[time-nuts] More Allan deviation data

Ulrich Bangert df6jb at ulrich-bangert.de
Sun Oct 29 14:46:51 EST 2006


Didier,

> (even the menu now has a *normal* File->Open :-)

you take the credit for this!

73 de Ulrich, DF6JB

> -----Ursprüngliche Nachricht-----
> Von: time-nuts-bounces at febo.com 
> [mailto:time-nuts-bounces at febo.com] Im Auftrag von Didier Juges
> Gesendet: Sonntag, 29. Oktober 2006 15:22
> An: Discussion of precise time and frequency measurement
> Betreff: Re: [time-nuts] More Allan deviation data
> 
> 
> Ulrich Bangert wrote:
> > Hi Didier,
> >
> > you may use the DRIFT section of the graphic editor of PLOTTER to 
> > remove a phase drift due to a constant frequency offset as seen in 
> > this data, with the result that you get more "visual 
> resolution" out 
> > of it, as in the attached PDF.
> >
> > 73 de Ulrich, DF6JB
> >
> >   
> Ulrich,
> 
> I ran the OCXO with the new antenna location overnight, 
> except that the 
> laptop went to sleep some time in the night, so I have lost several 
> hours of data, which may explain the sudden slope change in the plot 
> below (I need to save timestamps I guess). However, the 
> remaining data 
> is good I think. There was no sudden noise, and about 5 phase 
> jumps due 
> to the OCXO drifting during the observation period.
> 
> I downloaded the latest version of Plotter (10-27) and it's 
> all there. I 
> was able to quickly remove the phase jumps when the OCXO drifted past 
> the divided down period, and then remove the remaining slow drift.
> 
> What a nice piece of software!
> (even the menu now has a *normal* File->Open :-)
> 
> The latest plots are at the usual place: 
> http://www.ko4bb.com/Test_Equipment/HP10811-> GPS_10-29-2.png
> 
> 
http://www.ko4bb.com/Test_Equipment/HP10811-GPS_10-29-2_Allan.png

Now that the data collection method seems to be getting close, I wonder 
how I should use the data, and what it means.

The Allan deviation seems to taper around e-10 at 1000 seconds, then it 
looks like it wants to keep getting lower.

As a reminder, this is the HP10811 against the GPS receiver. I am not 
sure what I should expect?

Didier

PS: I am still planning to measure ambient temperature at the same time 
as I collect TI, via the GPIB, using a HP 3478A voltmeter and a 
thermistor. This way, I should be able to correlate frequency changes 
and temperature changes. I assume I can tell Plotter to ignore the 
temperature field or display it with its own scaling. Should I use a 
specific character as field delimiter? (such as a comma, or just
spaces?)

(In the short term, temperature data will be thermistor values, until I 
write the code to convert in degrees. )

Also, if I use time stamps, should I use field delimiter between the 
time stamp and the data?

What is the time stamps are discontinuous (as if the laptop falls asleep

again), will that mess up Plotter?



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