Transmitter or Fox Hunting
Transmitter Hunting (T-hunt) or Fox Hunting is one of the more demanding activities in Amateur Radio.
It involves many skills. It can be quite athletic, very competitive and not for the faint of heart. Techniques involved
in locating a transmitter are both useful for locating sources of interference and for rescue work. Joel Moel has an excellent
article on transmitter hunting.
If you are not familiary with fox hunting, please read this article.
Those that hold a General Class ticket will be familiar with the concept. Basically by taking several bearings at different locations
and plotting them on a map from the location the bearings were taken, the point of intersection of the plotted lines
should give the location of the transmitter.
Several factors complicate locating the transmitter. Compass accuracy is generally about 5 degrees and can be off by more if there are
metal objects that interfere with magnetic field of the earth on the compass needle. Even so called digital compasses rely on magnetism.
If a large distance is to be covered, declination of true north from magnetic north may have to be factored in. Directional antennas will have fairly broad
beamwidths. Cardiod patterns using the null maybe more accurate, but signals will be affected by multipath problems in urban
environments. As one gets closer to the transmitter, the transmitter signal may overwhelm the receiver.
Transmitter signals may be horizontal or vertically polarized. Finally the transmitter and antenna may be separated by
some distance making locating the actual transmitter even more difficult.
The simplest setup is a receiver, directional antenna, compass, map and ruler. The receiver can be a scanner, shortwave
receiver or Amateur Radio transceiver. Location of the hidden transmitter can be quickened by creating teams of 4 (3 trackers
with directional antennas and receivers and 1 for plotting). The complexity of the hunt and the region to be covered
is only limited by the imagination and availability of equipment. In some areas, hunts can last for days and cover
hundreds of miles. With APRS, hunts can be monitored with GPS.
For more information, obtain a copy of Transmitter Hunting
-- Radio Direction Finding Simplified by Joseph Moell, K0OV and Thomas Curlee, WB6UZZ.
Other resources include:
Two projects that the CARS club will cover at meetings or Shack Days are:
Stay tuned for possible T/Fox Hunts. Check the Event Section for related activities.
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