Mainscreen in APRS modes
*The left button takes you to the main menu.
* Right button takes you to APRS settings (chapter 3.11).
* The OK button sends a current position beacon even if you have not changed
your location and the set interval time has not elapsed.
Mainscreen in FM modes
* Left button takes you to the main menu.
* With the right button you get to the FM settings (chapter 3.12).
* The OK button emits a 1750Hz tone for 3 seconds.
* Use the Up/Down buttons to change the volume.