说明：  1.基带输入波形及其功率谱 2.QPSK调制信号及其功率谱 3.AWGN信道输出及其功率谱 4.通过瑞利信道之前和之后的信号星座图 5.在高斯白噪声和瑞利衰落信道条件下的误码性能以及高斯白噪声的理论曲线，所有误码性能曲线在同一坐标比例下绘制
(1. Baseband input waveform and its power spectrum 2. QPSK modulation signal and its power spectrum 3. AWGN channel output and its power spectrum 4. Signal constellation before and after Rayleigh channel 5. Bit error performance under Gaussian white noise and Rayleigh fading channel and theoretical curve of Gaussian white noise. All error performance curves are drawn in the same coordinate proportion)