Amateur Radio Direction Finding
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Amateur Radio Direction Finding (ARDF) should not be confused with Fox Hunting (sometimes called Bunny Hunting, Hidden Tranmitter Hunting and T-Hunting).
Amateur Radio Direction Finding has several variations according to the equipment used and geographic area covered by the hunters. In a large area, a typical event would have one transmitter and the hunters would have vehicle-mounted antennas for taking bearings and moving toward the transmitter. For an on-foot event, the area would typically be within a 10 square kilometer area only accessible on foot, and there may be several transmitters. The transmitting and receiving equipment could operate on any amateur band.
There is a well-organized form of the on-foot event promoted by the IARU with local, regional, and world championship competitions held. In this IARU style ARDF event, there are 5 transmitters placed in a course requiring 4 to 7 km travel to visit each one. The transmitters all operate on one frequency, and take turns transmitting for one minute each with a unique Morse code identifier--MOE, MOI, MOS, MOH, or MO5. The identifiers do not require understanding the code, just being able to count the number of trailing dots. There is one additional transmitter operating on a different frequency, transmitting continuously with the identifier MO, which is located at the finish line for the course. Contestants are timed from when they start until they reach the finish. The objective is to locate as many transmitters in as short a time as possible. There is a maximum time limit determined by the course designer taking into account terrain and distance, ranging from 100 to 140 minutes. Competitors exceeding the limit have no standing. There are two such events on separate days using 2 meter equipment on one day and 80 meters on the other. The 2m transmitters use MCW (tone am modulation, on/off keyed) and the 80m transmitters use on/off keying. Sometimes the 2m transmitters are FM, audio only keyed because of the availability of that type of transmitter.
Unlike our familiar "bunny hunts", in ARDF competition, the transmitters are not usually hidden. The competitor merely has to find the control point, which is within 2m of the transmitter. When you get to it, even the control point is obvious, as there is often a bag hanging on a stake. The bag contains a hole punch which is used by each competitor to punch the card they carry through the race. A referee is positioned near each transmitter to ensure there is no foul play. The winner of the event is the competitor who finds the most transmitters in the shortest time, for their class.
To participate, a competitor needs a handheld receiver with a directional antenna. A built-in attenuator, together with a signal strength meter, are important features for competitive ARDF. The amateur radio suppliers have developed some commercial products aimed at the ARDF market. Typical units are compact and lightweight, have both audible and visual signal strength indicators, attenuator and a wide dynamic range. The directional Yagi antenna can be integrated with the unit. Also available are microprocessor-controlled keyers which can convert a normal hand-held into an ARDF transmitter.
ARDF can be good exercise for the person looking for an excuse for a good walk in the woods, while "playing radio". At the Regional or World Championship level, it is a true athletic sport.
The RAC Board of Directors has recently approved the appointment of Mr. Gordon D. (Joe) Young, VE7BFK as the RAC National ARDF Coordinator replacing Perry Creighton, VA7PC who has held that appointment for several years.
Joe first became interested in ARDF when the Friendship Amateur Radio Society hosted the 3rd Friendship Radio Games in Victoria in 1993. He has attended ARDF events in Russia, Japan, USA and was responsible for the RDF event when FARS again hosted the 7th FRG in Victoria in August 2001. According to Joe, there is a momentum building in the USA with national events in 1999, 2001 and 2002 and he hopes for similar growth in Canada.
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