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VISION 5000 Videoconferencing System
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Advanced use
AGC Settings
========== AGC Settings ==========
Mic1-3,Audio4: Off On
Audio5(AUX): Off On
Audio6(VCR): Off On
Received Audio: Off On
Previous Menu
Select On to allow automatic adjustments (Automatic Gain Control) of audio levels. When On, the AGC
maintains the audio signal level at a fixed value by attenuating strong signals and amplifying weak signals.
Very weak signals, i.e. noise alone, will not be amplified.
Example: In most conferences, the participants will speak at different levels, and be at different distances
from the microphones. As a result, some of the participants will be harder to hear than others. The AGC
corrects this problem by automatically increasing the mic levels when quiet or distant people speak, and
by decreasing the mic levels when louder people speak.
Important
To ensure correct behaviour of the AGC, it is crucial that the levels on the input connectors are adjusted correctly
using the audio input level settings. The AGC will not compensate for severe misadjustment of input levels.
When applying a weak signal in the presence of strong background noise, the leveller might amplify the
background noise as well as the signal. Therefore, in noisy environments, it is advisable to turn the leveller
off.
Tips for improving the echo canceller performance:
Place all microphones as far as possible from the loudspeaker. Minimum loudspeaker-microphone distance
should be 2 meters.
Place all microphones as close as possible to the persons speaking. By using several microphones, the ratio
distance loudspeaker-to-mic/mic-to-speaker can be increased. Increasing this ratio improves the
echo canceller performance.
Place all microphones as far as possible from noise sources.
Reduce the volume setting. Ensure that the loudspeaker does not distort the audio.
The echo canceller tries to estimate the echo path from the speaker system to the microphones. Moving objects
change this path, therefore avoid moving objects. Be especially aware of large objects and objects placed close
to either the microphone or the speaker system as these objects will cause severe changes to the echo path.