[time-nuts] Trueposition Antenna Location

[Mark Goldberg]

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 <kb8tq at 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 <marklgoldberg at 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 at 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 at lists.febo.com
> To unsubscribe, go to
> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
> and follow the instructions there.
>