PT8000 Service Manual
6
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.
PT8000 has 39 groups of standard CTCSS frequencies for
your selection. See Table 4.1.
CTCSS signal (PWM wave) is generated by MCU, and is
passed through low pass filter consists of RC to remove the high
frequency components (above 300Hz). Then the resulting signal is
routed to VCO for modulation.
Table 4.1 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.
PT8000 has 83 standard codes (inverted and non-inverted) for
your selection. See Table 4.2.
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 routed 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 4.2 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
4.8 Semiconductor Data
MCU Description
Table 4.3 MCU (R5F212A8) Port Description
No. Port name Pin Name I/O Function
1 IGN P33 I Reserved
2 EXT-ALARM P34 I External Alarm Input
3 MODE I Connect the 4.7K resistor with VCC
4 SCL P43 O E
2
PROM Clock Line
5 SDA P44 I/O E
2
PROM Data Line
6 RST I Reset Input
7 XOUT O
8 VSS - GND
9 XIN I Oscillator（7.3MHz）
10 VCC - CPU Power Input 5V
11 SHIFT P54 O Clock Beat Shift. H: On
12 TO0 P53 O(PWM) QT/DQT Output
13 TO1 P52 O(PWM) QT/DQT Output
14 DEV1 P51 O
15 DEV2 P50 O
Max. Deviation Compensation
(frequency band is divided into four parts)
16 SCNLED P27 O Scanning Indicator H: on
17 LOWLED P26 O Low-power Indicator H: on
18 GLED P25 O Rx Green Indicator H: on
19 RLED P24 O Tx Red Indicator H: on
20 UL P23 I
PLL Unlock Detect Pin
H: Locked L: Unlocked
21 CK P22 O PLL Clock Output
22 LE P21 O PLL IC Enable Pin H: Locked
23 DT P20 O PLL Data Output
24 DTMFD0 P17 I DTMF Detect Input
25 DTMFD1 P16 I DTMF Detect Input
26 DTMFD2 P15 I DTMF Detect Input
27 DTMFD3 P14 I DTMF Detect Input
28 DTMFDV P86 I DTMF Decode Valid Input
29 RX P85 O TX/RX VCO Select H: Tx; L: Rx
30 MICDAT P84 I
Reserved: Hand MIC Digital Keypad Data
Input
31 T2IN P83 I(TRFI) Reserved: 2TONE Detect Input
32 HOOK P82 I Hook Signal Input, connect R0 with RXD
33 LEDC P81 O LED Display Control H: Valid
34 DATA P80 O LED Display Control Data
35 CLK P60 O LED Display Control Clock
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