FFT实现信号的检测与同步，使用FFT做相关运算，大大缩短了了同步的复杂度和时间，这里是主代码，其他模块QUARTUS中自带有IP核，直接调用就是了-FFT signal detection and synchronization, do the relevant calculations using FFT, greatly reducing the complexity and time synchronization, here is the main code IP core comes with other modules QUARTUS directly call it