[time-nuts] AVAR calculation
me_super at o2.pl
Mon Jan 11 23:50:22 UTC 2010
Tom Van Baak pisze:
> Hi Filip,
> See attached. Let me know how your results differ from this.
> It looks like 1.75 hours of frequency data of a 250 MHz DUT.
> You first convert your raw frequency measurement data into
> normalized frequency error data (i.e., subtract and divide by
> f0 = ~250 009 770 Hz).
> You can run the y- form (frequency) of an adev calculation
> directly, or integrate the frequency error series into a time
> error series and run the x- form (phase) of adev calculation.
> I can explain more if you wish.
> JohnM and UlrichB can double check this plot with their tools.
Thank you all for your charts. I forgot to substract and divide by
center frequency ;-)
That data represents a beat note between two optical frequencies: Nd:YAG
laser stabilized to hyperfine transitions of molecular iodine and
optical frequency comb that is phase locked to the SRS FS-725 rubidium
standard. And it seems that AVAR of this measurement is lower than
values for FS-725; AVAR for Nd:YAG laser can be found here:
Does anybody know what is the floor level of AVAR just by counting
frequency (for example using 53132 & Stable32 or SRS620)?
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