The PLL part, made of PD, Loop Filter, Voltage Control Oscillator, is the key circuit of the system to produce steady and continuous frequency scanning signal.

• PLL锁相环路部分主要由鉴相器、环路滤波器、电压控制振荡器构成，产生稳定连续的频率扫描信号，它是本系统的关键电路。