[ntp:questions] Pi 4 and Ultimate hat weirdness
Gary E. Miller
gem at rellim.com
Tue Jan 26 18:55:43 UTC 2021
Yo Jim!
On Mon, 25 Jan 2021 14:04:58 -0800
Jim Pennino <jimp at gonzo.specsol.net> wrote:
> > What versions of gpsd and xgps?
>
> gpsd -V
> gpsd: 3.17 (revision 3.17)
3.17 is from 2017. More than a few bugs and improvements since then.
> ntpd --version
> ntpd 4.2.8p12 at 1.3728-o (1)
We prefer NTPsec, our sister project here, but that s/b OK.
> > From your distro of from source?
>
> Distro, totally up to date.
You may be up to date with your distro, but your distro is not up to
date with gpsd.
> > Did xgps give any warnings on the command line when started from the
> > command line?
>
> xgps
> Gtk-Message: 13:45:00.966: Failed to load module "canberra-gtk-module"
> TypeError: Couldn't find foreign struct converter for 'cairo.Context'
That is easy. You are missing at least one python dependency. That
is a bug you need to report to your distro as your package manager should
have dealt with that.
> Makes me think the distro is missing a dependancy.
Yup.
If you look in the gpsd INSTALL file for you distro it might tell
you the missing giles. Here is what it says for Buster:
--------------------------------------------------------------
# apt-get install python-gi-dev python-cairo-dev
# apt-get install python-gobject-2-dev libgtk-3-dev
--------------------------------------------------------------
> > > I don't care too much about this one as AFAIK xgps is broken on
> > > Pi.
> >
> > Nope. Works for me.
>
> On buster?
Yes, but from source, not from a package.
> > > Second weird thing; I started the 20 driver in mode 0. ntpq showed
> > > lots of syntax errors on the $GPGGA message.
> >
> > Before that:
> >
> > How are you running gpsd? Root? With what command line?
>
> sudo systemctl start gpsd
> sudo systemctl start gpsd.socket
Oh. systemd(umb). I'm not allowed to help people with systemd(umbest).
But not your problem, yet.
> ps -eo euser,egroup,args | grep gps
> gpsd dialout /usr/sbin/gpsd -n -r /dev/ttyAMA0 /dev/pps0
Good, you have the -n and the pps0. Commonly missed requirements.
> ps -eo euser,egroup,args | grep ntp
> ntp ntp /usr/sbin/ntpd -p /var/run/ntpd.pid -g -u 115:124
You may want to add -N and -g.
> > Then please copy the errors here.
> >
> > > I changed the mode to 29 to deselect $GPGGA; no errors from ntpq.
> > > So maybe it was a satellite thing, but whatever it was, no more
> > > errors.
> >
> > We can only guess without seeing what you see.
>
> Not a big deal to me if ignoring $GPGGA makes the errors go away.
Another guess, without data.
> The GPS has been powered up since I stuck in the battery for the
> on board RTC 5+ days ago.
>
> How long does it typically take a receiver to have the current leap
> second.
Certainly no longer than 30 minutes after a fix.
Slow serial port speed can also cause your problem. Be sure you are
running at 9600, or faster. Faster the better.
> BTW, the GPS has an external antenna with a good view of the sky
> and cgps alway shows 11+ satellites in view and always 8+ in use.
Good. Also important that they have good SNR.
> > > Also the jitter times look high. At this moment ntpq shows:
> >
> > That is to be expected early on. Don't bother to look at the
> > jitter until the offset is stable for hours.
>
> Right now ntp has been running for about 18 hours.
It can take weeks. On a lightly loaded system. If you are running a
lot of daemones it may never improve.
Setup ntpviz. That makes monitoring the system mmuch easier.
> > > For comparison, a GlobalSat BU-353-S4 USB GPS on a PC ubuntu
> > > system shows: *SHM(0) .SHM. 0 l 3 16
> > > 377 0.000 -0.728 1.356
> >
> > Which I assume had been running for months.
>
> Yes and no; the system was rebooted 4 days before.
But the adjtime file survives a reboot. And not as good as your current
PPS.
The 0.720 you see now is a start. Now you have to check for anything that
disturbs your CPU. Heavy loads, temperature swings, CPU speed changing, etc.
RGDS
GARY
---------------------------------------------------------------------------
Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
gem at rellim.com Tel:+1 541 382 8588
Veritas liberabit vos. -- Quid est veritas?
"If you can't measure it, you can't improve it." - Lord Kelvin
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