本仿真程序对一串二进制信息进行QPSK调制，并画出其波形图和功率谱，在某种无线AWGN信道上进行传输，然后并在接收端进行解调，最后画出其误符号性能曲线-The simulation program for a string of binary information in QPSK modulation, and draw the waveforms and power spectrum, in some wireless AWGN channel for transmission, and then demodulates at the receiving end, the final draw its symbol error performance curve