[time-nuts] phase/frequency data of real atomic clocks

Tom Van Baak tvb at LeapSecond.com
Thu Mar 2 10:02:14 EST 2017

Hi Attila,

File www.leapsecond.com/tmp/log22722.dat.gz is half a million seconds of two active H-masers. Data is phase difference, units are seconds, tau0 is 1 s.

The raw phase will look bad until you apply a quadratic fit. Stable32 reports:
 DRIFT FOR FILE: log22722.002
 Frequency Data Points 1 thru 515027 of 515027
 Drift Type: Quadratic

With that done, it stays within 0.5 ns for the week. The ADEV plot might be a good example for you: white noise until 100 s; then the maser auto-tuning plateau until well past 1000 s; then a nice drop into the low -15's. The drift rate was really high. I'd have to check my notes; maybe this was a power-on test. I'll get you a much longer, more stable run later, but this particular run happened to be on my laptop.

Some plots attached.

log22733v.gif -- screen shot from TSC5110 an hour into the run
log22734v.gif -- ditto
log22722-1.gif -- Phase residual plot of full data set
log22722-2.gif -- ADEV+MDEV of residuals.


note to self:

cd \tvb\2013-ahm\5110\ahm5--st5

dir log227*
07/24/2013  04:00 PM           274,948 log22722-mjd56497.txt
07/25/2013  04:00 PM         2,811,260 log22722-mjd56498.txt
07/26/2013  04:00 PM         2,932,144 log22722-mjd56499.txt
07/27/2013  04:00 PM         2,937,430 log22722-mjd56500.txt
07/28/2013  04:00 PM         2,938,722 log22722-mjd56501.txt
07/29/2013  04:00 PM         2,937,226 log22722-mjd56502.txt
07/30/2013  12:36 PM         2,520,794 log22722-mjd56503.txt

cat log22722-mjd* | ht2
56497.897473773 1 0.4257858
56497.897485347 2 0.4257756
\/\/\/\/\/\/\/\/\/\/\/\/\/\/ (515027 lines total) \/\/\/\/\/\/\/\/\/\/\/\/\/\/
56503.858467512 515026 -4.3111472
56503.858479086 515027 -4.3111562

cat log22722-mjd* | mjdrate
56497.897474 ... 56503.858479 5.96 days (143.06 hours),  515027 lines,  1.000009 seconds/line,  0.999991 Hz

cat log22722-mjd* | da fld 3 /5e6 f .14 plus out \tmp\log22722.dat

----- Original Message ----- 
From: "Attila Kinali" <attila at kinali.ch>
To: "Discussion of precise time and frequency measurement" <time-nuts at febo.com>
Sent: Wednesday, March 01, 2017 2:36 PM
Subject: [time-nuts] phase/frequency data of real atomic clocks

> Hi,
> I have been looking into noise and noise processes in the last couple
> of months. Unfortunately, my seemingly simple question how to simulate
> power law noise (1/f^a noise) properly led me to a wild goose chase
> deep into the mathematical lala-land[1].  
> In order to verify that I haven't gone completely off the track,
> I would like to check some of the assumptions made with real data.
> Hence I would like to ask, whether people here have continuous
> phase/frequency data of real atomic clocks, and if I could get
> a copy of those, together with a description how it was measured.
> I am looking for any kind of atomic clock and any kind of measurement.
> The higher the sample rate and the longer the measurement the better,
> but I will not be picky. 
> If you know someone who has collected such data, any contact
> information would also be helpful.
> Computer generated data does not work in this case, as I want to
> verify that the assumptions made in the mathematical models
> have a foundation in the real physical implementations.
> Thanks in advance
> Attila Kinali
> [1] For those interested: If you think that calculus or stochastic
> was difficult, imagine what their offspring "stochastic calculus"
> looks like. Now add fractional calculus (half-integrals and
> half-differentials, but nothing about fractals per se) to the
> whole thing and you get fractals waiting around the corner.
> -- 
> It is upon moral qualities that a society is ultimately founded. All 
> the prosperity and technological sophistication in the world is of no 
> use without that foundation.
>                 -- Miss Matheson, The Diamond Age, Neil Stephenson
> _______________________________________________
> 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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