说明：  1.对信源进行AM，DSB,SSB调制 2.信道中各自加入进过带通滤波器后的窄带高斯白噪声,解调每个信号，并画出滤除前后，双边带信号和单边带信号的频谱。
(1. Letter source AM, DSB, SSB modulation 2. Add to each channel through the band pass filter into a narrow band Gaussian white noise, each signal demodulated, filtered and drawn before and after the double-sideband signal spectrum and single sideband signal.)