中文说明：kaiser窗的FIR低通滤波器，可以直接调用，滤波器阶数为75阶，通带为500HZ，阻带为600HZ，根据实际需要可直接改动通带、阻带频率。
English Description：
Kaiser window of FIR low-pass filter, can be called directly, 75-order filter order, band is 500HZ, the band is 600HZ, according to practical needs can directly change the passband and stopband frequencies.