时变系统的频谱扩展，（信道是平坦的）仿真结果为：滤波后高斯过程的功率谱密度和由滤波器产生的相关高斯序列的时域值-Time-varying system, spread spectrum, (the channel is flat) simulation results as follows: the filtered Gaussian process power spectral density and produced by the filter related to the value of

利用自相关函数法和周期图法实现随机信号的功率谱估计-Use of the autocorrelation function and periodogram method to achieve random signal power spectrum estimation