[ntp:questions] GPS-PPS, standalone server. NTP

Miroslav Lichvar mlichvar at redhat.com
Wed Jun 21 12:37:34 UTC 2017

On Tue, Jun 20, 2017 at 06:13:14AM -0700, Fida Hasan wrote:
> From this point onward, if I set up ntp, it get fix with the drivers and working fine. However, according to the instruction here:
> http://catb.org/gpsd/gpsd-time-service-howto.html#_feeding_chrony_from_gpsd
> 3. I installed chrony and gpsd into my system. And always ensured that Chrony is Running before gpsd.
> allow 0/0
> refclock SHM 1 refid GPS precision 1e-1 offset 0.9999 delay 0.2
> refclock SOCK /tmp/chrony.ttyS0.sock refid PPSS
> But I don't get any result. It is sure that chrony does not get feed from GPSD. 

With the pps-gpio module gpsd doesn't know that /dev/pps0 is related
to /dev/ttyS0. You might need to start gpsd with both devices
specified on the command line. I'm not sure since what version that is

If that doesn't work and chrony was compiled with PPS support, you
could use gpsd just for the message-based samples provided in SHM 0
and use the PPS device directly. For example:

refclock PPS /dev/pps0 poll 2 lock NMEA refid GPS
refclock SHM 0 offset 0.5 delay 0.2 refid NMEA noselect

Miroslav Lichvar

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