莫尔斯码的幅度调制与解调:信号x(t)含有一段简单的消息，由文件ctftmod.mat定义，由x(t)解出所需信息-The amplitude modulation and demodulation of the Morse code:the signal x (t) contains a simple piece of information, as defined by the file ctftmod.mat information required by the solution x (t)