HOW FLARM WORKS
•Flarm contains a GPS receiver which locates the aircraft’s position
•Flarm also contains a transmitter/receiver which transmits the aircraft’s gps position to other flarms in range and receives the other aircraft’s gps positions
•The rest is computation – providing  displays and/or audible warnings of the proximity of other aircraft relative to you
•It is important to realise that it is all based on gps i.e. speeds, tracks etc are relative to the ground