这是个带通信号仿真调制代码，画出带通信号X(t)的幅度谱，带通信号X(t)的包络波形等。-This is a simulation of bandpass modulation code, and draw the bandpass signal X (t) the amplitude spectrum, bandpass signal X (t) the envelope waveform.

一个求包络谱的小程序，里面有两种通过峰值求包络的方法(A small program for the envelope spectrum, there are two ways to achieve the envelope through the peak)