锁相两点调频的跟踪性能分析

TRACKING PERFORMANCE ANALYSIS OF TWO POINTS FM OF PLL

指出了直接和间接锁相调频的缺点，并提出了改进措施－采用锁相两点调频。提出了锁相两点调频的跟踪性能分析方法。分析表明：锁相两点或调频可以扩展调频器的下限调制频率，并且其稳态相位差不是恒定值。

The shortcotning of direct PLL FM and indirect PLL FM is pointed out. The improved method-two points FM is given. The analytical method of tracking performance of the two points FM of PLL is put forward. Analysis results show that the two points FM of PLL can spread the low cut off frequency of modulator and its stable phaso difference of the PLL FM is not fixed.