说明：  QPSK信号MATLAB仿真，分别有波形为滚降波形（载频为5Hz，符号速率为1Baud）和波形为矩形波（载频为5Hz，符号速率为1Baud）两种波形形成的仿真。以及误比特率性能曲线、星座图。
(MATLAB simulation of the QPSK signal, respectively, the waveform for the roll-off waveform (carrier frequency 5Hz, the symbol rate for 1Baud) and the waveform is a rectangular wave (carrier frequency of 5Hz, the symbol rate for 1Baud) simulation of the formation of the two waveforms. And bit error rate performance curve, the constellation diagram.)