[ntp:questions] garmin 18x and linux

Courtney Bane ntp-5620 at cbane.org
Fri Sep 2 03:14:33 UTC 2011

On Fri, Sep 02, 2011 at 02:24:44AM +0000, Greg Hennessy wrote:
> Given that ntp in debug mode shows gpsread showing NTP at least sees
> the GPRMC messages, can anyone sugguest why NTP never syncs? Is there
> additional debug flags that would be useful?

NTP isn't syncing because the GPS is reporting that it doesn't have a
valid fix.

> $GPRMC,195342,V,3855.3261,N,07704.0687,W,,,010911,010.8,W*68

The "V" in the second data field means that the fix is invalid (it will
be "A" if it's valid). See the documentation for the NMEA driver[1] for
details on just what each of the fields mean.

As an example of what you should see when the GPS is working properly,
here's a recent NMEA sentence from my Garmin 18-LVC (with the location


[1] http://www.eecis.udel.edu/~mills/ntp/html/drivers/driver20.html

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