[ntp:questions] Re: NTP precision

Tom Smith smith at cag.zko.hp.com
Fri Sep 23 21:23:16 UTC 2005


Richard B. Gilbert wrote:
> If I understand the definition of jitter, it has units of frequency 
> (1/T) and cannot meaningfully be added to or subtracted from time (T).
> 

Regrettably, even that's not clear. See the definitions that Brad
pointed out:

  Jitter
     Short-term variations in Frequency with components greater than 10 Hz.
     The estimated time error of the system clock measured as an exponential
     average of RMS time differences.

and the 4.2.0 documentation for ntpq:

jitter
     The estimated time error of the system clock measured as an exponential
     average of RMS time differences.

-Tom




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