[ntp:questions] Drift handling....

David J Taylor david-taylor at blueyonder.co.not-this-bit.nor-this-part.uk.invalid
Sun Jan 1 14:44:38 UTC 2006

It seems to me that a good proportion of my problems at the leap-second 
were due to the drift file suddenly being set to a large value (just short 
of 500).  NTP was able to recover from this on two PCs, but not on the 
other two.  The drift file was altered to this new value within an hour of 
midnight (UTC).

Is it possible to make it much less easy for NTP to alter the drift file 
value - for example to require a different measured value for e.g. 24 
hours before the drift is taken as having changed?  Of course, I only see 
the value in the drift file, but I presume I am really talking about the 
internal clock drift rate value.

Does altering that internal drift rate improve the stability over the 
diurnal temperature cycle?  If so, could you do something like keeping a 
drift history (say) once every 6 hours, so that a measure of the diurnal 
instability was known by four samples, each averaged over several days? 
And then, only if a whole day's values (four sets) were different, would 
you assume that something really had changed?

I don't know if what I'm asking for is sensible or feasible, but I put it 
up for comment.


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