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Re: [gpsd-users] Must first run gpsmon...

From: Gary E. Miller
Subject: Re: [gpsd-users] Must first run gpsmon...
Date: Wed, 10 Aug 2016 10:03:20 -0700

Yo Gary!

On Wed, 10 Aug 2016 09:29:40 -0600
Gary Hodges - NOAA Affiliate <address@hidden> wrote:

> > Then that would be slightly sub-optimal.  The ntp pool is flakey.
> > Find and pick better chimers close to you.  You should have
> > noselect on the NMEA time.  And have you measured the offset to
> > know that 0.183 is correct for you?  
> It has not been measured, only eyeballed.  That number looks like the 
> default value (or at least whatever number was in the example)
> though, so probably not even eyeballed.  "Correct" for me is likely
> pretty loose for most.  The reality is I'm good if accurate to a
> second or few with my instrument.  That said, this has been an on and
> off again little project of mine.  I have a little time this week
> which is why I decided to post.

Not a problem since you now have noselect, but otherwise it can
cause you time to thrash around a second or so.

> > Also, run "pstree -paul | fgrep gpsd" to verify which CLI options
> > are on gpsd.  
> address@hidden:~$ pstree -paul | fgrep gpsd
>    |-gpsd,1149,gpsd -N -n /dev/ttyUSB0
>    |   `-{gpsd},1154
>    |               |-grep,4858 -F gpsd
> address@hidden:~$ pstree -paul | fgrep gpsd
>    |-gpsd,1199,gpsd -N -b -n /dev/ttyUSB0
>    |   `-{gpsd},1204
>    |               |-grep,1215 -F gpsd

That looks good.  And yet cgps does not work at that point?

Do the same check for ntpd.

> > Whcih makes zero sense.  All gpsmon does, when gpsd is running, is
> > be a gpsd client.  If gpsd is started with the -n I can't see how
> > that changes how ntpd sees the gpsd server.  
> Though I haven't found it today or yesterday, I recall reading that 
> gpsmon performs an auto config of the serial port.  I've been running 
> with the assumption that all I needed to do was configure the ports 
> correctly and my quest would be over.

Only in standalone mode.  Since gpsd is already running then gpsmon
assumes gpsd has already configured the port.

Yes, setting "stty raw speed XXX < dev/ttyXX" speeds up startup.  BUt
gpsd goes further putting some GPS into a sane mode.

> address@hidden:~$ /usr/sbin/gpsd -V
> gpsd: 3.11 (revision 3.11-3)
> address@hidden:~$ /usr/sbin/ntpd --version
> ntpd 4.2.6p5

Gack....  Not good.

> I've gone back-and-forth on this.  I seem to recall in the past I've
> had time servers go away.  Using the pool seems to me a good way to
> avoid that.  Also, the reality is my time accuracy needs are pretty
> loose.

Nothing to discuss.  ntpd is designed for voting.  It needs at least
3 chmers to work as designed.

> >     # ppstest /dev/pps0  
> address@hidden:~$ sudo ppstest /dev/pps0
> trying PPS source "/dev/pps0"
> found PPS source "/dev/pps0"
> ok, found 1 source(s), now start fetching data...
> source 0 - assert 1470842538.999674124, sequence: 66675 - clear 
> 1470842538.099658684, sequence: 66674

That looks good.  After a reboot it should look that way as soon as
gpsd is started.

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

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