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 <[email protected]> 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 <[email protected]> > 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 -- [email protected] > > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > > and follow the instructions there. > > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. > _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
