[ntp:questions] NTP with GPS and RTC

David Woolley david at ex.djwhome.demon.invalid
Sat Apr 27 08:13:38 UTC 2013


David Taylor wrote:
> On 26/04/2013 20:20, David Woolley wrote:
>> David Taylor wrote:
>>
>>>
>>> I don't see that here.  With a local PPS reference you get within a
>>> few microseconds within an hour.  If the precision needed is less than
>>> that,
>>
>> We are discussing getting a good frequency lock, so that it will coast
>> well, rather than a good time lock.
> 
> If the time is stable, the frequency must also be stable, no?

If the time error is low and bounded the frequency error does not 
necessarily have a low error bound.  Simply polling fast and using a 
short loop time constant can give you a low error bound on the time, if 
the network delays are stable and the source is good.



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