Control System; Audio Amplifier - Kydera CDR-300UV Service Manual

5. 控制系统
U1 微处理器以 24MHZ 工作
音频放大器
6.
模拟信号由 FD6818 9 脚输出，数字信
号由 C7000 输出， 再由音频功率放大器
U4,(SA58632)放大后驱动扬声器。
接收信令(CTCSS DCS)
7.
从 FD6818 第 32 脚出来的 CTCSS,DCS 经
过微处理器 U1(C7000)出处理，微处理
器根据内部的各种处理判断接收的亚
音频是否与预先设定的值一致， 其判断
结果和噪声、 静噪的判断结果一起控制
MUTE 及 AFCO，由此控制扬声器输出。
锁相环
8.
接 收 和 发 射 的 压 控 控 制 振 荡 器 是 在
FD6818 内集成的， 锁相控制由编程控制。
基准振荡器由外部温补晶体 26M 振荡信
号。 通过晶振的可调端来校准 VCO 频率

5. Control system

U1 microprocessor works at 24MHZ.

6. Audio amplifier

The analog signal is output thru pin 9 of
FD6818, and the digital signal is output by
C7000, and then amplified by audio power
amplifier U4 (SA58632) to drive the speaker.
7. Receive signaling (CTCSS DCS)
The CTCSS and DCS coming out from the
32nd pin of FD6818 are processed by the
microprocessor U1
microprocessor judges whether the received
sub-audio is consistent with the preset value
according to various internal processes. The
judgment result together with judgment
results of noise and squelch to control MUTE
and AFCO, thereby controlling the speaker
output.
8.PLL (Phase locked loop)
The VCO of receiving and transmitting is
integrated in FD6818, and the PLL is
controlled by programming.The reference
oscillator consists of an external temperature
compensation crystal 26M oscillation signal,
and the VCO frequency is calibrated through
the adjustable end of the crystal.
(C7000). The