完成M=4的正交信号的数字通信系统的蒙特卡罗仿真。分析其在加性高斯白噪声下误码率与信噪比之间的关系，绘出误码率-信噪比曲线图，并和物理曲线进行比较。-The completion of M = 4 orthogonal signals in Monte Carlo simulation of digital communication systems. Analysis of the additive white Gaussian noise bit error rate and signal to noise ratio under the relationship between the mapped BER- signal to noise ratio curve, and and physical curves for comparison.