[ntp:questions] ARRGH!!! I woke up to a 50 SECOND clock error.

David J Taylor david-taylor at blueyonder.co.uk.invalid
Tue Mar 13 18:04:38 UTC 2012

> Hi all,
> I just woke up to a 50 SECOND clock error.  Prior to the error, with my 
> PC locked into the GPS and the internet servers noselected, here's what 
> my peerstats looked like.  Baseline is the GPS.  Colored lines are 
> internet servers.
> My system is Windows 7, NTP 4.2.7p259, GPS GlobalSat BU-353 USB NMEA 
> only with GPGGA sentence at 57,600 baud.
> If anyone can shed some light on what happened, please do.  It's driving 
> me bonkers.  I don't believe the GPS is at fault, and I suspect NTPD.
> Thanks in advance.
> Sincerely,
> Ron

As all the Internet servers agreed (in another graph you showed me), I 
would suggest that you stick with the Internet servers and discard that 
GPS!  I hope it will be better with the PPS from the Sure board.  At least 
remove the noselect from the Internet servers so that NTP can do its job 
properly.  At the moment you are telling NTP to trust the GPS no matter 
what it says.  Can't think that sounds the wisest option.  I might be 
inclined to add noselect to the GPS and measure it against the Internet 


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