[ntp:questions] Loop Frequency and Offset

David Woolley david at ex.djwhome.demon.invalid
Tue Sep 27 09:20:57 UTC 2011

Richard B. Gilbert wrote:

> I don't believe that accuracy of 1 microsecond , or less, is obtainable 
> without without installing a GPS Timing Receiver or an atomic clock of 
> some sort.

He asked for an offset of 1 microsecond (presumably RMS or 90 
percentile?), not an accuracy of 1 microsecond.

If you ignore systematic errors, an offset of 1 microsecond corresponds 
to an accuracy in the low 100s of nanoseconds.

However, without special instrumentation of both hardware and software, 
he won't be able to measure the systematic error, so an RMS offset in 
the one microsecond region could be associated with a rather larger 
systematic error.

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