[ntp:questions] NMEA ref.clock better than my ISP's timeserver?

David Woolley david at ex.djwhome.demon.co.uk.invalid
Fri May 29 06:45:53 UTC 2009


Richard B. Gilbert wrote:

> 
> It doesn't "compensate"!  It simply tells you the maximum uncertainty 
> introduced in transmitting the request and reply.  You know that it 
> can't be worse than one half of the round trip time.  All other things 
> being equal, the lowest round trip time gives you the best time.
> 

It does compensate.  However the degree of compensation may be wrong by 
anywhere between + and - half the round trip time.

The compensation is added to the time estimates, but is also added to 
the error bound calculation.




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