See last page for copyright and document info, File: Reeve_GpsNtp-Pi_Setup.doc, Page 23
Restart the NTP service:
sudo service ntp restart
After a few minutes run NTP Query (all query command options are defined in {
NTPQ
}:
ntpq –p
The * in the first column of the first line indicates the shared memory GPSD reference clock is being used. The o
in the first column of the second line indicates the kernel-mode PPS source is selected and being used. Other
symbols may appear in the first column; see table at end of this section. To see additional details, use more
command line options in the query tool. In the example display below the remote column shows the local
address of the KPPS (driver designated .22) rather than its name PPS(0):
ntpq -crv –pn
ntpq -crv –p
If you repeat the query command over periods of tens of minutes, you should see the PPS offset slowly decrease
toward zero. If it does not, you may have a typing error in ntp.conf. The first query shown in the example above
shows a PPS offset of 1.598 ms and the next query above, taken some time later, shows an offset of 0.001 ms (1
μs).
If you do not see the PPS source, it is possible the NTP server is picking up the NTP information via DHCP, which
is overriding the settings above. Do this:
sudo rm /etc/dhcp/dhclient-exit-hooks.d/ntp
sudo rm /var/lib/ntp/ntp.conf.dhcp
sudo reboot
After reboot, log into the RPi. To view various statistics that were enabled in the ntp.conf file, use WinSCP to go
to the root directory
