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Re: [gpsd-users] Garmin 18X-5Hz

From: Gary E. Miller
Subject: Re: [gpsd-users] Garmin 18X-5Hz
Date: Mon, 15 Aug 2016 11:12:57 -0700

Yo Alexander!

On Mon, 15 Aug 2016 08:10:09 -0700
Alexander Carver <address@hidden> wrote:

> > I use 28.  gpsd does all the work and hands the time corrections to
> > ntpd to deal with.  That is how the gpsd time server howto does it,
> > as well as the in progress NTPsec RasPi howto.  
> I find this interesting because on four different hardware platforms
> using different OSes and different GPS receivers I can not get gpsd's
> PPS SHM output to behave.

Many many people do this just fine.  I have 8 boxes doing this now.  
Eric has a simliar number.  We have a lot of beta testers doing
similar.  There are zero open bugs on anything like this.  I can provide
many graphs showing it works fine, and has for many years.

>  It consistently feeds awful time to ntpd
> and, in the end, I use the ntpd PPS driver (22) to keep things under
> control.

Well, since that driver is deprecated, maybe we need to find out how to
fix your installations?

> I feed the coarse clock into ntpd via gpsd (so the GPS
> receiver data can be monitored or shared with other applications) but
> PPS via SHM is terrible (offset in milliseconds and jitter also in
> milliseconds, using Driver 22, offset and jitter are single digit
> microseconds.)

Totally bizare.  Single digit microSeconds are the universal result.
Are you sure your kernel PPS driver is installed correctly and seen by
gpsd when it is built?

> Given that, I would really like to know how you have your whole system
> configured because following any available recipe fails.  I see the
> config in your link below and I've used that without success.

My setup is documented in the gpsd time howto:


And in the NTPsec Pi howto:

If those do not work for anyone we would jump on it right away to get
a fix.

> In any event, is NTPsec a replacement or is this a fork of ntpd?


Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
        address@hidden  Tel:+1 541 382 8588

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