| Re: [chrony-users] trying to get Chrony to work with gpsd/PPS GPS |
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- To: chrony-users@xxxxxxxxxxxxxxxxxxxx
- Subject: Re: [chrony-users] trying to get Chrony to work with gpsd/PPS GPS
- From: Miroslav Lichvar <mlichvar@xxxxxxxxxx>
- Date: Mon, 11 Sep 2017 11:32:34 +0200
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On Thu, Sep 07, 2017 at 06:49:42PM -0400, Bryan Seitz wrote:
> # Garmin GPS 18 LVC
> server 127.127.20.0 mode 0 minpoll 4 maxpoll 4 prefer
> fudge 127.127.20.0 time2 0.600 flag1 1 flag2 0 flag3 1 refid PPS
flag3 enables the kernel PPS discipline, which uses a 1-second update
interval. If you wanted to have something similar with chronyd, you
would need to shorten the polling by adding "poll 0" to the refclock
directive. I think in most cases with a serial PPS input that is too
short, so I'd suggest to try "poll 2" first.
> refclock SHM 0 offset -0.6 delay 0.5 refid NEMA noselect
> refclock SHM 1 offset -0.6 precision 1e-9 lock NEMA refid PPS
The second "offset -0.6" should be removed. Unless a wrong edge of the
PPS signal is used, the offset is typically just a few microseconds.
--
Miroslav Lichvar
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