---
www/gpsd-time-service-howto.txt | 8 ++++++++
1 file changed, 8 insertions(+)
diff --git a/www/gpsd-time-service-howto.txt b/www/gpsd-time-service-howto.txt
index a92a87f..6672fbe 100644
--- a/www/gpsd-time-service-howto.txt
+++ b/www/gpsd-time-service-howto.txt
@@ -788,18 +788,23 @@ log statistics measurements tracking
This enables logging of the peer server statistics.
+[start=2]
2. Make sure the directory exists properly. For ntpd as root do:
# mkdir -p /var/log/ntpstats
# chown ntp:ntp /var/log/ntpstats
For chronyd as root do:
+----------------------------------------
# mkdir -p /var/log/chrony
# chown root:root /var/log/chrony
+----------------------------------------
+[start=3]
3. Start ntpd (or chronyd) and let it run for at least four hours.
Periodically check progress with "ntpq -p" or "chronyc sources" and wait
until change has settled out.
+[start=4]
4. Calculate the average GPS offset using this script (a copy is
included as contrib/ntpoffset in the GPSD distribution):
@@ -812,6 +817,7 @@ awk '
This prints the average offset.
+[start=5]
5. Adjust the "time1" value for unit 0 of your ntp.conf (the non-PPS
channel) by subtracting the average offset from step 4.
@@ -828,6 +834,7 @@ example:
SHM 0 configured as:
refclock SHM 0 poll 8 filter 1000 noselect
+------------------------------------------------------------------------
# chronyc sourcestats
210 Number of sources = 6
Name/IP Address NP NR Span Frequency Freq Skew Offset Std Dev
@@ -838,6 +845,7 @@
mort.cihar.com 21 8 72m 0.148 0.798 +668us 490us
vps2.martinpoljak.net 6 4 17m -53.200 141.596 -24ms 15ms
ntp1.kajot.cz 25 16 91m -0.774 1.494 -11ms 1859us
ntp1.karneval.cz 17 10 89m 0.127 0.539 -4131us 574us
+--------------------------------------------------------------------------------
In this case (Garmin 18x) the offset specified in the config for the
SHM 0 source should be around 0.495.
--
1.8.3.2