用窗函数设计FIR滤波器　　掌握用窗函数设计FIR数字滤波器的原理及方法，熟悉相应的计算机高级语言编程。-The actual FIR low-pass digital filter program output using the selected window function design of the unit impulse response H (n), amplitude attenuation (20lg|H (ejw) |), phase frequency and ampl