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Diffstat (limited to 'www')
| -rw-r--r-- | www/gpsd-time-service-howto.txt | 30 |
1 files changed, 30 insertions, 0 deletions
diff --git a/www/gpsd-time-service-howto.txt b/www/gpsd-time-service-howto.txt index 6bdc7c36..fc793050 100644 --- a/www/gpsd-time-service-howto.txt +++ b/www/gpsd-time-service-howto.txt @@ -528,6 +528,36 @@ If the offset is positive, reduce the time1 value and vice versa. A more detailed description of the output is available at <<NTPQ-OUTPUT>>. +In order to determine the correct GPS offset, do the following: + +1. Add these lines to ntp.conf: + +----------------------------------------------------------------------------- +statsdir /var/log/ntpstats/ +statistics peerstats +filegen peerstats file peerstats type day enable +----------------------------------------------------------------------------- + +This enables logging of the peer server statistics. + +2. Start ntpd and let it run for at least four hours. + +3. Calculate the average GPS offset: + +----------------------------------------------------------------------------- +awk ' + /127\.127\.28\.0/ { sum += $5 * 1000; cnt++; } + END { print sum / cnt; } +' </var/log/ntpstats/peerstats +----------------------------------------------------------------------------- + +This prints the average offset. + +5. Adjust the "time1" value in ntp.conf by subtracting the average + offset from step 4. + +6. Restart ntpd. + == Providing public NTP service == <<NTP-FAQ>> has good advice on things to be sure you have done - and |