…And this is how we finally managed to use the GPS signal from our EMLID Reach M+.
Thanks a lot to Tinu Lüthi, who actually realised it:
In the instructions below the $ sign indicates the commands to be
typed into a terminal/shell. Do not type the $-sign.
=============
the gpsd part
=============
make sure that the GPS is visible and feeding the gps daemon gpsd
check whether you get GPS signals (for me this is /dev/ttyACM0, but
it might also be /dev/ttyUSB0 or something else, check with dmesg)
$ cat /dev/ttyACM0 # (interrupt with CTRL-C)
------------------
Make a backup of the GPSD service:
$ sudo cp /lib/systemd/system/gpsd.service /systemd/system/gpsd.service.orig
Then edit the service
$ nano /lib/systemd/system/gpsd.service
and add the line
ExecStart=/usr/bin/gpsd -b -n /dev/gps0
------------------
*now you have to create a link from your GPS device to the alias /dev/gps0 *
$ sudo ln -s /dev/ttyACM0 /dev/gps0
then restart the gpsd daemon
$ sudo systemctl restart gpsd
and see whether you were successful using gpsmon
$ gpsmon
============
the ntp part
============
------------------
Make a backup of the NTP config:
$ sudo cp /etc/ntp.conf /etc/ntp.conf.orig
Now edit /etc/ntp.conf:
$ nano /etc/ntp.conf
Add or change the lines below:
server 127.127.46.0
fudge 127.127.46.0 time1 0.0 time2 0.0 refid myGPS
------------------
now check whether the myGPS is found and provides a good time signal
$ ntpq -pcrv
or monitor with it every 5 seconds with
$ watch -n 5 ntpq -p