说明：  仿真不同占空比，等概、非等概双极性矩形随机信号的归一化功率谱密度，分析不同信号所包含的频谱分量，有无直流分量和定时分量信息
(Simulation different duty cycles, etc. There is, and so there was a non-random signal bipolar rectangular normalized power spectral density analysis of the spectral components of different signal contained, with or without DC component and timing component information)