说明：  本程序实现了一个QPSK和OQPSK的例子，分别画出了两种信号的包络起伏和功率谱密度及非线性电路的输入输出函数。
(This program implements a QPSK and OQPSK example, two signals were plotted envelope fluctuations and power spectral density and nonlinear circuit input and output functions.)