| Re: [chrony-users] PPS losing sync on RPiZero |
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- To: chrony-users@xxxxxxxxxxxxxxxxxxxx
- Subject: Re: [chrony-users] PPS losing sync on RPiZero
- From: "DOUG ELCOMB" <delcomb@xxxxxxxxx>
- Date: Tue, 31 Aug 2021 21:51:38 -0400
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- Feedback-id: delcomb@cogeco.
Thanks for the advice. I'm running a test with the changes at the moment.
It looks like I am also seeing occasional big changes in the GPS offset (dropping to 0.15s) for 25-60 sec before returning to the normal value. Got note from Steve Sommars pointing towards gspd causing this. I tried updating to the latest dev version of gpsd without any change in occurrences. If I can keep sync otherwise, the error doesn't get excessive with the dropouts.
Doug
On 21/08/31, Miroslav Lichvar wrote:
> The timing of messages from the GPS is too unstable. The logs show
> the delay is moving between 500 and 800ms. That's too much for
> reliable locking of the PPS refclock (+/- 0.2 second limit in
> chrony-3.4).
>
> > refclock SHM 0 refid GPS precision 1e-1 offset 0.5 delay 0.2 poll 4 noselect
>
> Try changing the precision to 1e-3 and offset to 0.6. That might be
> enough to get the estimated error to fit in that locking limit.
>
> > refclock PPS /dev/pps0 refid PPS precision 1e-9 lock GPS poll 4 trust prefer
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