Automatic Gain Control (Agc) - Polycom SoundStructure C16 Design Manual

Design Guide for the Polycom SoundStructure C16, C12, C8, and SR12

Automatic Gain Control (AGC)

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Once the conferencing ungated type is selected in the channels page as shown
in the following figure, the ungated signal path may be selected in the matrix
as shown in the following figure. This selection chooses the conferencing
ungated signal path and allows the user to enable noise cancellation on that
input signal.
Automatic gain control is used to automatically adjust the gain of audio sig-
nals so that the average signal level is close to the SoundStructure nominal
signal level of 0 dBu. The AGC processing can be used on any input signal.
AGC is typically used on microphone input signals to compensate for local
talkers that are different distances from their microphones or telephone input
signals to compensate for varying telephone levels. The AGC system has been
designed to adapt the gain only when valid speech is present.
The AGC can be turned on or off with the AGC enable button. When the AGC
is enabled, the current AGC gain (or attenuation) can be viewed from the AGC
meter and the text box next to the AGC meter.