At the startup, the Arduino will ask using 3 LEDs which APRS symbol will be used (car, bike, jogger) If you want to start in test mode (no guard for GPS fix or TX rate), keep pressed the "validation" ...

If short-distance on VHF with existing Internet linked receiver networks using an Arduino compatible platform is more to your taste, then checkout the Trackuino open source APRS Tracker.

Add a description, image, and links to the arduino-aprs topic page so that developers can more easily learn about it ...