[ntp:questions] stupid, simple question about precision

Richard B. Gilbert rgilbert88 at comcast.net
Thu Nov 16 19:07:27 UTC 2006


Simple Simon wrote:

> If 'ntpq -c rl' shows the precision of my clock as -20 (roughly, 
> 9ns), does that translate to timestamp confidence interval of +/- of 
> 9ns, or of +/- of 4.5ns) ?
> 
> Feel free to point to me to the section of the NTP FAQ I've missed, 
> or any other resource that I haven't seen in trying to answer this 
> question on my own.
> 
> Any guidance greatly appreciated.

I think you are mistaking precision for accuracy.  Precision is the 
measure of the shortest interval your clock can represent.  It has 
nothing (or very little) to do with accuracy.

ntptime will show you the estimated error for your clock.  Unless you 
are using a hardware reference clock, the estimated error may be in 
milliseconds rather than microseconds.




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