Thanks Miroslav, actually, my GPS module can be setup to issue NMEA sentences at a user specified frequency, so I think I'll start with 2Hz then see how high can it go... I'll report back when I have new results.
Cheers Enzo ________________________________ From: Miroslav Lichvar <mlich...@redhat.com> Sent: Wednesday 31 March 2021 10:21 To: chrony-users@chrony.tuxfamily.org <chrony-users@chrony.tuxfamily.org> Subject: Re: [chrony-users] How to use a "PPS" with freq higher than 1Hz? On Tue, Mar 30, 2021 at 04:48:55PM +0000, Vincenzo Miceli wrote: > Thanks Miroslav, > > I was able to get the PPS to start by removing the "lock GPS" and using a > public NTP. I guess the NMEA coming from the GPS has too much jitter then? I > don't fully understand though as the NMEA is always coming once a second and > at higher frequencies (I would think) the chrony algorithm has to deal with > more samples closer together and can still sample the GPS once a second and > compare that with the 10 pulses per second, maybe with the PPS-GPS separation > still working off the 200msec limit... I'm sure there are good statistical > reasons though 🙂🙂 If the NMEA rate stays at 1 per second (some receivers can be configured to report at a higher rate) then you would need to increase maxlockage of the PPS refclock. The locking feature uses just the latest sample. In theory it could use a longer-term average, but I'm not sure if it's worth the complications. -- Miroslav Lichvar -- To unsubscribe email chrony-users-requ...@chrony.tuxfamily.org with "unsubscribe" in the subject. For help email chrony-users-requ...@chrony.tuxfamily.org with "help" in the subject. Trouble? Email listmas...@chrony.tuxfamily.org.
