Now that I've finally upgraded my amateur licence I now have access to data modes, so time to play with APRS. I ultimately want to be able to track the car and addsome weather monitoring etc. A little research into using an Arduino for APRS found a number of projects, but unfortunately none of them are currently available and none of them meet my specific requirements.
I've also looked at a number of commercial offerings such as the tinytrack boards, but I'm afraid I find the price a little prohibitive given I can make my own. So this project is literally creating a small, inexpensive, arduino based TNC for APRS that can run standalone with a GPS module for operation in the car.
A little research brought me to some extremely informative sites, most notably who has done some awesome work. This then lead to the site which provides both a simple circuit diagram and coding example for the ATMega328P - and as I have a dozen or so in my component collection it's the perfect option.
Early testing on a breadboard found that the circuit needed a speaker level input to successfully decode the AFSK signal, no biggie there.
I grabbed the sample code, added in some upstream changes (in their repository) and managed to get the TNC working with a number of APRS serial clients including and Xastir for sending and receiving APRS data. So far it has decoded every message I've been able to hear and sent packets are decoded correctly, so it's working nicely.
The next stage was a more stable prototype, here using an . A minor code change and using the RX port for a GPS module has the board tracking its location and sending valid APRS messages. In this instance I'm using an I bought for another project and it's working nicely. Any serial GPS should work... - Full Post
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