This is the "Fox Delta"TNC that I recently bought from Brian, ZL3BCO. It can be used to beacon APRS packets, but I am only using it in receive mode. I have it connected to my Icom RC-5 scanner (pictured above) which is monitoring the local digi frequency.
The TNC will output all received APRS packets via it's RS-232 port. I plan to use this to feed the data into an Arduino circuit which will filter out only "APRS message" packets and display them in real-time on a 20x4 LCD that I picked up from ModernDevice. I plan to have a switch that will further filter the output so that it only displays messages addressed to my callsign.
I may even extend this further so I that can trigger a relay output by sending myself a specially crafted 'one time' APRS message that the Arduino recognises. It's plausible that I could use this to remotely allow someone access into my workshop via RF from anywhere in the world!
I have much more to learn about APRS. I find the best way to learn is to 'dive in head first'.
*Update* - I now have the TTL serial interface working and a very basic sketch accepting input from the TNC as shown in the picture below. The next step will be to filter the serial input and display only the relevant information. A project for next week perhaps ;)
