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Multiway Radio Mics - 2 - What is a radio mic system? - 2

The Receiver
The receiver will be tuned to the same frequency as the transmitter, in much the same way as you 'tune' your radio receiver to pick up a radio station. Most radio microphone receivers use diversity operation. As you will see from the picture below, the receiver has two aerials. Diversity operation means that it is able to select which of these aerials has the better signal, and use that. There are various means by which the receiver switches between these two aerials, but the most efficient and reliable is when the receiver effectively has two separate receivers and antennae and silently switches to the cleaner signal by means of a circuit called a 'voter'. Trantec, AKG, Micron and Sony all use this method.

Once the receiver has picked up the radio signal, it converts it into a conventional audio signal that is then output via a connector usually on the rear to a mixing desk. Depending on the model and make, the receiver will give information about the presence and strength of the radio signal (known as RF) and the level of the audio signal it is outputting (known as AF). There is usually some indication in a diversity system showing which antennae (A or B) is currently 'active'. Some receivers may also be able to monitor the battery in the transmitter, and warn the operator when it is getting low.

Summary
Hopefully the diagram below will clarify the role each item has in the system. Essentially, the radio transmission from transmitter to reciever takes the place of the cable in the standard microphone set up. If a performer is freed from the cable, they then have the ability to move anywhere in the performance space.

Thus far, what has been described is a single radio mic system. It is important to realise that for each transmitter, there needs to be a separate receiver - so an eight way radio mic system consists of eight transmitters and eight receivers, each tuned to a different radio frequency. The next part of the guide will detail the problems that may afflict radio systems, wether single or multi, before we finally examine how to set up a multiway system to try and avoid these problems.

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