[time-nuts] ADEV from phase or frequency measurement

Volker Esper ailer2 at t-online.de
Sat Mar 1 07:25:52 EST 2014

Thank you, Tom, so far. Yes, I know that I have to use different
formulas, but - of course - I didn't calculate the ADEV curves myself, I
let some software do the job, namely Ulrich's Plotter and TimeLab as
well. Plotter has a menu item, where you have to check if you deal with
phase or frequency data, so I assumed the software would do right.

I am confused. The ADEVs of the phase data are about 10 times better and
have a different shape...


Am 01.03.2014 12:37, schrieb Tom Van Baak:
> Hi Volker,
> Either phase or frequency raw data can be used to generate an ADEV plot, but you have to use different methods depending on the data type.
> See the two formulas for Allan Variance in: http://www.wriley.com/paper2ht.htm
> Usually we use the "x" form of the formula, where x is an array of phase samples. But if you have frequency samples then use the "y" form instead, where y is an array of frequency samples.
> Note you can also convert phase data to frequency data (by differentiating) and use the "y" form. Or convert frequency data to phase data (by integrating) and use the "x" form.
> /tvb
> ----- Original Message ----- 
> From: "Volker Esper" <ailer2 at t-online.de>
> To: "Discussion of precise time and frequency measurement" <time-nuts at febo.com>
> Sent: Saturday, March 01, 2014 3:15 AM
> Subject: [time-nuts] ADEV from phase or frequency measurement
>> Hello dear fellow time-nuts,
>> I stumbled over a question that may sound stupid to you:
>> Is the usual ADEV plot the result of a phase or a frequency measurement?
>> I get totally different results when comparing a phase and a frequency
>> measurement of the same source. Or am I doing something totally wrong?
>> Thanks a lot
>> Volker
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