说明：  利用巴特沃思、切比雪夫或椭圆滤波器设计数字滤波器,通过改变滤波器参数或特性（低通、高通、带通或带阻等）
(The use of Butterworth, Chebyshev or elliptic filter digital filter design, by changing the filter parameters or characteristics (low pass, high pass, band-pass or band stop) )