there.

References

   1. http://www.bb-elec.com/
   2. mailto:tvb at LeapSecond.com
   3. http://www.bandbelectronics.com/
   4. http://www.neon-john.com/
   5. http://www.johndearmond.com/
   6. mailto:time-nuts at febo.com
   7. https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts

From wje at quackers.net  Fri Dec  5 09:35:57 2008
From: wje at quackers.net (wje)
Date: Fri, 05 Dec 2008 04:35:57 -0500
Subject: [time-nuts] 10 MHz over optical fiber?
In-Reply-To: <5r4ij4pf433v8lh72r41lpuv4nf78deib3@4ax.com>
References: <C54F6D0D.2CED%James.P.Lux@jpl.nasa.gov>	<492AB812.4050403@cembreros.jazztel.es><20081124152247.DCDB0E91529@mail.ebirds.it>	<492B54EA.5070301@rubidium.dyndns.org>	<2BFB5AF2EF724F709CC612D2AF20876A@pc52>
	<5r4ij4pf433v8lh72r41lpuv4nf78deib3@4ax.com>
Message-ID: <4938F5FD.1050703@quackers.net>


   It's regular Heliax that's been temperature-conditioned by repeated
   temp cycling to minimize dielectric size change vs temperature. This
   minimizes phase shift over length. The cycling affects the foam used
   as the dielectric, which apparently eventually stops expanding and
   contracting as much as non-conditioned cables.
Bill Ezell
----------
They said 'Windows or better'
so I used Linux.

   Neon John wrote:

On Mon, 24 Nov 2008 17:33:25 -0800, "Tom Van Baak" [1]<tvb at LeapSecond.com> wrot
e:



Yes. I know of several commecial systems. If you only need to do a short
jump, then using fairly basic E/O-O/E equipment should work well
enought. It all depends if you want/can to roll your own or need to buy
a finished product (aka "buy this, and you will be fine!").


Magnus, what's the typical noise floor, tempco or drift of cheap
(i.e., non JPL-level) fiber distribution systems like this? Is it less
than regular coax, or phase stabilized heliax? At 100 m lengths?


OK, tom, you got me with another one.  WTF is phase stabilized heliax?  Is
that a hunk of ordinary heliax that has been characterized or is it made
special in some way?

re: original problem

check out B&B Electronics

[2]http://www.bandbelectronics.com/

sorry, I'm off-line right now and can't browse but they specialize in really
inexpensive implementations of stuff like this.

John
--
John De Armond
See my website for my current email address
[3]http://www.neon-john.com
[4]http://www.johndearmond.com <-- best little blog on the net!
Tellico Plains, Occupied TN
Save the whales, collect the whole set!


_______________________________________________
time-nuts mailing list -- [5]time-nuts at febo.com
To unsubscribe, go to [6]https://www.febo.com/cgi-bin/mailman/listinfo/time-nut
s
and follow the instructions there.

References

   1. mailto:tvb at LeapSecond.com
   2. http://www.bandbelectronics.com/
   3. http://www.neon-john.com/
   4. http://www.johndearmond.com/
   5. mailto:time-nuts at febo.com
   6. https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts

From phk at phk.freebsd.dk  Fri Dec  5 12:16:15 2008
From: phk at phk.freebsd.dk (Poul-Henning Kamp)
Date: Fri, 05 Dec 2008 12:16:15 +0000
Subject: [time-nuts] M12 100 Hz vs. 1PPS measurements
In-Reply-To: Your message of "Fri, 05 Dec 2008 04:00:57 PST."
	<033401c956d1$2278b760$6401a8c0@WSOffice> 
Message-ID: <20592.1228479375@critter.freebsd.dk>

In message <033401c956d1$2278b760$6401a8c0 at WSOffice>, "WarrenS" writes:

>>>The short of it is that every once in a while the 100 Hz syncs up
>>>for a short time to the 1 Hz
>>
>>As far as I have ever been able to tell, that is not how it
>>works.

>The 100 Hz is defiantly update or at least different on every cycle, 
>and has about the same peak to peak noise, which is why if nothing but just 
>average the 100 Hz before using it for the 1Hz update, things would get a
>better.

We are talking about different things here, you are talking about
collapsing the chosen (software) frequency (estimate) to phase
samples using the hardware, I'm talking about updates to the
(software) frequency (estimate).

Poul-Henning

-- 
Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk at FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.


From phk at phk.freebsd.dk  Fri Dec  5 12:18:34 2008
From: phk at phk.freebsd.dk (Poul-Henning Kamp)
Date: Fri, 05 Dec 2008 12:18:34 +0000
Subject: [time-nuts] M12 100 Hz vs. 1PPS measurements
In-Reply-To: Your message of "Fri, 05 Dec 2008 12:16:15 GMT."
	<20592.1228479375@critter.freebsd.dk> 
Message-ID: <20607.1228479514@critter.freebsd.dk>

In message <20592.1228479375 at critter.freebsd.dk>, "Poul-Henning Kamp" writes:

>We are talking about different things here, you are talking about
>collapsing the chosen (software) frequency (estimate) to phase
>samples using the hardware, I'm talking about updates to the
>(software) frequency (estimate).

Forgot to say: if you look right after 10.0 seconds in Toms 100Hz
strip-chart plot, you can see the kind of sample that indicates
a frequency adjustment.

-- 
Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk at FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.


From j.bastemeijer at tudelft.nl  Fri Dec  5 12:51:57 2008
From: j.bastemeijer at tudelft.nl (Jeroen Bastemeijer)
Date: Fri, 05 Dec 2008 13:51:57 +0100
Subject: [time-nuts] HP 1600A logic analyzer manual
Message-ID: <493923ED.7090006@tudelft.nl>

Dear All,

A couple of weeks ago I send a request to the list for a HP 1600A logic 
analyzer manual. Hans Agema was kind enough to send his manual to me for 
scanning. I made a scan of the manual, which is now available to the 
whole group through Didiers website (www.ko4bb.com). Check the manuals 
section!

Thanks to Hans and Didier!

Best regards, Jeroen
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From bruce.griffiths at xtra.co.nz  Fri Dec  5 13:39:49 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Sat, 06 Dec 2008 02:39:49 +1300
Subject: [time-nuts] Sub Pico Second Phase logger
In-Reply-To: <02e501c956c9$f225f980$6401a8c0@WSOffice>
References: <02e501c956c9$f225f980$6401a8c0@WSOffice>
Message-ID: <49392F25.2070404@xtra.co.nz>

Warren
> Bruce
>
> asked)  
> Doesn't this phase detector, like all digital phase detectors, have
> significant non linearity at the ends of its range?
> In the case of an XOR gate phase detector this is caused by the finite
> slew rate of the gate output.
>
> Thanks for all the ideas and Information. 
> True, XORs don't work good at the end of their range for several reasions. 
> This is why I had to put in the second pair of detectors.
> K1 and K2 are used in the example as a sort of "smooth linear demulplexer" 
> to switch between the phase detectors.  As one set of differential 
> phase detectors gets near its nonlinear and troublesome range at their zero 
> and 180 phase point their output change contribution is COMPLETELY shut down 
> by the a "sin" like function product of K and Phase#. Not really a sin 
> function and not really done as K's. The function of the sum of the two 
> phase detectors will be dependent on the voltages themself. 
> That is their modified voltage out will have less effect the farther away 
> from zero their phase voltage is.  A  smooth clipper function. 
> For a given detector pair the farther from zero it is the less its change 
> will contrubute. When both the zero and 90 degree phase detectors 
> are half way between zero and rail, their outputs gets summed together 
> with a weighing factor of 1/2 each. 
> One disadvantage of  the quad phase detectors,  is to work good and 
> allow the digital processing functions I want to have, there has to be two 
> seperate data paths, one from each Pair of phase detectors. 
> The data rate is slow enough even with the desired oversampling 
> that a multiplexed ADC my be OK.
>   
Multiplexing a sigma delta ADC inputs only works well if the ADC design
is appropriate.
Linear technology have some especially designed for use with multiplexed
inputs.
Sigma delta ADCs are relatively inexpensive so one could always use a
couple of them.
Surely the outputs of both phase detectors are required to sort out the
the sign/direction of phase changes?
One could always log both outputs and sort out the sign of any changes
together with the appropriate output to use for determining the
magnitude in software.
> Is there anything that cares about faster than about 10Hz high resolution
> phase update times, that a simple analog XOR phase detector could handle? 
>
> Also I do not think that the linearity has to be very good. I was thinking if 
> it stays within say 90% it would be good enough for what I know of. The important 
> thing is Just so it stays monotonic and glitch free with no hysteresis etc which 
> it seems to do. It is not 1 million to one accurate as you know, maybe more like 
> within 1% or 0.1%. The one I build only has a  million to one resolution 
> around 90, 270 degs, zero and 180 deg. which is the only place I generally using it. 
> At the moment the accuracy and noise performance with the detector away 
> from its zero output value is limited by the accuracy of the reference along 
> with a lot of other gain error things. 
> Is there any use for a truly linear and accurate simple phase detector?  
> I supose it could be done, in a similar mater, but may have to add a couple parts.
>
>   
Only when one uses such a phase detector to measure the frequency offset
between the 2 sources being compared as quickly and accurately as possible.
The principal source of non linearity near the ends of the range is due
to insufficient time available for the transitions to settle accurately
with short pulse widths.
If the value of the first resistor in the RC passive filter is too low
the output resistance mismatch between the 0 and 1 states will
contribute significantly to the nonlinearity.
Modulation of the output resistance of the gate/buffer driving the RC
filter can also be significant.
Both of these effects can easily be reduced to insignificance by using
appropriate feedback circuitry.
> You also said HCMOS buffers have 4ps or so of jitter. Is this the kind of jitter noise 
> that can be filtered down into the mud with the present 100ms analog Bandwidth 
> and the 250K samples that are effectively being averaging?  
> Do you have any knowledge or guess on ICs NON tracking delay change with Temp? 
>   
Random jitter will indeed average down to the femtosecond level with
that many samples.
A crude way of estimating the propagation delay mismatch tempco for CMOS
ICs is to assume that the propagation delay mismatch has the same tempco
as the propagation delay itself or about +0.4%/C.
e.g. if the propagation delay is say 10ns and the mismatch is 10% (1ns)
then the delay mismatch tempco will be in the region of 4ps/C.

> I've tried to match all delays in the four loops, by always having a part from the same 
> IC in each loop, so mostly, as long as all like parts in any single IC track well then their 
> zero errors should cancel.
> I have not tested it much below 1ps except to see what I think was more like 0.1 ps resolution.
> The test I did for that was to move my hand near the center of one channel's shielded 
> signal cable the watched the phase output smoothly change like a proximity detector 
> as my hand approached the shielded cable, not due to cap to ground but due to the 
> cable delay changing. Thoses electrons just don't get very far in 100fs
> I am considering using a faster famly, but I do want to say away from anything that 
> produces any heat. It looks like temperture offsets and changes are going to be the 
> limiting factor for zero stability. 
>   
If the power dissipation is low it would be feasible to use a
bootstrapped oven (similar in thermal design to some of the standard
cell oven designs from the 50's and 60's) like Wenzel has used to
achieve sup-picosecond stability in a frequency multiplier.
> I use the same dual detector design to phase lock now, but I never have checked or 
> cared how good it can get. 
>
> Thanks for the review and feedback, I've added several questions, please comment where you can? 
> I'm planning to make another pass at it and clean it up for thermos etc. and see how low it will go. 
>
> ************
> Concerning other uses of the single differential XOR phase detector.
> If anyone wants to improve the performance of an existing crappy XOR phase detector
> they may want to consider the differential XOR detector. Just be sure to include a good differential 
> integrator (with a zero pole) at its output before driving the EFC so that the phase detector's 
> output always stays at zero. The differential detector can reduce phase detector errors 
> by many orders of magnitude. 
>
> WarrenS
>
>   

Bruce


From bruce.griffiths at xtra.co.nz  Fri Dec  5 13:54:48 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Sat, 06 Dec 2008 02:54:48 +1300
Subject: [time-nuts] DMTD mixer question
In-Reply-To: <2ae26e4e0812050357l2bfc5ae0ubbeda1299004aee6@mail.gmail.com>
References: <2ae26e4e0812030750i1e8b0af4x4e99ccafcfcf7812@mail.gmail.com>	<4936D8D7.70204@xtra.co.nz>	<ECE7A93BD093E1439C20020FBE87C47FEB55DA84B2@ALTPHYEMBEVSP20.RES.AD.JPL>	<4936E5B0.2070201@xtra.co.nz>	<2ae26e4e0812031548te0e935awcd007815ccc490a4@mail.gmail.com>	<49372FF1.5020608@xtra.co.nz>
	<2ae26e4e0812050357l2bfc5ae0ubbeda1299004aee6@mail.gmail.com>
Message-ID: <493932A8.5030001@xtra.co.nz>

pablo alvarez wrote:
> Hi,
>
> Perhaps the most apropiate solution for the time-nuts world is to use
> an standard development kit and add a custom mezzanine with the extra
> required logic.
>
> Unfortunately the one I have in my lab is based on a Virtex5 fpga
> which is rather expensive, but one can find excelent solutions for
> 200$
> For example:
> http://www.xilinx.com/products/devkits/HW-SPAR3AN-SK-UNI-G.htm
>
> The mezaninne card would contain SMA connectors,  an array of ECL
> registers and the PLL that should generate the reference frequency.
>
> In the FPGA we will just do the PLL control, counting and external
> world interface (probably the simplest is to go for the good old
> rs232).
> In principle I will do all the code in VHDL so you will not have any
> problem in porting it to any device.
>
> Cheers
>
> pablo
>
>   
Pablo

At least a couple of us have the Spartan 3E board.
Digilent also have some inexpensive boards that should suffice.

Bruce



From iovane at inwind.it  Fri Dec  5 14:13:10 2008
From: iovane at inwind.it (iovane at inwind.it)
Date: Fri,  5 Dec 2008 15:13:10 +0100
Subject: [time-nuts] position determination over short distance
Message-ID: <KBEQ5Y$3F8B9F92F57DD4B36BE53C67B25CBBAD@libero.it>

Rick Harold wrote:
> All,
>
> I'm planning doing some experiments in distance measurement.  They don't
> deal with atomic time directly but with extreme short periods of time.
>
> I need to determine the position of a instrument with a 1mm accuracy or
> less.
> The instrument is not connected to a mechanical device but is separate &
> independent.
> The surface which the instrument is positioned on is close to the size of a
> 11"x11" square.
>
> I thought of using 1 RF transmitters (not sure of freq) on bottom of the
> device near the surface.
> The surface would have RF receivers on 3 or 4 edges/corners to receive the
> signal.
>
> If each of the receivers positions are known and they then send a signal to
> a central circuit (again known positions) how can I differentiate the time
> of arrival
> at the central location?  Does anybody know of a circuit/chip or system
> which would determine the time 'difference'.
> Obviously this is used to triangulate the position of the instrument.
> Light travels 1 mm in ~3.3 picoseconds so I would suspect the differentiator
> would have to have that or better resolution.
> It could also use some proportional method to extrapolate the position since
> the surface has a fixed size.
>
> Any ideas/thoughts?
>
> Thanks in advance.
>
> Rick Harold
>   

Just yesterday, reading an article on an Italian magazine, I 
got in the know of an interesting device which could be 
suitable to the purpose. It is a micro "camera", 1024 x 768 
pixels, whose output is not a video signal, but numeric values
for X and Y, representing the position of a "hot dot". In the 
original design, the hot dot is a IR LED, a couple of meters 
away. This camera has a two wire output, CLOCK and DATA. It 
outputs continuously X,Y,CRLF,X,Y,CRLF and so on. As I 
understood, if there is more than one hot point, say two, the 
output would be something like X,Y,X,Y,CRLF....
I guess that, if the hot dot takes more than one pixel, one 
will get a stream of XY values before a CRLF.
Unluckily, this device is not available as a part, being a 
component of a Nintendo video game, precisely it is part of 
the Nintendo Wii remote control (remote control is found on 
ebay around 25$). 
The magazine is the italian edition of "Elektor" (12/2008 
issue) which is published in several languages 
(www.elektor.com). I think the article always appeared in 
English on back issues abroad.
Also see the interesting

http://en.wikipedia.org/wiki/Wii_Remote

Hope this could be of interest.

Antonio I8IOV





From james.p.lux at jpl.nasa.gov  Fri Dec  5 14:43:29 2008
From: james.p.lux at jpl.nasa.gov (Lux, James P)
Date: Fri, 5 Dec 2008 06:43:29 -0800
Subject: [time-nuts] position determination over short distance
In-Reply-To: <nr3ij4hje87c3512ujrq9e8d0pkjaqj8l9@4ax.com>
Message-ID: <C55E7E11.334A%James.P.Lux@jpl.nasa.gov>




On 12/5/08 3:32 AM, "Neon John" <jgd at johngsbbq.com> wrote:

> On Sun, 23 Nov 2008 20:26:52 -0800, "Lux, James P" <james.p.lux at jpl.nasa.gov>
> wrote:
>
>> There's a fair amount of F/OSS software from JPL available to do this sort of
>> calibration. It's used to calibrate cameras used on Mars rovers, among other
>> things. The target pattern for calibration is a bunch of big circular dots on
>> a background.
>
> URLs?
>
Google "JPL Camera Calibration" and you'll get a bunch of hits to various
technical reports. Once you have those, you'll have better search terms. A
lot of the software has been published in NasaTechBriefs as a TSP, too.

In general, you get an image of an array of big polka dots. The software
locates the centroids of the dots (which can be done with higher precision
than just looking for a single pixel point.. 0.1 pixel is apparently not too
tough, from what the camera guys tell me) (for instance, if you're doing
something like a star tracker, it's actually easier if the image is
defocused)
Then the measurements are turned into CAHVOR coefficients, which get used in
subsequent photogrammetric processing to rectify the image.


> I recently found this freeware open source on the net.
>
> http://tim-jackson.co.uk/area/index.html
>
> Caution: I've encountered this guy on Usenet where he has a bad tendency to
> substitute abject BS in place of fact when it's too much trouble to dig up the
> facts.  I'd inspect the sources closely before using, looking for shortcuts
> that don't work and pure old logic errors.
>
> It would do the job in this instance but I'm interested in a more generalized
> solution (without having to write it myself or buy anything) to pulling
> measurements from photos.
>
> I'd like to be able to take a photograph in which an object of known
> dimensions is included and pull other dimensions from the photo, including
> areas.
The JPL stuff would be more likely to be a library of dozens of routines
which you could string together to do this, rather than a handy point and
click interface.




>
> Any suggestions?
>
> John
> --
> John De Armond
> See my website for my current email address
> http://www.neon-john.com
> http://www.johndearmond.com <-- best little blog on the net!
> Tellico Plains, Occupied TN
> What do you call a blonde's cranial cavity?  Vacuum chamber?
>
>
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>



From james.p.lux at jpl.nasa.gov  Fri Dec  5 14:48:59 2008
From: james.p.lux at jpl.nasa.gov (Lux, James P)
Date: Fri, 5 Dec 2008 06:48:59 -0800
Subject: [time-nuts] 10 MHz over optical fiber?
In-Reply-To: <5r4ij4pf433v8lh72r41lpuv4nf78deib3@4ax.com>
Message-ID: <C55E7F5B.334E%James.P.Lux@jpl.nasa.gov>




On 12/5/08 3:48 AM, "Neon John" <jgd at johngsbbq.com> wrote:

> On Mon, 24 Nov 2008 17:33:25 -0800, "Tom Van Baak" <tvb at LeapSecond.com> wrote:
>
>>> Yes. I know of several commecial systems. If you only need to do a short
>>> jump, then using fairly basic E/O-O/E equipment should work well
>>> enought. It all depends if you want/can to roll your own or need to buy
>>> a finished product (aka "buy this, and you will be fine!").
>>
>> Magnus, what's the typical noise floor, tempco or drift of cheap
>> (i.e., non JPL-level) fiber distribution systems like this? Is it less
>> than regular coax, or phase stabilized heliax? At 100 m lengths?
>
> OK, tom, you got me with another one.  WTF is phase stabilized heliax?  Is
> that a hunk of ordinary heliax that has been characterized or is it made
> special in some way?


I don't know about heliax, but in the semirigid and flex coax area, getting
good phase stability is a combination of the two.  Some dielectrics and
construction have distinct bumps in the phase/temperature curve at
inconvenient temperatures (I'm looking at you Gore!) although they're
generally pretty good.  Some might have more variation over temperature, but
it's smooth and consistent.  Esp if you're measuring temperature or have it
controlled, the latter might be a better choice.

Then, you temperature cycle it a bunch of times with it formed in the final
shape, which relaxes the residual mechanical stresses.

Then, you try them all, and pick the best ones.



Jim



From brad at shinji.net  Fri Dec  5 15:10:57 2008
From: brad at shinji.net (Brad Stockdale)
Date: Fri, 05 Dec 2008 10:10:57 -0500
Subject: [time-nuts] Odetics 325/425 owners, rejoice!
In-Reply-To: <200812021931020879.158F931B@192.168.42.129>
References: <200812021931020879.158F931B@192.168.42.129>
Message-ID: <mailman.0.1228489866.2496.time-nuts@febo.com>

Bruce,

    I just wanted to thank you for the interesting information. I 
grabbed a few other electronics related files that I saw on your FTP 
site. Much appreciated!

Regards,
Brad


At 10:31 PM 12/2/2008, you wrote:
>Fellow clock-tickers,
>
>
>         The manual may be found on the Blue Feather FTP archive.
>
>         ftp.bluefeathertech.com
>
>         Sign in as user ftp and the password can be anything you 
> want (though I prefer an E-mail for logging purposes).



From jam at magic.com  Fri Dec  5 15:19:15 2008
From: jam at magic.com (James A. Markevitch)
Date: Fri, 5 Dec 2008 07:19:15 -0800 (PST)
Subject: [time-nuts] Thunderbolt time-nuts/TAPR Group Buy - status
Message-ID: <200812051519.HAA15330@magellan.magic.com>

Tom,

I've sent you a couple of messages off-list.  I suspect they are caught
in your spam filters somewhere.  I am interested in the next group
buy of TBolts.

> I think we'll do one more group buy next month and then I'm
> done with this project. At that time I'll also announce the plans
> for all the TBolts that dropped out of the testing process over
> the past year.

Thanks,

James Markevitch


From XDE-L2G3 at myamail.com  Fri Dec  5 15:55:51 2008
From: XDE-L2G3 at myamail.com (Mike Monett)
Date: Fri, 05 Dec 2008 10:55:51 -0500
Subject: [time-nuts] Thunderbolt time-nuts/TAPR Group Buy - status
Message-ID: <mailman.1.1228492578.2496.time-nuts@febo.com>

  > Hi all,

  > Last month's lot of 100 Thunderbolts sold out in a day or two.

  > The status  is that more than half have been shipped  so  far; the
  > rest within a few weeks. Thank you all for your patience.

  > That was  the 4th large batch of Thunderbolts that I  was  able to
  > obtain, test,  and  send to TAPR to distribute as kits.  I  know a
  > number of  you wanted one but missed out on each  of  the previous
  > group buys.

  > Please let  me know, off-list, if you are one  of  those time-nuts
  > who have been passed over. I'm at tvb at LeapSecond.com.

  > I think  we'll do one more group buy next month and then  I'm done
  > with this  project. At that time I'll also announce the  plans for
  > all the  TBolts that dropped out of the testing  process  over the
  > past year.

  > If you have questions or suggestions please contact me off-list.

  > Thanks,
  > /tvb
  > http://www.leapsecond.com/time-nuts.htm

  Hi Tom,

  I also sent you an email off-list, requesting two TBolts, but I have
  not received a reply. I'd like to prepay so I don't lose out  due to
  transfer of funds from Canada like the last time.

  Please let me know if this is possible.

  Thanks,

  Best Regards,

  Mike Monett


From tvb at LeapSecond.com  Fri Dec  5 17:31:50 2008
From: tvb at LeapSecond.com (Tom Van Baak)
Date: Fri, 5 Dec 2008 09:31:50 -0800
Subject: [time-nuts] Thunderbolt time-nuts/TAPR Group Buy - status
References: <E1L8d2Q-0008CG-De@meow.febo.com>
Message-ID: <028FF033DD9047E0A2A88CCA6AF7709A@pc52>

>  Hi Tom,
> 
>  I also sent you an email off-list, requesting two TBolts, but I have
>  not received a reply. I'd like to prepay so I don't lose out  due to
>  transfer of funds from Canada like the last time.
> 
>  Please let me know if this is possible.
> 
>  Thanks,
> 
>  Best Regards,
> 
>  Mike Monett

Consider this a reply to you and all the others who contacted
me off-line. I'm keeping the names on file and will give you
first notice when the next batch is ready.

/tvb



From warrensjmail-one at yahoo.com  Fri Dec  5 17:49:01 2008
From: warrensjmail-one at yahoo.com (WarrenS)
Date: Fri, 5 Dec 2008 09:49:01 -0800
Subject: [time-nuts]  position determination over short distance
Message-ID: <001a01c95701$c2888340$6401a8c0@WSOffice>

Rick Harold wrote:
> All,
>
> I'm planning doing some experiments in distance measurement.  They don't
> deal with atomic time directly but with extreme short periods of time.
>
> I need to determine the position of a instrument with a 1mm accuracy or
> less.
> The instrument is not connected to a mechanical device but is separate &
> independent.
> The surface which the instrument is positioned on is close to the size of a
> 11"x11" square.
>
> I thought of using 1 RF transmitters (not sure of freq) on bottom of the
> device near the surface.
> The surface would have RF receivers on 3 or 4 edges/corners to receive the
> signal.
>
> If each of the receivers positions are known and they then send a signal to
> a central circuit (again known positions) how can I differentiate the time
> of arrival
> at the central location?  Does anybody know of a circuit/chip or system
> which would determine the time 'difference'.
> Obviously this is used to triangulate the position of the instrument.
> Light travels 1 mm in ~3.3 picoseconds so I would suspect the differentiator
> would have to have that or better resolution.
> It could also use some proportional method to extrapolate the position since
> the surface has a fixed size.
>
> Any ideas/thoughts?
>
> Thanks in advance.
>
> Rick Harold

********************
Rick

The way you are describing doing it may have one additional BIG problem you may not of addressed.
The antennas must be smaller than 1mm or at least be stable in effective position to that accuracy. 

As far as the basic configuration of how to do it, all you need is one transmitter, one narrow band FM receiver,
Three or four antennas and a RF audio mux between the antennas and the receivers. 
It uses the receivers audio freq / phase detector AKA, FM discriminator. No great Phase detector or special stuff like that.

The way that it works for example, say you are using a freq with a wave length of  1 inch.
Then if  two of your antennas are say 1/4 inch apart  ( or 1 mm apart or 1/4 plus any multiple of the one wave length) 
The AUDIO out of the receiver will be modulated "A lot" due to the FM caused by the 1/4 wave phase steps it sees.
This can resolve as fine of distances as you want until it reaches the noise level of your receiver and transmitters oscillators.
the system phase gain works out to be the ratio of the audio mux to the RF. 
To be sure there are all kinds of other issues you would have to address but having the resolution to determine 
the phase to below 3.3 ps need not be one of major ones.

Have fun,
WarrenS

From masondg44 at comcast.net  Fri Dec  5 18:03:06 2008
From: masondg44 at comcast.net (Dave M)
Date: Fri, 5 Dec 2008 13:03:06 -0500
Subject: [time-nuts] time-nuts Digest, Vol 53, Issue 28
References: <mailman.105.1228499348.2499.time-nuts@febo.com>
Message-ID: <56B721E2F8014553A56881CCA482D828@DELL2350>

Fri, 5 Dec 2008 09:31:50 -0800
From: "Tom Van Baak" <tvb at LeapSecond.com>
Subject: Re: [time-nuts] Thunderbolt time-nuts/TAPR Group Buy - status
To: "Discussion of precise time and frequency measurement"
<time-nuts at febo.com>
Message-ID: <028FF033DD9047E0A2A88CCA6AF7709A at pc52>
Content-Type: text/plain; format=flowed; charset="Windows-1252";
reply-type=original

>>   Hi Tom,
>>
>>   I also sent you an email off-list, requesting two TBolts, but I have
>>   not received a reply. I'd like to prepay so I don't lose out  due to
>>   transfer of funds from Canada like the last time.
>>
>>   Please let me know if this is possible.
>>
>>   Thanks,
>>
>>   Best Regards,
>>
>>   Mike Monett

> Consider this a reply to you and all the others who contacted
> me off-line. I'm keeping the names on file and will give you
> first notice when the next batch is ready.
>
> /tvb
>

Since I'm a relative new-comer to time-nuts, I didn't get the details of the 
TBolt offer.   What are the details...  which TBolt unit, price, shipping, forms 
of payment, etc.?

I'm the proud owner of a Z3801A that's been running flawlessly for over 3 years. 
I have the G4FRE / WW2R  digital clock add-on for it..  just haven't had time to 
put it all together.  A good winter project.

-- 
Dave M
MasonDG44 at comcast dot net  (Just substitute the appropriate characters in the 
address)

Life is like a roll of toilet paper; the closer it gets to the end, the faster 
it goes.





From w3kl at w3kl.com  Fri Dec  5 18:14:55 2008
From: w3kl at w3kl.com (w3kl at w3kl.com)
Date: Fri, 5 Dec 2008 10:14:55 -0800 (PST)
Subject: [time-nuts] position determination over short distance
In-Reply-To: <001a01c95701$c2888340$6401a8c0@WSOffice>
Message-ID: <243909.92158.qm@web35406.mail.mud.yahoo.com>

Sorry to jump in here so late in the discussion thread.
?
Have you considered a laser interferometer (which is an accepted primary standard for measuring displacement).? Over the distance you want to measure you'll get much better than 1 mm accuracy (closer to 1 micron actually, assuming you take care of all of the second order effects that can ruin a measurement like this).
?
You should also look at photogrammetry, which will easily get you 1 mm accuracies.
?
Hope this helps.
?
Jeff

Jeffrey K. Okamitsu, PhD, MBA
+1-609-638-5402

--- On Fri, 12/5/08, WarrenS <warrensjmail-one at yahoo.com> wrote:

From: WarrenS <warrensjmail-one at yahoo.com>
Subject: [time-nuts] position determination over short distance
To: "Discussion of precise time and frequency measurement" <time-nuts at febo.com>
Date: Friday, December 5, 2008, 12:49 PM

Rick Harold wrote:
> All,
>
> I'm planning doing some experiments in distance measurement.  They
don't
> deal with atomic time directly but with extreme short periods of time.
>
> I need to determine the position of a instrument with a 1mm accuracy or
> less.
> The instrument is not connected to a mechanical device but is separate
&
> independent.
> The surface which the instrument is positioned on is close to the size of
a
> 11"x11" square.
>
> I thought of using 1 RF transmitters (not sure of freq) on bottom of the
> device near the surface.
> The surface would have RF receivers on 3 or 4 edges/corners to receive the
> signal.
>
> If each of the receivers positions are known and they then send a signal
to
> a central circuit (again known positions) how can I differentiate the time
> of arrival
> at the central location?  Does anybody know of a circuit/chip or system
> which would determine the time 'difference'.
> Obviously this is used to triangulate the position of the instrument.
> Light travels 1 mm in ~3.3 picoseconds so I would suspect the
differentiator
> would have to have that or better resolution.
> It could also use some proportional method to extrapolate the position
since
> the surface has a fixed size.
>
> Any ideas/thoughts?
>
> Thanks in advance.
>
> Rick Harold

********************
Rick

The way you are describing doing it may have one additional BIG problem you may
not of addressed.
The antennas must be smaller than 1mm or at least be stable in effective
position to that accuracy. 

As far as the basic configuration of how to do it, all you need is one
transmitter, one narrow band FM receiver,
Three or four antennas and a RF audio mux between the antennas and the
receivers. 
It uses the receivers audio freq / phase detector AKA, FM discriminator. No
great Phase detector or special stuff like that.

The way that it works for example, say you are using a freq with a wave length
of  1 inch.
Then if  two of your antennas are say 1/4 inch apart  ( or 1 mm apart or 1/4
plus any multiple of the one wave length) 
The AUDIO out of the receiver will be modulated "A lot" due to the FM
caused by the 1/4 wave phase steps it sees.
This can resolve as fine of distances as you want until it reaches the noise
level of your receiver and transmitters oscillators.
the system phase gain works out to be the ratio of the audio mux to the RF. 
To be sure there are all kinds of other issues you would have to address but
having the resolution to determine 
the phase to below 3.3 ps need not be one of major ones.

Have fun,
WarrenS
_______________________________________________
time-nuts mailing list -- time-nuts at febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

From bg at lysator.liu.se  Fri Dec  5 19:53:52 2008
From: bg at lysator.liu.se (=?ISO-8859-1?Q?Bj=F6rn?= Gabrielsson)
Date: Fri, 05 Dec 2008 20:53:52 +0100
Subject: [time-nuts] position determination over short distance
In-Reply-To: <001a01c95701$c2888340$6401a8c0@WSOffice>
References: <001a01c95701$c2888340$6401a8c0@WSOffice>
Message-ID: <1228506832.27003.16.camel@bg-desktop>


On Fri, 2008-12-05 at 09:49 -0800, WarrenS wrote:

> The way you are describing doing it may have one additional BIG problem you may not of addressed.
> The antennas must be smaller than 1mm or at least be stable in effective position to that accuracy. 

Good geodetic quality GPS antennas have well defined phase centers that
are stable at the mm level. This is even though the antenna element
might be the size of a small plate and the groundplane (chokering) is
the size of a pizza.

Above said, I would explore a digital camera solution for the OPs
problem.

--

   Bj?rn



From technoid_tim at comcast.net  Fri Dec  5 19:55:27 2008
From: technoid_tim at comcast.net (Tim Schulz)
Date: Fri, 05 Dec 2008 12:55:27 -0700
Subject: [time-nuts] Ion pump power supply, Cs tube storage life
Message-ID: <4939872F.2050109@comcast.net>

Greetings again fellow listers - I have been trying to build a voltage 
multiplier to replace what I believe to be a dead one in my 5062C ion 
pump power supply.  I downloaded the 5061service manual (thanks 
Leapsecond!!), and it states that it is a doubler in that power supply.  
I long ago got rid of my HV parts stock at a ham swap foolishly thinking 
that I wouldn't be needing them, so I had to pay $6 each for a couple of 
NTE 2Kv PIV diodes at the local parts house.  I decided that HP might 
have used Greinacher type doubler and put one together using some 2Kv 
rated .01uf ceramic caps.  What I got out of it when hooked up to the 
ion pump ps was about 1.77Kv AC according to my Fluke 8060 and high 
voltage divider probe.  So I guess I am not quite there yet and would 
appreciate more guidance in that area.  I did get a Bertan 5Kv 
adjustable PS off ebay as a plan "B" if I can't fix the original 
supply.  I also tried to dissolve the potting material on the defective 
module, but sitting in xylol for 2 days hasn't done anything.
Also, I was wondering if Cs tubes could be stored for long periods (say 
10-20 years) as long as the ion pump was kept active or at least at 
regular intervals.  I was wondering what the failure modes might be - 
air leakage, or does the cesium sublimate over time out of the oven?  
Also, is anybody able to rebuild Cs tubes?  Again, I am wondering if I 
would be able to find a replacement down the road for the compact tube 
in the 5062.
Thanks again!  tim


From bruce.griffiths at xtra.co.nz  Fri Dec  5 21:01:17 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Sat, 06 Dec 2008 10:01:17 +1300
Subject: [time-nuts] Ion pump power supply, Cs tube storage life
In-Reply-To: <4939872F.2050109@comcast.net>
References: <4939872F.2050109@comcast.net>
Message-ID: <4939969D.7060506@xtra.co.nz>

Tim Schulz wrote:
> Greetings again fellow listers - I have been trying to build a voltage 
> multiplier to replace what I believe to be a dead one in my 5062C ion 
> pump power supply.  I downloaded the 5061service manual (thanks 
> Leapsecond!!), and it states that it is a doubler in that power supply.  
> I long ago got rid of my HV parts stock at a ham swap foolishly thinking 
> that I wouldn't be needing them, so I had to pay $6 each for a couple of 
> NTE 2Kv PIV diodes at the local parts house.  I decided that HP might 
> have used Greinacher type doubler and put one together using some 2Kv 
> rated .01uf ceramic caps.  What I got out of it when hooked up to the 
> ion pump ps was about 1.77Kv AC according to my Fluke 8060 and high 
> voltage divider probe.  So I guess I am not quite there yet and would 
> appreciate more guidance in that area.  I did get a Bertan 5Kv 
> adjustable PS off ebay as a plan "B" if I can't fix the original 
> supply.  I also tried to dissolve the potting material on the defective 
> module, but sitting in xylol for 2 days hasn't done anything.
> Also, I was wondering if Cs tubes could be stored for long periods (say 
> 10-20 years) as long as the ion pump was kept active or at least at 
> regular intervals.  I was wondering what the failure modes might be - 
> air leakage, or does the cesium sublimate over time out of the oven?  
> Also, is anybody able to rebuild Cs tubes?  Again, I am wondering if I 
> would be able to find a replacement down the road for the compact tube 
> in the 5062.
> Thanks again!  tim
>
>   
If the potting is epoxy tetrahydrofuran may be more effective.

Bruce


From bruce.griffiths at xtra.co.nz  Fri Dec  5 21:07:07 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Sat, 06 Dec 2008 10:07:07 +1300
Subject: [time-nuts] Sub Pico Second Phase logger
In-Reply-To: <02e501c956c9$f225f980$6401a8c0@WSOffice>
References: <02e501c956c9$f225f980$6401a8c0@WSOffice>
Message-ID: <493997FB.6050700@xtra.co.nz>

WarrenS wrote:
> Bruce
>
> asked)  
> Doesn't this phase detector, like all digital phase detectors, have
> significant non linearity at the ends of its range?
> In the case of an XOR gate phase detector this is caused by the finite
> slew rate of the gate output.
>
> Thanks for all the ideas and Information. 
> True, XORs don't work good at the end of their range for several reasions. 
> This is why I had to put in the second pair of detectors.
> K1 and K2 are used in the example as a sort of "smooth linear demulplexer" 
> to switch between the phase detectors.  As one set of differential 
> phase detectors gets near its nonlinear and troublesome range at their zero 
> and 180 phase point their output change contribution is COMPLETELY shut down 
> by the a "sin" like function product of K and Phase#. Not really a sin 
> function and not really done as K's. The function of the sum of the two 
> phase detectors will be dependent on the voltages themself. 
> That is their modified voltage out will have less effect the farther away 
> from zero their phase voltage is.  A  smooth clipper function. 
> For a given detector pair the farther from zero it is the less its change 
> will contrubute. When both the zero and 90 degree phase detectors 
> are half way between zero and rail, their outputs gets summed together 
> with a weighing factor of 1/2 each. 
> One disadvantage of  the quad phase detectors,  is to work good and 
> allow the digital processing functions I want to have, there has to be two 
> seperate data paths, one from each Pair of phase detectors. 
> The data rate is slow enough even with the desired oversampling 
> that a multiplexed ADC my be OK.
> Is there anything that cares about faster than about 10Hz high resolution
> phase update times, that a simple analog XOR phase detector could handle? 
>
> Also I do not think that the linearity has to be very good. I was thinking if 
> it stays within say 90% it would be good enough for what I know of. The important 
> thing is Just so it stays monotonic and glitch free with no hysteresis etc which 
> it seems to do. It is not 1 million to one accurate as you know, maybe more like 
> within 1% or 0.1%. The one I build only has a  million to one resolution 
> around 90, 270 degs, zero and 180 deg. which is the only place I generally using it. 
> At the moment the accuracy and noise performance with the detector away 
> from its zero output value is limited by the accuracy of the reference along 
> with a lot of other gain error things. 
> Is there any use for a truly linear and accurate simple phase detector?  
> I supose it could be done, in a similar mater, but may have to add a couple parts.
>
> You also said HCMOS buffers have 4ps or so of jitter. Is this the kind of jitter noise 
> that can be filtered down into the mud with the present 100ms analog Bandwidth 
> and the 250K samples that are effectively being averaging?  
> Do you have any knowledge or guess on ICs NON tracking delay change with Temp? 
> I've tried to match all delays in the four loops, by always having a part from the same 
> IC in each loop, so mostly, as long as all like parts in any single IC track well then their 
> zero errors should cancel.
> I have not tested it much below 1ps except to see what I think was more like 0.1 ps resolution.
> The test I did for that was to move my hand near the center of one channel's shielded 
> signal cable the watched the phase output smoothly change like a proximity detector 
> as my hand approached the shielded cable, not due to cap to ground but due to the 
> cable delay changing. Thoses electrons just don't get very far in 100fs
> I am considering using a faster famly, but I do want to say away from anything that 
> produces any heat. It looks like temperture offsets and changes are going to be the 
> limiting factor for zero stability. 
> I use the same dual detector design to phase lock now, but I never have checked or 
> cared how good it can get. 
>
> Thanks for the review and feedback, I've added several questions, please comment where you can? 
> I'm planning to make another pass at it and clean it up for thermos etc. and see how low it will go. 
>
> ************
> Concerning other uses of the single differential XOR phase detector.
> If anyone wants to improve the performance of an existing crappy XOR phase detector
> they may want to consider the differential XOR detector. Just be sure to include a good differential 
> integrator (with a zero pole) at its output before driving the EFC so that the phase detector's 
> output always stays at zero. The differential detector can reduce phase detector errors 
> by many orders of magnitude. 
>
> WarrenS
>
>   
Warren

Another potential issue is crosstalk between flipflops in the same
package, in particular between the 2 clock signals.
Such effects will not be evident when using a single clock source to
evaluate the system noise.
Using fully differential logic such as ECL will reduce such coupling at
the expense on increased power dissipation and relatively high logic
level tempcos.
Dithering one or both of the clocks may help.

Bruce

Bruce



From bruce.griffiths at xtra.co.nz  Fri Dec  5 21:57:22 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Sat, 06 Dec 2008 10:57:22 +1300
Subject: [time-nuts] Sub Pico Second Phase logger
In-Reply-To: <493997FB.6050700@xtra.co.nz>
References: <02e501c956c9$f225f980$6401a8c0@WSOffice>
	<493997FB.6050700@xtra.co.nz>
Message-ID: <4939A3C2.1010102@xtra.co.nz>

  

> Warren
>
> Another potential issue is crosstalk between flipflops in the same
> package, in particular between the 2 clock signals.
> Such effects will not be evident when using a single clock source to
> evaluate the system noise.
> Using fully differential logic such as ECL will reduce such coupling at
> the expense on increased power dissipation and relatively high logic
> level tempcos.
> Dithering one or both of the clocks may help.
>
> Bruce
>
>   
The effect of cross coupling between the clocks will be more significant
as the phase shift between the clocks approaches 0 or 180 degrees (for
50% duty cycle clocks).
Dividing the input frequencies by 4 to produce quadrature phase outputs
wont help.
You would need to actually use a pair of phase shifted clocks from one
of the input sources feeding separate dividers so that clock transitions
of the 2 clocks within a chip do not coincide.
Either a selected length of coax or a quadrature hybrid would suffice
for producing the 2 clocks with a near 90 degree phase shift.

Bruce


From bruce.griffiths at xtra.co.nz  Fri Dec  5 22:03:18 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Sat, 06 Dec 2008 11:03:18 +1300
Subject: [time-nuts] Sub Pico Second Phase logger
In-Reply-To: <4939A3C2.1010102@xtra.co.nz>
References: <02e501c956c9$f225f980$6401a8c0@WSOffice>	<493997FB.6050700@xtra.co.nz>
	<4939A3C2.1010102@xtra.co.nz>
Message-ID: <4939A526.3090501@xtra.co.nz>

Warren
>> Another potential issue is crosstalk between flipflops in the same
>> package, in particular between the 2 clock signals.
>> Such effects will not be evident when using a single clock source to
>> evaluate the system noise.
>> Using fully differential logic such as ECL will reduce such coupling at
>> the expense on increased power dissipation and relatively high logic
>> level tempcos.
>> Dithering one or both of the clocks may help.
>>
>> Bruce
>>
>>   
>>     
> The effect of cross coupling between the clocks will be more significant
> as the phase shift between the clocks approaches 0 or 180 degrees (for
> 50% duty cycle clocks).
> Dividing the input frequencies by 4 to produce quadrature phase outputs
> wont help.
> You would need to actually use a pair of phase shifted clocks from one
> of the input sources feeding separate dividers so that clock transitions
> of the 2 clocks within a chip do not coincide.
> Either a selected length of coax or a quadrature hybrid would suffice
> for producing the 2 clocks with a near 90 degree phase shift.
>
> Bruce
>
>   
A much simpler solution to the clock cross coupling problem is to use
separate chips for the 2 dividers and live with the less accurate delay
tracking.
One then has to ensure that significant cross coupling via the power
supply and ground systems doesnt occur.

Bruce



From cdelect at juno.com  Sat Dec  6 00:59:32 2008
From: cdelect at juno.com (Corby Dawson)
Date: Fri, 5 Dec 2008 16:59:32 -0800
Subject: [time-nuts] Ion pump power supply, Cs tube storage life
Message-ID: <20081205.165932.532.2.cdelect@juno.com>

 
Tim,

I did disassemble a 5062C  ion pump supply and I do have the schematic of
the potted tripler. 

I picked the potting apart a bit at a time. It has .2uf capacitors and
high voltage diodes.

I can look thru my documents and get the schematic for you if you want,


Corby Dawson
 
____________________________________________________________
Click here to find experienced pros to help with your home improvement project.
http://thirdpartyoffers.juno.com/TGL2141/fc/PnY6rw2eRInpipstJSviWmrt6ftWXsLpB8vWvSL1ZySRqV0wFLGz3/


From warrensjmail-one at yahoo.com  Sat Dec  6 03:53:35 2008
From: warrensjmail-one at yahoo.com (WarrenS)
Date: Fri, 5 Dec 2008 19:53:35 -0800
Subject: [time-nuts] Sub Pico Second Phase logger
References: <02e501c956c9$f225f980$6401a8c0@WSOffice><493997FB.6050700@xtra.co.nz>
	<4939A3C2.1010102@xtra.co.nz>
Message-ID: <005401c95756$37371310$6401a8c0@WSOffice>

Bruce

Thanks, for pointing out my FF mistake. I do know that at this level of resolution 
you can not have two edges that are close together in the same AIR Space, 
let alone the same IC without some interaction.I would not put them on the same PCB or PS
when checking what the best possible resolution is.

I was thinking because of the dual 90 deg paths, the IC in which the 
two phases got close together would not be used at that time anyway so it did not matter too much. 
Obviously I blew it big time by forgetting to consider the first set of FFs whose edges can and do cross. 
In my case this is not a problem because these FF are in fact on the reference osc and not in my breadboard. 
& I messed up, Thanks for pointing  what out.  

The description I gave is not my present phase detector. 
I include all the extra possibilities I could think of and some planned upgrades,
to make it into a more General purpose & flexible tool instead of the simple 
one function tool it now is. 

I need to remember the KISS concept. The best is the simple way.
For sub pico second measurement a single dual XOR differential phase detector is all that is needed. 
All that extra stuff I is only needed if someone wanted to make a very general purpose 
wide range less accurate XOR phase detector. 

The trick to keeping it simple and accurate is the willingness to change the phase 
of the low noise (2.5 MHz divided down) Osc to 90 deg offset at the start of the test.
The way I do it is: on my test OCXO Osc I have added a semi calibrated, 10 turn dial that I can 
fine set its freq to 1 part in 1E-12 resolution. 
It also has an added switch that allows the output of the dual differential sub pico second Phase detector 
to change the phase of  the test Osc in a short time period by way of the ECF.
Once the two signal are phase locked at 90 deg, indicated by the dual phase detector at zero volts out, 
I open the lock phase switch, re-adjust the fine freq trim pot if necessary so that the phase detector does 
not drift off too fast, and rezero the detector again with the switch when required, etc. 

To record data, I set my cheap little isolated 4+ digit PC logable DVM to its mV range, 
 and log data at once per second which is good for as long as the phase detector's output  
stays around zero. This all requires a manual set up, It takes a little extra time, BUT it gets the job done.
It is also Very cheap to build and it seems to perform better than most near 'state of the art' home equipment.
The whole thing takes 3 Ics including some extra non related stuffs. 

Thanks for your feedback, If you see or think of anything else you feel would be helpful to me do please let me know.

WarrenS

************************
>> Warren
>>
>> Another potential issue is crosstalk between flipflops in the same
>> package, in particular between the 2 clock signals.
>> Such effects will not be evident when using a single clock source to
>> evaluate the system noise.
>> Using fully differential logic such as ECL will reduce such coupling at
>> the expense on increased power dissipation and relatively high logic
>> level tempcos.
>> Dithering one or both of the clocks may help.
>>
>> Bruce
******************************* 
> The effect of cross coupling between the clocks will be more significant
> as the phase shift between the clocks approaches 0 or 180 degrees (for
> 50% duty cycle clocks).
> Dividing the input frequencies by 4 to produce quadrature phase outputs
> wont help.
> You would need to actually use a pair of phase shifted clocks from one
> of the input sources feeding separate dividers so that clock transitions
> of the 2 clocks within a chip do not coincide.
> Either a selected length of coax or a quadrature hybrid would suffice
> for producing the 2 clocks with a near 90 degree phase shift.
> 
> Bruce
>*******************************>   
>Warren
> A much simpler solution to the clock cross coupling problem is to use
>separate chips for the 2 dividers and live with the less accurate delay tracking.
>One then has to ensure that significant cross coupling via the power
>supply and ground systems doesn't occur.
>
Bruce
*********************

Warren
> Bruce
>
> asked)  
> Doesn't this phase detector, like all digital phase detectors, have
> significant non linearity at the ends of its range?
> In the case of an XOR gate phase detector this is caused by the finite
> slew rate of the gate output.
>
> Thanks for all the ideas and Information. 
> True, XORs don't work good at the end of their range for several reasions. 
> This is why I had to put in the second pair of detectors.
> K1 and K2 are used in the example as a sort of "smooth linear demulplexer" 
> to switch between the phase detectors.  As one set of differential 
> phase detectors gets near its nonlinear and troublesome range at their zero 
> and 180 phase point their output change contribution is COMPLETELY shut down 
> by the a "sin" like function product of K and Phase#. Not really a sin 
> function and not really done as K's. The function of the sum of the two 
> phase detectors will be dependent on the voltages themself. 
> That is their modified voltage out will have less effect the farther away 
> from zero their phase voltage is.  A  smooth clipper function. 
> For a given detector pair the farther from zero it is the less its change 
> will contrubute. When both the zero and 90 degree phase detectors 
> are half way between zero and rail, their outputs gets summed together 
> with a weighing factor of 1/2 each. 
> One disadvantage of  the quad phase detectors,  is to work good and 
> allow the digital processing functions I want to have, there has to be two 
> seperate data paths, one from each Pair of phase detectors. 
> The data rate is slow enough even with the desired oversampling 
> that a multiplexed ADC my be OK.
>   
Multiplexing a sigma delta ADC inputs only works well if the ADC design
is appropriate.
Linear technology have some especially designed for use with multiplexed
inputs.
Sigma delta ADCs are relatively inexpensive so one could always use a
couple of them.
Surely the outputs of both phase detectors are required to sort out the
the sign/direction of phase changes?
One could always log both outputs and sort out the sign of any changes
together with the appropriate output to use for determining the
magnitude in software.
> Is there anything that cares about faster than about 10Hz high resolution
> phase update times, that a simple analog XOR phase detector could handle? 
>
> Also I do not think that the linearity has to be very good. I was thinking if 
> it stays within say 90% it would be good enough for what I know of. The important 
> thing is Just so it stays monotonic and glitch free with no hysteresis etc which 
> it seems to do. It is not 1 million to one accurate as you know, maybe more like 
> within 1% or 0.1%. The one I build only has a  million to one resolution 
> around 90, 270 degs, zero and 180 deg. which is the only place I generally using it. 
> At the moment the accuracy and noise performance with the detector away 
> from its zero output value is limited by the accuracy of the reference along 
> with a lot of other gain error things. 
> Is there any use for a truly linear and accurate simple phase detector?  
> I supose it could be done, in a similar mater, but may have to add a couple parts.
>
>   
Only when one uses such a phase detector to measure the frequency offset
between the 2 sources being compared as quickly and accurately as possible.
The principal source of non linearity near the ends of the range is due
to insufficient time available for the transitions to settle accurately
with short pulse widths.
If the value of the first resistor in the RC passive filter is too low
the output resistance mismatch between the 0 and 1 states will
contribute significantly to the nonlinearity.
Modulation of the output resistance of the gate/buffer driving the RC
filter can also be significant.
Both of these effects can easily be reduced to insignificance by using
appropriate feedback circuitry.
> You also said HCMOS buffers have 4ps or so of jitter. Is this the kind of jitter noise 
> that can be filtered down into the mud with the present 100ms analog Bandwidth 
> and the 250K samples that are effectively being averaging?  
> Do you have any knowledge or guess on ICs NON tracking delay change with Temp? 
>   
Random jitter will indeed average down to the femtosecond level with
that many samples.
A crude way of estimating the propagation delay mismatch tempco for CMOS
ICs is to assume that the propagation delay mismatch has the same tempco
as the propagation delay itself or about +0.4%/C.
e.g. if the propagation delay is say 10ns and the mismatch is 10% (1ns)
then the delay mismatch tempco will be in the region of 4ps/C.

> I've tried to match all delays in the four loops, by always having a part from the same 
> IC in each loop, so mostly, as long as all like parts in any single IC track well then their 
> zero errors should cancel.
> I have not tested it much below 1ps except to see what I think was more like 0.1 ps resolution.
> The test I did for that was to move my hand near the center of one channel's shielded 
> signal cable the watched the phase output smoothly change like a proximity detector 
> as my hand approached the shielded cable, not due to cap to ground but due to the 
> cable delay changing. Thoses electrons just don't get very far in 100fs
> I am considering using a faster famly, but I do want to say away from anything that 
> produces any heat. It looks like temperture offsets and changes are going to be the 
> limiting factor for zero stability. 
>   
If the power dissipation is low it would be feasible to use a
bootstrapped oven (similar in thermal design to some of the standard
cell oven designs from the 50's and 60's) like Wenzel has used to
achieve sup-picosecond stability in a frequency multiplier.
> I use the same dual detector design to phase lock now, but I never have checked or 
> cared how good it can get. 
>
> Thanks for the review and feedback, I've added several questions, please comment where you can? 
> I'm planning to make another pass at it and clean it up for thermos etc. and see how low it will go. 
>
> ************
> Concerning other uses of the single differential XOR phase detector.
> If anyone wants to improve the performance of an existing crappy XOR phase detector
> they may want to consider the differential XOR detector. Just be sure to include a good differential 
> integrator (with a zero pole) at its output before driving the EFC so that the phase detector's 
> output always stays at zero. The differential detector can reduce phase detector errors 
> by many orders of magnitude. 
>
> WarrenS
>
>   



From bruce.griffiths at xtra.co.nz  Sat Dec  6 04:30:32 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Sat, 06 Dec 2008 17:30:32 +1300
Subject: [time-nuts] Sub Pico Second Phase logger
In-Reply-To: <005401c95756$37371310$6401a8c0@WSOffice>
References: <02e501c956c9$f225f980$6401a8c0@WSOffice><493997FB.6050700@xtra.co.nz>	<4939A3C2.1010102@xtra.co.nz>
	<005401c95756$37371310$6401a8c0@WSOffice>
Message-ID: <4939FFE8.50908@xtra.co.nz>

WarrenS wrote:
> Bruce
>
> Thanks, for pointing out my FF mistake. I do know that at this level of resolution 
> you can not have two edges that are close together in the same AIR Space, 
> let alone the same IC without some interaction.I would not put them on the same PCB or PS
> when checking what the best possible resolution is.
>
> I was thinking because of the dual 90 deg paths, the IC in which the 
> two phases got close together would not be used at that time anyway so it did not matter too much. 
> Obviously I blew it big time by forgetting to consider the first set of FFs whose edges can and do cross. 
> In my case this is not a problem because these FF are in fact on the reference osc and not in my breadboard. 
> & I messed up, Thanks for pointing  what out.  
>
> The description I gave is not my present phase detector. 
> I include all the extra possibilities I could think of and some planned upgrades,
> to make it into a more General purpose & flexible tool instead of the simple 
> one function tool it now is. 
>
> I need to remember the KISS concept. The best is the simple way.
> For sub pico second measurement a single dual XOR differential phase detector is all that is needed. 
> All that extra stuff I is only needed if someone wanted to make a very general purpose 
> wide range less accurate XOR phase detector. 
>
> The trick to keeping it simple and accurate is the willingness to change the phase 
> of the low noise (2.5 MHz divided down) Osc to 90 deg offset at the start of the test.
> The way I do it is: on my test OCXO Osc I have added a semi calibrated, 10 turn dial that I can 
> fine set its freq to 1 part in 1E-12 resolution. 
> It also has an added switch that allows the output of the dual differential sub pico second Phase detector 
> to change the phase of  the test Osc in a short time period by way of the ECF.
> Once the two signal are phase locked at 90 deg, indicated by the dual phase detector at zero volts out, 
> I open the lock phase switch, re-adjust the fine freq trim pot if necessary so that the phase detector does 
> not drift off too fast, and rezero the detector again with the switch when required, etc. 
>
> To record data, I set my cheap little isolated 4+ digit PC logable DVM to its mV range, 
>  and log data at once per second which is good for as long as the phase detector's output  
> stays around zero. This all requires a manual set up, It takes a little extra time, BUT it gets the job done.
> It is also Very cheap to build and it seems to perform better than most near 'state of the art' home equipment.
> The whole thing takes 3 Ics including some extra non related stuffs. 
>
> Thanks for your feedback, If you see or think of anything else you feel would be helpful to me do please let me know.
>
> WarrenS
>
>   
Warren

Some commercial instruments share flipflops in the same package between
2 channels each with a slightly different clock frequency.
The crosstalk between channels is largely capacitive in nature and can
be canceled to some extent by injecting a small portion of the
(antiphase) clock, crosstalk from which is to be canceled, via a
capacitor (of appropriate value). Whilst some improvement is possible
this isnt a complete cure.

For the less stable oscillators, dividing down the frequencies before
comparison with the limited range XOR phase detector is desirable if
they are to be monitored over a relatively long time.

HP used to make the K34-5991A phase comparator that used an ECL XOR
phase comparator.
This instrument was intended for driving a strip chart recorder.
It allowed the user to set the output to the ideal value for 180 degree
and zero degree phase shift between the inputs for calibration purposes.

Ratiometric conversion of the low pass filtered XOR output will reduce
the dependence of the measurement on power supply voltage.

Bruce


From warrensjmail-one at yahoo.com  Sat Dec  6 04:55:38 2008
From: warrensjmail-one at yahoo.com (WarrenS)
Date: Fri, 5 Dec 2008 20:55:38 -0800
Subject: [time-nuts] position determination over short distance
Message-ID: <009601c9575e$e24f7410$6401a8c0@WSOffice>


To  Bj??rn
wow,  neat, mm accurate antennas, 
That means the RF way still has some hope.
How does it get the information down the cable without unacceptable loss of accuracy?
Anyone know how they make these antennas, and can it be done with small cheapy ones?


To Rick:
I guess Rick,  you now know the RF frequency to use, Just watch out for the GPS police.

I think if Rick Harold would of wanted to use optics, then he would of asked the light-nuts instead of the freq-nuts.

One thing I don't think I have ever seen from Rick is anything about the time frame and the budget?
These are probable the two most important relevant requirements, funny they are unknown.
The $10 dollars options are probable different than the $100,000 ones.

I don't remember if you where going 2 or 3 or 4 D. 

Here are some ways to do it 2D on the cheap. 
Are you old enough to remember TV computers? most came with light pin options.
So all you need do is place your object on the  CRT type TV screen that is turned to face up, put the light pin in the center of the object pointing down at the TV and the basic program will tell you the location to about the accuracy you need if using the better game consoles.

You can also use an modern absolute position drawing pad for getting two D.

Or how about, they use to have a pen set that read the position of the pins tip when placed on the special pad, That was cheap.

Can you place you object on a touch screen panel?

Put a LED little red laser pointer down from above it on the ceiling and with a couple of motors "paint" the object with a TV type scan. Then provide some sort of sync so it is known where the pin is pointing at any time. A single photocell on the receiver could then determine its 2 D position. For 3 D use a second green led pointer painting from the side.

You know it sounds like you should look up the optic-nuts.
Or to get more relevant and serious answers you probable need to supply more information about the requirements.

Having too much Fun
WarrenS

**********************

----- Original Message ----- 
From: "Bj??rn Gabrielsson" <bg at lysator.liu.se>
To: "Discussion of precise time and frequency measurement" <time-nuts at febo.com>
Sent: Friday, December 05, 2008 11:53 AM
Subject: Re: [time-nuts] position determination over short distance



On Fri, 2008-12-05 at 09:49 -0800, WarrenS wrote:

> The way you are describing doing it may have one additional BIG problem you may not of addressed.
> The antennas must be smaller than 1mm or at least be stable in effective position to that accuracy. 

Good geodetic quality GPS antennas have well defined phase centers that
are stable at the mm level. This is even though the antenna element
might be the size of a small plate and the groundplane (chokering) is
the size of a pizza.

Above said, I would explore a digital camera solution for the OPs
problem.

--

   Bj??rn

Sorry to jump in here so late in the discussion thread.

Have you considered a laser interferometer (which is an accepted primary standard for measuring displacement). Over the distance you want to measure you'll get much better than 1 mm accuracy (closer to 1 micron actually, assuming you take care of all of the second order effects that can ruin a measurement like this).

You should also look at photogrammetry, which will easily get you 1 mm accuracies.

Hope this helps.

Jeff

Jeffrey K. Okamitsu, PhD, MBA
+1-609-638-5402

--- On Fri, 12/5/08, WarrenS <warrensjmail-one at yahoo.com> wrote:

From: WarrenS <warrensjmail-one at yahoo.com>
Subject: [time-nuts] position determination over short distance
To: "Discussion of precise time and frequency measurement" <time-nuts at febo.com>
Date: Friday, December 5, 2008, 12:49 PM

Rick Harold wrote:
> All,
>
> I'm planning doing some experiments in distance measurement.  They
don't
> deal with atomic time directly but with extreme short periods of time.
>
> I need to determine the position of a instrument with a 1mm accuracy or
> less.
> The instrument is not connected to a mechanical device but is separate
&
> independent.
> The surface which the instrument is positioned on is close to the size of
a
> 11"x11" square.
>
> I thought of using 1 RF transmitters (not sure of freq) on bottom of the
> device near the surface.
> The surface would have RF receivers on 3 or 4 edges/corners to receive the
> signal.
>
> If each of the receivers positions are known and they then send a signal
to
> a central circuit (again known positions) how can I differentiate the time
> of arrival
> at the central location?  Does anybody know of a circuit/chip or system
> which would determine the time 'difference'.
> Obviously this is used to triangulate the position of the instrument.
> Light travels 1 mm in ~3.3 picoseconds so I would suspect the
differentiator
> would have to have that or better resolution.
> It could also use some proportional method to extrapolate the position
since
> the surface has a fixed size.
>
> Any ideas/thoughts?
>
> Thanks in advance.
>
> Rick Harold

********************
Rick

The way you are describing doing it may have one additional BIG problem you may
not of addressed.
The antennas must be smaller than 1mm or at least be stable in effective
position to that accuracy. 

As far as the basic configuration of how to do it, all you need is one
transmitter, one narrow band FM receiver,
Three or four antennas and a RF audio mux between the antennas and the
receivers. 
It uses the receivers audio freq / phase detector AKA, FM discriminator. No
great Phase detector or special stuff like that.

The way that it works for example, say you are using a freq with a wave length
of  1 inch.
Then if  two of your antennas are say 1/4 inch apart  ( or 1 mm apart or 1/4
plus any multiple of the one wave length) 
The AUDIO out of the receiver will be modulated "A lot" due to the FM
caused by the 1/4 wave phase steps it sees.
This can resolve as fine of distances as you want until it reaches the noise
level of your receiver and transmitters oscillators.
the system phase gain works out to be the ratio of the audio mux to the RF. 
To be sure there are all kinds of other issues you would have to address but
having the resolution to determine 
the phase to below 3.3 ps need not be one of major ones.

Have fun,
WarrenS
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To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.






From james.p.lux at jpl.nasa.gov  Sat Dec  6 05:14:43 2008
From: james.p.lux at jpl.nasa.gov (Lux, James P)
Date: Fri, 5 Dec 2008 21:14:43 -0800
Subject: [time-nuts] position determination over short distance
In-Reply-To: <009601c9575e$e24f7410$6401a8c0@WSOffice>
Message-ID: <C55F4A43.33CF%James.P.Lux@jpl.nasa.gov>




On 12/5/08 8:55 PM, "WarrenS" <warrensjmail-one at yahoo.com> wrote:

>
>
> To  Bj??rn
> wow,  neat, mm accurate antennas,
> That means the RF way still has some hope.
> How does it get the information down the cable without unacceptable loss of
> accuracy?
> Anyone know how they make these antennas, and can it be done with small cheapy
> ones?
>

Nothing really special. Mostly, it's care in the surroundings.. A series of
choke rings to suppress multipath reflections from under the antenna.
Actually, putting the usual inexpensive hockey puck style antenna on a
cookie sheet makes a fair approximation.

The other thing is that they get calibrated.  You make a series of
observations of the signals from GPS satellites as they move overhead. You
know where the satellite is, and where the antenna is (in a long term
averaging sense), and you can calculate the phase center position as a
function of look angle.

I think the GIPSY software does this for you.

Once you know what a particular design does, then it's more a matter of
construction tolerances.



From warrensjmail-one at yahoo.com  Sat Dec  6 05:47:29 2008
From: warrensjmail-one at yahoo.com (WarrenS)
Date: Fri, 5 Dec 2008 21:47:29 -0800
Subject: [time-nuts] position determination over short distance
Message-ID: <00e501c95766$209fe400$6401a8c0@WSOffice>

James


Question
So if the antenna is rotated in any and all of its axes, it does not should like from what you are saying there is really just a single point in it like you get for say 'center of mass'. that stays at a known spot.
It sounds  more like a bunch of calibration points than a single point, similar to a calculated lookup table, depending on angle etc. 
Does the question make any since?
In any case do you think it would help in the original question, which was to measure NON GPS RF signal distances to mm distances??

Thanks,
Warren 

*********************

On 12/5/08 8:55 PM, "WarrenS" <warrensjmail-one at yahoo.com> wrote:

>
>
> To  Bj??rn
> wow,  neat, mm accurate antennas,
> That means the RF way still has some hope.
> How does it get the information down the cable without unacceptable loss of
> accuracy?
> Anyone know how they make these antennas, and can it be done with small cheapy
> ones?
>

Nothing really special. Mostly, it's care in the surroundings.. A series of
choke rings to suppress multipath reflections from under the antenna.
Actually, putting the usual inexpensive hockey puck style antenna on a
cookie sheet makes a fair approximation.

The other thing is that they get calibrated.  You make a series of
observations of the signals from GPS satellites as they move overhead. You
know where the satellite is, and where the antenna is (in a long term
averaging sense), and you can calculate the phase center position as a
function of look angle.

I think the GIPSY software does this for you.

Once you know what a particular design does, then it's more a matter of
construction tolerances.



From swingbyte at exemail.com.au  Sat Dec  6 14:11:15 2008
From: swingbyte at exemail.com.au (swingbyte)
Date: Sun, 07 Dec 2008 01:11:15 +1100
Subject: [time-nuts] ebay for the voltage nuts check item 140286890504
Message-ID: <493A8803.3070904@exemail.com.au>

Hi guys,
After the discussion here regarding voltage standards I thought I might 
point you to this ebay auction for two 3456 DMMs, which, as mentioned 
earlier, are great long term 6.5 digits.  Unfortunately I can't bid on 
these as no international shipping - But I'd rather someone here get 
them then the reseller :)

Tim


From warrensjmail-one at yahoo.com  Sat Dec  6 14:56:38 2008
From: warrensjmail-one at yahoo.com (WarrenS)
Date: Sat, 6 Dec 2008 06:56:38 -0800
Subject: [time-nuts] Analog or Digital GPSDO?
Message-ID: <007201c957b2$d8179870$6401a8c0@WSOffice>


Here is a posting meant to start a debate between open minded freq-nuts.
It is inspired by  Tom's latest posting  at http://www.leapsecond.com/pages/m12-adev/

All else being equal, Tom's data says to me that a simple analog front end design when 
combined with a microprocessor  is able to provide a better performing GPSDO 
than any digital only unit that is using just the 1PPS. 
It would appear that the analog front end can be as good and even better 
than using the sawtooth correction data.

I may be a bit pregidous toward analog because I have been using 
analog only sub ns tracking of the GPS error signal for a long time.

What analog or digital can not address is any of  the issues concerning non carrier phase receiver limitations. 
so I'd like to assume for this discussion that the GPSDO is using a Motorola Oncore type 
of receiver with position hold capability.

A different but related question is, does or would using some form of  waas help a GPSDO?

Have fun with it,
WarrenS




From warrensjmail-one at yahoo.com  Sat Dec  6 15:03:41 2008
From: warrensjmail-one at yahoo.com (WarrenS)
Date: Sat, 6 Dec 2008 07:03:41 -0800
Subject: [time-nuts] M12 100 Hz vs. 1PPS measurements
References: <F3D4DB1872C84B8AAD666A0DFBBB5BC0@pc52>
Message-ID: <008101c957b3$d3d7d670$6401a8c0@WSOffice>


Tom, 
This is great work and Information to see.
I do think that this will inspire, and make if not a giant leap, at least a small step to better GPSDO performance. 

1st question:
Does anyone have or can they tell me where to get a copy of the actual raw data Tom used for these plots?
http://www.leapsecond.com/pages/m12-adev/

The Link on his leapsecond site to the raw data seems to be missing.
www.LeapSecond.com/logs/ - Logbook and raw data (ask) 
A request to Tom, so far has gone unanswered.

2nd question 
Can anyone provide me with the filter formula or algorithm or any information 
regarding that is used by any of the better GPSDO units to calculate the ECV 
Dac output voltage.

I know about the simple basic 1st order averaging  filter used in some of the units, 
and the even more basic but effective over under check to increment / decrement 
an accumulator.  BUT it would seem to me there has got to be filters that give much 
better result than either of these available and being used out there.

Allan deviation (ADEV) and Modified Allan deviation (MDEV) 
http://www.mail-archive.com/time-nuts at febo.com/msg07211.html




I'm looking for just the basic formula used to process the phase error data before 
being applied to the DAC. I am not looking for anything secrete or with all the extra 
things some use to verify that the data is valid or appropriate before being applied 
or thrown away.

Thanks, for any information you can provide me.
WarrenS

**********************


----- Original Message ----- 
From: "Tom Van Baak" <tvb at LeapSecond.com>
To: "Discussion of precise time and frequency measurement" <time-nuts at febo.com>
Sent: Friday, December 05, 2008 12:32 AM
Subject: [time-nuts] M12 100 Hz vs. 1PPS measurements


>I know a number of you have been waiting for the results of
> this M12 experiment. I compared the performance of a 100 Hz
> output vs. a 1PPS output vs. a 1PPS with sawtooth correction.
> 
> http://www.leapsecond.com/pages/m12-adev/
> 
> I think it came out quite well and it may surprise some of you.
> 
> /tvb
> 
> 
> 
> 
>


From rdarlington at gmail.com  Sat Dec  6 15:26:04 2008
From: rdarlington at gmail.com (Robert Darlington)
Date: Sat, 6 Dec 2008 08:26:04 -0700
Subject: [time-nuts] ebay for the voltage nuts check item 140286890504
In-Reply-To: <493A8803.3070904@exemail.com.au>
References: <493A8803.3070904@exemail.com.au>
Message-ID: <b3bd5fcb0812060726s6396599cn1e75dd4c8ccccfd3@mail.gmail.com>

After the recent post about the 3456A I figured I'd get one for myself.  I
put a bid of $150 on one after seeing previous auctions go for no more than
about 70 bucks.  I got outbid.  This list is great advertising for eBay
items!

As it turned out, a buddy of mine had a 3456A and gave it to me when I
mentioned I put the bid on one, and his is still in cal.  He "upgraded" to a
more portable 5 digit model.

-Bob

On Sat, Dec 6, 2008 at 7:11 AM, swingbyte <swingbyte at exemail.com.au> wrote:

> Hi guys,
> After the discussion here regarding voltage standards I thought I might
> point you to this ebay auction for two 3456 DMMs, which, as mentioned
> earlier, are great long term 6.5 digits.  Unfortunately I can't bid on
> these as no international shipping - But I'd rather someone here get
> them then the reseller :)
>
> Tim
>
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>

From james.p.lux at jpl.nasa.gov  Sat Dec  6 15:36:52 2008
From: james.p.lux at jpl.nasa.gov (Lux, James P)
Date: Sat, 6 Dec 2008 07:36:52 -0800
Subject: [time-nuts] position determination over short distance
In-Reply-To: <00e501c95766$209fe400$6401a8c0@WSOffice>
Message-ID: <C55FDC14.33EF%James.P.Lux@jpl.nasa.gov>




On 12/5/08 9:47 PM, "WarrenS" <warrensjmail-one at yahoo.com> wrote:

> James
>
>
> Question
> So if the antenna is rotated in any and all of its axes, it does not should
> like from what you are saying there is really just a single point in it like
> you get for say 'center of mass'. that stays at a known spot.
> It sounds  more like a bunch of calibration points than a single point,
> similar to a calculated lookup table, depending on angle etc.
> Does the question make any since?


Yes.  What you're talking about is the "phase center" of the antenna.  Most
antennas have a fairly well defined phase center over some restricted set of
angles.

A perfect point source antenna would have the phase center at the point.
But, in real life antennas have physical extent, so the possibility arises
of the apparent phase center moving depending on what direction the incident
wavefront is coming from.

Consider a point radiator some distance above a reflective plane, and look
at the received phase at the point, as the angle of incidence of the
wavefront changes.  The point receives both the direct signal and the
reflected signal which combine to form something with different phase and
amplitude.


If you're building a feed for a parabolic dish, it's pretty easy to arrange
the phase center to be in a fixed location (i.e. The focus of the parabola),
but the field of view of the feed is only a small fraction of a hemisphere.


For GPS antennas, where you really want coverage over a hemisphere, its a
bit more challenging.  Mostly, it's a matter of suppressing the reflections
and creeping waves along the surface next to the antenna. (i.e. A patch or
quad helix in free space is pretty good.. But darn it, you've got to mount
it on something, and usually, you want the antenna on something else anyway,
like some sort of building)


There are published (online) data for lots of GPS antennas that give phase
center tolerances and properties. (it's something of interest to precision
GPS folks like surveyors and geodysists)

> In any case do you think it would help in the original question, which was to
> measure NON GPS RF signal distances to mm distances??

Yes. Most antennas can be calibrated.  In the specific case here, you'd
probably do some sort of insitu calibration.  Move the target to known
locations and build up a cal table.  We did something similar a few years
back with a form of interferometer where we were interested in knowing the
angle of an incoming wavefront to fractions of a milliradian.  We put the
system in an anechoic chamber (it was big, so doing it on the benchtop
wasn't feasible) and then had a source 15 meters away that we moved on a
precision mechanical positioner.


Jim



From wittend at wwrinc.com  Sat Dec  6 16:24:49 2008
From: wittend at wwrinc.com (David M. Witten II)
Date: Sat, 06 Dec 2008 10:24:49 -0600
Subject: [time-nuts] Voltage Standards
In-Reply-To: <49310C27.2000902@bellsouth.net>
References: <604DA6FE-2511-4CBB-8D1B-2758A3FA5C58@hughes.net>
	<49310C27.2000902@bellsouth.net>
Message-ID: <493AA751.8010407@wwrinc.com>

Brian Kirby wrote:
...

> Maybe we should consider coming up with a standard voltage reference as 
> a TAPR project.  We have a lot of good brainpower out here and it seems 
> a lot of experience available.
> 
> Brian - KD4FM
> 


I would be very interested in a project like that.

Dave
KD0EAG


From df6jb at ulrich-bangert.de  Sat Dec  6 17:06:28 2008
From: df6jb at ulrich-bangert.de (Ulrich Bangert)
Date: Sat, 6 Dec 2008 18:06:28 +0100
Subject: [time-nuts] M12 100 Hz vs. 1PPS measurements
In-Reply-To: <008101c957b3$d3d7d670$6401a8c0@WSOffice>
Message-ID: <D0C509E08EA542ACAB23B9B8AB4EF782@athlon>

Warren,

if you consider Stanford Research as a producer of a "better GPSDO" you
can download their PRS10 manual from their web pages. It contains all
the math that you are asking for.

Best regards
Ulrich

> -----Ursprungliche Nachricht-----
> Von: time-nuts-bounces at febo.com 
> [mailto:time-nuts-bounces at febo.com] Im Auftrag von WarrenS
> Gesendet: Samstag, 6. Dezember 2008 16:04
> An: Discussion of precise time and frequency measurement
> Betreff: Re: [time-nuts] M12 100 Hz vs. 1PPS measurements
> 
> 
> 
> Tom, 
> This is great work and Information to see.
> I do think that this will inspire, and make if not a giant 
> leap, at least a small step to better GPSDO performance. 
> 
> 1st question:
> Does anyone have or can they tell me where to get a copy of 
> the actual raw data Tom used for these plots? 
> http://www.leapsecond.com/pages/m12-adev/
> 
> The Link on his leapsecond site to the raw data seems to be 
> missing. www.LeapSecond.com/logs/ - Logbook and raw data (ask) 
> A request to Tom, so far has gone unanswered.
> 
> 2nd question 
> Can anyone provide me with the filter formula or algorithm or 
> any information 
> regarding that is used by any of the better GPSDO units to 
> calculate the ECV 
> Dac output voltage.
> 
> I know about the simple basic 1st order averaging  filter 
> used in some of the units, 
> and the even more basic but effective over under check to 
> increment / decrement 
> an accumulator.  BUT it would seem to me there has got to be 
> filters that give much 
> better result than either of these available and being used out there.
> 
> Allan deviation (ADEV) and Modified Allan deviation (MDEV) 
> http://www.mail-archive.com/time-nuts at febo.com/msg07211.html
> 
> 
> 
> 
> I'm looking for just the basic formula used to process the 
> phase error data before 
> being applied to the DAC. I am not looking for anything 
> secrete or with all the extra 
> things some use to verify that the data is valid or 
> appropriate before being applied 
> or thrown away.
> 
> Thanks, for any information you can provide me.
> WarrenS
> 
> **********************
> 
> 
> ----- Original Message ----- 
> From: "Tom Van Baak" <tvb at LeapSecond.com>
> To: "Discussion of precise time and frequency measurement" 
> <time-nuts at febo.com>
> Sent: Friday, December 05, 2008 12:32 AM
> Subject: [time-nuts] M12 100 Hz vs. 1PPS measurements
> 
> 
> >I know a number of you have been waiting for the results of  
> this M12 
> >experiment. I compared the performance of a 100 Hz  output 
> vs. a 1PPS 
> >output vs. a 1PPS with sawtooth correction.
> > 
> > http://www.leapsecond.com/pages/m12-adev/
> > 
> > I think it came out quite well and it may surprise some of you.
> > 
> > /tvb
> > 
> > 
> > 
> > 
> >
> 
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to 
> https://www.febo.com/cgi-> bin/mailman/listinfo/time-nuts
> and 
> follow the instructions there.
> 



From df6jb at ulrich-bangert.de  Sat Dec  6 17:23:26 2008
From: df6jb at ulrich-bangert.de (Ulrich Bangert)
Date: Sat, 6 Dec 2008 18:23:26 +0100
Subject: [time-nuts] Analog or Digital GPSDO?
In-Reply-To: <007201c957b2$d8179870$6401a8c0@WSOffice>
Message-ID: <707DEF0799624FF988F7B5D4CC5EF23F@athlon>

Warren,

I may be teriible wrong but I understand Tom and his data so that PPS
and 100 Hz have the SAME performance (what I had expected) with the PPS
being able to be improved by the sawtooth correction. Attached are some
seconds of data from my GPSDO which second Tom's measurements as far as
the PPS is concerned.

> All else being equal, Tom's data says to me that a simple analog front
end design when 
> combined with a microprocessor  is able to provide a better performing
GPSDO 
> than any digital only unit that is using just the 1PPS.

Can you explain again why you are thinking this? Tom's claim is:

For all tau beyond 1 second, the ADEV of the 100 Hz output exactly
matches the ADEV of the 1PPS output.

So, it does not matter whether PPS or 100 Hz are used, it is a question
of the loop time constant only, which must be the same for both.

Best regards
Ulrich

> -----Ursprungliche Nachricht-----
> Von: time-nuts-bounces at febo.com 
> [mailto:time-nuts-bounces at febo.com] Im Auftrag von WarrenS
> Gesendet: Samstag, 6. Dezember 2008 15:57
> An: Discussion of precise time and frequency measurement
> Betreff: [time-nuts] Analog or Digital GPSDO?
> 
> 
> 
> Here is a posting meant to start a debate between open minded 
> freq-nuts. It is inspired by  Tom's latest posting  at 
http://www.leapsecond.com/pages/m12-adev/

All else being equal, Tom's data says to me that a simple analog front
end design when 
combined with a microprocessor  is able to provide a better performing
GPSDO 
than any digital only unit that is using just the 1PPS. 
It would appear that the analog front end can be as good and even better

than using the sawtooth correction data.

I may be a bit pregidous toward analog because I have been using 
analog only sub ns tracking of the GPS error signal for a long time.

What analog or digital can not address is any of  the issues concerning
non carrier phase receiver limitations. 
so I'd like to assume for this discussion that the GPSDO is using a
Motorola Oncore type 
of receiver with position hold capability.

A different but related question is, does or would using some form of
waas help a GPSDO?

Have fun with it,
WarrenS



_______________________________________________
time-nuts mailing list -- time-nuts at febo.com
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
-------------- next part --------------
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From warrensjmail-one at yahoo.com  Sat Dec  6 18:39:12 2008
From: warrensjmail-one at yahoo.com (WarrenS)
Date: Sat, 6 Dec 2008 10:39:12 -0800
Subject: [time-nuts] M12 100 Hz vs. 1PPS measurements
References: <D0C509E08EA542ACAB23B9B8AB4EF782@athlon>
Message-ID: <00c901c957d1$ef8238c0$6401a8c0@WSOffice>

Ulrich

Thanks, I'd forgot about that, I'll certainly check it out better this time.
The PSR10 being a Rb and not a OCXO, I would expect the best type of tracking filter used there to be somewhat different, and I mean in more ways than  just a longer time constant. Last I looked, I  thought that I saw was that they just set their simple filter to about 20 hrs.

WarrenS
**************
----- Original Message ----- 
From: "Ulrich Bangert" <df6jb at ulrich-bangert.de>
To: "'Discussion of precise time and frequency measurement'" <time-nuts at febo.com>
Sent: Saturday, December 06, 2008 9:06 AM
Subject: Re: [time-nuts] M12 100 Hz vs. 1PPS measurements


> Warren,
> 
> if you consider Stanford Research as a producer of a "better GPSDO" you
> can download their PRS10 manual from their web pages. It contains all
> the math that you are asking for.
> 
> Best regards
> Ulrich
> 
>> -----Ursprungliche Nachricht-----
>> Von: time-nuts-bounces at febo.com 
>> [mailto:time-nuts-bounces at febo.com] Im Auftrag von WarrenS
>> Gesendet: Samstag, 6. Dezember 2008 16:04
>> An: Discussion of precise time and frequency measurement
>> Betreff: Re: [time-nuts] M12 100 Hz vs. 1PPS measurements
>> 
>> 
>> 
>> Tom, 
>> This is great work and Information to see.
>> I do think that this will inspire, and make if not a giant 
>> leap, at least a small step to better GPSDO performance. 
>> 
>> 1st question:
>> Does anyone have or can they tell me where to get a copy of 
>> the actual raw data Tom used for these plots? 
>> http://www.leapsecond.com/pages/m12-adev/
>> 
>> The Link on his leapsecond site to the raw data seems to be 
>> missing. www.LeapSecond.com/logs/ - Logbook and raw data (ask) 
>> A request to Tom, so far has gone unanswered.
>> 
>> 2nd question 
>> Can anyone provide me with the filter formula or algorithm or 
>> any information 
>> regarding that is used by any of the better GPSDO units to 
>> calculate the ECV 
>> Dac output voltage.
>> 
>> I know about the simple basic 1st order averaging  filter 
>> used in some of the units, 
>> and the even more basic but effective over under check to 
>> increment / decrement 
>> an accumulator.  BUT it would seem to me there has got to be 
>> filters that give much 
>> better result than either of these available and being used out there.
>> 
>> Allan deviation (ADEV) and Modified Allan deviation (MDEV) 
>> http://www.mail-archive.com/time-nuts at febo.com/msg07211.html
>> 
>> 
>> 
>> 
>> I'm looking for just the basic formula used to process the 
>> phase error data before 
>> being applied to the DAC. I am not looking for anything 
>> secrete or with all the extra 
>> things some use to verify that the data is valid or 
>> appropriate before being applied 
>> or thrown away.
>> 
>> Thanks, for any information you can provide me.
>> WarrenS
>> 
>> **********************
>> 
>> 
>> ----- Original Message ----- 
>> From: "Tom Van Baak" <tvb at LeapSecond.com>
>> To: "Discussion of precise time and frequency measurement" 
>> <time-nuts at febo.com>
>> Sent: Friday, December 05, 2008 12:32 AM
>> Subject: [time-nuts] M12 100 Hz vs. 1PPS measurements
>> 
>> 
>> >I know a number of you have been waiting for the results of  
>> this M12 
>> >experiment. I compared the performance of a 100 Hz  output 
>> vs. a 1PPS 
>> >output vs. a 1PPS with sawtooth correction.
>> > 
>> > http://www.leapsecond.com/pages/m12-adev/
>> > 
>> > I think it came out quite well and it may surprise some of you.
>> > 
>> > /tvb
>> > 
>> > 
>> > 
>> > 
>> >
>> 
>> _______________________________________________
>> time-nuts mailing list -- time-nuts at febo.com
>> To unsubscribe, go to 
>> https://www.febo.com/cgi-> bin/mailman/listinfo/time-nuts
>> and 
>> follow the instructions there.
>> 
> 
> 
> 
>


From warrensjmail-one at yahoo.com  Sat Dec  6 18:47:07 2008
From: warrensjmail-one at yahoo.com (WarrenS)
Date: Sat, 6 Dec 2008 10:47:07 -0800
Subject: [time-nuts] Analog or Digital GPSDO?
References: <707DEF0799624FF988F7B5D4CC5EF23F@athlon>
Message-ID: <00d001c957d3$0a695140$6401a8c0@WSOffice>


>Q) Can you explain again why you are thinking this? 

A) Yes, Short answer is I do not think Tom's graph's have finished analyzing the data.
As soon as I can get a copy of the raw data so that I can check out my claims in a simulator, I'll show you why I say that.

WarrenS

********************
----- Original Message ----- 
From: "Ulrich Bangert" <df6jb at ulrich-bangert.de>
To: "'Discussion of precise time and frequency measurement'" <time-nuts at febo.com>
Sent: Saturday, December 06, 2008 9:23 AM
Subject: Re: [time-nuts] Analog or Digital GPSDO?


> Warren,
> 
> I may be teriible wrong but I understand Tom and his data so that PPS
> and 100 Hz have the SAME performance (what I had expected) with the PPS
> being able to be improved by the sawtooth correction. Attached are some
> seconds of data from my GPSDO which second Tom's measurements as far as
> the PPS is concerned.
> 
>> All else being equal, Tom's data says to me that a simple analog front
> end design when 
>> combined with a microprocessor  is able to provide a better performing
> GPSDO 
>> than any digital only unit that is using just the 1PPS.
> 
> Can you explain again why you are thinking this? Tom's claim is:
> 
> For all tau beyond 1 second, the ADEV of the 100 Hz output exactly
> matches the ADEV of the 1PPS output.
> 
> So, it does not matter whether PPS or 100 Hz are used, it is a question
> of the loop time constant only, which must be the same for both.
> 
> Best regards
> Ulrich
> 
>> -----Ursprungliche Nachricht-----
>> Von: time-nuts-bounces at febo.com 
>> [mailto:time-nuts-bounces at febo.com] Im Auftrag von WarrenS
>> Gesendet: Samstag, 6. Dezember 2008 15:57
>> An: Discussion of precise time and frequency measurement
>> Betreff: [time-nuts] Analog or Digital GPSDO?
>> 
>> 
>> 
>> Here is a posting meant to start a debate between open minded 
>> freq-nuts. It is inspired by  Tom's latest posting  at 
> http://www.leapsecond.com/pages/m12-adev/
> 
> All else being equal, Tom's data says to me that a simple analog front
> end design when 
> combined with a microprocessor  is able to provide a better performing
> GPSDO 
> than any digital only unit that is using just the 1PPS. 
> It would appear that the analog front end can be as good and even better
> 
> than using the sawtooth correction data.
> 
> I may be a bit pregidous toward analog because I have been using 
> analog only sub ns tracking of the GPS error signal for a long time.
> 
> What analog or digital can not address is any of  the issues concerning
> non carrier phase receiver limitations. 
> so I'd like to assume for this discussion that the GPSDO is using a
> Motorola Oncore type 
> of receiver with position hold capability.
> 
> A different but related question is, does or would using some form of
> waas help a GPSDO?
> 
> Have fun with it,
> WarrenS
> 
> 
> 
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>


From tvb at LeapSecond.com  Sat Dec  6 19:08:11 2008
From: tvb at LeapSecond.com (Tom Van Baak)
Date: Sat, 6 Dec 2008 11:08:11 -0800
Subject: [time-nuts] M12 100 Hz vs. 1PPS measurements
References: <F3D4DB1872C84B8AAD666A0DFBBB5BC0@pc52>
	<008101c957b3$d3d7d670$6401a8c0@WSOffice>
Message-ID: <32EACD040BC94A3985DFC60FE6406879@pc52>

> 1st question:
> Does anyone have or can they tell me where to get a copy
> of the actual raw data Tom used for these plots?
> http://www.leapsecond.com/pages/m12-adev/

I'm out of town at the moment and so can't yet address all
the other comments and questions about the M12. The raw
data: log2367.dat.gz, log2385.dat.gz, log2387.dat.gz under
that same URL.

/tvb



From bruce.griffiths at xtra.co.nz  Sat Dec  6 20:18:53 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Sun, 07 Dec 2008 09:18:53 +1300
Subject: [time-nuts] M12 100 Hz vs. 1PPS measurements
In-Reply-To: <008101c957b3$d3d7d670$6401a8c0@WSOffice>
References: <F3D4DB1872C84B8AAD666A0DFBBB5BC0@pc52>
	<008101c957b3$d3d7d670$6401a8c0@WSOffice>
Message-ID: <493ADE2D.30500@xtra.co.nz>

WarrenS wrote:
> Tom, 
> This is great work and Information to see.
> I do think that this will inspire, and make if not a giant leap, at least a small step to better GPSDO performance. 
>
> 1st question:
> Does anyone have or can they tell me where to get a copy of the actual raw data Tom used for these plots?
> http://www.leapsecond.com/pages/m12-adev/
>
> The Link on his leapsecond site to the raw data seems to be missing.
> www.LeapSecond.com/logs/ - Logbook and raw data (ask) 
> A request to Tom, so far has gone unanswered.
>
> 2nd question 
> Can anyone provide me with the filter formula or algorithm or any information 
> regarding that is used by any of the better GPSDO units to calculate the ECV 
> Dac output voltage.
>
> I know about the simple basic 1st order averaging  filter used in some of the units, 
> and the even more basic but effective over under check to increment / decrement 
> an accumulator.  BUT it would seem to me there has got to be filters that give much 
> better result than either of these available and being used out there.
>
> Allan deviation (ADEV) and Modified Allan deviation (MDEV) 
> http://www.mail-archive.com/time-nuts at febo.com/msg07211.html
>
>
>
>
> I'm looking for just the basic formula used to process the phase error data before 
> being applied to the DAC. I am not looking for anything secrete or with all the extra 
> things some use to verify that the data is valid or appropriate before being applied 
> or thrown away.
>
> Thanks, for any information you can provide me.
> WarrenS
>
>   
Warren

The better GPSDOs also model OCXO, aging, tempco, and other effects such
as the effect of oven current (can be significant when Kelvin
connections to the EFC aren't available and the OCXO heater and EFC
share a common ground pin). Correction for these effects is important
when the GPSDO enters hold mode for any length of time.

A Kalman filter is probably more effective for such applications, given
sufficient training time, than a standard digital phase lock loop with
or without additional filtering.

Bruce


From sar10538 at gmail.com  Sun Dec  7 00:54:35 2008
From: sar10538 at gmail.com (Steve Rooke)
Date: Sun, 7 Dec 2008 13:54:35 +1300
Subject: [time-nuts] position determination over short distance
In-Reply-To: <cd5103e0811231834o482e124s4359d5ee2135c6ce@mail.gmail.com>
References: <cd5103e0811231834o482e124s4359d5ee2135c6ce@mail.gmail.com>
Message-ID: <1231b6a80812061654m8056e9fw8788eeeedcd090e4@mail.gmail.com>

Hi Rick,

Sorry for the late reply but I accidentally stumbled upon this device
and thought about your application. I'm not sure it will be accurate
enough to meet your requirements but if you choose the part of the
curve with the steepest slope you might just achieve the 1mm you need
and at a very inexpensive price.

Sharp GP2Y0A21YK0F Distance Sensor

73,
Steve

2008/11/24 Rick Harold <rickharold at gmail.com>:
> All,
>
> I'm planning doing some experiments in distance measurement.  They don't
> deal with atomic time directly but with extreme short periods of time.
>
> I need to determine the position of a instrument with a 1mm accuracy or
> less.
> The instrument is not connected to a mechanical device but is separate &
> independent.
> The surface which the instrument is positioned on is close to the size of a
> 11"x11" square.
>
> I thought of using 1 RF transmitters (not sure of freq) on bottom of the
> device near the surface.
> The surface would have RF receivers on 3 or 4 edges/corners to receive the
> signal.
>
> If each of the receivers positions are known and they then send a signal to
> a central circuit (again known positions) how can I differentiate the time
> of arrival
> at the central location?  Does anybody know of a circuit/chip or system
> which would determine the time 'difference'.
> Obviously this is used to triangulate the position of the instrument.
> Light travels 1 mm in ~3.3 picoseconds so I would suspect the differentiator
> would have to have that or better resolution.
> It could also use some proportional method to extrapolate the position since
> the surface has a fixed size.
>
> Any ideas/thoughts?
>
> Thanks in advance.
>
> Rick Harold
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>



-- 
Steve Rooke - ZL3TUV & G8KVD
Omnium finis imminet


From stans at sycard.com  Sun Dec  7 16:40:32 2008
From: stans at sycard.com (Stan Searing)
Date: Sun, 7 Dec 2008 08:40:32 -0800
Subject: [time-nuts] Odetics 325/425 owners, rejoice!
In-Reply-To: <200812021931020879.158F931B@192.168.42.129>
Message-ID: <000c01c9588a$89f02e40$6e00a8c0@dell>

I have an Odetics 325 that I'll make available to a fellow time-nut
for what I paid.  I got it recently at auction for $56 and it looks like the
oscillator was removed.  There was a note on it that it has a defective
LCD (or OCD?).  I didn't notice any signs that anything besides the
oscillator is missing.  It does have the Magellan OEM5000 receiver.

Please email off-list if interested.
First priority would be to someone who can pick it up
in San Jose or Mountain View, CA.

Stan



-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of Bruce Lane
Sent: Tuesday, December 02, 2008 7:31 PM
To: time-nuts at febo.com
Subject: [time-nuts] Odetics 325/425 owners, rejoice!

Fellow clock-tickers,

	Thanks to the generous assistance of a customer service rep at
Magellan Navigation, I have received a full .PDF manual covering the
Magellan OEM5000 receiver module used in many of the Odetics SatSync 325 and
425 GPS clock units.

	This manual contains full details on both ASCII and Magellan Binary
outputs from the receiver, including that previously-elusive PMGLK sentence
that was driving me nuts.

	The information in that manual, combined with a bit of hardware
ingenuity in the microcontroller world and the Odetics equipment manual,
should be enough to produce a hardware translation device which will
(hopefully) allow the use of a standard (and much more readily available)
NMEA-output receiver module. That's going to be a long-term project for me
in the coming year.

	Anyone who wants to try and beat me to it is, of course, welcome.
;-)

	The manual may be found on the Blue Feather FTP archive.

	ftp.bluefeathertech.com

	Sign in as user ftp and the password can be anything you want
(though I prefer an E-mail for logging purposes).

	The path is /electronics/radio/GPS/receivers/OEM/Magellan/oem5000

	The file name is OEM5K.pdf

	Happy reading.


-=-=-=-=-=-=-=-=-=-=-=-
Bruce Lane, Owner & Head Hardware Heavy,
Blue Feather Technologies -- http://www.bluefeathertech.com
kyrrin (at) bluefeathertech do/t c=o=m
"Quid Malmborg in Plano..."


_______________________________________________
time-nuts mailing list -- time-nuts at febo.com
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.




From technoid_tim at comcast.net  Sun Dec  7 18:50:39 2008
From: technoid_tim at comcast.net (Tim Schulz)
Date: Sun, 07 Dec 2008 11:50:39 -0700
Subject: [time-nuts] Ion pump PS voltage multiplier schematic
Message-ID: <493C1AFF.2060404@comcast.net>

Greetings again...  I guess I would like to ask Corby for the schematics 
of the multiplier at his convenience.  I appreciate everybody's 
suggestions on how to dissolve the potting material of the module.  I 
did attack it yesterday with a heat gun which actually worked pretty 
will.  I had it clamped in a metal jawed panavise, and when you get it 
hot with the heat gun, the epoxy softens to the consistency of a hard 
rubber eraser.  I then used an electricians knife to pick away at the 
potting.  I managed to uncover the 3 caps and the remains of a diode.  
The diode case softened up with the potting material and all that was 
left was the leads and some of the innards.  I left it about 1/2 
uncovered.  One has to be more precise at the picking away of the 
potting material than I was to preserve components,  but at least you 
are not using a bunch high powered and hazardous solvents.  My 
substitute HV PS is waiting for me at the post office, so I might be 
able to try that tomorrow if I get time...  Thanks again, tim


From richiem at hughes.net  Sun Dec  7 23:18:14 2008
From: richiem at hughes.net (Richard Moore)
Date: Sun, 7 Dec 2008 15:18:14 -0800
Subject: [time-nuts] Ulrich, re PRS10
In-Reply-To: <mailman.3.1228651201.20573.time-nuts@febo.com>
References: <mailman.3.1228651201.20573.time-nuts@febo.com>
Message-ID: <F5D7E58A-7BA0-4E34-AC74-7737CE3D54E9@hughes.net>

Ulrich, at the Stanford site, I found the manual for the PRS10 --  
thanks for the link. The manual has very thorough descriptions of the  
circuits, but doesn't have schematics -- which I thought was kind of  
odd. Do you have schematics or does any one here?

Dick Moore


From besten at gmail.com  Sun Dec  7 23:24:43 2008
From: besten at gmail.com (Remco den Besten)
Date: Mon, 8 Dec 2008 00:24:43 +0100
Subject: [time-nuts] thermostated 14.31818 MHz
Message-ID: <000b01c958c2$fde542d0$1343892c@kalium>

In order to minimise the temperature dependency of my system clock I made a 
thermostate with an uA723,
and soldered it on the 14.31818 MHz reference crystal of the system clock 
PLL.

The temperature of the thermostate converges to approx. 50 degr C and the 
results are really good for such a simple
solution. My jitter decreased with an order (approx 10 times). With FreeBSD 
I have 'pps stabilities' of
0.001 - 0.003 ppm, whereas 0.020 - 0.050 ppm was observed without the 
thermostate.
The PLL offset remains within +/- 1 usec most of the time for my ntp server 
ntp.remco.org.

For graphs: see http://remco.org/difference.php

Remco








From brooke at pacific.net  Sun Dec  7 23:38:59 2008
From: brooke at pacific.net (Brooke Clarke)
Date: Sun, 07 Dec 2008 15:38:59 -0800
Subject: [time-nuts] Ulrich, re PRS10
In-Reply-To: <F5D7E58A-7BA0-4E34-AC74-7737CE3D54E9@hughes.net>
References: <mailman.3.1228651201.20573.time-nuts@febo.com>
	<F5D7E58A-7BA0-4E34-AC74-7737CE3D54E9@hughes.net>
Message-ID: <493C5E93.5070204@pacific.net>

Hi Dick:

SRS does not put their schematics on line.  For that you need to buy the hard 
copy.  I took a tour when I picked up my PSR10 given by the head man.  It turns 
out he has a physics background as do most of the technical people there.  So 
their products have, IMHO, more bang for the buck than competitive products.

Have Fun,

Brooke Clarke
http://www.prc68.com

Richard Moore wrote:
> Ulrich, at the Stanford site, I found the manual for the PRS10 --  
> thanks for the link. The manual has very thorough descriptions of the  
> circuits, but doesn't have schematics -- which I thought was kind of  
> odd. Do you have schematics or does any one here?
> 
> Dick Moore
> 
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
> 


From tvb at LeapSecond.com  Mon Dec  8 02:52:32 2008
From: tvb at LeapSecond.com (Tom Van Baak)
Date: Sun, 7 Dec 2008 18:52:32 -0800
Subject: [time-nuts] M12 100 Hz vs. 1PPS measurements
References: <49844.1228467965@uk2.net>
Message-ID: <349AFE062799479DA9F8B33D14C077D9@pc52>

> Tom,
>
> Interesting results - thank you.  Is there a small problem with the
> graph plotting routine though?  On the left of the 100Hz plots, at
> some tau there are two points above each other (5 + 7 * 10^-2),
> and other tau have no data points (4, 6, + 8 * 10^-2).
>
> Peter

Right, those first few points do look off by one. Another clue was
that at tau[0], MDEV must always equal ADEV. The bug is fixed
and I refreshed the plots for you. Good eye. Thanks.

http://www.leapsecond.com/pages/m12-adev/

> Nice and useful....
>
> What about Jupiter's 10 KHz output under same conditions?
>
> Predrag Dukic

Yes, a Jupiter is next on the list. My expectation in all these cases
is that more pulses per solution does not give any additional timing
accuracy. The inexpensive OEM GPS receivers that we typically
use compute one solution per second so that defines a certain limit.

You could say averaging solutions over time (minutes to hours) is
what gives greater precision to a GPSDO, not averaging pulses
(milliseconds to seconds).

However, that's not to say more pulses can't be useful in alternative
GPSDO designs. One that comes to mind is James Miller (G3RUH)
Jupiter-based GPSDO which, in spite of its extreme simplicity, has
great performance. See http://www.leapsecond.com/pages/gpsdo/

/tvb



From dansawyer at earthlink.net  Mon Dec  8 04:58:43 2008
From: dansawyer at earthlink.net (Dan Sawyer)
Date: Sun, 07 Dec 2008 20:58:43 -0800
Subject: [time-nuts] repairing an HP 5248M crystal oscillator
In-Reply-To: <000b01c958c2$fde542d0$1343892c@kalium>
References: <000b01c958c2$fde542d0$1343892c@kalium>
Message-ID: <493CA983.6090102@earthlink.net>

The oven on a 5248M is not working properly. I have the schematics for  
48L however not the M. Does anyone have a schematic for an M model? The 
oven light comes on and dims, however the instrument appears to be 
temperature sensitive. I believe this is a double oven unit.

Thanks, Dan


From service at frequencystandards.com  Mon Dec  8 04:50:51 2008
From: service at frequencystandards.com (service at frequencystandards.com)
Date: Sun, 7 Dec 2008 23:50:51 -0500 (EST)
Subject: [time-nuts] An interesting clock
Message-ID: <2824.75.163.188.30.1228711851.squirrel@www.frequencystandards.com>

Found an interesting clock. I don't recall seeing it on here before. I
have no idea how accurate the statistics it shows are. Kind of interesting
though.
http://www.poodwaddle.com/worldclock.swf
Chuck Norton



From df6jb at ulrich-bangert.de  Mon Dec  8 09:09:10 2008
From: df6jb at ulrich-bangert.de (Ulrich Bangert)
Date: Mon, 8 Dec 2008 10:09:10 +0100
Subject: [time-nuts] Ulrich, re PRS10
In-Reply-To: <F5D7E58A-7BA0-4E34-AC74-7737CE3D54E9@hughes.net>
Message-ID: <065F1DE3A9354B3E97450CAE23915CA8@athlon>

Dick,

sorry I do not have schematics. I was refering to the manual because of
the well explained math of the regulation loop.

Best regards
Ulrich

> -----Ursprungliche Nachricht-----
> Von: time-nuts-bounces at febo.com 
> [mailto:time-nuts-bounces at febo.com] Im Auftrag von Richard Moore
> Gesendet: Montag, 8. Dezember 2008 00:18
> An: time-nuts at febo.com
> Betreff: Re: [time-nuts] Ulrich, re PRS10
> 
> 
> Ulrich, at the Stanford site, I found the manual for the PRS10 --  
> thanks for the link. The manual has very thorough 
> descriptions of the  
> circuits, but doesn't have schematics -- which I thought was kind of  
> odd. Do you have schematics or does any one here?
> 
> Dick Moore
> 
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to 
> https://www.febo.com/cgi-> bin/mailman/listinfo/time-nuts
> and 
> follow the instructions there.
> 



From df6jb at ulrich-bangert.de  Mon Dec  8 09:13:16 2008
From: df6jb at ulrich-bangert.de (Ulrich Bangert)
Date: Mon, 8 Dec 2008 10:13:16 +0100
Subject: [time-nuts] thermostated 14.31818 MHz
In-Reply-To: <000b01c958c2$fde542d0$1343892c@kalium>
Message-ID: <0A265CAFD0BC4CED96448D427CB27381@athlon>

For those that are interested in this method:

A read to go crystal heater can be bought from Kuhne Electronics. Look
for

http://www.kuhne-electronic.de/en/shop/155_Crystal_Heater

Best regards
Ulrich Bangert

> -----Ursprungliche Nachricht-----
> Von: time-nuts-bounces at febo.com 
> [mailto:time-nuts-bounces at febo.com] Im Auftrag von Remco den Besten
> Gesendet: Montag, 8. Dezember 2008 00:25
> An: linuxpps at ml.enneenne.com; Discussion of precise time and 
> frequency measurement
> Betreff: [time-nuts] thermostated 14.31818 MHz
> 
> 
> In order to minimise the temperature dependency of my system 
> clock I made a 
> thermostate with an uA723,
> and soldered it on the 14.31818 MHz reference crystal of the 
> system clock 
> PLL.
> 
> The temperature of the thermostate converges to approx. 50 
> degr C and the 
> results are really good for such a simple
> solution. My jitter decreased with an order (approx 10 
> times). With FreeBSD 
> I have 'pps stabilities' of
> 0.001 - 0.003 ppm, whereas 0.020 - 0.050 ppm was observed without the 
> thermostate.
> The PLL offset remains within +/- 1 usec most of the time for 
> my ntp server 
> ntp.remco.org.
> 
> For graphs: see http://remco.org/difference.php
> 
> Remco
> 
> 
> 
> 
> 
> 
> 
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to 
> https://www.febo.com/cgi-> bin/mailman/listinfo/time-nuts
> and 
> follow the instructions there.
> 



From phk at phk.freebsd.dk  Mon Dec  8 10:21:45 2008
From: phk at phk.freebsd.dk (Poul-Henning Kamp)
Date: Mon, 08 Dec 2008 10:21:45 +0000
Subject: [time-nuts] M12 100 Hz vs. 1PPS measurements
In-Reply-To: Your message of "Sun, 07 Dec 2008 18:52:32 PST."
	<349AFE062799479DA9F8B33D14C077D9@pc52> 
Message-ID: <44880.1228731705@critter.freebsd.dk>

In message <349AFE062799479DA9F8B33D14C077D9 at pc52>, "Tom Van Baak" writes:

>> What about Jupiter's 10 KHz output under same conditions?
>>
>Yes, a Jupiter is next on the list. My expectation in all these cases
>is that more pulses per solution does not give any additional timing
>accuracy.

That depends what clock-frequency is used to generate the pulses.

If that frequency is close to integer Hz, then it won't help much
and we get all the usual trouble with "hanging bridges".

If it is close to, but not quite a low modulus to 1Hz, N.33337 Hz
for instance, it will help, because the 10.000 pulses will sample
the "real" value and the average of them will give a sqrt(9999) ~=
100 times better resolution.


-- 
Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk at FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.


From masondg44 at comcast.net  Mon Dec  8 17:04:39 2008
From: masondg44 at comcast.net (Dave M)
Date: Mon, 8 Dec 2008 12:04:39 -0500
Subject: [time-nuts] repairing an HP 5248M crystal oscillator
References: <mailman.196.1228727600.2499.time-nuts@febo.com>
Message-ID: <930A79CBE5DF4164BF56E267A4639F81@DELL2350>

You can get an excellent PDF copy of the 5245M manual from Artek (http://artekmed.startlogic.com/page3.html) for only $10 US.  They do good work there.

-- 
Dave M

Life is like a roll of toilet paper; the closer it gets to the end, the faster it goes. 

  The oven on a 5248M is not working properly. I have the schematics for  
  48L however not the M. Does anyone have a schematic for an M model? The 
  oven light comes on and dims, however the instrument appears to be 
  temperature sensitive. I believe this is a double oven unit.

  Thanks, Dan

From True-Cal at swbell.net  Mon Dec  8 18:00:07 2008
From: True-Cal at swbell.net (Don @ True-Cal)
Date: Mon, 8 Dec 2008 12:00:07 -0600
Subject: [time-nuts] SR620 Manual
References: <065F1DE3A9354B3E97450CAE23915CA8@athlon>
Message-ID: <89853D241C8D41ADB0AA648D54FF6DE6@proxy>

Hi All,

As mentioned in these earlier threads, the Stanford site does not include schematics in their online manuals. I have the online version of the manual for my SR620 but would love to have the schematics. I am getting ready to install the low phase noise SC10 as the high stability reference oscillator option and would like to know exactly how the factory install is implemented. Does anyone have the schematic of full version manual to share? Alternatively, details of the reference oscillator option?

Thanks...
Don
  ----- Original Message ----- 
  From: Ulrich Bangert 
  To: 'Discussion of precise time and frequency measurement' 
  Sent: Monday, December 08, 2008 3:09 AM
  Subject: Re: [time-nuts] Ulrich, re PRS10


  Dick,

  sorry I do not have schematics. I was refering to the manual because of
  the well explained math of the regulation loop.

  Best regards
  Ulrich

  > -----Ursprungliche Nachricht-----
  > Von: time-nuts-bounces at febo.com 
  > [mailto:time-nuts-bounces at febo.com] Im Auftrag von Richard Moore
  > Gesendet: Montag, 8. Dezember 2008 00:18
  > An: time-nuts at febo.com
  > Betreff: Re: [time-nuts] Ulrich, re PRS10
  > 
  > 
  > Ulrich, at the Stanford site, I found the manual for the PRS10 --  
  > thanks for the link. The manual has very thorough 
  > descriptions of the  
  > circuits, but doesn't have schematics -- which I thought was kind of  
  > odd. Do you have schematics or does any one here?
  > 
  > Dick Moore
  > 
  > _______________________________________________
  > time-nuts mailing list -- time-nuts at febo.com
  > To unsubscribe, go to 
  > https://www.febo.com/cgi-> bin/mailman/listinfo/time-nuts
  > and 
  > follow the instructions there.
  > 


  _______________________________________________
  time-nuts mailing list -- time-nuts at febo.com
  To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
  and follow the instructions there.

From w1ksz at earthlink.net  Mon Dec  8 18:03:21 2008
From: w1ksz at earthlink.net (Richard W. Solomon)
Date: Mon, 8 Dec 2008 11:03:21 -0700 (GMT-07:00)
Subject: [time-nuts] SR620 Manual
Message-ID: <6288045.1228759401869.JavaMail.root@elwamui-rustique.atl.sa.earthlink.net>

They are not the only ones to guard the schematics as if they are
national treasures. TrueTime does it also. Very aggravating, as the
circuit design is not that unique. Just another way for those guys
to make an extra buck I guess.

73, Dick, W1KSZ

-----Original Message-----
>From: "Don @ True-Cal" <True-Cal at swbell.net>
>Sent: Dec 8, 2008 11:00 AM
>To: Discussion of precise time and frequency measurement <time-nuts at febo.com>
>Subject: [time-nuts] SR620 Manual
>
>Hi All,
>
>As mentioned in these earlier threads, the Stanford site does not include schematics in their online manuals. I have the online version of the manual for my SR620 but would love to have the schematics. I am getting ready to install the low phase noise SC10 as the high stability reference oscillator option and would like to know exactly how the factory install is implemented. Does anyone have the schematic of full version manual to share? Alternatively, details of the reference oscillator option?
>
>Thanks...
>Don
>  ----- Original Message ----- 
>  From: Ulrich Bangert 
>  To: 'Discussion of precise time and frequency measurement' 
>  Sent: Monday, December 08, 2008 3:09 AM
>  Subject: Re: [time-nuts] Ulrich, re PRS10
>
>
>  Dick,
>
>  sorry I do not have schematics. I was refering to the manual because of
>  the well explained math of the regulation loop.
>
>  Best regards
>  Ulrich
>
>  > -----Ursprungliche Nachricht-----
>  > Von: time-nuts-bounces at febo.com 
>  > [mailto:time-nuts-bounces at febo.com] Im Auftrag von Richard Moore
>  > Gesendet: Montag, 8. Dezember 2008 00:18
>  > An: time-nuts at febo.com
>  > Betreff: Re: [time-nuts] Ulrich, re PRS10
>  > 
>  > 
>  > Ulrich, at the Stanford site, I found the manual for the PRS10 --  
>  > thanks for the link. The manual has very thorough 
>  > descriptions of the  
>  > circuits, but doesn't have schematics -- which I thought was kind of  
>  > odd. Do you have schematics or does any one here?
>  > 
>  > Dick Moore
>  > 
>  > _______________________________________________
>  > time-nuts mailing list -- time-nuts at febo.com
>  > To unsubscribe, go to 
>  > https://www.febo.com/cgi-> bin/mailman/listinfo/time-nuts
>  > and 
>  > follow the instructions there.
>  > 
>
>
>  _______________________________________________
>  time-nuts mailing list -- time-nuts at febo.com
>  To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>  and follow the instructions there.
>_______________________________________________
>time-nuts mailing list -- time-nuts at febo.com
>To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>and follow the instructions there.



From magnus at rubidium.dyndns.org  Mon Dec  8 18:37:23 2008
From: magnus at rubidium.dyndns.org (Magnus Danielson)
Date: Mon, 08 Dec 2008 19:37:23 +0100
Subject: [time-nuts] SR620 Manual
In-Reply-To: <89853D241C8D41ADB0AA648D54FF6DE6@proxy>
References: <065F1DE3A9354B3E97450CAE23915CA8@athlon>
	<89853D241C8D41ADB0AA648D54FF6DE6@proxy>
Message-ID: <493D6963.4010604@rubidium.dyndns.org>

Don @ True-Cal skrev:
> Hi All,
> 
> As mentioned in these earlier threads, the Stanford site does not include
> schematics in their online manuals. I have the online version of the manual
> for my SR620 but would love to have the schematics. I am getting ready to
> install the low phase noise SC10 as the high stability reference oscillator
> option and would like to know exactly how the factory install is implemented.
> Does anyone have the schematic of full version manual to share?
> Alternatively, details of the reference oscillator option?

As it happends, I have my original hardcopy lying next to my computer 
and my SR620 with Option 01 installed just on top of my computer. I have 
a custom Wenzel oscillator in mine. By the looks of things, the SC10 
should fit right in. The only issue I see is the monitor signal which 
does not seem to be there on the SC10. It should be a few leads to 
solder in, move JUMPER 3 over and away you go. You also needs to replace 
some resistors in the PLL loop for the locking of the 10 MHz to external 
reference. All in all, it should be fairly doable.

Cheers,
Magnus


From magnus at rubidium.dyndns.org  Mon Dec  8 18:45:21 2008
From: magnus at rubidium.dyndns.org (Magnus Danielson)
Date: Mon, 08 Dec 2008 19:45:21 +0100
Subject: [time-nuts] SR620 Manual
In-Reply-To: <6288045.1228759401869.JavaMail.root@elwamui-rustique.atl.sa.earthlink.net>
References: <6288045.1228759401869.JavaMail.root@elwamui-rustique.atl.sa.earthlink.net>
Message-ID: <493D6B41.7080204@rubidium.dyndns.org>

Dear Richard,

Richard W. Solomon skrev:
> They are not the only ones to guard the schematics as if they are
> national treasures. TrueTime does it also. Very aggravating, as the
> circuit design is not that unique. Just another way for those guys
> to make an extra buck I guess.

Now I think you are a bit unfair here. I have a real hardcopy of the 
manual, and it contains the full schematics and is extremely readable.

You can buy one of these off Ebay, manual services or SRS themselfs for 
quite reasnoble money. Thus, the schematics IS obtainable.

There are some which do guard them as national treasury, but I don't 
think it is fair to say this about SRS. They just do not put them in the 
free for download PDFs, that's all.

There are those that does not seem to have much online, but are 
extremely helpfull in aiding repairs and maintainence. I agree it would 
be so much better if they would have an complete online manual archive, 
but not having that is not the same as keeping their claws around it as 
if it was a top secret document of the cold war level. There are many 
levels of support inbetween and in many cases you will find that pure 
effort to scan things and maintain the site is much more of a 
prohibiting factor than minds.

Then again, there are a few companies out there that DO think like that.

Cheers,
Magnus


From tractorb at ihug.co.nz  Mon Dec  8 19:23:57 2008
From: tractorb at ihug.co.nz (Dave Brown)
Date: Tue, 9 Dec 2008 08:23:57 +1300
Subject: [time-nuts] repairing an HP 5248M crystal oscillator
References: <mailman.196.1228727600.2499.time-nuts@febo.com>
	<930A79CBE5DF4164BF56E267A4639F81@DELL2350>
Message-ID: <207101c9596a$84cd9200$7900a8c0@athlon1200>

If the oven in the M version of the 5245 and the 5248 is the same then 
I have some notes here re pulling it apart etc. I have a 5245M and had 
to replace a buffer amp transistor in the oven some years ago.  The 
series regulator in the 'always on' power supply failed short and took 
it out - like the good little fast three legged fuse that it was.....
 I recommend that over voltage protection be added and a more rugged 
regulator pass transistor be fitted to the power supply while you have 
it on the bench, just in case. The 5248 supply may have these matters 
attended to- not sure.

DaveB, NZ

----- Original Message ----- 
From: "Dave M" <masondg44 at comcast.net>
To: <time-nuts at febo.com>
Sent: Tuesday, December 09, 2008 6:04 AM
Subject: Re: [time-nuts] repairing an HP 5248M crystal oscillator


> You can get an excellent PDF copy of the 5245M manual from Artek 
> (http://artekmed.startlogic.com/page3.html) for only $10 US.  They 
> do good work there.
>
> -- 
> Dave M
>
> Life is like a roll of toilet paper; the closer it gets to the end, 
> the faster it goes.
>
>  The oven on a 5248M is not working properly. I have the schematics 
> for
>  48L however not the M. Does anyone have a schematic for an M model? 
> The
>  oven light comes on and dims, however the instrument appears to be
>  temperature sensitive. I believe this is a double oven unit.
>
>  Thanks, Dan
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to 
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.


--------------------------------------------------------------------------------



No virus found in this incoming message.
Checked by AVG - http://www.avg.com
Version: 8.0.176 / Virus Database: 270.9.15/1835 - Release Date: 
7/12/2008 16:56



From hbonhorst at freenet.de  Mon Dec  8 20:15:16 2008
From: hbonhorst at freenet.de (v. Bonhorst)
Date: Mon, 8 Dec 2008 21:15:16 +0100
Subject: [time-nuts] repairing an HP 5248M crystal oscillator
In-Reply-To: <207101c9596a$84cd9200$7900a8c0@athlon1200>
References: <mailman.196.1228727600.2499.time-nuts@febo.com><930A79CBE5DF4164BF56E267A4639F81@DELL2350>
	<207101c9596a$84cd9200$7900a8c0@athlon1200>
Message-ID: <B6FE9F3A20054DE49C9C4B9297E25128@Shuttle>

The oven used for the M models is a 00105-xxxxx. Diagrams can be found as
part of the HP 105 manual. This oven was used as well for 5061A and 5065A
standards. Tom got a 5061 manual on his page. The first thing to check is
the 110 V preheater. If you need further assistance contact me offline.

Hubert
DB7ME 

-----Urspr?ngliche Nachricht-----
Von: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] Im
Auftrag von Dave Brown
Gesendet: Montag, 8. Dezember 2008 20:24
An: Discussion of precise time and frequency measurement
Betreff: [!! SPAM] Re: [time-nuts] repairing an HP 5248M crystal oscillator

If the oven in the M version of the 5245 and the 5248 is the same then 
I have some notes here re pulling it apart etc. I have a 5245M and had 
to replace a buffer amp transistor in the oven some years ago.  The 
series regulator in the 'always on' power supply failed short and took 
it out - like the good little fast three legged fuse that it was.....
 I recommend that over voltage protection be added and a more rugged 
regulator pass transistor be fitted to the power supply while you have 
it on the bench, just in case. The 5248 supply may have these matters 
attended to- not sure.

DaveB, NZ

----- Original Message ----- 
From: "Dave M" <masondg44 at comcast.net>
To: <time-nuts at febo.com>
Sent: Tuesday, December 09, 2008 6:04 AM
Subject: Re: [time-nuts] repairing an HP 5248M crystal oscillator


> You can get an excellent PDF copy of the 5245M manual from Artek 
> (http://artekmed.startlogic.com/page3.html) for only $10 US.  They 
> do good work there.
>
> -- 
> Dave M
>
> Life is like a roll of toilet paper; the closer it gets to the end, 
> the faster it goes.
>
>  The oven on a 5248M is not working properly. I have the schematics 
> for
>  48L however not the M. Does anyone have a schematic for an M model? 
> The
>  oven light comes on and dims, however the instrument appears to be
>  temperature sensitive. I believe this is a double oven unit.
>
>  Thanks, Dan
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to 
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.


----------------------------------------------------------------------------
----



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Checked by AVG - http://www.avg.com
Version: 8.0.176 / Virus Database: 270.9.15/1835 - Release Date: 
7/12/2008 16:56


_______________________________________________
time-nuts mailing list -- time-nuts at febo.com
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.



From gwinn at raytheon.com  Mon Dec  8 22:01:53 2008
From: gwinn at raytheon.com (Joseph M Gwinn)
Date: Mon, 8 Dec 2008 17:01:53 -0500
Subject: [time-nuts] Sub Pico Second Phase logger
In-Reply-To: <01f801c95693$85b913d0$6401a8c0@WSOffice>
Message-ID: <OFB7BC2CE2.9C55EBF4-ON85257519.00787791-85257519.00790527@mck.us.ray.com>

People used passive mixers driving electromechanical stripchart recorders 
to compare high-stability oscillators in the good old days.

One assumes that there is a purely analog approach to measurement of 
picosecond changes in delay at 10 MHz using a single oscillator, but I 
have not seen any methods described, probably because the relevant 
articles appeared many decades ago.

Can anyone suggest some articles to read?

Thanks,

Joe Gwinn

time-nuts-bounces at febo.com wrote on 12/04/2008 11:39:55 PM:

> 
> Building a Sub Pico Second phase detector.
> 
> I was inspired to build this project yesterday after 
> downloading and trying 
> Ulrich Bangert's 'DF6JB's Plotter 2008-10-10' program with its 
> unbelievable 
>  flexible user Interface capabilities.  http://www.ulrich-
> bangert.de/html/downloads.html
> What I needed was a Phase detector to use with the 'Plotter' program.
> I decided to see what it takes to build a simple high 
> resolution, sub Pico second, 
> linear phase logging detector using standard off the self IC's.
> 
> How If works:
> The 5 or 10 MHz signal to be measured is buffered and toggles a 
> synchronous divide by two or four FF. This gives a 2.5MHz 
> square wave and its complement. 
> Each side of the flip-flop connects to two of four XOR gates.
> 
> The 10 MHz reference signal goes thru a matching buffer and 
> then to a pair of synchronous 
> Flip-Flops that provide a zero and a 90 deg phase shifted 2.
> 5MHz square wave.
> Each of these goes to two inputs of the XOR gates. The four XOR
> phase detectors 
> are connected to give four PWM type XOR phase detectors, each 
> separate by 90 deg.
> 
> Each of the four XOR outputs are buffered by a cmos buffer gate 
> that has been powered by it's own 5 volt reference supply.
> The buffer outputs then goes thru a multi-stage passive RC 
> filter set up to 
> give two differential filtered PASSIVE + - 5 volt outputs, 90 deg apart.
> 
> Logging  Data:
> For the most flexible and best  performance, two differential 
> 16 plus bit ADC's 
> should be used, each connected to one of the dual differential 
> Phase detectors.
> After using the appropriate Analog RC filters, oversampling, 
> digital filters, and digital 
> scaling, you get a file with a single column of data to feed 
> "Plotter" the phase 
> difference of the two 10 MHz signals. 
> 
> The Data scaling and processing:
> For simple controlled short term or lower resolution data 
> taking a PC Multimeter, 
> if it is isolated so that you can use it differentially will 
> work.  If not you need to add a differential amp. 
> For best performance, process the phase data from the two 
> differential phase detectors 
> through two identical digital filter algorithms.
> Doing this real time on a PC or after all the data is recorder 
> on a XL spread sheet both work for me.
> Besides the filtering, the spread sheet or PC needs to also do 
> the linearizing by 
> ( K1* Phase1_Data) + (K2 * Phase2_Data). 
> K1 and K2 are the sine value of their respective Phase detectors.
> 
> One of the several tricks to why this can provide orders of 
> magnitude better 
> performance than is generally obtained from similar type phase detectors 

> is because of the four matched Phase detectors that are added, 
> subtracted 
> and combined and linerized in such a way as to cancel the type of errors 

> found in single XOR phase detectors.
> 
> Preliminary Performance
> The noise floor that I have seen while feeding the same low 
> noise osc, to both inputs, 
> is around 10 uv peak to peak at low Bandwidths, at zero phase, 
> using a 6 digit DVM 
> with a slow filter which corresponds to <<1 ps. Test are still 
> underway to see what the 
> lower limit is, and what the sensitivity to the environment is.
> 
> This is just the start of an on going learning project, It is 
> just at the breadboard stage and 
> needs to be verified, critiqued, cleaned up and packaged up. 
> Noted that when working with sub ps resolution, extra care 
> needs to be taken.
> Although it looks to be a standard digital circuit, It is not. 
> It is a very sensitive Analog circuit 
> capable of giving 1 part in a million type of resolution. It 
> can resolve path distance changes 
> in the 1/100 to 1/1000 of an inch, and needs to be built with 
> care and 'respect'. 
> 
> Another use (beside watching just how noisy your "GOOD " osc is),
> It can be used to compare and adjust the freq differences 
> between two osc 
> very quickly and with more resolution than most can use.
> 1 E-12 freq difference gave several counts per second change on 
> the DVM, and with the DVM updating at several times a second, 
> it made fine freq adjustments much easer than slower monitoring ways.
> 
> 
> If you know of other simple high resolution phase detectors, 
> or see any problems or improvements 
> with the idea, I'd like to hear from you.
> 
> Have fun
> WarrenS
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-
> bin/mailman/listinfo/time-nuts
> and follow the instructions there.



From bruce.griffiths at xtra.co.nz  Mon Dec  8 22:53:08 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Tue, 09 Dec 2008 11:53:08 +1300
Subject: [time-nuts] Sub Pico Second Phase logger
In-Reply-To: <OFB7BC2CE2.9C55EBF4-ON85257519.00787791-85257519.00790527@mck.us.ray.com>
References: <OFB7BC2CE2.9C55EBF4-ON85257519.00787791-85257519.00790527@mck.us.ray.com>
Message-ID: <493DA554.8080609@xtra.co.nz>

Joseph M Gwinn wrote:
> People used passive mixers driving electromechanical stripchart recorders 
> to compare high-stability oscillators in the good old days.
>
> One assumes that there is a purely analog approach to measurement of 
> picosecond changes in delay at 10 MHz using a single oscillator, but I 
> have not seen any methods described, probably because the relevant 
> articles appeared many decades ago.
>
> Can anyone suggest some articles to read?
>
> Thanks,
>
> Joe Gwinn
>   
Joe

Although one could in principle do this with a single diode double
balanced mixer used as a phase detector all one may end up measuring is
the effect of ambient temperature changes on the mixer phase shift.
Lower mixer phase shift tempcos are possible if the RF port is unsaturated.
A classical dual mixer system is probably better in that with matched
tempco mixers maintained at the same temperature the differential phase
shift tempco should (with careful matching) be lower.

Other than the numerous classical papers on dual mixer systems and the
occasionl NIST paper that have some mixer phase shift tempco data
(albeit sparse), I am not aware of any specific papers.

A purely analog approach to phase shift measurement has to be more
difficult than a hybrid one using a pair of low frequency ADCs (eg high
end sound card).

Bruce


From gwinn at raytheon.com  Mon Dec  8 23:37:34 2008
From: gwinn at raytheon.com (Joseph M Gwinn)
Date: Mon, 8 Dec 2008 18:37:34 -0500
Subject: [time-nuts] Sub Pico Second Phase logger
In-Reply-To: <493DA554.8080609@xtra.co.nz>
Message-ID: <OF5B683966.E233742C-ON85257519.007F81E4-85257519.0081C7F5@mck.us.ray.com>

Bruce,


time-nuts-bounces at febo.com wrote on 12/08/2008 05:53:08 PM:

> Joseph M Gwinn wrote:
> > People used passive mixers driving electromechanical stripchart 
recorders 
> > to compare high-stability oscillators in the good old days.
> >
> > One assumes that there is a purely analog approach to measurement of 
> > picosecond changes in delay at 10 MHz using a single oscillator, but I 

> > have not seen any methods described, probably because the relevant 
> > articles appeared many decades ago.
> >
> > Can anyone suggest some articles to read?
> >
> > Thanks,
> >
> > Joe Gwinn
> > 
> Joe
> 
> Although one could in principle do this with a single diode double
> balanced mixer used as a phase detector all one may end up measuring is
> the effect of ambient temperature changes on the mixer phase shift.
> Lower mixer phase shift tempcos are possible if the RF port is 
> unsaturated.

Single diode?  Why wouldn't one use a standard (MiniCircuits or the like) 
four-diode two-transformer double-balanced mixer as the phase detector? 
Many mixers have IF response down to DC.


> A classical dual mixer system is probably better in that with matched
> tempco mixers maintained at the same temperature the differential phase
> shift tempco should (with careful matching) be lower.

Dual mixer as in DMTD (dual mixer time difference) would certainly work, 
but is pretty complex and temperature sensitive.

I did use a loaner Symmetricom 5120A (a full digital DMTD implementation) 
to make some measurements six months ago, and after a few days of 
continuous operation it had settled to the point that one could see 0.01 
pS changes.  (And touching one of the BNC connectors caused a 1-3 pS 
jump.)  This instrument costs about $30K, and is intended more for 
measuring phase noise and allan variance than delay changes.

Anyway, I have to wonder what people did before DMTD was invented.


> Other than the numerous classical papers on dual mixer systems and the
> occasionl NIST paper that have some mixer phase shift tempco data
> (albeit sparse), I am not aware of any specific papers.

I've read many or most of the classical DMTD papers, and have seen various 
passing estimates that diode-ring mixers have a temperature sensitivity of 
8 to 10 pS per degree C.  (I recall your figure was 10 pS/K.)  I assume 
that the DC offset also varies with themerature and drive signal 
amplitude.

 
> A purely analog approach to phase shift measurement has to be more
> difficult than a hybrid one using a pair of low frequency ADCs (eg high
> end sound card).

Is the sound-card approach workable at the millidegree to microdegree 
level, if the change is spread out over an hour?  One picosecond at 10 MHz 
is 3.6 millidegrees of phase.

Joe


From bruce.griffiths at xtra.co.nz  Tue Dec  9 00:12:22 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Tue, 09 Dec 2008 13:12:22 +1300
Subject: [time-nuts] Sub Pico Second Phase logger
In-Reply-To: <OF5B683966.E233742C-ON85257519.007F81E4-85257519.0081C7F5@mck.us.ray.com>
References: <OF5B683966.E233742C-ON85257519.007F81E4-85257519.0081C7F5@mck.us.ray.com>
Message-ID: <493DB7E6.8030404@xtra.co.nz>

Joseph M Gwinn wrote:
> Bruce,
>
>
> time-nuts-bounces at febo.com wrote on 12/08/2008 05:53:08 PM:
>
>   
>> Joseph M Gwinn wrote:
>>     
>>> People used passive mixers driving electromechanical stripchart 
>>>       
> recorders 
>   
>>> to compare high-stability oscillators in the good old days.
>>>
>>> One assumes that there is a purely analog approach to measurement of 
>>> picosecond changes in delay at 10 MHz using a single oscillator, but I 
>>>       
>
>   
>>> have not seen any methods described, probably because the relevant 
>>> articles appeared many decades ago.
>>>
>>> Can anyone suggest some articles to read?
>>>
>>> Thanks,
>>>
>>> Joe Gwinn
>>>
>>>       
>> Joe
>>
>> Although one could in principle do this with a single diode double
>> balanced mixer used as a phase detector all one may end up measuring is
>> the effect of ambient temperature changes on the mixer phase shift.
>> Lower mixer phase shift tempcos are possible if the RF port is 
>> unsaturated.
>>     
>
> Single diode?  Why wouldn't one use a standard (MiniCircuits or the like) 
> four-diode two-transformer double-balanced mixer as the phase detector? 
> Many mixers have IF response down to DC.
>
>   
Oops, I meant "single diode type double balanced mixer style phase
detector".
>   
>> A classical dual mixer system is probably better in that with matched
>> tempco mixers maintained at the same temperature the differential phase
>> shift tempco should (with careful matching) be lower.
>>     
>
> Dual mixer as in DMTD (dual mixer time difference) would certainly work, 
> but is pretty complex and temperature sensitive.
>
> I did use a loaner Symmetricom 5120A (a full digital DMTD implementation) 
> to make some measurements six months ago, and after a few days of 
> continuous operation it had settled to the point that one could see 0.01 
> pS changes.  (And touching one of the BNC connectors caused a 1-3 pS 
> jump.)  This instrument costs about $30K, and is intended more for 
> measuring phase noise and allan variance than delay changes.
>
> Anyway, I have to wonder what people did before DMTD was invented.
>
>
>   
>> Other than the numerous classical papers on dual mixer systems and the
>> occasionl NIST paper that have some mixer phase shift tempco data
>> (albeit sparse), I am not aware of any specific papers.
>>     
>
> I've read many or most of the classical DMTD papers, and have seen various 
> passing estimates that diode-ring mixers have a temperature sensitivity of 
> 8 to 10 pS per degree C.  (I recall your figure was 10 pS/K.)  I assume 
> that the DC offset also varies with themerature and drive signal 
> amplitude.
>   
The only reference I have on the offset tempco is a miniciruits
application note from which one can deduce that the equivalent phase
shift tempco associated with the offset tempco is a few hundred
femtosec/C (@ 10MHz +7dBm) at some temperatures for the particular mixer
used. The graph also indicated (if you are lucky) that the offset tempco
may be zero at around 20C.
A NIST paper indicated that mixer phase shift tempco was around 10x
lower if the Rf port was unsaturated. It also indicated that the mixer
phase shift tempco is much lower if the input frequency is 100MHz rather
than 10MHz. This was one reason given for shifting to 100MHz DMTD systems.
>  
>   
>> A purely analog approach to phase shift measurement has to be more
>> difficult than a hybrid one using a pair of low frequency ADCs (eg high
>> end sound card).
>>     
>
> Is the sound-card approach workable at the millidegree to microdegree 
> level, if the change is spread out over an hour?  One picosecond at 10 MHz 
> is 3.6 millidegrees of phase.
>
> Joe
>
>   
Preliminary (non optimum) tests by Ulrich indicate that picosecond
stability for times up to 100sec is very easy to achieve.
Beyond that mixer phase shift tempco mismatch may be significant.
ADEV noise level of around 2E-14/Tau (1s < tau <100s).
Haven't yet seen have data for longer tau.
With identical beat frequency outputs crosstalk between channels within
the sound card shouldn't be a great problem.
In any case its very easy to measure the crosstalk transfer function.

One concern particularly for low beat frequencies is the phase shift in
the sound card input coupling capacitors (usually electrolytics).

It should be easy to test the sound card phase shift stability for this
application by driving both inputs from the same signal source.

Bruce



From Stephen.Quigg at measurement.gov.au  Tue Dec  9 04:06:30 2008
From: Stephen.Quigg at measurement.gov.au (Quigg, Stephen)
Date: Tue, 9 Dec 2008 15:06:30 +1100
Subject: [time-nuts] Ball-Efratom FRK-L manual [SEC=UNCLASSIFIED]
Message-ID: <EE70B72D037E154D981B052AD43B001E06A04A@PINS3VEX01.in.measurement.gov.au>

 

Looking for a manual for the FRK-L.

Thanks in advance

 

 


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From jmiles at pop.net  Tue Dec  9 05:58:25 2008
From: jmiles at pop.net (John Miles)
Date: Mon, 8 Dec 2008 21:58:25 -0800
Subject: [time-nuts] Ball-Efratom FRK-L manual [SEC=UNCLASSIFIED]
In-Reply-To: <EE70B72D037E154D981B052AD43B001E06A04A@PINS3VEX01.in.measurement.gov.au>
Message-ID: <PKEGJHPHLLBACEOICCBJAEEFPKAB.jmiles@pop.net>

Hadley's site has this one: http://to-way.com/tf.html

-- john, KE5FX

> -----Original Message-----
> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com]On
> Behalf Of Quigg, Stephen
> Sent: Monday, December 08, 2008 8:06 PM
> To: time-nuts at febo.com
> Subject: [time-nuts] Ball-Efratom FRK-L manual [SEC=UNCLASSIFIED]
> 
> 
>  
> 
> Looking for a manual for the FRK-L.
> 
> Thanks in advance
> 
>  
> 
> 


From ernieperes at aol.com  Tue Dec  9 11:37:34 2008
From: ernieperes at aol.com (ernieperes at aol.com)
Date: Tue, 09 Dec 2008 06:37:34 -0500
Subject: [time-nuts] TRUETIME   XL-DC  Manual
Message-ID: <8CB2809A9B95F6A-1458-27D6@FWM-D45.sysops.aol.com>

Hi Gents,

anybody has a manual or more detailed info about this unit?????

I just got 2ea unit / rack mounted / but one of them is inop... GPS 
does not receiving any sat.... the rest of the unit according to the 
BITE test is OK....
Swapping the GPS module sub assembly in the rack does not help because 
the 2 module is not identical..... ie.. the GPS sub-board is different 
and assume the rack mother board also has minor differences.
Any help is appreciated.

Ernie.


From richiem at hughes.net  Tue Dec  9 20:04:43 2008
From: richiem at hughes.net (Richard Moore)
Date: Tue, 9 Dec 2008 12:04:43 -0800
Subject: [time-nuts] Manuals
In-Reply-To: <mailman.5.1228824001.25444.time-nuts@febo.com>
References: <mailman.5.1228824001.25444.time-nuts@febo.com>
Message-ID: <9BA1C300-3C21-465D-A438-35A0CE529A00@hughes.net>

Hi, tickers -- I recently picked up an HP 5353A plug-in for my HP  
5345A. It's enroute now and is untested. I hate to pay twice as much  
for a manual as I did for the unit, and I really like having docs on  
stuff. I've visited all the usual suspects -- Didier, Boat-Anchor,  
TekNet, etc. -- and have found nothing. Anybody have one I can copy?

Best,
Dick Moore


From pvince at theiet.org  Tue Dec  9 21:44:45 2008
From: pvince at theiet.org (Peter Vince)
Date: Tue, 09 Dec 2008 21:44:45 +0000
Subject: [time-nuts] What are the important features to look for in an
	time
Message-ID: <49867.1228859085@uk2.net>


>What are the important features to look for in an time sync piece of
>hardware?
>
>Anyone have a list of the good/required/nice to have features?


While accepting the "horses for courses" comments, how about these ideas:

These features would relate to ANY equipment:

1) "Turn-key" operation.  Often you will just want to plug a piece of equipment in, and it should work with no user 
intervention.

2) Logging output.  A simple output that can optionally be used to see everything is working OK.

3) Configurability.

4) Optional manual operation of normally automatic functions.

5) If controllable via front-panel display and buttons, a sufficiently complex display to easily see what is needed, and enough 
buttons to make control simple without stepping up, down, and sideways through endless menus.


Specifically for time/frequency synchronising (and perhaps these are performance specs rather than features):

1) Timing accuracy.

2) Timing jitter and wander (ADEV and MTIE).

3) Step sizes (time and frequency).

4) Effects of power supply and environmental variations (temperature, humidity, vibration).


Peter





From gwinn at raytheon.com  Tue Dec  9 21:56:25 2008
From: gwinn at raytheon.com (Joseph M Gwinn)
Date: Tue, 9 Dec 2008 16:56:25 -0500
Subject: [time-nuts] Sub Pico Second Phase logger
In-Reply-To: <493DB7E6.8030404@xtra.co.nz>
Message-ID: <OF8719C35A.064E2D7B-ON8525751A.00728071-8525751A.00788546@mck.us.ray.com>

Bruce


time-nuts-bounces at febo.com wrote on 12/08/2008 07:12:22 PM:

> Joseph M Gwinn wrote:
> > Bruce,
> >
> >
> > time-nuts-bounces at febo.com wrote on 12/08/2008 05:53:08 PM:
> >
> > 
> >> Joseph M Gwinn wrote:
> >> 
> >>> People used passive mixers driving electromechanical stripchart 
recorders 
> >>> to compare high-stability oscillators in the good old days.
> >>>
> >>> One assumes that there is a purely analog approach to measurement of 

> >>> picosecond changes in delay at 10 MHz using a single oscillator, but 
I 
> >>> have not seen any methods described, probably because the relevant 
> >>> articles appeared many decades ago.
> >>>
> >>> Can anyone suggest some articles to read?
> >>>
> >>> Thanks,
> >>>
> >>> Joe Gwinn
> >>>
> >>> 
> >> Joe
> >>
> >> Although one could in principle do this with a single diode double
> >> balanced mixer used as a phase detector all one may end up measuring 
is
> >> the effect of ambient temperature changes on the mixer phase shift.
> >> Lower mixer phase shift tempcos are possible if the RF port is 
> >> unsaturated.
> >> 
> >
> > Single diode?  Why wouldn't one use a standard (MiniCircuits or the 
like) 
> > four-diode two-transformer double-balanced mixer as the phasedetector? 

> > Many mixers have IF response down to DC.
> > 
> Oops, I meant "single diode type double balanced mixer style phase
> detector".

Ah.  Four single diodes in a ratrace ring.  Max drive +13 dBm or so. 
Called Class I or Type I.

MiniCircuits ZRPD-1 being one example.

By the way, despite the circuit diagram in the datasheet, the 
corresponding phase-detector module MPD-1 can be wired to have the IF 
output ground isolated from the common RF, LO and case ground.  A little 
work with an ohmmeter will tell the tale.  This can help to contain the 
low frequency beatnote.

 
> >> A classical dual mixer system is probably better in that with matched
> >> tempco mixers maintained at the same temperature the differential 
phase
> >> shift tempco should (with careful matching) be lower.
> >
> > Dual mixer as in DMTD (dual mixer time difference) would certainly 
work, 
> > but is pretty complex and temperature sensitive.
> >
> > I did use a loaner Symmetricom 5120A (a full digital DMTD 
implementation) 
> > to make some measurements six months ago, and after a few days of 
> > continuous operation it had settled to the point that one could see 
0.01 
> > pS changes.  (And touching one of the BNC connectors caused a 1-3 pS 
> > jump.)  This instrument costs about $30K, and is intended more for 
> > measuring phase noise and allan variance than delay changes.
> >
> > Anyway, I have to wonder what people did before DMTD was invented.
> >
> >
> > 
> >> Other than the numerous classical papers on dual mixer systems and 
the
> >> occasionl NIST paper that have some mixer phase shift tempco data
> >> (albeit sparse), I am not aware of any specific papers.
> >
> > I've read many or most of the classical DMTD papers, and have seen 
various 
> > passing estimates that diode-ring mixers have a temperature 
sensitivity of 
> > 8 to 10 pS per degree C.  (I recall your figure was 10 pS/K.)  I 
assume 
> > that the DC offset also varies with temperature and drive signal 
> > amplitude.
> > 
> The only reference I have on the offset tempco is a miniciruits
> application note from which one can deduce that the equivalent phase
> shift tempco associated with the offset tempco is a few hundred
> femtosec/C (@ 10MHz +7dBm) at some temperatures for the particular mixer
> used. The graph also indicated (if you are lucky) that the offset tempco
> may be zero at around 20C.

Do you recall the part number?


> A NIST paper indicated that mixer phase shift tempco was around 10x
> lower if the Rf port was unsaturated. It also indicated that the mixer
> phase shift tempco is much lower if the input frequency is 100MHz rather
> than 10MHz. This was one reason given for shifting to 100MHz 
> DMTD systems.

Do you recall which paper?


What I've seen that seems useful is the Watkins-Johnson application note 
from 1978 on use of mixers as phase detectors: "Mixers as Phase 
Detectors", Stephan R. Kurtz, 8 pages.  This may be the source of the NIST 
article's information.  The electrons are available on the web from WJ 
Communications (now owned by TriQuint), filename "
http://www.wj.com/archive/documents/Tech_Notes_Archived/Mixers_phase_detectors.pdf
".  Don't know how long this URL will work, as WJ is assimilated into 
TriQuint.

 
> >> A purely analog approach to phase shift measurement has to be more
> >> difficult than a hybrid one using a pair of low frequency ADCs (eg 
high
> >> end sound card).
> >> 
> >
> > Is the sound-card approach workable at the millidegree to microdegree 
> > level, if the change is spread out over an hour?  One picosecond at 10 
MHz 
> > is 3.6 millidegrees of phase.
> >
> > Joe
> >
> > 
> Preliminary (non optimum) tests by Ulrich indicate that picosecond
> stability for times up to 100sec is very easy to achieve.
> Beyond that mixer phase shift tempco mismatch may be significant.

It would not be that hard to make an oven for the mixer, as the level of 
control needed is far less stringent than for a crystal.


> ADEV noise level of around 2E-14/Tau (1s < tau <100s).
> Haven't yet seen [or] have data for longer tau.

Yes.  Need at least 10^4 seconds.


> With identical beat frequency outputs, crosstalk between channels within
> the sound card shouldn't be a great problem.

I'm not sure I believe this, as there is likely ground coupling within the 
soundcard and the ear is famously insensitive to phase.  Channel isolation 
of 60 dB isn't enough to prevent phase shifts.


> In any case it's very easy to measure the crosstalk transfer function.

Yes.

 
> One concern particularly for low beat frequencies is the phase shift in
> the sound card input coupling capacitors (usually electrolytics).
> 
> It should be easy to test the sound card phase shift stability for this
> application by driving both inputs from the same signal source.

I assume that the beatnote must be ~100 Hz for the soundcard to handle 
with low phase shift.  One might get to 10 Hz, but 1 Hz is likely 
hopeless.

One thing that will be very useful is a list of sound cards by make and 
model, annotated with their advantages and disadvantages for time-nut use.

"High-end" may not be a sufficient description.


By the way, I looked at the operating and service manual for the HP 
K34-59991A Broadband Linear Phase Comparator.  Very interesting little 
gadget, but little performance data was given.  Does anyone know how well 
phase change can be measured?  It would be easy to duplicate this with 
modern ICs.  Also, about when was this unit made?  The manual has no date.


Joe


From bruce.griffiths at xtra.co.nz  Tue Dec  9 23:24:22 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Wed, 10 Dec 2008 12:24:22 +1300
Subject: [time-nuts] Sub Pico Second Phase logger
In-Reply-To: <OF8719C35A.064E2D7B-ON8525751A.00728071-8525751A.00788546@mck.us.ray.com>
References: <OF8719C35A.064E2D7B-ON8525751A.00728071-8525751A.00788546@mck.us.ray.com>
Message-ID: <493EFE26.1030105@xtra.co.nz>

Joseph M Gwinn wrote:
> Bruce
>
>
> time-nuts-bounces at febo.com wrote on 12/08/2008 07:12:22 PM:
>
>   
>> Joseph M Gwinn wrote:
>>     
>>> Bruce,
>>>
>>>
>>> time-nuts-bounces at febo.com wrote on 12/08/2008 05:53:08 PM:
>>>
>>>
>>>       
>>>> Joseph M Gwinn wrote:
>>>>
>>>>         
>>>>> People used passive mixers driving electromechanical stripchart 
>>>>>           
> recorders 
>   
>>>>> to compare high-stability oscillators in the good old days.
>>>>>
>>>>> One assumes that there is a purely analog approach to measurement of 
>>>>>           
>
>   
>>>>> picosecond changes in delay at 10 MHz using a single oscillator, but 
>>>>>           
> I 
>   
>>>>> have not seen any methods described, probably because the relevant 
>>>>> articles appeared many decades ago.
>>>>>
>>>>> Can anyone suggest some articles to read?
>>>>>
>>>>> Thanks,
>>>>>
>>>>> Joe Gwinn
>>>>>
>>>>>
>>>>>           
>>>> Joe
>>>>
>>>> Although one could in principle do this with a single diode double
>>>> balanced mixer used as a phase detector all one may end up measuring 
>>>>         
> is
>   
>>>> the effect of ambient temperature changes on the mixer phase shift.
>>>> Lower mixer phase shift tempcos are possible if the RF port is 
>>>> unsaturated.
>>>>
>>>>         
>>> Single diode?  Why wouldn't one use a standard (MiniCircuits or the 
>>>       
> like) 
>   
>>> four-diode two-transformer double-balanced mixer as the phasedetector? 
>>>       
>
>   
>>> Many mixers have IF response down to DC.
>>>
>>>       
>> Oops, I meant "single diode type double balanced mixer style phase
>> detector".
>>     
>
> Ah.  Four single diodes in a ratrace ring.  Max drive +13 dBm or so. 
> Called Class I or Type I.
>
> MiniCircuits ZRPD-1 being one example.
>
> By the way, despite the circuit diagram in the datasheet, the 
> corresponding phase-detector module MPD-1 can be wired to have the IF 
> output ground isolated from the common RF, LO and case ground.  A little 
> work with an ohmmeter will tell the tale.  This can help to contain the 
> low frequency beatnote.
>
>   
Yes, thats usually the case for the Minicircuits PCB mount phase
detectors and mixers except for some surface mount versions (usually the
very high frequency models).
A PCB mount mixer package is also preferable as its then much easier to
use a capacitive IF port termination (for lower noise) in conjunction
with series resistors at the RF and LO ports (for lower VSWR) than if a
mixer with SMA or other coax connectors were used.
>  
>   
>>>> A classical dual mixer system is probably better in that with matched
>>>> tempco mixers maintained at the same temperature the differential 
>>>>         
> phase
>   
>>>> shift tempco should (with careful matching) be lower.
>>>>         
>>> Dual mixer as in DMTD (dual mixer time difference) would certainly 
>>>       
> work, 
>   
>>> but is pretty complex and temperature sensitive.
>>>
>>> I did use a loaner Symmetricom 5120A (a full digital DMTD 
>>>       
> implementation) 
>   
>>> to make some measurements six months ago, and after a few days of 
>>> continuous operation it had settled to the point that one could see 
>>>       
> 0.01 
>   
>>> pS changes.  (And touching one of the BNC connectors caused a 1-3 pS 
>>> jump.)  This instrument costs about $30K, and is intended more for 
>>> measuring phase noise and allan variance than delay changes.
>>>
>>> Anyway, I have to wonder what people did before DMTD was invented.
>>>
>>>
>>>
>>>       
>>>> Other than the numerous classical papers on dual mixer systems and 
>>>>         
> the
>   
>>>> occasionl NIST paper that have some mixer phase shift tempco data
>>>> (albeit sparse), I am not aware of any specific papers.
>>>>         
>>> I've read many or most of the classical DMTD papers, and have seen 
>>>       
> various 
>   
>>> passing estimates that diode-ring mixers have a temperature 
>>>       
> sensitivity of 
>   
>>> 8 to 10 pS per degree C.  (I recall your figure was 10 pS/K.)  I 
>>>       
> assume 
>   
>>> that the DC offset also varies with temperature and drive signal 
>>> amplitude.
>>>
>>>       
>> The only reference I have on the offset tempco is a miniciruits
>> application note from which one can deduce that the equivalent phase
>> shift tempco associated with the offset tempco is a few hundred
>> femtosec/C (@ 10MHz +7dBm) at some temperatures for the particular mixer
>> used. The graph also indicated (if you are lucky) that the offset tempco
>> may be zero at around 20C.
>>     
>
> Do you recall the part number?
>
>
>   
Supposedly an SRA-1, but some caution is in order as some statements as
to the effect of the input offset of an opamp based IF preamp in the
same application note were of dubious veracity unless one were to use an
inverting opamp input stage.
>> A NIST paper indicated that mixer phase shift tempco was around 10x
>> lower if the Rf port was unsaturated. It also indicated that the mixer
>> phase shift tempco is much lower if the input frequency is 100MHz rather
>> than 10MHz. This was one reason given for shifting to 100MHz 
>> DMTD systems.
>>     
>
> Do you recall which paper?
>
>
>   
http://tf.nist.gov/timefreq/general/pdf/971.pdf
<http://tf.nist.gov/timefreq/general/pdf/971.pdf>
Has some measurement data on mixer phase shift tempco and power
sensitivity and their frequency dependence etc.

I'll search for the paper that stated that the phase shift tempco was
lower if the RF port was unsaturated.
AFAIK there was no accompanying measurement data

> What I've seen that seems useful is the Watkins-Johnson application note 
> from 1978 on use of mixers as phase detectors: "Mixers as Phase 
> Detectors", Stephan R. Kurtz, 8 pages.  This may be the source of the NIST 
> article's information.  The electrons are available on the web from WJ 
> Communications (now owned by TriQuint), filename "
> http://www.wj.com/archive/documents/Tech_Notes_Archived/Mixers_phase_detectors.pdf
> ".  Don't know how long this URL will work, as WJ is assimilated into 
> TriQuint.
>
>  
>   
>>>> A purely analog approach to phase shift measurement has to be more
>>>> difficult than a hybrid one using a pair of low frequency ADCs (eg 
>>>>         
> high
>   
>>>> end sound card).
>>>>
>>>>         
>>> Is the sound-card approach workable at the millidegree to microdegree 
>>> level, if the change is spread out over an hour?  One picosecond at 10 
>>>       
> MHz 
>   
>>> is 3.6 millidegrees of phase.
>>>
>>> Joe
>>>
>>>
>>>       
>> Preliminary (non optimum) tests by Ulrich indicate that picosecond
>> stability for times up to 100sec is very easy to achieve.
>> Beyond that mixer phase shift tempco mismatch may be significant.
>>     
>
> It would not be that hard to make an oven for the mixer, as the level of 
> control needed is far less stringent than for a crystal.
>
>
>   
>> ADEV noise level of around 2E-14/Tau (1s < tau <100s).
>> Haven't yet seen [or] have data for longer tau.
>>     
>
> Yes.  Need at least 10^4 seconds.
>
>
>   
>> With identical beat frequency outputs, crosstalk between channels within
>> the sound card shouldn't be a great problem.
>>     
>
> I'm not sure I believe this, as there is likely ground coupling within the 
> soundcard and the ear is famously insensitive to phase.  Channel isolation 
> of 60 dB isn't enough to prevent phase shifts.
>
>   
It will be present but its effect in some cases (when the phase shift
between channels is such that the crosstalk phase is at 90 degrees to
the signal of interest) will be negligible, in other cases it is easily
measured and compensated for.
>   
>> In any case it's very easy to measure the crosstalk transfer function.
>>     
>
> Yes.
>
>  
>   
>> One concern particularly for low beat frequencies is the phase shift in
>> the sound card input coupling capacitors (usually electrolytics).
>>
>> It should be easy to test the sound card phase shift stability for this
>> application by driving both inputs from the same signal source.
>>     
>
> I assume that the beatnote must be ~100 Hz for the soundcard to handle 
> with low phase shift.  One might get to 10 Hz, but 1 Hz is likely 
> hopeless.
>
> One thing that will be very useful is a list of sound cards by make and 
> model, annotated with their advantages and disadvantages for time-nut use.
>
> "High-end" may not be a sufficient description.
>
>
> By the way, I looked at the operating and service manual for the HP 
> K34-59991A Broadband Linear Phase Comparator.  Very interesting little 
> gadget, but little performance data was given.  Does anyone know how well 
> phase change can be measured?  It would be easy to duplicate this with 
> modern ICs.  Also, about when was this unit made?  The manual has no date.
>
>
> Joe
>
>   
Joe

I suspect that slow phase changes much less than 1ns or so are hard to
distinguish from gain drift given the gain tempco of the ECL phase detector.

A beat note near 1kHz appears to be even better if one is using
something like an enhanced Costas receiver or even using WKS
interpolation to locate and time stamp zero crossings.

So far only the M-Audio AP192 has been used.
Tests with an embedded motherboard 16 bit sound system show
significantly increased noise.
I've found that the noise level of motherboard sound systems varies
enormously from one motherboard model (sample of 2) to another.

Any 24 bit sound card with a performance close to or better than that of
the AP192 should suffice.
Other cards using AKM 24 bit ADCs should also be suitable.
Ideally an external sound card with balanced  XLR inputs would be best.

HP produced a number of different phase comparators each with a
different type of phase detector.
The K34-5991A design can't be older than the early 1970's because the
MECLIII devices used weren't available until then.

Warren built a similar phase detector (differential XOR or XOR + XNOR)
using CMOS ICs and for a common 10MHz input with a phase difference near
zero found short term output noise of of around 10uV or so (10V phase
detector FSR) using a passive low pass filter.
In principle an ADC like the LTC2484 could be used with a 2.5V CMOS
OR/XNOR phase detector and passive low pass filters.
The ratiometric conversion capability will significantly reduce the
sensitivity to the XOR gate supply if the XOR gate supply is also used
for the ADC reference voltage.
If one used 5V logic a resistive output attenuator would be needed which
reduce the gain stability somewhat.

All such phase detectors suffer from substantial nonlinearity near the
ends of the range due to gate output slew rate limitations.
However if operated near the centre of the range subpicosecond
sensitivity/short term stability may be possible.
Since the circuit volume is small and the tempco relatively low (few
ps/C at most) regulating the circuit temperature should be relatively
easy to do.

Bruce


From bruce.griffiths at xtra.co.nz  Wed Dec 10 00:10:55 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Wed, 10 Dec 2008 13:10:55 +1300
Subject: [time-nuts] Sub Pico Second Phase logger
In-Reply-To: <493EFE26.1030105@xtra.co.nz>
References: <OF8719C35A.064E2D7B-ON8525751A.00728071-8525751A.00788546@mck.us.ray.com>
	<493EFE26.1030105@xtra.co.nz>
Message-ID: <493F090F.2070608@xtra.co.nz>

Paper with capacitive IF port termination data:

http://tf.nist.gov/timefreq/general/pdf/112.pdf


Phase detector sensitivity to distortion:

http://tf.nist.gov/timefreq/general/pdf/1437.pdf


Bruce


From gwinn at raytheon.com  Wed Dec 10 00:34:19 2008
From: gwinn at raytheon.com (Joseph M Gwinn)
Date: Tue, 9 Dec 2008 19:34:19 -0500
Subject: [time-nuts] Sub Pico Second Phase logger
In-Reply-To: <493F090F.2070608@xtra.co.nz>
Message-ID: <OFEA3A5175.5B284DC8-ON8525751B.0002E7AF-8525751B.000323C5@mck.us.ray.com>

Bruce,


time-nuts-bounces at febo.com wrote on 12/09/2008 07:10:55 PM:

> Paper with capacitive IF port termination data:
> 
> http://tf.nist.gov/timefreq/general/pdf/112.pdf

This one is new to me, and interesting.  More later, when I've read it.


> Phase detector sensitivity to distortion:
> 
> http://tf.nist.gov/timefreq/general/pdf/1437.pdf

I had found this one, and is why I used a 3 dB attenuator on the LO port 
and a 8 dB attenuator on the RF port.  But the pieces are coming together.


Thanks,

Joe


From bruce.griffiths at xtra.co.nz  Wed Dec 10 00:55:50 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Wed, 10 Dec 2008 13:55:50 +1300
Subject: [time-nuts] Sub Pico Second Phase logger
In-Reply-To: <OFEA3A5175.5B284DC8-ON8525751B.0002E7AF-8525751B.000323C5@mck.us.ray.com>
References: <OFEA3A5175.5B284DC8-ON8525751B.0002E7AF-8525751B.000323C5@mck.us.ray.com>
Message-ID: <493F1396.1010200@xtra.co.nz>

Joseph M Gwinn wrote:
> Bruce,
>
>
> time-nuts-bounces at febo.com wrote on 12/09/2008 07:10:55 PM:
>
>   
>> Paper with capacitive IF port termination data:
>>
>> http://tf.nist.gov/timefreq/general/pdf/112.pdf
>>     
>
> This one is new to me, and interesting.  More later, when I've read it.
>
>
>   
>> Phase detector sensitivity to distortion:
>>
>> http://tf.nist.gov/timefreq/general/pdf/1437.pdf
>>     
>
> I had found this one, and is why I used a 3 dB attenuator on the LO port 
> and a 8 dB attenuator on the RF port.  But the pieces are coming together.
>
>
> Thanks,
>
> Joe
>
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>
>   
Joe

Did you also look at?:

http://tf.nist.gov/timefreq/general/pdf/971.pdf

Which indicates how one can tune the phase shift tempco to some extent.


Bruce


From gwinn at raytheon.com  Wed Dec 10 01:18:14 2008
From: gwinn at raytheon.com (Joseph M Gwinn)
Date: Tue, 9 Dec 2008 20:18:14 -0500
Subject: [time-nuts] Sub Pico Second Phase logger
In-Reply-To: <493EFE26.1030105@xtra.co.nz>
Message-ID: <OFADBD66E6.0CDD94C5-ON8525751A.008336DA-8525751B.0007292F@mck.us.ray.com>

Bruce,


time-nuts-bounces at febo.com wrote on 12/09/2008 06:24:22 PM:

> Joseph M Gwinn wrote:
> > Bruce
> >
> >
> > time-nuts-bounces at febo.com wrote on 12/08/2008 07:12:22 PM:
> >
> > 
[snip]
> >
> > 
> >>> Many mixers have IF response down to DC.
> >>>
> >>> 
> >> Oops, I meant "single diode type double balanced mixer style phase
> >> detector".
> >> 
> >
> > Ah.  Four single diodes in a ratrace ring.  Max drive +13 dBm or so. 
> > Called Class I or Type I.
> >
> > MiniCircuits ZRPD-1 being one example.
> >
> > By the way, despite the circuit diagram in the datasheet, the 
> > corresponding phase-detector module MPD-1 can be wired to have the IF 
> > output ground isolated from the common RF, LO and case ground.  A 
> > little work with an ohmmeter will tell the tale.  This can help to 
contain the 
> > low frequency beatnote.
> 
> Yes, that's usually the case for the Minicircuits PCB mount phase
> detectors and mixers except for some surface mount versions (usually the
> very high frequency models).

So it was already known.  It looks to me that MiniCircuit's intent is to 
support automated testing of modules.


> A PCB mount mixer package is also preferable as its then much easier to
> use a capacitive IF port termination (for lower noise) in conjunction
> with series resistors at the RF and LO ports (for lower VSWR) than if a
> mixer with SMA or other coax connectors were used.

I've been using 3 and 8 dB coaxial attenuators at the LO and RF inputs 
respectively, and it makes a big difference.

But I don't understand the part about capacitive loading of the IF port. I 
would think that the low pass filter would need to present a matched 
impedance at the sum frequency, so the emerging high-level 20 MHz signal 
is not reflected back into the mixer.

MiniCircuits AN-41-001 "FAQ about Phase Detectors" has on page 2 a 500 ohm 
resistor to ground and a 5000 ohm resistor to the first filter capacitor, 
so the capacitor is isolated from the IF port by the resistors.

I just got your posting about paper 112, so more later.

 
[snip]
> >>>> 
> >>> I've read many or most of the classical DMTD papers, and have seen 
> >>> various passing estimates that diode-ring mixers have a temperature 
> >>> sensitivity of 8 to 10 pS per degree C.  (I recall your figure was 
10 pS/K.) 
> >>> I assume that the DC offset also varies with temperature and drive 
signal 
> >>> amplitude.
> >>>
> >>> 
> >> The only reference I have on the offset tempco is a miniciruits
> >> application note from which one can deduce that the equivalent phase
> >> shift tempco associated with the offset tempco is a few hundred
> >> femtosec/C (@ 10MHz +7dBm) at some temperatures for the particular 
mixer
> >> used. The graph also indicated (if you are lucky) that the offset 
tempco
> >> may be zero at around 20C.
> >> 
> >
> > Do you recall the part number?
> >
> >
> > 
> Supposedly an SRA-1, but some caution is in order as some statements as
> to the effect of the input offset of an opamp based IF preamp in the
> same application note were of dubious veracity unless one were to use an
> inverting opamp input stage.

This issue was mentioned in another app note, but their main issue 
appeared to be that the opamp bias currents could cause an offset.


> >> A NIST paper indicated that mixer phase shift tempco was around 10x
> >> lower if the RF port was unsaturated. It also indicated that the 
mixer
> >> phase shift tempco is much lower if the input frequency is 100MHz 
rather
> >> than 10MHz. This was one reason given for shifting to 100MHz 
> >> DMTD systems.
> >> 
> >
> > Do you recall which paper?
> >
> >
> > 
> http://tf.nist.gov/timefreq/general/pdf/971.pdf
> <http://tf.nist.gov/timefreq/general/pdf/971.pdf>
> Has some measurement data on mixer phase shift tempco and power
> sensitivity and their frequency dependence etc.

I do know this paper.  At the bottom of page 834, to the right, is the 
estimate 3.5 pS/K.

Another reason to go to 100 MHz is that the temperature coefficient of 
electrical length of polymer-insulated coax is far lower at 100 MHz 
compared to 10 MHz.


> I'll search for the paper that stated that the phase shift tempco was
> lower if the RF port was unsaturated.

I think I have seen this too, but don't recall where.  But it's why I use 
an 8 dB pad on the RF input.


> AFAIK there was no accompanying measurement data
> 
> > What I've seen that seems useful is the Watkins-Johnson application 
note 
> > from 1978 on use of mixers as phase detectors: "Mixers as Phase 
> > Detectors", Stephan R. Kurtz, 8 pages.  This may be the source of the 
NIST 
> > article's information.  The electrons are available on the web from WJ 

> > Communications (now owned by TriQuint), filename 
<
http://www.wj.com/archive/documents/Tech_Notes_Archived/Mixers_phase_detectors.pdf
>. 
> > Don't know how long this URL will work, as WJ is assimilated into 
> > TriQuint.

This app note is reference 7 of paper 971 above.


[Soundcards]
> >>> 
> >> Preliminary (non optimum) tests by Ulrich indicate that picosecond
> >> stability for times up to 100sec is very easy to achieve.
> >> Beyond that mixer phase shift tempco mismatch may be significant.
> >> 
> >
> > It would not be that hard to make an oven for the mixer, as 
> the level of 
> > control needed is far less stringent than for a crystal.
> >
> >
> > 
> >> ADEV noise level of around 2E-14/Tau (1s < tau <100s).
> >> Haven't yet seen [or] have data for longer tau.
> >> 
> >
> > Yes.  Need at least 10^4 seconds.
> >
> >
> > 
> >> With identical beat frequency outputs, crosstalk between 
> >> channels within the sound card shouldn't be a great problem.
> >> 
> >
> > I'm not sure I believe this, as there is likely ground coupling within 
the 
> > soundcard and the ear is famously insensitive to phase.  Channel 
isolation 
> > of 60 dB isn't enough to prevent phase shifts.
> >
> > 
> It will be present but its effect in some cases (when the phase shift
> between channels is such that the crosstalk phase is at 90 degrees to
> the signal of interest) will be negligible, in other cases it is easily
> measured and compensated for.

Isn't 90 degrees (quadrature) the worst case for causing phase shifts? 

To get a one picosecond change at 10 MHz by injection of an attenuated 
quadrature copy of the main signal requires a relative voltage ratio of 
Tan[(10^-12)(10^7)(360)] = Tan[0.0036] = 0.0000628 of the main signal, or 
20 Log[0.0000628]= -84 dBc.  This is well exceeds the interchannel 
isolation of many sound cards.

Cancellation by mathematical means could be possible, but will require a 
dynamic range well exceeding 84 dB.  This ought to be easy to arrange.


> >> One concern particularly for low beat frequencies is the phase shift 
in
> >> the sound card input coupling capacitors (usually electrolytics).
> >>
> >> It should be easy to test the sound card phase shift stability for 
this
> >> application by driving both inputs from the same signal source.

Or terminate one channel input and drive the other, and measure the 
amplitude and phase of whatever comes out of the terminated channel, 
compared to the driven channel.  Then swap channels and repeat.  The phase 
and amplitude will depend on frequency, so a sweep will be required, and 
some frequencies may need to be avoided.


> > I assume that the beatnote must be ~100 Hz for the soundcard to handle 

> > with low phase shift.  One might get to 10 Hz, but 1 Hz is likely 
> > hopeless.
> >
> > One thing that will be very useful is a list of sound cards by make 
and 
> > model, annotated with their advantages and disadvantages for time-nut 
use.
> >
> > "High-end" may not be a sufficient description.
> >
> >
> > By the way, I looked at the operating and service manual for the HP 
> > K34-59991A Broadband Linear Phase Comparator.  Very interesting little 

> > gadget, but little performance data was given.  Does anyone know how 
well 
> > phase change can be measured?  It would be easy to duplicate this with 

> > modern ICs.  Also, about when was this unit made?  The manual has no 
date.
> >
> >
> > Joe
> >
> > 
> Joe
> 
> I suspect that slow phase changes much less than 1ns or so are hard to
> distinguish from gain drift given the gain tempco of the ECL 
> phase detector.
> 
> A beat note near 1kHz appears to be even better if one is using
> something like an enhanced Costas receiver or even using WKS
> interpolation to locate and time stamp zero crossings.

But it limits the phase slope gain.  I suppose there is an optimum 
somewhere.

 
> So far only the M-Audio AP192 has been used.
> Tests with an embedded motherboard 16 bit sound system show
> significantly increased noise.
> I've found that the noise level of motherboard sound systems varies
> enormously from one motherboard model (sample of 2) to another.
> 
> Any 24 bit sound card with a performance close to or better than that of
> the AP192 should suffice.

In general, firewire connected sound cards should be better, because the 
soundcard maker has complete control of what's inside the box.  Unlike 
inside a PC. 


> Other cards using AKM 24 bit ADCs should also be suitable.

Who is AKM?

20 Log[ 2^24 ] = 144 dB, so something else will be the limit.


> Ideally an external sound card with balanced  XLR inputs would be best.
> 
> HP produced a number of different phase comparators each with a
> different type of phase detector.
> The K34-5991A design can't be older than the early 1970's because the
> MECLIII devices used weren't available until then.

OK.  I recall MECL.  RIP.  But we have PECL now.


> Warren built a similar phase detector (differential XOR or XOR + XNOR)
> using CMOS ICs and for a common 10MHz input with a phase difference near
> zero found short term output noise of of around 10uV or so (10V phase
> detector FSR) using a passive low pass filter.

(10uV)/(10v)= 1 ppm.  (100 nS)(10^-6)= 0.1 pS.


> In principle an ADC like the LTC2484 could be used with a 2.5V CMOS
> OR/XNOR phase detector and passive low pass filters.
> The ratiometric conversion capability will significantly reduce the
> sensitivity to the XOR gate supply if the XOR gate supply is also used
> for the ADC reference voltage.
> If one used 5V logic a resistive output attenuator would be needed which
> reduce the gain stability somewhat.
> 
> All such phase detectors suffer from substantial nonlinearity near the
> ends of the range due to gate output slew rate limitations.

If one is tracking through multiple phase cycles (as did the HP unit), 
this would matter.

As for slew rate, one can buy faster logic, but probably at the expense of 
jitter (as bandwidth must be larger).

The HP unit used balanced logic all the way up to the flipflops.  This 
doubles the relative crossing rate for a given slew rate.  But doubles the 
noise, but it must have been worth it, or HP wouldn't have done that. 

In beatnote zero crossing detectors, differential signals help keep ground 
loops and bounce down.


> However if operated near the centre of the range subpicosecond
> sensitivity/short term stability may be possible.

Yes, 0.1 pS.


> Since the circuit volume is small and the tempco relatively low (few
> ps/C at most) regulating the circuit temperature should be relatively
> easy to do.

We ought to be able to achieve less than 0.1 K change.



Joe


From gwinn at raytheon.com  Wed Dec 10 01:21:37 2008
From: gwinn at raytheon.com (Joseph M Gwinn)
Date: Tue, 9 Dec 2008 20:21:37 -0500
Subject: [time-nuts] Sub Pico Second Phase logger
In-Reply-To: <493F1396.1010200@xtra.co.nz>
Message-ID: <OF5C3B8FE8.5EEFDEE7-ON8525751B.00073CF8-8525751B.000778B0@mck.us.ray.com>

Bruce,


time-nuts-bounces at febo.com wrote on 12/09/2008 07:55:50 PM:

> Joseph M Gwinn wrote:
> > Bruce,
> >
> >
> > time-nuts-bounces at febo.com wrote on 12/09/2008 07:10:55 PM:
> >
> > 
> >> Paper with capacitive IF port termination data:
> >>
> >> http://tf.nist.gov/timefreq/general/pdf/112.pdf
> >> 
> >
> > This one is new to me, and interesting.  More later, when I've read 
it.
> >
> >
> > 
> >> Phase detector sensitivity to distortion:
> >>
> >> http://tf.nist.gov/timefreq/general/pdf/1437.pdf
> >> 
> >
> > I had found this one, and is why I used a 3 dB attenuator on the LO 
port 
> > and a 8 dB attenuator on the RF port.  But the pieces are coming 
together.
> >
> >
> > Thanks,
> >
> > Joe
> >
> > _______________________________________________
> > time-nuts mailing list -- time-nuts at febo.com
> > To unsubscribe, go to https://www.febo.com/cgi-
> bin/mailman/listinfo/time-nuts
> > and follow the instructions there.
> >
> > 
> Joe
> 
> Did you also look at?:
> 
> http://tf.nist.gov/timefreq/general/pdf/971.pdf
> 
> Which indicates how one can tune the phase shift tempco to some extent.

Yes, I did know of that one, but thanks.  It seems largely based on prior 
papers, a summation of sorts.


Joe


From daun at yeagley.net  Wed Dec 10 01:43:10 2008
From: daun at yeagley.net (Daun Yeagley)
Date: Tue, 9 Dec 2008 20:43:10 -0500
Subject: [time-nuts] Manuals
In-Reply-To: <9BA1C300-3C21-465D-A438-35A0CE529A00@hughes.net>
References: <mailman.5.1228824001.25444.time-nuts@febo.com>
	<9BA1C300-3C21-465D-A438-35A0CE529A00@hughes.net>
Message-ID: <F5573522AE0E4C95B780608A40703A25@daundell>

Hi Dick

You might try Dave at Artek Media http://www.artekmedia.com/ (or email to
manuals at artekmedia.com).  He's active on the
hp_agilent_equipment at yahoogroups.com list.  I know he has literally *tons*
of HP manuals, because he picked them up from my barn where I've been
storing them since saving them from the dumpster for the Dayton Sales office
several years ago. (they were pitching the entire collection, and I couldn't
bear the thought of loosing all those manuals).  I think they've now found a
good home with Dave, as he seems to really be in the spirit of keeping the
older manuals available.  His prices are pretty reasonable too!

Daun 

-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of Richard Moore
Sent: Tuesday, December 09, 2008 3:05 PM
To: time-nuts at febo.com
Subject: Re: [time-nuts] Manuals

Hi, tickers -- I recently picked up an HP 5353A plug-in for my HP 5345A.
It's enroute now and is untested. I hate to pay twice as much for a manual
as I did for the unit, and I really like having docs on stuff. I've visited
all the usual suspects -- Didier, Boat-Anchor, TekNet, etc. -- and have
found nothing. Anybody have one I can copy?

Best,
Dick Moore

_______________________________________________
time-nuts mailing list -- time-nuts at febo.com To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.



From bruce.griffiths at xtra.co.nz  Wed Dec 10 02:20:08 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Wed, 10 Dec 2008 15:20:08 +1300
Subject: [time-nuts] Sub Pico Second Phase logger
In-Reply-To: <OFADBD66E6.0CDD94C5-ON8525751A.008336DA-8525751B.0007292F@mck.us.ray.com>
References: <OFADBD66E6.0CDD94C5-ON8525751A.008336DA-8525751B.0007292F@mck.us.ray.com>
Message-ID: <493F2758.6080809@xtra.co.nz>

Joe

Joseph M Gwinn wrote:
> Bruce,
>   
>>> By the way, despite the circuit diagram in the datasheet, the 
>>> corresponding phase-detector module MPD-1 can be wired to have the IF 
>>> output ground isolated from the common RF, LO and case ground.  A 
>>> little work with an ohmmeter will tell the tale.  This can help to 
>>>       
> contain the 
>   
>>> low frequency beatnote.
>>>       
>> Yes, that's usually the case for the Minicircuits PCB mount phase
>> detectors and mixers except for some surface mount versions (usually the
>> very high frequency models).
>>     
>
> So it was already known.  It looks to me that MiniCircuit's intent is to 
> support automated testing of modules.
>
>
>   
>> A PCB mount mixer package is also preferable as its then much easier to
>> use a capacitive IF port termination (for lower noise) in conjunction
>> with series resistors at the RF and LO ports (for lower VSWR) than if a
>> mixer with SMA or other coax connectors were used.
>>     
>
> I've been using 3 and 8 dB coaxial attenuators at the LO and RF inputs 
> respectively, and it makes a big difference.
>
> But I don't understand the part about capacitive loading of the IF port. I 
> would think that the low pass filter would need to present a matched 
> impedance at the sum frequency, so the emerging high-level 20 MHz signal 
> is not reflected back into the mixer.
>   
Reflecting the sum frequency back into the mixer is actually necessary
to reduce the noise at the IF port.
I believe that one of Agilent's simulation application notes mentions
this effect but I don't recall the actual application note number.
This will affect the mixer RF and IF port impedance so adding a series
resistor may be required to improve the SWR.
> MiniCircuits AN-41-001 "FAQ about Phase Detectors" has on page 2 a 500 ohm 
> resistor to ground and a 5000 ohm resistor to the first filter capacitor, 
> so the capacitor is isolated from the IF port by the resistors.
>
>   
I wouldn't take too much notice of that recommendation as I have little
confidence in the author's experience/knowledge.

>> Supposedly an SRA-1, but some caution is in order as some statements as
>> to the effect of the input offset of an opamp based IF preamp in the
>> same application note were of dubious veracity unless one were to use an
>> inverting opamp input stage.
>>     
>
> This issue was mentioned in another app note, but their main issue 
> appeared to be that the opamp bias currents could cause an offset.
>
>
>   
But the circuit they suggest has no effect on bias current induced
offset, the same current flows into the mixer and termination impedance
independent of the series resistance.
>>>> A NIST paper indicated that mixer phase shift tempco was around 10x
>>>> lower if the RF port was unsaturated. It also indicated that the 
>>>>         
> mixer
>   
>>>> phase shift tempco is much lower if the input frequency is 100MHz 
>>>>         
> rather
>   
>>>> than 10MHz. This was one reason given for shifting to 100MHz 
>>>> DMTD systems.
>>>>
>>>>         
>>> Do you recall which paper?
>>>
>>>
>>>
>>>       
>> http://tf.nist.gov/timefreq/general/pdf/971.pdf
>> <http://tf.nist.gov/timefreq/general/pdf/971.pdf>
>> Has some measurement data on mixer phase shift tempco and power
>> sensitivity and their frequency dependence etc.
>>     
>
> I do know this paper.  At the bottom of page 834, to the right, is the 
> estimate 3.5 pS/K.
>
> Another reason to go to 100 MHz is that the temperature coefficient of 
> electrical length of polymer-insulated coax is far lower at 100 MHz 
> compared to 10 MHz.
>
>
>   
>> I'll search for the paper that stated that the phase shift tempco was
>> lower if the RF port was unsaturated.
>>     
>
> I think I have seen this too, but don't recall where.  But it's why I use 
> an 8 dB pad on the RF input.
>
>
> http://www.wj.com/archive/documents/Tech_Notes_Archived/Mixers_phase_detectors.pdf
>   
>> . 
>>     
>>> Don't know how long this URL will work, as WJ is assimilated into 
>>> TriQuint.
>>>       
>
> This app note is reference 7 of paper 971 above.
>
>
> [Soundcards]
>>>
>>>> With identical beat frequency outputs, crosstalk between 
>>>> channels within the sound card shouldn't be a great problem.
>>>>
>>>>         
>>> I'm not sure I believe this, as there is likely ground coupling within 
>>>       
> the 
>   
>>> soundcard and the ear is famously insensitive to phase.  Channel 
>>>       
> isolation 
>   
>>> of 60 dB isn't enough to prevent phase shifts.
>>>
>>>
>>>       
>> It will be present but its effect in some cases (when the phase shift
>> between channels is such that the crosstalk phase is at 90 degrees to
>> the signal of interest) will be negligible, in other cases it is easily
>> measured and compensated for.
>>     
>
> Isn't 90 degrees (quadrature) the worst case for causing phase shifts? 
>
>   
Yes, I should have said that when the 2 input signals are in quadrature,
any capacitive crosstalk will have little effect on the phase shift.
> To get a one picosecond change at 10 MHz by injection of an attenuated 
> quadrature copy of the main signal requires a relative voltage ratio of 
> Tan[(10^-12)(10^7)(360)] = Tan[0.0036] = 0.0000628 of the main signal, or 
> 20 Log[0.0000628]= -84 dBc.  This is well exceeds the interchannel 
> isolation of many sound cards.
>
> Cancellation by mathematical means could be possible, but will require a 
> dynamic range well exceeding 84 dB.  This ought to be easy to arrange.
>
>   
The AP192 has a somewhat higher interchannel isolation than that, the
interchannel crosstalk spec is about -120dB.
With a sufficiently large number of samples the its easy to see
artifacts as low as -140dBFS.
>   
>>>> One concern particularly for low beat frequencies is the phase shift 
>>>>         
> in
>   
>>>> the sound card input coupling capacitors (usually electrolytics).
>>>>
>>>> It should be easy to test the sound card phase shift stability for 
>>>>         
> this
>   
>>>> application by driving both inputs from the same signal source.
>>>>         
>
> Or terminate one channel input and drive the other, and measure the 
> amplitude and phase of whatever comes out of the terminated channel, 
> compared to the driven channel.  Then swap channels and repeat.  The phase 
> and amplitude will depend on frequency, so a sweep will be required, and 
> some frequencies may need to be avoided.
>
>
>   
>>>       
>> Joe
>>
>> I suspect that slow phase changes much less than 1ns or so are hard to
>> distinguish from gain drift given the gain tempco of the ECL 
>> phase detector.
>>
>> A beat note near 1kHz appears to be even better if one is using
>> something like an enhanced Costas receiver or even using WKS
>> interpolation to locate and time stamp zero crossings.
>>     
>
> But it limits the phase slope gain.  I suppose there is an optimum 
> somewhere.
>
>  
>   
>> So far only the M-Audio AP192 has been used.
>> Tests with an embedded motherboard 16 bit sound system show
>> significantly increased noise.
>> I've found that the noise level of motherboard sound systems varies
>> enormously from one motherboard model (sample of 2) to another.
>>
>> Any 24 bit sound card with a performance close to or better than that of
>> the AP192 should suffice.
>>     
>
> In general, firewire connected sound cards should be better, because the 
> soundcard maker has complete control of what's inside the box.  Unlike 
> inside a PC. 
>
>   
Its hard to find such Firewire systems without such unnecessary frills
(for this application) as high gain preamps.
The gain tempco and linearity of some variable gain audio preamps is
somewhat suspect.
>   
>> Other cards using AKM 24 bit ADCs should also be suitable.
>>     
>
> Who is AKM?
>
>   
Asahi Kasei EKM

http://www.asahi-kasei.co.jp/akm/en/

http://www.asahi-kasei.co.jp/akm/en/product/proaudio.html

> 20 Log[ 2^24 ] = 144 dB, so something else will be the limit.
>
>
>   
Actual ENOB ~ 19 to 20 bits.
>> Ideally an external sound card with balanced  XLR inputs would be best.
>>
>> HP produced a number of different phase comparators each with a
>> different type of phase detector.
>> The K34-5991A design can't be older than the early 1970's because the
>> MECLIII devices used weren't available until then.
>>     
>
> OK.  I recall MECL.  RIP.  But we have PECL now.
>
>   
Same thing, different supplies.
PECL when Vcc is +ve and Vee is GND.
NECL when Vcc is GND and Vee is -ve.
>   
>> Warren built a similar phase detector (differential XOR or XOR + XNOR)
>> using CMOS ICs and for a common 10MHz input with a phase difference near
>> zero found short term output noise of of around 10uV or so (10V phase
>> detector FSR) using a passive low pass filter.
>>     
>
> (10uV)/(10v)= 1 ppm.  (100 nS)(10^-6)= 0.1 pS.
>
>
>   
>> In principle an ADC like the LTC2484 could be used with a 2.5V CMOS
>> OR/XNOR phase detector and passive low pass filters.
>> The ratiometric conversion capability will significantly reduce the
>> sensitivity to the XOR gate supply if the XOR gate supply is also used
>> for the ADC reference voltage.
>> If one used 5V logic a resistive output attenuator would be needed which
>> reduce the gain stability somewhat.
>>
>> All such phase detectors suffer from substantial nonlinearity near the
>> ends of the range due to gate output slew rate limitations.
>>     
>
> If one is tracking through multiple phase cycles (as did the HP unit), 
> this would matter.
>
>   
Can alleviate it to some extent by driving a pair of such phase
detectors so that their outputs are in quadrature.
One just selects the phase detector output that is in the linear range.
The quadrature outputs also allow unambiguous assignment of the sign of
any phase change.
> Joe
>
>   

Bruce


From richiem at hughes.net  Wed Dec 10 02:32:21 2008
From: richiem at hughes.net (Richard Moore)
Date: Tue, 9 Dec 2008 18:32:21 -0800
Subject: [time-nuts] Manuals
In-Reply-To: <mailman.230.1228875615.2499.time-nuts@febo.com>
References: <mailman.230.1228875615.2499.time-nuts@febo.com>
Message-ID: <ADF4D5BA-2C67-44F5-963F-B64AD705A3D2@hughes.net>

On Dec 9, 2008, at 6:20 PM, Daun wrote:

> ------------------------------
>
> Message: 5
> Date: Tue, 9 Dec 2008 20:43:10 -0500
> From: "Daun Yeagley" <daun at yeagley.net>
> Subject: Re: [time-nuts] Manuals
>
> Hi Dick
>
> You might try Dave at Artek Media http://www.artekmedia.com/ (or  
> email to
> manuals at artekmedia.com).  He's active on the
> hp_agilent_equipment at yahoogroups.com list.  I know he has literally  
> *tons*
> of HP manuals, because he picked them up from my barn where I've been
> storing them since saving them from the dumpster for the Dayton  
> Sales office
> several years ago. (they were pitching the entire collection, and I  
> couldn't
> bear the thought of loosing all those manuals).  I think they've  
> now found a
> good home with Dave, as he seems to really be in the spirit of  
> keeping the
> older manuals available.  His prices are pretty reasonable too!
>
> Daun

Thanks, Daun -- I searched Dave's lists but didn't find it, but I  
have not asked him about it directly. It may be something he has but  
has not yet scanned, so I'll drop him a note. I've done a fair amount  
of business with Dave (just got a Fluke 853 book from him two days  
ago) and he's top-notch. I also looked at all of his competitors that  
I am aware of, and none of them had it either. I figure, if all else  
fails, go to time-nuts.

Best,
Dick Moore


From daun at yeagley.net  Wed Dec 10 02:43:15 2008
From: daun at yeagley.net (Daun Yeagley)
Date: Tue, 9 Dec 2008 21:43:15 -0500
Subject: [time-nuts] Manuals
In-Reply-To: <ADF4D5BA-2C67-44F5-963F-B64AD705A3D2@hughes.net>
References: <mailman.230.1228875615.2499.time-nuts@febo.com>
	<ADF4D5BA-2C67-44F5-963F-B64AD705A3D2@hughes.net>
Message-ID: <1674799F23D2432FA441BA933A61656F@daundell>

Hi Dick

I'd go ahead and give him a call.  I know he hasn't had time to go through
everything.... it was over 60 good sized boxes!  The collection is pretty
much every manual ever up to the early 90's when the edict came down to dump
them. (there used to be a complete set in every HP office, and I guess the
powers that be decided it was to expensive to keep them).
So that's probably your best bet, and I'd give fairly good odds that he's
got it (probably in the "to do" stack). He's now got enough stuff to scan to
last several years I would think.
I had toyed with the idea of doing something like that myself, but I knew
I'd never get a round tuitt (and I think my buddies that have been prodding
me knew it too).  So finding Dave's operation seemed to be the right thing
to do.

Daun 
N8ASB

-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of Richard Moore
Sent: Tuesday, December 09, 2008 9:32 PM
To: time-nuts at febo.com
Subject: Re: [time-nuts] Manuals

On Dec 9, 2008, at 6:20 PM, Daun wrote:

> ------------------------------
>
> Message: 5
> Date: Tue, 9 Dec 2008 20:43:10 -0500
> From: "Daun Yeagley" <daun at yeagley.net>
> Subject: Re: [time-nuts] Manuals
>
> Hi Dick
>
> You might try Dave at Artek Media http://www.artekmedia.com/ (or email 
> to manuals at artekmedia.com).  He's active on the 
> hp_agilent_equipment at yahoogroups.com list.  I know he has literally
> *tons*
> of HP manuals, because he picked them up from my barn where I've been 
> storing them since saving them from the dumpster for the Dayton Sales 
> office several years ago. (they were pitching the entire collection, 
> and I couldn't bear the thought of loosing all those manuals).  I 
> think they've now found a good home with Dave, as he seems to really 
> be in the spirit of keeping the older manuals available.  His prices 
> are pretty reasonable too!
>
> Daun

Thanks, Daun -- I searched Dave's lists but didn't find it, but I have not
asked him about it directly. It may be something he has but has not yet
scanned, so I'll drop him a note. I've done a fair amount of business with
Dave (just got a Fluke 853 book from him two days
ago) and he's top-notch. I also looked at all of his competitors that I am
aware of, and none of them had it either. I figure, if all else fails, go to
time-nuts.

Best,
Dick Moore

_______________________________________________
time-nuts mailing list -- time-nuts at febo.com To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.



From pfmonet at wanadoo.fr  Wed Dec 10 06:28:08 2008
From: pfmonet at wanadoo.fr (=?iso-8859-1?Q?Pierre-Fran=E7ois_=28f5bqp=5Fpfm=29?=)
Date: Wed, 10 Dec 2008 07:28:08 +0100
Subject: [time-nuts] problem to access
Message-ID: <03b201c95a90$780761f0$4501a8c0@r44>

Hi,

I really have a problem to access your site to modify my parameters.
All the time sa "secure" error... 
What can I do? 

73's
pf, F5BQP
pfmonet at wanadoo.fr





From warrensjmail-one at yahoo.com  Wed Dec 10 09:03:25 2008
From: warrensjmail-one at yahoo.com (WarrenS)
Date: Wed, 10 Dec 2008 01:03:25 -0800
Subject: [time-nuts] GPS signal simulator
Message-ID: <031201c95aa6$29c11340$6401a8c0@WSOffice>


    In my quest to keep improving my GPSDO, a simple test tool 
that I find indispensable is a GPS 1PPS (or 100Hz) signal simulator 
reference.  Others may also find this useful because it allows testing the 
PLL & DO in their GPSDO to Cs type accuracy using a standard OCXO.

    The advantages of using the 1PPS GPS signal simulator instead of the 
real thing for high accuracy test, is that it eliminates all the errors and unknowns 
that come before the 1PPS signal so that the performance and limitations of 
just the PLL and it disciplined oscillator can be quickly tested independently 
of the receiver and the GPS signal. 
    This also gives higher accuracies than are available from the GPS system, 
while using a relatively low accuracy oscillator for its reference.

    The simulator generates the 1PPS signal from a divided down 
standard 10MHz OCXO. 
 For advanced test a simple Phase modulated 'Noise' can be added to the 
1PPS to represent  the basic phase noise of the GPS receiver's 1PPS signal.
The phase & freq  difference between the reference oscillator and the 
tracked PLL oscillator can then be compared to any desired accuracy 
and resolution limited by the noise, but not the accuracy, of the oscillators. 


Now I am wondering:
Has anyone made or considered the tricks needed to simulate a GPS 
RF signal in a simple and cheap way? 
Something that could be used to send a 1PPS timing signal to a GPS receiver 
for similar basic high accuracy receiver testing from the antenna to the 1PPS? 
It would seem that this may be feasible when used with a receiver that can 
output its 1PPS when locked to a single satellite? ? ?

WarrenS


From brooke at pacific.net  Wed Dec 10 09:44:36 2008
From: brooke at pacific.net (Brooke Clarke)
Date: Wed, 10 Dec 2008 01:44:36 -0800
Subject: [time-nuts] GPS signal simulator
In-Reply-To: <031201c95aa6$29c11340$6401a8c0@WSOffice>
References: <031201c95aa6$29c11340$6401a8c0@WSOffice>
Message-ID: <493F8F84.6020001@pacific.net>

Hi Warren:

Here's some info on a GPS signal generator made by Stanford Telecom  for 
testing their GPS ICs:
http://www.prc68.com/I/5001A.html
I'm sure it could be greatly reduced in size and complexity be replacing all 
the logic with a micro controller, but the RF part would remain.
There is a very strong correlation between the hardware and the ICD-200 GPS spec.

Have Fun,

Brooke Clarke
http://www.prc68.com

WarrenS wrote:
>     In my quest to keep improving my GPSDO, a simple test tool 
> that I find indispensable is a GPS 1PPS (or 100Hz) signal simulator 
> reference.  Others may also find this useful because it allows testing the 
> PLL & DO in their GPSDO to Cs type accuracy using a standard OCXO.
> 
>     The advantages of using the 1PPS GPS signal simulator instead of the 
> real thing for high accuracy test, is that it eliminates all the errors and unknowns 
> that come before the 1PPS signal so that the performance and limitations of 
> just the PLL and it disciplined oscillator can be quickly tested independently 
> of the receiver and the GPS signal. 
>     This also gives higher accuracies than are available from the GPS system, 
> while using a relatively low accuracy oscillator for its reference.
> 
>     The simulator generates the 1PPS signal from a divided down 
> standard 10MHz OCXO. 
>  For advanced test a simple Phase modulated 'Noise' can be added to the 
> 1PPS to represent  the basic phase noise of the GPS receiver's 1PPS signal.
> The phase & freq  difference between the reference oscillator and the 
> tracked PLL oscillator can then be compared to any desired accuracy 
> and resolution limited by the noise, but not the accuracy, of the oscillators. 
> 
> 
> Now I am wondering:
> Has anyone made or considered the tricks needed to simulate a GPS 
> RF signal in a simple and cheap way? 
> Something that could be used to send a 1PPS timing signal to a GPS receiver 
> for similar basic high accuracy receiver testing from the antenna to the 1PPS? 
> It would seem that this may be feasible when used with a receiver that can 
> output its 1PPS when locked to a single satellite? ? ?
> 
> WarrenS
> 
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
> 
> 



From bruce.griffiths at xtra.co.nz  Wed Dec 10 11:31:04 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Thu, 11 Dec 2008 00:31:04 +1300
Subject: [time-nuts] GPS signal simulator
In-Reply-To: <493F8F84.6020001@pacific.net>
References: <031201c95aa6$29c11340$6401a8c0@WSOffice>
	<493F8F84.6020001@pacific.net>
Message-ID: <493FA878.6030309@xtra.co.nz>

Brooke Clarke wrote:
> Hi Warren:
>
> Here's some info on a GPS signal generator made by Stanford Telecom  for 
> testing their GPS ICs:
> http://www.prc68.com/I/5001A.html
> I'm sure it could be greatly reduced in size and complexity be replacing all 
> the logic with a micro controller, but the RF part would remain.
> There is a very strong correlation between the hardware and the ICD-200 GPS spec.
>
> Have Fun,
>
> Brooke Clarke
> http://www.prc68.com
>
>   
Brooke

An FPGA would be far more practical than a microcontroller given the
1.023MHz chip rates for the civilian signals.

Bruce


From jra at febo.com  Wed Dec 10 15:27:38 2008
From: jra at febo.com (John Ackermann N8UR)
Date: Wed, 10 Dec 2008 10:27:38 -0500
Subject: [time-nuts] problem to access
In-Reply-To: <03b201c95a90$780761f0$4501a8c0@r44>
References: <03b201c95a90$780761f0$4501a8c0@r44>
Message-ID: <493FDFEA.3000201@febo.com>

You can ignore the security notice; it is simply saying that the SSL 
certificate we use is self-signed and not bought for $$$ from Verisign 
or someone like that.

73,
John N8UR
----

Pierre-Fran?ois (f5bqp_pfm) wrote:
> Hi,
>  
> I really have a problem to access your site to modify my parameters.
> All the time sa "secure" error... 
> What can I do?
>  
> 73's
> pf, F5BQP
> pfmonet at wanadoo.fr <mailto:pfmonet at wanadoo.fr>
>  
>  
>  
>  
>  



From bruce.griffiths at xtra.co.nz  Wed Dec 10 21:46:50 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Thu, 11 Dec 2008 10:46:50 +1300
Subject: [time-nuts] Sub Pico Second Phase logger
In-Reply-To: <OF8719C35A.064E2D7B-ON8525751A.00728071-8525751A.00788546@mck.us.ray.com>
References: <OF8719C35A.064E2D7B-ON8525751A.00728071-8525751A.00788546@mck.us.ray.com>
Message-ID: <494038CA.9030108@xtra.co.nz>

Joe

Another limitation on using too low a beat frequency is imposed by the
increasing equivalent input noise spectral density of the sound card as
the frequency decreases.

Bruce


From gwinn at raytheon.com  Thu Dec 11 00:48:57 2008
From: gwinn at raytheon.com (Joseph M Gwinn)
Date: Wed, 10 Dec 2008 19:48:57 -0500
Subject: [time-nuts] Sub Pico Second Phase logger
In-Reply-To: <493F2758.6080809@xtra.co.nz>
Message-ID: <OF0090ABB7.674A2CF6-ON8525751C.0000CCC2-8525751C.00047AC8@mck.us.ray.com>

Bruce,


time-nuts-bounces at febo.com wrote on 12/09/2008 09:20:08 PM:

> Joe
> 
> Joseph M Gwinn wrote:
> > Bruce,
> > 
> >> A PCB mount mixer package is also preferable as its then much easier 
to
> >> use a capacitive IF port termination (for lower noise) in conjunction
> >> with series resistors at the RF and LO ports (for lower VSWR) than if 
a
> >> mixer with SMA or other coax connectors were used.
> >> 
> >
> > I've been using 3 and 8 dB coaxial attenuators at the LO and RF inputs 

> > respectively, and it makes a big difference.
> >
> > But I don't understand the part about capacitive loading of the IF 
port. I 
> > would think that the low pass filter would need to present a matched 
> > impedance at the sum frequency, so the emerging high-level 20 MHz 
signal 
> > is not reflected back into the mixer.
> > 
> Reflecting the sum frequency back into the mixer is actually necessary
> to reduce the noise at the IF port.
> I believe that one of Agilent's simulation application notes mentions
> this effect but I don't recall the actual application note number.
> This will affect the mixer RF and IF port impedance so adding a series
> resistor may be required to improve the SWR.

How big an effect is this?  Is the absolute noise decreased, or does it 
remain the same while the signal increase?

If I'm understanding Walls and Stein (paper 112) correctly, the advantage 
is because with the capacitor load the beatnote waveform approaches 
square, thus increasing the zero-crossing speed and therefor the phase 
sensitivity.  This is no doubt true, but the question was if this also 
caused a small everything-dependent phase shift, something that would not 
have mattered in the measurement of phase noise.  The object of paper 112 
was to remedy a 10 to 20 dB error in phase noise measurements.  The 
critical words are in the lower left column of page 337, in the paragraph 
beginning "If the mixer is terminated ...".


> > MiniCircuits AN-41-001 "FAQ about Phase Detectors" has on page 2 a 500 
ohm 
> > resistor to ground and a 5000 ohm resistor to the first filter 
capacitor, 
> > so the capacitor is isolated from the IF port by the resistors.
> >
> > 
> I wouldn't take too much notice of that recommendation as I have little
> confidence in the author's experience/knowledge.

Well, OK, but:

Stephen Kurtz says the same thing on the third column of the third page, a 
bit above Figure 6.

Nelson and Walls (paper 971), Figure 4, also shows the low pass filter 
arranged to absorb the sum signal, not allowing it to be reflected back 
into the mixer.

 
> >> Supposedly an SRA-1, but some caution is in order as some 
> statements as
> >> to the effect of the input offset of an opamp based IF preamp in the
> >> same application note were of dubious veracity unless one 
> were to use an
> >> inverting opamp input stage.
> >> 
> >
> > This issue was mentioned in another app note, but their main issue 
> > appeared to be that the opamp bias currents could cause an offset.
> >
> >
> > 
> But the circuit they suggest has no effect on bias current induced
> offset, the same current flows into the mixer and termination impedance
> independent of the series resistance.

You're right that the proposed remedy didn't make sense.  I don't know 
that this is a big problem with modern opamps, especially FET input ones 
(if needed).


[snip]
> >
> > [Soundcards]
> >>>
> >>>> With identical beat frequency outputs, crosstalk between 
> >>>> channels within the sound card shouldn't be a great problem.
> >>>>
> >>>> 
> >>> I'm not sure I believe this, as there is likely ground coupling 
within the 
> >>> soundcard and the ear is famously insensitive to phase.  Channel 
> >>> isolation of 60 dB isn't enough to prevent phase shifts.
> >>>
> >>>
> >>> 
> >> It will be present but its effect in some cases (when the phase shift
> >> between channels is such that the crosstalk phase is at 90 degrees to
> >> the signal of interest) will be negligible, in other cases it is 
easily
> >> measured and compensated for.
> >> 
> >
> > Isn't 90 degrees (quadrature) the worst case for causing phase shifts? 

> >
> > 
> Yes, I should have said that when the 2 input signals are in quadrature,
> any capacitive crosstalk will have little effect on the phase shift.

Ah.  Because the capacitor coupling adds a second 90 degree shift, 
bringing the total to 180 degrees.

But crosstalk by ground coupling will be unaffected.  As will crosstalk by 
transformer action.  Those boards are pretty crowded.


> > To get a one picosecond change at 10 MHz by injection of an attenuated 

> > quadrature copy of the main signal requires a relative voltage ratio 
of 
> > Tan[(10^-12)(10^7)(360)] = Tan[0.0036] = 0.0000628 of the main signal, 
or 
> > 20 Log[0.0000628]= -84 dBc.  This is well exceeds the interchannel 
> > isolation of many sound cards.
> >
> > Cancellation by mathematical means could be possible, but will require 
a 
> > dynamic range well exceeding 84 dB.  This ought to be easy to arrange.
> >
> > 
> The AP192 has a somewhat higher interchannel isolation than that, the
> interchannel crosstalk spec is about -120dB.
> With a sufficiently large number of samples the its easy to see
> artifacts as low as -140dBFS.

Yep.  Seems like a very good card.


 
> >>>> One concern particularly for low beat frequencies is the phase 
shift 
> >>>> in the sound card input coupling capacitors (usually 
electrolytics).
> >>>>
> >>>> It should be easy to test the sound card phase shift stability for 
> >>>> this application by driving both inputs from the same signal 
source.
> >>>> 
> >
> > Or terminate one channel input and drive the other, and measure the 
> > amplitude and phase of whatever comes out of the terminated channel, 
> > compared to the driven channel.  Then swap channels and repeat.  The 
phase 
> > and amplitude will depend on frequency, so a sweep will be required, 
and 
> > some frequencies may need to be avoided.
> >
> >
> > 
> >>> 
> >> Joe
> >>
> >> I suspect that slow phase changes much less than 1ns or so are hard 
to
> >> distinguish from gain drift given the gain tempco of the ECL 
> >> phase detector.
> >>
> >> A beat note near 1kHz appears to be even better if one is using
> >> something like an enhanced Costas receiver or even using WKS
> >> interpolation to locate and time stamp zero crossings.
> >> 
> >
> > But it limits the phase slope gain.  I suppose there is an optimum 
> > somewhere.
> >
> > 
> > 
> >> So far only the M-Audio AP192 has been used.
> >> Tests with an embedded motherboard 16 bit sound system show
> >> significantly increased noise.
> >> I've found that the noise level of motherboard sound systems varies
> >> enormously from one motherboard model (sample of 2) to another.
> >>
> >> Any 24 bit sound card with a performance close to or better than that 
of
> >> the AP192 should suffice.
> >> 
> >
> > In general, firewire connected sound cards should be better, because 
the 
> > soundcard maker has complete control of what's inside the box.  Unlike 

> > inside a PC. 
> >
> > 
> It's hard to find such Firewire systems without such unnecessary frills
> (for this application) as high gain preamps.

The AP192 has high-level inputs, but I don't know if this bypasses the 
preamps, or attenuates.  Given their target market, I'd bet it bypasses.


> The gain tempco and linearity of some variable gain audio preamps is
> somewhat suspect.

I would think that none of these cards has a good tempco of anything, 
given the lack of necessity in their market.

I would think that linearity would be quite good, given the horsepower 
competitions on linearity.


> >> Other cards using AKM 24 bit ADCs should also be suitable.
> >> 
> >
> > Who is AKM?
> >
> > 
> Asahi Kasei EKM
> 
> http://www.asahi-kasei.co.jp/akm/en/
> 
> http://www.asahi-kasei.co.jp/akm/en/product/proaudio.html
>

Thanks.  I'll look into their data.


> > 20 Log[ 2^24 ] = 144 dB, so something else will be the limit.
> >
> >
> > 
> Actual ENOB ~ 19 to 20 bits.

Makes sense.  20 Log [ 2^19 ] = 114 dB.  Still plenty good enough.


> >> Ideally an external sound card with balanced  XLR inputs would be 
best.

Yes.



> >> HP produced a number of different phase comparators each with a
> >> different type of phase detector.

OK.  And the PLL folk must have a million designs.


> >> The K34-5991A design can't be older than the early 1970's because the
> >> MECLIII devices used weren't available until then.
> >> 
> >
> > OK.  I recall MECL.  RIP.  But we have PECL now.
> >
> > 
> Same thing, different supplies.
> PECL when Vcc is +ve and Vee is GND.
> NECL when Vcc is GND and Vee is -ve.
> > 
> >> Warren built a similar phase detector (differential XOR or XOR + 
XNOR)
> >> using CMOS ICs and for a common 10MHz input with a phase difference 
near
> >> zero found short term output noise of of around 10uV or so (10V phase
> >> detector FSR) using a passive low pass filter.
> >> 
> >
> > (10uV)/(10v)= 1 ppm.  (100 nS)(10^-6)= 0.1 pS.
> >
> >
> > 
> >> In principle an ADC like the LTC2484 could be used with a 2.5V CMOS
> >> OR/XNOR phase detector and passive low pass filters.
> >> The ratiometric conversion capability will significantly reduce the
> >> sensitivity to the XOR gate supply if the XOR gate supply isalso used
> >> for the ADC reference voltage.
> >> If one used 5V logic a resistive output attenuator would be needed 
which
> >> reduce the gain stability somewhat.
> >>
> >> All such phase detectors suffer from substantial nonlinearity near 
the
> >> ends of the range due to gate output slew rate limitations.
> >> 
> >
> > If one is tracking through multiple phase cycles (as did the HP unit), 

> > this would matter.
> >
> > 
> Can alleviate it to some extent by driving a pair of such phase
> detectors so that their outputs are in quadrature.
> One just selects the phase detector output that is in the linear range.
> The quadrature outputs also allow unambiguous assignment of the sign of
> any phase change.

The Symmetricom 5120A does something very clever to alleviate this 
problem.  Explained in US patent 7,227,346 and "Direct-Digital Phase-Noise 
Measurement"; J. Grove, J. Hein, J. Retta, P. Schweiger, W. Solbrig, and 
S.R. Stein; 2004 IEEE International Ultrasonics, Ferroelectrics, and 
Frequency Control Joint 50th Anniversary Conference, pages 287-291.

Joe


From gwinn at raytheon.com  Thu Dec 11 00:52:56 2008
From: gwinn at raytheon.com (Joseph M Gwinn)
Date: Wed, 10 Dec 2008 19:52:56 -0500
Subject: [time-nuts] Sub Pico Second Phase logger
In-Reply-To: <494038CA.9030108@xtra.co.nz>
Message-ID: <OFA2A9EAFC.8C92A058-ON8525751C.00049248-8525751C.0004D861@mck.us.ray.com>

Bruce,


time-nuts-bounces at febo.com wrote on 12/10/2008 04:46:50 PM:

> Joe
> 
> Another limitation on using too low a beat frequency is imposed by the
> increasing equivalent input noise spectral density of the sound card as
> the frequency decreases.

Yes, although people made good use of 1 Hz in DMTD instruments despite the 
junk near DC.


Joe


From bruce.griffiths at xtra.co.nz  Thu Dec 11 00:58:49 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Thu, 11 Dec 2008 13:58:49 +1300
Subject: [time-nuts] Sub Pico Second Phase logger
In-Reply-To: <OFA2A9EAFC.8C92A058-ON8525751C.00049248-8525751C.0004D861@mck.us.ray.com>
References: <OFA2A9EAFC.8C92A058-ON8525751C.00049248-8525751C.0004D861@mck.us.ray.com>
Message-ID: <494065C9.4060806@xtra.co.nz>

Joseph M Gwinn wrote:
> Bruce,
>
>
> time-nuts-bounces at febo.com wrote on 12/10/2008 04:46:50 PM:
>
>   
>> Joe
>>
>> Another limitation on using too low a beat frequency is imposed by the
>> increasing equivalent input noise spectral density of the sound card as
>> the frequency decreases.
>>     
>
> Yes, although people made good use of 1 Hz in DMTD instruments despite the 
> junk near DC.
>
>
> Joe
>   
Joe

The low frequency noise of the components used in their unoptimised
slope amplifiers is significantly smaller than that of a sound card.
A Collin's style optimised slope amplifier limiter may be useful for use
with a sound card (particularly the lower resolution ones) if one is
timetagging the beat frequency zero crossings.
Less slope gain will be required than when driving a counter input.
In the flicker noise region choice of beat frequency is relatively non
critical.

Bruce


From gwinn at raytheon.com  Thu Dec 11 01:15:47 2008
From: gwinn at raytheon.com (Joseph M Gwinn)
Date: Wed, 10 Dec 2008 20:15:47 -0500
Subject: [time-nuts] Sub Pico Second Phase logger
In-Reply-To: <494065C9.4060806@xtra.co.nz>
Message-ID: <OFA014E6A7.7B5A0543-ON8525751C.0005C688-8525751C.0006EFD2@mck.us.ray.com>

Bruce,


time-nuts-bounces at febo.com wrote on 12/10/2008 07:58:49 PM:

> Joseph M Gwinn wrote:
> > Bruce,
> >
> >
> > time-nuts-bounces at febo.com wrote on 12/10/2008 04:46:50 PM:
> >
> > 
> >> Joe
> >>
> >> Another limitation on using too low a beat frequency is imposed by 
the
> >> increasing equivalent input noise spectral density of the sound card 
as
> >> the frequency decreases.
> >> 
> >
> > Yes, although people made good use of 1 Hz in DMTD instruments despite 
the 
> > junk near DC.
> >
> >
> > Joe
> > 
> Joe
> 
> The low frequency noise of the components used in their unoptimised
> slope amplifiers is significantly smaller than that of a sound card.

Who is "their"?  But I would hazard that people designing for operation at 
1 Hz chose components with low flicker noise, to the extent then possible.


> A Collin's style optimised slope amplifier limiter may be useful for use
> with a sound card (particularly the lower resolution ones) if one is
> timetagging the beat frequency zero crossings.
> Less slope gain will be required than when driving a counter input.
> In the flicker noise region choice of beat frequency is relatively non
> critical.

With the vast amount of data available from a soundcard, I'd be tempted to 
do a least squares three-parameter fit of a sine wave to the (decimated) 
measured data and use only the resulting fitted parameters in subsequent 
computations.  Like estimating where the zero crossings are.  Then the 
noise averaging is over the entire fitting window, not just near zero 
crossings.  (I have been following the talk of using a sin x over x 
fitting function, but I don't know if this really works any better than a 
simple fit to a sine, given this much data.)

Joe


From bruce.griffiths at xtra.co.nz  Thu Dec 11 01:38:13 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Thu, 11 Dec 2008 14:38:13 +1300
Subject: [time-nuts] Sub Pico Second Phase logger
In-Reply-To: <OF0090ABB7.674A2CF6-ON8525751C.0000CCC2-8525751C.00047AC8@mck.us.ray.com>
References: <OF0090ABB7.674A2CF6-ON8525751C.0000CCC2-8525751C.00047AC8@mck.us.ray.com>
Message-ID: <49406F05.8030109@xtra.co.nz>

Joe
Joseph M Gwinn wrote:
> Bruce,
>
>   
>> Reflecting the sum frequency back into the mixer is actually necessary
>> to reduce the noise at the IF port.
>> I believe that one of Agilent's simulation application notes mentions
>> this effect but I don't recall the actual application note number.
>> This will affect the mixer RF and IF port impedance so adding a series
>> resistor may be required to improve the SWR.
>>     
>
> How big an effect is this?  Is the absolute noise decreased, or does it 
> remain the same while the signal increase?
>
>   
With the same difference frequency IF port termination impedance,  noise
is actually decreased along with the mixer conversion loss.
However if the sound card input noise dominates reducing the mixer
effective output noise wont help.
> If I'm understanding Walls and Stein (paper 112) correctly, the advantage 
> is because with the capacitor load the beatnote waveform approaches 
> square, thus increasing the zero-crossing speed and therefor the phase 
> sensitivity.  This is no doubt true, but the question was if this also 
> caused a small everything-dependent phase shift, something that would not 
> have mattered in the measurement of phase noise.  The object of paper 112 
> was to remedy a 10 to 20 dB error in phase noise measurements.  The 
> critical words are in the lower left column of page 337, in the paragraph 
> beginning "If the mixer is terminated ...".
>
>
>   
Saturating the RF port has a similar effect.
If one is time stamping the zero crossings an increased zero crossing
slope is an advantage.
For relative phase measurements a trapezoidal beat frequency waveform
may be less useful.
>>> MiniCircuits AN-41-001 "FAQ about Phase Detectors" has on page 2 a 500 
>>>       
> ohm 
>   
>>> resistor to ground and a 5000 ohm resistor to the first filter 
>>>       
> capacitor, 
>   
>>> so the capacitor is isolated from the IF port by the resistors.
>>>
>>>
>>>       
>> I wouldn't take too much notice of that recommendation as I have little
>> confidence in the author's experience/knowledge.
>>     
>
> Well, OK, but:
>
> Stephen Kurtz says the same thing on the third column of the third page, a 
> bit above Figure 6.
>   

Off course with a capacitive IF port termination matching the RF and LO
ports becomes more critical as does the reverse isolation of the various
amplifiers driving the RF and LO ports.
It may be simpler in fact to use a level 17 mixer with high LO to RF and
LO to IF isolation with the RF port unsaturated as it relaxes the
reverse isolation specs for the isolation amplifiers.
> Nelson and Walls (paper 971), Figure 4, also shows the low pass filter 
> arranged to absorb the sum signal, not allowing it to be reflected back 
> into the mixer.
>
>  
>   
>>>> Supposedly an SRA-1, but some caution is in order as some 
>>>>         
>> statements as
>>     
>>>> to the effect of the input offset of an opamp based IF preamp in the
>>>> same application note were of dubious veracity unless one 
>>>>         
>> were to use an
>>     
>>>> inverting opamp input stage.
>>>>
>>>>         
>>> This issue was mentioned in another app note, but their main issue 
>>> appeared to be that the opamp bias currents could cause an offset.
>>>
>>>
>>>
>>>       
>> But the circuit they suggest has no effect on bias current induced
>> offset, the same current flows into the mixer and termination impedance
>> independent of the series resistance.
>>     
>
> You're right that the proposed remedy didn't make sense.  I don't know 
> that this is a big problem with modern opamps, especially FET input ones 
> (if needed).
>
>   
The only configuration for which it makes any sense is an inverting
input amplifier with a finite input voltage offset.
>> Yes, I should have said that when the 2 input signals are in quadrature,
>> any capacitive crosstalk will have little effect on the phase shift.
>>     
>
> Ah.  Because the capacitor coupling adds a second 90 degree shift, 
> bringing the total to 180 degrees.
>
> But crosstalk by ground coupling will be unaffected.  As will crosstalk by 
> transformer action.  Those boards are pretty crowded.
>
>
>   
Yes its better to measure it rather than relying too much on conjecture.
>> The AP192 has a somewhat higher interchannel isolation than that, the
>> interchannel crosstalk spec is about -120dB.
>> With a sufficiently large number of samples the its easy to see
>> artifacts as low as -140dBFS.
>>     
>
> Yep.  Seems like a very good card.
>
>
>  
>
>   
>> It's hard to find such Firewire systems without such unnecessary frills
>> (for this application) as high gain preamps.
>>     
>
> The AP192 has high-level inputs, but I don't know if this bypasses the 
> preamps, or attenuates.  Given their target market, I'd bet it bypasses.
>
>   
There are no preamps other than an external differential input amplifier
that translates the 4 Vrms FS inputs at the input connector to a level
that the ADC can handle.
The ADC chip itself has no preamps built in.
There have been numerous complaint about this by some audio nuts,
however for this application not having such amplifiers is ideal.
>   
>> The gain tempco and linearity of some variable gain audio preamps is
>> somewhat suspect.
>>     
>
> I would think that none of these cards has a good tempco of anything, 
> given the lack of necessity in their market.
>
> I would think that linearity would be quite good, given the horsepower 
> competitions on linearity.
>
>   
Since the 2 ADCs share the same reference their gain tracking tempco
should be quite good given that they use capacitors rather than
resistors within the ADCs.
>   
>>>> Other cards using AKM 24 bit ADCs should also be suitable.
>>>>
>>>>         
>>> Who is AKM?
>>>
>>>
>>>       
>> Asahi Kasei EKM
>>
>> http://www.asahi-kasei.co.jp/akm/en/
>>
>> http://www.asahi-kasei.co.jp/akm/en/product/proaudio.html
>>
>>     
>
> Thanks.  I'll look into their data.
>
>
>   
>>> 20 Log[ 2^24 ] = 144 dB, so something else will be the limit.
>>>
>>>
>>>
>>>       
>> Actual ENOB ~ 19 to 20 bits.
>>     
>
> Makes sense.  20 Log [ 2^19 ] = 114 dB.  Still plenty good enough.
>
>
>   
>>>> Ideally an external sound card with balanced  XLR inputs would be 
>>>>         
> best.
>
> Yes.
>
>
>
>   
>>>> HP produced a number of different phase comparators each with a
>>>> different type of phase detector.
>>>>         
>
> OK.  And the PLL folk must have a million designs.
>
>
>   
>>
>> Can alleviate it to some extent by driving a pair of such phase
>> detectors so that their outputs are in quadrature.
>> One just selects the phase detector output that is in the linear range.
>> The quadrature outputs also allow unambiguous assignment of the sign of
>> any phase change.
>>     
>
> The Symmetricom 5120A does something very clever to alleviate this 
> problem.  Explained in US patent 7,227,346 and "Direct-Digital Phase-Noise 
> Measurement"; J. Grove, J. Hein, J. Retta, P. Schweiger, W. Solbrig, and 
> S.R. Stein; 2004 IEEE International Ultrasonics, Ferroelectrics, and 
> Frequency Control Joint 50th Anniversary Conference, pages 287-291.
>
> Joe
>
>   
I've read the patent.

Bruce



From bruce.griffiths at xtra.co.nz  Thu Dec 11 01:50:18 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Thu, 11 Dec 2008 14:50:18 +1300
Subject: [time-nuts] Sub Pico Second Phase logger
In-Reply-To: <OFA014E6A7.7B5A0543-ON8525751C.0005C688-8525751C.0006EFD2@mck.us.ray.com>
References: <OFA014E6A7.7B5A0543-ON8525751C.0005C688-8525751C.0006EFD2@mck.us.ray.com>
Message-ID: <494071DA.3060807@xtra.co.nz>

Joseph M Gwinn wrote:
> Bruce,
>
>
>
> The low frequency noise of the components used in their unoptimised
> slope amplifiers is significantly smaller than that of a sound card.
>   
>
> Who is "their"?  But I would hazard that people designing for operation at 
> 1 Hz chose components with low flicker noise, to the extent then possible.
>
>   
JPL and others who repeated the same assumptions..
The amplifier choices were reasonably appropriate, however the
distribution of gain and filter time constants is not optimum.
At least they weren't as bad as their early isolation amplifier designs,
but no one seemed to know how to design low phase noise amplifiers at
that time, although at the time of the more recent and somewhat better
isolation amplifier design, they ought to have.
>   
>> A Collin's style optimised slope amplifier limiter may be useful for use
>> with a sound card (particularly the lower resolution ones) if one is
>> timetagging the beat frequency zero crossings.
>> Less slope gain will be required than when driving a counter input.
>> In the flicker noise region choice of beat frequency is relatively non
>> critical.
>>     
>
> With the vast amount of data available from a soundcard, I'd be tempted to 
> do a least squares three-parameter fit of a sine wave to the (decimated) 
> measured data and use only the resulting fitted parameters in subsequent 
> computations.  Like estimating where the zero crossings are.  Then the 
> noise averaging is over the entire fitting window, not just near zero 
> crossings.  (I have been following the talk of using a sin x over x 
> fitting function, but I don't know if this really works any better than a 
> simple fit to a sine, given this much data.)
>
> Joe
>
>   
Even a crude linear interpolation to locate the zero crossing shouldnt
be too bad.

The phase or zero crossing location of the fitted sine wave will be
relatively insensitive to noise near the beat frequency signal peaks.

If you save the sound card samples in a file, you (and others) can then
analyse the same data using different methods.

Bruce


From mfeher at eozinc.com  Thu Dec 11 02:05:19 2008
From: mfeher at eozinc.com (Mike Feher)
Date: Wed, 10 Dec 2008 21:05:19 -0500
Subject: [time-nuts] Sub Pico Second Phase logger
In-Reply-To: <49406F05.8030109@xtra.co.nz>
Message-ID: <015801c95b34$ed064d50$a08cc84b@eozpod1>

I am now, and actually have been, at the point where I just do not read
bottom line post/replies. Bruce has a lot of good information to share,
but, now, if I click on a post, and do not immediately see a response it
is just deleted. Maybe it will be my loss, but, technology as well as
the internet is evolving, and bottom line replies totally suck. - Mike

 
Mike B. Feher
EOZ Inc.
89 Arnold Blvd.
Howell, NJ, 07731
732-886-5960
908-902-3831 - cell
 
 

-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of Bruce Griffiths
Sent: Wednesday, December 10, 2008 8:38 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Sub Pico Second Phase logger

Joe
Joseph M Gwinn wrote:
> Bruce,
>
>   
>> Reflecting the sum frequency back into the mixer is actually
necessary
>> to reduce the noise at the IF port.
>> I believe that one of Agilent's simulation application notes mentions
>> this effect but I don't recall the actual application note number.
>> This will affect the mixer RF and IF port impedance so adding a
series
>> resistor may be required to improve the SWR.
>>     
>
> How big an effect is this?  Is the absolute noise decreased, or does
it 
> remain the same while the signal increase?
>
>   
With the same difference frequency IF port termination impedance,  noise
is actually decreased along with the mixer conversion loss.
However if the sound card input noise dominates reducing the mixer
effective output noise wont help.
> If I'm understanding Walls and Stein (paper 112) correctly, the
advantage 
> is because with the capacitor load the beatnote waveform approaches 
> square, thus increasing the zero-crossing speed and therefor the phase

> sensitivity.  This is no doubt true, but the question was if this also

> caused a small everything-dependent phase shift, something that would
not 
> have mattered in the measurement of phase noise.  The object of paper
112 
> was to remedy a 10 to 20 dB error in phase noise measurements.  The 
> critical words are in the lower left column of page 337, in the
paragraph 
> beginning "If the mixer is terminated ...".
>
>
>   
Saturating the RF port has a similar effect.
If one is time stamping the zero crossings an increased zero crossing
slope is an advantage.
For relative phase measurements a trapezoidal beat frequency waveform
may be less useful.
>>> MiniCircuits AN-41-001 "FAQ about Phase Detectors" has on page 2 a
500 
>>>       
> ohm 
>   
>>> resistor to ground and a 5000 ohm resistor to the first filter 
>>>       
> capacitor, 
>   
>>> so the capacitor is isolated from the IF port by the resistors.
>>>
>>>
>>>       
>> I wouldn't take too much notice of that recommendation as I have
little
>> confidence in the author's experience/knowledge.
>>     
>
> Well, OK, but:
>
> Stephen Kurtz says the same thing on the third column of the third
page, a 
> bit above Figure 6.
>   

Off course with a capacitive IF port termination matching the RF and LO
ports becomes more critical as does the reverse isolation of the various
amplifiers driving the RF and LO ports.
It may be simpler in fact to use a level 17 mixer with high LO to RF and
LO to IF isolation with the RF port unsaturated as it relaxes the
reverse isolation specs for the isolation amplifiers.
> Nelson and Walls (paper 971), Figure 4, also shows the low pass filter

> arranged to absorb the sum signal, not allowing it to be reflected
back 
> into the mixer.
>
>  
>   
>>>> Supposedly an SRA-1, but some caution is in order as some 
>>>>         
>> statements as
>>     
>>>> to the effect of the input offset of an opamp based IF preamp in
the
>>>> same application note were of dubious veracity unless one 
>>>>         
>> were to use an
>>     
>>>> inverting opamp input stage.
>>>>
>>>>         
>>> This issue was mentioned in another app note, but their main issue 
>>> appeared to be that the opamp bias currents could cause an offset.
>>>
>>>
>>>
>>>       
>> But the circuit they suggest has no effect on bias current induced
>> offset, the same current flows into the mixer and termination
impedance
>> independent of the series resistance.
>>     
>
> You're right that the proposed remedy didn't make sense.  I don't know

> that this is a big problem with modern opamps, especially FET input
ones 
> (if needed).
>
>   
The only configuration for which it makes any sense is an inverting
input amplifier with a finite input voltage offset.
>> Yes, I should have said that when the 2 input signals are in
quadrature,
>> any capacitive crosstalk will have little effect on the phase shift.
>>     
>
> Ah.  Because the capacitor coupling adds a second 90 degree shift, 
> bringing the total to 180 degrees.
>
> But crosstalk by ground coupling will be unaffected.  As will
crosstalk by 
> transformer action.  Those boards are pretty crowded.
>
>
>   
Yes its better to measure it rather than relying too much on conjecture.
>> The AP192 has a somewhat higher interchannel isolation than that, the
>> interchannel crosstalk spec is about -120dB.
>> With a sufficiently large number of samples the its easy to see
>> artifacts as low as -140dBFS.
>>     
>
> Yep.  Seems like a very good card.
>
>
>  
>
>   
>> It's hard to find such Firewire systems without such unnecessary
frills
>> (for this application) as high gain preamps.
>>     
>
> The AP192 has high-level inputs, but I don't know if this bypasses the

> preamps, or attenuates.  Given their target market, I'd bet it
bypasses.
>
>   
There are no preamps other than an external differential input amplifier
that translates the 4 Vrms FS inputs at the input connector to a level
that the ADC can handle.
The ADC chip itself has no preamps built in.
There have been numerous complaint about this by some audio nuts,
however for this application not having such amplifiers is ideal.
>   
>> The gain tempco and linearity of some variable gain audio preamps is
>> somewhat suspect.
>>     
>
> I would think that none of these cards has a good tempco of anything, 
> given the lack of necessity in their market.
>
> I would think that linearity would be quite good, given the horsepower

> competitions on linearity.
>
>   
Since the 2 ADCs share the same reference their gain tracking tempco
should be quite good given that they use capacitors rather than
resistors within the ADCs.
>   
>>>> Other cards using AKM 24 bit ADCs should also be suitable.
>>>>
>>>>         
>>> Who is AKM?
>>>
>>>
>>>       
>> Asahi Kasei EKM
>>
>> http://www.asahi-kasei.co.jp/akm/en/
>>
>> http://www.asahi-kasei.co.jp/akm/en/product/proaudio.html
>>
>>     
>
> Thanks.  I'll look into their data.
>
>
>   
>>> 20 Log[ 2^24 ] = 144 dB, so something else will be the limit.
>>>
>>>
>>>
>>>       
>> Actual ENOB ~ 19 to 20 bits.
>>     
>
> Makes sense.  20 Log [ 2^19 ] = 114 dB.  Still plenty good enough.
>
>
>   
>>>> Ideally an external sound card with balanced  XLR inputs would be 
>>>>         
> best.
>
> Yes.
>
>
>
>   
>>>> HP produced a number of different phase comparators each with a
>>>> different type of phase detector.
>>>>         
>
> OK.  And the PLL folk must have a million designs.
>
>
>   
>>
>> Can alleviate it to some extent by driving a pair of such phase
>> detectors so that their outputs are in quadrature.
>> One just selects the phase detector output that is in the linear
range.
>> The quadrature outputs also allow unambiguous assignment of the sign
of
>> any phase change.
>>     
>
> The Symmetricom 5120A does something very clever to alleviate this 
> problem.  Explained in US patent 7,227,346 and "Direct-Digital
Phase-Noise 
> Measurement"; J. Grove, J. Hein, J. Retta, P. Schweiger, W. Solbrig,
and 
> S.R. Stein; 2004 IEEE International Ultrasonics, Ferroelectrics, and 
> Frequency Control Joint 50th Anniversary Conference, pages 287-291.
>
> Joe
>
>   
I've read the patent.

Bruce


_______________________________________________
time-nuts mailing list -- time-nuts at febo.com
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.



From gwinn at raytheon.com  Thu Dec 11 02:27:27 2008
From: gwinn at raytheon.com (Joseph M Gwinn)
Date: Wed, 10 Dec 2008 21:27:27 -0500
Subject: [time-nuts] Sub Pico Second Phase logger (Posting Style)
In-Reply-To: <015801c95b34$ed064d50$a08cc84b@eozpod1>
Message-ID: <OF5604B429.83466235-ON8525751C.000CFFCE-8525751C.000D7F5A@mck.us.ray.com>

Let's have a top-posting versus bottom-posting fight! 

But we're too late, it's already been done: 

<http://en.wikipedia.org/wiki/Posting_style>

<http://allmyfaqs.net/faq.pl?Top-posting_or_bottom-posting>

And so on.  Many times.

Joe




"Mike Feher" <mfeher at eozinc.com> 
Sent by: time-nuts-bounces at febo.com
12/10/2008 09:06 PM
Please respond to
Discussion of precise time and frequency measurement <time-nuts at febo.com>


To
"'Discussion of precise time and frequency measurement'" 
<time-nuts at febo.com>
cc

Subject
Re: [time-nuts] Sub Pico Second Phase logger






I am now, and actually have been, at the point where I just do not read
bottom line post/replies. Bruce has a lot of good information to share,
but, now, if I click on a post, and do not immediately see a response it
is just deleted. Maybe it will be my loss, but, technology as well as
the internet is evolving, and bottom line replies totally suck. - Mike

 
Mike B. Feher
EOZ Inc.
89 Arnold Blvd.
Howell, NJ, 07731
732-886-5960
908-902-3831 - cell
 
 

-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of Bruce Griffiths
Sent: Wednesday, December 10, 2008 8:38 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Sub Pico Second Phase logger

Joe
Joseph M Gwinn wrote:
> Bruce,
>
> 
>> Reflecting the sum frequency back into the mixer is actually
necessary
>> to reduce the noise at the IF port.
>> I believe that one of Agilent's simulation application notes mentions
>> this effect but I don't recall the actual application note number.
>> This will affect the mixer RF and IF port impedance so adding a
series
>> resistor may be required to improve the SWR.
>> 
>
> How big an effect is this?  Is the absolute noise decreased, or does
it 
> remain the same while the signal increase?
>
> 
With the same difference frequency IF port termination impedance,  noise
is actually decreased along with the mixer conversion loss.
However if the sound card input noise dominates reducing the mixer
effective output noise wont help.
> If I'm understanding Walls and Stein (paper 112) correctly, the
advantage 
> is because with the capacitor load the beatnote waveform approaches 
> square, thus increasing the zero-crossing speed and therefor the phase

> sensitivity.  This is no doubt true, but the question was if this also

> caused a small everything-dependent phase shift, something that would
not 
> have mattered in the measurement of phase noise.  The object of paper
112 
> was to remedy a 10 to 20 dB error in phase noise measurements.  The 
> critical words are in the lower left column of page 337, in the
paragraph 
> beginning "If the mixer is terminated ...".
>
>
> 
Saturating the RF port has a similar effect.
If one is time stamping the zero crossings an increased zero crossing
slope is an advantage.
For relative phase measurements a trapezoidal beat frequency waveform
may be less useful.
>>> MiniCircuits AN-41-001 "FAQ about Phase Detectors" has on page 2 a
500 
>>> 
> ohm 
> 
>>> resistor to ground and a 5000 ohm resistor to the first filter 
>>> 
> capacitor, 
> 
>>> so the capacitor is isolated from the IF port by the resistors.
>>>
>>>
>>> 
>> I wouldn't take too much notice of that recommendation as I have
little
>> confidence in the author's experience/knowledge.
>> 
>
> Well, OK, but:
>
> Stephen Kurtz says the same thing on the third column of the third
page, a 
> bit above Figure 6.
> 

Off course with a capacitive IF port termination matching the RF and LO
ports becomes more critical as does the reverse isolation of the various
amplifiers driving the RF and LO ports.
It may be simpler in fact to use a level 17 mixer with high LO to RF and
LO to IF isolation with the RF port unsaturated as it relaxes the
reverse isolation specs for the isolation amplifiers.
> Nelson and Walls (paper 971), Figure 4, also shows the low pass filter

> arranged to absorb the sum signal, not allowing it to be reflected
back 
> into the mixer.
>
> 
> 
>>>> Supposedly an SRA-1, but some caution is in order as some 
>>>> 
>> statements as
>> 
>>>> to the effect of the input offset of an opamp based IF preamp in
the
>>>> same application note were of dubious veracity unless one 
>>>> 
>> were to use an
>> 
>>>> inverting opamp input stage.
>>>>
>>>> 
>>> This issue was mentioned in another app note, but their main issue 
>>> appeared to be that the opamp bias currents could cause an offset.
>>>
>>>
>>>
>>> 
>> But the circuit they suggest has no effect on bias current induced
>> offset, the same current flows into the mixer and termination
impedance
>> independent of the series resistance.
>> 
>
> You're right that the proposed remedy didn't make sense.  I don't know

> that this is a big problem with modern opamps, especially FET input
ones 
> (if needed).
>
> 
The only configuration for which it makes any sense is an inverting
input amplifier with a finite input voltage offset.
>> Yes, I should have said that when the 2 input signals are in
quadrature,
>> any capacitive crosstalk will have little effect on the phase shift.
>> 
>
> Ah.  Because the capacitor coupling adds a second 90 degree shift, 
> bringing the total to 180 degrees.
>
> But crosstalk by ground coupling will be unaffected.  As will
crosstalk by 
> transformer action.  Those boards are pretty crowded.
>
>
> 
Yes its better to measure it rather than relying too much on conjecture.
>> The AP192 has a somewhat higher interchannel isolation than that, the
>> interchannel crosstalk spec is about -120dB.
>> With a sufficiently large number of samples the its easy to see
>> artifacts as low as -140dBFS.
>> 
>
> Yep.  Seems like a very good card.
>
>
> 
>
> 
>> It's hard to find such Firewire systems without such unnecessary
frills
>> (for this application) as high gain preamps.
>> 
>
> The AP192 has high-level inputs, but I don't know if this bypasses the

> preamps, or attenuates.  Given their target market, I'd bet it
bypasses.
>
> 
There are no preamps other than an external differential input amplifier
that translates the 4 Vrms FS inputs at the input connector to a level
that the ADC can handle.
The ADC chip itself has no preamps built in.
There have been numerous complaint about this by some audio nuts,
however for this application not having such amplifiers is ideal.
> 
>> The gain tempco and linearity of some variable gain audio preamps is
>> somewhat suspect.
>> 
>
> I would think that none of these cards has a good tempco of anything, 
> given the lack of necessity in their market.
>
> I would think that linearity would be quite good, given the horsepower

> competitions on linearity.
>
> 
Since the 2 ADCs share the same reference their gain tracking tempco
should be quite good given that they use capacitors rather than
resistors within the ADCs.
> 
>>>> Other cards using AKM 24 bit ADCs should also be suitable.
>>>>
>>>> 
>>> Who is AKM?
>>>
>>>
>>> 
>> Asahi Kasei EKM
>>
>> http://www.asahi-kasei.co.jp/akm/en/
>>
>> http://www.asahi-kasei.co.jp/akm/en/product/proaudio.html
>>
>> 
>
> Thanks.  I'll look into their data.
>
>
> 
>>> 20 Log[ 2^24 ] = 144 dB, so something else will be the limit.
>>>
>>>
>>>
>>> 
>> Actual ENOB ~ 19 to 20 bits.
>> 
>
> Makes sense.  20 Log [ 2^19 ] = 114 dB.  Still plenty good enough.
>
>
> 
>>>> Ideally an external sound card with balanced  XLR inputs would be 
>>>> 
> best.
>
> Yes.
>
>
>
> 
>>>> HP produced a number of different phase comparators each with a
>>>> different type of phase detector.
>>>> 
>
> OK.  And the PLL folk must have a million designs.
>
>
> 
>>
>> Can alleviate it to some extent by driving a pair of such phase
>> detectors so that their outputs are in quadrature.
>> One just selects the phase detector output that is in the linear
range.
>> The quadrature outputs also allow unambiguous assignment of the sign
of
>> any phase change.
>> 
>
> The Symmetricom 5120A does something very clever to alleviate this 
> problem.  Explained in US patent 7,227,346 and "Direct-Digital
Phase-Noise 
> Measurement"; J. Grove, J. Hein, J. Retta, P. Schweiger, W. Solbrig,
and 
> S.R. Stein; 2004 IEEE International Ultrasonics, Ferroelectrics, and 
> Frequency Control Joint 50th Anniversary Conference, pages 287-291.
>
> Joe
>
> 
I've read the patent.

Bruce


_______________________________________________
time-nuts mailing list -- time-nuts at febo.com
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.


_______________________________________________
time-nuts mailing list -- time-nuts at febo.com
To unsubscribe, go to 
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.






From mfeher at eozinc.com  Thu Dec 11 02:36:37 2008
From: mfeher at eozinc.com (Mike Feher)
Date: Wed, 10 Dec 2008 21:36:37 -0500
Subject: [time-nuts] Sub Pico Second Phase logger (Posting Style)
In-Reply-To: <OF5604B429.83466235-ON8525751C.000CFFCE-8525751C.000D7F5A@mck.us.ray.com>
Message-ID: <016001c95b39$4cd2d9c0$a08cc84b@eozpod1>

I do not give a shit about a fight or Wiki. I was only stating my
position. BTW, good thing you stated your post on top, otherwise I would
not have seen it :). - Mike


 
Mike B. Feher
EOZ Inc.
89 Arnold Blvd.
Howell, NJ, 07731
732-886-5960
908-902-3831 - cell
 
 

-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of Joseph M Gwinn
Sent: Wednesday, December 10, 2008 9:27 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Sub Pico Second Phase logger (Posting Style)

Let's have a top-posting versus bottom-posting fight! 

But we're too late, it's already been done: 

<http://en.wikipedia.org/wiki/Posting_style>

<http://allmyfaqs.net/faq.pl?Top-posting_or_bottom-posting>

And so on.  Many times.

Joe




"Mike Feher" <mfeher at eozinc.com> 
Sent by: time-nuts-bounces at febo.com
12/10/2008 09:06 PM
Please respond to
Discussion of precise time and frequency measurement
<time-nuts at febo.com>


To
"'Discussion of precise time and frequency measurement'" 
<time-nuts at febo.com>
cc

Subject
Re: [time-nuts] Sub Pico Second Phase logger






I am now, and actually have been, at the point where I just do not read
bottom line post/replies. Bruce has a lot of good information to share,
but, now, if I click on a post, and do not immediately see a response it
is just deleted. Maybe it will be my loss, but, technology as well as
the internet is evolving, and bottom line replies totally suck. - Mike

 
Mike B. Feher
EOZ Inc.
89 Arnold Blvd.
Howell, NJ, 07731
732-886-5960
908-902-3831 - cell
 
 

-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of Bruce Griffiths
Sent: Wednesday, December 10, 2008 8:38 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Sub Pico Second Phase logger

Joe
Joseph M Gwinn wrote:
> Bruce,
>
> 
>> Reflecting the sum frequency back into the mixer is actually
necessary
>> to reduce the noise at the IF port.
>> I believe that one of Agilent's simulation application notes mentions
>> this effect but I don't recall the actual application note number.
>> This will affect the mixer RF and IF port impedance so adding a
series
>> resistor may be required to improve the SWR.
>> 
>
> How big an effect is this?  Is the absolute noise decreased, or does
it 
> remain the same while the signal increase?
>
> 
With the same difference frequency IF port termination impedance,  noise
is actually decreased along with the mixer conversion loss.
However if the sound card input noise dominates reducing the mixer
effective output noise wont help.
> If I'm understanding Walls and Stein (paper 112) correctly, the
advantage 
> is because with the capacitor load the beatnote waveform approaches 
> square, thus increasing the zero-crossing speed and therefor the phase

> sensitivity.  This is no doubt true, but the question was if this also

> caused a small everything-dependent phase shift, something that would
not 
> have mattered in the measurement of phase noise.  The object of paper
112 
> was to remedy a 10 to 20 dB error in phase noise measurements.  The 
> critical words are in the lower left column of page 337, in the
paragraph 
> beginning "If the mixer is terminated ...".
>
>
> 
Saturating the RF port has a similar effect.
If one is time stamping the zero crossings an increased zero crossing
slope is an advantage.
For relative phase measurements a trapezoidal beat frequency waveform
may be less useful.
>>> MiniCircuits AN-41-001 "FAQ about Phase Detectors" has on page 2 a
500 
>>> 
> ohm 
> 
>>> resistor to ground and a 5000 ohm resistor to the first filter 
>>> 
> capacitor, 
> 
>>> so the capacitor is isolated from the IF port by the resistors.
>>>
>>>
>>> 
>> I wouldn't take too much notice of that recommendation as I have
little
>> confidence in the author's experience/knowledge.
>> 
>
> Well, OK, but:
>
> Stephen Kurtz says the same thing on the third column of the third
page, a 
> bit above Figure 6.
> 

Off course with a capacitive IF port termination matching the RF and LO
ports becomes more critical as does the reverse isolation of the various
amplifiers driving the RF and LO ports.
It may be simpler in fact to use a level 17 mixer with high LO to RF and
LO to IF isolation with the RF port unsaturated as it relaxes the
reverse isolation specs for the isolation amplifiers.
> Nelson and Walls (paper 971), Figure 4, also shows the low pass filter

> arranged to absorb the sum signal, not allowing it to be reflected
back 
> into the mixer.
>
> 
> 
>>>> Supposedly an SRA-1, but some caution is in order as some 
>>>> 
>> statements as
>> 
>>>> to the effect of the input offset of an opamp based IF preamp in
the
>>>> same application note were of dubious veracity unless one 
>>>> 
>> were to use an
>> 
>>>> inverting opamp input stage.
>>>>
>>>> 
>>> This issue was mentioned in another app note, but their main issue 
>>> appeared to be that the opamp bias currents could cause an offset.
>>>
>>>
>>>
>>> 
>> But the circuit they suggest has no effect on bias current induced
>> offset, the same current flows into the mixer and termination
impedance
>> independent of the series resistance.
>> 
>
> You're right that the proposed remedy didn't make sense.  I don't know

> that this is a big problem with modern opamps, especially FET input
ones 
> (if needed).
>
> 
The only configuration for which it makes any sense is an inverting
input amplifier with a finite input voltage offset.
>> Yes, I should have said that when the 2 input signals are in
quadrature,
>> any capacitive crosstalk will have little effect on the phase shift.
>> 
>
> Ah.  Because the capacitor coupling adds a second 90 degree shift, 
> bringing the total to 180 degrees.
>
> But crosstalk by ground coupling will be unaffected.  As will
crosstalk by 
> transformer action.  Those boards are pretty crowded.
>
>
> 
Yes its better to measure it rather than relying too much on conjecture.
>> The AP192 has a somewhat higher interchannel isolation than that, the
>> interchannel crosstalk spec is about -120dB.
>> With a sufficiently large number of samples the its easy to see
>> artifacts as low as -140dBFS.
>> 
>
> Yep.  Seems like a very good card.
>
>
> 
>
> 
>> It's hard to find such Firewire systems without such unnecessary
frills
>> (for this application) as high gain preamps.
>> 
>
> The AP192 has high-level inputs, but I don't know if this bypasses the

> preamps, or attenuates.  Given their target market, I'd bet it
bypasses.
>
> 
There are no preamps other than an external differential input amplifier
that translates the 4 Vrms FS inputs at the input connector to a level
that the ADC can handle.
The ADC chip itself has no preamps built in.
There have been numerous complaint about this by some audio nuts,
however for this application not having such amplifiers is ideal.
> 
>> The gain tempco and linearity of some variable gain audio preamps is
>> somewhat suspect.
>> 
>
> I would think that none of these cards has a good tempco of anything, 
> given the lack of necessity in their market.
>
> I would think that linearity would be quite good, given the horsepower

> competitions on linearity.
>
> 
Since the 2 ADCs share the same reference their gain tracking tempco
should be quite good given that they use capacitors rather than
resistors within the ADCs.
> 
>>>> Other cards using AKM 24 bit ADCs should also be suitable.
>>>>
>>>> 
>>> Who is AKM?
>>>
>>>
>>> 
>> Asahi Kasei EKM
>>
>> http://www.asahi-kasei.co.jp/akm/en/
>>
>> http://www.asahi-kasei.co.jp/akm/en/product/proaudio.html
>>
>> 
>
> Thanks.  I'll look into their data.
>
>
> 
>>> 20 Log[ 2^24 ] = 144 dB, so something else will be the limit.
>>>
>>>
>>>
>>> 
>> Actual ENOB ~ 19 to 20 bits.
>> 
>
> Makes sense.  20 Log [ 2^19 ] = 114 dB.  Still plenty good enough.
>
>
> 
>>>> Ideally an external sound card with balanced  XLR inputs would be 
>>>> 
> best.
>
> Yes.
>
>
>
> 
>>>> HP produced a number of different phase comparators each with a
>>>> different type of phase detector.
>>>> 
>
> OK.  And the PLL folk must have a million designs.
>
>
> 
>>
>> Can alleviate it to some extent by driving a pair of such phase
>> detectors so that their outputs are in quadrature.
>> One just selects the phase detector output that is in the linear
range.
>> The quadrature outputs also allow unambiguous assignment of the sign
of
>> any phase change.
>> 
>
> The Symmetricom 5120A does something very clever to alleviate this 
> problem.  Explained in US patent 7,227,346 and "Direct-Digital
Phase-Noise 
> Measurement"; J. Grove, J. Hein, J. Retta, P. Schweiger, W. Solbrig,
and 
> S.R. Stein; 2004 IEEE International Ultrasonics, Ferroelectrics, and 
> Frequency Control Joint 50th Anniversary Conference, pages 287-291.
>
> Joe
>
> 
I've read the patent.

Bruce


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From bruce.griffiths at xtra.co.nz  Thu Dec 11 03:32:19 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Thu, 11 Dec 2008 16:32:19 +1300
Subject: [time-nuts] Sub Pico Second Phase logger
In-Reply-To: <OFA014E6A7.7B5A0543-ON8525751C.0005C688-8525751C.0006EFD2@mck.us.ray.com>
References: <OFA014E6A7.7B5A0543-ON8525751C.0005C688-8525751C.0006EFD2@mck.us.ray.com>
Message-ID: <494089C3.6060902@xtra.co.nz>

Joe

A screen shot indicating the AP192 sound card noise level with nothing
connected to the inputs is attached.
Reference level is full scale (4Vrms).
Aside from the few discrete spurs which differ between both channels the
region from 1 - 10kHz is fairly quiet.
Technical Notes:

FFT bin equivalent noise bandwidth ~ 3Hz.
96 KSPS.

Bruce

-------------- next part --------------
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From sar10538 at gmail.com  Thu Dec 11 03:52:14 2008
From: sar10538 at gmail.com (Steve Rooke)
Date: Thu, 11 Dec 2008 16:52:14 +1300
Subject: [time-nuts] Sub Pico Second Phase logger (Posting Style)
In-Reply-To: <016001c95b39$4cd2d9c0$a08cc84b@eozpod1>
References: <OF5604B429.83466235-ON8525751C.000CFFCE-8525751C.000D7F5A@mck.us.ray.com>
	<016001c95b39$4cd2d9c0$a08cc84b@eozpod1>
Message-ID: <1231b6a80812101952i4d6df185k92cb2f186ed43cd4@mail.gmail.com>

You can blow out a candle but you can't blow out a fire...

2008/12/11 Mike Feher <mfeher at eozinc.com>:
> I do not give a shit about a fight or Wiki. I was only stating my
> position. BTW, good thing you stated your post on top, otherwise I would
> not have seen it :). - Mike
>
>
>
> Mike B. Feher
> EOZ Inc.
> 89 Arnold Blvd.
> Howell, NJ, 07731
> 732-886-5960
> 908-902-3831 - cell
>
>
>
> -----Original Message-----
> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
> Behalf Of Joseph M Gwinn
> Sent: Wednesday, December 10, 2008 9:27 PM
> To: Discussion of precise time and frequency measurement
> Subject: Re: [time-nuts] Sub Pico Second Phase logger (Posting Style)
>
> Let's have a top-posting versus bottom-posting fight!
>
> But we're too late, it's already been done:
>
> <http://en.wikipedia.org/wiki/Posting_style>
>
> <http://allmyfaqs.net/faq.pl?Top-posting_or_bottom-posting>
>
> And so on.  Many times.
>
> Joe
>
>
>
>
> "Mike Feher" <mfeher at eozinc.com>
> Sent by: time-nuts-bounces at febo.com
> 12/10/2008 09:06 PM
> Please respond to
> Discussion of precise time and frequency measurement
> <time-nuts at febo.com>
>
>
> To
> "'Discussion of precise time and frequency measurement'"
> <time-nuts at febo.com>
> cc
>
> Subject
> Re: [time-nuts] Sub Pico Second Phase logger
>
>
>
>
>
>
> I am now, and actually have been, at the point where I just do not read
> bottom line post/replies. Bruce has a lot of good information to share,
> but, now, if I click on a post, and do not immediately see a response it
> is just deleted. Maybe it will be my loss, but, technology as well as
> the internet is evolving, and bottom line replies totally suck. - Mike
>
>
> Mike B. Feher
> EOZ Inc.
> 89 Arnold Blvd.
> Howell, NJ, 07731
> 732-886-5960
> 908-902-3831 - cell
>
>
>
> -----Original Message-----
> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
> Behalf Of Bruce Griffiths
> Sent: Wednesday, December 10, 2008 8:38 PM
> To: Discussion of precise time and frequency measurement
> Subject: Re: [time-nuts] Sub Pico Second Phase logger
>
> Joe
> Joseph M Gwinn wrote:
>> Bruce,
>>
>>
>>> Reflecting the sum frequency back into the mixer is actually
> necessary
>>> to reduce the noise at the IF port.
>>> I believe that one of Agilent's simulation application notes mentions
>>> this effect but I don't recall the actual application note number.
>>> This will affect the mixer RF and IF port impedance so adding a
> series
>>> resistor may be required to improve the SWR.
>>>
>>
>> How big an effect is this?  Is the absolute noise decreased, or does
> it
>> remain the same while the signal increase?
>>
>>
> With the same difference frequency IF port termination impedance,  noise
> is actually decreased along with the mixer conversion loss.
> However if the sound card input noise dominates reducing the mixer
> effective output noise wont help.
>> If I'm understanding Walls and Stein (paper 112) correctly, the
> advantage
>> is because with the capacitor load the beatnote waveform approaches
>> square, thus increasing the zero-crossing speed and therefor the phase
>
>> sensitivity.  This is no doubt true, but the question was if this also
>
>> caused a small everything-dependent phase shift, something that would
> not
>> have mattered in the measurement of phase noise.  The object of paper
> 112
>> was to remedy a 10 to 20 dB error in phase noise measurements.  The
>> critical words are in the lower left column of page 337, in the
> paragraph
>> beginning "If the mixer is terminated ...".
>>
>>
>>
> Saturating the RF port has a similar effect.
> If one is time stamping the zero crossings an increased zero crossing
> slope is an advantage.
> For relative phase measurements a trapezoidal beat frequency waveform
> may be less useful.
>>>> MiniCircuits AN-41-001 "FAQ about Phase Detectors" has on page 2 a
> 500
>>>>
>> ohm
>>
>>>> resistor to ground and a 5000 ohm resistor to the first filter
>>>>
>> capacitor,
>>
>>>> so the capacitor is isolated from the IF port by the resistors.
>>>>
>>>>
>>>>
>>> I wouldn't take too much notice of that recommendation as I have
> little
>>> confidence in the author's experience/knowledge.
>>>
>>
>> Well, OK, but:
>>
>> Stephen Kurtz says the same thing on the third column of the third
> page, a
>> bit above Figure 6.
>>
>
> Off course with a capacitive IF port termination matching the RF and LO
> ports becomes more critical as does the reverse isolation of the various
> amplifiers driving the RF and LO ports.
> It may be simpler in fact to use a level 17 mixer with high LO to RF and
> LO to IF isolation with the RF port unsaturated as it relaxes the
> reverse isolation specs for the isolation amplifiers.
>> Nelson and Walls (paper 971), Figure 4, also shows the low pass filter
>
>> arranged to absorb the sum signal, not allowing it to be reflected
> back
>> into the mixer.
>>
>>
>>
>>>>> Supposedly an SRA-1, but some caution is in order as some
>>>>>
>>> statements as
>>>
>>>>> to the effect of the input offset of an opamp based IF preamp in
> the
>>>>> same application note were of dubious veracity unless one
>>>>>
>>> were to use an
>>>
>>>>> inverting opamp input stage.
>>>>>
>>>>>
>>>> This issue was mentioned in another app note, but their main issue
>>>> appeared to be that the opamp bias currents could cause an offset.
>>>>
>>>>
>>>>
>>>>
>>> But the circuit they suggest has no effect on bias current induced
>>> offset, the same current flows into the mixer and termination
> impedance
>>> independent of the series resistance.
>>>
>>
>> You're right that the proposed remedy didn't make sense.  I don't know
>
>> that this is a big problem with modern opamps, especially FET input
> ones
>> (if needed).
>>
>>
> The only configuration for which it makes any sense is an inverting
> input amplifier with a finite input voltage offset.
>>> Yes, I should have said that when the 2 input signals are in
> quadrature,
>>> any capacitive crosstalk will have little effect on the phase shift.
>>>
>>
>> Ah.  Because the capacitor coupling adds a second 90 degree shift,
>> bringing the total to 180 degrees.
>>
>> But crosstalk by ground coupling will be unaffected.  As will
> crosstalk by
>> transformer action.  Those boards are pretty crowded.
>>
>>
>>
> Yes its better to measure it rather than relying too much on conjecture.
>>> The AP192 has a somewhat higher interchannel isolation than that, the
>>> interchannel crosstalk spec is about -120dB.
>>> With a sufficiently large number of samples the its easy to see
>>> artifacts as low as -140dBFS.
>>>
>>
>> Yep.  Seems like a very good card.
>>
>>
>>
>>
>>
>>> It's hard to find such Firewire systems without such unnecessary
> frills
>>> (for this application) as high gain preamps.
>>>
>>
>> The AP192 has high-level inputs, but I don't know if this bypasses the
>
>> preamps, or attenuates.  Given their target market, I'd bet it
> bypasses.
>>
>>
> There are no preamps other than an external differential input amplifier
> that translates the 4 Vrms FS inputs at the input connector to a level
> that the ADC can handle.
> The ADC chip itself has no preamps built in.
> There have been numerous complaint about this by some audio nuts,
> however for this application not having such amplifiers is ideal.
>>
>>> The gain tempco and linearity of some variable gain audio preamps is
>>> somewhat suspect.
>>>
>>
>> I would think that none of these cards has a good tempco of anything,
>> given the lack of necessity in their market.
>>
>> I would think that linearity would be quite good, given the horsepower
>
>> competitions on linearity.
>>
>>
> Since the 2 ADCs share the same reference their gain tracking tempco
> should be quite good given that they use capacitors rather than
> resistors within the ADCs.
>>
>>>>> Other cards using AKM 24 bit ADCs should also be suitable.
>>>>>
>>>>>
>>>> Who is AKM?
>>>>
>>>>
>>>>
>>> Asahi Kasei EKM
>>>
>>> http://www.asahi-kasei.co.jp/akm/en/
>>>
>>> http://www.asahi-kasei.co.jp/akm/en/product/proaudio.html
>>>
>>>
>>
>> Thanks.  I'll look into their data.
>>
>>
>>
>>>> 20 Log[ 2^24 ] = 144 dB, so something else will be the limit.
>>>>
>>>>
>>>>
>>>>
>>> Actual ENOB ~ 19 to 20 bits.
>>>
>>
>> Makes sense.  20 Log [ 2^19 ] = 114 dB.  Still plenty good enough.
>>
>>
>>
>>>>> Ideally an external sound card with balanced  XLR inputs would be
>>>>>
>> best.
>>
>> Yes.
>>
>>
>>
>>
>>>>> HP produced a number of different phase comparators each with a
>>>>> different type of phase detector.
>>>>>
>>
>> OK.  And the PLL folk must have a million designs.
>>
>>
>>
>>>
>>> Can alleviate it to some extent by driving a pair of such phase
>>> detectors so that their outputs are in quadrature.
>>> One just selects the phase detector output that is in the linear
> range.
>>> The quadrature outputs also allow unambiguous assignment of the sign
> of
>>> any phase change.
>>>
>>
>> The Symmetricom 5120A does something very clever to alleviate this
>> problem.  Explained in US patent 7,227,346 and "Direct-Digital
> Phase-Noise
>> Measurement"; J. Grove, J. Hein, J. Retta, P. Schweiger, W. Solbrig,
> and
>> S.R. Stein; 2004 IEEE International Ultrasonics, Ferroelectrics, and
>> Frequency Control Joint 50th Anniversary Conference, pages 287-291.
>>
>> Joe
>>
>>
> I've read the patent.
>
> Bruce
>
>
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>
>
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>
>
>
>
>
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>
>
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>



-- 
Steve Rooke - ZL3TUV & G8KVD
Omnium finis imminet


From holrum at hotmail.com  Thu Dec 11 04:55:02 2008
From: holrum at hotmail.com (Mark Sims)
Date: Thu, 11 Dec 2008 04:55:02 +0000
Subject: [time-nuts] Sub Pico Second Phase logger (Posting Style)
In-Reply-To: <mailman.260.1228963012.2499.time-nuts@febo.com>
References: <mailman.260.1228963012.2499.time-nuts@febo.com>
Message-ID: <BLU125-W345D2443217FD044909AC8CEF80@phx.gbl>


With enough hot air you can...  now if I can only get Billly G and Microslosh to insert CR LF into a Hotmail message...> You can blow out a candle but you can't blow out a fire...

_________________________________________________________________
Send e-mail faster without improving your typing skills.
http://windowslive.com/Explore/hotmail?ocid=TXT_TAGLM_WL_hotmail_acq_speed_122008

From sar10538 at gmail.com  Thu Dec 11 05:02:43 2008
From: sar10538 at gmail.com (Steve Rooke)
Date: Thu, 11 Dec 2008 18:02:43 +1300
Subject: [time-nuts] Sub Pico Second Phase logger (Posting Style)
In-Reply-To: <BLU125-W345D2443217FD044909AC8CEF80@phx.gbl>
References: <mailman.260.1228963012.2499.time-nuts@febo.com>
	<BLU125-W345D2443217FD044909AC8CEF80@phx.gbl>
Message-ID: <1231b6a80812102102r234ddb1aw5d44f1fd148491d@mail.gmail.com>

2008/12/11 Mark Sims <holrum at hotmail.com>:
>
> With enough hot air you can...  now if I can only get Billly G and Microslosh to insert CR LF into a Hotmail message...> You can blow out a candle but you can't blow out a fire...

Does this qualify as top-posting or some new form of posting, perhaps
it should be called pre-posting, insert-inline-posting or just
posting-early-for-Christmas.

Now, CR LF, why do you need so many chars to delineate a line, surely
LF should be enough :-)

73, Steve
-- 
Steve Rooke - ZL3TUV & G8KVD
Omnium finis imminet


From holrum at hotmail.com  Thu Dec 11 05:23:03 2008
From: holrum at hotmail.com (Mark Sims)
Date: Thu, 11 Dec 2008 05:23:03 +0000
Subject: [time-nuts] Sub Pico Second Phase logger (Posting Style)
In-Reply-To: <mailman.260.1228963012.2499.time-nuts@febo.com>
References: <mailman.260.1228963012.2499.time-nuts@febo.com>
Message-ID: <BLU125-W1ABAEA2289D0CFA857A27CEF80@phx.gbl>


It appears that both Microsoft and Ebay have taken to hiring illiterate preschoolers for programmers... and fired their quality control/testing staff.  Hotmail has apparently forbidden the use use either CR or LF in any of their messages.  And Ebay's latest changes have made most of their listings unusable to Apple users...  assuming you can even get them to load without generating a NSURLE error.2008/12/11 Mark Sims <holrum at hotmail.com>:
>
> With enough hot air you can...  now if I can only get Billly G and Microslosh to insert CR LF into a Hotmail message...> You can blow out a candle but you can't blow out a fire...

Does this qualify as top-posting or some new form of posting, perhaps
it should be called pre-posting, insert-inline-posting or just
posting-early-for-Christmas.

Now, CR LF, why do you need so many chars to delineate a line, surely
LF should be enough :-)

73, Steve
-- 
Steve Rooke - ZL3TUV & G8KVD
Omnium finis imminet

_________________________________________________________________
Send e-mail faster without improving your typing skills.
http://windowslive.com/Explore/hotmail?ocid=TXT_TAGLM_WL_hotmail_acq_speed_122008

From wb6bnq at cox.net  Thu Dec 11 05:42:55 2008
From: wb6bnq at cox.net (WB6BNQ)
Date: Wed, 10 Dec 2008 21:42:55 -0800
Subject: [time-nuts] Bruce's postings {was} Sub Pico Second Phase logger
References: <015801c95b34$ed064d50$a08cc84b@eozpod1>
Message-ID: <4940A85F.1C37D0E2@cox.net>

Mike,

The biggest problem with Bruce's postings is that he does not leave any damn
space between the OLD data and his NEW data.  So you spend an unusual amount of
time mentally separating what is going on.  Very frustrating !

Bill....WB6BNQ


Mike Feher wrote:

> I am now, and actually have been, at the point where I just do not read
> bottom line post/replies. Bruce has a lot of good information to share,
> but, now, if I click on a post, and do not immediately see a response it
> is just deleted. Maybe it will be my loss, but, technology as well as
> the internet is evolving, and bottom line replies totally suck. - Mike
>
>
> Mike B. Feher
> EOZ Inc.
> 89 Arnold Blvd.
> Howell, NJ, 07731
> 732-886-5960
> 908-902-3831 - cell
>
>
>
> -----Original Message-----
> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
> Behalf Of Bruce Griffiths
> Sent: Wednesday, December 10, 2008 8:38 PM
> To: Discussion of precise time and frequency measurement
> Subject: Re: [time-nuts] Sub Pico Second Phase logger
>
> Joe
> Joseph M Gwinn wrote:
> > Bruce,
> >
> >
> >> Reflecting the sum frequency back into the mixer is actually
> necessary
> >> to reduce the noise at the IF port.
> >> I believe that one of Agilent's simulation application notes mentions
> >> this effect but I don't recall the actual application note number.
> >> This will affect the mixer RF and IF port impedance so adding a
> series
> >> resistor may be required to improve the SWR.
> >>
> >
> > How big an effect is this?  Is the absolute noise decreased, or does
> it
> > remain the same while the signal increase?
> >
> >
> With the same difference frequency IF port termination impedance,  noise
> is actually decreased along with the mixer conversion loss.
> However if the sound card input noise dominates reducing the mixer
> effective output noise wont help.
> > If I'm understanding Walls and Stein (paper 112) correctly, the
> advantage
> > is because with the capacitor load the beatnote waveform approaches
> > square, thus increasing the zero-crossing speed and therefor the phase
>
> > sensitivity.  This is no doubt true, but the question was if this also
>
> > caused a small everything-dependent phase shift, something that would
> not
> > have mattered in the measurement of phase noise.  The object of paper
> 112
> > was to remedy a 10 to 20 dB error in phase noise measurements.  The
> > critical words are in the lower left column of page 337, in the
> paragraph
> > beginning "If the mixer is terminated ...".
> >
> >
> >
> Saturating the RF port has a similar effect.
> If one is time stamping the zero crossings an increased zero crossing
> slope is an advantage.
> For relative phase measurements a trapezoidal beat frequency waveform
> may be less useful.
> >>> MiniCircuits AN-41-001 "FAQ about Phase Detectors" has on page 2 a
> 500
> >>>
> > ohm
> >
> >>> resistor to ground and a 5000 ohm resistor to the first filter
> >>>
> > capacitor,
> >
> >>> so the capacitor is isolated from the IF port by the resistors.
> >>>
> >>>
> >>>
> >> I wouldn't take too much notice of that recommendation as I have
> little
> >> confidence in the author's experience/knowledge.
> >>
> >
> > Well, OK, but:
> >
> > Stephen Kurtz says the same thing on the third column of the third
> page, a
> > bit above Figure 6.
> >
>
> Off course with a capacitive IF port termination matching the RF and LO
> ports becomes more critical as does the reverse isolation of the various
> amplifiers driving the RF and LO ports.
> It may be simpler in fact to use a level 17 mixer with high LO to RF and
> LO to IF isolation with the RF port unsaturated as it relaxes the
> reverse isolation specs for the isolation amplifiers.
> > Nelson and Walls (paper 971), Figure 4, also shows the low pass filter
>
> > arranged to absorb the sum signal, not allowing it to be reflected
> back
> > into the mixer.
> >
> >
> >
> >>>> Supposedly an SRA-1, but some caution is in order as some
> >>>>
> >> statements as
> >>
> >>>> to the effect of the input offset of an opamp based IF preamp in
> the
> >>>> same application note were of dubious veracity unless one
> >>>>
> >> were to use an
> >>
> >>>> inverting opamp input stage.
> >>>>
> >>>>
> >>> This issue was mentioned in another app note, but their main issue
> >>> appeared to be that the opamp bias currents could cause an offset.
> >>>
> >>>
> >>>
> >>>
> >> But the circuit they suggest has no effect on bias current induced
> >> offset, the same current flows into the mixer and termination
> impedance
> >> independent of the series resistance.
> >>
> >
> > You're right that the proposed remedy didn't make sense.  I don't know
>
> > that this is a big problem with modern opamps, especially FET input
> ones
> > (if needed).
> >
> >
> The only configuration for which it makes any sense is an inverting
> input amplifier with a finite input voltage offset.
> >> Yes, I should have said that when the 2 input signals are in
> quadrature,
> >> any capacitive crosstalk will have little effect on the phase shift.
> >>
> >
> > Ah.  Because the capacitor coupling adds a second 90 degree shift,
> > bringing the total to 180 degrees.
> >
> > But crosstalk by ground coupling will be unaffected.  As will
> crosstalk by
> > transformer action.  Those boards are pretty crowded.
> >
> >
> >
> Yes its better to measure it rather than relying too much on conjecture.
> >> The AP192 has a somewhat higher interchannel isolation than that, the
> >> interchannel crosstalk spec is about -120dB.
> >> With a sufficiently large number of samples the its easy to see
> >> artifacts as low as -140dBFS.
> >>
> >
> > Yep.  Seems like a very good card.
> >
> >
> >
> >
> >
> >> It's hard to find such Firewire systems without such unnecessary
> frills
> >> (for this application) as high gain preamps.
> >>
> >
> > The AP192 has high-level inputs, but I don't know if this bypasses the
>
> > preamps, or attenuates.  Given their target market, I'd bet it
> bypasses.
> >
> >
> There are no preamps other than an external differential input amplifier
> that translates the 4 Vrms FS inputs at the input connector to a level
> that the ADC can handle.
> The ADC chip itself has no preamps built in.
> There have been numerous complaint about this by some audio nuts,
> however for this application not having such amplifiers is ideal.
> >
> >> The gain tempco and linearity of some variable gain audio preamps is
> >> somewhat suspect.
> >>
> >
> > I would think that none of these cards has a good tempco of anything,
> > given the lack of necessity in their market.
> >
> > I would think that linearity would be quite good, given the horsepower
>
> > competitions on linearity.
> >
> >
> Since the 2 ADCs share the same reference their gain tracking tempco
> should be quite good given that they use capacitors rather than
> resistors within the ADCs.
> >
> >>>> Other cards using AKM 24 bit ADCs should also be suitable.
> >>>>
> >>>>
> >>> Who is AKM?
> >>>
> >>>
> >>>
> >> Asahi Kasei EKM
> >>
> >> http://www.asahi-kasei.co.jp/akm/en/
> >>
> >> http://www.asahi-kasei.co.jp/akm/en/product/proaudio.html
> >>
> >>
> >
> > Thanks.  I'll look into their data.
> >
> >
> >
> >>> 20 Log[ 2^24 ] = 144 dB, so something else will be the limit.
> >>>
> >>>
> >>>
> >>>
> >> Actual ENOB ~ 19 to 20 bits.
> >>
> >
> > Makes sense.  20 Log [ 2^19 ] = 114 dB.  Still plenty good enough.
> >
> >
> >
> >>>> Ideally an external sound card with balanced  XLR inputs would be
> >>>>
> > best.
> >
> > Yes.
> >
> >
> >
> >
> >>>> HP produced a number of different phase comparators each with a
> >>>> different type of phase detector.
> >>>>
> >
> > OK.  And the PLL folk must have a million designs.
> >
> >
> >
> >>
> >> Can alleviate it to some extent by driving a pair of such phase
> >> detectors so that their outputs are in quadrature.
> >> One just selects the phase detector output that is in the linear
> range.
> >> The quadrature outputs also allow unambiguous assignment of the sign
> of
> >> any phase change.
> >>
> >
> > The Symmetricom 5120A does something very clever to alleviate this
> > problem.  Explained in US patent 7,227,346 and "Direct-Digital
> Phase-Noise
> > Measurement"; J. Grove, J. Hein, J. Retta, P. Schweiger, W. Solbrig,
> and
> > S.R. Stein; 2004 IEEE International Ultrasonics, Ferroelectrics, and
> > Frequency Control Joint 50th Anniversary Conference, pages 287-291.
> >
> > Joe
> >
> >
> I've read the patent.
>
> Bruce
>
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.



From tvb at LeapSecond.com  Thu Dec 11 06:33:36 2008
From: tvb at LeapSecond.com (Tom Van Baak)
Date: Wed, 10 Dec 2008 22:33:36 -0800
Subject: [time-nuts] GPS signal simulator
References: <031201c95aa6$29c11340$6401a8c0@WSOffice>
Message-ID: <1632C3589DE343B8851EA4D882C9335D@pc52>

>    In my quest to keep improving my GPSDO, a simple test tool 
> that I find indispensable is a GPS 1PPS (or 100Hz) signal simulator 
> reference.  Others may also find this useful because it allows testing the 
> PLL & DO in their GPSDO to Cs type accuracy using a standard OCXO.

Warren,

There's been some discussion about a GPS simulator for the
purpose of playing with GPSDO algorithms a couple of times
on the list over the years.

But since you're making more progress than most have, here
is a nice pair of 400,000 (!) sample data sets for you to use:

http://www.leapsecond.com/pages/gpsdo-sim/

For playing with GPSDO, the character of the typical 1PPS is
very easy to model (it's basically a few ns of noise that nicely
averages down at 1 over tau out past a day) so going all the way
back to RF simulation of the GPS SV signal(s) might be overkill.

In any event, I found it much easier to just take real GPS 1PPS
data, and real OCXO data, and then simulate a GPSDO from
those two raw data sets. You can plot phase, frequency, ADEV
of both inputs and one output and see the GPSDO humps we
always talk about, etc.

/tvb




From warrensjmail-one at yahoo.com  Thu Dec 11 12:17:56 2008
From: warrensjmail-one at yahoo.com (WarrenS)
Date: Thu, 11 Dec 2008 04:17:56 -0800
Subject: [time-nuts]  GPS signal simulator
Message-ID: <014b01c95b8a$80557b30$6401a8c0@WSOffice>



>    In my quest to keep improving my GPSDO, a simple test tool 
> that I find indispensable is a GPS 1PPS (or 100Hz) signal simulator 
> reference.  Others may also find this useful because it allows testing the 
> PLL & DO in their GPSDO to Cs type accuracy using a standard OCXO.

Warren,

There's been some discussion about a GPS simulator for the
purpose of playing with GPSDO algorithms a couple of times
on the list over the years.

But since you're making more progress than most have, here
is a nice pair of 400,000 (!) sample data sets for you to use:

http://www.leapsecond.com/pages/gpsdo-sim/

For playing with GPSDO, the character of the typical 1PPS is
very easy to model (it's basically a few ns of noise that nicely
averages down at 1 over tau out past a day) so going all the way
back to RF simulation of the GPS SV signal(s) might be overkill.

In any event, I found it much easier to just take real GPS 1PPS
data, and real OCXO data, and then simulate a GPSDO from
those two raw data sets. You can plot phase, frequency, ADEV
of both inputs and one output and see the GPSDO humps we
always talk about, etc.

/tvb

****************** 
Tom

Thanks that should be very useful for software simulations.

The use I had in mind for the tool I described where for the next stage of testing. 
It can be used to test at the REAL Hardware level, using a 'perfect' GPS signal with 
no noise or with any type of desired controlled noise.
For example it is hard and time consuming to see how many ps of error 
your phase detector is adding or what the phase margin or noise gain is of the H/W PLL.
Is the power supply good enough or is it causing errors, etc 
When using real GPS data, the random noise will hide the advanced 
type of information you may want to take.
The other use of the Hardware simulator is for someone that wants to know how 
accurate their GPSDO is but does not have access to a source accurate enough 
to test their GPSDO.

WarrenS


From jgd at johngsbbq.com  Thu Dec 11 12:50:55 2008
From: jgd at johngsbbq.com (Neon John)
Date: Thu, 11 Dec 2008 07:50:55 -0500
Subject: [time-nuts] US Shipping Was huntron tracker advice
In-Reply-To: <1231b6a80811270055x2bbd2b0bhf610c39e0f67edb0@mail.gmail.com>
References: <1231b6a80811270021n405461cfy9b8d437a2978a13b@mail.gmail.com>
	<693057.30597.qm@web27103.mail.ukl.yahoo.com>
	<1231b6a80811270055x2bbd2b0bhf610c39e0f67edb0@mail.gmail.com>
Message-ID: <td22k45urf1v38jlt1j6r2gtm65ra9mup5@4ax.com>

On Thu, 27 Nov 2008 21:55:26 +1300, "Steve Rooke" <sar10538 at gmail.com> wrote:

>Hmmm... International Traffic in Arms Regulations, well I don't like
>to poke holes in that excuse but unless the US customs are REALLY
>paranoid, I can't see how most of the items I have tried to purchase
>would be covered under this. But, I suppose you could poke someone in
>the eye with a ball-point pen therefore it could be labled an an arm
>but I'm sure there are other reasons for most of refusals to ship
>outside the 48 States. It's not just a couple of dealers who take this
>position, it seems to be the case with a number of sellers sadly.

It is more than just the ITAR hassles.  There are hassles all around.  either
you lie at the post office about the value or you pay customs there.  The
paperwork takes time.  There is no legal recourse in the case of fraud.  Just
not worth the effort for most folks when they can sell their stuff here.

>
>What I need is a magic wormhole that runs from a US address and ends
>up in my home. Anyone got a design for one of these, sort of like a
>stargate :-)

Don't know about wormholes but there are people who do that, take receipt of
something you purchased and ship it to you.  I used to do that when I lived
next door to the post office.  I charged a small fee to cover my labors and to
average out the PO fees other than postage.  Alas, the closest PO to me now is
about 40 miles.  Bet you could find other people to do that for you.

If you're dealing on sleazebay, why not put up a Wormhole for sale.  Describe
the services and let people make offers.  Sleazebay may pull it after a few
days but I bet you'd find someone.

John
--
John De Armond
See my website for my current email address
http://www.neon-john.com
http://www.johndearmond.com <-- best little blog on the net!
Tellico Plains, Occupied TN
I'm going crazy. Wanna come along?



From jgd at johngsbbq.com  Thu Dec 11 13:19:30 2008
From: jgd at johngsbbq.com (Neon John)
Date: Thu, 11 Dec 2008 08:19:30 -0500
Subject: [time-nuts] Voltage standards
In-Reply-To: <20081130.172754.-1540392776.imp@bsdimp.com>
References: <20081130.151328.1120076896.imp@bsdimp.com>
	<C5586E81.2FF3%James.P.Lux@jpl.nasa.gov>
	<20081130.172754.-1540392776.imp@bsdimp.com>
Message-ID: <ve42k41uk112tugr52ldi4qdlgmrlhs88h@4ax.com>

On Sun, 30 Nov 2008 17:27:54 -0700 (MST), "M. Warner Losh" <imp at bsdimp.com>
wrote:

>The thing that got me was the word 'really' in Bruce's statement.  It
>read like someone who had tried it, had limited success, but in the
>end wound up believing that while possible, it wasn't really
>practical.  After thinking that, I couldn't imagine that somebody on
>the list hadn't tried it for some reason or another over the years.

Well, before my fire I had a gamma spectrometer based on an LN2 cooled HpGe
crystal in my basement lab.  Right beside it was a similarly cooled SiLi
detector for alpha and X-ray spectroscopy.  What can I say?  I'm a nuke.
that's what we do.  I managed to save the Canberra MCA, though it's grossly
obsolete now, there being little USB dongles that do the job these days.

I have been coveting one of the later model HpGe detectors with the Sterling
refrigeration pump.  No more LN2 deliveries.  Kinda pricey on a retiree's
budget.

One of those things that I've always wanted to do was to lash together a
liquid air plant from, say, refrigeration parts.  Never had the time and the
funds at the same time.

John
--
John De Armond
See my website for my current email address
http://www.neon-john.com
http://www.johndearmond.com <-- best little blog on the net!
Tellico Plains, Occupied TN
You can't turn [MS] shovelware into reliable software by patching it a whole lot. -Marcus Ranum



From jgd at johngsbbq.com  Thu Dec 11 13:39:53 2008
From: jgd at johngsbbq.com (Neon John)
Date: Thu, 11 Dec 2008 08:39:53 -0500
Subject: [time-nuts] Voltage Standards
In-Reply-To: <49310C27.2000902@bellsouth.net>
References: <604DA6FE-2511-4CBB-8D1B-2758A3FA5C58@hughes.net>
	<49310C27.2000902@bellsouth.net>
Message-ID: <4d52k4lodh9aev08s941athgge5jnuhm05@4ax.com>

On Sat, 29 Nov 2008 03:32:23 -0600, Brian Kirby <kirbybq at bellsouth.net> wrote:


>Maybe we should consider coming up with a standard voltage reference as 
>a TAPR project.  We have a lot of good brainpower out here and it seems 
>a lot of experience available.

I think that this is a spectacular idea.  Actually, two standards would be
nice.  One low-ppm one for us "volt-nuts" (maybe this list ought to change
names to "standards-nuts" or "precision-nuts") and another good enough to
check 3.5 and 4.5 digit meters.  With all the cheap-spit Chicom DVMs on the
market, some of which don't even make a good SWAG, a cheap standard that any
ham or other nerd could afford would go a long way toward eliminating a LOT of
headaches for folks like us.

I answer numerous tech questions every day and one of the first questions I've
learned to ask when voltage measurements are involved is "what kind of DVM are
you using?"  If it's a sub $50 chicom special, I suggest that they buy a
better meter before we waste time working on the "problem".

Awhile back I bought several ChiCom DVMs from a flea market vendor for $5 a
pop, thinking I could toss one in each car for on-the-side-of-the-road
troubleshooting.  Problem is, the damned thing varies over half a volt on the
20 volt scale between a new 9 volt battery and one that just lights the low
battery indicator.  They're using a standard DVM chip so they had to actually
WORK at it to make it that bad!!!

One day when I have a few spare round tuits I'm going to open one up and see
what's going on.  Bet I find a simple resistor divider instead of the voltage
reference or something like that.

Anyway, here's my vote for a TAPR Volt!

John
--
John De Armond
See my website for my current email address
http://www.neon-john.com
http://www.johndearmond.com <-- best little blog on the net!
Tellico Plains, Occupied TN
WARNING: Do not use this hair dryer in the shower!



From jgd at johngsbbq.com  Thu Dec 11 14:03:11 2008
From: jgd at johngsbbq.com (Neon John)
Date: Thu, 11 Dec 2008 09:03:11 -0500
Subject: [time-nuts] V standards
In-Reply-To: <E1L6aAR-0001gZ-St@meow.febo.com>
References: <mailman.456.1227994381.2542.time-nuts@febo.com>
	<E1L6aAR-0001gZ-St@meow.febo.com>
Message-ID: <n462k4pc9fum5s1jji7vkf3dguu5rvqmlc@4ax.com>

On Sat, 29 Nov 2008 19:27:34 -0500, "Mike Monett" <XDE-L2G3 at myamail.com>
wrote:

>This discussion of voltage standards is very informative and useful, and my
>thanks to all who are contributing. 
>
>It is clear why precise frequency standards are needed - there are
>innumerable applications such as GPS, VLBI, secure spread spectrum radio,
>deep space navigation using doppler, and so on.
>
>But I wonder why extreme accuracy is needed in measuring voltage? Don't get
>me wrong - I have a HP 3456A, and I would love to have a 3458. But the
>prices on eBay can reach $6k, and I can't see spending that much money for
>two more digits. As Bill would say, six digits should be enough for
>everyone:)

Because it's still an analog world out there.  One instance that immediately
comes to mind are truck scales, especially the enforcement ones.  I recently
serviced one that had a 200,000 lb capability, a 5 lb resolution and nailed my
personal body weight to within the resolution with no last digit dithering.
That indicates to me better than 2.5 lb internal resolution.

Calibration of this particular scale is done in the digital world - roll a
50,000 lb calibrated trailer onto the scale, tell the scale processor that it
weighs 50,000.0 lbs and it figures out its own conversion factors.  HOWEVER.
Servicing the thing means working down in the kind of precision levels we're
talking about.

I have the 4 lightning-struck load cells and the matched summing box in my
shop ($10,000 from the scale company) so when I get time I can see how they do
it that precise with so few parts and with the load cells and summing box out
in the weather.  There are only 4 wires coming from each load cell so the
temperature compensation has to be built into the mechano-electrical design
and not externally compensated.

John
--
John De Armond
See my website for my current email address
http://www.neon-john.com
http://www.johndearmond.com <-- best little blog on the net!
Tellico Plains, Occupied TN
In theory, there is no difference between theory and practice.  In practice, there is.



From stijena at tapko.de  Thu Dec 11 14:25:37 2008
From: stijena at tapko.de (Predrag Dukic)
Date: Thu, 11 Dec 2008 15:25:37 +0100
Subject: [time-nuts] V standards
In-Reply-To: <n462k4pc9fum5s1jji7vkf3dguu5rvqmlc@4ax.com>
References: <mailman.456.1227994381.2542.time-nuts@febo.com>
	<E1L6aAR-0001gZ-St@meow.febo.com>
	<n462k4pc9fum5s1jji7vkf3dguu5rvqmlc@4ax.com>
Message-ID: <7.0.1.0.1.20081211152218.01f1ed40@tapko.de>




John,

Yes, that is a common practice.  Both scale factor TC and balance TC 
are inside the cell body.

  Usually it is a device similar to foill strain gage, (but made of 
nickel or balco alloy) and glued to the cell near the sg bridge.

Micromeasurements.com   (Vishay) has a lot on that topic.

Predrag Dukic





At 15:03 11.12.2008, you wrote:
>On Sat, 29 Nov 2008 19:27:34 -0500, "Mike Monett" <XDE-L2G3 at myamail.com>
>wrote:
>
> >This discussion of voltage standards is very informative and useful, and my
> >thanks to all who are contributing.
> >
> >It is clear why precise frequency standards are needed - there are
> >innumerable applications such as GPS, VLBI, secure spread spectrum radio,
> >deep space navigation using doppler, and so on.
> >
> >But I wonder why extreme accuracy is needed in measuring voltage? Don't get
> >me wrong - I have a HP 3456A, and I would love to have a 3458. But the
> >prices on eBay can reach $6k, and I can't see spending that much money for
> >two more digits. As Bill would say, six digits should be enough for
> >everyone:)
>
>Because it's still an analog world out there.  One instance that immediately
>comes to mind are truck scales, especially the enforcement ones.  I recently
>serviced one that had a 200,000 lb capability, a 5 lb resolution and nailed my
>personal body weight to within the resolution with no last digit dithering.
>That indicates to me better than 2.5 lb internal resolution.
>
>Calibration of this particular scale is done in the digital world - roll a
>50,000 lb calibrated trailer onto the scale, tell the scale processor that it
>weighs 50,000.0 lbs and it figures out its own conversion factors.  HOWEVER.
>Servicing the thing means working down in the kind of precision levels we're
>talking about.
>
>I have the 4 lightning-struck load cells and the matched summing box in my
>shop ($10,000 from the scale company) so when I get time I can see how they do
>it that precise with so few parts and with the load cells and summing box out
>in the weather.  There are only 4 wires coming from each load cell so the
>temperature compensation has to be built into the mechano-electrical design
>and not externally compensated.
>
>John
>--
>John De Armond
>See my website for my current email address
>http://www.neon-john.com
>http://www.johndearmond.com <-- best little blog on the net!
>Tellico Plains, Occupied TN
>In theory, there is no difference between theory and practice.  In 
>practice, there is.
>
>
>_______________________________________________
>time-nuts mailing list -- time-nuts at febo.com
>To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>and follow the instructions there.



From james.p.lux at jpl.nasa.gov  Thu Dec 11 14:42:59 2008
From: james.p.lux at jpl.nasa.gov (Lux, James P)
Date: Thu, 11 Dec 2008 06:42:59 -0800
Subject: [time-nuts] Voltage standards
In-Reply-To: <ve42k41uk112tugr52ldi4qdlgmrlhs88h@4ax.com>
Message-ID: <C56666F3.3667%James.P.Lux@jpl.nasa.gov>




One of those things that I've always wanted to do was to lash together a
liquid air plant from, say, refrigeration parts.  Never had the time and the
funds at the same time.

Looked at that 10-15 years ago when in the SFX business and we used a lot of LN2.  You need a real high pressure compressor (e.g. Something like used for filling scuba tanks) for the classic technique.  After fiddling with designs and poring over catalogs and surplus auctions, we decided it's cheaper and easier to just fill the GP45 for $100.


But, it WOULD be fun...

From tvb at LeapSecond.com  Thu Dec 11 15:10:16 2008
From: tvb at LeapSecond.com (Tom Van Baak)
Date: Thu, 11 Dec 2008 07:10:16 -0800
Subject: [time-nuts] GPS signal simulator
References: <014b01c95b8a$80557b30$6401a8c0@WSOffice>
Message-ID: <60BD07D43C80493391C7062AEBC2BEB6@pc52>

> Tom
> 
> Thanks that should be very useful for software simulations.
> 
> The use I had in mind for the tool I described where for the next stage of testing. 
> It can be used to test at the REAL Hardware level, using a 'perfect' GPS signal with 
> no noise or with any type of desired controlled noise.
> For example it is hard and time consuming to see how many ps of error 
> your phase detector is adding or what the phase margin or noise gain is of the H/W PLL.
> Is the power supply good enough or is it causing errors, etc 
> When using real GPS data, the random noise will hide the advanced 
> type of information you may want to take.
> The other use of the Hardware simulator is for someone that wants to know how 
> accurate their GPSDO is but does not have access to a source accurate enough 
> to test their GPSDO.
> 
> WarrenS

Read a paper like this to appreciate the complexities involved:

http://tycho.usno.navy.mil/ptti/ptti2002/paper29.pdf

/tvb



From phill.r1 at btinternet.com  Thu Dec 11 17:03:19 2008
From: phill.r1 at btinternet.com (Roy Phillips)
Date: Thu, 11 Dec 2008 17:03:19 -0000
Subject: [time-nuts] Trimble GPS Antenna's
Message-ID: <2DD8E331AE1644BDB28AEC5FD877AF06@LapTop>

A question please . . . . .

In all the considerable exchange of useful information regarding the Trimble GPS units, I cannot recall any mention of the actual specification of the antenna system for these units. My old Odetics used an "Active" antenna which required 12 volts DC to be supplied from the unit and returned the signal in the intermediate frequency range of 40 something MHz. I am aware that the Trimble units also have "Active" antenna systems, which are supplied with +5 volts DC, but what is returned from the antenna  - - is this also an intermediate frequency?

I now have two antenna's awaiting better weather to install them on a single storey building, including a 26dB gain Lucent, which are currently stuck on temporary poles at approximately 15 feet/5 mts. I am surprised at the relatively good performance in this temporary position. In fact I have had the Trimble/NortelGPS unit working with GPS lock, with the Lucent antenna standing in a glass jar in a north facing window (4 feet from ground level !) . Propagation is certainly a very complex matter.
Roy Phillips



From brooke at pacific.net  Thu Dec 11 17:43:26 2008
From: brooke at pacific.net (Brooke Clarke)
Date: Thu, 11 Dec 2008 09:43:26 -0800
Subject: [time-nuts] Trimble GPS Antenna's
In-Reply-To: <2DD8E331AE1644BDB28AEC5FD877AF06@LapTop>
References: <2DD8E331AE1644BDB28AEC5FD877AF06@LapTop>
Message-ID: <4941513E.3030508@pacific.net>

Hi Roy:

I have some info on what antennas are allowable for the ThunderBolt at:
http://www.prc68.com/I/ThunderBolt.shtml#Ant
Note the earlier Trimble Trimpack receivers needed 41 dB of gain between the 
antenna and receiver, but the Thunderbolt only needs 18 to 35 dB.

Have Fun,

Brooke Clarke
http://www.prc68.com

Roy Phillips wrote:
> A question please . . . . .
> 
> In all the considerable exchange of useful information regarding the Trimble GPS units, I cannot recall any mention of the actual specification of the antenna system for these units. My old Odetics used an "Active" antenna which required 12 volts DC to be supplied from the unit and returned the signal in the intermediate frequency range of 40 something MHz. I am aware that the Trimble units also have "Active" antenna systems, which are supplied with +5 volts DC, but what is returned from the antenna  - - is this also an intermediate frequency?
> 
> I now have two antenna's awaiting better weather to install them on a single storey building, including a 26dB gain Lucent, which are currently stuck on temporary poles at approximately 15 feet/5 mts. I am surprised at the relatively good performance in this temporary position. In fact I have had the Trimble/NortelGPS unit working with GPS lock, with the Lucent antenna standing in a glass jar in a north facing window (4 feet from ground level !) . Propagation is certainly a very complex matter.
> Roy Phillips
> 
> 
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
> 
> 



From holrum at hotmail.com  Thu Dec 11 18:32:47 2008
From: holrum at hotmail.com (Mark Sims)
Date: Thu, 11 Dec 2008 18:32:47 +0000
Subject: [time-nuts] V standards
In-Reply-To: <mailman.276.1229008237.2499.time-nuts@febo.com>
References: <mailman.276.1229008237.2499.time-nuts@febo.com>
Message-ID: <BLU125-W49C47C4BE903FD7BACCE38CEF80@phx.gbl>


As far as DMM voltages standards,  no need to build one for the 4.5 digit meters.  Doug Malone sells an excellent Xicor based reference that runs off a 9V battery for around $30 shipped.  Mine checks out to better than 0.00005V on all my 6.5 and 7.5 digit meters.  He sells them on Ebay under them user name zildjianboy7 (see item number 280292722286).  There is also the Geller Labs unit,  potentially more accurate,  but it needs an external supply.  It would be nice if they had 2.0V (or 1.9V) units available for checking those X.5 digit meters to better accuracy.

   I am a bit of a mass nut (OK I have a LOT of digital scales with resolutions down to a nanogram and up to 60Kg with 0.01g res).  Many of the industrial scales require you to enter your lat/lon/altitude (or at least your general location) so they can better model and compensate for gravity.      A 3 meter (1 story in a building) change in altitude affects gravity by 1 part/million...  easily noticeable on even a modest analytical balance.  Modern lab balances can easily resolve 1 part in 20 million.  The better ones exceed 1 part in 100 million.  Industrial scales can do 1 part per million of max capacity...  not too shabby for a mass to digital converter.
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From tvb at LeapSecond.com  Thu Dec 11 18:55:12 2008
From: tvb at LeapSecond.com (Tom Van Baak)
Date: Thu, 11 Dec 2008 10:55:12 -0800
Subject: [time-nuts] V standards
References: <mailman.276.1229008237.2499.time-nuts@febo.com>
	<BLU125-W49C47C4BE903FD7BACCE38CEF80@phx.gbl>
Message-ID: <C2D5EC3402784785B73960E3B0433925@pc52>

Mark Sims writes:
> I am a bit of a mass nut (OK I have a LOT of digital scales
> with resolutions down to a nanogram and up to 60Kg with
> 0.01g res).  Many of the industrial scales require you to
> enter your lat/lon/altitude (or at least your general location)
> so they can better model and compensate for gravity.
> A 3 meter (1 story in a building) change in altitude affects
>gravity by 1 part/million...  easily noticeable on even a modest
> analytical balance.  Modern lab balances can easily resolve
> 1 part in 20 million.  The better ones exceed 1 part in 100 million.
> Industrial scales can do 1 part per million of max capacity...
> not too shabby for a mass to digital converter.

Mark,

That's very cool that they would model static gravity effects like
that. Makes sense at that level of resolution.

Do you know of any laboratory scales that also require you
to enter the date/time so they can also model the dynamic
0.1 ppm effect on gravity of lunar/solar tides?

/tvb



From warrensjmail-one at yahoo.com  Thu Dec 11 20:07:17 2008
From: warrensjmail-one at yahoo.com (WarrenS)
Date: Thu, 11 Dec 2008 12:07:17 -0800
Subject: [time-nuts] GPS signal simulator
References: <014b01c95b8a$80557b30$6401a8c0@WSOffice>
	<60BD07D43C80493391C7062AEBC2BEB6@pc52>
Message-ID: <018b01c95bcc$11dbc000$6401a8c0@WSOffice>


----- Original Message ----- 
From: "Tom Van Baak" <tvb at LeapSecond.com>
To: "Discussion of precise time and frequency measurement" <time-nuts at febo.com>
Sent: Thursday, December 11, 2008 7:10 AM
Subject: Re: [time-nuts] GPS signal simulator


>> Tom
>> 
>> Thanks that should be very useful for software simulations.
>> 
>> The use I had in mind for the tool I described where for the next stage of testing. 
>> It can be used to test at the REAL Hardware level, using a 'perfect' GPS signal with 
>> no noise or with any type of desired controlled noise.
>> For example it is hard and time consuming to see how many ps of error 
>> your phase detector is adding or what the phase margin or noise gain is of the H/W PLL.
>> Is the power supply good enough or is it causing errors, etc 
>> When using real GPS data, the random noise will hide the advanced 
>> type of information you may want to take.
>> The other use of the Hardware simulator is for someone that wants to know how 
>> accurate their GPSDO is but does not have access to a source accurate enough 
>> to test their GPSDO.
>> 
>> WarrenS
> 
> Read a paper like this to appreciate the complexities involved:
> 
> http://tycho.usno.navy.mil/ptti/ptti2002/paper29.pdf
> 
> /tvb
> 
******************************
TOM

Thanks once again,
The paper is very helpful,  even if I can't  yet say I understand it all.
Agree, noise is a complex issue, GPS noise more so than most, 
because of all the many different types of contributing noise sources.
That is the reason I like to remove those unknowns initially for my H/W test.
Without adding the GPS noise to confuse the facts, it is very clear and easy to 
see, measure, and fix if desired the difference between say a sub ns accurate 
design and a micro sec unit. 
One of the questions I've needed to answers is just how good is good enough 
when it comes to making a high performance GPSDO.

Some of the self build units I've heard being used can be 100 to 1000 or more 
times worse than desired for best performance.

WarrenS




From holrum at hotmail.com  Thu Dec 11 20:15:56 2008
From: holrum at hotmail.com (Mark Sims)
Date: Thu, 11 Dec 2008 20:15:56 +0000
Subject: [time-nuts] V standards
In-Reply-To: <mailman.276.1229008237.2499.time-nuts@febo.com>
References: <mailman.276.1229008237.2499.time-nuts@febo.com>
Message-ID: <BLU125-W32E677FAA222AB99CCA334CEF80@phx.gbl>


Most of the industrial scales that allow location to be specified do it to improve out-of-the-crate accuracy where you might not have a calibration weight/cart/truck available (BTW,  calibration carts are not  used on the more accurate scales...  things like bouyancy of the air in the tires can greatly affect the apparent mass).  Most lab scales way to accurate to be able to effectively use a gravity model.  They have built in calibration weights (or use external weights) that compensate for such things.     
I have not tried to see if I can see the tidal effect with my Mettler mass comparator (1 part in 100,000,000 res).  I would suspect that it would be swamped by temperature fluctuations and the HUGE effect of air density (the weigh chambers on these beasties lies behind three layers of thermal glass to keep radiation of body heat, etc from stirring up air currents).  At that  level of resolution you are recalibrating the scale pretty much between evey reading.  
-----------------------------------------------------------------Mark,

That's very cool that they would model static gravity effects like
that. Makes sense at that level of resolution.

Do you know of any laboratory scales that also require you
to enter the date/time so they can also model the dynamic
0.1 ppm effect on gravity of lunar/solar tides?

/tvb


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From hmurray at megapathdsl.net  Thu Dec 11 20:17:28 2008
From: hmurray at megapathdsl.net (Hal Murray)
Date: Thu, 11 Dec 2008 12:17:28 -0800
Subject: [time-nuts] V standards
In-Reply-To: Message from "Tom Van Baak" <tvb@LeapSecond.com> of "Thu,
	11 Dec 2008 10:55:12 PST." <C2D5EC3402784785B73960E3B0433925@pc52>
Message-ID: <20081211201729.7C9EABCD7@ip-64-139-1-69.sjc.megapath.net>


> Do you know of any laboratory scales that also require you to enter
> the date/time so they can also model the dynamic 0.1 ppm effect on
> gravity of lunar/solar tides? 

It's worse than that.

Geologists measure gravity to get the density of of the underlying rocks.  I 
saw a neat topo map of the San Francisco peninsula at one of the USGS open 
houses.  The contours were rock density rather than elevation.

Of course, they had to correct for elevation.  When I asked how they got the 
elevation, the guy smiled: "From the sewer people".

They had the instrument on display.  It wasn't very big, say a cubic foot.  
Maybe they will have it out at the next open house so I can look closer.



-- 
These are my opinions, not necessarily my employer's.  I hate spam.





From tvb at LeapSecond.com  Thu Dec 11 20:33:26 2008
From: tvb at LeapSecond.com (Tom Van Baak)
Date: Thu, 11 Dec 2008 12:33:26 -0800
Subject: [time-nuts] GPS signal simulator
References: <014b01c95b8a$80557b30$6401a8c0@WSOffice><60BD07D43C80493391C7062AEBC2BEB6@pc52>
	<018b01c95bcc$11dbc000$6401a8c0@WSOffice>
Message-ID: <CF7F4A7D20F54502B6CE22F7EE633C6B@pc52>

> One of the questions I've needed to answers is just how good is good enough 
> when it comes to making a high performance GPSDO.

There is no single answer to this. One man's high-performance
is another man's low-performance. It all depends on where you
are in your quest.
 
> Some of the self build units I've heard being used can be 100 to 1000 or more 
> times worse than desired for best performance.
> 
> WarrenS

That is correct. Because time can be measured more precisely
than any other physical quantities it is quite normal for amateur
projects or even professional products to span many orders of
magnitude in performance. It is also true that the requirements
have as great a span. Someone needing a time source simply
for NTP (milliseconds) can get by with a solution a million times
less precise than someone trying to tune the C-field of their own
cesium standard (nanoseconds).

/tvb



From bruce.griffiths at xtra.co.nz  Thu Dec 11 20:53:12 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Fri, 12 Dec 2008 09:53:12 +1300
Subject: [time-nuts] Sub Pico Second Phase logger
In-Reply-To: <OF0090ABB7.674A2CF6-ON8525751C.0000CCC2-8525751C.00047AC8@mck.us.ray.com>
References: <OF0090ABB7.674A2CF6-ON8525751C.0000CCC2-8525751C.00047AC8@mck.us.ray.com>
Message-ID: <49417DB8.6020203@xtra.co.nz>

Joe

I suspect that the phase detector characteristics stated in the NIST
papers only apply when the mixer RF port is saturated.
This is evident from the Kurtz application note:

http://www.wj.com/archive/documents/Tech_Notes_Archived/Mixers_phase_detectors.pdf

 which indicates (Figure 14 and Figure 15 plus surrounding text)  that
for a high impedance (resistive) IF port termination the phase detection
characteristic only approaches a triangular wave when the RF port is
saturated (Figure 15) whereas for an unsaturated RF port (Figure 14) the
phase detection characteristics still appears sinusoidal.
The Kurtz application note also indicates that the IF port signal
amplitude reaches a maximum when the IF port termination resistance
increases (for the particular mixer) above 400 ohms.

There are no corresponding figures for the case of an IF port terminated
in a capacitor.
It would be interesting to check this.

Saturating the RF port also degrades the isolation etc, thus another
interesting question is does capacitively terminating the IF port
degrade these parameters when the RF port is unsaturated?
This may well not be the case with 5MHz or 10MHz mixer input  frequencies.


Bruce




From warrensjmail-one at yahoo.com  Thu Dec 11 21:02:34 2008
From: warrensjmail-one at yahoo.com (WarrenS)
Date: Thu, 11 Dec 2008 13:02:34 -0800
Subject: [time-nuts]  V standards
Message-ID: <020a01c95bd3$cb041800$6401a8c0@WSOffice>

Most of the industrial scales that allow location to be specified do it to improve out-of-the-crate accuracy where you might not have a calibration weight/cart/truck available (BTW,  calibration carts are not  used on the more accurate scales...  things like bouyancy of the air in the tires can greatly affect the apparent mass).  Most lab scales way to accurate to be able to effectively use a gravity model.  They have built in calibration weights (or use external weights) that compensate for such things.     
I have not tried to see if I can see the tidal effect with my Mettler mass comparator (1 part in 100,000,000 res).  I would suspect that it would be swamped by temperature fluctuations and the HUGE effect of air density (the weigh chambers on these beasties lies behind three layers of thermal glass to keep radiation of body heat, etc from stirring up air currents).  At that  level of resolution you are recalibrating the scale pretty much between evey reading.  
-----------------------------------------------------------------Mark,

That's very cool that they would model static gravity effects like
that. Makes sense at that level of resolution.

Do you know of any laboratory scales that also require you
to enter the date/time so they can also model the dynamic
0.1 ppm effect on gravity of lunar/solar tides?

/tvb

**********************
Funny,
Anyone out there that remember "True weight, no springs", 
and for a penny you also get your horoscope.

Load cells have taken a big step backward.  
They use springs and therefore are measuring weight and not mass.
This is why they need to be calibrate for the location they are at.
Gravity can vary by more 0.1% from location to location,   
so a spring scale needs to be calibrated for a given location
A mass scale, on the other hand, does not depend on gravity, 
and does not need to be calibrated for location,  
AND it can not be use to measure the change in Gravity due to tides etc..

WarrenS
 



From brooke at pacific.net  Thu Dec 11 21:09:20 2008
From: brooke at pacific.net (Brooke Clarke)
Date: Thu, 11 Dec 2008 13:09:20 -0800
Subject: [time-nuts] Sub Pico Second Phase logger
In-Reply-To: <49417DB8.6020203@xtra.co.nz>
References: <OF0090ABB7.674A2CF6-ON8525751C.0000CCC2-8525751C.00047AC8@mck.us.ray.com>
	<49417DB8.6020203@xtra.co.nz>
Message-ID: <49418180.3000507@pacific.net>

Hi Bruce:

A general comments on mixers.

Since they are very nonlinear devices the output consists of signals at:
+/-m * RF +/-n * LO.
The output will change if the termination on any of the ports at any of those 
frequencies is changed.  How much it changes depends on how strong that signal 
is.  Some mixers reflect the image frequency to improve the conversion loss of 
the desired output.

For the mixers I was working with the LO needed to be strong enough to drive 
the diodes into saturation and the RF needed to be small enough to not effect 
the LO power.

More on that at:
http://www.prc68.com/I/Diodes.html

Have Fun,

Brooke Clarke
http://www.prc68.com

Bruce Griffiths wrote:
> Joe
> 
> I suspect that the phase detector characteristics stated in the NIST
> papers only apply when the mixer RF port is saturated.
> This is evident from the Kurtz application note:
> 
> http://www.wj.com/archive/documents/Tech_Notes_Archived/Mixers_phase_detectors.pdf
> 
>  which indicates (Figure 14 and Figure 15 plus surrounding text)  that
> for a high impedance (resistive) IF port termination the phase detection
> characteristic only approaches a triangular wave when the RF port is
> saturated (Figure 15) whereas for an unsaturated RF port (Figure 14) the
> phase detection characteristics still appears sinusoidal.
> The Kurtz application note also indicates that the IF port signal
> amplitude reaches a maximum when the IF port termination resistance
> increases (for the particular mixer) above 400 ohms.
> 
> There are no corresponding figures for the case of an IF port terminated
> in a capacitor.
> It would be interesting to check this.
> 
> Saturating the RF port also degrades the isolation etc, thus another
> interesting question is does capacitively terminating the IF port
> degrade these parameters when the RF port is unsaturated?
> This may well not be the case with 5MHz or 10MHz mixer input  frequencies.
> 
> 
> Bruce
> 
> 
> 
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
> 
> 



From warrensjmail-one at yahoo.com  Thu Dec 11 21:23:07 2008
From: warrensjmail-one at yahoo.com (WarrenS)
Date: Thu, 11 Dec 2008 13:23:07 -0800
Subject: [time-nuts]  GPS signal simulator
Message-ID: <021901c95bd6$a981e100$6401a8c0@WSOffice>



>> One of the questions I've needed to answers is just how good is good enough 
>> when it comes to making a high performance GPSDO.

>There is no single answer to this. One man's high-performance
>is another man's low-performance. It all depends on where you
>are in your quest.
 
>> Some of the self build units I've heard being used can be 100 to 1000 or more 
>> times worse than desired for best performance.
>> 
>> WarrenS

>That is correct. Because time can be measured more precisely
>than any other physical quantities it is quite normal for amateur
>projects or even professional products to span many orders of
>magnitude in performance. It is also true that the requirements
>have as great a span. Someone needing a time source simply
>for NTP (milliseconds) can get by with a solution a million times
>less precise than someone trying to tune the C-field of their own
>cesium standard (nanoseconds).
>
>/tvb
****************

My mistake, I should not of assumed as I did, that everyone would understand what 
"good enough" means for a "high performance GPSDO".
Good enough means: so as NOT to degrade the limited and available accuracy of the GSP signal.
i.e at least 3 to 6 db better than the noise. 
The correct answer is not a function of the user, it is a function of the GPS signal.

Warren

From holrum at hotmail.com  Thu Dec 11 21:23:45 2008
From: holrum at hotmail.com (Mark Sims)
Date: Thu, 11 Dec 2008 21:23:45 +0000
Subject: [time-nuts] time-nuts Digest, Vol 53, Issue 46
In-Reply-To: <mailman.291.1229028803.2499.time-nuts@febo.com>
References: <mailman.291.1229028803.2499.time-nuts@febo.com>
Message-ID: <BLU125-W12CCEA2F9496EAD108B9E5CEF80@phx.gbl>


The quintessential gravity meter (Worden Gravity Meter by Texas Instruments)...  still being made after 60 years or so:
http://www.mssu.edu/seg-vm/pict0246.html


------------------------------------------
Geologists measure gravity to get the density of of the underlying rocks.  I 
saw a neat topo map of the San Francisco peninsula at one of the USGS open 
houses.  The contours were rock density rather than elevation.

Of course, they had to correct for elevation.  When I asked how they got the 
elevation, the guy smiled: "From the sewer people".

They had the instrument on display.  It wasn't very big, say a cubic foot.  
Maybe they will have it out at the next open house so I can look closer.


_________________________________________________________________
Send e-mail anywhere. No map, no compass.
http://windowslive.com/Explore/hotmail?ocid=TXT_TAGLM_WL_hotmail_acq_anywhere_122008

From holrum at hotmail.com  Thu Dec 11 21:35:40 2008
From: holrum at hotmail.com (Mark Sims)
Date: Thu, 11 Dec 2008 21:35:40 +0000
Subject: [time-nuts] V standards
In-Reply-To: <mailman.276.1229008237.2499.time-nuts@febo.com>
References: <mailman.276.1229008237.2499.time-nuts@febo.com>
Message-ID: <BLU125-W17CCBAA94D5B25CFF3F0E2CEF80@phx.gbl>


And a newer design gravity meter:   

http://www.ipgp.jussieu.fr/files_lib/163_CG-3DescriptionTestResults.pdf

_________________________________________________________________
Suspicious message? There?s an alert for that. 
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From bruce.griffiths at xtra.co.nz  Thu Dec 11 21:43:52 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Fri, 12 Dec 2008 10:43:52 +1300
Subject: [time-nuts] Sub Pico Second Phase logger
In-Reply-To: <49418180.3000507@pacific.net>
References: <OF0090ABB7.674A2CF6-ON8525751C.0000CCC2-8525751C.00047AC8@mck.us.ray.com>	<49417DB8.6020203@xtra.co.nz>
	<49418180.3000507@pacific.net>
Message-ID: <49418998.7040609@xtra.co.nz>

Brooke

The NIST papers concerned were about using mixers as phase detectors:

http://tf.nist.gov/timefreq/general/pdf/112.pdf


http://tf.nist.gov/timefreq/general/pdf/971.pdf

As is all too often the case with some NIST papers the operating conditions for which the stated phase detection characteristics are true are not specified.

Its probably a case of over familiarity with the subject and forgetting
that what's obvious to the author isn't necessarily obvious to the reader.

Since the Minicircuits phase detectors (RPD, MPD series etc) are
specified for operation with a 500 ohm resistive IF termination, and
they have relatively high RF port to RF port isolation changing the RF
port termination from 50 ohms (at least with low frequency mixers using
conventional transformers) doesn't necessarily degrade the port to port
isolation significantly.

Bruce


Brooke Clarke wrote:
> Hi Bruce:
>
> A general comments on mixers.
>
> Since they are very nonlinear devices the output consists of signals at:
> +/-m * RF +/-n * LO.
> The output will change if the termination on any of the ports at any of those 
> frequencies is changed.  How much it changes depends on how strong that signal 
> is.  Some mixers reflect the image frequency to improve the conversion loss of 
> the desired output.
>
> For the mixers I was working with the LO needed to be strong enough to drive 
> the diodes into saturation and the RF needed to be small enough to not effect 
> the LO power.
>
> More on that at:
> http://www.prc68.com/I/Diodes.html
>
> Have Fun,
>
> Brooke Clarke
> http://www.prc68.com
>
> Bruce Griffiths wrote:
>   
>> Joe
>>
>> I suspect that the phase detector characteristics stated in the NIST
>> papers only apply when the mixer RF port is saturated.
>> This is evident from the Kurtz application note:
>>
>> http://www.wj.com/archive/documents/Tech_Notes_Archived/Mixers_phase_detectors.pdf
>>
>>  which indicates (Figure 14 and Figure 15 plus surrounding text)  that
>> for a high impedance (resistive) IF port termination the phase detection
>> characteristic only approaches a triangular wave when the RF port is
>> saturated (Figure 15) whereas for an unsaturated RF port (Figure 14) the
>> phase detection characteristics still appears sinusoidal.
>> The Kurtz application note also indicates that the IF port signal
>> amplitude reaches a maximum when the IF port termination resistance
>> increases (for the particular mixer) above 400 ohms.
>>
>> There are no corresponding figures for the case of an IF port terminated
>> in a capacitor.
>> It would be interesting to check this.
>>
>> Saturating the RF port also degrades the isolation etc, thus another
>> interesting question is does capacitively terminating the IF port
>> degrade these parameters when the RF port is unsaturated?
>> This may well not be the case with 5MHz or 10MHz mixer input  frequencies.
>>
>>
>> Bruce
>>
>>
>>
>> _______________________________________________
>> time-nuts mailing list -- time-nuts at febo.com
>> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>> and follow the instructions there.
>>
>>
>>     
>
>
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>
>   



From gwinn at raytheon.com  Thu Dec 11 22:19:34 2008
From: gwinn at raytheon.com (Joseph M Gwinn)
Date: Thu, 11 Dec 2008 17:19:34 -0500
Subject: [time-nuts] Sub Pico Second Phase logger
In-Reply-To: <49406F05.8030109@xtra.co.nz>
Message-ID: <OF92A8AB8F.8DFC4FD6-ON8525751C.0077DF13-8525751C.007AA3AD@mck.us.ray.com>

Bruce,


time-nuts-bounces at febo.com wrote on 12/10/2008 08:38:13 PM:

> Joe
> Joseph M Gwinn wrote:
> > Bruce,
> >
> > 
> >> Reflecting the sum frequency back into the mixer is actually 
necessary
> >> to reduce the noise at the IF port.
> >> I believe that one of Agilent's simulation application notes mentions
> >> this effect but I don't recall the actual application note number.
> >> This will affect the mixer RF and IF port impedance so adding a 
series
> >> resistor may be required to improve the SWR.
> >> 
> >
> > How big an effect is this?  Is the absolute noise decreased, or does 
it 
> > remain the same while the signal increase?
> >
> > 
> With the same difference frequency IF port termination impedance,  noise
> is actually decreased along with the mixer conversion loss.

OK.  Complicated beasts, those mixers.  Do you know of a paper (or book) 
on the subject?


> However if the sound card input noise dominates, reducing the mixer
> effective output noise won't help.

Yes.  In the plots you posted in a different email, there was a big rise 
below 1 KHz (scan stopped at 1 KHz, so don't know the shape).  Why is 
this?


> > If I'm understanding Walls and Stein (paper 112) correctly, the 
advantage 
> > is because with the capacitor load the beatnote waveform approaches 
> > square, thus increasing the zero-crossing speed and therefor the phase 

> > sensitivity.  This is no doubt true, but the question was if this also 

> > caused a small everything-dependent phase shift, something that would 
not 
> > have mattered in the measurement of phase noise.  The object of paper 
112 
> > was to remedy a 10 to 20 dB error in phase noise measurements.  The 
> > critical words are in the lower left column of page 337, in the 
paragraph 
> > beginning "If the mixer is terminated ...".
> >
> >
> > 
> Saturating the RF port has a similar effect.

Yes.  But there are tradeoffs pushing the other way.


> If one is time stamping the zero crossings an increased zero-crossing 
slope is an advantage.
> For relative phase measurements a trapezoidal beat frequency waveform 
may be less useful.

Fitting to the approximate waveshape, sine or trapezoidal, should yield a 
very robust estimate, due to the large data support, and zero-crossing 
slope won't much matter.  Hmm.  Actually, if the slopes of the trapezoid 
are too steep, we may not have all that many slope samples.


[snip]
> 
> Of course with a capacitive IF port termination, matching the RF and LO
> ports becomes more critical as does the reverse isolation of the various
> amplifiers driving the RF and LO ports.
> It may be simpler in fact to use a level 17 mixer with high LO to RF and
> LO to IF isolation with the RF port unsaturated as it relaxes the
> reverse isolation specs for the isolation amplifiers.

Another tradeoff.  I'll have to think about it.

I'm thinking of 6 db and 10 db attenuators on the LO and RF ports 
respectively, but no isolation amplifier.


[snip]
> >
> > 
> The only configuration for which it makes any sense is an inverting
> input amplifier with a finite input voltage offset.

Why would non-inverting not work?  Both inputs source or sink bias 
currents, and non-inverting presents a very high impedance.



> > 
> >> It's hard to find such Firewire systems without such unnecessary 
frills
> >> (for this application) as high gain preamps.
> >> 
> >
> > The AP192 has high-level inputs, but I don't know if this bypasses the 

> > preamps, or attenuates.  Given their target market, I'd bet it 
bypasses.
> >
> > 
> There are no preamps other than an external differential input amplifier
> that translates the 4 Vrms FS inputs at the input connector to a level
> that the ADC can handle.
> The ADC chip itself has no preamps built in.
> There have been numerous complaint about this by some audio nuts,
> however for this application not having such amplifiers is ideal.

Bingo!  Good to know.

 
> >> The gain tempco and linearity of some variable gain audio preamps is
> >> somewhat suspect.
> >> 
> >
> > I would think that none of these cards has a good tempco of anything, 
> > given the lack of necessity in their market.
> >
> > I would think that linearity would be quite good, given the horsepower 

> > competitions on linearity.
> >
> > 
> Since the 2 ADCs share the same reference their gain tracking tempco
> should be quite good given that they use capacitors rather than
> resistors within the ADCs.

A happy accident, but we'll take it.


We are converging on a soundcard wishlist:

1.  True balanced inputs on XLR connectors.  And good ground design, so we 
aren't bedeviled by ground loops.

2.  24-bit ADCs, and similar DACs.

3.  Very good isolation all around. 

4.  Digital access via firewire (or USB3 I suppose), with the soundcard in 
its own box.

5.  High-level input direct to the ADCs.


While use of AKM ICs may be a very good idea, it is not a requirement per 
se.

[snip]
> >> Can alleviate [oddities at end of phase range} to some extent by 
driving 
> >> a pair of such phase detectors so that their outputs are in 
quadrature.
> >> One just selects the phase detector output that is in the linear 
range.
> >> The quadrature outputs also allow unambiguous assignment of the sign 
of
> >> any phase change.
> >> 
> >
> > The Symmetricom 5120A does something very clever to alleviate this 
> > problem.  Explained in US patent 7,227,346 and "Direct-Digital 
Phase-Noise 
> > Measurement"; J. Grove, J. Hein, J. Retta, P. Schweiger, W. Solbrig, 
and 
> > S.R. Stein; 2004 IEEE International Ultrasonics, Ferroelectrics, and 
> > Frequency Control Joint 50th Anniversary Conference, pages 287-291.
> >
> > Joe
> >
> > 
> I've read the patent.

The paper is also worthwhile, and available on the web somewhere (don't 
recall where, but google found the pdf).  I had to read the patent 
multiple times to figure out what's going on.  The correlation approach is 
old as the hills, and only the digital phase detector was patentable.


Joe



From brooke at pacific.net  Thu Dec 11 22:38:19 2008
From: brooke at pacific.net (Brooke Clarke)
Date: Thu, 11 Dec 2008 14:38:19 -0800
Subject: [time-nuts] time-nuts Digest, Vol 53, Issue 46
In-Reply-To: <BLU125-W12CCEA2F9496EAD108B9E5CEF80@phx.gbl>
References: <mailman.291.1229028803.2499.time-nuts@febo.com>
	<BLU125-W12CCEA2F9496EAD108B9E5CEF80@phx.gbl>
Message-ID: <4941965B.5000105@pacific.net>

Hi Mark:

I think it's out of date.

The current method is to drop an optical corner cube (retro-reflector) in a 
vacuum and using a laser measure the distance it moves (which requires a 
reasonably good source of time.
http://www.ngs.noaa.gov/GRD/GRAVITY/ABSG.html

Have Fun,

Brooke Clarke
http://www.prc68.com

Mark Sims wrote:
> The quintessential gravity meter (Worden Gravity Meter by Texas Instruments)...  still being made after 60 years or so:
> http://www.mssu.edu/seg-vm/pict0246.html
> 
> 
> ------------------------------------------
> Geologists measure gravity to get the density of of the underlying rocks.  I 
> saw a neat topo map of the San Francisco peninsula at one of the USGS open 
> houses.  The contours were rock density rather than elevation.
> 
> Of course, they had to correct for elevation.  When I asked how they got the 
> elevation, the guy smiled: "From the sewer people".
> 
> They had the instrument on display.  It wasn't very big, say a cubic foot.  
> Maybe they will have it out at the next open house so I can look closer.
> 
> 
> _________________________________________________________________
> Send e-mail anywhere. No map, no compass.
> http://windowslive.com/Explore/hotmail?ocid=TXT_TAGLM_WL_hotmail_acq_anywhere_122008
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
> 
> 



From jmiles at pop.net  Thu Dec 11 22:41:03 2008
From: jmiles at pop.net (John Miles)
Date: Thu, 11 Dec 2008 14:41:03 -0800
Subject: [time-nuts] Sub Pico Second Phase logger
In-Reply-To: <OF92A8AB8F.8DFC4FD6-ON8525751C.0077DF13-8525751C.007AA3AD@mck.us.ray.com>
Message-ID: <PKEGJHPHLLBACEOICCBJOEKKPLAB.jmiles@pop.net>


> > > The Symmetricom 5120A does something very clever to alleviate this
> > > problem.  Explained in US patent 7,227,346 and "Direct-Digital
> Phase-Noise
> > > Measurement"; J. Grove, J. Hein, J. Retta, P. Schweiger, W. Solbrig,
> and
> > > S.R. Stein; 2004 IEEE International Ultrasonics, Ferroelectrics, and
> > > Frequency Control Joint 50th Anniversary Conference, pages 287-291.
> > >
> > > Joe
> > >
> > >
> > I've read the patent.
>
> The paper is also worthwhile, and available on the web somewhere (don't
> recall where, but google found the pdf).  I had to read the patent
> multiple times to figure out what's going on.  The correlation
> approach is
> old as the hills, and only the digital phase detector was patentable.

If you find a link to the Grove paper that's not behind an IEEE paywall,
please post it.  I'd like to read that one.

-- john, KE5FX




From holrum at hotmail.com  Thu Dec 11 23:27:31 2008
From: holrum at hotmail.com (Mark Sims)
Date: Thu, 11 Dec 2008 23:27:31 +0000
Subject: [time-nuts] time-nuts Digest, Vol 53, Issue 47
In-Reply-To: <mailman.296.1229034043.2499.time-nuts@febo.com>
References: <mailman.296.1229034043.2499.time-nuts@febo.com>
Message-ID: <BLU125-W2FD5466015A3D5A89E1E0CEF80@phx.gbl>


Ooooh,  way to big, complicated, expensive, fragile, and swoopty fancy pants for real world use...

The CG-3 type instruments and some of the the LaCoste & Romberg units also have ppb resolution and weigh around 12 kg.  The Worden units weigh even less (and I bought mine for less than $100).  The only problem with the Worden type devices is if you even think about jiggling it while the mechanism is unlocked you break the quartz fiber.

--------------------------------
The current method is to drop an optical corner cube (retro-reflector) in a 
vacuum and using a laser measure the distance it moves (which requires a 
reasonably good source of time.
http://www.ngs.noaa.gov/GRD/GRAVITY/ABSG.html


_________________________________________________________________
Suspicious message? There?s an alert for that. 
http://windowslive.com/Explore/hotmail?ocid=TXT_TAGLM_WL_hotmail_acq_broad2_122008

From bruce.griffiths at xtra.co.nz  Fri Dec 12 00:44:01 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Fri, 12 Dec 2008 13:44:01 +1300
Subject: [time-nuts] Sub Pico Second Phase logger
In-Reply-To: <OF92A8AB8F.8DFC4FD6-ON8525751C.0077DF13-8525751C.007AA3AD@mck.us.ray.com>
References: <OF92A8AB8F.8DFC4FD6-ON8525751C.0077DF13-8525751C.007AA3AD@mck.us.ray.com>
Message-ID: <4941B3D1.9030102@xtra.co.nz>

Joe

Isolation from mixer RF to LO port may be too low when the mixer input
frequencies are different.
Injection locking can then occur all too easily (just ask Ulrich about
this) when the mixer RF ports are driven by 2 separate OCXOs.

Detailed in line post follows:

Bruce

Joseph M Gwinn wrote:
> Bruce,
>
>
> time-nuts-bounces at febo.com wrote on 12/10/2008 08:38:13 PM:
>
>   
>> Joe
>> Joseph M Gwinn wrote:
>>     
>>> Bruce,
>>>
>>>
>>>       
>>>> Reflecting the sum frequency back into the mixer is actually 
>>>>         
> necessary
>   
>>>> to reduce the noise at the IF port.
>>>> I believe that one of Agilent's simulation application notes mentions
>>>> this effect but I don't recall the actual application note number.
>>>> This will affect the mixer RF and IF port impedance so adding a 
>>>>         
> series
>   
>>>> resistor may be required to improve the SWR.
>>>>
>>>>         
>>> How big an effect is this?  Is the absolute noise decreased, or does 
>>>       
> it 
>   
>>> remain the same while the signal increase?
>>>
>>>
>>>       
>> With the same difference frequency IF port termination impedance,  noise
>> is actually decreased along with the mixer conversion loss.
>>     
>
> OK.  Complicated beasts, those mixers.  Do you know of a paper (or book) 
> on the subject?
>
>   


Not offhand, but this crops up in lots of places usually when one least
expects it..


>> However if the sound card input noise dominates, reducing the mixer
>> effective output noise won't help.
>>     
>
> Yes.  In the plots you posted in a different email, there was a big rise 
> below 1 KHz (scan stopped at 1 KHz, so don't know the shape).  Why is 
> this?
>
>
>   


I'll expand the frequency scale and take another snapshot for the region
below 1kHz.
This rise may be due to ADC and/or input differential amplifier flicker
noise.


>>> If I'm understanding Walls and Stein (paper 112) correctly, the 
>>>       
> advantage 
>   
>>> is because with the capacitor load the beatnote waveform approaches 
>>> square, thus increasing the zero-crossing speed and therefor the phase 
>>>       
>
>   
>>> sensitivity.  This is no doubt true, but the question was if this also 
>>>       
>
>   
>>> caused a small everything-dependent phase shift, something that would 
>>>       
> not 
>   
>>> have mattered in the measurement of phase noise.  The object of paper 
>>>       
> 112 
>   
>>> was to remedy a 10 to 20 dB error in phase noise measurements.  The 
>>> critical words are in the lower left column of page 337, in the 
>>>       
> paragraph 
>   
>>> beginning "If the mixer is terminated ...".
>>>
>>>
>>>
>>>       
>> Saturating the RF port has a similar effect.
>>     
>
> Yes.  But there are tradeoffs pushing the other way.
>
>
>   
>> If one is time stamping the zero crossings an increased zero-crossing 
>>     
> slope is an advantage.
>   
>> For relative phase measurements a trapezoidal beat frequency waveform 
>>     
> may be less useful.
>
> Fitting to the approximate waveshape, sine or trapezoidal, should yield a 
> very robust estimate, due to the large data support, and zero-crossing 
> slope won't much matter.  Hmm.  Actually, if the slopes of the trapezoid 
> are too steep, we may not have all that many slope samples.
>
>
>   

If one believes the NIST papers the trapezoid zero crossing slope only
increases by a factor of 3.
If one uses a cascaded filter limiter the slope gain can be adjusted for
optimum results.



> [snip]
>   
>> Of course with a capacitive IF port termination, matching the RF and LO
>> ports becomes more critical as does the reverse isolation of the various
>> amplifiers driving the RF and LO ports.
>> It may be simpler in fact to use a level 17 mixer with high LO to RF and
>> LO to IF isolation with the RF port unsaturated as it relaxes the
>> reverse isolation specs for the isolation amplifiers.
>>     
>
> Another tradeoff.  I'll have to think about it.
>
> I'm thinking of 6 db and 10 db attenuators on the LO and RF ports 
> respectively, but no isolation amplifier.
>
>   

You may get away with that if you use mixers with very high RF to LO
port isolation.
Minicircuits have at least 3 level 17 mixer models that typically have
80dB LO to RF isolation at 10MHz.

Using a passive splitter for the LO drives will gain at least another
30dB in isolation between the 2 RF inputs if you use an appropriate
splitter.


> [snip]
>   
>>>       
>> The only configuration for which it makes any sense is an inverting
>> input amplifier with a finite input voltage offset.
>>     
>
> Why would non-inverting not work?  Both inputs source or sink bias 
> currents, and non-inverting presents a very high impedance.
>
>
>
>   


Non inverting amplifiers usually have lower noise and generally work
very well.
I was only trying to come up with a preamp circuit for which the
comments in the Minicircuits application note on the effect of amplifier
input offset voltage made any sense.
The only risk with a noninverting amplifier, is that under fault
conditions (missing supply) a very large current can flow back (with
some low noise opamps as Enrico has experienced) into the mixers and
destroy them.

For this particular application the mixer preamp gain need only be
sufficient to boost the mixer phase detector output (1V pk?, 350mV pk??
depends on mixer and its operating conditions) to the sound card input
(FSR ~ 5.6V pk for an AP192). The resultant preamp gain is relatively
low ( 5 - 15X depending on the mixer etc) and the sound card noise will
dominate (~ 100nV/rtHz midband for an AP192) thus using an ultra low
noise mixer preamp isnt necessary.


>>>> It's hard to find such Firewire systems without such unnecessary 
>>>>         
> frills
>   
>>>> (for this application) as high gain preamps.
>>>>
>>>>         
>>> The AP192 has high-level inputs, but I don't know if this bypasses the 
>>>       
>
>   
>>> preamps, or attenuates.  Given their target market, I'd bet it 
>>>       
> bypasses.
>   
>>>       
>> There are no preamps other than an external differential input amplifier
>> that translates the 4 Vrms FS inputs at the input connector to a level
>> that the ADC can handle.
>> The ADC chip itself has no preamps built in.
>> There have been numerous complaint about this by some audio nuts,
>> however for this application not having such amplifiers is ideal.
>>     
>
> Bingo!  Good to know.
>
>  
>   
>>>> The gain tempco and linearity of some variable gain audio preamps is
>>>> somewhat suspect.
>>>>
>>>>         
>>> I would think that none of these cards has a good tempco of anything, 
>>> given the lack of necessity in their market.
>>>
>>> I would think that linearity would be quite good, given the horsepower 
>>>       
>
>   
>>> competitions on linearity.
>>>
>>>
>>>       
>> Since the 2 ADCs share the same reference their gain tracking tempco
>> should be quite good given that they use capacitors rather than
>> resistors within the ADCs.
>>     
>
> A happy accident, but we'll take it.
>
>
> We are converging on a soundcard wishlist:
>
> 1.  True balanced inputs on XLR connectors.  And good ground design, so we 
> aren't bedeviled by ground loops.
>
> 2.  24-bit ADCs, and similar DACs.
>
> 3.  Very good isolation all around. 
>
> 4.  Digital access via firewire (or USB3 I suppose), with the soundcard in 
> its own box.
>
> 5.  High-level input direct to the ADCs.
>
>
> While use of AKM ICs may be a very good idea, it is not a requirement per 
> se.
>
> [snip]
>   


Optical isolation of the ADC from the noisy digital interface to the PC
would also be nice.

If we design our own PCB then the AD7760 series ADCs are another
possible option.
These have a built in differential input differential output amplifier.



>>>> Can alleviate [oddities at end of phase range} to some extent by 
>>>>         
> driving 
>   
>>>> a pair of such phase detectors so that their outputs are in 
>>>>         
> quadrature.
>   
>>>> One just selects the phase detector output that is in the linear 
>>>>         
> range.
>   
>>>> The quadrature outputs also allow unambiguous assignment of the sign 
>>>>         
> of
>   
>>>> any phase change.
>>>>
>>>>         
>>> The Symmetricom 5120A does something very clever to alleviate this 
>>> problem.  Explained in US patent 7,227,346 and "Direct-Digital 
>>>       
> Phase-Noise 
>   
>>> Measurement"; J. Grove, J. Hein, J. Retta, P. Schweiger, W. Solbrig, 
>>>       
> and 
>   
>>> S.R. Stein; 2004 IEEE International Ultrasonics, Ferroelectrics, and 
>>> Frequency Control Joint 50th Anniversary Conference, pages 287-291.
>>>
>>> Joe
>>>
>>>
>>>       
>> I've read the patent.
>>     
>
> The paper is also worthwhile, and available on the web somewhere (don't 
> recall where, but google found the pdf).  I had to read the patent 
> multiple times to figure out what's going on.  The correlation approach is 
> old as the hills, and only the digital phase detector was patentable.
>
>
>   


It may be feasible to achieve the same effect by purely digital means at
least for low sample rates where FIR filters with tens of thousands of
taps are feasible.
Of course 64 bit or higher precision arithmetic is then mandatory to
avoid excessive calculation roundoff noise.


> Joe
>
>   


From bruce.griffiths at xtra.co.nz  Fri Dec 12 01:36:47 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Fri, 12 Dec 2008 14:36:47 +1300
Subject: [time-nuts] Sub Pico Second Phase logger
In-Reply-To: <4941B3D1.9030102@xtra.co.nz>
References: <OF92A8AB8F.8DFC4FD6-ON8525751C.0077DF13-8525751C.007AA3AD@mck.us.ray.com>
	<4941B3D1.9030102@xtra.co.nz>
Message-ID: <4941C02F.8060009@xtra.co.nz>

Joe

Attached is noise spectrum (1kHz and below) of AP192 with nothing
connected to inputs.
Sampling rate 96KSPS.
Frequency bin equivalent noise bandwidth ~ 3Hz.
Noise has similar spectrum to flicker noise with a noise corner of
around 300Hz or so.


Bruce
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From boyscout at gmail.com  Fri Dec 12 02:42:58 2008
From: boyscout at gmail.com (Matt Ettus)
Date: Thu, 11 Dec 2008 18:42:58 -0800
Subject: [time-nuts] pps vs. 10 MHz timing
Message-ID: <ad9f78230812111842j1851b9c3vb06b9294371863fe@mail.gmail.com>

On my Oscilloquartz GPSDO, the 10 MHz output goes low at very close to
the same time as the 1 PPS output goes high.

On my Fury, the 10 MHz sine wave is just dropping off of its max high
voltage as the 1 PPS goes high.  The 10 MHz CMOS output goes high just
shortly before the 1 PPS.

What do other GPSDOs do?

Clearly, any device trying to latch the 1 PPS signal using the 10 MHz
clock will need to choose which clock edge to use, depending on which
type of GPSDO is used.  How is this normally handled?

Also, I noticed that the TADD-1 has some weird distortion of a 10 MHz
sine wave.  It turns it into a sort of a 3 valued square wave.
Essentially, it stops and dwells at the midpoint for a while instead
of making a sharp transition.  I think this would be bad if that dwell
point is close to the threshold for the receiving device.  Has anyone
else noticed this?


Thanks,
Matt


From bruce.griffiths at xtra.co.nz  Fri Dec 12 02:54:46 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Fri, 12 Dec 2008 15:54:46 +1300
Subject: [time-nuts] pps vs. 10 MHz timing
In-Reply-To: <ad9f78230812111842j1851b9c3vb06b9294371863fe@mail.gmail.com>
References: <ad9f78230812111842j1851b9c3vb06b9294371863fe@mail.gmail.com>
Message-ID: <4941D276.8000209@xtra.co.nz>

Matt

For those GPSDOs which also use the OCXO clock to generate the LO for
the GPS receiver (eg Thunderbolt) the zerocrossing transitions of the
10MHz output are accurately aligned to the leading edge of the 1PPS output.

For other GPSDOs there may be an offset between the 10MHz zero crossing
and the receiver 1 PPS output.

If the PPS output is derived from the OCXO via a divider then the
leading edge of the PPS output will be aligned (within a gate
propagation delay or 2) with the PPS output.

One can always use a dual phase synchroniser to detect the 1Hz
transition using the 10Mhz output.

Bruce

Matt Ettus wrote:
> On my Oscilloquartz GPSDO, the 10 MHz output goes low at very close to
> the same time as the 1 PPS output goes high.
>
> On my Fury, the 10 MHz sine wave is just dropping off of its max high
> voltage as the 1 PPS goes high.  The 10 MHz CMOS output goes high just
> shortly before the 1 PPS.
>
> What do other GPSDOs do?
>
> Clearly, any device trying to latch the 1 PPS signal using the 10 MHz
> clock will need to choose which clock edge to use, depending on which
> type of GPSDO is used.  How is this normally handled?
>
> Also, I noticed that the TADD-1 has some weird distortion of a 10 MHz
> sine wave.  It turns it into a sort of a 3 valued square wave.
> Essentially, it stops and dwells at the midpoint for a while instead
> of making a sharp transition.  I think this would be bad if that dwell
> point is close to the threshold for the receiving device.  Has anyone
> else noticed this?
>
>
> Thanks,
> Matt
>
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>
>   



From tvb at LeapSecond.com  Fri Dec 12 03:53:36 2008
From: tvb at LeapSecond.com (Tom Van Baak)
Date: Thu, 11 Dec 2008 19:53:36 -0800
Subject: [time-nuts] pps vs. 10 MHz timing
References: <ad9f78230812111842j1851b9c3vb06b9294371863fe@mail.gmail.com>
Message-ID: <15AB6D7EF03C40CBA1DFF66C0BD4D724@pc52>

Hi Matt,

> What do other GPSDOs do?

All over the map. A well-engineered GPSDO might choose to
align the rising zero crossing of the 10 MHz sinewave with the
leading edge of a very fast risetime 1PPS, because this is
"common sense" but if it isn't in the spec, it's best not to expect
it to happen.

> Clearly, any device trying to latch the 1 PPS signal using the 10 MHz
> clock will need to choose which clock edge to use, depending on which
> type of GPSDO is used.  How is this normally handled?

But worst case, if you chose the wrong 10 MHz sinewave edge
you're at most 50 ns off from the 1PPS -- and note this is still
within the +/- 100 ns of UTC accuracy spec that a lot of GPS
receivers claim.

There is often a fixed phase delay between the two outputs. It
may be just a few ns or it may be tens of ns depending on the
number of inverters, buffers, amplifiers in the signal path(s),
the length of internal or external cables, or impedance effects
on risetime (50R vs 1M can make a difference).

One also has to be very careful with the 1PPS pulse itself. Most
GPSDO do not specify the voltage level of the pulse. Now if the
pulse risetime is just a couple of ns this is not a serious problem.
But when the risetime is many ns or many tens of ns then you
need to know what trigger voltage level constitutes the intended
true moment of the 1PPS. See, for example, 

http://www.leapsecond.com/pages/gpsdo-rise/

Some of these GPSDO have about a 1 V / 10 ns slew rate which
means if you don't nail down your trigger level you're asking for
very large shifts in 1PPS timing. The zero-crossing of a 10 MHz
sinewave doesn't have the same ambiguity.

/tvb



From aceamusements at mchsi.com  Fri Dec 12 04:30:54 2008
From: aceamusements at mchsi.com (aceamusements at mchsi.com)
Date: Fri, 12 Dec 2008 04:30:54 +0000
Subject: [time-nuts] Date codes on hp 5071a?
In-Reply-To: <15AB6D7EF03C40CBA1DFF66C0BD4D724@pc52>
References: <ad9f78230812111842j1851b9c3vb06b9294371863fe@mail.gmail.com>
	<15AB6D7EF03C40CBA1DFF66C0BD4D724@pc52>
Message-ID: <121220080430.20468.4941E8FE0004E65B00004FF4223245003003010CD2079C080C03BF9C9B020A030A9C9A030E0A0C0E@mchsi.com>


 
 Hi,I was wondering by chance if someone familiar with hp date coding could tell me the date of manuf. of this 5071a 

3608A01190

Thanks,

From bruce.griffiths at xtra.co.nz  Fri Dec 12 04:33:28 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Fri, 12 Dec 2008 17:33:28 +1300
Subject: [time-nuts] Date codes on hp 5071a?
In-Reply-To: <121220080430.20468.4941E8FE0004E65B00004FF4223245003003010CD2079C080C03BF9C9B020A030A9C9A030E0A0C0E@mchsi.com>
References: <ad9f78230812111842j1851b9c3vb06b9294371863fe@mail.gmail.com>	<15AB6D7EF03C40CBA1DFF66C0BD4D724@pc52>
	<121220080430.20468.4941E8FE0004E65B00004FF4223245003003010CD2079C080C03BF9C9B020A030A9C9A030E0A0C0E@mchsi.com>
Message-ID: <4941E998.70909@xtra.co.nz>

aceamusements at mchsi.com wrote:
>  
>  Hi,I was wondering by chance if someone familiar with hp date coding could tell me the date of manuf. of this 5071a 
>
> 3608A01190
>
> Thanks,
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>
>   
Manufactured in USA during 8th week of 1996

Bruce


From aceamusements at mchsi.com  Fri Dec 12 04:40:30 2008
From: aceamusements at mchsi.com (aceamusements at mchsi.com)
Date: Fri, 12 Dec 2008 04:40:30 +0000
Subject: [time-nuts] Date codes on hp 5071a?
In-Reply-To: <4941E998.70909@xtra.co.nz>
References: <ad9f78230812111842j1851b9c3vb06b9294371863fe@mail.gmail.com>	<15AB6D7EF03C40CBA1DFF66C0BD4D724@pc52><121220080430.20468.4941E8FE0004E65B00004FF4223245003003010CD2079C080C03BF9C9B020A030A9C9A030E0A0C0E@mchsi.com>
	<4941E998.70909@xtra.co.nz>
Message-ID: <121220080440.9607.4941EB3E000B1C8600002587223245003003010CD2079C080C03BF9C9B020A030A9C9A030E0A0C0E@mchsi.com>


 
 Thanks,

I just purchased this on ebay and was just wondering how bad the tube could be(yrs left)

I have a agilent one now I got new a year ago and its ion pump current keeps rising,the one advertised says its still pretty low @ 2.0uA  ,1450emult..has telcom options installed so I bet it has lots of hrs but may be good for a few yrs?
 -------------- Original message from Bruce Griffiths <bruce.griffiths at xtra.co.nz>: --------------


> aceamusements at mchsi.com wrote:
> >  >  Hi,I was wondering by chance if someone familiar with hp date coding could 
> tell me the date of manuf. of this 5071a 
> >
> > 3608A01190
> >
> > Thanks,
> > _______________________________________________
> > time-nuts mailing list -- time-nuts at febo.com
> > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> > and follow the instructions there.
> >
> >   
> Manufactured in USA during 8th week of 1996
> 
> Bruce
> 
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.

From jmiles at pop.net  Fri Dec 12 04:39:43 2008
From: jmiles at pop.net (John Miles)
Date: Thu, 11 Dec 2008 20:39:43 -0800
Subject: [time-nuts] Date codes on hp 5071a?
In-Reply-To: <4941E998.70909@xtra.co.nz>
Message-ID: <PKEGJHPHLLBACEOICCBJAEMHPLAB.jmiles@pop.net>

The date code is not a production date, necessarily, but the date of that
particular design revision (presumably when it was released to
manufacturing).  It sets a lower bound, but your unit could potentially be
several years newer.  You can get a better idea by looking for the latest
date code on various ICs and capacitors.

-- john, KE5FX

> -----Original Message-----
> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com]On
> Behalf Of Bruce Griffiths
> Sent: Thursday, December 11, 2008 8:33 PM
> To: Discussion of precise time and frequency measurement
> Subject: Re: [time-nuts] Date codes on hp 5071a?
>
>
> aceamusements at mchsi.com wrote:
> >
> >  Hi,I was wondering by chance if someone familiar with hp date
> coding could tell me the date of manuf. of this 5071a
> >
> > 3608A01190
> >
> > Thanks,
> > _______________________________________________
> > time-nuts mailing list -- time-nuts at febo.com
> > To unsubscribe, go to
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> > and follow the instructions there.
> >
> >
> Manufactured in USA during 8th week of 1996
>
> Bruce
>
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>



From kirbybq at bellsouth.net  Fri Dec 12 06:34:51 2008
From: kirbybq at bellsouth.net (Brian Kirby)
Date: Fri, 12 Dec 2008 00:34:51 -0600
Subject: [time-nuts] pps vs. 10 MHz timing
In-Reply-To: <ad9f78230812111842j1851b9c3vb06b9294371863fe@mail.gmail.com>
References: <ad9f78230812111842j1851b9c3vb06b9294371863fe@mail.gmail.com>
Message-ID: <4942060B.1090607@bellsouth.net>

Are you using terminations or is the end equipment properly terminating 
?  Mismatched impedance does weird things to waveforms.  Also check to 
make sure you not overdriving on your source.  And a bad power supplies 
can induce waveform distortion.

Brian

Matt Ettus wrote:
> 
> 
> Also, I noticed that the TADD-1 has some weird distortion of a 10 MHz
> sine wave.  It turns it into a sort of a 3 valued square wave.
> Essentially, it stops and dwells at the midpoint for a while instead
> of making a sharp transition.  I think this would be bad if that dwell
> point is close to the threshold for the receiving device.  Has anyone
> else noticed this?
> 
> 
> Thanks,
> Matt
> 
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
> 


From magnus at rubidium.dyndns.org  Fri Dec 12 20:32:33 2008
From: magnus at rubidium.dyndns.org (Magnus Danielson)
Date: Fri, 12 Dec 2008 21:32:33 +0100
Subject: [time-nuts] pps vs. 10 MHz timing
In-Reply-To: <ad9f78230812111842j1851b9c3vb06b9294371863fe@mail.gmail.com>
References: <ad9f78230812111842j1851b9c3vb06b9294371863fe@mail.gmail.com>
Message-ID: <4942CA61.1020507@rubidium.dyndns.org>

Matt Ettus skrev:
> On my Oscilloquartz GPSDO, the 10 MHz output goes low at very close to
> the same time as the 1 PPS output goes high.
> 
> On my Fury, the 10 MHz sine wave is just dropping off of its max high
> voltage as the 1 PPS goes high.  The 10 MHz CMOS output goes high just
> shortly before the 1 PPS.
> 
> What do other GPSDOs do?

You can expect anything. Some buffers the PPS from the GPS engine and 
then make some more or less elaborate 10 MHz training algorithm. Don't 
expect rising edges to coinside for all of them.

> Clearly, any device trying to latch the 1 PPS signal using the 10 MHz
> clock will need to choose which clock edge to use, depending on which
> type of GPSDO is used.  How is this normally handled?

Depends, several approaches is possible. A simple approach is just a 
dual flip flop approach which is simple and straightforward. There is a 
risk for it to switch between 10 MHz cycle, but it may be acceptable for 
some applications. You could use any of many forms interpolating 
techniques to reduce or remove this risk. Exactly what you can achieve 
depends not only on the receiver hardware but also the transmitter side.

The trouble is that the 10 MHz + PPS is a very weekly defined interface 
which is not properly standardised. The only standard I know off is an 
old US MIL-STD document.

> Also, I noticed that the TADD-1 has some weird distortion of a 10 MHz
> sine wave.  It turns it into a sort of a 3 valued square wave.
> Essentially, it stops and dwells at the midpoint for a while instead
> of making a sharp transition.  I think this would be bad if that dwell
> point is close to the threshold for the receiving device.  Has anyone
> else noticed this?

Yes, on a signal not properly terminated. It occurs if you T a signal to 
your scope while the signal goes further on... to an open end. Then the 
reflex signal will create this type of dwelling.

Cheers,
Magnus


From bg at lysator.liu.se  Fri Dec 12 21:54:42 2008
From: bg at lysator.liu.se (=?ISO-8859-1?Q?Bj=F6rn?= Gabrielsson)
Date: Fri, 12 Dec 2008 22:54:42 +0100
Subject: [time-nuts] time-nuts Digest, Vol 53, Issue 46
In-Reply-To: <4941965B.5000105@pacific.net>
References: <mailman.291.1229028803.2499.time-nuts@febo.com>
	<BLU125-W12CCEA2F9496EAD108B9E5CEF80@phx.gbl>
	<4941965B.5000105@pacific.net>
Message-ID: <1229118882.5996.17.camel@bg-desktop>


On Thu, 2008-12-11 at 14:38 -0800, Brooke Clarke wrote:
> Hi Mark:
> 
> I think it's out of date.
> 
> The current method is to drop an optical corner cube (retro-reflector) in a 
> vacuum and using a laser measure the distance it moves (which requires a 
> reasonably good source of time.
> http://www.ngs.noaa.gov/GRD/GRAVITY/ABSG.html
> 
> Have Fun,
> 
> Brooke Clarke
> http://www.prc68.com
> 
> Mark Sims wrote:
> > The quintessential gravity meter (Worden Gravity Meter by Texas Instruments)...  still being made after 60 years or so:
> > http://www.mssu.edu/seg-vm/pict0246.html

Spring based (relative) gravimeters are NOT yet dead... 

   http://large.stanford.edu/courses/ph210/lee1/

and in local lingo for those so inclined... 

   http://www.lantmateriet.se/templates/LMV_Page.aspx?id=4912

These are not _as_ good, but very mobile

   http://inertialsensor.com/qa3000.shtml


--

   Bj?rn




From SAIDJACK at aol.com  Fri Dec 12 22:12:29 2008
From: SAIDJACK at aol.com (SAIDJACK at aol.com)
Date: Fri, 12 Dec 2008 17:12:29 EST
Subject: [time-nuts] pps vs. 10 MHz timing
Message-ID: <c3d.4a2be456.36743bcd@aol.com>

Hello Matt, Magnus,
 
unfortunately there will be a phase shift between the 1PPS and the  10MHz 
rising edge due to the nature of how we generate the 1PPS pulse from the  clean 
OCXO 10MHz signal.
 
But this trade-off allows us to offer the 1PPS phase-shift option via  the 
SERV:1PPS command.
 
We can simply shift the 1PPS by 16.66ns steps with the software command,  
which would not be possible if we had to align the signal to the 10MHz, 100ns  
period.
 
The system works by multiplying the 10MHz signal up to 60MHz using a PLL,  
then using a 60E6-to-1 divider with arbitrary phase alignment (selected by the  
user) to generate the clean 1PPS output. This allows a resolution of 16.66ns 
on  where to place the clean 1PPS using the serv:1pps command.
 
As Magnus has suggested, if you need a strict phase alignment, then using  
FF's to latch the 1PPS rising edge with the 10MHz signal can phase-align the two 
 signals. Due to metastability being possible, metastable-hardened FF's (from 
NXP  etc) should be used. Alternatively an external 10E6-to-1 divider could 
also be  used for this, clocked by the 10MHz signal. There would still be at 
least a  clock-to-output phase shift when using FPLD's etc to implement this  
divider.
 
BTW: by using the serv:1pps command for the coarse setting, and the  GPS 
antenna-delay command for fine-setting the user can place the 1PPS  pulse anywhere 
with 1ns resolution on the Fury GPSDO. The coarse 16.66ns steps  will be 
instantaneous, the 1ns antenna-delay steps will take some time for the  PLL to 
shift.
 
Hope that helps,
bye,
Said
 
 
 
 
In a message dated 12/12/2008 12:33:25 Pacific Standard Time,  
magnus at rubidium.dyndns.org writes:

Matt  Ettus skrev:
> On my Oscilloquartz GPSDO, the 10 MHz output goes low at  very close to
> the same time as the 1 PPS output goes high.
>  
> On my Fury, the 10 MHz sine wave is just dropping off of its max  high
> voltage as the 1 PPS goes high.  The 10 MHz CMOS output goes  high just
> shortly before the 1 PPS.
> 
> What do other  GPSDOs do?

You can expect anything. Some buffers the PPS from the GPS  engine and 
then make some more or less elaborate 10 MHz training  algorithm. Don't 
expect rising edges to coinside for all of  them.

> Clearly, any device trying to latch the 1 PPS signal using  the 10 MHz
> clock will need to choose which clock edge to use,  depending on which
> type of GPSDO is used.  How is this normally  handled?


From james.p.lux at jpl.nasa.gov  Fri Dec 12 22:15:52 2008
From: james.p.lux at jpl.nasa.gov (Lux, James P)
Date: Fri, 12 Dec 2008 14:15:52 -0800
Subject: [time-nuts] gravimeters
In-Reply-To: <1229118882.5996.17.camel@bg-desktop>
References: <mailman.291.1229028803.2499.time-nuts@febo.com>
	<BLU125-W12CCEA2F9496EAD108B9E5CEF80@phx.gbl>	<4941965B.5000105@pacific.net>
	<1229118882.5996.17.camel@bg-desktop>
Message-ID: <ECE7A93BD093E1439C20020FBE87C47FEB55DA8BA7@ALTPHYEMBEVSP20.RES.AD.JPL>

> -----Original Message-----
> From: time-nuts-bounces at febo.com
> [mailto:time-nuts-bounces at febo.com] On Behalf Of Bj?rn Gabrielsson
> Sent: Friday, December 12, 2008 1:55 PM
> To: brooke at pacific.net; Discussion of precise time and
> frequency measurement
> Subject: Re: [time-nuts] time-nuts Digest, Vol 53, Issue 46
>
>
> On Thu, 2008-12-11 at 14:38 -0800, Brooke Clarke wrote:
> > Hi Mark:
> >
> > I think it's out of date.
> >
> > The current method is to drop an optical corner cube
> (retro-reflector)
> > in a vacuum and using a laser measure the distance it moves (which
> > requires a reasonably good source of time.
> > http://www.ngs.noaa.gov/GRD/GRAVITY/ABSG.html
> >
> > Have Fun,
> >
> > Brooke Clarke
> > http://www.prc68.com
> >
> > Mark Sims wrote:
> > > The quintessential gravity meter (Worden Gravity Meter by
> Texas Instruments)...  still being made after 60 years or so:
> > > http://www.mssu.edu/seg-vm/pict0246.html
>
> Spring based (relative) gravimeters are NOT yet dead...
>
>    http://large.stanford.edu/courses/ph210/lee1/
>

See, there *is* a need for garage Liquid Helium plants...


From namichie at gmail.com  Fri Dec 12 22:40:47 2008
From: namichie at gmail.com (Neville Michie)
Date: Sat, 13 Dec 2008 09:40:47 +1100
Subject: [time-nuts] gravimeters
In-Reply-To: <ECE7A93BD093E1439C20020FBE87C47FEB55DA8BA7@ALTPHYEMBEVSP20.RES.AD.JPL>
References: <mailman.291.1229028803.2499.time-nuts@febo.com>
	<BLU125-W12CCEA2F9496EAD108B9E5CEF80@phx.gbl>	<4941965B.5000105@pacific.net>
	<1229118882.5996.17.camel@bg-desktop>
	<ECE7A93BD093E1439C20020FBE87C47FEB55DA8BA7@ALTPHYEMBEVSP20.RES.AD.JPL>
Message-ID: <206ADD7E-C88A-42A0-94C7-47628844397D@gmail.com>

The problem with helium is that it comes out of oil wells.
It does not cost much because they were digging up the oil anyway.
If what they say about peak oil is true, in 30 years or so there will  
be no
more helium and nowhere to get it, save tiny quantities from nuclear  
plants.
It seems to escape from earth's atmosphere to be lost for all time.
We should be doing all the research that needs helium now, because
we will not be able to do it in the future.
Every time my grand kids play with a helium balloon I feel guilty.
Neville mIchie


On 13/12/2008, at 9:15 AM, Lux, James P wrote:

>> -----Original Message-----
>> From: time-nuts-bounces at febo.com
>> [mailto:time-nuts-bounces at febo.com] On Behalf Of Bj?rn Gabrielsson
>> Sent: Friday, December 12, 2008 1:55 PM
>> To: brooke at pacific.net; Discussion of precise time and
>> frequency measurement
>> Subject: Re: [time-nuts] time-nuts Digest, Vol 53, Issue 46
>>
>>
>> On Thu, 2008-12-11 at 14:38 -0800, Brooke Clarke wrote:
>>> Hi Mark:
>>>
>>> I think it's out of date.
>>>
>>> The current method is to drop an optical corner cube
>> (retro-reflector)
>>> in a vacuum and using a laser measure the distance it moves (which
>>> requires a reasonably good source of time.
>>> http://www.ngs.noaa.gov/GRD/GRAVITY/ABSG.html
>>>
>>> Have Fun,
>>>
>>> Brooke Clarke
>>> http://www.prc68.com
>>>
>>> Mark Sims wrote:
>>>> The quintessential gravity meter (Worden Gravity Meter by
>> Texas Instruments)...  still being made after 60 years or so:
>>>> http://www.mssu.edu/seg-vm/pict0246.html
>>
>> Spring based (relative) gravimeters are NOT yet dead...
>>
>>    http://large.stanford.edu/courses/ph210/lee1/
>>
>
> See, there *is* a need for garage Liquid Helium plants...
>
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/ 
> time-nuts
> and follow the instructions there.



From magnus at rubidium.dyndns.org  Fri Dec 12 23:14:59 2008
From: magnus at rubidium.dyndns.org (Magnus Danielson)
Date: Sat, 13 Dec 2008 00:14:59 +0100
Subject: [time-nuts] pps vs. 10 MHz timing
In-Reply-To: <c3d.4a2be456.36743bcd@aol.com>
References: <c3d.4a2be456.36743bcd@aol.com>
Message-ID: <4942F073.7060200@rubidium.dyndns.org>

SAIDJACK at aol.com skrev:
> Hello Matt, Magnus,
>  
> unfortunately there will be a phase shift between the 1PPS and the  10MHz 
> rising edge due to the nature of how we generate the 1PPS pulse from the  clean 
> OCXO 10MHz signal.
>  
> But this trade-off allows us to offer the 1PPS phase-shift option via  the 
> SERV:1PPS command.
>  
> We can simply shift the 1PPS by 16.66ns steps with the software command,  
> which would not be possible if we had to align the signal to the 10MHz, 100ns  
> period.

Being able to fine-tune PPS-10 MHz phase relationship on the output is 
certainly a good thing.

Some have very tight requirements for this relationship, but it seems to 
me that they overspec it since they do not really know how things work 
and it is easy to verify. On the other hand, for some equipment I 
haven't seen any reasnoble specs at all on the inputs. Seems they have 
designed to match what their GPS gives them, whatever that is.

> The system works by multiplying the 10MHz signal up to 60MHz using a PLL,  
> then using a 60E6-to-1 divider with arbitrary phase alignment (selected by the  
> user) to generate the clean 1PPS output. This allows a resolution of 16.66ns 
> on  where to place the clean 1PPS using the serv:1pps command.

Sweet. Personally I did it a bit differently, but that's another thing. 
There are many things to implement the same thing.

> As Magnus has suggested, if you need a strict phase alignment, then using  
> FF's to latch the 1PPS rising edge with the 10MHz signal can phase-align the two 
>  signals. Due to metastability being possible, metastable-hardened FF's (from 
> NXP  etc) should be used. Alternatively an external 10E6-to-1 divider could 
> also be  used for this, clocked by the 10MHz signal. There would still be at 
> least a  clock-to-output phase shift when using FPLD's etc to implement this  
> divider.

You can use a FPLD for the counter state, but then use a good DFF to 
clock the state into a low jitter form. Since both is running of the 
same clock, just ensuring propper setup and hold times at the DFF input 
would suffice to ensure it is not be unstable. Just traditional engineering.

You really can't sync up some PPSes to the 10 MHz by simple DFFs since 
the variations may be more than 100 ns during some phases of the 
training and holdover shifts. The PPS output should always be generated 
using the 10 MHz such as they have a stable phase-relationship. The 
generated PPS is then compared to the source PPS and controlled phase 
adjustments should be done.

Cheers,
Magnus


From holrum at hotmail.com  Sat Dec 13 01:52:51 2008
From: holrum at hotmail.com (Mark Sims)
Date: Sat, 13 Dec 2008 01:52:51 +0000
Subject: [time-nuts] gravimeters
In-Reply-To: <mailman.3.1229083201.17624.time-nuts@febo.com>
References: <mailman.3.1229083201.17624.time-nuts@febo.com>
Message-ID: <BLU125-W24093AC08AB7CB7AD18700CEF60@phx.gbl>


There is just something nice about a 60 year old piece of technology (that is still being made and used daily) that can be schlepped by a trained ape (aka graduate student) to the remote corners of the earth and back and measure something as piddly as gravity to parts per billion resolution... and it is totally mechanical (except for perhaps a light bulb).

------------------

> Spring based (relative) gravimeters are NOT yet dead...
>
>    http://large.stanford.edu/courses/ph210/lee1/
>

See, there *is* a need for garage Liquid Helium plants...


_________________________________________________________________
Send e-mail anywhere. No map, no compass.
http://windowslive.com/Explore/hotmail?ocid=TXT_TAGLM_WL_hotmail_acq_anywhere_122008

From SAIDJACK at aol.com  Sat Dec 13 02:20:49 2008
From: SAIDJACK at aol.com (SAIDJACK at aol.com)
Date: Fri, 12 Dec 2008 21:20:49 EST
Subject: [time-nuts] pps vs. 10 MHz timing
Message-ID: <c17.4fbd16e5.36747601@aol.com>

Hi Magnus,
 
on our Fury system the phase relationship between the 1PPS (clean OCXO  
version) and the 10MHz is established during power-on, then held stable (it is  
generated by the same 10MHz crystal) unless it for some reason drifts more  than 
+/-220ns away from UTC at which point it is reset to UTC, or until it is  
changed by user-command.
 
We do also have the raw GPS 1PPS available (jumper selection option) which  
is asynchronous to the 10MHz, and as you mentioned will drift since it is  
generated by a separate crystal, and clocking system.
 
One could use two or three cascaded FF's two avoid the  
setup/hold/metastability issues, then set the phase via software command so as  to compensate for 
the FF-induced phase delays.
 
You are right, there are so many ways to cross that river :)
 
bye,
Said
 
 
In a message dated 12/12/2008 15:16:00 Pacific Standard Time,  
magnus at rubidium.dyndns.org writes:

You  really can't sync up some PPSes to the 10 MHz by simple DFFs since 
the  variations may be more than 100 ns during some phases of the 
training and  holdover shifts. The PPS output should always be generated 
using the 10  MHz such as they have a stable phase-relationship. The 
generated PPS is  then compared to the source PPS and controlled phase 
adjustments should be  done.

Cheers,
Magnus



From redrabbitlosangeles at yahoo.com  Sat Dec 13 09:21:47 2008
From: redrabbitlosangeles at yahoo.com (Randy Leifer)
Date: Sat, 13 Dec 2008 01:21:47 -0800 (PST)
Subject: [time-nuts] Build my own dist. amp ??
Message-ID: <667869.67900.qm@web35503.mail.mud.yahoo.com>

Can I build my own 10 MHz distribution amp, using fast opamps ?
I have searched the archives, but all of the designs are fairly complex for me to build using "point-to-point" on a proto/perf board.

I want to feed an oven-ized reference 10 MHz sine signal (50 ohm), as a master clock for my:
HP 3325A
Keithley Counter
PTS 160
and future gear.
(let's say, 1 in / 6 out)

Parts I have in stock are 
AD811
EL2030, 2070, 2090
CLC430
CLC200
LM7121
LM6165
Plus some LH0033 "damn fast" current boosting buffers, and some MH0007 clock drivers.
I don't build much high-freq stuff....but a lot of audio freq stuff.
My first thought is an input opamp buffer, branched off to separate line drivers.
Am I anywhere near to achieving my goal ?

Thanks.
=Randy=



      


From bruce.griffiths at xtra.co.nz  Sat Dec 13 09:52:56 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Sat, 13 Dec 2008 22:52:56 +1300
Subject: [time-nuts] Build my own dist. amp ??
In-Reply-To: <667869.67900.qm@web35503.mail.mud.yahoo.com>
References: <667869.67900.qm@web35503.mail.mud.yahoo.com>
Message-ID: <494385F8.7070902@xtra.co.nz>

Randy Leifer wrote:
> Can I build my own 10 MHz distribution amp, using fast opamps ?
> I have searched the archives, but all of the designs are fairly complex for me to build using "point-to-point" on a proto/perf board.
>
> I want to feed an oven-ized reference 10 MHz sine signal (50 ohm), as a master clock for my:
> HP 3325A
> Keithley Counter
> PTS 160
> and future gear.
> (let's say, 1 in / 6 out)
>
> Parts I have in stock are 
> AD811
> EL2030, 2070, 2090
> CLC430
> CLC200
> LM7121
> LM6165
> Plus some LH0033 "damn fast" current boosting buffers, and some MH0007 clock drivers.
> I don't build much high-freq stuff....but a lot of audio freq stuff.
> My first thought is an input opamp buffer, branched off to separate line drivers.
> Am I anywhere near to achieving my goal ?
>
> Thanks.
> =Randy=
>
>   
Randy

One can easily do this if the resultant performance is acceptable.
A discrete implementation almost invariably has a lower phase noise
floor and higher reverse isolation.

Current feedback amplifiers tend to be relatively noisy due to input
current noise flowing in the feedback resistor.
To keep the close in phase noise down the dc noise gain should be as low
as possible.

LH0033's were used in an early JPL design, however they are relatively
noisy especially in the flicker noise region.
If you really want it I have the circuit schematic.

The TADD1 designed by John Ackermann and available from TAPR is one
example of an opamp based distribution amplifier.
However a good discrete design can have a phase noise floor up to 20 dBc
lower.

If you do decide to use opamps then a low noise wide bandwidth voltage
feedback amplifier is usually a better choice than a current feedback
amplifier as the total ouput noise will be lower.

For a 10MHz isolation amplifier you dont need any transistors much more
exotic than 2N3904's in an appropriate package.
3 or 4  2N3904's per isolation amplifier stage will with careful design
and layout achieve a reverse isolation of more than 130dB.


Bruce


From rexa at sonic.net  Sat Dec 13 11:24:11 2008
From: rexa at sonic.net (Rex)
Date: Sat, 13 Dec 2008 03:24:11 -0800
Subject: [time-nuts] Build my own dist. amp ??
In-Reply-To: <494385F8.7070902@xtra.co.nz>
References: <667869.67900.qm@web35503.mail.mud.yahoo.com>
	<494385F8.7070902@xtra.co.nz>
Message-ID: <49439B5B.1060508@sonic.net>

Bruce Griffiths wrote:
> For a 10MHz isolation amplifier you dont need any transistors much more
> exotic than 2N3904's in an appropriate package.
> 3 or 4  2N3904's per isolation amplifier stage will with careful design
> and layout achieve a reverse isolation of more than 130dB.
>
>
> Bruce
>
>   

Bruce, you seem to have a tendency to tantalize. Couldn't you have 
pointed him to a reference (or two) to a pretty-darn-good circuit 
implementation that uses transistors?

I admit, I read most of the posts, but often I lose track and can't 
figure out if consensus is being achieved in the long threads.

Also, only being casually into all these time/frequency issues, I do 
lose track of some of the simplistic better things I thought I once knew.

Do we, or should we, have a FAQ? I know there are a couple or more great 
repositories provided by members. Many thanks to all you guys. But it 
seems like a lot of this could be covered by -- oh yes, go read number 7 
and then come back if you need more.

Has this been discussed before? Should we start a new thread or should I 
just shut up?



From yuri at ostry.ru  Sat Dec 13 13:12:09 2008
From: yuri at ostry.ru (Yuri Ostry)
Date: Sat, 13 Dec 2008 16:12:09 +0300
Subject: [time-nuts] gravimeters
In-Reply-To: <206ADD7E-C88A-42A0-94C7-47628844397D@gmail.com>
References: <mailman.291.1229028803.2499.time-nuts@febo.com>
	<BLU125-W12CCEA2F9496EAD108B9E5CEF80@phx.gbl>
	<4941965B.5000105@pacific.net>
	<1229118882.5996.17.camel@bg-desktop>
	<ECE7A93BD093E1439C20020FBE87C47FEB55DA8BA7@ALTPHYEMBEVSP20.RES.AD.JPL>
	<206ADD7E-C88A-42A0-94C7-47628844397D@gmail.com>
Message-ID: <1422346499.20081213161209@ostry.ru>

Hello,

Saturday, December 13, 2008, 1:40:47, Neville Michie wrote:

N> The problem with helium is that it comes out of oil wells.
N> It does not cost much because they were digging up the oil anyway.
N> If what they say about peak oil is true, in 30 years or so there will
N> be no
N> more helium and nowhere to get it, save tiny quantities from nuclear
N> plants.
N> It seems to escape from earth's atmosphere to be lost for all time.
N> We should be doing all the research that needs helium now, because
N> we will not be able to do it in the future.
N> Every time my grand kids play with a helium balloon I feel guilty.
N> Neville mIchie

I don't think that everything is so bad with helium supply. There is a
lots of He in a natural gas fields. There is some new gas fields in
Eastern Siberia where helium concentration exceeds 0.6% by volume. Few
large helium extraction plants located on large pipelines in Siberia
may double or triple world's helium supply easily. Winter temperatures
that sometimes goes well below -40 deg. centigrade there may make
process even more economical during cold season. The only real problem
is funding, as I understand this.

-- 
Best regards,
 Yuri                          mailto:yuri at ostry.ru



From bruce.griffiths at xtra.co.nz  Sat Dec 13 13:17:04 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Sun, 14 Dec 2008 02:17:04 +1300
Subject: [time-nuts] Build my own dist. amp ??
In-Reply-To: <49439B5B.1060508@sonic.net>
References: <667869.67900.qm@web35503.mail.mud.yahoo.com>	<494385F8.7070902@xtra.co.nz>
	<49439B5B.1060508@sonic.net>
Message-ID: <4943B5D0.40200@xtra.co.nz>

Rex wrote:
> Bruce Griffiths wrote:
>   
>> For a 10MHz isolation amplifier you dont need any transistors much more
>> exotic than 2N3904's in an appropriate package.
>> 3 or 4  2N3904's per isolation amplifier stage will with careful design
>> and layout achieve a reverse isolation of more than 130dB.
>>
>>
>> Bruce
>>
>>   
>>     
>
> Bruce, you seem to have a tendency to tantalize. Couldn't you have 
> pointed him to a reference (or two) to a pretty-darn-good circuit 
> implementation that uses transistors?
>
> I admit, I read most of the posts, but often I lose track and can't 
> figure out if consensus is being achieved in the long threads.
>
> Also, only being casually into all these time/frequency issues, I do 
> lose track of some of the simplistic better things I thought I once knew.
>
> Do we, or should we, have a FAQ? I know there are a couple or more great 
> repositories provided by members. Many thanks to all you guys. But it 
> seems like a lot of this could be covered by -- oh yes, go read number 7 
> and then come back if you need more.
>
> Has this been discussed before? Should we start a new thread or should I 
> just shut up?
>
>
>
>   
I've collected links to most of the useful references on isolation
amplifiers are at the bottom of:

http://www.ko4bb.com/~bruce/IsolationAmplifiers.html
<http://www.ko4bb.com/%7Ebruce/IsolationAmplifiers.html>

However, they don't include the earlier, less useful designs like the 2
JPL versions.


Rather than using perf board it would be better to assemble a TADD-1:
http://www.tapr.org/kits_tadd-1.html
Performance for which is shown:
http://www.febo.com/pages/amplifier_phase_noise/

http://www.leapsecond.com/pages/tadd-1/


To achieve good reverse isolation a good ground plane is essential.
If necessary one can use point to point wiring over a ground plane.

Once you've read these and decided if you want to build a discrete
distribution amplifier, I can show how these circuits can be used in
distribution amplifiers.


Bruce


From magnus at rubidium.dyndns.org  Sat Dec 13 17:53:37 2008
From: magnus at rubidium.dyndns.org (Magnus Danielson)
Date: Sat, 13 Dec 2008 18:53:37 +0100
Subject: [time-nuts] pps vs. 10 MHz timing
In-Reply-To: <c17.4fbd16e5.36747601@aol.com>
References: <c17.4fbd16e5.36747601@aol.com>
Message-ID: <4943F6A1.6030000@rubidium.dyndns.org>

SAIDJACK at aol.com skrev:
> Hi Magnus,
>  
> on our Fury system the phase relationship between the 1PPS (clean OCXO  
> version) and the 10MHz is established during power-on, then held stable (it is  
> generated by the same 10MHz crystal) unless it for some reason drifts more  than 
> +/-220ns away from UTC at which point it is reset to UTC, or until it is  
> changed by user-command.

This is indeed reasnoble. Depending on your application you may have 
some maximum frequency offset as well as maximum time offset. These can 
result in unnecessary long drift back times, so just jump in to the 
nearest 10 MHz cycle and glide in from there makes sense.

> We do also have the raw GPS 1PPS available (jumper selection option) which  
> is asynchronous to the 10MHz, and as you mentioned will drift since it is  
> generated by a separate crystal, and clocking system.

Indeed. As expected.

> One could use two or three cascaded FF's two avoid the  
> setup/hold/metastability issues, then set the phase via software command so as  to compensate for 
> the FF-induced phase delays.

Indeed.

> You are right, there are so many ways to cross that river :)

Certainly. As there is no standard of how this interface can be done, 
expect that almost any inconceivable way have been used. What is 
"obvious" to you may not be obvious to another, infact it could be 
viewed as contra-productive or comes at excess cost.

Cheers,
Magnus


From masondg44 at comcast.net  Sat Dec 13 18:43:05 2008
From: masondg44 at comcast.net (Dave M)
Date: Sat, 13 Dec 2008 13:43:05 -0500
Subject: [time-nuts] Build my own dist. amp ??
References: <mailman.1.1229169601.30901.time-nuts@febo.com>
Message-ID: <D480AC43450E4B03848DCCE08FADD4AD@DELL2350>

Randy,
There are a couple distribution amp projects on the RealHamRadio web site (http://www.realhamradio.com).  One has 8 isolated 75-ohm outputs; the other has 3 non-isolated outputs.  Here are the links to each:

http://www.realhamradio.com/10mhz-video-amp.htm
http://www.realhamradio.com/g8lmx-amplifier.htm

Neither uses any of your parts, but shouldn't be unreasonable in price.

-- 
Dave M
MasonDG44 at comcast dot net  (Just substitute the appropriate characters in the address)

Life is like a roll of toilet paper; the closer it gets to the end, the faster it goes. 

  ----- Original Message ----- 

  Date: Sat, 13 Dec 2008 01:21:47 -0800 (PST)
  From: Randy Leifer <redrabbitlosangeles at yahoo.com>
  Subject: [time-nuts] Build my own dist. amp ??
  To: time-nuts at febo.com
  Message-ID: <667869.67900.qm at web35503.mail.mud.yahoo.com>
  Content-Type: text/plain; charset=us-ascii

  Can I build my own 10 MHz distribution amp, using fast opamps ?
  I have searched the archives, but all of the designs are fairly complex for me to build using "point-to-point" on a proto/perf board.

  I want to feed an oven-ized reference 10 MHz sine signal (50 ohm), as a master clock for my:
  HP 3325A
  Keithley Counter
  PTS 160
  and future gear.
  (let's say, 1 in / 6 out)

  Parts I have in stock are 
  AD811
  EL2030, 2070, 2090
  CLC430
  CLC200
  LM7121
  LM6165
  Plus some LH0033 "damn fast" current boosting buffers, and some MH0007 clock drivers.
  I don't build much high-freq stuff....but a lot of audio freq stuff.
  My first thought is an input opamp buffer, branched off to separate line drivers.
  Am I anywhere near to achieving my goal ?

  Thanks.
  =Randy=


From w1ksz at earthlink.net  Sat Dec 13 18:57:36 2008
From: w1ksz at earthlink.net (Richard W. Solomon)
Date: Sat, 13 Dec 2008 11:57:36 -0700 (GMT-07:00)
Subject: [time-nuts] Build my own dist. amp ??
Message-ID: <23493233.1229194656705.JavaMail.root@mswamui-blood.atl.sa.earthlink.net>

It would be nice if the second link had a source for the boards.

73, Dick, W1KSZ

-----Original Message-----
>From: Dave M <masondg44 at comcast.net>
>Sent: Dec 13, 2008 11:43 AM
>To: time-nuts at febo.com
>Subject: Re: [time-nuts] Build my own dist. amp ??
>
>Randy,
>There are a couple distribution amp projects on the RealHamRadio web site (http://www.realhamradio.com).  One has 8 isolated 75-ohm outputs; the other has 3 non-isolated outputs.  Here are the links to each:
>
>http://www.realhamradio.com/10mhz-video-amp.htm
>http://www.realhamradio.com/g8lmx-amplifier.htm
>
>Neither uses any of your parts, but shouldn't be unreasonable in price.
>
>-- 
>Dave M
>MasonDG44 at comcast dot net  (Just substitute the appropriate characters in the address)
>
>Life is like a roll of toilet paper; the closer it gets to the end, the faster it goes. 
>
>  ----- Original Message ----- 
>
>  Date: Sat, 13 Dec 2008 01:21:47 -0800 (PST)
>  From: Randy Leifer <redrabbitlosangeles at yahoo.com>
>  Subject: [time-nuts] Build my own dist. amp ??
>  To: time-nuts at febo.com
>  Message-ID: <667869.67900.qm at web35503.mail.mud.yahoo.com>
>  Content-Type: text/plain; charset=us-ascii
>
>  Can I build my own 10 MHz distribution amp, using fast opamps ?
>  I have searched the archives, but all of the designs are fairly complex for me to build using "point-to-point" on a proto/perf board.
>
>  I want to feed an oven-ized reference 10 MHz sine signal (50 ohm), as a master clock for my:
>  HP 3325A
>  Keithley Counter
>  PTS 160
>  and future gear.
>  (let's say, 1 in / 6 out)
>
>  Parts I have in stock are 
>  AD811
>  EL2030, 2070, 2090
>  CLC430
>  CLC200
>  LM7121
>  LM6165
>  Plus some LH0033 "damn fast" current boosting buffers, and some MH0007 clock drivers.
>  I don't build much high-freq stuff....but a lot of audio freq stuff.
>  My first thought is an input opamp buffer, branched off to separate line drivers.
>  Am I anywhere near to achieving my goal ?
>
>  Thanks.
>  =Randy=
>
>_______________________________________________
>time-nuts mailing list -- time-nuts at febo.com
>To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>and follow the instructions there.



From danrae at verizon.net  Sat Dec 13 19:16:56 2008
From: danrae at verizon.net (Dan Rae)
Date: Sat, 13 Dec 2008 11:16:56 -0800
Subject: [time-nuts] Build my own dist. amp ??
In-Reply-To: <D480AC43450E4B03848DCCE08FADD4AD@DELL2350>
References: <mailman.1.1229169601.30901.time-nuts@febo.com>
	<D480AC43450E4B03848DCCE08FADD4AD@DELL2350>
Message-ID: <49440A28.9030602@verizon.net>

Dave M wrote:
> Randy,
> There are a couple distribution amp projects on the RealHamRadio web site (http://www.realhamradio.com).  One has 8 isolated 75-ohm outputs; the other has 3 non-isolated outputs.  Here are the links to each:
>
> http://www.realhamradio.com/10mhz-video-amp.htm
> http://www.realhamradio.com/g8lmx-amplifier.htm
>
>   
Dave, the problem with those, and indeed the TAPR kit eventually, is 
that all the Maxim ICs involved have been discontinued, and are no 
longer easily sourced.
dr



From jra at febo.com  Sat Dec 13 19:25:00 2008
From: jra at febo.com (John Ackermann N8UR)
Date: Sat, 13 Dec 2008 14:25:00 -0500
Subject: [time-nuts] Build my own dist. amp ??
In-Reply-To: <49440A28.9030602@verizon.net>
References: <mailman.1.1229169601.30901.time-nuts@febo.com>	<D480AC43450E4B03848DCCE08FADD4AD@DELL2350>
	<49440A28.9030602@verizon.net>
Message-ID: <49440C0C.9000800@febo.com>

Dan Rae said the following on 12/13/2008 02:16 PM:

> Dave, the problem with those, and indeed the TAPR kit eventually, is 
> that all the Maxim ICs involved have been discontinued, and are no 
> longer easily sourced.

The MAX477 is indeed going away, but it appears to still be available
without ridiculous leadtimes, despite what the Maxim order page says.
We bought a bunch for another run of TADD-1 kits back in September and
had no trouble getting them quickly.  Of course, that will change at
some point.

John



From redrabbitlosangeles at yahoo.com  Sat Dec 13 19:28:01 2008
From: redrabbitlosangeles at yahoo.com (Randy Leifer)
Date: Sat, 13 Dec 2008 11:28:01 -0800 (PST)
Subject: [time-nuts] VRefs - I'm a bigger Voltnut than a timenut..
Message-ID: <796985.19837.qm@web35502.mail.mud.yahoo.com>

Bigger Volt-nut here.
...albeit, less knowledgeable than most of you.
I have been in the chase for the perfect volt.
I have 2 JRL SCO-105 saturated cell references running 24/7.
But checking it's accuracy....I must rely on my cal'd HP3457 meter.
Although, those cells (6 total, 3 in each cabinet) are pretty stable, and good for determining drift of the Vrefs I build.
I have a Geller 5v, and I've built a few of my own refs using some 
National LM399AH-50 along with a chopper buffer. 
(these LM399's come with a 1000 hr burn-in and a drift plot)
I am getting a 10uV drift with these circuits, but that is over a +/- 15* F ambient temp range (as is the voltmeter)...and they're only in plastic cases in open air--not shielded yet.
http://i5.photobucket.com/albums/y177/Midiot/my_lm399_ref.gif

I am currently building/testing/tweaking a temp stable insulated enclosure,
using a Peltier, a 5 watt controller, and 0.1% glass thermistors.....to house my Vrefs and some standard resistors. 
I am shooting for 25* C, but the outside air still has an slight effect on the internal air (+/- 0.5* C on the inside).....not bad but I think I can do better. I put a low-ohm thermistor outside the box, in series with the main sensing thermistor inside, and this helps. But this may be a whole new topic.
I'm up for a Vref project. How about you?

=Randy=


      


From bruce.griffiths at xtra.co.nz  Sat Dec 13 19:48:24 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Sun, 14 Dec 2008 08:48:24 +1300
Subject: [time-nuts] VRefs - I'm a bigger Voltnut than a timenut..
In-Reply-To: <796985.19837.qm@web35502.mail.mud.yahoo.com>
References: <796985.19837.qm@web35502.mail.mud.yahoo.com>
Message-ID: <49441188.4070808@xtra.co.nz>

Randy Leifer wrote:
> Bigger Volt-nut here.
> ...albeit, less knowledgeable than most of you.
> I have been in the chase for the perfect volt.
> I have 2 JRL SCO-105 saturated cell references running 24/7.
> But checking it's accuracy....I must rely on my cal'd HP3457 meter.
> Although, those cells (6 total, 3 in each cabinet) are pretty stable, and good for determining drift of the Vrefs I build.
> I have a Geller 5v, and I've built a few of my own refs using some 
> National LM399AH-50 along with a chopper buffer. 
> (these LM399's come with a 1000 hr burn-in and a drift plot)
> I am getting a 10uV drift with these circuits, but that is over a +/- 15* F ambient temp range (as is the voltmeter)...and they're only in plastic cases in open air--not shielded yet.
> http://i5.photobucket.com/albums/y177/Midiot/my_lm399_ref.gif
>
> I am currently building/testing/tweaking a temp stable insulated enclosure,
> using a Peltier, a 5 watt controller, and 0.1% glass thermistors.....to house my Vrefs and some standard resistors. 
> I am shooting for 25* C, but the outside air still has an slight effect on the internal air (+/- 0.5* C on the inside).....not bad but I think I can do better. I put a low-ohm thermistor outside the box, in series with the main sensing thermistor inside, and this helps. But this may be a whole new topic.
> I'm up for a Vref project. How about you?
>
> =Randy=
>
>   
An LTZ1000 or LTZ1000A based reference will have better long term stability.
One can even build in a thermal conditioning cycle to "anneal" out
voltage shifts that occur when starting up after the reference loses power.

Bruce


From bruce.griffiths at xtra.co.nz  Sat Dec 13 19:52:15 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Sun, 14 Dec 2008 08:52:15 +1300
Subject: [time-nuts] Build my own dist. amp ??
In-Reply-To: <D480AC43450E4B03848DCCE08FADD4AD@DELL2350>
References: <mailman.1.1229169601.30901.time-nuts@febo.com>
	<D480AC43450E4B03848DCCE08FADD4AD@DELL2350>
Message-ID: <4944126F.8060307@xtra.co.nz>

Dave M wrote:
> Randy,
> There are a couple distribution amp projects on the RealHamRadio web site (http://www.realhamradio.com).  One has 8 isolated 75-ohm outputs; the other has 3 non-isolated outputs.  Here are the links to each:
>
> http://www.realhamradio.com/10mhz-video-amp.htm
> http://www.realhamradio.com/g8lmx-amplifier.htm
>
> Neither uses any of your parts, but shouldn't be unreasonable in price.
>
>   
Both of these designs flout at least some of the now well established
low phase noise design rules.

Expecting a MAX 477 to drive several 50 ohm loads in parallel at any
significant level is somewhat optimistic.

Using devices int the same package or a single opamp to drive the
individual loads compromises interchannel isolation.

Bruce


From SAIDJACK at aol.com  Sat Dec 13 20:56:36 2008
From: SAIDJACK at aol.com (SAIDJACK at aol.com)
Date: Sat, 13 Dec 2008 15:56:36 EST
Subject: [time-nuts] gravimeters
Message-ID: <d41.2f5f910d.36757b84@aol.com>

Hello Yuri, Neville,
 
interesting discussion about natural resources. I hear that with  the global 
soon-to-be-depression that some things may happen (sorry for the  slightly 
off-topic subject, but this may affect us Time Nuts too):
 
* Used high-end equipment will be available for fire-sale prices, much like  
the dot-com-bomb days here in Silicon Valley, except this will now be a  
global phenomenon due to Ebay, bankruptcies, reduction in  demand/production, etc. 
I am looking out for that high-end phase noise system,  and inexpensive 
5071A...
 
* Many folks will unfortunately be out of a job, and will have to live from  
savings. We are seeing this here in Silicon Valley in a big way now.
 
* Fiat currencies, especially the US $ will tank in value due to excessive  
"printing" of the same, making assets in the US a very attractive  investment 
for our friends overseas.
 
* Natural resources especially Gold, Silver, Oil, Helium, etc will rise in  
price due to reduction of production, and backwardation (we have Gold  
backwardation for the first time ever since December 2nd on the Comex), and  
flight-to-safety
 
* Some say there could be civil unrest due to lack of resources, say  heating 
oil, gas, food, etc. Having a Ham station at home may help here. See  what 
happened in Greece over the last week.
 
This could be a long and painful process; with proper preparation one may  
actually come out of this with one's savings more or less intact, and great  
opportunities to invest in wonderful equipment for the time nut.
 
I hope for the best for everyone.
bye,
Said
 
 
 
In a message dated 12/13/2008 05:12:52 Pacific Standard Time, yuri at ostry.ru  
writes:

I don't  think that everything is so bad with helium supply. There is a
lots of He  in a natural gas fields. There is some new gas fields in
Eastern Siberia  where helium concentration exceeds 0.6% by volume. Few
large helium  extraction plants located on large pipelines in Siberia
may double or  triple world's helium supply easily. Winter temperatures
that sometimes  goes well below -40 deg. centigrade there may make
process even more  economical during cold season. The only real problem
is funding, as I  understand this.

-- 
Best regards,
Yuri        mailto:yuri at ostry.ru




From glennmaillist at bellsouth.net  Sat Dec 13 21:11:25 2008
From: glennmaillist at bellsouth.net (Glenn Little WB4UIV)
Date: Sat, 13 Dec 2008 16:11:25 -0500
Subject: [time-nuts] Build my own dist. amp ??
In-Reply-To: <49440A28.9030602@verizon.net>
References: <mailman.1.1229169601.30901.time-nuts@febo.com>
	<D480AC43450E4B03848DCCE08FADD4AD@DELL2350>
	<49440A28.9030602@verizon.net>
Message-ID: <6.2.3.4.2.20081213160706.04ec8620@mail.bellsouth.net>

With TV stations shifting to digital, how would a surplus analog 
video distribution amplifier do?

There should be a lot of high end amplifiers made by Grass Valley 
(Tektronix) available soon.

These are used in a frame. The input loops through the frame. Each 
amplifier has 6 isolated outputs. Depending on the amplifier, you 
might have control over the equalization or not. All that I have seen 
allow the amplifier gain to be adjusted from the front of the module.

73
Glenn
WB4UIV

At 02:16 PM 12/13/2008, you wrote:
>Dave M wrote:
> > Randy,
> > There are a couple distribution amp projects on the RealHamRadio 
> web site (http://www.realhamradio.com).  One has 8 isolated 75-ohm 
> outputs; the other has 3 non-isolated outputs.  Here are the links to each:
> >
> > http://www.realhamradio.com/10mhz-video-amp.htm
> > http://www.realhamradio.com/g8lmx-amplifier.htm
> >
> >
>Dave, the problem with those, and indeed the TAPR kit eventually, is
>that all the Maxim ICs involved have been discontinued, and are no
>longer easily sourced.
>dr
>
>
>_______________________________________________
>time-nuts mailing list -- time-nuts at febo.com
>To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>and follow the instructions there.



From bruce.griffiths at xtra.co.nz  Sat Dec 13 21:22:27 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Sun, 14 Dec 2008 10:22:27 +1300
Subject: [time-nuts] Build my own dist. amp ??
In-Reply-To: <6.2.3.4.2.20081213160706.04ec8620@mail.bellsouth.net>
References: <mailman.1.1229169601.30901.time-nuts@febo.com>	<D480AC43450E4B03848DCCE08FADD4AD@DELL2350>	<49440A28.9030602@verizon.net>
	<6.2.3.4.2.20081213160706.04ec8620@mail.bellsouth.net>
Message-ID: <49442793.6040701@xtra.co.nz>

Glenn Little WB4UIV wrote:
> With TV stations shifting to digital, how would a surplus analog 
> video distribution amplifier do?
>
> There should be a lot of high end amplifiers made by Grass Valley 
> (Tektronix) available soon.
>
> These are used in a frame. The input loops through the frame. Each 
> amplifier has 6 isolated outputs. Depending on the amplifier, you 
> might have control over the equalization or not. All that I have seen 
> allow the amplifier gain to be adjusted from the front of the module.
>
> 73
> Glenn
> WB4UIV
>
>   
>   
If and only if you can live with the likely poor phase noise and isolation.
Equalisation is not necessary or even particularly useful for a single
output frequency.

Bruce



From wittend at wwrinc.com  Sat Dec 13 21:30:53 2008
From: wittend at wwrinc.com (David M. Witten II)
Date: Sat, 13 Dec 2008 15:30:53 -0600
Subject: [time-nuts] gravimeters, Helium
Message-ID: <4944298D.400@wwrinc.com>

I am surprised that helium reclamation pumps are not beginning to appear 
as surplus.  We are several (technological) generations into the period 
where supercooled MRI magnets are present in every town over 10,000 
population in the US.  Medical MRI has been in use for around 20 yrs, 
and though the demand for used equipment resold into less affluent 
markets hasn't probably been saturated, some of the squeaky little 
buggers should begin to turn up just because of their age.

Dave Witten
KD0EAG


From joegeller at roadrunner.com  Sat Dec 13 22:21:17 2008
From: joegeller at roadrunner.com (Joe Geller)
Date: Sat, 13 Dec 2008 17:21:17 -0500
Subject: [time-nuts] Low Cost Voltage Transfer References
Message-ID: <20081213172117.561354@avacado08>

I thought I might make a couple of comments about the Geller SVR board (I am a long time Time-Nuts reader, although sometimes only an occasional reader of the archives).  

The SVR board is nothing more than a high quality platform for a monolithic reference chip.  The goal of this project was to provide a relatively low cost way to transfer voltage calibration (primarily with hobbyists and amateur scientists in mind).  The SVR board is not intended to be a ?voltage standard?.  The absolute calibration of our set point is directly traceable to our Fluke 732B, which is in the Fluke calibration program.  We rate the transfer accuracy at +/- 5 ppm which I believe to be conservative.  With some care, generally a 2 to 3 ppm absolute transfer accuracy is realizable.  In recent years, most SVR boards are burned-in for 200 hours before final calibration.

Although there has been some industry support for the project, including some support from ADI, this project has largely been accomplished at a financial loss.  Our costs include the hp3458A, the Fluke 732B, (including overnight shipping, calibration cost is over $500 / year) not to mention component parts, shipping boxes, and eBay and PayPal fees.  

Since the relatively low cost AD587LN grade is now discontinued, I have been debating whether to continue testing and design efforts and to continue the low cost transfer project, or to just abandon the effort altogether.  There have been several promising new reference chips in recent years, yet none so far that match the performance of the AD587LN considering stability with time, stability with temperature, output noise spectrum (both below 10 Hz and higher frequency noise), stability with power supply, stability with load (output drive), and ease of assembly and use.  

I agree that the LTZ1000 appears to be the best ovenized reference available, especially with burn-in temperature cycling techniques and/or part selection.  However, at >$35 per part in quantity, and the need for an amplifier, and ultra low tempco scaling resistors, it does not appear to be practical for use in a low cost product.

Regards,

Joe Geller


From eb4apl at cembreros.jazztel.es  Sun Dec 14 00:25:29 2008
From: eb4apl at cembreros.jazztel.es (EB4APL)
Date: Sun, 14 Dec 2008 01:25:29 +0100
Subject: [time-nuts] OCXO info request
In-Reply-To: <49440A28.9030602@verizon.net>
References: <mailman.1.1229169601.30901.time-nuts@febo.com>	<D480AC43450E4B03848DCCE08FADD4AD@DELL2350>
	<49440A28.9030602@verizon.net>
Message-ID: <49445279.6040702@cembreros.jazztel.es>

Hi,
Since there is plenty of experience here, I want to locate info about an 
OCXO.  It is an HP 00105-6013, that probably came from a Rb or Cesium 
frequency standard.   Al pins and connectors are labeled with its 
function and even it has the crystal temp marked on the label.
TYA,
Ignacio


From rfnuts at arcor.de  Sun Dec 14 00:44:50 2008
From: rfnuts at arcor.de (Adrian)
Date: Sun, 14 Dec 2008 01:44:50 +0100
Subject: [time-nuts] OCXO info request
In-Reply-To: <49445279.6040702@cembreros.jazztel.es>
References: <mailman.1.1229169601.30901.time-nuts@febo.com>	<D480AC43450E4B03848DCCE08FADD4AD@DELL2350>	<49440A28.9030602@verizon.net>
	<49445279.6040702@cembreros.jazztel.es>
Message-ID: <49445702.7050006@arcor.de>

Ignacio,

for details check:
http://www.ko4bb.com/cgi-bin/manuals.pl?dir=HP_Agilent/HP_-_105
Early 105A/B's came with the 00105-6013 OCXO, as covered by the above 
manual.

Adrian

EB4APL schrieb:
> Hi,
> Since there is plenty of experience here, I want to locate info about an 
> OCXO.  It is an HP 00105-6013, that probably came from a Rb or Cesium 
> frequency standard.   Al pins and connectors are labeled with its 
> function and even it has the crystal temp marked on the label.
> TYA,
> Ignacio
>
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>
>   



From eb4apl at cembreros.jazztel.es  Sun Dec 14 01:53:14 2008
From: eb4apl at cembreros.jazztel.es (EB4APL)
Date: Sun, 14 Dec 2008 02:53:14 +0100
Subject: [time-nuts] OCXO info request
In-Reply-To: <49445702.7050006@arcor.de>
References: <mailman.1.1229169601.30901.time-nuts@febo.com>	<D480AC43450E4B03848DCCE08FADD4AD@DELL2350>	<49440A28.9030602@verizon.net>	<49445279.6040702@cembreros.jazztel.es>
	<49445702.7050006@arcor.de>
Message-ID: <4944670A.9040107@cembreros.jazztel.es>

OK Adrian, thank you.  Probably it is a good candidate to be disciplined.
Ignacio


Adrian escribi?:
> Ignacio,
>
> for details check:
> http://www.ko4bb.com/cgi-bin/manuals.pl?dir=HP_Agilent/HP_-_105
> Early 105A/B's came with the 00105-6013 OCXO, as covered by the above 
> manual.
>
> Adrian
>
> EB4APL schrieb:
>   
>> Hi,
>> Since there is plenty of experience here, I want to locate info about an 
>> OCXO.  It is an HP 00105-6013, that probably came from a Rb or Cesium 
>> frequency standard.   Al pins and connectors are labeled with its 
>> function and even it has the crystal temp marked on the label.
>> TYA,
>> Ignacio
>>
>> _______________________________________________
>>
>>     

From XDE-L2G3 at myamail.com  Sun Dec 14 13:07:16 2008
From: XDE-L2G3 at myamail.com (Mike Monett)
Date: Sun, 14 Dec 2008 08:07:16 -0500
Subject: [time-nuts] Low Cost Voltage Transfer References
References: <mailman.1.1229256002.8253.time-nuts@febo.com>
Message-ID: <mailman.3.1229260072.2496.time-nuts@febo.com>

  > I thought  I might make a couple of comments about the  Geller SVR
  > board (I am a long time Time-Nuts reader, although  sometimes only
  > an occasional reader of the archives).

  > The SVR  board is nothing more than a high quality platform  for a
  > monolithic reference chip. The goal of this project was to provide
  > a relatively  low   cost   way   to  transfer  voltage calibration
  > (primarily with hobbyists and amateur scientists in mind). The SVR
  > board is  not  intended  to be a  voltage  standard.  The absolute
  > calibration of  our set point is directly traceable  to  our Fluke
  > 732B, which  is  in  the Fluke calibration  program.  We  rate the
  > transfer accuracy at +/- 5 ppm which I believe to be conservative.

  > With some care, generally a 2 to 3 ppm absolute  transfer accuracy
  > is realizable. In recent years, most SVR boards are  burned-in for
  > 200 hours before final calibration.

  > Although there  has  been some industry support  for  the project,
  > including some  support  from ADI, this project  has  largely been
  > accomplished at  a financial loss. Our costs include  the hp3458A,
  > the Fluke 732B, (including overnight shipping, calibration cost is
  > over $500 / year) not to mention component parts,  shipping boxes,
  > and eBay and PayPal fees.

  > Since the relatively low cost AD587LN grade is now discontinued, I
  > have been debating whether to continue testing and  design efforts
  > and to continue the low cost transfer project, or to  just abandon
  > the effort  altogether.  There  have  been  several  promising new
  > reference chips  in recent years, yet none so far  that  match the
  > performance of  the   AD587LN   considering  stability  with time,
  > stability with  temperature, output noise spectrum (both  below 10
  > Hz and  higher  frequency  noise),  stability  with  power supply,
  > stability with load (output drive), and ease of assembly and use.

  > I agree that the LTZ1000 appears to be the best ovenized reference
  > available, especially with burn-in temperature  cycling techniques
  > and/or part selection. However, at >$35 per part in  quantity, and
  > the need for an amplifier, and ultra low tempco scaling resistors,
  > it does not appear to be practical for use in a low cost product.

  > Regards,

  > Joe Geller

  Hi Joe,

  I want  to  congratulate  you for your excellent  work.  You  have a
  well-deserved reputation for quality and fair dealing.

  It is  unfortunate the AD587LN is no longer available,  but  would a
  part like the AD780BN be suitable? It lists for only $6.39, which is
  considerably considerably better than the LTZ1000:

 
http://www.analog.com/en/other/militaryaerospace/ad780/products/product.html

  The AD780BN spec is 3ppm/C part vs the 5ppm/C of the AD587, so it is
  a bit  more stable with temperature. Both references  have  the same
  noise spec  of 100nV/sqrt(Hz). The initial accuracy is a  bit better
  at 1mV,  but I don't see anything on long-term stability  for either
  part.

  If it  is  suitable, it seems your customers may  not  mind  a small
  increase in  price,   especially   considering   the  improvement in
  performance over  the AD587LN. Also, I'm sure if you  put  the above
  explanation on your web site, your customers would certainly find it
  understandable if  you  increased your price to cover  the  costs of
  maintaining the  product. In fact, many products do better  when the
  price is raised to match the customer's perception of the  value. So
  keeping a  low  price may give the wrong  impression  of  the actual
  caliber of the service.

  It would be a shame to see such a valuable concept disappear. I'd go
  for it.

  Regards,

  Mike Monett

  P.S. I  liked  your page on the HP 53310A. I have the  file  you are
  missing, so if you would like, I can email it to you along with some
  others that might be useful. 


From brice at weaponeer.com  Mon Dec 15 06:22:49 2008
From: brice at weaponeer.com (brice at weaponeer.com)
Date: Mon, 15 Dec 2008 06:22:49 +0000
Subject: [time-nuts] =?utf-8?q?=2224_hour_birth_celebration_period=22?=
Message-ID: <W203893088715731229322169@webmail45>

Here is a new one, unless I missed a previous post. 
Turn 40 tomorrow, no woohoo required.

Tricky part, 
Birth certificate 12/15/68 / 01:30 am (no seconds)
Add leap years and seconds, can determine approximate, but no exact time. 
Sent to my brother, add 2-3 beers:

-----
I want to do the math when it comes to leap years/seconds to find out to the second when the big 40 rolls over.
(Was born early in the morning), Tomorrow is close enough for family even though my curiosity tells me to determine a more realistic time.
Some would argue that birth is a process has no particular event time and you could never pinpoint anything.
The math becomes pointless when you factor in your sense of time and disruption due to circumstance vs. reality.
I think Mr Einstein Had a midlife crisis himself. Math is pointless without reference.
------

Maybe i'm I barking up the wrong tree, there a possible close to accurate time I can mark, trusting the documentation is correct.
A little different than a rubidium standard. Take out the philosophical stuff.

Cheers, William.
(Hope I have another 40.... or somthing close)


From david.partridge at dsl.pipex.com  Mon Dec 15 10:03:54 2008
From: david.partridge at dsl.pipex.com (David C. Partridge)
Date: Mon, 15 Dec 2008 10:03:54 -0000
Subject: [time-nuts] OT: Levelled sine wave generator
Message-ID: <55B98184B0414ECD9D7B3BA16F5FB9A7@APOLLO>

Sort of related, but only just - however the signal to noise ratio here is
so good that I feel impelled to ask.

For 'scope calibration I'm considering building a levelled sine wave
generator.

Ideally the specs I'm looking for are:

 o Close to DC (10kHz or 100kHz would be fine) up to at least 1GHz.
 	more would be better but not critical

 o Output levels from 0.5Vp-p(-2dBm) to at least 4Vp-p(+16dBm) into 50R
	 (up to >6Vp-p(say +20dBm) would be better)

 o Output flatness levelled within 2% of desired output level (+/- 0.086dB)
	across the entire frequency range at the final connector to the DUT
	This will almost certainly mean an external levelling head.

 o Modulation - not critical, FM or AM might be useful.

 o A logarithmic sweep capability might be nice, but isn't necessary.

 o Frequency display - nice to have but output to external counter is OK.

Generating the basic signal is probably just a case of using something like
an HP VTO-8200, mixing it with 2GHz (Mini-Circuits RMS30?), low pass filter,
an AGC stage (see below) and then amplify probably using an MMIC like the
Mini-Circuits ERA-2SM followed by an additional stage to get the extra few
dB.   For more accurate frequency control some sort of synthesiser locked to
a reference might be in order (I had to get a time-nuts hook in here
somehow).

The question is what should go in the sensor head?

Logically I need to sample a proportion of the signal delivered to the
output connector, compare the output of the sensor against a DC reference
level telling it the desired output level, and feed back a voltage to a
wideband AGC stage (any suggestions for this?) in the main unit.   I also
need to be able to detect that output is not levelled.

Or should I just forget the whole idea and go talk to R&S with a large
cheque in hand?

Cheers
Dave



From bruce.griffiths at xtra.co.nz  Mon Dec 15 10:29:36 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Mon, 15 Dec 2008 23:29:36 +1300
Subject: [time-nuts] OT: Levelled sine wave generator
In-Reply-To: <55B98184B0414ECD9D7B3BA16F5FB9A7@APOLLO>
References: <55B98184B0414ECD9D7B3BA16F5FB9A7@APOLLO>
Message-ID: <49463190.8010708@xtra.co.nz>

David C. Partridge wrote:
> Sort of related, but only just - however the signal to noise ratio here is
> so good that I feel impelled to ask.
>
> For 'scope calibration I'm considering building a levelled sine wave
> generator.
>
> Ideally the specs I'm looking for are:
>
>  o Close to DC (10kHz or 100kHz would be fine) up to at least 1GHz.
>  	more would be better but not critical
>
>  o Output levels from 0.5Vp-p(-2dBm) to at least 4Vp-p(+16dBm) into 50R
> 	 (up to >6Vp-p(say +20dBm) would be better)
>
>  o Output flatness levelled within 2% of desired output level (+/- 0.086dB)
> 	across the entire frequency range at the final connector to the DUT
> 	This will almost certainly mean an external levelling head.
>
>  o Modulation - not critical, FM or AM might be useful.
>
>  o A logarithmic sweep capability might be nice, but isn't necessary.
>
>  o Frequency display - nice to have but output to external counter is OK.
>
> Generating the basic signal is probably just a case of using something like
> an HP VTO-8200, mixing it with 2GHz (Mini-Circuits RMS30?), low pass filter,
> an AGC stage (see below) and then amplify probably using an MMIC like the
> Mini-Circuits ERA-2SM followed by an additional stage to get the extra few
> dB.   For more accurate frequency control some sort of synthesiser locked to
> a reference might be in order (I had to get a time-nuts hook in here
> somehow).
>
> The question is what should go in the sensor head?
>
> Logically I need to sample a proportion of the signal delivered to the
> output connector, compare the output of the sensor against a DC reference
> level telling it the desired output level, and feed back a voltage to a
> wideband AGC stage (any suggestions for this?) in the main unit.   I also
> need to be able to detect that output is not levelled.
>
> Or should I just forget the whole idea and go talk to R&S with a large
> cheque in hand?
>
> Cheers
> Dave
>   
The phase noise wont be particularly low especially for low output
frequencies.

A diode double balanced mixer with dc current applied to the IF port is
useful as a wideband current controlled AGC device.

NB mixer IF response must extend to dc.

Bruce


From magnus at rubidium.dyndns.org  Mon Dec 15 11:08:22 2008
From: magnus at rubidium.dyndns.org (Magnus Danielson)
Date: Mon, 15 Dec 2008 12:08:22 +0100
Subject: [time-nuts] OT: Levelled sine wave generator
In-Reply-To: <49463190.8010708@xtra.co.nz>
References: <55B98184B0414ECD9D7B3BA16F5FB9A7@APOLLO>
	<49463190.8010708@xtra.co.nz>
Message-ID: <49463AA6.60407@rubidium.dyndns.org>

Bruce Griffiths skrev:
> David C. Partridge wrote:
>> Sort of related, but only just - however the signal to noise ratio here is
>> so good that I feel impelled to ask.
>>
>> For 'scope calibration I'm considering building a levelled sine wave
>> generator.
>>
>> Ideally the specs I'm looking for are:
>>
>>  o Close to DC (10kHz or 100kHz would be fine) up to at least 1GHz.
>>  	more would be better but not critical
>>
>>  o Output levels from 0.5Vp-p(-2dBm) to at least 4Vp-p(+16dBm) into 50R
>> 	 (up to >6Vp-p(say +20dBm) would be better)
>>
>>  o Output flatness levelled within 2% of desired output level (+/- 0.086dB)
>> 	across the entire frequency range at the final connector to the DUT
>> 	This will almost certainly mean an external levelling head.
>>
>>  o Modulation - not critical, FM or AM might be useful.
>>
>>  o A logarithmic sweep capability might be nice, but isn't necessary.
>>
>>  o Frequency display - nice to have but output to external counter is OK.
>>
>> Generating the basic signal is probably just a case of using something like
>> an HP VTO-8200, mixing it with 2GHz (Mini-Circuits RMS30?), low pass filter,
>> an AGC stage (see below) and then amplify probably using an MMIC like the
>> Mini-Circuits ERA-2SM followed by an additional stage to get the extra few
>> dB.   For more accurate frequency control some sort of synthesiser locked to
>> a reference might be in order (I had to get a time-nuts hook in here
>> somehow).
>>
>> The question is what should go in the sensor head?
>>
>> Logically I need to sample a proportion of the signal delivered to the
>> output connector, compare the output of the sensor against a DC reference
>> level telling it the desired output level, and feed back a voltage to a
>> wideband AGC stage (any suggestions for this?) in the main unit.   I also
>> need to be able to detect that output is not levelled.
>>
>> Or should I just forget the whole idea and go talk to R&S with a large
>> cheque in hand?
>>
>> Cheers
>> Dave
>>   
> The phase noise wont be particularly low especially for low output
> frequencies.

I think this is acceptable for the intended application.

> A diode double balanced mixer with dc current applied to the IF port is
> useful as a wideband current controlled AGC device.

Indeed. BTW, I used that trick when using my network analyzer for 
sweeping the Caesium-beam. I unplugged the 12,6 MHz and inserted my 
output port which was split to also go into a mixer. I picked up the 
detector voltage and feed it into the IF port and the resulting 
modulated sine was sent to the receiver port. Worked like a charm and 
provided me with a nice user-interface.

> NB mixer IF response must extend to dc.

It should not be too hard to find a suitable mixer that matches that 
description thought.

As for sensor-head, an old technique is to use a pair of diodes 
thermically connected, where one is fed a 100 kHz square wave and the 
other is used as a detector. The reference diode is bias adjusted and 
the reading from the other is compensated with the same amount and thus 
allowing for a linearization. I don't know if there is any modern ways 
which is more suitable. I think it could be a bit of a challenge for 
detecting it all the way down. I'm sure Bruce can elaborate some on that.

One possible issue would be that input impedance could mess things up. 
So maybe one should consider making quadrature readings in the head such 
that with some processing the propper level can be given considering the 
impedance mismatch. For the intended repeatability this might be 
something to consider.

Cheers,
Magnus


From bruce.griffiths at xtra.co.nz  Mon Dec 15 11:31:33 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Tue, 16 Dec 2008 00:31:33 +1300
Subject: [time-nuts] OT: Levelled sine wave generator
In-Reply-To: <49463AA6.60407@rubidium.dyndns.org>
References: <55B98184B0414ECD9D7B3BA16F5FB9A7@APOLLO>	<49463190.8010708@xtra.co.nz>
	<49463AA6.60407@rubidium.dyndns.org>
Message-ID: <49464015.3020508@xtra.co.nz>

Magnus Danielson wrote:
> Bruce Griffiths skrev:
>   
>> David C. Partridge wrote:
>>     
>>> Sort of related, but only just - however the signal to noise ratio here is
>>> so good that I feel impelled to ask.
>>>
>>> For 'scope calibration I'm considering building a levelled sine wave
>>> generator.
>>>
>>> Ideally the specs I'm looking for are:
>>>
>>>  o Close to DC (10kHz or 100kHz would be fine) up to at least 1GHz.
>>>  	more would be better but not critical
>>>
>>>  o Output levels from 0.5Vp-p(-2dBm) to at least 4Vp-p(+16dBm) into 50R
>>> 	 (up to >6Vp-p(say +20dBm) would be better)
>>>
>>>  o Output flatness levelled within 2% of desired output level (+/- 0.086dB)
>>> 	across the entire frequency range at the final connector to the DUT
>>> 	This will almost certainly mean an external levelling head.
>>>
>>>  o Modulation - not critical, FM or AM might be useful.
>>>
>>>  o A logarithmic sweep capability might be nice, but isn't necessary.
>>>
>>>  o Frequency display - nice to have but output to external counter is OK.
>>>
>>> Generating the basic signal is probably just a case of using something like
>>> an HP VTO-8200, mixing it with 2GHz (Mini-Circuits RMS30?), low pass filter,
>>> an AGC stage (see below) and then amplify probably using an MMIC like the
>>> Mini-Circuits ERA-2SM followed by an additional stage to get the extra few
>>> dB.   For more accurate frequency control some sort of synthesiser locked to
>>> a reference might be in order (I had to get a time-nuts hook in here
>>> somehow).
>>>
>>> The question is what should go in the sensor head?
>>>
>>> Logically I need to sample a proportion of the signal delivered to the
>>> output connector, compare the output of the sensor against a DC reference
>>> level telling it the desired output level, and feed back a voltage to a
>>> wideband AGC stage (any suggestions for this?) in the main unit.   I also
>>> need to be able to detect that output is not levelled.
>>>
>>> Or should I just forget the whole idea and go talk to R&S with a large
>>> cheque in hand?
>>>
>>> Cheers
>>> Dave
>>>   
>>>       
>> The phase noise wont be particularly low especially for low output
>> frequencies.
>>     
>
> I think this is acceptable for the intended application.
>
>   
>> A diode double balanced mixer with dc current applied to the IF port is
>> useful as a wideband current controlled AGC device.
>>     
>
> Indeed. BTW, I used that trick when using my network analyzer for 
> sweeping the Caesium-beam. I unplugged the 12,6 MHz and inserted my 
> output port which was split to also go into a mixer. I picked up the 
> detector voltage and feed it into the IF port and the resulting 
> modulated sine was sent to the receiver port. Worked like a charm and 
> provided me with a nice user-interface.
>
>   
>> NB mixer IF response must extend to dc.
>>     
>
> It should not be too hard to find a suitable mixer that matches that 
> description thought.
>
> As for sensor-head, an old technique is to use a pair of diodes 
> thermically connected, where one is fed a 100 kHz square wave and the 
> other is used as a detector. The reference diode is bias adjusted and 
> the reading from the other is compensated with the same amount and thus 
> allowing for a linearization. I don't know if there is any modern ways 
> which is more suitable. I think it could be a bit of a challenge for 
> detecting it all the way down. I'm sure Bruce can elaborate some on that.
>
> One possible issue would be that input impedance could mess things up. 
> So maybe one should consider making quadrature readings in the head such 
> that with some processing the propper level can be given considering the 
> impedance mismatch. For the intended repeatability this might be 
> something to consider.
>
> Cheers,
> Magnus
>
>   

Since the oscillator is intended for oscilloscope scope calibration the
leveling detector can operate with a fixed input level and an attenuator
can be used to set the output level.
A resistive splitter will have a wider operating frequency range than
most alternatives.

Diode detectors using a pair of matched diodes can be very stable.
NIST once used an elaborate coaxial dual diode differential RF detector
arrangement complete with temperature stabilisation.

Bruce



From wb6bnq at cox.net  Mon Dec 15 11:40:27 2008
From: wb6bnq at cox.net (WB6BNQ)
Date: Mon, 15 Dec 2008 03:40:27 -0800
Subject: [time-nuts] OT: Levelled sine wave generator
References: <55B98184B0414ECD9D7B3BA16F5FB9A7@APOLLO>	<49463190.8010708@xtra.co.nz>
	<49463AA6.60407@rubidium.dyndns.org> <49464015.3020508@xtra.co.nz>
Message-ID: <4946422B.6B7B32A@cox.net>

Bruce Griffiths wrote:

> Magnus Danielson wrote:
> > Bruce Griffiths skrev:
> >
> >> David C. Partridge wrote:
> >>
> >>> Sort of related, but only just - however the signal to noise ratio here is
> >>> so good that I feel impelled to ask.
> >>>
> >>> For 'scope calibration I'm considering building a levelled sine wave
> >>> generator.
> >>>
> >>> Ideally the specs I'm looking for are:
> >>>
> >>>  o Close to DC (10kHz or 100kHz would be fine) up to at least 1GHz.
> >>>     more would be better but not critical
> >>>
> >>>  o Output levels from 0.5Vp-p(-2dBm) to at least 4Vp-p(+16dBm) into 50R
> >>>      (up to >6Vp-p(say +20dBm) would be better)
> >>>
> >>>  o Output flatness levelled within 2% of desired output level (+/- 0.086dB)
> >>>     across the entire frequency range at the final connector to the DUT
> >>>     This will almost certainly mean an external levelling head.
> >>>
> >>>  o Modulation - not critical, FM or AM might be useful.
> >>>
> >>>  o A logarithmic sweep capability might be nice, but isn't necessary.
> >>>
> >>>  o Frequency display - nice to have but output to external counter is OK.
> >>>
> >>> Generating the basic signal is probably just a case of using something like
> >>> an HP VTO-8200, mixing it with 2GHz (Mini-Circuits RMS30?), low pass filter,
> >>> an AGC stage (see below) and then amplify probably using an MMIC like the
> >>> Mini-Circuits ERA-2SM followed by an additional stage to get the extra few
> >>> dB.   For more accurate frequency control some sort of synthesiser locked to
> >>> a reference might be in order (I had to get a time-nuts hook in here
> >>> somehow).
> >>>
> >>> The question is what should go in the sensor head?
> >>>
> >>> Logically I need to sample a proportion of the signal delivered to the
> >>> output connector, compare the output of the sensor against a DC reference
> >>> level telling it the desired output level, and feed back a voltage to a
> >>> wideband AGC stage (any suggestions for this?) in the main unit.   I also
> >>> need to be able to detect that output is not levelled.
> >>>
> >>> Or should I just forget the whole idea and go talk to R&S with a large
> >>> cheque in hand?
> >>>
> >>> Cheers
> >>> Dave
> >>>
> >>>
> >> The phase noise wont be particularly low especially for low output
> >> frequencies.
> >>
> >
> > I think this is acceptable for the intended application.
> >
> >
> >> A diode double balanced mixer with dc current applied to the IF port is
> >> useful as a wideband current controlled AGC device.
> >>
> >
> > Indeed. BTW, I used that trick when using my network analyzer for
> > sweeping the Caesium-beam. I unplugged the 12,6 MHz and inserted my
> > output port which was split to also go into a mixer. I picked up the
> > detector voltage and feed it into the IF port and the resulting
> > modulated sine was sent to the receiver port. Worked like a charm and
> > provided me with a nice user-interface.
> >
> >
> >> NB mixer IF response must extend to dc.
> >>
> >
> > It should not be too hard to find a suitable mixer that matches that
> > description thought.
> >
> > As for sensor-head, an old technique is to use a pair of diodes
> > thermically connected, where one is fed a 100 kHz square wave and the
> > other is used as a detector. The reference diode is bias adjusted and
> > the reading from the other is compensated with the same amount and thus
> > allowing for a linearization. I don't know if there is any modern ways
> > which is more suitable. I think it could be a bit of a challenge for
> > detecting it all the way down. I'm sure Bruce can elaborate some on that.
> >
> > One possible issue would be that input impedance could mess things up.
> > So maybe one should consider making quadrature readings in the head such
> > that with some processing the propper level can be given considering the
> > impedance mismatch. For the intended repeatability this might be
> > something to consider.
> >
> > Cheers,
> > Magnus
> >
> >
>
> Since the oscillator is intended for oscilloscope scope calibration the
> leveling detector can operate with a fixed input level and an attenuator
> can be used to set the output level.
> A resistive splitter will have a wider operating frequency range than
> most alternatives.
>
> Diode detectors using a pair of matched diodes can be very stable.
> NIST once used an elaborate coaxial dual diode differential RF detector
> arrangement complete with temperature stabilisation.
>
> Bruce

What about some of the "log" detector made by Analog Devices ?

Bill....WB6BNQ

'




From bruce.griffiths at xtra.co.nz  Mon Dec 15 11:41:10 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Tue, 16 Dec 2008 00:41:10 +1300
Subject: [time-nuts] OT: Levelled sine wave generator
In-Reply-To: <49464015.3020508@xtra.co.nz>
References: <55B98184B0414ECD9D7B3BA16F5FB9A7@APOLLO>	<49463190.8010708@xtra.co.nz>	<49463AA6.60407@rubidium.dyndns.org>
	<49464015.3020508@xtra.co.nz>
Message-ID: <49464256.4030504@xtra.co.nz>

Bruce Griffiths wrote:
> Magnus Danielson wrote:
>   
>> Bruce Griffiths skrev:
>>   
>>     
>>> David C. Partridge wrote:
>>>     
>>>       
>>>> Sort of related, but only just - however the signal to noise ratio here is
>>>> so good that I feel impelled to ask.
>>>>
>>>> For 'scope calibration I'm considering building a levelled sine wave
>>>> generator.
>>>>
>>>> Ideally the specs I'm looking for are:
>>>>
>>>>  o Close to DC (10kHz or 100kHz would be fine) up to at least 1GHz.
>>>>  	more would be better but not critical
>>>>
>>>>  o Output levels from 0.5Vp-p(-2dBm) to at least 4Vp-p(+16dBm) into 50R
>>>> 	 (up to >6Vp-p(say +20dBm) would be better)
>>>>
>>>>  o Output flatness levelled within 2% of desired output level (+/- 0.086dB)
>>>> 	across the entire frequency range at the final connector to the DUT
>>>> 	This will almost certainly mean an external levelling head.
>>>>
>>>>  o Modulation - not critical, FM or AM might be useful.
>>>>
>>>>  o A logarithmic sweep capability might be nice, but isn't necessary.
>>>>
>>>>  o Frequency display - nice to have but output to external counter is OK.
>>>>
>>>> Generating the basic signal is probably just a case of using something like
>>>> an HP VTO-8200, mixing it with 2GHz (Mini-Circuits RMS30?), low pass filter,
>>>> an AGC stage (see below) and then amplify probably using an MMIC like the
>>>> Mini-Circuits ERA-2SM followed by an additional stage to get the extra few
>>>> dB.   For more accurate frequency control some sort of synthesiser locked to
>>>> a reference might be in order (I had to get a time-nuts hook in here
>>>> somehow).
>>>>
>>>> The question is what should go in the sensor head?
>>>>
>>>> Logically I need to sample a proportion of the signal delivered to the
>>>> output connector, compare the output of the sensor against a DC reference
>>>> level telling it the desired output level, and feed back a voltage to a
>>>> wideband AGC stage (any suggestions for this?) in the main unit.   I also
>>>> need to be able to detect that output is not levelled.
>>>>
>>>> Or should I just forget the whole idea and go talk to R&S with a large
>>>> cheque in hand?
>>>>
>>>> Cheers
>>>> Dave
>>>>   
>>>>       
>>>>         
>>> The phase noise wont be particularly low especially for low output
>>> frequencies.
>>>     
>>>       
>> I think this is acceptable for the intended application.
>>
>>   
>>     
>>> A diode double balanced mixer with dc current applied to the IF port is
>>> useful as a wideband current controlled AGC device.
>>>     
>>>       
>> Indeed. BTW, I used that trick when using my network analyzer for 
>> sweeping the Caesium-beam. I unplugged the 12,6 MHz and inserted my 
>> output port which was split to also go into a mixer. I picked up the 
>> detector voltage and feed it into the IF port and the resulting 
>> modulated sine was sent to the receiver port. Worked like a charm and 
>> provided me with a nice user-interface.
>>
>>   
>>     
>>> NB mixer IF response must extend to dc.
>>>     
>>>       
>> It should not be too hard to find a suitable mixer that matches that 
>> description thought.
>>
>> As for sensor-head, an old technique is to use a pair of diodes 
>> thermically connected, where one is fed a 100 kHz square wave and the 
>> other is used as a detector. The reference diode is bias adjusted and 
>> the reading from the other is compensated with the same amount and thus 
>> allowing for a linearization. I don't know if there is any modern ways 
>> which is more suitable. I think it could be a bit of a challenge for 
>> detecting it all the way down. I'm sure Bruce can elaborate some on that.
>>
>> One possible issue would be that input impedance could mess things up. 
>> So maybe one should consider making quadrature readings in the head such 
>> that with some processing the propper level can be given considering the 
>> impedance mismatch. For the intended repeatability this might be 
>> something to consider.
>>
>> Cheers,
>> Magnus
>>
>>   
>>     
>
> Since the oscillator is intended for oscilloscope scope calibration the
> leveling detector can operate with a fixed input level and an attenuator
> can be used to set the output level.
> A resistive splitter will have a wider operating frequency range than
> most alternatives.
>
> Diode detectors using a pair of matched diodes can be very stable.
> NIST once used an elaborate coaxial dual diode differential RF detector
> arrangement complete with temperature stabilisation.
>
> Bruce
>
>   
Detector reference:

http://ts.nist.gov/MeasurementServices/Calibrations/upload/78-871.PDF


Bruce


From bruce.griffiths at xtra.co.nz  Mon Dec 15 11:54:48 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Tue, 16 Dec 2008 00:54:48 +1300
Subject: [time-nuts] OT: Levelled sine wave generator
In-Reply-To: <4946422B.6B7B32A@cox.net>
References: <55B98184B0414ECD9D7B3BA16F5FB9A7@APOLLO>	<49463190.8010708@xtra.co.nz>	<49463AA6.60407@rubidium.dyndns.org>
	<49464015.3020508@xtra.co.nz> <4946422B.6B7B32A@cox.net>
Message-ID: <49464588.905@xtra.co.nz>

WB6BNQ wrote:
> Bruce Griffiths wrote:
>
>   
>> Magnus Danielson wrote:
>>     
>>> Bruce Griffiths skrev:
>>>
>>>       
>>>> David C. Partridge wrote:
>>>>
>>>>         
>>>>> Sort of related, but only just - however the signal to noise ratio here is
>>>>> so good that I feel impelled to ask.
>>>>>
>>>>> For 'scope calibration I'm considering building a levelled sine wave
>>>>> generator.
>>>>>
>>>>> Ideally the specs I'm looking for are:
>>>>>
>>>>>  o Close to DC (10kHz or 100kHz would be fine) up to at least 1GHz.
>>>>>     more would be better but not critical
>>>>>
>>>>>  o Output levels from 0.5Vp-p(-2dBm) to at least 4Vp-p(+16dBm) into 50R
>>>>>      (up to >6Vp-p(say +20dBm) would be better)
>>>>>
>>>>>  o Output flatness levelled within 2% of desired output level (+/- 0.086dB)
>>>>>     across the entire frequency range at the final connector to the DUT
>>>>>     This will almost certainly mean an external levelling head.
>>>>>
>>>>>  o Modulation - not critical, FM or AM might be useful.
>>>>>
>>>>>  o A logarithmic sweep capability might be nice, but isn't necessary.
>>>>>
>>>>>  o Frequency display - nice to have but output to external counter is OK.
>>>>>
>>>>> Generating the basic signal is probably just a case of using something like
>>>>> an HP VTO-8200, mixing it with 2GHz (Mini-Circuits RMS30?), low pass filter,
>>>>> an AGC stage (see below) and then amplify probably using an MMIC like the
>>>>> Mini-Circuits ERA-2SM followed by an additional stage to get the extra few
>>>>> dB.   For more accurate frequency control some sort of synthesiser locked to
>>>>> a reference might be in order (I had to get a time-nuts hook in here
>>>>> somehow).
>>>>>
>>>>> The question is what should go in the sensor head?
>>>>>
>>>>> Logically I need to sample a proportion of the signal delivered to the
>>>>> output connector, compare the output of the sensor against a DC reference
>>>>> level telling it the desired output level, and feed back a voltage to a
>>>>> wideband AGC stage (any suggestions for this?) in the main unit.   I also
>>>>> need to be able to detect that output is not levelled.
>>>>>
>>>>> Or should I just forget the whole idea and go talk to R&S with a large
>>>>> cheque in hand?
>>>>>
>>>>> Cheers
>>>>> Dave
>>>>>
>>>>>
>>>>>           
>>>> The phase noise wont be particularly low especially for low output
>>>> frequencies.
>>>>
>>>>         
>>> I think this is acceptable for the intended application.
>>>
>>>
>>>       
>>>> A diode double balanced mixer with dc current applied to the IF port is
>>>> useful as a wideband current controlled AGC device.
>>>>
>>>>         
>>> Indeed. BTW, I used that trick when using my network analyzer for
>>> sweeping the Caesium-beam. I unplugged the 12,6 MHz and inserted my
>>> output port which was split to also go into a mixer. I picked up the
>>> detector voltage and feed it into the IF port and the resulting
>>> modulated sine was sent to the receiver port. Worked like a charm and
>>> provided me with a nice user-interface.
>>>
>>>
>>>       
>>>> NB mixer IF response must extend to dc.
>>>>
>>>>         
>>> It should not be too hard to find a suitable mixer that matches that
>>> description thought.
>>>
>>> As for sensor-head, an old technique is to use a pair of diodes
>>> thermically connected, where one is fed a 100 kHz square wave and the
>>> other is used as a detector. The reference diode is bias adjusted and
>>> the reading from the other is compensated with the same amount and thus
>>> allowing for a linearization. I don't know if there is any modern ways
>>> which is more suitable. I think it could be a bit of a challenge for
>>> detecting it all the way down. I'm sure Bruce can elaborate some on that.
>>>
>>> One possible issue would be that input impedance could mess things up.
>>> So maybe one should consider making quadrature readings in the head such
>>> that with some processing the propper level can be given considering the
>>> impedance mismatch. For the intended repeatability this might be
>>> something to consider.
>>>
>>> Cheers,
>>> Magnus
>>>
>>>
>>>       
>> Since the oscillator is intended for oscilloscope scope calibration the
>> leveling detector can operate with a fixed input level and an attenuator
>> can be used to set the output level.
>> A resistive splitter will have a wider operating frequency range than
>> most alternatives.
>>
>> Diode detectors using a pair of matched diodes can be very stable.
>> NIST once used an elaborate coaxial dual diode differential RF detector
>> arrangement complete with temperature stabilisation.
>>
>> Bruce
>>     
>
> What about some of the "log" detector made by Analog Devices ?
>
> Bill....WB6BNQ
>
>   
Their operating frequency range isnt large enough.
If the frequency response extends to dc the upper limit is less than 1GHz.
When the frequency response extends to 1GHz or more the lower limit isnt
low enough.
The Analog Devices tru-power rms detectors are similarly afflicted.

Bruce



From wb6bnq at cox.net  Mon Dec 15 12:02:43 2008
From: wb6bnq at cox.net (WB6BNQ)
Date: Mon, 15 Dec 2008 04:02:43 -0800
Subject: [time-nuts] OT: Levelled sine wave generator
References: <55B98184B0414ECD9D7B3BA16F5FB9A7@APOLLO>	<49463190.8010708@xtra.co.nz>	<49463AA6.60407@rubidium.dyndns.org>
	<49464015.3020508@xtra.co.nz> <4946422B.6B7B32A@cox.net>
	<49464588.905@xtra.co.nz>
Message-ID: <49464763.A046CDE9@cox.net>

Bruce Griffiths wrote:

> WB6BNQ wrote:
> > Bruce Griffiths wrote:
> >
> >
> >> Magnus Danielson wrote:
> >>
> >>> Bruce Griffiths skrev:
> >>>
> >>>
> >>>> David C. Partridge wrote:
> >>>>
> >>>>
> >>>>> Sort of related, but only just - however the signal to noise ratio here is
> >>>>> so good that I feel impelled to ask.
> >>>>>
> >>>>> For 'scope calibration I'm considering building a levelled sine wave
> >>>>> generator.
> >>>>>
> >>>>> Ideally the specs I'm looking for are:
> >>>>>
> >>>>>  o Close to DC (10kHz or 100kHz would be fine) up to at least 1GHz.
> >>>>>     more would be better but not critical
> >>>>>
> >>>>>  o Output levels from 0.5Vp-p(-2dBm) to at least 4Vp-p(+16dBm) into 50R
> >>>>>      (up to >6Vp-p(say +20dBm) would be better)
> >>>>>
> >>>>>  o Output flatness levelled within 2% of desired output level (+/- 0.086dB)
> >>>>>     across the entire frequency range at the final connector to the DUT
> >>>>>     This will almost certainly mean an external levelling head.
> >>>>>
> >>>>>  o Modulation - not critical, FM or AM might be useful.
> >>>>>
> >>>>>  o A logarithmic sweep capability might be nice, but isn't necessary.
> >>>>>
> >>>>>  o Frequency display - nice to have but output to external counter is OK.
> >>>>>
> >>>>> Generating the basic signal is probably just a case of using something like
> >>>>> an HP VTO-8200, mixing it with 2GHz (Mini-Circuits RMS30?), low pass filter,
> >>>>> an AGC stage (see below) and then amplify probably using an MMIC like the
> >>>>> Mini-Circuits ERA-2SM followed by an additional stage to get the extra few
> >>>>> dB.   For more accurate frequency control some sort of synthesiser locked to
> >>>>> a reference might be in order (I had to get a time-nuts hook in here
> >>>>> somehow).
> >>>>>
> >>>>> The question is what should go in the sensor head?
> >>>>>
> >>>>> Logically I need to sample a proportion of the signal delivered to the
> >>>>> output connector, compare the output of the sensor against a DC reference
> >>>>> level telling it the desired output level, and feed back a voltage to a
> >>>>> wideband AGC stage (any suggestions for this?) in the main unit.   I also
> >>>>> need to be able to detect that output is not levelled.
> >>>>>
> >>>>> Or should I just forget the whole idea and go talk to R&S with a large
> >>>>> cheque in hand?
> >>>>>
> >>>>> Cheers
> >>>>> Dave
> >>>>>
> >>>>>
> >>>>>
> >>>> The phase noise wont be particularly low especially for low output
> >>>> frequencies.
> >>>>
> >>>>
> >>> I think this is acceptable for the intended application.
> >>>
> >>>
> >>>
> >>>> A diode double balanced mixer with dc current applied to the IF port is
> >>>> useful as a wideband current controlled AGC device.
> >>>>
> >>>>
> >>> Indeed. BTW, I used that trick when using my network analyzer for
> >>> sweeping the Caesium-beam. I unplugged the 12,6 MHz and inserted my
> >>> output port which was split to also go into a mixer. I picked up the
> >>> detector voltage and feed it into the IF port and the resulting
> >>> modulated sine was sent to the receiver port. Worked like a charm and
> >>> provided me with a nice user-interface.
> >>>
> >>>
> >>>
> >>>> NB mixer IF response must extend to dc.
> >>>>
> >>>>
> >>> It should not be too hard to find a suitable mixer that matches that
> >>> description thought.
> >>>
> >>> As for sensor-head, an old technique is to use a pair of diodes
> >>> thermically connected, where one is fed a 100 kHz square wave and the
> >>> other is used as a detector. The reference diode is bias adjusted and
> >>> the reading from the other is compensated with the same amount and thus
> >>> allowing for a linearization. I don't know if there is any modern ways
> >>> which is more suitable. I think it could be a bit of a challenge for
> >>> detecting it all the way down. I'm sure Bruce can elaborate some on that.
> >>>
> >>> One possible issue would be that input impedance could mess things up.
> >>> So maybe one should consider making quadrature readings in the head such
> >>> that with some processing the propper level can be given considering the
> >>> impedance mismatch. For the intended repeatability this might be
> >>> something to consider.
> >>>
> >>> Cheers,
> >>> Magnus
> >>>
> >>>
> >>>
> >> Since the oscillator is intended for oscilloscope scope calibration the
> >> leveling detector can operate with a fixed input level and an attenuator
> >> can be used to set the output level.
> >> A resistive splitter will have a wider operating frequency range than
> >> most alternatives.
> >>
> >> Diode detectors using a pair of matched diodes can be very stable.
> >> NIST once used an elaborate coaxial dual diode differential RF detector
> >> arrangement complete with temperature stabilisation.
> >>
> >> Bruce
> >>
> >
> > What about some of the "log" detector made by Analog Devices ?
> >
> > Bill....WB6BNQ
> >
> >
> Their operating frequency range isnt large enough.
> If the frequency response extends to dc the upper limit is less than 1GHz.
> When the frequency response extends to 1GHz or more the lower limit isnt
> low enough.
> The Analog Devices tru-power rms detectors are similarly afflicted.
>
> Bruce
>

Good point !  Perhaps a combination could be dreamed up where two such detectors could
be used with some kind of cross-over scheme derived from the frequency generator.
This way optimization could be performed with two or more such detectors as I think
the cost per detector may not be that much.  A thought anyway.

Bill....WB6BNQ

'




From didier at cox.net  Mon Dec 15 12:28:36 2008
From: didier at cox.net (Didier)
Date: Mon, 15 Dec 2008 06:28:36 -0600
Subject: [time-nuts] OT: Levelled sine wave generator
In-Reply-To: <55B98184B0414ECD9D7B3BA16F5FB9A7@APOLLO>
References: <55B98184B0414ECD9D7B3BA16F5FB9A7@APOLLO>
Message-ID: <89F7D1C8258B46FA93032523015126F1@didierhp>

Dave,

You may want to look at the SG-503 Tektronix plug-in for a levelled sine
generator. It goes to 250 MHz, and the full service manual with schematics
is on my web site in the Manuals pages:

http://www.ko4bb.com/cgi-bin/manuals.pl

I have one and it works as advertised. Great for scope calibration, not so
great as a signal generator :-)

Didier KO4BB 

> -----Original Message-----
> From: time-nuts-bounces at febo.com 
> [mailto:time-nuts-bounces at febo.com] On Behalf Of David C. Partridge
> Sent: Monday, December 15, 2008 4:04 AM
> To: 'Discussion of precise time and frequency measurement'
> Subject: [time-nuts] OT: Levelled sine wave generator
> 
> Sort of related, but only just - however the signal to noise 
> ratio here is so good that I feel impelled to ask.
> 
> For 'scope calibration I'm considering building a levelled 
> sine wave generator.
> 
> Ideally the specs I'm looking for are:
> 
>  o Close to DC (10kHz or 100kHz would be fine) up to at least 1GHz.
>  	more would be better but not critical
> 
>  o Output levels from 0.5Vp-p(-2dBm) to at least 
> 4Vp-p(+16dBm) into 50R
> 	 (up to >6Vp-p(say +20dBm) would be better)
> 
>  o Output flatness levelled within 2% of desired output level 
> (+/- 0.086dB)
> 	across the entire frequency range at the final 
> connector to the DUT
> 	This will almost certainly mean an external levelling head.
> 
>  o Modulation - not critical, FM or AM might be useful.
> 
>  o A logarithmic sweep capability might be nice, but isn't necessary.
> 
>  o Frequency display - nice to have but output to external 
> counter is OK.
> 
> Generating the basic signal is probably just a case of using 
> something like an HP VTO-8200, mixing it with 2GHz 
> (Mini-Circuits RMS30?), low pass filter, an AGC stage (see 
> below) and then amplify probably using an MMIC like the 
> Mini-Circuits ERA-2SM followed by an additional stage to get 
> the extra few
> dB.   For more accurate frequency control some sort of 
> synthesiser locked to
> a reference might be in order (I had to get a time-nuts hook 
> in here somehow).
> 
> The question is what should go in the sensor head?
> 
> Logically I need to sample a proportion of the signal 
> delivered to the output connector, compare the output of the 
> sensor against a DC reference level telling it the desired 
> output level, and feed back a voltage to a
> wideband AGC stage (any suggestions for this?) in the main 
> unit.   I also
> need to be able to detect that output is not levelled.
> 
> Or should I just forget the whole idea and go talk to R&S 
> with a large cheque in hand?
> 
> Cheers
> Dave
> 
> 
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com To unsubscribe, 
> go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
> 



From james.p.lux at jpl.nasa.gov  Mon Dec 15 14:18:49 2008
From: james.p.lux at jpl.nasa.gov (Lux, James P)
Date: Mon, 15 Dec 2008 06:18:49 -0800
Subject: [time-nuts] "24 hour birth celebration period"
In-Reply-To: <W203893088715731229322169@webmail45>
Message-ID: <C56BA749.37F3%James.P.Lux@jpl.nasa.gov>

How close to you want to be.

I always just use the 365.25 year length, so the "time of birth" rotates by 6 hours earlier each year; except in a leap year or the year after, depending on if your birthday is before or after 28 Feb, when it moves 18 hours the other way (back to actual time).  We did do the calculation for my daughter in the car on a long drive with more precision once.. The 0.0022 day/year does add up after all (about 3 min/year offset... So 10 years IS half an hour, and to a 10 year old, this can be important..)


Maybe what you really want is the same sidereal time?


On 12/14/08 10:22 PM, "brice at weaponeer.com" <brice at weaponeer.com> wrote:

Here is a new one, unless I missed a previous post.
Turn 40 tomorrow, no woohoo required.

Tricky part,
Birth certificate 12/15/68 / 01:30 am (no seconds)
Add leap years and seconds, can determine approximate, but no exact time.
Sent to my brother, add 2-3 beers:

-----
I want to do the math when it comes to leap years/seconds to find out to the second when the big 40 rolls over.
(Was born early in the morning), Tomorrow is close enough for family even though my curiosity tells me to determine a more realistic time.
Some would argue that birth is a process has no particular event time and you could never pinpoint anything.
The math becomes pointless when you factor in your sense of time and disruption due to circumstance vs. reality.
I think Mr Einstein Had a midlife crisis himself. Math is pointless without reference.
------

Maybe i'm I barking up the wrong tree, there a possible close to accurate time I can mark, trusting the documentation is correct.
A little different than a rubidium standard. Take out the philosophical stuff.

Cheers, William.
(Hope I have another 40.... or somthing close)

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From james.p.lux at jpl.nasa.gov  Mon Dec 15 14:27:03 2008
From: james.p.lux at jpl.nasa.gov (Lux, James P)
Date: Mon, 15 Dec 2008 06:27:03 -0800
Subject: [time-nuts] OT: Levelled sine wave generator
In-Reply-To: <49464588.905@xtra.co.nz>
Message-ID: <C56BA937.37F6%James.P.Lux@jpl.nasa.gov>


>
>>>>> David C. Partridge wrote:
>>>>>
>>>>>
>>>>>> Sort of related, but only just - however the signal to noise ratio here
>>>>>> is
>>>>>> so good that I feel impelled to ask.
>>>>>>
>>>>>> For 'scope calibration I'm considering building a levelled sine wave
>>>>>> generator.
>>>>>>
>>>>>> Ideally the specs I'm looking for are:
>>>>>>
>>>>>>  o Close to DC (10kHz or 100kHz would be fine) up to at least 1GHz.
>>>>>>     more would be better but not critical
>>>>>>
>>>>>>  o Output levels from 0.5Vp-p(-2dBm) to at least 4Vp-p(+16dBm) into 50R
>>>>>>      (up to >6Vp-p(say +20dBm) would be better)
>>>>>>
>>>>>>  o Output flatness levelled within 2% of desired output level (+/-
>>>>>> 0.086dB)
>>>>>>     across the entire frequency range at the final connector to the DUT
>>>>>>     This will almost certainly mean an external levelling head.
>
>

This is somewhat of a challenge.  Have you considered the issue of the
mismatch? Are you leveling the "forward power" or the "total power" or
something else?

Over the past 10 years, I've been involved in several projects where I was
trying to very accurately measure or generate an RF power, typically with an
uncertainty (2 sigma) of better than 0.05 dB.  It is not easy, particularly
at microwave frequencies.

Not only do you have to stabilize your output, but you need some way to
calibrate it.  Fortunately, you're in a fairly high power application, so a
variety of calorimetric measurement schemes will work, which is nice,
because they tend to be pretty broadband (getting a resistor and mounting
hardware that's flat across a band is a lot easier than a diode...).

You might want to hunt down an IEEE Proceedings from about 30 years ago.. A
special issue on RF measurements or test equipment.

Jim



From david.partridge at dsl.pipex.com  Mon Dec 15 15:09:05 2008
From: david.partridge at dsl.pipex.com (David C. Partridge)
Date: Mon, 15 Dec 2008 15:09:05 -0000
Subject: [time-nuts] OT: Levelled sine wave generator
In-Reply-To: <4946422B.6B7B32A@cox.net>
References: <55B98184B0414ECD9D7B3BA16F5FB9A7@APOLLO>	<49463190.8010708@xtra.co.nz><49463AA6.60407@rubidium.dyndns.org>
	<49464015.3020508@xtra.co.nz> <4946422B.6B7B32A@cox.net>
Message-ID: <4B05C923028F45168E31B308B071339F@APOLLO>

Thanks for the pointer.  I've taken a look at the AD8317.  My main concern
is whether it will operate accurately over the full range of frequency as
the specification suggests a low frequency of 1MHz.

On the accuracy front, the data sheet seems to suggest +/-0.25dB over the
-50dBm to -10dBm range and rather better (probably within my target) at the
-40dBm to -10dBm range.   So I guess a directional coupler IC (are there
such things, and would that be the right part to pick off a sample portion
of the signal over such a large frqeuncy range, or is there a better
solution?) and an attenuator chip would do the job.   For ultimate accuracy
I'd need to keep a table of output correction values against frequency which
would mean adding a microcontroller - which I was rather hoping to avoid.

This looks more do-able with off the shelf parts than I'd expected.

Thanks
Dave
-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of WB6BNQ
Sent: 15 December 2008 11:40
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] OT: Levelled sine wave generator


What about some of the "log" detector made by Analog Devices ?

Bill....WB6BNQ

'



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From david.partridge at dsl.pipex.com  Mon Dec 15 15:18:41 2008
From: david.partridge at dsl.pipex.com (David C. Partridge)
Date: Mon, 15 Dec 2008 15:18:41 -0000
Subject: [time-nuts] OT: Levelled sine wave generator
In-Reply-To: <89F7D1C8258B46FA93032523015126F1@didierhp>
References: <55B98184B0414ECD9D7B3BA16F5FB9A7@APOLLO>
	<89F7D1C8258B46FA93032523015126F1@didierhp>
Message-ID: <3B751890015E4773840A9520182AE841@APOLLO>

Hi Didier,

I was actually considering an SG-504 to get the frequency range at the upper
end.    I has however hoping to better both that and the SG-503 by putting
it all in one for the complete frequency range and ideally having a better
generator as as well.

Conceptually I was hoping to aim for a capbility similar to the Tegam SG5050
(sort of like a "grown-up" version of the SG5030 but with a frequency range
extending up to 2.5GHz (I only need 1GHz though).

D.

-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of Didier
Sent: 15 December 2008 12:29
To: 'Discussion of precise time and frequency measurement'
Subject: Re: [time-nuts] OT: Levelled sine wave generator

Dave,

You may want to look at the SG-503 Tektronix plug-in for a levelled sine
generator. It goes to 250 MHz, and the full service manual with schematics
is on my web site in the Manuals pages:

http://www.ko4bb.com/cgi-bin/manuals.pl

I have one and it works as advertised. Great for scope calibration, not so
great as a signal generator :-)

Didier KO4BB 

> -----Original Message-----
> From: time-nuts-bounces at febo.com
> [mailto:time-nuts-bounces at febo.com] On Behalf Of David C. Partridge
> Sent: Monday, December 15, 2008 4:04 AM
> To: 'Discussion of precise time and frequency measurement'
> Subject: [time-nuts] OT: Levelled sine wave generator
> 
> Sort of related, but only just - however the signal to noise ratio 
> here is so good that I feel impelled to ask.
> 
> For 'scope calibration I'm considering building a levelled sine wave 
> generator.
> 
> Ideally the specs I'm looking for are:
> 
>  o Close to DC (10kHz or 100kHz would be fine) up to at least 1GHz.
>  	more would be better but not critical
> 
>  o Output levels from 0.5Vp-p(-2dBm) to at least
> 4Vp-p(+16dBm) into 50R
> 	 (up to >6Vp-p(say +20dBm) would be better)
> 
>  o Output flatness levelled within 2% of desired output level
> (+/- 0.086dB)
> 	across the entire frequency range at the final connector to the DUT
> 	This will almost certainly mean an external levelling head.
> 
>  o Modulation - not critical, FM or AM might be useful.
> 
>  o A logarithmic sweep capability might be nice, but isn't necessary.
> 
>  o Frequency display - nice to have but output to external counter is 
> OK.
> 
> Generating the basic signal is probably just a case of using something 
> like an HP VTO-8200, mixing it with 2GHz (Mini-Circuits RMS30?), low 
> pass filter, an AGC stage (see
> below) and then amplify probably using an MMIC like the Mini-Circuits 
> ERA-2SM followed by an additional stage to get the extra few
> dB.   For more accurate frequency control some sort of 
> synthesiser locked to
> a reference might be in order (I had to get a time-nuts hook in here 
> somehow).
> 
> The question is what should go in the sensor head?
> 
> Logically I need to sample a proportion of the signal delivered to the 
> output connector, compare the output of the sensor against a DC 
> reference level telling it the desired output level, and feed back a 
> voltage to a wideband AGC stage (any suggestions for this?) in the 
> main
> unit.   I also
> need to be able to detect that output is not levelled.
> 
> Or should I just forget the whole idea and go talk to R&S with a large 
> cheque in hand?
> 
> Cheers
> Dave
> 
> 
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com To unsubscribe, go to 
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
> 


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From gwinn at raytheon.com  Mon Dec 15 15:25:18 2008
From: gwinn at raytheon.com (Joseph M Gwinn)
Date: Mon, 15 Dec 2008 10:25:18 -0500
Subject: [time-nuts] Sub Pico Second Phase logger
In-Reply-To: <4941C02F.8060009@xtra.co.nz>
Message-ID: <OF90F71418.3B51DF3E-ON85257520.0054A02D-85257520.0054A708@mck.us.ray.com>

Bruce,


time-nuts-bounces at febo.com wrote on 12/11/2008 08:36:47 PM:

> Joe
> 
> Attached is noise spectrum (1kHz and below) of AP192 with nothing
> connected to inputs.
> Sampling rate 96KSPS.
> Frequency bin equivalent noise bandwidth ~ 3Hz.
> Noise has similar spectrum to flicker noise with a noise corner of
> around 300Hz or so.

The noise floor ain't so bad, -130 dB (dBm? dbV?) at maybe 10 Hz, even if 
it's 20 dB worse than at 1 KHz.

Has anyone measured the Allan Deviation?

Joe


From gwinn at raytheon.com  Mon Dec 15 16:16:29 2008
From: gwinn at raytheon.com (Joseph M Gwinn)
Date: Mon, 15 Dec 2008 11:16:29 -0500
Subject: [time-nuts] Sub Pico Second Phase logger
In-Reply-To: <4941B3D1.9030102@xtra.co.nz>
Message-ID: <OF6D4BA695.2556A502-ON85257520.0056DA8F-85257520.005956F1@mck.us.ray.com>

Bruce,


time-nuts-bounces at febo.com wrote on 12/11/2008 07:44:01 PM:

> Joe
> 
> Isolation from mixer RF to LO port may be too low when the mixer input
> frequencies are different.
> Injection locking can then occur all too easily (just ask Ulrich about
> this) when the mixer RF ports are driven by 2 separate OCXOs.
> 
> Detailed in line post follows:
> 
> Bruce
> 
> Joseph M Gwinn wrote:
> > Bruce,
> >
> >
> > time-nuts-bounces at febo.com wrote on 12/10/2008 08:38:13 PM:
> >
> > 
> >> Joe
> >> Joseph M Gwinn wrote:
> >> 
> >>> Bruce,
> >>>
> >>>
> >>> 
> >>>> Reflecting the sum frequency back into the mixer is actually 
necessary
> >>>> to reduce the noise at the IF port.
> >>>> I believe that one of Agilent's simulation application notes 
mentions
> >>>> this effect but I don't recall the actual application note number.
> >>>> This will affect the mixer RF and IF port impedance so adding a 
> >>>> series resistor may be required to improve the SWR.
> >>>>
> >>>> 
> >>> How big an effect is this?  Is the absolute noise decreased, or does 

> >>> it remain the same while the signal increase?
> >>>
> >>>
> >>> 
> >> With the same difference frequency IF port termination impedance, 
noise
> >> is actually decreased along with the mixer conversion loss.
> >> 
> >
> > OK.  Complicated beasts, those mixers.  Do you know of a paper (or 
book) 
> > on the subject?
> >
> > 
> 
> 
> Not offhand, but this crops up in lots of places usually when one least
> expects it..

I've noticed.  Someone has to have poured his soul into a monograph.


> >> However if the sound card input noise dominates, reducing the mixer
> >> effective output noise won't help.
> >> 
> >
> > Yes.  In the plots you posted in a different email, there was a big 
rise 
> > below 1 KHz (scan stopped at 1 KHz, so don't know the shape).  Why is 
> > this?
> >
> I'll expand the frequency scale and take another snapshot for the region
> below 1kHz.
> This rise may be due to ADC and/or input differential amplifier flicker
> noise.

Saw it.  Thanks.  Does look like flicker noise.  Although it wasn't large 
enough to be a real problem it seems.

 

> > 
> >> If one is time stamping the zero crossings an increased zero-crossing 

> >> slope is an advantage. 
> >> For relative phase measurements a trapezoidal beat frequencywaveform 
> >> may be less useful.
> >
> > Fitting to the approximate waveshape, sine or trapezoidal, 
> > should yield a very robust estimate, due to the large data support, 
and zero-crossing 
> > slope won't much matter.  Hmm.  Actually, if the slopes of the 
trapezoid 
> > are too steep, we may not have all that many slope samples.
> >
> >
> > 
> 
> If one believes the NIST papers the trapezoid zero crossing slope only
> increases by a factor of 3.
> If one uses a cascaded filter limiter the slope gain can be adjusted for
> optimum results.

The implication would be to not sharpen things up too well in before 
digitizing.


> > [snip]
> > 
> >> Of course with a capacitive IF port termination, matching the RF and 
LO
> >> ports becomes more critical as does the reverse isolation of the 
various
> >> amplifiers driving the RF and LO ports.
> >> It may be simpler in fact to use a level 17 mixer with high LO to RF 
and
> >> LO to IF isolation with the RF port unsaturated as it relaxes the
> >> reverse isolation specs for the isolation amplifiers.
> >> 
> >
> > Another tradeoff.  I'll have to think about it.
> >
> > I'm thinking of 6 db and 10 db attenuators on the LO and RF ports 
> > respectively, but no isolation amplifier.
> 
> You may get away with that if you use mixers with very high RF to LO
> port isolation.
> Minicircuits have at least 3 level 17 mixer models that typically have
> 80dB LO to RF isolation at 10MHz.

I've used the ZRPD-1, which claims about 75 dB isolation at 10 MHz.

 
> Using a passive splitter for the LO drives will gain at least another
> 30dB in isolation between the 2 RF inputs if you use an appropriate
> splitter.

True. 

I may have lost the thread here.  If we have one oscillator driving 
everything, one cannot have injection locking even if isolation isn't 
perfect.  What isolation does gain us is a reduction in undesired phase 
shifta.


 
> > [snip]
> > 
> >>> 
> >> The only configuration for which it makes any sense is an inverting
> >> input amplifier with a finite input voltage offset.
> >> 
> >
> > Why would non-inverting not work?  Both inputs source or sink bias 
> > currents, and non-inverting presents a very high impedance.
> 
> Non inverting amplifiers usually have lower noise and generally work 
very well.
> I was only trying to come up with a preamp circuit for which the
> comments in the Minicircuits application note on the effect of amplifier
> input offset voltage made any sense.

Ah.  It may be hopeless.

My reading was that they were worried about bias currents from the amp 
flowing into the mixer and causing offsets, not amplifier offset voltages 
per se.  The amplifier offset voltage does not cause a mixer offset, and 
may be reduced by use of a chopper amp or very good balance.


> The only risk with a noninverting amplifier, is that under fault
> conditions (missing supply) a very large current can flow back (with
> some low noise opamps as Enrico has experienced) into the mixers and
> destroy them.

Yes, I recall the discussion on your website.

 
> For this particular application the mixer preamp gain need only be
> sufficient to boost the mixer phase detector output (1V pk?, 350mV pk??
> depends on mixer and its operating conditions) to the sound card input
> (FSR ~ 5.6V pk for an AP192). The resultant preamp gain is relatively
> low ( 5 - 15X depending on the mixer etc) and the sound card noise will
> dominate (~ 100nV/rtHz midband for an AP192) thus using an ultra low
> noise mixer preamp isn't necessary.

Yes.



> > We are converging on a soundcard wishlist:
> >
> > 1.  True balanced inputs on XLR connectors.  And good ground design, 
so we 
> > aren't bedeviled by ground loops.
> >
> > 2.  24-bit ADCs, and similar DACs.
> >
> > 3.  Very good isolation all around. 
> >
> > 4.  Digital access via firewire (or USB3 I suppose), with the 
soundcard in 
> > its own box.
> >
> > 5.  High-level input direct to the ADCs.
> >
> >
> > While use of AKM ICs may be a very good idea, it is not a requirement 
per 
> > se.
> >
> > [snip]
> > 
> 
> 
> Optical isolation of the ADC from the noisy digital interface to the PC
> would also be nice.

Good point.  Part of ground design I suppose.   Although with noise floor 
of -150 dB down there cannot be so much leakage.

 
> If we design our own PCB then the AD7760 series ADCs are another
> possible option.
> These have a built in differential input differential output amplifier.

Yes.  But aren't we trying to use commonly available soundcards?

 
> 
> >>>> Can alleviate [oddities at end of phase range} to some extent by 
> >>>> driving a pair of such phase detectors so that their outputs are in 

> >>>> quadrature.
> > 
> >>>> One just selects the phase detector output that is in the linear 
> >>>> range.
> > 
> >>>> The quadrature outputs also allow unambiguous assignment of the 
sign 
> >>>> of any phase change.
> >>>>
> >>>> 
> >>> The Symmetricom 5120A does something very clever to alleviate this 
> >>> problem.  Explained in US patent 7,227,346 and "Direct-Digital 
> >>> Phase-Noise Measurement"; J. Grove, J. Hein, J. Retta, P. Schweiger, 
W.Solbrig, 
> >>> and S.R. Stein; 2004 IEEE International Ultrasonics, Ferroelectrics, 
and 
> >>> Frequency Control Joint 50th Anniversary Conference, pages 287-291.
> >>>
> >>> Joe
> >>>
> >>>
> >>> 
> >> I've read the patent.
> >> 
> >
> > The paper is also worthwhile, and available on the web somewhere 
(don't 
> > recall where, but google found the pdf).  I had to read the patent 
> > multiple times to figure out what's going on.  The correlation 
approach is 
> > old as the hills, and only the digital phase detector was patentable.
> >
> 
> It may be feasible to achieve the same effect by purely digital means at
> least for low sample rates where FIR filters with tens of thousands of
> taps are feasible.

It *is* feasible, and Sam Stein is doing it.  I've perhaps lost the thread 
here.


> Of course 64 bit or higher precision arithmetic is then mandatory to
> avoid excessive calculation roundoff noise.

It may be 64 bit *integer*, actually.

My understanding is that the 5120A is built upon a DSP or more likely FPGA 
(of unspecified make and model).  The 5125A will have a top frequency of 
400 MHz, so the DSP and/or FPGA better be damn fast.  Little analog stuff 
remains.

Joe


From holrum at hotmail.com  Mon Dec 15 16:45:21 2008
From: holrum at hotmail.com (Mark Sims)
Date: Mon, 15 Dec 2008 16:45:21 +0000
Subject: [time-nuts] OT: Levelled sine wave generator
In-Reply-To: <mailman.382.1229354326.2499.time-nuts@febo.com>
References: <mailman.382.1229354326.2499.time-nuts@febo.com>
Message-ID: <BLU125-W345F2C17E6C935FDA781BCEF40@phx.gbl>


I have both the SG503 and SG504.  You can get SG503's for cheap on Ebay.  Also SG504's... if they don't have the leveling head.  The SG504 head uses a custom ceramic hybrid detector (dual diode?) in the head (rough schematic in the SG504 manual available for download on BAMA).  How about settling for a dual module approach?  Use the SG503 and design a detector head for the SG504 (the world will acknowledge you greatness far and wide and buy you tasty cookies).  I have tried to build a leveling head with mixed (OK, piss poor) results but lost my motivation when I stumbled upon a couple of heads that were in a "tool box" plugin in a mainframe that I bought.
_________________________________________________________________
Send e-mail faster without improving your typing skills.
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From wa1zms at att.net  Mon Dec 15 16:53:43 2008
From: wa1zms at att.net (wa1zms at att.net)
Date: Mon, 15 Dec 2008 16:53:43 +0000
Subject: [time-nuts] Close-in phase noise question...
In-Reply-To: <OF6D4BA695.2556A502-ON85257520.0056DA8F-85257520.005956F1@mck.us.ray.com>
References: <4941B3D1.9030102@xtra.co.nz>
	<OF6D4BA695.2556A502-ON85257520.0056DA8F-85257520.005956F1@mck.us.ray.com>
Message-ID: <121520081653.29002.49468B97000A67F50000714A22243429029B0A02D29B9B0EBF9C0396CE0E99@att.net>

Looking for comment here...

The background:
I'm working on a sub mm-wave LO chain for
a ham radio application. While chasing issues
of close-in phase (ie: within 1KHz of RF
carrier) by peeling the "layers of the onion",
I'm starting to question the performance of
the MMICs that are used as buffers and amps
following my Wenzel reference OCXOs.

Question(s):
Should any MMIC be allowed to be driven
close to compression or into compression
when striving for best close-in noise?

I know and have seen the NF of a MMIC
degrade while in compression, but my
target right now is close-in noise rather
than broadband noise.

My design, in summary, takes 5MHz up to 630GHz
via several multipliers and PLL stages.

-Brian






From stanw1le at verizon.net  Mon Dec 15 17:19:19 2008
From: stanw1le at verizon.net (Stan W1LE)
Date: Mon, 15 Dec 2008 12:19:19 -0500
Subject: [time-nuts] Close-in phase noise question...
In-Reply-To: <121520081653.29002.49468B97000A67F50000714A22243429029B0A02D29B9B0EBF9C0396CE0E99@att.net>
References: <4941B3D1.9030102@xtra.co.nz>
	<OF6D4BA695.2556A502-ON85257520.0056DA8F-85257520.005956F1@mck.us.ray.com>
	<121520081653.29002.49468B97000A67F50000714A22243429029B0A02D29B9B0EBF9C0396CE0E99@att.net>
Message-ID: <49469197.50604@verizon.net>

Hello Brian,

I hope you and yours have the very best of this Holiday Season.

My considerations would be similar to spurious free dynamic range,
keeping all discrete intermodulation products very low, which
would in turn keep the intermodulation noise very low.

When you drive an amp towards and into saturation, to get harmonics 
generated,
 the broadband noise floor will be raised with intermodulation noise.

Most of the time this intermodulation noise is not a limiting factor,
until very high harmonic multiples are needed.

Stan, W1LE   FN41sr    Cape Cod


wa1zms at att.net wrote:
> Looking for comment here...
>
> The background:
> I'm working on a sub mm-wave LO chain for
> a ham radio application. While chasing issues
> of close-in phase (ie: within 1KHz of RF
> carrier) by peeling the "layers of the onion",
> I'm starting to question the performance of
> the MMICs that are used as buffers and amps
> following my Wenzel reference OCXOs.
>
> Question(s):
> Should any MMIC be allowed to be driven
> close to compression or into compression
> when striving for best close-in noise?
>
> I know and have seen the NF of a MMIC
> degrade while in compression, but my
> target right now is close-in noise rather
> than broadband noise.
>
> My design, in summary, takes 5MHz up to 630GHz
> via several multipliers and PLL stages.
>
> -Brian
>
>
>
>
>
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>
>   



From brice at weaponeer.com  Mon Dec 15 18:21:06 2008
From: brice at weaponeer.com (brice at weaponeer.com)
Date: Mon, 15 Dec 2008 18:21:06 +0000
Subject: [time-nuts] Birthday silliness......
Message-ID: <W626511224417611229365266@webmail30>

Thanks John,

First Rule - Stay off the internet when it is a eventful birthday and you have had a couple of beers.

Your answer is what I was after after. 

I looked at the numbers again last night, could not get there.
I remember when I was a kid, I tried to figure out if my birthday should be on a different day or time,
 and attempting to resolve the basics that so it made some knd of sence why it was not.
In longer periods we compensate because the earth Sun etc does not always cooperate with perfect timekeeping. 
(like we have a choice) and in the 365 day system, we make up for flaws on certain days and times.
Then add different different calenders to the list, I started thinking, what time is it anyway?

40 is really not that bad, but the day is not over yet.... 
Cheers!

William Rice



From had at to-way.com  Mon Dec 15 18:43:17 2008
From: had at to-way.com (Had)
Date: Mon, 15 Dec 2008 10:43:17 -0800
Subject: [time-nuts] PTS160 GPIB
Message-ID: <20081215184321.AF9B51EE83C@mail-in02.adhost.com>


Happy Holidays to "Nuts" of all types,

Looking for a copy of the GPIB section of a PTS Synthesizer manual, 
preferably a 160, if it makes a difference. My manual only has the 
standard PTS remote information.

Thanks,
Had, K7MLR

From jmiles at pop.net  Mon Dec 15 19:14:53 2008
From: jmiles at pop.net (John Miles)
Date: Mon, 15 Dec 2008 11:14:53 -0800
Subject: [time-nuts] Close-in phase noise question...
In-Reply-To: <121520081653.29002.49468B97000A67F50000714A22243429029B0A02D29B9B0EBF9C0396CE0E99@att.net>
Message-ID: <PKEGJHPHLLBACEOICCBJEECIPNAB.jmiles@pop.net>

The painful part is probably the first few stages, if you are starting at 5
MHz.  You probably want to do some HP 8662A-like tricks using crystal
filters to shave off the broadband noise below 1 GHz, and maybe SAW filters
above that.  This will do nothing for noise within 1 kHz, though... do you
really need a clean signal that close to the carrier all the way up to 630
GHz?

The noise characteristics of the MMICs seems to depend a lot on the fab
technology.  I can't seem to find my .PDF copy of it right now, but I have
one paper on microwave regenerative dividers where the authors measured the
residual PN of several contemporary parts driven to saturation.  At 4.5 GHz,
the 10 dB/decade corner frequency wasn't reached until past 100 kHz for the
Stanford Microdevices SGA-4186, which didn't speak well for the PN
performance of SiGe HBT parts.  They showed -143 dBc/Hz at 1 kHz for that
one.

The GaAs HBT part (Mini-Circuits ERA-5SM) they tested was among the best
(-156 dBc/Hz at 1 kHz).  Second-worst was an InGaP/GaAs HBT part (Stanford
NGA-489) at about -153 dBc/Hz at 1 kHz.  Still much better than the SiGe
part.

My understanding is that the newer GALI-series parts from Mini-Circuits are
InGaP HBT devices so they'd presumably perform about like the NGA-489.
You'd want to measure them to make sure, though, if your app is that
critical.

Take a look at NRAO's recent publications, especially those associated with
the ALMA array (many of which are on their site).  They're doing the real
bleeding-edge work at sub-mm these days.

-- john, KE5FX

> -----Original Message-----
> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com]On
> Behalf Of wa1zms at att.net
> Sent: Monday, December 15, 2008 8:54 AM
> To: time-nuts at febo.com
> Subject: [time-nuts] Close-in phase noise question...
>
>
> Looking for comment here...
>
> The background:
> I'm working on a sub mm-wave LO chain for
> a ham radio application. While chasing issues
> of close-in phase (ie: within 1KHz of RF
> carrier) by peeling the "layers of the onion",
> I'm starting to question the performance of
> the MMICs that are used as buffers and amps
> following my Wenzel reference OCXOs.
>
> Question(s):
> Should any MMIC be allowed to be driven
> close to compression or into compression
> when striving for best close-in noise?
>
> I know and have seen the NF of a MMIC
> degrade while in compression, but my
> target right now is close-in noise rather
> than broadband noise.
>
> My design, in summary, takes 5MHz up to 630GHz
> via several multipliers and PLL stages.
>
> -Brian
>

>



From didier at cox.net  Mon Dec 15 19:39:52 2008
From: didier at cox.net (Didier Juges)
Date: Mon, 15 Dec 2008 13:39:52 -0600
Subject: [time-nuts] OT: Levelled sine wave generator
In-Reply-To: <3B751890015E4773840A9520182AE841@APOLLO>
Message-ID: <6096f860-967b-40c3-a3ec-6cc4fb7ffa0d@fis-hts-01.cranecoelectronics.com>

Dave,

How about using a true signal generator?
I have not checked the spec for my HP 8657B (it's flat enough for what I
do), but it will do all that you are asking for, and being a true
synthesizer, it can be used for much more than just calibrate scopes. 

If flatness is not good enough, that could be addressed with an external
head, but all the signal generation and level control input is already
there.

Didier

-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of David C. Partridge
Sent: Monday, December 15, 2008 9:19 AM
To: 'Discussion of precise time and frequency measurement'
Subject: Re: [time-nuts] OT: Levelled sine wave generator

Hi Didier,

I was actually considering an SG-504 to get the frequency range at the upper
end.    I has however hoping to better both that and the SG-503 by putting
it all in one for the complete frequency range and ideally having a better
generator as as well.

Conceptually I was hoping to aim for a capbility similar to the Tegam SG5050
(sort of like a "grown-up" version of the SG5030 but with a frequency range
extending up to 2.5GHz (I only need 1GHz though).

D.

-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of Didier
Sent: 15 December 2008 12:29
To: 'Discussion of precise time and frequency measurement'
Subject: Re: [time-nuts] OT: Levelled sine wave generator

Dave,

You may want to look at the SG-503 Tektronix plug-in for a levelled sine
generator. It goes to 250 MHz, and the full service manual with schematics
is on my web site in the Manuals pages:

http://www.ko4bb.com/cgi-bin/manuals.pl

I have one and it works as advertised. Great for scope calibration, not so
great as a signal generator :-)

Didier KO4BB 

> -----Original Message-----
> From: time-nuts-bounces at febo.com
> [mailto:time-nuts-bounces at febo.com] On Behalf Of David C. Partridge
> Sent: Monday, December 15, 2008 4:04 AM
> To: 'Discussion of precise time and frequency measurement'
> Subject: [time-nuts] OT: Levelled sine wave generator
> 
> Sort of related, but only just - however the signal to noise ratio 
> here is so good that I feel impelled to ask.
> 
> For 'scope calibration I'm considering building a levelled sine wave 
> generator.
> 
> Ideally the specs I'm looking for are:
> 
>  o Close to DC (10kHz or 100kHz would be fine) up to at least 1GHz.
>  	more would be better but not critical
> 
>  o Output levels from 0.5Vp-p(-2dBm) to at least
> 4Vp-p(+16dBm) into 50R
> 	 (up to >6Vp-p(say +20dBm) would be better)
> 
>  o Output flatness levelled within 2% of desired output level
> (+/- 0.086dB)
> 	across the entire frequency range at the final connector to the DUT
> 	This will almost certainly mean an external levelling head.
> 
>  o Modulation - not critical, FM or AM might be useful.
> 
>  o A logarithmic sweep capability might be nice, but isn't necessary.
> 
>  o Frequency display - nice to have but output to external counter is 
> OK.
> 
> Generating the basic signal is probably just a case of using something 
> like an HP VTO-8200, mixing it with 2GHz (Mini-Circuits RMS30?), low 
> pass filter, an AGC stage (see
> below) and then amplify probably using an MMIC like the Mini-Circuits 
> ERA-2SM followed by an additional stage to get the extra few
> dB.   For more accurate frequency control some sort of 
> synthesiser locked to
> a reference might be in order (I had to get a time-nuts hook in here 
> somehow).
> 
> The question is what should go in the sensor head?
> 
> Logically I need to sample a proportion of the signal delivered to the 
> output connector, compare the output of the sensor against a DC 
> reference level telling it the desired output level, and feed back a 
> voltage to a wideband AGC stage (any suggestions for this?) in the 
> main
> unit.   I also
> need to be able to detect that output is not levelled.
> 
> Or should I just forget the whole idea and go talk to R&S with a large 
> cheque in hand?
> 
> Cheers
> Dave
> 
> 
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com To unsubscribe, go to 
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
> 


_______________________________________________
time-nuts mailing list -- time-nuts at febo.com To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.


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and follow the instructions there.




From david.partridge at dsl.pipex.com  Mon Dec 15 19:52:52 2008
From: david.partridge at dsl.pipex.com (David C. Partridge)
Date: Mon, 15 Dec 2008 19:52:52 -0000
Subject: [time-nuts] OT: Levelled sine wave generator
In-Reply-To: <6096f860-967b-40c3-a3ec-6cc4fb7ffa0d@fis-hts-01.cranecoelectronics.com>
References: <3B751890015E4773840A9520182AE841@APOLLO>
	<6096f860-967b-40c3-a3ec-6cc4fb7ffa0d@fis-hts-01.cranecoelectronics.com>
Message-ID: <1BE8D75ACB744DDCA282353BFD90CABD@APOLLO>

If I could find a suitable sig-gen with the amplitude range, frequency range
and the external levelling capability I'd probably go there (subject to
cost).  I've looked at the 8657A and B before, but as I didn't see anything
in the specification sheet about being able to use an external passthrough
head, so I passed on it. 

I suspect I might be able to build what I need for only a couple hundred
pounds using care in sourcing parts.

Dave



From jltran at worldnet.att.net  Mon Dec 15 19:56:07 2008
From: jltran at worldnet.att.net (J. L. Trantham, M. D.)
Date: Mon, 15 Dec 2008 13:56:07 -0600
Subject: [time-nuts] Close-in phase noise question...
In-Reply-To: <PKEGJHPHLLBACEOICCBJEECIPNAB.jmiles@pop.net>
Message-ID: <HDEFLGKACIEOIBFFBEHPKEJCCFAA.jltran@worldnet.att.net>

I really enjoy reading the mail on this group, but I thought it was the
'front molecule on the cutting edge'.

Joe

-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com]On
Behalf Of John Miles
Sent: Monday, December 15, 2008 1:15 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Close-in phase noise question...

The painful part is probably the first few stages, if you are starting at 5
MHz.  You probably want to do some HP 8662A-like tricks using crystal
filters to shave off the broadband noise below 1 GHz, and maybe SAW filters
above that.  This will do nothing for noise within 1 kHz, though... do you
really need a clean signal that close to the carrier all the way up to 630
GHz?

The noise characteristics of the MMICs seems to depend a lot on the fab
technology.  I can't seem to find my .PDF copy of it right now, but I have
one paper on microwave regenerative dividers where the authors measured the
residual PN of several contemporary parts driven to saturation.  At 4.5 GHz,
the 10 dB/decade corner frequency wasn't reached until past 100 kHz for the
Stanford Microdevices SGA-4186, which didn't speak well for the PN
performance of SiGe HBT parts.  They showed -143 dBc/Hz at 1 kHz for that
one.

The GaAs HBT part (Mini-Circuits ERA-5SM) they tested was among the best
(-156 dBc/Hz at 1 kHz).  Second-worst was an InGaP/GaAs HBT part (Stanford
NGA-489) at about -153 dBc/Hz at 1 kHz.  Still much better than the SiGe
part.

My understanding is that the newer GALI-series parts from Mini-Circuits are
InGaP HBT devices so they'd presumably perform about like the NGA-489.
You'd want to measure them to make sure, though, if your app is that
critical.

Take a look at NRAO's recent publications, especially those associated with
the ALMA array (many of which are on their site).  They're doing the real
bleeding-edge work at sub-mm these days.

-- john, KE5FX

> -----Original Message-----
> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com]On
> Behalf Of wa1zms at att.net
> Sent: Monday, December 15, 2008 8:54 AM
> To: time-nuts at febo.com
> Subject: [time-nuts] Close-in phase noise question...
>
>
> Looking for comment here...
>
> The background:
> I'm working on a sub mm-wave LO chain for
> a ham radio application. While chasing issues
> of close-in phase (ie: within 1KHz of RF
> carrier) by peeling the "layers of the onion",
> I'm starting to question the performance of
> the MMICs that are used as buffers and amps
> following my Wenzel reference OCXOs.
>
> Question(s):
> Should any MMIC be allowed to be driven
> close to compression or into compression
> when striving for best close-in noise?
>
> I know and have seen the NF of a MMIC
> degrade while in compression, but my
> target right now is close-in noise rather
> than broadband noise.
>
> My design, in summary, takes 5MHz up to 630GHz
> via several multipliers and PLL stages.
>
> -Brian
>

>


_______________________________________________
time-nuts mailing list -- time-nuts at febo.com
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.



From wa1zms at att.net  Mon Dec 15 19:58:23 2008
From: wa1zms at att.net (wa1zms at att.net)
Date: Mon, 15 Dec 2008 19:58:23 +0000
Subject: [time-nuts] Close-in phase noise question...
In-Reply-To: <PKEGJHPHLLBACEOICCBJEECIPNAB.jmiles@pop.net>
References: <121520081653.29002.49468B97000A67F50000714A22243429029B0A02D29B9B0EBF9C0396CE0E99@att.net>
	<PKEGJHPHLLBACEOICCBJEECIPNAB.jmiles@pop.net>
Message-ID: <121520081958.23843.4946B6DF0001943700005D2322230680329B0A02D29B9B0EBF9C0396CE0E99@att.net>

John-

I do agree with you. The pain is in the early stages of the
LO chain.  Since I'm planning to use QRSS CW (that's very
slow speed Morse Code with very narrow demod bandwidths for
non-hams on this reflector who may not be familiar with QRSS),
the noise very close to the carrier become key.

A noisy carrier can't be detected very well on a waterfall
display if it too, looks like noise.

I have a several MSA-1105 MMICs in the chain to provide
isolation and give gain while multiplying the 5MHz signal
to 10MHz and then to 20MHz. The 20MHz acts as a reference
for a 1320MHz PLL. The 1320MHz then is multiplied several
more times on it's way to a sun-harmonic mixer for 630GHz.

I am wondering if the MSA-1105s could be causing more
close-in noise than I expected. The CW note sounds a
bit "rough" by ear.

The final 600GHz mixer that I'm using comes from some of
the mm-wave boys that work with NRAO.

But my LO noise requirements are a bit different than their
needs.


 

 

 -------------- Original message from "John Miles" <jmiles at pop.net>: --------------


> The painful part is probably the first few stages, if you are starting at 5
> MHz.  You probably want to do some HP 8662A-like tricks using crystal
> filters to shave off the broadband noise below 1 GHz, and maybe SAW filters
> above that.  This will do nothing for noise within 1 kHz, though... do you
> really need a clean signal that close to the carrier all the way up to 630
> GHz?
> 
> The noise characteristics of the MMICs seems to depend a lot on the fab
> technology.  I can't seem to find my .PDF copy of it right now, but I have
> one paper on microwave regenerative dividers where the authors measured the
> residual PN of several contemporary parts driven to saturation.  At 4.5 GHz,
> the 10 dB/decade corner frequency wasn't reached until past 100 kHz for the
> Stanford Microdevices SGA-4186, which didn't speak well for the PN
> performance of SiGe HBT parts.  They showed -143 dBc/Hz at 1 kHz for that
> one.
> 
> The GaAs HBT part (Mini-Circuits ERA-5SM) they tested was among the best
> (-156 dBc/Hz at 1 kHz).  Second-worst was an InGaP/GaAs HBT part (Stanford
> NGA-489) at about -153 dBc/Hz at 1 kHz.  Still much better than the SiGe
> part.
> 
> My understanding is that the newer GALI-series parts from Mini-Circuits are
> InGaP HBT devices so they'd presumably perform about like the NGA-489.
> You'd want to measure them to make sure, though, if your app is that
> critical.
> 
> Take a look at NRAO's recent publications, especially those associated with
> the ALMA array (many of which are on their site).  They're doing the real
> bleeding-edge work at sub-mm these days.
> 
> -- john, KE5FX
> 
> > -----Original Message-----
> > From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com]On
> > Behalf Of wa1zms at att.net
> > Sent: Monday, December 15, 2008 8:54 AM
> > To: time-nuts at febo.com
> > Subject: [time-nuts] Close-in phase noise question...
> >
> >
> > Looking for comment here...
> >
> > The background:
> > I'm working on a sub mm-wave LO chain for
> > a ham radio application. While chasing issues
> > of close-in phase (ie: within 1KHz of RF
> > carrier) by peeling the "layers of the onion",
> > I'm starting to question the performance of
> > the MMICs that are used as buffers and amps
> > following my Wenzel reference OCXOs.
> >
> > Question(s):
> > Should any MMIC be allowed to be driven
> > close to compression or into compression
> > when striving for best close-in noise?
> >
> > I know and have seen the NF of a MMIC
> > degrade while in compression, but my
> > target right now is close-in noise rather
> > than broadband noise.
> >
> > My design, in summary, takes 5MHz up to 630GHz
> > via several multipliers and PLL stages.
> >
> > -Brian
> >
> 
> >
> 
> 
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.







From wa1zms at att.net  Mon Dec 15 20:10:55 2008
From: wa1zms at att.net (wa1zms at att.net)
Date: Mon, 15 Dec 2008 20:10:55 +0000
Subject: [time-nuts] Close-in phase noise question...
In-Reply-To: <HDEFLGKACIEOIBFFBEHPKEJCCFAA.jltran@worldnet.att.net>
References: <PKEGJHPHLLBACEOICCBJEECIPNAB.jmiles@pop.net>
	<HDEFLGKACIEOIBFFBEHPKEJCCFAA.jltran@worldnet.att.net>
Message-ID: <121520082010.6932.4946B9CF00018FF500001B1422230680329B0A02D29B9B0EBF9C0396CE0E99@att.net>

I would assume that the bleeding takes place
just after the first molecule has performed it's
dissecting task.
 

  -------------- Original message from "J. L. Trantham, M. D." <jltran at worldnet.att.net>: --------------


> I really enjoy reading the mail on this group, but I thought it was the
> 'front molecule on the cutting edge'.
> 
> Joe



From GandalfG8 at aol.com  Mon Dec 15 21:04:09 2008
From: GandalfG8 at aol.com (GandalfG8 at aol.com)
Date: Mon, 15 Dec 2008 16:04:09 EST
Subject: [time-nuts] PTS160 GPIB
Message-ID: <c1a.4b920752.36782049@aol.com>

 
In a message dated 15/12/2008 18:44:04 GMT Standard Time, had at to-way.com  
writes:

Looking  for a copy of the GPIB section of a PTS Synthesizer manual, 
preferably a  160, if it makes a difference. My manual only has the 
standard PTS remote  information.



----------------
Hi Had
 
If you check out the PTS manuals I uploaded to Didier's site I'm sure one  of 
those has the GPIB section, if not let me know and I should be able to scan  
it from one of my other manuals.
 
My original PTS160 manual doesn't include the GPIB section but I'm pretty  
sure thay'll all be similar.
The Manuals or PTS catalogue should give the option numbers in each  case for 
comparison anyway.
 
Regards
 
Nigel
GM8PZR

From bruce.griffiths at xtra.co.nz  Mon Dec 15 21:34:34 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Tue, 16 Dec 2008 10:34:34 +1300
Subject: [time-nuts] Sub Pico Second Phase logger
In-Reply-To: <OF90F71418.3B51DF3E-ON85257520.0054A02D-85257520.0054A708@mck.us.ray.com>
References: <OF90F71418.3B51DF3E-ON85257520.0054A02D-85257520.0054A708@mck.us.ray.com>
Message-ID: <4946CD6A.7070003@xtra.co.nz>

Joseph M Gwinn wrote:
> Bruce,
>
>
> time-nuts-bounces at febo.com wrote on 12/11/2008 08:36:47 PM:
>
>   
>> Joe
>>
>> Attached is noise spectrum (1kHz and below) of AP192 with nothing
>> connected to inputs.
>> Sampling rate 96KSPS.
>> Frequency bin equivalent noise bandwidth ~ 3Hz.
>> Noise has similar spectrum to flicker noise with a noise corner of
>> around 300Hz or so.
>>     
>
> The noise floor ain't so bad, -130 dB (dBm? dbV?) at maybe 10 Hz, even if 
> it's 20 dB worse than at 1 KHz.
>
> Has anyone measured the Allan Deviation?
>
> Joe
>
>
>   
Joe

Noise plot is with respect to full scale (4Vrms).
I need to build a noise source to check the absolute level.
Will use the amplified Johnson noise of a 150K resistor.

By Allan deviation do you mean calculate it from the sequential 96KSPS
ADC output samples?

I can do this, but since the dominant noise source is white the Allan
deviation will scale with the measurement bandwidth.

Bruce



From GandalfG8 at aol.com  Mon Dec 15 21:35:55 2008
From: GandalfG8 at aol.com (GandalfG8 at aol.com)
Date: Mon, 15 Dec 2008 16:35:55 EST
Subject: [time-nuts] PTS160 GPIB
Message-ID: <d22.31d8c77b.367827bb@aol.com>

 
In a message dated 15/12/2008 21:05:16 GMT Standard Time, GandalfG8 at aol.com  
writes:

If you  check out the PTS manuals I uploaded to Didier's site I'm sure one  
of  
those has the GPIB section, if not let me know and I should be able to  scan  
it from one of my other manuals.

My original PTS160  manual doesn't include the GPIB section but I'm pretty  
sure thay'll  all be similar.
The Manuals or PTS catalogue should give the option numbers  in each  case 
for 
comparison anyway.




--------------------
Hi again Had
 
I've just checked what I uploaded, and the PTS310 manual has a GPIB section  
in it.
I've also got a separate scan of the GPIB section from my PTS250 manual and  
that has different module/PCB numbers and might be closer to what's in the PTS 
 160 but, as I said before, I don't recall there being very much  difference.
 
I can't remember without checking what the the module references are for  the 
PTS 160 but will email you the separate section anyway.
 
regards
 
Nigel
GM8PZR
 

From bruce.griffiths at xtra.co.nz  Mon Dec 15 21:56:26 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Tue, 16 Dec 2008 10:56:26 +1300
Subject: [time-nuts] Sub Pico Second Phase logger
In-Reply-To: <OF6D4BA695.2556A502-ON85257520.0056DA8F-85257520.005956F1@mck.us.ray.com>
References: <OF6D4BA695.2556A502-ON85257520.0056DA8F-85257520.005956F1@mck.us.ray.com>
Message-ID: <4946D28A.2010201@xtra.co.nz>

Joe

Joseph M Gwinn wrote:
> Bruce,
>
>
> time-nuts-bounces at febo.com wrote on 12/11/2008 07:44:01 PM:
>
>   
>> Joe
>>
>> Isolation from mixer RF to LO port may be too low when the mixer input
>> frequencies are different.
>> Injection locking can then occur all too easily (just ask Ulrich about
>> this) when the mixer RF ports are driven by 2 separate OCXOs.
>>
>> Detailed in line post follows:
>>
>> Bruce
>>
>> Joseph M Gwinn wrote:
>>     
>>> Bruce,
>>>
>>>
>>> time-nuts-bounces at febo.com wrote on 12/10/2008 08:38:13 PM:
>>>
>>>
>>>       
>>>> Joe
>>>> Joseph M Gwinn wrote:
>>>>
>>>>         
>>>>> Bruce,
>>>>>
>>>>>
>>>>>
>>>>>           
>>>>>> Reflecting the sum frequency back into the mixer is actually 
>>>>>>             
> necessary
>   
>>>>>> to reduce the noise at the IF port.
>>>>>> I believe that one of Agilent's simulation application notes 
>>>>>>             
> mentions
>   
>>>>>> this effect but I don't recall the actual application note number.
>>>>>> This will affect the mixer RF and IF port impedance so adding a 
>>>>>> series resistor may be required to improve the SWR.
>>>>>>
>>>>>>
>>>>>>             
>>>>> How big an effect is this?  Is the absolute noise decreased, or does 
>>>>>           
>
>   
>>>>> it remain the same while the signal increase?
>>>>>
>>>>>
>>>>>
>>>>>           
>>>> With the same difference frequency IF port termination impedance, 
>>>>         
> noise
>   
>>>> is actually decreased along with the mixer conversion loss.
>>>>
>>>>         
>>> OK.  Complicated beasts, those mixers.  Do you know of a paper (or 
>>>       
> book) 
>   
>>> on the subject?
>>>
>>>
>>>       
>> Not offhand, but this crops up in lots of places usually when one least
>> expects it..
>>     
>
> I've noticed.  Someone has to have poured his soul into a monograph.
>
>
>   
>>>> However if the sound card input noise dominates, reducing the mixer
>>>> effective output noise won't help.
>>>>
>>>>         
>>> Yes.  In the plots you posted in a different email, there was a big 
>>>       
> rise 
>   
>>> below 1 KHz (scan stopped at 1 KHz, so don't know the shape).  Why is 
>>> this?
>>>
>>>       
>> I'll expand the frequency scale and take another snapshot for the region
>> below 1kHz.
>> This rise may be due to ADC and/or input differential amplifier flicker
>> noise.
>>     
>
> Saw it.  Thanks.  Does look like flicker noise.  Although it wasn't large 
> enough to be a real problem it seems.
>
>  
>
>   
>>>> If one is time stamping the zero crossings an increased zero-crossing 
>>>>         
>
>   
>>>> slope is an advantage. 
>>>> For relative phase measurements a trapezoidal beat frequencywaveform 
>>>> may be less useful.
>>>>         
>>> Fitting to the approximate waveshape, sine or trapezoidal, 
>>> should yield a very robust estimate, due to the large data support, 
>>>       
> and zero-crossing 
>   
>>> slope won't much matter.  Hmm.  Actually, if the slopes of the 
>>>       
> trapezoid 
>   
>>> are too steep, we may not have all that many slope samples.
>>>
>>>
>>>
>>>       
>> If one believes the NIST papers the trapezoid zero crossing slope only
>> increases by a factor of 3.
>> If one uses a cascaded filter limiter the slope gain can be adjusted for
>> optimum results.
>>     
>
> The implication would be to not sharpen things up too well in before 
> digitizing.
>
>
>   
>>> [snip]
>>>
>>>       
>>>> Of course with a capacitive IF port termination, matching the RF and 
>>>>         
> LO
>   
>>>> ports becomes more critical as does the reverse isolation of the 
>>>>         
> various
>   
>>>> amplifiers driving the RF and LO ports.
>>>> It may be simpler in fact to use a level 17 mixer with high LO to RF 
>>>>         
> and
>   
>>>> LO to IF isolation with the RF port unsaturated as it relaxes the
>>>> reverse isolation specs for the isolation amplifiers.
>>>>
>>>>         
>>> Another tradeoff.  I'll have to think about it.
>>>
>>> I'm thinking of 6 db and 10 db attenuators on the LO and RF ports 
>>> respectively, but no isolation amplifier.
>>>       
>> You may get away with that if you use mixers with very high RF to LO
>> port isolation.
>> Minicircuits have at least 3 level 17 mixer models that typically have
>> 80dB LO to RF isolation at 10MHz.
>>     
>
> I've used the ZRPD-1, which claims about 75 dB isolation at 10 MHz.
>
>  
>   
>> Using a passive splitter for the LO drives will gain at least another
>> 30dB in isolation between the 2 RF inputs if you use an appropriate
>> splitter.
>>     
>
> True. 
>
> I may have lost the thread here.  If we have one oscillator driving 
> everything, one cannot have injection locking even if isolation isn't 
> perfect.  What isolation does gain us is a reduction in undesired phase 
> shifta.
>
>
>   
You have 2 oscillators, the test source and the offset source, however
the >= 10Hz frequency offset between them means that the isolation
requirements are relaxed considerably.
If the offset oscillator is derived from the source then injection
locking doesnt occur.
I made the general comment to ensure that anyone following the thread,
who may be contemplating building a dual mixer setup with 2 sources very
close in frequency doesnt forget about the isolation requirements.
>  
>   
>>> [snip]
>>>
>>>       
>>>> The only configuration for which it makes any sense is an inverting
>>>> input amplifier with a finite input voltage offset.
>>>>
>>>>         
>>> Why would non-inverting not work?  Both inputs source or sink bias 
>>> currents, and non-inverting presents a very high impedance.
>>>       
>> Non inverting amplifiers usually have lower noise and generally work 
>>     
> very well.
>   
>> I was only trying to come up with a preamp circuit for which the
>> comments in the Minicircuits application note on the effect of amplifier
>> input offset voltage made any sense.
>>     
>
> Ah.  It may be hopeless.
>
> My reading was that they were worried about bias currents from the amp 
> flowing into the mixer and causing offsets, not amplifier offset voltages 
> per se.  The amplifier offset voltage does not cause a mixer offset, and 
> may be reduced by use of a chopper amp or very good balance.
>
>
>   
>> The only risk with a noninverting amplifier, is that under fault
>> conditions (missing supply) a very large current can flow back (with
>> some low noise opamps as Enrico has experienced) into the mixers and
>> destroy them.
>>     
>
> Yes, I recall the discussion on your website.
>
>  
>   
>> For this particular application the mixer preamp gain need only be
>> sufficient to boost the mixer phase detector output (1V pk?, 350mV pk??
>> depends on mixer and its operating conditions) to the sound card input
>> (FSR ~ 5.6V pk for an AP192). The resultant preamp gain is relatively
>> low ( 5 - 15X depending on the mixer etc) and the sound card noise will
>> dominate (~ 100nV/rtHz midband for an AP192) thus using an ultra low
>> noise mixer preamp isn't necessary.
>>     
>
> Yes.
>
>
>
>   
>>> We are converging on a soundcard wishlist:
>>>
>>> 1.  True balanced inputs on XLR connectors.  And good ground design, 
>>>       
> so we 
>   
>>> aren't bedeviled by ground loops.
>>>
>>> 2.  24-bit ADCs, and similar DACs.
>>>
>>> 3.  Very good isolation all around. 
>>>
>>> 4.  Digital access via firewire (or USB3 I suppose), with the 
>>>       
> soundcard in 
>   
>>> its own box.
>>>
>>> 5.  High-level input direct to the ADCs.
>>>
>>>
>>> While use of AKM ICs may be a very good idea, it is not a requirement 
>>>       
> per 
>   
>>> se.
>>>
>>> [snip]
>>>
>>>       
>> Optical isolation of the ADC from the noisy digital interface to the PC
>> would also be nice.
>>     
>
> Good point.  Part of ground design I suppose.   Although with noise floor 
> of -150 dB down there cannot be so much leakage.
>
>  
>   
>> If we design our own PCB then the AD7760 series ADCs are another
>> possible option.
>> These have a built in differential input differential output amplifier.
>>     
>
> Yes.  But aren't we trying to use commonly available soundcards?
>
>   
Ideally yes, but they all seem to have built in performance limitations.
AFAIK the AP192 with its 4Vrms full scale balanced inputs with no
variable gain preamps or +48V phantom supplies seems to be one of the
best for this application.
Its major drawback is that its a PCI card located within a noisy PC.
The 4V rms input allows the mixer preamp to use devices like the THAT
1646 to drive the balance sound card inputs without degrading the noise
floor too much.
With a 1V rms full scale the noise floor degradation would be very
obvious when using a THAT1646 (equivalent devices are even noisier).
It may be better to use a mixer preamp with a transformer coupled output
stage using hybrid feedback to achieve a low frequency cutoff below 1Hz
together with low noise.
>  
>   
>>>>>> Can alleviate [oddities at end of phase range} to some extent by 
>>>>>> driving a pair of such phase detectors so that their outputs are in 
>>>>>>             
>
>   
>>>>>> quadrature.
>>>>>>             
>>>>>> One just selects the phase detector output that is in the linear 
>>>>>> range.
>>>>>>             
>>>>>> The quadrature outputs also allow unambiguous assignment of the 
>>>>>>             
> sign 
>   
>>>>>> of any phase change.
>>>>>>
>>>>>>
>>>>>>             
>>>>> The Symmetricom 5120A does something very clever to alleviate this 
>>>>> problem.  Explained in US patent 7,227,346 and "Direct-Digital 
>>>>> Phase-Noise Measurement"; J. Grove, J. Hein, J. Retta, P. Schweiger, 
>>>>>           
> W.Solbrig, 
>   
>>>>> and S.R. Stein; 2004 IEEE International Ultrasonics, Ferroelectrics, 
>>>>>           
> and 
>   
>>>>> Frequency Control Joint 50th Anniversary Conference, pages 287-291.
>>>>>
>>>>> Joe
>>>>>
>>>>>
>>>>>
>>>>>           
>>>> I've read the patent.
>>>>
>>>>         
>>> The paper is also worthwhile, and available on the web somewhere 
>>>       
> (don't 
>   
>>> recall where, but google found the pdf).  I had to read the patent 
>>> multiple times to figure out what's going on.  The correlation 
>>>       
> approach is 
>   
>>> old as the hills, and only the digital phase detector was patentable.
>>>
>>>       
>> It may be feasible to achieve the same effect by purely digital means at
>> least for low sample rates where FIR filters with tens of thousands of
>> taps are feasible.
>>     
>
> It *is* feasible, and Sam Stein is doing it.  I've perhaps lost the thread 
> here.
>
>
>   
No, I meant replace his 90 degree hybrids with a digital equivalent.
>> Of course 64 bit or higher precision arithmetic is then mandatory to
>> avoid excessive calculation roundoff noise.
>>     
>
> It may be 64 bit *integer*, actually.
>
> My understanding is that the 5120A is built upon a DSP or more likely FPGA 
> (of unspecified make and model).  The 5125A will have a top frequency of 
> 400 MHz, so the DSP and/or FPGA better be damn fast.  Little analog stuff 
> remains.
>
>   
Although the 5125A appeared in the 2008 product catalog, it isn't on the
website yet.
> Joe
>
>   

Bruce


From bruce.griffiths at xtra.co.nz  Mon Dec 15 21:59:31 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Tue, 16 Dec 2008 10:59:31 +1300
Subject: [time-nuts] Close-in phase noise question...
In-Reply-To: <121520081653.29002.49468B97000A67F50000714A22243429029B0A02D29B9B0EBF9C0396CE0E99@att.net>
References: <4941B3D1.9030102@xtra.co.nz>	<OF6D4BA695.2556A502-ON85257520.0056DA8F-85257520.005956F1@mck.us.ray.com>
	<121520081653.29002.49468B97000A67F50000714A22243429029B0A02D29B9B0EBF9C0396CE0E99@att.net>
Message-ID: <4946D343.4000101@xtra.co.nz>

wa1zms at att.net wrote:
> Looking for comment here...
>
> The background:
> I'm working on a sub mm-wave LO chain for
> a ham radio application. While chasing issues
> of close-in phase (ie: within 1KHz of RF
> carrier) by peeling the "layers of the onion",
> I'm starting to question the performance of
> the MMICs that are used as buffers and amps
> following my Wenzel reference OCXOs.
>
> Question(s):
> Should any MMIC be allowed to be driven
> close to compression or into compression
> when striving for best close-in noise?
>
> I know and have seen the NF of a MMIC
> degrade while in compression, but my
> target right now is close-in noise rather
> than broadband noise.
>
> My design, in summary, takes 5MHz up to 630GHz
> via several multipliers and PLL stages.
>
> -Brian
>   
Brian

The increased nonlinearity when driven into compression will enhance the
conversion of low frequency noise to phase noise.

Bruce


From gwinn at raytheon.com  Mon Dec 15 22:12:39 2008
From: gwinn at raytheon.com (Joseph M Gwinn)
Date: Mon, 15 Dec 2008 17:12:39 -0500
Subject: [time-nuts] Sub Pico Second Phase logger
In-Reply-To: <4946CD6A.7070003@xtra.co.nz>
Message-ID: <OFFF478C92.B518B587-ON85257520.007900D3-85257520.0079F252@mck.us.ray.com>

Bruce,


time-nuts-bounces at febo.com wrote on 12/15/2008 04:34:34 PM:

> Joseph M Gwinn wrote:
> > Bruce,
> >
> >
> > time-nuts-bounces at febo.com wrote on 12/11/2008 08:36:47 PM:
> >
> > 
> >> Joe
> >>
> >> Attached is noise spectrum (1kHz and below) of AP192 with nothing
> >> connected to inputs.
> >> Sampling rate 96KSPS.
> >> Frequency bin equivalent noise bandwidth ~ 3Hz.
> >> Noise has similar spectrum to flicker noise with a noise corner of
> >> around 300Hz or so.
> >> 
> >
> > The noise floor ain't so bad, -130 dB (dBm? dbV?) at maybe 10 Hz, even 
if 
> > it's 20 dB worse than at 1 KHz.
> >
> > Has anyone measured the Allan Deviation?
> >
> > Joe
> >
> >
> > 
> Joe
> 
> Noise plot is with respect to full scale (4Vrms).

OK, call it dbV+12db.


> I need to build a noise source to check the absolute level.
> Will use the amplified Johnson noise of a 150K resistor.
> 
> By Allan deviation do you mean calculate it from the sequential 96KSPS
> ADC output samples?

Yes, although some decimation may be needed to keep compute times under 
control, at least for the larger values of tau.

 
> I can do this, but since the dominant noise source is white the Allan
> deviation will scale with the measurement bandwidth.

Would modified Allan deviation be better?

I'm more interested in the general shape of the Allan curve than its 
absolute value, one issue being the effect of thermal variations in your 
laboratory dungeon.  We had speculated as to the relative size of thermal 
effects in these sound cards, and this would give us some idea.


Joe


From bruce.griffiths at xtra.co.nz  Mon Dec 15 22:31:27 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Tue, 16 Dec 2008 11:31:27 +1300
Subject: [time-nuts] Sub Pico Second Phase logger
In-Reply-To: <OFFF478C92.B518B587-ON85257520.007900D3-85257520.0079F252@mck.us.ray.com>
References: <OFFF478C92.B518B587-ON85257520.007900D3-85257520.0079F252@mck.us.ray.com>
Message-ID: <4946DABF.1070903@xtra.co.nz>

Joseph M Gwinn wrote:
> Bruce,
>
>
> time-nuts-bounces at febo.com wrote on 12/15/2008 04:34:34 PM:
>
>   
>> Joseph M Gwinn wrote:
>>     
>>> Bruce,
>>>
>>>
>>> time-nuts-bounces at febo.com wrote on 12/11/2008 08:36:47 PM:
>>>
>>>
>>>       
>>>> Joe
>>>>
>>>> Attached is noise spectrum (1kHz and below) of AP192 with nothing
>>>> connected to inputs.
>>>> Sampling rate 96KSPS.
>>>> Frequency bin equivalent noise bandwidth ~ 3Hz.
>>>> Noise has similar spectrum to flicker noise with a noise corner of
>>>> around 300Hz or so.
>>>>
>>>>         
>>> The noise floor ain't so bad, -130 dB (dBm? dbV?) at maybe 10 Hz, even 
>>>       
> if 
>   
>>> it's 20 dB worse than at 1 KHz.
>>>
>>> Has anyone measured the Allan Deviation?
>>>
>>> Joe
>>>
>>>
>>>
>>>       
>> Joe
>>
>> Noise plot is with respect to full scale (4Vrms).
>>     
>
> OK, call it dbV+12db.
>
>
>   
>> I need to build a noise source to check the absolute level.
>> Will use the amplified Johnson noise of a 150K resistor.
>>
>> By Allan deviation do you mean calculate it from the sequential 96KSPS
>> ADC output samples?
>>     
>
> Yes, although some decimation may be needed to keep compute times under 
> control, at least for the larger values of tau.
>
>  
>   
>> I can do this, but since the dominant noise source is white the Allan
>> deviation will scale with the measurement bandwidth.
>>     
>
> Would modified Allan deviation be better?
>
> I'm more interested in the general shape of the Allan curve than its 
> absolute value, one issue being the effect of thermal variations in your 
> laboratory dungeon.  We had speculated as to the relative size of thermal 
> effects in these sound cards, and this would give us some idea.
>
>
> Joe
>
>   

Joe

Modified ADEV, ADEV etc are possible, although the maximum usable record
length probably depends more on the limits of Plotter and Windows 2K.


I'll look into doing this.
Real time filtering and decimation may be impractical, in the short term
at least, as most signal processing libraries only process 16 bit samples.
Most real time spectrum analysis programs are similarly afflicted in
that they only process 16 bit samples.

Bruce


From gwinn at raytheon.com  Mon Dec 15 23:03:33 2008
From: gwinn at raytheon.com (Joseph M Gwinn)
Date: Mon, 15 Dec 2008 18:03:33 -0500
Subject: [time-nuts] Sub Pico Second Phase logger
In-Reply-To: <4946D28A.2010201@xtra.co.nz>
Message-ID: <OF1AE7C59E.EA0B42E0-ON85257520.007A9F40-85257520.007E9B55@mck.us.ray.com>

Bruce,


time-nuts-bounces at febo.com [Bruce] wrote on 12/15/2008 04:56:26 PM:

> Joe
> 
> Joseph M Gwinn wrote:
> > Bruce,
> >
> >
> > time-nuts-bounces at febo.com wrote on 12/11/2008 07:44:01 PM:
> >
> > 
[snip]
> > 
> > 
> >> Using a passive splitter for the LO drives will gain at least another
> >> 30dB in isolation between the 2 RF inputs if you use an appropriate
> >> splitter.
> >> 
> >
> > True. 
> >
> > [Joe] I may have lost the thread here.  If we have one oscillator 
driving 
> > everything, one cannot have injection locking even if isolation isn't 
> > perfect.  What isolation does gain us is a reduction in undesired 
phase 
> > shifts.
> >
> >
> > 
> You have 2 oscillators, the test source and the offset source, however
> the >= 10Hz frequency offset between them means that the isolation
> requirements are relaxed considerably.
> If the offset oscillator is derived from the source then injection
> locking doesnt occur.
> I made the general comment to ensure that anyone following the thread,
> who may be contemplating building a dual mixer setup with 2 sources very
> close in frequency doesnt forget about the isolation requirements.

I see.  We had two intertwined threads.

 
> >>> [snip]
> >>>
> >>> 
> >>>> The only configuration for which it makes any sense is an inverting
> >>>> input amplifier with a finite input voltage offset.
> >>>>
> >>>> 
> >>> Why would non-inverting not work?  Both inputs source or sink bias 
> >>> currents, and non-inverting presents a very high impedance.
> >>> 
> >> Non inverting amplifiers usually have lower noise and generally work 
> >> very well.
> > 
> >> I was only trying to come up with a preamp circuit for which the
> >> comments in the Minicircuits application note on the effect of 
amplifier
> >> input offset voltage made any sense.
> >> 
> >
> > Ah.  It may be hopeless.
> >
> > My reading was that they were worried about bias currents from the amp 

> > flowing into the mixer and causing offsets, not amplifier offset 
voltages 
> > per se.  The amplifier offset voltage does not cause a mixer offset, 
and 
> > may be reduced by use of a chopper amp or very good balance.

By the way, I've noticed that Tek TDS3012B oscilloscope inputs can cause 
offsets as well, again I assume from the bias currents.  The circuit has 
the scope input in parallel with the Agilent 34410A 6.5-digit voltmeter. 
With scope input set to DC, big effect.  Set to AC, small effect.  Set to 
Gnd, no effect.  (Input is not grounded, so voltmeter is still happy.) 
Didn't try changing the input volts/cm scale.  Anyway, I think that this 
effect is what the mystery app note was trying to say.  A bias current 
from the scope would cause a voltage offset that depended on the DC 
resistance through which the bias current flowed, the DC load of the mixer 
in this case.



 
> >> If we design our own PCB then the AD7760 series ADCs are another
> >> possible option.
> >> These have a built in differential input differential 
outputamplifier.
> >> 
> >
> > Yes.  But aren't we trying to use commonly available soundcards?
> >
> > 
> Ideally yes, but they all seem to have built in performance limitations.
> AFAIK the AP192 with its 4Vrms full scale balanced inputs with no
> variable gain preamps or +48V phantom supplies seems to be one of the
> best for this application.
> Its major drawback is that its a PCI card located within a noisy PC.

I think that there are many top-end firewire soundcards.  Whatever the 
music folk like the sound of would be a good place to start - musicians' 
well-trained hearing can be quite good.  At least above 20 Hz.

Actually, the people that make the AP192 do have firewire and usb 
offerings:

<http://www.m-audio.com/index.php?do=products.family&ID=recording>



> The 4V rms input allows the mixer preamp to use devices like the THAT
> 1646 to drive the balanced sound card inputs without degrading the noise
> floor too much.

Or build an isolation amp with some gain, and kill two birds with one 
stone?


> With a 1V rms full scale the noise floor degradation would be very
> obvious when using a THAT 1646 (equivalent devices are even noisier).
> It may be better to use a mixer preamp with a transformer coupled output
> stage using hybrid feedback to achieve a low frequency cutoff below 1Hz
> together with low noise.

With a transformer, even if toroidal, keeping hum out may prove quite 
difficult.

 
> >>>>>> Can alleviate [oddities at end of phase range} to some extent by 
> >>>>>> driving a pair of such phase detectors so that their outputs are 
in 
> >>>>>> quadrature.
> >>>>>> 
> >>>>>> One just selects the phase detector output that is in the linear 
> >>>>>> range.
> >>>>>> 
> >>>>>> The quadrature outputs also allow unambiguous assignment of the 
> >>>>>> sign of any phase change.
> >>>>>>
> >>>>>>
> >>>>>> 
> >>>>> The Symmetricom 5120A does something very clever to alleviate this 

> >>>>> problem.  Explained in US patent 7,227,346 and "Direct-Digital 
> >>>>> Phase-Noise Measurement"; J. Grove, J. Hein, J. Retta, P. 
Schweiger, 
> >>>>> W.Solbrig, and S.R. Stein; 2004 IEEE International Ultrasonics, 
Ferroelectrics, 
> >>>>> and Frequency Control Joint 50th Anniversary Conference, pages 
287-291.
> >>>>>
> >>>>> 
> >>>> I've read the patent.
> >>>>
> >>>> 
> >>> The paper is also worthwhile, and available on the web somewhere 
> >>> (don't recall where, but google found the pdf).  I had to read the 
patent 
> >>> multiple times to figure out what's going on.  The correlation 
> >>> approach is old as the hills, and only the digital phase detector 
was patentable.
> >>>
> >>> 
> >> It may be feasible to achieve the same effect by purely digital means 
at
> >> least for low sample rates where FIR filters with tens of thousands 
of
> >> taps are feasible.
> >> 
> >
> > It *is* feasible, and Sam Stein is doing it.  I've perhaps lost the 
thread 
> > here.
> >
> > 
> No, I meant replace his 90 degree hybrids with a digital equivalent.

I believe that his 90-degree hybrids are already digital.  I think that 
there is a very short analog path, maybe just a buffer amplifier and a 
bunch of fancy ADCs.  I had to reread the patent, to read between the 
lines.  It is presented as if there were a number of physical components, 
but one can also read it to mean that these are logical components 
implemented in some kind of machine code. At 400 MHz, one would assume 
that the signal processor must be a FPGA, probably one of the fastest ones 
made.

One example is the DDS core.  Somewhere in the patent text it in effect 
says that one can also implement this by table lookup, and that if one 
chooses the table length correctly, one can contain a full cycle (where 
the "phase accumulator" returns to the exact same value) of full-precision 
amplitude samples.  This allows one to eliminate all spectral spurs in the 
DDS output, which is hard to do if there is phase truncation.


> >
> > My understanding is that the 5120A is built upon a DSP or more likely 
FPGA 
> > (of unspecified make and model).  The 5125A will have a top frequency 
of 
> > 400 MHz, so the DSP and/or FPGA better be damn fast.  Little analog 
stuff 
> > remains.
> >
> > 
> Although the 5125A appeared in the 2008 product catalog, it isn't on the
> website yet.

When I last talked to Symmetricom's sales folk about the 5120A and 5125A 
(about a year ago), they said that Sam was still trying to get the 5125A 
to work properly.  He may still be cleaning things up, as scaling up from 
30 MHz to 400 MHz is quite the jump, and may have forced a redesign.

Joe


From bruce.griffiths at xtra.co.nz  Mon Dec 15 23:42:59 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Tue, 16 Dec 2008 12:42:59 +1300
Subject: [time-nuts] Sub Pico Second Phase logger
In-Reply-To: <OF1AE7C59E.EA0B42E0-ON85257520.007A9F40-85257520.007E9B55@mck.us.ray.com>
References: <OF1AE7C59E.EA0B42E0-ON85257520.007A9F40-85257520.007E9B55@mck.us.ray.com>
Message-ID: <4946EB83.6050005@xtra.co.nz>

Joe
Joseph M Gwinn wrote:
> Bruce,
>
>
> time-nuts-bounces at febo.com [Bruce] wrote on 12/15/2008 04:56:26 PM:
>
>   
>> Joe
>>
>> Joseph M Gwinn wrote:
>>     
>>> Bruce,
>>>
>>>
>>> time-nuts-bounces at febo.com wrote on 12/11/2008 07:44:01 PM:
>>>
>>>
>>>       
> [snip]
>   
>>>       
>>>> Using a passive splitter for the LO drives will gain at least another
>>>> 30dB in isolation between the 2 RF inputs if you use an appropriate
>>>> splitter.
>>>>
>>>>         
>>> True. 
>>>
>>> [Joe] I may have lost the thread here.  If we have one oscillator 
>>>       
> driving 
>   
>>> everything, one cannot have injection locking even if isolation isn't 
>>> perfect.  What isolation does gain us is a reduction in undesired 
>>>       
> phase 
>   
>>> shifts.
>>>
>>>
>>>
>>>       
>> You have 2 oscillators, the test source and the offset source, however
>> the >= 10Hz frequency offset between them means that the isolation
>> requirements are relaxed considerably.
>> If the offset oscillator is derived from the source then injection
>> locking doesnt occur.
>> I made the general comment to ensure that anyone following the thread,
>> who may be contemplating building a dual mixer setup with 2 sources very
>> close in frequency doesnt forget about the isolation requirements.
>>     
>
> I see.  We had two intertwined threads.
>
>  
>   
>>>>> [snip]
>>>>>
>>>>>
>>>>>           
>>>>>> The only configuration for which it makes any sense is an inverting
>>>>>> input amplifier with a finite input voltage offset.
>>>>>>
>>>>>>
>>>>>>             
>>>>> Why would non-inverting not work?  Both inputs source or sink bias 
>>>>> currents, and non-inverting presents a very high impedance.
>>>>>
>>>>>           
>>>> Non inverting amplifiers usually have lower noise and generally work 
>>>> very well.
>>>>         
>>>> I was only trying to come up with a preamp circuit for which the
>>>> comments in the Minicircuits application note on the effect of 
>>>>         
> amplifier
>   
>>>> input offset voltage made any sense.
>>>>
>>>>         
>>> Ah.  It may be hopeless.
>>>
>>> My reading was that they were worried about bias currents from the amp 
>>>       
>
>   
>>> flowing into the mixer and causing offsets, not amplifier offset 
>>>       
> voltages 
>   
>>> per se.  The amplifier offset voltage does not cause a mixer offset, 
>>>       
> and 
>   
>>> may be reduced by use of a chopper amp or very good balance.
>>>       
>
> By the way, I've noticed that Tek TDS3012B oscilloscope inputs can cause 
> offsets as well, again I assume from the bias currents.  The circuit has 
> the scope input in parallel with the Agilent 34410A 6.5-digit voltmeter. 
> With scope input set to DC, big effect.  Set to AC, small effect.  Set to 
> Gnd, no effect.  (Input is not grounded, so voltmeter is still happy.) 
> Didn't try changing the input volts/cm scale.  Anyway, I think that this 
> effect is what the mystery app note was trying to say.  A bias current 
> from the scope would cause a voltage offset that depended on the DC 
> resistance through which the bias current flowed, the DC load of the mixer 
> in this case.
>
>   
However the proposed remedy has little or no effect on the errors caused
by such bias currents (eg transistor base currents).
The series resistor could be reduced to zero without effect on the mixer
offset due to the bias current. However the preamp offset due to the
source resistance would be reduced.
>
>  
>   
>>>> If we design our own PCB then the AD7760 series ADCs are another
>>>> possible option.
>>>> These have a built in differential input differential 
>>>>         
> outputamplifier.
>   
>>> Yes.  But aren't we trying to use commonly available soundcards?
>>>
>>>
>>>       
>> Ideally yes, but they all seem to have built in performance limitations.
>> AFAIK the AP192 with its 4Vrms full scale balanced inputs with no
>> variable gain preamps or +48V phantom supplies seems to be one of the
>> best for this application.
>> Its major drawback is that its a PCI card located within a noisy PC.
>>     
>
> I think that there are many top-end firewire soundcards.  Whatever the 
> music folk like the sound of would be a good place to start - musicians' 
> well-trained hearing can be quite good.  At least above 20 Hz.
>
> Actually, the people that make the AP192 do have firewire and usb 
> offerings:
>
> <http://www.m-audio.com/index.php?do=products.family&ID=recording>
>
>   

I've looked at all of the M-Audio offerings.
The more expensive ones have built in preamps plus 48V phantom supplies,
which can be switched off, however the presence of the switched +48V
supply is perhaps an invitation to disaster.

I've also looked at the specs for several other high end sound cards.
Quite a few only have single ended inputs.
Maybe, I should document the various cards and highlight their
shortcomings etc for this application.

>> The 4V rms input allows the mixer preamp to use devices like the THAT
>> 1646 to drive the balanced sound card inputs without degrading the noise
>> floor too much.
>>     
>
> Or build an isolation amp with some gain, and kill two birds with one 
> stone?
>
>
>   
A low noise isolation amplifier with a frequency response down to 1Hz or
so without using a transformer may be difficult to do.
>> With a 1V rms full scale the noise floor degradation would be very
>> obvious when using a THAT 1646 (equivalent devices are even noisier).
>> It may be better to use a mixer preamp with a transformer coupled output
>> stage using hybrid feedback to achieve a low frequency cutoff below 1Hz
>> together with low noise.
>>     
>
> With a transformer, even if toroidal, keeping hum out may prove quite 
> difficult.
>
>   
High end (eg Lundahl LL1517) line output audio transformers come with mu
metal screens and metal foil interwinding shields.
>  
>   
>>>>>>>> Can alleviate [oddities at end of phase range} to some extent by 
>>>>>>>> driving a pair of such phase detectors so that their outputs are 
>>>>>>>>                 
> in 
>   
>>>>>>>> quadrature.
>>>>>>>>
>>>>>>>> One just selects the phase detector output that is in the linear 
>>>>>>>> range.
>>>>>>>>
>>>>>>>> The quadrature outputs also allow unambiguous assignment of the 
>>>>>>>> sign of any phase change.
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>                 
>>>>>>> The Symmetricom 5120A does something very clever to alleviate this 
>>>>>>>               
>
>   
>>>>>>> problem.  Explained in US patent 7,227,346 and "Direct-Digital 
>>>>>>> Phase-Noise Measurement"; J. Grove, J. Hein, J. Retta, P. 
>>>>>>>               
> Schweiger, 
>   
>>>>>>> W.Solbrig, and S.R. Stein; 2004 IEEE International Ultrasonics, 
>>>>>>>               
> Ferroelectrics, 
>   
>>>>>>> and Frequency Control Joint 50th Anniversary Conference, pages 
>>>>>>>               
> 287-291.
>   
>>>>>>>               
>>>>>> I've read the patent.
>>>>>>
>>>>>>
>>>>>>             
>>>>> The paper is also worthwhile, and available on the web somewhere 
>>>>> (don't recall where, but google found the pdf).  I had to read the 
>>>>>           
> patent 
>   
>>>>> multiple times to figure out what's going on.  The correlation 
>>>>> approach is old as the hills, and only the digital phase detector 
>>>>>           
> was patentable.
>   
>>>>>           
>>>> It may be feasible to achieve the same effect by purely digital means 
>>>>         
> at
>   
>>>> least for low sample rates where FIR filters with tens of thousands 
>>>>         
> of
>   
>>>> taps are feasible.
>>>>
>>>>         
>>> It *is* feasible, and Sam Stein is doing it.  I've perhaps lost the 
>>>       
> thread 
>   
>>> here.
>>>
>>>
>>>       
>> No, I meant replace his 90 degree hybrids with a digital equivalent.
>>     
>
> I believe that his 90-degree hybrids are already digital.
I'm not convinced of that, if only because real time 10,000+ tap FIR
filters at 30+MSPS are probably still impractical.
>   I think that 
> there is a very short analog path, maybe just a buffer amplifier and a 
> bunch of fancy ADCs.  I had to reread the patent, to read between the 
> lines.  It is presented as if there were a number of physical components, 
> but one can also read it to mean that these are logical components 
> implemented in some kind of machine code. At 400 MHz, one would assume 
> that the signal processor must be a FPGA, probably one of the fastest ones 
> made.
>
> One example is the DDS core.  Somewhere in the patent text it in effect 
> says that one can also implement this by table lookup, and that if one 
> chooses the table length correctly, one can contain a full cycle (where 
> the "phase accumulator" returns to the exact same value) of full-precision 
> amplitude samples.  This allows one to eliminate all spectral spurs in the 
> DDS output, which is hard to do if there is phase truncation.
>
>
>   
>>> My understanding is that the 5120A is built upon a DSP or more likely 
>>>       
> FPGA 
>   
>>> (of unspecified make and model).  The 5125A will have a top frequency 
>>>       
> of 
>   
>>> 400 MHz, so the DSP and/or FPGA better be damn fast.  Little analog 
>>>       
> stuff 
>   
>>> remains.
>>>
>>>
>>>       
>> Although the 5125A appeared in the 2008 product catalog, it isn't on the
>> website yet.
>>     
>
> When I last talked to Symmetricom's sales folk about the 5120A and 5125A 
> (about a year ago), they said that Sam was still trying to get the 5125A 
> to work properly.  He may still be cleaning things up, as scaling up from 
> 30 MHz to 400 MHz is quite the jump, and may have forced a redesign.
>
> Joe
>
>
>   

Bruce



From wa1zms at att.net  Tue Dec 16 02:07:55 2008
From: wa1zms at att.net (wa1zms at att.net)
Date: Mon, 15 Dec 2008 21:07:55 -0500
Subject: [time-nuts] Close-in phase noise question...
In-Reply-To: <4946D343.4000101@xtra.co.nz>
Message-ID: <FBEDKEIEMDPKGDDCPGNCMEHEEAAA.wa1zms@att.net>

Bruce-

OK... So, linear operation does therefore seem to be the preferred
way to operate these MMICs rather than operation into compression.
That's what I seem to be observing if only because my final RF
frequency is so high and RX bandwidth so low.

Having said that, if my frequency synthesis scheme involves a mixer
does the same effect of low frequency noise to phase noise conversion still
take place? After all, the mixer element is typically into compression
if it's a FET based mixer. I assume a diode mixer is more immune to
similar effects?

I'm trying to grow my intuitive understanding of the subtle sources of
noise. But I don't recall Maas giving much info on this topic in
his otherwise excellent text.

As always, thanks for your sagely advice.

-Brian


-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com]On
Behalf Of Bruce Griffiths
Sent: Monday, December 15, 2008 5:00 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Close-in phase noise question...


wa1zms at att.net wrote:
> Looking for comment here...
>
> The background:
> I'm working on a sub mm-wave LO chain for
> a ham radio application. While chasing issues
> of close-in phase (ie: within 1KHz of RF
> carrier) by peeling the "layers of the onion",
> I'm starting to question the performance of
> the MMICs that are used as buffers and amps
> following my Wenzel reference OCXOs.
>
> Question(s):
> Should any MMIC be allowed to be driven
> close to compression or into compression
> when striving for best close-in noise?
>
> I know and have seen the NF of a MMIC
> degrade while in compression, but my
> target right now is close-in noise rather
> than broadband noise.
>
> My design, in summary, takes 5MHz up to 630GHz
> via several multipliers and PLL stages.
>
> -Brian
>
Brian

The increased nonlinearity when driven into compression will enhance the
conversion of low frequency noise to phase noise.

Bruce

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To unsubscribe, go to
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From bruce.griffiths at xtra.co.nz  Tue Dec 16 02:18:17 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Tue, 16 Dec 2008 15:18:17 +1300
Subject: [time-nuts] Close-in phase noise question...
In-Reply-To: <FBEDKEIEMDPKGDDCPGNCMEHEEAAA.wa1zms@att.net>
References: <FBEDKEIEMDPKGDDCPGNCMEHEEAAA.wa1zms@att.net>
Message-ID: <49470FE9.9060706@xtra.co.nz>

Brian

Low frequency noise modulates the switching times of the mixer
components and hence produces close in phase noise.
Diode mixers especially those using Schottky diodes have lower flicker
noise than active mixers.

Passive FET mixers are not immune to flicker noise.
The level of such flicker noise increases with the RF current level.

Bruce


wa1zms at att.net wrote:
> Bruce-
>
> OK... So, linear operation does therefore seem to be the preferred
> way to operate these MMICs rather than operation into compression.
> That's what I seem to be observing if only because my final RF
> frequency is so high and RX bandwidth so low.
>
> Having said that, if my frequency synthesis scheme involves a mixer
> does the same effect of low frequency noise to phase noise conversion still
> take place? After all, the mixer element is typically into compression
> if it's a FET based mixer. I assume a diode mixer is more immune to
> similar effects?
>
> I'm trying to grow my intuitive understanding of the subtle sources of
> noise. But I don't recall Maas giving much info on this topic in
> his otherwise excellent text.
>
> As always, thanks for your sagely advice.
>
> -Brian
>
>
> -----Original Message-----
> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com]On
> Behalf Of Bruce Griffiths
> Sent: Monday, December 15, 2008 5:00 PM
> To: Discussion of precise time and frequency measurement
> Subject: Re: [time-nuts] Close-in phase noise question...
>
>
> wa1zms at att.net wrote:
>   
>> Looking for comment here...
>>
>> The background:
>> I'm working on a sub mm-wave LO chain for
>> a ham radio application. While chasing issues
>> of close-in phase (ie: within 1KHz of RF
>> carrier) by peeling the "layers of the onion",
>> I'm starting to question the performance of
>> the MMICs that are used as buffers and amps
>> following my Wenzel reference OCXOs.
>>
>> Question(s):
>> Should any MMIC be allowed to be driven
>> close to compression or into compression
>> when striving for best close-in noise?
>>
>> I know and have seen the NF of a MMIC
>> degrade while in compression, but my
>> target right now is close-in noise rather
>> than broadband noise.
>>
>> My design, in summary, takes 5MHz up to 630GHz
>> via several multipliers and PLL stages.
>>
>> -Brian
>>
>>     
> Brian
>
> The increased nonlinearity when driven into compression will enhance the
> conversion of low frequency noise to phase noise.
>
> Bruce
>
>   



From cupido at mail.ua.pt  Tue Dec 16 02:44:46 2008
From: cupido at mail.ua.pt (Luis Cupido)
Date: Tue, 16 Dec 2008 02:44:46 +0000
Subject: [time-nuts] Close-in phase noise question...
In-Reply-To: <FBEDKEIEMDPKGDDCPGNCMEHEEAAA.wa1zms@att.net>
References: <FBEDKEIEMDPKGDDCPGNCMEHEEAAA.wa1zms@att.net>
Message-ID: <4947161E.1060104@mail.ua.pt>

Brian,

I also think the linear operation would be better, but not
so sure if bipolar transistors wouldn't be preferred
over MMIC's for this (on bottom part of the spectrum)
(ok... is not so handy).

What I can certainly add to the discussion is that
power amplification followed by higher rate varactor
multiplication is considerably better than a multiple
lower multiplication ratios chain.
I had that experience on the 411GHz where from a 70MHz(*)
xtal osc amplified to several Watt driving varactors and
cavities. I jump with few steps to about 45GHz as opposed
to a DB6NT like LO chain which was noticeably worst in
the close in noise.

Using mixers without driving hard the LO or the RF with
same marginal level on both ports is possible but you will
be in trouble with level settings :-(
Not sure how much you would gain there... theoretically
something... but then AM to PM conversion is against you so
not sure if better or worst.

Luis Cupido
ct1dmk.

(*) x12 x9 x3 x2
w/ 9th harm corner cube harm mixer
if my memory serves me well....


wa1zms at att.net wrote:
> Bruce-
> 
> OK... So, linear operation does therefore seem to be the preferred
> way to operate these MMICs rather than operation into compression.
> That's what I seem to be observing if only because my final RF
> frequency is so high and RX bandwidth so low.
> 
> Having said that, if my frequency synthesis scheme involves a mixer
> does the same effect of low frequency noise to phase noise conversion still
> take place? After all, the mixer element is typically into compression
> if it's a FET based mixer. I assume a diode mixer is more immune to
> similar effects?
> 
> I'm trying to grow my intuitive understanding of the subtle sources of
> noise. But I don't recall Maas giving much info on this topic in
> his otherwise excellent text.
> 
> As always, thanks for your sagely advice.
> 
> -Brian
> 
> 
> -----Original Message-----
> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com]On
> Behalf Of Bruce Griffiths
> Sent: Monday, December 15, 2008 5:00 PM
> To: Discussion of precise time and frequency measurement
> Subject: Re: [time-nuts] Close-in phase noise question...
> 
> 
> wa1zms at att.net wrote:
>> Looking for comment here...
>>
>> The background:
>> I'm working on a sub mm-wave LO chain for
>> a ham radio application. While chasing issues
>> of close-in phase (ie: within 1KHz of RF
>> carrier) by peeling the "layers of the onion",
>> I'm starting to question the performance of
>> the MMICs that are used as buffers and amps
>> following my Wenzel reference OCXOs.
>>
>> Question(s):
>> Should any MMIC be allowed to be driven
>> close to compression or into compression
>> when striving for best close-in noise?
>>
>> I know and have seen the NF of a MMIC
>> degrade while in compression, but my
>> target right now is close-in noise rather
>> than broadband noise.
>>
>> My design, in summary, takes 5MHz up to 630GHz
>> via several multipliers and PLL stages.
>>
>> -Brian
>>
> Brian
> 
> The increased nonlinearity when driven into compression will enhance the
> conversion of low frequency noise to phase noise.
> 
> Bruce
> 
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
> 
> 
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
> 


From BriMDavis at aol.com  Tue Dec 16 03:15:08 2008
From: BriMDavis at aol.com (BriMDavis at aol.com)
Date: Mon, 15 Dec 2008 22:15:08 EST
Subject: [time-nuts] Build my own dist. amp ??
Message-ID: <d10.3f8510c7.3678773c@aol.com>

Just wondering if anyone has ever tried the MAX2470/2471
VCO buffers as part of a reference distribution design?
 

_http://www.maxim-ic.com/quick_view2.cfm/qv_pk/1985_ 
(http://www.maxim-ic.com/quick_view2.cfm/qv_pk/1985) 

 


MAX2471specs:
   10-500 Mhz
   75 dB reverse isolation at 100 MHz
   N.F.  8.4 dB
   Pout    0 dBm
 
  The only noise info in the datasheet that I could spot 
is the noise figure.
 
  I'd considered these for a LO buffer amp in a synthesizer
design many years ago, but never actually tested any parts
for residual phase noise.
 
Brian
**************A Good Credit Score is 700 or Above. See yours in just 2 easy 
steps! 
(http://pr.atwola.com/promoclk/100000075x1215195222x1200993641/aol?redir=http://www.freecreditreport.com/pm/default.aspx?sc=668072%26hmpgID=82%26bcd=De
cemailfooterNO82)

From bruce.griffiths at xtra.co.nz  Tue Dec 16 03:24:44 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Tue, 16 Dec 2008 16:24:44 +1300
Subject: [time-nuts] Build my own dist. amp ??
In-Reply-To: <d10.3f8510c7.3678773c@aol.com>
References: <d10.3f8510c7.3678773c@aol.com>
Message-ID: <49471F7C.3090606@xtra.co.nz>

BriMDavis at aol.com wrote:
> Just wondering if anyone has ever tried the MAX2470/2471
> VCO buffers as part of a reference distribution design?
>  
>
> _http://www.maxim-ic.com/quick_view2.cfm/qv_pk/1985_ 
> (http://www.maxim-ic.com/quick_view2.cfm/qv_pk/1985) 
>
>  
>
>
> MAX2471specs:
>    10-500 Mhz
>    75 dB reverse isolation at 100 MHz
>    N.F.  8.4 dB
>    Pout    0 dBm
>  
>   The only noise info in the datasheet that I could spot 
> is the noise figure.
>  
>   I'd considered these for a LO buffer amp in a synthesizer
> design many years ago, but never actually tested any parts
> for residual phase noise.
>  
> Brian
> **************A Good Credit Score is 700 or Above. See yours in just 2 easy 
> steps! 
> (http://pr.atwola.com/promoclk/100000075x1215195222x1200993641/aol?redir=http://www.freecreditreport.com/pm/default.aspx?sc=668072%26hmpgID=82%26bcd=De
> cemailfooterNO82)
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>
>   
Very noisy, too much gain and not enough output for use in a 10MHz
distribution amplifier with +7dbM - +15dBm input signal.
Attenuating the input to suit just degrades the phase nose even further.

Bruce


From tlinbeck at sbcglobal.net  Tue Dec 16 04:41:16 2008
From: tlinbeck at sbcglobal.net (Thomas Linbeck)
Date: Mon, 15 Dec 2008 22:41:16 -0600
Subject: [time-nuts] Info needed:  II Morrow A-22 LORAN Signal Generator
Message-ID: <000601c95f38$8918c900$4501a8c0@DJXTKX61>

Colleagues,

 

Would any of you be able to direct me to operation and/or service
documentation for the II Morrow A22 LORAN Signal Generator?

My web-searches have not proven eventful.  The IC date codes put the
manufacturing date in the 1985-1987 time periods.

Any help would be appreciated.

 

I wish each of you happiness and peace during this holiday season.

 

Thank you,

 

Tom Linbeck

K4TEU


From grant at ghengineering.co.uk  Tue Dec 16 10:05:24 2008
From: grant at ghengineering.co.uk (Grant Hodgson)
Date: Tue, 16 Dec 2008 10:05:24 +0000
Subject: [time-nuts] Close-in phase noise question...
In-Reply-To: <mailman.392.1229368512.2499.time-nuts@febo.com>
References: <mailman.392.1229368512.2499.time-nuts@febo.com>
Message-ID: <49477D64.3010005@ghengineering.co.uk>


Brian

Could you give some more details?  I think alternative solutions to 
MMICs at 5 and 10MHz would give much lower phase noise.

Bruce's web pages have a number of designs that will get the 5MHz 
reference up to 20MHz in 2 stages :-

http://www.ko4bb.com/~bruce/FrequencyMultipliers.html

Another approach would be to use op-amps instead of MMICs, op-amps with 
a low flicker corner frequency should give lower close in noise than a 
MMIC, but probably won't be as good as a discrete solution.

regards

Grant

> 	
> 
> Looking for comment here...
> 
> The background:
> I'm working on a sub mm-wave LO chain for
> a ham radio application. While chasing issues
> of close-in phase (ie: within 1KHz of RF
> carrier) by peeling the "layers of the onion",
> I'm starting to question the performance of
> the MMICs that are used as buffers and amps
> following my Wenzel reference OCXOs.
> 
> Question(s):
> Should any MMIC be allowed to be driven
> close to compression or into compression
> when striving for best close-in noise?
> 
> I know and have seen the NF of a MMIC
> degrade while in compression, but my
> target right now is close-in noise rather
> than broadband noise.
> 
> My design, in summary, takes 5MHz up to 630GHz
> via several multipliers and PLL stages.
> 
> -Brian


From bruce.griffiths at xtra.co.nz  Tue Dec 16 10:29:18 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Tue, 16 Dec 2008 23:29:18 +1300
Subject: [time-nuts] Close-in phase noise question...
In-Reply-To: <49477D64.3010005@ghengineering.co.uk>
References: <mailman.392.1229368512.2499.time-nuts@febo.com>
	<49477D64.3010005@ghengineering.co.uk>
Message-ID: <494782FE.8040109@xtra.co.nz>

Grant

The trouble with most MMICs is that they usually have too much gain and
insufficient reverse isolation for use in an isolation amplifier.
However when the available signal level is low using an MMIC to boost
the signal to around +13dBm or more can be useful.
They can have quite low close in phase noise if the right technology is
employed.
Bipolar MMICs (Si, SiGe, HBT) usually has low close in phase noise (see
Wenzel's sight for some low frequency (5Mhz, 10MHz) MMIC close in phase
noise data).

Wide band voltage feedback opamps like the now obsolete MAX477 don't
usually specify the low frequency noise and have higher phase noise than
a good discrete design.
Some current feedback opamps can have low input voltage noise at low
frequencies, however the relatively high low frequency input current
noise flowing through the feedback resistor more than negates this.
If only it were possible to shunt the feedback resistor with an inductor
whilst maintaining stability the effect of this noise source could be
reduced.

To minimise the effect of opamp input noise on the phase noise, the
signal amplitude at the opamp needs to be large (use an input
transformer to increase the signal amplitude) and the opamp gain kept low.
The dc noise gain of the opamp should be low (ie 1) to keep the close in
phase noise low.

There are very few opamps that are useful at 630MHz.
The few that are available tend to have high flicker noise.

Another approach at higher frequencies is to use feed forward techniques
to reduce amplifier phase noise by largely canceling it.

Bruce

Grant Hodgson wrote:
> Brian
>
> Could you give some more details?  I think alternative solutions to 
> MMICs at 5 and 10MHz would give much lower phase noise.
>
> Bruce's web pages have a number of designs that will get the 5MHz 
> reference up to 20MHz in 2 stages :-
>
> http://www.ko4bb.com/~bruce/FrequencyMultipliers.html
>
> Another approach would be to use op-amps instead of MMICs, op-amps with 
> a low flicker corner frequency should give lower close in noise than a 
> MMIC, but probably won't be as good as a discrete solution.
>
> regards
>
> Grant
>
>   
>> 	
>>
>> Looking for comment here...
>>
>> The background:
>> I'm working on a sub mm-wave LO chain for
>> a ham radio application. While chasing issues
>> of close-in phase (ie: within 1KHz of RF
>> carrier) by peeling the "layers of the onion",
>> I'm starting to question the performance of
>> the MMICs that are used as buffers and amps
>> following my Wenzel reference OCXOs.
>>
>> Question(s):
>> Should any MMIC be allowed to be driven
>> close to compression or into compression
>> when striving for best close-in noise?
>>
>> I know and have seen the NF of a MMIC
>> degrade while in compression, but my
>> target right now is close-in noise rather
>> than broadband noise.
>>
>> My design, in summary, takes 5MHz up to 630GHz
>> via several multipliers and PLL stages.
>>
>> -Brian
>>     
>
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>
>   



From preynaert at yahoo.com  Tue Dec 16 11:17:17 2008
From: preynaert at yahoo.com (Patrick Reynaert)
Date: Tue, 16 Dec 2008 03:17:17 -0800 (PST)
Subject: [time-nuts] Jupiter modules: 1pps or 10kHz to lock an OCXO
In-Reply-To: <494782FE.8040109@xtra.co.nz>
Message-ID: <560514.8358.qm@web58805.mail.re1.yahoo.com>

Using the 10kHz output to lock an OCXO is common practice and seems to give good results. 

Has anyone tried to use the 1pps output? One? could first make a simple divider to create a 0.5Hz reference with 50% duty cycle, and then use this signal to lock an OCXO. This would also allow the use of other OEM GPS modules that don't have the 10kHz but only the 1pps signal.

Of course, as the 0.5Hz signal is much lower in frequency than 10kHz, the short-term stability is pushed more to the OCXO, making the requirements of the OCXO even harder.

But maybe the 1pps signal has better stability than the 10kHz signal? Or is this the same since these signals will only influence the long-term stability of the oscillator and have the same accuracy?

Any thoughts are highly appreciated.

Thanks,
Patrick.







      

From yuri at ostry.ru  Tue Dec 16 11:27:42 2008
From: yuri at ostry.ru (Yuri Ostry)
Date: Tue, 16 Dec 2008 14:27:42 +0300
Subject: [time-nuts] RF transformers for distribution amplifier
Message-ID: <6310328920.20081216142742@ostry.ru>

Hello,

Just digged in my junkbox(es) in hope to find something to quickly
build distribution amp for Rb module that I just received from
fluke.l. Figured out that I'm pretty short in fast opamps, but found
considerable quantity of Mini-Circuits TC1-6-75-1 SMT wideband
transformers (same as sold now by someone on eBay for US $17.49 for
lot of 200 as item #110259000213).

Here is some more detailed specs that good people from Mini-Circuits
provided a year or so ago....

> The P/N TC1-6-75-1 is a Mini-Circuits custom design for one of our
> cust's. However, this model was made available for other customers
> as well.
>
> The specs are as follow:
> Frequency:  5 - 50 MHz
> Impedance ratio:  1:1
> Impedance:  75 ohms nominal
> Insertion Loss:  0.5 dB maximum
> Input Return Loss:  14 dB typical
> Maximum RF Input Power:  15 mW
> Operating temperature:  0 to 70 degrees C
> 
> All electrical specs measured with 0 mA DC current
> 
> Case style:  AT224
> Pinout:  (same as TC1-1)
> Primary dot = pin 6
> Primary = pin 4
> Secondary dot = pin 1
> Secondary = pin 3
> Not used = pin 2


I'm in doubt... I'd like to get about 1 volt p-p on a 50 ohm load from
amplifier outputs, and it looks like that this transformer may be
"overdriven" a little bit. Can it cause any serious problems?



-- 
Sincerely,
 Yuri                          mailto:yuri at ostry.ru



From robert8rpi at yahoo.co.uk  Tue Dec 16 13:47:57 2008
From: robert8rpi at yahoo.co.uk (Robert Atkinson)
Date: Tue, 16 Dec 2008 13:47:57 +0000 (GMT)
Subject: [time-nuts] RF transformers for distribution amplifier
In-Reply-To: <6310328920.20081216142742@ostry.ru>
Message-ID: <835725.40474.qm@web27101.mail.ukl.yahoo.com>

Hi Yuri,
I don't know about thr transformers you have, but a useful source of a very usable triple 1:1 50R transformer is an old 10base2 Ethernet card (the type with a BNC) these cards have a standard design that calls for isolation. They also yield a 5 (or 12) volt to 9V isolated DC-DC converter.
Robert G8RPI.

--- On Tue, 16/12/08, Yuri Ostry <yuri at ostry.ru> wrote:

From: Yuri Ostry <yuri at ostry.ru>
Subject: [time-nuts] RF transformers for distribution amplifier
To: time-nuts at febo.com
Date: Tuesday, 16 December, 2008, 11:27 AM

Hello,

Just digged in my junkbox(es) in hope to find something to quickly
build distribution amp for Rb module that I just received from
fluke.l. Figured out that I'm pretty short in fast opamps, but found
considerable quantity of Mini-Circuits TC1-6-75-1 SMT wideband
transformers (same as sold now by someone on eBay for US $17.49 for
lot of 200 as item #110259000213).

Here is some more detailed specs that good people from Mini-Circuits
provided a year or so ago....

> The P/N TC1-6-75-1 is a Mini-Circuits custom design for one of our
> cust's. However, this model was made available for other customers
> as well.
>
> The specs are as follow:
> Frequency:  5 - 50 MHz
> Impedance ratio:  1:1
> Impedance:  75 ohms nominal
> Insertion Loss:  0.5 dB maximum
> Input Return Loss:  14 dB typical
> Maximum RF Input Power:  15 mW
> Operating temperature:  0 to 70 degrees C
> 
> All electrical specs measured with 0 mA DC current
> 
> Case style:  AT224
> Pinout:  (same as TC1-1)
> Primary dot = pin 6
> Primary = pin 4
> Secondary dot = pin 1
> Secondary = pin 3
> Not used = pin 2


I'm in doubt... I'd like to get about 1 volt p-p on a 50 ohm load from
amplifier outputs, and it looks like that this transformer may be
"overdriven" a little bit. Can it cause any serious problems?



-- 
Sincerely,
 Yuri                          mailto:yuri at ostry.ru


_______________________________________________
time-nuts mailing list -- time-nuts at febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.



      

From wa1zms at att.net  Tue Dec 16 16:39:20 2008
From: wa1zms at att.net (wa1zms at att.net)
Date: Tue, 16 Dec 2008 16:39:20 +0000
Subject: [time-nuts] Close-in phase noise question...more info...
In-Reply-To: <49477D64.3010005@ghengineering.co.uk>
References: <mailman.392.1229368512.2499.time-nuts@febo.com>
	<49477D64.3010005@ghengineering.co.uk>
Message-ID: <121620081639.3390.4947D9B80003612A00000D3E22218675169B0A02D29B9B0EBF9C0396CE0E99@att.net>

First, thanks for the replies from all.


More info on the LO chain:

1) 5MHz Wenzel OCXO <--Custom Osc for me.
2) MSA-1105 buffer MMIC and lumped LPF
3) 5MHz to 10MHz 1N5711 diode based doubler
4) MSA-1105 buffer and lumped LPF
5) 10MHz to 20MHz 1N5711 diode based doubler
6) 20MHz BPF
7) 20MHz drives sampling detector inside surplus Frequency
West PLL block to lock 1320MHz cavity oscillator.
8) 1320MHz drives Frequency West SRD multiplier to 6.6GHz.
9) 6.6GHz to 39.6GHz Milliwave diode multiplier/amp/filter
10) 39.6GHz to 79.2GHz in varactor doubler
11) 79.2GHz to 158.4GHz in varactor doubler
12) 158.4GHz into x4 sub-harmonic mixer

So my question was based on best close-in phase
noise in LO chain going from 5MHz to 20MHz.
My MSA-1105 MMICs may be running near or just
into compression and I may need to adjust the
design gain stack-up.

-Brian





From jmfranke at cox.net  Tue Dec 16 16:47:01 2008
From: jmfranke at cox.net (John Franke)
Date: Tue, 16 Dec 2008 11:47:01 -0500
Subject: [time-nuts] CHU to QSY
References: <mailman.276.1229008237.2499.time-nuts@febo.com><BLU125-W49C47C4BE903FD7BACCE38CEF80@phx.gbl>
	<C2D5EC3402784785B73960E3B0433925@pc52>
Message-ID: <F62FDC672A7641DFAE7BE05743D3B9D5@youre7075dc078>

CHU TO QSY JANUARY 1ST
The CQ Newsroom reports: "Canadian time/frequency standard station CHU -- a 
fixture for decades on 7335 kHz -- will change frequency to 7850 kHz at 0000 
UTC on January 1, 2009. The move comes as a result of the International 
Telecommunication Union's decision in 2007 to expand the 40-meter ham band 
in Europe and Africa (Region I) to 7000-7200 kHz. It was previously 
7000-7100 kHz, with -- as every 40-meter DXer knows -- international 
broadcasting allocated from 7100-7300 kHz.

As part of the 40-meter expansion, the international broadcast band was 
shifted to 7200-7350 kHz. As broadcasters began relocating, CHU on 7335 
began experiencing significant interference. Thus, officials at Canada's 
National Research Council which operates CHU, decided to move the 
time/frequency standard station's transmissions to 7850 kHz as of the 
beginning of 2009. The complete NRC announcement (English version) is online 
at:

http://inms-ienm.nrc-cnrc.gc.ca/common_files/stories/chu/communique_e.pdf



From bruce.griffiths at xtra.co.nz  Tue Dec 16 20:09:56 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Wed, 17 Dec 2008 09:09:56 +1300
Subject: [time-nuts] RF transformers for distribution amplifier
In-Reply-To: <835725.40474.qm@web27101.mail.ukl.yahoo.com>
References: <835725.40474.qm@web27101.mail.ukl.yahoo.com>
Message-ID: <49480B14.7000504@xtra.co.nz>


Yuri

1v pp into 50 ohm shouldn't be near transformer saturation.
If the transformer dc current is too high distortion will increase
significantly.
Seeing you have so many, you can afford to test one of them to
destruction should that eventuate.
Just drive it from a suitable source with a series resistor and /or
attenuator to set the drive level and look at the output.
Use an oscilloscope and/or spectrum analyser if you have them.

Bruce

Robert Atkinson wrote:
> Hi Yuri,
> I don't know about thr transformers you have, but a useful source of a very usable triple 1:1 50R transformer is an old 10base2 Ethernet card (the type with a BNC) these cards have a standard design that calls for isolation. They also yield a 5 (or 12) volt to 9V isolated DC-DC converter.
> Robert G8RPI.
>
> --- On Tue, 16/12/08, Yuri Ostry <yuri at ostry.ru> wrote:
>
> From: Yuri Ostry <yuri at ostry.ru>
> Subject: [time-nuts] RF transformers for distribution amplifier
> To: time-nuts at febo.com
> Date: Tuesday, 16 December, 2008, 11:27 AM
>
> Hello,
>
> Just digged in my junkbox(es) in hope to find something to quickly
> build distribution amp for Rb module that I just received from
> fluke.l. Figured out that I'm pretty short in fast opamps, but found
> considerable quantity of Mini-Circuits TC1-6-75-1 SMT wideband
> transformers (same as sold now by someone on eBay for US $17.49 for
> lot of 200 as item #110259000213).
>
> Here is some more detailed specs that good people from Mini-Circuits
> provided a year or so ago....
>
>   
>> The P/N TC1-6-75-1 is a Mini-Circuits custom design for one of our
>> cust's. However, this model was made available for other customers
>> as well.
>>
>> The specs are as follow:
>> Frequency:  5 - 50 MHz
>> Impedance ratio:  1:1
>> Impedance:  75 ohms nominal
>> Insertion Loss:  0.5 dB maximum
>> Input Return Loss:  14 dB typical
>> Maximum RF Input Power:  15 mW
>> Operating temperature:  0 to 70 degrees C
>>
>> All electrical specs measured with 0 mA DC current
>>
>> Case style:  AT224
>> Pinout:  (same as TC1-1)
>> Primary dot = pin 6
>> Primary = pin 4
>> Secondary dot = pin 1
>> Secondary = pin 3
>> Not used = pin 2
>>     
>
>
> I'm in doubt... I'd like to get about 1 volt p-p on a 50 ohm load from
> amplifier outputs, and it looks like that this transformer may be
> "overdriven" a little bit. Can it cause any serious problems?
>
>
>
>   



From eb4apl at cembreros.jazztel.es  Tue Dec 16 23:14:19 2008
From: eb4apl at cembreros.jazztel.es (EB4APL)
Date: Wed, 17 Dec 2008 00:14:19 +0100
Subject: [time-nuts] OCXO info request
In-Reply-To: <49445702.7050006@arcor.de>
References: <mailman.1.1229169601.30901.time-nuts@febo.com>	<D480AC43450E4B03848DCCE08FADD4AD@DELL2350>	<49440A28.9030602@verizon.net>	<49445279.6040702@cembreros.jazztel.es>
	<49445702.7050006@arcor.de>
Message-ID: <4948364B.40609@cembreros.jazztel.es>

Adrian, I have found another reference, this oscillator is also used in 
the HP 5061a Cesium freq. standard:
http://www.leapsecond.com/museum/hp5061a/5061a.pdf

Best regards,
Ignacio

Adrian escribi?:
> Ignacio,
>
> for details check:
> http://www.ko4bb.com/cgi-bin/manuals.pl?dir=HP_Agilent/HP_-_105
> Early 105A/B's came with the 00105-6013 OCXO, as covered by the above 
> manual.
>
> Adrian
>
> EB4APL schrieb:
>   
>> Hi,
>> Since there is plenty of experience here, I want to locate info about an 
>> OCXO.  It is an HP 00105-6013, that probably came from a Rb or Cesium 
>> frequency standard.   Al pins and connectors are labeled with its 
>> function and even it has the crystal temp marked on the label.
>> TYA,
>> Ignacio
>>
>>     



From jacques at tiete.org  Tue Dec 16 23:20:22 2008
From: jacques at tiete.org (Jacques Tiete)
Date: Wed, 17 Dec 2008 00:20:22 +0100
Subject: [time-nuts] Build my own dist. amp ??
Message-ID: <D3CC17D0-C71B-4713-B9DF-95674B50097B@tiete.org>

Glenn for your info:
Thomson Grass Valley uses AD8055 amps in their recent analog  
distribution amps, 1 loop-thru and 8 outputs (with 4 x AD8055 and 2  
outputs per ic @ 75 ohm), modifying to 50 ohm seems to be  
straightforward.
These cards are not yet out of production, they are still being used  
for all kind of "glue" applications, eg. sync, de-embed_do something  
like add audio_re-embed, etc. and this in, for the rest, full digital  
installs SD or HD.
The circuit does not seem to be complicated, didn't look at the  
schematics yet but the power-supply seems to be well filtered.
Model nrs. are 8901, 8902, etc, the board is not that expensive but  
they need to be put in a "Gecko" frame = means very expensive... BTW:  
all Pro Broadcast equipment is made of pure gold you know ;-))
I'll try to test this card with some decent 5 or 10 Mhz signal (I'm  
still waiting for my T-Bolt from TAPR...).
http://www.grassvalley.com/docs/Ordering_Guides/modular/gecko/MOD-1014M-2/8901.pdf

Jacques.

Jacques Tiete
jacques at tiete.org
GSM: 32(0)499 99 83 78






From gwinn at raytheon.com  Tue Dec 16 23:54:29 2008
From: gwinn at raytheon.com (Joseph M Gwinn)
Date: Tue, 16 Dec 2008 18:54:29 -0500
Subject: [time-nuts] Sub Pico Second Phase logger
In-Reply-To: <4946EB83.6050005@xtra.co.nz>
Message-ID: <OF7DB14F63.A2A92232-ON85257521.007FFABB-85257521.00834508@mck.us.ray.com>

Bruce,


time-nuts-bounces at febo.com wrote on 12/15/2008 06:42:59 PM:

> Joe
> Joseph M Gwinn wrote:
> > Bruce,
> >
> >
> > time-nuts-bounces at febo.com [Bruce] wrote on 12/15/2008 04:56:26 PM:
> >
 
> >>>>> [snip]
> >>>>>
> >>>>>
> >>>>> 
> >>>>>> The only configuration for which it makes any sense is an 
inverting
> >>>>>> input amplifier with a finite input voltage offset.
> >>>>>>
> >>>>>>
> >>>>>> 
> >>>>> Why would non-inverting not work?  Both inputs source or sink bias 

> >>>>> currents, and non-inverting presents a very high impedance.
> >>>>>
> >>>>> 
> >>>> Non inverting amplifiers usually have lower noise and generally 
work 
> >>>> very well.
> >>>> 
> >>>> I was only trying to come up with a preamp circuit for which the
> >>>> comments in the Minicircuits application note on the effect of 
> >>>> amplifier input offset voltage made any sense.
> >>>>
> >>>> 
> >>> Ah.  It may be hopeless.
> >>>
> >>> My reading was that they were worried about bias currents from the 
amp 
> >>> flowing into the mixer and causing offsets, not amplifier offset 
voltages 
> >>> per se.  The amplifier offset voltage does not cause a mixer offset, 

> >>> and may be reduced by use of a chopper amp or very good balance.
> >>> 
> >
> > By the way, I've noticed that Tek TDS3012B oscilloscope inputs can 
cause 
> > offsets as well, again I assume from the bias currents.  The circuit 
has 
> > the scope input in parallel with the Agilent 34410A 6.5-digit 
voltmeter. 
> > With scope input set to DC, big effect.  Set to AC, small effect.  Set 
to 
> > Gnd, no effect.  (Input is not grounded, so voltmeter is still happy.) 

> > Didn't try changing the input volts/cm scale.  Anyway, I think that 
this 
> > effect is what the mystery app note was trying to say.  A bias current 

> > from the scope would cause a voltage offset that depended on the DC 
> > resistance through which the bias current flowed, the DC load of the 
mixer 
> > in this case.
> >
> > 
> However the proposed remedy has little or no effect on the errors caused
> by such bias currents (eg transistor base currents).
> The series resistor could be reduced to zero without effect on the mixer
> offset due to the bias current. However the preamp offset due to the
> source resistance would be reduced.

Hmm.  It may be simpler than that.  With the TDS3012B and 34410A connected 
in parallel across the IF output of a mixer, the bias currents from the 
TDS3012B developed a voltage across the mixer load resistor, and this 
voltage was sensed by the 34410A.  All the phase detector had to do was 
not short the bias current to ground.



> >>>> If we design our own PCB then the AD7760 series ADCs are another
> >>>> possible option.
> >>>> These have a built in differential input differential output 
amplifier.
> > 
> >>> Yes.  But aren't we trying to use commonly available soundcards?
> >>>
> >>>
> >>> 
> >> Ideally yes, but they all seem to have built in performance 
limitations.
> >> AFAIK the AP192 with its 4Vrms full scale balanced inputs with no
> >> variable gain preamps or +48V phantom supplies seems to be one of the
> >> best for this application.
> >> Its major drawback is that its a PCI card located within a noisy PC.
> >> 
> >
> > I think that there are many top-end firewire soundcards.  Whatever the 

> > music folk like the sound of would be a good place to start - 
musicians' 
> > well-trained hearing can be quite good.  At least above 20 Hz.
> >
> > Actually, the people that make the AP192 do have firewire and usb 
> > offerings:
> >
> > <http://www.m-audio.com/index.php?do=products.family&ID=recording>
> >
> > 
> 
> I've looked at all of the M-Audio offerings.
> The more expensive ones have built in preamps plus 48V phantom supplies,
> which can be switched off, however the presence of the switched +48V
> supply is perhaps an invitation to disaster.

Given that capacitance to ground is more benefit than problem in this 
application, I would be tempted to use a pair of back-to-back rectifier 
diodes as a clamp to protect the mixer IF output et al.  The 48 volt 
phantom supply will be short-circuit protected, so current will 
automatically limit.


> I've also looked at the specs for several other high end sound cards.
> Quite a few only have single ended inputs.
> Maybe, I should document the various cards and highlight their
> shortcomings etc for this application.

That would be very useful.

 
> >> The 4V rms input allows the mixer preamp to use devices like the THAT
> >> 1646 to drive the balanced sound card inputs without degrading the 
noise
> >> floor too much.
> >> 
> >
> > Or build an isolation amp with some gain, and kill two birds with one 
> > stone?
> >
> >
> > 
> A low noise isolation amplifier with a frequency response down to 1Hz or
> so without using a transformer may be difficult to do.

People do make low noise common-base RF amplifiers, but 1 Hz would yield 
some pretty large bypass capacitors, even if the flicker noise can be 
controlled well enough.  I would consider using ultracapacitors, which 
didn't exist until very recently, and of course have very large 
capacitance values.


> >> With a 1V rms full scale the noise floor degradation would be very
> >> obvious when using a THAT 1646 (equivalent devices are even noisier).
> >> It may be better to use a mixer preamp with a transformer coupled 
output
> >> stage using hybrid feedback to achieve a low frequency cutoff below 
1Hz
> >> together with low noise.
> >> 
> >
> > With a transformer, even if toroidal, keeping hum out may prove quite 
> > difficult.
> >
> > 
> High end (eg Lundahl LL1517) line output audio transformers come with mu
> metal screens and metal foil interwinding shields.

They don't pass 1 Hz very well. I bet the rolloff is ~20 Hz. 

Certainly one can build a VLF transformer, but it will be a project for 
sure, and the transformer may be quite large.



> >>>>>> 
> >>>>> The [5120A] paper is also worthwhile, and available on the web 
somewhere 
> >>>>> (don't recall where, but google found the pdf).  I had to read the 
patent 
> >>>>> multiple times to figure out what's going on.  The correlation 
> >>>>> approach is old as the hills, and only the digital phase detector 
was patentable.
> >>>>> 
> >>>> It may be feasible to achieve the same effect by purely digital 
means 
> >>>> at least for low sample rates where FIR filters with tens of 
thousands 
> >>>> of taps are feasible.
> >>>>
> >>>> 
> >>> It *is* feasible, and Sam Stein is doing it.  I've perhaps lost the 
thread 
> >>> here.
> >>>
> >>>
> >>> 
> >> No, I meant replace his 90 degree hybrids with a digital equivalent.
> >> 
> >
> > I believe that his 90-degree hybrids are already digital.
> I'm not convinced of that, if only because real time 10,000+ tap FIR
> filters at 30+MSPS are probably still impractical.

I'm not convinced that one needs a 10,000-tap FIR to achieve this, and Sam 
Stein is one smart fellow.  I recall some NASA patents from twenty years 
ago on how to get I+Q data from a single ADC, and while there was FIR 
processing of some kind, there were only maybe 8 or 16 taps.  And Tayloe 
(US patent 6,230,000) gets much the same effect with one resistor, four 
capacitors, an analog mux, and two differential amplifiers.

How accurately must the quadrature delay be achieved?  If I recall, the 
patent or paper implies that it need not be exact.

I also recall thinking that he could implement the quadrature delay 
digitally.  I don't recall the details, but it depended on cutting time up 
into one-second batches and processing each batch independently of the 
others.  I suppose one can use a FFT-Multiply-IFFT to do it directly.


Joe


From gwinn at raytheon.com  Wed Dec 17 00:07:16 2008
From: gwinn at raytheon.com (Joseph M Gwinn)
Date: Tue, 16 Dec 2008 19:07:16 -0500
Subject: [time-nuts] Sub Pico Second Phase logger
In-Reply-To: <4946DABF.1070903@xtra.co.nz>
Message-ID: <OF0C5D80D0.D9694F3F-ON85257521.00837AF8-85257522.00009AE7@mck.us.ray.com>

Bruce,


time-nuts-bounces at febo.com wrote on 12/15/2008 05:31:27 PM:

> Joseph M Gwinn wrote:
> > Bruce,
> >
> >
> > time-nuts-bounces at febo.com wrote on 12/15/2008 04:34:34 PM:
> >
[snip]
> > 
> >> I need to build a noise source to check the absolute level.
> >> Will use the amplified Johnson noise of a 150K resistor.
> >>
> >> By Allan deviation do you mean calculate it from the sequential 
96KSPS
> >> ADC output samples?
> >> 
> >
> > Yes, although some decimation may be needed to keep compute times 
under 
> > control, at least for the larger values of tau.
> >
> > 
> > 
> >> I can do this, but since the dominant noise source is white the Allan
> >> deviation will scale with the measurement bandwidth.
> >> 
> >
> > Would modified Allan deviation be better?
> >
> > I'm more interested in the general shape of the Allan curve than its 
> > absolute value, one issue being the effect of thermal variations in 
your 
> > laboratory dungeon.  We had speculated as to the relative size of 
thermal 
> > effects in these sound cards, and this would give us some idea.
> >
> >
> > Joe
> >
> > 
> 
> Joe
> 
> Modified ADEV, ADEV etc are possible, although the maximum usable record
> length probably depends more on the limits of Plotter and Windows 2K.
> 
> 
> I'll look into doing this.
> Real time filtering and decimation may be impractical, in the short term
> at least, as most signal processing libraries only process 16 bit 
samples.
> Most real time spectrum analysis programs are similarly afflicted in
> that they only process 16 bit samples.

I don't see why we would need realtime filtering.  Data reduction can be 
offline, so we ought to be able to use 32-bit or 64-bit arithmetic.

Given that we will inspect Allan Deviation data in a log-log plot, one can 
save much processing time by spacing the tau values to be computed 
uniformly in log tau.  I've played with this in Mathematica, and it does 
work and yields a large speedup factor.  It should also help with Plotter 
and Win2K limits.  One trick is to ensure that one computes each tau value 
at most once.  This check is needed because with close spacing, the round 
function will yield the same tau values multiple times for small values of 
tau.

Joe


From jmiles at pop.net  Wed Dec 17 00:53:06 2008
From: jmiles at pop.net (John Miles)
Date: Tue, 16 Dec 2008 16:53:06 -0800
Subject: [time-nuts] Close-in phase noise question...more info...
In-Reply-To: <121620081639.3390.4947D9B80003612A00000D3E22218675169B0A02D29B9B0EBF9C0396CE0E99@att.net>
Message-ID: <PKEGJHPHLLBACEOICCBJMEKEPNAB.jmiles@pop.net>

> More info on the LO chain:
>
> 1) 5MHz Wenzel OCXO <--Custom Osc for me.
> 2) MSA-1105 buffer MMIC and lumped LPF
> 3) 5MHz to 10MHz 1N5711 diode based doubler
> 4) MSA-1105 buffer and lumped LPF
> 5) 10MHz to 20MHz 1N5711 diode based doubler
> 6) 20MHz BPF

What kind of BPF?  A really narrow crystal filter would be nice here.  (You
have basically reproduced the 8568A/B's 20 MHz reference section.)

> 7) 20MHz drives sampling detector inside surplus Frequency
> West PLL block to lock 1320MHz cavity oscillator.

Sounds OK as long as the sampler loop's noise floor doesn't limit you.  I
haven't measured the in-band residual floor of any bricks but I'd be
surprised if an SRD multiplier wouldn't be quieter.

> 8) 1320MHz drives Frequency West SRD multiplier to 6.6GHz.

If I wanted to get to several GHz with what's in my junk box right now, I
would do what you did to get to 20 MHz, BPF it with a multipole crystal
filter, and then use a few more multiplier stages to get somewhere between
100 MHz and 1 GHz, a la the 8662A reference section, depending on the choice
of the next stage.

That VHF drive signal would go into either an HP 33002A or 33004A SRD
multiplier, or one of the Picosecond NLTL multipliers (e.g.,
http://www.picosecond.com/product/product.asp?prod_id=109 ) I picked up in
their fire sale when they shut down their fab.

> 9) 6.6GHz to 39.6GHz Milliwave diode multiplier/amp/filter
> 10) 39.6GHz to 79.2GHz in varactor doubler
> 11) 79.2GHz to 158.4GHz in varactor doubler
> 12) 158.4GHz into x4 sub-harmonic mixer

AFAIK the rest of the chain is fine.  I'd focus on getting rid of the brick
PLL, or at least taking pains to make sure that it's not the problem, before
worrying about the MMICs in your early stages.

Remember that there's no point in optimizing the PN of any one stage much
below the input-referred residual noise of the following stage.  MMICs, in
saturation or not, are pretty quiet.  Quieter than sampler loops anyway.

-- john, KE5FX



From hmurray at megapathdsl.net  Wed Dec 17 01:19:41 2008
From: hmurray at megapathdsl.net (Hal Murray)
Date: Tue, 16 Dec 2008 17:19:41 -0800
Subject: [time-nuts] Close-in phase noise question...more info...
In-Reply-To: Your message of "Tue, 16 Dec 2008 16:53:06 PST."
	<PKEGJHPHLLBACEOICCBJMEKEPNAB.jmiles@pop.net> 
Message-ID: <20081217011942.970DEBCD7@ip-64-139-1-69.sjc.megapath.net>


>> 1) 5MHz Wenzel OCXO <--Custom Osc for me.
[snip multiplier chain]

> What kind of BPF?  A really narrow crystal filter would be nice here.
> (You have basically reproduced the 8568A/B's 20 MHz reference
> section.)

What happens when I put a crystal in series with a crystal filter?

I'd expect it would be hard to tune them accurately enough so things would 
end up working on the slope of the filter.

Maybe I'm missing the decimal point.  What's the bandwidth of a crystal 
filter relative to the spectrum out of the same crystal used as an osc?


-- 
These are my opinions, not necessarily my employer's.  I hate spam.





From bruce.griffiths at xtra.co.nz  Wed Dec 17 01:43:29 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Wed, 17 Dec 2008 14:43:29 +1300
Subject: [time-nuts] Sub Pico Second Phase logger
In-Reply-To: <OF7DB14F63.A2A92232-ON85257521.007FFABB-85257521.00834508@mck.us.ray.com>
References: <OF7DB14F63.A2A92232-ON85257521.007FFABB-85257521.00834508@mck.us.ray.com>
Message-ID: <49485941.6080406@xtra.co.nz>

Joe

Joseph M Gwinn wrote:
> Bruce,
>
>
> time-nuts-bounces at febo.com wrote on 12/15/2008 06:42:59 PM:
>
>   
>> Joe
>> Joseph M Gwinn wrote:
>>     
>>> Bruce,
>>>
>>>
>>> time-nuts-bounces at febo.com [Bruce] wrote on 12/15/2008 04:56:26 PM:
>>>
>>>       
>  
>   
>>>>>>> [snip]
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>               
>>>>>>>> The only configuration for which it makes any sense is an 
>>>>>>>>                 
> inverting
>   
>>>>>>>> input amplifier with a finite input voltage offset.
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>                 
>>>>>>> Why would non-inverting not work?  Both inputs source or sink bias 
>>>>>>>               
>
>   
>>>>>>> currents, and non-inverting presents a very high impedance.
>>>>>>>
>>>>>>>
>>>>>>>               
>>>>>> Non inverting amplifiers usually have lower noise and generally 
>>>>>>             
> work 
>   
>>>>>> very well.
>>>>>>
>>>>>> I was only trying to come up with a preamp circuit for which the
>>>>>> comments in the Minicircuits application note on the effect of 
>>>>>> amplifier input offset voltage made any sense.
>>>>>>
>>>>>>
>>>>>>             
>>>>> Ah.  It may be hopeless.
>>>>>
>>>>> My reading was that they were worried about bias currents from the 
>>>>>           
> amp 
>   
>>>>> flowing into the mixer and causing offsets, not amplifier offset 
>>>>>           
> voltages 
>   
>>>>> per se.  The amplifier offset voltage does not cause a mixer offset, 
>>>>>           
>
>   
>>>>> and may be reduced by use of a chopper amp or very good balance.
>>>>>
>>>>>           
>>> By the way, I've noticed that Tek TDS3012B oscilloscope inputs can 
>>>       
> cause 
>   
>>> offsets as well, again I assume from the bias currents.  The circuit 
>>>       
> has 
>   
>>> the scope input in parallel with the Agilent 34410A 6.5-digit 
>>>       
> voltmeter. 
>   
>>> With scope input set to DC, big effect.  Set to AC, small effect.  Set 
>>>       
> to 
>   
>>> Gnd, no effect.  (Input is not grounded, so voltmeter is still happy.) 
>>>       
>
>   
>>> Didn't try changing the input volts/cm scale.  Anyway, I think that 
>>>       
> this 
>   
>>> effect is what the mystery app note was trying to say.  A bias current 
>>>       
>
>   
>>> from the scope would cause a voltage offset that depended on the DC 
>>> resistance through which the bias current flowed, the DC load of the 
>>>       
> mixer 
>   
>>> in this case.
>>>
>>>
>>>       
>> However the proposed remedy has little or no effect on the errors caused
>> by such bias currents (eg transistor base currents).
>> The series resistor could be reduced to zero without effect on the mixer
>> offset due to the bias current. However the preamp offset due to the
>> source resistance would be reduced.
>>     
>
> Hmm.  It may be simpler than that.  With the TDS3012B and 34410A connected 
> in parallel across the IF output of a mixer, the bias currents from the 
> TDS3012B developed a voltage across the mixer load resistor, and this 
> voltage was sensed by the 34410A.  All the phase detector had to do was 
> not short the bias current to ground.
>
>
>   
AC coupling?
>   
>>>>>> If we design our own PCB then the AD7760 series ADCs are another
>>>>>> possible option.
>>>>>> These have a built in differential input differential output 
>>>>>>             
> amplifier.
>   
>>>>> Yes.  But aren't we trying to use commonly available soundcards?
>>>>>
>>>>>
>>>>>
>>>>>           
>>>> Ideally yes, but they all seem to have built in performance 
>>>>         
> limitations.
>   
>>>> AFAIK the AP192 with its 4Vrms full scale balanced inputs with no
>>>> variable gain preamps or +48V phantom supplies seems to be one of the
>>>> best for this application.
>>>> Its major drawback is that its a PCI card located within a noisy PC.
>>>>
>>>>         
>>> I think that there are many top-end firewire soundcards.  Whatever the 
>>>       
>
>   
>>> music folk like the sound of would be a good place to start - 
>>>       
> musicians' 
>   
>>> well-trained hearing can be quite good.  At least above 20 Hz.
>>>
>>> Actually, the people that make the AP192 do have firewire and usb 
>>> offerings:
>>>
>>> <http://www.m-audio.com/index.php?do=products.family&ID=recording>
>>>
>>>
>>>       
>> I've looked at all of the M-Audio offerings.
>> The more expensive ones have built in preamps plus 48V phantom supplies,
>> which can be switched off, however the presence of the switched +48V
>> supply is perhaps an invitation to disaster.
>>     
>
> Given that capacitance to ground is more benefit than problem in this 
> application, I would be tempted to use a pair of back-to-back rectifier 
> diodes as a clamp to protect the mixer IF output et al.  The 48 volt 
> phantom supply will be short-circuit protected, so current will 
> automatically limit.
>
>   
A pair of coupling capacitors at the preamp output combined with clamp
diodes to the amplifier power supply rails would work well even if the
+48V cant be switched off.
The +48V appears between the balanced pair conductors and ground.
Unfortunately the power available  from the phantom supply may not be
sufficient to power the mixer preamp.
>   
>> I've also looked at the specs for several other high end sound cards.
>> Quite a few only have single ended inputs.
>> Maybe, I should document the various cards and highlight their
>> shortcomings etc for this application.
>>     
>
> That would be very useful.
>   
I'll start on this shortly.
>  
>   
>>>> The 4V rms input allows the mixer preamp to use devices like the THAT
>>>> 1646 to drive the balanced sound card inputs without degrading the 
>>>>         
> noise
>   
>>>> floor too much.
>>>>
>>>>         
>>> Or build an isolation amp with some gain, and kill two birds with one 
>>> stone?
>>>
>>>
>>>
>>>       
>> A low noise isolation amplifier with a frequency response down to 1Hz or
>> so without using a transformer may be difficult to do.
>>     
>
> People do make low noise common-base RF amplifiers, but 1 Hz would yield 
> some pretty large bypass capacitors, even if the flicker noise can be 
> controlled well enough.  I would consider using ultracapacitors, which 
> didn't exist until very recently, and of course have very large 
> capacitance values.
>
>   
A CB stage probably isnt optimum for the mixer preamp so that lower
value caps can be used provided that they effectively short the
amplifier input resistor Johnson noise at the frequencies of interest.
>   
>>>> With a 1V rms full scale the noise floor degradation would be very
>>>> obvious when using a THAT 1646 (equivalent devices are even noisier).
>>>> It may be better to use a mixer preamp with a transformer coupled 
>>>>         
> output
>   
>>>> stage using hybrid feedback to achieve a low frequency cutoff below 
>>>>         
> 1Hz
>   
>>>> together with low noise.
>>>>
>>>>         
>>> With a transformer, even if toroidal, keeping hum out may prove quite 
>>> difficult.
>>>
>>>
>>>       
>> High end (eg Lundahl LL1517) line output audio transformers come with mu
>> metal screens and metal foil interwinding shields.
>>     
>
> They don't pass 1 Hz very well. I bet the rolloff is ~20 Hz. 
>
>   

When driven conventionally the transformer cutoff is around 20Hz,
however if one uses the appropriate driver with a controlled negative
output R to cancel the transformer primary internal winding resistance,
the low frequency response can be extended significantly. This also
reduces the low frequency distortion.
However individual adjustment of driver to suit transformer is required
and tracking the winding resistance over temperature may be an issue.

> Certainly one can build a VLF transformer, but it will be a project for 
> sure, and the transformer may be quite large.
>
>   
The transformers only weigh about 65g.

It may be simpler just to select a mixer for which the IF ground can be
isolated from the RF and IF grounds.
However a preamp with a transformer output may be useful if one uses a
mixer where all the grounds are connected together by the package.
>
>   
>>>>>>> The [5120A] paper is also worthwhile, and available on the web 
>>>>>>>               
> somewhere 
>   
>>>>>>> (don't recall where, but google found the pdf).  I had to read the 
>>>>>>>               
> patent 
>   
>>>>>>> multiple times to figure out what's going on.  The correlation 
>>>>>>> approach is old as the hills, and only the digital phase detector 
>>>>>>>               
> was patentable.
>   
>>>>>> It may be feasible to achieve the same effect by purely digital 
>>>>>>             
> means 
>   
>>>>>> at least for low sample rates where FIR filters with tens of 
>>>>>>             
> thousands 
>   
>>>>>> of taps are feasible.
>>>>>>
>>>>>>
>>>>>>             
>>>>> It *is* feasible, and Sam Stein is doing it.  I've perhaps lost the 
>>>>>           
> thread 
>   
>>>>> here.
>>>>>
>>>>>
>>>>>
>>>>>           
>>>> No, I meant replace his 90 degree hybrids with a digital equivalent.
>>>>
>>>>         
>>> I believe that his 90-degree hybrids are already digital.
>>>       
>> I'm not convinced of that, if only because real time 10,000+ tap FIR
>> filters at 30+MSPS are probably still impractical.
>>     
>
> I'm not convinced that one needs a 10,000-tap FIR to achieve this, and Sam 
> Stein is one smart fellow.  I recall some NASA patents from twenty years 
> ago on how to get I+Q data from a single ADC, and while there was FIR 
> processing of some kind, there were only maybe 8 or 16 taps.  And Tayloe 
> (US patent 6,230,000) gets much the same effect with one resistor, four 
> capacitors, an analog mux, and two differential amplifiers.
>
>   
I have read similar papers from that era on radar signal processing.
They either used a Hilbert transform or a pair of digital filters whose
outputs were in phase quadrature.
The quadrature accuracy for a given bandwidth depends on the the number
of taps.
The beat frequencies (in a dual mixer system) won't match exactly and
some correction for the resultant phase shift errors will need to be made.
This may be less of a problem when the 2 beat frequency signals are
identical in frequency and just differ in phase.
> How accurately must the quadrature delay be achieved?  If I recall, the 
> patent or paper implies that it need not be exact.
>
> I also recall thinking that he could implement the quadrature delay 
> digitally.  I don't recall the details, but it depended on cutting time up 
> into one-second batches and processing each batch independently of the 
> others.  I suppose one can use a FFT-Multiply-IFFT to do it directly.
>
>
> Joe
>
>
>   
Bruce


From bruce.griffiths at xtra.co.nz  Wed Dec 17 02:05:55 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Wed, 17 Dec 2008 15:05:55 +1300
Subject: [time-nuts] Sub Pico Second Phase logger
In-Reply-To: <OF0C5D80D0.D9694F3F-ON85257521.00837AF8-85257522.00009AE7@mck.us.ray.com>
References: <OF0C5D80D0.D9694F3F-ON85257521.00837AF8-85257522.00009AE7@mck.us.ray.com>
Message-ID: <49485E83.4070205@xtra.co.nz>

Joseph M Gwinn wrote:
> Bruce,
>
>
> time-nuts-bounces at febo.com wrote on 12/15/2008 05:31:27 PM:
>
>   
>> Joseph M Gwinn wrote:
>>     
>>> Bruce,
>>>
>>>
>>> time-nuts-bounces at febo.com wrote on 12/15/2008 04:34:34 PM:
>>>
>>>       
> [snip]
>   
>>>> I need to build a noise source to check the absolute level.
>>>> Will use the amplified Johnson noise of a 150K resistor.
>>>>
>>>> By Allan deviation do you mean calculate it from the sequential 
>>>>         
> 96KSPS
>   
>>>> ADC output samples?
>>>>
>>>>         
>>> Yes, although some decimation may be needed to keep compute times 
>>>       
> under 
>   
>>> control, at least for the larger values of tau.
>>>
>>>
>>>
>>>       
>>>> I can do this, but since the dominant noise source is white the Allan
>>>> deviation will scale with the measurement bandwidth.
>>>>
>>>>         
>>> Would modified Allan deviation be better?
>>>
>>> I'm more interested in the general shape of the Allan curve than its 
>>> absolute value, one issue being the effect of thermal variations in 
>>>       
> your 
>   
>>> laboratory dungeon.  We had speculated as to the relative size of 
>>>       
> thermal 
>   
>>> effects in these sound cards, and this would give us some idea.
>>>
>>>
>>> Joe
>>>
>>>
>>>       
>> Joe
>>
>> Modified ADEV, ADEV etc are possible, although the maximum usable record
>> length probably depends more on the limits of Plotter and Windows 2K.
>>
>>
>> I'll look into doing this.
>> Real time filtering and decimation may be impractical, in the short term
>> at least, as most signal processing libraries only process 16 bit 
>>     
> samples.
>   
>> Most real time spectrum analysis programs are similarly afflicted in
>> that they only process 16 bit samples.
>>     
>
> I don't see why we would need realtime filtering.  Data reduction can be 
> offline, so we ought to be able to use 32-bit or 64-bit arithmetic.
>
> Given that we will inspect Allan Deviation data in a log-log plot, one can 
> save much processing time by spacing the tau values to be computed 
> uniformly in log tau.  I've played with this in Mathematica, and it does 
> work and yields a large speedup factor.  It should also help with Plotter 
> and Win2K limits.  One trick is to ensure that one computes each tau value 
> at most once.  This check is needed because with close spacing, the round 
> function will yield the same tau values multiple times for small values of 
> tau.
>
> Joe
>
>   
Joe

Real time processing certainly isn't required to characterise the
performance.
However some may be tempted to do this, its probably possible with a
sufficently fast machine.
I was just highlighting a problem with some available signal processing
libraries which may have been developed before sound cards with
resolutions of more than 16 bits became available.
Some (perhaps most) real time spectrum display software also has this
problem (eg baudline, Virtins etc).

It isnt necessary to use a pair of mixers and an offset source to
characterise the sound card, driving both sound card inputs from the
same audio source should suffice.
The audio source need not have low ultra low distortion (the IF output
signals in a dual mixer system wont have ultra low distortion) or very
high frequency stability ( the IF output signals in a dual mixer system
wont necessarily have particularly high frequency stability).

A standard RC audio oscillator with distortion lower than 1% or so
should suffice.
At least the resultant frequency fluctuations should thoroughly exercise
the phase extraction algorithms.

Another option would be to low pass filter the output of a divider.
Using a sound card to generate the test signal is also possible but it
can potentially introduce extraneous noise and other artifacts such as
phase truncation spurs.

Bruce


From jmiles at pop.net  Wed Dec 17 02:13:42 2008
From: jmiles at pop.net (John Miles)
Date: Tue, 16 Dec 2008 18:13:42 -0800
Subject: [time-nuts] Close-in phase noise question...more info...
In-Reply-To: <20081217011942.970DEBCD7@ip-64-139-1-69.sjc.megapath.net>
Message-ID: <PKEGJHPHLLBACEOICCBJKEKIPNAB.jmiles@pop.net>


> Maybe I'm missing the decimal point.  What's the bandwidth of a crystal
> filter relative to the spectrum out of the same crystal used as an osc?
>

The oscillator's noise floor itself is superb, near -180 dBc/Hz beyond 1
kHz.  That is only true until you do something with it.  The idea behind the
crystal filters is to get rid of the broadband noise introduced by the
buffers and multipliers.

You don't put the crystal directly in series with the oscillator, but rather
after various multiplier stages.  See the HP note "Generation of low phase
noise microwave signals" at
http://www.ke5fx.com/Scherer_Low_PN_Signal_Generation.pdf , especially page
23.

The additional filtering won't necessarily solve Brian's problem of
minimizing phase noise at circa 1 KHz from a 630 GHz carrier, though.  That
is beyond anything I have tinkered with.

-- john, KE5FX



From gwinn at raytheon.com  Wed Dec 17 02:19:12 2008
From: gwinn at raytheon.com (Joseph M Gwinn)
Date: Tue, 16 Dec 2008 21:19:12 -0500
Subject: [time-nuts] Sub Pico Second Phase logger
In-Reply-To: <49485941.6080406@xtra.co.nz>
Message-ID: <OF6A6C60C1.F12961BF-ON85257522.000A56EB-85257522.000CAF0F@mck.us.ray.com>

Bruce,


time-nuts-bounces at febo.com wrote on 12/16/2008 08:43:29 PM:

> Joe
> 
> Joseph M Gwinn wrote:
> > Bruce,
> >
> >
> > time-nuts-bounces at febo.com wrote on 12/15/2008 06:42:59 PM:
> >
[snip]
> >>>
> >>> 
> >> However the proposed remedy has little or no effect on the errors 
caused
> >> by such bias currents (eg transistor base currents).
> >> The series resistor could be reduced to zero without effect on the 
mixer
> >> offset due to the bias current. However the preamp offset due to the
> >> source resistance would be reduced.
> >> 
> >
> > Hmm.  It may be simpler than that.  With the TDS3012B and 34410A 
connected 
> > in parallel across the IF output of a mixer, the bias currents from 
the 
> > TDS3012B developed a voltage across the mixer load resistor, and this 
> > voltage was sensed by the 34410A.  All the phase detector hadto do was 

> > not short the bias current to ground.
> >
> >
> > 
> AC coupling?

At the expense of phase shifts and temperature sensitivity, but yes.

And it makes it hard to sense a DC signal, if that's the intent.


 

> >>>> 
> >>> I think that there are many top-end firewire soundcards.  Whatever 
the 
> >>> music folk like the sound of would be a good place to start - 
musicians' 
> >>> well-trained hearing can be quite good.  At least above 20 Hz.
> >>>
> >>> Actually, the people that make the AP192 do have firewire and usb 
> >>> offerings:
> >>>
> >>> <http://www.m-audio.com/index.php?do=products.family&ID=recording>
> >>>
> >>>
> >>> 
> >> I've looked at all of the M-Audio offerings.
> >> The more expensive ones have built in preamps plus 48V phantom 
supplies,
> >> which can be switched off, however the presence of the switched +48V
> >> supply is perhaps an invitation to disaster.
> >> 
> >
> > Given that capacitance to ground is more benefit than problem in this 
> > application, I would be tempted to use a pair of back-to-back 
rectifier 
> > diodes as a clamp to protect the mixer IF output et al.  The 48 volt 
> > phantom supply will be short-circuit protected, so current will 
> > automatically limit.
> >
> > 
> A pair of coupling capacitors at the preamp output combined with clamp
> diodes to the amplifier power supply rails would work well even if the
> +48V can't be switched off.
> The +48V appears between the balanced pair conductors and ground.
> Unfortunately the power available  from the phantom supply may not be
> sufficient to power the mixer preamp.

OK.  The power limit does make protection easy.  I gather that the limit 
is a few milliamps, so even a 1N4148 would work.

 
> >> I've also looked at the specs for several other high end sound cards.
> >> Quite a few only have single ended inputs.
> >> Maybe, I should document the various cards and highlight their
> >> shortcomings etc for this application.
> >> 
> >
> > That would be very useful.
> > 
> I'll start on this shortly.

Thanks.


> >>>> The 4V rms input allows the mixer preamp to use devices like the 
THAT
> >>>> 1646 to drive the balanced sound card inputs without degrading the 
> >>>> noise floor too much.
> >>>>
> >>>> 
> >>> Or build an isolation amp with some gain, and kill two birds with 
one 
> >>> stone?
> >>>
> >>>
> >>>
> >>> 
> >> A low noise isolation amplifier with a frequency response down to 1Hz 
or
> >> so without using a transformer may be difficult to do.
> >> 
> >
> > People do make low noise common-base RF amplifiers, but 1 Hz would 
yield 
> > some pretty large bypass capacitors, even if the flicker noise can be 
> > controlled well enough.  I would consider using ultracapacitors, which 

> > didn't exist until very recently, and of course have very large 
> > capacitance values.
> >
> > 
> A CB stage probably isn't optimum for the mixer preamp so that lower
> value caps can be used provided that they effectively short the
> amplifier input resistor Johnson noise at the frequencies of interest.

But is a CB stage adequate?  Elimination of hum pickup is worth a lot.


> >>>> With a 1V rms full scale the noise floor degradation would be very
> >>>> obvious when using a THAT 1646 (equivalent devices are even 
noisier).
> >>>> It may be better to use a mixer preamp with a transformer coupled 
output
> >>>> stage using hybrid feedback to achieve a low frequency cutoff below 

> >>>> 1Hz together with low noise.
> >>>>
> >>>> 
> >>> With a transformer, even if toroidal, keeping hum out may prove 
quite 
> >>> difficult.
> >>>
> >>>
> >>> 
> >> High end (eg Lundahl LL1517) line output audio transformers come with 
mu
> >> metal screens and metal foil interwinding shields.
> >> 
> >
> > They don't pass 1 Hz very well. I bet the rolloff is ~20 Hz. 
> >
> > 
> 
> When driven conventionally the transformer cutoff is around 20Hz,
> however if one uses the appropriate driver with a controlled negative
> output R to cancel the transformer primary internal winding resistance,
> the low frequency response can be extended significantly. This also
> reduces the low frequency distortion.
> However individual adjustment of driver to suit transformer is required
> and tracking the winding resistance over temperature may be an issue.

That would certainly work.  See next.

 
> > Certainly one can build a VLF transformer, but it will be a project 
for 
> > sure, and the transformer may be quite large.
> >
> > 
> The transformers only weigh about 65g.

This weight estimate assumes the negative resistance circuit I assume, the 
intent being to allow use of the Lundahl LL1517 transformer.

You might be interested in the following article:  "A Broadband Active 
Antenna for ELF Magnetic Fields" by John F. Sutton and G. Craig Spaniol" 
in Physics Essays March 1993, Vol 6, #1, 1993.  The negative-impedance 
trick is expanded upon.  Sutton also has some US patents on this.  US 
patent 5,296,866 covers the antenna, but is hard to understand without the 
article.


> It may be simpler just to select a mixer for which the IF ground can be
> isolated from the RF and IF grounds.
> However a preamp with a transformer output may be useful if one uses a
> mixer where all the grounds are connected together by the package.

It has to be far easier to select the right mixer than to deal with a 1 Hz 
transformer.  And cheaper.

 

> >>>>>
> >>>>> 
> >>>> No, I meant replace his 90 degree hybrids with a digital 
equivalent.
> >>>>
> >>>> 
> >>> I believe that his 90-degree hybrids are already digital.
> >>> 
> >> I'm not convinced of that, if only because real time 10,000+ tap FIR
> >> filters at 30+MSPS are probably still impractical.
> >> 
> >
> > I'm not convinced that one needs a 10,000-tap FIR to achieve this, and 
Sam 
> > Stein is one smart fellow.  I recall some NASA patents from twenty 
years 
> > ago on how to get I+Q data from a single ADC, and while there was FIR 
> > processing of some kind, there were only maybe 8 or 16 taps. And 
Tayloe 
> > (US patent 6,230,000) gets much the same effect with one resistor, 
four 
> > capacitors, an analog mux, and two differential amplifiers.
> >
> > 
> I have read similar papers from that era on radar signal processing.
> They either used a Hilbert transform or a pair of digital filters whose
> outputs were in phase quadrature.
> The quadrature accuracy for a given bandwidth depends on the the number
> of taps.
> The beat frequencies (in a dual mixer system) won't match exactly and
> some correction for the resultant phase shift errors will need 
> to be made.
> This may be less of a problem when the 2 beat frequency signals are
> identical in frequency and just differ in phase.

So long as we know the exact frequency, even if it isn't the exact desired 
frequency, all may be well.

Joe



From wa1zms at att.net  Wed Dec 17 03:11:30 2008
From: wa1zms at att.net (wa1zms at att.net)
Date: Tue, 16 Dec 2008 22:11:30 -0500
Subject: [time-nuts] Close-in phase noise (long reply)
In-Reply-To: <PKEGJHPHLLBACEOICCBJMEKEPNAB.jmiles@pop.net>
Message-ID: <FBEDKEIEMDPKGDDCPGNCMEHIEAAA.wa1zms@att.net>

John-

The BPFs in the 5 to 20MHz chain are just 7-pole LC
filters with the goal of trying to keep any other
harmonics other than the desired at least -50dBc.
Xtal filters would be the better choice, no doubt.

The -50dBc level is clearly not the best
that one could get, but was enough for an earlier
240GHz project. I just used the same OCXOs and early
stages of multipliers to get the latest system running
on 630GHz.

In the 241GHz system, I ended up building a direct
frequency synthesizer to get 110MHz from a 10MHz
drive signal.  At the time, the Freq West PLL
blocks I used wanted a VHF signal to drive
the sampling detector to phase lock the L-band
cavity VCO. The original Freq West units used 5th OT
xtals for the commercial applications.

By later experimentation, I found that
the same sampling detector would also work with a
much lower frequency reference and still lock the
loop. The risk however is that the PLL might lock
on the wrong harmonic of the reference (i.e.: value of N)
or can have higher reference spur levels since the
PLL was designed assuming a VHF reference and not an
HF reference frequency. But this is not a commercial
design project, and I can live with a difficult alignment
procedure or initial power-up PLL lock troubles.

But all this aside, my efforts are currently aimed at
best close-in noise within the first 1KHz of BW around
the carrier.

The PLL bricks all seem to have several kHz of loop BW,
so my close-in noise going from 20MHz to 1320MHz should
be only slightly worse than 20Log(n), with n=66 in my case.
But I'm not ruling out the chance of 1/f noise (or similar)
showing up from the sampling detector or some other yet-to-be
determined source.

However my focus is currently on the 5MHz to 20MHz portion
of the LO chain and to be sure the gain stages are not
running near compression. I do still agree with your
earlier comment about getting the most from that portion
of the chain.

-Brian, WA1ZMS

-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com]On
Behalf Of John Miles
Sent: Tuesday, December 16, 2008 7:53 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Close-in phase noise question...more info...


> More info on the LO chain:
>
> 1) 5MHz Wenzel OCXO <--Custom Osc for me.
> 2) MSA-1105 buffer MMIC and lumped LPF
> 3) 5MHz to 10MHz 1N5711 diode based doubler
> 4) MSA-1105 buffer and lumped LPF
> 5) 10MHz to 20MHz 1N5711 diode based doubler
> 6) 20MHz BPF

What kind of BPF?  A really narrow crystal filter would be nice here.  (You
have basically reproduced the 8568A/B's 20 MHz reference section.)

> 7) 20MHz drives sampling detector inside surplus Frequency
> West PLL block to lock 1320MHz cavity oscillator.

Sounds OK as long as the sampler loop's noise floor doesn't limit you.  I
haven't measured the in-band residual floor of any bricks but I'd be
surprised if an SRD multiplier wouldn't be quieter.

> 8) 1320MHz drives Frequency West SRD multiplier to 6.6GHz.

If I wanted to get to several GHz with what's in my junk box right now, I
would do what you did to get to 20 MHz, BPF it with a multipole crystal
filter, and then use a few more multiplier stages to get somewhere between
100 MHz and 1 GHz, a la the 8662A reference section, depending on the choice
of the next stage.

That VHF drive signal would go into either an HP 33002A or 33004A SRD
multiplier, or one of the Picosecond NLTL multipliers (e.g.,
http://www.picosecond.com/product/product.asp?prod_id=109 ) I picked up in
their fire sale when they shut down their fab.

> 9) 6.6GHz to 39.6GHz Milliwave diode multiplier/amp/filter
> 10) 39.6GHz to 79.2GHz in varactor doubler
> 11) 79.2GHz to 158.4GHz in varactor doubler
> 12) 158.4GHz into x4 sub-harmonic mixer

AFAIK the rest of the chain is fine.  I'd focus on getting rid of the brick
PLL, or at least taking pains to make sure that it's not the problem, before
worrying about the MMICs in your early stages.

Remember that there's no point in optimizing the PN of any one stage much
below the input-referred residual noise of the following stage.  MMICs, in
saturation or not, are pretty quiet.  Quieter than sampler loops anyway.

-- john, KE5FX


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From bruce.griffiths at xtra.co.nz  Wed Dec 17 03:21:55 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Wed, 17 Dec 2008 16:21:55 +1300
Subject: [time-nuts] Sub Pico Second Phase logger
In-Reply-To: <OF6A6C60C1.F12961BF-ON85257522.000A56EB-85257522.000CAF0F@mck.us.ray.com>
References: <OF6A6C60C1.F12961BF-ON85257522.000A56EB-85257522.000CAF0F@mck.us.ray.com>
Message-ID: <49487053.8040300@xtra.co.nz>

Joe

Joseph M Gwinn wrote:
> Bruce,
>
>
> time-nuts-bounces at febo.com wrote on 12/16/2008 08:43:29 PM:
>
>   
>> Joe
>>
>> Joseph M Gwinn wrote:
>>     
>>> Bruce,
>>>
>>>
>>> time-nuts-bounces at febo.com wrote on 12/15/2008 06:42:59 PM:
>>>
>>>       
> [snip]
>   
>>>>>           
>>>> However the proposed remedy has little or no effect on the errors 
>>>>         
> caused
>   
>>>> by such bias currents (eg transistor base currents).
>>>> The series resistor could be reduced to zero without effect on the 
>>>>         
> mixer
>   
>>>> offset due to the bias current. However the preamp offset due to the
>>>> source resistance would be reduced.
>>>>
>>>>         
>>> Hmm.  It may be simpler than that.  With the TDS3012B and 34410A 
>>>       
> connected 
>   
>>> in parallel across the IF output of a mixer, the bias currents from 
>>>       
> the 
>   
>>> TDS3012B developed a voltage across the mixer load resistor, and this 
>>> voltage was sensed by the 34410A.  All the phase detector hadto do was 
>>>       
>
>   
>>> not short the bias current to ground.
>>>
>>>
>>>
>>>       
>> AC coupling?
>>     
>
> At the expense of phase shifts and temperature sensitivity, but yes.
>
> And it makes it hard to sense a DC signal, if that's the intent.
>
>
>  
>
>   
>>>>> I think that there are many top-end firewire soundcards.  Whatever 
>>>>>           
> the 
>   
>>>>> music folk like the sound of would be a good place to start - 
>>>>>           
> musicians' 
>   
>>>>> well-trained hearing can be quite good.  At least above 20 Hz.
>>>>>
>>>>> Actually, the people that make the AP192 do have firewire and usb 
>>>>> offerings:
>>>>>
>>>>> <http://www.m-audio.com/index.php?do=products.family&ID=recording>
>>>>>
>>>>>
>>>>>
>>>>>           
>>>> I've looked at all of the M-Audio offerings.
>>>> The more expensive ones have built in preamps plus 48V phantom 
>>>>         
> supplies,
>   
>>>> which can be switched off, however the presence of the switched +48V
>>>> supply is perhaps an invitation to disaster.
>>>>
>>>>         
>>> Given that capacitance to ground is more benefit than problem in this 
>>> application, I would be tempted to use a pair of back-to-back 
>>>       
> rectifier 
>   
>>> diodes as a clamp to protect the mixer IF output et al.  The 48 volt 
>>> phantom supply will be short-circuit protected, so current will 
>>> automatically limit.
>>>
>>>
>>>       
>> A pair of coupling capacitors at the preamp output combined with clamp
>> diodes to the amplifier power supply rails would work well even if the
>> +48V can't be switched off.
>> The +48V appears between the balanced pair conductors and ground.
>> Unfortunately the power available  from the phantom supply may not be
>> sufficient to power the mixer preamp.
>>     
>
> OK.  The power limit does make protection easy.  I gather that the limit 
> is a few milliamps, so even a 1N4148 would work.
>
>  
>   
>>>> I've also looked at the specs for several other high end sound cards.
>>>> Quite a few only have single ended inputs.
>>>> Maybe, I should document the various cards and highlight their
>>>> shortcomings etc for this application.
>>>>
>>>>         
>>> That would be very useful.
>>>
>>>       
>> I'll start on this shortly.
>>     
>
> Thanks.
>
>
>   
>>>>>> The 4V rms input allows the mixer preamp to use devices like the 
>>>>>>             
> THAT
>   
>>>>>> 1646 to drive the balanced sound card inputs without degrading the 
>>>>>> noise floor too much.
>>>>>>
>>>>>>
>>>>>>             
>>>>> Or build an isolation amp with some gain, and kill two birds with 
>>>>>           
> one 
>   
>>>>> stone?
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>           
>>>> A low noise isolation amplifier with a frequency response down to 1Hz 
>>>>         
> or
>   
>>>> so without using a transformer may be difficult to do.
>>>>
>>>>         
>>> People do make low noise common-base RF amplifiers, but 1 Hz would 
>>>       
> yield 
>   
>>> some pretty large bypass capacitors, even if the flicker noise can be 
>>> controlled well enough.  I would consider using ultracapacitors, which 
>>>       
>
>   
>>> didn't exist until very recently, and of course have very large 
>>> capacitance values.
>>>
>>>
>>>       
>> A CB stage probably isn't optimum for the mixer preamp so that lower
>> value caps can be used provided that they effectively short the
>> amplifier input resistor Johnson noise at the frequencies of interest.
>>     
>
> But is a CB stage adequate?  Elimination of hum pickup is worth a lot.
>
>
>   
Text should have been:

A CB stage probably isn't optimum for the mixer preamp so that a low noise preamp with a higher input impedance can be employed allowing lower
value coupling caps to be used provided that they effectively short the amplifier input resistor Johnson noise at the frequencies of interest.


>>>>>> With a 1V rms full scale the noise floor degradation would be very
>>>>>> obvious when using a THAT 1646 (equivalent devices are even 
>>>>>>             
> noisier).
>   
>>>>>> It may be better to use a mixer preamp with a transformer coupled 
>>>>>>             
> output
>   
>>>>>> stage using hybrid feedback to achieve a low frequency cutoff below 
>>>>>>             
>
>   
>>>>>> 1Hz together with low noise.
>>>>>>
>>>>>>
>>>>>>             
>>>>> With a transformer, even if toroidal, keeping hum out may prove 
>>>>>           
> quite 
>   
>>>>> difficult.
>>>>>
>>>>>
>>>>>
>>>>>           
>>>> High end (eg Lundahl LL1517) line output audio transformers come with 
>>>>         
> mu
>   
>>>> metal screens and metal foil interwinding shields.
>>>>
>>>>         
>>> They don't pass 1 Hz very well. I bet the rolloff is ~20 Hz. 
>>>
>>>
>>>       
>> When driven conventionally the transformer cutoff is around 20Hz,
>> however if one uses the appropriate driver with a controlled negative
>> output R to cancel the transformer primary internal winding resistance,
>> the low frequency response can be extended significantly. This also
>> reduces the low frequency distortion.
>> However individual adjustment of driver to suit transformer is required
>> and tracking the winding resistance over temperature may be an issue.
>>     
>
> That would certainly work.  See next.
>
>  
>   
>>> Certainly one can build a VLF transformer, but it will be a project 
>>>       
> for 
>   
>>> sure, and the transformer may be quite large.
>>>
>>>
>>>       
>> The transformers only weigh about 65g.
>>     
>
> This weight estimate assumes the negative resistance circuit I assume, the 
> intent being to allow use of the Lundahl LL1517 transformer.
>
>   
Yes.
> You might be interested in the following article:  "A Broadband Active 
> Antenna for ELF Magnetic Fields" by John F. Sutton and G. Craig Spaniol" 
> in Physics Essays March 1993, Vol 6, #1, 1993.  The negative-impedance 
> trick is expanded upon.  Sutton also has some US patents on this.  US 
> patent 5,296,866 covers the antenna, but is hard to understand without the 
> article.
>
>
>   
>> It may be simpler just to select a mixer for which the IF ground can be
>> isolated from the RF and IF grounds.
>> However a preamp with a transformer output may be useful if one uses a
>> mixer where all the grounds are connected together by the package.
>>     
>
> It has to be far easier to select the right mixer than to deal with a 1 Hz 
> transformer.  And cheaper.
>
>   

I've been advocating this for some time, however one can then no longer
just buy an off the shelf mixer complete with SMA connectors, one has to
design and assemble a suitable PCB.
Obtaining suitable mixers for 5MHz and 10MHz input frequencies or even
100MHz is easy.
However for the higher microwave frequencies most mixers come complete
with connectors attached and share a common ground.

The noise problem with audio balanced drive chips can easily be overcome
with a discrete implementation.
That is discrete resistors and IC opamps.


>  
>
>   
>>>>>>>               
>>>>>> No, I meant replace his 90 degree hybrids with a digital 
>>>>>>             
> equivalent.
>   
>>>>>>             
>>>>> I believe that his 90-degree hybrids are already digital.
>>>>>
>>>>>           
>>>> I'm not convinced of that, if only because real time 10,000+ tap FIR
>>>> filters at 30+MSPS are probably still impractical.
>>>>
>>>>         
>>> I'm not convinced that one needs a 10,000-tap FIR to achieve this, and 
>>>       
> Sam 
>   
>>> Stein is one smart fellow.  I recall some NASA patents from twenty 
>>>       
> years 
>   
>>> ago on how to get I+Q data from a single ADC, and while there was FIR 
>>> processing of some kind, there were only maybe 8 or 16 taps. And 
>>>       
> Tayloe 
>   
>>> (US patent 6,230,000) gets much the same effect with one resistor, 
>>>       
> four 
>   
>>> capacitors, an analog mux, and two differential amplifiers.
>>>
>>>
>>>       
>> I have read similar papers from that era on radar signal processing.
>> They either used a Hilbert transform or a pair of digital filters whose
>> outputs were in phase quadrature.
>> The quadrature accuracy for a given bandwidth depends on the the number
>> of taps.
>> The beat frequencies (in a dual mixer system) won't match exactly and
>> some correction for the resultant phase shift errors will need 
>> to be made.
>> This may be less of a problem when the 2 beat frequency signals are
>> identical in frequency and just differ in phase.
>>     
>
> So long as we know the exact frequency, even if it isn't the exact desired 
> frequency, all may be well.
>
> Joe
>
>
>   
I'm reminded of some phase recovery algorithms used in phase shift
interferometry that largely negate the effect of small fixed phase errors.

If we can devise a suitable test setup then one could just log the
samples to a file for whatever sound card one has and make the data
available to others for analysis.
This allows a wide variety of sound cards to be evaluated without one
person having to test them all.

Bruce


From BriMDavis at aol.com  Wed Dec 17 03:21:46 2008
From: BriMDavis at aol.com (BriMDavis at aol.com)
Date: Tue, 16 Dec 2008 22:21:46 EST
Subject: [time-nuts] Build my own dist. amp ??
Message-ID: <caf.3c3850c3.3679ca4a@aol.com>

Bruce Griffiths wrote:   
>
>Very noisy, too much gain and not enough output for use in a 10MHz
>distribution amplifier with +7dbM - +15dBm input signal.
>
 Given that I mentioned both Pout and Noise Figure of the MAX2471 in
my original post, I am obviously aware of those device specifications.
 
  I was attempting to ascertain whether anyone on the list had
direct measurements, or other insight, into the close in residual
phase noise performance of these parts, as I could not find any
further specifications or internal circuit info in the associated
datasheet and application notes.
 
  I have absolutely no aspirations of reaching a wideband noise floor
of -178 dBc/Hz whilst using a device with 0 dBm output power and
a noise figure of 8 dB.  But I suspect I can do as well as, or better
than, the op-amp designs, over a wider input bandwidth.
 
 Yes, if I need more than 0 dBm of output power, there will need
to be another output buffer or gain stage in the design, hence the
phrase  "... as part of a reference distribution design ..."
 
  If you know of anything else with comparable reverse isolation, 
usable from at least 10-200 Mhz, in such a tiny package, that
costs a buck a channel, please let me know!
 
Brian
 
 
 
 
 
 
 
 
 
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From bruce.griffiths at xtra.co.nz  Wed Dec 17 03:58:37 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Wed, 17 Dec 2008 16:58:37 +1300
Subject: [time-nuts] Build my own dist. amp ??
In-Reply-To: <caf.3c3850c3.3679ca4a@aol.com>
References: <caf.3c3850c3.3679ca4a@aol.com>
Message-ID: <494878ED.50407@xtra.co.nz>

Brian

What frequency sources other than those in cell phones (for which this
device is intended) have an output signal level of -14dBm?

Very few OCXOs and other frequency standards have outputs lower than +4dBm.
Most have outputs in the +7dBm to +15dBm range.
Thus for frequency distribution systems using such sources the device is
unsuitable for use at least in a well designed system at least.

High reverse isolation and low unit cost are irrelevant if the device
isn't a good fit.
Why compromise the system performance just so one can utilise such a
device??
Its not that much more expensive to do it properly.

Using an unnecessarily  wide band device in a frequency distribution
system isn't usually a particularly good idea.

No one in their right mind would attempt to use an opamp in a frequency
distribution system where the input signal level is around -14dBm unless
the phase noise performance is of little consequence.

The only way to find out what the close in phase noise characteristics
are is to construct an amplifier using such a device and measure it.
Its unlikely to be stellar given the small device geometries and the
likely biasing techniques employed.

At 10MHz the noise figure is likely to be closer to 15dB than 8dB.


Bruce

BriMDavis at aol.com wrote:
> Bruce Griffiths wrote:   
>   
>> Very noisy, too much gain and not enough output for use in a 10MHz
>> distribution amplifier with +7dbM - +15dBm input signal.
>>
>>     
>  Given that I mentioned both Pout and Noise Figure of the MAX2471 in
> my original post, I am obviously aware of those device specifications.
>  
>   I was attempting to ascertain whether anyone on the list had
> direct measurements, or other insight, into the close in residual
> phase noise performance of these parts, as I could not find any
> further specifications or internal circuit info in the associated
> datasheet and application notes.
>  
>   I have absolutely no aspirations of reaching a wideband noise floor
> of -178 dBc/Hz whilst using a device with 0 dBm output power and
> a noise figure of 8 dB.  But I suspect I can do as well as, or better
> than, the op-amp designs, over a wider input bandwidth.
>  
>  Yes, if I need more than 0 dBm of output power, there will need
> to be another output buffer or gain stage in the design, hence the
> phrase  "... as part of a reference distribution design ..."
>  
>   If you know of anything else with comparable reverse isolation, 
> usable from at least 10-200 Mhz, in such a tiny package, that
> costs a buck a channel, please let me know!
>  
> Brian
>  
>  
>  



From BriMDavis at aol.com  Wed Dec 17 05:15:25 2008
From: BriMDavis at aol.com (BriMDavis at aol.com)
Date: Wed, 17 Dec 2008 00:15:25 EST
Subject: [time-nuts] Build my own dist. amp ??
Message-ID: <cd6.419b5008.3679e4ed@aol.com>

Bruce Griffiths wrote:
 
>
>Very few OCXOs and other frequency standards have outputs 
>lower than +4dBm. Most have outputs in the +7dBm to +15dBm range.
>
And what happens to that +7 dBm source if you split it 8 ways and
add some padding for additional matching and isolation, plus some
input transformer and/or filter losses?
 
 Or what if the reference being distributed comes off a multiplier
chain or VCO at a lower output level?
 
 Is there room in your world view for a simple, low cost design
that doesn't reach the ultimate noise floor, but covers a wide 
range of input frequencies with decent noise floor performance?
 
>
>Using an unnecessarily  wide band device in a frequency distribution
>system isn't usually a particularly good idea.
>
It isn't "unecessary" when the circuit needs to operate over 
that wide of an input frequency range in its' intended range
of applications.
 
>
>The only way to find out what the close in phase noise characteristics
>are is to construct an amplifier using such a device and measure it.
>
Some data sheets contain this information at spot frequencies; 
this one does not.
 
 Unfortunately, I do not have access to a phase noise test system
at this point in time, hence my question to the list.
 

Brian
 
p.s.
 
 I deleted most of my original reply before posting this.
 
 Your posts contain many condescending remarks insinuating
misuse of the part, and how easy it is to do it properly,
yet you refuse to answer a simple question, to wit: 

Can you point to something, IC or discrete, that will 
cover sources in the 10-200 MHz range with similar or
better reverse isolation at comparable size and cost ?




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From bruce.griffiths at xtra.co.nz  Wed Dec 17 05:54:58 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Wed, 17 Dec 2008 18:54:58 +1300
Subject: [time-nuts] Build my own dist. amp ??
In-Reply-To: <cd6.419b5008.3679e4ed@aol.com>
References: <cd6.419b5008.3679e4ed@aol.com>
Message-ID: <49489432.3070700@xtra.co.nz>

Brian

BriMDavis at aol.com wrote:
> Bruce Griffiths wrote:
>  
>   
>> Very few OCXOs and other frequency standards have outputs 
>> lower than +4dBm. Most have outputs in the +7dBm to +15dBm range.
>>
>>     
> And what happens to that +7 dBm source if you split it 8 ways and
> add some padding for additional matching and isolation, plus some
> input transformer and/or filter losses?
>   
That is a very effective way of elevating the phase noise floor.
Its usually far better to amplify the input and then split the output
maintaining a gain to the splitter outputs of at least 0dB.
>  
>  Or what if the reference being distributed comes off a multiplier
> chain or VCO at a lower output level?
>  
>   
Again, its better where possible to ensure that the input to a
multiplier is as high as is reasonably possible, most multipliers are
more efficient with higher inputs.
If one has a low level signal it is best to use a low noise buffer driving a
>  Is there room in your world view for a simple, low cost design
> that doesn't reach the ultimate noise floor, but covers a wide 
> range of input frequencies with decent noise floor performance?
>  
>   
None, where it severely compromises the phase noise floor of the
reference frequency source.
Even a Thunderbolt OCXO phase noise floor will be degraded by a system
using this device (unless of course it is used to drive N of them in
parallel and their outputs are recombined - however thats more expensive
than implementing a good design in the first place).
>> Using an unnecessarily  wide band device in a frequency distribution
>> system isn't usually a particularly good idea.
>>
>>     
> It isn't "unecessary" when the circuit needs to operate over 
> that wide of an input frequency range in its' intended range
> of applications.
>  
>   
Its almost always better to design the circuit to suit the operating
frequency, often this just means using suitable output and input filters.
>> The only way to find out what the close in phase noise characteristics
>> are is to construct an amplifier using such a device and measure it.
>>
>>     
> Some data sheets contain this information at spot frequencies; 
> this one does not.
>   
Very few datasheets from Maxim specify much about the noise
characteristics of such devices.
>  
>  Unfortunately, I do not have access to a phase noise test system
> at this point in time, hence my question to the list.
>  
>
>   
You can easily cobble one together using whatever sound card your PC has
together with a mixer and a few inexpensive opamps, filters etc.

> Brian
>  
> p.s.
>  
>  I deleted most of my original reply before posting this.
>  
>  Your posts contain many condescending remarks insinuating
> misuse of the part, and how easy it is to do it properly,
> yet you refuse to answer a simple question, to wit: 
>
> Can you point to something, IC or discrete, that will 
> cover sources in the 10-200 MHz range with similar or
> better reverse isolation at comparable size and cost ?
>
>
>   
The criticism is aimed at the concept not the person.

The question is largely irrelevant.

The use of such a device in the way which you intend is far from optimum.
But of course you are free to do that.

However, I think that its important that the limitations of such an
approach be clearly stated.

Bruce



From cupido at mail.ua.pt  Wed Dec 17 11:50:01 2008
From: cupido at mail.ua.pt (Luis Cupido)
Date: Wed, 17 Dec 2008 11:50:01 +0000
Subject: [time-nuts] Close-in phase noise (long reply)
In-Reply-To: <FBEDKEIEMDPKGDDCPGNCMEHIEAAA.wa1zms@att.net>
References: <FBEDKEIEMDPKGDDCPGNCMEHIEAAA.wa1zms@att.net>
Message-ID: <4948E769.9080109@mail.ua.pt>

Brian,

Was there any particular reason to
go from 5MHz to 20MHz in two steps ?
couldn't be just one x4 stage followed by the filter
(preferably xtal) ?

Luis Cupido.
ct1dmk.


wa1zms at att.net wrote:
> John-
> 
> The BPFs in the 5 to 20MHz chain are just 7-pole LC
> filters with the goal of trying to keep any other
> harmonics other than the desired at least -50dBc.
> Xtal filters would be the better choice, no doubt.
> 
> The -50dBc level is clearly not the best
> that one could get, but was enough for an earlier
> 240GHz project. I just used the same OCXOs and early
> stages of multipliers to get the latest system running
> on 630GHz.
> 
> In the 241GHz system, I ended up building a direct
> frequency synthesizer to get 110MHz from a 10MHz
> drive signal.  At the time, the Freq West PLL
> blocks I used wanted a VHF signal to drive
> the sampling detector to phase lock the L-band
> cavity VCO. The original Freq West units used 5th OT
> xtals for the commercial applications.
> 
> By later experimentation, I found that
> the same sampling detector would also work with a
> much lower frequency reference and still lock the
> loop. The risk however is that the PLL might lock
> on the wrong harmonic of the reference (i.e.: value of N)
> or can have higher reference spur levels since the
> PLL was designed assuming a VHF reference and not an
> HF reference frequency. But this is not a commercial
> design project, and I can live with a difficult alignment
> procedure or initial power-up PLL lock troubles.
> 
> But all this aside, my efforts are currently aimed at
> best close-in noise within the first 1KHz of BW around
> the carrier.
> 
> The PLL bricks all seem to have several kHz of loop BW,
> so my close-in noise going from 20MHz to 1320MHz should
> be only slightly worse than 20Log(n), with n=66 in my case.
> But I'm not ruling out the chance of 1/f noise (or similar)
> showing up from the sampling detector or some other yet-to-be
> determined source.
> 
> However my focus is currently on the 5MHz to 20MHz portion
> of the LO chain and to be sure the gain stages are not
> running near compression. I do still agree with your
> earlier comment about getting the most from that portion
> of the chain.
> 
> -Brian, WA1ZMS
> 
> -----Original Message-----
> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com]On
> Behalf Of John Miles
> Sent: Tuesday, December 16, 2008 7:53 PM
> To: Discussion of precise time and frequency measurement
> Subject: Re: [time-nuts] Close-in phase noise question...more info...
> 
> 
>> More info on the LO chain:
>>
>> 1) 5MHz Wenzel OCXO <--Custom Osc for me.
>> 2) MSA-1105 buffer MMIC and lumped LPF
>> 3) 5MHz to 10MHz 1N5711 diode based doubler
>> 4) MSA-1105 buffer and lumped LPF
>> 5) 10MHz to 20MHz 1N5711 diode based doubler
>> 6) 20MHz BPF
> 
> What kind of BPF?  A really narrow crystal filter would be nice here.  (You
> have basically reproduced the 8568A/B's 20 MHz reference section.)
> 
>> 7) 20MHz drives sampling detector inside surplus Frequency
>> West PLL block to lock 1320MHz cavity oscillator.
> 
> Sounds OK as long as the sampler loop's noise floor doesn't limit you.  I
> haven't measured the in-band residual floor of any bricks but I'd be
> surprised if an SRD multiplier wouldn't be quieter.
> 
>> 8) 1320MHz drives Frequency West SRD multiplier to 6.6GHz.
> 
> If I wanted to get to several GHz with what's in my junk box right now, I
> would do what you did to get to 20 MHz, BPF it with a multipole crystal
> filter, and then use a few more multiplier stages to get somewhere between
> 100 MHz and 1 GHz, a la the 8662A reference section, depending on the choice
> of the next stage.
> 
> That VHF drive signal would go into either an HP 33002A or 33004A SRD
> multiplier, or one of the Picosecond NLTL multipliers (e.g.,
> http://www.picosecond.com/product/product.asp?prod_id=109 ) I picked up in
> their fire sale when they shut down their fab.
> 
>> 9) 6.6GHz to 39.6GHz Milliwave diode multiplier/amp/filter
>> 10) 39.6GHz to 79.2GHz in varactor doubler
>> 11) 79.2GHz to 158.4GHz in varactor doubler
>> 12) 158.4GHz into x4 sub-harmonic mixer
> 
> AFAIK the rest of the chain is fine.  I'd focus on getting rid of the brick
> PLL, or at least taking pains to make sure that it's not the problem, before
> worrying about the MMICs in your early stages.
> 
> Remember that there's no point in optimizing the PN of any one stage much
> below the input-referred residual noise of the following stage.  MMICs, in
> saturation or not, are pretty quiet.  Quieter than sampler loops anyway.
> 
> -- john, KE5FX
> 
> 
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
> 
> 
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
> 


From grant at ghengineering.co.uk  Wed Dec 17 13:03:50 2008
From: grant at ghengineering.co.uk (Grant Hodgson)
Date: Wed, 17 Dec 2008 13:03:50 +0000
Subject: [time-nuts] Close-in phase noise question...
In-Reply-To: <494782FE.8040109@xtra.co.nz>
References: <mailman.392.1229368512.2499.time-nuts@febo.com>
	<49477D64.3010005@ghengineering.co.uk>
	<494782FE.8040109@xtra.co.nz>
Message-ID: <4948F8B6.9030304@ghengineering.co.uk>

Brian

Thanks for the details.

There are a number of problems with crystal filters.  A crystal filter 
will have a finite bandwidth, and at offsets less than half the 
bandwidth the filter won't have a significant effect on the phase noise. 
  For example the 40MHz xtal filter used in the 8662A has a bandwidth of 
6kHz (according to the service manual), so phase noise at less than 3kHz 
offset will not be affected.

For your application you would need a filter with a very narrow 
bandwidth indeed - maybe 50Hz or so.  Ignoring the manufacturing issues 
of such a device, there could be problems with temperature sensitivity 
and microphony.  These problems could of course be overcome, but I'm not 
convinced that a crystal filter would give an overall benefit in this 
application, given that the primary goal is to achieve leading-edge 
close in phase noise.

The MSA1105 has better phase noise than I thought, but I'd still be 
tempted to change one or both of the passive doubler/buffer stages to an 
active doubler, if the figures for the NIST active doubler are correct.

regards

Grant


From wa1zms at att.net  Wed Dec 17 14:12:52 2008
From: wa1zms at att.net (wa1zms at att.net)
Date: Wed, 17 Dec 2008 14:12:52 +0000
Subject: [time-nuts] Close-in phase noise (long reply)
In-Reply-To: <4948E769.9080109@mail.ua.pt>
References: <FBEDKEIEMDPKGDDCPGNCMEHIEAAA.wa1zms@att.net>
	<4948E769.9080109@mail.ua.pt>
Message-ID: <121720081412.15305.494908E4000B6E6100003BC922243322829B0A02D29B9B0EBF9C0396CE0E99@att.net>

Luis-
Only beacuse I was more familiar with balanced doublers,
and felt that the x4 would need tougher filtering.

The balanced doublers also have much better conversion
efficiency, thus fewer gain stages. Or so I think.

Besides, I had drawers full of 1N5711 diodes, & toriods!

-Brian


 -------------- Original message from Luis Cupido <cupido at mail.ua.pt>: --------------


> Brian,
> 
> Was there any particular reason to
> go from 5MHz to 20MHz in two steps ?
> couldn't be just one x4 stage followed by the filter
> (preferably xtal) ?
> 
> Luis Cupido.
> ct1dmk.
> 
>


From gwinn at raytheon.com  Wed Dec 17 19:21:25 2008
From: gwinn at raytheon.com (Joseph M Gwinn)
Date: Wed, 17 Dec 2008 14:21:25 -0500
Subject: [time-nuts] Sub Pico Second Phase logger
In-Reply-To: <49487053.8040300@xtra.co.nz>
Message-ID: <OF82CE5BA4.E295CDB3-ON85257522.006701B9-85257522.006A4527@mck.us.ray.com>

Bruce,


time-nuts-bounces at febo.com wrote on 12/16/2008 10:21:55 PM:

> Joe
> 
> Joseph M Gwinn wrote:
> > Bruce,
> >
[snip]
> > 
Bruce wrote:
> >> 
> >> A CB stage probably isn't optimum for the mixer preamp so that lower
> >> value caps can be used provided that they effectively short the
> >> amplifier input resistor Johnson noise at the frequencies ofinterest.
> >> 
> >
> > But is a CB stage adequate?  Elimination of hum pickup is worth a lot.
> >
> >
> > 
> [Bruce] Text should have been:
> 
> A CB stage probably isn't optimum for the mixer preamp so that 
> a low noise preamp with a higher input impedance can be 
> employed allowing lower
> value coupling caps to be used provided that they effectively 
> short the amplifier input resistor Johnson noise at the 
> frequencies of interest.

OK.  The form of input amplifier is one of the tradeoffs one must make.



> >> It may be simpler just to select a mixer for which the IF ground can 
be
> >> isolated from the RF and LO grounds.
> >> However a preamp with a transformer output may be useful if one uses 
a
> >> mixer where all the grounds are connected together by the package.
> >> 
> >
> > It has to be far easier to select the right mixer than to deal with a 
1 Hz 
> > transformer.  And cheaper.
> >
> > 
> 
> I've been advocating this for some time, however one can then no longer
> just buy an off the shelf mixer complete with SMA connectors, one has to
> design and assemble a suitable PCB.

Actually, for quantity one, I don't bother with PCBs.  I use 1/16 inch 
thick glass-epoxy Vectorboard with a 0.1" hole pitch, and thread bare wire 
through the holes.  Given that these are effectively prototype boards, the 
ease of wholesale change is very useful.  For transmission lines, I would 
just run miniature coax or homebrew twisted pair from point to point on 
the board, although it has not been neecessary yet.  If microphonics is an 
issue, the board can be conformal coated to glue the wires in place. 

The traditional coat, wax, allows easy alteration and repair.  In the 
1960s, a friend was building things using RTL (Resistor Transistor Logic) 
ICs and solderable magnet wire between the leads.  What a rats' nest that 
was.   The problem was how to package this so it wouldn't fail when 
bumped.  The solution was to build the circuit on a sheet of vectorboard 
in a 12" by 12" rectangular baking pan, and then fill the pan with hot 
wax.  Whenever something had to be changed, melt the wax, pour it off, 
make the change, pour the wax back into the pan, allow to cool.

Modern ICs connected with point-to-point wires and potted in wax - it's an 
odd mix of technology ages.  Like implementing stone-age tools with modern 
ceramics.

If I were building receivers, I suppose I would be forced to use 
surface-mount comoponents and PCBs.


> Obtaining suitable mixers for 5MHz and 10MHz input frequencies or even 
100MHz is easy.
> However for the higher microwave frequencies most mixers come complete
> with connectors attached and share a common ground.

True.  However, I don't think we will be going from 1 GHz to 1 Hz in a 
single step, and the last mixer can have separate grounds.


> The noise problem with audio balanced drive chips can easily be overcome
> with a discrete implementation.
> That is discrete resistors and IC opamps.

Yes, even on vectorboard.  I do it all the time.

Eventually, the supply of through-hole components will dry up, but it 
hasn't happened yet, and some components from the 1970s are still 
available.  Even if the original manufacturer is long dead.


> > 
> >> I have read similar papers from that era on radar signal processing.
> >> They either used a Hilbert transform or a pair of digital filters 
whose
> >> outputs were in phase quadrature.
> >> The quadrature accuracy for a given bandwidth depends on the number
> >> of taps.
> >> The beat frequencies (in a dual mixer system) won't match exactly and
> >> some correction for the resultant phase shift errors will need 
> >> to be made.
> >> This may be less of a problem when the 2 beat frequency signals are
> >> identical in frequency and just differ in phase.
> >> 
> >
> > So long as we know the exact frequency, even if it isn't the exact 
desired 
> > frequency, all may be well.
> >
> > Joe
> >
> >
> > 
> I'm reminded of some phase recovery algorithms used in phase shift
> interferometry that largely negate the effect of small fixed 
> phase errors.

Yes.  A detailed math analysis of the test setup will be needed.

 
> If we can devise a suitable test setup then one could just log the
> samples to a file for whatever sound card one has and make the data
> available to others for analysis.

Yes.


> This allows a wide variety of sound cards to be evaluated without one
> person having to test them all.

And evaluation of the same test data by multiple people using different 
tools also allows us to distinguish test artifacts from processing 
artifacts.


Joe


From bruce.griffiths at xtra.co.nz  Wed Dec 17 20:43:16 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Thu, 18 Dec 2008 09:43:16 +1300
Subject: [time-nuts] Sub Pico Second Phase logger
In-Reply-To: <OF82CE5BA4.E295CDB3-ON85257522.006701B9-85257522.006A4527@mck.us.ray.com>
References: <OF82CE5BA4.E295CDB3-ON85257522.006701B9-85257522.006A4527@mck.us.ray.com>
Message-ID: <49496464.4000106@xtra.co.nz>

Joe

Joseph M Gwinn wrote:
> Bruce,
>
>
> time-nuts-bounces at febo.com wrote on 12/16/2008 10:21:55 PM:
>
>   
>> Joe
>>
>> Joseph M Gwinn wrote:
>>     
>>> Bruce,
>>>
>>>       
> [snip]
>   
> Bruce wrote:
>   
>>>> A CB stage probably isn't optimum for the mixer preamp so that lower
>>>> value caps can be used provided that they effectively short the
>>>> amplifier input resistor Johnson noise at the frequencies ofinterest.
>>>>
>>>>         
>>> But is a CB stage adequate?  Elimination of hum pickup is worth a lot.
>>>
>>>
>>>
>>>       
>> [Bruce] Text should have been:
>>
>> A CB stage probably isn't optimum for the mixer preamp so that 
>> a low noise preamp with a higher input impedance can be 
>> employed allowing lower
>> value coupling caps to be used provided that they effectively 
>> short the amplifier input resistor Johnson noise at the 
>> frequencies of interest.
>>     
>
> OK.  The form of input amplifier is one of the tradeoffs one must make.
>
>
>
>   
>>>> It may be simpler just to select a mixer for which the IF ground can 
>>>>         
> be
>   
>>>> isolated from the RF and LO grounds.
>>>> However a preamp with a transformer output may be useful if one uses 
>>>>         
> a
>   
>>>> mixer where all the grounds are connected together by the package.
>>>>
>>>>         
>>> It has to be far easier to select the right mixer than to deal with a 
>>>       
> 1 Hz 
>   
>>> transformer.  And cheaper.
>>>
>>>
>>>       
>> I've been advocating this for some time, however one can then no longer
>> just buy an off the shelf mixer complete with SMA connectors, one has to
>> design and assemble a suitable PCB.
>>     
>
> Actually, for quantity one, I don't bother with PCBs.  I use 1/16 inch 
> thick glass-epoxy Vectorboard with a 0.1" hole pitch, and thread bare wire 
> through the holes.  Given that these are effectively prototype boards, the 
> ease of wholesale change is very useful.  For transmission lines, I would 
> just run miniature coax or homebrew twisted pair from point to point on 
> the board, although it has not been neecessary yet.  If microphonics is an 
> issue, the board can be conformal coated to glue the wires in place. 
>
> The traditional coat, wax, allows easy alteration and repair.  In the 
> 1960s, a friend was building things using RTL (Resistor Transistor Logic) 
> ICs and solderable magnet wire between the leads.  What a rats' nest that 
> was.   The problem was how to package this so it wouldn't fail when 
> bumped.  The solution was to build the circuit on a sheet of vectorboard 
> in a 12" by 12" rectangular baking pan, and then fill the pan with hot 
> wax.  Whenever something had to be changed, melt the wax, pour it off, 
> make the change, pour the wax back into the pan, allow to cool.
>
> Modern ICs connected with point-to-point wires and potted in wax - it's an 
> odd mix of technology ages.  Like implementing stone-age tools with modern 
> ceramics.
>
> If I were building receivers, I suppose I would be forced to use 
> surface-mount comoponents and PCBs.
>
>
>   
>> Obtaining suitable mixers for 5MHz and 10MHz input frequencies or even 
>>     
> 100MHz is easy.
>   
>> However for the higher microwave frequencies most mixers come complete
>> with connectors attached and share a common ground.
>>     
>
> True.  However, I don't think we will be going from 1 GHz to 1 Hz in a 
> single step, and the last mixer can have separate grounds.
>
>
>   
An upper limit of at least 100MHz should be feasible for the final mixer.
A dual conversion scheme will be essential if one uses a triple balanced
or similar first mixer that has an IF response that doesn't extend down
to the low frequencies that a sound card can use.


>> The noise problem with audio balanced drive chips can easily be overcome
>> with a discrete implementation.
>> That is discrete resistors and IC opamps.
>>     
>
> Yes, even on vectorboard.  I do it all the time.
>
> Eventually, the supply of through-hole components will dry up, but it 
> hasn't happened yet, and some components from the 1970s are still 
> available.  Even if the original manufacturer is long dead.
>
>
>   
>>>> I have read similar papers from that era on radar signal processing.
>>>> They either used a Hilbert transform or a pair of digital filters 
>>>>         
> whose
>   
>>>> outputs were in phase quadrature.
>>>> The quadrature accuracy for a given bandwidth depends on the number
>>>> of taps.
>>>> The beat frequencies (in a dual mixer system) won't match exactly and
>>>> some correction for the resultant phase shift errors will need 
>>>> to be made.
>>>> This may be less of a problem when the 2 beat frequency signals are
>>>> identical in frequency and just differ in phase.
>>>>
>>>>         
>>> So long as we know the exact frequency, even if it isn't the exact 
>>>       
> desired 
>   
>>> frequency, all may be well.
>>>
>>> Joe
>>>
>>>
>>>
>>>       
>> I'm reminded of some phase recovery algorithms used in phase shift
>> interferometry that largely negate the effect of small fixed 
>> phase errors.
>>     
>
> Yes.  A detailed math analysis of the test setup will be needed.
>
>  
>   
>> If we can devise a suitable test setup then one could just log the
>> samples to a file for whatever sound card one has and make the data
>> available to others for analysis.
>>     
>
> Yes.
>
>
>   
>> This allows a wide variety of sound cards to be evaluated without one
>> person having to test them all.
>>     
>
> And evaluation of the same test data by multiple people using different 
> tools also allows us to distinguish test artifacts from processing 
> artifacts.
>
>
> Joe
>   

Proposed test setup:
(preliminary to be refined)

Drive 2 sound card inputs in parallel with the same source.

Source amplitude:
Max sound card input -3dB

Sources:

1) Wien bridge or equivalent (eg state variable oscillator with soft
clamping) relatively low distortion oscillator.

2) Buffered low pass filtered output of binary divider driven by a
crystal oscillator


Test frequencies:

100Hz

1kHz

Sound card sample rate:

~24KSPS

Test duration:

1000 sec

File format:

Wave file??
Resolution 24 bits for 24 bit sound cards, 16 bits for 16bit and lower
resolution sound cards, etc.

Some refinement of sample rates and test duration is required to keep
the data file sizes manageable.
With a 24 bit sound card sampling at 96KSPS or 192KSPS for 1000sec can
produce file sizes of 1GB or more.
Some preprocessing (low pass filter and decimation) may also be required.

Bruce


From gwinn at raytheon.com  Wed Dec 17 22:36:02 2008
From: gwinn at raytheon.com (Joseph M Gwinn)
Date: Wed, 17 Dec 2008 17:36:02 -0500
Subject: [time-nuts] Sub Pico Second Phase logger
In-Reply-To: <49485E83.4070205@xtra.co.nz>
Message-ID: <OFCC523E96.6A10106C-ON85257522.000CEFC1-85257522.007C164A@mck.us.ray.com>

Bruce,


time-nuts-bounces at febo.com wrote on 12/16/2008 09:05:55 PM:

> Joseph M Gwinn wrote:
> > Bruce,
> >
> >
> > time-nuts-bounces at febo.com wrote on 12/15/2008 05:31:27 PM:
> >
> > 
> >> Joseph M Gwinn wrote:
> >> 
> >>> Bruce,
> >>>
> >>>
> >>> time-nuts-bounces at febo.com wrote on 12/15/2008 04:34:34 PM:
> >>>
> >>> 
> > [snip]
> >>
> >> I'll look into doing this [MDEV and ADEV].
> >> Real time filtering and decimation may be impractical, in the short 
term
> >> at least, as most signal processing libraries only process 16 bit 
> >> samples.
> > 
> >> Most real time spectrum analysis programs are similarly afflicted in
> >> that they only process 16 bit samples.
> >> 
> >
> > I don't see why we would need realtime filtering.  Data reduction can 
be 
> > offline, so we ought to be able to use 32-bit or 64-bit arithmetic.
> >
> > Given that we will inspect Allan Deviation data in a log-log plot, one 
can 
> > save much processing time by spacing the tau values to be computed 
> > uniformly in log tau.  I've played with this in Mathematica, and it 
does 
> > work and yields a large speedup factor.  It should also help with 
Plotter 
> > and Win2K limits.  One trick is to ensure that one computes each tau 
value 
> > at most once.  This check is needed because with close spacing, the 
round 
> > function will yield the same tau values multiple times for small 
values of 
> > tau.
> >
> > Joe
> >
> > 
> Joe
> 
> Real time processing certainly isn't required to characterise the 
performance.
> However some may be tempted to do this, it's probably possible with a 
sufficently fast machine.

If we are looking for thermal effects, with a characteristic timescale of 
tens of minutes to hours, the concept of realtime can be very generous.


> I was just highlighting a problem with some available signal processing
> libraries which may have been developed before sound cards with
> resolutions of more than 16 bits became available.
> Some (perhaps most) real time spectrum display software also has this
> problem (eg baudline, Virtins etc).

I would assume that there are newer libraries now, and libraries available 
as source code can be updated and recompiled.

20 Log[ 2^16 ]= 96 dB.  This isn't awful, and we will get the entire 
16-bit range if the ADC is 24 bits (with ENOB of 19-20 bits) and we scale 
and round the samples properly.

As I think about it, the 16-bit limit must be for embedded signal 
processing code, and math libraries intended for use on ordinary computers 
will be at least 32 bit or 64-bit float, so it should not be difficult to 
come by the necessary code.


> It isn't necessary to use a pair of mixers and an offset source to
> characterise the sound card, driving both sound card inputs from the
> same audio source should suffice.

Yes.  One input at a time, with the other input shorted, so we can also 
see the crosstalk.


> The audio source need not have low ultra low distortion (the IF output
> signals in a dual mixer system won't have ultra low distortion) or very
> high frequency stability (the IF output signals in a dual mixer system
> won't necessarily have particularly high frequency stability).

But ... but ... but ... I thought Time Nuts used only atomic frequency 
refs, and crystals only if oven stabilized.

 
> A standard RC audio oscillator with distortion lower than 1% or so
> should suffice.
> At least the resultant frequency fluctuations should thoroughly exercise
> the phase extraction algorithms.
> 
> Another option would be to low pass filter the output of a divider.
> Using a sound card to generate the test signal is also possible but it
> can potentially introduce extraneous noise and other artifacts such as
> phase truncation spurs.

If one chooses the test frequencies correctly, one can eliminate the 
spurs.  The trick is to choose frequencies that lead to DDS tuning words 
that have zeroes in the accumulator bits that are truncated (that is, do 
not make it into the sin/cos lookup table).


Step one of planning an experiment is to decide on the objectives.  The 
large scale objective is to determine which sound cards are suitable for a 
number of time-related tasks, so we should enumerate and describe these 
tasks. 

Task 1.  The immediate task is to receive and digitize the sinewave output 
from a mixer, the sinewave being the offset frequency coming out of a DMTD 
apparatus. Offset frequencies will range from 10 Hz to 1 KHz, will be 
known with great precision from the design of the apparatus, and need not 
be measured.  This sinewave is high amplitude (at least one volt rms, 
matched to the needs of the soundcard) and very high SNR.  This will be 
done in two channels in parallel.  The signals are at the same frequency 
but differ in phase.  The intent is to extract the phases of these two 
sinewaves, the difference in phase being the ultimate output.  The phase 
of a signal will be extracted by least-squares fitting of a sine function 
to the measured data.

And so on.  We need to list the tasks, and to use this task list to inform 
the experiment design.



From bruce.griffiths at xtra.co.nz  Wed Dec 17 23:26:00 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Thu, 18 Dec 2008 12:26:00 +1300
Subject: [time-nuts] Sub Pico Second Phase logger
In-Reply-To: <OFCC523E96.6A10106C-ON85257522.000CEFC1-85257522.007C164A@mck.us.ray.com>
References: <OFCC523E96.6A10106C-ON85257522.000CEFC1-85257522.007C164A@mck.us.ray.com>
Message-ID: <49498A88.30106@xtra.co.nz>

Joseph M Gwinn wrote:
> Bruce,
>
>
> time-nuts-bounces at febo.com wrote on 12/16/2008 09:05:55 PM:
>
>   
>> Joseph M Gwinn wrote:
>>     
>>> Bruce,
>>>
>>>
>>> time-nuts-bounces at febo.com wrote on 12/15/2008 05:31:27 PM:
>>>
>>>
>>>       
>>>> Joseph M Gwinn wrote:
>>>>
>>>>         
>>>>> Bruce,
>>>>>
>>>>>
>>>>> time-nuts-bounces at febo.com wrote on 12/15/2008 04:34:34 PM:
>>>>>
>>>>>
>>>>>           
>>> [snip]
>>>       
>>>> I'll look into doing this [MDEV and ADEV].
>>>> Real time filtering and decimation may be impractical, in the short 
>>>>         
> term
>   
>>>> at least, as most signal processing libraries only process 16 bit 
>>>> samples.
>>>>         
>>>> Most real time spectrum analysis programs are similarly afflicted in
>>>> that they only process 16 bit samples.
>>>>
>>>>         
>>> I don't see why we would need realtime filtering.  Data reduction can 
>>>       
> be 
>   
>>> offline, so we ought to be able to use 32-bit or 64-bit arithmetic.
>>>
>>> Given that we will inspect Allan Deviation data in a log-log plot, one 
>>>       
> can 
>   
>>> save much processing time by spacing the tau values to be computed 
>>> uniformly in log tau.  I've played with this in Mathematica, and it 
>>>       
> does 
>   
>>> work and yields a large speedup factor.  It should also help with 
>>>       
> Plotter 
>   
>>> and Win2K limits.  One trick is to ensure that one computes each tau 
>>>       
> value 
>   
>>> at most once.  This check is needed because with close spacing, the 
>>>       
> round 
>   
>>> function will yield the same tau values multiple times for small 
>>>       
> values of 
>   
>>> tau.
>>>
>>> Joe
>>>
>>>
>>>       
>> Joe
>>
>> Real time processing certainly isn't required to characterise the 
>>     
> performance.
>   
>> However some may be tempted to do this, it's probably possible with a 
>>     
> sufficently fast machine.
>
> If we are looking for thermal effects, with a characteristic timescale of 
> tens of minutes to hours, the concept of realtime can be very generous.
>
>
>   
>> I was just highlighting a problem with some available signal processing
>> libraries which may have been developed before sound cards with
>> resolutions of more than 16 bits became available.
>> Some (perhaps most) real time spectrum display software also has this
>> problem (eg baudline, Virtins etc).
>>     
>
> I would assume that there are newer libraries now, and libraries available 
> as source code can be updated and recompiled.
>
> 20 Log[ 2^16 ]= 96 dB.  This isn't awful, and we will get the entire 
> 16-bit range if the ADC is 24 bits (with ENOB of 19-20 bits) and we scale 
> and round the samples properly.
>
> As I think about it, the 16-bit limit must be for embedded signal 
> processing code, and math libraries intended for use on ordinary computers 
> will be at least 32 bit or 64-bit float, so it should not be difficult to 
> come by the necessary code.
>
>
>   
>> It isn't necessary to use a pair of mixers and an offset source to
>> characterise the sound card, driving both sound card inputs from the
>> same audio source should suffice.
>>     
>
> Yes.  One input at a time, with the other input shorted, so we can also 
> see the crosstalk.
>
>
>   
>> The audio source need not have low ultra low distortion (the IF output
>> signals in a dual mixer system won't have ultra low distortion) or very
>> high frequency stability (the IF output signals in a dual mixer system
>> won't necessarily have particularly high frequency stability).
>>     
>
> But ... but ... but ... I thought Time Nuts used only atomic frequency 
> refs, and crystals only if oven stabilized.
>
>   
If one mixes down a 10MHz source to 100Hz the fractional frequency
instability (of the beat frequency) is magnified by a factor of 1E5 over
that of the 10MHz source.
This assumes that the offset source has significantly lower instability
than the source under test.
In the special case when the offset source and the test source are phase
locked the offset frequency will have much greater stability.

>  
>   
>> A standard RC audio oscillator with distortion lower than 1% or so
>> should suffice.
>> At least the resultant frequency fluctuations should thoroughly exercise
>> the phase extraction algorithms.
>>
>> Another option would be to low pass filter the output of a divider.
>> Using a sound card to generate the test signal is also possible but it
>> can potentially introduce extraneous noise and other artifacts such as
>> phase truncation spurs.
>>     
>
> If one chooses the test frequencies correctly, one can eliminate the 
> spurs.  The trick is to choose frequencies that lead to DDS tuning words 
> that have zeroes in the accumulator bits that are truncated (that is, do 
> not make it into the sin/cos lookup table).
>
>
>   
This just adds another layer of complexity for little immediate gain.
Making the algorithms robust against small drifts in beat frequency is
more useful in the general case (when 2 different test sources are being
compared) than just assuming that the the beat frequency is very stable
and fixed.
> Step one of planning an experiment is to decide on the objectives.  The 
> large scale objective is to determine which sound cards are suitable for a 
> number of time-related tasks, so we should enumerate and describe these 
> tasks. 
>
> Task 1.  The immediate task is to receive and digitize the sinewave output 
> from a mixer, the sinewave being the offset frequency coming out of a DMTD 
> apparatus. Offset frequencies will range from 10 Hz to 1 KHz, will be 
> known with great precision from the design of the apparatus, and need not 
> be measured.  This sinewave is high amplitude (at least one volt rms, 
> matched to the needs of the soundcard) and very high SNR.  This will be 
> done in two channels in parallel.  The signals are at the same frequency 
> but differ in phase.  The intent is to extract the phases of these two 
> sinewaves, the difference in phase being the ultimate output.  The phase 
> of a signal will be extracted by least-squares fitting of a sine function 
> to the measured data.
>
> And so on.  We need to list the tasks, and to use this task list to inform 
> the experiment design.
>
>
>   
The immediate task is actually to evaluate sound cards for their
suitability, preferably without the added cost and complexity of a DDS
LO and mixer.
Once this evaluation is done, using a mixer and a DDS based LO to
generate a beat frequency is the next step.
Eliminating the mixer and DDS allows a greater number of participants at
this stage than would otherwise be the case.

10Hz resolution whilst avoiding phase truncation spurs is impractical
with a DDS chip by itself.
Depending on the DDS and its clock frequency, the frequency spacing of
phase truncation spur free outputs may be as large as several kHz.
A few divide and mix stages will be required to achieve a spur free
resolution of 10Hz.
A DDS chip with higher resolution phase outputs after truncation such as
the AD99XX series are better in this respect than the earlier AD98XX series.

To broaden participation we need to broaden the scope of the project to
include dual mixer system with statistically independent test sources as
well as the more specialised case where the 2 input frequencies differ
only in phase.

1) Evaluate sound cards for suitablility.
Initially use simple less stable sources and follow up with more stable
test sources for the more promising cards.
Need to measure crosstalk, temporal instability of interchannel phase
shift, system noise etc.

2) Develop robust algorithms for phase extraction.
Use the data produced by the less stable sources and that produced by
the more stable sources

3) Repeat testing using a dual mixer system complete with offset LO.
Test frequencies identical to evaluate system noise floor.

4) Repeat testing using a dual mixer system complete with offset LO.
Test frequencies differ to help the effect of residual crosstalk and
other artifacts.

5) Split the project into 2 branches:
A) where mixer inputs differ only by a phase shift to be measured.
Useful for measuring effect on ADEV of various components and their
phase shift tempcos etc.

B) Where the mixer input test sources are statistically independent.
Useful for measuring pairwise source ADEV etc.

Bruce


From ch at murgatroid.com  Thu Dec 18 01:26:22 2008
From: ch at murgatroid.com (christopher hoover)
Date: Wed, 17 Dec 2008 17:26:22 -0800
Subject: [time-nuts] prototyping (was Sub Pico Second Phase logger)
In-Reply-To: <mailman.471.1229553406.2499.time-nuts@febo.com>
References: <mailman.471.1229553406.2499.time-nuts@febo.com>
Message-ID: <001601c960af$a2ee4f80$e8caee80$@com>

Joseph M Gwinn <gwinn at raytheon.com> wrote:
> 
> Actually, for quantity one, I don't bother with PCBs.  I use 1/16 inch
> thick glass-epoxy Vectorboard with a 0.1" hole pitch, and thread bare
> wire through the holes.  
>
>...
>
> If I were building receivers, I suppose I would be forced to use
> surface-mount comoponents and PCBs.

For one off and experimentation, ugly style on a solid ground plane works
quite well.   I have built a number of receivers in this style.

There are kits available of self-adhesive bits of PCB that you can stick
onto the ground plane to create islands or to mount delicate parts.  You can
get away without these -- e.g. by the judicious use of an xacto knife --
but they certainly are handy.

Of particular relevance to the quoted text, you can get strips of PCB for
50Z, 75Z, etc transmission lines -- we have these in our labstock.  (Sorry,
I forget the brand name.)

-ch




From didier at cox.net  Thu Dec 18 05:41:12 2008
From: didier at cox.net (Didier)
Date: Wed, 17 Dec 2008 23:41:12 -0600
Subject: [time-nuts] Build my own dist. amp ??
In-Reply-To: <cd6.419b5008.3679e4ed@aol.com>
References: <cd6.419b5008.3679e4ed@aol.com>
Message-ID: <72060A35C8994D2A9259BA2BA820478C@didierhp>

Brian,

Your original post asked for a reference distribution amplifier. 

"Just wondering if anyone has ever tried the MAX2470/2471 VCO buffers as
part of a reference distribution design?"

Why would it need to cover more than one frequency? 

Every piece of equipment in my lab that accepts an external reference will
accept 10 MHz. Some also accept 5, 2 and/or 1, but 10 is universal. I am
aware that some specific applications may require other frequencies, but in
most cases these will be between 1 and 10 MHz. For best performance (or
acceptable performance at low cost and low pain level), don't try to cover a
band wider than that, all you will get is increased noise and increased
susceptibility to leakage.

Certainly 10 to 500 MHz seems excessive for most reference distribution
designs. If you have a different application in mind, please tell us.

Didier KO4BB 

> -----Original Message-----
> From: time-nuts-bounces at febo.com 
> [mailto:time-nuts-bounces at febo.com] On Behalf Of BriMDavis at aol.com
> Sent: Tuesday, December 16, 2008 11:15 PM
> To: time-nuts at febo.com
> Subject: [time-nuts] Build my own dist. amp ??
> 
> >
> >Using an unnecessarily  wide band device in a frequency distribution 
> >system isn't usually a particularly good idea.
> >
> It isn't "unecessary" when the circuit needs to operate over 
> that wide of an input frequency range in its' intended range 
> of applications.
>  



From sar10538 at gmail.com  Thu Dec 18 05:50:07 2008
From: sar10538 at gmail.com (Steve Rooke)
Date: Thu, 18 Dec 2008 18:50:07 +1300
Subject: [time-nuts] Build my own dist. amp ??
In-Reply-To: <49489432.3070700@xtra.co.nz>
References: <cd6.419b5008.3679e4ed@aol.com> <49489432.3070700@xtra.co.nz>
Message-ID: <1231b6a80812172150o2089c31fy2f192f3833de584@mail.gmail.com>

Bruce,

2008/12/17 Bruce Griffiths <bruce.griffiths at xtra.co.nz>:
> You can easily cobble one together using whatever sound card your PC has
> together with a mixer and a few inexpensive opamps, filters etc.

I have read all your posts with great interest and have learned a
great deal from them but the thing that is invarably missing is a
reference to any actual designs. Do you have some links that would
enable a complete idiot like myself to be able to do things such as
this please. I am keen to be able to achieve these things, as I am
sure others are as well, but I lack the sort of hand-holding to get
into this field.

Thank you,
Steve
-- 
Steve Rooke - ZL3TUV & G8KVD
Omnium finis imminet


From bruce.griffiths at xtra.co.nz  Thu Dec 18 11:56:43 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Fri, 19 Dec 2008 00:56:43 +1300
Subject: [time-nuts] Phase noise measurement with a sound card
In-Reply-To: <1231b6a80812172150o2089c31fy2f192f3833de584@mail.gmail.com>
References: <cd6.419b5008.3679e4ed@aol.com> <49489432.3070700@xtra.co.nz>
	<1231b6a80812172150o2089c31fy2f192f3833de584@mail.gmail.com>
Message-ID: <494A3A7B.1040503@xtra.co.nz>

Steve Rooke wrote:
> Bruce,
>
> 2008/12/17 Bruce Griffiths <bruce.griffiths at xtra.co.nz>:
>   
>> You can easily cobble one together using whatever sound card your PC has
>> together with a mixer and a few inexpensive opamps, filters etc.
>>     
>
> I have read all your posts with great interest and have learned a
> great deal from them but the thing that is invarably missing is a
> reference to any actual designs. Do you have some links that would
> enable a complete idiot like myself to be able to do things such as
> this please. I am keen to be able to achieve these things, as I am
> sure others are as well, but I lack the sort of hand-holding to get
> into this field.
>
> Thank you,
> Steve
>   
Steve

Wenzel's site indicates how phase noise measurement of an OCXO can be done:

http://www.wenzel.com/documents/measuringphasenoise.htm

However he doesn't discuss the simpler problem of measuring the phase
noise of components such as amplifiers.
This only requires a single low noise signal source and the phase lock
loop can be replaced by a phase shifter.

You will need:

1) A sound card

2) Spectrum analyser software for the sound card

3) A low noise preamp

4) A mixer/phase detector

5) A phase shifter

6) A passive splitter

7) Some RF low phase noise isolation amplifiers

8) A means of calibrating the entire phase noise measurement setup.

You need to first obtain suitable software
For Linux Baudline will suffice if you only have a 16 bit sound card.
You can also run spectrum Lab under Wine

For Windows (but not Vista unless you run XP in a virtual machine)
Spectrum Lab is suitable.
http://freenet-homepage.de/dl4yhf/spectra1.html

The first task is to install suitable software and become familiar with
the performance of your sound card.
Once this has been determined you will be ready for the next step.

To be continued........

Bruce


From stijena at tapko.de  Thu Dec 18 20:19:44 2008
From: stijena at tapko.de (Predrag Dukic)
Date: Thu, 18 Dec 2008 21:19:44 +0100
Subject: [time-nuts] Is oscillator sync always bad?
In-Reply-To: <49496464.4000106@xtra.co.nz>
References: <OF82CE5BA4.E295CDB3-ON85257522.006701B9-85257522.006A4527@mck.us.ray.com>
	<49496464.4000106@xtra.co.nz>
Message-ID: <7.0.1.0.1.20081218211512.01ede5d8@tapko.de>



Hi, Time -Nuts,

Did anyone try to deliberately allow  syncronisation  of two 
oscillators, by , for example paralleling  outputs of two 10811.

I expect to see some benefits from the usual statistics:   Phase 
noise divided by sqrt of 2    and also decreased  amplitude   random 
frequency jumps.

Aging could also be average of the two.....

Predrag Dukic



From richard at karlquist.com  Thu Dec 18 20:28:38 2008
From: richard at karlquist.com (Rick Karlquist)
Date: Thu, 18 Dec 2008 12:28:38 -0800 (PST)
Subject: [time-nuts] Is oscillator sync always bad?
In-Reply-To: <7.0.1.0.1.20081218211512.01ede5d8@tapko.de>
References: <OF82CE5BA4.E295CDB3-ON85257522.006701B9-85257522.006A4527@mck.us.ray.com>
	<49496464.4000106@xtra.co.nz>
	<7.0.1.0.1.20081218211512.01ede5d8@tapko.de>
Message-ID: <0731239010587804f9cd0834325caf85.squirrel@webmail.sonic.net>

Some of Len Cutler's engineers at HP attempted to build
an ensemble of nine 10811 oscillators.  It was quite
non-trivial and I'm not sure they ever completed
the project.  I doubt whether just letting 10811's
self synchronize would result in satisfactory performance.

Rick Karlquist N6RK


Predrag Dukic wrote:
>
>
> Hi, Time -Nuts,
>
> Did anyone try to deliberately allow  syncronisation  of two
> oscillators, by , for example paralleling  outputs of two 10811.
>
> I expect to see some benefits from the usual statistics:   Phase
> noise divided by sqrt of 2    and also decreased  amplitude   random
> frequency jumps.
>
> Aging could also be average of the two.....
>
> Predrag Dukic
>
>
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>
>




From bruce.griffiths at xtra.co.nz  Thu Dec 18 20:31:36 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Fri, 19 Dec 2008 09:31:36 +1300
Subject: [time-nuts] Is oscillator sync always bad?
In-Reply-To: <7.0.1.0.1.20081218211512.01ede5d8@tapko.de>
References: <OF82CE5BA4.E295CDB3-ON85257522.006701B9-85257522.006A4527@mck.us.ray.com>	<49496464.4000106@xtra.co.nz>
	<7.0.1.0.1.20081218211512.01ede5d8@tapko.de>
Message-ID: <494AB328.9050204@xtra.co.nz>

Predrag Dukic wrote:
> Hi, Time -Nuts,
>
> Did anyone try to deliberately allow  syncronisation  of two 
> oscillators, by , for example paralleling  outputs of two 10811.
>
> I expect to see some benefits from the usual statistics:   Phase 
> noise divided by sqrt of 2    and also decreased  amplitude   random 
> frequency jumps.
>
> Aging could also be average of the two.....
>
> Predrag Dukic
>
>
>   
Pedrag

First ensure that doing this doesnt overstress the output amplifier cascade.
Then the two oscillators will need to be tuned so that they are very
close in frequency before injection locking can occur.
The higher the reverse isolation of the output amplifier and the higher
the crystal Q the closer the 2 oscillator frequencies will have to be.
The maximum frequency difference tolerable for injection locking to
occur can be estimated from Adlers equation.

Bruce


From bruce.griffiths at xtra.co.nz  Thu Dec 18 20:48:44 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Fri, 19 Dec 2008 09:48:44 +1300
Subject: [time-nuts] Is oscillator sync always bad?
In-Reply-To: <0731239010587804f9cd0834325caf85.squirrel@webmail.sonic.net>
References: <OF82CE5BA4.E295CDB3-ON85257522.006701B9-85257522.006A4527@mck.us.ray.com>	<49496464.4000106@xtra.co.nz>	<7.0.1.0.1.20081218211512.01ede5d8@tapko.de>
	<0731239010587804f9cd0834325caf85.squirrel@webmail.sonic.net>
Message-ID: <494AB72C.8070909@xtra.co.nz>

Pedrag

You may want to look at:

http://my.ece.ucsb.edu/yorklab/Publications/BioBib/84%20-%20MTT%20May%201997%20Phase%20Noise.pdf

http://repository.kulib.kyoto-u.ac.jp/dspace/bitstream/2433/49985/1/PhysRevLett_98_184101.pdf

to get some idea of the complexities involved in such a scheme if you
intend to reduce the phase noise of an ensemble of mutually coupled
oscillators.

Bruce

Rick Karlquist wrote:
> Some of Len Cutler's engineers at HP attempted to build
> an ensemble of nine 10811 oscillators.  It was quite
> non-trivial and I'm not sure they ever completed
> the project.  I doubt whether just letting 10811's
> self synchronize would result in satisfactory performance.
>
> Rick Karlquist N6RK
>
>
> Predrag Dukic wrote:
>   
>> Hi, Time -Nuts,
>>
>> Did anyone try to deliberately allow  syncronisation  of two
>> oscillators, by , for example paralleling  outputs of two 10811.
>>
>> I expect to see some benefits from the usual statistics:   Phase
>> noise divided by sqrt of 2    and also decreased  amplitude   random
>> frequency jumps.
>>
>> Aging could also be average of the two.....
>>
>> Predrag Dukic
>>
>>
>>     



From james.p.lux at jpl.nasa.gov  Thu Dec 18 21:03:31 2008
From: james.p.lux at jpl.nasa.gov (Lux, James P)
Date: Thu, 18 Dec 2008 13:03:31 -0800
Subject: [time-nuts] Is oscillator sync always bad?
In-Reply-To: <7.0.1.0.1.20081218211512.01ede5d8@tapko.de>
References: <OF82CE5BA4.E295CDB3-ON85257522.006701B9-85257522.006A4527@mck.us.ray.com>
	<49496464.4000106@xtra.co.nz>
	<7.0.1.0.1.20081218211512.01ede5d8@tapko.de>
Message-ID: <ECE7A93BD093E1439C20020FBE87C47FEB55DA8F84@ALTPHYEMBEVSP20.RES.AD.JPL>


> -----Original Message-----
> From: time-nuts-bounces at febo.com
> [mailto:time-nuts-bounces at febo.com] On Behalf Of Predrag Dukic
> Sent: Thursday, December 18, 2008 12:20 PM
> To: Discussion of precise time and frequency measurement
> Subject: [time-nuts] Is oscillator sync always bad?
>
>
>
> Hi, Time -Nuts,
>
> Did anyone try to deliberately allow  syncronisation  of two
> oscillators, by , for example paralleling  outputs of two 10811.
>
> I expect to see some benefits from the usual statistics:   Phase
> noise divided by sqrt of 2    and also decreased  amplitude   random
> frequency jumps.
>
> Aging could also be average of the two.....
>
> Predrag Dukic
>
>

 Allan, et al., did a thing with 8 small oscillators in a ring.  I don't recall if they deliberately tried to have them mutually couple, or if it was designed to try and cancel acceleration effects.


James Lux, P.E.
Task Manager, SOMD Software Defined Radios
Flight Communications Systems Section
Jet Propulsion Laboratory
4800 Oak Grove Drive, Mail Stop 161-213
Pasadena, CA, 91109
+1(818)354-2075 phone
+1(818)393-6875 fax
>


From james.p.lux at jpl.nasa.gov  Thu Dec 18 21:14:08 2008
From: james.p.lux at jpl.nasa.gov (Lux, James P)
Date: Thu, 18 Dec 2008 13:14:08 -0800
Subject: [time-nuts] Is oscillator sync always bad?
References: <OF82CE5BA4.E295CDB3-ON85257522.006701B9-85257522.006A4527@mck.us.ray.com>
	<49496464.4000106@xtra.co.nz>
	<7.0.1.0.1.20081218211512.01ede5d8@tapko.de> 
Message-ID: <ECE7A93BD093E1439C20020FBE87C47FEB55DA8F87@ALTPHYEMBEVSP20.RES.AD.JPL>



> -----Original Message-----
> From: Lux, James P
> Sent: Thursday, December 18, 2008 1:04 PM
> To: 'Discussion of precise time and frequency measurement'
> Subject: RE: [time-nuts] Is oscillator sync always bad?
>
>
>
>  Allan, et al., did a thing with 8 small oscillators in a
> ring.  I don't recall if they deliberately tried to have them
> mutually couple, or if it was designed to try and cancel
> acceleration effects.
>
>

Found the paper..

Allan, David W., Kusters, John A, and Wheatley, Charles E., III; "CTXO, Clever Time Crystal Oscillator (Clock)", 1999 Joint Meeting EFTF-IEEE IFCS

http://ieeexplore.ieee.org/iel5/6762/18075/00840780.pdf?arnumber=840780  if you have xplore access



From stijena at tapko.de  Thu Dec 18 21:16:23 2008
From: stijena at tapko.de (Predrag Dukic)
Date: Thu, 18 Dec 2008 22:16:23 +0100
Subject: [time-nuts] Is oscillator sync always bad?
In-Reply-To: <494AB328.9050204@xtra.co.nz>
References: <OF82CE5BA4.E295CDB3-ON85257522.006701B9-85257522.006A4527@mck.us.ray.com>
	<49496464.4000106@xtra.co.nz>
	<7.0.1.0.1.20081218211512.01ede5d8@tapko.de>
	<494AB328.9050204@xtra.co.nz>
Message-ID: <7.0.1.0.1.20081218221316.01ec8280@tapko.de>




Bruce,

I know the math,  and possible perils. The main question is still:

Does statistics help?  Is it going to be better?

If I do try,  I'll use a bunch of 13 MHZ TCXO's, because I have only 
3 10811, and more than 30 TCXOs.

Also with a higher number of lower quality oscs improvement  could be 
easier to see...

Predrag



At 21:31 18.12.2008, you wrote:
>Predrag Dukic wrote:
> > Hi, Time -Nuts,
> >
> > Did anyone try to deliberately allow  syncronisation  of two
> > oscillators, by , for example paralleling  outputs of two 10811.
> >
> > I expect to see some benefits from the usual statistics:   Phase
> > noise divided by sqrt of 2    and also decreased  amplitude   random
> > frequency jumps.
> >
> > Aging could also be average of the two.....
> >
> > Predrag Dukic
> >
> >
> >
>Pedrag
>
>First ensure that doing this doesnt overstress the output amplifier cascade.
>Then the two oscillators will need to be tuned so that they are very
>close in frequency before injection locking can occur.
>The higher the reverse isolation of the output amplifier and the higher
>the crystal Q the closer the 2 oscillator frequencies will have to be.
>The maximum frequency difference tolerable for injection locking to
>occur can be estimated from Adlers equation.
>
>Bruce
>
>_______________________________________________
>time-nuts mailing list -- time-nuts at febo.com
>To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>and follow the instructions there.



From stijena at tapko.de  Thu Dec 18 21:29:37 2008
From: stijena at tapko.de (Predrag Dukic)
Date: Thu, 18 Dec 2008 22:29:37 +0100
Subject: [time-nuts] Is oscillator sync always bad?
In-Reply-To: <494AB72C.8070909@xtra.co.nz>
References: <OF82CE5BA4.E295CDB3-ON85257522.006701B9-85257522.006A4527@mck.us.ray.com>
	<49496464.4000106@xtra.co.nz>
	<7.0.1.0.1.20081218211512.01ede5d8@tapko.de>
	<0731239010587804f9cd0834325caf85.squirrel@webmail.sonic.net>
	<494AB72C.8070909@xtra.co.nz>
Message-ID: <7.0.1.0.1.20081218222703.01ed0e38@tapko.de>




Bruce,

these articles are  more or less the  answer to my question.

In principle, there is obviously reduction in noise,  and the main 
concerns are uncoupled frequency difference and phase.

Thanks,

Predrag













At 21:48 18.12.2008, you wrote:
>Pedrag
>
>You may want to look at:
>
>http://my.ece.ucsb.edu/yorklab/Publications/BioBib/84%20-%20MTT%20May%201997%20Phase%20Noise.pdf
>
>http://repository.kulib.kyoto-u.ac.jp/dspace/bitstream/2433/49985/1/PhysRevLett_98_184101.pdf
>
>to get some idea of the complexities involved in such a scheme if you
>intend to reduce the phase noise of an ensemble of mutually coupled
>oscillators.
>
>Bruce
>
>Rick Karlquist wrote:
> > Some of Len Cutler's engineers at HP attempted to build
> > an ensemble of nine 10811 oscillators.  It was quite
> > non-trivial and I'm not sure they ever completed
> > the project.  I doubt whether just letting 10811's
> > self synchronize would result in satisfactory performance.
> >
> > Rick Karlquist N6RK
> >
> >
> > Predrag Dukic wrote:
> >
> >> Hi, Time -Nuts,
> >>
> >> Did anyone try to deliberately allow  syncronisation  of two
> >> oscillators, by , for example paralleling  outputs of two 10811.
> >>
> >> I expect to see some benefits from the usual statistics:   Phase
> >> noise divided by sqrt of 2    and also decreased  amplitude   random
> >> frequency jumps.
> >>
> >> Aging could also be average of the two.....
> >>
> >> Predrag Dukic
> >>
> >>
> >>
>
>
>_______________________________________________
>time-nuts mailing list -- time-nuts at febo.com
>To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>and follow the instructions there.



From stijena at tapko.de  Thu Dec 18 21:32:44 2008
From: stijena at tapko.de (Predrag Dukic)
Date: Thu, 18 Dec 2008 22:32:44 +0100
Subject: [time-nuts] Is oscillator sync always bad?
In-Reply-To: <ECE7A93BD093E1439C20020FBE87C47FEB55DA8F87@ALTPHYEMBEVSP20
	.RES.AD.JPL>
References: <OF82CE5BA4.E295CDB3-ON85257522.006701B9-85257522.006A4527@mck.us.ray.com>
	<49496464.4000106@xtra.co.nz>
	<7.0.1.0.1.20081218211512.01ede5d8@tapko.de>
	<ECE7A93BD093E1439C20020FBE87C47FEB55DA8F87@ALTPHYEMBEVSP20.RES.AD.JPL>
Message-ID: <7.0.1.0.1.20081218223143.01e78330@tapko.de>




Lux,

It is one more confimation that my assumption is valid.

Thanks for the link,


Predrag



At 22:14 18.12.2008, you wrote:


> > -----Original Message-----
> > From: Lux, James P
> > Sent: Thursday, December 18, 2008 1:04 PM
> > To: 'Discussion of precise time and frequency measurement'
> > Subject: RE: [time-nuts] Is oscillator sync always bad?
> >
> >
> >
> >  Allan, et al., did a thing with 8 small oscillators in a
> > ring.  I don't recall if they deliberately tried to have them
> > mutually couple, or if it was designed to try and cancel
> > acceleration effects.
> >
> >
>
>Found the paper..
>
>Allan, David W., Kusters, John A, and Wheatley, Charles E., III; 
>"CTXO, Clever Time Crystal Oscillator (Clock)", 1999 Joint Meeting 
>EFTF-IEEE IFCS
>
>http://ieeexplore.ieee.org/iel5/6762/18075/00840780.pdf?arnumber=840780 
>if you have xplore access
>
>
>_______________________________________________
>time-nuts mailing list -- time-nuts at febo.com
>To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>and follow the instructions there.



From james.p.lux at jpl.nasa.gov  Thu Dec 18 22:00:28 2008
From: james.p.lux at jpl.nasa.gov (Lux, James P)
Date: Thu, 18 Dec 2008 14:00:28 -0800
Subject: [time-nuts] Is oscillator sync always bad?
In-Reply-To: <7.0.1.0.1.20081218223143.01e78330@tapko.de>
References: <OF82CE5BA4.E295CDB3-ON85257522.006701B9-85257522.006A4527@mck.us.ray.com>
	<49496464.4000106@xtra.co.nz>	<7.0.1.0.1.20081218211512.01ede5d8@tapko.de>
	<ECE7A93BD093E1439C20020FBE87C47FEB55DA8F87@ALTPHYEMBEVSP20.RES.AD.JPL>
	<7.0.1.0.1.20081218223143.01e78330@tapko.de>
Message-ID: <ECE7A93BD093E1439C20020FBE87C47FEB55DA8F9A@ALTPHYEMBEVSP20.RES.AD.JPL>


>
> Lux,
>
> It is one more confimation that my assumption is valid.

In fact, they comment about the potential problem of injection locking..

> > >  Allan, et al., did a thing with 8 small oscillators in a
> ring.  I
> > > don't recall if they deliberately tried to have them mutually
> > > couple, or if it was designed to try and cancel acceleration
> > > effects.
> > >
> > >


From gwinn at raytheon.com  Thu Dec 18 22:20:07 2008
From: gwinn at raytheon.com (Joseph M Gwinn)
Date: Thu, 18 Dec 2008 17:20:07 -0500
Subject: [time-nuts] Sub Pico Second Phase logger
In-Reply-To: <49496464.4000106@xtra.co.nz>
Message-ID: <OF924BE3BD.9F59CEBF-ON85257523.00798D32-85257523.007AB142@mck.us.ray.com>

Bruce,

time-nuts-bounces at febo.com wrote on 12/17/2008 03:43:16 PM:

> Joe
> 
> Joseph M Gwinn wrote:
> > Bruce,
> >
> >
> > time-nuts-bounces at febo.com wrote on 12/16/2008 10:21:55 PM:
> >
[snip]
> > 
> >> [BG] Obtaining suitable mixers for 5MHz and 10MHz input frequencies 
or even 
> >> 100MHz is easy.
> > 
> >> However for the higher microwave frequencies most mixers come 
complete
> >> with connectors attached and share a common ground.
> >> 
> >
> > [JG] True.  However, I don't think we will be going from 1 GHz to 1 Hz 
in a 
> > single step, and the last mixer can have separate grounds.
> >
> >
> > 
> An upper limit of at least 100MHz should be feasible for the final 
mixer.
> A dual conversion scheme will be essential if one uses a triple balanced
> or similar first mixer that has an IF response that doesn't extend down
> to the low frequencies that a sound card can use.

Yes.  We will see if it's needed.


> > 
> >> [BG] If we can devise a suitable test setup then one could just log 
the
> >> samples to a file for whatever sound card one has and make the data
> >> available to others for analysis.
> >> 
> >
> > Yes.
> >
> >
> > 
> >> This allows a wide variety of sound cards to be evaluated without one
> >> person having to test them all.
> >> 
> >
> > And evaluation of the same test data by multiple people usingdifferent 

> > tools also allows us to distinguish test artifacts from processing 
> > artifacts.
> >
> 
> [BG] Proposed test setup:
> (preliminary to be refined)
> 
> Drive 2 sound card inputs in parallel with the same source.
> 
> Source amplitude:
> Max sound card input -3dB

What kind of dB?

 
> Sources:
> 
> 1) Wien bridge or equivalent (eg state variable oscillator with soft
> clamping) relatively low distortion oscillator.
> 
> 2) Buffered low pass filtered output of binary divider driven by a
> crystal oscillator

RC oscillator sounds far simpler and more flexible.

 
> Test frequencies:
> 
> 100Hz
> 
> 1kHz

Why no 10 Hz?  (Well, 20 Hz.)

 
> Sound card sample rate:
> 
> ~24KSPS

I assume that this is the lowest rate supported, and certainly is overkill 
for 1 KHz.

 
> Test duration:
> 
> 1000 sec

At least initially, but we will need longer datasets to see thermal 
effects clearly.

 
> File format:
> 
> Wave file??
> Resolution 24 bits for 24 bit sound cards, 16 bits for 16bit and lower
> resolution sound cards, etc.
> 
> Some refinement of sample rates and test duration is required to keep
> the data file sizes manageable.
> With a 24 bit sound card sampling at 96KSPS or 192KSPS for 1000sec can
> produce file sizes of 1GB or more.
> Some preprocessing (low pass filter and decimation) may also be 
required.

I agree that a simple preprocessor will be needed.  This would be the 
place to convert from the raw adc 16 or 24 bit format into something 
universal, perhaps 24 bit or 32 bit (with zero padding as needed).  It 
probably should be written in C, for speed and portability.  I expect that 
there are open-source libraries available to read and write wav files, and 
many analysis programs will accept wav.  However, it would be easy to make 
the preprocesor able to emit other formats as needed. 


From gwinn at raytheon.com  Thu Dec 18 23:00:15 2008
From: gwinn at raytheon.com (Joseph M Gwinn)
Date: Thu, 18 Dec 2008 18:00:15 -0500
Subject: [time-nuts] Sub Pico Second Phase logger
In-Reply-To: <49498A88.30106@xtra.co.nz>
Message-ID: <OF52F05A31.850FDF2D-ON85257523.007B0E75-85257523.007E5E01@mck.us.ray.com>

Bruce,


time-nuts-bounces at febo.com wrote on 12/17/2008 06:26:00 PM:

[snip]
> >
> >
> > 
> >> [BG] It isn't necessary to use a pair of mixers and an offset source 
to
> >> characterise the sound card, driving both sound card inputs from the
> >> same audio source should suffice.
> >> 
> >
> > [JG] Yes.  One input at a time, with the other input shorted, so we 
can also 
> > see the crosstalk.
> >
> >
> > 
> >> The audio source need not have low ultra low distortion (the IF 
output
> >> signals in a dual mixer system won't have ultra low distortion) or 
very
> >> high frequency stability (the IF output signals in a dual mixer 
system
> >> won't necessarily have particularly high frequency stability).
> >> 
> >
> > But ... but ... but ... I thought Time Nuts used only atomic frequency 

> > refs, and crystals only if oven stabilized.
> >
> > 
> If one mixes down a 10MHz source to 100Hz the fractional frequency
> instability (of the beat frequency) is magnified by a factor of 1E5 over
> that of the 10MHz source.
> This assumes that the offset source has significantly lower instability
> than the source under test.
> In the special case when the offset source and the test source are phase
> locked the offset frequency will have much greater stability.

Yes.  One approach is to use the two 10 MHz signals as the clocks of a 
pair of DDS chips programmed to generate ~ 1MHz and ~1 MHz + 10 Hz.  When 
mixed, these will yield a 10 Hz difference signal.

The same game can be performed in the software driving a soundcard, as 
discussed later.


> >> A standard RC audio oscillator with distortion lower than 1% or so
> >> should suffice.
> >> At least the resultant frequency fluctuations should thoroughly 
exercise
> >> the phase extraction algorithms.
> >>
> >> Another option would be to low pass filter the output of a divider.
> >> Using a sound card to generate the test signal is also possible but 
it
> >> can potentially introduce extraneous noise and other artifacts such 
as
> >> phase truncation spurs.
> >> 
> >
> > If one chooses the test frequencies correctly, one can eliminate the 
> > spurs.  The trick is to choose frequencies that lead to DDS tuning 
words 
> > that have zeroes in the accumulator bits that are truncated (that is, 
do 
> > not make it into the sin/cos lookup table).
> >
> >
> > 
> This just adds another layer of complexity for little immediate gain.
> Making the algorithms robust against small drifts in beat frequency is
> more useful in the general case (when 2 different test sources are being
> compared) than just assuming that the the beat frequency is very stable
> and fixed.

Yes, but I'm not sure we are solving the same problem.

I suppose the sound card could drive a simple PLL signal cleanup circuit.


> > Step one of planning an experiment is to decide on the objectives. The 

> > large scale objective is to determine which sound cards are suitable 
for a 
> > number of time-related tasks, so we should enumerate and describe 
these 
> > tasks. 
> >
> > Task 1.  The immediate task is to receive and digitize the sinewave 
output 
> > from a mixer, the sinewave being the offset frequency coming out of a 
DMTD 
> > apparatus. Offset frequencies will range from 10 Hz to 1 KHz, will be 
> > known with great precision from the design of the apparatus, and need 
not 
> > be measured.  This sinewave is high amplitude (at least one volt rms, 
> > matched to the needs of the soundcard) and very high SNR.  This will 
be 
> > done in two channels in parallel.  The signals are at the same 
frequency 
> > but differ in phase.  The intent is to extract the phases of these two 

> > sinewaves, the difference in phase being the ultimate output.The phase 

> > of a signal will be extracted by least-squares fitting of a sine 
function 
> > to the measured data.
> >
> > And so on.  We need to list the tasks, and to use this task list to 
inform 
> > the experiment design.
> >
> >
> > 
> The immediate task is actually to evaluate sound cards for their
> suitability, preferably without the added cost and complexity of a DDS
> LO and mixer.

Suitability for what?  That is the point of enumerating tasks.

I don't see where Task 1 above requires or even mentions a specific 
implementation, such as a DDS LO and mixer.


> Once this evaluation is done, using a mixer and a DDS based LO to
> generate a beat frequency is the next step.
> Eliminating the mixer and DDS allows a greater number of participants at
> this stage than would otherwise be the case.

True.


> 10Hz resolution whilst avoiding phase truncation spurs is impractical
> with a DDS chip by itself.
> Depending on the DDS and its clock frequency, the frequency spacing of
> phase truncation spur free outputs may be as large as several kHz.

Is this true of concatenated DDS chips?  I recall a patent to the 
contrary.


> A few divide and mix stages will be required to achieve a spur free
> resolution of 10Hz.

That is a traditional approach.  But are there alternate approaches that 
have now become practical?

 
> A DDS chip with higher resolution phase outputs after truncation such as
> the AD99XX series are better in this respect than the earlier 
> AD98XX series.

Absolutely.

Actually, if we use a sound card to generate the test signals, the "DDS" 
will be a bit of non-realtime math code in our computers.  If we choose 
the sample window size and test frequency correctly, we can arrange for 
very low spurs and other errors.  The spur reduction is largely due to the 
fact that being offline one can use all of the phase bits to compute 
sin/cos values, rather than truncating phase to say 14 bits. 

The algorithm is something like this:  Figure out how many samples there 
will be per cycle of the test frequency.  Adjust test frequency slightly 
to eliminate any residue.  Compute a full cycle of exact phase values. 

From bogus@does.not.exist.com  Wed Dec  3 18:34:25 2008
From: bogus@does.not.exist.com ()
Date: Wed, 03 Dec 2008 18:34:25 -0000
Subject: No subject
Message-ID: <mailman.4.1229641236.2496.time-nuts@febo.com>

full-precision sine function.  Fill the drive file with multiple copies of 
this one-cycle file placed nose-to-tail.  Feed to soundcard hardware.  If 
the soundcard has some kind of buffer and buffer-repeat function, one can 
eliminate generation of the big file.

This kind of software approach would eliminate a whole lot of uncommon 
hardware, so we really ought to see if it can be made to work well enough 
for our purposes, as it would be such a big win.


> To broaden participation we need to broaden the scope of the project to
> include dual mixer system with statistically independent test sources as
> well as the more specialised case where the 2 input frequencies differ
> only in phase.
> 
> 1) Evaluate sound cards for suitablility.
> Initially use simple less stable sources and follow up with more stable
> test sources for the more promising cards.
> Need to measure crosstalk, temporal instability of interchannel phase
> shift, system noise etc.

Generally agree, but there is that undefined elastic term "suitability" 
again.

 
> 2) Develop robust algorithms for phase extraction.
> Use the data produced by the less stable sources and that produced by
> the more stable sources

Agree.

 
> 3) Repeat testing using a dual mixer system complete with offset LO.
> Test frequencies identical to evaluate system noise floor.
> 
> 4) Repeat testing using a dual mixer system complete with offset LO.
> Test frequencies differ to help the effect of residual crosstalk and
> other artifacts.
> 
> 5) Split the project into 2 branches:
> A) where mixer inputs differ only by a phase shift to be measured.
> Useful for measuring effect on ADEV of various components and their
> phase shift tempcos etc.
> 
> B) Where the mixer input test sources are statistically independent.
> Useful for measuring pairwise source ADEV etc.

Although these are likely future directions, we probably should focus on 
your Tasks 1 and 2 for now, and see how much we can wring out of commonly 
available soundcards.  Tasks 3 et seq may change depending on the results 
of 1 and 2.

Our two Task 1 items appear to be compatible.

Joe


From bruce.griffiths at xtra.co.nz  Thu Dec 18 23:17:33 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Fri, 19 Dec 2008 12:17:33 +1300
Subject: [time-nuts] Sub Pico Second Phase logger
In-Reply-To: <OF924BE3BD.9F59CEBF-ON85257523.00798D32-85257523.007AB142@mck.us.ray.com>
References: <OF924BE3BD.9F59CEBF-ON85257523.00798D32-85257523.007AB142@mck.us.ray.com>
Message-ID: <494ADA0D.3060004@xtra.co.nz>

Joe

Joseph M Gwinn wrote:
> Bruce,
>
> time-nuts-bounces at febo.com wrote on 12/17/2008 03:43:16 PM:
>
>   
>> Joe
>>
>> Joseph M Gwinn wrote:
>>     
>>> Bruce,
>>>
>>>
>>> time-nuts-bounces at febo.com wrote on 12/16/2008 10:21:55 PM:
>>>
>>>       
> [snip]
>   
>>>> [BG] Obtaining suitable mixers for 5MHz and 10MHz input frequencies 
>>>>         
> or even 
>   
>>>> 100MHz is easy.
>>>>         
>>>> However for the higher microwave frequencies most mixers come 
>>>>         
> complete
>   
>>>> with connectors attached and share a common ground.
>>>>
>>>>         
>>> [JG] True.  However, I don't think we will be going from 1 GHz to 1 Hz 
>>>       
> in a 
>   
>>> single step, and the last mixer can have separate grounds.
>>>
>>>
>>>
>>>       
>> An upper limit of at least 100MHz should be feasible for the final 
>>     
> mixer.
>   
>> A dual conversion scheme will be essential if one uses a triple balanced
>> or similar first mixer that has an IF response that doesn't extend down
>> to the low frequencies that a sound card can use.
>>     
>
> Yes.  We will see if it's needed.
>
>
>   
>>>> [BG] If we can devise a suitable test setup then one could just log 
>>>>         
> the
>   
>>>> samples to a file for whatever sound card one has and make the data
>>>> available to others for analysis.
>>>>
>>>>         
>>> Yes.
>>>
>>>
>>>
>>>       
>>>> This allows a wide variety of sound cards to be evaluated without one
>>>> person having to test them all.
>>>>
>>>>         
>>> And evaluation of the same test data by multiple people usingdifferent 
>>>       
>
>   
>>> tools also allows us to distinguish test artifacts from processing 
>>> artifacts.
>>>
>>>       
>> [BG] Proposed test setup:
>> (preliminary to be refined)
>>
>> Drive 2 sound card inputs in parallel with the same source.
>>
>> Source amplitude:
>> Max sound card input -3dB
>>     
>
> What kind of dB?
>
>   
Peak input signal voltage = 70% of sound card maximum peak input voltage.
Just to leave some margin for gain tolerances.

>  
>   
>> Sources:
>>
>> 1) Wien bridge or equivalent (eg state variable oscillator with soft
>> clamping) relatively low distortion oscillator.
>>
>> 2) Buffered low pass filtered output of binary divider driven by a
>> crystal oscillator
>>     
>
> RC oscillator sounds far simpler and more flexible.
>
>   

A Wien bridge using a lamp is perhaps the simplest.
I'll create a circuit schematics for this using an OPA2134 (dual lowish
noise JFET opamp).
One opamp for the oscillator one to drive the sound card (attenuation of
the oscillator output will be required for some sound cards and it is
desirable to have a low output impedance driver).

>  
>   
>> Test frequencies:
>>
>> 100Hz
>>
>> 1kHz
>>     
>
> Why no 10 Hz?  (Well, 20 Hz.)
>
>   
No particular reason other than some complications if a lamp stabilised
oscillator is used.
A diode soft (series R) clamped RC oscillator is more flexible in this
regard.
I'll also produce a circuit schematic for one of these oscillators.
>  
>   
>> Sound card sample rate:
>>
>> ~24KSPS
>>     
>
> I assume that this is the lowest rate supported, and certainly is overkill 
> for 1 KHz.
>
>   
It varies with the sound card.
I just suggested that for a starting point in the discussion.

For an AP192 the directly (without sample rate interpolation) available
output sample rates are:

192, 96, 64, 48, 32, 8 KSPS.
>  
>   
>> Test duration:
>>
>> 1000 sec
>>     
>
> At least initially, but we will need longer datasets to see thermal 
> effects clearly.
>
>   

>> File format:
>>
>> Wave file??
>> Resolution 24 bits for 24 bit sound cards, 16 bits for 16bit and lower
>> resolution sound cards, etc.
>>
>> Some refinement of sample rates and test duration is required to keep
>> the data file sizes manageable.
>> With a 24 bit sound card sampling at 96KSPS or 192KSPS for 1000sec can
>> produce file sizes of 1GB or more.
>> Some preprocessing (low pass filter and decimation) may also be 
>>     
> required.
>
> I agree that a simple preprocessor will be needed.  This would be the 
> place to convert from the raw adc 16 or 24 bit format into something 
> universal, perhaps 24 bit or 32 bit (with zero padding as needed).  It 
> probably should be written in C, for speed and portability.  I expect that 
> there are open-source libraries available to read and write wav files, and 
> many analysis programs will accept wav.  However, it would be easy to make 
> the preprocesor able to emit other formats as needed. 
>
>   

Bruce


From bruce.griffiths at xtra.co.nz  Thu Dec 18 23:48:27 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Fri, 19 Dec 2008 12:48:27 +1300
Subject: [time-nuts] Sub Pico Second Phase logger
In-Reply-To: <OF52F05A31.850FDF2D-ON85257523.007B0E75-85257523.007E5E01@mck.us.ray.com>
References: <OF52F05A31.850FDF2D-ON85257523.007B0E75-85257523.007E5E01@mck.us.ray.com>
Message-ID: <494AE14B.2050405@xtra.co.nz>

Joe

Joseph M Gwinn wrote:
> Bruce,
>
>
> time-nuts-bounces at febo.com wrote on 12/17/2008 06:26:00 PM:
>
> [snip]
>   
>>>
>>>       
>>>> [BG] It isn't necessary to use a pair of mixers and an offset source 
>>>>         
> to
>   
>>>> characterise the sound card, driving both sound card inputs from the
>>>> same audio source should suffice.
>>>>
>>>>         
>>> [JG] Yes.  One input at a time, with the other input shorted, so we 
>>>       
> can also 
>   
>>> see the crosstalk.
>>>
>>>
>>>
>>>       
>>>> The audio source need not have low ultra low distortion (the IF 
>>>>         
> output
>   
>>>> signals in a dual mixer system won't have ultra low distortion) or 
>>>>         
> very
>   
>>>> high frequency stability (the IF output signals in a dual mixer 
>>>>         
> system
>   
>>>> won't necessarily have particularly high frequency stability).
>>>>
>>>>         
>>> But ... but ... but ... I thought Time Nuts used only atomic frequency 
>>>       
>
>   
>>> refs, and crystals only if oven stabilized.
>>>
>>>
>>>       
>> If one mixes down a 10MHz source to 100Hz the fractional frequency
>> instability (of the beat frequency) is magnified by a factor of 1E5 over
>> that of the 10MHz source.
>> This assumes that the offset source has significantly lower instability
>> than the source under test.
>> In the special case when the offset source and the test source are phase
>> locked the offset frequency will have much greater stability.
>>     
>
> Yes.  One approach is to use the two 10 MHz signals as the clocks of a 
> pair of DDS chips programmed to generate ~ 1MHz and ~1 MHz + 10 Hz.  When 
> mixed, these will yield a 10 Hz difference signal.
>
> The same game can be performed in the software driving a soundcard, as 
> discussed later.
>
>
>   
>>>> A standard RC audio oscillator with distortion lower than 1% or so
>>>> should suffice.
>>>> At least the resultant frequency fluctuations should thoroughly 
>>>>         
> exercise
>   
>>>> the phase extraction algorithms.
>>>>
>>>> Another option would be to low pass filter the output of a divider.
>>>> Using a sound card to generate the test signal is also possible but 
>>>>         
> it
>   
>>>> can potentially introduce extraneous noise and other artifacts such 
>>>>         
> as
>   
>>>> phase truncation spurs.
>>>>
>>>>         
>>> If one chooses the test frequencies correctly, one can eliminate the 
>>> spurs.  The trick is to choose frequencies that lead to DDS tuning 
>>>       
> words 
>   
>>> that have zeroes in the accumulator bits that are truncated (that is, 
>>>       
> do 
>   
>>> not make it into the sin/cos lookup table).
>>>
>>>
>>>
>>>       
>> This just adds another layer of complexity for little immediate gain.
>> Making the algorithms robust against small drifts in beat frequency is
>> more useful in the general case (when 2 different test sources are being
>> compared) than just assuming that the the beat frequency is very stable
>> and fixed.
>>     
>
> Yes, but I'm not sure we are solving the same problem.
>
> I suppose the sound card could drive a simple PLL signal cleanup circuit.
>
>
>   
One potential problem with using a sound card for a test source is that
the output DAC may share the same clock as the ADC ensuring that the
output signal is locked to the ADC sampling rate.
In an actual dual mixer system the beat frequency and the ADC clock wont
necessarily be synchronised (its difficult to lock the sampling clock of
most sound cards to an external reference).

If one isnt careful the algorithms developed may work well when the ADC
sample clock and the test frequencies are locked, but have problems when
they are not.


Using a second sound card to generate the test signal may overcome this
problem at increased cost, and for some it may not even be an option.

>>> Step one of planning an experiment is to decide on the objectives. The 
>>>       
>
>   
>>> large scale objective is to determine which sound cards are suitable 
>>>       
> for a 
>   
>>> number of time-related tasks, so we should enumerate and describe 
>>>       
> these 
>   
>>> tasks. 
>>>
>>> Task 1.  The immediate task is to receive and digitize the sinewave 
>>>       
> output 
>   
>>> from a mixer, the sinewave being the offset frequency coming out of a 
>>>       
> DMTD 
>   
>>> apparatus. Offset frequencies will range from 10 Hz to 1 KHz, will be 
>>> known with great precision from the design of the apparatus, and need 
>>>       
> not 
>   
>>> be measured.  This sinewave is high amplitude (at least one volt rms, 
>>> matched to the needs of the soundcard) and very high SNR.  This will 
>>>       
> be 
>   
>>> done in two channels in parallel.  The signals are at the same 
>>>       
> frequency 
>   
>>> but differ in phase.  The intent is to extract the phases of these two 
>>>       
>
>   
>>> sinewaves, the difference in phase being the ultimate output.The phase 
>>>       
>
>   
>>> of a signal will be extracted by least-squares fitting of a sine 
>>>       
> function 
>   
>>> to the measured data.
>>>
>>> And so on.  We need to list the tasks, and to use this task list to 
>>>       
> inform 
>   
>>> the experiment design.
>>>
>>>
>>>
>>>       
>> The immediate task is actually to evaluate sound cards for their
>> suitability, preferably without the added cost and complexity of a DDS
>> LO and mixer.
>>     
>
> Suitability for what?  That is the point of enumerating tasks.
>
>   
Suitability for use in a dual mixer system.
> I don't see where Task 1 above requires or even mentions a specific 
> implementation, such as a DDS LO and mixer.
>
>
>   
>> Once this evaluation is done, using a mixer and a DDS based LO to
>> generate a beat frequency is the next step.
>> Eliminating the mixer and DDS allows a greater number of participants at
>> this stage than would otherwise be the case.
>>     
>
> True.
>
>
>   
>> 10Hz resolution whilst avoiding phase truncation spurs is impractical
>> with a DDS chip by itself.
>> Depending on the DDS and its clock frequency, the frequency spacing of
>> phase truncation spur free outputs may be as large as several kHz.
>>     
>
> Is this true of concatenated DDS chips?  I recall a patent to the 
> contrary.
>
>
>   
Which patent?
If the zero crossings are time stamped and do not occur simultaneously
in each channel then the phase noise of the offset oscillator will
affect the measurement.
>> A few divide and mix stages will be required to achieve a spur free
>> resolution of 10Hz.
>>     
>
> That is a traditional approach.  But are there alternate approaches that 
> have now become practical?
>
>   
Diophantine frequency synthesis?
>  
>   
>> A DDS chip with higher resolution phase outputs after truncation such as
>> the AD99XX series are better in this respect than the earlier 
>> AD98XX series.
>>     
>
> Absolutely.
>
> Actually, if we use a sound card to generate the test signals, the "DDS" 
> will be a bit of non-realtime math code in our computers.  If we choose 
> the sample window size and test frequency correctly, we can arrange for 
> very low spurs and other errors.  The spur reduction is largely due to the 
> fact that being offline one can use all of the phase bits to compute 
> sin/cos values, rather than truncating phase to say 14 bits. 
>
> The algorithm is something like this:  Figure out how many samples there 
> will be per cycle of the test frequency.  Adjust test frequency slightly 
> to eliminate any residue.  Compute a full cycle of exact phase values. 
> >From these phase values, compute the corresponding signal voltages using a 
> full-precision sine function.  Fill the drive file with multiple copies of 
> this one-cycle file placed nose-to-tail.  Feed to soundcard hardware.  If 
> the soundcard has some kind of buffer and buffer-repeat function, one can 
> eliminate generation of the big file.
>
> This kind of software approach would eliminate a whole lot of uncommon 
> hardware, so we really ought to see if it can be made to work well enough 
> for our purposes, as it would be such a big win.
>
>
>   
>> To broaden participation we need to broaden the scope of the project to
>> include dual mixer system with statistically independent test sources as
>> well as the more specialised case where the 2 input frequencies differ
>> only in phase.
>>
>> 1) Evaluate sound cards for suitablility.
>> Initially use simple less stable sources and follow up with more stable
>> test sources for the more promising cards.
>> Need to measure crosstalk, temporal instability of interchannel phase
>> shift, system noise etc.
>>     
>
> Generally agree, but there is that undefined elastic term "suitability" 
> again.
>
>   
Replace suitability with:
Measure the characteristics of a sound card that affect the performance
when used in a dual mixer system used to measure the relative phases of
a pair of RF signals.
Where the pair of RF signals may either

1) originate from 2 statistically independent sources (OCXOs, GPSDO's etc)

OR

2) originate from the same source and just differ in phase.
>  
>   
>> 2) Develop robust algorithms for phase extraction.
>> Use the data produced by the less stable sources and that produced by
>> the more stable sources
>>     
>
> Agree.
>
>  
>   
>> 3) Repeat testing using a dual mixer system complete with offset LO.
>> Test frequencies identical to evaluate system noise floor.
>>
>> 4) Repeat testing using a dual mixer system complete with offset LO.
>> Test frequencies differ to help the effect of residual crosstalk and
>> other artifacts.
>>
>> 5) Split the project into 2 branches:
>> A) where mixer inputs differ only by a phase shift to be measured.
>> Useful for measuring effect on ADEV of various components and their
>> phase shift tempcos etc.
>>
>> B) Where the mixer input test sources are statistically independent.
>> Useful for measuring pairwise source ADEV etc.
>>     
>
> Although these are likely future directions, we probably should focus on 
> your Tasks 1 and 2 for now, and see how much we can wring out of commonly 
> available soundcards.  Tasks 3 et seq may change depending on the results 
> of 1 and 2.
>
> Our two Task 1 items appear to be compatible.
>
> Joe
>
>   
Bruce


From joegwinn at comcast.net  Fri Dec 19 01:22:57 2008
From: joegwinn at comcast.net (Joe Gwinn)
Date: Thu, 18 Dec 2008 20:22:57 -0500
Subject: [time-nuts] Sub Pico Second Phase logger
Message-ID: <p06240800c570a5b846fd@[192.168.1.212]>

This is from home.  I'll not be at work until next year.

At 11:48 PM +0000 12/18/08, time-nuts-request at febo.com wrote:
>Message: 4
>Date: Fri, 19 Dec 2008 12:17:33 +1300
>From: Bruce Griffiths <bruce.griffiths at xtra.co.nz>
>Subject: Re: [time-nuts] Sub Pico Second Phase logger
>To: Discussion of precise time and frequency measurement
>	<time-nuts at febo.com>
>Message-ID: <494ADA0D.3060004 at xtra.co.nz>
>Content-Type: text/plain; charset=ISO-8859-1
>
>Joe
>
>
>  >>>      
>>>  [BG] Proposed test setup:
>>>  (preliminary to be refined)
>>>
>>>  Drive 2 sound card inputs in parallel with the same source.
>>>
>>>  Source amplitude:
>>>  Max sound card input -3dB
>>>    
>>
>>  What kind of dB?
>>
>>  
>Peak input signal voltage = 70% of sound card maximum peak input voltage.
>Just to leave some margin for gain tolerances.

OK.


>  >> Sources:
>>>
>>>  1) Wien bridge or equivalent (eg state variable oscillator with soft
>>>  clamping) relatively low distortion oscillator.
>>>
>>>  2) Buffered low pass filtered output of binary divider driven by a
>>>  crystal oscillator
>>>    
>>
>  > RC oscillator sounds far simpler and more flexible.
>
>A Wien bridge using a lamp is perhaps the simplest.
>I'll create a circuit schematics for this using an OPA2134 (dual lowish
>noise JFET opamp).
>One opamp for the oscillator one to drive the sound card (attenuation of
>the oscillator output will be required for some sound cards and it is
>desirable to have a low output impedance driver).

Jim Williams of Linear Technology had a very good low-distortion AGC 
controlled Wein Bridge oscillator.  If I recall, he used a photo-FET 
or the like as the servoed resistor in the bridge.  There may be an 
application note on the LT website, but I saw it in a chapter of a 
book on analog circuitry, the chapter author being Jim W.


>  >> Test frequencies:
>>>
>>>  100Hz
>>>
>>>  1kHz
>>>    
>>
>>  Why no 10 Hz?  (Well, 20 Hz.)
>>
>>  
>No particular reason other than some complications if a lamp stabilised
>oscillator is used.
>A diode soft (series R) clamped RC oscillator is more flexible in this
>regard.
>I'll also produce a circuit schematic for one of these oscillators.

Jim Williams' circuit would handle 10 Hz if I recall.


>  >> Sound card sample rate:
>>>
>>>  ~24KSPS
>>>    
>>
>>  I assume that this is the lowest rate supported, and certainly is overkill
>>  for 1 KHz.
>>
>>  
>It varies with the sound card.
>I just suggested that for a starting point in the discussion.
>
>For an AP192 the directly (without sample rate interpolation) available
>output sample rates are:
>
>192, 96, 64, 48, 32, 8 KSPS.

OK.  I would start with 8 ksps.  We will end up decimating below that 
anyway, except for 1 KHz test signals.


Joe


From joegwinn at comcast.net  Fri Dec 19 01:46:50 2008
From: joegwinn at comcast.net (Joe Gwinn)
Date: Thu, 18 Dec 2008 20:46:50 -0500
Subject: [time-nuts] Sub Pico Second Phase logger
Message-ID: <p06240801c570a811d3c9@[192.168.1.212]>

At 11:48 PM +0000 12/18/08, time-nuts-request at febo.com wrote:
>
>Message: 5
>Date: Fri, 19 Dec 2008 12:48:27 +1300
>From: Bruce Griffiths <bruce.griffiths at xtra.co.nz>
>Subject: Re: [time-nuts] Sub Pico Second Phase logger
>To: Discussion of precise time and frequency measurement
>	<time-nuts at febo.com>
>Message-ID: <494AE14B.2050405 at xtra.co.nz>
>Content-Type: text/plain; charset=ISO-8859-1
>
>[snip]
>
>  >>>      
>>>  This just adds another layer of complexity for little immediate gain.
>>>  Making the algorithms robust against small drifts in beat frequency is
>>>  more useful in the general case (when 2 different test sources are being
>>>  compared) than just assuming that the the beat frequency is very stable
>>>  and fixed.
>>>    
>>
>>  Yes, but I'm not sure we are solving the same problem.
>>
>>  I suppose the sound card could drive a simple PLL signal cleanup circuit.
>>
>>
>>  
>One potential problem with using a sound card for a test source is that
>the output DAC may share the same clock as the ADC ensuring that the
>output signal is locked to the ADC sampling rate.

True.  I would expect everything on a given card to use the same clock.


>In an actual dual mixer system the beat frequency and the ADC clock won't
>necessarily be synchronised (it's difficult to lock the sampling clock of
>most sound cards to an external reference).

Maybe impossible.  While stuff used by the Broadcast folk probably 
does accept external sync, it may as well be made of purest beaten 
Gold.


>If one isn't careful the algorithms developed may work well when the ADC
>sample clock and the test frequencies are locked, but have problems when
>they are not.

True.


>Using a second sound card to generate the test signal may overcome this
>problem at increased cost, and for some it may not even be an option.

It may not work with PCI soundcards, as the card clock may be 
synchronized to the PCI bus clock.  Firewire/USB cards will have 
their own independent clocks.


>[snip]
>  >>>      
>>>  The immediate task is actually to evaluate sound cards for their
>>>  suitability, preferably without the added cost and complexity of a DDS
>>>  LO and mixer.
>>>    
>>
>>  Suitability for what?  That is the point of enumerating tasks.
>>
>>  
>Suitability for use in a dual mixer system.

Ah.


>  >> 10Hz resolution whilst avoiding phase truncation spurs is impractical
>>>  with a DDS chip by itself.
>>>  Depending on the DDS and its clock frequency, the frequency spacing of
>>>  phase truncation spur free outputs may be as large as several kHz.
>>>    
>>
>>  Is this true of concatenated DDS chips?  I recall a patent to the
>  > contrary.
>  >  
>Which patent?

Hmm.  It's at work.  I'll look it up in January.  As I recall, the 
second DDS made a small integer conversion, and so had low spurs, 
while the first DDS was set to whatever was needed.


>If the zero crossings are time stamped and do not occur simultaneously
>in each channel then the phase noise of the offset oscillator will
>affect the measurement.

I'm not following.  Please expand.  The zero crossings are never 
aligned unless there is no phase delay.


>  >> A few divide and mix stages will be required to achieve a spur free
>>>  resolution of 10Hz.
>>>    
>>
>>  That is a traditional approach.  But are there alternate approaches that
>>  have now become practical?
>>
>>
>Diophantine frequency synthesis?

 From the sound of the name I think so, at least in the last DDS 
stage, as done by that patent.

But I was fishing.


>  >  
>>>  To broaden participation we need to broaden the scope of the project to
>>>  include dual mixer system with statistically independent test sources as
>>>  well as the more specialised case where the 2 input frequencies differ
>>>  only in phase.
>>>
>>>  1) Evaluate sound cards for suitablility.
>>>  Initially use simple less stable sources and follow up with more stable
>>>  test sources for the more promising cards.
>>>  Need to measure crosstalk, temporal instability of interchannel phase
>>>  shift, system noise etc.
>>>    
>>
>>  Generally agree, but there is that undefined elastic term "suitability"
>  > again.
>>
>>  
>Replace suitability with:
>Measure the characteristics of a sound card that affect the performance
>when used in a dual mixer system used to measure the relative phases of
>a pair of RF signals.
>Where the pair of RF signals may either:
>
>1) originate from 2 statistically independent sources (OCXOs, GPSDO's etc)
>
>OR
>
>2) originate from the same source and just differ in phase.

That covers it for sure.



From BriMDavis at aol.com  Fri Dec 19 03:40:41 2008
From: BriMDavis at aol.com (BriMDavis at aol.com)
Date: Thu, 18 Dec 2008 22:40:41 EST
Subject: [time-nuts] Build my own dist. amp ??
Message-ID: <bde.3adc3a86.367c71b9@aol.com>

Bruce Griffiths wrote:
>
>That is a very effective way of elevating the phase noise floor.
>Its usually far better to amplify the input and then split the output
>maintaining a gain to the splitter outputs of at least 0dB.
>
As I already explained the last time you mentioned this, 
I am well aware of noise floor limitations when operating 
an LO or clock at reduced signal levels.
 
 It is nice to keep the drive levels as high as possible; 
however, as long as the overall system noise floor is not 
impacted, it really doesn't matter if the reference level 
drops somewhere along the way.
 
>
>> Some data sheets contain this information at spot frequencies; 
>> this one does not.
>>   
> Very few datasheets from Maxim specify much about the noise
> characteristics of such devices.
>
Perhaps we are suffering from a language barrier here.
 
 When I look at all 21 devices in their "VCOs/VCO Buffers" 
parts category, the only ones _without_ noise specs are the 
very parts about which I am asking, the MAX274x family.
 
>   
>The criticism is aimed at the concept not the person.
>
So far, you've penned the following:
 
 "unsuitable for use at least in a well designed system"
"Its not that much more expensive to do it properly"
"No one in their right mind would attempt"
 
 I'm not sure which particular brand of rose colored reading
glasses you are using nowadays, but that is hardly appropriate
wording for something you would have us treat as an impartial 
technical critique.
 
>
>The question is largely irrelevant.
>
My questions are quite relevant.
 
 What is "largely irrelevant" are your "answers", which
so far have consisted of caustic postings containing
nothing but the repetition of basic design information.
 
Please refrain from "answering" any further questions on my part.
 

Brian
 
 
 
 
 
 
 
 
**************A Good Credit Score is 700 or Above. See yours in just 2 easy 
steps! 
(http://pr.atwola.com/promoclk/100000075x1215195222x1200993641/aol?redir=http://www.freecreditreport.com/pm/default.aspx?sc=668072%26hmpgID=82%26bcd=De
cemailfooterNO82)

From BriMDavis at aol.com  Fri Dec 19 03:42:24 2008
From: BriMDavis at aol.com (BriMDavis at aol.com)
Date: Thu, 18 Dec 2008 22:42:24 EST
Subject: [time-nuts] Build my own dist. amp ??
Message-ID: <cfb.49d985ba.367c7220@aol.com>

Didier wrote:
 
>
>Your original post asked for a reference distribution amplifier. 
>
I did not ask _for_ a reference distribution amplifier.

I asked whether anyone had used the MAX2470/2471 in such a 
design, specifically in regards to its residual phase noise.
 
>
> "Just wondering if anyone has ever tried the MAX2470/2471 VCO buffers as
> part of a reference distribution design?"
>
> Why would it need to cover more than one frequency? 
>
 
 My references are often higher frequency OCXOs ( e.g. 80, 100 MHz )
or multiples thereof ( e.g. 160, 200, 320, 400 MHz ).
 
 Distributed within a rack or box, rather than around a building.
 
 Instead of designing and building many different discrete 
narrowband amplifiers with optimum performance for a single
frequency, it is sufficient to design fewer amplifiers, 
having adequate performance in all bands.
 
Brian
 
p.s. 
 
 Another reason I am interested in this particular part is 
that the end of many such reference chains terminates in a
high speed data converter, needing differential clock drive 
in the 0-3 dBm range.
 
 Other options for this final device in the reference chain
include ECL line drivers or baluns; neither has much in the 
way of reverse isolation, and the ECL parts I've used in 
years past have a noise floor only in the -140's or so.
 
 There are also some newer LVDS/CML buffer parts that might 
be useful for this end of things, but many of these also lack 
any detailed phase noise data or reverse isolation specs.
 
 
 
 
 
 
 
 
 


**************A Good Credit Score is 700 or Above. See yours in just 2 easy 
steps! 
(http://pr.atwola.com/promoclk/100000075x1215195222x1200993641/aol?redir=http://www.freecreditreport.com/pm/default.aspx?sc=668072%26hmpgID=82%26bcd=De
cemailfooterNO82)

From bruce.griffiths at xtra.co.nz  Fri Dec 19 03:51:55 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Fri, 19 Dec 2008 16:51:55 +1300
Subject: [time-nuts] Sub Pico Second Phase logger
In-Reply-To: <p06240801c570a811d3c9@[192.168.1.212]>
References: <p06240801c570a811d3c9@[192.168.1.212]>
Message-ID: <494B1A5B.3030200@xtra.co.nz>

Joe

Joe Gwinn wrote:
> At 11:48 PM +0000 12/18/08, time-nuts-request at febo.com wrote:
>   
>> Message: 5
>> Date: Fri, 19 Dec 2008 12:48:27 +1300
>> From: Bruce Griffiths <bruce.griffiths at xtra.co.nz>
>> Subject: Re: [time-nuts] Sub Pico Second Phase logger
>> To: Discussion of precise time and frequency measurement
>> 	<time-nuts at febo.com>
>> Message-ID: <494AE14B.2050405 at xtra.co.nz>
>> Content-Type: text/plain; charset=ISO-8859-1
>>
>> [snip]
>>
>>  >>>      
>>     
>>>>  This just adds another layer of complexity for little immediate gain.
>>>>  Making the algorithms robust against small drifts in beat frequency is
>>>>  more useful in the general case (when 2 different test sources are being
>>>>  compared) than just assuming that the the beat frequency is very stable
>>>>  and fixed.
>>>>    
>>>>         
>>>  Yes, but I'm not sure we are solving the same problem.
>>>
>>>  I suppose the sound card could drive a simple PLL signal cleanup circuit.
>>>
>>>
>>>  
>>>       
>> One potential problem with using a sound card for a test source is that
>> the output DAC may share the same clock as the ADC ensuring that the
>> output signal is locked to the ADC sampling rate.
>>     
>
> True.  I would expect everything on a given card to use the same clock.
>
>
>   
>> In an actual dual mixer system the beat frequency and the ADC clock won't
>> necessarily be synchronised (it's difficult to lock the sampling clock of
>> most sound cards to an external reference).
>>     
>
> Maybe impossible.  While stuff used by the Broadcast folk probably 
> does accept external sync, it may as well be made of purest beaten 
> Gold.
>
>
>   
>> If one isn't careful the algorithms developed may work well when the ADC
>> sample clock and the test frequencies are locked, but have problems when
>> they are not.
>>     
>
> True.
>
>
>   
>> Using a second sound card to generate the test signal may overcome this
>> problem at increased cost, and for some it may not even be an option.
>>     
>
> It may not work with PCI soundcards, as the card clock may be 
> synchronized to the PCI bus clock.  Firewire/USB cards will have 
> their own independent clocks.
>
>   
Most recent design PCI sound cards have their own independent crystal
oscillator.
Some claim to be able to sync to an SPDIF input but the resultant jitter
may be large.
>> [snip]
>>  >>>      
>>     
>>>>  The immediate task is actually to evaluate sound cards for their
>>>>  suitability, preferably without the added cost and complexity of a DDS
>>>>  LO and mixer.
>>>>    
>>>>         
>>>  Suitability for what?  That is the point of enumerating tasks.
>>>
>>>  
>>>       
>> Suitability for use in a dual mixer system.
>>     
>
> Ah.
>
>
>   
>>  >> 10Hz resolution whilst avoiding phase truncation spurs is impractical
>>     
>>>>  with a DDS chip by itself.
>>>>  Depending on the DDS and its clock frequency, the frequency spacing of
>>>>  phase truncation spur free outputs may be as large as several kHz.
>>>>    
>>>>         
>>>  Is this true of concatenated DDS chips?  I recall a patent to the
>>>       
>>  > contrary.
>>  >  
>> Which patent?
>>     
>
> Hmm.  It's at work.  I'll look it up in January.  As I recall, the 
> second DDS made a small integer conversion, and so had low spurs, 
> while the first DDS was set to whatever was needed.
>
>   
Do you mean US5598440?
>   
>> If the zero crossings are time stamped and do not occur simultaneously
>> in each channel then the phase noise of the offset oscillator will
>> affect the measurement.
>>     
>
> I'm not following.  Please expand.  The zero crossings are never 
> aligned unless there is no phase delay.
>
>
>   
Yes, thats the point, the offset generator phase noise contribution isnt
the same for both zero crossings.
Greenhall et al correct for this to some extent, but at least for short
tau, one is then no longer measuring ADEV, MDEV etc.
There is some advantage in having a higher beat frequency as the offset
generator phase noise has less time to accumulate.
>>  >> A few divide and mix stages will be required to achieve a spur free
>>     
>>>>  resolution of 10Hz.
>>>>    
>>>>         
>>>  That is a traditional approach.  But are there alternate approaches that
>>>  have now become practical?
>>>
>>>
>>>       
>> Diophantine frequency synthesis?
>>     
>
>  From the sound of the name I think so, at least in the last DDS 
> stage, as done by that patent.
>
> But I was fishing.
>
>   
Conventional Diophantine synthesis uses number theory together with 2 or
3 conventional synthesiser loops to achieve very fine resolution whilst
maintaining a high PLL phase detector input frequency.
>   
>>  >  
>>     
>>>>  To broaden participation we need to broaden the scope of the project to
>>>>  include dual mixer system with statistically independent test sources as
>>>>  well as the more specialised case where the 2 input frequencies differ
>>>>  only in phase.
>>>>
>>>>  1) Evaluate sound cards for suitablility.
>>>>  Initially use simple less stable sources and follow up with more stable
>>>>  test sources for the more promising cards.
>>>>  Need to measure crosstalk, temporal instability of interchannel phase
>>>>  shift, system noise etc.
>>>>    
>>>>         
>>>  Generally agree, but there is that undefined elastic term "suitability"
>>>       
>>  > again.
>>     
>>>  
>>>       
>> Replace suitability with:
>> Measure the characteristics of a sound card that affect the performance
>> when used in a dual mixer system used to measure the relative phases of
>> a pair of RF signals.
>> Where the pair of RF signals may either:
>>
>> 1) originate from 2 statistically independent sources (OCXOs, GPSDO's etc)
>>
>> OR
>>
>> 2) originate from the same source and just differ in phase.
>>     
>
> That covers it for sure.
>
>   
Bruce


From bruce.griffiths at xtra.co.nz  Fri Dec 19 03:54:12 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Fri, 19 Dec 2008 16:54:12 +1300
Subject: [time-nuts] Sub Pico Second Phase logger
In-Reply-To: <p06240800c570a5b846fd@[192.168.1.212]>
References: <p06240800c570a5b846fd@[192.168.1.212]>
Message-ID: <494B1AE4.1010106@xtra.co.nz>

Joe
Joe Gwinn wrote:
> This is from home.  I'll not be at work until next year.
>
> At 11:48 PM +0000 12/18/08, time-nuts-request at febo.com wrote:
>   
>> Message: 4
>> Date: Fri, 19 Dec 2008 12:17:33 +1300
>> From: Bruce Griffiths <bruce.griffiths at xtra.co.nz>
>> Subject: Re: [time-nuts] Sub Pico Second Phase logger
>> To: Discussion of precise time and frequency measurement
>> 	<time-nuts at febo.com>
>> Message-ID: <494ADA0D.3060004 at xtra.co.nz>
>> Content-Type: text/plain; charset=ISO-8859-1
>>
>> Joe
>>
>>
>>  >>>      
>>     
>>>>  [BG] Proposed test setup:
>>>>  (preliminary to be refined)
>>>>
>>>>  Drive 2 sound card inputs in parallel with the same source.
>>>>
>>>>  Source amplitude:
>>>>  Max sound card input -3dB
>>>>    
>>>>         
>>>  What kind of dB?
>>>
>>>  
>>>       
>> Peak input signal voltage = 70% of sound card maximum peak input voltage.
>> Just to leave some margin for gain tolerances.
>>     
>
> OK.
>
>
>   
>>  >> Sources:
>>     
>>>>  1) Wien bridge or equivalent (eg state variable oscillator with soft
>>>>  clamping) relatively low distortion oscillator.
>>>>
>>>>  2) Buffered low pass filtered output of binary divider driven by a
>>>>  crystal oscillator
>>>>    
>>>>         
>>  > RC oscillator sounds far simpler and more flexible.
>>
>> A Wien bridge using a lamp is perhaps the simplest.
>> I'll create a circuit schematics for this using an OPA2134 (dual lowish
>> noise JFET opamp).
>> One opamp for the oscillator one to drive the sound card (attenuation of
>> the oscillator output will be required for some sound cards and it is
>> desirable to have a low output impedance driver).
>>     
>
> Jim Williams of Linear Technology had a very good low-distortion AGC 
> controlled Wein Bridge oscillator.  If I recall, he used a photo-FET 
> or the like as the servoed resistor in the bridge.  There may be an 
> application note on the LT website, but I saw it in a chapter of a 
> book on analog circuitry, the chapter author being Jim W.
>
>
>   
I have the application note.
>>  >> Test frequencies:
>>     
>>>>  100Hz
>>>>
>>>>  1kHz
>>>>    
>>>>         
>>>  Why no 10 Hz?  (Well, 20 Hz.)
>>>
>>>  
>>>       
>> No particular reason other than some complications if a lamp stabilised
>> oscillator is used.
>> A diode soft (series R) clamped RC oscillator is more flexible in this
>> regard.
>> I'll also produce a circuit schematic for one of these oscillators.
>>     
>
> Jim Williams' circuit would handle 10 Hz if I recall.
>
>
>   
>>  >> Sound card sample rate:
>>     
>>>>  ~24KSPS
>>>>    
>>>>         
>>>  I assume that this is the lowest rate supported, and certainly is overkill
>>>  for 1 KHz.
>>>
>>>  
>>>       
>> It varies with the sound card.
>> I just suggested that for a starting point in the discussion.
>>
>> For an AP192 the directly (without sample rate interpolation) available
>> output sample rates are:
>>
>> 192, 96, 64, 48, 32, 8 KSPS.
>>     
>
> OK.  I would start with 8 ksps.  We will end up decimating below that 
> anyway, except for 1 KHz test signals.
>
>
> Joe
>
>   
I'll breadboard an oscillator over the holidays and take some samples.

Bruce


From bruce.griffiths at xtra.co.nz  Fri Dec 19 04:35:32 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Fri, 19 Dec 2008 17:35:32 +1300
Subject: [time-nuts] Build my own dist. amp ??
In-Reply-To: <bde.3adc3a86.367c71b9@aol.com>
References: <bde.3adc3a86.367c71b9@aol.com>
Message-ID: <494B2494.9060504@xtra.co.nz>

BriMDavis at aol.com wrote:
> Bruce Griffiths wrote:
>   
>> That is a very effective way of elevating the phase noise floor.
>> Its usually far better to amplify the input and then split the output
>> maintaining a gain to the splitter outputs of at least 0dB.
>>
>>     
> As I already explained the last time you mentioned this, 
> I am well aware of noise floor limitations when operating 
> an LO or clock at reduced signal levels.
>   
Have you actually estimated the resultant phase noise floor with 0dBm
output??
An optimistic estimate can be done using the noise figure at the
frequency of interest.
>  
>  It is nice to keep the drive levels as high as possible; 
> however, as long as the overall system noise floor is not 
> impacted, it really doesn't matter if the reference level 
> drops somewhere along the way.
>   
When is a noise penalty of around 30dB (for the better sources) not
significant?

>  
>   
>>> Some data sheets contain this information at spot frequencies; 
>>> this one does not.
>>>   
>>>       
>> Very few datasheets from Maxim specify much about the noise
>> characteristics of such devices.
>>
>>     
> Perhaps we are suffering from a language barrier here.
>  
>  When I look at all 21 devices in their "VCOs/VCO Buffers" 
> parts category, the only ones _without_ noise specs are the 
> very parts about which I am asking, the MAX274x family.
>  
>   
Very little useful phase noise data is given (for a distribution
amplifier application), particularly for low offset frequencies.
For example MAX9989 only gives a spot phase noise at 100MHz output for a
1500MHz input.

I was also referring to the lack of low frequency noise data for devices
like the MAX477.
Maxim aren't alone in this.
> Brian
>  
>  
>   

Bruce


From stijena at tapko.de  Fri Dec 19 08:22:40 2008
From: stijena at tapko.de (Predrag Dukic)
Date: Fri, 19 Dec 2008 09:22:40 +0100
Subject: [time-nuts] Is oscillator sync always bad?
In-Reply-To: <ECE7A93BD093E1439C20020FBE87C47FEB55DA8F9A@ALTPHYEMBEVSP20
	.RES.AD.JPL>
References: <OF82CE5BA4.E295CDB3-ON85257522.006701B9-85257522.006A4527@mck.us.ray.com>
	<49496464.4000106@xtra.co.nz>
	<7.0.1.0.1.20081218211512.01ede5d8@tapko.de>
	<ECE7A93BD093E1439C20020FBE87C47FEB55DA8F87@ALTPHYEMBEVSP20.RES.AD.JPL>
	<7.0.1.0.1.20081218223143.01e78330@tapko.de>
	<ECE7A93BD093E1439C20020FBE87C47FEB55DA8F9A@ALTPHYEMBEVSP20.RES.AD.JPL>
Message-ID: <7.0.1.0.1.20081219091913.01ef8a58@tapko.de>



Lux,

I read only the abstract. I have access to the database only from the 
University computers,
and my comment was sent at midnight , local time, from home.

 From the abstract I understood that they want to improve oscillators 
by using multiple units....


Predrag




At 23:00 18.12.2008, you wrote:

> >
> > Lux,
> >
> > It is one more confimation that my assumption is valid.
>
>In fact, they comment about the potential problem of injection locking..
>
> > > >  Allan, et al., did a thing with 8 small oscillators in a
> > ring.  I
> > > > don't recall if they deliberately tried to have them mutually
> > > > couple, or if it was designed to try and cancel acceleration
> > > > effects.
> > > >
> > > >
>
>_______________________________________________
>time-nuts mailing list -- time-nuts at febo.com
>To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>and follow the instructions there.



From scopefreak at onsnet.nu  Fri Dec 19 10:08:30 2008
From: scopefreak at onsnet.nu (Tom)
Date: Fri, 19 Dec 2008 11:08:30 +0100
Subject: [time-nuts] Sub Pico Second Phase logger
In-Reply-To: <p06240801c570a811d3c9@[192.168.1.212]>
References: <p06240801c570a811d3c9@[192.168.1.212]>
Message-ID: <200812191108.30679.scopefreak@onsnet.nu>

On Friday 19 December 2008 02:46, Joe Gwinn wrote:
> >  >> 10Hz resolution whilst avoiding phase truncation spurs is
> >  >> impractical
> >>>  with a DDS chip by itself.
> >>>  Depending on the DDS and its clock frequency, the frequency
> >>> spacing of phase truncation spur free outputs may be as large
> >>> as several kHz.
> >>
> >>  Is this true of concatenated DDS chips?  I recall a patent to
> >> the
> >  > contrary.
> >
> >Which patent?
>
> Hmm.  It's at work.  I'll look it up in January.  As I recall, the
> second DDS made a small integer conversion, and so had low spurs,
> while the first DDS was set to whatever was needed.
>
I think you are referring to patent 5598440 about a DDS driven DDS.

Tom


From james.p.lux at jpl.nasa.gov  Fri Dec 19 14:36:28 2008
From: james.p.lux at jpl.nasa.gov (Lux, James P)
Date: Fri, 19 Dec 2008 06:36:28 -0800
Subject: [time-nuts] Is oscillator sync always bad?
In-Reply-To: <7.0.1.0.1.20081219091913.01ef8a58@tapko.de>
Message-ID: <C570F16C.3A3D%James.P.Lux@jpl.nasa.gov>


I read only the abstract. I have access to the database only from the
University computers,
and my comment was sent at midnight , local time, from home.

 From the abstract I understood that they want to improve oscillators
by using multiple units....

Yes.. You're right. But, they do mention a lot of the potential problems (e.g. Injection lock) in the paper, and I don't know that they actually ever built one of the CTXOs.

From ernieperes at aol.com  Fri Dec 19 17:06:17 2008
From: ernieperes at aol.com (ernieperes at aol.com)
Date: Fri, 19 Dec 2008 12:06:17 -0500
Subject: [time-nuts] FE5680 PINOUT
Message-ID: <8CB30133D940FFD-CAC-C2B@mblk-d20.sysops.aol.com>

Hi Gents,

Having a Fe5680 Rub freq standard but can not figure out the 9 pin 
connector..

It is a version with 4x8 DIP SW inside and no SMA output connector, 
inside can measure the 8,388,608 Hz but can not detect the 1PPS 
output.... although I do not know which pin should have the +5Volt 
input...
Only known pin nbr 1...+15Volt
                 pin nbr 2.. GRND

      rest unknown.....

Thanks in advance.

Rgds Ernie.


From joegwinn at comcast.net  Fri Dec 19 17:57:35 2008
From: joegwinn at comcast.net (Joe Gwinn)
Date: Fri, 19 Dec 2008 12:57:35 -0500
Subject: [time-nuts] Sub Pico Second Phase logger
Message-ID: <p06240803c5718de0b0e5@[192.168.1.212]>

Bruce,

At 3:54 AM +0000 12/19/08, time-nuts-request at febo.com wrote:
>
>Message: 5
>Date: Fri, 19 Dec 2008 16:51:55 +1300
>From: Bruce Griffiths <bruce.griffiths at xtra.co.nz>
>Subject: Re: [time-nuts] Sub Pico Second Phase logger
>To: Discussion of precise time and frequency measurement
>	<time-nuts at febo.com>
>
>Joe
>
>Joe Gwinn wrote:
>>  At 11:48 PM +0000 12/18/08, time-nuts-request at febo.com wrote:
>>  
>>>  Message: 5
>>>  Date: Fri, 19 Dec 2008 12:48:27 +1300
>>>  From: Bruce Griffiths <bruce.griffiths at xtra.co.nz>
>>>  Subject: Re: [time-nuts] Sub Pico Second Phase logger
>>>  To: Discussion of precise time and frequency measurement
>  >>	<time-nuts at febo.com>
>  >>
>  >> [snip]
>  >  
>>>  Using a second sound card to generate the test signal may overcome this
>>>  problem at increased cost, and for some it may not even be an option.
>  >>    
>>
>>  It may not work with PCI soundcards, as the card clock may be
>>  synchronized to the PCI bus clock.  Firewire/USB cards will have
>>  their own independent clocks.
>>
>>  
>Most recent design PCI sound cards have their own independent crystal
>oscillator.

It won't be a great crystal, but a crystal nonetheless.


>Some claim to be able to sync to an SPDIF input but the resultant jitter
>may be large.

Why large jitter?  Bad implementation?


>  >  
>>>   >> 10Hz resolution whilst avoiding phase truncation spurs is impractical
>>>    
>>>>>   with a DDS chip by itself.
>>>>>   Depending on the DDS and its clock frequency, the frequency spacing of
>>>>>   phase truncation spur free outputs may be as large as several kHz.
>>>>>   
>>>>>
>  >>>  Is this true of concatenated DDS chips?  I recall a patent to the
>  >>> contrary.
>  >>  >
>  >> Which patent?
>  >
>>  Hmm.  It's at work.  I'll look it up in January.  As I recall, the
>>  second DDS made a small integer conversion, and so had low spurs,
>>  while the first DDS was set to whatever was needed.
>>
>>
>Do you mean US5598440?

Yes, that's it.


>  >> If the zero crossings are time stamped and do not occur simultaneously
>>>  in each channel then the phase noise of the offset oscillator will
>  >> affect the measurement.
>  >
>>  I'm not following.  Please expand.  The zero crossings are never
>>  aligned unless there is no phase delay.
>>
>>
>>  
>Yes, thats the point, the offset generator phase noise contribution isnt
>the same for both zero crossings.
>Greenhall et al correct for this to some extent, but at least for short
>tau, one is then no longer measuring ADEV, MDEV etc.
>There is some advantage in having a higher beat frequency as the offset
>generator phase noise has less time to accumulate.

I recall reading an article on this by Greenhall, probably _the_ 
article.  My reaction was that I would be fortunate to have a setup 
where I could even detect such a problem.


>  >>  >> A few divide and mix stages will be required to achieve a spur free
>>>    
>>>>>   resolution of 10Hz.
>>>>>   
>>>>>        
>>>>   That is a traditional approach.  But are there alternate approaches that
>>>>   have now become practical?
>>>>
>>>>
>>>>      
>>>  Diophantine frequency synthesis?
>>>    
>>
>>   From the sound of the name I think so, at least in the last DDS
>>  stage, as done by that patent.
>>
>>  But I was fishing.
>>
>>  
>Conventional Diophantine synthesis uses number theory together with 2 or
>3 conventional synthesiser loops to achieve very fine resolution whilst
>maintaining a high PLL phase detector input frequency.

In a sense, the concatenated DDS approach is a divide-and-mix chain. 
Perhaps there is a parallel here.



From dave.g0dja at tiscali.co.uk  Fri Dec 19 19:11:10 2008
From: dave.g0dja at tiscali.co.uk (Dave Ackrill)
Date: Fri, 19 Dec 2008 19:11:10 +0000
Subject: [time-nuts] BBC Radio 4 Programme - In Our Time
In-Reply-To: <p06240803c5718de0b0e5@[192.168.1.212]>
References: <p06240803c5718de0b0e5@[192.168.1.212]>
Message-ID: <494BF1CE.2070909@tiscali.co.uk>

There was an interesting edition of a programme called 'In Our Time' 
yesterday about time.

If you go to 
http://www.bbc.co.uk/radio4/history/inourtime/inourtime.shtml you can 
read about what was discussed and listen to the programme online as well.

Hope it's of interest.

Dave


From n3izn at aol.com  Fri Dec 19 20:06:44 2008
From: n3izn at aol.com (n3izn at aol.com)
Date: Fri, 19 Dec 2008 15:06:44 -0500
Subject: [time-nuts] Agilent 53148A, thunderbolt and my 10 Ghz LO
Message-ID: <8CB302C72F46E0A-90-29D@FWM-D15.sysops.aol.com>

I'm borrowing a power meter and frequency county from work, an Agilent 53148A. While it's slow at work I wanted to make some measurements and align my ham radio stuff.

It's last calibration was in May 08. I let it warm up for several hours, and it has the oven option. 

My 10 Ghz LO is 10,224 Mhz and it was 70 hz off. Not a big deal for my application.

I found the manual and figured out how to choose an external reference on the 53148. I just wanted to ask the group if the Thunderbolt would be more accurate than the internal reference? I want to think it is but my link to the thunderbolt spec sheet is no longer valid.

This weekend I'll measure it again using the tBolt as a reference. 

From joegwinn at comcast.net  Fri Dec 19 20:53:46 2008
From: joegwinn at comcast.net (Joe Gwinn)
Date: Fri, 19 Dec 2008 15:53:46 -0500
Subject: [time-nuts] Sub Pico Second Phase logger
Message-ID: <p06240804c571adf034e9@[192.168.1.212]>

Bruce,

At 3:54 AM +0000 12/19/08, time-nuts-request at febo.com wrote:
>
>Message: 6
>Date: Fri, 19 Dec 2008 16:54:12 +1300
>From: Bruce Griffiths <bruce.griffiths at xtra.co.nz>
>Subject: Re: [time-nuts] Sub Pico Second Phase logger
>To: Discussion of precise time and frequency measurement
>	<time-nuts at febo.com>
>
>Joe
>Joe Gwinn wrote:
>>  This is from home.  I'll not be at work until next year.
>>
>>  At 11:48 PM +0000 12/18/08, time-nuts-request at febo.com wrote:
>>  
>>>  Message: 4
>>>  Date: Fri, 19 Dec 2008 12:17:33 +1300
>>>  From: Bruce Griffiths <bruce.griffiths at xtra.co.nz>
>>>  Subject: Re: [time-nuts] Sub Pico Second Phase logger
>>>  To: Discussion of precise time and frequency measurement
>  >>	<time-nuts at febo.com>
>  >>
>>>  Joe
>>>
>>>
>>>   >>>
>  >>
>[snip]
>  >>  >> Sources:
>>>    
>>>>>   1) Wien bridge or equivalent (eg state variable oscillator with soft
>>>>>   clamping) relatively low distortion oscillator.
>>>>>
>>>>>   2) Buffered low pass filtered output of binary divider driven by a
>>>>>   crystal oscillator
>>>>>   
>>>>>        
>>>   > RC oscillator sounds far simpler and more flexible.
>>>
>>>  A Wien bridge using a lamp is perhaps the simplest.
>>>  I'll create a circuit schematics for this using an OPA2134 (dual lowish
>>>  noise JFET opamp).
>>>  One opamp for the oscillator one to drive the sound card (attenuation of
>>>  the oscillator output will be required for some sound cards and it is
>>>  desirable to have a low output impedance driver).
>>>    
>>
>>  Jim Williams of Linear Technology had a very good low-distortion AGC
>>  controlled Wein Bridge oscillator.  If I recall, he used a photo-FET
>>  or the like as the servoed resistor in the bridge.  There may be an
>>  application note on the LT website, but I saw it in a chapter of a
>>  book on analog circuitry, the chapter author being Jim W.
>>
>>
>>  
>I have the application note.

LT App Note 43 is what JW mentions.  Figure 47 is the key.  (He also 
mentions App Note 5.)

These cites are from the refs of "Max Wien, Mr. Hewlett, and a Rainy 
Sunday Afternoon", Jim Williams, Chapter 7 in "Analog Circuit Design 
-- Art, Science, and Personalities, edited by Jim Williams, 
Butterworth-Heinemann 1991.  The relevant section of App Note 43 
seems to be shared with this chapter.

It wasn't a photo-FET he used, it was a Vactec model VTL5C10 
optically (LED) driven CdS photocell.

Most of it is here (what's missing is some history and the refs): 
<http://books.google.com/books?id=Il4xxTTyhbEC&pg=PA43&lpg=PA43&dq=Max+Wien,+Mr.+Hewlett,+and+a+Rainy+Sunday+Afternoon&source=bl&ots=jnHNItJrOF&sig=ZL_CB_yIdT0ZbsD7Ieu_CjVYJHk&hl=en&sa=X&oi=book_result&resnum=1&ct=result#PPA53,M1>.


>  >> For an AP192 the directly (without sample rate interpolation) available
>>>  output sample rates are:
>>>
>>>  192, 96, 64, 48, 32, 8 KSPS.
>>>    
>>
>>  OK.  I would start with 8 ksps.  We will end up decimating below that
>>  anyway, except for 1 KHz test signals.
>>
>>
>>  Joe
>>
>>
>I'll breadboard an oscillator over the holidays and take some samples.

A rainy-day activity for sure.   In the Boston area, the issue is 
snow - a noreaster is just now starting, with a foot of snow expected.

Joe


From bruce.griffiths at xtra.co.nz  Fri Dec 19 21:38:26 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Sat, 20 Dec 2008 10:38:26 +1300
Subject: [time-nuts] Sub Pico Second Phase logger
In-Reply-To: <p06240803c5718de0b0e5@[192.168.1.212]>
References: <p06240803c5718de0b0e5@[192.168.1.212]>
Message-ID: <494C1452.1080900@xtra.co.nz>

Joe

Joe Gwinn wrote:
> Bruce,
>
> At 3:54 AM +0000 12/19/08, time-nuts-request at febo.com wrote:
>   
>> Message: 5
>> Date: Fri, 19 Dec 2008 16:51:55 +1300
>> From: Bruce Griffiths <bruce.griffiths at xtra.co.nz>
>> Subject: Re: [time-nuts] Sub Pico Second Phase logger
>> To: Discussion of precise time and frequency measurement
>> 	<time-nuts at febo.com>
>>
>> Joe
>>
>> Joe Gwinn wrote:
>>     
>>>  At 11:48 PM +0000 12/18/08, time-nuts-request at febo.com wrote:
>>>  
>>>       
>>>>  Message: 5
>>>>  Date: Fri, 19 Dec 2008 12:48:27 +1300
>>>>  From: Bruce Griffiths <bruce.griffiths at xtra.co.nz>
>>>>  Subject: Re: [time-nuts] Sub Pico Second Phase logger
>>>>  To: Discussion of precise time and frequency measurement
>>>>         
>>  >>	<time-nuts at febo.com>
>>  >>
>>  >> [snip]
>>  >  
>>     
>>>>  Using a second sound card to generate the test signal may overcome this
>>>>  problem at increased cost, and for some it may not even be an option.
>>>>         
>>  >>    
>>     
>>>  It may not work with PCI soundcards, as the card clock may be
>>>  synchronized to the PCI bus clock.  Firewire/USB cards will have
>>>  their own independent clocks.
>>>
>>>  
>>>       
>> Most recent design PCI sound cards have their own independent crystal
>> oscillator.
>>     
>
> It won't be a great crystal, but a crystal nonetheless.
>
>   
The AP192 has 2 low profile HC49 style crystal packages on the PCB.
>   
>> Some claim to be able to sync to an SPDIF input but the resultant jitter
>> may be large.
>>     
>
> Why large jitter?  Bad implementation?
>
>
>   
I'm just suspicious, although I did see some data somewhere that seemed
to confirm my suspicions.
The S/PDIF signal has to be a valid SPDIF signal not just a square or
sine wave clock.
Output sample rates (for the AP192) are then identical to that of the
the S/PDIF source which is limited to
192, 176.4, 96,88.2 48, 44.1 32 KSPS.
>>  >  
>>     
>>>>   >> 10Hz resolution whilst avoiding phase truncation spurs is impractical
>>>>    
>>>>         
>>>>>>   with a DDS chip by itself.
>>>>>>   Depending on the DDS and its clock frequency, the frequency spacing of
>>>>>>   phase truncation spur free outputs may be as large as several kHz.
>>>>>>   
>>>>>>
>>>>>>             
>>  >>>  Is this true of concatenated DDS chips?  I recall a patent to the
>>  >>> contrary.
>>  >>  >
>>  >> Which patent?
>>  >
>>     
>>>  Hmm.  It's at work.  I'll look it up in January.  As I recall, the
>>>  second DDS made a small integer conversion, and so had low spurs,
>>>  while the first DDS was set to whatever was needed.
>>>
>>>
>>>       
>> Do you mean US5598440?
>>     
>
> Yes, that's it.
>
>
>   
>>  >> If the zero crossings are time stamped and do not occur simultaneously
>>     
>>>>  in each channel then the phase noise of the offset oscillator will
>>>>         
>>  >> affect the measurement.
>>  >
>>     
>>>  I'm not following.  Please expand.  The zero crossings are never
>>>  aligned unless there is no phase delay.
>>>
>>>
>>>  
>>>       
>> Yes, thats the point, the offset generator phase noise contribution isnt
>> the same for both zero crossings.
>> Greenhall et al correct for this to some extent, but at least for short
>> tau, one is then no longer measuring ADEV, MDEV etc.
>> There is some advantage in having a higher beat frequency as the offset
>> generator phase noise has less time to accumulate.
>>     
>
> I recall reading an article on this by Greenhall, probably _the_ 
> article.  My reaction was that I would be fortunate to have a setup 
> where I could even detect such a problem.
>
>
>   
>>  >>  >> A few divide and mix stages will be required to achieve a spur free
>>     
>>>>    
>>>>         
>>>>>>   resolution of 10Hz.
>>>>>>   
>>>>>>        
>>>>>>             
>>>>>   That is a traditional approach.  But are there alternate approaches that
>>>>>   have now become practical?
>>>>>
>>>>>
>>>>>      
>>>>>           
>>>>  Diophantine frequency synthesis?
>>>>    
>>>>         
>>>   From the sound of the name I think so, at least in the last DDS
>>>  stage, as done by that patent.
>>>
>>>  But I was fishing.
>>>
>>>  
>>>       
>> Conventional Diophantine synthesis uses number theory together with 2 or
>> 3 conventional synthesiser loops to achieve very fine resolution whilst
>> maintaining a high PLL phase detector input frequency.
>>     
>
> In a sense, the concatenated DDS approach is a divide-and-mix chain. 
> Perhaps there is a parallel here.
>
>
>   
The DDS based equivalent (of the dual PLL Diophantine synthesiser) would
use a pair of DDS chips each replacing a conventional PPL in the
Diophantine frequency synthesiser, the output frequency of each having
zero phase truncation spurs.
Both DDS clock sources should be spur free and have a frequency ratio
that is a selected fixed rational fraction.
A conventional mixer would then be used to either add or subtract the
two DDS output frequencies.
If the ratio of the 2 DDS clock source frequencies is appropriately
chosen the spacing between the resultant mixer output frequencies can be
much finer than the spacing between the truncation spur free outputs of
either DDS chip.
The DDS and mixer outputs should be filtered to remove harmonics and
other unwanted frequencies.

One drawback is that selecting the output frequencies of the 2 DDS chips
required to produce the desired output frequency is somewhat complex.
Since one almost certainly needs a computer of some sort to set the DDS
frequencies this shouldn't be a significant issue.

Bruce



From bruce.griffiths at xtra.co.nz  Fri Dec 19 21:50:46 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Sat, 20 Dec 2008 10:50:46 +1300
Subject: [time-nuts] Sub Pico Second Phase logger
In-Reply-To: <p06240804c571adf034e9@[192.168.1.212]>
References: <p06240804c571adf034e9@[192.168.1.212]>
Message-ID: <494C1736.60504@xtra.co.nz>

Joe

Joe Gwinn wrote:
> Bruce,
>
> At 3:54 AM +0000 12/19/08, time-nuts-request at febo.com wrote:
>   
>> Message: 6
>> Date: Fri, 19 Dec 2008 16:54:12 +1300
>> From: Bruce Griffiths <bruce.griffiths at xtra.co.nz>
>> Subject: Re: [time-nuts] Sub Pico Second Phase logger
>> To: Discussion of precise time and frequency measurement
>> 	<time-nuts at febo.com>
>>
>> Joe
>> Joe Gwinn wrote:
>>     
>>>  This is from home.  I'll not be at work until next year.
>>>
>>>  At 11:48 PM +0000 12/18/08, time-nuts-request at febo.com wrote:
>>>  
>>>       
>>>>  Message: 4
>>>>  Date: Fri, 19 Dec 2008 12:17:33 +1300
>>>>  From: Bruce Griffiths <bruce.griffiths at xtra.co.nz>
>>>>  Subject: Re: [time-nuts] Sub Pico Second Phase logger
>>>>  To: Discussion of precise time and frequency measurement
>>>>         
>>  >>	<time-nuts at febo.com>
>>  >>
>>     
>>>>  Joe
>>>>
>>>>
>>>>   >>>
>>>>         
>>  >>
>> [snip]
>>  >>  >> Sources:
>>     
>>>>    
>>>>         
>>>>>>   1) Wien bridge or equivalent (eg state variable oscillator with soft
>>>>>>   clamping) relatively low distortion oscillator.
>>>>>>
>>>>>>   2) Buffered low pass filtered output of binary divider driven by a
>>>>>>   crystal oscillator
>>>>>>   
>>>>>>        
>>>>>>             
>>>>   > RC oscillator sounds far simpler and more flexible.
>>>>
>>>>  A Wien bridge using a lamp is perhaps the simplest.
>>>>  I'll create a circuit schematics for this using an OPA2134 (dual lowish
>>>>  noise JFET opamp).
>>>>  One opamp for the oscillator one to drive the sound card (attenuation of
>>>>  the oscillator output will be required for some sound cards and it is
>>>>  desirable to have a low output impedance driver).
>>>>    
>>>>         
>>>  Jim Williams of Linear Technology had a very good low-distortion AGC
>>>  controlled Wein Bridge oscillator.  If I recall, he used a photo-FET
>>>  or the like as the servoed resistor in the bridge.  There may be an
>>>  application note on the LT website, but I saw it in a chapter of a
>>>  book on analog circuitry, the chapter author being Jim W.
>>>
>>>
>>>  
>>>       
>> I have the application note.
>>     
>
> LT App Note 43 is what JW mentions.  Figure 47 is the key.  (He also 
> mentions App Note 5.)
>
> These cites are from the refs of "Max Wien, Mr. Hewlett, and a Rainy 
> Sunday Afternoon", Jim Williams, Chapter 7 in "Analog Circuit Design 
> -- Art, Science, and Personalities, edited by Jim Williams, 
> Butterworth-Heinemann 1991.  The relevant section of App Note 43 
> seems to be shared with this chapter.
>
> It wasn't a photo-FET he used, it was a Vactec model VTL5C10 
> optically (LED) driven CdS photocell.
>
>   
Note for those (in Australia,  NZ and Europe) who may want to replicate
that oscillator:
The VTL5C10 device is obtainable locally from RS Components.
> Most of it is here (what's missing is some history and the refs): 
> <http://books.google.com/books?id=Il4xxTTyhbEC&pg=PA43&lpg=PA43&dq=Max+Wien,+Mr.+Hewlett,+and+a+Rainy+Sunday+Afternoon&source=bl&ots=jnHNItJrOF&sig=ZL_CB_yIdT0ZbsD7Ieu_CjVYJHk&hl=en&sa=X&oi=book_result&resnum=1&ct=result#PPA53,M1>.
>
>
>   
>>  >> For an AP192 the directly (without sample rate interpolation) available
>>     
>>>>  output sample rates are:
>>>>
>>>>  192, 96, 64, 48, 32, 8 KSPS.
>>>>    
>>>>         
>>>  OK.  I would start with 8 ksps.  We will end up decimating below that
>>>  anyway, except for 1 KHz test signals.
>>>
>>>
>>>  Joe
>>>
>>>
>>>       
>> I'll breadboard an oscillator over the holidays and take some samples.
>>     
>
> A rainy-day activity for sure.   In the Boston area, the issue is 
> snow - a noreaster is just now starting, with a foot of snow expected.
>
> Joe
>
>   
AFAIK it has never snowed here.
It does snow on the central NI Plateau but not usually in December.
I'll start with a diode limited (soft clamps - resistance in series with
diodes) oscillator and move to a lower distortion one if necessary.

Bruce


From jmiles at pop.net  Fri Dec 19 22:53:01 2008
From: jmiles at pop.net (John Miles)
Date: Fri, 19 Dec 2008 14:53:01 -0800
Subject: [time-nuts] Agilent 53148A, thunderbolt and my 10 Ghz LO
In-Reply-To: <8CB302C72F46E0A-90-29D@FWM-D15.sysops.aol.com>
Message-ID: <PKEGJHPHLLBACEOICCBJEEOHPOAB.jmiles@pop.net>

Well, sure, it's more accurate than the undisciplined OCXO in the counter,
that's the idea behind the Thunderbolt. :)

-- john, KE5FX

> -----Original Message-----
> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com]On
> Behalf Of n3izn at aol.com
> Sent: Friday, December 19, 2008 12:07 PM
> To: time-nuts at febo.com
> Subject: [time-nuts] Agilent 53148A, thunderbolt and my 10 Ghz LO
>
>
> I'm borrowing a power meter and frequency county from work, an
> Agilent 53148A. While it's slow at work I wanted to make some
> measurements and align my ham radio stuff.
>
> It's last calibration was in May 08. I let it warm up for several
> hours, and it has the oven option.
>
> My 10 Ghz LO is 10,224 Mhz and it was 70 hz off. Not a big deal
> for my application.
>
> I found the manual and figured out how to choose an external
> reference on the 53148. I just wanted to ask the group if the
> Thunderbolt would be more accurate than the internal reference? I
> want to think it is but my link to the thunderbolt spec sheet is
> no longer valid.
>
> This weekend I'll measure it again using the tBolt as a reference.
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>



From pvince at theiet.org  Sat Dec 20 10:45:14 2008
From: pvince at theiet.org (Peter Vince)
Date: Sat, 20 Dec 2008 10:45:14 +0000
Subject: [time-nuts] FE5680 PINOUT
Message-ID: <49381.1229769914@uk2.net>

Hi Ernie,

     The KO4BB repository has a manual for "Option 2" of the 5680A.  This might not be exactly the same as the one you have, 
but should hopefully at least use the same pinout.

     Regards,

          Peter


On Fri Dec 19 15:06 , ernieperes at aol.com sent:

>Hi Gents,
>
>Having a Fe5680 Rub freq standard but can not figure out the 9 pin connector...




From ernieperes at aol.com  Sat Dec 20 11:44:22 2008
From: ernieperes at aol.com (ernieperes at aol.com)
Date: Sat, 20 Dec 2008 06:44:22 -0500
Subject: [time-nuts] FE5680 PINOUT
In-Reply-To: <49381.1229769914@uk2.net>
References: <49381.1229769914@uk2.net>
Message-ID: <8CB30AF6EC551B5-E40-1ABE@webmail-mf06.sysops.aol.com>

Hi Peter,

Thanks for the info, in the mean time got additional docs, now need 
more time to play with it.

Best regards and Marry Xmas,

Ernie.



-----Original Message-----
From: Peter Vince <pvince at theiet.org>
To: Discussion of precise time and frequency measurement 
<time-nuts at febo.com>
Sent: Sat, 20 Dec 2008 11:45 am
Subject: Re: [time-nuts] FE5680 PINOUT



Hi Ernie,

The KO4BB repository has a manual for "Option 2" of the 5680A. This 
might
not be exactly the same as the one you have,
but should hopefully at least use the same pinout.

Regards,

Peter


On Fri Dec 19 15:06 , ernieperes at aol.com sent:

>Hi Gents,
>
>Having a Fe5680 Rub freq standard but can not figure out the 9 pin 
connector...



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time-nuts mailing list -- time-nuts at febo.com
To unsubscribe, go to 
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.



From mpb45 at clanbaker.org  Sat Dec 20 14:25:31 2008
From: mpb45 at clanbaker.org (Michael Baker)
Date: Sat, 20 Dec 2008 09:25:31 -0500
Subject: [time-nuts] Thunderbolt accuracy...??
Message-ID: <494D005B.1010308@clanbaker.org>

Hello, TimeNutters--

John Miles, KE5FX wrote:
 > Well, sure, it's more accurate than the undisciplined
 > OCXO in the counter, that's the idea behind the Thunderbolt.  :)

n3izn at aol.com wrote:
 > I just wanted to ask the group if the
 > Thunderbolt would be more accurate than the internal reference? I
 > want to think it is but my link to the thunderbolt spec sheet is
 > no longer valid.
-------------------------------------

Some time ago, I took my T-bolt over to the Metrology and
Standards Lab at the University of Florida and set it up
to run overnight and let it do its full survey process.

In spite of the fact that the antenna was in a rather poor
location it locked up quickly and seemed to run flawlessly.

The monitoring was only intended to look at the frequency
accuracy of the 10 MHz output-- other timing characteristics
so dear to Time-Nuts hearts were ignored.

After its overnight warm-up and survey process was done,
we found (over a period of 48 hours) that the 10MHz output
was never worse than 1.0 X E-12 and was generally better than
that by a considerable margin about 90% of the time.

Mike Baker
WA4HFR
Gainesville, FL


From ne8s at earthlink.net  Sat Dec 20 18:12:08 2008
From: ne8s at earthlink.net (NE8S)
Date: Sat, 20 Dec 2008 12:12:08 -0600
Subject: [time-nuts] Query to all Time-Nuts about forum member
Message-ID: <001e01c962ce$80cccbe0$0e01a8c0@HITACHI>

Greetings to all Time-Nuts and Happy Holidays,

Has anyone heard from Chuck Norton lately?

I have been trying to contact him with no success.

Any info would me appreciated.

I sure hope that he is all right.

Doc
NE8S

From magnus at rubidium.dyndns.org  Sat Dec 20 18:13:43 2008
From: magnus at rubidium.dyndns.org (Magnus Danielson)
Date: Sat, 20 Dec 2008 19:13:43 +0100
Subject: [time-nuts] Thunderbolt accuracy...??
In-Reply-To: <494D005B.1010308@clanbaker.org>
References: <494D005B.1010308@clanbaker.org>
Message-ID: <494D35D7.3070505@rubidium.dyndns.org>

Michael Baker skrev:
> Hello, TimeNutters--
> 
> John Miles, KE5FX wrote:
>  > Well, sure, it's more accurate than the undisciplined
>  > OCXO in the counter, that's the idea behind the Thunderbolt.  :)
> 
> n3izn at aol.com wrote:
>  > I just wanted to ask the group if the
>  > Thunderbolt would be more accurate than the internal reference? I
>  > want to think it is but my link to the thunderbolt spec sheet is
>  > no longer valid.
> -------------------------------------
> 
> Some time ago, I took my T-bolt over to the Metrology and
> Standards Lab at the University of Florida and set it up
> to run overnight and let it do its full survey process.
> 
> In spite of the fact that the antenna was in a rather poor
> location it locked up quickly and seemed to run flawlessly.
> 
> The monitoring was only intended to look at the frequency
> accuracy of the 10 MHz output-- other timing characteristics
> so dear to Time-Nuts hearts were ignored.
> 
> After its overnight warm-up and survey process was done,
> we found (over a period of 48 hours) that the 10MHz output
> was never worse than 1.0 X E-12 and was generally better than
> that by a considerable margin about 90% of the time.

You should have logged the reported frequency error and compared with 
the logged error. An average over a longer period would probably go deeper.

But it does show the potential for getting pretty good accuracy for a 
small lab at a reasnoble cost. You should monitor the condition of the 
receiver to ensure you are locked, and preferably log the frequency 
error to be able to see any deviations.

Cheers,
Magnus


From N3IZN at aol.com  Sat Dec 20 19:45:10 2008
From: N3IZN at aol.com (N3IZN at aol.com)
Date: Sat, 20 Dec 2008 14:45:10 EST
Subject: [time-nuts] Thunderbolt accuracy...??
Message-ID: <c9d.3a498f89.367ea546@aol.com>

OK thanks, I couldn't find the link for the thunderbolt. The Agilent manual  
states the best it's LO is <1 X E-10, (I think). I was just thinking  
expensive test equipment that was recently calibrated versus junk GPSDO that I  
salvaged from telco equipment.
**************A Good Credit Score is 700 or Above. See yours in just 2 easy 
steps! 
(http://pr.atwola.com/promoclk/100000075x1215195222x1200993641/aol?redir=http://www.freecreditreport.com/pm/default.aspx?sc=668072%26hmpgID=82%26bcd=De
cemailfooterNO82)

From hmurray at megapathdsl.net  Sat Dec 20 20:09:20 2008
From: hmurray at megapathdsl.net (Hal Murray)
Date: Sat, 20 Dec 2008 12:09:20 -0800
Subject: [time-nuts] Thunderbolt accuracy...??
In-Reply-To: Message from N3IZN@aol.com 
	of "Sat, 20 Dec 2008 14:45:10 EST." <c9d.3a498f89.367ea546@aol.com> 
Message-ID: <20081220200921.EAC5ABCD9@ip-64-139-1-69.sjc.megapath.net>

> versus junk GPSDO

It's not junk.

What are you interested in?  Short term stability or long term accuracy?

I'd expect the GPSDO to be more accurate over the long term, but probably 
wobble around slightly at a time scale of a few seconds as the "D" tries to 
keep things on target.  An equivalent quality undisciplined crystal would 
just slowly drift over the long term.


-- 
These are my opinions, not necessarily my employer's.  I hate spam.





From magnus at rubidium.dyndns.org  Sat Dec 20 20:17:47 2008
From: magnus at rubidium.dyndns.org (Magnus Danielson)
Date: Sat, 20 Dec 2008 21:17:47 +0100
Subject: [time-nuts] Thunderbolt accuracy...??
In-Reply-To: <20081220200921.EAC5ABCD9@ip-64-139-1-69.sjc.megapath.net>
References: <20081220200921.EAC5ABCD9@ip-64-139-1-69.sjc.megapath.net>
Message-ID: <494D52EB.6060906@rubidium.dyndns.org>

Hal Murray skrev:
>> versus junk GPSDO
> 
> It's not junk.
> 
> What are you interested in?  Short term stability or long term accuracy?
> 
> I'd expect the GPSDO to be more accurate over the long term, but probably 
> wobble around slightly at a time scale of a few seconds as the "D" tries to 
> keep things on target.  An equivalent quality undisciplined crystal would 
> just slowly drift over the long term.
> 
> 

What level of stability is of interest is also significant to ask.
What kind of measurements are you going to perform and at what stability 
do you need?

Cheers,
Magnus


From w1ksz at earthlink.net  Sat Dec 20 20:32:01 2008
From: w1ksz at earthlink.net (Richard W. Solomon)
Date: Sat, 20 Dec 2008 15:32:01 -0500 (EST)
Subject: [time-nuts] Thunderbolt accuracy...??
Message-ID: <24601788.1229805122214.JavaMail.root@mswamui-bichon.atl.sa.earthlink.net>

..."junk GPSDO"... . Are you sure of that statement ?
The Cal Lab where I retired from had one of those "junk GPSDO's"
that they used. The only difference between theirs and mine (that
I built) was the 3 orders of magnitude difference in price !!

73, Dick, W1KSZ

-----Original Message-----
>From: N3IZN at aol.com
>Sent: Dec 20, 2008 2:45 PM
>To: time-nuts at febo.com
>Subject: Re: [time-nuts] Thunderbolt accuracy...??
>
>OK thanks, I couldn't find the link for the thunderbolt. The Agilent manual  
>states the best it's LO is <1 X E-10, (I think). I was just thinking  
>expensive test equipment that was recently calibrated versus junk GPSDO that I  
>salvaged from telco equipment.
>**************A Good Credit Score is 700 or Above. See yours in just 2 easy 
>steps! 
>(http://pr.atwola.com/promoclk/100000075x1215195222x1200993641/aol?redir=http://www.freecreditreport.com/pm/default.aspx?sc=668072%26hmpgID=82%26bcd=De
>cemailfooterNO82)
>_______________________________________________
>time-nuts mailing list -- time-nuts at febo.com
>To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>and follow the instructions there.



From kc0ukk at msosborn.com  Sat Dec 20 20:40:02 2008
From: kc0ukk at msosborn.com (Matt Osborn)
Date: Sat, 20 Dec 2008 14:40:02 -0600
Subject: [time-nuts] GPSDO recurring Time Interval aberation
Message-ID: <unkqk45chmtca9aj54alqd3k24ctbf1ei5@4ax.com>

I've been tracking my Fury GPSDO (ROM version 1.21) equipped with an
Isotemp OXCXO134-10 oscillator for a couple of weeks now and have
noticed that the Time Interval (TI) spikes around 20 to 40 nsec
everyday at 17:45 UTC (11:45 AM CST local time). There are minor
spikes (5 nsec) every 2 to 3 hours, but I find the large spikes to be
very curious.

The oscillator itself has no idea of the time of day (does it?), the
Fury generated EFC follows the spike and brings the TI back into line
within tow or three minutes.  There are no unusual charges to the EFC
prior to or after the spike.

I've already tracked ambient temperature over several days and have
seen nothing unusual. I'm going to monitor line voltage next.

Has anyone else ever seen such behavior?

-- kc0ukk at msosborn dot com


From dave.g0dja at tiscali.co.uk  Sat Dec 20 20:42:11 2008
From: dave.g0dja at tiscali.co.uk (Dave Ackrill)
Date: Sat, 20 Dec 2008 20:42:11 +0000
Subject: [time-nuts] Thunderbolt accuracy...??
In-Reply-To: <20081220200921.EAC5ABCD9@ip-64-139-1-69.sjc.megapath.net>
References: <20081220200921.EAC5ABCD9@ip-64-139-1-69.sjc.megapath.net>
Message-ID: <494D58A3.3050900@tiscali.co.uk>

Hal Murray wrote:
>> versus junk GPSDO
>>     
>
> It's not junk.
>
> What are you interested in?  Short term stability or long term accuracy?
>   
I'm glad to hear that the Thunderbolt is not classed as 'junk'... :-)

Personally, what I want to do is two things.  1. Keep my PC clock within 
a reasonable time frame when compared with other PC clocks for Amateur 
Radio data mode transmissions.  In this case, the actual time seems less 
important than the effective time between the other station and myself, 
so that we don't try to transmit at the same time, or receive at the 
same time.  What that time is, is not that critical, as far as I can 
see.  As long as we both agree when to transmit and when to receive.

2. I want to keep various transverters reasonably on frequency when 
compared to other people who may, or may not, be 'on frequency' so that 
we have a better chance of finding one another on UHF and SHF bands when 
we set a frequency to transmit or receive on.

The Thunderbolt 10MHz GPSDO seems ideal for this second application.  
The more accurate and stable the better, of course, but in comparison 
with some older transceiver or transverter designs the Thunderbolt 
option to lock in a frequency should be far in advance of many of the 
older hit and miss operations when trying to agree upon what frequency 
is in use on the SHF bands.

 From what I can make out, the next technique to address is to use SDR 
technology to identify when someone is even a few Hz away from where you 
think they might, or should, be.

The pursuit of perfection is a laudable goal, but it can obscure the 
original objectives that you wanted to reach, in my opinion, if you are 
not careful.

Dave (G0DJA)


From phk at phk.freebsd.dk  Sat Dec 20 20:43:24 2008
From: phk at phk.freebsd.dk (Poul-Henning Kamp)
Date: Sat, 20 Dec 2008 20:43:24 +0000
Subject: [time-nuts] GPSDO recurring Time Interval aberation
In-Reply-To: Your message of "Sat, 20 Dec 2008 14:40:02 CST."
	<unkqk45chmtca9aj54alqd3k24ctbf1ei5@4ax.com> 
Message-ID: <48828.1229805804@critter.freebsd.dk>

In message <unkqk45chmtca9aj54alqd3k24ctbf1ei5 at 4ax.com>, Matt Osborn writes:

>I've been tracking my Fury GPSDO (ROM version 1.21) equipped with an
>Isotemp OXCXO134-10 oscillator for a couple of weeks now and have
>noticed that the Time Interval (TI) spikes around 20 to 40 nsec
>everyday at 17:45 UTC (11:45 AM CST local time).

Likely a bad constellation or multipathing of a low satellite.

See which satellites come into or out of view around that time, and
consider lifting your horizon or blacklisting that particular satellite
during that time period.

-- 
Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk at FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.


From bruce.griffiths at xtra.co.nz  Sat Dec 20 21:16:36 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Sun, 21 Dec 2008 10:16:36 +1300
Subject: [time-nuts] Thunderbolt accuracy...??
In-Reply-To: <494D005B.1010308@clanbaker.org>
References: <494D005B.1010308@clanbaker.org>
Message-ID: <494D60B4.5000205@xtra.co.nz>

Mike

A statement of accuracy is of little value unless you also give:

1) An estimate of the accuracy of standard used for comparison.

2) An estimate of the random and systematic errors in the comparison

3) Some details of the comparison method.

4) Averaging time and other pertinent info.

Bruce

Michael Baker wrote:
> Hello, TimeNutters--
>
> John Miles, KE5FX wrote:
>  > Well, sure, it's more accurate than the undisciplined
>  > OCXO in the counter, that's the idea behind the Thunderbolt.  :)
>
> n3izn at aol.com wrote:
>  > I just wanted to ask the group if the
>  > Thunderbolt would be more accurate than the internal reference? I
>  > want to think it is but my link to the thunderbolt spec sheet is
>  > no longer valid.
> -------------------------------------
>
> Some time ago, I took my T-bolt over to the Metrology and
> Standards Lab at the University of Florida and set it up
> to run overnight and let it do its full survey process.
>
> In spite of the fact that the antenna was in a rather poor
> location it locked up quickly and seemed to run flawlessly.
>
> The monitoring was only intended to look at the frequency
> accuracy of the 10 MHz output-- other timing characteristics
> so dear to Time-Nuts hearts were ignored.
>
> After its overnight warm-up and survey process was done,
> we found (over a period of 48 hours) that the 10MHz output
> was never worse than 1.0 X E-12 and was generally better than
> that by a considerable margin about 90% of the time.
>
> Mike Baker
> WA4HFR
> Gainesville, FL
>
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>
>   



From magnus at rubidium.dyndns.org  Sat Dec 20 21:39:01 2008
From: magnus at rubidium.dyndns.org (Magnus Danielson)
Date: Sat, 20 Dec 2008 22:39:01 +0100
Subject: [time-nuts] Thunderbolt accuracy...??
In-Reply-To: <494D60B4.5000205@xtra.co.nz>
References: <494D005B.1010308@clanbaker.org> <494D60B4.5000205@xtra.co.nz>
Message-ID: <494D65F5.7000802@rubidium.dyndns.org>

Bruce Griffiths skrev:
> Mike
> 
> A statement of accuracy is of little value unless you also give:
> 
> 1) An estimate of the accuracy of standard used for comparison.
> 
> 2) An estimate of the random and systematic errors in the comparison
> 
> 3) Some details of the comparison method.
> 
> 4) Averaging time and other pertinent info.

True, but for an hobby enthusiast we could be a little less stringent 
(as long as we remember we are cheating) if the goal is to say: Be able 
to measure and maintain my 10 GHz signals to within 1 Hz on long term.

Achieving the frequency stability below 1E-10 for tau = 100s and above 
should not be too hard to achieve and some fairly easy means of 
monitoring the state of a Thunderbolt should be able to indicate wither 
this is met or not.

It's not that we can't achieve better performance, but if we do not need 
to be near the cutting edge but rather have fairly relaxed requirements, 
let's not complicate maters more than necessary. The one thing we do 
want to say is that things needs to be monitored, since there may be 
many sources which could make the functionality be severely degraded or 
lost.

Many forget the performance supervision aspect. GPS receivers in 
particular seems to be (fairly) cheap magical boxes which makes things 
work, and then they are forgotten all about until something breaks. The 
type of actions needed to handle the case when the service is degraded 
depends. For a ham it may very well be that he just does not really know 
where he is on the spectrum right now... but the years of previous 
measurements could at least given him some confidence on how much he 
could expect to be off now that he is not able verify or steer his rig.

(Sorry for the stereotypic identification of a ham as being "he", I know 
for a fact there is female hams out there and also sharing the same 
concerns as any male ham on where she is on the spectrum, but it was 
just convenient to type it like that.)

Cheers,
Magnus


From namichie at gmail.com  Sat Dec 20 21:50:47 2008
From: namichie at gmail.com (Neville Michie)
Date: Sun, 21 Dec 2008 08:50:47 +1100
Subject: [time-nuts] PC run FFT
Message-ID: <DFDCFE9A-9497-4AD8-9430-CBFD84C65426@gmail.com>

Hi,
does anyone know of a fast fourier transform module or subroutine  
that could be run in XCEL ?
Or a small program that could process a data set in a PC.
It is a convenient way of handling data but I have not seen a FFT in  
the box of tricks.
cheers, Neville Michie


From magnus at rubidium.dyndns.org  Sat Dec 20 22:01:52 2008
From: magnus at rubidium.dyndns.org (Magnus Danielson)
Date: Sat, 20 Dec 2008 23:01:52 +0100
Subject: [time-nuts] PC run FFT
In-Reply-To: <DFDCFE9A-9497-4AD8-9430-CBFD84C65426@gmail.com>
References: <DFDCFE9A-9497-4AD8-9430-CBFD84C65426@gmail.com>
Message-ID: <494D6B50.3080800@rubidium.dyndns.org>

Neville Michie skrev:
> Hi,

Dear Neville,

> does anyone know of a fast fourier transform module or subroutine  
> that could be run in XCEL ?
> Or a small program that could process a data set in a PC.
> It is a convenient way of handling data but I have not seen a FFT in  
> the box of tricks.

I prefer to use FFTW which is a C library which does alot of tricks in 
the background to provide the fastest FFT for your requested size on 
your particular machine. There exists a number of wrappings which makes 
it available in other languages.

You can also use Octave or similar for processing and FFT is also 
available. Some of them actually relies on FFTW nowdays.

I am Linux-oriented, but I see no reason why these should not do their 
job well on Windows etc.

Cheers,
Magnus


From bruce.griffiths at xtra.co.nz  Sat Dec 20 22:08:41 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Sun, 21 Dec 2008 11:08:41 +1300
Subject: [time-nuts] Thunderbolt accuracy...??
In-Reply-To: <494D65F5.7000802@rubidium.dyndns.org>
References: <494D005B.1010308@clanbaker.org> <494D60B4.5000205@xtra.co.nz>
	<494D65F5.7000802@rubidium.dyndns.org>
Message-ID: <494D6CE9.7020103@xtra.co.nz>

Hej Magnus

Magnus Danielson wrote:
> Bruce Griffiths skrev:
>   
>> Mike
>>
>> A statement of accuracy is of little value unless you also give:
>>
>> 1) An estimate of the accuracy of standard used for comparison.
>>
>> 2) An estimate of the random and systematic errors in the comparison
>>
>> 3) Some details of the comparison method.
>>
>> 4) Averaging time and other pertinent info.
>>     
>
> True, but for an hobby enthusiast we could be a little less stringent 
> (as long as we remember we are cheating) if the goal is to say: Be able 
> to measure and maintain my 10 GHz signals to within 1 Hz on long term.
>
>   
Some description of the method and resolution at least is desirable.
If the some parameters arent known at least say so.
If the method isnt well defined no one else can make comparable
measurements on their frequency reference.
> Achieving the frequency stability below 1E-10 for tau = 100s and above 
> should not be too hard to achieve and some fairly easy means of 
> monitoring the state of a Thunderbolt should be able to indicate wither 
> this is met or not.
>
>   
You are being vague, do you mean ADEV, MDEV or what?
High frequency stability is only part of the  requirement, the relative
frequency offset also has to be known.
> It's not that we can't achieve better performance, but if we do not need 
> to be near the cutting edge but rather have fairly relaxed requirements, 
> let's not complicate maters more than necessary. The one thing we do 
> want to say is that things needs to be monitored, since there may be 
> many sources which could make the functionality be severely degraded or 
> lost.
>
>   
No excuse for omitting measurement technique details.
Such info is essential if others are to make meaningful comparisons with
their own measurements.
> Many forget the performance supervision aspect. GPS receivers in 
> particular seems to be (fairly) cheap magical boxes which makes things 
> work, and then they are forgotten all about until something breaks. The 
> type of actions needed to handle the case when the service is degraded 
> depends. For a ham it may very well be that he just does not really know 
> where he is on the spectrum right now... but the years of previous 
> measurements could at least given him some confidence on how much he 
> could expect to be off now that he is not able verify or steer his rig.
>
>   
The important requirements appear to be that the clocks at the 2
stations should agree to within a small fraction of a second and that
the relative ADEV of the receiver and transmitter LO frequencies for tau
of a few seconds needs to be better than around 1E-11 (for the upper end
of the SHF band). To make effective use of microsecond time offsets
between station clocks would require fully automated operation and
taking the propagation delay of the transmission path into account.
> (Sorry for the stereotypic identification of a ham as being "he", I know 
> for a fact there is female hams out there and also sharing the same 
> concerns as any male ham on where she is on the spectrum, but it was 
> just convenient to type it like that.)
>
> Cheers,
> Magnus
>
>   

Bruce


From XDE-L2G3 at myamail.com  Sat Dec 20 22:08:47 2008
From: XDE-L2G3 at myamail.com (Mike Monett)
Date: Sat, 20 Dec 2008 17:08:47 -0500
Subject: [time-nuts] Thunderbolt accuracy...??
References: <mailman.578.1229805810.2499.time-nuts@febo.com>
Message-ID: <mailman.5.1229810975.2496.time-nuts@febo.com>

  >> I just  wanted to ask the group if the Thunderbolt would  be more
  >> accurate than  the internal reference? I want to think it  is but
  >> my link to the thunderbolt spec sheet is no longer valid.

  > Some time  ago,  I  took  my  T-bolt  over  to  the  Metrology and
  > Standards Lab  at the University of Florida and set it  up  to run
  > overnight and let it do its full survey process.

  > In spite  of  the  fact  that the antenna  was  in  a  rather poor
  > location it locked up quickly and seemed to run flawlessly.

  > The monitoring was only intended to look at the frequency accuracy
  > of the  10  MHz output - other timing characteristics  so  dear to
  > Time-Nuts hearts were ignored.

  > After its overnight warm-up and survey process was done,  we found
  > (over a period of 48 hours) that the 10MHz output was  never worse
  > than 1.0  X  E-12  and   was   generally  better  than  that  by a
  > considerable margin about 90% of the time.

  > Mike Baker
  > WA4HFR
  > Gainesville, FL

  Mike, thanks  for  the info. These real-world data  points  are very
  valuable. I have some questions:

  What frequency  reference did they use at  the  university standards
  lab to  measure the T-Bolt frequency? And how did  they  measure its
  frequency?

  How did  they do the comparison to your TBolt? If it was  a counter,
  what kind was it?

  You mentioned the error was better than 1e-12 90% of the  time. What
  was the average error?

  Thanks,

  Mike Monett


From bruce.griffiths at xtra.co.nz  Sat Dec 20 22:11:47 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Sun, 21 Dec 2008 11:11:47 +1300
Subject: [time-nuts] PC run FFT
In-Reply-To: <DFDCFE9A-9497-4AD8-9430-CBFD84C65426@gmail.com>
References: <DFDCFE9A-9497-4AD8-9430-CBFD84C65426@gmail.com>
Message-ID: <494D6DA3.7030904@xtra.co.nz>

Neville Michie wrote:
> Hi,
> does anyone know of a fast fourier transform module or subroutine  
> that could be run in XCEL ?
> Or a small program that could process a data set in a PC.
> It is a convenient way of handling data but I have not seen a FFT in  
> the box of tricks.
> cheers, Neville Michie
>
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>
>   
Neville

There is a DFT routine built into Excel:

http://blogs.epfl.ch/document/11828

Bruce


From rexa at sonic.net  Sat Dec 20 22:42:50 2008
From: rexa at sonic.net (Rex)
Date: Sat, 20 Dec 2008 14:42:50 -0800
Subject: [time-nuts] Thunderbolt accuracy...??
In-Reply-To: <24601788.1229805122214.JavaMail.root@mswamui-bichon.atl.sa.earthlink.net>
References: <24601788.1229805122214.JavaMail.root@mswamui-bichon.atl.sa.earthlink.net>
Message-ID: <494D74EA.4060206@sonic.net>

Richard W. Solomon wrote:
> ..."junk GPSDO"... . Are you sure of that statement ?
> The Cal Lab where I retired from had one of those "junk GPSDO's"
> that they used. The only difference between theirs and mine (that
> I built) was the 3 orders of magnitude difference in price !!
>
> 73, Dick, W1KSZ
>
>   

He said, [a] "junk GPSDO that I salvaged from telco equipment."

A poor choice of words, perhaps, but I think the intention may be that 
the telco took it out of service for some reason and "junked" it. Not 
necessarily an adjective denoting quality. More than 90 % of my 
high-tech equipment is "junk".




From bruce.griffiths at xtra.co.nz  Sat Dec 20 22:47:10 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Sun, 21 Dec 2008 11:47:10 +1300
Subject: [time-nuts] PC run FFT
In-Reply-To: <DFDCFE9A-9497-4AD8-9430-CBFD84C65426@gmail.com>
References: <DFDCFE9A-9497-4AD8-9430-CBFD84C65426@gmail.com>
Message-ID: <494D75EE.2000703@xtra.co.nz>

Neville

Ulrich's Plotter program has some built in FFT capability.

Bruce

Neville Michie wrote:
> Hi,
> does anyone know of a fast fourier transform module or subroutine  
> that could be run in XCEL ?
> Or a small program that could process a data set in a PC.
> It is a convenient way of handling data but I have not seen a FFT in  
> the box of tricks.
> cheers, Neville Michie
>
>   



From biwa at att.net  Sat Dec 20 23:03:07 2008
From: biwa at att.net (Burt I. Weiner)
Date: Sat, 20 Dec 2008 15:03:07 -0800
Subject: [time-nuts] Thunderbolt Accuracy needs...
In-Reply-To: <mailman.582.1229813238.2499.time-nuts@febo.com>
References: <mailman.582.1229813238.2499.time-nuts@febo.com>
Message-ID: <7.0.0.16.2.20081220145925.03835148@att.net>

I suppose a good comparison would be: How accurate does the 
speedometer in the car really need to be and why.

Burt, K6OQK

>From: Magnus Danielson <magnus at rubidium.dyndns.org>
>Subject: Re: [time-nuts] Thunderbolt accuracy...??
>
>sniped...
>It's not that we can't achieve better performance, but if we do not need
>to be near the cutting edge but rather have fairly relaxed requirements,
>let's not complicate maters more than necessary. The one thing we do
>want to say is that things needs to be monitored, since there may be
>many sources which could make the functionality be severely degraded or
>lost.

Burt I. Weiner Associates
Broadcast Technical Services
Glendale, California  U.S.A.
biwa at att.net
K6OQK 



From alan.melia at btinternet.com  Sat Dec 20 23:24:37 2008
From: alan.melia at btinternet.com (Alan Melia)
Date: Sat, 20 Dec 2008 23:24:37 -0000
Subject: [time-nuts] PC run FFT
References: <DFDCFE9A-9497-4AD8-9430-CBFD84C65426@gmail.com>
Message-ID: <004c01c962fa$22ca5040$0900a8c0@AM>

Neville there is a Fourier routine built in I have used it for time sequence
analysis. It is not loaded by default. You may have to check the dropdown
menus to load it in (at least that was what I needed to do, but I am mean
and running an old Op-system :-)) )

Cheers de Alan G3NYK

----- Original Message -----
From: "Neville Michie" <namichie at gmail.com>
To: "Discussion of precise time and frequency measurement"
<time-nuts at febo.com>
Sent: Saturday, December 20, 2008 9:50 PM
Subject: [time-nuts] PC run FFT


> Hi,
> does anyone know of a fast fourier transform module or subroutine
> that could be run in XCEL ?
> Or a small program that could process a data set in a PC.
> It is a convenient way of handling data but I have not seen a FFT in
> the box of tricks.
> cheers, Neville Michie
>
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.



From magnus at rubidium.dyndns.org  Sat Dec 20 23:31:35 2008
From: magnus at rubidium.dyndns.org (Magnus Danielson)
Date: Sun, 21 Dec 2008 00:31:35 +0100
Subject: [time-nuts] Thunderbolt accuracy...??
In-Reply-To: <494D74EA.4060206@sonic.net>
References: <24601788.1229805122214.JavaMail.root@mswamui-bichon.atl.sa.earthlink.net>
	<494D74EA.4060206@sonic.net>
Message-ID: <494D8057.6070109@rubidium.dyndns.org>

Rex skrev:
> Richard W. Solomon wrote:
>> ..."junk GPSDO"... . Are you sure of that statement ?
>> The Cal Lab where I retired from had one of those "junk GPSDO's"
>> that they used. The only difference between theirs and mine (that
>> I built) was the 3 orders of magnitude difference in price !!
>>
>> 73, Dick, W1KSZ
>>
>>   
> 
> He said, [a] "junk GPSDO that I salvaged from telco equipment."
> 
> A poor choice of words, perhaps, but I think the intention may be that 
> the telco took it out of service for some reason and "junked" it. Not 
> necessarily an adjective denoting quality. More than 90 % of my 
> high-tech equipment is "junk".

We can be happy that telcos etc. work on a system thinking. While they 
shift systems they can't handle little details like re-use of GPSDOs 
even thought they would still do a good job even for the new system.

Cheers,
Magnus


From iovane at inwind.it  Sat Dec 20 23:59:31 2008
From: iovane at inwind.it (iovane at inwind.it)
Date: Sun, 21 Dec 2008 00:59:31 +0100
Subject: [time-nuts] PC run FFT
Message-ID: <KC79B7$64AAC195427A4B87BB6EDF162556FABF@libero.it>

I've been using the Xcel built in FFT, and even under WinXP it
should be intentionally installed.
The path for doing so is (translating from Italian):
tools>additional components>analysis tools
then follow the instructions.
The function will be available as "data analysis", I don't 
remember if under the "tools" or "data" dropdown menu (not yet
installed it on this PC).
If I recall, it works only with data sets long powers_of_two,
and handles max 4096 data points.

Antonio I8IOV

> Neville there is a Fourier routine built in I have used it for time sequence
> analysis. It is not loaded by default. You may have to check the dropdown
> menus to load it in (at least that was what I needed to do, but I am mean
> and running an old Op-system :-)) )
> 
> Cheers de Alan G3NYK
> 
> > Hi,
> > does anyone know of a fast fourier transform module or subroutine
> > that could be run in XCEL ?
> > Or a small program that could process a data set in a PC.
> > It is a convenient way of handling data but I have not seen a FFT in
> > the box of tricks.
> > cheers, Neville Michie
> >
> > _______________________________________________
> > time-nuts mailing list -- time-nuts at febo.com
> > To unsubscribe, go to
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> > and follow the instructions there.
> 
> 
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
> 



From ebwalker at embarqmail.com  Sun Dec 21 00:26:14 2008
From: ebwalker at embarqmail.com (Edwin B. Walker)
Date: Sat, 20 Dec 2008 19:26:14 -0500
Subject: [time-nuts] Thunderbolt accuracy...??
In-Reply-To: <494D74EA.4060206@sonic.net>
References: <24601788.1229805122214.JavaMail.root@mswamui-bichon.atl.sa.earthlink.net>
	<494D74EA.4060206@sonic.net>
Message-ID: <BEF3D75312804F8781DAF1FC080CA5AC@EdwinBWalkerPC>

I wonder if companies don't junk equipment because "electrolytic capacitors 
last years not decades" Does this  make sense?

Ed
----- Original Message ----- 
From: "Rex" <rexa at sonic.net>
To: "Discussion of precise time and frequency measurement" 
<time-nuts at febo.com>
Sent: Saturday, December 20, 2008 5:42 PM
Subject: Re: [time-nuts] Thunderbolt accuracy...??


> Richard W. Solomon wrote:
>> ..."junk GPSDO"... . Are you sure of that statement ?
>> The Cal Lab where I retired from had one of those "junk GPSDO's"
>> that they used. The only difference between theirs and mine (that
>> I built) was the 3 orders of magnitude difference in price !!
>>
>> 73, Dick, W1KSZ
>>
>>
>
> He said, [a] "junk GPSDO that I salvaged from telco equipment."
>
> A poor choice of words, perhaps, but I think the intention may be that
> the telco took it out of service for some reason and "junked" it. Not
> necessarily an adjective denoting quality. More than 90 % of my
> high-tech equipment is "junk".
>
>
>
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to 
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
> 



From namichie at gmail.com  Sun Dec 21 00:28:43 2008
From: namichie at gmail.com (Neville Michie)
Date: Sun, 21 Dec 2008 11:28:43 +1100
Subject: [time-nuts] PC run FFT
In-Reply-To: <KC79B7$64AAC195427A4B87BB6EDF162556FABF@libero.it>
References: <KC79B7$64AAC195427A4B87BB6EDF162556FABF@libero.it>
Message-ID: <4DD25923-3A82-4E92-A5BC-CA4D304254AF@gmail.com>

Thanks all,
I had looked but did not see...
I have found the function in Excel,
now I will revise the subject with Bracewell
and try to use it.
Thanks, Neville Michie






On 21/12/2008, at 10:59 AM, iovane@@inwind..it wrote:

> I've been using the Xcel built in FFT, and even under WinXP it
> should be intentionally installed.
> The path for doing so is (translating from Italian):
> tools>additional components>analysis tools
> then follow the instructions.
> The function will be available as "data analysis", I don't
> remember if under the "tools" or "data" dropdown menu (not yet
> installed it on this PC).
> If I recall, it works only with data sets long powers_of_two,
> and handles max 4096 data points.
>
> Antonio I8IOV
>
>> Neville there is a Fourier routine built in I have used it for  
>> time sequence
>> analysis. It is not loaded by default. You may have to check the  
>> dropdown
>> menus to load it in (at least that was what I needed to do, but I  
>> am mean
>> and running an old Op-system :-)) )
>>
>> Cheers de Alan G3NYK
>>
>>> Hi,
>>> does anyone know of a fast fourier transform module or subroutine
>>> that could be run in XCEL ?
>>> Or a small program that could process a data set in a PC.
>>> It is a convenient way of handling data but I have not seen a FFT in
>>> the box of tricks.
>>> cheers, Neville Michie
>>>
>>> _______________________________________________
>>> time-nuts mailing list -- time-nuts at febo.com
>>> To unsubscribe, go to
>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>>> and follow the instructions there.
>>
>>
>> _______________________________________________
>> time-nuts mailing list -- time-nuts at febo.com
>> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/ 
>> listinfo/time-nuts
>> and follow the instructions there.
>>
>
>
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/ 
> time-nuts
> and follow the instructions there.



From magnus at rubidium.dyndns.org  Sun Dec 21 00:44:17 2008
From: magnus at rubidium.dyndns.org (Magnus Danielson)
Date: Sun, 21 Dec 2008 01:44:17 +0100
Subject: [time-nuts] Thunderbolt accuracy...??
In-Reply-To: <BEF3D75312804F8781DAF1FC080CA5AC@EdwinBWalkerPC>
References: <24601788.1229805122214.JavaMail.root@mswamui-bichon.atl.sa.earthlink.net>	<494D74EA.4060206@sonic.net>
	<BEF3D75312804F8781DAF1FC080CA5AC@EdwinBWalkerPC>
Message-ID: <494D9161.5060704@rubidium.dyndns.org>

Edwin B. Walker skrev:
> I wonder if companies don't junk equipment because "electrolytic capacitors 
> last years not decades" Does this  make sense?

No. Details like that does not comes into play. If the quality of the 
gear does not match the specs, the manufacturer gets a serious problems 
so they choose components accordingly. They kick the manufacturer around 
or they choose another if worse comes to worse. Shifting out systems is 
a much bigger thing. It is about being able to provide the needed 
services, ensuring the revenue stream. Shifting out old systems can also 
release frequency spectrum for new more efficient services. This may be 
at the control of the spectrum authority.

So issues like poor capacitors does not really come up. Telco runs quite 
a different ship than consumer PCs. Way different.

Cheers,
Magnus


From kirbybq at bellsouth.net  Sun Dec 21 01:04:00 2008
From: kirbybq at bellsouth.net (Brian Kirby)
Date: Sat, 20 Dec 2008 19:04:00 -0600
Subject: [time-nuts] Thunderbolt accuracy...??
In-Reply-To: <BEF3D75312804F8781DAF1FC080CA5AC@EdwinBWalkerPC>
References: <24601788.1229805122214.JavaMail.root@mswamui-bichon.atl.sa.earthlink.net>	<494D74EA.4060206@sonic.net>
	<BEF3D75312804F8781DAF1FC080CA5AC@EdwinBWalkerPC>
Message-ID: <494D9600.6080101@bellsouth.net>

I do not think so.  Most telephone company stuff is engineered to last 
20+ years - it takes them a few years to recoup there investments cost 
wise, and the electronics are usually close to mil specs.

Probably what happens, is they engineer a whole new system and all the 
old systems , racks and all go.

Brian KD4FM

Edwin B. Walker wrote:
> I wonder if companies don't junk equipment because "electrolytic capacitors 
> last years not decades" Does this  make sense?
> 
> Ed
> ----- Original Message ----- 
> From: "Rex" <rexa at sonic.net>
> To: "Discussion of precise time and frequency measurement" 
> <time-nuts at febo.com>
> Sent: Saturday, December 20, 2008 5:42 PM
> Subject: Re: [time-nuts] Thunderbolt accuracy...??
> 
> 
>> Richard W. Solomon wrote:
>>> ..."junk GPSDO"... . Are you sure of that statement ?
>>> The Cal Lab where I retired from had one of those "junk GPSDO's"
>>> that they used. The only difference between theirs and mine (that
>>> I built) was the 3 orders of magnitude difference in price !!
>>>
>>> 73, Dick, W1KSZ
>>>
>>>
>> He said, [a] "junk GPSDO that I salvaged from telco equipment."
>>
>> A poor choice of words, perhaps, but I think the intention may be that
>> the telco took it out of service for some reason and "junked" it. Not
>> necessarily an adjective denoting quality. More than 90 % of my
>> high-tech equipment is "junk".
>>
>>
>>
>> _______________________________________________
>> time-nuts mailing list -- time-nuts at febo.com
>> To unsubscribe, go to 
>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>> and follow the instructions there.
>>
> 
> 
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
> 


From james.p.lux at jpl.nasa.gov  Sun Dec 21 01:07:07 2008
From: james.p.lux at jpl.nasa.gov (Lux, James P)
Date: Sat, 20 Dec 2008 17:07:07 -0800
Subject: [time-nuts] Thunderbolt accuracy...??
In-Reply-To: <494D9161.5060704@rubidium.dyndns.org>
Message-ID: <C572D6BB.3AB5%James.P.Lux@jpl.nasa.gov>




On 12/20/08 4:44 PM, "Magnus Danielson" <magnus at rubidium.dyndns.org> wrote:

> Edwin B. Walker skrev:
>> I wonder if companies don't junk equipment because "electrolytic capacitors
>> last years not decades" Does this  make sense?
>
> No. Details like that does not comes into play. If the quality of the
> gear does not match the specs, the manufacturer gets a serious problems
> so they choose components accordingly. They kick the manufacturer around
> or they choose another if worse comes to worse. Shifting out systems is
> a much bigger thing. It is about being able to provide the needed
> services, ensuring the revenue stream. Shifting out old systems can also
> release frequency spectrum for new more efficient services. This may be
> at the control of the spectrum authority.
>
> So issues like poor capacitors does not really come up. Telco runs quite
> a different ship than consumer PCs. Way different.
>

Even if the basic function is sound, in a large operation, there's value to
having a limited number of different kinds of equipment around.  You have
smaller training costs, interoperability is easier, etc.  Say you have 5000
cell sites, each with a widget that's a few years old, and now you're adding
another 5000 new sites, and the old widget's not available.  It might
actually be easier and cheaper in a lifecycle cost sense to buy 10,000 new
widgets and scrap/junk the 5000 old ones.  Your maintenance manual only
needs to cover one kind of widget, your depots only have to stock 1 kind of
spare, etc.

Furthermore, the "book value" of the widgets being scrapped might be zero
(having taken accelerated depreciation of 3 years, for instance), so from a
corporate standpoint, selling them for cheap is a good thing.


You'll see this in the desktop PC market for large companies, where the cost
to support multiple hardware configurations is substantial, and where
there's a fairly standard 3 year amortization cycle.  At some point, keeping
that 5 year old PC working just isn't worth it. (Oh, only Bob knows how to
fix that one, so you won't get your computer fixed today, because Bob's on
another call or on vacation, sorry, key employee doing mission critical job,
you're out of luck.)

Even for test equipment, there's good reasons to cycle through new gear in a
fairly short time. Especially if you're changing test configurations a lot,
you want to encourage "model number independence" and not depend on
peculiarities of a particular instrument, otherwise you wind up with
specialized test sets with 20-25 year old signal generators (I'm looking at
YOU, you old HP 8663s) that can't be repaired, and because nobody has been
following along, using something new is a major jump, rather than a small
update. (And you find out that Agilent Exxxx models have very different
operating peculiarities from their predecessors with similar model #s, even
if they do work better by all rational evaluations.).

To those tinkering at home, though, this cycling through is great.. If
you're willing to fix it yourself, and maybe have a hangar queen or princess
for parts, or you don't need ALL the functions to work (never needed that
knob anyway..), then you too get really nice gear to work with. (and,
besides there's something really satisfying about that orange glow of the
Nixies... It impresses people who see your garage, because its redolent of
Atomic Age science fiction movies of the 60s and 70s.)

Jim






From SAIDJACK at aol.com  Sun Dec 21 01:36:32 2008
From: SAIDJACK at aol.com (SAIDJACK at aol.com)
Date: Sat, 20 Dec 2008 20:36:32 EST
Subject: [time-nuts] GPSDO recurring Time Interval aberation
Message-ID: <c52.41b9d796.367ef7a0@aol.com>

Hi there,
 
this could also be caused by a slight error in the Auto Survey  position of 
the Fury GPSDO.
 
The M12 does the auto survey over 3 hours, so you are limited to the  
accuracy and constellation of the Sats during that time period. You could try  the 
following to improve your position accuracy:
 
1) Write down your present hold position.
 
2) Do another auto survey, preferably at night if you did the first one  
during the day, or during the day if you did it at night etc.
 
3) Average the two resulting positions, pay particular attention to  Antenna  
height. For example if you get a height of 45 meters and 47 meters  from the 
two measurements, use 46 meters as the averaged result.
 
4) Enter the averaged position into the unit manually by using the:
 
   GPS:POS
 
and:
 
   GPS:POS LAST
 
commands.
 
5) Repeat from 1) as necessary.
 
Additionally you could try:
 
6) Increase your Mask angle from 10 Degrees with the command  
GPS:SAT:TRAC:EMAN 20
 
7) Make sure the M12 TRAIM is turned on with the command:
 
   GPS:REF:TRAIM ON
 
Hope that helps,
bye,
Said
 
 
In a message dated 12/20/2008 12:40:28 Pacific Standard Time,  
kc0ukk at msosborn.com writes:

I've  been tracking my Fury GPSDO (ROM version 1.21) equipped with an
Isotemp  OXCXO134-10 oscillator for a couple of weeks now and have
noticed that the  Time Interval (TI) spikes around 20 to 40 nsec
everyday at 17:45 UTC (11:45  AM CST local time). There are minor
spikes (5 nsec) every 2 to 3 hours, but  I find the large spikes to be
very curious.

The oscillator itself  has no idea of the time of day (does it?), the
Fury generated EFC follows  the spike and brings the TI back into line
within tow or three  minutes.  There are no unusual charges to the EFC
prior to or after  the spike.

I've already tracked ambient temperature over several days  and have
seen nothing unusual. I'm going to monitor line voltage  next.

Has anyone else ever seen such behavior?

-- kc0ukk at  msosborn dot com



From magnus at rubidium.dyndns.org  Sun Dec 21 01:37:57 2008
From: magnus at rubidium.dyndns.org (Magnus Danielson)
Date: Sun, 21 Dec 2008 02:37:57 +0100
Subject: [time-nuts] Thunderbolt accuracy...??
In-Reply-To: <C572D6BB.3AB5%James.P.Lux@jpl.nasa.gov>
References: <C572D6BB.3AB5%James.P.Lux@jpl.nasa.gov>
Message-ID: <494D9DF5.7060606@rubidium.dyndns.org>

Lux, James P skrev:
> 
> 
> On 12/20/08 4:44 PM, "Magnus Danielson" <magnus at rubidium.dyndns.org> wrote:
> 
>> Edwin B. Walker skrev:
>>> I wonder if companies don't junk equipment because "electrolytic capacitors
>>> last years not decades" Does this  make sense?
>> No. Details like that does not comes into play. If the quality of the
>> gear does not match the specs, the manufacturer gets a serious problems
>> so they choose components accordingly. They kick the manufacturer around
>> or they choose another if worse comes to worse. Shifting out systems is
>> a much bigger thing. It is about being able to provide the needed
>> services, ensuring the revenue stream. Shifting out old systems can also
>> release frequency spectrum for new more efficient services. This may be
>> at the control of the spectrum authority.
>>
>> So issues like poor capacitors does not really come up. Telco runs quite
>> a different ship than consumer PCs. Way different.
>>
> 
> Even if the basic function is sound, in a large operation, there's value to
> having a limited number of different kinds of equipment around.  You have
> smaller training costs, interoperability is easier, etc.  Say you have 5000
> cell sites, each with a widget that's a few years old, and now you're adding
> another 5000 new sites, and the old widget's not available.  It might
> actually be easier and cheaper in a lifecycle cost sense to buy 10,000 new
> widgets and scrap/junk the 5000 old ones.  Your maintenance manual only
> needs to cover one kind of widget, your depots only have to stock 1 kind of
> spare, etc.

Indeed. When running such a large network, having a consistent network 
management system is crutial. The network management needs to know all 
key boxes in the system, be able to control them, be able to take alarms 
from them and be able to provide good information to the team doing the 
24x7 hours of network operation. These people cost good hours and must 
be able to take actions to ensure the network functionality. Large set 
of diversity is a problem in such cases. Designing network management 
software that makes the two boxes act and behave in the same fasion, 
making the manuals for the support team etc. becomes more expensive. To 
support that telcos spend alot of effort to ensure there is standards 
and multiple vendors for the same box-role to ensure that not a single 
vendor can skirt them up or dry up.

> Furthermore, the "book value" of the widgets being scrapped might be zero
> (having taken accelerated depreciation of 3 years, for instance), so from a
> corporate standpoint, selling them for cheap is a good thing.

Indeed.

One should recall that for a telco, the actual equipment cost is only a 
part of the cost. Operational costs, maintenance cost and installations 
costs includes so much more.

So gear being phased out from a telco may have no value for them but may 
not be without value outside of their framework.

However, not phasing out equipment in time to keep consistency can also 
bite back. One telco for instance had their complete network failed as 
their GPS receivers (same model thoughout) did not support a certain PRN 
number, and as long as it was not overhead they would work, but fail as 
it came up again.

Let's just say that the customers where not impressed and happy about 
it, they had to make a very quick (and hence more expensive) buy-up and 
replacement.

> You'll see this in the desktop PC market for large companies, where the cost
> to support multiple hardware configurations is substantial, and where
> there's a fairly standard 3 year amortization cycle.  At some point, keeping
> that 5 year old PC working just isn't worth it. (Oh, only Bob knows how to
> fix that one, so you won't get your computer fixed today, because Bob's on
> another call or on vacation, sorry, key employee doing mission critical job,
> you're out of luck.)

Another aspect may be that you want to shift them out before they die on 
you and in a way that kills you more than the loss of the machine... 
loss of data. Loss of access to data is annoying but can painstaking and 
critical in itself, however usually that spreads out a bit. Loosing 
critical data and not being able to get it back is worse.
Being able to support the set of applications needed and upgrading OS 
and applications is an issue. In just about three years machines seems 
small and weak, but can still work on for a while. In 5 years another 
upgrade becomes troublesome. At the same time the actual hardware cost 
as gone down. Upgrading to a OK machine has become much less a hardware 
issue than the cost of managing it.

> Even for test equipment, there's good reasons to cycle through new gear in a
> fairly short time. Especially if you're changing test configurations a lot,
> you want to encourage "model number independence" and not depend on
> peculiarities of a particular instrument, otherwise you wind up with
> specialized test sets with 20-25 year old signal generators (I'm looking at
> YOU, you old HP 8663s) that can't be repaired, and because nobody has been
> following along, using something new is a major jump, rather than a small
> update. (And you find out that Agilent Exxxx models have very different
> operating peculiarities from their predecessors with similar model #s, even
> if they do work better by all rational evaluations.).

Developing and revising test rigs comes at a fairly high cost. Being 
able to support the same command-set to ease drop-in-replacements is one 
way to achieve things. For a production line setup, being able to swap 
in instruments to handle scheduled calibrations should also be 
considered. As a source of instrument dry up, this could lead to stalls 
in the production. In the end, it could mean the death of that product.
With dry up it can mean that the instrument support has been dropped for 
instance. Being able to keep it calibrated could be an issue. Loosing 
calibration due to loss of battery power is another issue.

> To those tinkering at home, though, this cycling through is great.. If
> you're willing to fix it yourself, and maybe have a hangar queen or princess
> for parts, or you don't need ALL the functions to work (never needed that
> knob anyway..), then you too get really nice gear to work with. (and,
> besides there's something really satisfying about that orange glow of the
> Nixies... It impresses people who see your garage, because its redolent of
> Atomic Age science fiction movies of the 60s and 70s.)

Certainly. Let's not complain or whine about it. We are winners on this. 
Most of the time.

Cheers,
Magnus


From harmon52 at mchsi.com  Sun Dec 21 01:58:38 2008
From: harmon52 at mchsi.com (Robert Harmon)
Date: Sat, 20 Dec 2008 19:58:38 -0600
Subject: [time-nuts] TBolt deliveries from Oct 19 announcement of group buy
Message-ID: <1D5FBAD1D5334F2587EB3D382B201B47@bobsp4>

On Oct 19, I saw on this list an announcement from Tom Van Baak mentioning
another group buy of the TBolt:

 

>Message: 6

>Date: Sun, 19 Oct 2008 18:18:54 -0700

>From: "Tom Van Baak" <tvb at LeapSecond.com>

>Subject: [time-nuts] Thunderbolt Group Buy, part 3

>To: "Discussion of precise time and frequency measurement"

>          <time-nuts at febo.com>

>Message-ID: <000901c93251$d5b071a0$0500a8c0 at pc52>

>Content-Type: text/plain; format=flowed; charset="Windows-1252";

>          reply-type=original

> 

>Thunderbolt group buy: MORE kits and NEW price.

> 

 

I responded that evening and ordered one unit.

 

I got this response from TAPR:

 

>If you wish to make any changes, add special instructions, or inquire about
your order, REPLY TO THIS >MESSAGE and place your comment at the TOP of the
message.  Please DO NOT change the subject of the message >because this will
be the key to matching up the additional messages with the original order.  

> 

>Order Summary

> 

>Item 1     Qty: 1      Thunderbolt

> 

> 

>No virus found in this incoming message.

>Checked by AVG - http://www.avg.com <http://www.avg.com/> 

>Version: 8.0.169 / Virus Database: 270.8.1/1733 - Release Date: 10/19/2008
6:02 PM

 

I have inquired several times to TAPR and Tom about delivery times. Is it
normal to have to wait for two months for these things? If that wait time is
normal, then that's OK with me. I just have a feeling that my order was
overlooked.

 

Have any of you ordered one shortly after Oct 19 and received it?

Thanks,

 

73, Bob, WB0SVU

 


From cfharris at erols.com  Sun Dec 21 02:12:13 2008
From: cfharris at erols.com (Chuck Harris)
Date: Sat, 20 Dec 2008 21:12:13 -0500
Subject: [time-nuts] TBolt deliveries from Oct 19 announcement of group
 buy
In-Reply-To: <1D5FBAD1D5334F2587EB3D382B201B47@bobsp4>
References: <1D5FBAD1D5334F2587EB3D382B201B47@bobsp4>
Message-ID: <494DA5FD.70208@erols.com>

Tom is just one guy who is doing this because he wants
to help his fellow time-nuts... and to play with some of
his toys.

He tests every single unit that goes through the system,
discarding those that don't meet his standards.

A couple of months is normal, and frankly, we are lucky
that it doesn't take longer.

Smile!  You will get your t-bolt.

-Chuck Harris

Robert Harmon wrote:
> On Oct 19, I saw on this list an announcement from Tom Van Baak mentioning
> another group buy of the TBolt:
> 
>  
> 
>> Message: 6
> 
>> Date: Sun, 19 Oct 2008 18:18:54 -0700
> 
>> From: "Tom Van Baak" <tvb at LeapSecond.com>
> 
>> Subject: [time-nuts] Thunderbolt Group Buy, part 3
> 
>> To: "Discussion of precise time and frequency measurement"
> 
>>          <time-nuts at febo.com>
> 
>> Message-ID: <000901c93251$d5b071a0$0500a8c0 at pc52>
> 
>> Content-Type: text/plain; format=flowed; charset="Windows-1252";
> 
>>          reply-type=original
> 
> 
>> Thunderbolt group buy: MORE kits and NEW price.
> 
> 
>  
> 
> I responded that evening and ordered one unit.
> 
>  
> 
> I got this response from TAPR:
> 
>  
> 
>> If you wish to make any changes, add special instructions, or inquire about
> your order, REPLY TO THIS >MESSAGE and place your comment at the TOP of the
> message.  Please DO NOT change the subject of the message >because this will
> be the key to matching up the additional messages with the original order.  
> 
> 
>> Order Summary
> 
> 
>> Item 1     Qty: 1      Thunderbolt
> 
> 
> 
>> No virus found in this incoming message.
> 
>> Checked by AVG - http://www.avg.com <http://www.avg.com/> 
> 
>> Version: 8.0.169 / Virus Database: 270.8.1/1733 - Release Date: 10/19/2008
> 6:02 PM
> 
>  
> 
> I have inquired several times to TAPR and Tom about delivery times. Is it
> normal to have to wait for two months for these things? If that wait time is
> normal, then that's OK with me. I just have a feeling that my order was
> overlooked.
> 
>  
> 
> Have any of you ordered one shortly after Oct 19 and received it?
> 
> Thanks,
> 
>  
> 
> 73, Bob, WB0SVU
> 
>  
> 
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
> 


From mpb45 at clanbaker.org  Sun Dec 21 06:48:58 2008
From: mpb45 at clanbaker.org (Michael Baker)
Date: Sun, 21 Dec 2008 01:48:58 -0500
Subject: [time-nuts] Old nixie tube displays
Message-ID: <494DE6DA.5060606@clanbaker.org>

Hello, Time-Nutters--

Jim Lux wrote:

To those tinkering at home, though, this cycling through is great.. If
you're willing to fix it yourself, and maybe have a hangar queen or princess
for parts, or you don't need ALL the functions to work (never needed that
knob anyway..), then you too get really nice gear to work with. (and,
besides there's something really satisfying about that orange glow of the
Nixies... It impresses people who see your garage, because its redolent of
Atomic Age science fiction movies of the 60s and 70s.)
--------------------

For what it is worth, I keep a couple of vintage
HP counters, sweepers and timers operational in my
shop simply because they are so, well... kuel.
Besides, the flickering of the nixie tubes impresses
the natives.  You gotta admit, an old 10 digit HP
frequency counter cycling away on its internal reference
just oozes panache....

Mike Baker
---------------------------


From ka2cdk at cox.net  Sun Dec 21 07:11:50 2008
From: ka2cdk at cox.net (Thomas A. Frank)
Date: Sun, 21 Dec 2008 02:11:50 -0500
Subject: [time-nuts] Thunderbolt Accuracy needs...
In-Reply-To: <7.0.0.16.2.20081220145925.03835148@att.net>
References: <mailman.582.1229813238.2499.time-nuts@febo.com>
	<7.0.0.16.2.20081220145925.03835148@att.net>
Message-ID: <80978102-0B27-4F46-9506-594F257FF755@cox.net>

On Dec 20, 2008, at 6:03 PM, Burt I. Weiner wrote:

> I suppose a good comparison would be: How accurate does the
> speedometer in the car really need to be and why.

Accurate enough so that if its reading matches the posted sign, you  
don't receive a ticket?

Tom Frank, KA2CDK




From brooke at pacific.net  Sun Dec 21 07:28:18 2008
From: brooke at pacific.net (Brooke Clarke)
Date: Sat, 20 Dec 2008 23:28:18 -0800
Subject: [time-nuts] Thunderbolt Accuracy needs...
In-Reply-To: <80978102-0B27-4F46-9506-594F257FF755@cox.net>
References: <mailman.582.1229813238.2499.time-nuts@febo.com>	<7.0.0.16.2.20081220145925.03835148@att.net>
	<80978102-0B27-4F46-9506-594F257FF755@cox.net>
Message-ID: <494DF012.9050102@pacific.net>

Hi Tom:

Or, certifiable that it was reading low getting you out of a ticket.
The judge told me I could use this only once.

Have Fun,

Brooke Clarke
http://www.prc68.com

Thomas A. Frank wrote:
> On Dec 20, 2008, at 6:03 PM, Burt I. Weiner wrote:
> 
>> I suppose a good comparison would be: How accurate does the
>> speedometer in the car really need to be and why.
> 
> Accurate enough so that if its reading matches the posted sign, you  
> don't receive a ticket?
> 
> Tom Frank, KA2CDK
> 
> 
> 
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
> 
> 



From pe1rks at xs4all.nl  Sun Dec 21 13:07:50 2008
From: pe1rks at xs4all.nl (S. Nestra)
Date: Sun, 21 Dec 2008 14:07:50 +0100
Subject: [time-nuts] Request for info/doc's FEI FE-1000Q
Message-ID: <494E3FA6.5050604@xs4all.nl>


Hello all,

I have recently acquired a rackmount frequency standard made by FEI for 
Marconi.
It consists of two FE-1000Q standards, wich consist of the following 
modules:
FE-10A Oscillator
FE-20B Power Supply
FE-30  Battery Box
Since one of the inner ovens is not stable, I was wondering if someone 
on this list has some documentation for this apparatus?
Also is one of the battery boxes missing, so if someone has a spare and 
is willing to part with it.

Sincerely,

Stijn Nestra


From mpb45 at clanbaker.org  Sun Dec 21 14:09:40 2008
From: mpb45 at clanbaker.org (Michael Baker)
Date: Sun, 21 Dec 2008 09:09:40 -0500
Subject: [time-nuts] How good is my T-bolt...??
Message-ID: <494E4E24.1040100@clanbaker.org>

Hello, Time-Nutters--

Bruce said:

 > A statement of accuracy is of little value unless you also give:
 > 1) An estimate of the accuracy of standard used for comparison.
 > 2) An estimate of the random and systematic errors in the comparison
 > 3) Some details of the comparison method.
 > 4) Averaging time and other pertinent info.
------------------------------

Mike asked:

 > What frequency  reference did they use at  the  university standards
  lab to  measure the T-Bolt frequency? And how did  they  measure its
  frequency?

 >  How did  they do the comparison to your TBolt? If it was  a counter,
  what kind was it?

 > You mentioned the error was better than 1e-12 90% of the  time. What
  was the average error?
------------------------------


Hi, Bruce, Mike, et al--

Your points are all well taken! However, all I wanted to
know (and all I asked the standards lab) was: How much
"ballpark" error will I have when using my T-bolt as a
reference to confirm the frequency of my 10GHz ham transmitter?
Yes, from a Time-Nuts perspective, my question is crude and
unsophisticated, but I simply did not have any interest in
knowing anything about the T-bolt except how good it is when
used as a reference for checking the frequency output of my
10GHz transmitter.  I really did not care about ADEV, MDEV,
XYZDEV or any other alphabet soup criteria, and yes, I know
that this confirms that I am a primitive knuckle-dragging
troglodyte with respect to the subtle nuances of time and
frequency standards...

It's kinda like looking at the speedometer on my pickup truck
as I drive down the Interstate highway....:  My only interest
is that it be accurate enough to use for my particular
application.  Same goes for my T-bolt...  Can I trust it
to get me within 10Hz at 10GHz?    +/- 100Hz?    +/- 1KHz?

As for what the lab used to make the measurements, all I can
say is that the lab has several time/frequency references,
one I saw was about the size of a refrigerator called a
CH1-75 Active Hydrogen Maser.  Big-- looked expensive,
blinking lights, pretty colors... impressed me.

I'll go back to my cave, now...

Cheers!!

Mike Baker
WA4HFR
Gainesville, Florida, USA



From stijena at tapko.de  Sun Dec 21 14:23:13 2008
From: stijena at tapko.de (Predrag Dukic)
Date: Sun, 21 Dec 2008 15:23:13 +0100
Subject: [time-nuts] How good is my T-bolt...??
In-Reply-To: <494E4E24.1040100@clanbaker.org>
References: <494E4E24.1040100@clanbaker.org>
Message-ID: <7.0.1.0.1.20081221151908.01e43ac0@tapko.de>



Mike,

Thunderbolt is going to bring You from NY to SF  at exactly 55MPH 
AVERAGE,  down to the fraction of the INPH, and still there is a 
possibility that You earn a speeding ticket or two (or more) on the way.

Predrag Dukic   (also not an expert,  but things are not that simple 
as Your question)




At 15:09 21.12.2008, you wrote:
>Hello, Time-Nutters--
>
>Bruce said:
>
>  > A statement of accuracy is of little value unless you also give:
>  > 1) An estimate of the accuracy of standard used for comparison.
>  > 2) An estimate of the random and systematic errors in the comparison
>  > 3) Some details of the comparison method.
>  > 4) Averaging time and other pertinent info.
>------------------------------
>
>Mike asked:
>
>  > What frequency  reference did they use at  the  university standards
>   lab to  measure the T-Bolt frequency? And how did  they  measure its
>   frequency?
>
>  >  How did  they do the comparison to your TBolt? If it was  a counter,
>   what kind was it?
>
>  > You mentioned the error was better than 1e-12 90% of the  time. What
>   was the average error?
>------------------------------
>
>
>Hi, Bruce, Mike, et al--
>
>Your points are all well taken! However, all I wanted to
>know (and all I asked the standards lab) was: How much
>"ballpark" error will I have when using my T-bolt as a
>reference to confirm the frequency of my 10GHz ham transmitter?
>Yes, from a Time-Nuts perspective, my question is crude and
>unsophisticated, but I simply did not have any interest in
>knowing anything about the T-bolt except how good it is when
>used as a reference for checking the frequency output of my
>10GHz transmitter.  I really did not care about ADEV, MDEV,
>XYZDEV or any other alphabet soup criteria, and yes, I know
>that this confirms that I am a primitive knuckle-dragging
>troglodyte with respect to the subtle nuances of time and
>frequency standards...
>
>It's kinda like looking at the speedometer on my pickup truck
>as I drive down the Interstate highway....:  My only interest
>is that it be accurate enough to use for my particular
>application.  Same goes for my T-bolt...  Can I trust it
>to get me within 10Hz at 10GHz?    +/- 100Hz?    +/- 1KHz?
>
>As for what the lab used to make the measurements, all I can
>say is that the lab has several time/frequency references,
>one I saw was about the size of a refrigerator called a
>CH1-75 Active Hydrogen Maser.  Big-- looked expensive,
>blinking lights, pretty colors... impressed me.
>
>I'll go back to my cave, now...
>
>Cheers!!
>
>Mike Baker
>WA4HFR
>Gainesville, Florida, USA
>
>
>_______________________________________________
>time-nuts mailing list -- time-nuts at febo.com
>To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>and follow the instructions there.



From mmoss at mindspring.com  Sun Dec 21 15:57:39 2008
From: mmoss at mindspring.com (Marvin Moss)
Date: Sun, 21 Dec 2008 10:57:39 -0500
Subject: [time-nuts] Systron Donner 6152A Freq Counter manual?
Message-ID: <380-2200812021155739289@mindspring.com>

Is there a close counter to the 6152A that I might be able to use to fix my 6152A?
I have been unable to locate a manual for the 6152A and perhaps could use another manual for another counter as being somewhat close to the 6152A.
My problem is either in the power supply or the gate circuit as it runs all the time with no (or grounded) input.
It would be a lot easier to find the problem with a manual :-)

Thanks,
Marvin

From belanning at verizon.net  Sun Dec 21 16:33:06 2008
From: belanning at verizon.net (Bruce Lanning)
Date: Sun, 21 Dec 2008 11:33:06 -0500
Subject: [time-nuts] Systron Donner 6152A Freq Counter manual?
References: <380-2200812021155739289@mindspring.com>
Message-ID: <25BBFBCBD28D4F039CA189F85B6695A2@yoursz6x6sefxo>

I Marvin,
I have a 6152A and the Manual. Also, I have a spare 6152A in the attic that 
is missing the Power Transformer. If I can be of help, let me know.
Bruce W1GBS

----- Original Message ----- 
From: "Marvin Moss" <mmoss at mindspring.com>
To: <time-nuts at febo.com>
Sent: Sunday, December 21, 2008 10:57 AM
Subject: [time-nuts] Systron Donner 6152A Freq Counter manual?


> Is there a close counter to the 6152A that I might be able to use to fix 
> my 6152A?
> I have been unable to locate a manual for the 6152A and perhaps could use 
> another manual for another counter as being somewhat close to the 6152A.
> My problem is either in the power supply or the gate circuit as it runs 
> all the time with no (or grounded) input.
> It would be a lot easier to find the problem with a manual :-)
>
> Thanks,
> Marvin
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to 
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.


--------------------------------------------------------------------------------



Internal Virus Database is out of date.
Checked by AVG - http://www.avg.com
Version: 8.0.176 / Virus Database: 270.9.17/1847 - Release Date: 12/13/2008 
4:56 PM



From etroy at aeroconsult.com  Sun Dec 21 17:10:33 2008
From: etroy at aeroconsult.com (Ed Troy)
Date: Sun, 21 Dec 2008 12:10:33 -0500
Subject: [time-nuts]  Looking for recommendation GPS time/freq standard
Message-ID: <200812211710.mBLHAGiI025532@host2.secureserver15.com>

I am looking to buy a high quality GPSDO for my lab, so that I can 
run all of my test equipment off a single, high quality, low phase 
noise oscillator. While time accuracy is important, phase noise is 
the most important. I suspect my best phase noise instrument is my 
HP8563E, with which I measure phase noise of various oscillators, but 
I suspect the phase noise of some of the GPSDO's is better. The ones 
I am considering are the following:
Z3801A
Z3816A
Z3805A Symmetricom
Trimble Z3801A
Thunderbolt

Any suggestions or warnings would be appreciated.



From magnus at rubidium.dyndns.org  Sun Dec 21 17:21:07 2008
From: magnus at rubidium.dyndns.org (Magnus Danielson)
Date: Sun, 21 Dec 2008 18:21:07 +0100
Subject: [time-nuts] Thunderbolt Accuracy needs...
In-Reply-To: <80978102-0B27-4F46-9506-594F257FF755@cox.net>
References: <mailman.582.1229813238.2499.time-nuts@febo.com>	<7.0.0.16.2.20081220145925.03835148@att.net>
	<80978102-0B27-4F46-9506-594F257FF755@cox.net>
Message-ID: <494E7B03.7000502@rubidium.dyndns.org>

Thomas A. Frank skrev:
> On Dec 20, 2008, at 6:03 PM, Burt I. Weiner wrote:
> 
>> I suppose a good comparison would be: How accurate does the
>> speedometer in the car really need to be and why.
> 
> Accurate enough so that if its reading matches the posted sign, you  
> don't receive a ticket?

An engineer pointed out that due to the spreading of readings on various 
speedometers un-necessary take-overs where performed by those having a 
higher speed for the same reading than those having a lower speed for 
the same reading. Thus, the precaution is to some degree compromised by 
the lack of consistency in the degraded reading. This is further 
compromised by people knowing their speedometers is degraded, so they 
form their own rules of how to interprent them in a favorable fashion.
The tires and air pressure in them comes in as things compromising the 
scale. My speedometer gives different readings on my summer-tires than 
my winter tires.

I think I actually prefer more exact speedometer in all cars. Then there 
is less room for subjective judgements and less of a discussion altogether.

I think we already did some work in a similar fields like weigth, 
lengths and time...

I learned alot of what my speedometer told me when looking at my TomTom 
reading.

Cheers,
Magnus


From kyrrin at bluefeathertech.com  Sun Dec 21 17:24:21 2008
From: kyrrin at bluefeathertech.com (Bruce Lane)
Date: Sun, 21 Dec 2008 09:24:21 -0800
Subject: [time-nuts] Looking for recommendation GPS time/freq  standard
In-Reply-To: <200812211710.mBLHAGiI025532@host2.secureserver15.com>
References: <200812211710.mBLHAGiI025532@host2.secureserver15.com>
Message-ID: <200812210924210516.282FA842@192.168.42.129>

	FWIW - The Z3801 and 3816 are nearly identical.

	Personally, I've been very pleased with my Z3801. It has been a real workhorse, serving reliably for the last 5-6 years without a hitch. I use it as an external reference for my service monitor (IFR/Aeroflex 1600A/S), and I've yet to see a 'bad' measurement as a result.

	I can't speak to phase noise from the thing, since I've never bothered to measure it, but consider where the Z-series was used: Cellphone sites. This means that any phase noise would likely become a nasty problem in terms of signal quality at the cellphone end, and that HP would likely have gone to great lengths to minimize it.

	Happy tweaking.

*********** REPLY SEPARATOR  ***********

On 21-Dec-08 at 12:10 Ed Troy wrote:

>I am looking to buy a high quality GPSDO for my lab, so that I can 
>run all of my test equipment off a single, high quality, low phase 
>noise oscillator. While time accuracy is important, phase noise is 
>the most important. I suspect my best phase noise instrument is my 
>HP8563E, with which I measure phase noise of various oscillators, but 
>I suspect the phase noise of some of the GPSDO's is better. The ones 
>I am considering are the following:
>Z3801A
>Z3816A
>Z3805A Symmetricom
>Trimble Z3801A
>Thunderbolt
>
>Any suggestions or warnings would be appreciated.
>
>
>_______________________________________________
>time-nuts mailing list -- time-nuts at febo.com
>To unsubscribe, go to
>https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>and follow the instructions there.


-=-=-=-=-=-=-=-=-=-=-=-
Bruce Lane, Owner & Head Hardware Heavy,
Blue Feather Technologies -- http://www.bluefeathertech.com
kyrrin (at) bluefeathertech do/t c=o=m
"Quid Malmborg in Plano..."



From rdarlington at gmail.com  Sun Dec 21 17:34:49 2008
From: rdarlington at gmail.com (Robert Darlington)
Date: Sun, 21 Dec 2008 10:34:49 -0700
Subject: [time-nuts] Thunderbolt Accuracy needs...
In-Reply-To: <494E7B03.7000502@rubidium.dyndns.org>
References: <mailman.582.1229813238.2499.time-nuts@febo.com>
	<7.0.0.16.2.20081220145925.03835148@att.net>
	<80978102-0B27-4F46-9506-594F257FF755@cox.net>
	<494E7B03.7000502@rubidium.dyndns.org>
Message-ID: <b3bd5fcb0812210934l1864eae2kc6df9a3f6ca14c27@mail.gmail.com>

And faster speedometers make your warranty run out faster, which nobody
except the car companies like.

On Sun, Dec 21, 2008 at 10:21 AM, Magnus Danielson <
magnus at rubidium.dyndns.org> wrote:

> Thomas A. Frank skrev:
> > On Dec 20, 2008, at 6:03 PM, Burt I. Weiner wrote:
> >
> >> I suppose a good comparison would be: How accurate does the
> >> speedometer in the car really need to be and why.
> >
> > Accurate enough so that if its reading matches the posted sign, you
> > don't receive a ticket?
>
> An engineer pointed out that due to the spreading of readings on various
> speedometers un-necessary take-overs where performed by those having a
> higher speed for the same reading than those having a lower speed for
> the same reading. Thus, the precaution is to some degree compromised by
> the lack of consistency in the degraded reading. This is further
> compromised by people knowing their speedometers is degraded, so they
> form their own rules of how to interprent them in a favorable fashion.
> The tires and air pressure in them comes in as things compromising the
> scale. My speedometer gives different readings on my summer-tires than
> my winter tires.
>
> I think I actually prefer more exact speedometer in all cars. Then there
> is less room for subjective judgements and less of a discussion altogether.
>
> I think we already did some work in a similar fields like weigth,
> lengths and time...
>
> I learned alot of what my speedometer told me when looking at my TomTom
> reading.
>
> Cheers,
> Magnus
>
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>

From XDE-L2G3 at myamail.com  Sun Dec 21 18:02:07 2008
From: XDE-L2G3 at myamail.com (Mike Monett)
Date: Sun, 21 Dec 2008 13:02:07 -0500
Subject: [time-nuts] How good is my T-bolt...??
References: <mailman.590.1229880891.2499.time-nuts@febo.com>
Message-ID: <mailman.6.1229882540.2496.time-nuts@febo.com>


  > Hello, Time-Nutters

  [...]

  > Hi, Bruce, Mike, et al

  > Your points are all well taken! However, all I wanted to know (and
  > all I asked the standards lab) was: How much "ballpark" error will
  > I have  when  using  my  T-bolt  as  a  reference  to  confirm the
  > frequency of  my  10GHz  ham transmitter?  Yes,  from  a Time-Nuts
  > perspective, my  question  is  crude  and  unsophisticated,  but I
  > simply did  not  have any interest in knowing  anything  about the
  > T-bolt except how good it is when used as a reference for checking
  > the frequency  output  of my 10GHz transmitter. I  really  did not
  > care about ADEV, MDEV, XYZDEV or any other alphabet soup criteria,
  > and yes,  I  know  that  this   confirms  that  I  am  a primitive
  > knuckle-dragging troglodyte with respect to the subtle  nuances of
  > time and frequency standards.

  > It's kinda like looking at the speedometer on my pickup truck as I
  > drive down  the Interstate highway. : My only interest is  that it
  > be accurate enough to use for my particular application. Same goes
  > for my T-bolt. Can I trust it to get me within 10Hz at  10GHz? +/-
  > 100Hz? +/- 1KHz?

  > As for  what the lab used to make the measurements, all I  can say
  > is that  the lab has several time/frequency references, one  I saw
  > was about  the  size  of a  refrigerator  called  a  CH1-75 Active
  > Hydrogen Maser.  Big - looked expensive,  blinking  lights, pretty
  > colors. Impressed me.

  > I'll go back to my cave, now.

  > Cheers!!

  > Mike Baker
  > WA4HFR
  > Gainesville, Florida, USA

  Hi Mike,

  It is refreshing to see such sweet innocence. For most of  us, those
  days are gone forever.

  Your problem is you only have one clock. As soon as you get two, you
  ask a very simple question: which one is right?

  But that only makes things worse.

  That question  leads you over the edge and down  the  slippery slope
  that brings  most  of us to this forum. The same  thing  happened to
  Tom, and look at how many clocks he has now.

  Right now,  you don't have enough clocks. The only real  solution to
  your problem, is to get another TBolt:)

  Regards,

  Mike Monett


From joegwinn at comcast.net  Sun Dec 21 18:46:05 2008
From: joegwinn at comcast.net (Joe Gwinn)
Date: Sun, 21 Dec 2008 13:46:05 -0500
Subject: [time-nuts] Sub Pico Second Phase logger
Message-ID: <p06240800c5743311b2a3@[192.168.1.212]>

Bruce,

At 9:50 PM +0000 12/19/08, time-nuts-request at febo.com wrote:
>
>Message: 7
>Date: Sat, 20 Dec 2008 10:38:26 +1300
>From: Bruce Griffiths <bruce.griffiths at xtra.co.nz>
>Subject: Re: [time-nuts] Sub Pico Second Phase logger
>To: Discussion of precise time and frequency measurement
>	<time-nuts at febo.com>
>
>Joe
>
>Joe Gwinn wrote:
>>  Bruce,
>>
>>  At 3:54 AM +0000 12/19/08, time-nuts-request at febo.com wrote:
>>  
>>>  Message: 5
>>>  Date: Fri, 19 Dec 2008 16:51:55 +1300
>>>  From: Bruce Griffiths <bruce.griffiths at xtra.co.nz>
>>>  Subject: Re: [time-nuts] Sub Pico Second Phase logger
>>>  To: Discussion of precise time and frequency measurement
>>>	<time-nuts at febo.com>
>>>
>>>  Joe
>>>
>>>  Joe Gwinn wrote:
>>>    
>>>>   At 11:48 PM +0000 12/18/08, time-nuts-request at febo.com wrote:
>  >>>
>[snip]
>
>>  
>>>  Some claim to be able to sync to an SPDIF input but the resultant jitter
>>>  may be large.
>>>    
>>
>>  Why large jitter?  Bad implementation?
>>
>>
>>  
>I'm just suspicious, although I did see some data somewhere that seemed
>to confirm my suspicions.
>The S/PDIF signal has to be a valid SPDIF signal not just a square or
>sine wave clock.
>Output sample rates (for the AP192) are then identical to that of the
>the S/PDIF source which is limited to
>192, 176.4, 96,88.2 48, 44.1 32 KSPS.

I did a little looking.  I bet that the sync quite well, but this 
signal is pretty complex.  One assumes that there is a box that takes 
in a 10 MHz ref and does the rest, because the broadcast industry 
does use atomic clocks.


>  >
>  >>  >>  >> A few divide and mix stages will be required to achieve 
>a spur free resolution of 10Hz.
>  >>>>>>            
>>>>>>    That is a traditional approach.  But are there alternate 
>>>>>>approaches that
>  >>>>>   have now become practical?
>  >>>>>
>  >>>>  Diophantine frequency synthesis?
>  >>>>        
>>>>    From the sound of the name I think so, at least in the last DDS
>>>>   stage, as done by that patent.
>>>>
>  >>>  But I was fishing.
>  >>>      
>>>  Conventional Diophantine synthesis uses number theory together with 2 or
>>>  3 conventional synthesiser loops to achieve very fine resolution whilst
>  >> maintaining a high PLL phase detector input frequency.
>  >
>>  In a sense, the concatenated DDS approach is a divide-and-mix chain.
>  > Perhaps there is a parallel here.
>  >  
>The DDS based equivalent (of the dual PLL Diophantine synthesiser) would
>use a pair of DDS chips each replacing a conventional PLL in the
>Diophantine frequency synthesiser, the output frequency of each having
>zero phase truncation spurs.
>
>Both DDS clock sources should be spur free and have a frequency ratio
>that is a selected fixed rational fraction.

A M/N PLL chip can arrange this.  I recall that Silicon Labs makes 
such a chip, which requires a parameter load on power-up, so a 
computer or FPGA is needed.


>A conventional mixer would then be used to either add or subtract the
>two DDS output frequencies.
>If the ratio of the 2 DDS clock source frequencies is appropriately
>chosen the spacing between the resultant mixer output frequencies can be
>much finer than the spacing between the truncation spur free outputs of
>either DDS chip.
>The DDS and mixer outputs should be filtered to remove harmonics and
>other unwanted frequencies.

If the DDS chips are well chosen, we will get sin and cos outputs, 
and so can implement a dual-mixer phasing scheme to yield only the 
sum frequency or only the difference frequency, greatly reducing the 
amount of filtering needed.  The better balanced the channels are the 
better the cancellation of the unwanted term.  This is basically the 
phasing method of single-sideband signal generation.


>One drawback is that selecting the output frequencies of the 2 DDS chips
>required to produce the desired output frequency is somewhat complex.
>Since one almost certainly needs a computer of some sort to set the DDS
>frequencies this shouldn't be a significant issue.

Yes.  Basically, every digital chip in this scheme requires a 
computer of some kind.  What I've seen used is a small CPLD to do the 
initial parameter loads, and then to run the show.

Joe


From joegwinn at comcast.net  Sun Dec 21 19:02:24 2008
From: joegwinn at comcast.net (Joe Gwinn)
Date: Sun, 21 Dec 2008 14:02:24 -0500
Subject: [time-nuts] Sub Pico Second Phase logger
Message-ID: <p06240802c5743fb0a7e9@[192.168.1.212]>

Bruce,

At 9:50 PM +0000 12/19/08, time-nuts-request at febo.com wrote:
>
>Message: 8
>Date: Sat, 20 Dec 2008 10:50:46 +1300
>From: Bruce Griffiths <bruce.griffiths at xtra.co.nz>
>Subject: Re: [time-nuts] Sub Pico Second Phase logger
>To: Discussion of precise time and frequency measurement
>	<time-nuts at febo.com>
>
>Joe
>
>Joe Gwinn wrote:
>>  Bruce,
>>
>>  At 3:54 AM +0000 12/19/08, time-nuts-request at febo.com wrote:
>>  
>>>  Message: 6
>>>  Date: Fri, 19 Dec 2008 16:54:12 +1300
>>>  From: Bruce Griffiths <bruce.griffiths at xtra.co.nz>
>>>  Subject: Re: [time-nuts] Sub Pico Second Phase logger
>>>  To: Discussion of precise time and frequency measurement
>  >>	<time-nuts at febo.com>
>>>
>[snip]
>  >> I'll breadboard an oscillator over the holidays and take some samples.
>>>    
>>
>>  A rainy-day activity for sure.   In the Boston area, the issue is
>>  snow - a noreaster is just now starting, with a foot of snow expected.
>>
>>  Joe
>>
>>  
>AFAIK it has never snowed here.

So it instead rains heavily?


>It does snow on the central NI Plateau but not usually in December.

Well, I've just dug out of 1.5 feet of snow already, and it continues 
to snow.  The threat is that later we will get rain, and then it will 
all freeze into solid ice.  This in the Boston area.


>I'll start with a diode limited (soft clamps - resistance in series with
>diodes) oscillator and move to a lower distortion one if necessary.

What distortion level do we need?  Given that the parts cost nothing, 
I'd be tempted into some overkill.

Joe


From richiem at hughes.net  Sun Dec 21 19:51:11 2008
From: richiem at hughes.net (Richard Moore)
Date: Sun, 21 Dec 2008 11:51:11 -0800
Subject: [time-nuts] Speedometers -- bah, humbug
In-Reply-To: <mailman.590.1229880891.2499.time-nuts@febo.com>
References: <mailman.590.1229880891.2499.time-nuts@febo.com>
Message-ID: <9647ECAA-5CEA-4F44-9495-67436E36C797@hughes.net>

Shortly after I bought my '97 VW Eurovan Camper in late '97, I  
noticed that it was reading higher than I was going as timed by  
stopwatch and mile markers. I kept measuring from time to time to  
sort of average things out. I finally complained to the dealer that  
it was about 5% high. After a lot of incidental discussion about tire  
sizes, air pressure, etc. they called VWoA. The answer? The Feds then  
required the speedometer to read not less than 2% nor more than 8%  
high -- oddly enough, 5% is the mean of this variance. I don't know  
what's required now. My '02 Toyota Highlander reads a tad less than  
1% high, based on readings from my Garmin eTrex.

Dick Moore

On Dec 21, 2008, at 9:34 AM, time-nuts-request at febo.com wrote:

> Message: 3
> Date: Sun, 21 Dec 2008 15:23:13 +0100
> From: Predrag Dukic <stijena at tapko.de>
> Subject: Re: [time-nuts] How good is my T-bolt...??
> To: Discussion of precise time and frequency measurement
> 	<time-nuts at febo.com>
> Message-ID: <7.0.1.0.1.20081221151908.01e43ac0 at tapko.de>
> Content-Type: text/plain; charset="us-ascii"; format=flowed
>
> Mike,
> Thunderbolt is going to bring You from NY to SF  at exactly 55MPH
> AVERAGE,  down to the fraction of the INPH, and still there is a
> possibility that You earn a speeding ticket or two (or more) on the  
> way.
>
> Predrag Dukic   (also not an expert,  but things are not that simple
> as Your question)
>
>
> ------------------------------
>
> Message: 9
> Date: Sun, 21 Dec 2008 10:34:49 -0700
> From: "Robert Darlington" <rdarlington at gmail.com>
> Subject: Re: [time-nuts] Thunderbolt Accuracy needs...
> To: "Discussion of precise time and frequency measurement"
> 	<time-nuts at febo.com>
> Message-ID:
> 	<b3bd5fcb0812210934l1864eae2kc6df9a3f6ca14c27 at mail.gmail.com>
> Content-Type: text/plain; charset=ISO-8859-1
>
> And faster speedometers make your warranty run out faster, which  
> nobody
> except the car companies like.
>
> On Sun, Dec 21, 2008 at 10:21 AM, Magnus Danielson <
> magnus at rubidium.dyndns.org> wrote:
>
>> Thomas A. Frank skrev:
>>> On Dec 20, 2008, at 6:03 PM, Burt I. Weiner wrote:
>>>
>>>> I suppose a good comparison would be: How accurate does the
>>>> speedometer in the car really need to be and why.
>>>
>>> Accurate enough so that if its reading matches the posted sign, you
>>> don't receive a ticket?
>>
>> An engineer pointed out that due to the spreading of readings on  
>> various
>> speedometers un-necessary take-overs where performed by those  
>> having a
>> higher speed for the same reading than those having a lower speed for
>> the same reading. Thus, the precaution is to some degree  
>> compromised by
>> the lack of consistency in the degraded reading. This is further
>> compromised by people knowing their speedometers is degraded, so they
>> form their own rules of how to interprent them in a favorable  
>> fashion.
>> The tires and air pressure in them comes in as things compromising  
>> the
>> scale. My speedometer gives different readings on my summer-tires  
>> than
>> my winter tires.
>>
>> I think I actually prefer more exact speedometer in all cars. Then  
>> there
>> is less room for subjective judgements and less of a discussion  
>> altogether.
>>
>> I think we already did some work in a similar fields like weigth,
>> lengths and time...
>>
>> I learned alot of what my speedometer told me when looking at my  
>> TomTom
>> reading.
>>
>> Cheers,
>> Magnus


From bill at iaxs.net  Sun Dec 21 21:11:00 2008
From: bill at iaxs.net (Bill Hawkins)
Date: Sun, 21 Dec 2008 15:11:00 -0600
Subject: [time-nuts] Solstice question, about 5000 years ago
In-Reply-To: <9647ECAA-5CEA-4F44-9495-67436E36C797@hughes.net>
References: <mailman.590.1229880891.2499.time-nuts@febo.com>
	<9647ECAA-5CEA-4F44-9495-67436E36C797@hughes.net>
Message-ID: <D00317DCB61E485F9398BC7D57D6D124@cyrus>

The passage grave at New Grange, Ireland, is one of those astronomical
wonders where the rising sun at winter solstice shines down a relatively
long tunnel to shine on carved stone at the far wall of a chamber.

We know that solstice has the shortest day and the longest night.

How'd they know that?

Bill Hawkins



From msokolov at ivan.Harhan.ORG  Sun Dec 21 21:25:44 2008
From: msokolov at ivan.Harhan.ORG (Michael Sokolov)
Date: Sun, 21 Dec 2008 21:25:44 GMT
Subject: [time-nuts] Solstice question, about 5000 years ago
Message-ID: <0812212125.AA02184@ivan.Harhan.ORG>

Bill Hawkins <bill at iaxs.net> wrote:

> The passage grave at New Grange, Ireland, is one of those astronomical
> wonders where the rising sun at winter solstice shines down a relatively
> long tunnel to shine on carved stone at the far wall of a chamber.
>
> We know that solstice has the shortest day and the longest night.
>
> How'd they know that?

I'll abstain from answering the last question, but I'm more interested
in a different question: from what I understand, the exact shape of the
analemma depends on the misalignment between the line of apses (aphelion
and perihelion of Earth's slightly eccentric orbit) and the solstices
and equinoxes defined by Earth's obliquity.  These things do change very
slowly over the course of millennia, don't they?  Isn't that change
significant enough that the correct stone alignment would be different
between today and 5000 y ago?  If they got it right 5000 y ago for their
epoch, why does it still work now?  Hasn't the analemma shifted far
enough to break the alignment?

Just wondering.

MS


From namichie at gmail.com  Sun Dec 21 21:57:10 2008
From: namichie at gmail.com (Neville Michie)
Date: Mon, 22 Dec 2008 08:57:10 +1100
Subject: [time-nuts] Solstice question, about 5000 years ago
In-Reply-To: <0812212125.AA02184@ivan.Harhan.ORG>
References: <0812212125.AA02184@ivan.Harhan.ORG>
Message-ID: <D4EDAFC1-41BB-4235-B79A-2B877C19FC41@gmail.com>

The astronomers of 5000 years ago were amateurs, so of course they
made their own gear and found out what worked.
Now if you find a notch in a rock on a distant mountain and the  
shadow it casts every day at sunrise,
you only have to place a chalk mark on the wall each day to discover  
that the position change each day slows down
then reverses at the solstice.
Now you have a way to find the solstice, so you chip your chalk marks  
into the wall.
They show ten days to the solstice and the countdown to the day.
You have been making a good living telling people when the solstice  
is going to occur,
so you drag up some big rocks to sit in the right place to see the  
sunrise shadow as it approaches the solstice
so your son can inherit the business and make a good living when you  
shuffle off.
Your son runs the company of wise guru pty ltd, and he suggests that  
the really cool way to make
the next monument would be to have it point to the rising sun on the  
solstice.
He knows when it gets to the solstice so he sets up a few sticks to  
get the line to set the
stones to when they build the monument.
Ever since that new bits of information have been found, and when  
Kepler and Newton
had thrown their discoveries in we called it modern times. Then  
Einstein came along and we have time nuts.
cheers, Merry solstice,  Neville Michie

On 21/12/2008, at 9:25 PM, Michael Sokolov wrote:

> Bill Hawkins <bill at iaxs.net> wrote:
>
>> The passage grave at New Grange, Ireland, is one of those  
>> astronomical
>> wonders where the rising sun at winter solstice shines down a  
>> relatively
>> long tunnel to shine on carved stone at the far wall of a chamber.
>>
>> We know that solstice has the shortest day and the longest night.
>>
>> How'd they know that?
>
> I'll abstain from answering the last question, but I'm more interested
> in a different question: from what I understand, the exact shape of  
> the
> analemma depends on the misalignment between the line of apses  
> (aphelion
> and perihelion of Earth's slightly eccentric orbit) and the solstices
> and equinoxes defined by Earth's obliquity.  These things do change  
> very
> slowly over the course of millennia, don't they?  Isn't that change
> significant enough that the correct stone alignment would be different
> between today and 5000 y ago?  If they got it right 5000 y ago for  
> their
> epoch, why does it still work now?  Hasn't the analemma shifted far
> enough to break the alignment?
>
> Just wondering.
>
> MS
>
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/ 
> time-nuts
> and follow the instructions there.



From bruce.griffiths at xtra.co.nz  Sun Dec 21 22:08:30 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Mon, 22 Dec 2008 11:08:30 +1300
Subject: [time-nuts] Sub Pico Second Phase logger
In-Reply-To: <p06240802c5743fb0a7e9@[192.168.1.212]>
References: <p06240802c5743fb0a7e9@[192.168.1.212]>
Message-ID: <494EBE5E.2050905@xtra.co.nz>

Joe

Joe Gwinn wrote:
> Bruce,
>
> At 9:50 PM +0000 12/19/08, time-nuts-request at febo.com wrote:
>   
>> Message: 8
>> Date: Sat, 20 Dec 2008 10:50:46 +1300
>> From: Bruce Griffiths <bruce.griffiths at xtra.co.nz>
>> Subject: Re: [time-nuts] Sub Pico Second Phase logger
>> To: Discussion of precise time and frequency measurement
>> 	<time-nuts at febo.com>
>>
>> Joe
>>
>> Joe Gwinn wrote:
>>     
>>>  Bruce,
>>>
>>>  At 3:54 AM +0000 12/19/08, time-nuts-request at febo.com wrote:
>>>  
>>>       
>>>>  Message: 6
>>>>  Date: Fri, 19 Dec 2008 16:54:12 +1300
>>>>  From: Bruce Griffiths <bruce.griffiths at xtra.co.nz>
>>>>  Subject: Re: [time-nuts] Sub Pico Second Phase logger
>>>>  To: Discussion of precise time and frequency measurement
>>>>         
>>  >>	<time-nuts at febo.com>
>>     
>> [snip]
>>  >> I'll breadboard an oscillator over the holidays and take some samples.
>>     
>>>>    
>>>>         
>>>  A rainy-day activity for sure.   In the Boston area, the issue is
>>>  snow - a noreaster is just now starting, with a foot of snow expected.
>>>
>>>  Joe
>>>
>>>  
>>>       
>> AFAIK it has never snowed here.
>>     
>
> So it instead rains heavily?
>
>
>   
Yes, it does rain heavily from time to time but nothing like a monsoon.
>> It does snow on the central NI Plateau but not usually in December.
>>     
>
> Well, I've just dug out of 1.5 feet of snow already, and it continues 
> to snow.  The threat is that later we will get rain, and then it will 
> all freeze into solid ice.  This in the Boston area.
>
>
>   
>> I'll start with a diode limited (soft clamps - resistance in series with
>> diodes) oscillator and move to a lower distortion one if necessary.
>>     
>
> What distortion level do we need?  Given that the parts cost nothing, 
> I'd be tempted into some overkill.
>   
At some stage we need to emulate the distortion level that is likely
from the mixer output which could be as high as a few percent depending
on the RF input level.
Saturating the Mixer RF port as is usually recommended will increase the
distortion.

May build a quadrature oscillator as this then allows testing with the 2
sound card channels either driven in quadrature or in phase.
Can either use diode soft clamping or a photoresistor based AGC to
control the output level.
> Joe
>
>   
Bruce


From alan.melia at btinternet.com  Sun Dec 21 22:12:15 2008
From: alan.melia at btinternet.com (Alan Melia)
Date: Sun, 21 Dec 2008 22:12:15 -0000
Subject: [time-nuts] Solstice question, about 5000 years ago
References: <mailman.590.1229880891.2499.time-nuts@febo.com><9647ECAA-5CEA-4F44-9495-67436E36C797@hughes.net>
	<D00317DCB61E485F9398BC7D57D6D124@cyrus>
Message-ID: <001101c963b9$30b15f40$0900a8c0@AM>

Hi Bill
About 100 millenia of accumulated experience with probably the last  2 or
three actually farming very successfully where you need to know about
seasons. The Celts were a very civilised people (but their history was
written by their conquorers!)  and great traders even in those days. Flints
were exported and later metals tin lead and copper, and even some gold. The
Romans didnt beat us up for nothing !! It had to be worth the effort. GB was
the granary of their western empire. Note Stonehenge dates from the same
period or even earlier and has 10 ton stones which can only be found 100
miles away on the Welsh mountains.....not just picked up near by! Mind you I
dont expect the drummed the local Druid out of the time-nuts if he got it
wrong by a day :-))

Alan G3NYK

----- Original Message -----
From: "Bill Hawkins" <bill at iaxs.net>
To: "'Discussion of precise time and frequency measurement'"
<time-nuts at febo.com>
Sent: Sunday, December 21, 2008 9:11 PM
Subject: [time-nuts] Solstice question, about 5000 years ago


> The passage grave at New Grange, Ireland, is one of those astronomical
> wonders where the rising sun at winter solstice shines down a relatively
> long tunnel to shine on carved stone at the far wall of a chamber.
>
> We know that solstice has the shortest day and the longest night.
>
> How'd they know that?
>
> Bill Hawkins
>
>
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.



From preynaert at yahoo.com  Sun Dec 21 22:13:00 2008
From: preynaert at yahoo.com (Patrick Reynaert)
Date: Sun, 21 Dec 2008 14:13:00 -0800 (PST)
Subject: [time-nuts] Jupiter modules: 1pps or 10kHz to lock an OCXO ?
Message-ID: <969255.43432.qm@web58802.mail.re1.yahoo.com>

Hello,


Using the 10kHz output to lock an OCXO is common practice and seems to give good results. 

Has anyone tried to use the 1pps output? One? could first make a simple divider to create a 0.5Hz reference with 50% duty cycle, and then use this signal to lock an OCXO. This would also allow the use of other OEM GPS modules that don't have the 10kHz but only the 1pps signal.

Of course, as the 0.5Hz signal is much lower in frequency than 10kHz, the short-term stability is pushed more to the OCXO, making the requirements of the OCXO even harder.

But maybe the 1pps signal has better stability than the 10kHz signal? Or is this the same since these signals will only influence the long-term stability of the oscillator and have the same accuracy?

Any thoughts are highly appreciated.

Thanks,
Patrick.




      

From dave.g0dja at tiscali.co.uk  Sun Dec 21 22:17:44 2008
From: dave.g0dja at tiscali.co.uk (Dave Ackrill)
Date: Sun, 21 Dec 2008 22:17:44 +0000
Subject: [time-nuts] Speedometers -- bah, humbug
In-Reply-To: <9647ECAA-5CEA-4F44-9495-67436E36C797@hughes.net>
References: <mailman.590.1229880891.2499.time-nuts@febo.com>
	<9647ECAA-5CEA-4F44-9495-67436E36C797@hughes.net>
Message-ID: <494EC088.8080901@tiscali.co.uk>

Richard Moore wrote:
>  The answer? The Feds then  
> required the speedometer to read not less than 2% nor more than 8%  
> high -- oddly enough, 5% is the mean of this variance. I don't know  
> what's required now. My '02 Toyota Highlander reads a tad less than  
> 1% high, based on readings from my Garmin eTrex.
>
>   
That's true this side of the herring pond as well...

So, if you are caught on camera, you cannot say your speedo was telling 
you that you were under the speed limit.

However, over here, you can still challenge the plods (UK term for 
Police Officers) to show that their measuring instruments were correctly 
callibrated on the day that they tracked you...

If they did not keep to the law on this, then you were not lawfully 
shown to be over the limit.

Dave (G0DJA)


From bruce.griffiths at xtra.co.nz  Sun Dec 21 22:19:06 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Mon, 22 Dec 2008 11:19:06 +1300
Subject: [time-nuts] Sub Pico Second Phase logger
In-Reply-To: <p06240800c5743311b2a3@[192.168.1.212]>
References: <p06240800c5743311b2a3@[192.168.1.212]>
Message-ID: <494EC0DA.2010601@xtra.co.nz>

Joe

Joe Gwinn wrote:
> Bruce,
>
> At 9:50 PM +0000 12/19/08, time-nuts-request at febo.com wrote:
>   
>> Message: 7
>> Date: Sat, 20 Dec 2008 10:38:26 +1300
>> From: Bruce Griffiths <bruce.griffiths at xtra.co.nz>
>> Subject: Re: [time-nuts] Sub Pico Second Phase logger
>> To: Discussion of precise time and frequency measurement
>> 	<time-nuts at febo.com>
>>
>> Joe
>>
>> Joe Gwinn wrote:
>>     
>>>  Bruce,
>>>
>>>  At 3:54 AM +0000 12/19/08, time-nuts-request at febo.com wrote:
>>>  
>>>       
>>>>  Message: 5
>>>>  Date: Fri, 19 Dec 2008 16:51:55 +1300
>>>>  From: Bruce Griffiths <bruce.griffiths at xtra.co.nz>
>>>>  Subject: Re: [time-nuts] Sub Pico Second Phase logger
>>>>  To: Discussion of precise time and frequency measurement
>>>> 	<time-nuts at febo.com>
>>>>
>>>>  Joe
>>>>
>>>>  Joe Gwinn wrote:
>>>>    
>>>>         
>>>>>   At 11:48 PM +0000 12/18/08, time-nuts-request at febo.com wrote:
>>>>>           
>>  >>>
>> [snip]
>>
>>     
>>>  
>>>       
>>>>  Some claim to be able to sync to an SPDIF input but the resultant jitter
>>>>  may be large.
>>>>    
>>>>         
>>>  Why large jitter?  Bad implementation?
>>>
>>>
>>>  
>>>       
>> I'm just suspicious, although I did see some data somewhere that seemed
>> to confirm my suspicions.
>> The S/PDIF signal has to be a valid SPDIF signal not just a square or
>> sine wave clock.
>> Output sample rates (for the AP192) are then identical to that of the
>> the S/PDIF source which is limited to
>> 192, 176.4, 96,88.2 48, 44.1 32 KSPS.
>>     
>
> I did a little looking.  I bet that the sync quite well, but this 
> signal is pretty complex.  One assumes that there is a box that takes 
> in a 10 MHz ref and does the rest, because the broadcast industry 
> does use atomic clocks.
>
>
>   
Ulrich has built a circuit that takes a sampling frequency input derived
from a 10MHz GPSDO output and produces an S/PDIF output for this
application.
Its certainly worth trying since all the specs for the sound card aren't
readily available.
>>  >
>>  >>  >>  >> A few divide and mix stages will be required to achieve 
>> a spur free resolution of 10Hz.
>>  >>>>>>            
>>     
>>>>>>>    That is a traditional approach.  But are there alternate 
>>>>>>> approaches that
>>>>>>>               
>>  >>>>>   have now become practical?
>>  >>>>>
>>  >>>>  Diophantine frequency synthesis?
>>  >>>>        
>>     
>>>>>    From the sound of the name I think so, at least in the last DDS
>>>>>   stage, as done by that patent.
>>>>>
>>>>>           
>>  >>>  But I was fishing.
>>  >>>      
>>     
>>>>  Conventional Diophantine synthesis uses number theory together with 2 or
>>>>  3 conventional synthesiser loops to achieve very fine resolution whilst
>>>>         
>>  >> maintaining a high PLL phase detector input frequency.
>>  >
>>     
>>>  In a sense, the concatenated DDS approach is a divide-and-mix chain.
>>>       
>>  > Perhaps there is a parallel here.
>>  >  
>> The DDS based equivalent (of the dual PLL Diophantine synthesiser) would
>> use a pair of DDS chips each replacing a conventional PLL in the
>> Diophantine frequency synthesiser, the output frequency of each having
>> zero phase truncation spurs.
>>
>> Both DDS clock sources should be spur free and have a frequency ratio
>> that is a selected fixed rational fraction.
>>     
>
> A M/N PLL chip can arrange this.  I recall that Silicon Labs makes 
> such a chip, which requires a parameter load on power-up, so a 
> computer or FPGA is needed.
>
>
>   
M and N only have to be relatively prime (ie the GCD of M and N is 1).
The ratio of M/N should also be close to 1.
If the spacing of the phase truncation spur free output frequencies is
about 10kHz (for either DDS) and M, N ~ 1000 the resultant mixer output
frequencies would have a spacing of about 10Hz which may be adequate for
this application.

>> A conventional mixer would then be used to either add or subtract the
>> two DDS output frequencies.
>> If the ratio of the 2 DDS clock source frequencies is appropriately
>> chosen the spacing between the resultant mixer output frequencies can be
>> much finer than the spacing between the truncation spur free outputs of
>> either DDS chip.
>> The DDS and mixer outputs should be filtered to remove harmonics and
>> other unwanted frequencies.
>>     
>
> If the DDS chips are well chosen, we will get sin and cos outputs, 
> and so can implement a dual-mixer phasing scheme to yield only the 
> sum frequency or only the difference frequency, greatly reducing the 
> amount of filtering needed.  The better balanced the channels are the 
> better the cancellation of the unwanted term.  This is basically the 
> phasing method of single-sideband signal generation.
>
>
>   
>> One drawback is that selecting the output frequencies of the 2 DDS chips
>> required to produce the desired output frequency is somewhat complex.
>> Since one almost certainly needs a computer of some sort to set the DDS
>> frequencies this shouldn't be a significant issue.
>>     
>
> Yes.  Basically, every digital chip in this scheme requires a 
> computer of some kind.  What I've seen used is a small CPLD to do the 
> initial parameter loads, and then to run the show.
>
> Joe
>
>   
Bruce


From james.p.lux at jpl.nasa.gov  Sun Dec 21 22:39:49 2008
From: james.p.lux at jpl.nasa.gov (Lux, James P)
Date: Sun, 21 Dec 2008 14:39:49 -0800
Subject: [time-nuts] Solstice question, about 5000 years ago
In-Reply-To: <D00317DCB61E485F9398BC7D57D6D124@cyrus>
Message-ID: <C57405B5.3ADC%James.P.Lux@jpl.nasa.gov>




On 12/21/08 1:11 PM, "Bill Hawkins" <bill at iaxs.net> wrote:

> The passage grave at New Grange, Ireland, is one of those astronomical
> wonders where the rising sun at winter solstice shines down a relatively
> long tunnel to shine on carved stone at the far wall of a chamber.
>
> We know that solstice has the shortest day and the longest night.
>
> How'd they know that?
>
> Bill

By observation?
One thing to remember is that things that are tough to do in 10 minutes
might be easy to do in 10 years, and astronomical alignments are one of
those.

There's a Anasazi site in New Mexico where on some particular day (solstice
or equinox.. I can't remember) a "dagger of light"  pierces a petroglyph.
Folks are always amazed at this until reminded that if you just wait long
enough, then do the petroglyphy afterwards, it's pretty straight forward to
get it in the right place.

To return to shortest days..

It's pretty easy to observe the rise and set points of the sun (assuming
it's clear.. Not guaranteed in Ireland in winter, I suspect) and to note
when it's most southern. Even if one thinks geocentrically, that would be
consistent with shortest day (suns path through sky being shortest),
especially if there's particular significance (like all days getting longer
afterwards, and returning from the days of mostly dark to the days of mostly
light).  One doesn't actually have to "measure time" to make the reasonable
assertion that southernmost rise and set, or lowest elevation meridian
crossing of sun, is shortest day.





From didier at cox.net  Mon Dec 22 00:02:40 2008
From: didier at cox.net (Didier)
Date: Sun, 21 Dec 2008 18:02:40 -0600
Subject: [time-nuts] Jupiter modules: 1pps or 10kHz to lock an OCXO ?
In-Reply-To: <969255.43432.qm@web58802.mail.re1.yahoo.com>
References: <969255.43432.qm@web58802.mail.re1.yahoo.com>
Message-ID: <0DCA237D2D474B518A530D44D6B44030@didierhp>

Patrick,

This has been covered extensively in recent past (this year). A quick look
through the archives will tell you more than you bargained for...

Didier 

> -----Original Message-----
> From: time-nuts-bounces at febo.com 
> [mailto:time-nuts-bounces at febo.com] On Behalf Of Patrick Reynaert
> Sent: Sunday, December 21, 2008 4:13 PM
> To: time-nuts
> Subject: [time-nuts] Jupiter modules: 1pps or 10kHz to lock an OCXO ?
> 
> Hello,
> 
> 
> Using the 10kHz output to lock an OCXO is common practice and 
> seems to give good results. 
> 
> Has anyone tried to use the 1pps output? One? could first 
> make a simple divider to create a 0.5Hz reference with 50% 
> duty cycle, and then use this signal to lock an OCXO. This 
> would also allow the use of other OEM GPS modules that don't 
> have the 10kHz but only the 1pps signal.
> 
> Of course, as the 0.5Hz signal is much lower in frequency 
> than 10kHz, the short-term stability is pushed more to the 
> OCXO, making the requirements of the OCXO even harder.
> 
> But maybe the 1pps signal has better stability than the 10kHz 
> signal? Or is this the same since these signals will only 
> influence the long-term stability of the oscillator and have 
> the same accuracy?
> 
> Any thoughts are highly appreciated.
> 
> Thanks,
> Patrick.
> 
> 
> 
> 
>       
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com To unsubscribe, 
> go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.



From quenbob5 at pacbell.net  Mon Dec 22 00:13:26 2008
From: quenbob5 at pacbell.net (Bob Q)
Date: Sun, 21 Dec 2008 16:13:26 -0800
Subject: [time-nuts] Jupiter modules: 1pps or 10kHz to lock an OCXO ?
References: <969255.43432.qm@web58802.mail.re1.yahoo.com>
Message-ID: <001501c963ca$1cae5320$1801a8c0@BOBCEL1R7>

Patrick,
I don't know of an analog approach using the 1 pps divided to 0.5 Hz (for 
50% duty cycle) as input to a phase detector.  1 Hz ripple frequency from 
the phase detector is probably not practical to filter.  You would need a 
low pass filter time constant of at least 1000 seconds and I think 
capacitors that will work for the long time constant will have poor 
temperature properties, leading to excess drift.  Digital approaches using 
the 1 pps signal compared to a divided OCXO signal are used by most modern 
designs.
Bob Q.
----- Original Message ----- 
From: "Patrick Reynaert" <preynaert at yahoo.com>
To: "time-nuts" <time-nuts at febo.com>
Sent: Sunday, December 21, 2008 2:13 PM
Subject: [time-nuts] Jupiter modules: 1pps or 10kHz to lock an OCXO ?


> Hello,
>
>
> Using the 10kHz output to lock an OCXO is common practice and seems to 
> give good results.
>
> Has anyone tried to use the 1pps output? One? could first make a simple 
> divider to create a 0.5Hz reference with 50% duty cycle, and then use this 
> signal to lock an OCXO. This would also allow the use of other OEM GPS 
> modules that don't have the 10kHz but only the 1pps signal.
>
> Of course, as the 0.5Hz signal is much lower in frequency than 10kHz, the 
> short-term stability is pushed more to the OCXO, making the requirements 
> of the OCXO even harder.
>
> But maybe the 1pps signal has better stability than the 10kHz signal? Or 
> is this the same since these signals will only influence the long-term 
> stability of the oscillator and have the same accuracy?
>
> Any thoughts are highly appreciated.
>
> Thanks,
> Patrick.
>
>
>
>
>
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to 
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there. 



From hmurray at megapathdsl.net  Mon Dec 22 02:01:08 2008
From: hmurray at megapathdsl.net (Hal Murray)
Date: Sun, 21 Dec 2008 18:01:08 -0800
Subject: [time-nuts] Jupiter modules: 1pps or 10kHz to lock an OCXO ?
In-Reply-To: Message from "Bob Q" <quenbob5@pacbell.net> of "Sun,
	21 Dec 2008 16:13:26 PST." <001501c963ca$1cae5320$1801a8c0@BOBCEL1R7> 
Message-ID: <20081222020109.D32D5BCD9@ip-64-139-1-69.sjc.megapath.net>


> I don't know of an analog approach using the 1 pps divided to 0.5 Hz
> (for  50% duty cycle) as input to a phase detector.  1 Hz ripple
> frequency from  the phase detector is probably not practical to
> filter.  You would need a low pass filter time constant of at least
> 1000 seconds and I think capacitors that will work for the long time
> constant will have poor temperature properties, leading to excess
> drift.

Has anybody considered putting that stuff into an oven?

I wonder if it would be practical to take apart the ovenized osc you are 
trying to control and put the cap inside at the right place in the existing 
circuit.





-- 
These are my opinions, not necessarily my employer's.  I hate spam.





From sar10538 at gmail.com  Mon Dec 22 02:27:26 2008
From: sar10538 at gmail.com (Steve Rooke)
Date: Mon, 22 Dec 2008 15:27:26 +1300
Subject: [time-nuts] How good is my T-bolt...??
In-Reply-To: <E1LESdA-0003wo-S1@meow.febo.com>
References: <mailman.590.1229880891.2499.time-nuts@febo.com>
	<E1LESdA-0003wo-S1@meow.febo.com>
Message-ID: <1231b6a80812211827g7f0d2b57i465372619dc27df@mail.gmail.com>

2008/12/22 Mike Monett <XDE-L2G3 at myamail.com>:
>
>  Right now,  you don't have enough clocks. The only real  solution to
>  your problem, is to get another TBolt:)

But which one of them is going to be right...

73, Steve - JAKDTNW  (just another knuckle dragging troglodyte time-nut wannabe)
-- 
Steve Rooke - ZL3TUV & G8KVD
Omnium finis imminet


From mpb45 at clanbaker.org  Mon Dec 22 02:28:49 2008
From: mpb45 at clanbaker.org (Michael Baker)
Date: Sun, 21 Dec 2008 21:28:49 -0500
Subject: [time-nuts] He is a Time-Nut Troublemaker....
Message-ID: <494EFB61.5000603@clanbaker.org>

Hello, TimeNutters--

Mike Monett said:

  It is refreshing to see such sweet innocence. For most of  us, those
  days are gone forever.

  Your problem is you only have one clock. As soon as you get two, you
  ask a very simple question: which one is right?

  But that only makes things worse.

  That question  leads you over the edge and down  the  slippery slope
  that brings  most  of us to this forum. The same  thing  happened to
  Tom, and look at how many clocks he has now.

  Right now,  you don't have enough clocks. The only real  solution to
  your problem, is to get another TBolt:)
--------------------------

Just ducked out of my cave to let you know that
you are a troublemaker.  Get another T-bolt... Right.
--Just what I need... another techno-addiction.  As far as
"sweet innocence" is concerned, I lost all I ever had
when I jumped head-first into bench-rest rifle competition
15 years ago.  You have your addiction-- I already have mine
in the never ending search to find the magic combination
of details that produce the holy-grail of a 10-shot half-inch
group at 400 yards...

For what it is worth, I am up to my kiester in the pursuit
of long-range bench-rest rifle accuracy.  I spend most of
my free time trying to come up with subtle ways to better
last week's tight shot-group I got with my bench-rest rifle
with the diamond-lapped, air-gaged Krieger barrel. I weigh
and sort each boat-tailed projectile to the nearest 0.1 grain,
I check every handloaded cartridge case for neck concentricity
and runout error.  I weigh and match all my cartridge cases, I
weigh each boat-tailed Berger benchrest grade bullet.  I weigh
each powder charge to the nearest 0.1 grain. Every primer
pocket is cleaned and inspected and every primer flash
hole is swaged for uniformity.  I set my wind flags out and
carefully analyze the vagaries of every little zephyr that
wafts over the 400 yard space between me and my target.

After all of this, I am only half way down the list of details
I pay careful attention to, but you get the idea....  Hey--
do I look like the kind of guy that would get sucked down the
slippery slope of paying attention to any kind of activity that
would require attention to microscopic subtle technical details
of some arcane art in order to advance my capabilities by one-half of
one percent (such as paying attention to ADEV, MDEV or close-in
phase noise??)

Not me...

Now, if you will excuse me, I need to prepare for next weeks
shoot by spinning each of these projectiles on my ultrasonic
testing instrument and testing for uniform concentric jacket
thickness...

Cheers!!

Mike Baker
WA4HFR
Gainesville, FL



From quenbob5 at pacbell.net  Mon Dec 22 02:33:49 2008
From: quenbob5 at pacbell.net (Bob Q)
Date: Sun, 21 Dec 2008 18:33:49 -0800
Subject: [time-nuts] Jupiter modules: 1pps or 10kHz to lock an OCXO ?
References: <969255.43432.qm@web58802.mail.re1.yahoo.com>
Message-ID: <001301c963dd$b9b3a450$1801a8c0@BOBCEL1R7>

I thought of something else.  Time to lock can be really long.  Say the OCXO 
can swing +/- 1 ppm, +/- 10 Hz at 10 MHz.  The +/- 1 ppm also applies to 0.5 
Hz.  To swing 180 degrees at 0.5 Hz, assuming the low pass filtered control 
signal pushes the OCXO the full 1 ppm, will take 1e6 seconds unless you use 
a circuit similar to what I used to prealign 50 Hz signals in the 100 Hz 
Motorola Oncore design.
Bob Q.
----- Original Message ----- 
From: "Patrick Reynaert" <preynaert at yahoo.com>
To: "time-nuts" <time-nuts at febo.com>
Sent: Sunday, December 21, 2008 2:13 PM
Subject: [time-nuts] Jupiter modules: 1pps or 10kHz to lock an OCXO ?


> Hello,
>
>
> Using the 10kHz output to lock an OCXO is common practice and seems to 
> give good results.
>
> Has anyone tried to use the 1pps output? One? could first make a simple 
> divider to create a 0.5Hz reference with 50% duty cycle, and then use this 
> signal to lock an OCXO. This would also allow the use of other OEM GPS 
> modules that don't have the 10kHz but only the 1pps signal.
>
> Of course, as the 0.5Hz signal is much lower in frequency than 10kHz, the 
> short-term stability is pushed more to the OCXO, making the requirements 
> of the OCXO even harder.
>
> But maybe the 1pps signal has better stability than the 10kHz signal? Or 
> is this the same since these signals will only influence the long-term 
> stability of the oscillator and have the same accuracy?
>
> Any thoughts are highly appreciated.
>
> Thanks,
> Patrick.
>
>
>
>
>
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to 
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there. 



From wd6cmu at earthlink.net  Mon Dec 22 02:41:59 2008
From: wd6cmu at earthlink.net (Eric Williams)
Date: Sun, 21 Dec 2008 18:41:59 -0800
Subject: [time-nuts] He is a Time-Nut Troublemaker....
In-Reply-To: <494EFB61.5000603@clanbaker.org>
References: <494EFB61.5000603@clanbaker.org>
Message-ID: <494EFE77.2080904@earthlink.net>

Michael Baker wrote:
> Just ducked out of my cave to let you know that
> you are a troublemaker.  Get another T-bolt... Right.
> --Just what I need... another techno-addiction.  As far as
> "sweet innocence" is concerned, I lost all I ever had
> when I jumped head-first into bench-rest rifle competition
> 15 years ago.  You have your addiction-- I already have mine
> in the never ending search to find the magic combination
> of details that produce the holy-grail of a 10-shot half-inch
> group at 400 yards...
>  the instructions there.
>   

I have my 3-shot half-inch group at 600 yards, that's enough for me. 

Yeah, I know, it's not statistically significant.  I guess it's like 
having only one clock.


From sar10538 at gmail.com  Mon Dec 22 03:19:19 2008
From: sar10538 at gmail.com (Steve Rooke)
Date: Mon, 22 Dec 2008 16:19:19 +1300
Subject: [time-nuts] Solstice question, about 5000 years ago
In-Reply-To: <0812212125.AA02184@ivan.Harhan.ORG>
References: <0812212125.AA02184@ivan.Harhan.ORG>
Message-ID: <1231b6a80812211919g36e5d363k90d8ad994d99e540@mail.gmail.com>

Michael,

2008/12/22 Michael Sokolov <msokolov at ivan.harhan.org>:
> Bill Hawkins <bill at iaxs.net> wrote:
>
>> The passage grave at New Grange, Ireland, is one of those astronomical
>> wonders where the rising sun at winter solstice shines down a relatively
>> long tunnel to shine on carved stone at the far wall of a chamber.
>>
>> We know that solstice has the shortest day and the longest night.
>>
>> How'd they know that?
>
> I'll abstain from answering the last question, but I'm more interested
> in a different question: from what I understand, the exact shape of the
> analemma depends on the misalignment between the line of apses (aphelion
> and perihelion of Earth's slightly eccentric orbit) and the solstices
> and equinoxes defined by Earth's obliquity.  These things do change very
> slowly over the course of millennia, don't they?  Isn't that change
> significant enough that the correct stone alignment would be different
> between today and 5000 y ago?  If they got it right 5000 y ago for their
> epoch, why does it still work now?  Hasn't the analemma shifted far
> enough to break the alignment?

This is a very interesting point, of course, so this is my 2c worth:-

1) We talk about nano/pico/femto second differences here but I wonder
just how far the analema has shifted in the 5000 years and just how
much difference it would make physically to this location in Ireland.
I assume the slit of light that shines through the passage is not
microns wide and the target, similar. It may be that the change only
makes a small physical difference and is within the accuracy
percentage of the measuring instrument, being The Passage Grave.

2) Is it possible that any shift in the analema may be circular over
that time and has reverted to it's position of 5000 years ago.

3) Bill said that this alignment is noted at rising sun on the winter
solstice. Is it possible that originally the alignment was at a
different time of the day, say, mid-day which would seem to be a
better target to aim for.

4) Stonehenge dates from about the same time and there is a suggestion
that this has an astronomical connection. If that is the case, it
would also be affected by any shift in the analema but I wonder how
much physical difference that would make considering, what appears to
me, to be an instrument with quite a degree of accuracy latitude.

73, Steve - JAKDTTNW (yes, I got it right this time, said I was a troglodyte :-)
-- 
Steve Rooke - ZL3TUV & G8KVD
Omnium finis imminet


From james.p.lux at jpl.nasa.gov  Mon Dec 22 03:27:37 2008
From: james.p.lux at jpl.nasa.gov (Lux, James P)
Date: Sun, 21 Dec 2008 19:27:37 -0800
Subject: [time-nuts] How good is my T-bolt...??
In-Reply-To: <1231b6a80812211827g7f0d2b57i465372619dc27df@mail.gmail.com>
Message-ID: <C5744929.3AE9%James.P.Lux@jpl.nasa.gov>




On 12/21/08 6:27 PM, "Steve Rooke" <sar10538 at gmail.com> wrote:

> 2008/12/22 Mike Monett <XDE-L2G3 at myamail.com>:
>>
>>  Right now,  you don't have enough clocks. The only real  solution to
>>  your problem, is to get another TBolt:)
>
> But which one of them is going to be right...
>
> 73, Steve - JAKDTNW  (just another knuckle dragging troglodyte time-nut
> wan

The man who has two clocks never knows which one is right.  You need at
least three.




From sar10538 at gmail.com  Mon Dec 22 03:36:57 2008
From: sar10538 at gmail.com (Steve Rooke)
Date: Mon, 22 Dec 2008 16:36:57 +1300
Subject: [time-nuts] Speedometers -- bah, humbug
In-Reply-To: <494EC088.8080901@tiscali.co.uk>
References: <mailman.590.1229880891.2499.time-nuts@febo.com>
	<9647ECAA-5CEA-4F44-9495-67436E36C797@hughes.net>
	<494EC088.8080901@tiscali.co.uk>
Message-ID: <1231b6a80812211936g1b95d85clcdedcb24c90a5aff@mail.gmail.com>

2008/12/22 Dave Ackrill <dave.g0dja at tiscali.co.uk>:
> Richard Moore wrote:
>>  The answer? The Feds then
>> required the speedometer to read not less than 2% nor more than 8%
>> high -- oddly enough, 5% is the mean of this variance. I don't know
>> what's required now. My '02 Toyota Highlander reads a tad less than
>> 1% high, based on readings from my Garmin eTrex.
>>
>>
> That's true this side of the herring pond as well...
>
> So, if you are caught on camera, you cannot say your speedo was telling
> you that you were under the speed limit.
>
> However, over here, you can still challenge the plods (UK term for
> Police Officers) to show that their measuring instruments were correctly
> callibrated on the day that they tracked you...
>
> If they did not keep to the law on this, then you were not lawfully
> shown to be over the limit.

Just a bit off topic but it's probably a waste of time having a really
accurate spedo over here in New Zealand. We have roadside cameras
which have a coil of wire in the road and the action of a speeding car
travelling over the coil triggers the speed detector. To me it seems
quite privative and I'd bet that it is not that accurate. A while back
someone contested a speeding ticket on the grounds that they wanted to
verify that the unit had been calibrated. Well it seems they cannot
reliably check the accuracy so this seemed to be a way out of any
ticket issued by these units therefore making all of them throughout
the country redundant. So the government fixed this by making a law
that basically said that the units don't need to be checked for
accuracy and that tickets given out by them cannot be challenged on
this issue.

73, Steve - JAKDTTNW
-- 
Steve Rooke - ZL3TUV & G8KVD
Omnium finis imminet


From brooke at pacific.net  Mon Dec 22 03:38:11 2008
From: brooke at pacific.net (Brooke Clarke)
Date: Sun, 21 Dec 2008 19:38:11 -0800
Subject: [time-nuts] Solstice question, about 5000 years ago
In-Reply-To: <1231b6a80812211919g36e5d363k90d8ad994d99e540@mail.gmail.com>
References: <0812212125.AA02184@ivan.Harhan.ORG>
	<1231b6a80812211919g36e5d363k90d8ad994d99e540@mail.gmail.com>
Message-ID: <494F0BA3.9020003@pacific.net>

Hi:

Isn't it the case that if the tilt of the Earth's spin axis is the same now as 
it was 5,000 years ago that the Sun will shine through the tunnel at the 
Solstice independent of any time or calender changes between then and now.

If, the tilt axis has changed then all bets are off.


Have Fun,

Brooke Clarke
http://www.prc68.com

Steve Rooke wrote:
> Michael,
> 
> 2008/12/22 Michael Sokolov <msokolov at ivan.harhan.org>:
>> Bill Hawkins <bill at iaxs.net> wrote:
>>
>>> The passage grave at New Grange, Ireland, is one of those astronomical
>>> wonders where the rising sun at winter solstice shines down a relatively
>>> long tunnel to shine on carved stone at the far wall of a chamber.
>>>
>>> We know that solstice has the shortest day and the longest night.
>>>
>>> How'd they know that?
>> I'll abstain from answering the last question, but I'm more interested
>> in a different question: from what I understand, the exact shape of the
>> analemma depends on the misalignment between the line of apses (aphelion
>> and perihelion of Earth's slightly eccentric orbit) and the solstices
>> and equinoxes defined by Earth's obliquity.  These things do change very
>> slowly over the course of millennia, don't they?  Isn't that change
>> significant enough that the correct stone alignment would be different
>> between today and 5000 y ago?  If they got it right 5000 y ago for their
>> epoch, why does it still work now?  Hasn't the analemma shifted far
>> enough to break the alignment?
> 
> This is a very interesting point, of course, so this is my 2c worth:-
> 
> 1) We talk about nano/pico/femto second differences here but I wonder
> just how far the analema has shifted in the 5000 years and just how
> much difference it would make physically to this location in Ireland.
> I assume the slit of light that shines through the passage is not
> microns wide and the target, similar. It may be that the change only
> makes a small physical difference and is within the accuracy
> percentage of the measuring instrument, being The Passage Grave.
> 
> 2) Is it possible that any shift in the analema may be circular over
> that time and has reverted to it's position of 5000 years ago.
> 
> 3) Bill said that this alignment is noted at rising sun on the winter
> solstice. Is it possible that originally the alignment was at a
> different time of the day, say, mid-day which would seem to be a
> better target to aim for.
> 
> 4) Stonehenge dates from about the same time and there is a suggestion
> that this has an astronomical connection. If that is the case, it
> would also be affected by any shift in the analema but I wonder how
> much physical difference that would make considering, what appears to
> me, to be an instrument with quite a degree of accuracy latitude.
> 
> 73, Steve - JAKDTTNW (yes, I got it right this time, said I was a troglodyte :-)



From aa8k at comcast.net  Mon Dec 22 03:40:38 2008
From: aa8k at comcast.net (Mike Naruta AA8K)
Date: Sun, 21 Dec 2008 22:40:38 -0500
Subject: [time-nuts] How good is my T-bolt...??
In-Reply-To: <C5744929.3AE9%James.P.Lux@jpl.nasa.gov>
References: <C5744929.3AE9%James.P.Lux@jpl.nasa.gov>
Message-ID: <494F0C36.3020009@comcast.net>

What if all three are different from each other?

Or, if two agree, how do you know that the
two are not both wrong?

If you have 30 clocks and 20 say one time while
10 say another time, do you go with the majority?

Is there not a small probability that the 10 are correct?


:)


Lux, James P wrote:
> 
> 

> 
> The man who has two clocks never knows which one is right.  You need at
> least three.
> 
> 


From sar10538 at gmail.com  Mon Dec 22 03:40:40 2008
From: sar10538 at gmail.com (Steve Rooke)
Date: Mon, 22 Dec 2008 16:40:40 +1300
Subject: [time-nuts] How good is my T-bolt...??
In-Reply-To: <C5744929.3AE9%James.P.Lux@jpl.nasa.gov>
References: <1231b6a80812211827g7f0d2b57i465372619dc27df@mail.gmail.com>
	<C5744929.3AE9%James.P.Lux@jpl.nasa.gov>
Message-ID: <1231b6a80812211940m29482d4cu11432ef7f7167b63@mail.gmail.com>

2008/12/22 Lux, James P <james.p.lux at jpl.nasa.gov>:
>
>
>
> On 12/21/08 6:27 PM, "Steve Rooke" <sar10538 at gmail.com> wrote:
>
>> 2008/12/22 Mike Monett <XDE-L2G3 at myamail.com>:
>>>
>>>  Right now,  you don't have enough clocks. The only real  solution to
>>>  your problem, is to get another TBolt:)
>>
>> But which one of them is going to be right...
>>
>> 73, Steve - JAKDTNW  (just another knuckle dragging troglodyte time-nut
>> wan
>
> The man who has two clocks never knows which one is right.  You need at
> least three.

Exactly, and what's more it grows like topsy, ask Tom.

73, Steve - JAKDTTNW
-- 
Steve Rooke - ZL3TUV & G8KVD
Omnium finis imminet


From bruce.griffiths at xtra.co.nz  Mon Dec 22 03:47:59 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Mon, 22 Dec 2008 16:47:59 +1300
Subject: [time-nuts] Solstice question, about 5000 years ago
In-Reply-To: <1231b6a80812211919g36e5d363k90d8ad994d99e540@mail.gmail.com>
References: <0812212125.AA02184@ivan.Harhan.ORG>
	<1231b6a80812211919g36e5d363k90d8ad994d99e540@mail.gmail.com>
Message-ID: <494F0DEF.5010903@xtra.co.nz>

Steve
Steve Rooke wrote:

> Michael,
>
> 2008/12/22 Michael Sokolov <msokolov at ivan.harhan.org>:
>   
>> Bill Hawkins <bill at iaxs.net> wrote:
>>
>>     
>>> The passage grave at New Grange, Ireland, is one of those astronomical
>>> wonders where the rising sun at winter solstice shines down a relatively
>>> long tunnel to shine on carved stone at the far wall of a chamber.
>>>
>>> We know that solstice has the shortest day and the longest night.
>>>
>>> How'd they know that?
>>>       
>> I'll abstain from answering the last question, but I'm more interested
>> in a different question: from what I understand, the exact shape of the
>> analemma depends on the misalignment between the line of apses (aphelion
>> and perihelion of Earth's slightly eccentric orbit) and the solstices
>> and equinoxes defined by Earth's obliquity.  These things do change very
>> slowly over the course of millennia, don't they?  Isn't that change
>> significant enough that the correct stone alignment would be different
>> between today and 5000 y ago?  If they got it right 5000 y ago for their
>> epoch, why does it still work now?  Hasn't the analemma shifted far
>> enough to break the alignment?
>>     
>
> This is a very interesting point, of course, so this is my 2c worth:-
>
> 1) We talk about nano/pico/femto second differences here but I wonder
> just how far the analema has shifted in the 5000 years and just how
> much difference it would make physically to this location in Ireland.
> I assume the slit of light that shines through the passage is not
> microns wide and the target, similar. It may be that the change only
> makes a small physical difference and is within the accuracy
> percentage of the measuring instrument, being The Passage Grave.
>   
The sun has an angular diameter of about 1/2 degree so it would be
difficult to achieve an alignment accuracy much better (<10% of suns
diameter) than that without optical aids.
To get some idea of the potential accuracy and resolution of the setup
some dimensions would be useful.
> 2) Is it possible that any shift in the analema may be circular over
> that time and has reverted to it's position of 5000 years ago.
>
> 3) Bill said that this alignment is noted at rising sun on the winter
> solstice. Is it possible that originally the alignment was at a
> different time of the day, say, mid-day which would seem to be a
> better target to aim for.
>
>   
When the sun is at its highest point in the sky the vertical alignment
will be quite different than when it is near the horizon.
If the sun is near the horizon refraction is quite significant.
However regular refraction will have no effect on its apparent azimuth.
> 4) Stonehenge dates from about the same time and there is a suggestion
> that this has an astronomical connection. If that is the case, it
> would also be affected by any shift in the analema but I wonder how
> much physical difference that would make considering, what appears to
> me, to be an instrument with quite a degree of accuracy latitude.
>
> 73, Steve - JAKDTTNW (yes, I got it right this time, said I was a troglodyte :-)
>   

Bruce


From sar10538 at gmail.com  Mon Dec 22 03:51:25 2008
From: sar10538 at gmail.com (Steve Rooke)
Date: Mon, 22 Dec 2008 16:51:25 +1300
Subject: [time-nuts] How good is my T-bolt...??
In-Reply-To: <494F0C36.3020009@comcast.net>
References: <C5744929.3AE9%James.P.Lux@jpl.nasa.gov>
	<494F0C36.3020009@comcast.net>
Message-ID: <1231b6a80812211951u698e1061oc1e92a81276db1b2@mail.gmail.com>

2008/12/22 Mike Naruta AA8K <aa8k at comcast.net>:
> What if all three are different from each other?
>
> Or, if two agree, how do you know that the
> two are not both wrong?
>
> If you have 30 clocks and 20 say one time while
> 10 say another time, do you go with the majority?
>
> Is there not a small probability that the 10 are correct?

In that case, who cares about 'their' time, I have my own here and
it's about five'ish now :-)

Statistical probability of measured data from each clock measured over
a long period. At any one time you should be able to predict the
likelihood that certain data is probably going to be correct. I don't
think you can state what is correct just given a single time-slice of
data from a number of clocks.

73, Steve - JAKDTTNW
-- 
Steve Rooke - ZL3TUV & G8KVD
Omnium finis imminet


From bruce.griffiths at xtra.co.nz  Mon Dec 22 04:09:59 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Mon, 22 Dec 2008 17:09:59 +1300
Subject: [time-nuts] Solstice question, about 5000 years ago
In-Reply-To: <494F0DEF.5010903@xtra.co.nz>
References: <0812212125.AA02184@ivan.Harhan.ORG>	<1231b6a80812211919g36e5d363k90d8ad994d99e540@mail.gmail.com>
	<494F0DEF.5010903@xtra.co.nz>
Message-ID: <494F1317.70100@xtra.co.nz>

Bruce Griffiths wrote:
> Steve
> Steve Rooke wrote:
>
>   
>> Michael,
>>
>> 2008/12/22 Michael Sokolov <msokolov at ivan.harhan.org>:
>>   
>>     
>>> Bill Hawkins <bill at iaxs.net> wrote:
>>>
>>>     
>>>       
>>>> The passage grave at New Grange, Ireland, is one of those astronomical
>>>> wonders where the rising sun at winter solstice shines down a relatively
>>>> long tunnel to shine on carved stone at the far wall of a chamber.
>>>>
>>>> We know that solstice has the shortest day and the longest night.
>>>>
>>>> How'd they know that?
>>>>       
>>>>         
>>> I'll abstain from answering the last question, but I'm more interested
>>> in a different question: from what I understand, the exact shape of the
>>> analemma depends on the misalignment between the line of apses (aphelion
>>> and perihelion of Earth's slightly eccentric orbit) and the solstices
>>> and equinoxes defined by Earth's obliquity.  These things do change very
>>> slowly over the course of millennia, don't they?  Isn't that change
>>> significant enough that the correct stone alignment would be different
>>> between today and 5000 y ago?  If they got it right 5000 y ago for their
>>> epoch, why does it still work now?  Hasn't the analemma shifted far
>>> enough to break the alignment?
>>>     
>>>       
>> This is a very interesting point, of course, so this is my 2c worth:-
>>
>> 1) We talk about nano/pico/femto second differences here but I wonder
>> just how far the analema has shifted in the 5000 years and just how
>> much difference it would make physically to this location in Ireland.
>> I assume the slit of light that shines through the passage is not
>> microns wide and the target, similar. It may be that the change only
>> makes a small physical difference and is within the accuracy
>> percentage of the measuring instrument, being The Passage Grave.
>>   
>>     
> The sun has an angular diameter of about 1/2 degree so it would be
> difficult to achieve an alignment accuracy much better (<10% of suns
> diameter) than that without optical aids.
> To get some idea of the potential accuracy and resolution of the setup
> some dimensions would be useful.
>   
>> 2) Is it possible that any shift in the analema may be circular over
>> that time and has reverted to it's position of 5000 years ago.
>>
>> 3) Bill said that this alignment is noted at rising sun on the winter
>> solstice. Is it possible that originally the alignment was at a
>> different time of the day, say, mid-day which would seem to be a
>> better target to aim for.
>>
>>   
>>     
> When the sun is at its highest point in the sky the vertical alignment
> will be quite different than when it is near the horizon.
> If the sun is near the horizon refraction is quite significant.
> However regular refraction will have no effect on its apparent azimuth.
>   
>> 4) Stonehenge dates from about the same time and there is a suggestion
>> that this has an astronomical connection. If that is the case, it
>> would also be affected by any shift in the analema but I wonder how
>> much physical difference that would make considering, what appears to
>> me, to be an instrument with quite a degree of accuracy latitude.
>>
>> 73, Steve - JAKDTTNW (yes, I got it right this time, said I was a troglodyte :-)
>>   
>>     
>
> Bruce
>
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>
>   
According to the Wikipedia entry on Newgrange the duration of the
illumination of the floor at the end of the 18m long passage is 17
minutes and the time at which the floor is initially illuminated on the
Winter Solstice occurs at 4 minutes after sunset in our time. Precession
over the intervening 5000 years means that when constructed the initial
illumination would have occured exactly at sunrise. The geometry
precludes using any other time of day for alignment.


Bruce


From hmurray at megapathdsl.net  Mon Dec 22 04:12:24 2008
From: hmurray at megapathdsl.net (Hal Murray)
Date: Sun, 21 Dec 2008 20:12:24 -0800
Subject: [time-nuts] How good is my T-bolt...??
In-Reply-To: Message from Mike Naruta AA8K <aa8k@comcast.net> 
	of "Sun, 21 Dec 2008 22:40:38 EST." <494F0C36.3020009@comcast.net> 
Message-ID: <20081222041225.01AD2BCD9@ip-64-139-1-69.sjc.megapath.net>


> What if all three are different from each other?

Then you have a problem to debug.

> Or, if two agree, how do you know that the two are not both wrong?
> If you have 30 clocks and 20 say one time while 10 say another time,
> do you go with the majority?

> Is there not a small probability that the 10 are correct? 

Sure.  A lot of this depends upon whether you are talking about an initial 
setup/install or a set of clocks that have been running correctly for a while.

If you have 3 clocks of the same brand that have been running OK for a while 
and now 1 disagrees, the most likely problem is that it broke.

If you have 10 clocks of brand A and 20 clocks of brand B and the two sets 
agree within the set but disagree with the other set, then you probably have 
a design error and the number of clocks in each set doesn't tell you much 
about which one is likely to be right.

If your 3 or 30 clocks all agree with eachother, there is a chance that they 
are all wrong due to a design error or some problem common to all of them.




-- 
These are my opinions, not necessarily my employer's.  I hate spam.





From akbiocca at comcast.net  Mon Dec 22 04:31:40 2008
From: akbiocca at comcast.net (Alan Biocca)
Date: Sun, 21 Dec 2008 20:31:40 -0800
Subject: [time-nuts] Solstice question, about 5000 years ago
In-Reply-To: <494F1317.70100@xtra.co.nz>
References: <0812212125.AA02184@ivan.Harhan.ORG>
	<1231b6a80812211919g36e5d363k90d8ad994d99e540@mail.gmail.com>
	<494F0DEF.5010903@xtra.co.nz> <494F1317.70100@xtra.co.nz>
Message-ID: <df3c5e400812212031k3c2d9a5aiedfd66fa1efc0da4@mail.gmail.com>

The sun is illuminating the floor 4 minutes after sunset?

-- Alan

On Sun, Dec 21, 2008 at 8:09 PM, Bruce Griffiths <bruce.griffiths at xtra.co.nz
> wrote:

> Bruce Griffiths wrote:
> > Steve
> > Steve Rooke wrote:
> >
> >
> >> Michael,
> >>
> >> 2008/12/22 Michael Sokolov <msokolov at ivan.harhan.org>:
> >>
> >>
> >>> Bill Hawkins <bill at iaxs.net> wrote:
> >>>
> >>>
> >>>
> >>>> The passage grave at New Grange, Ireland, is one of those astronomical
> >>>> wonders where the rising sun at winter solstice shines down a
> relatively
> >>>> long tunnel to shine on carved stone at the far wall of a chamber.
> >>>>
> >>>> We know that solstice has the shortest day and the longest night.
> >>>>
> >>>> How'd they know that?
> >>>>
> >>>>
> >>> I'll abstain from answering the last question, but I'm more interested
> >>> in a different question: from what I understand, the exact shape of the
> >>> analemma depends on the misalignment between the line of apses
> (aphelion
> >>> and perihelion of Earth's slightly eccentric orbit) and the solstices
> >>> and equinoxes defined by Earth's obliquity.  These things do change
> very
> >>> slowly over the course of millennia, don't they?  Isn't that change
> >>> significant enough that the correct stone alignment would be different
> >>> between today and 5000 y ago?  If they got it right 5000 y ago for
> their
> >>> epoch, why does it still work now?  Hasn't the analemma shifted far
> >>> enough to break the alignment?
> >>>
> >>>
> >> This is a very interesting point, of course, so this is my 2c worth:-
> >>
> >> 1) We talk about nano/pico/femto second differences here but I wonder
> >> just how far the analema has shifted in the 5000 years and just how
> >> much difference it would make physically to this location in Ireland.
> >> I assume the slit of light that shines through the passage is not
> >> microns wide and the target, similar. It may be that the change only
> >> makes a small physical difference and is within the accuracy
> >> percentage of the measuring instrument, being The Passage Grave.
> >>
> >>
> > The sun has an angular diameter of about 1/2 degree so it would be
> > difficult to achieve an alignment accuracy much better (<10% of suns
> > diameter) than that without optical aids.
> > To get some idea of the potential accuracy and resolution of the setup
> > some dimensions would be useful.
> >
> >> 2) Is it possible that any shift in the analema may be circular over
> >> that time and has reverted to it's position of 5000 years ago.
> >>
> >> 3) Bill said that this alignment is noted at rising sun on the winter
> >> solstice. Is it possible that originally the alignment was at a
> >> different time of the day, say, mid-day which would seem to be a
> >> better target to aim for.
> >>
> >>
> >>
> > When the sun is at its highest point in the sky the vertical alignment
> > will be quite different than when it is near the horizon.
> > If the sun is near the horizon refraction is quite significant.
> > However regular refraction will have no effect on its apparent azimuth.
> >
> >> 4) Stonehenge dates from about the same time and there is a suggestion
> >> that this has an astronomical connection. If that is the case, it
> >> would also be affected by any shift in the analema but I wonder how
> >> much physical difference that would make considering, what appears to
> >> me, to be an instrument with quite a degree of accuracy latitude.
> >>
> >> 73, Steve - JAKDTTNW (yes, I got it right this time, said I was a
> troglodyte :-)
> >>
> >>
> >
> > Bruce
> >
> > _______________________________________________
> > time-nuts mailing list -- time-nuts at febo.com
> > To unsubscribe, go to
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> > and follow the instructions there.
> >
> >
> According to the Wikipedia entry on Newgrange the duration of the
> illumination of the floor at the end of the 18m long passage is 17
> minutes and the time at which the floor is initially illuminated on the
> Winter Solstice occurs at 4 minutes after sunset in our time. Precession
> over the intervening 5000 years means that when constructed the initial
> illumination would have occured exactly at sunrise. The geometry
> precludes using any other time of day for alignment.
>
>
> Bruce
>
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>

From holrum at hotmail.com  Mon Dec 22 04:36:08 2008
From: holrum at hotmail.com (Mark Sims)
Date: Mon, 22 Dec 2008 04:36:08 +0000
Subject: [time-nuts] He is a Time-Nut Troublemaker....
In-Reply-To: <mailman.600.1229917104.2499.time-nuts@febo.com>
References: <mailman.600.1229917104.2499.time-nuts@febo.com>
Message-ID: <BLU125-W46831CE6F2E119B7EEBE6CCEEF0@phx.gbl>


I got to play with a custom .50 BMG that shoots meaningful groups at 1500 meters...  the maker's definition of "meaningful group" is "smaller than your head".  I managed to put two rounds through pretty much the same hole.  Don't know where most of the other 18 rounds went...  Then there was his .17 cal varmint rifle.  Does wonders for groundhoggies at 500 yards.  Most gawd awful recoil through.  I was black and blue for a month.  The barrel and all the hardware in those guns is finished to optical tolerances and maintains it despite having just a little less energy than a small nuke going off each time you fire.

_________________________________________________________________
Send e-mail anywhere. No map, no compass.
http://windowslive.com/oneline/hotmail?ocid=TXT_TAGLM_WL_hotmail_acq_anywhere_122008

From bruce.griffiths at xtra.co.nz  Mon Dec 22 04:50:20 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Mon, 22 Dec 2008 17:50:20 +1300
Subject: [time-nuts] Solstice question, about 5000 years ago
In-Reply-To: <df3c5e400812212031k3c2d9a5aiedfd66fa1efc0da4@mail.gmail.com>
References: <0812212125.AA02184@ivan.Harhan.ORG>	<1231b6a80812211919g36e5d363k90d8ad994d99e540@mail.gmail.com>	<494F0DEF.5010903@xtra.co.nz>
	<494F1317.70100@xtra.co.nz>
	<df3c5e400812212031k3c2d9a5aiedfd66fa1efc0da4@mail.gmail.com>
Message-ID: <494F1C8C.4060304@xtra.co.nz>

Alan Biocca wrote:
> The sun is illuminating the floor 4 minutes after sunset?
>
>   
Oops! Thanks, I thought sunrise and typed sunset.

Actually the sun is visible after geometric sunset due to atmospheric
refraction.

corrected version:

According to the Wikipedia entry on Newgrange the duration of the
illumination of the floor at the end of the 18m long passage is 17
minutes and the time at which the floor is initially illuminated on the
Winter Solstice occurs at 4 minutes after sunrise in our time. Precession
over the intervening 5000 years means that when constructed the initial
illumination would have occurred exactly at sunrise. The geometry
precludes using any other time of day for alignment.



Bruce
> -- Alan
>
> On Sun, Dec 21, 2008 at 8:09 PM, Bruce Griffiths <bruce.griffiths at xtra.co.nz
>   
>> wrote:
>>     
>
>   
>> Bruce Griffiths wrote:
>>     
>>> Steve
>>> Steve Rooke wrote:
>>>
>>>
>>>       
>>>> Michael,
>>>>
>>>> 2008/12/22 Michael Sokolov <msokolov at ivan.harhan.org>:
>>>>
>>>>
>>>>         
>>>>> Bill Hawkins <bill at iaxs.net> wrote:
>>>>>
>>>>>
>>>>>
>>>>>           
>>>>>> The passage grave at New Grange, Ireland, is one of those astronomical
>>>>>> wonders where the rising sun at winter solstice shines down a
>>>>>>             
>> relatively
>>     
>>>>>> long tunnel to shine on carved stone at the far wall of a chamber.
>>>>>>
>>>>>> We know that solstice has the shortest day and the longest night.
>>>>>>
>>>>>> How'd they know that?
>>>>>>
>>>>>>
>>>>>>             
>>>>> I'll abstain from answering the last question, but I'm more interested
>>>>> in a different question: from what I understand, the exact shape of the
>>>>> analemma depends on the misalignment between the line of apses
>>>>>           
>> (aphelion
>>     
>>>>> and perihelion of Earth's slightly eccentric orbit) and the solstices
>>>>> and equinoxes defined by Earth's obliquity.  These things do change
>>>>>           
>> very
>>     
>>>>> slowly over the course of millennia, don't they?  Isn't that change
>>>>> significant enough that the correct stone alignment would be different
>>>>> between today and 5000 y ago?  If they got it right 5000 y ago for
>>>>>           
>> their
>>     
>>>>> epoch, why does it still work now?  Hasn't the analemma shifted far
>>>>> enough to break the alignment?
>>>>>
>>>>>
>>>>>           
>>>> This is a very interesting point, of course, so this is my 2c worth:-
>>>>
>>>> 1) We talk about nano/pico/femto second differences here but I wonder
>>>> just how far the analema has shifted in the 5000 years and just how
>>>> much difference it would make physically to this location in Ireland.
>>>> I assume the slit of light that shines through the passage is not
>>>> microns wide and the target, similar. It may be that the change only
>>>> makes a small physical difference and is within the accuracy
>>>> percentage of the measuring instrument, being The Passage Grave.
>>>>
>>>>
>>>>         
>>> The sun has an angular diameter of about 1/2 degree so it would be
>>> difficult to achieve an alignment accuracy much better (<10% of suns
>>> diameter) than that without optical aids.
>>> To get some idea of the potential accuracy and resolution of the setup
>>> some dimensions would be useful.
>>>
>>>       
>>>> 2) Is it possible that any shift in the analema may be circular over
>>>> that time and has reverted to it's position of 5000 years ago.
>>>>
>>>> 3) Bill said that this alignment is noted at rising sun on the winter
>>>> solstice. Is it possible that originally the alignment was at a
>>>> different time of the day, say, mid-day which would seem to be a
>>>> better target to aim for.
>>>>
>>>>
>>>>
>>>>         
>>> When the sun is at its highest point in the sky the vertical alignment
>>> will be quite different than when it is near the horizon.
>>> If the sun is near the horizon refraction is quite significant.
>>> However regular refraction will have no effect on its apparent azimuth.
>>>
>>>       
>>>> 4) Stonehenge dates from about the same time and there is a suggestion
>>>> that this has an astronomical connection. If that is the case, it
>>>> would also be affected by any shift in the analema but I wonder how
>>>> much physical difference that would make considering, what appears to
>>>> me, to be an instrument with quite a degree of accuracy latitude.
>>>>
>>>> 73, Steve - JAKDTTNW (yes, I got it right this time, said I was a
>>>>         
>> troglodyte :-)
>>     
>>>>         
>>> Bruce
>>>
>>> _______________________________________________
>>> time-nuts mailing list -- time-nuts at febo.com
>>> To unsubscribe, go to
>>>       
>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>>     
>>> and follow the instructions there.
>>>
>>>
>>>       
>> According to the Wikipedia entry on Newgrange the duration of the
>> illumination of the floor at the end of the 18m long passage is 17
>> minutes and the time at which the floor is initially illuminated on the
>> Winter Solstice occurs at 4 minutes after sunset in our time. Precession
>> over the intervening 5000 years means that when constructed the initial
>> illumination would have occured exactly at sunrise. The geometry
>> precludes using any other time of day for alignment.
>>
>>
>> Bruce
>>
>> _______________________________________________
>> time-nuts mailing list -- time-nuts at febo.com
>> To unsubscribe, go to
>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>> and follow the instructions there.
>>
>>     
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>
>   



From bruce.griffiths at xtra.co.nz  Mon Dec 22 04:55:00 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Mon, 22 Dec 2008 17:55:00 +1300
Subject: [time-nuts] He is a Time-Nut Troublemaker....
In-Reply-To: <BLU125-W46831CE6F2E119B7EEBE6CCEEF0@phx.gbl>
References: <mailman.600.1229917104.2499.time-nuts@febo.com>
	<BLU125-W46831CE6F2E119B7EEBE6CCEEF0@phx.gbl>
Message-ID: <494F1DA4.4000106@xtra.co.nz>

Mark Sims wrote:
> I got to play with a custom .50 BMG that shoots meaningful groups at 1500 meters...  the maker's definition of "meaningful group" is "smaller than your head".  I managed to put two rounds through pretty much the same hole.  Don't know where most of the other 18 rounds went...  Then there was his .17 cal varmint rifle.  Does wonders for groundhoggies at 500 yards.  Most gawd awful recoil through.  I was black and blue for a month.  The barrel and all the hardware in those guns is finished to optical tolerances and maintains it despite having just a little less energy than a small nuke going off each time you fire.
>
>   
The fact that the direction in which the last 4" of the barrel largely
determines the initial trajectory of the bullet (in absence of crosswind
etc) was made use of to assist in alignment of the sights during mass
production of infantry rifles during WWII.

Bruce


From richiem at hughes.net  Mon Dec 22 05:23:50 2008
From: richiem at hughes.net (Richard Moore)
Date: Sun, 21 Dec 2008 21:23:50 -0800
Subject: [time-nuts] Solstice at Newgrange
In-Reply-To: <mailman.600.1229917104.2499.time-nuts@febo.com>
References: <mailman.600.1229917104.2499.time-nuts@febo.com>
Message-ID: <F409300F-96EA-4BAB-A8DB-F5F55BC77BD0@hughes.net>

> A visit to this site, which I make every day I can, and to this  
> particular page, will answer many questions and raise many more:

http://antwrp.gsfc.nasa.gov/apod/ap081220.html

Dick Moore
>
>
> ------------------------------
>
> Message: 5
> Date: Mon, 22 Dec 2008 16:19:19 +1300
> From: "Steve Rooke" <sar10538 at gmail.com>
> Subject: Re: [time-nuts] Solstice question, about 5000 years ago
> To: "Discussion of precise time and frequency measurement"
> 	<time-nuts at febo.com>
> Message-ID:
> 	<1231b6a80812211919g36e5d363k90d8ad994d99e540 at mail.gmail.com>
> Content-Type: text/plain; charset=ISO-8859-1
>
> Michael,
>
> 2008/12/22 Michael Sokolov <msokolov at ivan.harhan.org>:
>> Bill Hawkins <bill at iaxs.net> wrote:
>>
>>> The passage grave at New Grange, Ireland, is one of those  
>>> astronomical
>>> wonders where the rising sun at winter solstice shines down a  
>>> relatively
>>> long tunnel to shine on carved stone at the far wall of a chamber.
>>>
>>> We know that solstice has the shortest day and the longest night.
>>>
>>> How'd they know that?
>>
>> I'll abstain from answering the last question, but I'm more  
>> interested
>> in a different question: from what I understand, the exact shape  
>> of the
>> analemma depends on the misalignment between the line of apses  
>> (aphelion
>> and perihelion of Earth's slightly eccentric orbit) and the solstices
>> and equinoxes defined by Earth's obliquity.  These things do  
>> change very
>> slowly over the course of millennia, don't they?  Isn't that change
>> significant enough that the correct stone alignment would be  
>> different
>> between today and 5000 y ago?  If they got it right 5000 y ago for  
>> their
>> epoch, why does it still work now?  Hasn't the analemma shifted far
>> enough to break the alignment?
>
> This is a very interesting point, of course, so this is my 2c worth:-
>
> 1) We talk about nano/pico/femto second differences here but I wonder
> just how far the analema has shifted in the 5000 years and just how
> much difference it would make physically to this location in Ireland.
> I assume the slit of light that shines through the passage is not
> microns wide and the target, similar. It may be that the change only
> makes a small physical difference and is within the accuracy
> percentage of the measuring instrument, being The Passage Grave.
>
> 2) Is it possible that any shift in the analema may be circular over
> that time and has reverted to it's position of 5000 years ago.
>
> 3) Bill said that this alignment is noted at rising sun on the winter
> solstice. Is it possible that originally the alignment was at a
> different time of the day, say, mid-day which would seem to be a
> better target to aim for.
>
> 4) Stonehenge dates from about the same time and there is a suggestion
> that this has an astronomical connection. If that is the case, it
> would also be affected by any shift in the analema but I wonder how
> much physical difference that would make considering, what appears to
> me, to be an instrument with quite a degree of accuracy latitude.
>
> 73, Steve - JAKDTTNW (yes, I got it right this time, said I was a  
> troglodyte :-)
> -- 
> Steve Rooke - ZL3TUV & G8KVD
> Omnium finis imminet
>
> ------------------------------
>
> Message: 8
> Date: Sun, 21 Dec 2008 19:38:11 -0800
> From: Brooke Clarke <brooke at pacific.net>
> Subject: Re: [time-nuts] Solstice question, about 5000 years ago
> To: Discussion of precise time and frequency measurement
> 	<time-nuts at febo.com>
> Message-ID: <494F0BA3.9020003 at pacific.net>
> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
>
> Hi:
>
> Isn't it the case that if the tilt of the Earth's spin axis is the  
> same now as
> it was 5,000 years ago that the Sun will shine through the tunnel  
> at the
> Solstice independent of any time or calender changes between then  
> and now.
>
> If, the tilt axis has changed then all bets are off.
>
>
> Have Fun,
>
> Brooke Clarke
> http://www.prc68.com
>
> Steve Rooke wrote:
>> Michael,
>>
>> 2008/12/22 Michael Sokolov <msokolov at ivan.harhan.org>:
>>> Bill Hawkins <bill at iaxs.net> wrote:
>>>
>>>> The passage grave at New Grange, Ireland, is one of those  
>>>> astronomical
>>>> wonders where the rising sun at winter solstice shines down a  
>>>> relatively
>>>> long tunnel to shine on carved stone at the far wall of a chamber.
>>>>
>>>> We know that solstice has the shortest day and the longest night.
>>>>
>>>> How'd they know that?
>>> I'll abstain from answering the last question, but I'm more  
>>> interested
>>> in a different question: from what I understand, the exact shape  
>>> of the
>>> analemma depends on the misalignment between the line of apses  
>>> (aphelion
>>> and perihelion of Earth's slightly eccentric orbit) and the  
>>> solstices
>>> and equinoxes defined by Earth's obliquity.  These things do  
>>> change very
>>> slowly over the course of millennia, don't they?  Isn't that change
>>> significant enough that the correct stone alignment would be  
>>> different
>>> between today and 5000 y ago?  If they got it right 5000 y ago  
>>> for their
>>> epoch, why does it still work now?  Hasn't the analemma shifted far
>>> enough to break the alignment?
>>
>> This is a very interesting point, of course, so this is my 2c worth:-
>>
>> 1) We talk about nano/pico/femto second differences here but I wonder
>> just how far the analema has shifted in the 5000 years and just how
>> much difference it would make physically to this location in Ireland.
>> I assume the slit of light that shines through the passage is not
>> microns wide and the target, similar. It may be that the change only
>> makes a small physical difference and is within the accuracy
>> percentage of the measuring instrument, being The Passage Grave.
>>
>> 2) Is it possible that any shift in the analema may be circular over
>> that time and has reverted to it's position of 5000 years ago.
>>
>> 3) Bill said that this alignment is noted at rising sun on the winter
>> solstice. Is it possible that originally the alignment was at a
>> different time of the day, say, mid-day which would seem to be a
>> better target to aim for.
>>
>> 4) Stonehenge dates from about the same time and there is a  
>> suggestion
>> that this has an astronomical connection. If that is the case, it
>> would also be affected by any shift in the analema but I wonder how
>> much physical difference that would make considering, what appears to
>> me, to be an instrument with quite a degree of accuracy latitude.
>>
>> 73, Steve - JAKDTTNW (yes, I got it right this time, said I was a  
>> troglodyte :-)

From bill at iaxs.net  Mon Dec 22 06:15:38 2008
From: bill at iaxs.net (Bill Hawkins)
Date: Mon, 22 Dec 2008 00:15:38 -0600
Subject: [time-nuts] Solstice question, about 5000 years ago
In-Reply-To: <494F1C8C.4060304@xtra.co.nz>
References: <0812212125.AA02184@ivan.Harhan.ORG>	<1231b6a80812211919g36e5d363k90d8ad994d99e540@mail.gmail.com>	<494F0DEF.5010903@xtra.co.nz><494F1317.70100@xtra.co.nz><df3c5e400812212031k3c2d9a5aiedfd66fa1efc0da4@mail.gmail.com>
	<494F1C8C.4060304@xtra.co.nz>
Message-ID: <6629242569E94BF39926B77FBAC1C487@cyrus>

Group,

The question of 5000 year accuracy is moot, according to this quote from
an Irish newspaper, in response to asking Google for "Newgrange
rebuild."

  "This was after the dismantling and replacing of the box under Prof
O'Kelly
   between 1964 and 1967, during which slight changes turned it into a
"narrow
   passage"."

The "box" is a 25 cm high opening (width unspecified) above the entrance
that let light into the passage. Further, the stones that line the
passage
have moved somewhat. Most of the rebuild concerned the quartz blocks
that
covered the East wall of the tomb. The box was unknown in modern times
until that rebuild. Most people trust O'Kelly to have done a proper job.

Seems like the critical alignment is horizontal, as the light shines
down
the passage for about seven days in a row.

Interesting that my dilemma was solved by an analemma.

Thanks to all who responded with intelligence and wit.

Bill Hawkins

And thanks to the Celestial Technicians who refit the fading sun on
Solstice
night to prepare it for the new year.

(Too bad that story doesn't work if the spherical Earth theory is true.)




From hmurray at megapathdsl.net  Mon Dec 22 06:57:32 2008
From: hmurray at megapathdsl.net (Hal Murray)
Date: Sun, 21 Dec 2008 22:57:32 -0800
Subject: [time-nuts] Sub Pico Second Phase logger
In-Reply-To: Message from Joe Gwinn <joegwinn@comcast.net> of "Sun,
	21 Dec 2008 13:46:05 EST." <p06240800c5743311b2a3@[192.168.1.212]>
Message-ID: <20081222065733.931D4BCD9@ip-64-139-1-69.sjc.megapath.net>


> Yes.  Basically, every digital chip in this scheme requires a
> computer of some kind.  What I've seen used is a small CPLD to do the
> initial parameter loads, and then to run the show. 

If you prefer software to hardware, both Microchip (PIC) and Atmel (AVR) make 
microprocessors that are available in 8 pin chips.  There are others too.

-- 
These are my opinions, not necessarily my employer's.  I hate spam.





From df6jb at ulrich-bangert.de  Mon Dec 22 07:56:55 2008
From: df6jb at ulrich-bangert.de (Ulrich Bangert)
Date: Mon, 22 Dec 2008 08:56:55 +0100
Subject: [time-nuts] Sub Pico Second Phase logger
In-Reply-To: <494EC0DA.2010601@xtra.co.nz>
Message-ID: <ED80C477117441E586F381F9D2C6C2AD@athlon>

Joe and Bruce,

> Ulrich has built a circuit that takes a sampling frequency 
> input derived from a 10MHz GPSDO output and produces an 
> S/PDIF output for this application. Its certainly worth 
> trying since all the specs for the sound card aren't readily 
> available.

I use a cheap and easy to use CRYSTAL CS8402 S/PDIF transmitter to
generate the S/PDIF signal for the sound card. Data input just tight to
ground. The balanced output is done with a Minicircuits T1-1T
transformer. The chip needs an 12.844 MHz clock for 96 kHz sample rate
and 6.144 MHz for 48 kHz sample rate. However, these two frequencies are
generated by an old HP3330 locked to 10 MHz in my case. If the circuit
had to be designed new I would have used a ANALOG DEVICES dds circuit
with a built in clock multiplier.

Best regards
Ulrich Bangert   



> -----Ursprungliche Nachricht-----
> Von: time-nuts-bounces at febo.com 
> [mailto:time-nuts-bounces at febo.com] Im Auftrag von Bruce Griffiths
> Gesendet: Sonntag, 21. Dezember 2008 23:19
> An: Discussion of precise time and frequency measurement
> Betreff: Re: [time-nuts] Sub Pico Second Phase logger
> 
> 
> Joe
> 
> Joe Gwinn wrote:
> > Bruce,
> >
> > At 9:50 PM +0000 12/19/08, time-nuts-request at febo.com wrote:
> >   
> >> Message: 7
> >> Date: Sat, 20 Dec 2008 10:38:26 +1300
> >> From: Bruce Griffiths <bruce.griffiths at xtra.co.nz>
> >> Subject: Re: [time-nuts] Sub Pico Second Phase logger
> >> To: Discussion of precise time and frequency measurement
> >> 	<time-nuts at febo.com>
> >>
> >> Joe
> >>
> >> Joe Gwinn wrote:
> >>     
> >>>  Bruce,
> >>>
> >>>  At 3:54 AM +0000 12/19/08, time-nuts-request at febo.com wrote:
> >>>  
> >>>       
> >>>>  Message: 5
> >>>>  Date: Fri, 19 Dec 2008 16:51:55 +1300
> >>>>  From: Bruce Griffiths <bruce.griffiths at xtra.co.nz>
> >>>>  Subject: Re: [time-nuts] Sub Pico Second Phase logger
> >>>>  To: Discussion of precise time and frequency measurement
> >>>> 	<time-nuts at febo.com>
> >>>>
> >>>>  Joe
> >>>>
> >>>>  Joe Gwinn wrote:
> >>>>    
> >>>>         
> >>>>>   At 11:48 PM +0000 12/18/08, time-nuts-request at febo.com wrote:
> >>>>>           
> >>  >>>
> >> [snip]
> >>
> >>     
> >>>  
> >>>       
> >>>>  Some claim to be able to sync to an SPDIF input but the 
> resultant 
> >>>> jitter  may be large.
> >>>>    
> >>>>         
> >>>  Why large jitter?  Bad implementation?
> >>>
> >>>
> >>>  
> >>>       
> >> I'm just suspicious, although I did see some data somewhere that 
> >> seemed to confirm my suspicions. The S/PDIF signal has to 
> be a valid 
> >> SPDIF signal not just a square or sine wave clock.
> >> Output sample rates (for the AP192) are then identical to 
> that of the
> >> the S/PDIF source which is limited to
> >> 192, 176.4, 96,88.2 48, 44.1 32 KSPS.
> >>     
> >
> > I did a little looking.  I bet that the sync quite well, but this
> > signal is pretty complex.  One assumes that there is a box 
> that takes 
> > in a 10 MHz ref and does the rest, because the broadcast industry 
> > does use atomic clocks.
> >
> >
> >   
> Ulrich has built a circuit that takes a sampling frequency 
> input derived from a 10MHz GPSDO output and produces an 
> S/PDIF output for this application. Its certainly worth 
> trying since all the specs for the sound card aren't readily 
> available.
> >>  >
> >>  >>  >>  >> A few divide and mix stages will be required to achieve
> >> a spur free resolution of 10Hz.
> >>  >>>>>>            
> >>     
> >>>>>>>    That is a traditional approach.  But are there alternate
> >>>>>>> approaches that
> >>>>>>>               
> >>  >>>>>   have now become practical?
> >>  >>>>>
> >>  >>>>  Diophantine frequency synthesis?
> >>  >>>>        
> >>     
> >>>>>    From the sound of the name I think so, at least in 
> the last DDS
> >>>>>   stage, as done by that patent.
> >>>>>
> >>>>>           
> >>  >>>  But I was fishing.
> >>  >>>      
> >>     
> >>>>  Conventional Diophantine synthesis uses number theory together 
> >>>> with 2 or  3 conventional synthesiser loops to achieve very fine 
> >>>> resolution whilst
> >>>>         
> >>  >> maintaining a high PLL phase detector input frequency.
> >>  >
> >>     
> >>>  In a sense, the concatenated DDS approach is a divide-and-mix 
> >>> chain.
> >>>       
> >>  > Perhaps there is a parallel here.
> >>  >
> >> The DDS based equivalent (of the dual PLL Diophantine 
> synthesiser) would
> >> use a pair of DDS chips each replacing a conventional PLL in the
> >> Diophantine frequency synthesiser, the output frequency of 
> each having
> >> zero phase truncation spurs.
> >>
> >> Both DDS clock sources should be spur free and have a 
> frequency ratio 
> >> that is a selected fixed rational fraction.
> >>     
> >
> > A M/N PLL chip can arrange this.  I recall that Silicon Labs makes
> > such a chip, which requires a parameter load on power-up, so a 
> > computer or FPGA is needed.
> >
> >
> >   
> M and N only have to be relatively prime (ie the GCD of M and 
> N is 1). The ratio of M/N should also be close to 1. If the 
> spacing of the phase truncation spur free output frequencies 
> is about 10kHz (for either DDS) and M, N ~ 1000 the resultant 
> mixer output frequencies would have a spacing of about 10Hz 
> which may be adequate for this application.
> 
> >> A conventional mixer would then be used to either add or 
> subtract the 
> >> two DDS output frequencies. If the ratio of the 2 DDS clock source 
> >> frequencies is appropriately chosen the spacing between 
> the resultant 
> >> mixer output frequencies can be much finer than the 
> spacing between 
> >> the truncation spur free outputs of either DDS chip.
> >> The DDS and mixer outputs should be filtered to remove 
> harmonics and
> >> other unwanted frequencies.
> >>     
> >
> > If the DDS chips are well chosen, we will get sin and cos outputs,
> > and so can implement a dual-mixer phasing scheme to yield only the 
> > sum frequency or only the difference frequency, greatly 
> reducing the 
> > amount of filtering needed.  The better balanced the 
> channels are the 
> > better the cancellation of the unwanted term.  This is 
> basically the 
> > phasing method of single-sideband signal generation.
> >
> >
> >   
> >> One drawback is that selecting the output frequencies of the 2 DDS 
> >> chips required to produce the desired output frequency is somewhat 
> >> complex. Since one almost certainly needs a computer of 
> some sort to 
> >> set the DDS frequencies this shouldn't be a significant issue.
> >>     
> >
> > Yes.  Basically, every digital chip in this scheme requires a
> > computer of some kind.  What I've seen used is a small CPLD 
> to do the 
> > initial parameter loads, and then to run the show.
> >
> > Joe
> >
> >   
> Bruce
> 
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to 
> https://www.febo.com/cgi-> bin/mailman/listinfo/time-nuts
> and 
> follow the instructions there.
> 



From besten at gmail.com  Mon Dec 22 08:02:38 2008
From: besten at gmail.com (Remco dB)
Date: Mon, 22 Dec 2008 09:02:38 +0100
Subject: [time-nuts] parallel port PPS with FreeBSD
In-Reply-To: <df3c5e400812212031k3c2d9a5aiedfd66fa1efc0da4@mail.gmail.com>
References: <0812212125.AA02184@ivan.Harhan.ORG> <494F1317.70100@xtra.co.nz>
	<df3c5e400812212031k3c2d9a5aiedfd66fa1efc0da4@mail.gmail.com>
Message-ID: <200812220902.38925.besten@gmail.com>

Perhaps this question may be totally off topic or considered to be part of 
the 'newbie category' but I tried to activate PPS on the parallel port (lpt0) 
with FreeBSD.

By the way, the system runs fine with serial PPS but I want to compare the
results of 'serial PPS' and 'parallel PPS' with my system.

I made a symlink /dev/pps1, pointing towards /dev/lpt0.

Using 127.127.22.1 in ntp.conf I get:

22 Dec 07:36:21 ntpd[633]: refclock_atom: /dev/pps1: Device busy

I googled a little and changed the specs for the parallel port in my BIOS
from 'ECP' to 'bi-directional', but the error remains. 

Any ideas what might be the issue here? 

Regards,

Remco


From df6jb at ulrich-bangert.de  Mon Dec 22 08:04:07 2008
From: df6jb at ulrich-bangert.de (Ulrich Bangert)
Date: Mon, 22 Dec 2008 09:04:07 +0100
Subject: [time-nuts] Sub Pico Second Phase logger
In-Reply-To: <ED80C477117441E586F381F9D2C6C2AD@athlon>
Message-ID: <2DF4E29D9ACF4F6DAD3FEF2E262D2621@athlon>

Correction of a typo:

12.288 MHz clock

> -----Ursprungliche Nachricht-----
> Von: time-nuts-bounces at febo.com 
> [mailto:time-nuts-bounces at febo.com] Im Auftrag von Ulrich Bangert
> Gesendet: Montag, 22. Dezember 2008 08:57
> An: 'Discussion of precise time and frequency measurement'
> Betreff: Re: [time-nuts] Sub Pico Second Phase logger
> 
> 
> Joe and Bruce,
> 
> > Ulrich has built a circuit that takes a sampling frequency
> > input derived from a 10MHz GPSDO output and produces an 
> > S/PDIF output for this application. Its certainly worth 
> > trying since all the specs for the sound card aren't readily 
> > available.
> 
> I use a cheap and easy to use CRYSTAL CS8402 S/PDIF 
> transmitter to generate the S/PDIF signal for the sound card. 
> Data input just tight to ground. The balanced output is done 
> with a Minicircuits T1-1T transformer. The chip needs an 
> 12.844 MHz clock for 96 kHz sample rate and 6.144 MHz for 48 
> kHz sample rate. However, these two frequencies are generated 
> by an old HP3330 locked to 10 MHz in my case. If the circuit 
> had to be designed new I would have used a ANALOG DEVICES dds 
> circuit with a built in clock multiplier.
> 
> Best regards
> Ulrich Bangert   
> 
> 
> 
> > -----Ursprungliche Nachricht-----
> > Von: time-nuts-bounces at febo.com
> > [mailto:time-nuts-bounces at febo.com] Im Auftrag von Bruce Griffiths
> > Gesendet: Sonntag, 21. Dezember 2008 23:19
> > An: Discussion of precise time and frequency measurement
> > Betreff: Re: [time-nuts] Sub Pico Second Phase logger
> > 
> > 
> > Joe
> > 
> > Joe Gwinn wrote:
> > > Bruce,
> > >
> > > At 9:50 PM +0000 12/19/08, time-nuts-request at febo.com wrote:
> > >   
> > >> Message: 7
> > >> Date: Sat, 20 Dec 2008 10:38:26 +1300
> > >> From: Bruce Griffiths <bruce.griffiths at xtra.co.nz>
> > >> Subject: Re: [time-nuts] Sub Pico Second Phase logger
> > >> To: Discussion of precise time and frequency measurement
> > >> 	<time-nuts at febo.com>
> > >>
> > >> Joe
> > >>
> > >> Joe Gwinn wrote:
> > >>     
> > >>>  Bruce,
> > >>>
> > >>>  At 3:54 AM +0000 12/19/08, time-nuts-request at febo.com wrote:
> > >>>  
> > >>>       
> > >>>>  Message: 5
> > >>>>  Date: Fri, 19 Dec 2008 16:51:55 +1300
> > >>>>  From: Bruce Griffiths <bruce.griffiths at xtra.co.nz>
> > >>>>  Subject: Re: [time-nuts] Sub Pico Second Phase logger
> > >>>>  To: Discussion of precise time and frequency measurement
> > >>>> 	<time-nuts at febo.com>
> > >>>>
> > >>>>  Joe
> > >>>>
> > >>>>  Joe Gwinn wrote:
> > >>>>    
> > >>>>         
> > >>>>>   At 11:48 PM +0000 12/18/08, 
> time-nuts-request at febo.com wrote:
> > >>>>>           
> > >>  >>>
> > >> [snip]
> > >>
> > >>     
> > >>>  
> > >>>       
> > >>>>  Some claim to be able to sync to an SPDIF input but the
> > resultant
> > >>>> jitter  may be large.
> > >>>>    
> > >>>>         
> > >>>  Why large jitter?  Bad implementation?
> > >>>
> > >>>
> > >>>  
> > >>>       
> > >> I'm just suspicious, although I did see some data somewhere that
> > >> seemed to confirm my suspicions. The S/PDIF signal has to 
> > be a valid
> > >> SPDIF signal not just a square or sine wave clock.
> > >> Output sample rates (for the AP192) are then identical to
> > that of the
> > >> the S/PDIF source which is limited to
> > >> 192, 176.4, 96,88.2 48, 44.1 32 KSPS.
> > >>     
> > >
> > > I did a little looking.  I bet that the sync quite well, but this 
> > > signal is pretty complex.  One assumes that there is a box
> > that takes
> > > in a 10 MHz ref and does the rest, because the broadcast industry
> > > does use atomic clocks.
> > >
> > >
> > >   
> > Ulrich has built a circuit that takes a sampling frequency
> > input derived from a 10MHz GPSDO output and produces an 
> > S/PDIF output for this application. Its certainly worth 
> > trying since all the specs for the sound card aren't readily 
> > available.
> > >>  >
> > >>  >>  >>  >> A few divide and mix stages will be required 
> to achieve 
> > >> a spur free resolution of 10Hz.
> > >>  >>>>>>            
> > >>     
> > >>>>>>>    That is a traditional approach.  But are there alternate 
> > >>>>>>> approaches that
> > >>>>>>>               
> > >>  >>>>>   have now become practical?
> > >>  >>>>>
> > >>  >>>>  Diophantine frequency synthesis?
> > >>  >>>>        
> > >>     
> > >>>>>    From the sound of the name I think so, at least in
> > the last DDS
> > >>>>>   stage, as done by that patent.
> > >>>>>
> > >>>>>           
> > >>  >>>  But I was fishing.
> > >>  >>>      
> > >>     
> > >>>>  Conventional Diophantine synthesis uses number theory together
> > >>>> with 2 or  3 conventional synthesiser loops to achieve 
> very fine 
> > >>>> resolution whilst
> > >>>>         
> > >>  >> maintaining a high PLL phase detector input frequency.  >
> > >>     
> > >>>  In a sense, the concatenated DDS approach is a divide-and-mix
> > >>> chain.
> > >>>       
> > >>  > Perhaps there is a parallel here.
> > >>  >
> > >> The DDS based equivalent (of the dual PLL Diophantine
> > synthesiser) would
> > >> use a pair of DDS chips each replacing a conventional PLL in the 
> > >> Diophantine frequency synthesiser, the output frequency of
> > each having
> > >> zero phase truncation spurs.
> > >>
> > >> Both DDS clock sources should be spur free and have a
> > frequency ratio
> > >> that is a selected fixed rational fraction.
> > >>     
> > >
> > > A M/N PLL chip can arrange this.  I recall that Silicon 
> Labs makes 
> > > such a chip, which requires a parameter load on power-up, so a 
> > > computer or FPGA is needed.
> > >
> > >
> > >   
> > M and N only have to be relatively prime (ie the GCD of M and
> > N is 1). The ratio of M/N should also be close to 1. If the 
> > spacing of the phase truncation spur free output frequencies 
> > is about 10kHz (for either DDS) and M, N ~ 1000 the resultant 
> > mixer output frequencies would have a spacing of about 10Hz 
> > which may be adequate for this application.
> > 
> > >> A conventional mixer would then be used to either add or
> > subtract the
> > >> two DDS output frequencies. If the ratio of the 2 DDS 
> clock source
> > >> frequencies is appropriately chosen the spacing between 
> > the resultant
> > >> mixer output frequencies can be much finer than the
> > spacing between
> > >> the truncation spur free outputs of either DDS chip.
> > >> The DDS and mixer outputs should be filtered to remove
> > harmonics and
> > >> other unwanted frequencies.
> > >>     
> > >
> > > If the DDS chips are well chosen, we will get sin and cos 
> outputs, 
> > > and so can implement a dual-mixer phasing scheme to yield 
> only the 
> > > sum frequency or only the difference frequency, greatly
> > reducing the
> > > amount of filtering needed.  The better balanced the
> > channels are the
> > > better the cancellation of the unwanted term.  This is
> > basically the
> > > phasing method of single-sideband signal generation.
> > >
> > >
> > >   
> > >> One drawback is that selecting the output frequencies of 
> the 2 DDS
> > >> chips required to produce the desired output frequency 
> is somewhat 
> > >> complex. Since one almost certainly needs a computer of 
> > some sort to
> > >> set the DDS frequencies this shouldn't be a significant issue.
> > >>     
> > >
> > > Yes.  Basically, every digital chip in this scheme requires a 
> > > computer of some kind.  What I've seen used is a small CPLD
> > to do the
> > > initial parameter loads, and then to run the show.
> > >
> > > Joe
> > >
> > >   
> > Bruce
> > 
> > _______________________________________________
> > time-nuts mailing list -- time-nuts at febo.com
> > To unsubscribe, go to
> > https://www.febo.com/cgi-> bin/mailman/listinfo/time-nuts
> > and 
> > follow the instructions there.
> > 
> 
> 
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to 
> https://www.febo.com/cgi-> bin/mailman/listinfo/time-nuts
> and 
> follow the instructions there.
> 



From geoff at palaemon.demon.co.uk  Mon Dec 22 08:06:15 2008
From: geoff at palaemon.demon.co.uk (Geoff Blake)
Date: Mon, 22 Dec 2008 08:06:15 +0000 (GMT)
Subject: [time-nuts] time-nuts Digest, Vol 53, Issue 80
In-Reply-To: <mailman.598.1229911275.2499.time-nuts@febo.com>
References: <mailman.598.1229911275.2499.time-nuts@febo.com>
Message-ID: <Pine.LNX.4.58.0812220756500.5970@server.palaemon.co.uk>

> That's true this side of the herring pond as well...
>
> So, if you are caught on camera, you cannot say your speedo was telling
> you that you were under the speed limit.
>
> However, over here, you can still challenge the plods (UK term for
> Police Officers) to show that their measuring instruments were correctly
> callibrated on the day that they tracked you...
>
> If they did not keep to the law on this, then you were not lawfully
> shown to be over the limit.

Just for interest Dave, evidence from various types of speed
cameras has been successfully challenged by tachograph readings.
Presumeably the tachographs were of the more modern digital
variety.

G
-- 
  Geoff Blake  G8GNZ   located  near  Chelmsford,  Essex,  U.K.
  Please reply to:    geoff(at)palaemon(dot)demon(dot)co(dot)uk
  Using Linux on Intel & Linux or NetBSD on Sun Sparc platforms

  Please  avoid sending  me  Word  or  PowerPoint  attachments.
  See  <http://www.gnu.org/philosophy/no-word-attachments.html>
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From magnus at rubidium.dyndns.org  Mon Dec 22 10:57:03 2008
From: magnus at rubidium.dyndns.org (Magnus Danielson)
Date: Mon, 22 Dec 2008 11:57:03 +0100
Subject: [time-nuts] How good is my T-bolt...??
In-Reply-To: <494F0C36.3020009@comcast.net>
References: <C5744929.3AE9%James.P.Lux@jpl.nasa.gov>
	<494F0C36.3020009@comcast.net>
Message-ID: <494F727F.3060009@rubidium.dyndns.org>

Mike Naruta AA8K skrev:
> What if all three are different from each other?
> 
> Or, if two agree, how do you know that the
> two are not both wrong?
> 
> If you have 30 clocks and 20 say one time while
> 10 say another time, do you go with the majority?
> 
> Is there not a small probability that the 10 are correct?
> 
> 
> :)

Actually, you can't say that. If you have 20 clocks saying 12:05 and 10 
clocks saying 12:10 and you see the sun setting (assuming we are 
sufficiently distant from polar circles, which most people are most of 
the time), then clearly all 30 clocks are wrong. Statistics only 
indicate the mean value for your set of clocks, not which one of them is 
right. Your lack of external reference prohibits you from making such 
conclusions.

Cheers,
Magnus


From magnus at rubidium.dyndns.org  Mon Dec 22 11:29:39 2008
From: magnus at rubidium.dyndns.org (Magnus Danielson)
Date: Mon, 22 Dec 2008 12:29:39 +0100
Subject: [time-nuts] Solstice question, about 5000 years ago
In-Reply-To: <df3c5e400812212031k3c2d9a5aiedfd66fa1efc0da4@mail.gmail.com>
References: <0812212125.AA02184@ivan.Harhan.ORG>	<1231b6a80812211919g36e5d363k90d8ad994d99e540@mail.gmail.com>	<494F0DEF.5010903@xtra.co.nz>
	<494F1317.70100@xtra.co.nz>
	<df3c5e400812212031k3c2d9a5aiedfd66fa1efc0da4@mail.gmail.com>
Message-ID: <494F7A23.9020003@rubidium.dyndns.org>

Alan Biocca skrev:
> The sun is illuminating the floor 4 minutes after sunset?

I was similarly amazed. Now THAT cave I do want to see, cause it would 
be a wonder worth seeing. :)

Cheers,
Magnus


From didier at cox.net  Mon Dec 22 13:20:20 2008
From: didier at cox.net (Didier)
Date: Mon, 22 Dec 2008 07:20:20 -0600
Subject: [time-nuts] Jupiter modules: 1pps or 10kHz to lock an OCXO ?
In-Reply-To: <001301c963dd$b9b3a450$1801a8c0@BOBCEL1R7>
References: <969255.43432.qm@web58802.mail.re1.yahoo.com>
	<001301c963dd$b9b3a450$1801a8c0@BOBCEL1R7>
Message-ID: <15874976224C426DBF356A2C9BB82D97@didierhp>

If you are trying to have precise enough frequency for ham microwave
applications for instance (1E-9 would be 10 Hz at 10 GHz), the 10kHz output
of the Jupiter can be used to your advantage to phase lock a cheap VCXO with
a short time constant. A perfect example is the Jim Miller design which Tom
(and others) has tested and found to perform very well. A short time
constant is advantageous because it means the system will phase lock quickly
after power up, and many ham microwave stations are mobile and do not remain
powered all the time.

However, if you try to phase lock a relatively good OCXO like the HP 10811
or better (and achieve 1E-11 or better), any time constant faster than 20
minutes or so is likely to actually degrade the available performance of the
OCXO because the GPS signal has a lot of fluctuations in the short term due
to atmospheric perturbations and satellite position in the sky, refered to
as geometry, so a fast loop will force the otherwise stable OCXO to follow
the short term instability of the GPS signal, not what you want. With that
kind of time constant, it makes little difference if the phase detector
works at 10 kHz or 1Hz, aside from saving a few dividers. As it has been
pointed out, long time constants are better implemented in software, due to
the negative effect of large value resistors on noise.

Tom has a lot of very useful charts on his site www.leapsecond.com showing
the relative effects of GPS jitter and OCXO drift on overall stability.

Conclusions:

1) if you have a Jupiter and your needs are modest, use the 10kHz and an
analog loop, it will make your life easier (fewest parts), but depending on
the reference oscillator you use and the performance you try to achieve, do
not speed up the loop unnecessarily.

2) if you only need 1E-9 stability, the Jim Miller design is excellent and
so simple, anything else would be a waste.

3) if you need 1E-11 or better, you will need much more hardware, including
a good quality GPS receiver, antenna and OCXO and a microprocessor to
implement the loop filter, and probably some holdover algorithms,
essentially what you will find in a Fury, Z3801, Thunderbolt or Brandywine
integrated GPSDO.

4) if your needs are in between, you have a lot of room for experimentation.

Didier KO4BB

> -----Original Message-----
> From: time-nuts-bounces at febo.com 
> [mailto:time-nuts-bounces at febo.com] On Behalf Of Bob Q
> Sent: Sunday, December 21, 2008 8:34 PM
> To: Discussion of precise time and frequency measurement
> Subject: Re: [time-nuts] Jupiter modules: 1pps or 10kHz to 
> lock an OCXO ?
> 
> I thought of something else.  Time to lock can be really 
> long.  Say the OCXO can swing +/- 1 ppm, +/- 10 Hz at 10 MHz. 
>  The +/- 1 ppm also applies to 0.5 Hz.  To swing 180 degrees 
> at 0.5 Hz, assuming the low pass filtered control signal 
> pushes the OCXO the full 1 ppm, will take 1e6 seconds unless 
> you use a circuit similar to what I used to prealign 50 Hz 
> signals in the 100 Hz Motorola Oncore design.
> Bob Q.
> ----- Original Message -----
> From: "Patrick Reynaert" <preynaert at yahoo.com>
> To: "time-nuts" <time-nuts at febo.com>
> Sent: Sunday, December 21, 2008 2:13 PM
> Subject: [time-nuts] Jupiter modules: 1pps or 10kHz to lock an OCXO ?
> 
> 
> > Hello,
> >
> >
> > Using the 10kHz output to lock an OCXO is common practice 
> and seems to 
> > give good results.
> >
> > Has anyone tried to use the 1pps output? One? could first make a 
> > simple divider to create a 0.5Hz reference with 50% duty cycle, and 
> > then use this signal to lock an OCXO. This would also allow 
> the use of 
> > other OEM GPS modules that don't have the 10kHz but only 
> the 1pps signal.
> >
> > Of course, as the 0.5Hz signal is much lower in frequency 
> than 10kHz, 
> > the short-term stability is pushed more to the OCXO, making the 
> > requirements of the OCXO even harder.
> >
> > But maybe the 1pps signal has better stability than the 
> 10kHz signal? 
> > Or is this the same since these signals will only influence the 
> > long-term stability of the oscillator and have the same accuracy?
> >
> > Any thoughts are highly appreciated.
> >
> > Thanks,
> > Patrick.
> >
> >
> >
> >
> >
> > _______________________________________________
> > time-nuts mailing list -- time-nuts at febo.com To unsubscribe, go to 
> > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> > and follow the instructions there. 
> 
> 
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com To unsubscribe, 
> go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.



From didier at cox.net  Mon Dec 22 13:24:22 2008
From: didier at cox.net (Didier)
Date: Mon, 22 Dec 2008 07:24:22 -0600
Subject: [time-nuts] How good is my T-bolt...??
In-Reply-To: <C5744929.3AE9%James.P.Lux@jpl.nasa.gov>
References: <1231b6a80812211827g7f0d2b57i465372619dc27df@mail.gmail.com>
	<C5744929.3AE9%James.P.Lux@jpl.nasa.gov>
Message-ID: <A3668C69805E4B349D028D24B5424979@didierhp>

With two clocks, you don't know which is right. With three, you know for a
fact they are all wrong :-) 

Didier

> -----Original Message-----
> From: time-nuts-bounces at febo.com 
> [mailto:time-nuts-bounces at febo.com] On Behalf Of Lux, James P
> Sent: Sunday, December 21, 2008 9:28 PM
> To: Discussion of precise time and frequency measurement
> Subject: Re: [time-nuts] How good is my T-bolt...??
> 
> 
> The man who has two clocks never knows which one is right.  
> You need at least three.
> 



From cfharris at erols.com  Mon Dec 22 13:31:07 2008
From: cfharris at erols.com (Chuck Harris)
Date: Mon, 22 Dec 2008 08:31:07 -0500
Subject: [time-nuts] He is a Time-Nut Troublemaker....
In-Reply-To: <494F1DA4.4000106@xtra.co.nz>
References: <mailman.600.1229917104.2499.time-nuts@febo.com>	<BLU125-W46831CE6F2E119B7EEBE6CCEEF0@phx.gbl>
	<494F1DA4.4000106@xtra.co.nz>
Message-ID: <494F969B.1030604@erols.com>

Could you be more specific, and perhaps provide a reference?

Paul Mauser's group was pretty fussy about sighting through the
new barrels, and bending them a little here and there to make sure
their bores were perfectly straight.  The WWII records on the M1 Garand
talk of using a bore scope to adjust the adjustible iron sights.
The WWII records on the M1 Carbine talk of the same technique.

-Chuck Harris

Bruce Griffiths wrote:
> Mark Sims wrote:
>> I got to play with a custom .50 BMG that shoots meaningful groups at 1500 meters...  the maker's definition of
>> "meaningful group" is "smaller than your head".  I managed to put two rounds through pretty much the same hole.
>> Don't know where most of the other 18 rounds went...  Then there was his .17 cal varmint rifle.  Does wonders for
>> groundhoggies at 500 yards.  Most gawd awful recoil through.  I was black and blue for a month.  The barrel and all
>> the hardware in those guns is finished to optical tolerances and maintains it despite having just a little less
>> energy than a small nuke going off each time you fire.
>> 
>> 
> The fact that the direction in which the last 4" of the barrel largely determines the initial trajectory of the
> bullet (in absence of crosswind etc) was made use of to assist in alignment of the sights during mass production of
> infantry rifles during WWII.
> 
> Bruce
> 
> _______________________________________________ time-nuts mailing list -- time-nuts at febo.com To unsubscribe, go to
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
> 


From dave.g0dja at tiscali.co.uk  Mon Dec 22 13:55:42 2008
From: dave.g0dja at tiscali.co.uk (Dave Ackrill)
Date: Mon, 22 Dec 2008 13:55:42 +0000
Subject: [time-nuts] How good is my T-bolt...??
In-Reply-To: <A3668C69805E4B349D028D24B5424979@didierhp>
References: <1231b6a80812211827g7f0d2b57i465372619dc27df@mail.gmail.com>	<C5744929.3AE9%James.P.Lux@jpl.nasa.gov>
	<A3668C69805E4B349D028D24B5424979@didierhp>
Message-ID: <494F9C5E.2000503@tiscali.co.uk>

Didier wrote:
> With two clocks, you don't know which is right. With three, you know for a
> fact they are all wrong :-) 
>
> Didier
>   
I had a watch that I knew was correct twice a day...

Dave


From dave.g0dja at tiscali.co.uk  Mon Dec 22 13:57:35 2008
From: dave.g0dja at tiscali.co.uk (Dave Ackrill)
Date: Mon, 22 Dec 2008 13:57:35 +0000
Subject: [time-nuts] Trimble multi-way socket
In-Reply-To: <15874976224C426DBF356A2C9BB82D97@didierhp>
References: <969255.43432.qm@web58802.mail.re1.yahoo.com>	<001301c963dd$b9b3a450$1801a8c0@BOBCEL1R7>
	<15874976224C426DBF356A2C9BB82D97@didierhp>
Message-ID: <494F9CCF.3090404@tiscali.co.uk>

I have one of the circular Trimbel units, I think it might be a Jupiter?

Anyway, what I'm after is one of the multi-way plugs so that I can 
connect it up and start to use it.  Does anyone know of a source for 
these plugs please?

Thanks - Dave


From magnus at rubidium.dyndns.org  Mon Dec 22 14:22:01 2008
From: magnus at rubidium.dyndns.org (Magnus Danielson)
Date: Mon, 22 Dec 2008 15:22:01 +0100
Subject: [time-nuts] How good is my T-bolt...??
In-Reply-To: <494F9C5E.2000503@tiscali.co.uk>
References: <1231b6a80812211827g7f0d2b57i465372619dc27df@mail.gmail.com>	<C5744929.3AE9%James.P.Lux@jpl.nasa.gov>	<A3668C69805E4B349D028D24B5424979@didierhp>
	<494F9C5E.2000503@tiscali.co.uk>
Message-ID: <494FA289.6000407@rubidium.dyndns.org>

Dave Ackrill skrev:
> Didier wrote:
>> With two clocks, you don't know which is right. With three, you know for a
>> fact they are all wrong :-) 
>>
>> Didier
>>   
> I had a watch that I knew was correct twice a day...

The trouble with that arrangement is that you know at what time it will 
be correct, but it will not help you to know when it occurs.

Cheers,
Magnus


From chris.kuethe at gmail.com  Mon Dec 22 14:57:01 2008
From: chris.kuethe at gmail.com (Chris Kuethe)
Date: Mon, 22 Dec 2008 06:57:01 -0800
Subject: [time-nuts] parallel port PPS with FreeBSD
In-Reply-To: <200812220902.38925.besten@gmail.com>
References: <0812212125.AA02184@ivan.Harhan.ORG> <494F1317.70100@xtra.co.nz>
	<df3c5e400812212031k3c2d9a5aiedfd66fa1efc0da4@mail.gmail.com>
	<200812220902.38925.besten@gmail.com>
Message-ID: <91981b3e0812220657n27d02a48y5b0e2fabbd5434bc@mail.gmail.com>

dumb question, but is your printing system active? maybe lpd is
camping on the printer port?

On Mon, Dec 22, 2008 at 12:02 AM, Remco dB <besten at gmail.com> wrote:
> Perhaps this question may be totally off topic or considered to be part of
> the 'newbie category' but I tried to activate PPS on the parallel port (lpt0)
> with FreeBSD.
>
> By the way, the system runs fine with serial PPS but I want to compare the
> results of 'serial PPS' and 'parallel PPS' with my system.
>
> I made a symlink /dev/pps1, pointing towards /dev/lpt0.
>
> Using 127.127.22.1 in ntp.conf I get:
>
> 22 Dec 07:36:21 ntpd[633]: refclock_atom: /dev/pps1: Device busy
>
> I googled a little and changed the specs for the parallel port in my BIOS
> from 'ECP' to 'bi-directional', but the error remains.
>
> Any ideas what might be the issue here?
>
> Regards,
>
> Remco
>
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>



-- 
GDB has a 'break' feature; why doesn't it have 'fix' too?


From GandalfG8 at aol.com  Mon Dec 22 17:11:47 2008
From: GandalfG8 at aol.com (GandalfG8 at aol.com)
Date: Mon, 22 Dec 2008 12:11:47 EST
Subject: [time-nuts] Trimble multi-way socket
Message-ID: <d0d.45665ba8.36812453@aol.com>

 
In a message dated 22/12/2008 13:58:07 GMT Standard Time,  
dave.g0dja at tiscali.co.uk writes:

I have  one of the circular Trimbel units, I think it might be a  Jupiter?

Anyway, what I'm after is one of the multi-way plugs so that I  can 
connect it up and start to use it.  Does anyone know of a source  for 
these plugs please?



---------------
Hi Dave
 
Take a look here for connector info and a manual for the Palisade unit,  plus 
other interesting info....
 
_http://www.dc2light.pwp.blueyonder.co.uk/Webpage/GPS_ref.htm_ 
(http://www.dc2light.pwp.blueyonder.co.uk/Webpage/GPS_ref.htm) 
 
regards
 
Nigel
GM8PZR

From joegwinn at comcast.net  Mon Dec 22 17:44:53 2008
From: joegwinn at comcast.net (Joe Gwinn)
Date: Mon, 22 Dec 2008 12:44:53 -0500
Subject: [time-nuts] Sub Pico Second Phase logger
Message-ID: <p06240807c57581b3217e@[192.168.1.212]>

Ulrich,

At 7:57 AM +0000 12/22/08, time-nuts-request at febo.com wrote:
>
>Message: 7
>Date: Mon, 22 Dec 2008 08:56:55 +0100
>From: "Ulrich Bangert" <df6jb at ulrich-bangert.de>
>Subject: Re: [time-nuts] Sub Pico Second Phase logger
>To: "'Discussion of precise time and frequency measurement'"
>	<time-nuts at febo.com>
>
>Joe and Bruce,
>
>>  Ulrich has built a circuit that takes a sampling frequency
>>  input derived from a 10MHz GPSDO output and produces an
>>  S/PDIF output for this application. Its certainly worth
>>  trying since all the specs for the sound card aren't readily
>>  available.
>
>I use a cheap and easy to use CRYSTAL CS8402 S/PDIF transmitter to
>generate the S/PDIF signal for the sound card. Data input just tight to
>ground. The balanced output is done with a Minicircuits T1-1T
>transformer. The chip needs an 12.844 MHz clock for 96 kHz sample rate
>and 6.144 MHz for 48 kHz sample rate. However, these two frequencies are
>generated by an old HP3330 locked to 10 MHz in my case. If the circuit
>had to be designed new I would have used a ANALOG DEVICES dds circuit
>with a built in clock multiplier.

Thanks for the pointer.  I'll look at the datasheet of the CS8406, 
which replaces the CS8402.

<http://www.cirrus.com/en/products/pro/detail/P1009.html>

Joe


From joegwinn at comcast.net  Mon Dec 22 18:16:24 2008
From: joegwinn at comcast.net (Joe Gwinn)
Date: Mon, 22 Dec 2008 13:16:24 -0500
Subject: [time-nuts] Sub Pico Second Phase logger
Message-ID: <p06240808c57582fb6e67@[192.168.1.212]>

At 2:01 AM +0000 12/22/08, time-nuts-request at febo.com wrote:
>
>Message: 4
>Date: Mon, 22 Dec 2008 11:19:06 +1300
>From: Bruce Griffiths <bruce.griffiths at xtra.co.nz>
>Subject: Re: [time-nuts] Sub Pico Second Phase logger
>To: Discussion of precise time and frequency measurement
>	<time-nuts at febo.com>
>
>Joe
>
>Joe Gwinn wrote:
>  > Bruce,
>>
>  >>
>
>[snip]
>>>
>>>    
>>>> 
>>>>      
>>>>>   Some claim to be able to sync to an SPDIF input but the resultant jitter
>>>>>   may be large.
>>>>>   
>>>>>        
>>>>   Why large jitter?  Bad implementation?
>>>>
>>>>
>>>> 
>>>>      
>>>  I'm just suspicious, although I did see some data somewhere that seemed
>>>  to confirm my suspicions.
>>>  The S/PDIF signal has to be a valid SPDIF signal not just a square or
>>>  sine wave clock.
>>>  Output sample rates (for the AP192) are then identical to that of the
>>>  the S/PDIF source which is limited to
>>>  192, 176.4, 96,88.2 48, 44.1 32 KSPS.
>>>    
>>
>>  I did a little looking.  I bet that the sync quite well, but this
>>  signal is pretty complex.  One assumes that there is a box that takes
>  > in a 10 MHz ref and does the rest, because the broadcast industry
>>  does use atomic clocks.
>>
>>
>>  
>Ulrich has built a circuit that takes a sampling frequency input derived
>from a 10MHz GPSDO output and produces an S/PDIF output for this
>application.
>Its certainly worth trying since all the specs for the sound card aren't
>readily available.

Ulrich posted some details, and I got the datasheet for study.

But I bet someone already makes the necessary box.


>  >>>>  Conventional Diophantine synthesis uses number theory 
>together with 2 or
>>>>>   3 conventional synthesiser loops to achieve very fine resolution whilst
>>>>>        
>>>   >> maintaining a high PLL phase detector input frequency.
>>>   >
>>>    
>>>>   In a sense, the concatenated DDS approach is a divide-and-mix chain.
>>>>      
>>>   > Perhaps there is a parallel here.
>>>   > 
>>>  The DDS based equivalent (of the dual PLL Diophantine synthesiser) would
>>>  use a pair of DDS chips each replacing a conventional PLL in the
>>>  Diophantine frequency synthesiser, the output frequency of each having
>>>  zero phase truncation spurs.
>>>
>>>  Both DDS clock sources should be spur free and have a frequency ratio
>>>  that is a selected fixed rational fraction.
>>>    
>>
>>  A M/N PLL chip can arrange this.  I recall that Silicon Labs makes
>>  such a chip, which requires a parameter load on power-up, so a
>  > computer or FPGA is needed.

<https://www.silabs.com/products/clocksoscillators/clocks/Pages/default.aspx>

Also of interest:

<https://www.silabs.com/products/clocksoscillators/clocks/Pages/Any-RateJitterAttenuatingClockMultipliers.aspx>


>M and N only have to be relatively prime (ie the GCD of M and N is 1).
>The ratio of M/N should also be close to 1.
>If the spacing of the phase truncation spur free output frequencies is
>about 10kHz (for either DDS) and M, N ~ 1000 the resultant mixer output
>frequencies would have a spacing of about 10Hz which may be adequate for
>this application.

I found and read the basic articles, which can be downloaded from 
Prof Sotiriadis' website:

<http://www.ece.jhu.edu/~pps/WEB/Publications/pub.html>

Items J10, J13, and J15 seem particularly relevant.

All one needs is the M/N chip, although one can certainly use DDS chips.


>  >> A conventional mixer would then be used to either add or subtract the
>>>  two DDS output frequencies.
>>>  If the ratio of the 2 DDS clock source frequencies is appropriately
>>>  chosen the spacing between the resultant mixer output frequencies can be
>>>  much finer than the spacing between the truncation spur free outputs of
>>>  either DDS chip.
>>>  The DDS and mixer outputs should be filtered to remove harmonics and
>>>  other unwanted frequencies.
>>>    
>>
>>  If the DDS chips are well chosen, we will get sin and cos outputs,
>>  and so can implement a dual-mixer phasing scheme to yield only the
>>  sum frequency or only the difference frequency, greatly reducing the
>>  amount of filtering needed.  The better balanced the channels are the
>  > better the cancellation of the unwanted term.  This is basically the
>  > phasing method of single-sideband signal generation.

This would be a reason to use DDS chips instead of M/N PLL chips, 
unless there are M/N PLL chips that provide quadrature outputs. 
SiLabs Si5338 may suffice, as it allows one to control the relative 
phase of its outputs.


Joe


From w1ksz at earthlink.net  Mon Dec 22 18:24:43 2008
From: w1ksz at earthlink.net (Richard W. Solomon)
Date: Mon, 22 Dec 2008 11:24:43 -0700 (GMT-07:00)
Subject: [time-nuts] LORAL FS-9256 Oscillator
Message-ID: <29573751.1229970284152.JavaMail.root@mswamui-thinleaf.atl.sa.earthlink.net>

I just snagged a couple of these. Thought they might be fun to play with.
Before I re-invent the wheel, does anyone have any info on these ?
Anything at all ... .
I thought maybe I could lock one up to my GPSDO, thereby getting some
useful outputs.

Thanks, Dick, W1KSZ


From bruce.griffiths at xtra.co.nz  Mon Dec 22 19:36:57 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Tue, 23 Dec 2008 08:36:57 +1300
Subject: [time-nuts] He is a Time-Nut Troublemaker....
In-Reply-To: <494F969B.1030604@erols.com>
References: <mailman.600.1229917104.2499.time-nuts@febo.com>	<BLU125-W46831CE6F2E119B7EEBE6CCEEF0@phx.gbl>	<494F1DA4.4000106@xtra.co.nz>
	<494F969B.1030604@erols.com>
Message-ID: <494FEC59.90905@xtra.co.nz>

Chuck

It was a paper written around 1942 detailing the procedures used to
align the sights of mass produced rifles for which it was impractical to
have each rifle individually adjusted on a firing range.
Unfortunately I dont think I have a copy of this any longer, however
I'll keep an eye out for it.
The alignment jig used a mirror attached to a cylindrical plug that was
a close slip fit into the end of the bore.
It wasn't perfect but far better than not adjusting the sights at all.

Bruce


Chuck Harris wrote:
> Could you be more specific, and perhaps provide a reference?
>
> Paul Mauser's group was pretty fussy about sighting through the
> new barrels, and bending them a little here and there to make sure
> their bores were perfectly straight.  The WWII records on the M1 Garand
> talk of using a bore scope to adjust the adjustible iron sights.
> The WWII records on the M1 Carbine talk of the same technique.
>
> -Chuck Harris
>
> Bruce Griffiths wrote:
>   
>> Mark Sims wrote:
>>     
>>> I got to play with a custom .50 BMG that shoots meaningful groups at 1500 meters...  the maker's definition of
>>> "meaningful group" is "smaller than your head".  I managed to put two rounds through pretty much the same hole.
>>> Don't know where most of the other 18 rounds went...  Then there was his .17 cal varmint rifle.  Does wonders for
>>> groundhoggies at 500 yards.  Most gawd awful recoil through.  I was black and blue for a month.  The barrel and all
>>> the hardware in those guns is finished to optical tolerances and maintains it despite having just a little less
>>> energy than a small nuke going off each time you fire.
>>>
>>>
>>>       
>> The fact that the direction in which the last 4" of the barrel largely determines the initial trajectory of the
>> bullet (in absence of crosswind etc) was made use of to assist in alignment of the sights during mass production of
>> infantry rifles during WWII.
>>
>> Bruce
>>
>>     
>



From bruce.griffiths at xtra.co.nz  Mon Dec 22 19:55:36 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Tue, 23 Dec 2008 08:55:36 +1300
Subject: [time-nuts] He is a Time-Nut Troublemaker....
In-Reply-To: <494FEC59.90905@xtra.co.nz>
References: <mailman.600.1229917104.2499.time-nuts@febo.com>	<BLU125-W46831CE6F2E119B7EEBE6CCEEF0@phx.gbl>	<494F1DA4.4000106@xtra.co.nz>	<494F969B.1030604@erols.com>
	<494FEC59.90905@xtra.co.nz>
Message-ID: <494FF0B8.4030809@xtra.co.nz>

If I recall correctly, the article was published in the Journal of the
Optical Society of America around that time or perhaps a little later.

Bruce Griffiths wrote:
> Chuck
>
> It was a paper written around 1942 detailing the procedures used to
> align the sights of mass produced rifles for which it was impractical to
> have each rifle individually adjusted on a firing range.
> Unfortunately I dont think I have a copy of this any longer, however
> I'll keep an eye out for it.
> The alignment jig used a mirror attached to a cylindrical plug that was
> a close slip fit into the end of the bore.
> It wasn't perfect but far better than not adjusting the sights at all.
>
> Bruce
>
>
> Chuck Harris wrote:
>   
>> Could you be more specific, and perhaps provide a reference?
>>
>> Paul Mauser's group was pretty fussy about sighting through the
>> new barrels, and bending them a little here and there to make sure
>> their bores were perfectly straight.  The WWII records on the M1 Garand
>> talk of using a bore scope to adjust the adjustible iron sights.
>> The WWII records on the M1 Carbine talk of the same technique.
>>
>> -Chuck Harris
>>
>> Bruce Griffiths wrote:
>>   
>>     
>>> Mark Sims wrote:
>>>     
>>>       
>>>> I got to play with a custom .50 BMG that shoots meaningful groups at 1500 meters...  the maker's definition of
>>>> "meaningful group" is "smaller than your head".  I managed to put two rounds through pretty much the same hole.
>>>> Don't know where most of the other 18 rounds went...  Then there was his .17 cal varmint rifle.  Does wonders for
>>>> groundhoggies at 500 yards.  Most gawd awful recoil through.  I was black and blue for a month.  The barrel and all
>>>> the hardware in those guns is finished to optical tolerances and maintains it despite having just a little less
>>>> energy than a small nuke going off each time you fire.
>>>>
>>>>
>>>>       
>>>>         
>>> The fact that the direction in which the last 4" of the barrel largely determines the initial trajectory of the
>>> bullet (in absence of crosswind etc) was made use of to assist in alignment of the sights during mass production of
>>> infantry rifles during WWII.
>>>
>>> Bruce
>>>
>>>     
>>>       
>
>
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>
>   



From bruce.griffiths at xtra.co.nz  Mon Dec 22 20:25:27 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Tue, 23 Dec 2008 09:25:27 +1300
Subject: [time-nuts] He is a Time-Nut Troublemaker....
In-Reply-To: <494FF0B8.4030809@xtra.co.nz>
References: <mailman.600.1229917104.2499.time-nuts@febo.com>	<BLU125-W46831CE6F2E119B7EEBE6CCEEF0@phx.gbl>	<494F1DA4.4000106@xtra.co.nz>	<494F969B.1030604@erols.com>	<494FEC59.90905@xtra.co.nz>
	<494FF0B8.4030809@xtra.co.nz>
Message-ID: <494FF7B7.2020403@xtra.co.nz>

I've remembered that I was originally looking for DD Maksutov's article
on his catadioptric telescope published in 1944.
Consequently I had a look at the contents of JOSA for 1944 and I believe
the actual article in question is:

An Optical Sighting Gauge for the Garand Rifle C. B. SITTERSON and JR.
and NORMAN F. BARNES, JOSA, Vol. 34, Iss. 3, pp. *126?126* (1944):
http://www.opticsinfobase.org/josa/issue.cfm?volume=34&issue=3
<http://www.opticsinfobase.org/josa/issue.cfm?volume=34&issue=3>

It was probably intended more as an acceptance test by the army.

Bruce


Bruce Griffiths wrote:
> If I recall correctly, the article was published in the Journal of the
> Optical Society of America around that time or perhaps a little later.
>
> Bruce Griffiths wrote:
>   
>> Chuck
>>
>> It was a paper written around 1942 detailing the procedures used to
>> align the sights of mass produced rifles for which it was impractical to
>> have each rifle individually adjusted on a firing range.
>> Unfortunately I dont think I have a copy of this any longer, however
>> I'll keep an eye out for it.
>> The alignment jig used a mirror attached to a cylindrical plug that was
>> a close slip fit into the end of the bore.
>> It wasn't perfect but far better than not adjusting the sights at all.
>>
>> Bruce
>>
>>
>> Chuck Harris wrote:
>>   
>>     
>>> Could you be more specific, and perhaps provide a reference?
>>>
>>> Paul Mauser's group was pretty fussy about sighting through the
>>> new barrels, and bending them a little here and there to make sure
>>> their bores were perfectly straight.  The WWII records on the M1 Garand
>>> talk of using a bore scope to adjust the adjustible iron sights.
>>> The WWII records on the M1 Carbine talk of the same technique.
>>>
>>> -Chuck Harris
>>>
>>> Bruce Griffiths wrote:
>>>   
>>>     
>>>       
>>>> Mark Sims wrote:
>>>>     
>>>>       
>>>>         
>>>>> I got to play with a custom .50 BMG that shoots meaningful groups at 1500 meters...  the maker's definition of
>>>>> "meaningful group" is "smaller than your head".  I managed to put two rounds through pretty much the same hole.
>>>>> Don't know where most of the other 18 rounds went...  Then there was his .17 cal varmint rifle.  Does wonders for
>>>>> groundhoggies at 500 yards.  Most gawd awful recoil through.  I was black and blue for a month.  The barrel and all
>>>>> the hardware in those guns is finished to optical tolerances and maintains it despite having just a little less
>>>>> energy than a small nuke going off each time you fire.
>>>>>
>>>>>
>>>>>       
>>>>>         
>>>>>           
>>>> The fact that the direction in which the last 4" of the barrel largely determines the initial trajectory of the
>>>> bullet (in absence of crosswind etc) was made use of to assist in alignment of the sights during mass production of
>>>> infantry rifles during WWII.
>>>>
>>>> Bruce
>>>>
>>>>     
>>>>       
>>>>         
>> _______________________________________________
>> time-nuts mailing list -- time-nuts at febo.com
>> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>> and follow the instructions there.
>>
>>   
>>     
>
>
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>
>   



From cfharris at erols.com  Mon Dec 22 21:04:37 2008
From: cfharris at erols.com (Chuck Harris)
Date: Mon, 22 Dec 2008 16:04:37 -0500
Subject: [time-nuts] He is a Time-Nut Troublemaker....
In-Reply-To: <494FF7B7.2020403@xtra.co.nz>
References: <mailman.600.1229917104.2499.time-nuts@febo.com>	<BLU125-W46831CE6F2E119B7EEBE6CCEEF0@phx.gbl>	<494F1DA4.4000106@xtra.co.nz>	<494F969B.1030604@erols.com>	<494FEC59.90905@xtra.co.nz>	<494FF0B8.4030809@xtra.co.nz>
	<494FF7B7.2020403@xtra.co.nz>
Message-ID: <495000E5.7090500@erols.com>

Hi Bruce,

Thanks for the reference.

Bore sights are a system that I use, and I find they work very well.

Some how I misread your initial post in a way that lead me to believe
that you were saying the barrel was being bent to adjust it to target.

Upon re-reading your post, I cannot for the life of me figure out how
I could have gotten that impression from what you wrote... Sorry!

-Chuck Harris

Bruce Griffiths wrote:
> I've remembered that I was originally looking for DD Maksutov's article
> on his catadioptric telescope published in 1944.
> Consequently I had a look at the contents of JOSA for 1944 and I believe
> the actual article in question is:
> 
> An Optical Sighting Gauge for the Garand Rifle C. B. SITTERSON and JR.
> and NORMAN F. BARNES, JOSA, Vol. 34, Iss. 3, pp. *126?126* (1944):
> http://www.opticsinfobase.org/josa/issue.cfm?volume=34&issue=3
> <http://www.opticsinfobase.org/josa/issue.cfm?volume=34&issue=3>
> 
> It was probably intended more as an acceptance test by the army.
> 
> Bruce
> 
> 
> Bruce Griffiths wrote:
>> If I recall correctly, the article was published in the Journal of the
>> Optical Society of America around that time or perhaps a little later.
>>
>> Bruce Griffiths wrote:
>>   


From bruce.griffiths at xtra.co.nz  Mon Dec 22 21:08:35 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Tue, 23 Dec 2008 10:08:35 +1300
Subject: [time-nuts] Sub Pico Second Phase logger
In-Reply-To: <p06240808c57582fb6e67@[192.168.1.212]>
References: <p06240808c57582fb6e67@[192.168.1.212]>
Message-ID: <495001D3.6010200@xtra.co.nz>

Joe
Joe Gwinn wrote:
> At 2:01 AM +0000 12/22/08, time-nuts-request at febo.com wrote:
>   
>> Message: 4
>> Date: Mon, 22 Dec 2008 11:19:06 +1300
>> From: Bruce Griffiths <bruce.griffiths at xtra.co.nz>
>> Subject: Re: [time-nuts] Sub Pico Second Phase logger
>> To: Discussion of precise time and frequency measurement
>> 	<time-nuts at febo.com>
>>
>> Joe
>>
>> Joe Gwinn wrote:
>>  > Bruce,
>>     
>>  >>
>>
>> [snip]
>>     
>>>>    
>>>>         
>>>>>      
>>>>>           
>>>>>>   Some claim to be able to sync to an SPDIF input but the resultant jitter
>>>>>>   may be large.
>>>>>>   
>>>>>>        
>>>>>>             
>>>>>   Why large jitter?  Bad implementation?
>>>>>
>>>>>
>>>>>
>>>>>      
>>>>>           
>>>>  I'm just suspicious, although I did see some data somewhere that seemed
>>>>  to confirm my suspicions.
>>>>  The S/PDIF signal has to be a valid SPDIF signal not just a square or
>>>>  sine wave clock.
>>>>  Output sample rates (for the AP192) are then identical to that of the
>>>>  the S/PDIF source which is limited to
>>>>  192, 176.4, 96,88.2 48, 44.1 32 KSPS.
>>>>    
>>>>         
>>>  I did a little looking.  I bet that the sync quite well, but this
>>>  signal is pretty complex.  One assumes that there is a box that takes
>>>       
>>  > in a 10 MHz ref and does the rest, because the broadcast industry
>>     
>>>  does use atomic clocks.
>>>
>>>
>>>  
>>>       
>> Ulrich has built a circuit that takes a sampling frequency input derived
>>     
> >from a 10MHz GPSDO output and produces an S/PDIF output for this
>   
>> application.
>> Its certainly worth trying since all the specs for the sound card aren't
>> readily available.
>>     
>
> Ulrich posted some details, and I got the datasheet for study.
>
> But I bet someone already makes the necessary box.
>
>
>   
>>  >>>>  Conventional Diophantine synthesis uses number theory 
>> together with 2 or
>>     
>>>>>>   3 conventional synthesiser loops to achieve very fine resolution whilst
>>>>>>        
>>>>>>             
>>>>   >> maintaining a high PLL phase detector input frequency.
>>>>   >
>>>>    
>>>>         
>>>>>   In a sense, the concatenated DDS approach is a divide-and-mix chain.
>>>>>      
>>>>>           
>>>>   > Perhaps there is a parallel here.
>>>>   > 
>>>>  The DDS based equivalent (of the dual PLL Diophantine synthesiser) would
>>>>  use a pair of DDS chips each replacing a conventional PLL in the
>>>>  Diophantine frequency synthesiser, the output frequency of each having
>>>>  zero phase truncation spurs.
>>>>
>>>>  Both DDS clock sources should be spur free and have a frequency ratio
>>>>  that is a selected fixed rational fraction.
>>>>    
>>>>         
>>>  A M/N PLL chip can arrange this.  I recall that Silicon Labs makes
>>>  such a chip, which requires a parameter load on power-up, so a
>>>       
>>  > computer or FPGA is needed.
>>     
>
> <https://www.silabs.com/products/clocksoscillators/clocks/Pages/default.aspx>
>
> Also of interest:
>
> <https://www.silabs.com/products/clocksoscillators/clocks/Pages/Any-RateJitterAttenuatingClockMultipliers.aspx>
>
>
>   
The close in phase noise of these devices appears to be very high.
This may preclude their use in a system that just uses 2 of them directly.
However in the high resolution version where the output frequencies of
the 2 M/N synthesisers are each divided by a large factor before being
added and subtracted from the reference (10MHz ??) frequency the
resultant close in phase noise will be much lower.
Control of the close in spur levels produced by the NCO may also be an
issue.
>> M and N only have to be relatively prime (ie the GCD of M and N is 1).
>> The ratio of M/N should also be close to 1.
>> If the spacing of the phase truncation spur free output frequencies is
>> about 10kHz (for either DDS) and M, N ~ 1000 the resultant mixer output
>> frequencies would have a spacing of about 10Hz which may be adequate for
>> this application.
>>     
>
> I found and read the basic articles, which can be downloaded from 
> Prof Sotiriadis' website:
>
> <http://www.ece.jhu.edu/~pps/WEB/Publications/pub.html>
>
>   
There is also US patent 5267182.

> Items J10, J13, and J15 seem particularly relevant.
>
> All one needs is the M/N chip, although one can certainly use DDS chips.
>
>
>   
Using a DDS avoids the requirement for a pair of low phase noise VCOs.

>>  >> A conventional mixer would then be used to either add or subtract the
>>     
>>>>  two DDS output frequencies.
>>>>  If the ratio of the 2 DDS clock source frequencies is appropriately
>>>>  chosen the spacing between the resultant mixer output frequencies can be
>>>>  much finer than the spacing between the truncation spur free outputs of
>>>>  either DDS chip.
>>>>  The DDS and mixer outputs should be filtered to remove harmonics and
>>>>  other unwanted frequencies.
>>>>    
>>>>         
>>>  If the DDS chips are well chosen, we will get sin and cos outputs,
>>>  and so can implement a dual-mixer phasing scheme to yield only the
>>>  sum frequency or only the difference frequency, greatly reducing the
>>>  amount of filtering needed.  The better balanced the channels are the
>>>       
>>  > better the cancellation of the unwanted term.  This is basically the
>>  > phasing method of single-sideband signal generation.
>>     
>
> This would be a reason to use DDS chips instead of M/N PLL chips, 
> unless there are M/N PLL chips that provide quadrature outputs. 
> SiLabs Si5338 may suffice, as it allows one to control the relative 
> phase of its outputs.
>
>
>   
If one were to divide the output frequency of the diophantine
synthesizer by 4 using a 2 bit Johnson counter then quadrature phase
outputs are available.
However the filters used to extract the fundamental from the divider
outputs would need to be matched.
If the diophantine frequency synthesiser output frequency doesn't vary
too much one can always use a quadrature hybrid.
> Joe
>
>   

Bruce


From joegwinn at comcast.net  Mon Dec 22 22:07:30 2008
From: joegwinn at comcast.net (Joe Gwinn)
Date: Mon, 22 Dec 2008 17:07:30 -0500
Subject: [time-nuts] Sub Pico Second Phase logger
Message-ID: <p0624080bc575badb86f8@[192.168.1.212]>

Bruce,

At 9:08 PM +0000 12/22/08, time-nuts-request at febo.com wrote:
>
>Date: Tue, 23 Dec 2008 10:08:35 +1300
>From: Bruce Griffiths <bruce.griffiths at xtra.co.nz>
>Subject: Re: [time-nuts] Sub Pico Second Phase logger
>To: Discussion of precise time and frequency measurement
>	<time-nuts at febo.com>
>
>Joe
>Joe Gwinn wrote:
>>  At 2:01 AM +0000 12/22/08, time-nuts-request at febo.com wrote:
>>  
>>>  Message: 4
>>>  Date: Mon, 22 Dec 2008 11:19:06 +1300
>>>  From: Bruce Griffiths <bruce.griffiths at xtra.co.nz>
>>>  Subject: Re: [time-nuts] Sub Pico Second Phase logger
>>>  To: Discussion of precise time and frequency measurement
>>>	<time-nuts at febo.com>
>>>
>>>  Joe
>>>
>>>  Joe Gwinn wrote:
>>>   > Bruce,
>>>    
>>>   >>
>>>
>  >> [snip]
>
>  >
>  >>>>  [BG]  The DDS based equivalent (of the dual PLL Diophantine 
>synthesiser) would
>>>>>   use a pair of DDS chips each replacing a conventional PLL in the
>>>>>   Diophantine frequency synthesiser, the output frequency of each having
>  >>>>  zero phase truncation spurs.
>>>>>
>>>>>   Both DDS clock sources should be spur free and have a frequency ratio
>>>>>   that is a selected fixed rational fraction.
>>>>>   
>>>>>        
>>>>   [JG]  A M/N PLL chip can arrange this.  I recall that Silicon Labs makes
>  >>>  such a chip, which requires a parameter load on power-up, so a
>  >>> computer or FPGA is needed.
>  >>    
>>
>  > 
><https://www.silabs.com/products/clocksoscillators/clocks/Pages/default.aspx>
>>
>>  Also of interest:
>>
>> 
>><https://www.silabs.com/products/clocksoscillators/clocks/Pages/Any-RateJitterAttenuatingClockMultipliers.aspx>
>>
>>
>>  
>The close in phase noise of these devices appears to be very high.
>This may preclude their use in a system that just uses 2 of them directly.

The SiLabs "Precision" units claim very low jitter (and thus low 
phase noise).  The above "jitter-attenuating" units are in this 
group.  I see that the spec numbers are still TBD though.

There may be other makers; this is a very competitive area.  I got 
the source from a RF engineer at work.

By the way, when we first used one of the simple PLL chips, we had 
failures.  It turned out that one had to bake the chips (to drive 
moisture off) longer than the original instructions said, and some of 
the chips cracked during soldering.  The new instructions eliminated 
the problem.

I suppose that all single-IC solutions will have worse phase noise 
than a well-engineered discrete unit, simply because it's hard to 
prevent undesired leakage of signals between parts of the the IC. 
However, the ICs may still be more than adequate, and are a whole lot 
easier than rolling our own discrete units.


>However in the high resolution version where the output frequencies of
>the 2 M/N synthesisers are each divided by a large factor before being
>added and subtracted from the reference (10MHz ??) frequency the
>resultant close in phase noise will be much lower.

And can be combined with use of the precision units.


>Control of the close in spur levels produced by the NCO may also be an
>issue.

If the division ratio is an integer, the spurs are reduced.

Analog Devices has a web calculator that's useful for fast 
exploration.  The calculator operation is explained and the reference 
provided in their big tutorial on DDS principles.


>  >> M and N only have to be relatively prime (ie the GCD of M and N is 1).
>>>  The ratio of M/N should also be close to 1.
>>>  If the spacing of the phase truncation spur free output frequencies is
>>>  about 10kHz (for either DDS) and M, N ~ 1000 the resultant mixer output
>>>  frequencies would have a spacing of about 10Hz which may be adequate for
>>>  this application.
>>>    
>>
>>  I found and read the basic articles, which can be downloaded from
>  > Prof Sotiriadis' website:
>>
>>  <http://www.ece.jhu.edu/~pps/WEB/Publications/pub.html>
>>
>>
>There is also US patent 5267182.

I did find 5,267,182 while searching for Sotiriadis' patent, but 
forgot to mention it.  Don't know what the difference is.  In the US, 
patent applications are made public after 18 months, or immediately 
if the person is also applying for a European patent.  The US Patent 
Office is years behind, so patent issuance may be a while.


>  > Items J10, J13, and J15 seem particularly relevant.
>  >
>>  All one needs is the M/N chip, although one can certainly use DDS chips.
>>
>>
>>
>Using a DDS avoids the requirement for a pair of low phase noise VCOs.

If we can control the spurs, many DDS chips are very good.


>  >>  >> A conventional mixer would then be used to either add or subtract the
>>>    
>>>>>   two DDS output frequencies.
>>>>>   If the ratio of the 2 DDS clock source frequencies is appropriately
>>>>>   chosen the spacing between the resultant mixer output frequencies can be
>>>>>   much finer than the spacing between the truncation spur free outputs of
>>>>>   either DDS chip.
>>>>>   The DDS and mixer outputs should be filtered to remove harmonics and
>>>>>   other unwanted frequencies.
>>>>>   
>>>>>        
>>>>   If the DDS chips are well chosen, we will get sin and cos outputs,
>>>>   and so can implement a dual-mixer phasing scheme to yield only the
>>>>   sum frequency or only the difference frequency, greatly reducing the
>>>>   amount of filtering needed.  The better balanced the channels are the
>>>>      
>>>   > better the cancellation of the unwanted term.  This is basically the
>>>   > phasing method of single-sideband signal generation.
>>>    
>>
>>  This would be a reason to use DDS chips instead of M/N PLL chips,
>>  unless there are M/N PLL chips that provide quadrature outputs.
>>  SiLabs Si5338 may suffice, as it allows one to control the relative
>>  phase of its outputs.
>>
>>
>>  
>If one were to divide the output frequency of the diophantine
>synthesizer by 4 using a 2 bit Johnson counter then quadrature phase
>outputs are available.
>However the filters used to extract the fundamental from the divider
>outputs would need to be matched.
>If the diophantine frequency synthesiser output frequency doesn't vary
>too much one can always use a quadrature hybrid.

This seems like a lot of work.  Hmm.  Now that I think of it, the 
SiLabs chips emit square waves (logic signals), not sine waves.  Back 
to DDS chips, it seems.

Joe


From jdb at lartmaker.nl  Mon Dec 22 22:08:16 2008
From: jdb at lartmaker.nl (J.D. Bakker)
Date: Mon, 22 Dec 2008 23:08:16 +0100
Subject: [time-nuts] Sub Pico Second Phase logger
In-Reply-To: <494EC0DA.2010601@xtra.co.nz>
References: <p06240800c5743311b2a3@[192.168.1.212]>
	<494EC0DA.2010601@xtra.co.nz>
Message-ID: <p06240573c575bd3c67b6@[10.1.5.33]>

At 11:19 +1300 22-12-2008, Bruce Griffiths wrote:
>Ulrich has built a circuit that takes a sampling frequency input derived
>from a 10MHz GPSDO output and produces an S/PDIF output for this
>application.

Most common S/PDIF receiver chips have >100ps jitter. Lower jitter 
implementations are available (PLL/VCXO, usually), but only in 
higher-end equipment.

http://www.sm5bsz.com/linuxdsp/hware/delta44.htm describes a 
modification to a common sound card to lower its noise level; 
http://www.sm5bsz.com/linuxdsp/linrad.htm has software that may be 
useful for phase measurement.

As mentioned earlier, for best noise/jitter-performance an external 
ADC should be used, connected through a digital link to a PC sound 
card. One could do a lot worse than the TI PCM4222 eval board 
(http://focus.ti.com/docs/prod/folders/print/pcm4222.html), which 
accepts an external clock if so desired. At $149 (plus a tenner or 
two for the sound card) this will likely be much cheaper than an 
equivalent FireWire-device.

JDB.
[more on S/PDIF sync in AES standards AES11 (sync) and AES3 (serial 
bitstream format)]
-- 
LART. 250 MIPS under one Watt. Free hardware design files.
http://www.lartmaker.nl/


From bruce.griffiths at xtra.co.nz  Mon Dec 22 23:01:40 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Tue, 23 Dec 2008 12:01:40 +1300
Subject: [time-nuts] Sub Pico Second Phase logger
In-Reply-To: <p0624080bc575badb86f8@[192.168.1.212]>
References: <p0624080bc575badb86f8@[192.168.1.212]>
Message-ID: <49501C54.9010705@xtra.co.nz>

Joe
Joe Gwinn wrote:
> Bruce,
>
> At 9:08 PM +0000 12/22/08, time-nuts-request at febo.com wrote:
>   
>> Date: Tue, 23 Dec 2008 10:08:35 +1300
>> From: Bruce Griffiths <bruce.griffiths at xtra.co.nz>
>> Subject: Re: [time-nuts] Sub Pico Second Phase logger
>> To: Discussion of precise time and frequency measurement
>> 	<time-nuts at febo.com>
>>
>> Joe
>> Joe Gwinn wrote:
>>     
>>>  At 2:01 AM +0000 12/22/08, time-nuts-request at febo.com wrote:
>>>  
>>>       
>>>>  Message: 4
>>>>  Date: Mon, 22 Dec 2008 11:19:06 +1300
>>>>  From: Bruce Griffiths <bruce.griffiths at xtra.co.nz>
>>>>  Subject: Re: [time-nuts] Sub Pico Second Phase logger
>>>>  To: Discussion of precise time and frequency measurement
>>>> 	<time-nuts at febo.com>
>>>>
>>>>  Joe
>>>>
>>>>  Joe Gwinn wrote:
>>>>   > Bruce,
>>>>    
>>>>   >>
>>>>
>>>>         
>>  >> [snip]
>>
>>  >
>>  >>>>  [BG]  The DDS based equivalent (of the dual PLL Diophantine 
>> synthesiser) would
>>     
>>>>>>   use a pair of DDS chips each replacing a conventional PLL in the
>>>>>>   Diophantine frequency synthesiser, the output frequency of each having
>>>>>>             
>>  >>>>  zero phase truncation spurs.
>>     
>>>>>>   Both DDS clock sources should be spur free and have a frequency ratio
>>>>>>   that is a selected fixed rational fraction.
>>>>>>   
>>>>>>        
>>>>>>             
>>>>>   [JG]  A M/N PLL chip can arrange this.  I recall that Silicon Labs makes
>>>>>           
>>  >>>  such a chip, which requires a parameter load on power-up, so a
>>  >>> computer or FPGA is needed.
>>  >>    
>>     
>>  > 
>> <https://www.silabs.com/products/clocksoscillators/clocks/Pages/default.aspx>
>>     
>>>  Also of interest:
>>>
>>>
>>> <https://www.silabs.com/products/clocksoscillators/clocks/Pages/Any-RateJitterAttenuatingClockMultipliers.aspx>
>>>
>>>
>>>  
>>>       
>> The close in phase noise of these devices appears to be very high.
>> This may preclude their use in a system that just uses 2 of them directly.
>>     
>
> The SiLabs "Precision" units claim very low jitter (and thus low 
> phase noise).  The above "jitter-attenuating" units are in this 
> group.  I see that the spec numbers are still TBD though.
>
> There may be other makers; this is a very competitive area.  I got 
> the source from a RF engineer at work.
>
> By the way, when we first used one of the simple PLL chips, we had 
> failures.  It turned out that one had to bake the chips (to drive 
> moisture off) longer than the original instructions said, and some of 
> the chips cracked during soldering.  The new instructions eliminated 
> the problem.
>
> I suppose that all single-IC solutions will have worse phase noise 
> than a well-engineered discrete unit, simply because it's hard to 
> prevent undesired leakage of signals between parts of the the IC. 
> However, the ICs may still be more than adequate, and are a whole lot 
> easier than rolling our own discrete units.
>
>
>   
>> However in the high resolution version where the output frequencies of
>> the 2 M/N synthesisers are each divided by a large factor before being
>> added and subtracted from the reference (10MHz ??) frequency the
>> resultant close in phase noise will be much lower.
>>     
>
> And can be combined with use of the precision units.
>
>
>   
>> Control of the close in spur levels produced by the NCO may also be an
>> issue.
>>     
>
> If the division ratio is an integer, the spurs are reduced.
>
> Analog Devices has a web calculator that's useful for fast 
> exploration.  The calculator operation is explained and the reference 
> provided in their big tutorial on DDS principles.
>
>
>   
Its a bit misleading in that it indicates that the performance is
impaired when their is no phase truncation spur.
This may well be true for frequencies close to that frequency that has
no phase truncation spur, however in this application one wouldn't
choose an output frequency that has significant phase truncation spurs.
>>  >> M and N only have to be relatively prime (ie the GCD of M and N is 1).
>>     
>>>>  The ratio of M/N should also be close to 1.
>>>>  If the spacing of the phase truncation spur free output frequencies is
>>>>  about 10kHz (for either DDS) and M, N ~ 1000 the resultant mixer output
>>>>  frequencies would have a spacing of about 10Hz which may be adequate for
>>>>  this application.
>>>>    
>>>>         
>>>  I found and read the basic articles, which can be downloaded from
>>>       
>>  > Prof Sotiriadis' website:
>>     
>>>  <http://www.ece.jhu.edu/~pps/WEB/Publications/pub.html>
>>>
>>>
>>>       
>> There is also US patent 5267182.
>>     
>
> I did find 5,267,182 while searching for Sotiriadis' patent, but 
> forgot to mention it.  Don't know what the difference is.  In the US, 
> patent applications are made public after 18 months, or immediately 
> if the person is also applying for a European patent.  The US Patent 
> Office is years behind, so patent issuance may be a while.
>
>
>   
>>  > Items J10, J13, and J15 seem particularly relevant.
>>  >
>>     
>>>  All one needs is the M/N chip, although one can certainly use DDS chips.
>>>
>>>
>>>
>>>       
>> Using a DDS avoids the requirement for a pair of low phase noise VCOs.
>>     
>
> If we can control the spurs, many DDS chips are very good.
>
>   
A DDS, unlike a conventional digital frequency divider doesn't suffer
from aliasing of phase noise into the output passband.
>   
>>  >>  >> A conventional mixer would then be used to either add or subtract the
>>     
>>>>    
>>>>         
>>>>>>   two DDS output frequencies.
>>>>>>   If the ratio of the 2 DDS clock source frequencies is appropriately
>>>>>>   chosen the spacing between the resultant mixer output frequencies can be
>>>>>>   much finer than the spacing between the truncation spur free outputs of
>>>>>>   either DDS chip.
>>>>>>   The DDS and mixer outputs should be filtered to remove harmonics and
>>>>>>   other unwanted frequencies.
>>>>>>   
>>>>>>        
>>>>>>             
>>>>>   If the DDS chips are well chosen, we will get sin and cos outputs,
>>>>>   and so can implement a dual-mixer phasing scheme to yield only the
>>>>>   sum frequency or only the difference frequency, greatly reducing the
>>>>>   amount of filtering needed.  The better balanced the channels are the
>>>>>      
>>>>>           
>>>>   > better the cancellation of the unwanted term.  This is basically the
>>>>   > phasing method of single-sideband signal generation.
>>>>    
>>>>         
>>>  This would be a reason to use DDS chips instead of M/N PLL chips,
>>>  unless there are M/N PLL chips that provide quadrature outputs.
>>>  SiLabs Si5338 may suffice, as it allows one to control the relative
>>>  phase of its outputs.
>>>
>>>
>>>  
>>>       
>> If one were to divide the output frequency of the diophantine
>> synthesizer by 4 using a 2 bit Johnson counter then quadrature phase
>> outputs are available.
>> However the filters used to extract the fundamental from the divider
>> outputs would need to be matched.
>> If the diophantine frequency synthesiser output frequency doesn't vary
>> too much one can always use a quadrature hybrid.
>>     
>
> This seems like a lot of work.  Hmm.  Now that I think of it, the 
> SiLabs chips emit square waves (logic signals), not sine waves.  Back 
> to DDS chips, it seems.
>
> Joe
>
>   
The simplest way of achieving the required performance is preferable.

Bruce


From jgd at johngsbbq.com  Mon Dec 22 23:37:46 2008
From: jgd at johngsbbq.com (Neon John)
Date: Mon, 22 Dec 2008 18:37:46 -0500
Subject: [time-nuts] He is a Time-Nut Troublemaker....
In-Reply-To: <494FEC59.90905@xtra.co.nz>
References: <mailman.600.1229917104.2499.time-nuts@febo.com>	<BLU125-W46831CE6F2E119B7EEBE6CCEEF0@phx.gbl>	<494F1DA4.4000106@xtra.co.nz>
	<494F969B.1030604@erols.com> <494FEC59.90905@xtra.co.nz>
Message-ID: <uk80l4lbpbalj37v9rifggnacli5406g1j@4ax.com>

On Tue, 23 Dec 2008 08:36:57 +1300, Bruce Griffiths
<bruce.griffiths at xtra.co.nz> wrote:

>Chuck
>
>It was a paper written around 1942 detailing the procedures used to
>align the sights of mass produced rifles for which it was impractical to
>have each rifle individually adjusted on a firing range.
>Unfortunately I dont think I have a copy of this any longer, however
>I'll keep an eye out for it.
>The alignment jig used a mirror attached to a cylindrical plug that was
>a close slip fit into the end of the bore.
>It wasn't perfect but far better than not adjusting the sights at all.

since we have so many shooting time nuts here, I thought that y'all would
enjoy this page:

http://www.neon-john.com/Misc/Antique_Chrono.htm

I bought this instrument new in the box at an estate sale.  The guy apparently
acquired it but never even cut the packing tape from the box.

It works perfectly, using the wire-break principle.  I made some screens by
gluing a few runs fine copper wire across the bull's eye to paper targets. The
display is transit time.  The velocity must be looked up on charts that
convert the time and the screen spacing into velocity.  I actually wrote a
little HP41 program to do that and dispense with the charts.

 Unlike my Oehler and its sky screens, it is not fooled by shock waves
(sub-sonic rounds) or debris (shotgun shells) and is very repeatable.  The
velocity results agree within reasonable statistics of my Oehler 33p.

One of these days when the round tuits become plentiful, I'm going to design a
little box to interface the Oehler skyscreens to this unit.

I also have one of Oehler's very first commercial chronos.  It's all analog
and uses the constant current/capacitor method of determining time-of-flight
and displays the results on an analog meter.  Again, it appears to use the
wire-break method (no manual).

John
--
John De Armond
See my website for my current email address
http://www.neon-john.com
http://www.johndearmond.com <-- best little blog on the net!
Tellico Plains, Occupied TN
Democracy is three wolves and one sheep voting on what to have for supper.



From rdarlington at gmail.com  Mon Dec 22 23:43:26 2008
From: rdarlington at gmail.com (Robert Darlington)
Date: Mon, 22 Dec 2008 16:43:26 -0700
Subject: [time-nuts] He is a Time-Nut Troublemaker....
In-Reply-To: <uk80l4lbpbalj37v9rifggnacli5406g1j@4ax.com>
References: <mailman.600.1229917104.2499.time-nuts@febo.com>
	<BLU125-W46831CE6F2E119B7EEBE6CCEEF0@phx.gbl>
	<494F1DA4.4000106@xtra.co.nz> <494F969B.1030604@erols.com>
	<494FEC59.90905@xtra.co.nz>
	<uk80l4lbpbalj37v9rifggnacli5406g1j@4ax.com>
Message-ID: <b3bd5fcb0812221543t24e7338ek9cfb27a98618640e@mail.gmail.com>

Cool.  I used systems like this (but a bit faster) for measuring
detonation velocity in explosives.  Several wires would run through an
explosive compound and would break as the material detonated.  Later
the systems used the same wires but would measure the voltage/current
running through them as the explosive detonated in a magnetic field.

-Bob

On Mon, Dec 22, 2008 at 4:37 PM, Neon John <jgd at johngsbbq.com> wrote:
> On Tue, 23 Dec 2008 08:36:57 +1300, Bruce Griffiths
> <bruce.griffiths at xtra.co.nz> wrote:
>
>>Chuck
>>
>>It was a paper written around 1942 detailing the procedures used to
>>align the sights of mass produced rifles for which it was impractical to
>>have each rifle individually adjusted on a firing range.
>>Unfortunately I dont think I have a copy of this any longer, however
>>I'll keep an eye out for it.
>>The alignment jig used a mirror attached to a cylindrical plug that was
>>a close slip fit into the end of the bore.
>>It wasn't perfect but far better than not adjusting the sights at all.
>
> since we have so many shooting time nuts here, I thought that y'all would
> enjoy this page:
>
> http://www.neon-john.com/Misc/Antique_Chrono.htm
>
> I bought this instrument new in the box at an estate sale.  The guy apparently
> acquired it but never even cut the packing tape from the box.
>
> It works perfectly, using the wire-break principle.  I made some screens by
> gluing a few runs fine copper wire across the bull's eye to paper targets. The
> display is transit time.  The velocity must be looked up on charts that
> convert the time and the screen spacing into velocity.  I actually wrote a
> little HP41 program to do that and dispense with the charts.
>
>  Unlike my Oehler and its sky screens, it is not fooled by shock waves
> (sub-sonic rounds) or debris (shotgun shells) and is very repeatable.  The
> velocity results agree within reasonable statistics of my Oehler 33p.
>
> One of these days when the round tuits become plentiful, I'm going to design a
> little box to interface the Oehler skyscreens to this unit.
>
> I also have one of Oehler's very first commercial chronos.  It's all analog
> and uses the constant current/capacitor method of determining time-of-flight
> and displays the results on an analog meter.  Again, it appears to use the
> wire-break method (no manual).
>
> John
> --
> John De Armond
> See my website for my current email address
> http://www.neon-john.com
> http://www.johndearmond.com <-- best little blog on the net!
> Tellico Plains, Occupied TN
> Democracy is three wolves and one sheep voting on what to have for supper.
>
>
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>


From hmurray at megapathdsl.net  Tue Dec 23 01:52:06 2008
From: hmurray at megapathdsl.net (Hal Murray)
Date: Mon, 22 Dec 2008 17:52:06 -0800
Subject: [time-nuts] He is a Time-Nut Troublemaker....
In-Reply-To: Message from "Robert Darlington" <rdarlington@gmail.com> of "Mon,
	22 Dec 2008 16:43:26 MST."
	<b3bd5fcb0812221543t24e7338ek9cfb27a98618640e@mail.gmail.com> 
Message-ID: <20081223015207.E744DBCD9@ip-64-139-1-69.sjc.megapath.net>


> Cool.  I used systems like this (but a bit faster) for measuring
> detonation velocity in explosives.  Several wires would run through an
> explosive compound and would break as the material detonated.  Later
> the systems used the same wires but would measure the voltage/current
> running through them as the explosive detonated in a magnetic field. 

Speaking of timings and explosions...

Early Ethernets used coax with transceivers at the coax and a drop cable down 
to the computer.  One of the problems was that a short in the transceiver or 
the attachment could kill the whole segment.  They were a pain to debug.

Some early host adapter cards had a TDR feature.  It didn't cost much.  It 
was basically just a counter that started when you started transmitting a 
packet and stopped when the transceiver said "collision".  It wasn't great, 
but could at least get you close.

I've heard stories that the TDR feature was used to collect timing data on 
some A-bomb tests.  The bomb was at the bottom of a hole.  An ethernet cable 
went down the hole.  I can't remember or reconstruct the details.  I assume 
there was a PDP-11 at the top of the hole.  The idea is something like you 
send a packet to trigger the bomb, and when the bomb goes off, the cable 
vaporizes and is no longer terminated so packets turn into collisions and the 
TDR grabs the time.

It sounds like an urban legend, but it's a fun one.




-- 
These are my opinions, not necessarily my employer's.  I hate spam.





From yuri at ostry.ru  Tue Dec 23 02:04:18 2008
From: yuri at ostry.ru (Yuri Ostry)
Date: Tue, 23 Dec 2008 05:04:18 +0300
Subject: [time-nuts] He is a Time-Nut Troublemaker....
In-Reply-To: <uk80l4lbpbalj37v9rifggnacli5406g1j@4ax.com>
References: <mailman.600.1229917104.2499.time-nuts@febo.com>
	<BLU125-W46831CE6F2E119B7EEBE6CCEEF0@phx.gbl>
	<494F1DA4.4000106@xtra.co.nz>
	<494F969B.1030604@erols.com> <494FEC59.90905@xtra.co.nz>
	<uk80l4lbpbalj37v9rifggnacli5406g1j@4ax.com>
Message-ID: <8610481299.20081223050418@ostry.ru>

Hello,

Tuesday, December 23, 2008, 2:37:46, Neon John wrote:

N> since we have so many shooting time nuts here, I thought that y'all would
N> enjoy this page:

N> http://www.neon-john.com/Misc/Antique_Chrono.htm

Fun thing... I seen similar decade modules in some russian counters
dated early 50's...

But much more funny thing was old dekatron-based pulse/time period
counters. They was widely used in a nuclear research in late 40 -
early 50's, I still seen one of them working in some lab in late 90's
(12 decades in a row if memory serves me correctly). Guys there keep
one unit and some stock of spare dekatron tubes from decomissioned
ones as a sample of old technology. ;)

Other funny thing I seen there - old tube secondary frequency standard
(CH1-27 if memory serves me correctly). Two large boxes, one is
precision ovenized xtal oscillator with standard frequency broadcast
receiver, scope to tune its own xtal by Lissajou figures and some
other goodies, other box is frequency synthesizer up to 600 MHz. Don't
know how much it weighs, but certainly over 100 kg total.

-- 
Best regards,
 Yuri                          mailto:yuri at ostry.ru



From holrum at hotmail.com  Tue Dec 23 02:29:00 2008
From: holrum at hotmail.com (Mark Sims)
Date: Tue, 23 Dec 2008 02:29:00 +0000
Subject: [time-nuts] He is a Time-Nut Troublemaker....
In-Reply-To: <mailman.643.1229989408.2499.time-nuts@febo.com>
References: <mailman.643.1229989408.2499.time-nuts@febo.com>
Message-ID: <BLU125-W2622494AE2E1E407182B0ACEEC0@phx.gbl>


Nope, definietly not a legend...  TDR/coax based systems are rather common for measuring blasts (nuke and otherwise,  but not using Ethernet cards).  Basically the shock wave crushes the coax and messes up the impedance as it propogates.  Results are monitored by TDRs.  And a fun time is had by all...Another system uses high speed photography to record the mayhem and work out the blast effects.  Million+ frames per second can be achieved. I saw some great video of a very large boulder being obliterated.  Cracks that formed in well under a millisecond took ages to appear and spread.  The full recording took about 15 minutes to play back.  They also had a video of a pipe bomb in action.  Such things are like Medusa...  best to watch them a mirror.-------------I've heard stories that the TDR feature was used to collect timing data on 
some A-bomb tests.  The bomb was at the bottom of a hole.  An ethernet cable 
went down the hole.  I can't remember or reconstruct the details.  I assume 
there was a PDP-11 at the top of the hole.  The idea is something like you 
send a packet to trigger the bomb, and when the bomb goes off, the cable 
vaporizes and is no longer terminated so packets turn into collisions and the 
TDR grabs the time.

It sounds like an urban legend, but it's a fun one.


_________________________________________________________________
Life on your PC is safer, easier, and more enjoyable with Windows Vista?. 
http://clk.atdmt.com/MRT/go/127032870/direct/01/

From brooke at pacific.net  Tue Dec 23 02:45:34 2008
From: brooke at pacific.net (Brooke Clarke)
Date: Mon, 22 Dec 2008 18:45:34 -0800
Subject: [time-nuts] He is a Time-Nut Troublemaker....
In-Reply-To: <494FF7B7.2020403@xtra.co.nz>
References: <mailman.600.1229917104.2499.time-nuts@febo.com>	<BLU125-W46831CE6F2E119B7EEBE6CCEEF0@phx.gbl>	<494F1DA4.4000106@xtra.co.nz>	<494F969B.1030604@erols.com>	<494FEC59.90905@xtra.co.nz>	<494FF0B8.4030809@xtra.co.nz>
	<494FF7B7.2020403@xtra.co.nz>
Message-ID: <495050CE.5020704@pacific.net>

Hi:

The original Time Nut, Alfred Loomis (book: Tuxedo Park) patented:

1435073 Gun Mount
1409304 Chronograph
1376890 Chronograph
2884628 Long Range Navigation System  (LORAN)
Links at: http://www.prc68.com/I/timefreq.shtml#HC
so this topic is not as far off topic as it might appear.

Have Fun,

Brooke Clarke
http://www.prc68.com



From cfharris at erols.com  Tue Dec 23 06:23:14 2008
From: cfharris at erols.com (Chuck Harris)
Date: Tue, 23 Dec 2008 01:23:14 -0500
Subject: [time-nuts] He is a Time-Nut Troublemaker....
In-Reply-To: <495050CE.5020704@pacific.net>
References: <mailman.600.1229917104.2499.time-nuts@febo.com>	<BLU125-W46831CE6F2E119B7EEBE6CCEEF0@phx.gbl>	<494F1DA4.4000106@xtra.co.nz>	<494F969B.1030604@erols.com>	<494FEC59.90905@xtra.co.nz>	<494FF0B8.4030809@xtra.co.nz>	<494FF7B7.2020403@xtra.co.nz>
	<495050CE.5020704@pacific.net>
Message-ID: <495083D2.8010503@erols.com>

And for the ham time-nuts, Hiram Percy Maxim's father invented the
Maxim machine gun.  Hiram Percy Maxim invented the firearm silencer.

-Chuck Harris

Brooke Clarke wrote:
> Hi:
> 
> The original Time Nut, Alfred Loomis (book: Tuxedo Park) patented:
> 
> 1435073 Gun Mount
> 1409304 Chronograph
> 1376890 Chronograph
> 2884628 Long Range Navigation System  (LORAN)
> Links at: http://www.prc68.com/I/timefreq.shtml#HC
> so this topic is not as far off topic as it might appear.
> 
> Have Fun,
> 
> Brooke Clarke
> http://www.prc68.com
> 
> 
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
> 


From stephan at rrsg.ee.uct.ac.za  Tue Dec 23 09:06:30 2008
From: stephan at rrsg.ee.uct.ac.za (Stephan Sandenbergh)
Date: Tue, 23 Dec 2008 11:06:30 +0200
Subject: [time-nuts] Motorola M12+T - On board oscillator phase noise spec
	and/or part number
Message-ID: <ca708d410812230106p68979033t4f656cc94f9dab7b@mail.gmail.com>

Hi All,

Has anyone been able to figure out the part number and/or measured the
phase noise of the quartz oscillator on board the Motorola M12+T?

This will be an interesting figure to see.

Regards,

Stephan.


From joegwinn at comcast.net  Tue Dec 23 15:00:15 2008
From: joegwinn at comcast.net (Joe Gwinn)
Date: Tue, 23 Dec 2008 10:00:15 -0500
Subject: [time-nuts] Sub Pico Second Phase logger
Message-ID: <p0624080cc575e635b033@[192.168.1.212]>

Bruce,

At 11:43 PM +0000 12/22/08, time-nuts-request at febo.com wrote:
>
>Date: Tue, 23 Dec 2008 12:01:40 +1300
>From: Bruce Griffiths <bruce.griffiths at xtra.co.nz>
>Subject: Re: [time-nuts] Sub Pico Second Phase logger
>To: Discussion of precise time and frequency measurement
>	<time-nuts at febo.com>
>
>[snip]
>  >> [BG]  Control of the close in spur levels produced by the NCO 
>may also be an
>>>  issue.
>>>    
>>
>>  [JG]  If the division ratio is an integer, the spurs are reduced.
>>
>>  Analog Devices has a web calculator that's useful for fast
>>  exploration.  The calculator operation is explained and the reference
>>  provided in their big tutorial on DDS principles.
>>
>>
>>  
>It's a bit misleading in that it indicates that the performance is
>impaired when there is no phase truncation spur.

I just look at the spur chart.


>This may well be true for frequencies close to that frequency that has
>no phase truncation spur, however in this application one wouldn't
>choose an output frequency that has significant phase truncation spurs.

The value of the calculator is to look around for such sweet spots.

One can also generate the traditional spur chart, the one with the 
nest of diagonal lines.


>  >>>  I found and read the basic articles, which can be downloaded from
>>>>      
>>>   > Prof Sotiriadis' website:
>>>    
>>>>   <http://www.ece.jhu.edu/~pps/WEB/Publications/pub.html>
>>>>
>>>>
>>>>      
>>>  [BG]  There is also US patent 5267182.
>>>    
>>
>  > I did find 5,267,182 while searching for Sotiriadis' patent, but
>>  forgot to mention it.  Don't know what the difference is.  In the US,
>>  patent applications are made public after 18 months, or immediately
>>  if the person is also applying for a European patent.  The US Patent
>  > Office is years behind, so patent issuance may be a while.

I just read 5,267,182.  It appears to anticipate Sotiriadis in every 
aspect, so it may be a *long* time before Sotiriadis's patent is 
issued.


>  >>  > Items J10, J13, and J15 seem particularly relevant.
>>>   >
>>>    
>>>>   All one needs is the M/N chip, although one can certainly use DDS chips.
>>>>
>>>>
>>>>
>>>>      
>>>  Using a DDS avoids the requirement for a pair of low phase noise VCOs.
>>>    
>>
>>  If we can control the spurs, many DDS chips are very good.
>>
>>  
>A DDS, unlike a conventional digital frequency divider, doesn't suffer
>from aliasing of phase noise into the output passband.

How true is this, in practice?  A DDS is at the mercy of phase noise 
in its reference clock, by much the same mechanism as for a simple 
divider chain.  And the variable-factor dividers (the M and N above) 
work in a manner similar to a DDS, but with far coarser increments 
and limits.  Both DDS and M/N PLL chips use a PLL to clean up the 
resulting ref signal.  Many DDS chips incorporate a M/N PLL to 
multiply the ref frequency.


>  >>  >>  >> A conventional mixer would then be used to either add or 
>subtract the
>>>    
>>>>>   
>>>>>        
>>>>>>>    two DDS output frequencies.
>>>>>>>    If the ratio of the 2 DDS clock source frequencies is appropriately
>>>>>>>    chosen the spacing between the resultant mixer output 
>>>>>>>frequencies can be
>>>>>>>    much finer than the spacing between the truncation spur 
>>>>>>>free outputs of
>>>>>>>    either DDS chip.
>>>>>>>    The DDS and mixer outputs should be filtered to remove harmonics and
>>>>>>>    other unwanted frequencies.
>>>>>>>  
>>>>>>>       
>>>>>>>            
>>>>>>    If the DDS chips are well chosen, we will get sin and cos outputs,
>>>>>>    and so can implement a dual-mixer phasing scheme to yield only the
>  >>>>>   sum frequency or only the difference frequency, greatly reducing the
>>>>>>    amount of filtering needed.  The better balanced the channels are the
>>>>>>     
>>>>>>          
>>>>>    > better the cancellation of the unwanted term.  This is basically the
>>>>>    > phasing method of single-sideband signal generation.
>>>>>   
>>>>>        
>>>>   This would be a reason to use DDS chips instead of M/N PLL chips,
>>>>   unless there are M/N PLL chips that provide quadrature outputs.
>  >>>  SiLabs Si5338 may suffice, as it allows one to control the relative
>>>>   phase of its outputs.
>>>>
>>>>
>>>> 
>>>>      
>>>  If one were to divide the output frequency of the diophantine
>>>  synthesizer by 4 using a 2 bit Johnson counter then quadrature phase
>>>  outputs are available.
>>>  However the filters used to extract the fundamental from the divider
>>>  outputs would need to be matched.
>>>  If the diophantine frequency synthesiser output frequency doesn't vary
>>>  too much one can always use a quadrature hybrid.
>>>    
>>
>>  This seems like a lot of work.  Hmm.  Now that I think of it, the
>>  SiLabs chips emit square waves (logic signals), not sine waves.  Back
>>  to DDS chips, it seems.
>>
>>  Joe
>>
>>
>The simplest way of achieving the required performance is preferable.

Yes, but aren't we Time Nuts?

Joe


From robert8rpi at yahoo.co.uk  Tue Dec 23 15:39:03 2008
From: robert8rpi at yahoo.co.uk (Robert Atkinson)
Date: Tue, 23 Dec 2008 15:39:03 +0000 (GMT)
Subject: [time-nuts] Trimble multi-way socket
In-Reply-To: <494F9CCF.3090404@tiscali.co.uk>
Message-ID: <910515.28451.qm@web27101.mail.ukl.yahoo.com>

Hi Dave,
Farnell sell the plugs for the Pallisade (I assume you have the selfcontained antenna/receiver unit). You have to buy the plug houding and contacts separately. The manual (available online) has the part numbers if you look carefully). I'm in California at the moment so don't have easy access to give you full part numbers. I'f you can't identify the parts let me know.
?
Robert G8RPI.

--- On Mon, 22/12/08, Dave Ackrill <dave.g0dja at tiscali.co.uk> wrote:

From: Dave Ackrill <dave.g0dja at tiscali.co.uk>
Subject: [time-nuts] Trimble multi-way socket
To: "Discussion of precise time and frequency measurement" <time-nuts at febo.com>
Date: Monday, 22 December, 2008, 1:57 PM

I have one of the circular Trimbel units, I think it might be a Jupiter?

Anyway, what I'm after is one of the multi-way plugs so that I can 
connect it up and start to use it.  Does anyone know of a source for 
these plugs please?

Thanks - Dave

_______________________________________________
time-nuts mailing list -- time-nuts at febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.



      

From holrum at hotmail.com  Tue Dec 23 16:10:29 2008
From: holrum at hotmail.com (Mark Sims)
Date: Tue, 23 Dec 2008 16:10:29 +0000
Subject: [time-nuts] Sub Pico Second Phase logger
In-Reply-To: <mailman.5.1230033601.9617.time-nuts@febo.com>
References: <mailman.5.1230033601.9617.time-nuts@febo.com>
Message-ID: <BLU125-W29C8667E5FAE2A1EE11F5BCEEC0@phx.gbl>


Since when has prior art or obviousness kept the US Patent Orifice from issuing a patent?  ;-)

---------

I just read 5,267,182.  It appears to anticipate Sotiriadis in every 
aspect, so it may be a *long* time before Sotiriadis's patent is 
issued.


_________________________________________________________________
It?s the same Hotmail?. If by ?same? you mean up to 70% faster.
http://windowslive.com/online/hotmail?ocid=TXT_TAGLM_WL_hotmail_acq_broad1_122008

From wittend at wwrinc.com  Tue Dec 23 16:15:37 2008
From: wittend at wwrinc.com (David M. Witten II)
Date: Tue, 23 Dec 2008 10:15:37 -0600
Subject: [time-nuts] He is a Time-Nut Troublemaker....
In-Reply-To: <495083D2.8010503@erols.com>
References: <mailman.600.1229917104.2499.time-nuts@febo.com>	<BLU125-W46831CE6F2E119B7EEBE6CCEEF0@phx.gbl>	<494F1DA4.4000106@xtra.co.nz>	<494F969B.1030604@erols.com>	<494FEC59.90905@xtra.co.nz>	<494FF0B8.4030809@xtra.co.nz>	<494FF7B7.2020403@xtra.co.nz>	<495050CE.5020704@pacific.net>
	<495083D2.8010503@erols.com>
Message-ID: <49510EA9.5030100@wwrinc.com>

Points of pride, I'm sure.

-- Dave

Chuck Harris wrote:
> And for the ham time-nuts, Hiram Percy Maxim's father invented the
> Maxim machine gun.  Hiram Percy Maxim invented the firearm silencer.
> 
> -Chuck Harris
> 
> Brooke Clarke wrote:
>> Hi:
>>
>> The original Time Nut, Alfred Loomis (book: Tuxedo Park) patented:
>>
>> 1435073 Gun Mount
>> 1409304 Chronograph
>> 1376890 Chronograph
>> 2884628 Long Range Navigation System  (LORAN)
>> Links at: http://www.prc68.com/I/timefreq.shtml#HC
>> so this topic is not as far off topic as it might appear.
>>
>> Have Fun,
>>
>> Brooke Clarke
>> http://www.prc68.com
>>
>>
>> _______________________________________________
>> time-nuts mailing list -- time-nuts at febo.com
>> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>> and follow the instructions there.
>>
> 
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.


From magnus at rubidium.dyndns.org  Tue Dec 23 16:27:28 2008
From: magnus at rubidium.dyndns.org (Magnus Danielson)
Date: Tue, 23 Dec 2008 17:27:28 +0100
Subject: [time-nuts] He is a Time-Nut Troublemaker....
In-Reply-To: <49510EA9.5030100@wwrinc.com>
References: <mailman.600.1229917104.2499.time-nuts@febo.com>	<BLU125-W46831CE6F2E119B7EEBE6CCEEF0@phx.gbl>	<494F1DA4.4000106@xtra.co.nz>	<494F969B.1030604@erols.com>	<494FEC59.90905@xtra.co.nz>	<494FF0B8.4030809@xtra.co.nz>	<494FF7B7.2020403@xtra.co.nz>	<495050CE.5020704@pacific.net>	<495083D2.8010503@erols.com>
	<49510EA9.5030100@wwrinc.com>
Message-ID: <49511170.2080600@rubidium.dyndns.org>

David M. Witten II skrev:
> Points of pride, I'm sure.

All this talk still does not make me feel like going out and get a 
firearm of any sort, fashinating as they can be in their own right.

If someone got me involved in elk-hunting maybe, but that's about it I 
think.

My intent is to get some stuff done in the lab during the vacation. 
(Desperatly trying to get some more on-topic discussions going).

Cheers,
Magnus


From dave.g0dja at tiscali.co.uk  Tue Dec 23 16:33:14 2008
From: dave.g0dja at tiscali.co.uk (Dave Ackrill)
Date: Tue, 23 Dec 2008 16:33:14 +0000
Subject: [time-nuts] Trimble multi-way socket
In-Reply-To: <910515.28451.qm@web27101.mail.ukl.yahoo.com>
References: <910515.28451.qm@web27101.mail.ukl.yahoo.com>
Message-ID: <495112CA.20208@tiscali.co.uk>

Robert Atkinson wrote:
> Hi Dave,
> Farnell sell the plugs for the Pallisade (I assume you have the selfcontained antenna/receiver unit). You have to buy the plug houding and contacts separately. The manual (available online) has the part numbers if you look carefully). I'm in California at the moment so don't have easy access to give you full part numbers. I'f you can't identify the parts let me know.
>  
> Robert G8RPI.
>   

Thanks Robert,

Yes, it is the Pallisade in the white self contained unit.  So, I'll 
hunt round in the Farnell catalogue.

Thanks for the information.

Cheers - Dave (G0DJA)


From jra at febo.com  Tue Dec 23 16:40:51 2008
From: jra at febo.com (John Ackermann N8UR)
Date: Tue, 23 Dec 2008 11:40:51 -0500
Subject: [time-nuts] New topics (was Re: He is a Time-Nut Troublemaker....)
In-Reply-To: <49511170.2080600@rubidium.dyndns.org>
References: <mailman.600.1229917104.2499.time-nuts@febo.com>	<BLU125-W46831CE6F2E119B7EEBE6CCEEF0@phx.gbl>	<494F1DA4.4000106@xtra.co.nz>	<494F969B.1030604@erols.com>	<494FEC59.90905@xtra.co.nz>	<494FF0B8.4030809@xtra.co.nz>	<494FF7B7.2020403@xtra.co.nz>	<495050CE.5020704@pacific.net>	<495083D2.8010503@erols.com>	<49510EA9.5030100@wwrinc.com>
	<49511170.2080600@rubidium.dyndns.org>
Message-ID: <49511493.4090803@febo.com>

Magnus Danielson wrote:

> My intent is to get some stuff done in the lab during the vacation. 
> (Desperatly trying to get some more on-topic discussions going).

Here are two questions that have been running around my head:

1.  Following on from the discussion last week about trying to 
synchronize multiple oscillators to improve phase noise, I've wondered 
about a simpler tack:  take, for example, two 5 MHz atomic standards and 
mix their outputs together, using the 10 MHz result to drive a time 
scale.  Assuming the standards were of relatively equal quality, would 
this provide a better time scale than using one of the standards alone?

2.  Several measurement techniques require a given phase relationship 
(e.g., quadrature) between DUT and reference.  For HF frequencies (ie, 5 
or 10 MHz) is there a *practical* phase shifter design covering 180+ 
degrees that doesn't involve switching various lengths of coax in and 
out of the line?

Happy holidays!

John


From james.p.lux at jpl.nasa.gov  Tue Dec 23 17:05:31 2008
From: james.p.lux at jpl.nasa.gov (Lux, James P)
Date: Tue, 23 Dec 2008 09:05:31 -0800
Subject: [time-nuts] New topics (was Re: He is a Time-Nut
 Troublemaker....)
In-Reply-To: <49511493.4090803@febo.com>
References: <mailman.600.1229917104.2499.time-nuts@febo.com>
	<BLU125-W46831CE6F2E119B7EEBE6CCEEF0@phx.gbl>	<494F1DA4.4000106@xtra.co.nz>
	<494F969B.1030604@erols.com>	<494FEC59.90905@xtra.co.nz>
	<494FF0B8.4030809@xtra.co.nz>	<494FF7B7.2020403@xtra.co.nz>
	<495050CE.5020704@pacific.net>	<495083D2.8010503@erols.com>
	<49510EA9.5030100@wwrinc.com>	<49511170.2080600@rubidium.dyndns.org>
	<49511493.4090803@febo.com>
Message-ID: <ECE7A93BD093E1439C20020FBE87C47FEB55DA9096@ALTPHYEMBEVSP20.RES.AD.JPL>



> -----Original Message-----
> From: time-nuts-bounces at febo.com
> [mailto:time-nuts-bounces at febo.com] On Behalf Of John Ackermann N8UR
> Sent: Tuesday, December 23, 2008 8:41 AM
> To: Discussion of precise time and frequency measurement
> Subject: [time-nuts] New topics (was Re: He is a Time-Nut
> Troublemaker....)
>
> Magnus Danielson wrote:
>
> > My intent is to get some stuff done in the lab during the vacation.
> > (Desperatly trying to get some more on-topic discussions going).
>
> Here are two questions that have been running around my head:
>
> 1.  Following on from the discussion last week about trying
> to synchronize multiple oscillators to improve phase noise,
> I've wondered about a simpler tack:  take, for example, two 5
> MHz atomic standards and mix their outputs together, using
> the 10 MHz result to drive a time scale.  Assuming the
> standards were of relatively equal quality, would this
> provide a better time scale than using one of the standards alone?
>
> 2.  Several measurement techniques require a given phase
> relationship (e.g., quadrature) between DUT and reference.
> For HF frequencies (ie, 5 or 10 MHz) is there a *practical*
> phase shifter design covering 180+ degrees that doesn't
> involve switching various lengths of coax in and out of the line?
>

Surely, you don't have a problem with a precision trombone line for 10 MHz, do you?
You could use a water dielectric and slow the waves WAY down so it's of practical length (if not impractical in other ways)

But more seriously.. How accurate and stable does the phase shift have to be?  There are some little 10MHz phase shifters down in one of our labs that are (guessing) some sort of transformer inside.  They're about the size of the Helipot style 10 turns (i.e. a couple inches in diameter and a couple or three inches long, with a 1/4" shaft to adjust phase. (I'll go down and see if I can find one and the mfr & part #.. They're probably not made any more, though)

A more classic approach is to take a 2x or 4x frequency and run it into a suitable divider/decoder to generate quadrature.


Once you have quadrature, you then need some way to combine the two with varying amplitudes.. Sine/cosine pots, etc  Or some MDACs driven by a lookup table.  (the commercial phase shifters use a 90degree hybrid and some sort of variable gain thing.. PIN diodes, mixers, what-have-you)

Some form of goniometer springs to mind as a way to do it.  The stability of couplings, etc., are going to be determined by mechanical tolerances, and clever design might make it fairly temperature immune.  Vacuum capacitors are quite stable with aging (since the dielectric doesn't change)


James Lux, P.E.
Task Manager, SOMD Software Defined Radios
Flight Communications Systems Section
Jet Propulsion Laboratory
4800 Oak Grove Drive, Mail Stop 161-213
Pasadena, CA, 91109
+1(818)354-2075 phone
+1(818)393-6875 fax


From magnus at rubidium.dyndns.org  Tue Dec 23 17:25:44 2008
From: magnus at rubidium.dyndns.org (Magnus Danielson)
Date: Tue, 23 Dec 2008 18:25:44 +0100
Subject: [time-nuts] New topics (was Re: He is a Time-Nut
	Troublemaker....)
In-Reply-To: <49511493.4090803@febo.com>
References: <mailman.600.1229917104.2499.time-nuts@febo.com>	<BLU125-W46831CE6F2E119B7EEBE6CCEEF0@phx.gbl>	<494F1DA4.4000106@xtra.co.nz>	<494F969B.1030604@erols.com>	<494FEC59.90905@xtra.co.nz>	<494FF0B8.4030809@xtra.co.nz>	<494FF7B7.2020403@xtra.co.nz>	<495050CE.5020704@pacific.net>	<495083D2.8010503@erols.com>	<49510EA9.5030100@wwrinc.com>	<49511170.2080600@rubidium.dyndns.org>
	<49511493.4090803@febo.com>
Message-ID: <49511F18.7050903@rubidium.dyndns.org>

John Ackermann N8UR skrev:
> Magnus Danielson wrote:
> 
>> My intent is to get some stuff done in the lab during the vacation. 
>> (Desperatly trying to get some more on-topic discussions going).
> 
> Here are two questions that have been running around my head:
> 
> 1.  Following on from the discussion last week about trying to 
> synchronize multiple oscillators to improve phase noise, I've wondered 
> about a simpler tack:  take, for example, two 5 MHz atomic standards and 
> mix their outputs together, using the 10 MHz result to drive a time 
> scale.  Assuming the standards were of relatively equal quality, would 
> this provide a better time scale than using one of the standards alone?

I have been looking at mutual lock systems for say two 10 MHz 
oscillators. This mutual lock system behaves much as a PLL circuit (as 
contrary to the other mutual lock methods described previous) such that 
a phase detector detects the phase-difference between the oscillators, a 
loop filter filters this difference and then it is feed back with 
opposite signs to the respective oscillator. I envision that a common 
EFC input exists to the system. Such a system is kind of interesting in 
that within the PLL bandwidth, the two oscillators are locked and you 
see the average of frequency errors etc. Well above the PLL bandwidth 
the two oscillators is independent of each other and just above the PLL 
bandwidth they are essentially independent. As the two oscillators is 
phase-locked in, their outputs can be combined and noise reduction can 
be achived, which is the significant effect above the PLL bandwidth.

It is interesting to notice that the PLL operates on the difference 
between the oscillators, where as the EFC input is acting as a common 
mode action, which in the perfect world is not influenced by the 
diffrential PLL. Realities is however such that the EFC is not linear, 
and the need to regulate differently also ensures that the oscillator 
gain constant never really match, and therefore will also the 
diffrential PLL "leak-in" on the common mode behaviour.

I have not seen any reference to this type of diffrential PLL action to 
mutual locking. I've only seen discussions on mutual locking involving 
injection locking.

This diffrential locking technique could be applied to atomic standards, 
but then naturally require much improved solution than simple 
oscillators. The diffrential locking technique does not magically solve 
issues that is typically common mode, such as temperature dependence. It 
can however even out individual properties like noise and systematic 
drift to some extent. It essentially runs the oscillators as a common 
constellation and attempts to achieve the average improvements of those 
oscillators in an interlocked fashion. In its simplicity it will do 
unweighed averaging. It is fairly easy to do weighed averaging by 
individualizing the feedback gain to the respective oscillators. Further 
refinements would individualize the proportional and integrate feedback 
terms, but as always, the simplicity forms a limit.

I have intended to make some runs just for fun to see how this behaves 
in real life.

> Happy holidays!

I wish you all happy holidays!

Cheers,
Magnus


From dave.g0dja at tiscali.co.uk  Tue Dec 23 17:41:04 2008
From: dave.g0dja at tiscali.co.uk (Dave Ackrill)
Date: Tue, 23 Dec 2008 17:41:04 +0000
Subject: [time-nuts] Trimble multi-way socket
In-Reply-To: <910515.28451.qm@web27101.mail.ukl.yahoo.com>
References: <910515.28451.qm@web27101.mail.ukl.yahoo.com>
Message-ID: <495122B0.7050006@tiscali.co.uk>

Robert Atkinson wrote:
> Hi Dave,
> Farnell sell the plugs for the Pallisade (I assume you have the selfcontained antenna/receiver unit). You have to buy the plug houding and contacts separately. The manual (available online) has the part numbers if you look carefully). I'm in California at the moment so don't have easy access to give you full part numbers. I'f you can't identify the parts let me know.
>   

 From the GM4ISM website at 
http://www.dc2light.pwp.blueyonder.co.uk/Webpage/GPS_ref.htm I 
discovered that I needed the "backshell, part no. 6810-204-2001 and 
sockets, part no. 6862-201-22278".

However, although I've found the sockets (Deutsch 6862-201-22278 - look 
for the alternative RoHS compliant type) in Farnell, but I'm not so sure 
about the backshell.  The information on the GM4IS page says I need a 
6810-204-2001 but the list in the online catelogue only has 
6810-201-2001, in various diameters, and a couple of 6810-204-1001, both 
5.08mm diameter.  So, I'm not sure which one would be correct.  Does 
anyone have more information that would help please?

Thanks - Dave


From cfharris at erols.com  Tue Dec 23 17:43:25 2008
From: cfharris at erols.com (Chuck Harris)
Date: Tue, 23 Dec 2008 12:43:25 -0500
Subject: [time-nuts] He is a Time-Nut Troublemaker....
In-Reply-To: <49510EA9.5030100@wwrinc.com>
References: <mailman.600.1229917104.2499.time-nuts@febo.com>	<BLU125-W46831CE6F2E119B7EEBE6CCEEF0@phx.gbl>	<494F1DA4.4000106@xtra.co.nz>	<494F969B.1030604@erols.com>	<494FEC59.90905@xtra.co.nz>	<494FF0B8.4030809@xtra.co.nz>	<494FF7B7.2020403@xtra.co.nz>	<495050CE.5020704@pacific.net>	<495083D2.8010503@erols.com>
	<49510EA9.5030100@wwrinc.com>
Message-ID: <4951233D.8000605@erols.com>

David M. Witten II wrote:
> Points of pride, I'm sure.

ABSOLUTELY!  Freedom was born of guns.

Tyrants are never willing to give it to you
without a fight.

-Chuck Harris

> 
> -- Dave
> 
> Chuck Harris wrote:
>> And for the ham time-nuts, Hiram Percy Maxim's father invented the
>> Maxim machine gun.  Hiram Percy Maxim invented the firearm silencer.
>>
>> -Chuck Harris


From james.p.lux at jpl.nasa.gov  Tue Dec 23 17:49:59 2008
From: james.p.lux at jpl.nasa.gov (Lux, James P)
Date: Tue, 23 Dec 2008 09:49:59 -0800
Subject: [time-nuts] New topics (was Re: He is a
	Time-Nut	Troublemaker....)
In-Reply-To: <49511F18.7050903@rubidium.dyndns.org>
References: <mailman.600.1229917104.2499.time-nuts@febo.com>
	<BLU125-W46831CE6F2E119B7EEBE6CCEEF0@phx.gbl>	<494F1DA4.4000106@xtra.co.nz>
	<494F969B.1030604@erols.com>	<494FEC59.90905@xtra.co.nz>
	<494FF0B8.4030809@xtra.co.nz>	<494FF7B7.2020403@xtra.co.nz>
	<495050CE.5020704@pacific.net>	<495083D2.8010503@erols.com>
	<49510EA9.5030100@wwrinc.com>	<49511170.2080600@rubidium.dyndns.org>
	<49511493.4090803@febo.com> <49511F18.7050903@rubidium.dyndns.org>
Message-ID: <ECE7A93BD093E1439C20020FBE87C47FEB55DA90A2@ALTPHYEMBEVSP20.RES.AD.JPL>



> -----Original Message-----
> From: time-nuts-bounces at febo.com
> [mailto:time-nuts-bounces at febo.com] On Behalf Of Magnus Danielson
> Sent: Tuesday, December 23, 2008 9:26 AM
> To: Discussion of precise time and frequency measurement
> Subject: Re: [time-nuts] New topics (was Re: He is a Time-Nut
> Troublemaker....)
>
> John Ackermann N8UR skrev:
> > Magnus Danielson wrote:
> >
> >> My intent is to get some stuff done in the lab during the vacation.
> >> (Desperatly trying to get some more on-topic discussions going).
> >
> > Here are two questions that have been running around my head:
> >
> > 1.  Following on from the discussion last week about trying to
> > synchronize multiple oscillators to improve phase noise,
> I've wondered
> > about a simpler tack:  take, for example, two 5 MHz atomic
> standards
> > and mix their outputs together, using the 10 MHz result to drive a
> > time scale.  Assuming the standards were of relatively
> equal quality,
> > would this provide a better time scale than using one of
> the standards alone?
>
> I have been looking at mutual lock systems for say two 10 MHz
> oscillators. This mutual lock system behaves much as a PLL
> circuit (as contrary to the other mutual lock methods
> described previous) such that a phase detector detects the
> phase-difference between the oscillators, a loop filter
> filters this difference and then it is feed back with
> opposite signs to the respective oscillator. I envision that
> a common EFC input exists to the system. Such a system is
> kind of interesting in that within the PLL bandwidth, the two
> oscillators are locked and you see the average of frequency
> errors etc. Well above the PLL bandwidth the two oscillators
> is independent of each other and just above the PLL bandwidth
> they are essentially independent. As the two oscillators is
> phase-locked in, their outputs can be combined and noise
> reduction can be achived, which is the significant effect
> above the PLL bandwidth.
>

This is similar to the problems of synchronizing multiple AC generators connected to a common bus. In that application, you typically adjust the throttle on the prime mover (or penstock gate for hydro) for each generator, while keeping a stable system frequency.  This is a very difficult problem because of the nonlinearity and time delays inherent in the system, not to mention the fact that there's transmission lines involved and a varying load.  The transients on long transmission paths (like from pacific northwest to southern California) can take many hours to die out.

There have been notorious oscillation issues in days of yore.. Modern GPS disciplined frequency references makes it easier.. (rather than sync to each other, you all sync to a common master) As do DC links with inverters.


In your case, you're trying to do the mutual synchronization scheme.

Jim


From jra at febo.com  Tue Dec 23 17:57:59 2008
From: jra at febo.com (John Ackermann N8UR)
Date: Tue, 23 Dec 2008 12:57:59 -0500
Subject: [time-nuts] New topics (was Re: He is a
	Time-Nut	Troublemaker....)
In-Reply-To: <49511F18.7050903@rubidium.dyndns.org>
References: <mailman.600.1229917104.2499.time-nuts@febo.com>	<BLU125-W46831CE6F2E119B7EEBE6CCEEF0@phx.gbl>	<494F1DA4.4000106@xtra.co.nz>	<494F969B.1030604@erols.com>	<494FEC59.90905@xtra.co.nz>	<494FF0B8.4030809@xtra.co.nz>	<494FF7B7.2020403@xtra.co.nz>	<495050CE.5020704@pacific.net>	<495083D2.8010503@erols.com>	<49510EA9.5030100@wwrinc.com>	<49511170.2080600@rubidium.dyndns.org>	<49511493.4090803@febo.com>
	<49511F18.7050903@rubidium.dyndns.org>
Message-ID: <495126A7.7080500@febo.com>

Magnus Danielson wrote:

> This diffrential locking technique could be applied to atomic standards, 
> but then naturally require much improved solution than simple 
> oscillators. The diffrential locking technique does not magically solve 
> issues that is typically common mode, such as temperature dependence. It 
> can however even out individual properties like noise and systematic 
> drift to some extent. It essentially runs the oscillators as a common 
> constellation and attempts to achieve the average improvements of those 
> oscillators in an interlocked fashion. In its simplicity it will do 
> unweighed averaging. It is fairly easy to do weighed averaging by 
> individualizing the feedback gain to the respective oscillators. Further 
> refinements would individualize the proportional and integrate feedback 
> terms, but as always, the simplicity forms a limit.

Assuming that the atomic standards are correct for some tolerance of 
"correct", I'm not sure why you would need to use a differential locking 
scheme (or anything else that moves one oscillator versus the other) -- 
if you simply mix the two signals together you get a sum that contains 
both signals.  Apart from redundancy (what if one unit fails), why not 
just use that sum to drive the clock?

John


From magnus at rubidium.dyndns.org  Tue Dec 23 18:03:06 2008
From: magnus at rubidium.dyndns.org (Magnus Danielson)
Date: Tue, 23 Dec 2008 19:03:06 +0100
Subject: [time-nuts] New topics (was Re: He is
	a	Time-Nut	Troublemaker....)
In-Reply-To: <495126A7.7080500@febo.com>
References: <mailman.600.1229917104.2499.time-nuts@febo.com>	<BLU125-W46831CE6F2E119B7EEBE6CCEEF0@phx.gbl>	<494F1DA4.4000106@xtra.co.nz>	<494F969B.1030604@erols.com>	<494FEC59.90905@xtra.co.nz>	<494FF0B8.4030809@xtra.co.nz>	<494FF7B7.2020403@xtra.co.nz>	<495050CE.5020704@pacific.net>	<495083D2.8010503@erols.com>	<49510EA9.5030100@wwrinc.com>	<49511170.2080600@rubidium.dyndns.org>	<49511493.4090803@febo.com>	<49511F18.7050903@rubidium.dyndns.org>
	<495126A7.7080500@febo.com>
Message-ID: <495127DA.5030903@rubidium.dyndns.org>

John Ackermann N8UR skrev:
> Magnus Danielson wrote:
> 
>> This diffrential locking technique could be applied to atomic standards, 
>> but then naturally require much improved solution than simple 
>> oscillators. The diffrential locking technique does not magically solve 
>> issues that is typically common mode, such as temperature dependence. It 
>> can however even out individual properties like noise and systematic 
>> drift to some extent. It essentially runs the oscillators as a common 
>> constellation and attempts to achieve the average improvements of those 
>> oscillators in an interlocked fashion. In its simplicity it will do 
>> unweighed averaging. It is fairly easy to do weighed averaging by 
>> individualizing the feedback gain to the respective oscillators. Further 
>> refinements would individualize the proportional and integrate feedback 
>> terms, but as always, the simplicity forms a limit.
> 
> Assuming that the atomic standards are correct for some tolerance of 
> "correct", I'm not sure why you would need to use a differential locking 
> scheme (or anything else that moves one oscillator versus the other) -- 
> if you simply mix the two signals together you get a sum that contains 
> both signals.  Apart from redundancy (what if one unit fails), why not 
> just use that sum to drive the clock?

Because they _WILL_ drift appart.

Interlocking them force them to a common frequency and average phase.

Cheers,
Magnus


From hmurray at megapathdsl.net  Tue Dec 23 18:58:58 2008
From: hmurray at megapathdsl.net (Hal Murray)
Date: Tue, 23 Dec 2008 10:58:58 -0800
Subject: [time-nuts] New topics (was Re: He is a Time-Nut
 Troublemaker....)
In-Reply-To: Message from John Ackermann N8UR <jra@febo.com> 
	of "Tue, 23 Dec 2008 11:40:51 EST." <49511493.4090803@febo.com> 
Message-ID: <20081223185859.1FB6BBCD7@ip-64-139-1-69.sjc.megapath.net>


> 2.  Several measurement techniques require a given phase relationship
> (e.g., quadrature) between DUT and reference.  For HF frequencies (ie,
> 5  or 10 MHz) is there a *practical* phase shifter design covering
> 180+  degrees that doesn't involve switching various lengths of coax
> in and  out of the line? 

PLL up by a factor of N, use that to drive a DDS, then filter.  Maybe a pair 
of DDSes will get better tracking.

For each possible phase offset, you need N slots in the table.  (N/4 with 
more work)

-- 
These are my opinions, not necessarily my employer's.  I hate spam.





From james.p.lux at jpl.nasa.gov  Tue Dec 23 19:07:47 2008
From: james.p.lux at jpl.nasa.gov (Lux, James P)
Date: Tue, 23 Dec 2008 11:07:47 -0800
Subject: [time-nuts] New topics (was Re: He is a Time-Nut
 Troublemaker....)
In-Reply-To: <20081223185859.1FB6BBCD7@ip-64-139-1-69.sjc.megapath.net>
References: Message from John Ackermann N8UR <jra@febo.com> 	of "Tue, 23 Dec
	2008 11:40:51 EST." <49511493.4090803@febo.com>
	<20081223185859.1FB6BBCD7@ip-64-139-1-69.sjc.megapath.net>
Message-ID: <ECE7A93BD093E1439C20020FBE87C47FEB55DA90B7@ALTPHYEMBEVSP20.RES.AD.JPL>

Several DDS parts from Analog Devices (e.g. AD9854, which runs quite warm) are dual quadrature.. And have adjustable phase offsets as well.
I think the single DDS parts also have a programmable phase offset of 14-16 bits.  You have to be careful with the configuration bits, so that writing the phase register doesn't zero the phase accumulator.

They're all available as eval boards, too.

> -----Original Message-----
> From: time-nuts-bounces at febo.com
> [mailto:time-nuts-bounces at febo.com] On Behalf Of Hal Murray
> Sent: Tuesday, December 23, 2008 10:59 AM
> To: Discussion of precise time and frequency measurement
> Subject: Re: [time-nuts] New topics (was Re: He is a Time-Nut
> Troublemaker....)
>
>
> > 2.  Several measurement techniques require a given phase
> relationship
> > (e.g., quadrature) between DUT and reference.  For HF
> frequencies (ie,
> > 5  or 10 MHz) is there a *practical* phase shifter design covering
> > 180+  degrees that doesn't involve switching various lengths of coax
> > in and  out of the line?
>
> PLL up by a factor of N, use that to drive a DDS, then
> filter.  Maybe a pair of DDSes will get better tracking.
>
> For each possible phase offset, you need N slots in the
> table.  (N/4 with more work)


From bruce.griffiths at xtra.co.nz  Tue Dec 23 19:47:21 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Wed, 24 Dec 2008 08:47:21 +1300
Subject: [time-nuts] Sub Pico Second Phase logger
In-Reply-To: <p0624080cc575e635b033@[192.168.1.212]>
References: <p0624080cc575e635b033@[192.168.1.212]>
Message-ID: <49514049.3010508@xtra.co.nz>

Joe

Joe Gwinn wrote:
> Bruce,
>
> At 11:43 PM +0000 12/22/08, time-nuts-request at febo.com wrote:
>   
>> Date: Tue, 23 Dec 2008 12:01:40 +1300
>> From: Bruce Griffiths <bruce.griffiths at xtra.co.nz>
>> Subject: Re: [time-nuts] Sub Pico Second Phase logger
>> To: Discussion of precise time and frequency measurement
>> 	<time-nuts at febo.com>
>>
>> [snip]
>>  >> [BG]  Control of the close in spur levels produced by the NCO 
>> may also be an
>>     
>>>>  issue.
>>>>    
>>>>         
>>>  [JG]  If the division ratio is an integer, the spurs are reduced.
>>>
>>>  Analog Devices has a web calculator that's useful for fast
>>>  exploration.  The calculator operation is explained and the reference
>>>  provided in their big tutorial on DDS principles.
>>>
>>>
>>>  
>>>       
>> It's a bit misleading in that it indicates that the performance is
>> impaired when there is no phase truncation spur.
>>     
>
> I just look at the spur chart.
>
>
>   
>> This may well be true for frequencies close to that frequency that has
>> no phase truncation spur, however in this application one wouldn't
>> choose an output frequency that has significant phase truncation spurs.
>>     
>
> The value of the calculator is to look around for such sweet spots.
>
> One can also generate the traditional spur chart, the one with the 
> nest of diagonal lines.
>
>
>   
>>  >>>  I found and read the basic articles, which can be downloaded from
>>     
>>>>>      
>>>>>           
>>>>   > Prof Sotiriadis' website:
>>>>    
>>>>         
>>>>>   <http://www.ece.jhu.edu/~pps/WEB/Publications/pub.html>
>>>>>
>>>>>
>>>>>      
>>>>>           
>>>>  [BG]  There is also US patent 5267182.
>>>>    
>>>>         
>>  > I did find 5,267,182 while searching for Sotiriadis' patent, but
>>     
>>>  forgot to mention it.  Don't know what the difference is.  In the US,
>>>  patent applications are made public after 18 months, or immediately
>>>  if the person is also applying for a European patent.  The US Patent
>>>       
>>  > Office is years behind, so patent issuance may be a while.
>>     
>
> I just read 5,267,182.  It appears to anticipate Sotiriadis in every 
> aspect, so it may be a *long* time before Sotiriadis's patent is 
> issued.
>
>
>   
>>  >>  > Items J10, J13, and J15 seem particularly relevant.
>>     
>>>>   >
>>>>    
>>>>         
>>>>>   All one needs is the M/N chip, although one can certainly use DDS chips.
>>>>>
>>>>>
>>>>>
>>>>>      
>>>>>           
>>>>  Using a DDS avoids the requirement for a pair of low phase noise VCOs.
>>>>    
>>>>         
>>>  If we can control the spurs, many DDS chips are very good.
>>>
>>>  
>>>       
>> A DDS, unlike a conventional digital frequency divider, doesn't suffer
>>     
> >from aliasing of phase noise into the output passband.
>
> How true is this, in practice?  A DDS is at the mercy of phase noise 
> in its reference clock, by much the same mechanism as for a simple 
> divider chain.  And the variable-factor dividers (the M and N above) 
> work in a manner similar to a DDS, but with far coarser increments 
> and limits.  Both DDS and M/N PLL chips use a PLL to clean up the 
> resulting ref signal.  Many DDS chips incorporate a M/N PLL to 
> multiply the ref frequency.
>
>
>   
For NIST's measurements of this effect see:
http://tf.nist.gov/timefreq/general/pdf/1380.pdf
>>  >>  >>  >> A conventional mixer would then be used to either add or 
>> subtract the
>>     
>>>>    
>>>>         
>>>>>>   
>>>>>>        
>>>>>>             
>>>>>>>>    two DDS output frequencies.
>>>>>>>>    If the ratio of the 2 DDS clock source frequencies is appropriately
>>>>>>>>    chosen the spacing between the resultant mixer output 
>>>>>>>> frequencies can be
>>>>>>>>    much finer than the spacing between the truncation spur 
>>>>>>>> free outputs of
>>>>>>>>    either DDS chip.
>>>>>>>>    The DDS and mixer outputs should be filtered to remove harmonics and
>>>>>>>>    other unwanted frequencies.
>>>>>>>>  
>>>>>>>>       
>>>>>>>>            
>>>>>>>>                 
>>>>>>>    If the DDS chips are well chosen, we will get sin and cos outputs,
>>>>>>>    and so can implement a dual-mixer phasing scheme to yield only the
>>>>>>>               
>>  >>>>>   sum frequency or only the difference frequency, greatly reducing the
>>     
>>>>>>>    amount of filtering needed.  The better balanced the channels are the
>>>>>>>     
>>>>>>>          
>>>>>>>               
>>>>>>    > better the cancellation of the unwanted term.  This is basically the
>>>>>>    > phasing method of single-sideband signal generation.
>>>>>>   
>>>>>>        
>>>>>>             
>>>>>   This would be a reason to use DDS chips instead of M/N PLL chips,
>>>>>   unless there are M/N PLL chips that provide quadrature outputs.
>>>>>           
>>  >>>  SiLabs Si5338 may suffice, as it allows one to control the relative
>>     
>>>>>   phase of its outputs.
>>>>>
>>>>>
>>>>>
>>>>>      
>>>>>           
>>>>  If one were to divide the output frequency of the diophantine
>>>>  synthesizer by 4 using a 2 bit Johnson counter then quadrature phase
>>>>  outputs are available.
>>>>  However the filters used to extract the fundamental from the divider
>>>>  outputs would need to be matched.
>>>>  If the diophantine frequency synthesiser output frequency doesn't vary
>>>>  too much one can always use a quadrature hybrid.
>>>>    
>>>>         
>>>  This seems like a lot of work.  Hmm.  Now that I think of it, the
>>>  SiLabs chips emit square waves (logic signals), not sine waves.  Back
>>>  to DDS chips, it seems.
>>>
>>>  Joe
>>>
>>>
>>>       
>> The simplest way of achieving the required performance is preferable.
>>     
>
> Yes, but aren't we Time Nuts?
>
>   
Usually with finite budgets.

> Joe
>
>   
Bruce


From jra at febo.com  Tue Dec 23 20:28:47 2008
From: jra at febo.com (John Ackermann N8UR)
Date: Tue, 23 Dec 2008 15:28:47 -0500
Subject: [time-nuts] New topics (was Re: He is a Time-Nut
	Troublemaker....)
In-Reply-To: <20081223185859.1FB6BBCD7@ip-64-139-1-69.sjc.megapath.net>
References: <20081223185859.1FB6BBCD7@ip-64-139-1-69.sjc.megapath.net>
Message-ID: <495149FF.3020908@febo.com>

Hal Murray said the following on 12/23/2008 01:58 PM:
>> 2.  Several measurement techniques require a given phase relationship
>> (e.g., quadrature) between DUT and reference.  For HF frequencies (ie,
>> 5  or 10 MHz) is there a *practical* phase shifter design covering
>> 180+  degrees that doesn't involve switching various lengths of coax
>> in and  out of the line? 
> 
> PLL up by a factor of N, use that to drive a DDS, then filter.  Maybe a pair 
> of DDSes will get better tracking.
> 
> For each possible phase offset, you need N slots in the table.  (N/4 with 
> more work)

If doing phase noise or short term stability measurements, wouldn't the
noise of the DDS impact the results?


From magnus at rubidium.dyndns.org  Tue Dec 23 20:37:13 2008
From: magnus at rubidium.dyndns.org (Magnus Danielson)
Date: Tue, 23 Dec 2008 21:37:13 +0100
Subject: [time-nuts] New topics (was Re: He is a
	Time-Nut	Troublemaker....)
In-Reply-To: <495149FF.3020908@febo.com>
References: <20081223185859.1FB6BBCD7@ip-64-139-1-69.sjc.megapath.net>
	<495149FF.3020908@febo.com>
Message-ID: <49514BF9.6010200@rubidium.dyndns.org>

John Ackermann N8UR skrev:
> Hal Murray said the following on 12/23/2008 01:58 PM:
>>> 2.  Several measurement techniques require a given phase relationship
>>> (e.g., quadrature) between DUT and reference.  For HF frequencies (ie,
>>> 5  or 10 MHz) is there a *practical* phase shifter design covering
>>> 180+  degrees that doesn't involve switching various lengths of coax
>>> in and  out of the line? 
>> PLL up by a factor of N, use that to drive a DDS, then filter.  Maybe a pair 
>> of DDSes will get better tracking.
>>
>> For each possible phase offset, you need N slots in the table.  (N/4 with 
>> more work)
> 
> If doing phase noise or short term stability measurements, wouldn't the
> noise of the DDS impact the results?

It would, unless you are able to use a double-mixer approach of some 
sort such that it cancels out.

I was expecting something simpler and quieter, but the usual suspect for 
such solutions has been quitet. A number of different approaches could 
be used naturally. I guess one would prefer a solution where a control 
loop could be created.

Cheers,
Magnus


From bruce.griffiths at xtra.co.nz  Tue Dec 23 20:47:15 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Wed, 24 Dec 2008 09:47:15 +1300
Subject: [time-nuts] New topics (was Re: He is a
	Time-Nut	Troublemaker....)
In-Reply-To: <495149FF.3020908@febo.com>
References: <20081223185859.1FB6BBCD7@ip-64-139-1-69.sjc.megapath.net>
	<495149FF.3020908@febo.com>
Message-ID: <49514E53.3070200@xtra.co.nz>

John Ackermann N8UR wrote:
> Hal Murray said the following on 12/23/2008 01:58 PM:
>   
>>> 2.  Several measurement techniques require a given phase relationship
>>> (e.g., quadrature) between DUT and reference.  For HF frequencies (ie,
>>> 5  or 10 MHz) is there a *practical* phase shifter design covering
>>> 180+  degrees that doesn't involve switching various lengths of coax
>>> in and  out of the line? 
>>>       
>> PLL up by a factor of N, use that to drive a DDS, then filter.  Maybe a pair 
>> of DDSes will get better tracking.
>>
>> For each possible phase offset, you need N slots in the table.  (N/4 with 
>> more work)
>>     
>
> If doing phase noise or short term stability measurements, wouldn't the
> noise of the DDS impact the results?
>
>   
John

Split the signal to be measured, use 2 independent DDS circuits, 2
mixers and measure the cross power spectrum of the 2 mixer outputs.
This should only measure the noise common to both channels.
Should be easy to do with a sound card for example.
The phase noise of other non common components such as isolation
amplifiers should also cancel.

Bruce


From james.p.lux at jpl.nasa.gov  Tue Dec 23 20:57:27 2008
From: james.p.lux at jpl.nasa.gov (Lux, James P)
Date: Tue, 23 Dec 2008 12:57:27 -0800
Subject: [time-nuts] New topics (was Re: He is a
	Time-Nut	Troublemaker....)
In-Reply-To: <495149FF.3020908@febo.com>
References: <20081223185859.1FB6BBCD7@ip-64-139-1-69.sjc.megapath.net>
	<495149FF.3020908@febo.com>
Message-ID: <ECE7A93BD093E1439C20020FBE87C47FEB55DA90D0@ALTPHYEMBEVSP20.RES.AD.JPL>


> [mailto:time-nuts-bounces at febo.com] On Behalf Of John Ackermann N8UR
> Sent: Tuesday, December 23, 2008 12:29 PM
> To: Discussion of precise time and frequency measurement
> Subject: Re: [time-nuts] New topics (was Re: He is a Time-Nut
> Troublemaker....)
>
> Hal Murray said the following on 12/23/2008 01:58 PM:
> >> 2.  Several measurement techniques require a given phase
> relationship
> >> (e.g., quadrature) between DUT and reference.  For HF frequencies
> >> (ie,
> >> 5  or 10 MHz) is there a *practical* phase shifter design covering
> >> 180+  degrees that doesn't involve switching various
> lengths of coax
> >> in and  out of the line?
> >
> > PLL up by a factor of N, use that to drive a DDS, then
> filter.  Maybe
> > a pair of DDSes will get better tracking.
> >
> > For each possible phase offset, you need N slots in the
> table.  (N/4
> > with more work)
>
> If doing phase noise or short term stability measurements,
> wouldn't the noise of the DDS impact the results?
>

I would assume that one could have enough bits in the DDS phase accumulator AND in the DAC (and potentially use various error feedback/feedforward schemes) to get the noise low enough.  Vankka's papers (and book, for that matter) talk about "how low you can go" with this sort of thing.

Maybe not, though.. There's always going to be some noise added to that of the reference you're feeding in. Might be small, but it's not non-zero.  For instance, a 16 bit DAC adds quantization noise at roughly -96dBFS. (there's actualy a correction of a dB or two, because quantization noise is uniformly distributed over an interval, not gaussian). It's spread evenly, so the power spectral density is low.  If the clock's running at 200MHz, the noise is spread over 100 MHz, so -96-80 dBFS/Hz or -176 dBFS/Hz (how's that for an odd unit?)

That's pretty good, in any case.

(for more real numbers.. AD9954 is a 14bit DAC, 32 bit phase accumulator, etc.  And says -120dB/Hz phase noise on the datasheet cover.. -132dBc/hz at 1kHz away from a 40MHz outpt with 400MHz clkin. The 9910 gives -125dBc/Hz at 1kHz away from a 400MHz carrier w/1GHz in. Divide that down to 10 MHz and you'll pick up, what, about 32 dB more.. -157dBc/Hz

The datasheet says residual phase noise at 20MHz out, 1kHz away, is -152 dBc/Hz, presumably with 1GHz in.  Looking at Figure 15, it looks like it's about -135 at 10 Hz away, -145 at 100Hz, down to a floor around -165dBc/Hz around 50 kHz away.


From hmurray at megapathdsl.net  Tue Dec 23 21:13:29 2008
From: hmurray at megapathdsl.net (Hal Murray)
Date: Tue, 23 Dec 2008 13:13:29 -0800
Subject: [time-nuts] New topics (was Re: He is a Time-Nut
 Troublemaker....)
In-Reply-To: Message from John Ackermann N8UR <jra@febo.com> 
	of "Tue, 23 Dec 2008 15:28:47 EST." <495149FF.3020908@febo.com> 
Message-ID: <20081223211330.62283BCD7@ip-64-139-1-69.sjc.megapath.net>


>> PLL up by a factor of N, use that to drive a DDS, then filter.  Maybe
>> a pair of DDSes will get better tracking.

>> For each possible phase offset, you need N slots in the table.  (N/4
>> with more work)

> If doing phase noise or short term stability measurements, wouldn't
> the noise of the DDS impact the results?

I'm not a wizard on this stuff.  I think there are 2 sources of errors in 
traditional DDSes.  One is round off errors in the sin/cos tables (and D/A).  
The other is spurs because the step size on the index into the table isn't 
constant.  (It's mostly X, but occasionally X+1 or X-1)

I think the spurs depend upon N and who designs the table.

If you use an all-in-one DDS chip, you get their choices.  I think it will 
work cleanly if N is a power of 2 so there are no low bits in the accumulator.

If you design your own, you can use a not-quite traditional DDS.  Say N is 5 
so you have 5 steps per cycle.  Just count up from 0 and reset when you get 
to 4.  That's 3 bits.  Suppose you want 0-360 phase offset by 1 degree steps. 
 That's 9 bits.  So you need a ROM with 12 bits of addressing, 4K.

I think the round off errors will not be a serious problem.  You are making a 
signal with a clean period, no spurs.  You won't make a perfect sine wave, 
but you can filter out the harmonics.

Did I get that right?


-- 
These are my opinions, not necessarily my employer's.  I hate spam.





From bruce.griffiths at xtra.co.nz  Tue Dec 23 22:16:25 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Wed, 24 Dec 2008 11:16:25 +1300
Subject: [time-nuts] New topics (was Re: He is a
	Time-Nut	Troublemaker....)
In-Reply-To: <495149FF.3020908@febo.com>
References: <20081223185859.1FB6BBCD7@ip-64-139-1-69.sjc.megapath.net>
	<495149FF.3020908@febo.com>
Message-ID: <49516339.9090000@xtra.co.nz>

John Ackermann N8UR wrote:
> Hal Murray said the following on 12/23/2008 01:58 PM:
>   
>>> 2.  Several measurement techniques require a given phase relationship
>>> (e.g., quadrature) between DUT and reference.  For HF frequencies (ie,
>>> 5  or 10 MHz) is there a *practical* phase shifter design covering
>>> 180+  degrees that doesn't involve switching various lengths of coax
>>> in and  out of the line? 
>>>       
>> PLL up by a factor of N, use that to drive a DDS, then filter.  Maybe a pair 
>> of DDSes will get better tracking.
>>
>> For each possible phase offset, you need N slots in the table.  (N/4 with 
>> more work)
>>     
>
> If doing phase noise or short term stability measurements, wouldn't the
> noise of the DDS impact the results?
>
>   
John

When measuring the phase noise of amplifiers and other devices with
relatively low phase shifts at 10MHz (or 5MHz) one can start with a
quadrature hybrid to produce test and reference signals in approximate
quadrature. One then only has to compensate for the UUT delay using an
splitter an, attenuator and another quadrature hybrid to produce the
small phase shift required.
One can even use a mixer as a dc controlled attenuator for the fine
phase adjustment to interpolate between attenuator steps.

Bruce


From magnus at rubidium.dyndns.org  Tue Dec 23 22:23:38 2008
From: magnus at rubidium.dyndns.org (Magnus Danielson)
Date: Tue, 23 Dec 2008 23:23:38 +0100
Subject: [time-nuts] New topics (was Re: He is
	a	Time-Nut	Troublemaker....)
In-Reply-To: <49516339.9090000@xtra.co.nz>
References: <20081223185859.1FB6BBCD7@ip-64-139-1-69.sjc.megapath.net>	<495149FF.3020908@febo.com>
	<49516339.9090000@xtra.co.nz>
Message-ID: <495164EA.1040905@rubidium.dyndns.org>

Bruce Griffiths skrev:
> John Ackermann N8UR wrote:
>> Hal Murray said the following on 12/23/2008 01:58 PM:
>>   
>>>> 2.  Several measurement techniques require a given phase relationship
>>>> (e.g., quadrature) between DUT and reference.  For HF frequencies (ie,
>>>> 5  or 10 MHz) is there a *practical* phase shifter design covering
>>>> 180+  degrees that doesn't involve switching various lengths of coax
>>>> in and  out of the line? 
>>>>       
>>> PLL up by a factor of N, use that to drive a DDS, then filter.  Maybe a pair 
>>> of DDSes will get better tracking.
>>>
>>> For each possible phase offset, you need N slots in the table.  (N/4 with 
>>> more work)
>>>     
>> If doing phase noise or short term stability measurements, wouldn't the
>> noise of the DDS impact the results?
>>
>>   
> John
> 
> When measuring the phase noise of amplifiers and other devices with
> relatively low phase shifts at 10MHz (or 5MHz) one can start with a
> quadrature hybrid to produce test and reference signals in approximate
> quadrature. One then only has to compensate for the UUT delay using an
> splitter an, attenuator and another quadrature hybrid to produce the
> small phase shift required.
> One can even use a mixer as a dc controlled attenuator for the fine
> phase adjustment to interpolate between attenuator steps.

Using two mixers programmed by two individual DC signals the quadrature 
signal can be setup to arbitrary phase shift. It is trivial to combine 
programmed damping and phase-shift in this fashion.

Cheers,
Magnus


From bruce.griffiths at xtra.co.nz  Tue Dec 23 22:38:28 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Wed, 24 Dec 2008 11:38:28 +1300
Subject: [time-nuts] New topics (was Re: He
	is	a	Time-Nut	Troublemaker....)
In-Reply-To: <495164EA.1040905@rubidium.dyndns.org>
References: <20081223185859.1FB6BBCD7@ip-64-139-1-69.sjc.megapath.net>	<495149FF.3020908@febo.com>	<49516339.9090000@xtra.co.nz>
	<495164EA.1040905@rubidium.dyndns.org>
Message-ID: <49516864.4060906@xtra.co.nz>

Magnus Danielson wrote:
> Bruce Griffiths skrev:
>   
>> John Ackermann N8UR wrote:
>>     
>>> Hal Murray said the following on 12/23/2008 01:58 PM:
>>>   
>>>       
>>>>> 2.  Several measurement techniques require a given phase relationship
>>>>> (e.g., quadrature) between DUT and reference.  For HF frequencies (ie,
>>>>> 5  or 10 MHz) is there a *practical* phase shifter design covering
>>>>> 180+  degrees that doesn't involve switching various lengths of coax
>>>>> in and  out of the line? 
>>>>>       
>>>>>           
>>>> PLL up by a factor of N, use that to drive a DDS, then filter.  Maybe a pair 
>>>> of DDSes will get better tracking.
>>>>
>>>> For each possible phase offset, you need N slots in the table.  (N/4 with 
>>>> more work)
>>>>     
>>>>         
>>> If doing phase noise or short term stability measurements, wouldn't the
>>> noise of the DDS impact the results?
>>>
>>>   
>>>       
>> John
>>
>> When measuring the phase noise of amplifiers and other devices with
>> relatively low phase shifts at 10MHz (or 5MHz) one can start with a
>> quadrature hybrid to produce test and reference signals in approximate
>> quadrature. One then only has to compensate for the UUT delay using an
>> splitter an, attenuator and another quadrature hybrid to produce the
>> small phase shift required.
>> One can even use a mixer as a dc controlled attenuator for the fine
>> phase adjustment to interpolate between attenuator steps.
>>     
>
> Using two mixers programmed by two individual DC signals the quadrature 
> signal can be setup to arbitrary phase shift. It is trivial to combine 
> programmed damping and phase-shift in this fashion.
>
> Cheers,
> Magnus
>
>   
Hej Magnus


See patent US3803499 for one implementation of this scheme.**

**However, where possible, a lower noise more stable system usually
results when the phase shift provided by such a system is relatively
small.**

**Bruce


From magnus at rubidium.dyndns.org  Wed Dec 24 00:10:40 2008
From: magnus at rubidium.dyndns.org (Magnus Danielson)
Date: Wed, 24 Dec 2008 01:10:40 +0100
Subject: [time-nuts] New topics (was Re:
	He	is	a	Time-Nut	Troublemaker....)
In-Reply-To: <49516864.4060906@xtra.co.nz>
References: <20081223185859.1FB6BBCD7@ip-64-139-1-69.sjc.megapath.net>	<495149FF.3020908@febo.com>	<49516339.9090000@xtra.co.nz>	<495164EA.1040905@rubidium.dyndns.org>
	<49516864.4060906@xtra.co.nz>
Message-ID: <49517E00.5020200@rubidium.dyndns.org>

Hej Bruce,

> See patent US3803499 for one implementation of this scheme.**

Using a quadrature hybrid to combine the two signals and achive the 90 
degrees offset is one of several approaches. It is however just a matter 
of trigonometry at work.

> **However, where possible, a lower noise more stable system usually
> results when the phase shift provided by such a system is relatively
> small.**

There is something about that sentence that does not compute.

Cheers,
Magnus


From bruce.griffiths at xtra.co.nz  Wed Dec 24 00:24:02 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Wed, 24 Dec 2008 13:24:02 +1300
Subject: [time-nuts] New topics (was
	Re:	He	is	a	Time-Nut	Troublemaker....)
In-Reply-To: <49517E00.5020200@rubidium.dyndns.org>
References: <20081223185859.1FB6BBCD7@ip-64-139-1-69.sjc.megapath.net>	<495149FF.3020908@febo.com>	<49516339.9090000@xtra.co.nz>	<495164EA.1040905@rubidium.dyndns.org>	<49516864.4060906@xtra.co.nz>
	<49517E00.5020200@rubidium.dyndns.org>
Message-ID: <49518122.2010908@xtra.co.nz>

Magnus Danielson wrote:
> Hej Bruce,
>
>   
>> See patent US3803499 for one implementation of this scheme.**
>>     
>
> Using a quadrature hybrid to combine the two signals and achive the 90 
> degrees offset is one of several approaches. It is however just a matter 
> of trigonometry at work.
>
>   
>> **However, where possible, a lower noise more stable system usually
>> results when the phase shift provided by such a system is relatively
>> small.**
>>     
>
> There is something about that sentence that does not compute.
>
> Cheers,
> Magnus
>
>   
Hej Magnus

Rephrasing:
A lower noise system with less phase instability due to the variable RF
gain mixer is possible when the phase shift contribution from the
circuit branch including said mixer is small.

Bruce


From magnus at rubidium.dyndns.org  Wed Dec 24 00:32:24 2008
From: magnus at rubidium.dyndns.org (Magnus Danielson)
Date: Wed, 24 Dec 2008 01:32:24 +0100
Subject: [time-nuts] New topics
	(was	Re:	He	is	a	Time-Nut	Troublemaker....)
In-Reply-To: <49518122.2010908@xtra.co.nz>
References: <20081223185859.1FB6BBCD7@ip-64-139-1-69.sjc.megapath.net>	<495149FF.3020908@febo.com>	<49516339.9090000@xtra.co.nz>	<495164EA.1040905@rubidium.dyndns.org>	<49516864.4060906@xtra.co.nz>	<49517E00.5020200@rubidium.dyndns.org>
	<49518122.2010908@xtra.co.nz>
Message-ID: <49518318.9090302@rubidium.dyndns.org>

Hej Bruce,

> Rephrasing:
> A lower noise system with less phase instability due to the variable RF
> gain mixer is possible when the phase shift contribution from the
> circuit branch including said mixer is small.

Should I interprent this as when the phase shifts near 0, 90, 180 and 
270 degrees has less noise than other phase shifts? Would make sense, 
but question is how much worse it gets.

Cheers,
Magnus


From jgd at johngsbbq.com  Wed Dec 24 00:43:25 2008
From: jgd at johngsbbq.com (Neon John)
Date: Tue, 23 Dec 2008 19:43:25 -0500
Subject: [time-nuts] He is a Time-Nut Troublemaker....
In-Reply-To: <49511170.2080600@rubidium.dyndns.org>
References: <mailman.600.1229917104.2499.time-nuts@febo.com>	<BLU125-W46831CE6F2E119B7EEBE6CCEEF0@phx.gbl>	<494F1DA4.4000106@xtra.co.nz>	<494F969B.1030604@erols.com>	<494FEC59.90905@xtra.co.nz>	<494FF0B8.4030809@xtra.co.nz>	<494FF7B7.2020403@xtra.co.nz>	<495050CE.5020704@pacific.net>	<495083D2.8010503@erols.com>
	<49510EA9.5030100@wwrinc.com>
	<49511170.2080600@rubidium.dyndns.org>
Message-ID: <5o03l4hv0qv05gi4m35j6ef9alepin16h1@4ax.com>

On Tue, 23 Dec 2008 17:27:28 +0100, Magnus Danielson
<magnus at rubidium.dyndns.org> wrote:

>David M. Witten II skrev:
>> Points of pride, I'm sure.
>
>All this talk still does not make me feel like going out and get a 
>firearm of any sort, fashinating as they can be in their own right.
>
>If someone got me involved in elk-hunting maybe, but that's about it I 
>think.

I got the hunting thing out of my blood when I was still a teenager.  I'm now
a precision shooter and a shooting nerd.  Shooting can be very exciting to the
type that populate this list.  Internal ballistics, external ballistics,
statistics, precision mechanics, precision electronics, etc.

Ballistics timing is fast enough that you get to play with the things that
concern time-nuts.  I have, for example, drilled an old barrel and inserted
conductive probes every inch.  The bullet passing by makes up the circuit. The
probes were arranged in an R/2R D/A converter circuit so that I could digitize
them all with one fast A/D converter.  I wanted to watch the acceleration of
the bullet down the barrel and compare it to chamber pressure.

I learned that what I suspected was true, that with some powder loads, the
acceleration process is over before the bullet exits the muzzle and that
during the last few inches, the bullet was actually slowing from friction.

It also explained why I could get almost as much velocity out of my .308 bolt
action silhouette pistol with the 14" barrel as I could from my M-14,
optimized power and powder weight for the pistol, of course.

Finally, of course, there is the pride of accomplishment of achieving results
that few others in the world can do.  Similar to achieving the best amateurs
have done with time measurements.

There are lots and lots of things a nerd can do with a firearm other than just
shoot at things.

John
--
John De Armond
See my website for my current email address
http://www.neon-john.com
http://www.johndearmond.com <-- best little blog on the net!
Tellico Plains, Occupied TN
Some people are like a Slinky .. not really good for anything
 but you still smile 
when you shove them down the stairs.



From didier at cox.net  Wed Dec 24 00:47:19 2008
From: didier at cox.net (Didier)
Date: Tue, 23 Dec 2008 18:47:19 -0600
Subject: [time-nuts] New topics (was Re: He
	isa	Time-Nut	Troublemaker....)
In-Reply-To: <495127DA.5030903@rubidium.dyndns.org>
References: <mailman.600.1229917104.2499.time-nuts@febo.com>	<BLU125-W46831CE6F2E119B7EEBE6CCEEF0@phx.gbl>	<494F1DA4.4000106@xtra.co.nz>	<494F969B.1030604@erols.com>	<494FEC59.90905@xtra.co.nz>	<494FF0B8.4030809@xtra.co.nz>	<494FF7B7.2020403@xtra.co.nz>	<495050CE.5020704@pacific.net>	<495083D2.8010503@erols.com>	<49510EA9.5030100@wwrinc.com>	<49511170.2080600@rubidium.dyndns.org>	<49511493.4090803@febo.com>	<49511F18.7050903@rubidium.dyndns.org><495126A7.7080500@febo.com>
	<495127DA.5030903@rubidium.dyndns.org>
Message-ID: <0C1BA262774A4C0289449218537A9D61@didierhp>

John,

When you add two (statistically independent) 5 MHz signals and get a 10MHz
signal, the 10 MHz signal's *relative* noise and drift will be the average
of the *relative* noise and drift of the two 5 MHz signals. So as when you
average n signals, the noise and drift are reduced by sq.rt of n, in this
case, 1.4, or about 2dB (if I am correct), a modest improvement. 

Combining more than 2 signals that way (to get more than 2dB improvement)
gets complicated in a hurry.

I guess the idea behind differential locking was to simplify the circuit so
that a large n could be used to get meaningful improvement without too much
additional circuitry.

Didier KO4BB

> -----Original Message-----
> From: time-nuts-bounces at febo.com 
> [mailto:time-nuts-bounces at febo.com] On Behalf Of Magnus Danielson
> Sent: Tuesday, December 23, 2008 12:03 PM
> To: Discussion of precise time and frequency measurement
> Subject: Re: [time-nuts] New topics (was Re: He isa Time-Nut 
> Troublemaker....)
> 
> John Ackermann N8UR skrev:
> > Magnus Danielson wrote:
> > 
> >> This diffrential locking technique could be applied to atomic 
> >> standards, but then naturally require much improved solution than 
> >> simple oscillators. The diffrential locking technique does not 
> >> magically solve issues that is typically common mode, such as 
> >> temperature dependence. It can however even out individual 
> properties 
> >> like noise and systematic drift to some extent. It 
> essentially runs 
> >> the oscillators as a common constellation and attempts to 
> achieve the 
> >> average improvements of those oscillators in an 
> interlocked fashion. 
> >> In its simplicity it will do unweighed averaging. It is 
> fairly easy 
> >> to do weighed averaging by individualizing the feedback 
> gain to the 
> >> respective oscillators. Further refinements would 
> individualize the 
> >> proportional and integrate feedback terms, but as always, 
> the simplicity forms a limit.
> > 
> > Assuming that the atomic standards are correct for some 
> tolerance of 
> > "correct", I'm not sure why you would need to use a differential 
> > locking scheme (or anything else that moves one oscillator 
> versus the 
> > other) -- if you simply mix the two signals together you get a sum 
> > that contains both signals.  Apart from redundancy (what if 
> one unit 
> > fails), why not just use that sum to drive the clock?
> 
> Because they _WILL_ drift appart.
> 
> Interlocking them force them to a common frequency and average phase.
> 
> Cheers,
> Magnus
> 
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com To unsubscribe, 
> go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
> 



From magnus at rubidium.dyndns.org  Wed Dec 24 01:04:38 2008
From: magnus at rubidium.dyndns.org (Magnus Danielson)
Date: Wed, 24 Dec 2008 02:04:38 +0100
Subject: [time-nuts] New topics (was Re:
	He	isa	Time-Nut	Troublemaker....)
In-Reply-To: <0C1BA262774A4C0289449218537A9D61@didierhp>
References: <mailman.600.1229917104.2499.time-nuts@febo.com>	<BLU125-W46831CE6F2E119B7EEBE6CCEEF0@phx.gbl>	<494F1DA4.4000106@xtra.co.nz>	<494F969B.1030604@erols.com>	<494FEC59.90905@xtra.co.nz>	<494FF0B8.4030809@xtra.co.nz>	<494FF7B7.2020403@xtra.co.nz>	<495050CE.5020704@pacific.net>	<495083D2.8010503@erols.com>	<49510EA9.5030100@wwrinc.com>	<49511170.2080600@rubidium.dyndns.org>	<49511493.4090803@febo.com>	<49511F18.7050903@rubidium.dyndns.org><495126A7.7080500@febo.com>	<495127DA.5030903@rubidium.dyndns.org>
	<0C1BA262774A4C0289449218537A9D61@didierhp>
Message-ID: <49518AA6.90401@rubidium.dyndns.org>

Didier skrev:
> John,
> 
> When you add two (statistically independent) 5 MHz signals and get a 10MHz
> signal, the 10 MHz signal's *relative* noise and drift will be the average
> of the *relative* noise and drift of the two 5 MHz signals.

Not to ruin your analogy here, but what I was discussing on interlocking 
was intended as means to phase-lock the two oscillators (say 5 MHz but I 
was thinking 10 MHz) and you could then just add their sines, not mix 
them up. Thus, you do not get the sum frequency, you get the average 
frequency. Of course you could go for the frequency multiplication 
variant if you want.

> So as when you average n signals, the noise and drift are reduced by sq.rt of n, in this
> case, 1.4, or about 2dB (if I am correct), a modest improvement. 

Square root of 2 is about 1,414 or about 3,01 dB.

> Combining more than 2 signals that way (to get more than 2dB improvement)
> gets complicated in a hurry.

Actually no. Not really. You can build pairs and then interconnect them 
together the same way to form a quad, and so you go on. The neat thing 
is that the combined oscillators behave as a new oscillator. This is a 
very traditional way of combining sources to reduce noise. It is 
certainly not new.

> I guess the idea behind differential locking was to simplify the circuit so
> that a large n could be used to get meaningful improvement without too much
> additional circuitry.

Indeed.

Cheers,
Magnus


From bruce.griffiths at xtra.co.nz  Wed Dec 24 01:13:12 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Wed, 24 Dec 2008 14:13:12 +1300
Subject: [time-nuts] New
	topics	(was	Re:	He	is	a	Time-Nut	Troublemaker....)
In-Reply-To: <49518318.9090302@rubidium.dyndns.org>
References: <20081223185859.1FB6BBCD7@ip-64-139-1-69.sjc.megapath.net>	<495149FF.3020908@febo.com>	<49516339.9090000@xtra.co.nz>	<495164EA.1040905@rubidium.dyndns.org>	<49516864.4060906@xtra.co.nz>	<49517E00.5020200@rubidium.dyndns.org>	<49518122.2010908@xtra.co.nz>
	<49518318.9090302@rubidium.dyndns.org>
Message-ID: <49518CA8.6080400@xtra.co.nz>

Magnus Danielson wrote:
> Hej Bruce,
>
>   
>> Rephrasing:
>> A lower noise system with less phase instability due to the variable RF
>> gain mixer is possible when the phase shift contribution from the
>> circuit branch including said mixer is small.
>>     
>
> Should I interprent this as when the phase shifts near 0, 90, 180 and 
> 270 degrees has less noise than other phase shifts? Would make sense, 
> but question is how much worse it gets.
>
> Cheers,
> Magnus
>
>   
Hej Magnus

Thats true, but I had the more general case in mind wherein which one
adds coarse fixed delay increments as required and merely uses the
variable gain mixer to make a fine adjustment to the phase.
No real need for sine and cosine weighting for small phase adjustments
as the effect on the amplitude will be small and phase noise measurement
systems are usually relatively insensitive to AM.

Bruce


From magnus at rubidium.dyndns.org  Wed Dec 24 01:33:01 2008
From: magnus at rubidium.dyndns.org (Magnus Danielson)
Date: Wed, 24 Dec 2008 02:33:01 +0100
Subject: [time-nuts]
	New	topics	(was	Re:	He	is	a	Time-Nut	Troublemaker....)
In-Reply-To: <49518CA8.6080400@xtra.co.nz>
References: <20081223185859.1FB6BBCD7@ip-64-139-1-69.sjc.megapath.net>	<495149FF.3020908@febo.com>	<49516339.9090000@xtra.co.nz>	<495164EA.1040905@rubidium.dyndns.org>	<49516864.4060906@xtra.co.nz>	<49517E00.5020200@rubidium.dyndns.org>	<49518122.2010908@xtra.co.nz>	<49518318.9090302@rubidium.dyndns.org>
	<49518CA8.6080400@xtra.co.nz>
Message-ID: <4951914D.1000107@rubidium.dyndns.org>

Hej Bruce,

> Hej Magnus
> 
> Thats true, but I had the more general case in mind wherein which one
> adds coarse fixed delay increments as required and merely uses the
> variable gain mixer to make a fine adjustment to the phase.

How do you intend that to work? Slightly introduce the signal with a 
different but nearby phase?

> No real need for sine and cosine weighting for small phase adjustments
> as the effect on the amplitude will be small and phase noise measurement
> systems are usually relatively insensitive to AM.

Certainly, but various delay-adjustments will provide different output 
levels, which can be handled in a sub-sequent scaling or by weighing the 
signal of different levels.

To achieve an arbitrary (0-360 degree) phase-shift with such a system 
may be a viable question. Running a set of cables and a programable 
multiplexer of some sort would be possible.

Well, that was not what was asked for originally, and also not apparent 
from your original comment. Surely you can achieve better performance 
than this quad-phase circuit provides, but since it was not described 
what type of circuit you intended it never became clear what you meant.

The original question infact was for a system where you do not use fixed 
delays such as cables.

Cheers,
Magnus


From had at to-way.com  Wed Dec 24 01:48:58 2008
From: had at to-way.com (Had)
Date: Tue, 23 Dec 2008 17:48:58 -0800
Subject: [time-nuts] He is a Time-Nut Troublemaker....
In-Reply-To: <5o03l4hv0qv05gi4m35j6ef9alepin16h1@4ax.com>
References: <mailman.600.1229917104.2499.time-nuts@febo.com>
	<BLU125-W46831CE6F2E119B7EEBE6CCEEF0@phx.gbl>
	<494F1DA4.4000106@xtra.co.nz> <494F969B.1030604@erols.com>
	<494FEC59.90905@xtra.co.nz> <494FF0B8.4030809@xtra.co.nz>
	<494FF7B7.2020403@xtra.co.nz> <495050CE.5020704@pacific.net>
	<495083D2.8010503@erols.com> <49510EA9.5030100@wwrinc.com>
	<49511170.2080600@rubidium.dyndns.org>
	<5o03l4hv0qv05gi4m35j6ef9alepin16h1@4ax.com>
Message-ID: <20081224014901.5227E98D9F3@mail-in05.adhost.com>


John,

Just so won't feel alone on this list; I, also am a 'shooter' and 
have many things that go BANG, besides reverse polarity 
electrolytics. I'm a handgun target and combat nut. Of corse I load 
all own ammo.

Hadley
K7MLR


At 04:43 PM 12/23/2008, you wrote:
>On Tue, 23 Dec 2008 17:27:28 +0100, Magnus Danielson
><magnus at rubidium.dyndns.org> wrote:
>
> >David M. Witten II skrev:
> >> Points of pride, I'm sure.
> >
> >All this talk still does not make me feel like going out and get a
> >firearm of any sort, fashinating as they can be in their own right.
> >
> >If someone got me involved in elk-hunting maybe, but that's about it I
> >think.
>
>I got the hunting thing out of my blood when I was still a teenager.  I'm now
>a precision shooter and a shooting nerd.  Shooting can be very exciting to the
>type that populate this list.  Internal ballistics, external ballistics,
>statistics, precision mechanics, precision electronics, etc.
>
>Ballistics timing is fast enough that you get to play with the things that
>concern time-nuts.  I have, for example, drilled an old barrel and inserted
>conductive probes every inch.  The bullet passing by makes up the circuit. The
>probes were arranged in an R/2R D/A converter circuit so that I could digitize
>them all with one fast A/D converter.  I wanted to watch the acceleration of
>the bullet down the barrel and compare it to chamber pressure.
>
>I learned that what I suspected was true, that with some powder loads, the
>acceleration process is over before the bullet exits the muzzle and that
>during the last few inches, the bullet was actually slowing from friction.
>
>It also explained why I could get almost as much velocity out of my .308 bolt
>action silhouette pistol with the 14" barrel as I could from my M-14,
>optimized power and powder weight for the pistol, of course.
>
>Finally, of course, there is the pride of accomplishment of achieving results
>that few others in the world can do.  Similar to achieving the best amateurs
>have done with time measurements.
>
>There are lots and lots of things a nerd can do with a firearm other than just
>shoot at things.
>
>John
>--
>John De Armond
>See my website for my current email address
>http://www.neon-john.com
>http://www.johndearmond.com <-- best little blog on the net!
>Tellico Plains, Occupied TN
>Some people are like a Slinky .. not really good for anything
>  but you still smile
>when you shove them down the stairs.
>
>
>_______________________________________________
>time-nuts mailing list -- time-nuts at febo.com
>To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>and follow the instructions there.

From sar10538 at gmail.com  Wed Dec 24 02:26:28 2008
From: sar10538 at gmail.com (Steve Rooke)
Date: Wed, 24 Dec 2008 15:26:28 +1300
Subject: [time-nuts] He is a Time-Nut Troublemaker....
In-Reply-To: <20081224014901.5227E98D9F3@mail-in05.adhost.com>
References: <mailman.600.1229917104.2499.time-nuts@febo.com>
	<494FEC59.90905@xtra.co.nz> <494FF0B8.4030809@xtra.co.nz>
	<494FF7B7.2020403@xtra.co.nz> <495050CE.5020704@pacific.net>
	<495083D2.8010503@erols.com> <49510EA9.5030100@wwrinc.com>
	<49511170.2080600@rubidium.dyndns.org>
	<5o03l4hv0qv05gi4m35j6ef9alepin16h1@4ax.com>
	<20081224014901.5227E98D9F3@mail-in05.adhost.com>
Message-ID: <1231b6a80812231826u60a317fao762c87cdca55b91c@mail.gmail.com>

2008/12/24 Had <had at to-way.com>:
> Just so won't feel alone on this list; I, also am a 'shooter' and
> have many things that go BANG, besides reverse polarity
> electrolytics. I'm a handgun target and combat nut. Of corse I load
> all own ammo.

I only shoot in the shower and load my own ammo.

I've always found that NTC resistors, or electrolytics, go really well
across 240Vac and make a decent enough sound of a shotgun when let off
indoors. I wonder if I should measure just how fast people can be made
to move when encouraged by one of these going off.

Bah Humbug, Steve
-- 
Steve Rooke - ZL3TUV & G8KVD & JAKDTTNW
Omnium finis imminet


From bruce.griffiths at xtra.co.nz  Wed Dec 24 02:34:42 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Wed, 24 Dec 2008 15:34:42 +1300
Subject: [time-nuts]
	New	topics	(was	Re:	He	is	a	Time-Nut	Troublemaker....)
In-Reply-To: <4951914D.1000107@rubidium.dyndns.org>
References: <20081223185859.1FB6BBCD7@ip-64-139-1-69.sjc.megapath.net>	<495149FF.3020908@febo.com>	<49516339.9090000@xtra.co.nz>	<495164EA.1040905@rubidium.dyndns.org>	<49516864.4060906@xtra.co.nz>	<49517E00.5020200@rubidium.dyndns.org>	<49518122.2010908@xtra.co.nz>	<49518318.9090302@rubidium.dyndns.org>	<49518CA8.6080400@xtra.co.nz>
	<4951914D.1000107@rubidium.dyndns.org>
Message-ID: <49519FC2.9050802@xtra.co.nz>

Hej Magnus

Magnus Danielson wrote:
> Hej Bruce,
>
>   
>> Hej Magnus
>>
>> Thats true, but I had the more general case in mind wherein which one
>> adds coarse fixed delay increments as required and merely uses the
>> variable gain mixer to make a fine adjustment to the phase.
>>     
>
> How do you intend that to work? Slightly introduce the signal with a 
> different but nearby phase?
>
>   
Simple, use a splitter (0 degree, 90 degree, 180 degree as appropriate)
to separate the signal into 2 parts one for the LO, one for the DUT.
Add some fixed delay to the LO branch then use a 90 degree splitter, 
attenuate the 90 degree  output  and add it (a hybrid combiner/splitter)
to the  0 degree output, thus phase shifting the  final output by a
small adjustable amount.
>> No real need for sine and cosine weighting for small phase adjustments
>> as the effect on the amplitude will be small and phase noise measurement
>> systems are usually relatively insensitive to AM.
>>     
>
> Certainly, but various delay-adjustments will provide different output 
> levels, which can be handled in a sub-sequent scaling or by weighing the 
> signal of different levels.
>   
Probably a simple calibration will suffice when using a saturated mixer
used as a phase detector.
> To achieve an arbitrary (0-360 degree) phase-shift with such a system 
> may be a viable question. Running a set of cables and a programable 
> multiplexer of some sort would be possible.
>
> Well, that was not what was asked for originally, and also not apparent 
> from your original comment. Surely you can achieve better performance 
> than this quad-phase circuit provides, but since it was not described 
> what type of circuit you intended it never became clear what you meant.
>
> The original question infact was for a system where you do not use fixed 
> delays such as cables.
>   
I reinterpreted it to mean that some fixed delays would be OK as long as
they don't have to be accurate to within better than a few nanosec.
In most cases ( eg when measuring isolation amplifier phase noise at
10MHz ) such lumped delays probably wont be necessary as the amplifier
delay will be relatively small.
> Cheers,
> Magnus
>
>   
Bruce


From jmiles at pop.net  Wed Dec 24 07:16:44 2008
From: jmiles at pop.net (John Miles)
Date: Tue, 23 Dec 2008 23:16:44 -0800
Subject: [time-nuts] FS: HP 8663A, near mint
In-Reply-To: <PKEGJHPHLLBACEOICCBJOEFKPGAB.jmiles@pop.net>
Message-ID: <PKEGJHPHLLBACEOICCBJCEMPPPAB.jmiles@pop.net>

I've got a very clean late-production HP 8663A signal generator up for sale,
in case anyone is looking.  This description page will be posted to eBay
next week unless sold offline first:

http://www.ke5fx.com/8663a.htm

Will be packaged safely for shipment in a wooden crate.  Asking $3000, US
sales only.  Not the cheapest one on the market, but unlike typical
8662A/8663As sold on eBay, you will be happy when you get it.

Local pickup also OK (Seattle area).  Thanks!

-- john, KE5FX



From doublebackslash at gmail.com  Wed Dec 24 13:12:38 2008
From: doublebackslash at gmail.com (Trevor Higgins)
Date: Wed, 24 Dec 2008 08:12:38 -0500
Subject: [time-nuts] hello and first questions
Message-ID: <49523546.1000709@gmail.com>

Hello!
Just a couple of backslashes probing the world of insanely accurate time.

My first question, which will doubtlessly lead to many more, is where 
can I find some information on the circuitry to derive the difference 
between two PPS signals and read it in some sort of digital format.
I'd also be interested in finding some information on deriving PPS 
signals from a raw 10Mhz signal, since it seems that rubidium frequency 
standards are a fair bit cheaper than 1PPS standards.
I hope to build my first GPS disciplined atomic standard within a few 
months, learning all sorts of things along the way. Sorry if I'm already 
asking some questions that have obvious answers, but i wanted to start 
on the best possible information out there, and anyone on this list 
probably has the best advice that I could ask for.

I've got a lot of raw potential, and have been feeding my interest in 
timekeeping with a ton of random information for a long time, and it is 
time to do something with it.
Glad to be part of a group that might understand how fascinating this 
all is to me.

Obsessed with all things precise and accurate,
\\


From pvince at theiet.org  Wed Dec 24 14:01:37 2008
From: pvince at theiet.org (Peter Vince)
Date: Wed, 24 Dec 2008 14:01:37 +0000
Subject: [time-nuts] hello and first questions
Message-ID: <49254.1230127297@uk2.net>

Hello Trevor - welcome to the group.

Bruce Griffiths (in New Zealand) is one of our best circuit gurus, and maintains some pages on Didier Juges' web site  
(http://www.ko4bb.com/~bruce/) where you'll find lots of information about the sort of circuitry you are considering.  Didier 
also has a large selection of equipment manuals online at http://www.ko4bb.com/cgi-bin/manuals.pl

Ton van Baak is another expert - see his web site at http://www.leapsecond.com/time-nuts.htm where he has information and 
links to other sites.  And you can check the Time Nuts mailing list archives at  http://www.febo.com/pipermail/time-nuts/

Merry Christmas,

     Peter


On Wed Dec 24 13:12 , Trevor Higgins <doublebackslash at gmail.com> sent:

>Hello!
>Just a couple of backslashes probing the world of insanely accurate time.
>
>My first question, which will doubtlessly lead to many more, is where 
>can I find some information on the circuitry to derive the difference 
>between two PPS signals and read it in some sort of digital format.
>...



From didier at cox.net  Wed Dec 24 14:04:10 2008
From: didier at cox.net (Didier)
Date: Wed, 24 Dec 2008 08:04:10 -0600
Subject: [time-nuts] New topics (was Re: He is a Time-Nut
	Troublemaker....)
In-Reply-To: <49518AA6.90401@rubidium.dyndns.org>
References: <mailman.600.1229917104.2499.time-nuts@febo.com>	<BLU125-W46831CE6F2E119B7EEBE6CCEEF0@phx.gbl>	<494F1DA4.4000106@xtra.co.nz>	<494F969B.1030604@erols.com>	<494FEC59.90905@xtra.co.nz>	<494FF0B8.4030809@xtra.co.nz>	<494FF7B7.2020403@xtra.co.nz>	<495050CE.5020704@pacific.net>	<495083D2.8010503@erols.com>	<49510EA9.5030100@wwrinc.com>	<49511170.2080600@rubidium.dyndns.org>	<49511493.4090803@febo.com>	<49511F18.7050903@rubidium.dyndns.org><495126A7.7080500@febo.com>	<495127DA.5030903@rubidium.dyndns.org><0C1BA262774A4C0289449218537A9D61@didierhp>
	<49518AA6.90401@rubidium.dyndns.org>
Message-ID: <CA6A9764C28C4BE193016C3BB13F1D8E@didierhp>

> -----Original Message-----
> On Behalf Of Magnus Danielson
> 
> Didier skrev:
> > John,
> > 
> > When you add two (statistically independent) 5 MHz signals 
> > and get a 10MHz signal, the 10 MHz signal's *relative* noise 
> > and drift will be the average of the *relative* noise and 
> > drift of the two 5 MHz signals.
> 
> Not to ruin your analogy here, but what I was discussing on 
> interlocking was intended as means to phase-lock the two 
> oscillators (say 5 MHz but I was thinking 10 MHz) and you 
> could then just add their sines, not mix them up. Thus, you 
> do not get the sum frequency, you get the average frequency. 
> Of course you could go for the frequency multiplication 
> variant if you want.
> 

Specifically, John was suggesting adding the two 5MHz signals, instead of
locking them, that's why I added "statistically independent".

> > So as when you average n signals, the noise and drift are 
> > reduced by sq.rt of n, in this case, 1.4, or about 2dB 
> > (if I am correct), a modest improvement.
> 
> Square root of 2 is about 1,414 or about 3,01 dB.

I am always confused when considering noise, is it 10*log(p1/p0) or
20*log(p1/p0)?

> 
> > Combining more than 2 signals that way (to get more than 2dB 
> > improvement) gets complicated in a hurry.
> 
> Actually no. Not really. You can build pairs and then 
> interconnect them together the same way to form a quad, and 
> so you go on. The neat thing is that the combined oscillators 
> behave as a new oscillator. This is a very traditional way of 
> combining sources to reduce noise. It is certainly not new.
> 

First of all, that only works for a number of oscillators that is a power of
two. Then I suppose that as you increase the number of pairs, it will become
harder for individual oscillators to lock themselves to the output (unless
you add circuitry), so you move away from an interlocked system and closer
to a purely added system. Adding the outputs from a bunch of independent
oscillators does not give you one clean output, it gives you a narrow band
of noise. I must be missing something?

> > I guess the idea behind differential locking was to simplify the 
> > circuit so that a large n could be used to get meaningful 
> > improvement without too much additional circuitry.
> 
> Indeed.
> 
> Cheers,
> Magnus
> 

Didier



From stanley_reynolds at yahoo.com  Wed Dec 24 14:22:52 2008
From: stanley_reynolds at yahoo.com (Stanley Reynolds)
Date: Wed, 24 Dec 2008 06:22:52 -0800 (PST)
Subject: [time-nuts] hello and first questions
References: <49523546.1000709@gmail.com>
Message-ID: <676126.15243.qm@web30308.mail.mud.yahoo.com>

Welcome Trevor,

To divide down 10 MHz to 1 PPS use a TVB :

http://www.leapsecond.com/tools/PPSDIV.ASM

The archives has some info on using a more available chips:
http://www.mail-archive.com/time-nuts at febo.com/msg03444.html
http://www.mail-archive.com/time-nuts at febo.com/msg03442.html

You may want to check here as well :

http://www.prc68.com/
http://www.febo.com/time-freq/index.html
http://www.leapsecond.com/

Stanley

From james.p.lux at jpl.nasa.gov  Wed Dec 24 14:56:38 2008
From: james.p.lux at jpl.nasa.gov (Lux, James P)
Date: Wed, 24 Dec 2008 06:56:38 -0800
Subject: [time-nuts] New topics (was Re: He is a Time-Nut
 Troublemaker....)
In-Reply-To: <CA6A9764C28C4BE193016C3BB13F1D8E@didierhp>
Message-ID: <C5778DA6.3BF0%James.P.Lux@jpl.nasa.gov>




On 12/24/08 6:04 AM, "Didier" <didier at cox.net> wrote:

>> -----Original Message-----
>> On Behalf Of Magnus Danielson
>>
>>
>
> Specifically, John was suggesting adding the two 5MHz signals, instead of
> locking them, that's why I added "statistically independent".
>
>>> So as when you average n signals, the noise and drift are
>>> reduced by sq.rt of n, in this case, 1.4, or about 2dB
>>> (if I am correct), a modest improvement.
>>
>> Square root of 2 is about 1,414 or about 3,01 dB.
>
> I am always confused when considering noise, is it 10*log(p1/p0) or
> 20*log(p1/p0)?


If you're talking noise POWER (or variance..) 10 log10(p1/p0)
If you're talking noise voltage (or standard deviations) 20 log10(v1/vo)





From cfharris at erols.com  Wed Dec 24 16:02:06 2008
From: cfharris at erols.com (Chuck Harris)
Date: Wed, 24 Dec 2008 11:02:06 -0500
Subject: [time-nuts] New topics (was Re: He is a
	Time-Nut	Troublemaker....)
In-Reply-To: <CA6A9764C28C4BE193016C3BB13F1D8E@didierhp>
References: <mailman.600.1229917104.2499.time-nuts@febo.com>	<BLU125-W46831CE6F2E119B7EEBE6CCEEF0@phx.gbl>	<494F1DA4.4000106@xtra.co.nz>	<494F969B.1030604@erols.com>	<494FEC59.90905@xtra.co.nz>	<494FF0B8.4030809@xtra.co.nz>	<494FF7B7.2020403@xtra.co.nz>	<495050CE.5020704@pacific.net>	<495083D2.8010503@erols.com>	<49510EA9.5030100@wwrinc.com>	<49511170.2080600@rubidium.dyndns.org>	<49511493.4090803@febo.com>	<49511F18.7050903@rubidium.dyndns.org><495126A7.7080500@febo.com>	<495127DA.5030903@rubidium.dyndns.org><0C1BA262774A4C0289449218537A9D61@didierhp>	<49518AA6.90401@rubidium.dyndns.org>
	<CA6A9764C28C4BE193016C3BB13F1D8E@didierhp>
Message-ID: <49525CFE.8070802@erols.com>

Didier wrote:

>> Square root of 2 is about 1,414 or about 3,01 dB.
> 
> I am always confused when considering noise, is it 10*log(p1/p0) or
> 20*log(p1/p0)?

A moment's reflection on why the 10 log  vs. 20 log, might help.

The conversion from a power ratio to dB is:

dB = 10 log (P1/P2)

Remember that Power = VxV/R, so:

P1/P2 = (V1xV1)/(V2xV2), the R's cancelling.

So,

dB = 10 log [(V1^2)/V2^2)] or, 10 log[(V1/V2)^2]

If we want to express this as a ratio of voltages, rather than a
ratio of powers (there's a pun in there somewhere ;-),
we need to take the square root of (V1/V2)^2 outside of the log.

To do this, we need to remember that log[X^2] = 2 log X, so:

dB = 10 log[(V1/V2)^2] = 20 log[V1/V2]

A couple of things to note:

1) dB's are dB's.  3dB represents the doubling of a power ratio,
    6dB represents the doubling of a voltage ratio.
2) Convention says that if -dB's are loss, and +dB's are gain, but that
    is just convention.

-Chuck Harris


From magnus at rubidium.dyndns.org  Wed Dec 24 16:02:32 2008
From: magnus at rubidium.dyndns.org (Magnus Danielson)
Date: Wed, 24 Dec 2008 17:02:32 +0100
Subject: [time-nuts] New topics (was Re: He is a
	Time-Nut	Troublemaker....)
In-Reply-To: <CA6A9764C28C4BE193016C3BB13F1D8E@didierhp>
References: <mailman.600.1229917104.2499.time-nuts@febo.com>	<BLU125-W46831CE6F2E119B7EEBE6CCEEF0@phx.gbl>	<494F1DA4.4000106@xtra.co.nz>	<494F969B.1030604@erols.com>	<494FEC59.90905@xtra.co.nz>	<494FF0B8.4030809@xtra.co.nz>	<494FF7B7.2020403@xtra.co.nz>	<495050CE.5020704@pacific.net>	<495083D2.8010503@erols.com>	<49510EA9.5030100@wwrinc.com>	<49511170.2080600@rubidium.dyndns.org>	<49511493.4090803@febo.com>	<49511F18.7050903@rubidium.dyndns.org><495126A7.7080500@febo.com>	<495127DA.5030903@rubidium.dyndns.org><0C1BA262774A4C0289449218537A9D61@didierhp>	<49518AA6.90401@rubidium.dyndns.org>
	<CA6A9764C28C4BE193016C3BB13F1D8E@didierhp>
Message-ID: <49525D18.9090607@rubidium.dyndns.org>

Didier skrev:
>> -----Original Message-----
>> On Behalf Of Magnus Danielson
>>
>> Didier skrev:
>>> John,
>>>
>>> When you add two (statistically independent) 5 MHz signals 
>>> and get a 10MHz signal, the 10 MHz signal's *relative* noise 
>>> and drift will be the average of the *relative* noise and 
>>> drift of the two 5 MHz signals.
>> Not to ruin your analogy here, but what I was discussing on 
>> interlocking was intended as means to phase-lock the two 
>> oscillators (say 5 MHz but I was thinking 10 MHz) and you 
>> could then just add their sines, not mix them up. Thus, you 
>> do not get the sum frequency, you get the average frequency. 
>> Of course you could go for the frequency multiplication 
>> variant if you want.
>>
> 
> Specifically, John was suggesting adding the two 5MHz signals, instead of
> locking them, that's why I added "statistically independent".

They are statistically independent regardless, except for within (or in 
the vincinity of) the PLL bandwidth.

>>> So as when you average n signals, the noise and drift are 
>>> reduced by sq.rt of n, in this case, 1.4, or about 2dB 
>>> (if I am correct), a modest improvement.
>> Square root of 2 is about 1,414 or about 3,01 dB.
> 
> I am always confused when considering noise, is it 10*log(p1/p0) or
> 20*log(p1/p0)?

It is very simple. bel is a power ratio in base 10 logarithm, thus 
log10(P/Pref) where P is the power (in watts) and Pref is the reference 
Power by which we normalize. A decibel is the same thing but scaled to a 
tenth of the scale, thus 10*log10(P/Pref). For voltage we recall that 
P=UI and Ohm's law gives us U=RI giving I=U/R and thus P=U^/R. Inserting 
this gives 10*log10(U^2/R/Pref). Since log(x^2)=2log(x) we can shift the 
2 out and form 20*log10(U/sqrt(R*Pref)) which we can simplify to 
20*log10(U/Uref) by letting Uref = sqrt(R*Pref).

So 10*log... is for powers and 20*log is for voltages.

Double power gives 10*log10(2) = 10*0.301 = 3,01 dB.
Double voltage gives 20*log10(2) = 20*0.301 = 6,02 dB.

>>> Combining more than 2 signals that way (to get more than 2dB 
>>> improvement) gets complicated in a hurry.
>> Actually no. Not really. You can build pairs and then 
>> interconnect them together the same way to form a quad, and 
>> so you go on. The neat thing is that the combined oscillators 
>> behave as a new oscillator. This is a very traditional way of 
>> combining sources to reduce noise. It is certainly not new.
>>
> 
> First of all, that only works for a number of oscillators that is a power of
> two. Then I suppose that as you increase the number of pairs, it will become
> harder for individual oscillators to lock themselves to the output (unless
> you add circuitry), so you move away from an interlocked system and closer
> to a purely added system. Adding the outputs from a bunch of independent
> oscillators does not give you one clean output, it gives you a narrow band
> of noise. I must be missing something?

If you look at the grouping that I described you will see that for 
combining N oscillators it takes N-1 diffrential locking loops, meaning 
N-1 phase comparators and N-1 loopfilters etc. I was also giving the 
specific hint that this was a simplified description in that I assumed 
non-weighed result, where as you could fairly easily create a weighed 
form. Consider want to lock one oscillator two a pair. Then weigth 2/3 
of the signal to the pair input and 4/3 of the signal to the single 
oscillator, thus slightly less to the pair and slightly more to the 
single oscillator.

The actual trick here is that the signal and the noise will add 
differently together. Recall, that for uncorrelated signals we add 
powers, so Ptot = P1 + P2 or from a voltage perspective Utot^2 = U1^2 + 
U2^2, assuing U1 = U2 gives Utot = U1 * sqrt(2) or Ptot = P1 * 2 thus 
giving +3,01 dB. For correlated signals we add amplitude (in voltage) 
such that Utot = U1 + U2 which for U1=U2 gives Utot = U1 * 2 thus giving 
+6,02 dB. Now, for two frequency-locked 10 MHz sines which is also 
phase-locked to be nominally at 0 degrees from each other we have two 
correlated signals and the phase-alignment ensures that their amplitudes 
adds correctly to the maximum value, thus giving us a +6,02 dB gain. The 
noise of the two oscillators is uncorrelated to each other, and thus 
giving us a +3,01 dB gain, assuming more or less equalent oscillators.
The net gain in S/N ratio is 6,02-3,01 = 3,01 dB.

You can combine the two sines through a mixer rather than through 
additive combination, but that was not what was originally described.

This technique have been used for ages for low-noise amplifiers etc. I 
have only adapted it to the fields of oscillators. It is a crude 
approximation which gives some improvement (if done correctly) but does 
not really comes THAT cheaply.

Cheers,
Magnus


From danrae at verizon.net  Wed Dec 24 16:55:06 2008
From: danrae at verizon.net (Dan Rae)
Date: Wed, 24 Dec 2008 08:55:06 -0800
Subject: [time-nuts] Programming an 8051 for Didier's Tbolt monitor?
Message-ID: <4952696A.1060408@verizon.net>

Can someone here in the US kindly do this for me?  I have the blank DIP 
IC, 20 pin version, but none of my old eprom programmers or PIC 
programmers will talk to it, and I didn't really want to buy or build 
something just for this one task...

Dan

ac6ao / g3ncr



From didier at cox.net  Wed Dec 24 17:14:22 2008
From: didier at cox.net (Didier)
Date: Wed, 24 Dec 2008 11:14:22 -0600
Subject: [time-nuts] New topics (was Re: He is aTime-Nut
	Troublemaker....)
In-Reply-To: <49525CFE.8070802@erols.com>
References: <mailman.600.1229917104.2499.time-nuts@febo.com>	<BLU125-W46831CE6F2E119B7EEBE6CCEEF0@phx.gbl>	<494F1DA4.4000106@xtra.co.nz>	<494F969B.1030604@erols.com>	<494FEC59.90905@xtra.co.nz>	<494FF0B8.4030809@xtra.co.nz>	<494FF7B7.2020403@xtra.co.nz>	<495050CE.5020704@pacific.net>	<495083D2.8010503@erols.com>	<49510EA9.5030100@wwrinc.com>	<49511170.2080600@rubidium.dyndns.org>	<49511493.4090803@febo.com>	<49511F18.7050903@rubidium.dyndns.org><495126A7.7080500@febo.com>	<495127DA.5030903@rubidium.dyndns.org><0C1BA262774A4C0289449218537A9D61@didierhp>	<49518AA6.90401@rubidium.dyndns.org><CA6A9764C28C4BE193016C3BB13F1D8E@didierhp>
	<49525CFE.8070802@erols.com>
Message-ID: <F3B89D59B2774310A86386BEC90AC35A@didierhp>

Chuck,

I am quite familiar with how to calculate a voltage or power ratio in dB,
but refering to the first issue, when you combine two oscillators, does the
noise improve by 3dB?

Didier

> -----Original Message-----
> From: time-nuts-bounces at febo.com 
> [mailto:time-nuts-bounces at febo.com] On Behalf Of Chuck Harris
> Sent: Wednesday, December 24, 2008 10:02 AM
> To: Discussion of precise time and frequency measurement
> Subject: Re: [time-nuts] New topics (was Re: He is aTime-Nut 
> Troublemaker....)
> 
> Didier wrote:
> 
> >> Square root of 2 is about 1,414 or about 3,01 dB.
> > 
> > I am always confused when considering noise, is it 10*log(p1/p0) or 
> > 20*log(p1/p0)?
> 
> A moment's reflection on why the 10 log  vs. 20 log, might help.
> 
> The conversion from a power ratio to dB is:
> 
> dB = 10 log (P1/P2)
> 
> Remember that Power = VxV/R, so:
> 
> P1/P2 = (V1xV1)/(V2xV2), the R's cancelling.
> 
> So,
> 
> dB = 10 log [(V1^2)/V2^2)] or, 10 log[(V1/V2)^2]
> 
> If we want to express this as a ratio of voltages, rather 
> than a ratio of powers (there's a pun in there somewhere ;-), 
> we need to take the square root of (V1/V2)^2 outside of the log.
> 
> To do this, we need to remember that log[X^2] = 2 log X, so:
> 
> dB = 10 log[(V1/V2)^2] = 20 log[V1/V2]
> 
> A couple of things to note:
> 
> 1) dB's are dB's.  3dB represents the doubling of a power ratio,
>     6dB represents the doubling of a voltage ratio.
> 2) Convention says that if -dB's are loss, and +dB's are 
> gain, but that
>     is just convention.
> 
> -Chuck Harris
> 
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com To unsubscribe, 
> go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.



From didier at cox.net  Wed Dec 24 17:15:57 2008
From: didier at cox.net (Didier)
Date: Wed, 24 Dec 2008 11:15:57 -0600
Subject: [time-nuts] Programming an 8051 for Didier's Tbolt monitor?
In-Reply-To: <4952696A.1060408@verizon.net>
References: <4952696A.1060408@verizon.net>
Message-ID: <213E8AA2CA414920A7CC2AEA8CEB6FB3@didierhp>

If you send it to me, I'll be glad to flash it for you

Didier KO4BB

> -----Original Message-----
> From: time-nuts-bounces at febo.com 
> [mailto:time-nuts-bounces at febo.com] On Behalf Of Dan Rae
> Sent: Wednesday, December 24, 2008 10:55 AM
> To: 'Discussion of precise time and frequency measurement'
> Subject: [time-nuts] Programming an 8051 for Didier's Tbolt monitor?
> 
> Can someone here in the US kindly do this for me?  I have the 
> blank DIP IC, 20 pin version, but none of my old eprom 
> programmers or PIC programmers will talk to it, and I didn't 
> really want to buy or build something just for this one task...
> 
> Dan
> 
> ac6ao / g3ncr
> 
> 
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com To unsubscribe, 
> go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
> 



From magnus at rubidium.dyndns.org  Wed Dec 24 17:48:20 2008
From: magnus at rubidium.dyndns.org (Magnus Danielson)
Date: Wed, 24 Dec 2008 18:48:20 +0100
Subject: [time-nuts] New topics (was Re: He is
	aTime-Nut	Troublemaker....)
In-Reply-To: <F3B89D59B2774310A86386BEC90AC35A@didierhp>
References: <mailman.600.1229917104.2499.time-nuts@febo.com>	<BLU125-W46831CE6F2E119B7EEBE6CCEEF0@phx.gbl>	<494F1DA4.4000106@xtra.co.nz>	<494F969B.1030604@erols.com>	<494FEC59.90905@xtra.co.nz>	<494FF0B8.4030809@xtra.co.nz>	<494FF7B7.2020403@xtra.co.nz>	<495050CE.5020704@pacific.net>	<495083D2.8010503@erols.com>	<49510EA9.5030100@wwrinc.com>	<49511170.2080600@rubidium.dyndns.org>	<49511493.4090803@febo.com>	<49511F18.7050903@rubidium.dyndns.org><495126A7.7080500@febo.com>	<495127DA.5030903@rubidium.dyndns.org><0C1BA262774A4C0289449218537A9D61@didierhp>	<49518AA6.90401@rubidium.dyndns.org><CA6A9764C28C4BE193016C3BB13F1D8E@didierhp>	<49525CFE.8070802@erols.com>
	<F3B89D59B2774310A86386BEC90AC35A@didierhp>
Message-ID: <495275E4.6020602@rubidium.dyndns.org>

Didier skrev:
> Chuck,
> 
> I am quite familiar with how to calculate a voltage or power ratio in dB,
> but refering to the first issue, when you combine two oscillators, does the
> noise improve by 3dB?

If you look back at my previous post, when combining the two outputs, 
the noise raises by 3 dB, but the signal strength raises by 6 dB, giving 
a net effect of lowering the noise by 3 dB relative the signal strength.

You will find this described in many places for transistors. It occurs 
for instance in the MAT-0x series of datasheets among several other places.

Cheers,
Magnus

> Didier
> 
>> -----Original Message-----
>> From: time-nuts-bounces at febo.com 
>> [mailto:time-nuts-bounces at febo.com] On Behalf Of Chuck Harris
>> Sent: Wednesday, December 24, 2008 10:02 AM
>> To: Discussion of precise time and frequency measurement
>> Subject: Re: [time-nuts] New topics (was Re: He is aTime-Nut 
>> Troublemaker....)
>>
>> Didier wrote:
>>
>>>> Square root of 2 is about 1,414 or about 3,01 dB.
>>> I am always confused when considering noise, is it 10*log(p1/p0) or 
>>> 20*log(p1/p0)?
>> A moment's reflection on why the 10 log  vs. 20 log, might help.
>>
>> The conversion from a power ratio to dB is:
>>
>> dB = 10 log (P1/P2)
>>
>> Remember that Power = VxV/R, so:
>>
>> P1/P2 = (V1xV1)/(V2xV2), the R's cancelling.
>>
>> So,
>>
>> dB = 10 log [(V1^2)/V2^2)] or, 10 log[(V1/V2)^2]
>>
>> If we want to express this as a ratio of voltages, rather 
>> than a ratio of powers (there's a pun in there somewhere ;-), 
>> we need to take the square root of (V1/V2)^2 outside of the log.
>>
>> To do this, we need to remember that log[X^2] = 2 log X, so:
>>
>> dB = 10 log[(V1/V2)^2] = 20 log[V1/V2]
>>
>> A couple of things to note:
>>
>> 1) dB's are dB's.  3dB represents the doubling of a power ratio,
>>     6dB represents the doubling of a voltage ratio.
>> 2) Convention says that if -dB's are loss, and +dB's are 
>> gain, but that
>>     is just convention.
>>
>> -Chuck Harris
>>
>> _______________________________________________
>> time-nuts mailing list -- time-nuts at febo.com To unsubscribe, 
>> go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>> and follow the instructions there.
> 
> 
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.


From magnus at rubidium.dyndns.org  Wed Dec 24 17:55:46 2008
From: magnus at rubidium.dyndns.org (Magnus Danielson)
Date: Wed, 24 Dec 2008 18:55:46 +0100
Subject: [time-nuts] Christmas gift from GLONASS
Message-ID: <495277A2.2060807@rubidium.dyndns.org>

Dear all,

It seems that the GLONASS team have decided to bring us a nice Christmas 
present in form of three more GLONASS-M sats in space.

http://sidt.gpsworld.com/gpssidt/System+Design+and+Test+News/GLONASS-Launch-Update-Satellites-on-the-Launch-Pad/ArticleStandard/Article/detail/573051?contextCategoryId=33831

Lovely pics with launch-pad and snow. :)

Cheers,
Magnus


From holrum at hotmail.com  Wed Dec 24 18:14:50 2008
From: holrum at hotmail.com (Mark Sims)
Date: Wed, 24 Dec 2008 18:14:50 +0000
Subject: [time-nuts] Lady Heather's Disciplined Oscillator (Thunderbolt)
	Software
In-Reply-To: <mailman.709.1230137721.2499.time-nuts@febo.com>
References: <mailman.709.1230137721.2499.time-nuts@febo.com>
Message-ID: <BLU125-W4125966DA4ABC01F59B4ACCEED0@phx.gbl>


Lady Heather,  Mistress of the Disciplined Oscillator,  kidnapped me and locked me in Her Dungeon 'o Doom.  She forced me a whip point to write Her a controller program for Her Thunderbolt.  I had no choice but to comply.  When She stepped out to buy some Whip Wax,  I escaped with Her precious code.  
Lady Heather lives on the outskirts of the Land of the Obsolete and the code is written in Quick-C to run under DOS or WIN98, etc that allow direct access to the hardware.  Default video hardware required is a VGA type controller with VESA compatible BIOS.  It should be easy to modify for more modern environments.
Her program allows control over most Thunderbolt parameters and graphs the important ones.  It also supports logging data to a file.  It also calculates and graphs ADEV and OADEV of the REPORTED oscillator ppb and PPS values.
_________________________________________________________________
It?s the same Hotmail?. If by ?same? you mean up to 70% faster.
http://windowslive.com/online/hotmail?ocid=TXT_TAGLM_WL_hotmail_acq_broad1_122008
-------------- next part --------------
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From holrum at hotmail.com  Wed Dec 24 18:17:07 2008
From: holrum at hotmail.com (Mark Sims)
Date: Wed, 24 Dec 2008 18:17:07 +0000
Subject: [time-nuts] How are you going to spend your extra second?
In-Reply-To: <mailman.709.1230137721.2499.time-nuts@febo.com>
References: <mailman.709.1230137721.2499.time-nuts@febo.com>
Message-ID: <BLU125-W30C12D745935B851A41CD8CEED0@phx.gbl>


Well,  the lords of time have blessed us this year with a whole extra second of existence.  How are you going to use yours?
_________________________________________________________________
Send e-mail anywhere. No map, no compass.
http://windowslive.com/oneline/hotmail?ocid=TXT_TAGLM_WL_hotmail_acq_anywhere_122008

From normn3ykf at stny.rr.com  Wed Dec 24 18:19:20 2008
From: normn3ykf at stny.rr.com (Norman J McSweyn)
Date: Wed, 24 Dec 2008 13:19:20 -0500
Subject: [time-nuts] Lady Heather's Disciplined Oscillator (Thunderbolt)
 Software
In-Reply-To: <BLU125-W4125966DA4ABC01F59B4ACCEED0@phx.gbl>
References: <mailman.709.1230137721.2499.time-nuts@febo.com>
	<BLU125-W4125966DA4ABC01F59B4ACCEED0@phx.gbl>
Message-ID: <49527D28.80303@stny.rr.com>

Mark Sims wrote:
> Lady Heather,  Mistress of the Disciplined Oscillator,  kidnapped me and locked me in Her Dungeon 'o Doom.  She forced me a whip point to write Her a controller program for Her Thunderbolt.  I had no choice but to comply.  When She stepped out to buy some Whip Wax,  I escaped with Her precious code.  
> Lady Heather lives on the outskirts of the Land of the Obsolete and the code is written in Quick-C to run under DOS or WIN98, etc that allow direct access to the hardware.  Default video hardware required is a VGA type controller with VESA compatible BIOS.  It should be easy to modify for more modern environments.
> Her program allows control over most Thunderbolt parameters and graphs the important ones.  It also supports logging data to a file.  It also calculates and graphs ADEV and OADEV of the REPORTED oscillator ppb and PPS values.
> _________________________________________________________________
> It?s the same Hotmail?. If by ?same? you mean up to 70% faster.
> http://windowslive.com/online/hotmail?ocid=TXT_TAGLM_WL_hotmail_acq_broad1_122008
> 
> 
> ------------------------------------------------------------------------
> 
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
Who cares about T and F!
More about Lady Heather, please!


From rk at timing-consultants.com  Wed Dec 24 19:36:27 2008
From: rk at timing-consultants.com (Rob Kimberley)
Date: Wed, 24 Dec 2008 19:36:27 -0000
Subject: [time-nuts] How are you going to spend your extra second?
In-Reply-To: <BLU125-W30C12D745935B851A41CD8CEED0@phx.gbl>
References: <mailman.709.1230137721.2499.time-nuts@febo.com>
	<BLU125-W30C12D745935B851A41CD8CEED0@phx.gbl>
Message-ID: <D1835C84FB1A45DFA2128C0F4E9CD817@Robin>

Don't know about you, but I'm off to a "theme" Murder Mystery party on New
Years Eve playing the part of a Gestapo office by the name of Otto Von
Pinkelwurst. I'm desperately trying to work out how best to spend that extra
second of my life..........

:-))

Anyway, whatever you are all doing, I hope you all have a super Christmas,
and an even better 2009.

Cheers 'n Beers

Rob Kimberley

-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of Mark Sims
Sent: 24 December 2008 18:17
To: time-nuts at febo.com
Subject: [time-nuts] How are you going to spend your extra second?


Well,  the lords of time have blessed us this year with a whole extra second
of existence.  How are you going to use yours?
_________________________________________________________________
Send e-mail anywhere. No map, no compass.
http://windowslive.com/oneline/hotmail?ocid=TXT_TAGLM_WL_hotmail_acq_anywher
e_122008
_______________________________________________
time-nuts mailing list -- time-nuts at febo.com To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.



From magnus at rubidium.dyndns.org  Wed Dec 24 19:45:36 2008
From: magnus at rubidium.dyndns.org (Magnus Danielson)
Date: Wed, 24 Dec 2008 20:45:36 +0100
Subject: [time-nuts] How are you going to spend your extra second?
In-Reply-To: <D1835C84FB1A45DFA2128C0F4E9CD817@Robin>
References: <mailman.709.1230137721.2499.time-nuts@febo.com>	<BLU125-W30C12D745935B851A41CD8CEED0@phx.gbl>
	<D1835C84FB1A45DFA2128C0F4E9CD817@Robin>
Message-ID: <49529160.1080502@rubidium.dyndns.org>

Dear Rob and all,

Rob Kimberley skrev:
> Don't know about you, but I'm off to a "theme" Murder Mystery party on New
> Years Eve playing the part of a Gestapo office by the name of Otto Von
> Pinkelwurst. I'm desperately trying to work out how best to spend that extra
> second of my life..........
> 
> :-))
> 
> Anyway, whatever you are all doing, I hope you all have a super Christmas,
> and an even better 2009.

In swedish leap-second translates to skott-sekund, and skott translates 
back to shot, so recalling the recent thread on fire-arms, don't get 
shot on the leap-second.

Best Regards,
Magnus


From hmurray at megapathdsl.net  Wed Dec 24 19:53:06 2008
From: hmurray at megapathdsl.net (Hal Murray)
Date: Wed, 24 Dec 2008 11:53:06 -0800
Subject: [time-nuts] How are you going to spend your extra second?
In-Reply-To: Message from Mark Sims <holrum@hotmail.com> of "Wed,
	24 Dec 2008 18:17:07 GMT."
	<BLU125-W30C12D745935B851A41CD8CEED0@phx.gbl> 
Message-ID: <20081224195308.17AF6BCD7@ip-64-139-1-69.sjc.megapath.net>


> Well,  the lords of time have blessed us this year with a whole extra
> second of existence.  How are you going to use yours? 

I'm in PST, GMT -8, so the extra second happens at 4 in the afternoon.

I expect I (and many others on this list) will be right here watching to see 
how my systems handle the extra second.


-- 
These are my opinions, not necessarily my employer's.  I hate spam.





From bruce.griffiths at xtra.co.nz  Wed Dec 24 20:11:54 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Thu, 25 Dec 2008 09:11:54 +1300
Subject: [time-nuts] hello and first questions
In-Reply-To: <49523546.1000709@gmail.com>
References: <49523546.1000709@gmail.com>
Message-ID: <4952978A.6020705@xtra.co.nz>

Trevor

The answer to your question depends on your accuracy and resolution
requirements.

The easiest method is to obtain a time interval counter like the HP5370A
(or HP5370B), the SR620, the Agilent 53131A. Agilent 53132A, etc.

Alternatively you can build your own:

1) If your resolution requirements are more modest (eg 100ns) then you
can easily build your own time interval counter. With some ingenuity its
possible to use a suitable micro to do this.
The best method being to sample a free running counter (extended in
software as required) with the synchronised leading edge of the PPS
pulses and subtract the corresponding time stamps. Done correctly, this
ensures that no PPS pulses are lost due to processing time.

2) If you need higher resolution you can use a gate array and
microprocessor together with a faster clock (100MHz or more depending on
the gate array).
Its also possible to use a suitable DSP (eg an Analog Devices Blackfin
DSP) to timestamp the leading edge of a PPS pulse with a resolution of a
few nanosec (<3) with little external logic required.

3) Subnanosecond resolution requires an interpolator as GHz clocks are
usually impractical and/or expensive.
There are many interpolation techniques including:

a) Sampling a a pair of quadrature phased sine waves. The clock usually
has the same frequency as and is phase locked to the sinewave.

b) Charging a capacitor for the time interval from the leading edge of a
PPS pulse to the next active clock edge. Use an ADC to measure the
voltage across the capacitor, combine this with the digital time stamp
derived by sampling a continuously clocked counter and reset the
capacitor for the next PPS pulse. A variant of this is to charge the
capacitor with a current I and discharge it with a lower current such as
I/1000 and measure the time taken to discharge the capacitor to zero
using a conventional counter. This technique can increase the resolution
by a factor of 1000 or more.

c) Triggered phase locked vernier oscillators as used in the HP5370 (A
or B).

d) Use a tapped delay line consisting of a long string of gates within
an IC (custom or FPGA) as in the Acam time interval measurement chips.

All the clocks need to be phase locked to a low noise frequency standard
to maintain accuracy for longer time intervals.

For short time delays between the 2 PPS pulses an interpolator circuit
by itself may suffice.

Thus the relevant questions are:

1) What is the maximum range you need/want to be able to measure?

2) What resolution do you need/want?

3) What accuracy do you need/want?

Bruce


Trevor Higgins wrote:
> Hello!
> Just a couple of backslashes probing the world of insanely accurate time.
>
> My first question, which will doubtlessly lead to many more, is where 
> can I find some information on the circuitry to derive the difference 
> between two PPS signals and read it in some sort of digital format.
> I'd also be interested in finding some information on deriving PPS 
> signals from a raw 10Mhz signal, since it seems that rubidium frequency 
> standards are a fair bit cheaper than 1PPS standards.
> I hope to build my first GPS disciplined atomic standard within a few 
> months, learning all sorts of things along the way. Sorry if I'm already 
> asking some questions that have obvious answers, but i wanted to start 
> on the best possible information out there, and anyone on this list 
> probably has the best advice that I could ask for.
>
> I've got a lot of raw potential, and have been feeding my interest in 
> timekeeping with a ton of random information for a long time, and it is 
> time to do something with it.
> Glad to be part of a group that might understand how fascinating this 
> all is to me.
>
> Obsessed with all things precise and accurate,
> \\
>
>   



From didier at cox.net  Wed Dec 24 20:23:49 2008
From: didier at cox.net (Didier)
Date: Wed, 24 Dec 2008 14:23:49 -0600
Subject: [time-nuts] New topics (was Re: He isaTime-Nut Troublemaker....)
In-Reply-To: <495275E4.6020602@rubidium.dyndns.org>
References: <mailman.600.1229917104.2499.time-nuts@febo.com>	<BLU125-W46831CE6F2E119B7EEBE6CCEEF0@phx.gbl>	<494F1DA4.4000106@xtra.co.nz>	<494F969B.1030604@erols.com>	<494FEC59.90905@xtra.co.nz>	<494FF0B8.4030809@xtra.co.nz>	<494FF7B7.2020403@xtra.co.nz>	<495050CE.5020704@pacific.net>	<495083D2.8010503@erols.com>	<49510EA9.5030100@wwrinc.com>	<49511170.2080600@rubidium.dyndns.org>	<49511493.4090803@febo.com>	<49511F18.7050903@rubidium.dyndns.org><495126A7.7080500@febo.com>	<495127DA.5030903@rubidium.dyndns.org><0C1BA262774A4C0289449218537A9D61@didierhp>	<49518AA6.90401@rubidium.dyndns.org><CA6A9764C28C4BE193016C3BB13F1D8E@didierhp>	<49525CFE.8070802@erols.com><F3B89D59B2774310A86386BEC90AC35A@didierhp>
	<495275E4.6020602@rubidium.dyndns.org>
Message-ID: <0BEC2603FD974AC3AFAF74E46FD1E057@didierhp>

6dB means the power is four times the power of one oscillator, how does the
power go up by 4 when combining two oscillators?

Didier 

> -----Original Message-----
> From: time-nuts-bounces at febo.com 
> [mailto:time-nuts-bounces at febo.com] On Behalf Of Magnus Danielson
> Sent: Wednesday, December 24, 2008 11:48 AM
> To: Discussion of precise time and frequency measurement
> Subject: Re: [time-nuts] New topics (was Re: He isaTime-Nut 
> Troublemaker....)
> 
> Didier skrev:
> > Chuck,
> > 
> > I am quite familiar with how to calculate a voltage or 
> power ratio in 
> > dB, but refering to the first issue, when you combine two 
> oscillators, 
> > does the noise improve by 3dB?
> 
> If you look back at my previous post, when combining the two 
> outputs, the noise raises by 3 dB, but the signal strength 
> raises by 6 dB, giving a net effect of lowering the noise by 
> 3 dB relative the signal strength.
> 
> You will find this described in many places for transistors. 
> It occurs for instance in the MAT-0x series of datasheets 
> among several other places.
> 
> Cheers,
> Magnus
> 
> > Didier
> > 
> >> -----Original Message-----
> >> From: time-nuts-bounces at febo.com
> >> [mailto:time-nuts-bounces at febo.com] On Behalf Of Chuck Harris
> >> Sent: Wednesday, December 24, 2008 10:02 AM
> >> To: Discussion of precise time and frequency measurement
> >> Subject: Re: [time-nuts] New topics (was Re: He is aTime-Nut
> >> Troublemaker....)
> >>
> >> Didier wrote:
> >>
> >>>> Square root of 2 is about 1,414 or about 3,01 dB.
> >>> I am always confused when considering noise, is it 
> 10*log(p1/p0) or 
> >>> 20*log(p1/p0)?
> >> A moment's reflection on why the 10 log  vs. 20 log, might help.
> >>
> >> The conversion from a power ratio to dB is:
> >>
> >> dB = 10 log (P1/P2)
> >>
> >> Remember that Power = VxV/R, so:
> >>
> >> P1/P2 = (V1xV1)/(V2xV2), the R's cancelling.
> >>
> >> So,
> >>
> >> dB = 10 log [(V1^2)/V2^2)] or, 10 log[(V1/V2)^2]
> >>
> >> If we want to express this as a ratio of voltages, rather than a 
> >> ratio of powers (there's a pun in there somewhere ;-), we need to 
> >> take the square root of (V1/V2)^2 outside of the log.
> >>
> >> To do this, we need to remember that log[X^2] = 2 log X, so:
> >>
> >> dB = 10 log[(V1/V2)^2] = 20 log[V1/V2]
> >>
> >> A couple of things to note:
> >>
> >> 1) dB's are dB's.  3dB represents the doubling of a power ratio,
> >>     6dB represents the doubling of a voltage ratio.
> >> 2) Convention says that if -dB's are loss, and +dB's are gain, but 
> >> that
> >>     is just convention.
> >>
> >> -Chuck Harris
> >>
> >> _______________________________________________
> >> time-nuts mailing list -- time-nuts at febo.com To unsubscribe, go to 
> >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> >> and follow the instructions there.
> > 
> > 
> > _______________________________________________
> > time-nuts mailing list -- time-nuts at febo.com To unsubscribe, go to 
> > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> > and follow the instructions there.
> 
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com To unsubscribe, 
> go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.



From jgd at johngsbbq.com  Wed Dec 24 20:29:56 2008
From: jgd at johngsbbq.com (Neon John)
Date: Wed, 24 Dec 2008 15:29:56 -0500
Subject: [time-nuts] How are you going to spend your extra second?
In-Reply-To: <BLU125-W30C12D745935B851A41CD8CEED0@phx.gbl>
References: <mailman.709.1230137721.2499.time-nuts@febo.com>
	<BLU125-W30C12D745935B851A41CD8CEED0@phx.gbl>
Message-ID: <ds65l49rq9vph63npq2gph2nt4127dbmaq@4ax.com>

On Wed, 24 Dec 2008 18:17:07 +0000, Mark Sims <holrum at hotmail.com> wrote:

>
>Well,  the lords of time have blessed us this year with a whole extra second of existence.  How are you going to use yours?

Dunno.  Let me think about it for a sec.

ooops...

Merry Christmas all

John
--
John De Armond
See my website for my current email address
http://www.neon-john.com
http://www.johndearmond.com <-- best little blog on the net!
Tellico Plains, Occupied TN
Better remain silent and be thought a fool than to cite Wikipedia and remove all doubt.



From magnus at rubidium.dyndns.org  Wed Dec 24 20:47:14 2008
From: magnus at rubidium.dyndns.org (Magnus Danielson)
Date: Wed, 24 Dec 2008 21:47:14 +0100
Subject: [time-nuts] New topics (was Re: He isaTime-Nut Troublemaker....)
In-Reply-To: <0BEC2603FD974AC3AFAF74E46FD1E057@didierhp>
References: <mailman.600.1229917104.2499.time-nuts@febo.com>	<BLU125-W46831CE6F2E119B7EEBE6CCEEF0@phx.gbl>	<494F1DA4.4000106@xtra.co.nz>	<494F969B.1030604@erols.com>	<494FEC59.90905@xtra.co.nz>	<494FF0B8.4030809@xtra.co.nz>	<494FF7B7.2020403@xtra.co.nz>	<495050CE.5020704@pacific.net>	<495083D2.8010503@erols.com>	<49510EA9.5030100@wwrinc.com>	<49511170.2080600@rubidium.dyndns.org>	<49511493.4090803@febo.com>	<49511F18.7050903@rubidium.dyndns.org><495126A7.7080500@febo.com>	<495127DA.5030903@rubidium.dyndns.org><0C1BA262774A4C0289449218537A9D61@didierhp>	<49518AA6.90401@rubidium.dyndns.org><CA6A9764C28C4BE193016C3BB13F1D8E@didierhp>	<49525CFE.8070802@erols.com><F3B89D59B2774310A86386BEC90AC35A@didierhp>	<495275E4.6020602@rubidium.dyndns.org>
	<0BEC2603FD974AC3AFAF74E46FD1E057@didierhp>
Message-ID: <49529FD2.5040007@rubidium.dyndns.org>

Didier skrev:
> 6dB means the power is four times the power of one oscillator, how does the
> power go up by 4 when combining two oscillators?

When you add the two signals together. A linear addition give twice the 
amplitude and 4 times the power assuming the same impedance, but to 
achieve this you need an active amplifier. A passive adder will 
naturally not produce more power out than put into it, so it dampens the 
signal, but will also dampen the noise applied to the input, so the same 
relative gain remains.

Cheers,
Magnus


From holrum at hotmail.com  Wed Dec 24 21:22:09 2008
From: holrum at hotmail.com (Mark Sims)
Date: Wed, 24 Dec 2008 21:22:09 +0000
Subject: [time-nuts] How are you going to spend your extra second?
In-Reply-To: <mailman.718.1230150600.2499.time-nuts@febo.com>
References: <mailman.718.1230150600.2499.time-nuts@febo.com>
Message-ID: <BLU125-W38BF78030AFF1965A7D391CEED0@phx.gbl>


Unfortunately, in many US cities,  getting shot on New Years is an all too common occurance.  Knuckle dragging idiots celebrate with lots of booze, ammunition, and firearms.  At the stoke of midnight they unleash a hail of gunfire into the air...  and what goes up tends to come back down.  Inevitably somebody (more often than not, a child) will be in the exact place where something comes down.-------------In swedish leap-second translates to skott-sekund, and skott translates 
back to shot, so recalling the recent thread on fire-arms, don't get 
shot on the leap-second.
_________________________________________________________________
Send e-mail anywhere. No map, no compass.
http://windowslive.com/oneline/hotmail?ocid=TXT_TAGLM_WL_hotmail_acq_anywhere_122008

From brooke at pacific.net  Wed Dec 24 21:42:40 2008
From: brooke at pacific.net (Brooke Clarke)
Date: Wed, 24 Dec 2008 13:42:40 -0800
Subject: [time-nuts] How are you going to spend your extra second?
In-Reply-To: <BLU125-W38BF78030AFF1965A7D391CEED0@phx.gbl>
References: <mailman.718.1230150600.2499.time-nuts@febo.com>
	<BLU125-W38BF78030AFF1965A7D391CEED0@phx.gbl>
Message-ID: <4952ACD0.9080802@pacific.net>

Hi Mark:

It turns out that many large cities in the U.S. have Time Of Arrival systems to 
locate where a gun is discharged.
http://www.prc68.com/I/Sensors.shtml#Aco
The military also uses time of arrival to locate guns:
http://www.prc68.com/I/RT1185.shtml
so again the topic is time related.

Have Fun,

Brooke Clarke
http://www.prc68.com

Mark Sims wrote:
> Unfortunately, in many US cities,  getting shot on New Years is an all too common occurance.  Knuckle dragging idiots celebrate with lots of booze, ammunition, and firearms.  At the stoke of midnight they unleash a hail of gunfire into the air...  and what goes up tends to come back down.  Inevitably somebody (more often than not, a child) will be in the exact place where something comes down.-------------In swedish leap-second translates to skott-sekund, and skott translates 
> back to shot, so recalling the recent thread on fire-arms, don't get 
> shot on the leap-second.
> _________________________________________________________________
> Send e-mail anywhere. No map, no compass.
> http://windowslive.com/oneline/hotmail?ocid=TXT_TAGLM_WL_hotmail_acq_anywhere_122008
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
> 
> 



From joegwinn at comcast.net  Wed Dec 24 21:49:23 2008
From: joegwinn at comcast.net (Joe Gwinn)
Date: Wed, 24 Dec 2008 16:49:23 -0500
Subject: [time-nuts] Sub Pico Second Phase logger
Message-ID: <p0624080fc5785e03c644@[192.168.1.212]>

At 5:05 PM +0000 12/23/08, time-nuts-request at febo.com wrote:
>Date: Tue, 23 Dec 2008 16:10:29 +0000
>From: Mark Sims <holrum at hotmail.com>
>Subject: [time-nuts] Sub Pico Second Phase logger
>To: <time-nuts at febo.com>
>Message-ID: <BLU125-W29C8667E5FAE2A1EE11F5BCEEC0 at phx.gbl>
>Content-Type: text/plain; charset="Windows-1252"
>
>
>Since when has prior art or obviousness kept the US Patent Orifice 
>from issuing a patent?  ;-)
>
>---------
>
>[JG]  I just read 5,267,182.  It appears to anticipate Sotiriadis in every
>aspect, so it may be a *long* time before Sotiriadis's patent is
>issued.

The USPTO is in over their heads, both on expertise and on sheer 
volume of applications.

Given that the uncommon word "Diophantine" appears in both, there is 
a possibility that the Examiner will find 5,267,182.

Joe


From joegwinn at comcast.net  Wed Dec 24 21:52:50 2008
From: joegwinn at comcast.net (Joe Gwinn)
Date: Wed, 24 Dec 2008 16:52:50 -0500
Subject: [time-nuts] New topics (was Re: He is a Time-Nut
 Troublemaker....)
Message-ID: <p06240810c5785f360e1b@[192.168.1.212]>

At 5:05 PM +0000 12/23/08, time-nuts-request at febo.com wrote:
>Date: Tue, 23 Dec 2008 11:40:51 -0500
>From: John Ackermann N8UR <jra at febo.com>
>Subject: [time-nuts] New topics (was Re: He is a Time-Nut
>	Troublemaker....)
>To: Discussion of precise time and frequency measurement
>	<time-nuts at febo.com>
>
>Magnus Danielson wrote:
>
>>  My intent is to get some stuff done in the lab during the vacation.
>>  (Desperatly trying to get some more on-topic discussions going).
>
>Here are two questions that have been running around my head:
>
>[snip]
>2.  Several measurement techniques require a given phase relationship
>(e.g., quadrature) between DUT and reference.  For HF frequencies (ie, 5
>or 10 MHz) is there a *practical* phase shifter design covering 180+
>degrees that doesn't involve switching various lengths of coax in and
>out of the line?

Why the aversion to coax delay lines?  They are simple and reliable. 
The reason will help people to tell what alternatives would be best.

Joe


From bruce.griffiths at xtra.co.nz  Wed Dec 24 21:53:47 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Thu, 25 Dec 2008 10:53:47 +1300
Subject: [time-nuts] How are you going to spend your extra second?
In-Reply-To: <4952ACD0.9080802@pacific.net>
References: <mailman.718.1230150600.2499.time-nuts@febo.com>	<BLU125-W38BF78030AFF1965A7D391CEED0@phx.gbl>
	<4952ACD0.9080802@pacific.net>
Message-ID: <4952AF6B.3020402@xtra.co.nz>

Brooke

Using sound to locate large guns dates back to at least WWI.

Bruce

Brooke Clarke wrote:
> Hi Mark:
>
> It turns out that many large cities in the U.S. have Time Of Arrival systems to 
> locate where a gun is discharged.
> http://www.prc68.com/I/Sensors.shtml#Aco
> The military also uses time of arrival to locate guns:
> http://www.prc68.com/I/RT1185.shtml
> so again the topic is time related.
>
> Have Fun,
>
> Brooke Clarke
> http://www.prc68.com
>
> Mark Sims wrote:
>   
>> Unfortunately, in many US cities,  getting shot on New Years is an all too common occurance.  Knuckle dragging idiots celebrate with lots of booze, ammunition, and firearms.  At the stoke of midnight they unleash a hail of gunfire into the air...  and what goes up tends to come back down.  Inevitably somebody (more often than not, a child) will be in the exact place where something comes down.-------------In swedish leap-second translates to skott-sekund, and skott translates 
>> back to shot, so recalling the recent thread on fire-arms, don't get 
>> shot on the leap-second.
>> _________________________________________________________________
>> Send e-mail anywhere. No map, no compass.
>> http://windowslive.com/oneline/hotmail?ocid=TXT_TAGLM_WL_hotmail_acq_anywhere_122008
>>     



From kirbybq at bellsouth.net  Wed Dec 24 22:25:08 2008
From: kirbybq at bellsouth.net (Brian Kirby)
Date: Wed, 24 Dec 2008 16:25:08 -0600
Subject: [time-nuts] Lady Heather's Disciplined Oscillator (Thunderbolt)
 Software
In-Reply-To: <BLU125-W4125966DA4ABC01F59B4ACCEED0@phx.gbl>
References: <mailman.709.1230137721.2499.time-nuts@febo.com>
	<BLU125-W4125966DA4ABC01F59B4ACCEED0@phx.gbl>
Message-ID: <4952B6C4.7060000@bellsouth.net>

I took it and moved it to a machine I have dedicated to timing.  The 
machine is a 700 Mhz athlon, that can boot 2000, NT and DOS 6.22.

2000 just went back to the command line, NT said its initializing memory 
and went back to the command prompt and DOS 6.22 appeared to run, but It 
put the computer video in a higher resolution than my monitor can support.

I'll give a better report when I have time to move a better monitor to 
the machine....

Brian KD4FM

Mark Sims wrote:
> Lady Heather,  Mistress of the Disciplined Oscillator,  kidnapped me and locked me in Her Dungeon 'o Doom.  She forced me a whip point to write Her a controller program for Her Thunderbolt.  I had no choice but to comply.  When She stepped out to buy some Whip Wax,  I escaped with Her precious code.  
> Lady Heather lives on the outskirts of the Land of the Obsolete and the code is written in Quick-C to run under DOS or WIN98, etc that allow direct access to the hardware.  Default video hardware required is a VGA type controller with VESA compatible BIOS.  It should be easy to modify for more modern environments.
> Her program allows control over most Thunderbolt parameters and graphs the important ones.  It also supports logging data to a file.  It also calculates and graphs ADEV and OADEV of the REPORTED oscillator ppb and PPS values.
> _________________________________________________________________
> It?s the same Hotmail?. If by ?same? you mean up to 70% faster.
> http://windowslive.com/online/hotmail?ocid=TXT_TAGLM_WL_hotmail_acq_broad1_122008
> 
> 
> ------------------------------------------------------------------------
> 
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.


From max at maxsmusicplace.com  Wed Dec 24 23:23:22 2008
From: max at maxsmusicplace.com (Max Robinson)
Date: Wed, 24 Dec 2008 17:23:22 -0600
Subject: [time-nuts] New topics (was Re: He is a Time-Nut
	Troublemaker....)
References: <p06240810c5785f360e1b@[192.168.1.212]>
Message-ID: <96D89022798E45BE91660BC4D4906BAC@BACKROOM>

>>2.  Several measurement techniques require a given phase relationship
>>(e.g., quadrature) between DUT and reference.  For HF frequencies (ie, 5
>>or 10 MHz) is there a *practical* phase shifter design covering 180+
>>degrees that doesn't involve switching various lengths of coax in and
>>out of the line?

There was a Hewlett Packard generator called a two phase oscillator or maybe 
it was two phase function generator.  I forget the model number and don't 
have any way to look it up.   It featured two outputs and a dial calibrated 
from 0 to 359 that would adjust the phase of one output with respect to the 
other.   Behind the panel was a little box which I didn't try to open but 
the manual revealed it to have 3 coils, two at right angles to each other 
and the third one on the shaft.  It operated at 5 MHz.  If memory serves 
correctly, they called it a variable phase transformer.

Regards.

Max.  K 4 O D S.

Email: max at maxsmusicplace.com

Transistor site http://www.funwithtransistors.net
Vacuum tube site: http://www.funwithtubes.net
Music site: http://www.maxsmusicplace.com

To subscribe to the fun with tubes group send an email to,
funwithtubes-subscribe at yahoogroups.com

----- Original Message ----- 
From: "Joe Gwinn" <joegwinn at comcast.net>
To: <time-nuts at febo.com>
Sent: Wednesday, December 24, 2008 3:52 PM
Subject: Re: [time-nuts] New topics (was Re: He is a Time-Nut 
Troublemaker....)


> At 5:05 PM +0000 12/23/08, time-nuts-request at febo.com wrote:
>>Date: Tue, 23 Dec 2008 11:40:51 -0500
>>From: John Ackermann N8UR <jra at febo.com>
>>Subject: [time-nuts] New topics (was Re: He is a Time-Nut
>> Troublemaker....)
>>To: Discussion of precise time and frequency measurement
>> <time-nuts at febo.com>
>>
>>Magnus Danielson wrote:
>>
>>>  My intent is to get some stuff done in the lab during the vacation.
>>>  (Desperatly trying to get some more on-topic discussions going).
>>
>>Here are two questions that have been running around my head:
>>
>>[snip]
>>2.  Several measurement techniques require a given phase relationship
>>(e.g., quadrature) between DUT and reference.  For HF frequencies (ie, 5
>>or 10 MHz) is there a *practical* phase shifter design covering 180+
>>degrees that doesn't involve switching various lengths of coax in and
>>out of the line?
>
> Why the aversion to coax delay lines?  They are simple and reliable.
> The reason will help people to tell what alternatives would be best.
>
> Joe
>
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to 
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>
> 



From n3toy at yahoo.com  Wed Dec 24 23:26:50 2008
From: n3toy at yahoo.com (James R. Gorr)
Date: Wed, 24 Dec 2008 15:26:50 -0800 (PST)
Subject: [time-nuts] How are you going to spend your extra second?
Message-ID: <474020.37443.qm@web54102.mail.re2.yahoo.com>


Not sure what your post has to do with time.  But thanks for your anti-gun political commentary.  

I am going to spend my extra second making up for the time it took me to  delete your post.

--- On Wed, 12/24/08, Mark Sims <holrum at hotmail.com> wrote:

From: Mark Sims <holrum at hotmail.com>
Subject: [time-nuts] How are you going to spend your extra second?
To: time-nuts at febo.com
Date: Wednesday, December 24, 2008, 1:22 PM


Unfortunately, in many US cities,? getting shot on New Years is an all too common occurance.? Knuckle dragging idiots celebrate with lots of booze, ammunition, and firearms.? At the stoke of midnight they unleash a hail of gunfire into the air...? and what goes up tends to come back down.? Inevitably somebody (more often than not, a child) will be in the exact place where something comes down.-------------In swedish leap-second translates to skott-sekund, and skott translates 
back to shot, so recalling the recent thread on fire-arms, don't get 
shot on the leap-second.
_________________________________________________________________
Send e-mail anywhere. No map, no compass.
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From bruce.griffiths at xtra.co.nz  Wed Dec 24 23:34:10 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Thu, 25 Dec 2008 12:34:10 +1300
Subject: [time-nuts] New topics (was Re: He is a
	Time-Nut	Troublemaker....)
In-Reply-To: <96D89022798E45BE91660BC4D4906BAC@BACKROOM>
References: <p06240810c5785f360e1b@[192.168.1.212]>
	<96D89022798E45BE91660BC4D4906BAC@BACKROOM>
Message-ID: <4952C6F2.4080502@xtra.co.nz>

Max

The better versions used a 2 othogonal pairs  of Helmholtz coils, with
the nonmagnetic shaft mounted coil rotating in the centre where the
field is relatively uniform.

Braunbek coils (4 coils rather than 2) produce a more uniform field than
Helmholtz coils.
Braunbek coil sets are used for canceling the Earths magnetic field:
http://www.iop.org/EJ/abstract/0957-0233/6/5/022
http://www.serviciencia.es/folletos/Braunbek-Barker-Examples-1.pdf
http://www.igep.tu-bs.de/institut/einrichtungen/magnetsrode/index_en.htm
<http://www.igep.tu-bs.de/institut/einrichtungen/magnetsrode/index_en.html>l
<http://www.igep.tu-bs.de/institut/einrichtungen/magnetsrode/index_en.html>
http://www.ptb.de/en/org/2/25/251/realization.pdf
http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20050071098_2005071182.pdf


Bruce

Max Robinson wrote:
>>> 2.  Several measurement techniques require a given phase relationship
>>> (e.g., quadrature) between DUT and reference.  For HF frequencies (ie, 5
>>> or 10 MHz) is there a *practical* phase shifter design covering 180+
>>> degrees that doesn't involve switching various lengths of coax in and
>>> out of the line?
>>>       
>
> There was a Hewlett Packard generator called a two phase oscillator or maybe 
> it was two phase function generator.  I forget the model number and don't 
> have any way to look it up.   It featured two outputs and a dial calibrated 
> from 0 to 359 that would adjust the phase of one output with respect to the 
> other.   Behind the panel was a little box which I didn't try to open but 
> the manual revealed it to have 3 coils, two at right angles to each other 
> and the third one on the shaft.  It operated at 5 MHz.  If memory serves 
> correctly, they called it a variable phase transformer.
>
> Regards.
>
> Max.  K 4 O D S.
>
> Email: max at maxsmusicplace.com
>
> Transistor site http://www.funwithtransistors.net
> Vacuum tube site: http://www.funwithtubes.net
> Music site: http://www.maxsmusicplace.com
>
> To subscribe to the fun with tubes group send an email to,
> funwithtubes-subscribe at yahoogroups.com
>
> ----- Original Message ----- 
> From: "Joe Gwinn" <joegwinn at comcast.net>
> To: <time-nuts at febo.com>
> Sent: Wednesday, December 24, 2008 3:52 PM
> Subject: Re: [time-nuts] New topics (was Re: He is a Time-Nut 
> Troublemaker....)
>
>
>   
>> At 5:05 PM +0000 12/23/08, time-nuts-request at febo.com wrote:
>>     
>>> Date: Tue, 23 Dec 2008 11:40:51 -0500
>>> From: John Ackermann N8UR <jra at febo.com>
>>> Subject: [time-nuts] New topics (was Re: He is a Time-Nut
>>> Troublemaker....)
>>> To: Discussion of precise time and frequency measurement
>>> <time-nuts at febo.com>
>>>
>>> Magnus Danielson wrote:
>>>
>>>       
>>>>  My intent is to get some stuff done in the lab during the vacation.
>>>>  (Desperatly trying to get some more on-topic discussions going).
>>>>         
>>> Here are two questions that have been running around my head:
>>>
>>> [snip]
>>> 2.  Several measurement techniques require a given phase relationship
>>> (e.g., quadrature) between DUT and reference.  For HF frequencies (ie, 5
>>> or 10 MHz) is there a *practical* phase shifter design covering 180+
>>> degrees that doesn't involve switching various lengths of coax in and
>>> out of the line?
>>>       
>> Why the aversion to coax delay lines?  They are simple and reliable.
>> The reason will help people to tell what alternatives would be best.
>>
>> Joe
>>
>> _______________________________________________
>> time-nuts mailing list -- time-nuts at febo.com
>> To unsubscribe, go to 
>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>> and follow the instructions there.
>>
>>
>>     
>
>
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>
>   



From m0ycm at veenstras.com  Wed Dec 24 23:35:54 2008
From: m0ycm at veenstras.com (Lester Veenstra)
Date: Wed, 24 Dec 2008 18:35:54 -0500
Subject: [time-nuts] New topics (was Re: He is a
	Time-NutTroublemaker....)
In-Reply-To: <96D89022798E45BE91660BC4D4906BAC@BACKROOM>
References: <p06240810c5785f360e1b@[192.168.1.212]>
	<96D89022798E45BE91660BC4D4906BAC@BACKROOM>
Message-ID: <B26A016720CC40A7998AE80729188979@hp>

A.K.A a Goniometer

 
Lester B Veenstra  M?YCM K1YCM
lester at veenstras.com
m0ycm at veenstras.com
k1ycm at veenstras.com
 
 
US Postal Address:
PSC 45 Box 781
APO AE 09468 USA
 
UK Postal Address:
Dawn Cottage
Norwood, Harrogate
HG3 1SD, UK
 
Telephones:
Office:     +44-(0)1423-846-385
Home:     +44-(0)1943-880-963 
Guam Cell: +1-671-788-5654
UK Cell:   +44-(0)7716-298-224 
US Cell:   +1-240-425-7335 
Jamaica:  +1-876-352-7504 
 
This e-mail and any documents attached hereto contain confidential or
privileged information. The information is intended to be for use only by
the individual or entity to whom they are addressed. If you are not the
intended recipient or the person responsible for delivering the e-mail to
the intended recipient, be aware that any disclosure, copying, distribution
or use of the contents of this e-mail or any documents attached hereto is
prohibited.
-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of Max Robinson
Sent: Wednesday, December 24, 2008 6:23 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] New topics (was Re: He is a
Time-NutTroublemaker....)

>>2.  Several measurement techniques require a given phase relationship
>>(e.g., quadrature) between DUT and reference.  For HF frequencies (ie, 5
>>or 10 MHz) is there a *practical* phase shifter design covering 180+
>>degrees that doesn't involve switching various lengths of coax in and
>>out of the line?

There was a Hewlett Packard generator called a two phase oscillator or maybe

it was two phase function generator.  I forget the model number and don't 
have any way to look it up.   It featured two outputs and a dial calibrated 
from 0 to 359 that would adjust the phase of one output with respect to the 
other.   Behind the panel was a little box which I didn't try to open but 
the manual revealed it to have 3 coils, two at right angles to each other 
and the third one on the shaft.  It operated at 5 MHz.  If memory serves 
correctly, they called it a variable phase transformer.

Regards.

Max.  K 4 O D S.

Email: max at maxsmusicplace.com

Transistor site http://www.funwithtransistors.net
Vacuum tube site: http://www.funwithtubes.net
Music site: http://www.maxsmusicplace.com

To subscribe to the fun with tubes group send an email to,
funwithtubes-subscribe at yahoogroups.com

----- Original Message ----- 
From: "Joe Gwinn" <joegwinn at comcast.net>
To: <time-nuts at febo.com>
Sent: Wednesday, December 24, 2008 3:52 PM
Subject: Re: [time-nuts] New topics (was Re: He is a Time-Nut 
Troublemaker....)


> At 5:05 PM +0000 12/23/08, time-nuts-request at febo.com wrote:
>>Date: Tue, 23 Dec 2008 11:40:51 -0500
>>From: John Ackermann N8UR <jra at febo.com>
>>Subject: [time-nuts] New topics (was Re: He is a Time-Nut
>> Troublemaker....)
>>To: Discussion of precise time and frequency measurement
>> <time-nuts at febo.com>
>>
>>Magnus Danielson wrote:
>>
>>>  My intent is to get some stuff done in the lab during the vacation.
>>>  (Desperatly trying to get some more on-topic discussions going).
>>
>>Here are two questions that have been running around my head:
>>
>>[snip]
>>2.  Several measurement techniques require a given phase relationship
>>(e.g., quadrature) between DUT and reference.  For HF frequencies (ie, 5
>>or 10 MHz) is there a *practical* phase shifter design covering 180+
>>degrees that doesn't involve switching various lengths of coax in and
>>out of the line?
>
> Why the aversion to coax delay lines?  They are simple and reliable.
> The reason will help people to tell what alternatives would be best.
>
> Joe
>
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to 
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>
> 


_______________________________________________
time-nuts mailing list -- time-nuts at febo.com
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https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.


From bill at iaxs.net  Thu Dec 25 00:12:00 2008
From: bill at iaxs.net (Bill Hawkins)
Date: Wed, 24 Dec 2008 18:12:00 -0600
Subject: [time-nuts] How are you going to spend your extra second?
In-Reply-To: <ds65l49rq9vph63npq2gph2nt4127dbmaq@4ax.com>
References: <mailman.709.1230137721.2499.time-nuts@febo.com><BLU125-W30C12D745935B851A41CD8CEED0@phx.gbl>
	<ds65l49rq9vph63npq2gph2nt4127dbmaq@4ax.com>
Message-ID: <574F698B698E42A58F571DC699B069AD@cyrus>

Good one, John.

Hope we never have to account for personal time to the second . . .

Bill Hawkins 

-----Original Message-----
From: Neon John
Sent: Wednesday, December 24, 2008 2:30 PM
>Well,  the lords of time have blessed us this year with a whole extra
second of existence.  How are you going to use yours?

Dunno.  Let me think about it for a sec.

ooops...

Merry Christmas all

John
--



From holrum at hotmail.com  Thu Dec 25 01:11:10 2008
From: holrum at hotmail.com (Mark Sims)
Date: Thu, 25 Dec 2008 01:11:10 +0000
Subject: [time-nuts] How are you going to spend your extra second?
In-Reply-To: <mailman.720.1230161216.2499.time-nuts@febo.com>
References: <mailman.720.1230161216.2499.time-nuts@febo.com>
Message-ID: <BLU125-W8AB056F358DD9103CE19ACEEA0@phx.gbl>


James,
If you had read my previous post you would have realized I am far from an anti-gun political nut.  I have an arsenal that would make Sadaam blush (over 100 pieces,  mostly military models from .17 cal to .50BMG).  I paid for the HP45 calculator that put me through engineering school by shooting rabbits for ranchers.  I was seventh in the nation in a Naval postal match.  What I am against is nutcases that spoil the fun for the rest of us by doing things like unloading a few magazines of ammo into the sky in the middle of a crowded city.
_________________________________________________________________
It?s the same Hotmail?. If by ?same? you mean up to 70% faster.
http://windowslive.com/online/hotmail?ocid=TXT_TAGLM_WL_hotmail_acq_broad1_122008

From jltran at worldnet.att.net  Thu Dec 25 01:16:54 2008
From: jltran at worldnet.att.net (J. L. Trantham)
Date: Wed, 24 Dec 2008 19:16:54 -0600
Subject: [time-nuts] How are you going to spend your extra second?
In-Reply-To: <BLU125-W8AB056F358DD9103CE19ACEEA0@phx.gbl>
Message-ID: <AF981DA3FEED485083544500E03E4C9A@S0028384766>

Amen!

And Merry Christmas and Happy New Year to the entire list.

This is a great group!

Joe

-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of Mark Sims
Sent: Wednesday, December 24, 2008 7:11 PM
To: time-nuts at febo.com
Subject: [time-nuts] How are you going to spend your extra second?


James,
If you had read my previous post you would have realized I am far from an
anti-gun political nut.  I have an arsenal that would make Sadaam blush
(over 100 pieces,  mostly military models from .17 cal to .50BMG).  I paid
for the HP45 calculator that put me through engineering school by shooting
rabbits for ranchers.  I was seventh in the nation in a Naval postal match.
What I am against is nutcases that spoil the fun for the rest of us by doing
things like unloading a few magazines of ammo into the sky in the middle of
a crowded city.
_________________________________________________________________
It's the same HotmailR. If by "same" you mean up to 70% faster.
http://windowslive.com/online/hotmail?ocid=TXT_TAGLM_WL_hotmail_acq_broad1_1
22008
_______________________________________________
time-nuts mailing list -- time-nuts at febo.com
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.



From jgd at johngsbbq.com  Thu Dec 25 01:32:18 2008
From: jgd at johngsbbq.com (Neon John)
Date: Wed, 24 Dec 2008 20:32:18 -0500
Subject: [time-nuts] OT: Forum <--> email gateway/bridge
Message-ID: <rao5l45hafkcrc2qq71and41598cmrob0r@4ax.com>

this is completely off-topic (so please reply via direct email) but since this
is the greatest brain trust on the internet, I thought I'd risk asking the
question.

I can't stand web forums.  My loathing goes beyond hatred.  Even worse now
that I'm stuck back on dial-up again.  Unfortunately there are some areas of
my interest that simply aren't covered by mailing lists.  Fora only.  I've
tried, I really have, to adapt but I can't.

So.

What I'm looking for is a third party application that will gateway or bridge
selected fora to email.  I'd like to point it at a forum or sub-forum and have
it convert each new message into email and send it to me, and in turn take my
replies and convert them into forum posts.  In-line photos could be either
dropped or turned into URLs.  Ideally Linux-based (debian) so that I could
install it on my web host.

Anyone know of anything like this?  Surely I'm not the only forum-hater out
there.

Thanks,
John

And Merry Christmas to all.

--
John De Armond
See my website for my current email address
http://www.neon-john.com
http://www.johndearmond.com <-- best little blog on the net!
Tellico Plains, Occupied TN
Okay, okay, I'll take it back ... UNfuck you!



From holrum at hotmail.com  Thu Dec 25 01:38:03 2008
From: holrum at hotmail.com (Mark Sims)
Date: Thu, 25 Dec 2008 01:38:03 +0000
Subject: [time-nuts] Lady Heather's Disciplined Oscillator (Thunderbolt)
	Software
In-Reply-To: <mailman.720.1230161216.2499.time-nuts@febo.com>
References: <mailman.720.1230161216.2499.time-nuts@febo.com>
Message-ID: <BLU125-W38C3C5114757E3B803DF9ACEEA0@phx.gbl>


The program attempts to allocate quite a bit of memory  for its plot and ADEV buffers.  It assumes it is running in a 640K memory space under DOS/WIN98.   I suspect that WIN2000, etc have more overhead,  hence the memory/startup errors.  The buffers are  allocated as old style HUGE memory arrays (so that  they can be> 64kb) that manipulate the real mode X86 memory segment registers with each access...  might also cause problems with the later operating systems. 

The supported graphics video mode is defined at compile time.  There are compile options for 800x600,  1024x768, or 1280x1024 res screens.  You can also run it in a text only mode with the /T command line option.  If you can't get it working with a 1024x768 screen,  I can send you the version compiled for a 800x600 screen (but  you lose a bit of goodness with the smaller screen).  You don't gain a whole bunch of goodness going to 1280x1024 (just a bigger graph area).

The program uses the old school technology so that it is easy and cheap to dedicate a $20 surplus laptop as the GPSDO controller.  I am using it with Compaq Armadas (200 MHz) and Fujitsu Milan (90 MHz) laptops.
_________________________________________________________________
Life on your PC is safer, easier, and more enjoyable with Windows Vista?. 
http://clk.atdmt.com/MRT/go/127032870/direct/01/

From n3toy at yahoo.com  Thu Dec 25 01:50:49 2008
From: n3toy at yahoo.com (James R. Gorr)
Date: Wed, 24 Dec 2008 17:50:49 -0800 (PST)
Subject: [time-nuts] How are you going to spend your extra second?
Message-ID: <625009.5418.qm@web54109.mail.re2.yahoo.com>


Maybe I jumped the gun... (no pun intended).  My apologies, I must not have gone back far enough.

Ok, maybe the pun was intended.  :-)

--- On Wed, 12/24/08, Mark Sims <holrum at hotmail.com> wrote:

From: Mark Sims <holrum at hotmail.com>
Subject: [time-nuts] How are you going to spend your extra second?
To: time-nuts at febo.com
Date: Wednesday, December 24, 2008, 5:11 PM


James,
If you had read my previous post you would have realized I am far from an anti-gun political nut.? I have an arsenal that would make Sadaam blush (over 100 pieces,? mostly military models from .17 cal to .50BMG).? I paid for the HP45 calculator that put me through engineering school by shooting rabbits for ranchers.? I was seventh in the nation in a Naval postal match.? What I am against is nutcases that spoil the fun for the rest of us by doing things like unloading a few magazines of ammo into the sky in the middle of a crowded city.
_________________________________________________________________
It?s the same Hotmail?. If by ?same? you mean up to 70% faster.
http://windowslive.com/online/hotmail?ocid=TXT_TAGLM_WL_hotmail_acq_broad1_122008
_______________________________________________
time-nuts mailing list -- time-nuts at febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.



      


From hmurray at megapathdsl.net  Thu Dec 25 02:01:16 2008
From: hmurray at megapathdsl.net (Hal Murray)
Date: Wed, 24 Dec 2008 18:01:16 -0800
Subject: [time-nuts] How are you going to spend your extra second?
In-Reply-To: Message from Mark Sims <holrum@hotmail.com> of "Wed,
	24 Dec 2008 21:22:09 GMT."
	<BLU125-W38BF78030AFF1965A7D391CEED0@phx.gbl> 
Message-ID: <20081225020117.E1DCBBCD7@ip-64-139-1-69.sjc.megapath.net>


> In swedish leap-second translates to skott-sekund, and
> skott translates back to shot, so recalling the recent thread
> on fire-arms, don't get shot on the leap-second.

That seems backwards.  Getting shot would make more sense if we were deleting 
(killing) leap-seconds rather than adding/inserting them.


-- 
These are my opinions, not necessarily my employer's.  I hate spam.





From magnus at rubidium.dyndns.org  Thu Dec 25 02:35:57 2008
From: magnus at rubidium.dyndns.org (Magnus Danielson)
Date: Thu, 25 Dec 2008 03:35:57 +0100
Subject: [time-nuts] How are you going to spend your extra second?
In-Reply-To: <20081225020117.E1DCBBCD7@ip-64-139-1-69.sjc.megapath.net>
References: <20081225020117.E1DCBBCD7@ip-64-139-1-69.sjc.megapath.net>
Message-ID: <4952F18D.3060007@rubidium.dyndns.org>

Hal Murray skrev:
>> In swedish leap-second translates to skott-sekund, and
>> skott translates back to shot, so recalling the recent thread
>> on fire-arms, don't get shot on the leap-second.
> 
> That seems backwards.  Getting shot would make more sense if we were deleting 
> (killing) leap-seconds rather than adding/inserting them.

Well, think of it as the second in which he was shot. I think he would 
rather have leaped over that particular second if possible. :)

Didn't help did it? :)

Think of it as shoot-in (skjuta in) as the action of insertion, 
inserting a second.

Leap-seconds act both ways, so it also means the second we did not have, 
that we shoot-out.

Cheers,
Magnus



From cfharris at erols.com  Thu Dec 25 04:12:49 2008
From: cfharris at erols.com (Chuck Harris)
Date: Wed, 24 Dec 2008 23:12:49 -0500
Subject: [time-nuts] How are you going to spend your extra second?
In-Reply-To: <BLU125-W38BF78030AFF1965A7D391CEED0@phx.gbl>
References: <mailman.718.1230150600.2499.time-nuts@febo.com>
	<BLU125-W38BF78030AFF1965A7D391CEED0@phx.gbl>
Message-ID: <49530841.1070204@erols.com>

Really?  I would think it would make the papers... but for
some reason, it doesn't.

-Chuck Harris

Mark Sims wrote:
> Unfortunately, in many US cities,  getting shot on New Years is an all too common occurance.  Knuckle dragging idiots celebrate with lots of booze, ammunition, and firearms.  At the stoke of midnight they unleash a hail of gunfire into the air...  and what goes up tends to come back down.  Inevitably somebody (more often than not, a child) will be in the exact place where something comes down.-------------In swedish leap-second translates to skott-sekund, and skott translates 
> back to shot, so recalling the recent thread on fire-arms, don't get 
> shot on the leap-second.
> _________________________________________________________________
> Send e-mail anywhere. No map, no compass.
> http://windowslive.com/oneline/hotmail?ocid=TXT_TAGLM_WL_hotmail_acq_anywhere_122008
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
> 


From cfharris at erols.com  Thu Dec 25 04:44:44 2008
From: cfharris at erols.com (Chuck Harris)
Date: Wed, 24 Dec 2008 23:44:44 -0500
Subject: [time-nuts] New topics (was Re: He is
	aTime-Nut	Troublemaker....)
In-Reply-To: <F3B89D59B2774310A86386BEC90AC35A@didierhp>
References: <mailman.600.1229917104.2499.time-nuts@febo.com>	<BLU125-W46831CE6F2E119B7EEBE6CCEEF0@phx.gbl>	<494F1DA4.4000106@xtra.co.nz>	<494F969B.1030604@erols.com>	<494FEC59.90905@xtra.co.nz>	<494FF0B8.4030809@xtra.co.nz>	<494FF7B7.2020403@xtra.co.nz>	<495050CE.5020704@pacific.net>	<495083D2.8010503@erols.com>	<49510EA9.5030100@wwrinc.com>	<49511170.2080600@rubidium.dyndns.org>	<49511493.4090803@febo.com>	<49511F18.7050903@rubidium.dyndns.org><495126A7.7080500@febo.com>	<495127DA.5030903@rubidium.dyndns.org><0C1BA262774A4C0289449218537A9D61@didierhp>	<49518AA6.90401@rubidium.dyndns.org><CA6A9764C28C4BE193016C3BB13F1D8E@didierhp>	<49525CFE.8070802@erols.com>
	<F3B89D59B2774310A86386BEC90AC35A@didierhp>
Message-ID: <49530FBC.5050306@erols.com>

Hi Didier,

I presumed you at one time knew the difference between voltage
ratio, and power ratio dB, but your question gave the impression
that you might have needed a tiny nudge to refresh your memory.

If both oscillators are in lock step, you obviously can combine
them using an appropriately wound transformer to gain a 3dB increase
in power.  But it would seem that the noise, being random and
independent, should add constructively as often as destructively.

I don't know the answer to your question... I did once, but that was
30 years ago... but I get the feeling that the noise power is going
to add up as some fractional power giving you a net improvement
in signal to noise... probably close to 3dB, but not quite 3dB...
I just don't remember anymore.

-Chuck Harris

Didier wrote:
> Chuck,
> 
> I am quite familiar with how to calculate a voltage or power ratio in dB,
> but refering to the first issue, when you combine two oscillators, does the
> noise improve by 3dB?
> 
> Didier


From brooke at pacific.net  Thu Dec 25 05:00:49 2008
From: brooke at pacific.net (Brooke Clarke)
Date: Wed, 24 Dec 2008 21:00:49 -0800
Subject: [time-nuts] Lady Heather's Disciplined Oscillator (Thunderbolt)
 Software
In-Reply-To: <49527D28.80303@stny.rr.com>
References: <mailman.709.1230137721.2499.time-nuts@febo.com>	<BLU125-W4125966DA4ABC01F59B4ACCEED0@phx.gbl>
	<49527D28.80303@stny.rr.com>
Message-ID: <49531381.4080208@pacific.net>

Hi Norman:

For more on Lady Heather, see:

Lady Heather's Box
http://www.imdb.com/title/tt0534712/

Melinda Clarke (related?)
http://www.imdb.com/name/nm0164918/

Have Fun,

Brooke Clarke
http://www.prc68.com

Norman J McSweyn wrote:
> Who cares about T and F!
> More about Lady Heather, please!




From holrum at hotmail.com  Thu Dec 25 05:00:49 2008
From: holrum at hotmail.com (Mark Sims)
Date: Thu, 25 Dec 2008 05:00:49 +0000
Subject: [time-nuts] How are you going to spend your extra second?
In-Reply-To: <mailman.727.1230169852.2499.time-nuts@febo.com>
References: <mailman.727.1230169852.2499.time-nuts@febo.com>
Message-ID: <BLU125-W38FC92FC0DFB0193992D17CEEA0@phx.gbl>


Hello Chuck,

You must not be reading the same papers as me (or live in Dallas)...    Google "dallas new years gunfire" to get 63,900 hits.  The Wikipedia article has an interesting statistic...  bullets falling from the sky are 5-15 times as likely to be fatal as direct gunshot wounds.  A couple of articles to start with:

http://en.wikipedia.org/wiki/Celebratory_gunfire



http://www.upi.com/Top_News/2002/12/31/New_Years_Eve_gunfire_may_bring_jail_time/UPI-67071041369090/


http://cbs11tv.com/local/Dallas.Police.Warn.2.620823.html


------------

Really?  I would think it would make the papers... but for
some reason, it doesn't.

-Chuck Harris


_________________________________________________________________
Send e-mail anywhere. No map, no compass.
http://windowslive.com/oneline/hotmail?ocid=TXT_TAGLM_WL_hotmail_acq_anywhere_122008

From holrum at hotmail.com  Thu Dec 25 05:13:13 2008
From: holrum at hotmail.com (Mark Sims)
Date: Thu, 25 Dec 2008 05:13:13 +0000
Subject: [time-nuts] How are you going to spend your extra second?
In-Reply-To: <mailman.727.1230169852.2499.time-nuts@febo.com>
References: <mailman.727.1230169852.2499.time-nuts@febo.com>
Message-ID: <BLU125-W54EE278E6F4178B3F035B9CEEA0@phx.gbl>


The acoustic gunfire systems are neat.  A lot of them are located on cell phone towers.  I played around (just for fun) with a time-of-arrival system using a PC sound card and locating a beeper/cell phone inside an auditorium once.  Worked fairly well.  Echoes are a problem in the real world.
Unfortunately these system are rather useless on New Years eve...  overwhelmed by the ruccus.  To see what they are up against check out this youtube recording of last year in Garland, Texas (a medium sized  suburb of Dallas).  And by the way,  the amount of gunfire is way down over the last few years.

http://www.youtube.com/watch?v=FgvaZs-2vxc

_________________________________________________________________
Life on your PC is safer, easier, and more enjoyable with Windows Vista?. 
http://clk.atdmt.com/MRT/go/127032870/direct/01/

From rdarlington at gmail.com  Thu Dec 25 13:59:52 2008
From: rdarlington at gmail.com (Robert Darlington)
Date: Thu, 25 Dec 2008 06:59:52 -0700
Subject: [time-nuts] How are you going to spend your extra second?
In-Reply-To: <BLU125-W38FC92FC0DFB0193992D17CEEA0@phx.gbl>
References: <mailman.727.1230169852.2499.time-nuts@febo.com>
	<BLU125-W38FC92FC0DFB0193992D17CEEA0@phx.gbl>
Message-ID: <b3bd5fcb0812250559y1272737bn2afbf0e1c8ec0c0c@mail.gmail.com>

Bullets falling from the sky are almost never fatal.  Remember, we're
not in a vacuum so there is friction with the atmosphere.  They slow
down on the way up due to both gravity and friction, and then fall
back down reaching a terminal velocity where the bullet is in
equilibrium on the way down (no acceleration).   I've heard of one
case where a bullet falling was fatal when it landed on an infant's
"soft spot" on top of the head where the skull had not yet fused.  One
other recent case where a bullet landed on a lady's shoulder and left
a nice bruise.  I found this descriptive blurb on the net with some
real numbers:

For further insight, we turn to Hatcher's Notebook (1962) by Major
General Julian S. Hatcher, a U.S. Army ordnance expert. Hatcher
described military tests with, among other things, a .30 caliber
bullet weighing .021 pounds. Using a special rig, the testers shot the
bullet straight into the air. It came down bottom (not point) first at
what was later computed to be about 300 feet per second. "With the
[.021 pound] bullet, this corresponds to an energy of 30 foot pounds,"
Hatcher wrote. "Previously, the army had decided that on the average
an energy of 60 foot pounds is required to produce a disabling wound.
Thus, service bullets returning from extreme heights cannot be
considered lethal by this standard."


I for one wouldn't want to be hit by a falling bullet, but I'd sure
take that over one being fired directly at me!

-Bob



On Wed, Dec 24, 2008 at 10:00 PM, Mark Sims <holrum at hotmail.com> wrote:
>
> Hello Chuck,
>
> You must not be reading the same papers as me (or live in Dallas)...    Google "dallas new years gunfire" to get 63,900 hits.  The Wikipedia article has an interesting statistic...  bullets falling from the sky are 5-15 times as likely to be fatal as direct gunshot wounds.  A couple of articles to start with:
>
> http://en.wikipedia.org/wiki/Celebratory_gunfire
>
>
>
> http://www.upi.com/Top_News/2002/12/31/New_Years_Eve_gunfire_may_bring_jail_time/UPI-67071041369090/
>
>
> http://cbs11tv.com/local/Dallas.Police.Warn.2.620823.html
>
>
> ------------
>
> Really?  I would think it would make the papers... but for
> some reason, it doesn't.
>
> -Chuck Harris
>
>
> _________________________________________________________________
> Send e-mail anywhere. No map, no compass.
> http://windowslive.com/oneline/hotmail?ocid=TXT_TAGLM_WL_hotmail_acq_anywhere_122008
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>


From didier at cox.net  Thu Dec 25 14:29:37 2008
From: didier at cox.net (Didier Juges)
Date: Thu, 25 Dec 2008 08:29:37 -0600
Subject: [time-nuts] New topics (was Re: He isaTime-Nut	Troublemaker....)
In-Reply-To: <49530FBC.5050306@erols.com>
Message-ID: <20081225142942.LIJC18445.eastrmmtao103.cox.net@eastrmimpo01.cox.net>

Chuck,

That was exactly my point. I have used phase combining of power amplifiers
to increase power and I know it improves broadband noise performance (noise
figure) even though that is usually not why we combine power amplifiers. My
last phase-combined amplifier combines two 100W Ku band TWTs for a very
compact airborne 200W satellite transmitter (much shorter than if I had been
using a 200W TWT, which was a requirement in order to fit in a small
diameter unit)

For power amplifiers, the improvement in noise figure (broad band,
uncorrelated noise) is about 3dB, but I am not sure it applies when you
combine two similar oscillators that may have a similar noise pattern. For
instance, combining TWTs does not improve power supply ripple induced
sidebands of course (when both tubes operate from the same supply). I would
expect that combining low noise osacillators will improve the random noise
by close to 3dB, but not all oscillator perturbations are broadband
uncorrelated. Particularly, the supply induced, temperature and load pulling
variations will not improve at all, limiting the benefits of the technique
for low noise oscillators.

The cost in complexity for combining oscillators is much more significant
than for amplifiers. Amplifiers only need phase matching (electrical
length). Oscillators need to be phase locked to begin with.

Merry Christmas to all.

Didier KO4BB

-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of Chuck Harris
Sent: Wednesday, December 24, 2008 10:45 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] New topics (was Re: He isaTime-Nut
Troublemaker....)

Hi Didier,

I presumed you at one time knew the difference between voltage ratio, and
power ratio dB, but your question gave the impression that you might have
needed a tiny nudge to refresh your memory.

If both oscillators are in lock step, you obviously can combine them using
an appropriately wound transformer to gain a 3dB increase in power.  But it
would seem that the noise, being random and independent, should add
constructively as often as destructively.

I don't know the answer to your question... I did once, but that was 30
years ago... but I get the feeling that the noise power is going to add up
as some fractional power giving you a net improvement in signal to noise...
probably close to 3dB, but not quite 3dB...
I just don't remember anymore.

-Chuck Harris

Didier wrote:
> Chuck,
> 
> I am quite familiar with how to calculate a voltage or power ratio in 
> dB, but refering to the first issue, when you combine two oscillators, 
> does the noise improve by 3dB?
> 
> Didier

_______________________________________________
time-nuts mailing list -- time-nuts at febo.com To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.




From rdarlington at gmail.com  Thu Dec 25 16:44:12 2008
From: rdarlington at gmail.com (Robert Darlington)
Date: Thu, 25 Dec 2008 09:44:12 -0700
Subject: [time-nuts] How are you going to spend your extra second?
In-Reply-To: <b3bd5fcb0812250559y1272737bn2afbf0e1c8ec0c0c@mail.gmail.com>
References: <mailman.727.1230169852.2499.time-nuts@febo.com>
	<BLU125-W38FC92FC0DFB0193992D17CEEA0@phx.gbl>
	<b3bd5fcb0812250559y1272737bn2afbf0e1c8ec0c0c@mail.gmail.com>
Message-ID: <b3bd5fcb0812250844g4c2973b5m10f53945773e192b@mail.gmail.com>

Hey, I just wanted to clarify a statement I made, in particular the
first one.  I stand by it, but put it in the context that stray
bullets falling rarely hit anybody.   Of those that do come down,
large caliber rounds certainly can cause trauma, but even then usually
not enough to cause death.  The statistical blip mentioned in the
Wikipedia article probably has some merit, just not enough for me to
worry about.  The smaller caliber rounds (pronounced "lighter" or
"less massive") that we would typically see in the USA are of
extremely low concern when compared to the larger .30 or .50 cal rifle
rounds you might see elsewhere during celebrations.  I'm certainly not
saying it doesn't happen, I'm saying it's rare.  Focus on eating less
cheeseburgers or wearing seat belts more often if you want to save
lives!

As for me, I will be driving to the target range today while wearing a
seat belt, shooting my .308 in the cold, and won't be eating a burger
-but I had one yesterday!

On Thu, Dec 25, 2008 at 6:59 AM, Robert Darlington
<rdarlington at gmail.com> wrote:
> Bullets falling from the sky are almost never fatal.  Remember, we're
> not in a vacuum so there is friction with the atmosphere.  They slow
> down on the way up due to both gravity and friction, and then fall
> back down reaching a terminal velocity where the bullet is in
> equilibrium on the way down (no acceleration).   I've heard of one
> case where a bullet falling was fatal when it landed on an infant's
> "soft spot" on top of the head where the skull had not yet fused.  One
> other recent case where a bullet landed on a lady's shoulder and left
> a nice bruise.  I found this descriptive blurb on the net with some
> real numbers:
>
> For further insight, we turn to Hatcher's Notebook (1962) by Major
> General Julian S. Hatcher, a U.S. Army ordnance expert. Hatcher
> described military tests with, among other things, a .30 caliber
> bullet weighing .021 pounds. Using a special rig, the testers shot the
> bullet straight into the air. It came down bottom (not point) first at
> what was later computed to be about 300 feet per second. "With the
> [.021 pound] bullet, this corresponds to an energy of 30 foot pounds,"
> Hatcher wrote. "Previously, the army had decided that on the average
> an energy of 60 foot pounds is required to produce a disabling wound.
> Thus, service bullets returning from extreme heights cannot be
> considered lethal by this standard."
>
>
> I for one wouldn't want to be hit by a falling bullet, but I'd sure
> take that over one being fired directly at me!
>
> -Bob
>
>
>
> On Wed, Dec 24, 2008 at 10:00 PM, Mark Sims <holrum at hotmail.com> wrote:
>>
>> Hello Chuck,
>>
>> You must not be reading the same papers as me (or live in Dallas)...    Google "dallas new years gunfire" to get 63,900 hits.  The Wikipedia article has an interesting statistic...  bullets falling from the sky are 5-15 times as likely to be fatal as direct gunshot wounds.  A couple of articles to start with:
>>
>> http://en.wikipedia.org/wiki/Celebratory_gunfire
>>
>>
>>
>> http://www.upi.com/Top_News/2002/12/31/New_Years_Eve_gunfire_may_bring_jail_time/UPI-67071041369090/
>>
>>
>> http://cbs11tv.com/local/Dallas.Police.Warn.2.620823.html
>>
>>
>> ------------
>>
>> Really?  I would think it would make the papers... but for
>> some reason, it doesn't.
>>
>> -Chuck Harris
>>
>>
>> _________________________________________________________________
>> Send e-mail anywhere. No map, no compass.
>> http://windowslive.com/oneline/hotmail?ocid=TXT_TAGLM_WL_hotmail_acq_anywhere_122008
>> _______________________________________________
>> time-nuts mailing list -- time-nuts at febo.com
>> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>> and follow the instructions there.
>>
>


From biwa at att.net  Thu Dec 25 19:39:35 2008
From: biwa at att.net (Burt I. Weiner)
Date: Thu, 25 Dec 2008 11:39:35 -0800
Subject: [time-nuts] From K6OQK...
Message-ID: <7.0.0.16.2.20081225113842.03609320@att.net>

 From our home to your's, best wishes for the Christmas and our 
sincere hopes that the New Year will bring continued good health and 
much contentment.

Burt K6OQK and Margaret

Burt I. Weiner Associates
Broadcast Technical Services
Glendale, California  U.S.A.
biwa at att.net
K6OQK 



From saidjack at aol.com  Thu Dec 25 23:57:03 2008
From: saidjack at aol.com (Said Jackson)
Date: Thu, 25 Dec 2008 15:57:03 -0800
Subject: [time-nuts] How are you going to spend your extra second?
In-Reply-To: <b3bd5fcb0812250844g4c2973b5m10f53945773e192b@mail.gmail.com>
References: <mailman.727.1230169852.2499.time-nuts@febo.com>
	<BLU125-W38FC92FC0DFB0193992D17CEEA0@phx.gbl>
	<b3bd5fcb0812250559y1272737bn2afbf0e1c8ec0c0c@mail.gmail.com>
	<b3bd5fcb0812250844g4c2973b5m10f53945773e192b@mail.gmail.com>
Message-ID: <83F4BFFD-AEF1-466A-9487-EF65981D1DD4@aol.com>

Hi guys, most problems will originate when bullets are fired at say 45  
degree angles and thus have significant velocity left. Someone was  
killed here in silicon valley by such a stray some years ago. Bye said

 From iPhone

On Dec 25, 2008, at 8:44, "Robert Darlington" <rdarlington at gmail.com>  
wrote:

> Hey, I just wanted to clarify a statement I made, in particular the
> first one.  I stand by it, but put it in the context that stray
> bullets falling rarely hit anybody.   Of those that do come down,
> large caliber rounds certainly can cause trauma, but even then usually
> not enough to cause death.  The statistical blip mentioned in the
> Wikipedia article probably has some merit, just not enough for me to
> worry about.  The smaller caliber rounds (pronounced "lighter" or
> "less massive") that we would typically see in the USA are of
> extremely low concern when compared to the larger .30 or .50 cal rifle
> rounds you might see elsewhere during celebrations.  I'm certainly not
> saying it doesn't happen, I'm saying it's rare.  Focus on eating less
> cheeseburgers or wearing seat belts more often if you want to save
> lives!
>
> As for me, I will be driving to the target range today while wearing a
> seat belt, shooting my .308 in the cold, and won't be eating a burger
> -but I had one yesterday!
>
> On Thu, Dec 25, 2008 at 6:59 AM, Robert Darlington
> <rdarlington at gmail.com> wrote:
>> Bullets falling from the sky are almost never fatal.  Remember, we're
>> not in a vacuum so there is friction with the atmosphere.  They slow
>> down on the way up due to both gravity and friction, and then fall
>> back down reaching a terminal velocity where the bullet is in
>> equilibrium on the way down (no acceleration).   I've heard of one
>> case where a bullet falling was fatal when it landed on an infant's
>> "soft spot" on top of the head where the skull had not yet fused.   
>> One
>> other recent case where a bullet landed on a lady's shoulder and left
>> a nice bruise.  I found this descriptive blurb on the net with some
>> real numbers:
>>
>> For further insight, we turn to Hatcher's Notebook (1962) by Major
>> General Julian S. Hatcher, a U.S. Army ordnance expert. Hatcher
>> described military tests with, among other things, a .30 caliber
>> bullet weighing .021 pounds. Using a special rig, the testers shot  
>> the
>> bullet straight into the air. It came down bottom (not point) first  
>> at
>> what was later computed to be about 300 feet per second. "With the
>> [.021 pound] bullet, this corresponds to an energy of 30 foot  
>> pounds,"
>> Hatcher wrote. "Previously, the army had decided that on the average
>> an energy of 60 foot pounds is required to produce a disabling wound.
>> Thus, service bullets returning from extreme heights cannot be
>> considered lethal by this standard."
>>
>>
>> I for one wouldn't want to be hit by a falling bullet, but I'd sure
>> take that over one being fired directly at me!
>>
>> -Bob
>>
>>
>>
>> On Wed, Dec 24, 2008 at 10:00 PM, Mark Sims <holrum at hotmail.com>  
>> wrote:
>>>
>>> Hello Chuck,
>>>
>>> You must not be reading the same papers as me (or live in  
>>> Dallas)...    Google "dallas new years gunfire" to get 63,900  
>>> hits.  The Wikipedia article has an interesting statistic...   
>>> bullets falling from the sky are 5-15 times as likely to be fatal  
>>> as direct gunshot wounds.  A couple of articles to start with:
>>>
>>> http://en.wikipedia.org/wiki/Celebratory_gunfire
>>>
>>>
>>>
>>> http://www.upi.com/Top_News/2002/12/31/New_Years_Eve_gunfire_may_bring_jail_time/UPI-67071041369090/
>>>
>>>
>>> http://cbs11tv.com/local/Dallas.Police.Warn.2.620823.html
>>>
>>>
>>> ------------
>>>
>>> Really?  I would think it would make the papers... but for
>>> some reason, it doesn't.
>>>
>>> -Chuck Harris
>>>
>>>
>>> _________________________________________________________________
>>> Send e-mail anywhere. No map, no compass.
>>> http://windowslive.com/oneline/hotmail?ocid=TXT_TAGLM_WL_hotmail_acq_anywhere_122008
>>> _______________________________________________
>>> time-nuts mailing list -- time-nuts at febo.com
>>> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>>> and follow the instructions there.
>>>
>>
>
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.


From mccorkle at ptialaska.net  Fri Dec 26 08:04:51 2008
From: mccorkle at ptialaska.net (Richard H McCorkle)
Date: Thu, 25 Dec 2008 23:04:51 -0900 (AKST)
Subject: [time-nuts] Happy Holidays
Message-ID: <23166.206.174.20.67.1230278691.squirrel@mymail.acsalaska.net>

Ho Ho Ho

Merry Christmas from the far north to all the
Time-Nuts. As a gift for the holidays I have
created a free version of the PICTIC for you
and Didier has kindly posted the files at:

http://www.ko4bb.com/dokuwiki/doku.php?id=precision_timing:pictic


And to all a good night,

Richard



From jherrero at hvsistemas.es  Fri Dec 26 08:17:15 2008
From: jherrero at hvsistemas.es (Javier Herrero)
Date: Fri, 26 Dec 2008 09:17:15 +0100
Subject: [time-nuts] Lady Heather's Disciplined Oscillator (Thunderbolt)
 Software
In-Reply-To: <49531381.4080208@pacific.net>
References: <mailman.709.1230137721.2499.time-nuts@febo.com>	<BLU125-W4125966DA4ABC01F59B4ACCEED0@phx.gbl>	<49527D28.80303@stny.rr.com>
	<49531381.4080208@pacific.net>
Message-ID: <4954930B.5000700@hvsistemas.es>

Oh, she was THAT Lady Heather? ;)

Regards,

Javier

Brooke Clarke escribi?:
> Hi Norman:
>
> For more on Lady Heather, see:
>
> Lady Heather's Box
> http://www.imdb.com/title/tt0534712/
>
> Melinda Clarke (related?)
> http://www.imdb.com/name/nm0164918/
>
> Have Fun,
>
> Brooke Clarke
> http://www.prc68.com
>
> Norman J McSweyn wrote:
>> Who cares about T and F!
>> More about Lady Heather, please!
>
>
>
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>
>

-- 
------------------------------------------------------------------------
Javier Herrero                            EMAIL: jherrero at hvsistemas.com
HV Sistemas S.L.                          PHONE:         +34 949 336 806
Los Charcones, 17A                        FAX:           +34 949 336 792
19170 El Casar - Guadalajara - Spain      WEB: http://www.hvsistemas.com



From bruce.griffiths at xtra.co.nz  Fri Dec 26 09:21:49 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Fri, 26 Dec 2008 22:21:49 +1300
Subject: [time-nuts] Happy Holidays
In-Reply-To: <23166.206.174.20.67.1230278691.squirrel@mymail.acsalaska.net>
References: <23166.206.174.20.67.1230278691.squirrel@mymail.acsalaska.net>
Message-ID: <4954A22D.10802@xtra.co.nz>

Richard H McCorkle wrote:
> Ho Ho Ho
>
> Merry Christmas from the far north to all the
> Time-Nuts. As a gift for the holidays I have
> created a free version of the PICTIC for you
> and Didier has kindly posted the files at:
>
> http://www.ko4bb.com/dokuwiki/doku.php?id=precision_timing:pictic
>
>
> And to all a good night,
>
> Richard
>
>
>   
Richard

Your analog interpolator needs a little work.
The switching speed of the 2N3906's is so slow because the 2N3906's that
switch the current to ground or into the 470pF cap are saturated.
They will switch much faster if used as current mode switches.
In fact you can just replace the 2N3906 whose collector is connected to
the 470pF cap with a fast switching diode and the current source will be
switched much faster.
The 2N7000's have a relatively high non linear output capacitance
replacing them with something like 1/6X 74HC05 would be better.
The 470pF silver mica caps will have relatively large dielectric absorption.
NP0/C0G caps would be a better choice, particularly if higher input
pulse rates were to be used.

Have you actually measured the linearity of the interpolator?


Bruce



From marks at twotoe.com  Fri Dec 26 10:04:24 2008
From: marks at twotoe.com (Mark Stephens)
Date: Fri, 26 Dec 2008 21:04:24 +1100
Subject: [time-nuts] PPS from Samsung GCRU
Message-ID: <C1483046D5364BD59D25D2E12D545016@twotoe.com>


Just wanted to bounce some thoughts off the group: 

I have a Samsung GCRU and I need to permanently tap the 1PPS signal.

Can the PPS output of the GPS RX be used without interfering with the accuracy of the unit?

Is there is another PPS output, preferably buffered and in phase from the GCRU?

If I am forced to use the GPS RX PPS output, at this stage I would use either a RS232 line driver, or a 74HC04 to buffer the output.

What sort of problems should I look out for?


Happy holidays,
Mark



From bruce.griffiths at xtra.co.nz  Fri Dec 26 10:28:51 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Fri, 26 Dec 2008 23:28:51 +1300
Subject: [time-nuts] Happy Holidays
In-Reply-To: <4954A22D.10802@xtra.co.nz>
References: <23166.206.174.20.67.1230278691.squirrel@mymail.acsalaska.net>
	<4954A22D.10802@xtra.co.nz>
Message-ID: <4954B1E3.3040004@xtra.co.nz>

Bruce Griffiths wrote:
> Richard H McCorkle wrote:
>   
>> Ho Ho Ho
>>
>> Merry Christmas from the far north to all the
>> Time-Nuts. As a gift for the holidays I have
>> created a free version of the PICTIC for you
>> and Didier has kindly posted the files at:
>>
>> http://www.ko4bb.com/dokuwiki/doku.php?id=precision_timing:pictic
>>
>>
>> And to all a good night,
>>
>> Richard
>>
>>
>>   
>>     
> Richard
>
> Your analog interpolator needs a little work.
> The switching speed of the 2N3906's is so slow because the 2N3906's that
> switch the current to ground or into the 470pF cap are saturated.
> They will switch much faster if used as current mode switches.
> In fact you can just replace the 2N3906 whose collector is connected to
> the 470pF cap with a fast switching diode and the current source will be
> switched much faster.
> The 2N7000's have a relatively high non linear output capacitance
> replacing them with something like 1/6X 74HC05 would be better.
> The 470pF silver mica caps will have relatively large dielectric absorption.
> NP0/C0G caps would be a better choice, particularly if higher input
> pulse rates were to be used.
>
> Have you actually measured the linearity of the interpolator?
>
>
> Bruce
>
>
>   
The quickest fix is to drop the differential drive to the 2N3906's and
bias the base of the 2N3906 whose collector is connected to the 470pF
cap at +2.5V.
This will ensure the 2N3906's switch much faster.
The maximum voltage on the 470pF cap should be about 1V to avoid
saturating the transistor whose collector is connected to it.
The opamp gain network should then be adjusted to produce the required
output swing.
If the maximum charging time of the capacitor is 400ns then the charging
current should be about 4.7E-10/4E-7 or about 1.2mA.
The 2N3906's will switch a bit faster if the current is increased to 5
or 10mA in which case the 470pF cap should be replaced by a ~2nF cap
(with 5mA charging current).
Use an NP0/C0G for low dielectric absorption.

Bruce


From jltran at worldnet.att.net  Fri Dec 26 13:35:56 2008
From: jltran at worldnet.att.net (J. L. Trantham)
Date: Fri, 26 Dec 2008 07:35:56 -0600
Subject: [time-nuts] Happy Holidays
In-Reply-To: <23166.206.174.20.67.1230278691.squirrel@mymail.acsalaska.net>
Message-ID: <6E1D662C04714FEEB9A35778D0D85631@S0028384766>

Richard,

Thank you for the gift.  It looks like an interesting project and worthy of
a time-nut novice like myself.  I will add it to my list of 'to-do's'.

And thank you to all on the list for their very interesting discussions and
renewing my interests in electronics in the past year.

Merry Christmas and Happy New Year.

Joe

-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of Richard H McCorkle
Sent: Friday, December 26, 2008 2:05 AM
To: time-nuts at febo.com
Subject: [time-nuts] Happy Holidays

Ho Ho Ho

Merry Christmas from the far north to all the
Time-Nuts. As a gift for the holidays I have
created a free version of the PICTIC for you
and Didier has kindly posted the files at:

http://www.ko4bb.com/dokuwiki/doku.php?id=precision_timing:pictic


And to all a good night,

Richard


_______________________________________________
time-nuts mailing list -- time-nuts at febo.com
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.



From tob at starhouse.org  Fri Dec 26 16:18:40 2008
From: tob at starhouse.org (Tom Bales)
Date: Fri, 26 Dec 2008 11:18:40 -0500
Subject: [time-nuts] Real-time Timestamp with Richard's PICTIC?
In-Reply-To: <1553074.1230295026789.JavaMail.root@m06>
References: <1553074.1230295026789.JavaMail.root@m06>
Message-ID: <E1LGFOo-0007od-BQ@elasmtp-mealy.atl.sa.earthlink.net>

At 07:00 AM 12/26/2008, time-nuts-request at febo.com wrote:
>Send time-nuts mailing list submissions to
>         time-nuts at febo.com
>
>To subscribe or unsubscribe via the World Wide Web, visit
>         https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>or, via email, send a message with subject or body 'help' to
>         time-nuts-request at febo.com
>
>You can reach the person managing the list at
>         time-nuts-owner at febo.com
>
>When replying, please edit your Subject line so it is more specific
>than "Re: Contents of time-nuts digest..."
>
>
>Today's Topics:
>
>    1. Re: Happy Holidays (Bruce Griffiths)
>    2. PPS from Samsung GCRU (Mark Stephens)
>    3. Re: Happy Holidays (Bruce Griffiths)
>
>
>----------------------------------------------------------------------
>
>Message: 1
>Date: Fri, 26 Dec 2008 22:21:49 +1300
>From: Bruce Griffiths <bruce.griffiths at xtra.co.nz>
>Subject: Re: [time-nuts] Happy Holidays
>To: mccorkle at ptialaska.net,     Discussion of precise time and frequency
>         measurement <time-nuts at febo.com>
>Message-ID: <4954A22D.10802 at xtra.co.nz>
>Content-Type: text/plain; charset=ISO-8859-1
>
Ho, Ho, Ho!  Thanks to Richard from the Cold North for such a nice 
Christmas present!

I've been working on a crackpot scheme to measure the time of arrival 
of cosmic-ray events.  It's a "crackpot scheme" because I want to 
record the times in a (no-doubt futile) attempt to see if any of the 
events are correlated in time--sent from a common source in a uniform 
pulse train, perhaps.

So for, I've assembled some simple detectors, an HP53131 interval 
counter, a Lucent RFTGm GPS/XO/Rb set for frequency reference, and a 
bunch of cables with the result that I can record the time interval 
between events to 0.1 nanoseconds, but not real arrival time.  I 
figured that I would just add up all the interval times to get a sort 
of real time, but after lots and lots of events, the cumulative error 
probably defeats the purpose (and missing events hurt your cause a 
lot).  So, I've been looking for a very precise, high-resolution 
real-time event timestamper.

This all started when I was listening to Tom van Baak talk about ADEV 
of pendulum clocks at the BHI anniversary symposium last summer, and 
how you could pick up the signature of astronomical events, such as 
lunar tides.  At the time I was reading a report about some 
physicists at Brookhaven discovering strange semi-annual rate 
variations in the radioactive decay of nuclei, and I was toting 
around a book about cosmic rays.  Funny how the brain works.  Oh, 
yes--and the LHC was starting up.  So, imagine some spaceman a long 
time ago in a galaxy far, far away firing up his proton accelerator, 
sending off pulses of protons into space, and a few of them hitting 
us here on earth every now and then.  It doesn't seem that anyone has 
ever looked for such a signal, so why not look for one?  (There are 
lots of complications, such as the motion of the earth, to deal 
with--but you get the idea.)

I haven't found a simple way to record a file of real-time time 
stamps, at least without lashing together a bunch of clocks, interval 
counters, GPIB controller, and so forth, but Richard's gift seems to 
have everything needed to do the job, except for a GPS time receiver 
to form the low-resolution part of the timestamp, and a software 
means of concatenating the data for date, hour, minute, and second to 
the high-resolution data from the PICTIC.  Can anyone offer suggestions?

Tom Bales
Coral Gables, FL



>Richard H McCorkle wrote:
> > Ho Ho Ho
> >
> > Merry Christmas from the far north to all the
> > Time-Nuts. As a gift for the holidays I have
> > created a free version of the PICTIC for you
> > and Didier has kindly posted the files at:
> >
> > http://www.ko4bb.com/dokuwiki/doku.php?id=precision_timing:pictic
> >
> >
> > And to all a good night,
> >
> > Richard
> >
> >
> >
>Richard
>
>Your analog interpolator needs a little work.
>The switching speed of the 2N3906's is so slow because the 2N3906's that
>switch the current to ground or into the 470pF cap are saturated.
>They will switch much faster if used as current mode switches.
>In fact you can just replace the 2N3906 whose collector is connected to
>the 470pF cap with a fast switching diode and the current source will be
>switched much faster.
>The 2N7000's have a relatively high non linear output capacitance
>replacing them with something like 1/6X 74HC05 would be better.
>The 470pF silver mica caps will have relatively large dielectric absorption.
>NP0/C0G caps would be a better choice, particularly if higher input
>pulse rates were to be used.
>
>Have you actually measured the linearity of the interpolator?
>
>
>Bruce
>
>
>
>
>------------------------------
>
>Message: 2
>Date: Fri, 26 Dec 2008 21:04:24 +1100
>From: "Mark Stephens" <marks at twotoe.com>
>Subject: [time-nuts] PPS from Samsung GCRU
>To: <time-nuts at febo.com>
>Message-ID: <C1483046D5364BD59D25D2E12D545016 at twotoe.com>
>Content-Type: text/plain;       charset="iso-8859-1"
>
>
>Just wanted to bounce some thoughts off the group:
>
>I have a Samsung GCRU and I need to permanently tap the 1PPS signal.
>
>Can the PPS output of the GPS RX be used without interfering with 
>the accuracy of the unit?
>
>Is there is another PPS output, preferably buffered and in phase 
>from the GCRU?
>
>If I am forced to use the GPS RX PPS output, at this stage I would 
>use either a RS232 line driver, or a 74HC04 to buffer the output.
>
>What sort of problems should I look out for?
>
>
>Happy holidays,
>Mark
>
>
>
>
>------------------------------
>
>Message: 3
>Date: Fri, 26 Dec 2008 23:28:51 +1300
>From: Bruce Griffiths <bruce.griffiths at xtra.co.nz>
>Subject: Re: [time-nuts] Happy Holidays
>To: Discussion of precise time and frequency measurement
>         <time-nuts at febo.com>
>Message-ID: <4954B1E3.3040004 at xtra.co.nz>
>Content-Type: text/plain; charset=ISO-8859-1
>
>Bruce Griffiths wrote:
> > Richard H McCorkle wrote:
> >
> >> Ho Ho Ho
> >>
> >> Merry Christmas from the far north to all the
> >> Time-Nuts. As a gift for the holidays I have
> >> created a free version of the PICTIC for you
> >> and Didier has kindly posted the files at:
> >>
> >> http://www.ko4bb.com/dokuwiki/doku.php?id=precision_timing:pictic
> >>
> >>
> >> And to all a good night,
> >>
> >> Richard
> >>
> >>
> >>
> >>
> > Richard
> >
> > Your analog interpolator needs a little work.
> > The switching speed of the 2N3906's is so slow because the 2N3906's that
> > switch the current to ground or into the 470pF cap are saturated.
> > They will switch much faster if used as current mode switches.
> > In fact you can just replace the 2N3906 whose collector is connected to
> > the 470pF cap with a fast switching diode and the current source will be
> > switched much faster.
> > The 2N7000's have a relatively high non linear output capacitance
> > replacing them with something like 1/6X 74HC05 would be better.
> > The 470pF silver mica caps will have relatively large dielectric 
> absorption.
> > NP0/C0G caps would be a better choice, particularly if higher input
> > pulse rates were to be used.
> >
> > Have you actually measured the linearity of the interpolator?
> >
> >
> > Bruce
> >
> >
> >
>The quickest fix is to drop the differential drive to the 2N3906's and
>bias the base of the 2N3906 whose collector is connected to the 470pF
>cap at +2.5V.
>This will ensure the 2N3906's switch much faster.
>The maximum voltage on the 470pF cap should be about 1V to avoid
>saturating the transistor whose collector is connected to it.
>The opamp gain network should then be adjusted to produce the required
>output swing.
>If the maximum charging time of the capacitor is 400ns then the charging
>current should be about 4.7E-10/4E-7 or about 1.2mA.
>The 2N3906's will switch a bit faster if the current is increased to 5
>or 10mA in which case the 470pF cap should be replaced by a ~2nF cap
>(with 5mA charging current).
>Use an NP0/C0G for low dielectric absorption.
>
>Bruce
>
>
>
>------------------------------
>
>_______________________________________________
>time-nuts mailing list
>time-nuts at febo.com
>https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>
>End of time-nuts Digest, Vol 53, Issue 101
>******************************************



From bruce.griffiths at xtra.co.nz  Fri Dec 26 19:44:38 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Sat, 27 Dec 2008 08:44:38 +1300
Subject: [time-nuts] Real-time Timestamp with Richard's PICTIC?
In-Reply-To: <E1LGFOo-0007od-BQ@elasmtp-mealy.atl.sa.earthlink.net>
References: <1553074.1230295026789.JavaMail.root@m06>
	<E1LGFOo-0007od-BQ@elasmtp-mealy.atl.sa.earthlink.net>
Message-ID: <49553426.9050402@xtra.co.nz>

Tom

The design needs some rework to achieve useful performance.
Apart from the interpolator problems, you will need to use a different
microprocessor (suitable PIC and AVR micros are available).
A microprocessor which allows the value of an internal counter to be
sampled on the transition of an external signal is required.
Since there is no way to share the counter without introducing
significant complications at least 2 such internal counters are required.
An external synchroniser is required despite the one built into the chip
as the external interpolator has to measure the delay of the synchroniser.
The GPS PPS signal should be used to sample one counter whilst the event
of interest samples the other.
TThe count resolution is extended in software and combined with sawtooth
correction data and the time data from the GPS a timestamp noise level
of a few nanosec should be achievable.
However the events to be time stamped will need to be be several
microsec apart.
If you need lower deadtime you will have to use something like one of
the ACAM TDCs.

Bruce

Tom Bales wrote:
> At 07:00 AM 12/26/2008, time-nuts-request at febo.com wrote:
>   
>> Send time-nuts mailing list submissions to
>>         time-nuts at febo.com
>>
>> To subscribe or unsubscribe via the World Wide Web, visit
>>         https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>> or, via email, send a message with subject or body 'help' to
>>         time-nuts-request at febo.com
>>
>> You can reach the person managing the list at
>>         time-nuts-owner at febo.com
>>
>> When replying, please edit your Subject line so it is more specific
>> than "Re: Contents of time-nuts digest..."
>>
>>
>> Today's Topics:
>>
>>    1. Re: Happy Holidays (Bruce Griffiths)
>>    2. PPS from Samsung GCRU (Mark Stephens)
>>    3. Re: Happy Holidays (Bruce Griffiths)
>>
>>
>> ----------------------------------------------------------------------
>>
>> Message: 1
>> Date: Fri, 26 Dec 2008 22:21:49 +1300
>> From: Bruce Griffiths <bruce.griffiths at xtra.co.nz>
>> Subject: Re: [time-nuts] Happy Holidays
>> To: mccorkle at ptialaska.net,     Discussion of precise time and frequency
>>         measurement <time-nuts at febo.com>
>> Message-ID: <4954A22D.10802 at xtra.co.nz>
>> Content-Type: text/plain; charset=ISO-8859-1
>>
>>     
> Ho, Ho, Ho!  Thanks to Richard from the Cold North for such a nice 
> Christmas present!
>
> I've been working on a crackpot scheme to measure the time of arrival 
> of cosmic-ray events.  It's a "crackpot scheme" because I want to 
> record the times in a (no-doubt futile) attempt to see if any of the 
> events are correlated in time--sent from a common source in a uniform 
> pulse train, perhaps.
>
> So for, I've assembled some simple detectors, an HP53131 interval 
> counter, a Lucent RFTGm GPS/XO/Rb set for frequency reference, and a 
> bunch of cables with the result that I can record the time interval 
> between events to 0.1 nanoseconds, but not real arrival time.  I 
> figured that I would just add up all the interval times to get a sort 
> of real time, but after lots and lots of events, the cumulative error 
> probably defeats the purpose (and missing events hurt your cause a 
> lot).  So, I've been looking for a very precise, high-resolution 
> real-time event timestamper.
>
> This all started when I was listening to Tom van Baak talk about ADEV 
> of pendulum clocks at the BHI anniversary symposium last summer, and 
> how you could pick up the signature of astronomical events, such as 
> lunar tides.  At the time I was reading a report about some 
> physicists at Brookhaven discovering strange semi-annual rate 
> variations in the radioactive decay of nuclei, and I was toting 
> around a book about cosmic rays.  Funny how the brain works.  Oh, 
> yes--and the LHC was starting up.  So, imagine some spaceman a long 
> time ago in a galaxy far, far away firing up his proton accelerator, 
> sending off pulses of protons into space, and a few of them hitting 
> us here on earth every now and then.  It doesn't seem that anyone has 
> ever looked for such a signal, so why not look for one?  (There are 
> lots of complications, such as the motion of the earth, to deal 
> with--but you get the idea.)
>
> I haven't found a simple way to record a file of real-time time 
> stamps, at least without lashing together a bunch of clocks, interval 
> counters, GPIB controller, and so forth, but Richard's gift seems to 
> have everything needed to do the job, except for a GPS time receiver 
> to form the low-resolution part of the timestamp, and a software 
> means of concatenating the data for date, hour, minute, and second to 
> the high-resolution data from the PICTIC.  Can anyone offer suggestions?
>
> Tom Bales
> Coral Gables, FL
>
>
>
>   
>> Richard H McCorkle wrote:
>>     
>>> Ho Ho Ho
>>>
>>> Merry Christmas from the far north to all the
>>> Time-Nuts. As a gift for the holidays I have
>>> created a free version of the PICTIC for you
>>> and Didier has kindly posted the files at:
>>>
>>> http://www.ko4bb.com/dokuwiki/doku.php?id=precision_timing:pictic
>>>
>>>
>>> And to all a good night,
>>>
>>> Richard
>>>
>>>
>>>
>>>       
>> Richard
>>
>> Your analog interpolator needs a little work.
>> The switching speed of the 2N3906's is so slow because the 2N3906's that
>> switch the current to ground or into the 470pF cap are saturated.
>> They will switch much faster if used as current mode switches.
>> In fact you can just replace the 2N3906 whose collector is connected to
>> the 470pF cap with a fast switching diode and the current source will be
>> switched much faster.
>> The 2N7000's have a relatively high non linear output capacitance
>> replacing them with something like 1/6X 74HC05 would be better.
>> The 470pF silver mica caps will have relatively large dielectric absorption.
>> NP0/C0G caps would be a better choice, particularly if higher input
>> pulse rates were to be used.
>>
>> Have you actually measured the linearity of the interpolator?
>>
>>
>> Bruce
>>
>>
>>
>>
>> ------------------------------
>>
>> Message: 2
>> Date: Fri, 26 Dec 2008 21:04:24 +1100
>> From: "Mark Stephens" <marks at twotoe.com>
>> Subject: [time-nuts] PPS from Samsung GCRU
>> To: <time-nuts at febo.com>
>> Message-ID: <C1483046D5364BD59D25D2E12D545016 at twotoe.com>
>> Content-Type: text/plain;       charset="iso-8859-1"
>>
>>
>> Just wanted to bounce some thoughts off the group:
>>
>> I have a Samsung GCRU and I need to permanently tap the 1PPS signal.
>>
>> Can the PPS output of the GPS RX be used without interfering with 
>> the accuracy of the unit?
>>
>> Is there is another PPS output, preferably buffered and in phase 
>>     
> >from the GCRU?
>   
>> If I am forced to use the GPS RX PPS output, at this stage I would 
>> use either a RS232 line driver, or a 74HC04 to buffer the output.
>>
>> What sort of problems should I look out for?
>>
>>
>> Happy holidays,
>> Mark
>>
>>
>>
>>
>> ------------------------------
>>
>> Message: 3
>> Date: Fri, 26 Dec 2008 23:28:51 +1300
>> From: Bruce Griffiths <bruce.griffiths at xtra.co.nz>
>> Subject: Re: [time-nuts] Happy Holidays
>> To: Discussion of precise time and frequency measurement
>>         <time-nuts at febo.com>
>> Message-ID: <4954B1E3.3040004 at xtra.co.nz>
>> Content-Type: text/plain; charset=ISO-8859-1
>>
>> Bruce Griffiths wrote:
>>     
>>> Richard H McCorkle wrote:
>>>
>>>       
>>>> Ho Ho Ho
>>>>
>>>> Merry Christmas from the far north to all the
>>>> Time-Nuts. As a gift for the holidays I have
>>>> created a free version of the PICTIC for you
>>>> and Didier has kindly posted the files at:
>>>>
>>>> http://www.ko4bb.com/dokuwiki/doku.php?id=precision_timing:pictic
>>>>
>>>>
>>>> And to all a good night,
>>>>
>>>> Richard
>>>>
>>>>
>>>>
>>>>
>>>>         
>>> Richard
>>>
>>> Your analog interpolator needs a little work.
>>> The switching speed of the 2N3906's is so slow because the 2N3906's that
>>> switch the current to ground or into the 470pF cap are saturated.
>>> They will switch much faster if used as current mode switches.
>>> In fact you can just replace the 2N3906 whose collector is connected to
>>> the 470pF cap with a fast switching diode and the current source will be
>>> switched much faster.
>>> The 2N7000's have a relatively high non linear output capacitance
>>> replacing them with something like 1/6X 74HC05 would be better.
>>> The 470pF silver mica caps will have relatively large dielectric 
>>>       
>> absorption.
>>     
>>> NP0/C0G caps would be a better choice, particularly if higher input
>>> pulse rates were to be used.
>>>
>>> Have you actually measured the linearity of the interpolator?
>>>
>>>
>>> Bruce
>>>
>>>
>>>
>>>       
>> The quickest fix is to drop the differential drive to the 2N3906's and
>> bias the base of the 2N3906 whose collector is connected to the 470pF
>> cap at +2.5V.
>> This will ensure the 2N3906's switch much faster.
>> The maximum voltage on the 470pF cap should be about 1V to avoid
>> saturating the transistor whose collector is connected to it.
>> The opamp gain network should then be adjusted to produce the required
>> output swing.
>> If the maximum charging time of the capacitor is 400ns then the charging
>> current should be about 4.7E-10/4E-7 or about 1.2mA.
>> The 2N3906's will switch a bit faster if the current is increased to 5
>> or 10mA in which case the 470pF cap should be replaced by a ~2nF cap
>> (with 5mA charging current).
>> Use an NP0/C0G for low dielectric absorption.
>>
>> Bruce
>>
>>
>>
>> ------------------------------
>>
>> _______________________________________________
>> time-nuts mailing list
>> time-nuts at febo.com
>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>>
>> End of time-nuts Digest, Vol 53, Issue 101
>> ******************************************
>>     
>
>
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>
>   



From gbusg at comcast.net  Fri Dec 26 19:50:19 2008
From: gbusg at comcast.net (Greg Burnett)
Date: Fri, 26 Dec 2008 12:50:19 -0700
Subject: [time-nuts]  WWVB Outages?
References: <6E1D662C04714FEEB9A35778D0D85631@S0028384766>
Message-ID: <003101c96793$2f0b6860$6501a8c0@gb02>

Have any of you noticed intermittent WWVB outages lately?

I've been having that problem, every once in a while, the past month or 
more. For example, here in Colorado Springs, the 60 kHz signal disappeared 
sometime this morning before 11:42AM MST, and returned at 12:28PM MST. When 
this happens it kills my routine plot of my GPS-disciplined house standard 
against WWVB (that I use for in-house cross-checking / confidence purposes).

I'm using a Kinemetrics Model 60TF WWVB Frequency Comparator / Receiver, 
that requires a continuous WWVB signal. (This is unlike the consumer "Atomic 
Clocks" that the public use; those kinds of WWVB-locked clocks do *not* 
require a continuous on-air signal, but rather "flywheel" in between 
scheduled locks a few times per day, as I understand it?)

Cheers,
Greg





From dmendesf at bol.com.br  Fri Dec 26 21:03:58 2008
From: dmendesf at bol.com.br (Daniel Mendes)
Date: Fri, 26 Dec 2008 18:03:58 -0300
Subject: [time-nuts] Request for MC598X4 and Datum LPRO datasheet
Message-ID: <495546BE.4040209@bol.com.br>

Hy, my name is Daniel, I lurk at this list trying to learn something
with the masters of time measurements  :)  I?ve bought two MC598X4 from
Ebay. Does someone have a datasheet for them? Or at least the pinouts...
I?ve bought also an  Datum LPRO 102500-001 but the datasheet is no more
available at  http://www.symmetricom.com/media/pdf/manuals/man-lpro.pdf  .
Does someone have a copy?
 
 Thanks!
 
 Daniel



From gbusg at comcast.net  Fri Dec 26 20:02:29 2008
From: gbusg at comcast.net (Greg Burnett)
Date: Fri, 26 Dec 2008 13:02:29 -0700
Subject: [time-nuts] WWVB Outages?
References: <6E1D662C04714FEEB9A35778D0D85631@S0028384766>
	<003101c96793$2f0b6860$6501a8c0@gb02>
Message-ID: <003501c96794$e236e940$6501a8c0@gb02>

I forgot to mention: When on-the-air, WWVB produces a nice, clean signal, 
at -51 dBm (at the higher of it's two shifted amplitudes) as output from my 
Kinemetrics active antenna (and measured by both a HP 3586C in 20Hz BW and a 
HP 3585A in 30Hz BW), here in Colorado Springs. When the WWVB signal 
disappears, those same measurements drop to a noise floor in the range -80 
to -129 dBm, depending on residual 60kHz noise/interference in my 
neighborhood.

Greg


----- Original Message ----- 
From: "Greg Burnett" <gbusg at comcast.net>
To: "Discussion of precise time and frequency measurement" 
<time-nuts at febo.com>
Sent: Friday, December 26, 2008 12:50 PM
Subject: [time-nuts] WWVB Outages?


Have any of you noticed intermittent WWVB outages lately?

I've been having that problem, every once in a while, the past month or
more. For example, here in Colorado Springs, the 60 kHz signal disappeared
sometime this morning before 11:42AM MST, and returned at 12:28PM MST. When
this happens it kills my routine plot of my GPS-disciplined house standard
against WWVB (that I use for in-house cross-checking / confidence purposes).

I'm using a Kinemetrics Model 60TF WWVB Frequency Comparator / Receiver,
that requires a continuous WWVB signal. (This is unlike the consumer "Atomic
Clocks" that the public use; those kinds of WWVB-locked clocks do *not*
require a continuous on-air signal, but rather "flywheel" in between
scheduled locks a few times per day, as I understand it?)

Cheers,
Greg




_______________________________________________
time-nuts mailing list -- time-nuts at febo.com
To unsubscribe, go to 
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there. 



From jra at febo.com  Fri Dec 26 20:02:27 2008
From: jra at febo.com (John Ackermann N8UR)
Date: Fri, 26 Dec 2008 15:02:27 -0500
Subject: [time-nuts] WWVB Outages?
In-Reply-To: <003101c96793$2f0b6860$6501a8c0@gb02>
References: <6E1D662C04714FEEB9A35778D0D85631@S0028384766>
	<003101c96793$2f0b6860$6501a8c0@gb02>
Message-ID: <49553853.9010509@febo.com>

I don't see any alarm LEDs on my Spectracom WWVB receivers (one a
WWVB-DO, the other a clock), but I'm not sure that their "unlock" LEDs
latch, or that the "error" LEDs trip on loss of lock.

John
----

Greg Burnett said the following on 12/26/2008 02:50 PM:
> Have any of you noticed intermittent WWVB outages lately?
> 
> I've been having that problem, every once in a while, the past month or 
> more. For example, here in Colorado Springs, the 60 kHz signal disappeared 
> sometime this morning before 11:42AM MST, and returned at 12:28PM MST. When 
> this happens it kills my routine plot of my GPS-disciplined house standard 
> against WWVB (that I use for in-house cross-checking / confidence purposes).
> 
> I'm using a Kinemetrics Model 60TF WWVB Frequency Comparator / Receiver, 
> that requires a continuous WWVB signal. (This is unlike the consumer "Atomic 
> Clocks" that the public use; those kinds of WWVB-locked clocks do *not* 
> require a continuous on-air signal, but rather "flywheel" in between 
> scheduled locks a few times per day, as I understand it?)
> 
> Cheers,
> Greg
> 
> 
> 
> 
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.


From tvb at LeapSecond.com  Fri Dec 26 20:06:15 2008
From: tvb at LeapSecond.com (Tom Van Baak)
Date: Fri, 26 Dec 2008 12:06:15 -0800
Subject: [time-nuts] WWVB Outages?
References: <6E1D662C04714FEEB9A35778D0D85631@S0028384766>
	<003101c96793$2f0b6860$6501a8c0@gb02>
Message-ID: <1E2BB68EAC6B47C083E45A30A37E2997@pc52>

Greg,

It happens now and then; no big deal. NIST is very good about
logging these events for us. For recent (and past 7 years) see:

http://tf.nist.gov/stations/wwvboutages.htm

/tvb

> Have any of you noticed intermittent WWVB outages lately?
> 
> I've been having that problem, every once in a while, the past month or 
> more. For example, here in Colorado Springs, the 60 kHz signal disappeared 
> sometime this morning before 11:42AM MST, and returned at 12:28PM MST. When 
> this happens it kills my routine plot of my GPS-disciplined house standard 
> against WWVB (that I use for in-house cross-checking / confidence purposes).
> 
> I'm using a Kinemetrics Model 60TF WWVB Frequency Comparator / Receiver, 
> that requires a continuous WWVB signal. (This is unlike the consumer "Atomic 
> Clocks" that the public use; those kinds of WWVB-locked clocks do *not* 
> require a continuous on-air signal, but rather "flywheel" in between 
> scheduled locks a few times per day, as I understand it?)
> 
> Cheers,
> Greg
> 



From gbusg at comcast.net  Fri Dec 26 20:08:18 2008
From: gbusg at comcast.net (Greg Burnett)
Date: Fri, 26 Dec 2008 13:08:18 -0700
Subject: [time-nuts] WWVB Outages?
References: <6E1D662C04714FEEB9A35778D0D85631@S0028384766><003101c96793$2f0b6860$6501a8c0@gb02>
	<49553853.9010509@febo.com>
Message-ID: <003d01c96795$b21f6600$6501a8c0@gb02>

John,

If it's not too much trouble, could you temporarily disconnect antenna, 
confirm the alarm, then reconnect antenna to see if the alarm remains 
latched or goes away.

In my case, the Kinemetrics 60TF's "Unlock" alarm is *not* latching. 
Therefore you have to be there, to catch the problem "in the act". ...Or 
else run continuous plots.

Greg


----- Original Message ----- 
From: "John Ackermann N8UR" <jra at febo.com>
To: "Discussion of precise time and frequency measurement" 
<time-nuts at febo.com>
Sent: Friday, December 26, 2008 1:02 PM
Subject: Re: [time-nuts] WWVB Outages?


I don't see any alarm LEDs on my Spectracom WWVB receivers (one a
WWVB-DO, the other a clock), but I'm not sure that their "unlock" LEDs
latch, or that the "error" LEDs trip on loss of lock.

John
----

Greg Burnett said the following on 12/26/2008 02:50 PM:
> Have any of you noticed intermittent WWVB outages lately?
>
> I've been having that problem, every once in a while, the past month or
> more. For example, here in Colorado Springs, the 60 kHz signal disappeared
> sometime this morning before 11:42AM MST, and returned at 12:28PM MST. 
> When
> this happens it kills my routine plot of my GPS-disciplined house standard
> against WWVB (that I use for in-house cross-checking / confidence 
> purposes).
>
> I'm using a Kinemetrics Model 60TF WWVB Frequency Comparator / Receiver,
> that requires a continuous WWVB signal. (This is unlike the consumer 
> "Atomic
> Clocks" that the public use; those kinds of WWVB-locked clocks do *not*
> require a continuous on-air signal, but rather "flywheel" in between
> scheduled locks a few times per day, as I understand it?)
>
> Cheers,
> Greg
>
>
>
>
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to 
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.

_______________________________________________
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To unsubscribe, go to 
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
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From gbusg at comcast.net  Fri Dec 26 20:18:41 2008
From: gbusg at comcast.net (Greg Burnett)
Date: Fri, 26 Dec 2008 13:18:41 -0700
Subject: [time-nuts] WWVB Outages?
References: <6E1D662C04714FEEB9A35778D0D85631@S0028384766><003101c96793$2f0b6860$6501a8c0@gb02>
	<1E2BB68EAC6B47C083E45A30A37E2997@pc52>
Message-ID: <004101c96797$2594c840$6501a8c0@gb02>

Thanks for the link, Tom. That's the same link that Michael Lombardi gave me 
a number of years ago. The issues I have with that NIST data is that, 1), 
it's not updated in realtime, e.g., I can't see today's events; and, 2), it 
only records outages lasting 5 minutes or longer. In the past few years, 
I've experienced numerous other outages (lasting less than 5 minutes), that 
weren't reported at NIST's "Broadcast Outages" site.

One problem with lack of "realtime" data (including events lasting less than 
5 minutes) from NIST is that it tends to cause customers to waste time, 
troubleshooting their equipment and processes, in case the problem might be 
at their side instead of NIST's.

Today's outage lasted more than 5 minutes. So it will be interesting to see 
if it's eventually included in NIST's "Broadcast Outages" list.

Greg


----- Original Message ----- 
From: "Tom Van Baak" <tvb at LeapSecond.com>
To: "Discussion of precise time and frequency measurement" 
<time-nuts at febo.com>
Sent: Friday, December 26, 2008 1:06 PM
Subject: Re: [time-nuts] WWVB Outages?


Greg,

It happens now and then; no big deal. NIST is very good about
logging these events for us. For recent (and past 7 years) see:

http://tf.nist.gov/stations/wwvboutages.htm

/tvb

> Have any of you noticed intermittent WWVB outages lately?
>
> I've been having that problem, every once in a while, the past month or
> more. For example, here in Colorado Springs, the 60 kHz signal disappeared
> sometime this morning before 11:42AM MST, and returned at 12:28PM MST. 
> When
> this happens it kills my routine plot of my GPS-disciplined house standard
> against WWVB (that I use for in-house cross-checking / confidence 
> purposes).
>
> I'm using a Kinemetrics Model 60TF WWVB Frequency Comparator / Receiver,
> that requires a continuous WWVB signal. (This is unlike the consumer 
> "Atomic
> Clocks" that the public use; those kinds of WWVB-locked clocks do *not*
> require a continuous on-air signal, but rather "flywheel" in between
> scheduled locks a few times per day, as I understand it?)
>
> Cheers,
> Greg
>


_______________________________________________
time-nuts mailing list -- time-nuts at febo.com
To unsubscribe, go to 
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there. 



From time-nuts at adobe-labs.com  Fri Dec 26 20:19:21 2008
From: time-nuts at adobe-labs.com (Brent Gordon)
Date: Fri, 26 Dec 2008 13:19:21 -0700
Subject: [time-nuts] WWVB Outages?
In-Reply-To: <1E2BB68EAC6B47C083E45A30A37E2997@pc52>
References: <6E1D662C04714FEEB9A35778D0D85631@S0028384766>	<003101c96793$2f0b6860$6501a8c0@gb02>
	<1E2BB68EAC6B47C083E45A30A37E2997@pc52>
Message-ID: <49553C49.8030903@adobe-labs.com>

Your outage matches what NIST shows:
http://tf.nist.gov/tf-cgi/wwvbgraph_e.cgi?5482602

Brent

Tom Van Baak wrote:
> Greg,
>
> It happens now and then; no big deal. NIST is very good about
> logging these events for us. For recent (and past 7 years) see:
>
> http://tf.nist.gov/stations/wwvboutages.htm
>
> /tvb
>
>   
>> Have any of you noticed intermittent WWVB outages lately?
>>
>> I've been having that problem, every once in a while, the past month or 
>> more. For example, here in Colorado Springs, the 60 kHz signal disappeared 
>> sometime this morning before 11:42AM MST, and returned at 12:28PM MST. When 
>> this happens it kills my routine plot of my GPS-disciplined house standard 
>> against WWVB (that I use for in-house cross-checking / confidence purposes).
>>
>> I'm using a Kinemetrics Model 60TF WWVB Frequency Comparator / Receiver, 
>> that requires a continuous WWVB signal. (This is unlike the consumer "Atomic 
>> Clocks" that the public use; those kinds of WWVB-locked clocks do *not* 
>> require a continuous on-air signal, but rather "flywheel" in between 
>> scheduled locks a few times per day, as I understand it?)
>>
>> Cheers,
>> Greg
>>
>>     


From msa at latt.net  Fri Dec 26 20:25:42 2008
From: msa at latt.net (Majdi S. Abbas)
Date: Fri, 26 Dec 2008 20:25:42 +0000
Subject: [time-nuts] WWVB Outages?
In-Reply-To: <003d01c96795$b21f6600$6501a8c0@gb02>
References: <49553853.9010509@febo.com> <003d01c96795$b21f6600$6501a8c0@gb02>
Message-ID: <20081226202542.GA43497@mx1.latt.net>

On Fri, Dec 26, 2008 at 01:08:18PM -0700, Greg Burnett wrote:
> In my case, the Kinemetrics 60TF's "Unlock" alarm is *not* latching. 
> Therefore you have to be there, to catch the problem "in the act". ...Or 
> else run continuous plots.

	You could modify the receiver and use an SCR or something similar
as a latching alarm trigger.  Leave the current light in place, but add
an additional one that latches, and a reset button to clear the statE.

	Then there's no need for a chart recorder to at least tell if an
alarm has occured since the last time you reset it.

	--msa


From gbusg at comcast.net  Fri Dec 26 20:29:42 2008
From: gbusg at comcast.net (Greg Burnett)
Date: Fri, 26 Dec 2008 13:29:42 -0700
Subject: [time-nuts] WWVB Outages?
References: <6E1D662C04714FEEB9A35778D0D85631@S0028384766>	<003101c96793$2f0b6860$6501a8c0@gb02><1E2BB68EAC6B47C083E45A30A37E2997@pc52>
	<49553C49.8030903@adobe-labs.com>
Message-ID: <005101c96798$af8c7ec0$6501a8c0@gb02>

Aha!

Thanks Brent for that link! I wasn't aware that NIST had added that feature.

Thanks again!
Greg


----- Original Message ----- 
From: "Brent Gordon" <time-nuts at adobe-labs.com>
To: "Discussion of precise time and frequency measurement" 
<time-nuts at febo.com>
Sent: Friday, December 26, 2008 1:19 PM
Subject: Re: [time-nuts] WWVB Outages?


Your outage matches what NIST shows:
http://tf.nist.gov/tf-cgi/wwvbgraph_e.cgi?5482602

Brent

Tom Van Baak wrote:
> Greg,
>
> It happens now and then; no big deal. NIST is very good about
> logging these events for us. For recent (and past 7 years) see:
>
> http://tf.nist.gov/stations/wwvboutages.htm
>
> /tvb
>
>
>> Have any of you noticed intermittent WWVB outages lately?
>>
>> I've been having that problem, every once in a while, the past month or
>> more. For example, here in Colorado Springs, the 60 kHz signal 
>> disappeared
>> sometime this morning before 11:42AM MST, and returned at 12:28PM MST. 
>> When
>> this happens it kills my routine plot of my GPS-disciplined house 
>> standard
>> against WWVB (that I use for in-house cross-checking / confidence 
>> purposes).
>>
>> I'm using a Kinemetrics Model 60TF WWVB Frequency Comparator / Receiver,
>> that requires a continuous WWVB signal. (This is unlike the consumer 
>> "Atomic
>> Clocks" that the public use; those kinds of WWVB-locked clocks do *not*
>> require a continuous on-air signal, but rather "flywheel" in between
>> scheduled locks a few times per day, as I understand it?)
>>
>> Cheers,
>> Greg
>>
>>

_______________________________________________
time-nuts mailing list -- time-nuts at febo.com
To unsubscribe, go to 
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there. 



From gbusg at comcast.net  Fri Dec 26 20:32:43 2008
From: gbusg at comcast.net (Greg Burnett)
Date: Fri, 26 Dec 2008 13:32:43 -0700
Subject: [time-nuts] WWVB Outages?
References: <49553853.9010509@febo.com> <003d01c96795$b21f6600$6501a8c0@gb02>
	<20081226202542.GA43497@mx1.latt.net>
Message-ID: <005501c96799$1b9c38d0$6501a8c0@gb02>

Good suggestion. ...And, as an enhancement to your suggestion, the start and 
stop times of the outage could be recorded to a spare computer or something.

Greg

----- Original Message ----- 
From: "Majdi S. Abbas" <msa at latt.net>
To: "Discussion of precise time and frequency measurement" 
<time-nuts at febo.com>
Sent: Friday, December 26, 2008 1:25 PM
Subject: Re: [time-nuts] WWVB Outages?


On Fri, Dec 26, 2008 at 01:08:18PM -0700, Greg Burnett wrote:
> In my case, the Kinemetrics 60TF's "Unlock" alarm is *not* latching.
> Therefore you have to be there, to catch the problem "in the act". ...Or
> else run continuous plots.

You could modify the receiver and use an SCR or something similar
as a latching alarm trigger.  Leave the current light in place, but add
an additional one that latches, and a reset button to clear the statE.

Then there's no need for a chart recorder to at least tell if an
alarm has occured since the last time you reset it.

--msa

_______________________________________________
time-nuts mailing list -- time-nuts at febo.com
To unsubscribe, go to 
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there. 



From time-nuts at adobe-labs.com  Fri Dec 26 20:38:45 2008
From: time-nuts at adobe-labs.com (Brent Gordon)
Date: Fri, 26 Dec 2008 13:38:45 -0700
Subject: [time-nuts] WWVB Outages?
In-Reply-To: <005101c96798$af8c7ec0$6501a8c0@gb02>
References: <6E1D662C04714FEEB9A35778D0D85631@S0028384766>	<003101c96793$2f0b6860$6501a8c0@gb02><1E2BB68EAC6B47C083E45A30A37E2997@pc52>	<49553C49.8030903@adobe-labs.com>
	<005101c96798$af8c7ec0$6501a8c0@gb02>
Message-ID: <495540D5.1050407@adobe-labs.com>

You're welcome Greg.  I'm glad I could post something useful to this list.

I was exploring the WWVB website last night and discovered the page that 
lets you see WWVB reception in different parts of the country.  For 
anyone interested, here's the gateway page that lets you see reception 
in Boulder, Gaithersburg, LaCrosse, and Santa Clara:
http://tf.nist.gov/tf-cgi/wwvbmonitor_e.cgi

Brent

Greg Burnett wrote:
> Aha!
>
> Thanks Brent for that link! I wasn't aware that NIST had added that feature.
>
> Thanks again!
> Greg
>
>
> ----- Original Message ----- 
> From: "Brent Gordon" <time-nuts at adobe-labs.com>
> To: "Discussion of precise time and frequency measurement" 
> <time-nuts at febo.com>
> Sent: Friday, December 26, 2008 1:19 PM
> Subject: Re: [time-nuts] WWVB Outages?
>
>
> Your outage matches what NIST shows:
> http://tf.nist.gov/tf-cgi/wwvbgraph_e.cgi?5482602
>
> Brent
>
> Tom Van Baak wrote:
>   
>> Greg,
>>
>> It happens now and then; no big deal. NIST is very good about
>> logging these events for us. For recent (and past 7 years) see:
>>
>> http://tf.nist.gov/stations/wwvboutages.htm
>>
>> /tvb
>>
>>
>>     
>>> Have any of you noticed intermittent WWVB outages lately?
>>>
>>> I've been having that problem, every once in a while, the past month or
>>> more. For example, here in Colorado Springs, the 60 kHz signal 
>>> disappeared
>>> sometime this morning before 11:42AM MST, and returned at 12:28PM MST. 
>>> When
>>> this happens it kills my routine plot of my GPS-disciplined house 
>>> standard
>>> against WWVB (that I use for in-house cross-checking / confidence 
>>> purposes).
>>>
>>> I'm using a Kinemetrics Model 60TF WWVB Frequency Comparator / Receiver,
>>> that requires a continuous WWVB signal. (This is unlike the consumer 
>>> "Atomic
>>> Clocks" that the public use; those kinds of WWVB-locked clocks do *not*
>>> require a continuous on-air signal, but rather "flywheel" in between
>>> scheduled locks a few times per day, as I understand it?)
>>>
>>> Cheers,
>>> Greg
>>>
>>>       


From gbusg at comcast.net  Fri Dec 26 21:11:38 2008
From: gbusg at comcast.net (Greg Burnett)
Date: Fri, 26 Dec 2008 14:11:38 -0700
Subject: [time-nuts] WWVB Outages?
References: <6E1D662C04714FEEB9A35778D0D85631@S0028384766>	<003101c96793$2f0b6860$6501a8c0@gb02><1E2BB68EAC6B47C083E45A30A37E2997@pc52>
	<49553C49.8030903@adobe-labs.com>
Message-ID: <006301c9679e$8afa6850$6501a8c0@gb02>

According to the link (that Brent provided), there were WWVB outages on Dec 
3, 8, 11, 12, 13, 14, 15, 17, 19, 24, 26.

I'm not sure if all those were actual outages or only loss of published data 
for some other reason?

I do know that I've had a lot of WWVB tracking problems this past month. 
...More than just a few.

Upon loss of WWVB signal, my Kinemetrics 60TF drifts 5us in 2 minutes 
(during unlock), but recovers to 0us upon re-lock. But the 60TF cannot 
recover to 0us when the WWVB signal drop-out is greater than 2 minutes. For 
example, it recovers with a 34us offset after a WWVB drop lasting 2.5 
minutes.

Greg



----- Original Message ----- 
From: "Brent Gordon" <time-nuts at adobe-labs.com>
To: "Discussion of precise time and frequency measurement" 
<time-nuts at febo.com>
Sent: Friday, December 26, 2008 1:19 PM
Subject: Re: [time-nuts] WWVB Outages?


Your outage matches what NIST shows:
http://tf.nist.gov/tf-cgi/wwvbgraph_e.cgi?5482602

Brent




From joegwinn at comcast.net  Fri Dec 26 21:19:14 2008
From: joegwinn at comcast.net (Joe Gwinn)
Date: Fri, 26 Dec 2008 16:19:14 -0500
Subject: [time-nuts] Sub Pico Second Phase logger
Message-ID: <p06240814c57af5173110@[192.168.1.212]>

Bruce,

At 10:16 PM +0000 12/23/08, time-nuts-request at febo.com wrote:
>
>Message: 1
>Date: Wed, 24 Dec 2008 08:47:21 +1300
>From: Bruce Griffiths <bruce.griffiths at xtra.co.nz>
>Subject: Re: [time-nuts] Sub Pico Second Phase logger
>To: Discussion of precise time and frequency measurement
>	<time-nuts at febo.com>
>
>[snip]
>  >>>>>
>  >>>>  Using a DDS avoids the requirement for a pair of low phase noise VCOs.
>  >>>>
>  >>>  If we can control the spurs, many DDS chips are very good.
>  >>>
>  >> [BG] A DDS, unlike a conventional digital frequency divider, 
>doesn't suffer
>  >> from aliasing of phase noise into the output passband.
>  >
>>  [JG] How true is this, in practice?  A DDS is at the mercy of phase noise
>>  in its reference clock, by much the same mechanism as for a simple
>>  divider chain.  And the variable-factor dividers (the M and N above)
>>  work in a manner similar to a DDS, but with far coarser increments
>>  and limits.  Both DDS and M/N PLL chips use a PLL to clean up the
>>  resulting ref signal.  Many DDS chips incorporate a M/N PLL to
>  > multiply the ref frequency.
>  >  
>For NIST's measurements of this effect see:
>http://tf.nist.gov/timefreq/general/pdf/1380.pdf

Thanks for the reference.  Very interesting paper, although speckled 
with typos and gaps.   For instance, equation 5 is not grammatical, 
and appears to have been mangled.  There is a later and longer IEEE 
paper by the same authors that I'll get in January.

One would have expected this paper to have appeared 15 or 20 years 
earlier.  I guess the effect wasn't elucidated until many people 
tried to lock microwave sources to 10 MHz.

It also shows how to avoid the aliasing effect: Put an antialiasing 
filter and comparitor between stages.  This is what Ascarrunz does in 
his US patent 6,278,330, specifically Figure 4.  (This patent is what 
ref 3 of paper 1380 became.)


>[snip]
>  >> The simplest way of achieving the required performance is preferable.
>>>    
>>
>>  Yes, but aren't we Time Nuts?
>>
>>
>Usually with finite budgets.

Few dollars, many hours.


Joe


From jra at febo.com  Fri Dec 26 23:02:06 2008
From: jra at febo.com (John Ackermann N8UR)
Date: Fri, 26 Dec 2008 18:02:06 -0500
Subject: [time-nuts] WWVB Outages?
In-Reply-To: <003d01c96795$b21f6600$6501a8c0@gb02>
References: <6E1D662C04714FEEB9A35778D0D85631@S0028384766><003101c96793$2f0b6860$6501a8c0@gb02>	<49553853.9010509@febo.com>
	<003d01c96795$b21f6600$6501a8c0@gb02>
Message-ID: <4955626E.5050609@febo.com>

Haven't had a chance to do that yet, but I looked at my NTP statistics
and my server driven by WWVB did lose lock earlier today, though looking
at the longer term data doesn't show any other losses in the last few
weeks.  Check out http://www.febo.com/time-freq/ntp/stats/ and look for
the toe.febo.com plots.

John
----

Greg Burnett said the following on 12/26/2008 03:08 PM:
> John,
> 
> If it's not too much trouble, could you temporarily disconnect antenna, 
> confirm the alarm, then reconnect antenna to see if the alarm remains 
> latched or goes away.
> 
> In my case, the Kinemetrics 60TF's "Unlock" alarm is *not* latching. 
> Therefore you have to be there, to catch the problem "in the act". ...Or 
> else run continuous plots.
> 
> Greg
> 
> 
> ----- Original Message ----- 
> From: "John Ackermann N8UR" <jra at febo.com>
> To: "Discussion of precise time and frequency measurement" 
> <time-nuts at febo.com>
> Sent: Friday, December 26, 2008 1:02 PM
> Subject: Re: [time-nuts] WWVB Outages?
> 
> 
> I don't see any alarm LEDs on my Spectracom WWVB receivers (one a
> WWVB-DO, the other a clock), but I'm not sure that their "unlock" LEDs
> latch, or that the "error" LEDs trip on loss of lock.
> 
> John
> ----
> 
> Greg Burnett said the following on 12/26/2008 02:50 PM:
>> Have any of you noticed intermittent WWVB outages lately?
>>
>> I've been having that problem, every once in a while, the past month or
>> more. For example, here in Colorado Springs, the 60 kHz signal disappeared
>> sometime this morning before 11:42AM MST, and returned at 12:28PM MST. 
>> When
>> this happens it kills my routine plot of my GPS-disciplined house standard
>> against WWVB (that I use for in-house cross-checking / confidence 
>> purposes).
>>
>> I'm using a Kinemetrics Model 60TF WWVB Frequency Comparator / Receiver,
>> that requires a continuous WWVB signal. (This is unlike the consumer 
>> "Atomic
>> Clocks" that the public use; those kinds of WWVB-locked clocks do *not*
>> require a continuous on-air signal, but rather "flywheel" in between
>> scheduled locks a few times per day, as I understand it?)
>>
>> Cheers,
>> Greg
>>
>>
>>
>>
>> _______________________________________________
>> time-nuts mailing list -- time-nuts at febo.com
>> To unsubscribe, go to 
>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>> and follow the instructions there.
> 
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to 
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there. 
> 
> 
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.


From mpb45 at clanbaker.org  Fri Dec 26 23:11:23 2008
From: mpb45 at clanbaker.org (Michael Baker)
Date: Fri, 26 Dec 2008 18:11:23 -0500
Subject: [time-nuts] Leap-second happens when...??
Message-ID: <4955649B.3070107@clanbaker.org>

Hello, Time-Nutters--

I must have missed something...  I have known about
the coming leap-second for months, but have not heard
when it was going to be inserted. 

When will the leap-second take place?

Will it hurt?   Am I going to need a band-aid?

Or just another rum-laced egg-nog...??

Thanks!!

Mike Baker
WA4HFR
Gainesville, FL
----------------------------------


From hmurray at megapathdsl.net  Fri Dec 26 23:36:15 2008
From: hmurray at megapathdsl.net (Hal Murray)
Date: Fri, 26 Dec 2008 15:36:15 -0800
Subject: [time-nuts] Leap-second happens when...??
In-Reply-To: Message from Michael Baker <mpb45@clanbaker.org> 
	of "Fri, 26 Dec 2008 18:11:23 EST." <4955649B.3070107@clanbaker.org> 
Message-ID: <20081226233616.9ED14BCD7@ip-64-139-1-69.sjc.megapath.net>


> I must have missed something...  I have known about the coming
> leap-second for months, but have not heard when it was going to be
> inserted.  

They try to do it at the end of the year.  Second choice is the end of June.
  http://tf.nist.gov/pubs/bulletin/leapsecond.htm

For me, PST, UTC midnight is 4 PM, a convenient time to watch.

-- 
These are my opinions, not necessarily my employer's.  I hate spam.





From mccorkle at ptialaska.net  Fri Dec 26 23:46:04 2008
From: mccorkle at ptialaska.net (Richard H McCorkle)
Date: Fri, 26 Dec 2008 14:46:04 -0900 (AKST)
Subject: [time-nuts] Happy Holidays
In-Reply-To: <4954B1E3.3040004@xtra.co.nz>
References: <23166.206.174.20.67.1230278691.squirrel@mymail.acsalaska.net>
	<4954A22D.10802@xtra.co.nz> <4954B1E3.3040004@xtra.co.nz>
Message-ID: <23520.206.174.20.67.1230335164.squirrel@mymail.acsalaska.net>

Bruce,

Thank you for your critical evaluation of the interpolator circuitry.
I have no doubt that further improvements to the design are possible
and hope to inspire other amateurs on the list to come up with an
improved interpolator design. The circuit shown provides good results
with very low temperature sensitivity, and I recommend building one
and testing it your self before saying it needs further work to be
useable. What I found in 7 months of testing different variations of
the interpolator (including biased and commutating diode versions as
you have suggested) were:

1. A high-gain constant current source provides the best ramp linearity.
2. Larger capacitors with higher currents produced better stability
   with less effect from stray capacitance.
3. A saturated differential switch had the least effect on ramp
   linearity of numerous switching arrangements tested.
4. With a saturated switch the voltage span across the capacitor can be
   maximized so minimum amplification of the sample voltage is required.
5. Minimum amplification of the sample voltage minimizes the temperature
   sensitivity as voltage variations due to capacitance changes with
   temperature are not amplified.
6. A differential switch provided faster turn-off switching and less
   sample ?droop? at turn-off than using a high-speed commutating diode.

  The transistor switching time is not as critical in this design as
there is always a sample at least 1 clock cycle in duration. Using a
saturated switch insures it has minimum effect on the charge current
delivered to the capacitor by the high-gain constant current source.
Slower turn-on times reduce the minimum count returned, reducing the
data offset, but as long as the turn-on time is consistent and less
than 1 clock cycle in duration the switch is fully saturated and the
ramp is linear at the beginning of the sample period and has little
effect on the data. A slower turn-off time due to saturation increases
the maximum count returned but as long as the transistor turn-off
time is consistent and the maximum sample voltage is below current
source saturation the data span is linear and consistent.
  When a high-speed switching diode was used instead of the
differential switch the diode conducted for a longer period than
the switch transistors and reduced the sample voltage from its
peak value. With similar transistors in the differential switch
the voltage ramp stops abruptly with no turn-off ?droop? evident
in testing. Choice of capacitors is left to the user but 5%
tolerance NPO/COG or mica caps should be used for best temperature
stability. The discharge switch can be replaced with any suitable
device but the 2N7000 switches in 10ns, is readily available, low cost,
and with large sample capacitor values has minimal effect on the data
returned. Testing of the charge linearity without the differential
switch was performed on a similar design with the results shown in
the attached file. The linearity with a saturated differential switch
in the actual interpolator is similar but has not been documented yet.

Richard


>> Bruce Griffiths wrote:
>> Your analog interpolator needs a little work.
>> The switching speed of the 2N3906's is so slow because the 2N3906's that
>> switch the current to ground or into the 470pF cap are saturated.
>> They will switch much faster if used as current mode switches.
>> In fact you can just replace the 2N3906 whose collector is connected to
>> the 470pF cap with a fast switching diode and the current source will be
>> switched much faster.
>> The 2N7000's have a relatively high non linear output capacitance
>> replacing them with something like 1/6X 74HC05 would be better.
>> The 470pF silver mica caps will have relatively large dielectric absorption.
>> NP0/C0G caps would be a better choice, particularly if higher input
>> pulse rates were to be used.
>>
>> Have you actually measured the linearity of the interpolator?
>>
>>
>> Bruce
>>
>>
>>
> The quickest fix is to drop the differential drive to the 2N3906's and
> bias the base of the 2N3906 whose collector is connected to the 470pF
> cap at +2.5V.
> This will ensure the 2N3906's switch much faster.
> The maximum voltage on the 470pF cap should be about 1V to avoid
> saturating the transistor whose collector is connected to it.
> The opamp gain network should then be adjusted to produce the required
> output swing.
> If the maximum charging time of the capacitor is 400ns then the charging
> current should be about 4.7E-10/4E-7 or about 1.2mA.
> The 2N3906's will switch a bit faster if the current is increased to 5
> or 10mA in which case the 470pF cap should be replaced by a ~2nF cap
> (with 5mA charging current).
> Use an NP0/C0G for low dielectric absorption.
>
> Bruce
>
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>
-------------- next part --------------
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From bruce.griffiths at xtra.co.nz  Sat Dec 27 00:50:47 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Sat, 27 Dec 2008 13:50:47 +1300
Subject: [time-nuts] Happy Holidays
In-Reply-To: <23520.206.174.20.67.1230335164.squirrel@mymail.acsalaska.net>
References: <23166.206.174.20.67.1230278691.squirrel@mymail.acsalaska.net>	<4954A22D.10802@xtra.co.nz>
	<4954B1E3.3040004@xtra.co.nz>
	<23520.206.174.20.67.1230335164.squirrel@mymail.acsalaska.net>
Message-ID: <49557BE7.7080303@xtra.co.nz>

Richard

Richard H McCorkle wrote:
> Bruce,
>
> Thank you for your critical evaluation of the interpolator circuitry.
> I have no doubt that further improvements to the design are possible
> and hope to inspire other amateurs on the list to come up with an
> improved interpolator design. The circuit shown provides good results
> with very low temperature sensitivity, and I recommend building one
> and testing it your self before saying it needs further work to be
> useable. What I found in 7 months of testing different variations of
> the interpolator (including biased and commutating diode versions as
> you have suggested) were:
>
>   
I wouldn't waste my time with a circuit that  is inherently as non
linear as yours.
A simulation quickly shows its shortcomings as does you linearity plot.
I've built many interpolation circuits over the years and can see little
purpose in building something with such poor performance.
Especially when a better design requires no extra components, other than
a couple of resistors.
I learned how to do it correctly decades ago.
You comments are misguided, the effect of the substantial base current
of the saturated switches is far from negligible.
> 1. A high-gain constant current source provides the best ramp linearity.
> 2. Larger capacitors with higher currents produced better stability
>    with less effect from stray capacitance.
> 3. A saturated differential switch had the least effect on ramp
>    linearity of numerous switching arrangements tested.
>   
Rubbish, what about the base current of the saturated switch?
Try a real current source drive such as that I suggested and you'll see
how much better it is.
> 4. With a saturated switch the voltage span across the capacitor can be
>    maximized so minimum amplification of the sample voltage is required.
>   
If you want to use such a switch at least use a FET for which the gate
current is essentially negligible.
> 5. Minimum amplification of the sample voltage minimizes the temperature
>    sensitivity as voltage variations due to capacitance changes with
>    temperature are not amplified.
>   
Get real using +1200ppm/C tempco carbon resistors negates this.
> 6. A differential switch provided faster turn-off switching and less
>    sample ?droop? at turn-off than using a high-speed commutating diode.
>
>   
Differential drive only works well when the 2 complementary drive
signals are accurately aligned.
Whilst this is inherent in ECL and current mode logic, it isnt
guaranteed for CMOS logic.
>   The transistor switching time is not as critical in this design as
> there is always a sample at least 1 clock cycle in duration. 
Nonsense, the temperature coefficient of the switching delay of a
saturated switch is relatively large.
> Using a
> saturated switch insures it has minimum effect on the charge current
> delivered to the capacitor by the high-gain constant current source.
>   
Rubbish, it affects the charge substantially.
> Slower turn-on times reduce the minimum count returned, reducing the
> data offset, but as long as the turn-on time is consistent and less
> than 1 clock cycle in duration the switch is fully saturated and the
> ramp is linear at the beginning of the sample period and has little
> effect on the data. A slower turn-off time due to saturation increases
> the maximum count returned but as long as the transistor turn-off
> time is consistent and the maximum sample voltage is below current
> source saturation the data span is linear and consistent.
>   When a high-speed switching diode was used instead of the
> differential switch the diode conducted for a longer period than
> the switch transistors and reduced the sample voltage from its
> peak value. 
Only because the bias and drive for the switching  transistor were
inappropriate.
> With similar transistors in the differential switch
> the voltage ramp stops abruptly with no turn-off ?droop? evident
> in testing. Choice of capacitors is left to the user but 5%
> tolerance NPO/COG or mica caps should be used for best temperature
> stability. The discharge switch can be replaced with any suitable
> device but the 2N7000 switches in 10ns, is readily available, 
So are 74HC05's.
> low cost,
> and with large sample capacitor values has minimal effect on the data
> returned. Testing of the charge linearity without the differential
> switch was performed on a similar design with the results shown in
> the attached file. The linearity with a saturated differential switch
> in the actual interpolator is similar but has not been documented yet.
>
> Richard
>
>   
The capacitor charging current in your design is not as well defined as
it should be, the capacitor charging current in the "operating region"
is about 4.5mA the rest of the 10mA from the current source is lost as
base current in the saturated switch.

Bruce
>   
>>> Bruce Griffiths wrote:
>>> Your analog interpolator needs a little work.
>>> The switching speed of the 2N3906's is so slow because the 2N3906's that
>>> switch the current to ground or into the 470pF cap are saturated.
>>> They will switch much faster if used as current mode switches.
>>> In fact you can just replace the 2N3906 whose collector is connected to
>>> the 470pF cap with a fast switching diode and the current source will be
>>> switched much faster.
>>> The 2N7000's have a relatively high non linear output capacitance
>>> replacing them with something like 1/6X 74HC05 would be better.
>>> The 470pF silver mica caps will have relatively large dielectric absorption.
>>> NP0/C0G caps would be a better choice, particularly if higher input
>>> pulse rates were to be used.
>>>
>>> Have you actually measured the linearity of the interpolator?
>>>
>>>
>>> Bruce
>>>
>>>
>>>
>>>       
>> The quickest fix is to drop the differential drive to the 2N3906's and
>> bias the base of the 2N3906 whose collector is connected to the 470pF
>> cap at +2.5V.
>> This will ensure the 2N3906's switch much faster.
>> The maximum voltage on the 470pF cap should be about 1V to avoid
>> saturating the transistor whose collector is connected to it.
>> The opamp gain network should then be adjusted to produce the required
>> output swing.
>> If the maximum charging time of the capacitor is 400ns then the charging
>> current should be about 4.7E-10/4E-7 or about 1.2mA.
>> The 2N3906's will switch a bit faster if the current is increased to 5
>> or 10mA in which case the 470pF cap should be replaced by a ~2nF cap
>> (with 5mA charging current).
>> Use an NP0/C0G for low dielectric absorption.
>>
>> Bruce
>>
>> _______________________________________________
>> time-nuts mailing list -- time-nuts at febo.com
>> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>> and follow the instructions there.
>>
>>     
>> ------------------------------------------------------------------------
>>
>> _______________________________________________
>> time-nuts mailing list -- time-nuts at febo.com
>> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>> and follow the instructions there.



From holrum at hotmail.com  Sat Dec 27 00:59:40 2008
From: holrum at hotmail.com (Mark Sims)
Date: Sat, 27 Dec 2008 00:59:40 +0000
Subject: [time-nuts] Leap-second happens when...??
In-Reply-To: <mailman.784.1230335169.2499.time-nuts@febo.com>
References: <mailman.784.1230335169.2499.time-nuts@febo.com>
Message-ID: <BLU125-W43723CC5A421067C47FABDCEE80@phx.gbl>


If Lady Heather (Queen Mistress of the well disciplined oscillator) inserts the leap second it WILL hurt...  and you WILL like it...

---------

I must have missed something...  I have known about
the coming leap-second for months, but have not heard
when it was going to be inserted. 

When will the leap-second take place?

Will it hurt?   Am I going to need a band-aid?

Or just another rum-laced egg-nog...??
_________________________________________________________________
Life on your PC is safer, easier, and more enjoyable with Windows Vista?. 
http://clk.atdmt.com/MRT/go/127032870/direct/01/

From didier at cox.net  Sat Dec 27 01:06:17 2008
From: didier at cox.net (Didier)
Date: Fri, 26 Dec 2008 19:06:17 -0600
Subject: [time-nuts] Request for MC598X4 and Datum LPRO datasheet
In-Reply-To: <495546BE.4040209@bol.com.br>
References: <495546BE.4040209@bol.com.br>
Message-ID: <BB020F7D1B8D48E6AC062816D7066EF5@didierhp>

Go to http://www.ko4bb.com/cgi-bin/search.pl
And enter lpro in the Search box

Didier KO4BB

> -----Original Message-----
> From: time-nuts-bounces at febo.com 
> [mailto:time-nuts-bounces at febo.com] On Behalf Of Daniel Mendes
> Sent: Friday, December 26, 2008 3:04 PM
> To: time-nuts at febo.com
> Subject: [time-nuts] Request for MC598X4 and Datum LPRO datasheet
> 
> Hy, my name is Daniel, I lurk at this list trying to learn 
> something with the masters of time measurements  :)  I?ve 
> bought two MC598X4 from Ebay. Does someone have a datasheet 
> for them? Or at least the pinouts...
> I?ve bought also an  Datum LPRO 102500-001 but the datasheet 
> is no more available at  
> http://www.symmetricom.com/media/pdf/manuals/man-lpro.pdf  .
> Does someone have a copy?
>  
>  Thanks!
>  
>  Daniel
> 
> 
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com To unsubscribe, 
> go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
> 



From bruce.griffiths at xtra.co.nz  Sat Dec 27 01:12:44 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Sat, 27 Dec 2008 14:12:44 +1300
Subject: [time-nuts] Happy Holidays
In-Reply-To: <49557BE7.7080303@xtra.co.nz>
References: <23166.206.174.20.67.1230278691.squirrel@mymail.acsalaska.net>	<4954A22D.10802@xtra.co.nz>	<4954B1E3.3040004@xtra.co.nz>	<23520.206.174.20.67.1230335164.squirrel@mymail.acsalaska.net>
	<49557BE7.7080303@xtra.co.nz>
Message-ID: <4955810C.8000202@xtra.co.nz>

Richard

The attached circuit illustrates how to construct a simple high
linearity ramp TAC.
The circuit has been used in various guises for decades.
The latest incarnations use ultra high speed IC processes to integrate
all components on chip to minimise interconnection inductances and
achieve subpicosecond resolution.
Just change the transistors, capacitor value etc to suit the desired range.

Bruce
-------------- next part --------------
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From mccorkle at ptialaska.net  Sat Dec 27 01:27:03 2008
From: mccorkle at ptialaska.net (Richard H McCorkle)
Date: Fri, 26 Dec 2008 16:27:03 -0900 (AKST)
Subject: [time-nuts] Happy Holidays
In-Reply-To: <4955810C.8000202@xtra.co.nz>
References: <23166.206.174.20.67.1230278691.squirrel@mymail.acsalaska.net>
	<4954A22D.10802@xtra.co.nz> <4954B1E3.3040004@xtra.co.nz>
	<23520.206.174.20.67.1230335164.squirrel@mymail.acsalaska.net>
	<49557BE7.7080303@xtra.co.nz> <4955810C.8000202@xtra.co.nz>
Message-ID: <23644.206.174.20.67.1230341223.squirrel@mymail.acsalaska.net>

Bruce,

Thank You for posting a proper TAC, I'll give your circuit a try so I
improve my education in interpolator design before sharing any further
work with this list.

Richard


> Richard
>
> The attached circuit illustrates how to construct a simple high
> linearity ramp TAC.
> The circuit has been used in various guises for decades.
> The latest incarnations use ultra high speed IC processes to integrate
> all components on chip to minimise interconnection inductances and
> achieve subpicosecond resolution.
> Just change the transistors, capacitor value etc to suit the desired range.
>
> Bruce
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.




From peterawson at earthlink.net  Sat Dec 27 02:10:47 2008
From: peterawson at earthlink.net (Pete)
Date: Fri, 26 Dec 2008 19:10:47 -0700
Subject: [time-nuts] Sub Pico Second Phase logger
References: <p06240804c571adf034e9@[192.168.1.212]>
Message-ID: <212B042106C6419F9EAA1EA481E4D129@BASE1>

Joe,

I have been following this thread from the start & learned a lot from it.

Thanks to you and Bruce for the insights.

I thought I would take a look at a simple, passive approach, just to
see what happens. I also limited my attention to stable 5 or 10 MHz
sources & observation windows of <100s. I used a Mini-circuits
SYPD-1 PD with a PSCQ-2-10.5 90 deg hybrid plus an ATM
P1506 phase shifter (delta=0.32ns). There are lots of other items
which will work just as well, this stuff happens to be on hand.

The SYPD-1 also needs a diplexer to terminate the high order
products & low pass filter the desired output; this is a cobble
together item from the parts box. I used a PC logging program
with my HP 3478A to take DC readings from the diplexer output.

Thus armed, I first checked the DVM logging with no RF in to see
if it was stable enough to yield a useable noise floor. This first result
was good enough. Reading 720 points over 100 seconds; the data
was limited to -1, 0 or +1 uV.

Then I applied 10MHz @ to the 90 deg hybrid & connected one
hybrid output to the SYPD-1 LO & the other hybrid output to the
ATM P1506. The ATM output then drives the SYPD-1 RF port.
I measured both SYPD-1 inputs to be +6.4dBm. Now I was able
to set the ATM phase to zero the SYPD-1 output & verify it was
stable over the 100s time I was interested in. The 3478A readings
ranged from -1 to +2uV during this time with STDDEV of 0.6uV 
-again, good enough for me.

Finally, I used a HP 105B to get a quiet 5MHz source & a 1MHz
ext. reference for my HP3336C sythesizer. All this to give me 2
"nearly" identical. phase locked sources to measure the calibration
factor of the SYPD-1/Diplexer output. The 3336C was set to
5,000,000.005Hz & +6.4dBm driving the SYPD-1 LO port. The
105B 5MHz output was attenuated to +6.4dBm driving the RF
port. The resulting 5mHz data was logged & analyzed at the zero
crossings (max gain). The result is a phase sensitivity of 1.22uRad/uV.
The + & - zero crossings were identical and the 1.22uRad/uV factor
is linear (+/- 2 %) up to +/- 20 % of FS. FS = 1.023V

If my math is about right, @10MHz, 1uRad = 16fs; so a noise floor
of +/- 2uV (+/-2.5uRad) equals +/-40fs. I expect that, if 2 sources
are near zero phase, then it should only require <10s to estimate
the actual phase error within 1ps, or less. Anyone agree?

I await & hope for constructive comments and/or corrections.

Pete Rawson


From dmendesf at bol.com.br  Sat Dec 27 03:21:40 2008
From: dmendesf at bol.com.br (Daniel Mendes)
Date: Sat, 27 Dec 2008 00:21:40 -0300
Subject: [time-nuts] Request for MC598X4 and Datum LPRO datasheet
Message-ID: <49559F44.6050305@bol.com.br>

Thank you Didier! Now I just need to find out how to power the  
MC598X4...

Daniel

    Go to http://www.ko4bb.com/cgi-bin/search.pl
    And enter lpro in the Search box

    Didier KO4BB

      

>     > -----Original Message-----
>     > From: time-nuts-bounces at febo.com 
>     > [mailto:time-nuts-bounces at febo.com] On Behalf Of Daniel Mendes
>     > Sent: Friday, December 26, 2008 3:04 PM
>     > To: time-nuts at febo.com
>     > Subject: [time-nuts] Request for MC598X4 and Datum LPRO datasheet
>     > 
>     > Hy, my name is Daniel, I lurk at this list trying to learn 
>     > something with the masters of time measurements   :)   I?ve 
>     > bought two MC598X4 from Ebay. Does someone have a datasheet 
>     > for them? Or at least the pinouts...
>     > I?ve bought also an  Datum LPRO 102500-001 but the datasheet 
>     > is no more available at  
>     > http://www.symmetricom.com/media/pdf/manuals/man-lpro.pdf  .
>     > Does someone have a copy?
>     >  



From bruce.griffiths at xtra.co.nz  Sat Dec 27 02:46:33 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Sat, 27 Dec 2008 15:46:33 +1300
Subject: [time-nuts] Sub Pico Second Phase logger
In-Reply-To: <212B042106C6419F9EAA1EA481E4D129@BASE1>
References: <p06240804c571adf034e9@[192.168.1.212]>
	<212B042106C6419F9EAA1EA481E4D129@BASE1>
Message-ID: <49559709.9020606@xtra.co.nz>

Pete

Pete wrote:
> Joe,
>
> I have been following this thread from the start & learned a lot from it.
>
> Thanks to you and Bruce for the insights.
>
> I thought I would take a look at a simple, passive approach, just to
> see what happens. I also limited my attention to stable 5 or 10 MHz
> sources & observation windows of <100s. I used a Mini-circuits
> SYPD-1 PD with a PSCQ-2-10.5 90 deg hybrid plus an ATM
> P1506 phase shifter (delta=0.32ns). There are lots of other items
> which will work just as well, this stuff happens to be on hand.
>
> The SYPD-1 also needs a diplexer to terminate the high order
> products & low pass filter the desired output; this is a cobble
> together item from the parts box. I used a PC logging program
> with my HP 3478A to take DC readings from the diplexer output.
>
>   
The use of a diplexer perpetuates a common fallacy.
You get significantly lower noise with a capacitive IF port termination.
This is true even in the microwave region when reflecting the sum
frequency back into the mixer reduces the noise.
At low frequencies this has little effect on the Rf and LO port VSWR.
The capacitive termination limits the IF port bandwidth to a few tens of
kHz and a 50 ohm termination is more useful if an IF bandwidth of
several MHz is desired.
> Thus armed, I first checked the DVM logging with no RF in to see
> if it was stable enough to yield a useable noise floor. This first result
> was good enough. Reading 720 points over 100 seconds; the data
> was limited to -1, 0 or +1 uV.
>
> Then I applied 10MHz @ to the 90 deg hybrid & connected one
> hybrid output to the SYPD-1 LO & the other hybrid output to the
> ATM P1506. The ATM output then drives the SYPD-1 RF port.
> I measured both SYPD-1 inputs to be +6.4dBm. Now I was able
> to set the ATM phase to zero the SYPD-1 output & verify it was
> stable over the 100s time I was interested in. The 3478A readings
> ranged from -1 to +2uV during this time with STDDEV of 0.6uV 
> -again, good enough for me.
>   
Can you produce ADEV and MDEV plots for tau up to 1000sec or more?
This would then give us some idea of the noise floor of your setup.
SDEV by itself can be very misleading as for some noise processes it
diverges.
The RPD and MPD series are better, in that they allow low frequency
isolation of the RF, LO and IF port grounds.
This can be critical for low offset frequency measurements.

> Finally, I used a HP 105B to get a quiet 5MHz source & a 1MHz
> ext. reference for my HP3336C sythesizer. All this to give me 2
> "nearly" identical. phase locked sources to measure the calibration
> factor of the SYPD-1/Diplexer output. The 3336C was set to
> 5,000,000.005Hz & +6.4dBm driving the SYPD-1 LO port. The
> 105B 5MHz output was attenuated to +6.4dBm driving the RF
> port. The resulting 5mHz data was logged & analyzed at the zero
> crossings (max gain). The result is a phase sensitivity of 1.22uRad/uV.
> The + & - zero crossings were identical and the 1.22uRad/uV factor
> is linear (+/- 2 %) up to +/- 20 % of FS. FS = 1.023V
>
> If my math is about right, @10MHz, 1uRad = 16fs; so a noise floor
> of +/- 2uV (+/-2.5uRad) equals +/-40fs. I expect that, if 2 sources
> are near zero phase, then it should only require <10s to estimate
> the actual phase error within 1ps, or less. Anyone agree?
>
> I await & hope for constructive comments and/or corrections.
>
> Pete Rawson
>
>   
At 10MHz 1 radian = 16ns
1 millirad = 16 ps.
1urad = 16fs.

It would be more useful if you logged the DVM readings for an hour or
more so that ADEV, MDEV plots can be produced.
Eyeballing the data doesnt always deliver the full story.

If one compares a couple of oscillators one has to be very careful to
ensure that inadvertent injection locking isn't occuring.
This can happen with almost imperceptible coupling if the oscillators
are very close in frequency.
You need to use very high reverse isolation ( ideally 150dB or more)
buffer amplifiers to ensure this doesnt occur.

The first test you made only indicates the system noise floor.
When the mixer/phase detector is driven by 2 different oscillators the
noise level will be much higher that the noise level of the mixer system
itself.
In fact practically all OCXOs will/should be much noisier.
If the noise is too low this is an indication of injection locking.

One thing to watch out for is the measurement system noise bandwidth.
You need to know this as ADEV, MDEV etc depend on the actual noise
bandwidth.
When you use a DVM it usually has built in low pass filtering as well as
its inherent sinc response due to the integration process.
It can be useful to use external passive components to accurately define
the noise response.

Bruce


From bruce.griffiths at xtra.co.nz  Sat Dec 27 03:15:21 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Sat, 27 Dec 2008 16:15:21 +1300
Subject: [time-nuts] Sub Pico Second Phase logger
In-Reply-To: <49559709.9020606@xtra.co.nz>
References: <p06240804c571adf034e9@[192.168.1.212]>	<212B042106C6419F9EAA1EA481E4D129@BASE1>
	<49559709.9020606@xtra.co.nz>
Message-ID: <49559DC9.7010108@xtra.co.nz>

Pete

Another very useful thing to do is to measure the output noise spectrum
at the of mixer port both with capacitive termination and with a diplexer.
You can do this with your PC sound card system (even the motherboard
one) and a low noise preamp.
If you want a simple low noise preamp circuit I can supply several.
The gain required depends on the sound card depends on the sound cards
internal noise level.
One way is to drive the RF and LO ports with quadrature phase signals
and measure the IF spectrum.
Another is to just drive the LO port and look at the IF port spectrum.
Try both with the Rf port open circuit and terminated in 50 ohms.
Once you've obtained spectra posting them would be useful and informative.

Bruce


Bruce Griffiths wrote:
> Pete
>
> Pete wrote:
>   
>> Joe,
>>
>> I have been following this thread from the start & learned a lot from it.
>>
>> Thanks to you and Bruce for the insights.
>>
>> I thought I would take a look at a simple, passive approach, just to
>> see what happens. I also limited my attention to stable 5 or 10 MHz
>> sources & observation windows of <100s. I used a Mini-circuits
>> SYPD-1 PD with a PSCQ-2-10.5 90 deg hybrid plus an ATM
>> P1506 phase shifter (delta=0.32ns). There are lots of other items
>> which will work just as well, this stuff happens to be on hand.
>>
>> The SYPD-1 also needs a diplexer to terminate the high order
>> products & low pass filter the desired output; this is a cobble
>> together item from the parts box. I used a PC logging program
>> with my HP 3478A to take DC readings from the diplexer output.
>>
>>   
>>     
> The use of a diplexer perpetuates a common fallacy.
> You get significantly lower noise with a capacitive IF port termination.
> This is true even in the microwave region when reflecting the sum
> frequency back into the mixer reduces the noise.
> At low frequencies this has little effect on the Rf and LO port VSWR.
> The capacitive termination limits the IF port bandwidth to a few tens of
> kHz and a 50 ohm termination is more useful if an IF bandwidth of
> several MHz is desired.
>   
>> Thus armed, I first checked the DVM logging with no RF in to see
>> if it was stable enough to yield a useable noise floor. This first result
>> was good enough. Reading 720 points over 100 seconds; the data
>> was limited to -1, 0 or +1 uV.
>>
>> Then I applied 10MHz @ to the 90 deg hybrid & connected one
>> hybrid output to the SYPD-1 LO & the other hybrid output to the
>> ATM P1506. The ATM output then drives the SYPD-1 RF port.
>> I measured both SYPD-1 inputs to be +6.4dBm. Now I was able
>> to set the ATM phase to zero the SYPD-1 output & verify it was
>> stable over the 100s time I was interested in. The 3478A readings
>> ranged from -1 to +2uV during this time with STDDEV of 0.6uV 
>> -again, good enough for me.
>>   
>>     
> Can you produce ADEV and MDEV plots for tau up to 1000sec or more?
> This would then give us some idea of the noise floor of your setup.
> SDEV by itself can be very misleading as for some noise processes it
> diverges.
> The RPD and MPD series are better, in that they allow low frequency
> isolation of the RF, LO and IF port grounds.
> This can be critical for low offset frequency measurements.
>
>   
>> Finally, I used a HP 105B to get a quiet 5MHz source & a 1MHz
>> ext. reference for my HP3336C sythesizer. All this to give me 2
>> "nearly" identical. phase locked sources to measure the calibration
>> factor of the SYPD-1/Diplexer output. The 3336C was set to
>> 5,000,000.005Hz & +6.4dBm driving the SYPD-1 LO port. The
>> 105B 5MHz output was attenuated to +6.4dBm driving the RF
>> port. The resulting 5mHz data was logged & analyzed at the zero
>> crossings (max gain). The result is a phase sensitivity of 1.22uRad/uV.
>> The + & - zero crossings were identical and the 1.22uRad/uV factor
>> is linear (+/- 2 %) up to +/- 20 % of FS. FS = 1.023V
>>
>> If my math is about right, @10MHz, 1uRad = 16fs; so a noise floor
>> of +/- 2uV (+/-2.5uRad) equals +/-40fs. I expect that, if 2 sources
>> are near zero phase, then it should only require <10s to estimate
>> the actual phase error within 1ps, or less. Anyone agree?
>>
>> I await & hope for constructive comments and/or corrections.
>>
>> Pete Rawson
>>
>>   
>>     
> At 10MHz 1 radian = 16ns
> 1 millirad = 16 ps.
> 1urad = 16fs.
>
> It would be more useful if you logged the DVM readings for an hour or
> more so that ADEV, MDEV plots can be produced.
> Eyeballing the data doesnt always deliver the full story.
>
> If one compares a couple of oscillators one has to be very careful to
> ensure that inadvertent injection locking isn't occuring.
> This can happen with almost imperceptible coupling if the oscillators
> are very close in frequency.
> You need to use very high reverse isolation ( ideally 150dB or more)
> buffer amplifiers to ensure this doesnt occur.
>
> The first test you made only indicates the system noise floor.
> When the mixer/phase detector is driven by 2 different oscillators the
> noise level will be much higher that the noise level of the mixer system
> itself.
> In fact practically all OCXOs will/should be much noisier.
> If the noise is too low this is an indication of injection locking.
>
> One thing to watch out for is the measurement system noise bandwidth.
> You need to know this as ADEV, MDEV etc depend on the actual noise
> bandwidth.
> When you use a DVM it usually has built in low pass filtering as well as
> its inherent sinc response due to the integration process.
> It can be useful to use external passive components to accurately define
> the noise response.
>
> Bruce
>
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>
>   



From namichie at gmail.com  Sat Dec 27 04:58:22 2008
From: namichie at gmail.com (Neville Michie)
Date: Sat, 27 Dec 2008 15:58:22 +1100
Subject: [time-nuts] Request for MC598X4 and Datum LPRO datasheet
In-Reply-To: <BB020F7D1B8D48E6AC062816D7066EF5@didierhp>
References: <495546BE.4040209@bol.com.br>
	<BB020F7D1B8D48E6AC062816D7066EF5@didierhp>
Message-ID: <63FFA1F9-0792-4D5B-8ECE-8F623EA32BE4@gmail.com>

Hi,
The LPRO manual has a circuit mistake on page 16.
The north end of R145 should go to +17V, not the resistor junction.
It may make a difference when interfacing the unit.
Seasons Greetings
Neville Michie



On 27/12/2008, at 12:06 PM, Didier wrote:

> Go to http://www.ko4bb.com/cgi-bin/search.pl
> And enter lpro in the Search box
>
> Didier KO4BB
>
>> -----Original Message-----
>> From: time-nuts-bounces at febo.com
>> [mailto:time-nuts-bounces at febo.com] On Behalf Of Daniel Mendes
>> Sent: Friday, December 26, 2008 3:04 PM
>> To: time-nuts at febo.com
>> Subject: [time-nuts] Request for MC598X4 and Datum LPRO datasheet
>>
>> Hy, my name is Daniel, I lurk at this list trying to learn
>> something with the masters of time measurements  :)  I?ve
>> bought two MC598X4 from Ebay. Does someone have a datasheet
>> for them? Or at least the pinouts...
>> I?ve bought also an  Datum LPRO 102500-001 but the datasheet
>> is no more available at
>> http://www.symmetricom.com/media/pdf/manuals/man-lpro.pdf  .
>> Does someone have a copy?
>>
>>  Thanks!
>>
>>  Daniel
>>
>>
>> _______________________________________________
>> time-nuts mailing list -- time-nuts at febo.com To unsubscribe,
>> go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>> and follow the instructions there.
>>
>
>
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/ 
> time-nuts
> and follow the instructions there.



From holrum at hotmail.com  Sat Dec 27 05:12:02 2008
From: holrum at hotmail.com (Mark Sims)
Date: Sat, 27 Dec 2008 05:12:02 +0000
Subject: [time-nuts] Happy Holidays
In-Reply-To: <mailman.786.1230340369.2499.time-nuts@febo.com>
References: <mailman.786.1230340369.2499.time-nuts@febo.com>
Message-ID: <BLU125-W54E65F48D2AEBEA026580DCEE80@phx.gbl>


Another possible thing to try is one of the Miller integrator chips that Tektronix used in their scopes and time base modules.  I seem to remember that at least one could yield 0.01% linearity.  The 5Bxx and 7Bxx modules for the 5000 and 7000 series scopes are available in vast quantities,  often for less than $10 (plus about that in shipping).  There is also an Ebay seller that has one of the chips in lots of 10...  search for "Tektronix miller".   I don't know what unit those chips were from.  They are in a TO5 type can,  not the usual DIP package.  To use a particular chip  you would need to do some reverse engineering from the appropriate module service manual.  The connections are usually fairly simple.
_________________________________________________________________
It?s the same Hotmail?. If by ?same? you mean up to 70% faster.
http://windowslive.com/online/hotmail?ocid=TXT_TAGLM_WL_hotmail_acq_broad1_122008

From kc0ukk at msosborn.com  Sat Dec 27 06:33:14 2008
From: kc0ukk at msosborn.com (Matt Osborn)
Date: Sat, 27 Dec 2008 00:33:14 -0600
Subject: [time-nuts] DMTD mixer question
In-Reply-To: <493932A8.5030001@xtra.co.nz>
References: <2ae26e4e0812030750i1e8b0af4x4e99ccafcfcf7812@mail.gmail.com>	<4936D8D7.70204@xtra.co.nz>	<ECE7A93BD093E1439C20020FBE87C47FEB55DA84B2@ALTPHYEMBEVSP20.RES.AD.JPL>	<4936E5B0.2070201@xtra.co.nz>	<2ae26e4e0812031548te0e935awcd007815ccc490a4@mail.gmail.com>	<49372FF1.5020608@xtra.co.nz>
	<2ae26e4e0812050357l2bfc5ae0ubbeda1299004aee6@mail.gmail.com>
	<493932A8.5030001@xtra.co.nz>
Message-ID: <osibl4h7irfumc5e08aioudu86i8fv06o4@4ax.com>

On Sat, 06 Dec 2008 02:54:48 +1300, Bruce Griffiths
<bruce.griffiths at xtra.co.nz> wrote:

>At least a couple of us have the Spartan 3E board.

Is the ISE evaluation software time limited?

-- kc0ukk at msosborn dot com


From hmurray at megapathdsl.net  Sat Dec 27 06:53:54 2008
From: hmurray at megapathdsl.net (Hal Murray)
Date: Fri, 26 Dec 2008 22:53:54 -0800
Subject: [time-nuts] DMTD mixer question
In-Reply-To: Message from Matt Osborn <kc0ukk@msosborn.com> of "Sat,
	27 Dec 2008 00:33:14 CST." <osibl4h7irfumc5e08aioudu86i8fv06o4@4ax.com>
Message-ID: <20081227065355.89DC9BCD7@ip-64-139-1-69.sjc.megapath.net>

>>At least a couple of us have the Spartan 3E board.

> Is the ISE evaluation software time limited?

No, but there isn't any support and it doesn't work on the big/expensive 
chips.

You can search their web site.  Many bugs/glitches that get processed through 
their support system (and are bugs rather than user errors) get written up 
and turned into a web page.

comp.arch.fpga on usenet is pretty good.


-- 
These are my opinions, not necessarily my employer's.  I hate spam.





From hmurray at megapathdsl.net  Sat Dec 27 07:38:02 2008
From: hmurray at megapathdsl.net (Hal Murray)
Date: Fri, 26 Dec 2008 23:38:02 -0800
Subject: [time-nuts] DMTD mixer question
In-Reply-To: Message from Hal Murray <hmurray@megapathdsl.net> of "Fri,
	26 Dec 2008 22:53:54 PST."
	<20081227065355.89DC9BCD7@ip-64-139-1-69.sjc.megapath.net> 
Message-ID: <20081227073803.B1D41BCD7@ip-64-139-1-69.sjc.megapath.net>


> >>At least a couple of us have the Spartan 3E board.
> > Is the ISE evaluation software time limited?
> No, but there isn't any support and it doesn't work on the big/
> expensive  chips. 

I got confused and/or that's misleading.  Let me try again.

Xilinx has 2 basic software packages: ISE and Webpack.

Webpack is a subset of ISE.  It's free.  You can pull a copy off the web.  
There is no support and it doesn't handle the high end chips.

ISE is $.  There is an evaluation package shipped with every demo/evaluation 
board.  That is time limited.  If you purchase a copy, you get support for a 
year.  After that, for an annual fee you get support and updates.

If you don't pay for support/updates, the software keeps working.  At least 
it did several/many years ago when I last when through that dance.  I doubt 
if that has changed but YMMV.  (I assumed that the idea was that you should 
be able to archive the PC you used to work on a system and it would work if 
you turned it on after a few years to make a minor change.)


Webpack is good enough to get a lot of work done.  You might want some of the 
fancier features.  You probably don't want to pay for ISE if all you are 
doing is hobby stuff.


-- 
These are my opinions, not necessarily my employer's.  I hate spam.





From magnus at rubidium.dyndns.org  Sat Dec 27 09:24:38 2008
From: magnus at rubidium.dyndns.org (Magnus Danielson)
Date: Sat, 27 Dec 2008 10:24:38 +0100
Subject: [time-nuts] Leap-second happens when...??
In-Reply-To: <4955649B.3070107@clanbaker.org>
References: <4955649B.3070107@clanbaker.org>
Message-ID: <4955F456.8000800@rubidium.dyndns.org>

Michael Baker skrev:
> Hello, Time-Nutters--
> 
> I must have missed something...  I have known about
> the coming leap-second for months, but have not heard
> when it was going to be inserted. 
> 
> When will the leap-second take place?

A leap-second can be inserted or removed at the end of the last minute 
of a month in UTC.

Normal transition:
23:59:58
23:59:59
00:00:00

Adding a leap second:
23:59:58
23:59:59
23:59:60
00:00:00

Removing a leap second:
23:59:58
00:00:00

The first preference on which month to insert them is first to the June 
and December.

The second preference is on Mars and September.

You naturally need to convert to your local time zone to get a little 
more aid on when it happens, but for Florida it will occur at 18:00 
(UTC-6h) on Wednesday where as for me it will occur at 1:00 (UTC+1h) on 
Thursday.

> Will it hurt?

No.

> Am I going to need a band-aid?

No.

> Or just another rum-laced egg-nog...??

Yes. Sounds like a good idea. But don't drink it all during the 
leap-second, that would be a waste of perfectly good egg-nog.

Cheers,
Magnus


From joegwinn at comcast.net  Sat Dec 27 16:52:16 2008
From: joegwinn at comcast.net (Joe Gwinn)
Date: Sat, 27 Dec 2008 11:52:16 -0500
Subject: [time-nuts] Sub Pico Second Phase logger
Message-ID: <p06240817c57c0a3b261e@[192.168.1.212]>

Pete,

At 4:58 AM +0000 12/27/08, time-nuts-request at febo.com wrote:
>
>Message: 2
>Date: Fri, 26 Dec 2008 19:10:47 -0700
>From: "Pete" <peterawson at earthlink.net>
>Subject: Re: [time-nuts] Sub Pico Second Phase logger
>To: "Discussion of precise time and frequency measurement"
>	<time-nuts at febo.com>
>
>Joe,
>
>I have been following this thread from the start & learned a lot from it.
>
>Thanks to you and Bruce for the insights.
>
>I thought I would take a look at a simple, passive approach, just to
>see what happens. I also limited my attention to stable 5 or 10 MHz
>sources & observation windows of <100s. I used a Mini-circuits
>SYPD-1 PD with a PSCQ-2-10.5 90 deg hybrid plus an ATM
>P1506 phase shifter (delta=0.32ns). There are lots of other items
>which will work just as well, this stuff happens to be on hand.
>
>The SYPD-1 also needs a diplexer to terminate the high order
>products & low pass filter the desired output; this is a cobble
>together item from the parts box. I used a PC logging program
>with my HP 3478A to take DC readings from the diplexer output.

What do you mean by "diplexer"?


>Thus armed, I first checked the DVM logging with no RF in to see
>if it was stable enough to yield a useable noise floor. This first result
>was good enough. Reading 720 points over 100 seconds; the data
>was limited to -1, 0 or +1 uV.
>
>Then I applied 10MHz @ to the 90 deg hybrid & connected one
>hybrid output to the SYPD-1 LO & the other hybrid output to the
>ATM P1506. The ATM output then drives the SYPD-1 RF port.
>I measured both SYPD-1 inputs to be +6.4dBm. Now I was able
>to set the ATM phase to zero the SYPD-1 output & verify it was
>stable over the 100s time I was interested in. The 3478A readings
>ranged from -1 to +2uV during this time with STDDEV of 0.6uV
>-again, good enough for me.
>
>Finally, I used a HP 105B to get a quiet 5MHz source & a 1MHz
>ext. reference for my HP3336C sythesizer. All this to give me 2
>"nearly" identical. phase locked sources to measure the calibration
>factor of the SYPD-1/Diplexer output. The 3336C was set to
>5,000,000.005Hz & +6.4dBm driving the SYPD-1 LO port. The
>105B 5MHz output was attenuated to +6.4dBm driving the RF
>port. The resulting 5mHz data was logged & analyzed at the zero
>crossings (max gain). The result is a phase sensitivity of 1.22uRad/uV.
>The + & - zero crossings were identical and the 1.22uRad/uV factor
>is linear (+/- 2 %) up to +/- 20 % of FS. FS = 1.023V
>
>If my math is about right, @10MHz, 1uRad = 16fs; so a noise floor
>of +/- 2uV (+/-2.5uRad) equals +/-40fs. I expect that, if 2 sources
>are near zero phase, then it should only require <10s to estimate
>the actual phase error within 1ps, or less. Anyone agree?
>
>I await & hope for constructive comments and/or corrections.

I've done similar things, and can also get random errors in the 
femtoseconds, but only over short periods of time.  The key is 
temperature sensitivity.   I would be suspicious of the 90 degree 
hybrid in particular, although the phase detector also has an 
opinion. The splitter phase unbalance is also quite sensitive to 
drive frequency, so the frequency stable sources are essential.

Joe


From pvince at theiet.org  Sat Dec 27 16:57:19 2008
From: pvince at theiet.org (Peter Vince)
Date: Sat, 27 Dec 2008 16:57:19 +0000
Subject: [time-nuts] Leap-second happens when...??
Message-ID: <62299.1230397039@uk2.net>


>For me, PST, UTC midnight is 4 PM, a convenient time to watch.

For those of us in the zulu time zone (near the Greenwich meridian), happening
just as the new year is about to start is not *nearly* so convenient - especially
if you are trying to transmit new year celebration programmes, and praying the
equipment doesn't fall over!

Peter



From ka2cdk at cox.net  Sat Dec 27 17:10:28 2008
From: ka2cdk at cox.net (Thomas A. Frank)
Date: Sat, 27 Dec 2008 12:10:28 -0500
Subject: [time-nuts] Leap-second happens when...??
In-Reply-To: <62299.1230397039@uk2.net>
References: <62299.1230397039@uk2.net>
Message-ID: <7D0818AF-8248-4E9F-885B-C5C05B70C6D9@cox.net>

>> For me, PST, UTC midnight is 4 PM, a convenient time to watch.
>
> For those of us in the zulu time zone (near the Greenwich  
> meridian), happening
> just as the new year is about to start is not *nearly* so  
> convenient - especially
> if you are trying to transmit new year celebration programmes, and  
> praying the
> equipment doesn't fall over!
>
> Peter


No really, should you be more concerned with the equipment or the  
operator falling over on New Years Eve?

Tom Frank, KA2CDK




From magnus at rubidium.dyndns.org  Sat Dec 27 17:14:28 2008
From: magnus at rubidium.dyndns.org (Magnus Danielson)
Date: Sat, 27 Dec 2008 18:14:28 +0100
Subject: [time-nuts] Leap-second happens when...??
In-Reply-To: <62299.1230397039@uk2.net>
References: <62299.1230397039@uk2.net>
Message-ID: <49566274.8020404@rubidium.dyndns.org>

Peter Vince skrev:
>> For me, PST, UTC midnight is 4 PM, a convenient time to watch.
> 
> For those of us in the zulu time zone (near the Greenwich meridian), happening
> just as the new year is about to start is not *nearly* so convenient - especially
> if you are trying to transmit new year celebration programmes, and praying the
> equipment doesn't fall over!

"At the time Big Ben strikes midnight we expect a slight interrupt of 
the programme, for which we are deeply sorry."

Maybe it could be a big motivator for getting an upgrade of equipment.

I feel for you, as you need to stand by (physically) rather than staying 
at home or with friends as appropriate.

Cheers,
Magnus


From magnus at rubidium.dyndns.org  Sat Dec 27 17:19:05 2008
From: magnus at rubidium.dyndns.org (Magnus Danielson)
Date: Sat, 27 Dec 2008 18:19:05 +0100
Subject: [time-nuts] Leap-second happens when...??
In-Reply-To: <7D0818AF-8248-4E9F-885B-C5C05B70C6D9@cox.net>
References: <62299.1230397039@uk2.net>
	<7D0818AF-8248-4E9F-885B-C5C05B70C6D9@cox.net>
Message-ID: <49566389.2080503@rubidium.dyndns.org>

Hi Tom,

Thomas A. Frank skrev:
>>> For me, PST, UTC midnight is 4 PM, a convenient time to watch.
>> For those of us in the zulu time zone (near the Greenwich  
>> meridian), happening
>> just as the new year is about to start is not *nearly* so  
>> convenient - especially
>> if you are trying to transmit new year celebration programmes, and  
>> praying the
>> equipment doesn't fall over!
>>
>> Peter
> 
> 
> No really, should you be more concerned with the equipment or the  
> operator falling over on New Years Eve?

If you where the operator in charge, would you like to be known as the 
drunk operator that screwed the transmission up?

If not, I think you know in what way you would have prepared yourself in 
concern with getting proper rest and staying sober.

Cheers,
Magnus


From hmurray at megapathdsl.net  Sat Dec 27 17:50:34 2008
From: hmurray at megapathdsl.net (Hal Murray)
Date: Sat, 27 Dec 2008 09:50:34 -0800
Subject: [time-nuts] Sub Pico Second Phase logger
In-Reply-To: Message from Joe Gwinn <joegwinn@comcast.net> of "Sat,
	27 Dec 2008 11:52:16 EST." <p06240817c57c0a3b261e@[192.168.1.212]>
Message-ID: <20081227175035.842E8BCD7@ip-64-139-1-69.sjc.megapath.net>

> What do you mean by "diplexer"?

It's one of those magic RF/Microwave boxes.
  http://en.wikipedia.org/wiki/Diplexor


-- 
These are my opinions, not necessarily my employer's.  I hate spam.





From timenuts at bobj.org  Sat Dec 27 20:13:14 2008
From: timenuts at bobj.org (Bob Johnson)
Date: Sat, 27 Dec 2008 14:13:14 -0600
Subject: [time-nuts] Leap-second happens when...??
In-Reply-To: <mailman.4.1230379202.5393.time-nuts@febo.com>
References: <mailman.4.1230379202.5393.time-nuts@febo.com>
Message-ID: <49568C5A.1050200@bobj.org>


Magnus Danielson <magnus at rubidium.dyndns.org> wrote
> Michael Baker skrev:
>> Hello, Time-Nutters--
>>
>> I must have missed something...  I have known about
>> the coming leap-second for months, but have not heard
>> when it was going to be inserted.
>> When will the leap-second take place?
> 
> A leap-second can be inserted or removed at the end of the last minute 
> of a month in UTC.

[...]

> You naturally need to convert to your local time zone to get a little 
> more aid on when it happens, but for Florida it will occur at 18:00 
> (UTC-6h) on Wednesday where as for me it will occur at 1:00 (UTC+1h) on 
> Thursday.

I think that's UTC-6h in northwest Florida (Central time zone), but 
UTC-5h in peninsular Florida where Mike is (Eastern time zone). Or else 
I'm confused. I grew up in one and live in the other, and between that 
and keeping track of summer and winter times, I don't always get it right...

But anyway, Mike, be at your clock, or GPS, or whatever, at 23:59:59Z on 
Dec 31. Don't forget your eggnog.

- Bob


From bruce.griffiths at xtra.co.nz  Sat Dec 27 20:29:49 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Sun, 28 Dec 2008 09:29:49 +1300
Subject: [time-nuts] Sub Pico Second Phase logger
In-Reply-To: <20081227175035.842E8BCD7@ip-64-139-1-69.sjc.megapath.net>
References: <20081227175035.842E8BCD7@ip-64-139-1-69.sjc.megapath.net>
Message-ID: <4956903D.5060801@xtra.co.nz>

Hal Murray wrote:
>> What do you mean by "diplexer"?
>>     
>
> It's one of those magic RF/Microwave boxes.
>   http://en.wikipedia.org/wiki/Diplexor
>
>
>   
No, in this context it usually means a circuit that terminates the mixer
port in 50 ohms for RF frequencies whilst maintaining a different
termination imedance for lower frequencies.

Bruce


From magnus at rubidium.dyndns.org  Sat Dec 27 20:56:17 2008
From: magnus at rubidium.dyndns.org (Magnus Danielson)
Date: Sat, 27 Dec 2008 21:56:17 +0100
Subject: [time-nuts] Leap-second happens when...??
In-Reply-To: <49568C5A.1050200@bobj.org>
References: <mailman.4.1230379202.5393.time-nuts@febo.com>
	<49568C5A.1050200@bobj.org>
Message-ID: <49569671.3000008@rubidium.dyndns.org>

Bob,

>> You naturally need to convert to your local time zone to get a little 
>> more aid on when it happens, but for Florida it will occur at 18:00 
>> (UTC-6h) on Wednesday where as for me it will occur at 1:00 (UTC+1h) on 
>> Thursday.
> 
> I think that's UTC-6h in northwest Florida (Central time zone), but 
> UTC-5h in peninsular Florida where Mike is (Eastern time zone). Or else 
> I'm confused. I grew up in one and live in the other, and between that 
> and keeping track of summer and winter times, I don't always get it right...
> 
> But anyway, Mike, be at your clock, or GPS, or whatever, at 23:59:59Z on 
> Dec 31. Don't forget your eggnog.

Thanks for correcting me. I was not quite sure and too lazy to check up 
the facts.

Cheers,
Magnus


From bruce.griffiths at xtra.co.nz  Sat Dec 27 21:20:10 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Sun, 28 Dec 2008 10:20:10 +1300
Subject: [time-nuts] Happy Holidays
In-Reply-To: <BLU125-W54E65F48D2AEBEA026580DCEE80@phx.gbl>
References: <mailman.786.1230340369.2499.time-nuts@febo.com>
	<BLU125-W54E65F48D2AEBEA026580DCEE80@phx.gbl>
Message-ID: <49569C0A.7030208@xtra.co.nz>

Mark Sims wrote:
> Another possible thing to try is one of the Miller integrator chips that Tektronix used in their scopes and time base modules.  I seem to remember that at least one could yield 0.01% linearity.  The 5Bxx and 7Bxx modules for the 5000 and 7000 series scopes are available in vast quantities,  often for less than $10 (plus about that in shipping).  There is also an Ebay seller that has one of the chips in lots of 10...  search for "Tektronix miller".   I don't know what unit those chips were from.  They are in a TO5 type can,  not the usual DIP package.  To use a particular chip  you would need to do some reverse engineering from the appropriate module service manual.  The connections are usually fairly simple.
>   
Mark

As far as I can tell from the 5B40 and 5B42 manuals its just a triggered
ramp generator with no provision for holding the ramp level in response
to an external signal.
Consequently it would only be useful in a TAC (time to amplitude
converter) if a sample and hold were used to sample the ramp at the
appropriate instant.
In principle one could use an ADC with a built in sample and hold that
has a sufficiently low acquisition time and low sampling jitter.
For modern sampling ADCs with no input buffer the RC sampling capacitor
charging time constant ensures that the voltage on the sampling cap is
merely delayed with respect to the input ramp voltage at the sampling
instant (provided that the ramp has been slewing for sufficient time for
the sampling capacitor ramp start transients to settle).

Bruce


From bruce.griffiths at xtra.co.nz  Sat Dec 27 22:55:43 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Sun, 28 Dec 2008 11:55:43 +1300
Subject: [time-nuts] Happy Holidays
In-Reply-To: <BLU125-W54E65F48D2AEBEA026580DCEE80@phx.gbl>
References: <mailman.786.1230340369.2499.time-nuts@febo.com>
	<BLU125-W54E65F48D2AEBEA026580DCEE80@phx.gbl>
Message-ID: <4956B26F.3090001@xtra.co.nz>

Mark Sims wrote:
> Another possible thing to try is one of the Miller integrator chips that Tektronix used in their scopes and time base modules.  I seem to remember that at least one could yield 0.01% linearity.  The 5Bxx and 7Bxx modules for the 5000 and 7000 series scopes are available in vast quantities,  often for less than $10 (plus about that in shipping).  There is also an Ebay seller that has one of the chips in lots of 10...  search for "Tektronix miller".   I don't know what unit those chips were from.  They are in a TO5 type can,  not the usual DIP package.  To use a particular chip  you would need to do some reverse engineering from the appropriate module service manual.  The connections are usually fairly simple.
> _________________________________________________________________
> It?s the same Hotmail?. If by ?same? you mean up to 70% faster.
> http://windowslive.com/online/hotmail?ocid=TXT_TAGLM_WL_hotmail_acq_broad1_122008
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>
>   
Yet another option is to use the simple TAC (figure 2) in:
http://n1.taur.dk/permanent/frequencymeasurement.pdf

The only drawback with this circuit is that the capacitor voltage at
reset isn't zero.
The capacitor reset voltage is also temperature dependent.
Since the change in the capacitor voltage is proportional to the
synchroniser delay, the solution to this is obvious:
Measure the capacitor reset voltage with the ADC and subtract it from
the capacitor voltage held on the capacitor after charging is terminated
by the STOP input.
Dedicated ACMOS (or equivalent low output impedance) flipflops can be
used to drive the diode switches directly.

Bruce



From bruce.griffiths at xtra.co.nz  Sat Dec 27 23:24:10 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Sun, 28 Dec 2008 12:24:10 +1300
Subject: [time-nuts] Happy Holidays
In-Reply-To: <4956B26F.3090001@xtra.co.nz>
References: <mailman.786.1230340369.2499.time-nuts@febo.com>	<BLU125-W54E65F48D2AEBEA026580DCEE80@phx.gbl>
	<4956B26F.3090001@xtra.co.nz>
Message-ID: <4956B91A.90106@xtra.co.nz>

Bruce Griffiths wrote:
> Mark Sims wrote:
>   
>> Another possible thing to try is one of the Miller integrator chips that Tektronix used in their scopes and time base modules.  I seem to remember that at least one could yield 0.01% linearity.  The 5Bxx and 7Bxx modules for the 5000 and 7000 series scopes are available in vast quantities,  often for less than $10 (plus about that in shipping).  There is also an Ebay seller that has one of the chips in lots of 10...  search for "Tektronix miller".   I don't know what unit those chips were from.  They are in a TO5 type can,  not the usual DIP package.  To use a particular chip  you would need to do some reverse engineering from the appropriate module service manual.  The connections are usually fairly simple.
>> _________________________________________________________________
>> It?s the same Hotmail?. If by ?same? you mean up to 70% faster.
>> http://windowslive.com/online/hotmail?ocid=TXT_TAGLM_WL_hotmail_acq_broad1_122008
>> _______________________________________________
>> time-nuts mailing list -- time-nuts at febo.com
>> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>> and follow the instructions there.
>>
>>   
>>     
> Yet another option is to use the simple TAC (figure 2) in:
> http://n1.taur.dk/permanent/frequencymeasurement.pdf
>
> The only drawback with this circuit is that the capacitor voltage at
> reset isn't zero.
> The capacitor reset voltage is also temperature dependent.
> Since the change in the capacitor voltage is proportional to the
> synchroniser delay, the solution to this is obvious:
> Measure the capacitor reset voltage with the ADC and subtract it from
> the capacitor voltage held on the capacitor after charging is terminated
> by the STOP input.
> Dedicated ACMOS (or equivalent low output impedance) flipflops can be
> used to drive the diode switches directly.
>
> Bruce
>
>
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>
>   
With a suitable charge redistribution ADC (one without resistive input
attenuators or an input buffer amplifier eg LTC1400, LTC1418 etc) the
buffer amplifier can be eliminated by connecting  the ADC input directly
to the ramp capacitor.

Bruce


From Tracy.Bales at Williams.com  Sat Dec 27 23:58:06 2008
From: Tracy.Bales at Williams.com (Bales, Tracy)
Date: Sat, 27 Dec 2008 17:58:06 -0600
Subject: [time-nuts] GPS and PLL's...
Message-ID: <80E5CB389E07E84E968B506911F9F1AD09BA29@wmstutmb03.WILLIAMS.COM>

I just started receiving the Time-Nuts emails...I admit that I've got a
lot of learning ahead of me.

 

I've got a Trimble GPS module that outputs a 10 uSec wide pulse every
second.  Now this is where I need some education...

 

How would you use the 1 PPS output to steer a phase locked loop running
at 10MHZ?  Are you dividing the 10MHZ clock by 10 million?

 

If you are dividing by 10 million, wouldn't it take forever for the PLL
to lock?

 

See, I gave everyone warning about my learning curve!!!  Thanks...


From stijena at tapko.de  Sun Dec 28 00:21:26 2008
From: stijena at tapko.de (Predrag Dukic)
Date: Sun, 28 Dec 2008 01:21:26 +0100
Subject: [time-nuts] DMTD mixer question
In-Reply-To: <osibl4h7irfumc5e08aioudu86i8fv06o4@4ax.com>
References: <2ae26e4e0812030750i1e8b0af4x4e99ccafcfcf7812@mail.gmail.com>
	<4936D8D7.70204@xtra.co.nz>
	<ECE7A93BD093E1439C20020FBE87C47FEB55DA84B2@ALTPHYEMBEVSP20.RES.AD.JPL>
	<4936E5B0.2070201@xtra.co.nz>
	<2ae26e4e0812031548te0e935awcd007815ccc490a4@mail.gmail.com>
	<49372FF1.5020608@xtra.co.nz>
	<2ae26e4e0812050357l2bfc5ae0ubbeda1299004aee6@mail.gmail.com>
	<493932A8.5030001@xtra.co.nz>
	<osibl4h7irfumc5e08aioudu86i8fv06o4@4ax.com>
Message-ID: <7.0.1.0.1.20081228011646.00a2fc00@tapko.de>


Matt,

No, Webpack is not time limited.   Only the feature set is a bit 
limited (no specialized libraries and addons).

There is also a limitation concerning gate count, but I think 
Spartan3e with  500 kgates will pass.

I have full set (academic license)  and the board, in case You 
stumble on any limitation.


Predrag






At 07:33 27.12.2008, you wrote:
>On Sat, 06 Dec 2008 02:54:48 +1300, Bruce Griffiths
><bruce.griffiths at xtra.co.nz> wrote:
>
> >At least a couple of us have the Spartan 3E board.
>
>Is the ISE evaluation software time limited?
>
>-- kc0ukk at msosborn dot com
>
>_______________________________________________
>time-nuts mailing list -- time-nuts at febo.com
>To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>and follow the instructions there.



From bruce.griffiths at xtra.co.nz  Sun Dec 28 00:17:15 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Sun, 28 Dec 2008 13:17:15 +1300
Subject: [time-nuts] GPS and PLL's...
In-Reply-To: <80E5CB389E07E84E968B506911F9F1AD09BA29@wmstutmb03.WILLIAMS.COM>
References: <80E5CB389E07E84E968B506911F9F1AD09BA29@wmstutmb03.WILLIAMS.COM>
Message-ID: <4956C58B.5030908@xtra.co.nz>

Bales, Tracy wrote:
> I just started receiving the Time-Nuts emails...I admit that I've got a
> lot of learning ahead of me.
>
>  
>
> I've got a Trimble GPS module that outputs a 10 uSec wide pulse every
> second.  Now this is where I need some education...
>
>  
>
> How would you use the 1 PPS output to steer a phase locked loop running
> at 10MHZ?  Are you dividing the 10MHZ clock by 10 million?
>
>  
>
> If you are dividing by 10 million, wouldn't it take forever for the PLL
> to lock?
>
>  
>
> See, I gave everyone warning about my learning curve!!!  Thanks...
>
>   
Tracy

If one only has the PPS output from the receiver, then indeed this is
all you can use to discipline the 10MHz oscillator.
A PLL is generally used for this, and yes the time to lock can be
relatively long.
The lock time is governed by the PLL dynamics (principally the loop time
constant).
Typical loop time constants can range from 100 sec to 1000 sec or more
for a good OCXO.

Whilst one can divide the 10MHz down to 1Hz, this isn't necessary.
All one really needs is a phase detector with a range somewhat greater
than the timing noise in the GPS receivers PPS output.
For example one can use the 10MHz signal directly and measure the time
delay from the leading edge of the PPS pulse to the next positive slope
zero crossing of the 10MHz signal.
This will suffice if the PPS timing noise is somewhat less than about
50ns or so.
However if the EFC tuning range of the OCXO is too great the OCXO could
lock to a frequency like 10MHz + N Hz where N is a small integer with a
range of say (-10, +10) - includes 0.
To avoid this its usually better to divide the OCXO frequency down to
1MHz or so and measure the time delay from the leading edge of the PPS
pulse to the next positive slope threshold crossing of the 1MHz signal.
The possible frequencies that the 10MHz oscillator can lock to are then
10MHz + 10*N Hz. The EFC range will likely only allow locking to 10MHz,
if not divide down to  a lower frequency such as 250kHz, 100kHz etc.

Various techniques (analog and/or digital) of varying complexity can be
used to measure this time delay.


Bruce


From magnus at rubidium.dyndns.org  Sun Dec 28 00:17:11 2008
From: magnus at rubidium.dyndns.org (Magnus Danielson)
Date: Sun, 28 Dec 2008 01:17:11 +0100
Subject: [time-nuts] GPS and PLL's...
In-Reply-To: <80E5CB389E07E84E968B506911F9F1AD09BA29@wmstutmb03.WILLIAMS.COM>
References: <80E5CB389E07E84E968B506911F9F1AD09BA29@wmstutmb03.WILLIAMS.COM>
Message-ID: <4956C587.5030209@rubidium.dyndns.org>

Bales, Tracy skrev:
> I just started receiving the Time-Nuts emails...I admit that I've got a
> lot of learning ahead of me.
> 
> I've got a Trimble GPS module that outputs a 10 uSec wide pulse every
> second.  Now this is where I need some education...
> 
> How would you use the 1 PPS output to steer a phase locked loop running
> at 10MHZ?  Are you dividing the 10MHZ clock by 10 million?

That is usually what is done.

> If you are dividing by 10 million, wouldn't it take forever for the PLL
> to lock?

No, you get a fairly good idea about the initial frequency error in just 
the first seconds, using a PI-regulator is usually done. You can 
bootstrap it for a quicker lockup by raw-adjusting phase and possibly 
also frequency.

> See, I gave everyone warning about my learning curve!!!  Thanks...

Many of your fellow new friends here have been there, so no big worries.

If you look in the archives you will find this issue discussed over and 
over. You will also find links to several sites, include TvB. Do follow 
up on those links as there is usually lot of good info nearby.

Cheers,
Magnus


From kc0ukk at msosborn.com  Sun Dec 28 00:57:47 2008
From: kc0ukk at msosborn.com (Matt Osborn)
Date: Sat, 27 Dec 2008 18:57:47 -0600
Subject: [time-nuts] DMTD mixer question
In-Reply-To: <20081227073803.B1D41BCD7@ip-64-139-1-69.sjc.megapath.net>
References: <hmurray@megapathdsl.net> of "Fri, 26 Dec 2008 22:53:54 PST."
	<20081227065355.89DC9BCD7@ip-64-139-1-69.sjc.megapath.net>
	<20081227073803.B1D41BCD7@ip-64-139-1-69.sjc.megapath.net>
Message-ID: <lkjdl41juefnq3ij3ppf7f9iii2j20jdfs@4ax.com>

Thanks for the info.  I saw the development system for $149 and
thought the exposure would be worth the price if the exposure lasted
more than 60 days.  Webpack sounds as if it will do the job.


On Fri, 26 Dec 2008 23:38:02 -0800, Hal Murray
<hmurray at megapathdsl.net> wrote:

>Webpack is good enough to get a lot of work done.  You might want some of the 
>fancier features.  You probably don't want to pay for ISE if all you are 
>doing is hobby stuff.

-- kc0ukk at msosborn dot com


From imp at bsdimp.com  Sun Dec 28 00:56:54 2008
From: imp at bsdimp.com (M. Warner Losh)
Date: Sat, 27 Dec 2008 17:56:54 -0700 (MST)
Subject: [time-nuts] Leap-second happens when...??
In-Reply-To: <4955F456.8000800@rubidium.dyndns.org>
References: <4955649B.3070107@clanbaker.org>
	<4955F456.8000800@rubidium.dyndns.org>
Message-ID: <20081227.175654.1474622066.imp@bsdimp.com>

In message: <4955F456.8000800 at rubidium.dyndns.org>
            Magnus Danielson <magnus at rubidium.dyndns.org> writes:
: Michael Baker skrev:
: > Hello, Time-Nutters--
: > 
: > I must have missed something...  I have known about
: > the coming leap-second for months, but have not heard
: > when it was going to be inserted. 
: > 
: > When will the leap-second take place?
: 
: A leap-second can be inserted or removed at the end of the last minute 
: of a month in UTC.
: 
: Normal transition:
: 23:59:58
: 23:59:59
: 00:00:00
: 
: Adding a leap second:
: 23:59:58
: 23:59:59
: 23:59:60
: 00:00:00
: 
: Removing a leap second:
: 23:59:58
: 00:00:00
: 
: The first preference on which month to insert them is first to the June 
: and December.
: 
: The second preference is on Mars and September.

I assume you mean 'May' here.  The standard additionally allows for
leap seconds at the end of any month.  However, there's a lot of
software out there that will be dodgy for the Secondary times, and not
work at all for the others.

: You naturally need to convert to your local time zone to get a little 
: more aid on when it happens, but for Florida it will occur at 18:00 
: (UTC-6h) on Wednesday where as for me it will occur at 1:00 (UTC+1h) on 
: Thursday.
: 
: > Will it hurt?
: 
: No.
: 
: > Am I going to need a band-aid?
: 
: No.
: 
: > Or just another rum-laced egg-nog...??
: 
: Yes. Sounds like a good idea. But don't drink it all during the 
: leap-second, that would be a waste of perfectly good egg-nog.
: 
: Cheers,
: Magnus
: 
: _______________________________________________
: time-nuts mailing list -- time-nuts at febo.com
: To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
: and follow the instructions there.
: 
: 


From time-nuts at kasperkp.dk  Sun Dec 28 01:15:07 2008
From: time-nuts at kasperkp.dk (Kasper Pedersen)
Date: Sun, 28 Dec 2008 02:15:07 +0100
Subject: [time-nuts] Happy Holidays
In-Reply-To: <4956B26F.3090001@xtra.co.nz>
References: <mailman.786.1230340369.2499.time-nuts@febo.com>	<BLU125-W54E65F48D2AEBEA026580DCEE80@phx.gbl>
	<4956B26F.3090001@xtra.co.nz>
Message-ID: <4956D31B.8040809@kasperkp.dk>

Bruce Griffiths wrote:
> Yet another option is to use the simple TAC (figure 2) in:
> http://n1.taur.dk/permanent/frequencymeasurement.pdf
>
> The only drawback with this circuit is that the capacitor voltage at
> reset isn't zero.
> The capacitor reset voltage is also temperature dependent.
> Since the change in the capacitor voltage is proportional to the
> synchroniser delay, the solution to this is obvious:
> Measure the capacitor reset voltage with the ADC and subtract it from
> the capacitor voltage held on the capacitor after charging is terminated
> by the STOP input.
> Dedicated ACMOS (or equivalent low output impedance) flipflops can be
> used to drive the diode switches directly.
>   
The drawback turned out to be a useful feature.

For one, the TLC072 opamp I used does not swing below V-+0.5V, and I had 
no negative supply. Also, the 0.8V reset keeps me out of the worst 
varactor-behaviour of the opamp's clamp diodes, and ditto the 'i' diode, 
which would have caused some nonlinearity for short pulses. Finally, the 
leakage of 'i' in hold has less variation over 0.8V-2.5V (1nA) than 
0.0V-2.0V (5nA), http://n1.taur.dk/permanent/1n4148.png , which in turn 
means that the delay from the stop to the adc s/h closes doesn't 
introduce as much nonlinearity, as long as it is constant.

The way I do the subtraction is to measure the reset voltage after the 
start-stop-convert-reset sequence (one could possibly misread your 
description as suggesting converting the reset voltage first) and before 
rearming - that way drift doesn't creep in while waiting for the edge.

The charge redistribution adc would have been good, true, but there 
wasn't one in my junkbox.

/Kasper Pedersen


From magnus at rubidium.dyndns.org  Sun Dec 28 01:17:12 2008
From: magnus at rubidium.dyndns.org (Magnus Danielson)
Date: Sun, 28 Dec 2008 02:17:12 +0100
Subject: [time-nuts] Leap-second happens when...??
In-Reply-To: <20081227.175654.1474622066.imp@bsdimp.com>
References: <4955649B.3070107@clanbaker.org>	<4955F456.8000800@rubidium.dyndns.org>
	<20081227.175654.1474622066.imp@bsdimp.com>
Message-ID: <4956D398.6060401@rubidium.dyndns.org>


> : The first preference on which month to insert them is first to the June 
> : and December.
> : 
> : The second preference is on Mars and September.
> 
> I assume you mean 'May' here.

No. Read on. (spelt March incorrectly. sorry)

>  The standard additionally allows for
> leap seconds at the end of any month.  However, there's a lot of
> software out there that will be dodgy for the Secondary times, and not
> work at all for the others.

TF.460-4 says:

"A positive or negative leap-second should be the last second of a UTC 
month, but first preference should be given to the end of December and 
June, and second preference to the end of March and September."

There is an incorrect interpretation that only December and June are 
allowed. Another incorrect interpretation is that only March, June, 
September and December is allowed. Each month is allowed. There is only 
a preference towards the others. The flagging of upcoming leap second 
occuring in December already in July is ambiguous. Ah well.

Anyway, the TF.460-4 is very clear on it. May is allowed, but not preferred.

Cheers,
Magnus


From jmiles at pop.net  Sun Dec 28 01:15:37 2008
From: jmiles at pop.net (John Miles)
Date: Sat, 27 Dec 2008 17:15:37 -0800
Subject: [time-nuts] DMTD mixer question
In-Reply-To: <lkjdl41juefnq3ij3ppf7f9iii2j20jdfs@4ax.com>
Message-ID: <PKEGJHPHLLBACEOICCBJOELJAAAC.jmiles@pop.net>

Even though the ISE/Webpack toolchain is considered somewhat buggier and
less-capable than the competing Altera freeware, I prefer it because the
Altera package requires product activation.  Call it paranoia on my part,
but I see a lot of HPSDR experimenters who are going to be unhappy campers
when (not if) Altera decides to stop supporting their toolchain.

-- john, KE5FX


> Thanks for the info.  I saw the development system for $149 and
> thought the exposure would be worth the price if the exposure lasted
> more than 60 days.  Webpack sounds as if it will do the job.
>
>
> On Fri, 26 Dec 2008 23:38:02 -0800, Hal Murray
> <hmurray at megapathdsl.net> wrote:
>
> >Webpack is good enough to get a lot of work done.  You might
> want some of the
> >fancier features.  You probably don't want to pay for ISE if all you are
> >doing is hobby stuff.
>
> -- kc0ukk at msosborn dot com
>



From n3toy at yahoo.com  Sun Dec 28 02:26:26 2008
From: n3toy at yahoo.com (James R. Gorr)
Date: Sat, 27 Dec 2008 18:26:26 -0800 (PST)
Subject: [time-nuts] altitude difference between two gps
Message-ID: <264215.54635.qm@web54106.mail.re2.yahoo.com>

Hello everyone!

I have a tbolt that I am monitoring with tboltmon.exe and some off-brand 12 channel GPS (I bought from Sure Electronics on eBay) that I am monitoring with VisualGPS.  Both are fed from the same GPS antenna through a symmetricom splitter.  There is a 30 meter difference in the altitude readings between the two.  My tbolt says my altitude (after a self-survey) is ~761 meters and the 12 channel Sure Electronics GPS says my altitude is ~791 meters after 7,500+ readings.  I took my hand held Garmin 12XL outside and it says my altitude is ~790 meters at street level.

Anyone have an idea why my tbolt might be reading different from the other two devices?  I am assuming the tbolt is reading low. 

Jamie


      


From w1ksz at earthlink.net  Sun Dec 28 03:24:57 2008
From: w1ksz at earthlink.net (Richard W. Solomon)
Date: Sat, 27 Dec 2008 22:24:57 -0500 (EST)
Subject: [time-nuts] altitude difference between two gps
Message-ID: <7611216.1230434697732.JavaMail.root@elwamui-hound.atl.sa.earthlink.net>

-800 meters ??
Live in a mine ??
How can that be ?

73, Dick, W1KSZ

-----Original Message-----
>From: "James R. Gorr" <n3toy at yahoo.com>
>Sent: Dec 27, 2008 9:26 PM
>To: time-nuts at febo.com
>Subject: [time-nuts] altitude difference between two gps
>
>Hello everyone!
>
>I have a tbolt that I am monitoring with tboltmon.exe and some off-brand 12 channel GPS (I bought from Sure Electronics on eBay) that I am monitoring with VisualGPS.  Both are fed from the same GPS antenna through a symmetricom splitter.  There is a 30 meter difference in the altitude readings between the two.  My tbolt says my altitude (after a self-survey) is ~761 meters and the 12 channel Sure Electronics GPS says my altitude is ~791 meters after 7,500+ readings.  I took my hand held Garmin 12XL outside and it says my altitude is ~790 meters at street level.
>
>Anyone have an idea why my tbolt might be reading different from the other two devices?  I am assuming the tbolt is reading low. 
>
>Jamie
>
>
>      
>
>_______________________________________________
>time-nuts mailing list -- time-nuts at febo.com
>To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>and follow the instructions there.



From chris.kuethe at gmail.com  Sun Dec 28 03:45:15 2008
From: chris.kuethe at gmail.com (Chris Kuethe)
Date: Sat, 27 Dec 2008 19:45:15 -0800
Subject: [time-nuts] altitude difference between two gps
In-Reply-To: <7611216.1230434697732.JavaMail.root@elwamui-hound.atl.sa.earthlink.net>
References: <7611216.1230434697732.JavaMail.root@elwamui-hound.atl.sa.earthlink.net>
Message-ID: <91981b3e0812271945k74262f0amae606ad41bb3899@mail.gmail.com>

On Sat, Dec 27, 2008 at 7:24 PM, Richard W. Solomon <w1ksz at earthlink.net> wrote:
> -800 meters ??
> Live in a mine ??
> How can that be ?

He's using the "~" to mean approximately.

As for the height difference, perhaps one receiver is using elipsoid
and the other is using MSL altitude?

CK

-- 
GDB has a 'break' feature; why doesn't it have 'fix' too?


From n3toy at yahoo.com  Sun Dec 28 03:46:41 2008
From: n3toy at yahoo.com (James R. Gorr)
Date: Sat, 27 Dec 2008 19:46:41 -0800 (PST)
Subject: [time-nuts] altitude difference between two gps
Message-ID: <729608.49521.qm@web54109.mail.re2.yahoo.com>


Yes.  The pending leap second has me very scared.  It is the Y2k bug of 2008.  :-)

Sorry, that is a tilde, not a negative sign.  Meant as "approximately" 791 meters, although I may be using it completely wrong.  The real value (mean average) is 790.83 meters for the Sure Electronics GPS.

Sorry for the confusion.  

--- On Sat, 12/27/08, Richard W. Solomon <w1ksz at earthlink.net> wrote:

From: Richard W. Solomon <w1ksz at earthlink.net>
Subject: Re: [time-nuts] altitude difference between two gps
To: "Discussion of precise time and frequency measurement" <time-nuts at febo.com>
Date: Saturday, December 27, 2008, 7:24 PM

-800 meters ??
Live in a mine ??
How can that be ?

73, Dick, W1KSZ

-----Original Message-----
>From: "James R. Gorr" <n3toy at yahoo.com>
>Sent: Dec 27, 2008 9:26 PM
>To: time-nuts at febo.com
>Subject: [time-nuts] altitude difference between two gps
>
>Hello everyone!
>
>I have a tbolt that I am monitoring with tboltmon.exe and some off-brand 12 channel GPS (I bought from Sure Electronics on eBay) that I am monitoring with VisualGPS.? Both are fed from the same GPS antenna through a symmetricom splitter.? There is a 30 meter difference in the altitude readings between the two.? My tbolt says my altitude (after a self-survey) is ~761 meters and the 12 channel Sure Electronics GPS says my altitude is ~791 meters after 7,500+ readings.? I took my hand held Garmin 12XL outside and it says my altitude is ~790 meters at street level.
>
>Anyone have an idea why my tbolt might be reading different from the other two devices?? I am assuming the tbolt is reading low. 
>
>Jamie
>
>
>? ? ? 
>
>_______________________________________________
>time-nuts mailing list -- time-nuts at febo.com
>To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>and follow the instructions there.


_______________________________________________
time-nuts mailing list -- time-nuts at febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.



      


From normn3ykf at stny.rr.com  Sun Dec 28 03:56:52 2008
From: normn3ykf at stny.rr.com (Norman J McSweyn)
Date: Sat, 27 Dec 2008 22:56:52 -0500
Subject: [time-nuts] altitude difference between two gps
In-Reply-To: <729608.49521.qm@web54109.mail.re2.yahoo.com>
References: <729608.49521.qm@web54109.mail.re2.yahoo.com>
Message-ID: <4956F904.8040309@stny.rr.com>

James R. Gorr wrote:
> Yes.  The pending leap second has me very scared.  It is the Y2k bug of 2008.  :-)
> 
> Sorry, that is a tilde, not a negative sign.  Meant as "approximately" 791 meters, although I may be using it completely wrong.  The real value (mean average) is 790.83 meters for the Sure Electronics GPS.
> 
> Sorry for the confusion.  
> 
> --- On Sat, 12/27/08, Richard W. Solomon <w1ksz at earthlink.net> wrote:
> 
> From: Richard W. Solomon <w1ksz at earthlink.net>
> Subject: Re: [time-nuts] altitude difference between two gps
> To: "Discussion of precise time and frequency measurement" <time-nuts at febo.com>
> Date: Saturday, December 27, 2008, 7:24 PM
> 
> -800 meters ??
> Live in a mine ??
> How can that be ?
> 
> 73, Dick, W1KSZ
> 
> -----Original Message-----
>> From: "James R. Gorr" <n3toy at yahoo.com>
>> Sent: Dec 27, 2008 9:26 PM
>> To: time-nuts at febo.com
>> Subject: [time-nuts] altitude difference between two gps
>>
>> Hello everyone!
>>
>> I have a tbolt that I am monitoring with tboltmon.exe and some off-brand 12 channel GPS (I bought from Sure Electronics on eBay) that I am monitoring with VisualGPS.  Both are fed from the same GPS antenna through a symmetricom splitter.  There is a 30 meter difference in the altitude readings between the two.  My tbolt says my altitude (after a self-survey) is ~761 meters and the 12 channel Sure Electronics GPS says my altitude is ~791 meters after 7,500+ readings.  I took my hand held Garmin 12XL outside and it says my altitude is ~790 meters at street level.
>>
>> Anyone have an idea why my tbolt might be reading different from the other two devices?  I am assuming the tbolt is reading low. 
>>
>> Jamie
>>
>>
>>       
>>
>> _______________________________________________
>> time-nuts mailing list -- time-nuts at febo.com
>> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>> and follow the instructions there.
> 
> 
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
> 
> 
> 
>       
> 
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
> 
My m12+t and Thunderbolt were doing the same thing (non agreement in 
height). They do share the same antenna. By setting the antenna mask 
angle to the same value on both gps units, the difference was less than 
one meter.
Norm n3ykf


From imp at bsdimp.com  Sun Dec 28 04:07:27 2008
From: imp at bsdimp.com (M. Warner Losh)
Date: Sat, 27 Dec 2008 21:07:27 -0700 (MST)
Subject: [time-nuts] Leap-second happens when...??
In-Reply-To: <4956D398.6060401@rubidium.dyndns.org>
References: <4955F456.8000800@rubidium.dyndns.org>
	<20081227.175654.1474622066.imp@bsdimp.com>
	<4956D398.6060401@rubidium.dyndns.org>
Message-ID: <20081227.210727.-1980909570.imp@bsdimp.com>

In message: <4956D398.6060401 at rubidium.dyndns.org>
            Magnus Danielson <magnus at rubidium.dyndns.org> writes:
: 
: > : The first preference on which month to insert them is first to the June 
: > : and December.
: > : 
: > : The second preference is on Mars and September.
: > 
: > I assume you mean 'May' here.
: 
: No. Read on. (spelt March incorrectly. sorry)
: 
: >  The standard additionally allows for
: > leap seconds at the end of any month.  However, there's a lot of
: > software out there that will be dodgy for the Secondary times, and not
: > work at all for the others.
: 
: TF.460-4 says:
: 
: "A positive or negative leap-second should be the last second of a UTC 
: month, but first preference should be given to the end of December and 
: June, and second preference to the end of March and September."
: 
: There is an incorrect interpretation that only December and June are 
: allowed. Another incorrect interpretation is that only March, June, 
: September and December is allowed. Each month is allowed. There is only 
: a preference towards the others. The flagging of upcoming leap second 
: occuring in December already in July is ambiguous. Ah well.
: 
: Anyway, the TF.460-4 is very clear on it. May is allowed, but not preferred.

Yes.  But there's very little software that actually implements the
secondary months, let alone the others.  There's been cases where the
GPS constellation turned on leap indicator before the end of September
and the HP Oscilloquartz GPSDO clocks glitched at the end of September
due to a bug in the firmware...

Warner


From k1ggi at arrl.net  Sun Dec 28 07:12:50 2008
From: k1ggi at arrl.net (Ed, k1ggi)
Date: Sun, 28 Dec 2008 02:12:50 -0500
Subject: [time-nuts] altitude difference between two gps
In-Reply-To: <264215.54635.qm@web54106.mail.re2.yahoo.com>
References: <264215.54635.qm@web54106.mail.re2.yahoo.com>
Message-ID: <057901c968bb$b71a3190$0a01a8c0@ATHLONXP1700>

On the thunderbolt, what datum do you have selected in Setup > Packet Masks
and Options? If it is 0 (WGS-84), try 2 (NAD-27).
-30m is about right for the geoid height around Las Vegas.
Ed, k1ggi

-----Original Message-----
From: James R. Gorr [mailto:n3toy at yahoo.com] 
Sent: Saturday, December 27, 2008 9:26 PM
To: time-nuts at febo.com
Subject: [time-nuts] altitude difference between two gps

Hello everyone!

I have a tbolt that I am monitoring with tboltmon.exe and some off-brand 12
channel GPS (I bought from Sure Electronics on eBay) that I am monitoring
with VisualGPS.  Both are fed from the same GPS antenna through a
symmetricom splitter.  There is a 30 meter difference in the altitude
readings between the two.  My tbolt says my altitude (after a self-survey)
is ~761 meters and the 12 channel Sure Electronics GPS says my altitude is
~791 meters after 7,500+ readings.  I took my hand held Garmin 12XL outside
and it says my altitude is ~790 meters at street level.

Anyone have an idea why my tbolt might be reading different from the other
two devices?  I am assuming the tbolt is reading low. 

Jamie


      

_______________________________________________
time-nuts mailing list -- time-nuts at febo.com
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.




From phk at phk.freebsd.dk  Sun Dec 28 08:26:55 2008
From: phk at phk.freebsd.dk (Poul-Henning Kamp)
Date: Sun, 28 Dec 2008 08:26:55 +0000
Subject: [time-nuts] Happy Holidays
In-Reply-To: Your message of "Sun, 28 Dec 2008 02:15:07 +0100."
	<4956D31B.8040809@kasperkp.dk> 
Message-ID: <32846.1230452815@critter.freebsd.dk>

In message <4956D31B.8040809 at kasperkp.dk>, Kasper Pedersen writes:
>Bruce Griffiths wrote:

>The charge redistribution adc would have been good, true, but there 
>wasn't one in my junkbox.

I'm pretty sure the ADC in most, if not all, micrcontrollers are
charge redistribution types.

-- 
Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk at FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.


From bruce.griffiths at xtra.co.nz  Sun Dec 28 09:07:21 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Sun, 28 Dec 2008 22:07:21 +1300
Subject: [time-nuts] Happy Holidays
In-Reply-To: <32846.1230452815@critter.freebsd.dk>
References: <32846.1230452815@critter.freebsd.dk>
Message-ID: <495741C9.7040709@xtra.co.nz>

Poul-Henning Kamp wrote:
> In message <4956D31B.8040809 at kasperkp.dk>, Kasper Pedersen writes:
>   
>> Bruce Griffiths wrote:
>>     
>
>   
>> The charge redistribution adc would have been good, true, but there 
>> wasn't one in my junkbox.
>>     
>
> I'm pretty sure the ADC in most, if not all, micrcontrollers are
> charge redistribution types.
>
>   
That is true for both the Microchip PIC16F917/6/4/3 series and the
ATMega128 (however the low bandwidth internal amplifier should not be
used for this application).


Bruce


From rk at timing-consultants.com  Sun Dec 28 13:24:39 2008
From: rk at timing-consultants.com (Rob Kimberley)
Date: Sun, 28 Dec 2008 13:24:39 -0000
Subject: [time-nuts] Downsizing - manuals available for UK collection only
Message-ID: <6F871448C3894CBCBC99B6A5DA4233D6@Robin>

I'm currently having a clearout of my stuff.

Several boxes of manuals available free to anyone willing to collect.

Austron, Datum, Efratom, Systron Donner.

Would like them to stay in the Time Nuts fraternity rather than dump them,
as I'm stuck for space where I'm moving.

Please contact me off list if you are interested in collection only -
Nuneaton, Warwickshire.

Cheers

Rob Kimberley



From bruce.griffiths at xtra.co.nz  Sun Dec 28 20:24:36 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Mon, 29 Dec 2008 09:24:36 +1300
Subject: [time-nuts] Happy Holidays
In-Reply-To: <495741C9.7040709@xtra.co.nz>
References: <32846.1230452815@critter.freebsd.dk> <495741C9.7040709@xtra.co.nz>
Message-ID: <4957E084.7070605@xtra.co.nz>

Bruce Griffiths wrote:
> Poul-Henning Kamp wrote:
>   
>> In message <4956D31B.8040809 at kasperkp.dk>, Kasper Pedersen writes:
>>   
>>     
>>> Bruce Griffiths wrote:
>>>     
>>>       
>>   
>>     
>>> The charge redistribution adc would have been good, true, but there 
>>> wasn't one in my junkbox.
>>>     
>>>       
>> I'm pretty sure the ADC in most, if not all, micrcontrollers are
>> charge redistribution types.
>>
>>   
>>     
> That is true for both the Microchip PIC16F917/6/4/3 series and the
> ATMega128 (however the low bandwidth internal amplifier should not be
> used for this application).
>
>
> Bruce
>
>   
The PIC16F688 used by Richard also has a charge redistribution ADC.
Consequently an external buffer amplifier is probably not necessary.
However a delay of about 5us after the termination of the interpolator
ramp is necessary to allow the charge on the ADC sampling capacitance
and the ADC internal amplifier to settle before beginning the ADC
conversion cycle.
When using the built in multiplexer to switch between analog inputs some
charge injection effects will occur.
A dedicated charge redistribution ADC per interpolator is preferable
especially if very high resolution is required.

The PIC16F688 ADC input pin leakage current is specified at 500nA,
however this may be due more to test time limitations than the actual
leakage.
The actual leakage current of the ADC input pin can be readily measured
by using a DVM to measure the voltage drop across a series resistor in
series with the analog input.

If the ramp capacitor charging current is sufficiently high the effect
of such leakage will be small.

Bruce


From john at pcsupportsolutions.com  Sun Dec 28 21:02:58 2008
From: john at pcsupportsolutions.com (John Allen)
Date: Sun, 28 Dec 2008 16:02:58 -0500
Subject: [time-nuts] Trimble NTPX26AB-06 Software?
Message-ID: <F8AAAE39FF1E4AF2B3D14F699C88AC6E@JAOpti755>

Hi - Does anyone have software for the Trimble NTPX26AB-06 GPSDO that is
similar to the Z3801?

 

Thanks!

 

John Allen K1AE

 


From bill at iaxs.net  Sun Dec 28 22:41:29 2008
From: bill at iaxs.net (Bill Hawkins)
Date: Sun, 28 Dec 2008 16:41:29 -0600
Subject: [time-nuts] Happy Holidays
In-Reply-To: <4957E084.7070605@xtra.co.nz>
References: <32846.1230452815@critter.freebsd.dk>
	<495741C9.7040709@xtra.co.nz> <4957E084.7070605@xtra.co.nz>
Message-ID: <398B0DB14898401995AF3E4C99F24AF2@cyrus>

Bruce Griffiths wrote:
> Poul-Henning Kamp wrote:
>> In message <4956D31B.8040809 at kasperkp.dk>, Kasper Pedersen writes:
>>     
>>> Bruce Griffiths wrote:
>>> The charge redistribution adc would have been good, true, but there 
>>> wasn't one in my junkbox.

If it wouldn't be too much trouble, could you change the Subject line?
This is not about happy days at all.

Bill Hawkins



From bruce.griffiths at xtra.co.nz  Sun Dec 28 23:24:45 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Mon, 29 Dec 2008 12:24:45 +1300
Subject: [time-nuts] Simple Time to Amplitude Converter
In-Reply-To: <398B0DB14898401995AF3E4C99F24AF2@cyrus>
References: <32846.1230452815@critter.freebsd.dk>	<495741C9.7040709@xtra.co.nz>
	<4957E084.7070605@xtra.co.nz>
	<398B0DB14898401995AF3E4C99F24AF2@cyrus>
Message-ID: <49580ABD.5000100@xtra.co.nz>

Bill Hawkins wrote:
> Bruce Griffiths wrote:
>   
>> Poul-Henning Kamp wrote:
>>     
>>> In message <4956D31B.8040809 at kasperkp.dk>, Kasper Pedersen writes:
>>>     
>>>       
>>>> Bruce Griffiths wrote:
>>>> The charge redistribution adc would have been good, true, but there 
>>>> wasn't one in my junkbox.
>>>>         
>
> If it wouldn't be too much trouble, could you change the Subject line?
> This is not about happy days at all.
>
> Bill Hawkins
>
>
>   
To account for charge injection effects from the ADC multiplexer and the
residual voltage on the ADC sampling capacitor as well as the inevitable
gain mismatch between the 2 channels a more comprehensive model of the
TAC's + ADC will be required. To a first order approximation such
effects will be small and linear a model something like

t2-t1 = G*(V2-V1) + e*V1 may suffice.

Where
V2 is the voltage across the second TAC ramp cap as measured by the ADC
V1 is the voltage across the second TAC ramp cap as measured by the ADC


This equation will need to be elaborated slightly when the initial
voltages across the TAC capacitors (during reset) are also measured.
The exact form of the correction will depend on the order in which the
voltage measurements are made.

Ideally the 2 synchroniser circuits would be include the capability of
producing calibration signals of known duration to facilitate
calibration of the gains of the 2 TACs whenever required.


Bruce


From bruce.griffiths at xtra.co.nz  Sun Dec 28 23:30:26 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Mon, 29 Dec 2008 12:30:26 +1300
Subject: [time-nuts] Simple Time to Amplitude Converter
In-Reply-To: <49580ABD.5000100@xtra.co.nz>
References: <32846.1230452815@critter.freebsd.dk>	<495741C9.7040709@xtra.co.nz>	<4957E084.7070605@xtra.co.nz>	<398B0DB14898401995AF3E4C99F24AF2@cyrus>
	<49580ABD.5000100@xtra.co.nz>
Message-ID: <49580C12.40600@xtra.co.nz>

Bruce Griffiths wrote:
> Bill Hawkins wrote:
>   
>> Bruce Griffiths wrote:
>>   
>>     
>>> Poul-Henning Kamp wrote:
>>>     
>>>       
>>>> In message <4956D31B.8040809 at kasperkp.dk>, Kasper Pedersen writes:
>>>>     
>>>>       
>>>>         
>>>>> Bruce Griffiths wrote:
>>>>> The charge redistribution adc would have been good, true, but there 
>>>>> wasn't one in my junkbox.
>>>>>         
>>>>>           
>> If it wouldn't be too much trouble, could you change the Subject line?
>> This is not about happy days at all.
>>
>> Bill Hawkins
>>
>>
>>   
>>     
> To account for charge injection effects from the ADC multiplexer and the
> residual voltage on the ADC sampling capacitor as well as the inevitable
> gain mismatch between the 2 channels a more comprehensive model of the
> TAC's + ADC will be required. To a first order approximation such
> effects will be small and linear a model something like
>
> t2-t1 = G*(V2-V1) + e*V1 may suffice.
>
> Where
> V2 is the voltage across the second TAC ramp cap as measured by the ADC
> V1 is the voltage across the second TAC ramp cap as measured by the ADC
>
>
> This equation will need to be elaborated slightly when the initial
> voltages across the TAC capacitors (during reset) are also measured.
> The exact form of the correction will depend on the order in which the
> voltage measurements are made.
>
> Ideally the 2 synchroniser circuits would be include the capability of
> producing calibration signals of known duration to facilitate
> calibration of the gains of the 2 TACs whenever required.
>
>
> Bruce
>
>   
Equation should have been

t2-t1 = G*(V2-V1) + e*V1 + offset.

Where
G is the  TAC gain
E is a small coefficient that accounts for TAC gain mismatch and the
residual voltage on the ADC sampling cap.
offset is a time offset principally due to propagation delay mismatch
between the 2 synchronisers.

Bruce


From jim77742 at gmail.com  Mon Dec 29 02:31:49 2008
From: jim77742 at gmail.com (Jim Palfreyman)
Date: Mon, 29 Dec 2008 13:31:49 +1100
Subject: [time-nuts] How are you going to spend your extra second?
In-Reply-To: <625009.5418.qm@web54109.mail.re2.yahoo.com>
References: <625009.5418.qm@web54109.mail.re2.yahoo.com>
Message-ID: <f616e0f80812281831w6b580904y78d2015ea0b4441b@mail.gmail.com>

I suppose it's "nuts" is it to want to live in a society where there a very
few guns available, where ordinary people don't carry them and people can't
be shot and killed in a quick fit of anger over something trivial.

I like living in a society like that and I find it objectionable to be
called a "nut".

But I like being called a time-nut!

Jim

2008/12/25 James R. Gorr <n3toy at yahoo.com>

>
> Maybe I jumped the gun... (no pun intended).  My apologies, I must not have
> gone back far enough.
>
> Ok, maybe the pun was intended.  :-)
>
> --- On Wed, 12/24/08, Mark Sims <holrum at hotmail.com> wrote:
>
> From: Mark Sims <holrum at hotmail.com>
> Subject: [time-nuts] How are you going to spend your extra second?
> To: time-nuts at febo.com
> Date: Wednesday, December 24, 2008, 5:11 PM
>
>
> James,
> If you had read my previous post you would have realized I am far from an
> anti-gun political nut.  I have an arsenal that would make Sadaam blush
> (over 100 pieces,  mostly military models from .17 cal to .50BMG).  I paid
> for the HP45 calculator that put me through engineering school by shooting
> rabbits for ranchers.  I was seventh in the nation in a Naval postal match.
> What I am against is nutcases that spoil the fun for the rest of us by doing
> things like unloading a few magazines of ammo into the sky in the middle of
> a crowded city.
> _________________________________________________________________
> It's the same Hotmail(R). If by "same" you mean up to 70% faster.
>
> http://windowslive.com/online/hotmail?ocid=TXT_TAGLM_WL_hotmail_acq_broad1_122008
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>
>
>
>
>
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>

From didier at cox.net  Mon Dec 29 03:01:00 2008
From: didier at cox.net (Didier)
Date: Sun, 28 Dec 2008 21:01:00 -0600
Subject: [time-nuts] Thunderbolt Monitor
In-Reply-To: <f616e0f80812281831w6b580904y78d2015ea0b4441b@mail.gmail.com>
References: <625009.5418.qm@web54109.mail.re2.yahoo.com>
	<f616e0f80812281831w6b580904y78d2015ea0b4441b@mail.gmail.com>
Message-ID: <A88EB04D81C64B168F8F4CA4DD19C80E@didierhp>

Fellow time-nuts,

I am glad to announce a new version of the Thunderbolt Monitor software has
been released (v0.2.1).

http://www.ko4bb.com/dokuwiki/doku.php?id=precision_timing:gps_monitor

Dan Karg contributed bug fixes and a new display routine, and I believe I
have fixed a random corruption issue with the VFD.

Now, all I need to do is finish the PWB...

Didier KO4BB



From bill at iaxs.net  Mon Dec 29 04:50:50 2008
From: bill at iaxs.net (Bill Hawkins)
Date: Sun, 28 Dec 2008 22:50:50 -0600
Subject: [time-nuts] How are you going to spend your extra second?
In-Reply-To: <f616e0f80812281831w6b580904y78d2015ea0b4441b@mail.gmail.com>
References: <625009.5418.qm@web54109.mail.re2.yahoo.com>
	<f616e0f80812281831w6b580904y78d2015ea0b4441b@mail.gmail.com>
Message-ID: <A38FCA1F176644FF96FA1D41EF5A863A@cyrus>


"I suppose it's "nuts" is it to want to live in a society where there
a very few guns available, where ordinary people don't carry them and
people can't be shot and killed in a quick fit of anger over something
trivial."

There's another subject line that could stand changing.

Maybe to another list, too.

See, subject lines tell me to delete if I don't care. I'm feeling worse
than I have in a while, so the fall of a mosquito's wing would irritate
me.

Bill Hawkins



From cfharris at erols.com  Mon Dec 29 06:55:40 2008
From: cfharris at erols.com (Chuck Harris)
Date: Mon, 29 Dec 2008 01:55:40 -0500
Subject: [time-nuts] How are you going to spend your extra second?
In-Reply-To: <f616e0f80812281831w6b580904y78d2015ea0b4441b@mail.gmail.com>
References: <625009.5418.qm@web54109.mail.re2.yahoo.com>
	<f616e0f80812281831w6b580904y78d2015ea0b4441b@mail.gmail.com>
Message-ID: <4958746C.9040701@erols.com>

Jim Palfreyman wrote:
> I suppose it's "nuts" is it to want to live in a society where there a very
> few guns available, where ordinary people don't carry them and people can't
> be shot and killed in a quick fit of anger over something trivial.

It's nuts to believe that criminals are going to stop using guns
just because you have banned them from the law abiding people.

Criminals by definition break laws.

It's nuts to believe that the law abiding gun owners are just
latent criminals waiting for a chance to snap and do violence.

It's nuts to believe that a very few guns in the hands of the
police will make you safe.  The police, just like everybody else
are prone to being human.  They are also prone to having their
possessions (guns) stolen.

> 
> I like living in a society like that and I find it objectionable to be
> called a "nut".

-Chuck Harris


From jim77742 at gmail.com  Mon Dec 29 07:43:33 2008
From: jim77742 at gmail.com (Jim Palfreyman)
Date: Mon, 29 Dec 2008 18:43:33 +1100
Subject: [time-nuts] How are you going to spend your extra second?
In-Reply-To: <4958746C.9040701@erols.com>
References: <625009.5418.qm@web54109.mail.re2.yahoo.com>
	<f616e0f80812281831w6b580904y78d2015ea0b4441b@mail.gmail.com>
	<4958746C.9040701@erols.com>
Message-ID: <f616e0f80812282343u2bad4dfescd3992e684625c82@mail.gmail.com>

Well it seems to work quite well in Australia.

2008/12/29 Chuck Harris <cfharris at erols.com>

> Jim Palfreyman wrote:
> > I suppose it's "nuts" is it to want to live in a society where there a
> very
> > few guns available, where ordinary people don't carry them and people
> can't
> > be shot and killed in a quick fit of anger over something trivial.
>
> It's nuts to believe that criminals are going to stop using guns
> just because you have banned them from the law abiding people.
>
> Criminals by definition break laws.
>
> It's nuts to believe that the law abiding gun owners are just
> latent criminals waiting for a chance to snap and do violence.
>
> It's nuts to believe that a very few guns in the hands of the
> police will make you safe.  The police, just like everybody else
> are prone to being human.  They are also prone to having their
> possessions (guns) stolen.
>
> >
> > I like living in a society like that and I find it objectionable to be
> > called a "nut".
>
> -Chuck Harris
>
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>

From phk at phk.freebsd.dk  Mon Dec 29 08:03:04 2008
From: phk at phk.freebsd.dk (Poul-Henning Kamp)
Date: Mon, 29 Dec 2008 08:03:04 +0000
Subject: [time-nuts] How are you going to spend your extra second?
In-Reply-To: Your message of "Mon, 29 Dec 2008 01:55:40 EST."
	<4958746C.9040701@erols.com> 
Message-ID: <38346.1230537784@critter.freebsd.dk>

In message <4958746C.9040701 at erols.com>, Chuck Harris writes:
>Jim Palfreyman wrote:
>> I suppose it's "nuts" is it to want to live in a society where there a very
>> few guns available, where ordinary people don't carry them and people can't
>> be shot and killed in a quick fit of anger over something trivial.
>
>It's nuts to believe that criminals are going to stop using guns
>just because you have banned them from the law abiding people.

Can we can the gun-talk on the *time-nuts* list please ?

-- 
Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk at FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.


From magnus at rubidium.dyndns.org  Mon Dec 29 08:19:33 2008
From: magnus at rubidium.dyndns.org (Magnus Danielson)
Date: Mon, 29 Dec 2008 09:19:33 +0100
Subject: [time-nuts] How are you going to spend your extra second?
In-Reply-To: <38346.1230537784@critter.freebsd.dk>
References: <38346.1230537784@critter.freebsd.dk>
Message-ID: <49588815.4030901@rubidium.dyndns.org>

Poul-Henning Kamp skrev:
> In message <4958746C.9040701 at erols.com>, Chuck Harris writes:
>> Jim Palfreyman wrote:
>>> I suppose it's "nuts" is it to want to live in a society where there a very
>>> few guns available, where ordinary people don't carry them and people can't
>>> be shot and killed in a quick fit of anger over something trivial.
>> It's nuts to believe that criminals are going to stop using guns
>> just because you have banned them from the law abiding people.
> 
> Can we can the gun-talk on the *time-nuts* list please ?
> 

I was just contacted by an artist that wants to capture the leap-second 
for a project she does. I think it very well matches the topic of this 
thread.

It brings on the discussion on how to best observe the leap-second.

For her part, getting the 23:59:60 reading would be the ideal. I came to 
realize that few computer clocks would report that even with propper NTP.

So, ideas, knowledge, update since the last leap-second?

I would sure like to see it in various forms. I would like to have a 
computer (UNIX/LINUX) clock that provides propper UTC...

I would not mind seeing it popping out of my GPS clocks either.

I don't think I will have DCF77, MSF or LORAN-C capability on new years 
eve, otherwise those should be possible to receive here too.

Cheers,
Magnus


From namichie at gmail.com  Mon Dec 29 09:00:55 2008
From: namichie at gmail.com (Neville Michie)
Date: Mon, 29 Dec 2008 20:00:55 +1100
Subject: [time-nuts] How are you going to spend your extra second?
In-Reply-To: <38346.1230537784@critter.freebsd.dk>
References: <38346.1230537784@critter.freebsd.dk>
Message-ID: <3E6B8240-DBF1-41FE-8D2A-F00E9595BA62@gmail.com>

We in more civilised countries have been quiet as you in USA have
proclaimed how free you are due to your guns....
You also shoot 17 thousand citizens dead in your free country every  
year.
We have a few criminals with guns, but we also only lose 5% of the  
number
of citizens that are lost to guns in USA.
Now I have had my say, lets get back to time-nut business.
cheers, Neville Michie


On 29/12/2008, at 7:03 PM, Poul-Henning Kamp wrote:

> In message <4958746C.9040701 at erols.com>, Chuck Harris writes:
>> Jim Palfreyman wrote:
>>> I suppose it's "nuts" is it to want to live in a society where  
>>> there a very
>>> few guns available, where ordinary people don't carry them and  
>>> people can't
>>> be shot and killed in a quick fit of anger over something trivial.
>>
>> It's nuts to believe that criminals are going to stop using guns
>> just because you have banned them from the law abiding people.
>
> Can we can the gun-talk on the *time-nuts* list please ?
>
> -- 
> Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
> phk at FreeBSD.ORG         | TCP/IP since RFC 956
> FreeBSD committer       | BSD since 4.3-tahoe
> Never attribute to malice what can adequately be explained by  
> incompetence.
>
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/ 
> time-nuts
> and follow the instructions there.



From jim77742 at gmail.com  Mon Dec 29 11:24:11 2008
From: jim77742 at gmail.com (Jim Palfreyman)
Date: Mon, 29 Dec 2008 22:24:11 +1100
Subject: [time-nuts] How are you going to spend your extra second?
In-Reply-To: <49588815.4030901@rubidium.dyndns.org>
References: <38346.1230537784@critter.freebsd.dk>
	<49588815.4030901@rubidium.dyndns.org>
Message-ID: <f616e0f80812290324x8fc48f6rf7a14f58923d0a2e@mail.gmail.com>

I have a "speaking clock" from Australia in my possession and it handles the
leap second. I plan to photograph its display.

2008/12/29 Magnus Danielson <magnus at rubidium.dyndns.org>

> Poul-Henning Kamp skrev:
> > In message <4958746C.9040701 at erols.com>, Chuck Harris writes:
> >> Jim Palfreyman wrote:
> >>> I suppose it's "nuts" is it to want to live in a society where there a
> very
> >>> few guns available, where ordinary people don't carry them and people
> can't
> >>> be shot and killed in a quick fit of anger over something trivial.
> >> It's nuts to believe that criminals are going to stop using guns
> >> just because you have banned them from the law abiding people.
> >
> > Can we can the gun-talk on the *time-nuts* list please ?
> >
>
> I was just contacted by an artist that wants to capture the leap-second
> for a project she does. I think it very well matches the topic of this
> thread.
>
> It brings on the discussion on how to best observe the leap-second.
>
> For her part, getting the 23:59:60 reading would be the ideal. I came to
> realize that few computer clocks would report that even with propper NTP.
>
> So, ideas, knowledge, update since the last leap-second?
>
> I would sure like to see it in various forms. I would like to have a
> computer (UNIX/LINUX) clock that provides propper UTC...
>
> I would not mind seeing it popping out of my GPS clocks either.
>
> I don't think I will have DCF77, MSF or LORAN-C capability on new years
> eve, otherwise those should be possible to receive here too.
>
> Cheers,
> Magnus
>
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>

From didier at cox.net  Mon Dec 29 12:43:06 2008
From: didier at cox.net (Didier)
Date: Mon, 29 Dec 2008 06:43:06 -0600
Subject: [time-nuts] How are you going to spend your extra second?
In-Reply-To: <38346.1230537784@critter.freebsd.dk>
References: Your message of "Mon,
	29 Dec 2008 01:55:40 EST."<4958746C.9040701@erols.com>
	<38346.1230537784@critter.freebsd.dk>
Message-ID: <FBF6B929705042D1BFD3AF3366DFF27F@didierhp>

That would be about time...

Didier 

> -----Original Message-----
> From: time-nuts-bounces at febo.com 
> [mailto:time-nuts-bounces at febo.com] On Behalf Of Poul-Henning Kamp
> Sent: Monday, December 29, 2008 2:03 AM
> To: Discussion of precise time and frequency measurement
> Subject: Re: [time-nuts] How are you going to spend your extra second?
> 
> In message <4958746C.9040701 at erols.com>, Chuck Harris writes:
> >Jim Palfreyman wrote:
> >> I suppose it's "nuts" is it to want to live in a society 
> where there 
> >> a very few guns available, where ordinary people don't 
> carry them and 
> >> people can't be shot and killed in a quick fit of anger 
> over something trivial.
> >
> >It's nuts to believe that criminals are going to stop using 
> guns just 
> >because you have banned them from the law abiding people.
> 
> Can we can the gun-talk on the *time-nuts* list please ?
> 
> -- 
> Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
> phk at FreeBSD.ORG         | TCP/IP since RFC 956
> FreeBSD committer       | BSD since 4.3-tahoe    
> Never attribute to malice what can adequately be explained by 
> incompetence.
> 
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com To unsubscribe, 
> go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.



From sar10538 at gmail.com  Mon Dec 29 13:03:36 2008
From: sar10538 at gmail.com (Steve Rooke)
Date: Tue, 30 Dec 2008 02:03:36 +1300
Subject: [time-nuts] How are you going to spend your extra second?
In-Reply-To: <FBF6B929705042D1BFD3AF3366DFF27F@didierhp>
References: <4958746C.9040701@erols.com> <38346.1230537784@critter.freebsd.dk>
	<FBF6B929705042D1BFD3AF3366DFF27F@didierhp>
Message-ID: <1231b6a80812290503k22796806t68e2e42312d1a90@mail.gmail.com>

Are there any web sites that would show the leap-second?

2008/12/30 Didier <didier at cox.net>:
> That would be about time...
>
> Didier
>
>> -----Original Message-----
>> From: time-nuts-bounces at febo.com
>> [mailto:time-nuts-bounces at febo.com] On Behalf Of Poul-Henning Kamp
>> Sent: Monday, December 29, 2008 2:03 AM
>> To: Discussion of precise time and frequency measurement
>> Subject: Re: [time-nuts] How are you going to spend your extra second?
>>
>> In message <4958746C.9040701 at erols.com>, Chuck Harris writes:
>> >Jim Palfreyman wrote:
>> >> I suppose it's "nuts" is it to want to live in a society
>> where there
>> >> a very few guns available, where ordinary people don't
>> carry them and
>> >> people can't be shot and killed in a quick fit of anger
>> over something trivial.
>> >
>> >It's nuts to believe that criminals are going to stop using
>> guns just
>> >because you have banned them from the law abiding people.
>>
>> Can we can the gun-talk on the *time-nuts* list please ?
>>
>> --
>> Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
>> phk at FreeBSD.ORG         | TCP/IP since RFC 956
>> FreeBSD committer       | BSD since 4.3-tahoe
>> Never attribute to malice what can adequately be explained by
>> incompetence.
>>
>> _______________________________________________
>> time-nuts mailing list -- time-nuts at febo.com To unsubscribe,
>> go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>> and follow the instructions there.
>
>
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>



-- 
Steve Rooke - ZL3TUV & G8KVD
Omnium finis imminet


From n3toy at yahoo.com  Mon Dec 29 13:07:26 2008
From: n3toy at yahoo.com (James R. Gorr)
Date: Mon, 29 Dec 2008 05:07:26 -0800 (PST)
Subject: [time-nuts] How are you going to spend your extra second?
In-Reply-To: <49588815.4030901@rubidium.dyndns.org>
Message-ID: <154512.75886.qm@web54105.mail.re2.yahoo.com>


As simple as it is, time.gov shows the leap second.  A screen capture from there is probably one of the easiest ways to "see" the leap second. 

Would be interested in seeing her leap second art.

Jamie


--- On Mon, 12/29/08, Magnus Danielson <magnus at rubidium.dyndns.org> wrote:


> I was just contacted by an artist that wants to capture the
> leap-second 
> for a project she does. I think it very well matches the
> topic of this 
> thread.
> 
> It brings on the discussion on how to best observe the
> leap-second.
> 
> For her part, getting the 23:59:60 reading would be the
> ideal. I came to 
> realize that few computer clocks would report that even
> with propper NTP.
> 
> So, ideas, knowledge, update since the last leap-second?
> 
> I would sure like to see it in various forms. I would like
> to have a 
> computer (UNIX/LINUX) clock that provides propper UTC...
> 
> I would not mind seeing it popping out of my GPS clocks
> either.
> 
> I don't think I will have DCF77, MSF or LORAN-C
> capability on new years 
> eve, otherwise those should be possible to receive here
> too.
> 
> Cheers,
> Magnus
> 
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.


      


From jra at febo.com  Mon Dec 29 13:13:20 2008
From: jra at febo.com (John Ackermann N8UR)
Date: Mon, 29 Dec 2008 08:13:20 -0500
Subject: [time-nuts] How are you going to spend your extra second?
In-Reply-To: <4958746C.9040701@erols.com>
References: <625009.5418.qm@web54109.mail.re2.yahoo.com>	<f616e0f80812281831w6b580904y78d2015ea0b4441b@mail.gmail.com>
	<4958746C.9040701@erols.com>
Message-ID: <4958CCF0.6000504@febo.com>

Guys, this is totally off topic.  Please drop it.

Thanks,

Your Sysadmin
----

Chuck Harris said the following on 12/29/2008 01:55 AM:
> Jim Palfreyman wrote:
>> I suppose it's "nuts" is it to want to live in a society where there a very
>> few guns available, where ordinary people don't carry them and people can't
>> be shot and killed in a quick fit of anger over something trivial.
> 
> It's nuts to believe that criminals are going to stop using guns
> just because you have banned them from the law abiding people.
> 
> Criminals by definition break laws.
> 
> It's nuts to believe that the law abiding gun owners are just
> latent criminals waiting for a chance to snap and do violence.
> 
> It's nuts to believe that a very few guns in the hands of the
> police will make you safe.  The police, just like everybody else
> are prone to being human.  They are also prone to having their
> possessions (guns) stolen.
> 
>> I like living in a society like that and I find it objectionable to be
>> called a "nut".
> 
> -Chuck Harris
> 
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.


From sar10538 at gmail.com  Mon Dec 29 13:46:23 2008
From: sar10538 at gmail.com (Steve Rooke)
Date: Tue, 30 Dec 2008 02:46:23 +1300
Subject: [time-nuts] Deriving PPS from hockey-puck G-Mouse GPS receiver to
	lock an oscillator
Message-ID: <1231b6a80812290546l6f0e802eq2aaf01758e8e5667@mail.gmail.com>

I bought a job lot of Polstar G-Mouse receivers to play with. These
use the Sony CXD2951GA-4 chipset which has a PPS output but this is
not made available at the end of the cable unfortunately. The units
themselves are fully waterproof so they are happy to sit through all
kinds of weather outside and cling like limpets to a metal surface
even with the gusty winds we have been experiencing here. Now I have
looked at the output of these which from a reset state run at 4800bd
and produce the requisite NMEA 0183 protocol as expected. Looking at
the TTL output on a scope there is a burst of data, at 4800bd, each
second with a reasonable gap between each burst. Each packet of data
starts with a $GPGGA message and time-stamping these shows they seem
to occur at 1 second intervals. What I was thinking about building was
a small circuit which would switch on the start of the data block and
then time out at the end of the block thereby producing a 1Hz signal,
albeit not 50% duty cycle, which could possibly be used to lock a ocxo
via a phase-frequency detector, like a MC4044, and a low pass filter.
Has anyone looked at this before and, perhaps discarded it or
whatever? Yes, I know it is no substitute for a Thunderbolt but I
don't have one of those yet and this may be a cheap and cheerful way
to sync to GPS.

Be gentle Bruce :-)

73, Steve
-- 
Steve Rooke - ZL3TUV & G8KVD & JAKDTTNW
Omnium finis imminet


From cfharris at erols.com  Mon Dec 29 14:43:23 2008
From: cfharris at erols.com (Chuck Harris)
Date: Mon, 29 Dec 2008 09:43:23 -0500
Subject: [time-nuts] How are you going to spend your extra second?
In-Reply-To: <f616e0f80812282343u2bad4dfescd3992e684625c82@mail.gmail.com>
References: <625009.5418.qm@web54109.mail.re2.yahoo.com>	<f616e0f80812281831w6b580904y78d2015ea0b4441b@mail.gmail.com>	<4958746C.9040701@erols.com>
	<f616e0f80812282343u2bad4dfescd3992e684625c82@mail.gmail.com>
Message-ID: <4958E20B.1070502@erols.com>

If you discount the gun violence caused by gangs and drug
dealers, guns cause few problems in the US.

Law abiding gun owners are not the problem!

This is a time-nuts group, yet I have a difficult time
allowing liberal anti-gun BS to go unchallenged.

Let's return this channel to time related messages.

-Chuck Harris

Jim Palfreyman wrote:
> Well it seems to work quite well in Australia.
> 
> 2008/12/29 Chuck Harris <cfharris at erols.com>
> 
>> Jim Palfreyman wrote:
>>> I suppose it's "nuts" is it to want to live in a society where there a
>> very
>>> few guns available, where ordinary people don't carry them and people
>> can't
>>> be shot and killed in a quick fit of anger over something trivial.
>> It's nuts to believe that criminals are going to stop using guns
>> just because you have banned them from the law abiding people.
>>
>> Criminals by definition break laws.
>>
>> It's nuts to believe that the law abiding gun owners are just
>> latent criminals waiting for a chance to snap and do violence.
>>
>> It's nuts to believe that a very few guns in the hands of the
>> police will make you safe.  The police, just like everybody else
>> are prone to being human.  They are also prone to having their
>> possessions (guns) stolen.
>>
>>> I like living in a society like that and I find it objectionable to be
>>> called a "nut".
>> -Chuck Harris


From cfharris at erols.com  Mon Dec 29 15:10:46 2008
From: cfharris at erols.com (Chuck Harris)
Date: Mon, 29 Dec 2008 10:10:46 -0500
Subject: [time-nuts] New topics (was Re: He isaTime-Nut	Troublemaker....)
In-Reply-To: <20081225142942.LIJC18445.eastrmmtao103.cox.net@eastrmimpo01.cox.net>
References: <20081225142942.LIJC18445.eastrmmtao103.cox.net@eastrmimpo01.cox.net>
Message-ID: <4958E876.7060707@erols.com>

Didier,

I wonder what would happen if you took N, uncorrelated and well isolated,
10 MHz sources and added them together?

-Chuck Harris


> 
> The cost in complexity for combining oscillators is much more significant
> than for amplifiers. Amplifiers only need phase matching (electrical
> length). Oscillators need to be phase locked to begin with.
> 
> Merry Christmas to all.
> 
> Didier KO4BB
> 


From bg at lysator.liu.se  Mon Dec 29 15:11:51 2008
From: bg at lysator.liu.se (=?ISO-8859-1?Q?Bj=F6rn?= Gabrielsson)
Date: Mon, 29 Dec 2008 16:11:51 +0100
Subject: [time-nuts] Deriving PPS from hockey-puck G-Mouse GPS
	receiver	to lock an oscillator
In-Reply-To: <1231b6a80812290546l6f0e802eq2aaf01758e8e5667@mail.gmail.com>
References: <1231b6a80812290546l6f0e802eq2aaf01758e8e5667@mail.gmail.com>
Message-ID: <1230563511.20850.37.camel@bg-desktop>


On Tue, 2008-12-30 at 02:46 +1300, Steve Rooke wrote:
[...
> even with the gusty winds we have been experiencing here. Now I have
> looked at the output of these which from a reset state run at 4800bd
> and produce the requisite NMEA 0183 protocol as expected. Looking at
> the TTL output on a scope there is a burst of data, at 4800bd, each
> second with a reasonable gap between each burst. Each packet of data
> starts with a $GPGGA message and time-stamping these shows they seem
> to occur at 1 second intervals. What I was thinking about building was
> a small circuit which would switch on the start of the data block and
> then time out at the end of the block thereby producing a 1Hz signal,
> albeit not 50% duty cycle, which could possibly be used to lock a ocxo
> via a phase-frequency detector, like a MC4044, and a low pass filter.
> Has anyone looked at this before and, perhaps discarded it or
> whatever? Yes, I know it is no substitute for a Thunderbolt but I
> don't have one of those yet and this may be a cheap and cheerful way
> to sync to GPS.

Measuring is more fun than theoretical pondering... so start there. ;-)

Try to measure the jitter on that 1Hz signal. Either with "external"
hardware, or software. One way to do this is by configuring the GPS as a
refclock to a computer running NTP.

  http://www.eecis.udel.edu/~mills/ntp/html/drivers/driver20.html

When you have the computer running you can query NTP of what kind of
jitter it sees. Look at the last column in the query below. With a few
external network servers you can also estimate approximate delay or
offset. Both are in milliseconds below.

NOTE: The GENERIC clock here IS using PPS.

$ ntpq -c pe timehost.lysator.liu.se
     remote       refid    st t when poll reach   delay   offset  jitter
==============================================================================
*GENERIC(0)      .GPS.     0 l   64   64  377    0.000    0.001   0.002
+nissan.ifm.liu. .PPS.     1 u  644 1024  377    0.655   -0.009   0.033
+ntp1.sth.netnod .PPS.     1 u  593 1024  377    3.661   -0.037   0.053
+ntp2.gbg.netnod .PPS.     1 u  619 1024  377   10.967   -0.025   0.042
-ntp1.mmo.netnod .PPS.     1 u  623 1024  377   13.933   -0.097   0.050

Last time I tried a NMEA without PPS i got jitter of about 10ms. Delay
(offset) was a few hundred ms.

Why is NMEA probably the worst way to get time out of a generic GPS
receiver?  

The receiver has more important stuff to do than putting the first bit
of a long serial message on a slow 4800baud link exactly at the correct
time. If the receiver is busy tending to its correlator chip. Serial
output will have to wait.

There are often two serial protocols implemented in the receiver. A
binary format different for each manufacturer. Trimble has TSIP, SIRF
Binary etc. This require less CPU to generate than the ascii NMEA. The
binary protocol often has better timing.

The number of CPU cycles to compute a PVT solution is not constant. With
4 satelite measurements its quicker than with 12 SVs in view. 

If the NMEA output is the task with lowest priority in the receiver the
leading pulse timing accuracy will suffer. 

There are sometimes a short binary timing message that have better
specifications on jitter and offset. This would probably be an order of
magnitude better than NMEA. A real PPS would be another 3 or so
magnitudes better.

There are surely exceptions to the above arguments not to use straight
NMEA. Measuring the performance over some time of cause gives you the
best answer for your particular GPS.

good luck!

    Bj?rn

> Be gentle Bruce :-)
> 
> 73, Steve



From didier at cox.net  Mon Dec 29 16:33:52 2008
From: didier at cox.net (Didier)
Date: Mon, 29 Dec 2008 10:33:52 -0600
Subject: [time-nuts] FW: time-nuts Digest, Vol 53, Issue 112
Message-ID: <FA2D45FC987B4AE6806152FAF685B015@didierhp>

When I replied to this message, it bounced (apparently the address
fre_eng at g4fre.com cannot be resolved)

Didier

> -----Original Message-----
> From: fre_eng [mailto:fre_eng at g4fre.com]
> Sent: Monday, December 29, 2008 8:00 AM
> To: didier at cox.net
> Subject: FW: time-nuts Digest, Vol 53, Issue 112
> 
> Very interesting project
> 
> what is the part number of the "base adaptor"? I searched mouser for 
> that term and didnt find one.
> 
> Thanks
> 
> Dave
> 
> 
> 

-----Original Response-----
From: Didier [mailto:didier at cox.net] 
Sent: Monday, December 29, 2008 10:30 AM
To: 'fre_eng'
Subject: RE: time-nuts Digest, Vol 53, Issue 112

Dave,

I did not remember the link, so I googled "Silabs Base Adapter" and this
came back

http://parts.digikey.com/1/parts/410050-toolstick-base-adapter-toolstickba.h
tml

:-)

If you want to program DIP chips (not Toolsticks), you also need a Debug
adapter

https://www.silabs.com/products/mcu/Pages/ToolStick.aspx

Scroll to the bottom of the page.

The Debug adapter plugs into the Base adapter and has a JTAG/C2 connector
that is convenient for prototypes (10 pin header, but you only need 4
wires).

Happy building!

Didier 



From didier at cox.net  Mon Dec 29 16:38:04 2008
From: didier at cox.net (Didier)
Date: Mon, 29 Dec 2008 10:38:04 -0600
Subject: [time-nuts] New topics (was Re: He isaTime-Nut	Troublemaker....)
In-Reply-To: <4958E876.7060707@erols.com>
References: <20081225142942.LIJC18445.eastrmmtao103.cox.net@eastrmimpo01.cox.net>
	<4958E876.7060707@erols.com>
Message-ID: <949C8C71AFC249B3866DA1068E79D089@didierhp>

I think you will get a narrow (how narrow will depend on how close they are
in frequency and how many there are) band of noise centered around 10 MHz. 

Didier

> -----Original Message-----
> From: time-nuts-bounces at febo.com 
> [mailto:time-nuts-bounces at febo.com] On Behalf Of Chuck Harris
> Sent: Monday, December 29, 2008 9:11 AM
> To: Discussion of precise time and frequency measurement
> Subject: Re: [time-nuts] New topics (was Re: He isaTime-Nut 
> Troublemaker....)
> 
> Didier,
> 
> I wonder what would happen if you took N, uncorrelated and 
> well isolated, 10 MHz sources and added them together?
> 
> -Chuck Harris
> 
> 
> > 
> > The cost in complexity for combining oscillators is much more 
> > significant than for amplifiers. Amplifiers only need phase 
> matching 
> > (electrical length). Oscillators need to be phase locked to 
> begin with.
> > 
> > Merry Christmas to all.
> > 
> > Didier KO4BB
> > 
> 
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com To unsubscribe, 
> go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.



From pvince at theiet.org  Mon Dec 29 16:49:25 2008
From: pvince at theiet.org (Peter Vince)
Date: Mon, 29 Dec 2008 16:49:25 +0000
Subject: [time-nuts] New topics (was Re: He isaTime-Nut	Troublemaker....)
Message-ID: <1130.1230569365@uk2.net>

But surely also you would get beating as they drifted in and out of phase with
each other, and hence large amplitude and phase variations?

Peter


On Mon Dec 29 16:38 , 'Didier' <didier at cox.net> sent:

>I think you will get a narrow (how narrow will depend on how close they are
>in frequency and how many there are) band of noise centered around 10 MHz. 
>
>Didier
>
>> -----Original Message-----
>> From: time-nuts-bounces at febo.com 
>> [time-nuts-bounces at febo.com','','','')">time-nuts-bounces at febo.com] On Behalf
Of Chuck Harris
>> Sent: Monday, December 29, 2008 9:11 AM
>> To: Discussion of precise time and frequency measurement
>> Subject: Re: [time-nuts] New topics (was Re: He isaTime-Nut 
>> Troublemaker....)
>> 
>> Didier,
>> 
>> I wonder what would happen if you took N, uncorrelated and 
>> well isolated, 10 MHz sources and added them together?
>> 
>> -Chuck Harris
>> 
>> 
>> > 
>> > The cost in complexity for combining oscillators is much more 
>> > significant than for amplifiers. Amplifiers only need phase 
>> matching 
>> > (electrical length). Oscillators need to be phase locked to 
>> begin with.
>> > 
>> > Merry Christmas to all.
>> > 
>> > Didier KO4BB
>> > 
>> 
>> _______________________________________________
>> time-nuts mailing list -- time-nuts at febo.com To unsubscribe, 
>> go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>> and follow the instructions there.
>
>
>_______________________________________________
>time-nuts mailing list -- time-nuts at febo.com
>To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>and follow the instructions there.
>
>______________________________________________________________________
>This email has been scanned by the MessageLabs Email Security System.
>For more information please visit http://www.messagelabs.com/email 
>______________________________________________________________________




From holrum at hotmail.com  Mon Dec 29 17:07:28 2008
From: holrum at hotmail.com (Mark Sims)
Date: Mon, 29 Dec 2008 17:07:28 +0000
Subject: [time-nuts] Deriving PPS from hockey-puck G-Mouse GPS receiver to
 lock an oscillator
In-Reply-To: <mailman.849.1230563517.2499.time-nuts@febo.com>
References: <mailman.849.1230563517.2499.time-nuts@febo.com>
Message-ID: <BLU125-W153ACD5559C8C8AA8F92EACEE60@phx.gbl>


A long time ago, I did something very similar with an early release Magellan 5000 board  (and a couple of other models of GPS cards) that did not implement the 1PPS signal.  I think the best time sync that I ever got was around 1 mS (most boards were around 10 mS).  

True 1PPS signals are implemented and synchronized in hardware.  The NMEA messages are generated in software.  Due to the vagaries of things like software interrupt latencies,  serial port bit synchronization, etc I doubt that you could ever get better than 1 serial bit time of accuracy out of any board and 10-100 bit times is more likely.  At 4800 bits/sec the jitter/offset of even 1 bit time would be huge at best.  Perfectly OK for things like clock displays,  but totally inadequate for things like oscillator locking.
_________________________________________________________________
Send e-mail faster without improving your typing skills.
http://windowslive.com/online/hotmail?ocid=TXT_TAGLM_WL_hotmail_acq_speed_122008

From w1ksz at earthlink.net  Mon Dec 29 17:38:16 2008
From: w1ksz at earthlink.net (Richard W. Solomon)
Date: Mon, 29 Dec 2008 10:38:16 -0700 (GMT-07:00)
Subject: [time-nuts] Help ID Display
Message-ID: <30097828.1230572296476.JavaMail.root@elwamui-rubis.atl.sa.earthlink.net>

I have a nice looking display that I salvaged from a piece of
Cell Phone Site equipment. It's either a 4 X 20 or 4 X 40 display.

The only markings on it are:
KL SN102 94V-0
and the letters VL in a square box.

I Googled it and saw others in France and Otaly looking for similar
info, but no answers yet.

It might make a nifty display for a stand-alone GPS Monitor.

Anyone heard of or saw this beastie ??

Thsnks and HNY to all,

Dick, W1KSZ 


From newell at cei.net  Mon Dec 29 18:14:21 2008
From: newell at cei.net (Scott Newell)
Date: Mon, 29 Dec 2008 12:14:21 -0600
Subject: [time-nuts] Help ID Display
In-Reply-To: <30097828.1230572296476.JavaMail.root@elwamui-rubis.atl.sa.
	earthlink.net>
Message-ID: <200812291814.mBTIEMxe006519@mail959c35.nsolutionszone.com>

At 11:38 AM 12/29/2008 , Richard W. Solomon wrote:
>I have a nice looking display that I salvaged from a piece of
>Cell Phone Site equipment. It's either a 4 X 20 or 4 X 40 display.

Got pics?  What's the connector look like?  Graphic LCD, character mode
LCD, VFD, LED, plasma, or?  Any chips/drivers on it?

-- 
newell  N5TNL



From w1ksz at earthlink.net  Mon Dec 29 18:29:19 2008
From: w1ksz at earthlink.net (Richard W. Solomon)
Date: Mon, 29 Dec 2008 11:29:19 -0700 (GMT-07:00)
Subject: [time-nuts] Help ID Display
Message-ID: <4705110.1230575359785.JavaMail.root@elwamui-rubis.atl.sa.earthlink.net>

Not sure if this accepts attachments, but here goes ...

Thanks, Dick, W1KSZ

-----Original Message-----
>From: Scott Newell <newell at cei.net>
>Sent: Dec 29, 2008 11:14 AM
>To: time-nuts at febo.com
>Subject: Re: [time-nuts] Help ID Display
>
>At 11:38 AM 12/29/2008 , Richard W. Solomon wrote:
>>I have a nice looking display that I salvaged from a piece of
>>Cell Phone Site equipment. It's either a 4 X 20 or 4 X 40 display.
>
>Got pics?  What's the connector look like?  Graphic LCD, character mode
>LCD, VFD, LED, plasma, or?  Any chips/drivers on it?
>
>-- 
>newell  N5TNL
>
>
>_______________________________________________
>time-nuts mailing list -- time-nuts at febo.com
>To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>and follow the instructions there.
-------------- next part --------------
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From time-nuts at adobe-labs.com  Mon Dec 29 18:29:38 2008
From: time-nuts at adobe-labs.com (Brent Gordon)
Date: Mon, 29 Dec 2008 11:29:38 -0700
Subject: [time-nuts] Help ID Display
In-Reply-To: <30097828.1230572296476.JavaMail.root@elwamui-rubis.atl.sa.earthlink.net>
References: <30097828.1230572296476.JavaMail.root@elwamui-rubis.atl.sa.earthlink.net>
Message-ID: <49591712.5090509@adobe-labs.com>

I found this using Google.  Look about half-way down in the postings for 
a connection pinout.

http://www.mp3car.com/vbulletin/lcd-display/15058-so-i-got-40x4-off-ebay.html

Brent.

Richard W. Solomon wrote:
> I have a nice looking display that I salvaged from a piece of
> Cell Phone Site equipment. It's either a 4 X 20 or 4 X 40 display.
>
> The only markings on it are:
> KL SN102 94V-0
> and the letters VL in a square box.
>
> I Googled it and saw others in France and Otaly looking for similar
> info, but no answers yet.
>
> It might make a nifty display for a stand-alone GPS Monitor.
>
> Anyone heard of or saw this beastie ??
>
> Thsnks and HNY to all,
>
> Dick, W1KSZ 
>
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>
>   



From martinrh45 at googlemail.com  Mon Dec 29 18:46:11 2008
From: martinrh45 at googlemail.com (Martin Richmond-Hardy)
Date: Mon, 29 Dec 2008 18:46:11 +0000
Subject: [time-nuts] Fwd:  Trimble NTPX26AB-06 Software?
References: <EDF376E0-1BE7-4318-B5DC-B1A123F32244@googlemail.com>
Message-ID: <8D448620-C2FE-4BA2-BB7B-1AD7EBC50FFC@googlemail.com>

[forgot to cc original to the group]

Begin forwarded message:

> From: Martin Richmond-Hardy <martinrh45 at googlemail.com>
> Date: 29 December 2008 15:47:06 GMT
> To: john at pcsupportsolutions.com
> Subject: [time-nuts] Trimble NTPX26AB-06 Software?
>
> John,
> I bought one of these on eBay a few weeks ago, supplied with a  
> minidisk which I've only just managed to read (had to fire up an old  
> blue iMac). I was advised that they appear to be using the  
> thunderbolt monitor software at 9600 8 n 1 (which I downloaded from  
> the net at http://www.trimble.com/support_trl.asp?pt=Thunderbolt%C2%AEGPSDisciplinedClock&Nav=Collection-2357 
>  This runs on Windows xP. Interface is RS442 so needs a mod if your  
> PC only has RS232.
>
> Haven't managed to test it yet. Need to fire up another ancient  
> Windows machine as the VMWare Fusion emulator on my iMac won't drive  
> the serial ports (or rather, I haven't figured it out yet)
>
> Best of luck!
>
>
>
> 73 de
> Martin Richmond-Hardy G8BHC
> QTH: JO02pa
>
>
>
>
>


From masondg44 at comcast.net  Mon Dec 29 18:50:54 2008
From: masondg44 at comcast.net (Dave M)
Date: Mon, 29 Dec 2008 13:50:54 -0500
Subject: [time-nuts] Ovenaire OSC-48-11C Oscillator info?
Message-ID: <75DC56F3AB2442A8B8418590DADCEAF8@DELL2350>

Rummaging through my junquebox this weekend produced an Ovenaire OSC-48-11C 3MHz ovenized oscillator.  Googling for an hour or so produced little useful information.  Does anyone have data or a source for data on this unit?  It seems that Ovenaire went through several acquisitions over the years, eventually being swallowed up by Corning Frequency Products, which is nowhere to be found.

It has four terminals on the top of the unit; E1 through E4.  I'm sure that one is ground and one is the RF output.  Are the oven power and oscillator power separate (on the other two terminals) or tied together internally?
What are the oven and oscillator power voltages?
Is the oscillator able to be disciplined?  If so, what are the characteristics?

Any help is sincerely appreciated.
-- 
Dave M
MasonDG44 at comcast dot net  (Just substitute the appropriate characters in the address)

Life is like a roll of toilet paper; the closer it gets to the end, the faster it goes. 

From n3toy at yahoo.com  Mon Dec 29 18:58:28 2008
From: n3toy at yahoo.com (James R. Gorr)
Date: Mon, 29 Dec 2008 10:58:28 -0800 (PST)
Subject: [time-nuts] altitude difference between two gps
In-Reply-To: <057901c968bb$b71a3190$0a01a8c0@ATHLONXP1700>
Message-ID: <368350.26621.qm@web54108.mail.re2.yahoo.com>


It does appear to be a datum issue.  Although I never got the two GPS to match exactly, they are still a few meters apart.  I did find an older thread on the topic from March also.  Thanks for the replies!

Jamie

--- On Sat, 12/27/08, Ed, k1ggi <k1ggi at arrl.net> wrote:

> From: Ed, k1ggi <k1ggi at arrl.net>
> Subject: Re: [time-nuts] altitude difference between two gps
> To: "'Discussion of precise time and frequency measurement'" <time-nuts at febo.com>
> Date: Saturday, December 27, 2008, 11:12 PM
> On the thunderbolt, what datum do you have selected in Setup
> > Packet Masks
> and Options? If it is 0 (WGS-84), try 2 (NAD-27).
> -30m is about right for the geoid height around Las Vegas.
> Ed, k1ggi
> 
> -----Original Message-----
> From: James R. Gorr [mailto:n3toy at yahoo.com] 
> Sent: Saturday, December 27, 2008 9:26 PM
> To: time-nuts at febo.com
> Subject: [time-nuts] altitude difference between two gps
> 
> Hello everyone!
> 
> I have a tbolt that I am monitoring with tboltmon.exe and
> some off-brand 12
> channel GPS (I bought from Sure Electronics on eBay) that I
> am monitoring
> with VisualGPS.  Both are fed from the same GPS antenna
> through a
> symmetricom splitter.  There is a 30 meter difference in
> the altitude
> readings between the two.  My tbolt says my altitude (after
> a self-survey)
> is ~761 meters and the 12 channel Sure Electronics GPS says
> my altitude is
> ~791 meters after 7,500+ readings.  I took my hand held
> Garmin 12XL outside
> and it says my altitude is ~790 meters at street level.
> 
> Anyone have an idea why my tbolt might be reading different
> from the other
> two devices?  I am assuming the tbolt is reading low. 
> 
> Jamie
> 
> 
>       
> 
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
> 
> 
> 
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.


      


From rdarlington at gmail.com  Mon Dec 29 19:00:02 2008
From: rdarlington at gmail.com (Robert Darlington)
Date: Mon, 29 Dec 2008 12:00:02 -0700
Subject: [time-nuts] Help ID Display
In-Reply-To: <4705110.1230575359785.JavaMail.root@elwamui-rubis.atl.sa.earthlink.net>
References: <4705110.1230575359785.JavaMail.root@elwamui-rubis.atl.sa.earthlink.net>
Message-ID: <b3bd5fcb0812291100l62c9ba63h1bf74c1f3f37617c@mail.gmail.com>

Looks like a standard "Hitachi" LCD display.  You can find some info
on them here:  http://josepino.com/pic_projects/?hitachi_displays.jpc

-Bob

On Mon, Dec 29, 2008 at 11:29 AM, Richard W. Solomon
<w1ksz at earthlink.net> wrote:
> Not sure if this accepts attachments, but here goes ...
>
> Thanks, Dick, W1KSZ
>
> -----Original Message-----
>>From: Scott Newell <newell at cei.net>
>>Sent: Dec 29, 2008 11:14 AM
>>To: time-nuts at febo.com
>>Subject: Re: [time-nuts] Help ID Display
>>
>>At 11:38 AM 12/29/2008 , Richard W. Solomon wrote:
>>>I have a nice looking display that I salvaged from a piece of
>>>Cell Phone Site equipment. It's either a 4 X 20 or 4 X 40 display.
>>
>>Got pics?  What's the connector look like?  Graphic LCD, character mode
>>LCD, VFD, LED, plasma, or?  Any chips/drivers on it?
>>
>>--
>>newell  N5TNL
>>
>>
>>_______________________________________________
>>time-nuts mailing list -- time-nuts at febo.com
>>To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>>and follow the instructions there.
>
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>


From cfharris at erols.com  Mon Dec 29 19:08:30 2008
From: cfharris at erols.com (Chuck Harris)
Date: Mon, 29 Dec 2008 14:08:30 -0500
Subject: [time-nuts] New topics (was Re: He isaTime-Nut	Troublemaker....)
In-Reply-To: <949C8C71AFC249B3866DA1068E79D089@didierhp>
References: <20081225142942.LIJC18445.eastrmmtao103.cox.net@eastrmimpo01.cox.net>	<4958E876.7060707@erols.com>
	<949C8C71AFC249B3866DA1068E79D089@didierhp>
Message-ID: <4959202E.5020002@erols.com>

That's what I would expect.  There would, of course be a fair bit
of low frequency beating and the like, but if kept to a long window, it
should average out to a bell curve that is exactly centered on the average
frequency of the references.

Now, I guess the companion question is: Of what use would it be?

-Chuck Harris

Didier wrote:
> I think you will get a narrow (how narrow will depend on how close they are
> in frequency and how many there are) band of noise centered around 10 MHz. 
> 
> Didier


From boyscout at gmail.com  Mon Dec 29 19:15:19 2008
From: boyscout at gmail.com (Matt Ettus)
Date: Mon, 29 Dec 2008 11:15:19 -0800
Subject: [time-nuts] Mini Circuits Power Meter PWR-6G+
Message-ID: <ad9f78230812291115s7c10ad4fi561645c220a97c5@mail.gmail.com>

I just got a Mini Circuits power meter, the PWR-6G+, which is good to
6 GHz, -30 dBm to +20dBm.  It hooks up by USB and is only $695.  Very
cool device, and quite accurate from what I can tell.  It's a nice
small package, just a sensor head with USB cable.


My only complaint is that I can't find Linux drivers for it.  Looks
like they use this chip:

   http://www.delcom-eng.com/DelcomCD/USBChips/USBChips.htm

So maybe it wouldn't be hard to talk to it.

Matt


From newell at cei.net  Mon Dec 29 19:21:16 2008
From: newell at cei.net (Scott Newell)
Date: Mon, 29 Dec 2008 13:21:16 -0600
Subject: [time-nuts] Help ID Display
In-Reply-To: <4705110.1230575359785.JavaMail.root@elwamui-rubis.atl.sa.e
	arthlink.net>
Message-ID: <200812291921.mBTJLHBa002832@mail962c35.nsolutionszone.com>

At 12:29 PM 12/29/2008 , Richard W. Solomon wrote:
>Not sure if this accepts attachments, but here goes ...

I doubt it's a 4x40--there's only one controller visible in the pic.  Maybe
a 2x40, 2x20, 2x16, etc.

The 2x8 connector isn't as common as a 2x7.  Most that I've seen tie the
backlight to pins 15 and 16.  You can beep it out to be sure.  (I don't see
a backlight on this one, so maybe the top two pins aren't used?)

Other than that, it looks very much like one of the common-as-dirt HD44780
based character LCD modules.

-- 
newell  N5TNL




From brooke at pacific.net  Mon Dec 29 19:42:04 2008
From: brooke at pacific.net (Brooke Clarke)
Date: Mon, 29 Dec 2008 11:42:04 -0800
Subject: [time-nuts] Help ID Display
In-Reply-To: <30097828.1230572296476.JavaMail.root@elwamui-rubis.atl.sa.earthlink.net>
References: <30097828.1230572296476.JavaMail.root@elwamui-rubis.atl.sa.earthlink.net>
Message-ID: <4959280C.6060302@pacific.net>

Hi Dick:

It's probably a standard HD44780 type character display.  Since the HD44780 is 
long obsolete you probably will not see that number on any of the ICs, the 
electrical and software interface is most likely compatible.
http://www.prc68.com/I/PIC16F88.shtml#LCD

The above link has some info on different ways to control them.  For example 
you can use a multi-wire parallel approach, or various ways to use fewer I/O 
pins on the uC.

Have Fun,

Brooke Clarke
http://www.prc68.com

Richard W. Solomon wrote:
> I have a nice looking display that I salvaged from a piece of
> Cell Phone Site equipment. It's either a 4 X 20 or 4 X 40 display.
> 
> The only markings on it are:
> KL SN102 94V-0
> and the letters VL in a square box.
> 
> I Googled it and saw others in France and Otaly looking for similar
> info, but no answers yet.
> 
> It might make a nifty display for a stand-alone GPS Monitor.
> 
> Anyone heard of or saw this beastie ??
> 
> Thsnks and HNY to all,
> 
> Dick, W1KSZ 
> 
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
> 
> 



From magnus at rubidium.dyndns.org  Mon Dec 29 22:14:23 2008
From: magnus at rubidium.dyndns.org (Magnus Danielson)
Date: Mon, 29 Dec 2008 23:14:23 +0100
Subject: [time-nuts] New topics (was Re: He isaTime-Nut	Troublemaker....)
In-Reply-To: <4959202E.5020002@erols.com>
References: <20081225142942.LIJC18445.eastrmmtao103.cox.net@eastrmimpo01.cox.net>	<4958E876.7060707@erols.com>	<949C8C71AFC249B3866DA1068E79D089@didierhp>
	<4959202E.5020002@erols.com>
Message-ID: <49594BBF.2080509@rubidium.dyndns.org>

Chuck Harris skrev:
> That's what I would expect.  There would, of course be a fair bit
> of low frequency beating and the like, but if kept to a long window, it
> should average out to a bell curve that is exactly centered on the average
> frequency of the references.

Which I would guess would be adrift, so it would be kind of hard.

Actually, I wonder if it for two unsynchronized clocks would look like 
an amplitude or phase modulated signal with a sine modulation. This 
would cause a very typical sine-modulation curve on the histogram, and 
with gaussian bell shaped outer edges. You would need to lock them up 
for this hollow shape to fall out and it all become just a bell-shape.

> Now, I guess the companion question is: Of what use would it be?

If they are free-running, I think the functionality is fairly unuseful.
If you lock them up, well, that's another issue.

Cheers,
Magnus


From holrum at hotmail.com  Mon Dec 29 22:29:46 2008
From: holrum at hotmail.com (Mark Sims)
Date: Mon, 29 Dec 2008 22:29:46 +0000
Subject: [time-nuts] Help ID Display
In-Reply-To: <mailman.856.1230588874.2499.time-nuts@febo.com>
References: <mailman.856.1230588874.2499.time-nuts@febo.com>
Message-ID: <BLU125-W436BDD0B5550AEA681CA5FCEE60@phx.gbl>


Although the pinouts are fairly standard for most displays beware of a few common variations: 
+5V and GND can be reversed
The backlight connections can be reversed.  Backlights are usually LED without an on board current limit resistor.  The LED is usually a fairly high current device/devices (up to 500mA!,  but 30mA will usually work well enough for a night-light display).   Some modules use EL backlights that are driven by high voltage (around 100V, 400Hz) AC.
The connections to the bias generator can be different.  Some displays have an on-board bias supply,  others require an external supply.  Most need the external bias voltage control pot (usually around 10K-20K).
Sometimes a pin on the connector is a display enable pin of either active high or low polarity.  If present,  it is usually biased ON with an internal resistor.
_________________________________________________________________
Life on your PC is safer, easier, and more enjoyable with Windows Vista?. 
http://clk.atdmt.com/MRT/go/127032870/direct/01/

From eb4apl at cembreros.jazztel.es  Tue Dec 30 00:44:12 2008
From: eb4apl at cembreros.jazztel.es (EB4APL)
Date: Tue, 30 Dec 2008 01:44:12 +0100
Subject: [time-nuts] altitude difference between two gps
In-Reply-To: <264215.54635.qm@web54106.mail.re2.yahoo.com>
References: <264215.54635.qm@web54106.mail.re2.yahoo.com>
Message-ID: <49596EDC.1050307@cembreros.jazztel.es>

James, 
I suppose the GPS you bought at Sure Electronics is the demo board with 
the Skylab module.
Did you made any test to know if  it has a reliable PPS output that can 
be used for timing?  I?m considering to buy one.

Your question about the height difference is almost sure due to 
different datums in each receiver, as others had pointed out.

Best regards,
Ignacio, EB4APL


James R. Gorr wrote:
> Hello everyone!
>
> I have a tbolt that I am monitoring with tboltmon.exe and some off-brand 12 channel GPS (I bought from Sure Electronics on eBay) that I am monitoring with VisualGPS.  Both are fed from the same GPS antenna through a symmetricom splitter.  There is a 30 meter difference in the altitude readings between the two.  My tbolt says my altitude (after a self-survey) is ~761 meters and the 12 channel Sure Electronics GPS says my altitude is ~791 meters after 7,500+ readings.  I took my hand held Garmin 12XL outside and it says my altitude is ~790 meters at street level.
>
> Anyone have an idea why my tbolt might be reading different from the other two devices?  I am assuming the tbolt is reading low. 
>
> Jamie
>  



From holrum at hotmail.com  Tue Dec 30 04:35:15 2008
From: holrum at hotmail.com (Mark Sims)
Date: Tue, 30 Dec 2008 04:35:15 +0000
Subject: [time-nuts] Did Santa Claus bring you anything time-nutty?
In-Reply-To: <mailman.856.1230588874.2499.time-nuts@febo.com>
References: <mailman.856.1230588874.2499.time-nuts@febo.com>
Message-ID: <BLU125-W3488DF4ADA165C7A481540CEE70@phx.gbl>


I got a Klein bottle.  I am going to use it to capture and store my leap second.  I'll save the leap second for a rainy day (or perhaps auction it off on Ebay).
_________________________________________________________________
Send e-mail faster without improving your typing skills.
http://windowslive.com/online/hotmail?ocid=TXT_TAGLM_WL_hotmail_acq_speed_122008

From sar10538 at gmail.com  Tue Dec 30 05:11:06 2008
From: sar10538 at gmail.com (Steve Rooke)
Date: Tue, 30 Dec 2008 18:11:06 +1300
Subject: [time-nuts] Deriving PPS from hockey-puck G-Mouse GPS receiver
	to lock an oscillator
In-Reply-To: <1230563511.20850.37.camel@bg-desktop>
References: <1231b6a80812290546l6f0e802eq2aaf01758e8e5667@mail.gmail.com>
	<1230563511.20850.37.camel@bg-desktop>
Message-ID: <1231b6a80812292111j83fb6cdr91259e05243d583@mail.gmail.com>

Bj?rn,

Thanks for your response.

2008/12/30 Bj?rn Gabrielsson <bg at lysator.liu.se>:
>
> On Tue, 2008-12-30 at 02:46 +1300, Steve Rooke wrote:
>
> Measuring is more fun than theoretical pondering... so start there. ;-)

Indeed, although in this case I am not measuring absolute time, I'm
just trying to sync a GPSDO.

> Try to measure the jitter on that 1Hz signal. Either with "external"
> hardware, or software. One way to do this is by configuring the GPS as a
> refclock to a computer running NTP.
>
>  http://www.eecis.udel.edu/~mills/ntp/html/drivers/driver20.html

Thanks for the link but I will just be deriving the PPS and running it
in on something like CD or so.

> When you have the computer running you can query NTP of what kind of
> jitter it sees. Look at the last column in the query below. With a few
> external network servers you can also estimate approximate delay or
> offset. Both are in milliseconds below.
>
> NOTE: The GENERIC clock here IS using PPS.
>
> $ ntpq -c pe timehost.lysator.liu.se
>     remote       refid    st t when poll reach   delay   offset  jitter
> ==============================================================================
> *GENERIC(0)      .GPS.     0 l   64   64  377    0.000    0.001   0.002
> +nissan.ifm.liu. .PPS.     1 u  644 1024  377    0.655   -0.009   0.033
> +ntp1.sth.netnod .PPS.     1 u  593 1024  377    3.661   -0.037   0.053
> +ntp2.gbg.netnod .PPS.     1 u  619 1024  377   10.967   -0.025   0.042
> -ntp1.mmo.netnod .PPS.     1 u  623 1024  377   13.933   -0.097   0.050
>
> Last time I tried a NMEA without PPS i got jitter of about 10ms. Delay
> (offset) was a few hundred ms.

I would not expect that the absolute time from my PPS would be highly
accurate for this purpose. Wouldn't the jitter be filtered out by a
low pass filter following the phase-frequency detector in a GPSDO
using the method I propose?

> Why is NMEA probably the worst way to get time out of a generic GPS
> receiver?

Sorry, this is off-topic for me.

> The receiver has more important stuff to do than putting the first bit
> of a long serial message on a slow 4800baud link exactly at the correct
> time. If the receiver is busy tending to its correlator chip. Serial
> output will have to wait.
>
> There are often two serial protocols implemented in the receiver. A
> binary format different for each manufacturer. Trimble has TSIP, SIRF
> Binary etc. This require less CPU to generate than the ascii NMEA. The
> binary protocol often has better timing.
>
> The number of CPU cycles to compute a PVT solution is not constant. With
> 4 satelite measurements its quicker than with 12 SVs in view.
>
> If the NMEA output is the task with lowest priority in the receiver the
> leading pulse timing accuracy will suffer.
>
> There are sometimes a short binary timing message that have better
> specifications on jitter and offset. This would probably be an order of
> magnitude better than NMEA. A real PPS would be another 3 or so
> magnitudes better.
>
> There are surely exceptions to the above arguments not to use straight
> NMEA. Measuring the performance over some time of cause gives you the
> best answer for your particular GPS.
>
> good luck!

Thanks & 73,
Steve
-- 
Steve Rooke - ZL3TUV & G8KVD & JAKDTTNW
Omnium finis imminet


From sar10538 at gmail.com  Tue Dec 30 05:21:13 2008
From: sar10538 at gmail.com (Steve Rooke)
Date: Tue, 30 Dec 2008 18:21:13 +1300
Subject: [time-nuts] Deriving PPS from hockey-puck G-Mouse GPS receiver
	to lock an oscillator
In-Reply-To: <BLU125-W153ACD5559C8C8AA8F92EACEE60@phx.gbl>
References: <mailman.849.1230563517.2499.time-nuts@febo.com>
	<BLU125-W153ACD5559C8C8AA8F92EACEE60@phx.gbl>
Message-ID: <1231b6a80812292121j602fa4dfvdde228c653d915db@mail.gmail.com>

Mark,

2008/12/30 Mark Sims <holrum at hotmail.com>:
>
> A long time ago, I did something very similar with an early release Magellan 5000 board  (and a couple of other models of GPS cards) that did not implement the 1PPS signal.  I think the best time sync that I ever got was around 1 mS (most boards were around 10 mS).

I'm not actually looking at time syncing, only making a GPSDO.

> True 1PPS signals are implemented and synchronized in hardware.  The NMEA messages are generated in software.  Due to the vagaries of things like software interrupt latencies,  serial port bit synchronization, etc I doubt that you could ever get better than 1 serial bit time of accuracy out of any board and 10-100 bit times is more likely.  At 4800 bits/sec the jitter/offset of even 1 bit time would be huge at best.  Perfectly OK for things like clock displays,  but totally inadequate for things like oscillator locking.

Ok, so I can see what you mean about jitter but would that not be
taken care of by a low pass filter with a reasonable time constant
following phase-frequency detection between the PPS and a divided down
ocxo? Agreed the short term stability (ADEV for small tao?) would be
poor but would it not improve significantly in the longer term (ADEV
for large tao?)? As for offset against an absolute PPS synced to GPS
time, well this is not important to me.

73, Steve
-- 
Steve Rooke - ZL3TUV & G8KVD & JAKDTTNW
Omnium finis imminet


From sar10538 at gmail.com  Tue Dec 30 05:30:19 2008
From: sar10538 at gmail.com (Steve Rooke)
Date: Tue, 30 Dec 2008 18:30:19 +1300
Subject: [time-nuts] Count up/down DAC circuit
Message-ID: <1231b6a80812292130r623ac2d3jbc36240512674384@mail.gmail.com>

As part of the current idea I have with the hockey-pucks, I'm thinking
about feeding the D1 and U1 phase difference pulses out of an MC4044
out to some circuit that could clock up and down an analog output
which would ultimately go to the EFC of a ocxo, IE D1 pulses when the
phase of one input signal is advanced and visa versa for the U1 pin.
Anyone seen a circuit like that please?

Thanks & 73, Steve
-- 
Steve Rooke - ZL3TUV & G8KVD & JAKDTTNW
Omnium finis imminet


From bruce.griffiths at xtra.co.nz  Tue Dec 30 05:57:32 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Tue, 30 Dec 2008 18:57:32 +1300
Subject: [time-nuts] Count up/down DAC circuit
In-Reply-To: <1231b6a80812292130r623ac2d3jbc36240512674384@mail.gmail.com>
References: <1231b6a80812292130r623ac2d3jbc36240512674384@mail.gmail.com>
Message-ID: <4959B84C.7070404@xtra.co.nz>

Steve Rooke wrote:
> As part of the current idea I have with the hockey-pucks, I'm thinking
> about feeding the D1 and U1 phase difference pulses out of an MC4044
> out to some circuit that could clock up and down an analog output
> which would ultimately go to the EFC of a ocxo, IE D1 pulses when the
> phase of one input signal is advanced and visa versa for the U1 pin.
> Anyone seen a circuit like that please?
>
> Thanks & 73, Steve
>   
Steve

It could be done using a  capacitive charge dispenser based circuit
feeding an analog integrator.

Bruce


From bruce.griffiths at xtra.co.nz  Tue Dec 30 06:06:58 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Tue, 30 Dec 2008 19:06:58 +1300
Subject: [time-nuts] Deriving PPS from hockey-puck G-Mouse GPS receiver
 to lock an oscillator
In-Reply-To: <1231b6a80812292121j602fa4dfvdde228c653d915db@mail.gmail.com>
References: <mailman.849.1230563517.2499.time-nuts@febo.com>	<BLU125-W153ACD5559C8C8AA8F92EACEE60@phx.gbl>
	<1231b6a80812292121j602fa4dfvdde228c653d915db@mail.gmail.com>
Message-ID: <4959BA82.2030901@xtra.co.nz>

Steve Rooke wrote:
> Mark,
>
> 2008/12/30 Mark Sims <holrum at hotmail.com>:
>   
>> A long time ago, I did something very similar with an early release Magellan 5000 board  (and a couple of other models of GPS cards) that did not implement the 1PPS signal.  I think the best time sync that I ever got was around 1 mS (most boards were around 10 mS).
>>     
>
> I'm not actually looking at time syncing, only making a GPSDO.
>
>   
>> True 1PPS signals are implemented and synchronized in hardware.  The NMEA messages are generated in software.  Due to the vagaries of things like software interrupt latencies,  serial port bit synchronization, etc I doubt that you could ever get better than 1 serial bit time of accuracy out of any board and 10-100 bit times is more likely.  At 4800 bits/sec the jitter/offset of even 1 bit time would be huge at best.  Perfectly OK for things like clock displays,  but totally inadequate for things like oscillator locking.
>>     
>
> Ok, so I can see what you mean about jitter but would that not be
> taken care of by a low pass filter with a reasonable time constant
> following phase-frequency detection between the PPS and a divided down
> ocxo? Agreed the short term stability (ADEV for small tao?) would be
> poor but would it not improve significantly in the longer term (ADEV
> for large tao?)? As for offset against an absolute PPS synced to GPS
> time, well this is not important to me.
>
> 73, Steve
>   
Steve

Instead of waxing lyrically try doing some estimates of the averaging
time required for a given accuracy:
You need to measure the ADEV of the reference source (ie the relevant
NMEA sentence).

As a crude model say the jitter is 10 millisec of white phase noise and
you want the GPSDO to be within 1ppm for averaging times from  1 sec  to
a time equal to the loop time constant then
the loop time constant will have to be about 3 hours.
If you hope to achieve 1E-9 averaging over something like 3000 hours
will be required.
Whilst one can achieve lower noise by averaging the GPSDO over a day or
so, this may not be what you want.
Aging and thermal drift of the OCXO over 3000 hours will make it
impractical to achieve a stability of 1E-9.


Bruce


From john at pcsupportsolutions.com  Tue Dec 30 06:37:21 2008
From: john at pcsupportsolutions.com (John Allen)
Date: Tue, 30 Dec 2008 01:37:21 -0500
Subject: [time-nuts] Fwd:  Trimble NTPX26AB-06 Software?
In-Reply-To: <8D448620-C2FE-4BA2-BB7B-1AD7EBC50FFC@googlemail.com>
References: <EDF376E0-1BE7-4318-B5DC-B1A123F32244@googlemail.com>
	<8D448620-C2FE-4BA2-BB7B-1AD7EBC50FFC@googlemail.com>
Message-ID: <B2FD666D055A4CBA949CA50FCF1F95CE@JAOpti755>

Thanks Martin.  Please let me know how things come out and I will do the
same when my unit arrives.

73 to all, and to all a Happy New Year, John K1AE

-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of Martin Richmond-Hardy
Sent: Monday, December 29, 2008 1:46 PM
To: time-nuts at febo.com
Subject: [time-nuts] Fwd: Trimble NTPX26AB-06 Software?

[forgot to cc original to the group]

Begin forwarded message:

> From: Martin Richmond-Hardy <martinrh45 at googlemail.com>
> Date: 29 December 2008 15:47:06 GMT
> To: john at pcsupportsolutions.com
> Subject: [time-nuts] Trimble NTPX26AB-06 Software?
>
> John,
> I bought one of these on eBay a few weeks ago, supplied with a  
> minidisk which I've only just managed to read (had to fire up an old  
> blue iMac). I was advised that they appear to be using the  
> thunderbolt monitor software at 9600 8 n 1 (which I downloaded from  
> the net at
http://www.trimble.com/support_trl.asp?pt=Thunderbolt%C2%AEGPSDisciplinedClo
ck&Nav=Collection-2357 
>  This runs on Windows xP. Interface is RS442 so needs a mod if your  
> PC only has RS232.
>
> Haven't managed to test it yet. Need to fire up another ancient  
> Windows machine as the VMWare Fusion emulator on my iMac won't drive  
> the serial ports (or rather, I haven't figured it out yet)
>
> Best of luck!
>
>
>
> 73 de
> Martin Richmond-Hardy G8BHC
> QTH: JO02pa
>
>
>
>
>

_______________________________________________
time-nuts mailing list -- time-nuts at febo.com
To unsubscribe, go to
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.



From sar10538 at gmail.com  Tue Dec 30 07:29:24 2008
From: sar10538 at gmail.com (Steve Rooke)
Date: Tue, 30 Dec 2008 20:29:24 +1300
Subject: [time-nuts] Count up/down DAC circuit
In-Reply-To: <4959B84C.7070404@xtra.co.nz>
References: <1231b6a80812292130r623ac2d3jbc36240512674384@mail.gmail.com>
	<4959B84C.7070404@xtra.co.nz>
Message-ID: <1231b6a80812292329o4ec333dajd90da9a1be925015@mail.gmail.com>

2008/12/30 Bruce Griffiths <bruce.griffiths at xtra.co.nz>:
> Steve Rooke wrote:
>> As part of the current idea I have with the hockey-pucks, I'm thinking
>> about feeding the D1 and U1 phase difference pulses out of an MC4044
>> out to some circuit that could clock up and down an analog output
>> which would ultimately go to the EFC of a ocxo, IE D1 pulses when the
>> phase of one input signal is advanced and visa versa for the U1 pin.
>> Anyone seen a circuit like that please?
>>
>> Thanks & 73, Steve
>>
> Steve
>
> It could be done using a  capacitive charge dispenser based circuit
> feeding an analog integrator.

Thanks Bruce, this is an interesting idea.

73, Steve
-- 
Steve Rooke - ZL3TUV & G8KVD & JAKDTTNW
Omnium finis imminet


From hmurray at megapathdsl.net  Tue Dec 30 14:41:42 2008
From: hmurray at megapathdsl.net (Hal Murray)
Date: Tue, 30 Dec 2008 06:41:42 -0800
Subject: [time-nuts] Count up/down DAC circuit
In-Reply-To: Message from "Steve Rooke" <sar10538@gmail.com> of "Tue,
	30 Dec 2008 18:30:19 +1300."
	<1231b6a80812292130r623ac2d3jbc36240512674384@mail.gmail.com> 
Message-ID: <20081230144143.0DF50BCD7@ip-64-139-1-69.sjc.megapath.net>


> As part of the current idea I have with the hockey-pucks, I'm thinking
> about feeding the D1 and U1 phase difference pulses out of an MC4044
> out to some circuit that could clock up and down an analog output
> which would ultimately go to the EFC of a ocxo, IE D1 pulses when the
> phase of one input signal is advanced and visa versa for the U1 pin.
> Anyone seen a circuit like that please? 

I assume that "clock up and down an analog output" means an up/down counter 
driving an A/D.

Digital logic needs a min pulse width on clocks.

The best I can think of right now would be to use each pulse to set a FF, run 
them through a synchronizer (pair of FFs), then bump the counter and clear 
the initial FF.  That is, build a small circuit running on another clean 
clock that looks for the input pulses.


-- 
These are my opinions, not necessarily my employer's.  I hate spam.





From SAIDJACK at aol.com  Tue Dec 30 17:46:51 2008
From: SAIDJACK at aol.com (SAIDJACK at aol.com)
Date: Tue, 30 Dec 2008 12:46:51 EST
Subject: [time-nuts] Count up/down DAC circuit
Message-ID: <bde.3bebfab1.368bb88b@aol.com>

Hi Steve,
 
I played with such a circuit a long time ago.
 
The slope is limited to the clocking of your circuit (one LSB digit per  
clock typ), which can present an issue if you cannot follow the OCXO's EFC  
changes fast enough. You could be chasing the OCXO voltage and this may lead to  
instability.
 
Even if it is "locked", the circuit will constantly be "chasing" the OCXO,  
unless you implement a dead-zone where the circuit stops counting up/down when  
you are close enough to your target frequency.
 
This chasing may cause the frequency to modulate up and down, and could  lead 
to large-scale oscillations.
 
Tough to get this to work properly, but with circuitry to add a deadzone,  
and to dampen the lock, and maybe to introduce gain (jump more than one LSB when 
 far off etc) it may work. Then again implementing a standard PI controller 
(in a  micro etc), and calculating it's stability etc is much easier than 
getting this  to work properly.
 
bye,
Said
 
 
In a message dated 12/29/2008 21:30:54 Pacific Standard Time,  
sar10538 at gmail.com writes:

As part  of the current idea I have with the hockey-pucks, I'm thinking
about  feeding the D1 and U1 phase difference pulses out of an MC4044
out to some  circuit that could clock up and down an analog output
which would  ultimately go to the EFC of a ocxo, IE D1 pulses when the
phase of one  input signal is advanced and visa versa for the U1 pin.
Anyone seen a  circuit like that please?

Thanks & 73, Steve
-- 
Steve Rooke  - ZL3TUV & G8KVD & JAKDTTNW
Omnium finis  imminet

_______________________________________________
time-nuts  mailing list -- time-nuts at febo.com
To unsubscribe, go to  https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the  instructions there.



From holrum at hotmail.com  Wed Dec 31 01:03:24 2008
From: holrum at hotmail.com (Mark Sims)
Date: Wed, 31 Dec 2008 01:03:24 +0000
Subject: [time-nuts] Thunderbolt hiccup
In-Reply-To: <mailman.3.1230638401.32613.time-nuts@febo.com>
References: <mailman.3.1230638401.32613.time-nuts@febo.com>
Message-ID: <BLU125-W25F330FC36B1C76D30D132CEE40@phx.gbl>


I have been using Thunderbolts for a couple of years now without a hitch.  Today something strange happened.  I checked my system at home this afternoon in preparation for The Leapsecond and noticed that the unit had been in holdover for the last 20,000 seconds.  All alarms were normal but the unit was showing no sats available and OCXO holdover mode.  The Thunderbolt processor was working normally. 

I moved the antenna to another unit and got signal just fine.  Restored the antenna to the original unit and got no sats.  Power cycled the unit and it recovered and started working just fine.  Not sure what caused the hiccup,  probably not a power glitch/spike.  The unit is on a heavily monitored/filtered/redundant/backed up power supply that will flag and record any power disturbances as short as a few nanoseconds.
_________________________________________________________________
Send e-mail faster without improving your typing skills.
http://windowslive.com/online/hotmail?ocid=TXT_TAGLM_WL_hotmail_acq_speed_122008

From sar10538 at gmail.com  Wed Dec 31 04:31:55 2008
From: sar10538 at gmail.com (Steve Rooke)
Date: Wed, 31 Dec 2008 17:31:55 +1300
Subject: [time-nuts] Count up/down DAC circuit
In-Reply-To: <bde.3bebfab1.368bb88b@aol.com>
References: <bde.3bebfab1.368bb88b@aol.com>
Message-ID: <1231b6a80812302031j76fec7bt664e6d67c573d932@mail.gmail.com>

Hi Said,

Yes, I could see that my idea would suffer from this hunting in the
locked state problem an was wondering if this could be perhaps 'cured'
with a simple low-pass filter stage between the count up/down DAC and
the EFC, IE, the DAC would hunt up and down with a duty cycle equal to
the difference between the two DAC levels filtered by the LPF, thereby
giving a constant frequency.

This, of course, would further exasperate any problems trying to lock
a fast moving oxco or achieving lock in the first place. Some tuning
of the LPF time constant would be required to stop ringing as the PLL
moved into lock.

Do you think that would work as it would probably be easier to
implement than something to implement a dead-zone?

As for achieving lock in the first place with this idea, I'm thinking
now that it could take a very lon time for the DAC to count up/down
with output from a phase detector at 1PPS.  I was really only thinking
about this whole idea as it seemed to be a natural to hold the EFC
voltage during lack of PPS if the GPS goes down. Without the PPS, the
phase detector will output no pulses so the DAC would remain frozen in
it's last state. Implementing a GPSDO via a phase detector followed by
a LPF would obviously be easier but in the absence of the PPS, I
imagine that leakage in the circuit would make the EFC voltage drift.
I guess I could buffer it with a source-follower or something like
that, or perhaps some form of sample and hokld circuit.

I was just bouncing around ideas as I know there are a lot of great
brains on this list.

73, Steve

2008/12/31  <SAIDJACK at aol.com>:
> Hi Steve,
>
> I played with such a circuit a long time ago.
>
> The slope is limited to the clocking of your circuit (one LSB digit per
> clock typ), which can present an issue if you cannot follow the OCXO's EFC
> changes fast enough. You could be chasing the OCXO voltage and this may lead to
> instability.
>
> Even if it is "locked", the circuit will constantly be "chasing" the OCXO,
> unless you implement a dead-zone where the circuit stops counting up/down when
> you are close enough to your target frequency.
>
> This chasing may cause the frequency to modulate up and down, and could  lead
> to large-scale oscillations.
>
> Tough to get this to work properly, but with circuitry to add a deadzone,
> and to dampen the lock, and maybe to introduce gain (jump more than one LSB when
>  far off etc) it may work. Then again implementing a standard PI controller
> (in a  micro etc), and calculating it's stability etc is much easier than
> getting this  to work properly.
>
> bye,
> Said
>
>
> In a message dated 12/29/2008 21:30:54 Pacific Standard Time,
> sar10538 at gmail.com writes:
>
> As part  of the current idea I have with the hockey-pucks, I'm thinking
> about  feeding the D1 and U1 phase difference pulses out of an MC4044
> out to some  circuit that could clock up and down an analog output
> which would  ultimately go to the EFC of a ocxo, IE D1 pulses when the
> phase of one  input signal is advanced and visa versa for the U1 pin.
> Anyone seen a  circuit like that please?
>
> Thanks & 73, Steve
> --
> Steve Rooke  - ZL3TUV & G8KVD & JAKDTTNW
> Omnium finis  imminet
>
> _______________________________________________
> time-nuts  mailing list -- time-nuts at febo.com
> To unsubscribe, go to  https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the  instructions there.
>
>
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>



-- 
Steve Rooke - ZL3TUV & G8KVD & JAKDTTNW
Omnium finis imminet


From magnus at rubidium.dyndns.org  Wed Dec 31 07:00:12 2008
From: magnus at rubidium.dyndns.org (Magnus Danielson)
Date: Wed, 31 Dec 2008 08:00:12 +0100
Subject: [time-nuts] Capturing CHU frequency switchover
Message-ID: <495B187C.1020503@rubidium.dyndns.org>

Hi!

I don't have the equipment for it, but I am sure that a ham near would 
be able to pull this off. Here the deal:

"After seventy years of broadcasting Canada's official time, NRC's 
shortwave station CHU will move the transmission frequency for the 7335 
KHz transmitter to 7850 KHz. The change will occur on 01 January 2009 at 
00:00 UTC."

Now, as this happends at the same time as the leap second, it would be 
kind of cool recording both the old and new CHU transmissions on left 
and right channel of a stereo-pair. That should capture leap-second and 
frequency switchover.

Just a thought for the hams out there in North America.

Cheers,
Magnus


From namichie at gmail.com  Wed Dec 31 12:39:08 2008
From: namichie at gmail.com (Neville Michie)
Date: Wed, 31 Dec 2008 23:39:08 +1100
Subject: [time-nuts] Capturing CHU frequency switchover
In-Reply-To: <495B187C.1020503@rubidium.dyndns.org>
References: <495B187C.1020503@rubidium.dyndns.org>
Message-ID: <A149A2C0-9FE2-4A61-B6CE-DAF9E2DB8FF6@gmail.com>

Over here in Australia there are no time services to see/hear the  
leap second.
WWV is available but only during the night.
The leap second will be here about 10AM so I will not be able to hear  
WWV.
If WWV does something notable I would love it if some one could make  
a sound clip of it.

Have a precise, accurate, happy and very prosperous New Year,
Neville Michie


On 31/12/2008, at 6:00 PM, Magnus Danielson wrote:

> Hi!
>
> I don't have the equipment for it, but I am sure that a ham near would
> be able to pull this off. Here the deal:
>
> "After seventy years of broadcasting Canada's official time, NRC's
> shortwave station CHU will move the transmission frequency for the  
> 7335
> KHz transmitter to 7850 KHz. The change will occur on 01 January  
> 2009 at
> 00:00 UTC."
>
> Now, as this happends at the same time as the leap second, it would be
> kind of cool recording both the old and new CHU transmissions on left
> and right channel of a stereo-pair. That should capture leap-second  
> and
> frequency switchover.
>
> Just a thought for the hams out there in North America.
>
> Cheers,
> Magnus
>
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/ 
> time-nuts
> and follow the instructions there.



From jra at febo.com  Wed Dec 31 14:48:19 2008
From: jra at febo.com (John Ackermann N8UR)
Date: Wed, 31 Dec 2008 09:48:19 -0500
Subject: [time-nuts] Capturing CHU frequency switchover
In-Reply-To: <495B187C.1020503@rubidium.dyndns.org>
References: <495B187C.1020503@rubidium.dyndns.org>
Message-ID: <495B8633.3030701@febo.com>

Magnus, you read my mind!  I'm planning to record 7335 on one channel,
and 7850 on the other.  The only problem is that my wire antenna blew
down in the last wind storm, so I only have a vertical and I'm not sure
how that will work.

John
----

Magnus Danielson said the following on 12/31/2008 02:00 AM:
> Hi!
> 
> I don't have the equipment for it, but I am sure that a ham near would 
> be able to pull this off. Here the deal:
> 
> "After seventy years of broadcasting Canada's official time, NRC's 
> shortwave station CHU will move the transmission frequency for the 7335 
> KHz transmitter to 7850 KHz. The change will occur on 01 January 2009 at 
> 00:00 UTC."
> 
> Now, as this happends at the same time as the leap second, it would be 
> kind of cool recording both the old and new CHU transmissions on left 
> and right channel of a stereo-pair. That should capture leap-second and 
> frequency switchover.
> 
> Just a thought for the hams out there in North America.
> 
> Cheers,
> Magnus
> 
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.


From newell at cei.net  Wed Dec 31 15:01:20 2008
From: newell at cei.net (Scott Newell)
Date: Wed, 31 Dec 2008 09:01:20 -0600
Subject: [time-nuts] Capturing CHU frequency switchover
In-Reply-To: <A149A2C0-9FE2-4A61-B6CE-DAF9E2DB8FF6@gmail.com>
References: <495B187C.1020503@rubidium.dyndns.org>
	<495B187C.1020503@rubidium.dyndns.org>
Message-ID: <200812311501.mBVF1LJo013367@mail958c35.nsolutionszone.com>

At 06:39 AM 12/31/2008 , Neville Michie wrote:
>If WWV does something notable I would love it if some one could make  
>a sound clip of it.

I plan on recording the WWVB timecode (sampling the demodulated output of a
rat shack radio clock at 100Hz), logging a TAPR Thunderbolt, and doing an
audio recording of WWV.  I'd like to catch the CHU transition, but I'm not
sure I'll have time to set up another stereo recorder this evening.

What's everyone else planning on recording?


-- 
newell  N5TNL



From phk at phk.freebsd.dk  Wed Dec 31 15:18:49 2008
From: phk at phk.freebsd.dk (Poul-Henning Kamp)
Date: Wed, 31 Dec 2008 15:18:49 +0000
Subject: [time-nuts] Capturing CHU frequency switchover
In-Reply-To: Your message of "Wed, 31 Dec 2008 09:01:20 CST."
	<200812311501.mBVF1LJo013367@mail958c35.nsolutionszone.com> 
Message-ID: <50339.1230736729@critter.freebsd.dk>

In message <200812311501.mBVF1LJo013367 at mail958c35.nsolutionszone.com>, Scott Newell writes:
>At 06:39 AM 12/31/2008 , Neville Michie wrote:

>What's everyone else planning on recording?

I'm samling VLF up to about 200 kHz at 1MSPS which should give me
DCF77, MSF, HCG and Loran-C

I also run significant data-logging on a couple of NTP servers
running Oncore GPS and a single DCF77.

-- 
Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk at FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.


From n3izn at aol.com  Wed Dec 31 15:56:23 2008
From: n3izn at aol.com (n3izn at aol.com)
Date: Wed, 31 Dec 2008 10:56:23 -0500
Subject: [time-nuts] Need schoolin PPM vs E to the umth?
In-Reply-To: <495B8633.3030701@febo.com>
References: <495B187C.1020503@rubidium.dyndns.org> <495B8633.3030701@febo.com>
Message-ID: <8CB397776CBA6AC-494-179@WEBMAIL-MA02.sysops.aol.com>

So can any one bring it down a few clicks and explain the accuracy thing to this balding hippie?

I'm leaning towards ham radio applications. GPSDO are rated in one way like 1 X 10 to something. Ham radios are coming with "High Stability" oscillators that are rated in ? PPM.

In laymen's terms what do those numbers mean and how do they relate to each other?

Hope this doesn't start to much controversy on the board.

73
Chris




From ptdeboer at cs.utwente.nl  Wed Dec 31 15:57:23 2008
From: ptdeboer at cs.utwente.nl (Pieter-Tjerk de Boer)
Date: Wed, 31 Dec 2008 16:57:23 +0100
Subject: [time-nuts] Capturing CHU frequency switchover
In-Reply-To: <200812311501.mBVF1LJo013367@mail958c35.nsolutionszone.com>
References: <495B187C.1020503@rubidium.dyndns.org>
	<495B187C.1020503@rubidium.dyndns.org>
	<200812311501.mBVF1LJo013367@mail958c35.nsolutionszone.com>
Message-ID: <20081231155723.GO12719@cs.utwente.nl>


On Wed, Dec 31, 2008 at 09:01:20AM -0600, Scott Newell wrote:
> What's everyone else planning on recording?

I hope to record roughly the following parts of the radio spectrum:

    0 - 300 kHz    MSF, HBG, DCF, Loran, longwave broadcast
  700 - 1300 kHz   part of the medium-wave broadcast band
 4950 - 5100 kHz   Russian time signal at 4996 kHz, and perhaps WWV
 5950 - 6250 kHz   short-wave broadcast
 7100 - 7400 kHz   short-wave broadcast, and perhaps CHU
 7730 - 7880 kHz   new CHU frequency, if propagation permits

However, I have some local noise around 59 kHz which will probably
destroy MSF's signal, and I'm pessimistic about propagation from
Canada to here (the Netherlands) for CHU.
And since I will not be at home at the time, it will all have to
run unattended as a cron job, hopefully nothing goes wrong...

Regards,
  Pieter-Tjerk, PA3FWM
  


From jmfranke at cox.net  Wed Dec 31 16:07:29 2008
From: jmfranke at cox.net (John Franke)
Date: Wed, 31 Dec 2008 11:07:29 -0500
Subject: [time-nuts] Need schoolin PPM vs E to the umth?
References: <495B187C.1020503@rubidium.dyndns.org> <495B8633.3030701@febo.com>
	<8CB397776CBA6AC-494-179@WEBMAIL-MA02.sysops.aol.com>
Message-ID: <F49F693D76564409B36895CA5793C611@youre7075dc078>

1 PPM is one part per million or 1 X 10^-6.  An uncertainty of 1 PPM for a 
frequency of 1 MHz would mean an uncertainty of 1 Hz.  At 3.5 MHz, the 
uncertainty would be 3.5 Hz.  An accuracy of 1 X 10^-10 is 10,000, or 10^4, 
times better than 1 X 10^-6. 1 X 10^-10 is equivalent to 0.0001 PPM.

John WA4WDL

----- Original Message ----- 
From: <n3izn at aol.com>
To: <time-nuts at febo.com>
Sent: Wednesday, December 31, 2008 10:56 AM
Subject: [time-nuts] Need schoolin PPM vs E to the umth?


> So can any one bring it down a few clicks and explain the accuracy thing 
> to this balding hippie?
>
> I'm leaning towards ham radio applications. GPSDO are rated in one way 
> like 1 X 10 to something. Ham radios are coming with "High Stability" 
> oscillators that are rated in ? PPM.
>
> In laymen's terms what do those numbers mean and how do they relate to 
> each other?
>
> Hope this doesn't start to much controversy on the board.
>
> 73
> Chris
>
>
>
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to 
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
> 



From cfharris at erols.com  Wed Dec 31 17:30:39 2008
From: cfharris at erols.com (Chuck Harris)
Date: Wed, 31 Dec 2008 12:30:39 -0500
Subject: [time-nuts] Need schoolin PPM vs E to the umth?
In-Reply-To: <8CB397776CBA6AC-494-179@WEBMAIL-MA02.sysops.aol.com>
References: <495B187C.1020503@rubidium.dyndns.org> <495B8633.3030701@febo.com>
	<8CB397776CBA6AC-494-179@WEBMAIL-MA02.sysops.aol.com>
Message-ID: <495BAC3F.4020606@erols.com>

n3izn at aol.com wrote:
> So can any one bring it down a few clicks and explain the accuracy thing to this balding hippie?
> 
> I'm leaning towards ham radio applications. GPSDO are rated in one way like 1 X 10 to something. Ham radios are
> coming with "High Stability" oscillators that are rated in ? PPM.
> 
> In laymen's terms what do those numbers mean and how do they relate to each other?

They convey the same information as an accuracy percentage, only they
allow for an easier to understand number for higher stability sources.

For example, an oscillator that is accurate to 1%, is accurate to
one part in 100, or expressed in scientific notation, 1 part per 10E2.

Most people on this group consider that pretty (well awfully, actually)
crude.

As you get to more and more stable frequency sources, you might hear
of 1 part per million, or 1 PPM, or 1 part in 10E6.  In percentages,
that would be 0.0001%.

And as you become a time-nut, you start to talk of parts in 10E12, which
in percentages would be 0.0000000001%... Which is just too cumbersome
to use.  You have to count the zeros every time you look at the number,
and you still aren't sure what it means.

Any specification that tells of the accuracy of a frequency standard
needs some additional information... notably, a time frame over which
the accuracy is valid.  So you will hear things like 1PPM/year, or
1 part in 10E12 per second.

Some information about environmental conditions would also be useful.

Also, implicit in an accuracy specification is +/- which creates an
error band for the error to be contained within.

When one becomes a true time-nut, one starts to worry about trends in
stability issues, and at that point, statistical analysis becomes
important, and you start to talk of things like Allen-Variances.

-Chuck Harris
> 
> Hope this doesn't start to much controversy on the board.
> 
> 73 Chris
> 
> 
> 
> _______________________________________________ time-nuts mailing list -- time-nuts at febo.com To unsubscribe, go to
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
> 


From EWKehren at aol.com  Wed Dec 31 18:50:16 2008
From: EWKehren at aol.com (EWKehren at aol.com)
Date: Wed, 31 Dec 2008 13:50:16 EST
Subject: [time-nuts] Info on FEI rubidium
Message-ID: <c6a.46e478a6.368d18e8@aol.com>

I have a FE-5602B from Frequency Electronics. Can any one help me with info  
on pin out and specification. Thank you Bert Kehren WB5MZJ.  Ewkehren at AOL.com
**************New year...new news.  Be the first to know what is making 
headlines. (http://www.aol.com/?ncid=emlcntaolcom00000026)

From bruce.griffiths at xtra.co.nz  Wed Dec 31 21:55:43 2008
From: bruce.griffiths at xtra.co.nz (Bruce Griffiths)
Date: Thu, 01 Jan 2009 10:55:43 +1300
Subject: [time-nuts] Need schoolin PPM vs E to the umth?
In-Reply-To: <495BAC3F.4020606@erols.com>
References: <495B187C.1020503@rubidium.dyndns.org>
	<495B8633.3030701@febo.com>	<8CB397776CBA6AC-494-179@WEBMAIL-MA02.sysops.aol.com>
	<495BAC3F.4020606@erols.com>
Message-ID: <495BEA5F.4000405@xtra.co.nz>

Chuck

Chuck Harris wrote:
> n3izn at aol.com wrote:
>   
>> So can any one bring it down a few clicks and explain the accuracy thing to this balding hippie?
>>
>> I'm leaning towards ham radio applications. GPSDO are rated in one way like 1 X 10 to something. Ham radios are
>> coming with "High Stability" oscillators that are rated in ? PPM.
>>
>> In laymen's terms what do those numbers mean and how do they relate to each other?
>>     
>
> They convey the same information as an accuracy percentage, only they
> allow for an easier to understand number for higher stability sources.
>
> For example, an oscillator that is accurate to 1%, is accurate to
> one part in 100, or expressed in scientific notation, 1 part per 10E2.
>
>   
Wrong, it should read: 1 part in 1E2.
1E2 is actually shorthand for 1x10^2 .

For example see:
 http://en.wikipedia.org/wiki/Scientific_notation

This is the way the E notation is implemented on HP scientific calculators.

> Most people on this group consider that pretty (well awfully, actually)
> crude.
>
> As you get to more and more stable frequency sources, you might hear
> of 1 part per million, or 1 PPM, or 1 part in 10E6.  In percentages,
> that would be 0.0001%.
>
>   
1 PPM is 1 part in 1E6 .
You are just perpetuating a misinterpretation that was relatively common
in some old OCXO datasheets.
> And as you become a time-nut, you start to talk of parts in 10E12, which
> in percentages would be 0.0000000001%... Which is just too cumbersome
> to use.  You have to count the zeros every time you look at the number,
> and you still aren't sure what it means.
>
> Any specification that tells of the accuracy of a frequency standard
> needs some additional information... notably, a time frame over which
> the accuracy is valid.  So you will hear things like 1PPM/year, or
> 1 part in 10E12 per second.
>
>   
1 part in 10E12 per second is actually 1 part in 10^11 per second.
> Some information about environmental conditions would also be useful.
>
> Also, implicit in an accuracy specification is +/- which creates an
> error band for the error to be contained within.
>
> When one becomes a true time-nut, one starts to worry about trends in
> stability issues, and at that point, statistical analysis becomes
> important, and you start to talk of things like Allen-Variances.
>
> -Chuck Harris
>   
>> Hope this doesn't start to much controversy on the board.
>>
>> 73 Chris
>>
>>
>>
>>     

Bruce


From jra at febo.com  Wed Dec 31 22:00:22 2008
From: jra at febo.com (John Ackermann N8UR)
Date: Wed, 31 Dec 2008 17:00:22 -0500
Subject: [time-nuts] [Fwd: Morning show seeking time nut]
Message-ID: <495BEB76.8030000@febo.com>

Someone in New York, Washington, or a Canadian provincial capital
looking to become famous?  If so, please respond directly to Dagna.
They are looking for someone who can come into the studio.

John

-------- Original Message --------
Subject: 	Morning show seeking time nut
Date: 	Wed, 31 Dec 2008 16:27:01 -0500
From: 	Dagna Pielaszkiewicz <Dagna.Pielaszkiewicz at ctv.ca>
To: 	<jra at febo.com>



Dear John,



I?m a producer with CTV?s Canada AM, a national, live morning program.
We are very interested in speaking to a ?Time Nut? early next week.
Could you please let this out on the mailing list? Our interview would
have to be recorded sometime between 6 and 9 AM EST next week (our desk
generally picks the time slot), and we?d prefer someone located near
Washington DC, New York, or somewhere in Canada (we have a studio in
every province).



Best,



Dagna



From tvb at LeapSecond.com  Wed Dec 31 22:24:37 2008
From: tvb at LeapSecond.com (Tom Van Baak)
Date: Wed, 31 Dec 2008 14:24:37 -0800
Subject: [time-nuts] Fw: How to schedule a leap second on 5071A?
Message-ID: <F8372F73575540BBB1E6B9D30C17CD06@pc52>

Time-Nuts -- you still have a few hours to program your cesium
clocks for the leap second! Older clocks such as the HP 5060
and 5061 or FTS 4050 and 4060 don't have a mechanism to
add or delete a second, but most later model FTS, Datum, or
Symmetricom cesium clocks have a switch or a GUI to handle
leap seconds. See email below and attached photo for how to
update a 5071A.

As an aside, back in the early 90's when I first got into this
precision time hobby (see www.LeapSecond.com), "catching
the leap second" was something I very much looked forward to.

But now that I have a rather large collection of precision time
pieces, it turns out that leap seconds are a bit of a pain. It's
embarrassing to have a cesium clock sitting on a shelf, stable
to nanoseconds, but the time display is off by a second.

Anyway, over the next day please post reports of your own leap
second events; whether you have a cesium clock, a PC clock,
a GPSDO (HP,Agilent,Thunderbolt,Oncore,Fury,Jupiter,etc.).

A number of you did well during the last one a few years ago.
There are more subscribers on the list now so we might have
quite a variety of reports. No regular clocks bother with leap
seconds at all and a surprising number of laboratory or other
precision time instruments don't do it right. So catch them in
the act, if you can.

Too bad http://www.humanclock.com/ ignores leap seconds.

Thanks,
/tvb

<How to Watch a Leap Second>
http://leapsecond.com/notes/leap-watch.htm
<Time-Nuts -- Precise Time and Frequency for Amateurs>
http://leapsecond.com/time-nuts.htm

----- Original Message ----- 
From: "Tom Van Baak" <tvb at LeapSecond.com>
To: "Marat Konkanov" <marconzenti at ...>
Sent: Wednesday, December 31, 2008 12:21 AM
Subject: Re: How to schedule a leap second on 5071A?

> Hello Marat,
> 
> Thanks for your email; it is my first one from Kazakhstan.
> 
> You are correct; the last minute of Wednesday, December
> 31, 2008 will have 61 seconds instead of the usual 60. You
> can program your 5071A from the front panel menu using:
> Top -> CLOCK -> LEAPSEC -> MJD 54831 is 61 sec. See
> attached photo.
> 
> If you can, please take a picture of your 5071A when the
> leap second occurs later today and send it to me, OK?
> 
> Thanks,
> /tvb
> http://www.LeapSecond.com
> http://www.leapsecond.com/notes/leap-watch.htm
> 
> 
> ----- Original Message ----- 
> From: "Marat Konkanov" <marconzenti at ...>
> To: <tvb at LeapSecond.com>
> Sent: Tuesday, December 30, 2008 11:31 PM
> Subject: How to schedule a leap second on 5071A?
> 
>> Hello, Mr. Baak.
>>
>> My name is Marat. I am from Kazakhstan. I have got
>> Agilent 5071A. I know about the leap second in this year,
>> but I do not know how to schedule it.
>>
>> There are 2 values: 59 and 61 in 5071A MENU's. That
>> value should I choose? I think I must choose 61.
>>
>> Best regards,
>> Marat Konkanov
>> 
>
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From k1ggi at arrl.net  Wed Dec 31 22:29:31 2008
From: k1ggi at arrl.net (Ed, k1ggi)
Date: Wed, 31 Dec 2008 17:29:31 -0500
Subject: [time-nuts] Need schoolin PPM vs E to the umth?
In-Reply-To: <8CB397776CBA6AC-494-179@WEBMAIL-MA02.sysops.aol.com>
References: <495B187C.1020503@rubidium.dyndns.org> <495B8633.3030701@febo.com>
	<8CB397776CBA6AC-494-179@WEBMAIL-MA02.sysops.aol.com>
Message-ID: <041b01c96b97$428c6260$0a01a8c0@ATHLONXP1700>

Chris -

To help avoid too much confusion, it needs to be pointed out that this 'E'
notation gets used somewhat imprecisely in context, and you have to read
"what they meant" rather than "what they wrote".

In the convention of scientific E notation, Eb (sometimes eb) denotes a
factor whose value is 10 raised to the power b. 

see
http://en.wikipedia.org/wiki/Scientific_notation

(This has nothing to do with that mathematical 'e' that gets raised to all
sorts of powers in electronics, etc. -- eb does not mean 2.718... raised to
the power b.)

Examples:
3E2 = 3E+2 = 300, a number with two factors, the first being three and the
second being 10 to the power of positive two, or 100.
8E2 = 800
9E2 = 900
10E2 = 1000
1E2 = 100
10E1 = 100
Calculators such as Excel or Google deal with this notation.
No explicit symbol for a multiplication operator appears within the notation
itself, it is understood.

Compare this to caret notation, where
a^b denotes a raised to the power b.
3^2 = 9
10^2 = 100
3*10^2 = 300
And just for illustration,
e^-1 = 0.36... where this _is_ the 'other' e thing, 2.718....
Calculators also understand this notation.

Now, the values of 10^2 and 10E2 differ by a factor of 10.
3*10^2 = 300
3*10E2 = 3000
3*1E3 = 3000
3E3 = 3000

So here's the thing. When you read about 1 part in 10^2 or 1 part in 10E2,
you find that the writers quite often really meant the same thing,
regardless of the numbers being different, and you have to make a mental
adjustment.

On this list, where precision and accuracy are so highly regarded, this bit
of ambiguity is accommodated, but if you're not paying attention, a
calculation can be off by a factor of 10. Used equipment also gets described
this way when somebody has to type it up, so it pays to check original
manufacturer's specs.

With some savvy, it's a good bet that when you see a leading 10, i.e.
10Eanything, the writer meant to convey only the general notion of the
exponent, not the actual numeric value of the expression. This is because if
the actual value were intended, it would have been written as, say, 1E3
rather than 10E2. OTOH, any leading number other than 10, as in 9E2, doesn't
readily lend itself to misinterpretation. 10E2 literally means 1000, but may
need to be read as 100, whereas 9E2 always means 900. You would think that
if something goes from 9 to 10 it would come out bigger, but it doesn't.
See?

<snip>
>an oscillator that is accurate to 1%, is accurate to one part in 100, or
>expressed in scientific notation, 1 part per 10E2.
<snip>

10E2 is a number. If you put 1 over 10E2 into a calculator, it doesn't come
out 1%, it comes out 0.1%, 10 times smaller, but here the context reveals
the intent, so there you go. Intent is harder to figure out when there are a
dozen zeros floating around and there is less explanatory context.

So just be on guard when you see 10Eanything, check for reasonableness, and
consider embracing 1Eanything, which is unambiguous.

Not intending to drive anyone nuts,
Ed, k1ggi




From wb6bnq at cox.net  Wed Dec 31 22:44:15 2008
From: wb6bnq at cox.net (WB6BNQ)
Date: Wed, 31 Dec 2008 14:44:15 -0800
Subject: [time-nuts] Need schoolin PPM vs E to the umth?
References: <495B187C.1020503@rubidium.dyndns.org> <495B8633.3030701@febo.com>
	<8CB397776CBA6AC-494-179@WEBMAIL-MA02.sysops.aol.com>
	<041b01c96b97$428c6260$0a01a8c0@ATHLONXP1700>
Message-ID: <495BF5BF.13329343@cox.net>

Ed,

I think your Email was right on point and should not annoy anyone.  It is most
helpful to point out inconsistencies of a common nature.

I also have missused the "E" notation in exactly the way you discussed without
ever giving it a thought.  Now I will be constantly checking myself.

Bill....WB6BNQ


"Ed, k1ggi" wrote:

> Chris -
>
> To help avoid too much confusion, it needs to be pointed out that this 'E'
> notation gets used somewhat imprecisely in context, and you have to read
> "what they meant" rather than "what they wrote".
>
> In the convention of scientific E notation, Eb (sometimes eb) denotes a
> factor whose value is 10 raised to the power b.
>
> see
> http://en.wikipedia.org/wiki/Scientific_notation
>
> (This has nothing to do with that mathematical 'e' that gets raised to all
> sorts of powers in electronics, etc. -- eb does not mean 2.718... raised to
> the power b.)
>
> Examples:
> 3E2 = 3E+2 = 300, a number with two factors, the first being three and the
> second being 10 to the power of positive two, or 100.
> 8E2 = 800
> 9E2 = 900
> 10E2 = 1000
> 1E2 = 100
> 10E1 = 100
> Calculators such as Excel or Google deal with this notation.
> No explicit symbol for a multiplication operator appears within the notation
> itself, it is understood.
>
> Compare this to caret notation, where
> a^b denotes a raised to the power b.
> 3^2 = 9
> 10^2 = 100
> 3*10^2 = 300
> And just for illustration,
> e^-1 = 0.36... where this _is_ the 'other' e thing, 2.718....
> Calculators also understand this notation.
>
> Now, the values of 10^2 and 10E2 differ by a factor of 10.
> 3*10^2 = 300
> 3*10E2 = 3000
> 3*1E3 = 3000
> 3E3 = 3000
>
> So here's the thing. When you read about 1 part in 10^2 or 1 part in 10E2,
> you find that the writers quite often really meant the same thing,
> regardless of the numbers being different, and you have to make a mental
> adjustment.
>
> On this list, where precision and accuracy are so highly regarded, this bit
> of ambiguity is accommodated, but if you're not paying attention, a
> calculation can be off by a factor of 10. Used equipment also gets described
> this way when somebody has to type it up, so it pays to check original
> manufacturer's specs.
>
> With some savvy, it's a good bet that when you see a leading 10, i.e.
> 10Eanything, the writer meant to convey only the general notion of the
> exponent, not the actual numeric value of the expression. This is because if
> the actual value were intended, it would have been written as, say, 1E3
> rather than 10E2. OTOH, any leading number other than 10, as in 9E2, doesn't
> readily lend itself to misinterpretation. 10E2 literally means 1000, but may
> need to be read as 100, whereas 9E2 always means 900. You would think that
> if something goes from 9 to 10 it would come out bigger, but it doesn't.
> See?
>
> <snip>
> >an oscillator that is accurate to 1%, is accurate to one part in 100, or
> >expressed in scientific notation, 1 part per 10E2.
> <snip>
>
> 10E2 is a number. If you put 1 over 10E2 into a calculator, it doesn't come
> out 1%, it comes out 0.1%, 10 times smaller, but here the context reveals
> the intent, so there you go. Intent is harder to figure out when there are a
> dozen zeros floating around and there is less explanatory context.
>
> So just be on guard when you see 10Eanything, check for reasonableness, and
> consider embracing 1Eanything, which is unambiguous.
>
> Not intending to drive anyone nuts,
> Ed, k1ggi
>
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.



From magnus at rubidium.dyndns.org  Wed Dec 31 22:48:51 2008
From: magnus at rubidium.dyndns.org (Magnus Danielson)
Date: Wed, 31 Dec 2008 23:48:51 +0100
Subject: [time-nuts] Fw: How to schedule a leap second on 5071A?
In-Reply-To: <F8372F73575540BBB1E6B9D30C17CD06@pc52>
References: <F8372F73575540BBB1E6B9D30C17CD06@pc52>
Message-ID: <495BF6D3.6080103@rubidium.dyndns.org>

Tom Van Baak skrev:
> Time-Nuts -- you still have a few hours to program your cesium
> clocks for the leap second! Older clocks such as the HP 5060
> and 5061 or FTS 4050 and 4060 don't have a mechanism to
> add or delete a second, but most later model FTS, Datum, or
> Symmetricom cesium clocks have a switch or a GUI to handle
> leap seconds. See email below and attached photo for how to
> update a 5071A.
> 
> As an aside, back in the early 90's when I first got into this
> precision time hobby (see www.LeapSecond.com), "catching
> the leap second" was something I very much looked forward to.
> 
> But now that I have a rather large collection of precision time
> pieces, it turns out that leap seconds are a bit of a pain. It's
> embarrassing to have a cesium clock sitting on a shelf, stable
> to nanoseconds, but the time display is off by a second.
> 
> Anyway, over the next day please post reports of your own leap
> second events; whether you have a cesium clock, a PC clock,
> a GPSDO (HP,Agilent,Thunderbolt,Oncore,Fury,Jupiter,etc.).
> 
> A number of you did well during the last one a few years ago.
> There are more subscribers on the list now so we might have
> quite a variety of reports. No regular clocks bother with leap
> seconds at all and a surprising number of laboratory or other
> precision time instruments don't do it right. So catch them in
> the act, if you can.
> 
> Too bad http://www.humanclock.com/ ignores leap seconds.

Does your "web nixie clock" display the leap second properly?

BTW. One news reporter here in Sweden had the leap second noted down to 
be at 01:23:49 but I think they got it a little bit wrong.

Cheers,
Magnus


From tvb at LeapSecond.com  Wed Dec 31 23:43:54 2008
From: tvb at LeapSecond.com (Tom Van Baak)
Date: Wed, 31 Dec 2008 15:43:54 -0800
Subject: [time-nuts] Fw: How to schedule a leap second on 5071A?
References: <F8372F73575540BBB1E6B9D30C17CD06@pc52>
	<495BF6D3.6080103@rubidium.dyndns.org>
Message-ID: <95B4A4FBA9E240F3808BB388FDE2BFF6@pc52>

> Does your "web nixie clock" display the leap second properly?

Last I remember it did. I guess we'll find out in a few minutes...

http://www.leapsecond.com/java/nixie.htm

/tvb

> BTW. One news reporter here in Sweden had the leap second noted down to 
> be at 01:23:49 but I think they got it a little bit wrong.
> 
> Cheers,
> Magnus




From cfharris at erols.com  Wed Dec 31 23:47:23 2008
From: cfharris at erols.com (Chuck Harris)
Date: Wed, 31 Dec 2008 18:47:23 -0500
Subject: [time-nuts] Need schoolin PPM vs E to the umth?
In-Reply-To: <495BEA5F.4000405@xtra.co.nz>
References: <495B187C.1020503@rubidium.dyndns.org>	<495B8633.3030701@febo.com>	<8CB397776CBA6AC-494-179@WEBMAIL-MA02.sysops.aol.com>	<495BAC3F.4020606@erols.com>
	<495BEA5F.4000405@xtra.co.nz>
Message-ID: <495C048B.3020102@erols.com>

Bruce Griffiths wrote:
> Chuck
> 
> Chuck Harris wrote:
>> n3izn at aol.com wrote:
>>   
>>> So can any one bring it down a few clicks and explain the accuracy thing to this balding hippie?
>>>
>>> I'm leaning towards ham radio applications. GPSDO are rated in one way like 1 X 10 to something. Ham radios are
>>> coming with "High Stability" oscillators that are rated in ? PPM.
>>>
>>> In laymen's terms what do those numbers mean and how do they relate to each other?
>>>     
>> They convey the same information as an accuracy percentage, only they
>> allow for an easier to understand number for higher stability sources.
>>
>> For example, an oscillator that is accurate to 1%, is accurate to
>> one part in 100, or expressed in scientific notation, 1 part per 10E2.
>>
>>   
> Wrong, it should read: 1 part in 1E2.
> 1E2 is actually shorthand for 1x10^2 .

Right Bruce.  It must be fun being a pedant.  I'll bet you are
a hoot at parties.

I was writing for a person, not a fortran compiler.  My notation
was a simulation of normal scientific notation where I couldn't
specify superscripts... just as they used to do in old data sheets.

But then, you knew that.

-Chuck Harris


From sar10538 at gmail.com  Wed Dec 31 23:55:40 2008
From: sar10538 at gmail.com (Steve Rooke)
Date: Thu, 1 Jan 2009 12:55:40 +1300
Subject: [time-nuts] Need schoolin PPM vs E to the umth?
In-Reply-To: <495C048B.3020102@erols.com>
References: <495B187C.1020503@rubidium.dyndns.org> <495B8633.3030701@febo.com>
	<8CB397776CBA6AC-494-179@WEBMAIL-MA02.sysops.aol.com>
	<495BAC3F.4020606@erols.com> <495BEA5F.4000405@xtra.co.nz>
	<495C048B.3020102@erols.com>
Message-ID: <1231b6a80812311555k5088b2ccg7a3bb190fca4faf2@mail.gmail.com>

2009/1/1 Chuck Harris <cfharris at erols.com>:
> Bruce Griffiths wrote:
>> Chuck
>>
>> Chuck Harris wrote:
>>> n3izn at aol.com wrote:
>>>
>>>> So can any one bring it down a few clicks and explain the accuracy thing to this balding hippie?
>>>>
>>>> I'm leaning towards ham radio applications. GPSDO are rated in one way like 1 X 10 to something. Ham radios are
>>>> coming with "High Stability" oscillators that are rated in ? PPM.
>>>>
>>>> In laymen's terms what do those numbers mean and how do they relate to each other?
>>>>
>>> They convey the same information as an accuracy percentage, only they
>>> allow for an easier to understand number for higher stability sources.
>>>
>>> For example, an oscillator that is accurate to 1%, is accurate to
>>> one part in 100, or expressed in scientific notation, 1 part per 10E2.
>>>
>>>
>> Wrong, it should read: 1 part in 1E2.
>> 1E2 is actually shorthand for 1x10^2 .
>
> Right Bruce.  It must be fun being a pedant.  I'll bet you are
> a hoot at parties.
>
> I was writing for a person, not a fortran compiler.  My notation
> was a simulation of normal scientific notation where I couldn't
> specify superscripts... just as they used to do in old data sheets.
>
> But then, you knew that.

Geez, can someone get Bruce laid!
-- 
Steve Rooke - ZL3TUV & G8KVD & JAKDTTNW
Omnium finis imminet


From bogus@does.not.exist.com  Wed Dec  3 18:34:25 2008
From: bogus@does.not.exist.com ()
Date: Wed, 03 Dec 2008 18:34:25 -0000
Subject: No subject
Message-ID: <mailman.9.1231319132.2496.time-nuts@febo.com>

generating an accurate antenna height measurement due to the way GPS works. 
They  don't seem to have a problem generating good long/lat coordinates. But in  
timing, all three axis need to be precise unfortunately.
 
bye,
Said
 
 
In a message dated 1/6/2009 03:23:53 Pacific Standard Time,  
pvince at theiet.org writes:

Said  wrote:

>When we say units typically have 25ns unit-to-unit variation  on the 1PPS on 
 
>un-calibrated units, then I believe most of this  is caused by the 
auto-survey  
>position errors of the GPS  receiver. One could get much better performance 
by 
> manually entering  the exact position-hold position of the antenna, and 
then   
>calibrating for antenna cable delay (in 1ns steps).

A naive  question, if I may: how do I go about doing a precise manual 
position survey?  Is it simply a case of letting the unit self 
survey, then manually  entering different co-ordinates (say +/- 10 metres) in 
each of the three  directions in turn, watch the 
signal output, and try to tune for minimum  wobble?

Thanks,   Peter



From bogus@does.not.exist.com  Wed Dec  3 18:34:25 2008
From: bogus@does.not.exist.com ()
Date: Wed, 03 Dec 2008 18:34:25 -0000
Subject: No subject
Message-ID: <mailman.17.1234136964.2496.time-nuts@febo.com>

foot for a 22 Gage wire. We have seen that the OCXO current varies by 4mA over a 
 couple of days. This 4mA generates a ~65 microvolts delta across the ground  
wire.
 
The OCXO we use has about 40Hz delta per 5V change in EFC, or 8Hz/V, thus  we 
get:
 
   8Hz/V * 65microvolts = 516 microhertz change due to ground  loop, or 
~5.2E-011.
 
That's a fairly significant change just due to the ground loop.
 
This change is linear to OCXO current, which we can see  is inverse-linear to 
EFC voltage to keep the OCXO locked. So as the OCXO  current rises, the 
voltage drop across the ground wire would increase, so the  OCXO would see less EFC 
voltage on it's EFC pin.
 
So it could theoretically actually reduce the thermal sensitivity of the  
system, since the OCXO EFC needs to go down with rising OCXO current as can be  
seen in the plots I had sent out earlier!
 
BTW: the unit that was having large phase errors now stays locked within  
-10ns to +13ns, and has a SD of only 3ns over the last 52 hours. The unit now  
had enough time to learn, and is compensating very well now, you can see it in  
the attached plot or online.
 
bye,
Said
 
 
 
 
 
 
In a message dated 2/8/2009 15:07:08 Pacific Standard Time,  
tvb at LeapSecond.com writes:


I  still don't like unintended consequences. Did anyone try the
experiment to  move your OCXO off-board by a foot of cable?

That might help isolate  the root cause of the effect that you're
compensating for. Also, do you  know if all single/double OCXO
show the same correlation of frequency  output change vs. oven
current consumption change? This might be relevant  for anyone
taking a Fury board and using their own external  oscillator.



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--part1_c33.49700364.36c0c97b_boundary--


From bogus@does.not.exist.com  Wed Dec  3 18:34:25 2008
From: bogus@does.not.exist.com ()
Date: Wed, 03 Dec 2008 18:34:25 -0000
Subject: No subject
Message-ID: <mailman.18.1234639807.2496.time-nuts@febo.com>

components are available from third-party.=20

My target is to create a clone of that extension. I think it will not =
cost more than $50. Then, I=E2=80=99m planning to offer a =E2=80=9CDIY =
frequency extension kit=E2=80=9D for sales for all time enthusiasts and =
without making profit.  Every owner of a 53181A, 53131A will be able to =
add the nice freq extender for a fraction of the MSRP. But I need some =
help. The first thing to do is to find someone with an original -003, =
-005 or -124 extension and willing to scan (or take pictures of) the =
card in high resolution in order to reproduce the schematic and layout =
used by Agilent. Knowing the pinout of the J2 connector will be useful =
too. Then, I will create a PCB and find the good replacement =
components...etc.=20

Do you think this project is a good idea and may interest somebody other =
than me?=20

Please share your thoughts ;)

Regards,

---------------------
Samuel DEMEULEMEESTER
Presse Non Stop - Canard PC
www.canardpc.com
MSN : sam at x86.fr




From bogus@does.not.exist.com  Wed Dec  3 18:34:25 2008
From: bogus@does.not.exist.com ()
Date: Wed, 03 Dec 2008 18:34:25 -0000
Subject: No subject
Message-ID: <mailman.26.1236743573.2496.time-nuts@febo.com>

"But if France could lock space and mass in the protected basement of
Bretuil [kilogram and meter], time proved more elusive. At the beginning
of the 1880s, one French review lamented that clocks were
extraordinarily recalcitrant, each one's own "personality" repelling any
attempt to regularize it . . ."

"Not that French astronomers and physicists had not tried. All over
Europe, neighborhoods, cities, regions, and countries were struggling to
standardize and unify their clocks. In Paris and Vienna during the late
1870s, industrial steam plants injected subterranean pipes with
compressed air, then modulated that pressure to set clocks pneumatically
around the city."

[There are no details of the modulator or the regulating mechanism in
the clocks, probably for the same reason that equations are not used in
books for wide audiences. There is a drawing of the control room at the
Rue du Telegraphe, circa 1880, but the operation remains obscure.]

"At first the fifteen-second delay caused by the time it took the
pressure pulse to race under the streets of Paris seemed like nothing.
Yet time sensitivity had sufficiently mounted by 1881 that even this
tiny delay (. . .) became visible. Astronomers caught the problem, so
did the engineers of bridges and roads. Soon the public did as well."

"At first the engineers tried to shrug off the discrepancy: "this small
discordance, indisputable in theory, has little practical importance
since we are dealing with clocks that display minutes, and where the
minute hands jump in steps and do not permit further divisions, even
approximately between that division of time.""

"The clock minders hastened to add that they would offset the
Observatory's clock by the fifteen seconds the pulse took to reach the
outermost reaches of the network. To be exact, they then mounted
retarding counter-weights on each pneumatic clock based on its distance
from the center."

"Two striking features of time coordination emerge from this little
vignette. First, time awareness had become acute. Before the nineteenth
century, clocks normally did not even have minute hands. . . . Second,
the transmission time - even of a pressure wave traveling at the speed
of sound - looked to professionals and the public like a problem
demanding correction."

[Of course, electrical transmission soon solved the problem, but
certainly not overnight.]

IMHO, a little history helps to put today's problems in perspective.

Google provides some useful hits. An 1881 article in the London Times
(reprinted by the NY Times) reveals that the system runs on pulses at
one minute intervals that index the minute hand. Paris had 16 miles of
clock air piping to over 2000 clocks and 14 public clocks at that time.
There is no mention of time synchronization, just the pulse from a
pendulum oscillator.

The US had pneumatic clocks made by Hals and Wenzel. NAWCC has some
articles - need to follow up on that.

Would like to see one of those pneumatic clocks. If I owned one, I'd
build a GPS disciplined pneumatic oscillator for it.

Bill Hawkins


-----Original Message-----
From: Tom Van Baak
Sent: Tuesday, March 10, 2009 12:52 PM

1pps = 1 puff per second?




From bogus@does.not.exist.com  Wed Dec  3 18:34:25 2008
From: bogus@does.not.exist.com ()
Date: Wed, 03 Dec 2008 18:34:25 -0000
Subject: No subject
Message-ID: <mailman.27.1236761322.2496.time-nuts@febo.com>

10cmm long.



Bruce