说明：  杨建国老师的通讯原理课件，第三章模拟信号的调制与解调，主要讲述信号产生与调制，射频特性，解调，MSK、GMSK、PSK、QPSK、BPSK、QAM等原理
(Yang Jianguo teacher communication principles of courseware, the third chapter of the analog signal modulation and demodulation, and focuses on the signal generation and modulation, the RF characteristics, demodulation, MSK, GMSK, PSK, QPSK, as BPSK, QAM and other principles of)