Receiver Noise
Vega wireless-microphone receivers are designed to be extremely sensitive. Although high-
performance squelch circuits are provided, it is not unusual for the receiver squelch to open
and let through audio noise when the transmitter is off. This is usually due to harmonic
outputs of commercial radio and TV stations, spurious outputs from two-way radio
transmitters, adjacent-channel leakage from TV transmitters, and, sometimes, RF noise from
digital equipment such as audio and video effects generators, computers, and other industrial
equipment near the antennas.
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
Vega wireless-microphone systems have been specifically designed to reject interference.
However, interfering signals might fall directly on the receiver frequency, making it
impossible to avoid problems completely. This can be a particular problem if the receiver
audio is left open when the transmitter is turned off.
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.
Some digital audio and video signal processing equipment and effects generators also can
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Vega U2020 UHF
