利用matlab强大的数据处理功能和图形化功能，可用来处理信号，这是吴镇扬第二版的实验三的所有的实验代码，经过运行，完全正确，请参考-Using matlab powerful data processing and graphics capabilities, can be used to process the signal, which is the second version of the experimental three-Zhen-Yang Wu for all the expe