[ntp:questions] Can NTP sync within 1ms

Jason Rabel jason at extremeoverclocking.com
Sun Apr 27 13:31:22 UTC 2014

> First, we sync all machines to locally connected GPS receivers with
> PPS output.  We use ntpd and kernel PPS.  This is wellknown territory.

> In the ntpq -p stats this appears to bring the systems within 10us,
> often within 2us, of the PPS signal.  We still have to find out if this
> is reality or just output of a program.

You need to look up the specs of your GPS units to see what the PPS performance is spec'ed for. That uncertainty needs to be
factored into your final figure.

Likewise, are you inputting surveyed antenna coordinates at each location or just letting the receiver auto-survey? If the "assumed"
position is off that is another source of time error.

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