[ntp:questions] garmin 18x and linux

steven Sommars stevesommarsntp at gmail.com
Sat Sep 3 13:05:21 UTC 2011


I monitored Garmin LVC (corrected firmware) NMEA time and saw variance of up
to 50msec.  I wonder if the variation in NMEA time depends on GPS signal
quality.


On Fri, Sep 2, 2011 at 11:19 PM, unruh <unruh at wormhole.physics.ubc.ca>wrote:

> On 2011-09-02, David Woolley <david at ex.djwhome.demon.invalid> wrote:
> > Rob wrote:
> >
> >>
> >> You will find (you have found) that by posting on this group, your
> message
> >> falls into the hands of a small group of people that will either base
> >> all their solutions on much more stringent requirements than you
> actually
> >> have (e.g. they don't consider using GPS serial messages because it is
> >> not possible to have millisecond precision with that), or they go on an
> >> on about how the requirements you post cannot be achieved at all and
> should
> >> be relaxed or be realized with atom clocks etc.
> >
> > NTP isn't designed to work at accuracies worse than a few 10s of
> > milliseconds.
>
> ?? Where does this come from? While it is true that there is the 128ms
> rule ( which I believe can be adjusted) but where is this coming from?
> And besides, Garmin GPS nmea can control to better than 10ms.
>
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