GA3219 / GA3218 / GA3217 Preliminary Data Sheet
7.6 Channel Processing
Figure 7-2 represents the I/O characteristic of independent AGC channel
processing. The I/O curve can be divided into four main regions:
•
•
•
•
low input level expansion (squelch) region
low input level linear region
compression region
high input level linear region (return to linear)
0
High Level
Gain
-10
-20
Compression
Ratio
-30
Upper
Threshold
-40
Low Level
Gain
-50
Lower
Threshold
-60
Squelch
Threshold
-70
-80
-90
-100
-120 -110 -100 -90
-80
-70
-60
-50
-40
-30
-20
INPUT LEVEL (dBV)
Figure 7-2: Independent Channel I/O Curve Flexibility
The I/O characteristic of the channel processing can be adjusted in six ways:
•
•
•
•
•
•
squelch threshold (SQUELCHTH)
low level gain (LLGAIN)
lower threshold (LTH)
high level gain (HLGAIN)
upper threshold (UTH)
compression ratio (CR)
To ensure that the I/O characteristics are continuous it is necessary to limit
adjustment to a maximum of four of the available five parameters. During
Parameter Map creation it is necessary to select four parameters as user
adjustable (or fixed) and allow one parameter to be calculated.
The squelch region within each channel implements a low level noise reduction
scheme (1:2 or 1:3 expansion ratio) for listener comfort. This scheme operates in
quiet listening environments (programmable threshold) to reduce the gain at very
low levels.
The number of compression channels is programmable in ARKonline and can be
1, 2 or 4.
Proprietary and Confidential 32718 - 2
February 2005
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GENNUM [ GENNUM CORPORATION ]
