| Re: [chrony-users] SatPulse: server-oriented alternative to gpsd for chrony |
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- To: James Clark <jjc@xxxxxxxxxx>
- Subject: Re: [chrony-users] SatPulse: server-oriented alternative to gpsd for chrony
- From: Miroslav Lichvar <mlichvar@xxxxxxxxxx>
- Date: Tue, 14 Apr 2026 09:55:17 +0200
- Cc: chrony-users@xxxxxxxxxxxxxxxxxxxx
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On Tue, Apr 14, 2026 at 04:25:07AM +0200, James Clark wrote:
> Yes, it is. It is not hugely noticeable with an F9T (because the sawtooth
> amplitude is small), but it does make a significant difference with an M8T.
>
> Embarassingly, I had the sign wrong for a while. When I fixed that, it made
> quite a noticeable difference to the M8T:
>
> https://github.com/jclark/satpulse/discussions/163#discussioncomment-15656148
That looks great. I'm curious to see how it compares to higher-rate PPS +
filtering. IIRC the u-blox sawtooth correction works only with 1Hz PPS.
> I have sometimes wondered whether it would be possible to extend the
> refclock SOCK interface so that something like satpulse could provide
> sawtooth corrections when chrony is reading the PPS, especially with PHC
> extpps. Concretely, it would be an addiional kind of message giving the
> amount of the correction as a float and the true time of the pulse (e.g.
> UTC in ms) to which it applied.