[time-nuts] Frequency Ensemble

[Michael Wouters]

Hello Dan,

As promised here is a comparison of the ZED-F9P and NEO-M8T
sawtooth-corrected PPS. The PPS is measured against a 5071 with standard
tube. Three days of data were used. The 5071 was measured against another
5071 and I divided the TDEV by sqrt(2). The 5071 data at shorter than 300s
is limited by the counter resolution so I didn't show it. The ZED-F9P is
significantly better than the M8T between 10 and 1000 s but much the same
past 10000s.

Cheers
Michael

On Tue, 19 Mar 2019 at 8:02 am, Dan Kemppainen <dan at irtelemetrics.com>
wrote:

> Bob,
>
> I recalled the plot you posted a few days ago. Nice plot on the F9P,
> BTW. Thanks for posting that.
>
> I don't supposed you happened to be recording a similar plot with a L1
> only Ublox part at the same time by chance, did you? I think it would be
> interesting to compare a 6T or M8 part to the F9P. (I lack a standard
> good enough to compare them to...)
>
> Thanks!
> Dan
>
>
>
>
> On 3/18/2019 1:00 PM, time-nuts-request at lists.febo.com wrote:
> > Message: 2
> > Date: Mon, 18 Mar 2019 12:26:55 -0400
> > From: Bob kb8tq<kb8tq at n1k.org>
> > To: Discussion of precise time and frequency measurement
> >       <time-nuts at lists.febo.com>
> > Subject: Re: [time-nuts] Frequency Ensemble
> > Message-ID:<88460EA2-6034-48D1-A77A-FED1F824D843 at n1k.org>
> > Content-Type: text/plain;     charset=utf-8
> >
> > Hi
> >
> > There are a variety of GPS devices that put out a PPS. uBlox makes some,
> there
> > are a number of other companies that do so. The PPS comes out modulo the
> local
> > timebase. On a precision part, there is a ?sawtooth correction? message
> that also
> > comes out to further quantify the best guess time of that pulse.
> >
> > Noise wise, even with correction you are lucky to get a one second ADEV
> in the
> > 1 to 2 ppb range with a typical L1 receiver. With a L1 / L2 device like
> the F9P,
> > you might do a bit better than that.
> >
> > The ADEV of your other sources at short tau will be much better than the
> GPS PPS
> > noise. As you average out over long periods, the GPS will win the race.
> >
> > Bob
>
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