On 30/10/2012 17:57, David Woolley wrote:
David Taylor wrote:
However, suppose I had /only/ the GPS receiver? NTP has the GPS time
and the PPS signal for the exact second, syncs, and then a few minutes
in the time suddenly changes by 16 seconds. I would hope that then
causes NTP to step the clock onto UTC rather than GPS time. I realise
that the time for the GPS receiver to be sending UTC rather than GPS
time varies, but how long might it then take NTP to react to the 16
second change, and alter the system clock? Both the PPS and the gpsd
are being polled at fixed 16 second intervals.
It's not a specified characteristic, as it is a GIGO case. However, I
believe it it is the order of 20 minutes, with standard parameters. Most
of this is for ntpd to convince itself that the local clock time it has
really is wrong.
Thanks, David. Do you think that it would still be 20 minutes when the
clock in question is being polled every 16 seconds?
--
Cheers,
David
Web: http://www.satsignal.eu
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