True diversity radio microphone receiver
We recommend the use of true diversity radio microphone systems. A radio microphone system consists of a radio microphone and radio microphone receiver. A true diversity radio microphone receiver has two aerials and two aerial circuits. True diversity means that the radio signal is picked up on two aerials, each connected to a separate set of receiving electronic circuits - the output of the receiver is provided from the set aerial circuits which is giving the best quality signal at any moment in time, or is a combination of the two. True diversity receivers are much less prone to drop-outs (intermittent loss of sound) than non-diversity types. The aerials are generally best set at between + and - 30 to 45 degrees from the vertical, i.e. spreading apart at between 60 and 90 degrees from each other.

Non diversity radio microphone receiver
Non diversity means that the radio signal (usually picked up on a single aerial) is processed by a single aerial circuit. These types are prone to "drop-outs" temporary interruptions of the audio signal caused by temporary reductions in the received radio signal strength (due to reflections of the signal and physical obstacles in its path). The receiver aerial is generally best set vertically. Some single-channel receivers are equipped with two aerials, even though they have only one aerial circuit these may perform a little better than non diversity receivers with only one aerial, but fall far short of the performance obtained from true diversity receivers.

Channel selection
When several radio microphone systems need to be operated simultaneously in the same area, each system must be set to a different frequency. If two or more systems are set to the same frequency inter-modulation interference occurs. This causes each system to lock the other one out resulting in no sound output.

Channel selector
VHF Radio microphone systems use a frequency-modulated (FM) radio signal at VHF frequencies. Strictly, each system does not operate at a single frequency, but rather uses a narrow range of frequencies called a 'channel' (the TOA WM3800 has 6 selectable channels).

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