自动闭塞系统移频信号的锁相环解调

利用锁相环(PLL)的窄带跟踪特性，与单片机结合，实现自动闭塞系统移频信号解调，实验结果表明，该系统不仅能正确地从接收到的信号中提取出低频脉冲调制信号，还能有效地抑制由轨道电路引入的各种干扰，在各种复杂信道条件下都能获得较高的信噪比。

Demodulation of Frequency-Shifting Signals of Automatic Block System with PLL

Signal demodulation of automatic block with audio frequency shift modulated track circuits was implemented with phase-locked loop (PLL) technique and a singe chip microcomputer. Experiment showed that the demodulation system can not only reduce the low-frequency pulses from the received signals, but also effectively depress the noises induced in the track circuits and achieve high signal-noise ratio.