function [Hr,w,b,L] = hr_type2(h);
% 計(jì)算所設(shè)計(jì)的II型濾波器的振幅響應(yīng)
% Hr = 振幅響應(yīng)
% b = II型濾波器的系數(shù)
% L = Hr的階次
% h = II型濾波器的單位沖激響應(yīng)

M = length(h);
L = M/2;
b = 2*h(L:-1:1);
n = [1:1:L];
n=n-0.5;
w = [0:1:500]'*2*pi/500;
Hr = cos(w*n)*b';