说明：  差分检测的程序，包括一个调制程序，以及两个检测程序：一个是比较复杂但是易于理解的，一个是简便方法。对于理解调制解调的初学者来说，很有帮助
(Differential detection procedures, including a modulation process, as well as two testing procedures: one is more complicated but easy-to-understand, one is the easy way. For understanding the modulation and demodulation for beginners, very helpful)