Page 108 - DCAP311_DCAP607_WIRELESS_NETWORKS

Wireless Networks

Notes Plug-in, plug-on, slot-in, or cube-style transmitters attach to the bottom of a standard
microphone, thus converting it to wireless operation (see below).
Bodypack is a small box housing the transmitter and battery pack, but not the microphone
itself. It is attachable to belt or elsewhere and has a wire going to headset, lavalier
microphone or a guitar.
Several manufacturers including Sennheiser, AKG, Nady Systems, Lectrosonics and
Zaxcom offer a plug-in transmitter for existing wired microphones, which plugs into the
XLR output of the microphone and transmits to the manufacturer's standard receiver. This
offers many of the benefits of an integrated system, and also allows microphone types
(of which there may be no wireless equivalent) to be used without a cable. For example
a television, or film, sound production engineer may use a plug-in transmitter to enable
wireless transmission of a highly directional rifle (or "shotgun") microphone, removing
the safety hazard of a cable connection and permitting the production engineer greater
freedom to follow the action. Plug-in transmitters also allow the conversion of vintage
microphone types to cordless operation. This is useful where a vintage microphone
is needed for visual or other artistic reasons, and the absence of cables allows for rapid
scene changes and reducing trip hazards. In some cases these plug-in transmitters can also
provide 48 volt phantom power allowing the use of condenser microphone types. DC-DC
converter circuitry within the transmitter is used to multiply the battery supply, which
may be three volts or less, up to the required 48 volts.

Receivers
Wireless microphone receiver racks backstage at a large televised music awards event
There are many types of receiver. True Diversity receivers have two radio modules and
two antennas. Diversity receivers have one radio module and two antennas, although
some times the second antenna may not be obviously visible. Non-diversity receivers have
only one antenna.

Receivers are commonly housed in a half-rack configuration, so that two can be mounted
together in a rack system (that is to say the receiver is enclosed in a box 1U high and
half-width, so two receivers can be installed in 1U). For large complex multi-channel
radio microphone systems, as used in broadcast television studios and musical theatre
productions, modular receiver systems with several (commonly six or eight) true diversity
receivers slotting into a rack mounted mainframe housing are available. Several mainframes
may be used together in a rack to supply the number of receivers required. In some musical
theatre productions, systems with forty or more radio microphones are not unusual.
Receivers specifically for use with video cameras are often mounted in a bodypack
configuration, typically with a hotshoe mount to be fitted onto the hotshoe of the camcorder.
Small true diversity receivers which slot into a special housing on many professional
broadcast standard video cameras are produced by manufacturers including Sennheiser,
Lectrosonics and Sony. For less demanding or more budget conscious video applications
small non-diversity receivers are common. When used at relatively short operating
distances from the transmitter this arrangement gives adequate and reliable performance.
Questions:

1. Study and analyse the case.
2. Write down the case facts.
3. What do you infer from it?
Source: http://en.wikipedia.org/wiki/Wireless_microphone

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