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ntpq -p 50m
remote refid st t when poll reach delay offset jitter
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LOCAL(0) .LOCL. 10 l 20d 64 0 0.000 0.000 0.000
oGPS_NMEA(0) .GPS. 0 l 5 16 377 0.000 -0.001 0.031
The above shows the system GPS reference clock is offset from the GPS system CPU clock by -0.001 milliseconds. The "reach" value for GPS_NMEA should be 377 (octal value of all 1's). The reach for the LOCAL clock is always 0.
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The above shows that the clock on flux agrees to within a maximum 52 microseconds with each DSM, as indicated by the "Last sample" value in brackets. The second character should be '*' (chrony on flux is sync'd to this server) or '+' (good server). Sometimes I've seen '-' (lately on 100m for some reason) indicating chrony does not have a high opinion of its time information, relative to the others.
The "reach" values should again be 377. If not, it means the DSM is not on the network, or its NTP server is not responding or sync'd to its GPS.
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