对于非平稳信号的分析不能依靠傅里叶变换，但可以采用时频分析的方法，其中加窗傅里叶变换是最简单的一种。但是，它有很大的局限性：当基本窗函数一旦取定，窗口的时窗宽度和频窗宽度就固定了，不会随时域和频域的位移而变化。-For non-stationary signal analysis can not rely on Fourier transform, but you can use time-frequency analysis method, in which the windowed Four

实现各种典型窗函数的时域与频域特性、已知滤波器条件设计巴特沃思等滤波器、或已知系统函数可求出数字滤波器。-Achieve a variety of typical window function in time domain and frequency domain characteristics, known design Butterworth filter criteria such as filters, or known to the system function can be ob