Ok I've got the new refclock line in place and statistics are logging.
I'll check it in a couple days.
Quick question on binary mode. It's a ublox and GPSD supports it. Would
I get better results if I force the module into binary mode?
On Aug 10, 2016 3:24 AM, "Miroslav Lichvar" <mlich...@redhat.com> wrote:
> On Tue, Aug 09, 2016 at 04:22:56PM -0400, Chris Greenman wrote:
> > Ok I set it to 0.0065 offset. Here's my chrony.conf
> > pool pool.ntp.org
> > driftfile /var/lib/chrony/drift
> > allow
> > refclock SHM 0 refid GPS offset 0.065
> > #refclock SHM 0 refid GPS precision 1e-1 offset 0.9999 delay 0.2
> > makestep 1 -1
> > and here is the chrony sources output:
> > ============================================================
> > #* GPS 0 4 377 12 +2112us[+2967us] +/-
> > 325us
> > ^- orchid.sidereal.ca 2 6 17 19 +11ms[ +12ms] +/-
> > 40ms
> > ^- static-96-244-96-19.bltmm 2 6 17 19 +11ms[ +12ms] +/-
> > 40ms
> > ^- hydrogen.constant.com 2 6 17 18 +14ms[ +15ms] +/-
> > 32ms
> > ^- host2.kingrst.com 2 6 15 19 +9078us[ +10ms] +/-
> > 100ms
> Ok, so now it seems the correction should be actually about 10
> milliseconds smaller. This means the GPS offset is not very stable,
> which is normal with message based (e.g. NMEA) samples. The value
> specified by the delay option should include this interval. If you set
> it to 0.2, the assumed error of the source will be +/- 0.1 seconds. As
> long as the GPS time (corrected by the offset) doesn't move from the
> true time by more than 0.1 seconds, the error interval will contain
> the true time and the source will always agree with other good
> If you enable the statistics log and run it for few days, you will
> probably better see how much the offset moves. If you don't have time
> for that, I think delay of 0.2 seconds should be good enough.
> The recommended refclock line in this case would be:
> refclock SHM 0 refid GPS offset 0.060 delay 0.2 minsamples 64
> The assumed error of the GPS source will now be similar or larger than
> the NTP sources, so if they are online, GPS should be ignored or
> combined with them (+ symbol in the sources output). Only when the NTP
> sources are offline the synchronization will use GPS alone.
> Miroslav Lichvar
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