I’ve recently started playing with radios again and I’ve been looking mainly at packet radio. APRS is a system which uses amateur radio to transmit position reports, weather reports, and messages between users. There is an Internet backbone for APRS called APRS-IS that can be used to access a filtered feed of APRS broadcasts. I thought it would be nice if such a feed were also available via XMPP so set about building a gateway.
This was not as easy as I’d hoped it would be. All the libraries I tried to use to access APRS-IS data either were in a language I didn’t want to touch (i.e. Perl) or wouldn’t run on my system without segfaulting. Luckily, it is quite easy to talk to the APRS-IS servers as it turns out. Opening a TCP connection and sending:
user MM6MVQ-1 pass -1 vers testsoftware 1.0_05 filter r/57.1526/-2.1100/50\r\n
caused the server to begin sending me all the APRS packets broadcast within 50km of Aberdeen.
Next up was the XMPP bit. I really wanted to get a pubsub service going, but I had no idea how they worked, and after fighting with libraries again and even giving up on the server software and using jabber.ccc.de’s server instead I went for the easier option of just sending messages to a MUC for now.
Check out xmpp:firstname.lastname@example.org?join to see the messages being broadcast around me.