exa080401.m

设计椭圆滤波器及计算和显示功率互补IIR滤波器的频率响应；设计一个单带滤波器

%-----------------------------------------------------------------------------------
% exa080401.m    for example 8.4.1 and fig8.4.2
% 说明一个三通道滤波器组的频率响应
% h0(n),h1(n): 来自文献 [Ngu89]
%-----------------------------------------------------------------------------------

clear;

           h= [-0.0429753          -0.0927704           0.0429888  
                 0.0000139           0.0000008          -0.0000139
                 0.1489104           0.0087654          -0.1489217
                 0.2971954           0.0000226           0.2972354
                 0.3537539           0.1864025          -0.3537496
                 0.2672266          -0.0000020           0.2672007
                 0.0870758          -0.3543303          -0.0870508
                -0.0521155          -0.0000363          -0.0520909
                -0.0875973           0.3564594           0.0875786
                -0.0427096          -0.0000049          -0.0427067
                0.0474530          -0.1931082          -0.0474452
                0.0429618           0.0000230           0.0429677
                0.0                 0.0                 0.0
               -0.0232765          -0.0000026          -0.0232749
               0.0000022           0.0                 0.0000022];
            h0=h(:,1);
            h1=h(:,2);
            h2=h(:,3);

[H0,w]=freqz(h0,1,512,1);
[H1,w]=freqz(h1,1,512,1);
[H2,w]=freqz(h2,1,512,1);
H00=20*log10(abs(H0+0.0000001));
H11=20*log10(abs(H1+0.0000001));
H22=20*log10(abs(H2+0.0000001));
plot(w,H00,'b-',w,H11,'k-',w,H22,'r-');

grid on;
title('H0                                    H1                                H2');
ylabel('                dB');
hold on;