Re: [chrony-users] Chrony does not select PPS source

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On Mon, Sep 11, 2017 at 03:01:13AM +0000, Simon Haines wrote:
> The GPS is connected through gpsd using the SHM driver, and I've confirmed
> it is working (refclock log is below). Here is my chrony.conf:
> # cat /etc/chrony.conf
> refclock PPS /dev/pps0 lock NMEA
> refclock SHM 0 offset 0.5 delay 0.2 refid NMEA noselect

Try changing the offset to 0.1. From the log below it looks like the
offset between the two refclocks is too large and prevents their

> 1970-01-01T01:03:34Z refclock.c:465:(RCL_AddPulse) refclock pulse ignored
> offdiff=0.380447388 refdisp=0.000001260 disp=0.000000001
> 1970-01-01T01:03:34Z refclock.c:723:(filter_add_sample) filter sample 2
> t=3814.536533857 offset=1505092242.963466167 dispersion=0.000001000
> 1970-01-01T01:03:35Z refclock.c:465:(RCL_AddPulse) refclock pulse ignored
> offdiff=0.381711483 refdisp=0.000001260 disp=0.000000001

> Further help with synchronising to the PPS would be appreciated, as would
> any configuration advice for an isolated system with a large time delta at
> boot (I am considering 'makestep 0.1 300' assuming 5 minutes for the GPS to

Please note that the second argument of makestep is number of updates
and not seconds.

Miroslav Lichvar

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