GPS on our garden

As per our yesterday’s post – our initial GPS accuracy test was horrifying. So I discussed this with Andrew and he suggested to give it a go with something more sophisticated like gpsd — a GPS service daemon. It took just a moment to set it up on our BeagleBoneBlue as gpsd is one of commonly supported packages on Linux.

debian@beaglebone:~$ sudo apt install gpsd
[sudo] password for debian: 
Reading package lists... Done
Building dependency tree       
Reading state information... Done
gpsd is already the newest version (3.17-7).
0 upgraded, 0 newly installed, 0 to remove and 1 not upgraded.

Then we hit a bit of trouble when installation actually starts the gpsd daemon on its own and there’s been a conflict on sockets, but couple of systemd commands sorted it out.

debian@beaglebone:~$ sudo systemctl stop gpsd
debian@beaglebone:~$ sudo systemctl stop gpsd.socket

And finally we’ve been ready to launch it.

debian@beaglebone:~$ sudo gpsd -D 5 -N -n /dev/ttyO2

Now querying it with telnet on socket 2947 comes with nice “welcome” message.

debian@beaglebone:~$ telnet localhost 2947
Trying ::1...
Connected to localhost.
Escape character is '^]'.
{"class":"VERSION","release":"3.17","rev":"3.17","proto_major":3,"proto_minor":12}

Next stage is to enter “?WATCH={“enable”:true,”json”:true};” to set gpsd to the observing mode and start us feeding back.

I’ve left it running for few moments and picked random message like this:

{"class":"TPV","device":"/dev/ttyO2","mode":3,"time":"2022-01-06T11:12:21.000Z","ept":0.005,"lat":-27.205174468,"lon":153.094770215,"alt":0.258,"epx":20.312,"epy":16.881,"epv":87.471,"track":261.5038,"speed":0.170,"climb":-0.049,"eps":40.62,"epc":174.94}

There you can see information in a much nicer (human readable) form which gave us coordinates like: “lat”:-27.205174468,”lon”:153.094770215 and that thrown us to our neighbours!

Seeing how those values were fluctuating, we went out with Sebi and did one more measurement in front of our house.

That went spot on! I think it was like about a meter from us. That’s what we needed. Next step – telling this information to our jet-cart and making it move along waypoints – that’s going to be the real fun! 🙂