When the wireless transmitter is “on,” this noise is suppressed and rarely causes
any difficulties. However, if the audio channel is left “open” with the transmitter
“off,” loud blasts of noise may occur. Therefore, it is advisable to “fade” the
receiver audio when the transmitter is not in use. Changing the placement of the
antennas and, in some extreme cases, changing the operating frequency may be
necessary to minimize these problems.
The receiver rear panel “SQUELCH” control may be adjusted to eliminate false
squelch openings when the transmitter is off. This will be effective only in mild
cases of interference. Adjustment of this control will directly affect the system's
operating range, so considerable caution should be used.
Antennas/Cables
If there is a coverage problem, try moving the receiving antenna, particularly if
there are nearby metallic materials. Antenna placement and mounting is vitally
important. Shielding the antenna with metallic objects reduces the signal level
available, and may result in creating locations within the coverage area where the
receiving antenna is almost entirely ineffective (pattern “nulls”).
Acoustic Feedback
Bodypack transmitters usually use lavalier electret microphones. Almost all such
microphones are omnidirectional (equal sensitivity in all directions) and usually
pick up much more ambient noise than handheld microphones.
In many sound systems, on-stage monitors are used. Often, the directional
characteristics of handheld microphones provide the only protection from acoustic
feedback. Omnidirectional lavalier microphones do not provide the same degree
of protection, and acoustic feedback may occur when the wireless is used.
However, this is an acoustic problem and is not directly related to the use of
wireless transmission. There are several solutions to this problem: substituting a
directional lavalier microphone (a few models are available), reducing the monitor
level, relocating the monitor speakers, or careful adjustment of equalizers.
Interference
Problems with RF noise sources (fluorescent lights, digital effects generators, and
industrial equipment, etc.) are quite rare. However, defective fluorescent lighting
fixtures can generate astonishing amounts of RF energy. Usually, repairing the
fixture will cure the problem. Normally functioning fixtures almost never cause
trouble. Some digital audio and video signal processing equipment and effects
generators also can generate substantial amounts of broadband noise. When this
situation exists, nothing can be done to the wireless equipment to correct the
problem that will not seriously degrade performance. The receive antennas must
be positioned away from these sources of RF noise to minimize the effect of this
interference. Fortunately, this type of problem is surprisingly rare.
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Model R-662A PRO PLUS Dynex III