说明：  利用Matlab编程的方法仿真数字通信系统。数字调制与解调系统：采用的是2FSK的调制方法；画出FSK调制后的频谱图；调制后的序列在传输的过程中产生高斯窄带白噪声；
(The use of Matlab programming method simulation of digital communication system. Digital modulation and demodulation system: using the 2FSK modulation method draw FSK modulated spectrum modulated sequence in the transmission process resulting in Gauss narrow-band white noise )