老师上课给的课件，主要讲解傅里叶变换及时域频域分析的方法-Teacher in the class to the courseware, the main brief Fourier transform time-domain frequency domain analysis method

振动信号的频域处理方法，包括谱分析、窗函数等-Vibration signal in the frequency domain processing methods, including spectrum analysis, the window function and so on