ARDF — discipline of radio sport in which you must use terrain map, a compass and a radio receiver with a directional antenna ( "finder") to find a certain number of radio transmitters ( "Fox" or KP) rough terrain. The goal of the competition is to find all the “foxes” in the shortest time. The radio zones in which the radio transmitter is “heard” can be marked on the map. Or it can be heard almost throughout the competition area.