说明：  采样简便的FAM算法来计算OFDM信号的循环谱，利用OFDM信号的循环谱的性质可以估计出OFDM信号的载频和码片时宽。FAM算法是在时域平滑算法的基础上，提出的一种基于快速傅立叶变换的时域平滑算法。通过滑动FFT变换可以实现带通滤波，同时为了提高运算效率，对输入数据进行L倍的抽样，抽取倍数L>1。根据采样定理知，对输入数据进行L倍抽取，不会对信号的频谱的计算产生影响。那么时域平均进行计算的采样数据长度为P=N/L，因此大大降低了求解循环谱的运算量
(The simple fam algorithm is used to calculate the cyclic spectrum of OFDM signal. The carrier frequency and chip time width of OFDM signal can be estimated by using the properties of cyclic spectrum of OFDM signal. Fam algorithm is a time domain smoothing algorithm based on fast Fourier transform. In order to improve the efficiency of operation, the input data can be sampled by l times, and the extraction multiple is l > 1. According to the sampling theorem, it is known that l-times extraction of input data will not affect the calculation of signal spectrum. So the average length of sampling data in time domain is p = n / L, which greatly reduces the calculation amount of solving cyclic spectrum)