[time-nuts] Frequency Ensemble

[Dan Kemppainen]

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