passband ripple in db = 1
minimum stopband attenuation in db = 32 N
4 Wn
0.7000 a
1.0000 2.3741 2.7057 1.5917 0.4103 b
0.0084 -0.0335 0.0502 -0.0335 0.0084
则切比雪夫I型的最小阶次N= ；截止频率Wn= ；
传输函数H(z)=
传输函数的增益响应如下图：
Type Ichebyshev highpass Filter0-50-100gain,db-150-200-25000.10.20.30.40.50.60.70.80.91?/?
项目三
利用巴特沃斯滤波器设计一个IIR带通滤波器，其规格如下：通带截止频率的
Wp=[0.45 0.65],Ws=[0.3 0.75],，阻带截止频率，通带波纹Rp=1dB，阻带波纹Rs=40dB；
(1) 决定传输函数的分子分母系数；
(2) 利用公式9-3，确定满足要求的最小阶次N和和截止频率Wn; (3) 利用公式9-3，画出滤波器的增益响应； 代码如下：
function p6-3
wp=input('passband edge frequencies = '); ws=input('stopband edge frequencies = '); rp=input('passband ripple in db = ');
rs=input('minimum stopband attenuation in db = '); [N,Wn]=buttord(wp,ws,rp,rs); [b,a]=butter(N,Wn);
[h,omega]=freqz(b,a,256);
plot(omega/pi,20*log10(abs(h)));grid;
xlabel('\\omega/\\pi'); ylabel('gain,db');
title('IIR Butterworth bandpass Filter'); disp('N'),disp(N); disp('Wn'),disp(Wn); disp('a'),disp(a); disp('b'),disp(b);
passband edge frequencies = [0.45 0.65] stopband edge frequencies = [0.3 0.75] passband ripple in db = 1
minimum stopband attenuation in db = 40 N
7 Wn
0.4284 0.6693 a
Columns 1 through 8
1.0000 1.7451 4.9282 6.1195 9.8134 9.2245 10.4323 Columns 9 through 15
6.4091 3.4595 2.2601 0.8470 0.4167 0.0856 0.0299 b
Columns 1 through 8
0.0003 0 -0.0019 0 0.0057 0 -0.0095 Columns 9 through 15
0.0095 0 -0.0057 0 0.0019 0 -0.0003 则切比雪夫I型的最小阶次N= ；截止频率Wn= ；
传输函数H(z)=
传输函数的增益响应如下图： IIR Butterworth bandpass Filter500-50-100bd,ni-150ag-200-250-300-35000.10.20.30.40.50.60.70.80.91?/?
7.5154 0