Quite funny - I know someone who uses a similar setup to send GPS Coordinates for a Quadcopter and a Plane via the audio channel of the video link (he flies the Quadcopter/Plane with video goggles) to the ground station.
There, an Arduino controls some stepper motors to point directional antennas at the copter/plane.
Project is at https://github.com/KipK/Ghettostation - video at https://www.youtube.com/watch?v=tiO4YCX7hJo - you can hear the modulation in https://www.youtube.com/watch?v=nm0okv8mTsg