First <a href='https://en.wikipedia.org/wiki/WSPR_(amateur_radio_software)'>WSPR</a> client for android that can not only transmit beacon signals using phone's audio output, but also receive and decode beacons using phone's audio input.

It can use device's camera flash to trigger yout radio's transmit circuitry, GPS to automaticaly update your GRID location the app transmits, and network to send received packets to wsprnet.org.

Most of permissions are not required if those features are disabled in settings (which are disabled by default).