用c语言实现fft和iir滤波器的设计。可以和matlab中的函数fft,filter等效。-used language fft and IIR filter design. Matlab can and the function fft, filter equivalent.

psd cpsd C语言实现方法，随机信号产生，随机信道参数，使用fftw函数库辅助计算fft-psd cpsd C language implementation, the random signal is generated, random channel parameters, use fftw library helper function computing fft

FFT的头文件，可直接调用函数进行FFT运算，采样点数可以自行修改(The header file of the FFT can be directly invoked by the function for the FFT operation, and the number of sampling points can be modified by itself)