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-requ...@lists.febo.com wrote:
Message: 2
Date: Mon, 18 Mar 2019 12:26:55 -0400
From: Bob kb8tq<kb...@n1k.org>
To: Discussion of precise time and frequency measurement
<time-nuts@lists.febo.com>
Subject: Re: [time-nuts] Frequency Ensemble
Message-ID:<88460ea2-6034-48d1-a77a-fed1f824d...@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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