other ten, so four frequencies are used in total. It is possible to combine the spectator control with the beacon control. Competitors start at 2 min intervals and have to visit between 3 and 5 controls out of the first set (according to their age class) before visiting the compulsory spectator control. They then visit the requisite controls from the second set before punching the compulsory beacon control, prior to finishing. Fox Oring is a variation of the sport that requires more orienteering skills. In a Fox Oring course, the radio transmitters put out very little power, and can be received over only very short distances, often no more than 100 meters. The location of each transmitter will be indicated on the map with a circle. The transmitter does not need to be exactly at the circle's center or even located inside the circle, but one should be able to receive its transmissions everywhere within the area indicated by the circle. A competitor must use orienteering skills to navigate to the area of the circle on the map and only then use radio direction finding skills to locate the very low power transmitter. Another variation of the sport, Radio Orienteering in a Compact Area, requires less athletic skill and more technical radio direction finding skills. In a ROCA course, the transmitters put out very little power, typically 10 to 200 mW, and can be received over only very short distances. The transmitters are physically small, and marked with a control card that is no larger than a typical postcard with a unique number identification. Because of the low power and short distances involved, most ROCA competitors walk the entire course, and focus their attention on the radio direction finding tasks rather than navigation. Another form of recreational radio direction finding activity in North America that includes the use of automobiles for transportation is most often referred to as foxhunting or transmitter hunting, but is sometimes confused with the organized international sport of amateur radio direction finding. See also Friendship Radiosport Games Radio direction finder References Cited references General references Harker, Kenneth WM5R (2005). "What You Need to Get Started in ARDF". Retrieved Nov. 28, 2005. Moell, Joe KØOV and Curlee, Thomas N. WB6UZZ (1987). ''Transmitter Hunting: Radio Direction Finding Simplified". TAB Books, McGraw-Hill. . Special Postal Cancellation on ARDF 18 May 2009 Bangalore India by VU2JHM Lion Ajoy, International Director,