本次仿真研究多幅度电平信号误码率与信噪比之间的关系，系统框图如上。假设考虑8幅度电平，则根据流程首先需要用一个随机数发生器产生在(0,1)间的均匀随机数，然后将(0,1)区间均匀划分为(0,0.125)、(0.125,0.25)、(0.25,0.375)、(0.375,0.5)、(0.5,0.625)、(0.625,0.75)、(0.75,0.875)、(0.875,1)这些子区间，并分别对应于一个3bit符号000、001、010、011、100、101、110、111，接着分别映射到-7d、-5d、-3d、-d、d、3d、5d、7d幅度电平上。之后高斯随机数与幅度电平叠加(高斯噪声的方差由输入信噪比控制)，生成随机幅度r。通过与判定门限的比较判定r的符号值，然后与输入符号比较，如果不等则认为此符号传送错误。本实验假定进行10000次信号发送，计算发送错误的比例作为仿真误码率。

　　另外计算对应不同信噪比情况下理论误码率的值，与上述实验进行对比验证。

-The simulation of multi-amplitude level signal bit error rate and the relationship between SNR, the system block diagram above. Assumption consider the magnitude of level 8, then according to the process you first need to use a random number generator in (0,1) uniform random number, then (0,1) interval is divided into uniform (0,0.125), (0.125 , 0.25), (0.25,0.375), (0.375,0.5), (0.5,0.625), (0.625,0.75), (0.75,0.875), (0.875,1) These sub-intervals, and corresponding to a symbol 3bit 000,001,010,011,100,101,110,111, and then are mapped to-7d,-5d,-3d,-d, d, 3d, 5d, 7d on the amplitude level. After the Gaussian random number with the amplitude level overlay (Gaussian noise of variance controlled by the input signal to noise ratio) to generate a random rate r. By comparison with the determined threshold value to determine the sign of r, and then compared with the input symbol, if the range is that this symbol transmission error. This study assumes that the signal sent 10000, send an error