说明：  产生64QAM基带通信系统发射机：基带成型滤波采用3种方式（1）采用每个符号调制一个成型滤波函数，然后将各个函数进行时域叠加的方法； （2）采用信号与低通滤波器响应函数卷积的方法；（3） matlab自带的升余弦函数
(Produce 64QAM baseband communication system transmitter: baseband shaping filter uses three ways (1) the use of a molding each symbol modulation filter function, and then each time domain overlay function (2) the use of signals and low-pass filter response function convolution method (3) matlab comes with a raised cosine function)