User`s manual

42
4.2.5: Digitally-Controlled AGC
Application:
The dual output Automatic Gain Control automatically attempts to boost low-level output
signals to a peak reference level (-18dB bargraph level) by gradually increasing output signal
gain over a specified Release Time interval until either the proper level or Maximum Gain
has been reached. This compensates for near party/far party conversations and for losses in
signal level which may have occurred during the enhancement process. If the output signal
levels are at or above the -18 dB reference level, the AGC will have no effect.
Clicking on the Active Button within the AGC block will cause its RED LED to toggle on and off as
shown in Figure 4-9, indicating whether the AGC is in (RED) or out (GRAY) of the process.
Figure 4-11 AGC Active Button
For fast access to the AGC, pressing <Alt-G> may also be used to toggle the AGC in or out of the
process.
NOTE: The AGC’s Active Button is overridden by the Processor Enabled button. When the LED
on the Processor Enabled button is not illuminated, the AGC stage will be bypassed.
When the AGC Config button is clicked, the window in
Figure 4-12 will appear. This window allows the user to adjust the Release Time, Maximum Gain, and
Link settings of the AGC.
Release Time specifies how quickly the AGC will react to decreases in output signal level. The shorter
the Release Time, the more quickly the AGC will react. The Release Time options are 50 milliseconds
(fastest), 100 milliseconds, 200 milliseconds, and 400 milliseconds (slowest). For most voice
applications, the 200 milliseconds setting is recommended. Release Time settings less than 200
milliseconds may result in annoying "pumping" sounds as the AGC changes gain during rapid-fire
conversations.