Amateur radio direction finding (ARDF, also known as radio orienteering and radiosport) is an amateur racing sport that combines radio direction finding with the map and compass skills of orienteering.
It is a timed race in which individual competitors use a topographic map, a magnetic compass and radio direction finding apparatus to navigate through rough terrain while searching for radio transmitters. The rules of the sport and international competitions are organized by the International Amateur Radio Union. The sport has been most popular in Eastern Europe, Russia, and China, where it has been used in the physical education programs in schools since the late 1950s, but is found throughout the world.
Over 400 athletes from twenty-nine countries, representing four continents, entered the 2004 World Championship held in the Czech Republic. The rules used throughout the world, with minor variations, are maintained by the IARU Region I ARDF Working Group. Although these rules were developed specifically for international competitions, they have become the de facto standard used as the basis for all international competitions worldwide.
An ARDF competition takes place in diverse wooded terrain, such as in a public park or natural area. Each competitor receives a detailed topographic map of the competition area. The map will indicate the location of the start with a triangle and the location of the finish with two concentric circles. Somewhere within the competition area designated on the map, the meet organizer will have placed five low power radio transmitters. The locations of the transmitters are kept a secret from the competitors and are not marked on the map. Each transmitter emits a signal in Morse code by which it is easily identifiable to the competitors. The transmitters automatically transmit one after another in a repeating cycle. Depending on entry classification, a competitor will attempt to locate as many as three, four, or all five of the transmitters in the woods, and then travel to the finish line in the shortest possible time.
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