[ntp:questions] NTP Cheat Sheet

David L. Mills mills at udel.edu
Thu May 8 03:21:49 UTC 2008


Kevin,

Strange. I have an EndRun Cntp, bu it has an Ethernet interface. If 4 
works for you use it. That's a pretty grotty driver with all kinds of 
bandaids to deal with long forgotten radios; I wonder why EndRun chose 
that driver...

Dave

Kevin Oberman wrote:
> Dave,
> 
> Thanks for the quick response, but I guess I failed to make one point
> clear. 
> 
> EndRun supplies only the hardware. It is the Ct which as only a serial
> interface which is plugged into a standard COM port on the server. They
> don't provide any software at all. The clock just provides the time
> string every second (with an offset of about 10 ms. and jitter in the
> area of 3-5 ms.) and a very accurate PPS which allows us sync within
> about three usec. (The clock spec is better than ten usec, but three
> seems the norm.)
> 
> I am running 4.2.0-a using the stock TrueTime and PPS drivers. The
> FreeBSD kernel has PPS support included, so any filtering in the
> TrueTime driver should be of little or no impact.
> 
> I am assuming than as long as I am using PPS and training the TrueTime
> source, a minpoll of 4 is reasonable and I just wanted to make sure that
> I am not wrong in doing this.




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