[ntp:questions] How to debug GPS PPS?

David Lord snews at lordynet.org
Fri Feb 12 21:30:10 UTC 2010


xyz-2041 wrote:
> OK.  Couldn't get the Oncore unit to work in any way
> shape or form.  I bought a DB9 LED tester like this:
> 
>   <http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=260546635257>
> 
> Had PPS going to pin 1, DATA OUT to pin 2, and DATA IN to pin 3.
> Still
> no good.
> 
> Bought a Garmin GPS 25-LVC, put it in an enclosure, commented
> out the Oncore driver and added to ntp.conf:
> 
>   # Garmin / PPS driver:
>   server 127.127.20.0   prefer
>   fudge  127.127.20.0   refid GPS
> 
> Restarted:
> 
>   /etc/rc.d/ntpd restart
> 
> Checking the status:
> 
>   # ntpq -c pe
> 
>        remote           refid      st t when poll reach   delay
> offset  jitter
>   ==========================================================
>   xGPS_NMEA(0)     .GPS.            0 l   15   64  377    0.000
> -716.52 105.934
> 
> 
> Looks like it is being read, but is off by quite a bit.  Any ideas on
> how
> to get it to behave?
> 

Might be useful to install and run gpsd. The debug mode
is useful. Also worth trying that with your Oncore as
you stated upthread having had that working from windows.

Also outputs from /var/log/ntp/ntp.log (or wherever you
log to) and ntpd lines in /var/log/messages might give
some help.


David




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