[chrony-users] Synchronize system clock to GPS time

["Ryan Govostes (he/him)" <rgovostes@xxxxxxxx>]

I have a GPS receiver with PPS connected to an embedded Linux system. GPSD feeds Chrony time updates from the GPS receiver over the Chrony socket.

The system clock is behind by a few months, and Chrony does not want to update the clock to the time reported by GPSD.

I have read the FAQ and a few threads on the same topic but the solutions presented don’t work for me. I have tried setting maxdistance to an absurdly high number, and allowing  makestep 1 -1.

The “chronyc sources” command suggests that Chrony thinks that the GPS is in error. There is no console message that says that Chrony is attempting to adjust the clock.

Can I force Chrony to accept the time from the GPS?

Thanks,
Ryan


$ chronyc sources
210 Number of sources = 3
MS Name/IP address         Stratum Poll Reach LastRx Last sample               
===============================================================================
#x GPS                           0   4   377    11   -2002h[ -2002h] +/-  100ms
#x PPS                           0   4   377    10   -2002h[ -2002h] +/- 2919ns
^? asdf.xyz                      0   9     0     -     +0ns[   +0ns] +/-    0ns

$ chronyc tracking
Reference ID    : 00000000 ()
Stratum         : 0
Ref time (UTC)  : Thu Jan 01 00:00:00 1970
System time     : 0.000000041 seconds fast of NTP time
Last offset     : +0.000000000 seconds
RMS offset      : 0.000000000 seconds
Frequency       : 404.716 ppm fast
Residual freq   : +0.000 ppm
Skew            : 0.000 ppm
Root delay      : 1.000000000 seconds
Root dispersion : 1.000000000 seconds
Update interval : 0.0 seconds
Leap status     : Not synchronised

$ cat /etc/chrony/chrony.conf 
server asdf.xyz iburst prefer

# This directive specify the file into which chronyd will store the rate
# information
driftfile /var/lib/chrony/chrony.drift

# Log files location
logdir /var/log/chrony

# Stop bad estimates upsetting machine clock
#maxupdateskew 100.0

# This directive enables kernel synchronisation (every 11 minutes) of the
# real-time clock
rtcsync

# Step the system clock instead of slewing it if the adjustment is larger than
# one second, but only in the first three clock updates
makestep 1 -1

# 
maxdistance 100000000

refclock SOCK /run/chrony.ttyCOM2.sock refid GPS precision 1e-1 offset 0.9999
refclock SOCK /run/chrony.ppsCOM2.sock refid PPS precision 1e-7