Marine VHF Audio and Signalling Processor
CMX885
Attenuation
Attenuation
b11-0 Value (hex)
b11-0 Value (hex)
(dB)
0
(dB)
1.6
1.8
2.0
2.2
2.4
2.6
2.8
3.0
FFF
F90
F40
EE0
EA0
E50
DE0
DA0
D50
CF0
CB0
C60
C20
BF0
BA0
B60
0.2
0.4
0.6
0.8
1.0
1.2
1.4
Table 5 Voice Level Attenuation
01102:
The Output 1 level may be attenuated by the value written to b11-0. The default value of $FFF is
equivalent to x1. This register operates in parallel with P4.2, but allows the level to be adjusted “on-the-fly”
without needing to drop back into Idle mode.
10002:
The Output 2 level may be attenuated by the value written to b11-0. The default value of $FFF is
equivalent to x1. This register operates in parallel with P4.4, but allows the level to be adjusted “on-the-fly”
without needing to drop back into Idle mode.
10102:
This sets the value of the Tx Voice Level Multiplier at the output of the Tx limiter stage. This can be useful
in situations where it has been necessary to use a small limiting threshold and still maintain an acceptable
level at the MOD outputs. The default state is x1.
b2
b1
b0
Tx Voice Level Multiplier
0
0
0
0
1
1
0
0
1
1
0
0
0
1
0
1
0
1
x1
x2
x4
x8
x16
x32
11002:
MOD1 and MOD2 fine attenuator controls. In conjunction with the coarse attenuator register ($B0), these
bits allow fine control over the MOD1 and MOD2 levels in 0.2dB steps. Additional gain and offset control
of Output 1 and Output 2 is also provided in register $CD:0111 and $CD:1000 settings as well as
Program Blocks P4.2 – 4.5. These bits may be changed whilst the device is in Tx or Rx modes.
b3
b2
b1
b0
MOD1 Fine Output Attenuation
b7
0
0
0
0
0
0
0
0
1
1
b6
0
0
0
0
1
1
1
1
0
0
b5
0
0
1
1
0
0
1
1
0
0
b4
0
1
0
1
0
1
0
1
0
1
MOD2 Fine Output Attenuation
0dB
0.2dB
0.4dB
0.6dB
0.8dB
1.0dB
1.2dB
1.4dB
1.6dB
1.8dB
© 2010 CML Microsystems Plc
49
D/885/3
CMLMICRO [ CML MICROCIRCUITS ]
