[ntp:questions] What is the NTP recovery time from 16s step in GPS server?

David Taylor david-taylor at blueyonder.co.uk.invalid
Tue Oct 30 19:21:46 UTC 2012

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?
Web: http://www.satsignal.eu

More information about the questions mailing list