在对PSK系统进行仿真，要求：对M=4的PSK系统，分别取信噪比为odB、10dB和20dB，在星座图上观察接收端接收到的信号向量。 -in the PSK system simulation, requirements : M = 4 for the PSK system, the signal-to-noise were taken odB. 10dB and 20dB, in the constellation observation receiving termination rec