[time-nuts] Lucent GPSDO comments

Anthony Roby aroby at antamy.com
Fri Nov 14 09:38:32 EST 2014


My unit has been on for just over a week.  I captured the data overnight - the PPS TI plot is here https://drive.google.com/file/d/0B5tlecUITRBLMVV4NzFTMnlNaDA/.  I see a similar PPS TI graph to yours, but my EFC is much different.  Trouble is with that, I'm not sure what I'm looking at and what "normal" should look like!

I also snapped the Time Measures graph - https://drive.google.com/file/d/0B5tlecUITRBLdjdPRWpITGpmeDQ/.  I don't yet have any other method of measuring ADEV, but what is captured here looks similar to many other ADEV charts.  Again, any advice on what I should be looking for would be helpful.

Anthony


-----Original Message-----
From: time-nuts [mailto:time-nuts-bounces at febo.com] On Behalf Of paul swed
Sent: Friday, November 14, 2014 8:18 AM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Lucent GPSDO comments

Thanks everyone. My concern is did I need to reach out and get an exchange before the 30 days is up. I sense ASI the vendor is actually a pretty good company and will do the right thing.
Regards
Paul
WB8TSL

On Fri, Nov 14, 2014 at 7:35 AM, Bob Camp <kb8tq at n1k.org> wrote:

> Hi
>
>
> That OCXO is doing very well.
>
> If you look at the plot, it ??s doing a few LSB ??s on the DAC over 
> the time period. That ??s good performance.
>
> Bob
>
> > On Nov 13, 2014, at 9:17 PM, paul swed <paulswedb at gmail.com> wrote:
> >
> > Bob the actual pictures and files are large so here is the left 
> > screen
> and
> > right screen from the z3811 program. Pretty easy to guess whats in 
> > the middle.
> > Lots of noise on the ti/pps and you can see EFC is rising all the time.
> > I will say in the past it had been a steady rise now there is a wave 
> > that might mean its slowing down a bit.
> > But this all looks rattier then I would believe.
> > Regards
> > Paul
> > WB8TSL
> >
> >
> > On Thu, Nov 13, 2014 at 5:43 PM, Bob Camp <kb8tq at n1k.org> wrote:
> >
> >> Hi
> >>
> >> How much is your unit moving?
> >>
> >> Bob
> >>
> >>> On Nov 13, 2014, at 1:50 PM, paul swed <paulswedb at gmail.com> wrote:
> >>>
> >>> On the older units that used a RB to control an Xtal. They created 
> >>> a
> mix
> >> of
> >>> 5 Mhz +10 Mhz and that produced 15 out that hit an amplifier to 
> >>> drive a
> >> 12
> >>> way splitter.
> >>> I think I reverse engineered the circuit. Its on paper and filed. 
> >>> Oh
> that
> >>> ends this discussion.
> >>> Anyhow it was not hard to figure out.
> >>> I am still baking my Lucent in so want to see if it settles.
> >>> There is just the barest of hints it may be.
> >>>
> >>> So do not want to power down to explore. Happy to dig in if I 
> >>> don't
> have
> >> to
> >>> return the unit.
> >>>
> >>> Regards
> >>> Paul
> >>> WB8TSL
> >>>
> >>> On Wed, Nov 12, 2014 at 7:21 PM, Bob Camp <kb8tq at n1k.org> wrote:
> >>>
> >>>> Hi
> >>>>
> >>>> The chain in the Z3810 / 3811 / 3812 Lucent boxes is *much* 
> >>>> different
> >> than
> >>>> the setup in the earlier parts. The phase noise and ADEV on the
> Z3810 ??s
> >> is
> >>>> better than what you got on the earlier versions. That makes 
> >>>> keeping
> the
> >>>> noise down in whatever mod you do more important. The existing 10 
> >>>> MHz output on the Z3810 setup is a real good example of how a 
> >>>> seemingly
> >> simple
> >>>> thing can add a lot of phase noise and even mess up ADEV.
> >>>>
> >>>> I don ??t think the 15 MHz is used for much of anything in the Z3810.
> That
> >>>> could be wrong, but I can ??t see where it is needed based on 
> >>>> poking
> >> around a
> >>>> little. The 15 MHz buffer appears to be quiet and puts out a lot 
> >>>> of
> >> power.
> >>>> Using it for 10 MHz would give you a *lot* of 10 MHz signal to 
> >>>> play
> >> with.
> >>>> IF the mods are simple it ??s an attractive solution. If it 
> >>>> involves
> >> swapping
> >>>> out 30 parts - not so much.
> >>>>
> >>>> Bob
> >>>>
> >>>>> On Nov 12, 2014, at 5:50 PM, Perry Sandeen via time-nuts <
> >>>> time-nuts at febo.com> wrote:
> >>>>>
> >>>>> Wrote: At some point we will get into hacking the main board to 
> >>>>> switch from 15 MHz to 10 MHz.
> >>>>>
> >>>>> One doesn ??t have to that if one uses the two IC divide by
> >>>>> 1.5 circuit I offered the list. I specifically found it so I 
> >>>>> didn ??t
> >> have
> >>>> to
> >>>>> hack the innards.
> >>>>>
> >>>>> Wrote: The great news is the oscillator is 5 Mhz.
> >>>>>
> >>>>> Don ??t bet the rent on that. My early units have 10 MHZ Datum 
> >>>>> oscillators.
> >>>>>
> >>>>> Bob ??s point about getting the GPSDO ??s if all cost the same 
> >>>>> is a good point.
> >>>>>
> >>>>> Another point. At least on the older units I have: GPSDO, 
> >>>>> Rubidium, and Crystal oscillator, the output circuitry after the 
> >>>>> 15
> MHz
> >>>>> conversion takes place is the same. So if one hacks the 10 Mhz 
> >>>>> into
> the
> >>>> chain,
> >>>>> all one has to do is remove or bypass the 15 MHz filter before 
> >>>>> the
> >>>> output.
> >>>>>
> >>>>> Even if you don ??t have the rubidium unit but have either/or 
> >>>>> GPDO or Crystal oscillator email me off list for the rubidium
> schematic
> >>>> as
> >>>>> after the logic chips they use the same circuit.
> >>>>>
> >>>>> Regards,
> >>>>>
> >>>>> Perrier
> >>>>> _______________________________________________
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> side.GIF>_______________________________________________
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