自定义一段信息序列，用QPSK调制方法对信息序列进行调制和解调-Custom period information sequence, the information sequence is modulated using the QPSK modulation method and demodulation

QPSK、SSB、BPSK、QAM等好几种调制方式，用matlab画出了调制图形，已调波形和星座图及误码率曲线-Modulation and demodulation