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DriveRack® User Manual
Section 4Section 4
4.5 Automatic Gain Control (AGC)
The AGC is used to keep the average level of a signal at a constant level. This is done by
selecting a desired Target output level and Window. The AGC keeps the signal within the
Window about the selected Target by slowly adjusting the gain. The maximum gain that can
be applied to the signal is selected by the Gain parameter. When the input signal falls below
the Low Threshold the AGC releases the gain and returns to unity. This prevents the AGC from
adding gain when there is no signal present and raising the system noise floor. High level
signals are reduced by a fast limiter to prevent distortion by clipping. The AGC Threshold
meters show what region of the AGC the input signal is in. The T (yellow) indicates the signal is
within the Window. A + (red) indicates the signal is going into the Limiter. A – (green) indicates
the AGC is adding maximum Gain and is at or below the Window. When the Threshold meter
is off the signal is below the Low Threshold.
AGC: On/Off
Turns the AGC module On and Off.
Target: (Targ) -20 to 20 dB
The Target parameter defines where you would like the average level of the AGC output to be.
If the average level of the signal rises above the Target the gain will be reduced. For signals
with an average level below the Target the gain will be increased.
Gain: 1 to 20dB
This adjusts the maximum amount of gain that can be added by the AGC.
Window: 1 to 10dB
This adjusts the amount of variation in the output
Low Threshold: -60 to -30dB
The Low Threshold sets a lower limit to the AGC. This prevents the AGC from adding gain to
low level signals or noise.
Attack: 0.20 to 5 Seconds
This adjusts how fast the AGC will increase gain.
Release: 30.0 to 1 dB/Second
This adjusts how fast the AGC will reduce gain.
Detailed Parameters