Other Circuits - Icom IC-RP1620 Service Manual

3-6 OTHER CIRCUITS
3.6-1 CTCSS DECODER CIRCUIT (RX UNIT)
lC6 contains a CTCSS tone encoderldecoder, an AF
amplifier circuit, and a two-stage AF filter. The encoder
is not used in this circuit.
The AF signal from IC1 (pin 9) is applied to (212. Q12
is an active filter which functions as a low-pass filter. The
filtered signals are applied to a programmable
CTCSS tone decoder (1C6, pin 29) which decodes 67.0 Hz
-250.3 Hz tone frequencies. The tone frequency is set
by the dip switches (S3) on the LOGIC-A UNIT.
The AF signal from 1C6 (pin 29) is applied to the AF
amplifier circuit and then to the two-stage AF filter. The
filtered signal is output as a tone squelch signal from
IC6 (pin 23). The tone squelch signal is applied to IC9
(pin 17) on the LOGIC UNIT through the "T-SOL" signal
line.
iC7 functions as a seriallparallel converter and supplies
8-bit parallel data to IC6 (pin 3-6).
The following table
shows the relation between the input data and output
frequency from IC6.
CTCSS TONE DECODER FREQUENCY TABLE
-:
OFF
3-6.2 CTCSS ENCODER CIRCUIT (TX UNIT)
TONE
NUMBER
01
02
03
04
05
06
07
08
09
10
1 1
12
13
The CTCSS encoder (lC6) encodes 67.0 Hz-250.3 Hz
IC5 functions as a seriallparallel converter and supplies
tone frequencies which are set by the dip switches (Sf 1)
8-bit parallel data to IC6. The following table shows the
on the LOGIC-A UNIT. The tone frequency is output
relation between input data and the output frequency from
from IC6 (pin 1) and then applied to R32 for the deviation
lC6.
adjustment.
CTCSS TONE ENCODER FREQUENCY TABLE
TONE
FREQUENCY
(Hz)
670
719
744
770
797
825
854
885
91 5
948
97 4
1000
1035
TONE
FREQUENCY
(HZ)
1072
1109
1148
1188
1230
1273
1318
1365
141 3
27
28
29
30
3 1
32
33
34
35
-
36
37
38
-: OFF
S3
TONE
FREQUENCY
(Hz)
167 9
1738
1799
1862
1928
2035
2107
2181
2257
2336
241 8
2503
NUMBER
14
15
16
17
18
19
20
2 1
22
23
24
25
26
S3
1
-
O N -
O N O N
-
-
1462
1514
1567
1622
- -
TONE
NUMBER
01
02
03
04
05
06
07
08
09
S3
1
- -
ON
ON
-
ON
27
28
29
30
3 1
32
33
34
35
TONE
FREQUENCY
(Hz)
670
719
744
770
797
825
854
885
915
.
ON
-
ON
-
ON
ON
-
O N O N
-
ON
5
-
-
-
-
6
-
-
-
-
-
-
-
-
-
2
-
ON
ON
-
-
- O N
TONE
FREQUENCY
(Hz)
167 9
1738
1799
1862
1928
2035
2107
2181
2257
Sf1
2
O N O N -
- O N O N -
O N O N O N -
-
6
-
-
-
-
-
No
asscgned
- I - ~ o N ~ o N I - I -
TONE
FREQUENCY
(Hz)
1072
110 9
1148
1188
1230
1273
1318
1365
141 3
NUMBER
14
15
16
17
18
19
20
2 1
22
Sll
ON
-
ON
ON
- - - -
-
ON
-
- 0 N O N
3
- 0 N O N O N -
O N O N O N O N -
-
-
O N - O N - O N -
ON
ON
-
-
-
ON
-
ON
-
ON
ON
-
3
O N - - - - -
- - O N - - -
O N - O N - - -
-
- O N - O N -
ON
1 2 3 4 5 6
ON
ON
ON
ON
ON
-
-
-
1
ON
- -
S f 1
-
ON
ON
-
-
-
- O N
ON
4
- - O N - - - -
-
- O N - -
ON
4
-
ON
O N O N
O N O N
-
ON
-
-
ON
ON
-
ON
5
-
-
-
-
1
ON
-
-
O N O N
ON
-
5
ON
ON
- -
ON
ON
ON
ON
ON
-
-
-
-
ON
ON
ON
ON
- - - -
-
-
O N O N
2
-
- 0 N O N -
O N O N O N -
6
-
-
-
-
1 2 3 4 5 6
ON
- 0 N O N O N
O N O N
-
-
-
-
-
ON
ON
ON
- O N
-
2
ON
-
ON
ON
-
- O N - - O N -
- O N - O N -
-
3
O N - - - - -
O N O N - - - -
- - O N - - -
ON
-
O N - - O N - -
ON
ON
- - O N -
- O N
ON
4
- O N - - - -
-
ON
-
-
3
- 0 N O N O N -
ON
-
O N - - - O N -
-
-
- - O N - O N -
- O N
ON
-
-
-
ON
- O N
- O N
- O N
-
ON
ON
- O N
O N O N O N
ON
ON
-
-
-
-
-
-
5
-
ON
ON
- O N
ON
ON
4
ON
-
-
-
-
ON
ON
-
-
-
6
-
-
-
-
-
-
-