Re: [gpsd-users] Large ntp.conf time1 offset needed with GPSD shared memory driver

[Gary E. Miller]

Yo Jon!

On Tue, 09 Aug 2016 15:23:04 -0500
Jon Brase <address@hidden> wrote:

> In my case I'm using GPSD for coarse time, but not for PPS, because I
> have not been able to get PPS working with GPSD on the Raspberry Pi
> (but ntp picks it up just fine).

Many problems with that.  Not the least of which is that ntpd does not 
know when PPS is valid or not.

I have three RasPi's.  A B, a 2 and a 3.  Each with a different PPS/GPS.
They all work great.

Have you looked at the RasPi HOWTO?

> Thus I'm using 28 for coarse time,
> 22 for PPS.

Which makes it real easy to get the PPS on the wrong second.  Or worse,
following PPS when the PPS is not valid.

> I'm needing to offset the coarse time by nearly half a
> second,  and am just wondering if this is normal. 

Yes, that is normal.  But that brings it's own problems.  You need to
set 'prefer' on the PPS and 'noselect' on the NMEA time.  And of course
at least 3 other chimers.


> 
> -------- Original message --------
> From: "Gary E. Miller" <address@hidden> 
> Date: 8/9/2016  14:56  (GMT-06:00) 
> To: George Sexton <address@hidden> 
> Cc: address@hidden 
> Subject: Re: [gpsd-users] Large ntp.conf time1 offset needed with
> GPSD shared memory driver 
> 
> Yo George!
> 
> On Tue, 9 Aug 2016 11:19:37 -0600
> George Sexton <address@hidden> wrote:
> 
> > server 127.127.20.0 mode 49 minpoll 4 maxpoll 4 iburst true prefer
> > server 127.127.20.0 time2 0.45 flag1 1 refid GPS  
> 
> > > #coarse time from GPSD
> > > server 127.127.28.0 minpoll 4 maxpoll 4 prefer
> > > fudge 127.127.28.0 time1 0.47 refid GPS
> > >
> > > #PPS ref-clock for top-of-second
> > > server 127.127.22.0 minpoll 4 maxpoll 4
> > > fudge 172.127.22.0 refid PPS  
> 
> Please note we now have refclock drivers 20, 22, and 28 in the mix.
> Don't do that!
> 
> If you are using gpsd and ntpd together your should ONLY be using
> refclocks 127.127.28.0 and 127.127.28.1
> 
> Driver 20 and 22 are for when gpsd is NOT begin used.
> 
> RGDS
> GARY
> ---------------------------------------------------------------------------
> Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
>       address@hidden Tel:+1 541 382 8588




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

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