| Re: [chrony-users] How to set GPS and PPS source offline |
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On Thu, Nov 24, 2016 at 10:25:26AM +0100, Wielant, Ulrich wrote:
> After chrony synchronized once to the PPS it never selects another time source although the PPS/GPS signal might disappear. This might be the case if gpsd is not running, the GPS is off or the GPS has no fix.
>
> MS Name/IP address Stratum Poll Reach LastRx Last sample
> ===============================================================================
> #- GPS 0 4 0 21m +44ms[ +44ms] +/- 200ms
> #* PPS 0 4 0 21m -1211ns[-2913ns] +/- 1634ns
> ^- ntp03.cc-netzwerk.de 3 8 377 47 -1809us[-1809us] +/- 42ms
> ^- ts1.sct.de 2 8 377 55 -403us[ -403us] +/- 60ms
> ^- news01.nierle.com 2 8 377 246 -1518us[-1518us] +/- 38ms
> ^- xserv-01.tenretni.org 2 8 377 53 -4528us[-4528us] +/- 58ms
>
> What do I have to do so that chrony no longer synchronizes to the non available PPS/GPS source?
Just wait a bit longer :). The PPS source was much better than the NTP
servers, so it may take couple hours before chronyd assumes the clock
has drifted so much that it should switch to the significantly worse NTP
sources. It's a feature, not a bug. If chronyd switched immediately to
another source, that would be bad for accuracy of the clock, e.g. when
the GPS has a weak signal and PPS stops for couple of minutes at a
time.
> I would also modify the stratum of the PPS/GPS source but this doesn't seem to be possible with refclock sources. Correct?
Right, there is currently no option to set stratum for refclocks. It
wouldn't make much of a difference in the source selection anyway.
--
Miroslav Lichvar
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