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

Unruh unruh-spam at physics.ubc.ca
Wed Oct 22 23:07:33 UTC 2008

nb at komeda-berlin.de (Nicola Berndt) writes:

>Hal Murray schrieb:
>>> A termistor on the crystal on the other hand might be useful to compensate
>>> the temperature ( there is an alteration of ntp which also calculates the
>>> temp compensation of the crystal and uses that to calculate the required
>>> drift rate.-- unfortunately I do not remember its name of location on the
>>> web)
>>   NTP temperature compensation
>>   Mark Martinec, 2001-01-08
>>   http://www.ijs.si/time/temp-compensation/
>> A wonderful read.
>Really nice one, thx for the link!

>Also thx to everyone thinking about a solution.

>A good idea might be to find someone who would program GPS/PPS support 
>for chrony. Many people would benefit from it. We also have a good 
>programmer working with us and he is already looking into things..

I keep thinking about it, but I am not a good programmer, and first one has
to understand chrony well enough to start hacking it. What would be really
nice is to install a glue layer so one could simply take the ntp refclock
files and compile them into chrony. Unfortunately the ntp people did not
isolate the refclock behaviour terribly well, but it should be relatively
easy for a good programmer to write such glue ( chrony also has a
reasonably well issolated glue to the server querying stuff)

>I also have to further investigate the sudden change of behaviour I 
>experienced and if I found the reason I will have to try to start the 
>machine in a very cold room, on the heating and so on.. If it would 
>settle down within 15 Minutes, we could live with it...


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