Cleveland RAYNET Group

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Direction Finding

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RDF Principles
Getting a fix
RDF Aerials
Doppler Systems
RDF: Other bands

Some Radio Amateurs enjoy the Radio Direction Finding (RDF) aspect of the hobby.  Like many branches of Amateur Radio, some find it quite fascinating, while others see little point in expending the energy.

One reason for using RDF is to locate interference.  Another is simply for the technical experience.  Another is for the social or competitive aspect.

Clubs or groups may organise an RDF hunt at which entrants meet at a certain place and are told the frequencies and callsigns of the targets.  They take bearings on the targets, then drive to other locations of their own choice and take further bearings.  The individuals, teams or cars which find all of the targets in the shortest time wins a small prize.  Or simply wins the kudos (street cred!) of being best on that day.

Simple RDF Hunt

One of the simplest targets to be located is two radio amateurs parked in different locations, chatting to each other from their cars.  To keep it simple, it will be obvious that the cars belong to Radio Amateurs by the type of aerials on the cars and perhaps by window stickers.  Each of the two targets takes it in turn to speak.  It can be frustrating for the searchers if the target station they are after at the time is on receive, as the the other target is giving a five minute monologue.  It does, however, give the opportunity of double checking bearings on the target who is speaking at the time if it hasn't yet been found.

Hidden Transmitters

More complicated is the "hidden box" target.  The Amateur Radio licence allows unmanned operation of a transmitter for RDF hunts, within certain rules.  There could be a few hidden boxes in an area.  Each one may turn on at random times, transmit a callsign, then turn off.  They could be hidden in the woods next to a public footpath.  When you find one, you write down what is printed on the label, to prove that you found it.

Licence not needed

On RDF hunts (often called Fox Hunts), the participants don't have to hold an Amateur Radio licence as they are receiving, not transmitting.  If they have any type of radio which receives the target transmissions, they may have an equal chance of finding all of the targets, especially if they are experienced.

RDF on the 1.8 MHz band

Doppler RDF Kit

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Page updated on 09 January 2017

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