PT3600 Service Manual
5
Memory (E
2
PROM, AT24C08):
The memory is stored with channel data, CTCSS/DCS data,
other function setting data, and parameter adjusting data.
CTCSS/DCS signal encoding and decoding:
The CTCSS/DCS signal (output from pin 17, PWM wave)
generated by MCU is filtered by R359, R356, C324 and C325.
Then the resulting signal is sent to RDA1846 for modulation.
The CTCSS/DCS signal from the receiver is sent to MCU for
decoding. MCU checks if the CTCSS/DCS signal in the received
signal matches the preset value of the radio, and determines
whether to open the speaker or not.
Power adjustment:
Output signal from pin 19 of the MCU passes through low
pass filter to be changed into DC signal, and is sent to the APC
unit to control the output power of the transmitter.
CTCSS
CTCSS (Continuous Tone Control Squelch System) is a
squelch control system which is modulated on carrier and is
guided by a continuous sub-audio signal. If CTCSS is set, the
communication between the transmitting and receiving radios can
be realized only when the two radios have set the same CTCSS
frequency. In doing this, disturbance from other signals can be
avoided.
PT3600 has 39 groups of standard CTCSS frequencies for
your selection (meanwhile, any CTCSS frequency between 67 and
254.1Hz is compatible). See table 3.1.
The CTCSS signal (PWM wave) is generated by MCU, and is
passed through low pass filter consists of RC to remove high
frequency components (above 300Hz). Then the resulting signal is
sent to VCO for modulation.
Table 3.1 CTCSS Frequencies
No.
Frequency
[Hz]
No.
Frequency
[Hz]
No.
Frequency
[Hz]
No.
Frequency
[Hz]
1 67.0 11 94.8 21 131.8 31 186.2
2 69.3 12 97.4 22 136.5 32 192.8
3 71.9 13 100.0 23 141.3 33 203.5
4 74.4 14 103.5 24 146.2 34 210.7
5 77.0 15 107.2 25 151.4 35 218.1
6 79.7 16 110.9 26 156.7 36 225.7
7 82.5 17 114.8 27 162.2 37 233.6
8 85.4 18 118.8 28 167.9 38 241.8
9 88.5 19 123.0 29 173.8 39 250.3
10 91.5 20 127.3 30 179.9
DCS
DCS (Digital Code Squelch), which is used to control squelch,
is a series of continuous digital codes modulated on carrier
together with voice signal. If DCS is set, the speaker can be
opened only when the radio receives signal with the same DCS to
avoid disturbance of unwanted signals.
PT3600 has 83 standard codes (normal and inverse) for your
selection. See table 3.2.
DCS signal (PWM wave) is produced by MCU. It passes
through the low pass filter consists of RC to remove the high
frequency components (above 300Hz). Then the resulting signal is
sent to VCO and TCXO for modulation, with HF components of
the DCS signal being modulated by VCO, and the LF components
of the DCS signal being modulated by TCXO.
The DCS signal coming from the receiver is sent to MCU for
decoding. MCU checks if the DCS code in the received signal
matches the preset DCS of the radio, and determines whether to
open the speaker or not.
Table 3.2 DCS Codes
023 114 174 315 445 631
025 115 205 331 464 632
026 116 223 343 465 654
031 125 226 346 466 662
032 131 243 351 503 664
043 132 244 364 506 703
047 134 245 365 516 712
051 143 251 371 532 723
054 152 261 411 546 731
065 155 263 412 565 732
071 156 265 413 606 734
072 162 271 423 612 743
073 165 306 431 624 754
074 172 311 432 627
3.8 Semiconductor Data
MCU Description
Table 3.3 Microprocessor (R8C/2A/2B) Port Description
Pin No.
I/O
Port Name
Function
1
I/O
ERDATA
EEPROM data line
2 O EPCLK
EEPROM
clock
line
3 MODE
Connect the 4.7K resistor with VCC,
programming test point
4
I
TOP KEY
Top key
5
I
UP KEY
Up key
6
RESET
Reset pin, programming test point
7 I XOUT
Oscillator
7.3m
8
VSS/AVSS
GND
9 I XIN
Oscillator
7.3m
10
I
VCC
Power supply, programming test point
