Marine VHF Audio and Signalling Processor
CMX885
limiter threshold v p4.7
2500
2000
1500
1000
500
limit
0
0
1000
2000
3000
4000
5000
6000
7000
8000
p4.7 value (decimal)
Figure 15 Limiter Values
The limiter is set to maximum following a C-BUS Reset or a Power-up Reset. The levels of internally
generated signals may need to be adjusted by setting appropriate transmit levels to avoid unintentional
limiting.
$C8 (P4.8)
Scrambler Inversion Frequency
Bit:
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
P4.8
0
0
Scrambler Inversion Frequency = f / 0.7324
This unsigned hex number sets the inversion frequency for the Voice Scrambler and de-Scrambler
(Default is 3300Hz).
$C8 (P4.9)
Audio Filter Sequence
Bit:
15
14
13
12
11
10
9
8
7
6
5
0
4
0
3
2
1
0
P4.9
0
0
Limit
src Input AGC
Pre-emp
Scramble
300Hz
b13 sets the position of the limiter in the Audio Processing chain. The default is a soft limiter function;
setting this bit provides a hard limiter function.
b12 sets the source of the reference signal when InputAGC function is active.
0
1
=
=
Audio Input
Pre-emphasis output
b11-8 control the hardware InputAGC function and its release timer for Voice / Audio signals on Input 1 in
64ms steps:
0000
0001
0010
0011
0100
0101
- - - -
1111
InputAGC off
InputAGC on, release time = 64ms
InputAGC on, release time = 128ms
InputAGC on, release time = 196ms
InputAGC on, release time = 256ms
InputAGC on, release time = 320ms
- - - - - - - - - - - - - - - - - - - - - - - - - -
InputAGC on, release time = 960ms
© 2010 CML Microsystems Plc
56
D/885/3
CMLMICRO [ CML MICROCIRCUITS ]
