滤波器设计 　　　产生一个连续信号，包含低频，中频，高频分量，对其进行采样，进行频谱分析，分别设计低通，带通，高通滤波器对信号进行滤波处理，观察滤波前后信号的频谱。-The filter is designed to generate a continuous signal containing the low, mid, and high frequency components, to be sampled, for spectral analysis, respectively, to