[ntp:questions] Re: HowTo calibrate system clock frequency using NTP

David L. Mills mills at udel.edu
Fri Feb 3 14:33:23 UTC 2006


Daniel,

The frequency measurement uses the feedback loop described in detail on 
the architecture and clock discipline briefings on the NTP project page 
linked via www.ntp.org. A simple average is not good enough as it does 
not account for the heavy-tail effects due to the random-walk character 
of the clock oscillator frequency.

Dave

Daniel Kabs wrote:

> David Woolley wrote:
> 
>> Incidentally, I find a simple average is good enough to get 30 second
>> a year accuracy in an air conditioned environment, providing you do it
>> over about a week.
> 
> 
> I'd like to know: how do you measure the frequency error of your system 
> clock? Are you reading the ntp.drift file after running ntpd for some days?
> 
> 
> Cheers
> Daniel




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