Kenwood TK-3360 Service Manual page 17

■ High-speed data (2-tone, DTMF)
High-speed data (HSD) is output from pin 1 (TXTONE) of
the MCU.
The signal passes through a low-pass CR fi lter. TX devia-
tion making an adjustment by MCU is applied to the base-
band IC (IC812). The signal is mixed with the audio signal
and goes to the VCO and TCXO.
■ MSK
MSK signal is output from pin 24 of IC812. The signal
passes through the D/A converter and is routed to the VCO.
When encoding MSK, the microphone input signal is muted.
6-2. Dceode
■ QT/DQT
The output signal from IF IC (IC401) enters the MCU
(IC809) through IC812. IC809 determines whether the QT or
DQT matches the preset value, and controls the AFSW and
the speaker output sounds according to the squelch results.
■ 2-tone
The demodulated signal from the FM IC (IC401) is ampli-
fied by the baseband IC and passes through a high-pass
fi lter to remove frequencies of 3kHz or more. The MCU digi-
tizes this signal and decodes the signal after receiving the
signal at pin 5 (HSDI).
■ DTMF/MSK
The DTMF and MSK input signal from the IF IC (IC401)
goes to IC812. The decoded information is then processed
by the MCU.
7. Power Supply
There are fi ve 5V and three 3.3V power supplies for the
MCU:
50M and 33M is always output while the power is on.
33MS is always output, but turns off when the power is
turned off to prevent malfunction of the MCU.
50C is a common 5V and is output when SAVE is not set
to ON.
50R is 5V for reception and output during reception.
50T is 5V for transmission and output during transmis-
sion.
50V is 5V for the SP/MIC connector.
33B is 3.3V for the baseband IC (IC812).
CIRCUIT DESCRIPTION /
电路说明
■高速数据 (2- 音 ,DTMF)
高速数据 (HSD) 从微处理器的针脚 1(TXTONE) 输出。
信号通过低通 C R 滤波器。由微处理器进行调整的 T X 频偏
被施加到基带 IC(IC812)。此信号与音频信号混合，然后送入
VCO 和 TCXO。
■ MSK
MSK 信号从 IC812 的针脚 24 输出。此信号通过数模转换器，
然后发送给 VCO。编码 MSK 时，麦克风输入信号被静音。
6-2. 解码
■ QT/DQT
I F I C ( I C401) 的 输 出 信 号 通 过 I C812 送 入 微 处 理 器
( I C809)。I C809 确 认 Q T 或 D Q T 是 否 与 预 设 值 匹 配， 控 制
AFSW，然后扬声器根据静噪结果输出声音。
■ 2- 音
F M I C ( I C401) 的解调信号由基带 I C 放大，并通过高通滤
波器以消除 3kHz 或以上的频率。在针脚 5(HSDI) 接收信号之
后，微处理器将该信号数字化并对信号解码。
■ DTMF/MSK
IF IC(IC401) 的 DTMF 和 MSK 输入信号送入 IC812。然后由
微处理器处理解码信息。
7. 电源
微处理器有 5 个 5V 电源和 3 个 3.3V 电源。
电源打开时，50M 和 33M 总是输出。5M 总是输出，但电源
关闭时 33MS 关闭，以防止微处理器出现故障。
50C 是普通的 5V 电源，它在 SAVE 没有设为 ON 时输出。
50R 是接收用 5V 电源，它在接收期间输出。
50T 是为发射用的 5V 电源，它在发射期间保持输出。
50V 是 SP/MIC 用 5V 电源。
33B 是基带 IC(IC812) 用 3.3V 电源。
TK-3360
17