Components of Wireless Systems

Microphone or Transducer

Any microphone or transducer can be converted to wireless operation with the addition of a transmitter and receiver wireless link. Microphones as well as piezoelectric pickups commonly used in guitars are the heart of the system long before a transmitter and receiver come into play. It is often said that "garbage in is garbage out," and this phrase couldn't be more true with a wireless system. Any system is only as good as its weakest link, and generally the least expensive way to improve the overall quality of the system is to improve the microphone or transducer. A suitable microphone should have excellent dynamic range and headroom, and good linearity over the audio range or the end result will be disappointing. When a wireless system is used, it should include a high quality microphone that is matched to the application.

Transmitters

The transmitter provides the link between the microphone and the receiver. The transmitter takes the audio signal from the microphone, converts this energy into a frequency modulated carrier (FM) then radiates the modulated RF carrier where it is picked-up by the receiver.

Receivers

The receiver reverses the process by receiving the RF signal and converting the carrier signal into a usable audio signal. This is accomplished by a process called heterodyning where the carrier is filtered, then converted to an intermediate frequency (IF) which is a fraction of the original carrier frequency. After filtering in the IF section, the signal is sent to an FM demodulator which separates the superimposed audio signal from the RF carrier, and converts it into a usable microphone signal again. The usable audio signal is then fed to the output which is connected to the amplifier or mixer. The receiver acts like a standard microphone when used in conjunction with a transmitter and microphone.

There are numerous variations of both transmitters and receivers depending on the particular application. We will explore both receivers and transmitters in depth later in this paper, but first we need to begin by examining the different frequency groups applicable to wireless microphones.

CONTINUE: WIRELESS MICROPHONES

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