说明：  本程序用matlab m文件仿真rc二阶环，对于通信领域研究人员来说，同步问题非常重要，工程常用二阶环对于初学者大有裨益。
(This procedure uses Matlab m file simulation RC two level ring, for the field of communication researchers, synchronization is very important, the project commonly used two steps ring for beginners great benefit.)