说明：  介绍了一种基于锁频锁相环(FPLL)的载波跟踪算法。频率跟踪模块可以适应较大动态范围的频率变化，基于软件的数控振荡器(NCO)模块可以达到极高的频率跟踪精度。由于有锁频环的频率牵引，锁相环路滤波器可以设计得很窄，具有很好的抑噪性能，满足精确跟踪载波相位的要求。因此，该基于FPLL的载波跟踪算法可以适应信号存在较大的动态范围和噪声干扰的应用环境；同时，其鉴频鉴相算法表达式简单，易于用可编程数字器件实现。
(Introduce an approach based on frequency-locking phase-locked loop (FPLL) carrier tracking algorithm. Frequency tracking module can adapt to a larger dynamic range of the frequency change, software-based numerical control oscillator (NCO) module can achieve the very high frequency tracking accuracy. Because of the frequency lock loop traction PLL filter can be designed very narrow, with very good noise suppression performance, to meet the precise requirements of carrier phase tracking. Therefore, the FPLL carrier-based tracking algorithm can be adapted to signal the existence of a larger dynamic range and noise of the application environment at the same time, the PFD algorithm expression is simple, easy to use programmable digital devices.)