说明：  用窗函数法设计FIR带通滤波器。指标：低端通带截止频率wlp=0.35π 低端阻带截止频率wls=0.2π。高端通带截止频率whp=0.65π 高端阻带截止频率whs=0.8π。
(Design of FIR with window function bandpass filter target: low-pass with cutoff frequency wlp = 0.35π low stopband cutoff frequency wls = 0.2π passband cutoff frequency of high-end whp = 0.65π high stopband cut-off frequency whs = 0.8π)