在理想信道条件下、在高斯白噪声信道条件下和在先经过瑞利衰落信道再通过AWGN信道条件下的QPSK仿真（基带输入波形及其功率谱、QPSK调制信号及其功率谱、QPSK信号星座图、误码性能等）-In an ideal channel conditions, in white Gaussian noise channel conditions and earlier through Rayleigh fading channels through QPSK simulation AWGN channel