[ntp:questions] Slow convergence of NTP with GPS/PPS

David Woolley david at ex.djwhome.demon.co.uk.invalid
Tue Sep 30 20:12:36 UTC 2008


Richard B. Gilbert wrote:

> 
> If you are using a recent version of ntpd, start it with the "-g" 
> switch.  That will cause it to set the clock to the correct time once 
> only!  If you have a good drift file, you should be synchronized in 
> thirty seconds or so and be within ten milliseconds, or less, of the 
> correct time.

My understanding was that -g turns off the 1000 second check for the 
first step, but still leaves the time within +/- 128ms, which will still 
take an unacceptable time to converge to +/- 5ms.  Certainly the 4.2.4p4 
documentation makes no claims for it beyond once only disabling the 1000 
second check.

> 
> Try not to reboot unless absolutely necessary.  I realize that some 
> versions of Windows need fairly frequent reboots but there are are 

I imagine this is some sort of embedded system, which he can't control, 
but might be switched off outside office hours, in part because that is 
the socially responsible thing to do.




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