TANDBERG 5000 user manual Tips for improving the echo canceller performance

VISION 5000 Videoconferencing System 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.

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