Problem with GPSD refclock

Rich Wales richw at
Thu Jan 26 03:38:04 UTC 2017

Gary E. Miller wrote:

> The GPS/JSON refclock never really worked.  I have been thinking
> about fixing it for ntpsec.

Hmmm.  I'd be interested in hearing more about the problems with this
refclock.  I'd been using SHM in 4.2.8 for a very long time, until I
switched to the GPS/JSON refclock recently, and they both have seemed to
work solidly as far as I've been able to tell (again, with the old ntpd
4.2.8, not with ntpsec).

I already tried the following refclock line with ntpsec, but it didn't
work at all (silently ignored):

refclock shm prefer unit 1 minpoll 3 maxpoll 3 stratum 0 refid GPS

I'm wondering if I'm doing something fundamentally wrong in my
configuration that is causing the refclocks to be simply ignored.

FWIW, my GPS has PPS support, and it's attached to my system via a real
RS232 serial port (*not* serial-over-USB), so the PPS really does work

Rich Wales
richw at

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