说明：  锁相的意义是相位同步的自动控制,能够完成两个电信号相位同步的自动控制闭环系统叫做锁相环,简称PLL. 3种软件锁相的方法：指针归零法，先调频后调相法，调频调相同时进行法。
(The meaning of phase-locked is the automatic control of phase synchronization. The automatic control closed-loop system that can complete the phase synchronization of two electrical signals is called PLL The 3 method of software phase-locked: pointer to zeros, first phase modulation after frequency modulation, frequency modulation phase modulation at the same time.)