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Re: PPS in GPSD vs Chrony

From: Dennis Law
Subject: Re: PPS in GPSD vs Chrony
Date: Wed, 1 Jul 2020 17:51:59 +0800

Hello Gary, Miroslav,

Thank you very much for your replies.
Our doubts were clarified.

Thank you.

On Wed, Jul 1, 2020 at 2:12 AM Gary E. Miller <> wrote:
Yo Miroslav!

On Tue, 30 Jun 2020 12:39:03 +0200
Miroslav Lichvar <> wrote:

> On Tue, Jun 30, 2020 at 12:49:13AM -0700, Gary E. Miller wrote:
> > Miroslav Lichvar <> wrote:
> >   
> > > For example, I set the PPS on my ublox units to
> > > 32 Hz to get more samples and improve the stability. 
> >
> > Interesting.  Do you have data on this configuration compared to
> > plain PPS? 
> No, I can't find any data that would compare a 32Hz PPS to 1Hz PPS
> directly. It's been a while since I experimented with it. The jitter
> of samples updating the clock should roughly improve with a square
> root of the PPS rate.

An ntpviz of different polling rates on several of my hosts showed optimal
poll depends on hardware, and is usually between 2 and 4 seconds.  Depending
on whether you are optimings for Frequency offset or Jitter.

If you repear your experiments I'd help you get some data,

Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703  Tel:+1 541 382 8588

            Veritas liberabit vos. -- Quid est veritas?
    "If you can't measure it, you can't improve it." - Lord Kelvin

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