[time-nuts] time-nuts newbie
Bob Camp
lists at rtty.us
Thu May 2 21:33:59 EDT 2013
Hi
Warmup time on an Rb is going to be a "that depends" sort of thing (just like anything else). One would *hope* that you could get to 0.1 ppb of final frequency in 10 minutes from normal boat temperatures. That may or may not be what the particular unit you get at auction is doing.
Next issue would be temperature. Again, who knows, but you could hope for 0.1 to 0.2 ppb over a modest temperature range.
Net result would be something in the 0.2 ppb (or so) range. The ADEV on your OCXO and Rb should be good enough that it will not limit the process. Something like a PicTic should be able to give you that sort of resolution in a second. You could get a *lot* of data for a frequency locked loop in the last two minutes of the Rb's warmup. Maybe run for another minute or two to converge the lock.
A good (say $30 at auction) OCXO should be able to do less than 0.1 ppb per day running continuously. The same 0.1to 0.2 ppb of tempo over a narrow range likely applies to it as well. Re-sync once a day and you probably are holding 0.2 to 0.5 ppb on average. You could get fancy and back calculate the OCXO drift as you locked it up. I would assume you can lock the OCXO this way to 0.05 ppb. That might take a few bits on a DAC.
Now for the "flunked this last time" part:
Hopefully there are 31,536,000 seconds in a 365 day long year.
One ppb would be 0.031536 seconds per year.
Even if you don't hit the 0.2 to 0.5 ppb average, you should quite easily hit 0.03 seconds per year.
If the Rb pulls 30W for 6 minutes plus 15 W for the next 6, that's 4.5 WH per day.
If the OCXO pulls 1W all the time, that's 24 WH per day.
The Rb is < 1/5 the total power budget. That assumes the rest of the "stuff" is insignificant power wise.
Sounds like it would work even without an EMXO involved.
I sure hope I got the math right that time….
Bob
On May 2, 2013, at 5:43 PM, Chris Albertson <albertson.chris at gmail.com> wrote:
> Turning off the Rb is a good idea. That is one of the best features
> of the Rb is that it will come back on from a zero power and be pretty
> much spot on the frequency but the phase will be random. So the
> question is that if you want to re-calibrate the OCXO how long to you
> need to compare it to the Rb. You can't look at the phase difference,
> that has been randomized by the power cycle.
>
> I think one could get at least 10 and maybe 100 times better than the
> OP's requirement and still be under the $500 limit.
>
>
> On Thu, May 2, 2013 at 12:59 PM, Bob Camp <lists at rtty.us> wrote:
>> Hi
>>
>> A clock based on an eBay Rb can be set up to pull less than 10 watts. Based
>> on 8 hours of light a day that would get you to 30 watts of solar needed to
>> power it. That's a pretty small fraction of your 480W setup. You will get
>> CSAC level timing and still fit your budget.
>>
>> For a lower power solution, wake up the Rb once a day around mid day. Only
>> do it if the solar has surplus power. Re-sync your OCXO to the Rb. That
>> should cut the power by a factor of about 10:1. A Google search for "RBXO"
>> will turn up details on the process. Not quite CSAC performance, but far
>> better than the OCXO alone.
>>
>> Bob
>>
>> -----Original Message-----
>> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
>> Behalf Of Timothy Bastian
>> Sent: Thursday, May 02, 2013 12:36 PM
>> To: time-nuts at febo.com
>> Subject: Re: [time-nuts] time-nuts newbie
>>
>> Wow I didn't know how much I was going to stir up here. As for the accuracy
>> of the DS32khz you are correct in what the literature says. They call for an
>> accuracy of one minute per year. The 10 seconds / year is what the gentleman
>> who designed the clock thought would be possible. The testing he has done is
>> giving better results than 10 seconds / year. My clock has not been running
>> long enough to give you any meaningful results.
>>
>>
>> As far as the requirements for my chronometer... there is what I would like
>> to have and what I can afford. A clock driven by a csac (SA.45s) would be
>> the ultimate. I am however shooting for something in the $500.00 or
>> less price range. I have ships power available to power the clock but would
>> like to have the ability to run on an internal battery for an extended
>> period if needed. Say for two months. I have 4, 120 watt solar panels with
>> 500 amp hours of 12 volt battery power. I'm shooting for a size of not more
>> than one cubic foot. You are correct about the 100 ppb aging, which I
>> believe will put me at +/- 3 seconds / year. A GPS time reference to set the
>> clock would be acceptable however the whole point of having said clock is to
>> still be able to navigate in the event of GPS failure.
>>
>> Thanks for all of the replies,
>>
>> Tim KK4FQB
>>
>> ________________________________
>> From: "time-nuts-request at febo.com" <time-nuts-request at febo.com>
>> To: time-nuts at febo.com
>> Sent: Wednesday, May 1, 2013 11:08 AM
>> Subject: time-nuts Digest, Vol 106, Issue 1
>>
>>
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>> Today's Topics:
>>
>> 1. Re: Time nut newbie (Rex)
>> 2. Re: 10811 (John Miles)
>> 3. Re: HP5065B !!! (Jim Palfreyman)
>> 4. Re: Time nut newbie (Jim Palfreyman)
>> 5. Re: Time nut newbie (Hal Murray)
>> 6. Re: Time nut newbie (Chris Albertson)
>> 7. Re: Time nut newbie (Attila Kinali)
>> 8. Re: Time nut newbie (Bob Camp)
>>
>>
>> ----------------------------------------------------------------------
>>
>> Message: 1
>> Date: Tue, 30 Apr 2013 18:57:20 -0700
>> From: Rex <rexa at sonic.net>
>> To: Discussion of precise time and frequency measurement
>> <time-nuts at febo.com>
>> Subject: Re: [time-nuts] Time nut newbie
>> Message-ID: <51807680.2040705 at sonic.net>
>> Content-Type: text/plain; charset=windows-1252; format=flowed
>>
>> It doesn't affect the general magnitude conclusions by Bruce, but as
>> long as we are making corrections, my calculator seems to think
>> 60 * 60 * 24 * 12 = 1036800 seconds in 12 days, not 1024800. That does
>> come out to 115.7 days for 1 sec error. Maybe the 12-day number was a typo?
>>
>> -Rex
>>
>>
>> On 4/30/2013 12:57 PM, Bruce Griffiths wrote:
>>> 12 days is 1024800 s ie just over 1 million seconds so a frequency
>>> offset of 0.1ppm results in a time error of ~ 0.1s not 1s.
>>> 1sec error would occur in just under 116 days,
>>>
>>> Bruce
>>>
>>> Bob Camp wrote:
>>>> Hi
>>>>
>>>> If you take a look down in the fine print on the OCXO spec, the aging
>>>> rate
>>>> is 100 ppb / year in the first year. If you are off by 0.1 ppm (100 ppb)
>>>> your clock will gain a second in less than 12 days.
>>>>
>>>> Bob
>>>>
>>
>>
>>
>> ------------------------------
>>
>> Message: 2
>> Date: Tue, 30 Apr 2013 19:53:49 -0700
>> From: "John Miles" <jmiles at pop.net>
>> To: "'Discussion of precise time and frequency measurement'"
>> <time-nuts at febo.com>
>> Subject: Re: [time-nuts] 10811
>> Message-ID: <004a01ce4617$1ba19710$52e4c530$@pop.net>
>> Content-Type: text/plain; charset="UTF-8"
>>
>>> Close, but it's for the 105, not the 5061, and the boards are physically
>> very
>>> different.
>>
>> The 5061A upgrade used those 105-series boards. With the 5061B, they
>> changed the part number of A1A3 (the OCXO interface board) from 00105-6044
>> to 05061-6198, but I don't see any major differences in the schematic,
>> looking at the Artek .PDF manual for the 5061B.
>>
>>> The part number on the connector for the board is the same as the
>> connector
>>> for the 10811. Does anyone know where to get boards that fit the
>> connector?
>>> Mouser carries the connector, but I can't find any boards.
>>
>> You don't really need a board -- I didn't use one (see
>> http://www.ke5fx.com/tbolt.htm ). It uses a pretty common edge connector
>> that can be pulled off of any number of random surplus HP PCBs, if you don't
>> want to order one.
>>
>>> how often do people need to retune the 10811? I have a pair of the 10811-
>>> 60109's, another 10811, and a 10544 and all are within 1 Hz of 10 MHz.
>> That's close
>>> enough
>>
>> Some anecdata: my GPS-disciplined 10811-60109 has been running for about 5
>> years without any retuning. The DAC voltage is currently about 0.52V, and
>> I'm sure I would have started it out near 0.0, so about 10% of its EFC
>> control range has been needed after 5 years. (Of course it could have
>> wandered around arbitrarily in the meantime, but I doubt it.)
>>
>> At -0.324 Hz/volt, this would be about 0.03 Hz per year of positive drift on
>> average, or 3E-9 per year. That's in line with what I've seen other
>> well-settled 10811s achieve.
>>
>>> Is there any advantage in using the 723 voltage regulator? The 10811 and
>>> 10544 manuals both show the use of the 723 for the regulator for the
>> oscillator supply,
>>> but on the HP schematic for the 6198 board they use a pair of three
>> terminal
>>> regulators.
>>
>> HP's use of an LM317T-style regulator to drive the 18V oven supply, a 78L12
>> to drive the oscillator, and a Zener+emitter follower to drive the 7474
>> divider was a bit funky. Regulator noise on the oven supply isn't critical,
>> but for driving the oscillator circuit itself, the difference between a 7812
>> and an LM317T can be seen in some cases. Not sure offhand how sensitive the
>> 10811 is to supply noise, but you can certainly see the difference in
>> regulators with a Wenzel ULN.
>>
>> In any event an LM317T would be fine for driving the +12 rail.
>>
>> -- john, KE5FX
>> Miles Design LLC
>>
>>
>>
>>
>> ------------------------------
>>
>> Message: 3
>> Date: Wed, 1 May 2013 13:36:43 +1000
>> From: Jim Palfreyman <jim77742 at gmail.com>
>> To: Discussion of precise time and frequency measurement
>> <time-nuts at febo.com>
>> Subject: Re: [time-nuts] HP5065B !!!
>> Message-ID:
>> <CALH-g5YNYi2o4wGJmzPDciCt8+hPGjfx0QPnjG1Ew+h0KGXXWA at mail.gmail.com>
>> Content-Type: text/plain; charset=windows-1252
>>
>> Am I missing something? What actual modifications were done and how?
>>
>> Jim
>>
>>
>>
>> On 1 May 2013 07:30, <EWKehren at aol.com> wrote:
>>
>>> Attilla
>>> No one should or will discourage you from developing a laser pumped Rb.
>>> Bruce posted the following link. It addresses some of the issues and for
>> me
>>> looking at lamp Rb's is most helpful.
>>>
>>> http://tf.boulder.nist.gov/general/pdf/1219.pdf
>>>
>>> Bert Kehren
>>>
>>>
>>>
>>> In a message dated 4/30/2013 4:51:57 P.M. Eastern Daylight Time,
>>> attila at kinali.ch writes:
>>>
>>> On Mon, 29 Apr 2013 17:19:05 -0400 (EDT)
>>> EWKehren at aol.com wrote:
>>>
>>>> I am still sitting here trying to figure out the purpose of posting
>> the
>>>
>>>> article on laser diode pumping of the Rb. One look at the data and it
>>> is
>>>> clear that Corby?s work far surpasses the data shown in the paper. All
>>> it does
>>>> is distract from Corb?s accomplishments.
>>>
>>> Sorry i didnt mean to do that. I am very gratefull at the work Corby
>>> has done and the new insights on what error sources a Rb gas cell
>>> has.
>>>
>>> But as someone living in europe, i have certain problems getting my
>>> hands on a HP5065. There is virtually no surplus market here. And
>>> if there is anything sold in europe, the price is nearly that of
>>> a new device, sometimes even more (no, i'm neither joking nor
>>> exagerating).
>>> I cannot buy any of the fancy devices you have access to in the US.
>>> Buying a Cs beam, as a few of you have, is a dream that will not come
>>> true for me, unless i win in the lottery.
>>> But building my own Rb standard using laser diodes is feasible.
>>> I still lack a lot of knowledge and understanding how to do that,
>>> but this group has been very helpfull in filling my gaps, when asking
>>> the right questions. And if you don't mind, i would like to keep
>>> asking those questions.
>>>
>>>
>>> Attila Kinali
>>> --
>>> The people on 4chan are like brilliant psychologists
>>> who also happen to be insane and gross.
>>> -- unknown
>>> _______________________________________________
>>> time-nuts mailing list -- time-nuts at febo.com
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>>> and follow the instructions there.
>>>
>>
>>
>> ------------------------------
>>
>> Message: 4
>> Date: Wed, 1 May 2013 12:40:02 +1000
>> From: Jim Palfreyman <jim77742 at gmail.com>
>> To: Discussion of precise time and frequency measurement
>> <time-nuts at febo.com>
>> Subject: Re: [time-nuts] Time nut newbie
>> Message-ID:
>> <CALH-g5ZoeGsGnfXj2SX=dL2cmHs+F+_VniG5p3KC4XXToP9Hxg at mail.gmail.com>
>> Content-Type: text/plain; charset=ISO-8859-1
>>
>> Buy a cheap rubidium off ebay and use it to drive a micro-controller and
>> write some clock software.
>>
>>
>> On 1 May 2013 11:57, Rex <rexa at sonic.net> wrote:
>>
>>> It doesn't affect the general magnitude conclusions by Bruce, but as long
>>> as we are making corrections, my calculator seems to think
>>> 60 * 60 * 24 * 12 = 1036800 seconds in 12 days, not 1024800. That does
>>> come out to 115.7 days for 1 sec error. Maybe the 12-day number was a
>> typo?
>>>
>>> -Rex
>>>
>>>
>>>
>>> On 4/30/2013 12:57 PM, Bruce Griffiths wrote:
>>>
>>>> 12 days is 1024800 s ie just over 1 million seconds so a frequency offset
>>>> of 0.1ppm results in a time error of ~ 0.1s not 1s.
>>>> 1sec error would occur in just under 116 days,
>>>>
>>>> Bruce
>>>>
>>>> Bob Camp wrote:
>>>>
>>>>> Hi
>>>>>
>>>>> If you take a look down in the fine print on the OCXO spec, the aging
>>>>> rate
>>>>> is 100 ppb / year in the first year. If you are off by 0.1 ppm (100 ppb)
>>>>> your clock will gain a second in less than 12 days.
>>>>>
>>>>> Bob
>>>>>
>>>>>
>>> ______________________________**_________________
>>> time-nuts mailing list -- time-nuts at febo.com
>>> To unsubscribe, go to https://www.febo.com/cgi-bin/**
>>>
>> mailman/listinfo/time-nuts<https://www.febo.com/cgi-bin/mailman/listinfo/tim
>> e-nuts>
>>> and follow the instructions there.
>>>
>>
>>
>> ------------------------------
>>
>> Message: 5
>> Date: Tue, 30 Apr 2013 23:13:44 -0700
>> From: Hal Murray <hmurray at megapathdsl.net>
>> To: lists at lazygranch.com, Discussion of precise time and frequency
>> measurement <time-nuts at febo.com>
>> Subject: Re: [time-nuts] Time nut newbie
>> Message-ID:
>> <20130501061344.DB93980006F at ip-64-139-1-69.sjc.megapath.net>
>> Content-Type: text/plain; charset=us-ascii
>>
>>
>> lists at lazygranch.com said:
>>> A bit OT, but back in the day there was what amounted to an X-prize for a
>>> real accurate chronometer for navigation.
>>
>>> Make that way back in the day.
>> http://en.m.wikipedia.org/wiki/John_Harrison
>>
>> There is a good book out on that topic:
>> Longitude by Dava Sobel
>> There is also a fancy version with lots of very good pictures.
>> I'll have to go find my copy so I can look at them again.
>>
>>
>>
>> --
>> These are my opinions. I hate spam.
>>
>>
>>
>>
>>
>> ------------------------------
>>
>> Message: 6
>> Date: Tue, 30 Apr 2013 23:36:57 -0700
>> From: Chris Albertson <albertson.chris at gmail.com>
>> To: Discussion of precise time and frequency measurement
>> <time-nuts at febo.com>
>> Subject: Re: [time-nuts] Time nut newbie
>> Message-ID:
>> <CABbxVHuUjp3Af0tpkRG6E26BrSQGQviMCRi3wzgSYT9+OfzSHw at mail.gmail.com>
>> Content-Type: text/plain; charset=ISO-8859-1
>>
>> On Tue, Apr 30, 2013 at 7:40 PM, Jim Palfreyman <jim77742 at gmail.com> wrote:
>>> Buy a cheap rubidium off ebay and use it to drive a micro-controller and
>>> write some clock software.
>>
>> That was exactly my solution but I'm waiting ti hear about his size,
>> power and cost budget. If this has to run on Battery power for the
>> entire year the Rb unit is not going to work
>>
>> The OP's 1 second per year goal is only asking for 3.2E-7 level
>> performance if I did the math correctly. Even the $100 Rb is at
>> least 100 times better than required.
>> --
>>
>> Chris Albertson
>> Redondo Beach, California
>>
>>
>> ------------------------------
>>
>> Message: 7
>> Date: Wed, 1 May 2013 09:45:06 +0200
>> From: Attila Kinali <attila at kinali.ch>
>> To: Discussion of precise time and frequency measurement
>> <time-nuts at febo.com>
>> Subject: Re: [time-nuts] Time nut newbie
>> Message-ID: <20130501094506.966146722efbbaf9c80e5aca at kinali.ch>
>> Content-Type: text/plain; charset=UTF-8
>>
>> On Tue, 30 Apr 2013 13:49:43 -0400
>> "Tim Bastian"<n714x at yahoo.com> wrote:
>>
>>
>>> I'm a time nut newbie. My obsession started with the search for an
>> accurate chronometer to carry on my boat for celestial navigation. Yes there
>> still are a few of us left that practice the art.
>>>
>>> My current project is a quartz chronometer using a DS32Khz tcxo oscillator
>> and two 74HC4060s (+ or- 10 seconds / year).?
>>>
>>> For my next project I'm looking at an Abricon Part Number
>> AOCJY2-10.000MHZ? ocxo 5 ppb running through a pic and using the algorithm
>> posted on http://www.romanblack.com/one_sec.htm. I'm shooting for + or - 1
>> seconds / year.?
>>>
>>> Is there an archive of old posts that might be helpful in answering some
>> of my questions and for getting ideas.
>>
>> You want to read Vig's Quartz Crystal Tutorial. That explains a lot about
>> where the instabilities of a crystal oscillator come from. You can find
>> them (and a lot more) on http://www.ko4bb.com/ in the Manuals section.
>> Have a look at different versions, as some interesting things were left
>> out in the newer versions.
>>
>> An idea how to get to the stability you want without wasting too much
>> power might be an MCXO. [1] gives a pretty decent overview of the way how
>> they work including a schematic for an oscillator. [2] has some ideas how
>> to simplify the circuit and get lower power.
>>
>> In your case, i guess it would be an idea to leave out the second stage
>> frequency generation (the VCO or DDS) and generate a PPS directly from
>> the microcontroller.
>>
>> Attila Kinali
>>
>>
>> [1] "A microcomputer compensated crystal oscillator using a
>> dual-mode resonator", by Benjaminson and Stallings, 1989
>>
>> [2] "An Improved Method of MCXO", by Zhou, Liu, Wang, 2000
>> --
>> The people on 4chan are like brilliant psychologists
>> who also happen to be insane and gross.
>> -- unknown
>>
>>
>> ------------------------------
>>
>> Message: 8
>> Date: Wed, 1 May 2013 07:00:33 -0400
>> From: Bob Camp <lists at rtty.us>
>> To: Discussion of precise time and frequency measurement
>> <time-nuts at febo.com>
>> Subject: Re: [time-nuts] Time nut newbie
>> Message-ID: <7D23F52C-1BC6-449B-A47E-FC9BCC454E3A at rtty.us>
>> Content-Type: text/plain; charset=windows-1252
>>
>> Hi
>>
>> It was tired old eyes and tiny numbers on the calculator ?.That plus to much
>> distraction to double check things.
>>
>> Bob
>>
>> On Apr 30, 2013, at 9:57 PM, Rex <rexa at sonic.net> wrote:
>>
>>> It doesn't affect the general magnitude conclusions by Bruce, but as long
>> as we are making corrections, my calculator seems to think
>>> 60 * 60 * 24 * 12 = 1036800 seconds in 12 days, not 1024800. That does
>> come out to 115.7 days for 1 sec error. Maybe the 12-day number was a typo?
>>>
>>> -Rex
>>>
>>>
>>> On 4/30/2013 12:57 PM, Bruce Griffiths wrote:
>>>> 12 days is 1024800 s ie just over 1 million seconds so a frequency offset
>> of 0.1ppm results in a time error of ~ 0.1s not 1s.
>>>> 1sec error would occur in just under 116 days,
>>>>
>>>> Bruce
>>>>
>>>> Bob Camp wrote:
>>>>> Hi
>>>>>
>>>>> If you take a look down in the fine print on the OCXO spec, the aging
>> rate
>>>>> is 100 ppb / year in the first year. If you are off by 0.1 ppm (100 ppb)
>>>>> your clock will gain a second in less than 12 days.
>>>>>
>>>>> Bob
>>>>>
>>>
>>> _______________________________________________
>>> 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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>
>
>
> --
>
> Chris Albertson
> Redondo Beach, California
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
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