Hi ADEV is pretty well documented and the results should *not* be dependent on the sample rate. The proper approach to dropping the sample rate is decimation of the data. I think you may want to look at the way you are doing ADEV.
Bob > On Dec 3, 2018, at 12:30 AM, Mark Goldberg <marklgoldb...@gmail.com> wrote: > > I ran them again today and the results are almost identical. The slower > sample rate still shows a lower ADEV. I am not sure what the algorithm to > determine the peak frequency is but it is described as a linear > interpolation between the two highest peaks on the FFT. I could see how > that could be subject to math errors. For the slower sample rate, the > frequency bins are smaller. I have not researched how all this could affect > the peak frequency and possibly introduce noise (or by truncation remove > small amounts of noise). > > I will run it a few times in the next few days and will also try to move > the antennas to a location with lower multipath. > > Thanks for the suggestions, > > Mark > > > On Sun, Dec 2, 2018 at 2:16 PM Bob kb8tq <kb...@n1k.org> wrote: > >> Hi >> >> Looking at the data, I’m guessing the slower sample rate was done last. If >> so, >> you may not be letting the GPSDO’s “warm up” long enough. Most designs >> take days (if not weeks) to get to their ultimate stability. >> >> Bob >> >>> On Dec 2, 2018, at 11:16 AM, Mark Goldberg <marklgoldb...@gmail.com> >> wrote: >>> >>> I broke down and drilled a couple holes in the wall and moved the >> antennas >>> for both GPSDOs outside with a better view of the sky, but still somewhat >>> shielded by the house and a metal RV cover. The number of sats is way up >>> and the TruePosition is in normal mode most of the time. The ADEV is not >>> improved and actually measured worse. I took data for twice as long at >> two >>> sample rates, 0.6816 sec and 5.453 sec. The ADEV from the slower sample >>> rates is lower, possibly due to the measurement method, but they all are >> in >>> the same order of magnitude. I've named the Heather screen captures for >> the >>> inside and outside locations and shown one combined Timelab capture. >>> >>> Regards, >>> >>> Mark >>> >> <TruePos_Outside_Ant_Heather.png><TruePos_Inside_Outside_Compare_Ant_Allan.png><TruePos_Inside_Ant_Heather.png>_______________________________________________ >>> time-nuts mailing list -- time-nuts@lists.febo.com >>> To unsubscribe, go to >> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com >>> and follow the instructions there. >> >> >> _______________________________________________ >> time-nuts mailing list -- time-nuts@lists.febo.com >> To unsubscribe, go to >> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com >> and follow the instructions there. >> > _______________________________________________ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. _______________________________________________ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.