中文说明：
此代码是用matlab软件仿真PAM4信号的传输，自动生成传输数据，在接收端做基本的信号处理，计算出误码率。
English Description：
This code is to simulate the transmission of pam4 signal with MATLAB software, automatically generate the transmission data, do the basic signal processing at the receiving end, and calculate the bit error rate.