[ntp:questions] PPS signal from Garmin GPS 18x LVC

Steve Kostecke kostecke at ntp.org
Sun Dec 29 22:13:54 UTC 2013

On 2013-12-29, Adrian P <mailing-lists at pascalau.ro> wrote:

> So "o" means PPS is used... In my case, I only have "*" in front of
> the driver IP...

In my experience the NMEA driver displays the '*' talley-code even when
PPS is in use.

> So I suppose NTP is not using the PPS signal... hmm,
> wondering why. This is my output:
> server mode 1 minpoll 4 maxpoll 4 prefer
> fudge flag1 1 flag2 0 flag3 1 refid PPS

Setting the RefID to PPS is purely cosmetic and propagates a falsehood
when the NMEA driver is not using PPS.

> root at debian:~# ntpq ... -pn


>      remote   refid st t when poll reach delay offset jitter
> * .PPS.  0 l   15   16  377  0.000 14.437 23.063
> root at debian:~#

The offset and jitter shown above suggest to me that the NMEA driver is
not using the PPS signal.

Steve Kostecke <kostecke at ntp.org>
NTP Public Services Project - http://support.ntp.org/

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