[ntp:questions] Start of new GPS 1024 week epoch

David Taylor david-taylor at blueyonder.co.uk.invalid
Sun Aug 18 05:51:59 UTC 2013

On 17/08/2013 18:31, Magnus Danielson wrote:
> What might be useful is to store the corrected 1024 weeks offsets, since
> if the NTPD is restarted, those corrections can be applied up-front and
> then can these corrected values be used to provide good basis for
> majority decisions about "correct time". When a particular receiver
> flips, then it is the only one (possibly a few of them changing at the
> same time) which shift by 1024 weeks, and then it is easy to use the
> 1024-week assumption as a priori knowledge to correct them. When you
> wake up the flipped receivers may form a majority, which would be
> unfortunate, as we already know they have flipped, but we forgot it in
> the re-start process. Doing this, the system integrity can be maintained
> throughout.
> Cheers,
> Magnus

It will be interesting to see what folks come up with for the patch.  I 
must admit to feeling that a fault in GPS receivers should /not/ have to 
be fixed in NTP, but I accept that's likely to be the best solution.

It should certainly be an option that has to be specifically enabled 
(command-line switch or fudge command), and one which has no impact 
otherwise on the reliability and maintainability of NTP.
Web: http://www.satsignal.eu

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