第6章无限脉冲响应数字滤波器设计说明.docx
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第6章无限脉冲响应数字滤波器设计说明
《数字信号处理》
作业与上机实验
(第六章)
班级:
学号:
姓名:
任课老师:
完成时间:
2014.11.18
信息与通信工程学院
2013—2014学年第2学期
第6章无限脉冲响应数字滤波器设计
1、教材p195:
13,14,15,16,17,18,19
(1)代码如下:
clear;closeall
t=1;fs=4000;
wpi=0.45*pi,wpl=0.25*pi;
wsu=0.55*pi,wsl=0.15*pi;
wpz=[0.25,0.45];
wsz=[0.15,0.55];
wp=2/t*tan(wpz/2);ws=2/t*tan(wsz/2);
rp=3;as=40;
[n,wc]=buttord(wp,ws,rp,as,'s');
[b,a]=butter(n,wc,'s');
[bz,az]=bilinear(b,a,fs);
[nd,wdc]=buttord(wpz,wsz,rp,as);
[bd,adz]=butter(nd,wdc);
hk=freqz(bd,adz)
figure
(1)
plot(angle(hk))
title('相频特性曲线')
[hp,w]=freqz(bd,adz,4000);
figure
(2)
plot(w/pi,20*log10(hp));
title('损耗函数曲线')
图示如1.1
图1.1
(2)代码如下:
fs=80000;T=1/fs;
rp=0.5;
rs=45;
wp=4000*2*pi*T;ws=20000*2*pi*T;
[N,wc]=buttord(wp,ws,rp,rs,'s');
[B,A]=butter(N,wc,'s');
hk=freqz(B,A);
figure
(1)
plot(angle(hk))
title('相频特性曲线')
[hp,w]=freqz(B,A);
figure
(2)
plot(w/pi,20*log10(hp));
title('损耗函数曲线')
图示如1.2
图1.2
(3)代码如下:
fs=80000;T=1/fs;
rp=0.5;
rs=45;
wp=4000*2*pi*T;ws=20000*2*pi*T;
[N,wc]=cheb1ord(wp,ws,rp,rs,'s');
[B,A]=cheby1(N,rp,wc,'s');
fk=0:
120000:
120000;wk=2*pi*fk
hk=freqs(B,A,wk);
figure
(1)
plot(angle(hk))
title('相频特性曲线')
[hp,w]=freqz(B,A,4000);
[Bz,Az]=impinvar(B,A);
figure
(2)
freqz(Bz,Az);图示如1.3
图1.3
(4)代码如下:
fs=2500000;
T=1/fs;
rp=1;rs=40;
wp=325000*2*pi*T;ws=225000*2*pi*T;
rp=1;rs=40;
[N,wpo]=ellipord(wp,ws,rp,rs);
[B,A]=ellip(N,rp,rs,wpo,'s')
hk=freqz(B,A)
figure
(1)
plot(angle(hk))
title('相频特性曲线')
[hp,w]=freqz(B,A);
figure
(2)
plot(w/pi,20*log10(hp));
title('损耗函数曲线')
图示如1.4
图1.4
(5)代码如下:
fs=5000000;
T=1/fs;
rp=1;rs=50;
wp=[560000*2*pi*T,780000*2*pi*T];ws=[375000*2*pi*T,1000000*2*pi*T];
[N,wpo]=ellipord(wp,ws,rp,rs,'s');
[B,A]=ellip(N,rp,rs,wpo,'s')
hk=freqz(B,A)
figure
(1)
plot(angle(hk))
title('相频特性曲线')
[hp,w]=freqz(B,A);
figure
(2)
plot(w/pi,20*log10(hp));
title('损耗函数曲线')
图示如1.5
图1.5
(6)代码如下:
fs=5000;
T=1/fs;
rp=1;rs=40;
wp=[500000*2*pi*T,2125000*2*pi*T;];ws=[1050000*2*pi*T,1400000*2*pi*T];
[N,wpo]=ellipord(wp,ws,rp,rs,'s');
[B,A]=ellip(N,rp,rs,wpo,'s');
hk=freqz(B,A)
figure
(1)
plot(angle(hk))
title('相频特性曲线')
[hp,w]=freqz(B,A);
figure
(2)
plot(w/pi,20*log10(hp));
title('损耗函数曲线')
图示如1.6
图1.6
(7)代码如下:
fs=80000;T=1/fs;
rp=0.5;
rs=45;
wp=4000*2*pi*T;ws=20000*2*pi*T;
[N,wc]=buttord(wp,ws,rp,rs,'s');
[B,A]=butter(N,wc,'s');
hk=freqz(B,A)
figure
(1)
plot(angle(hk))
title('相频特性曲线')
[Bz,Az]=impinvar(B,A);
figure
(2)
freqz(Bz,Az);
[hp,w]=freqz(Bz,Az);
figure(3)
plot(w/pi,20*log10(hp));
title('损耗函数曲线')
图示如1.7
图1.7
2、某信号
为:
,其中
设计最低阶数IIR数字滤波器,按下图所示对
进行数字滤波处理,实现:
1)IIR数字滤波器代码如下:
fs=3800;T=1/fs
fp=130;fs=600;rs=50;
wp=2*pi*fp*T;ws=2*pi*fs*T;
Bt=ws-wp;
alph=0.5842*(rs-21)^0.4+0.07886*(rs-21);
N=ceil((rs-8)/2.285/Bt);
wc=(wp+ws)/2/pi;
hn=fir1(N,wc,kaiser(N+1,alph));
M=1024;
Hk=fft(hn,M);
k=0:
M/2-1;
wk=(2*pi/M)*k;
figure
(1);
plot(wk/pi,20*log10(abs(Hk(k+1))));
title('损耗函数');gridon
figure
(2)
plot(wk/pi,angle(Hk(k+1))/pi);gridon
title('相频特性曲线');
图示如2.1
图2.1