傅里叶变换和傅里叶变换的性质,周期信号和非周期信号的频谱分析,卷积和卷积定理,抽样信号的傅里叶变换和抽样定理,相关、能量谱和功率谱.-Fourier transform and Fourier transform nature, the cycle-cycle signal and the signal spectrum analysis, Convolution and convolution theorem, the sampling signal to the Fourier transform and sampling theorem related to the energy spectrum and the power spectrum.