SonicFly drone tracks other drones using rotor sounds without GPS or cameras

Engineers have developed SonicFly, a drone without cameras or GPS that can track another aircraft by listening to rotor noise. In tests, its four microphones detected and tracked the sound with an average error of 1.34 metres. The technology could support search-and-rescue missions, drone swarms and deliveries, particularly in environments where GPS or communication signals are unavailable.