Radio Orienteering

The foxes, who are they?

The transmitters are called foxes, probably because they are usually hard to find. Each fox transmits Morse code to identify itself. The code consists of two dahs (M), three dahs (O), and the number of dits corresponding to the fox number. For instance, the fox number two will transmit dah-dah dah-dah-dah dit-dit (MOI).

How does it work?

The 80m receiver has a directional antenna. The received signal strength varies depending on how you orient the antenna and it has two directional patterns. The first has a broad maximum and minimum. It is used most often to determine the general direction to the fox (transmitter) and in the simple cases it is enough to find it.

What happens when the fox is close?

Well, the first thing that happens is that the sharp minimums are not sharp anymore due to the specifics of the signal propagation close to the transmitter. All that is left is either a broad maximum or broad minimum.

What about the 2m receivers?

They only search for the strongest signal, because at that wavelength the antenna pattern is sharp enough to take a meaningful bearing. Watch out for reflections though, they can be as strong as the direct signal and even stronger. Most competitors take the bearings on the move and at an elevation because it averages out the reflections.