Family Radio CTCSS 'Type 2' Encoder and Decoder
CMX808A
When this bit is “1” the audio band-pass filter is enabled and the output of the
filter is switched to RX AUDIO OUT. The output is then controlled by BPF UN-
MUTE. See Bit 5 below.
RX BPF ENABLE
(Bit 6)
When this bit is “0” the audio band-pass filter is disabled (powersaved) and the
output of the filter is disconnected from RX AUDIO OUT, which is then in a high
impedance state.
When this bit is “1” and TX BPF ENABLE is “1” the audio band-pass filter output
is switched to the TX AUDIO OUT pin. When this bit is “0” the output of the filter
is disconnected from TX AUDIO OUT, which is then in a high impedance state.
This control, along with TX BPF ENABLE, allows the filter to power up and settle
internally before switching the output on, when coming out of powersave.
BPF UN-MUTE
(Bit 5)
When this bit is “1” and RX BPF ENABLE is “1” the audio band-pass filter output
is switched to the RX AUDIO OUT pin. When this bit is “0” the output of the
filter is disconnected from RX AUDIO OUT, which is then in a high impedance
state. This control, along with RX BPF ENABLE, allows the filter to power up
and settle internally before switching the output on, to avoid clicks when coming
out of powersave.
These five bits are used to set the attenuation of the audio volume control
according to the table below:
AUDIO ATTENUATION
(Bits 4, 3, 2, 1, and 0)
Bits
2
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
Audio
Attenuation
Off (VBIAS
4
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
3
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
)
48.0dB
46.4dB
44.8dB
43.2dB
41.6dB
40.0dB
38.4dB
36.8dB
35.2dB
33.6dB
32.0dB
30.4dB
28.8dB
27.2dB
25.6dB
24.0dB
22.4dB
20.8dB
19.2dB
17.6dB
16.0dB
14.4dB
12.8dB
11.2dB
9.6dB
8.0dB
6.4dB
4.8dB
3.2dB
1.6dB
0dB
2003 CML Microsystems Plc
9
D/808A/6
CMLMICRO [ CML MICROCIRCUITS ]
