第6章-无限脉冲响应数字滤波器设计

1、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;close all 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=b

2、uttord(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=4

3、5;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(a ngle(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,r

4、s,s);B,A=cheby1(N,rp,wc,s); fk=0:120000:120000;wk=2*pi*fk hk=freqs(B,A,wk);figure(1)plot(a ngle(hk)title(相频特性曲线) hp,w=freqz(B, A,4000); Bz, Az=imp in var(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,

5、rs);B,A=ellip(N,rp,rs,wpo,s)hk=freqz(B,A)figure(1)plot(a ngle(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,r

6、s,wpo,s)hk=freqz(B,A)figure(1)plot(a ngle(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)fig

7、ure(1)plot(a ngle(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(a ngle(hk) title(相频特性曲线) Bz, Az=imp in var(B,A);fi

8、gure(2)freqz(B z, Az); hp,w=freqz(B z,Az);figure)plot(w/pi,20*log10(hp);title(损耗函数曲线)图示如1.7才日妬犷M灶00.10.20.30.40.50.G0.70.80.91Normalised Frequency (乂天 rad/samplei)o o o5 5-mp) GpnrEEW-1000-100-200-30000 10 20 30 40 50 60 70 80 91Normalised Frequency (x rad/sample)图1.72、某信号 x(t)为：x(t) 0.5cos(2 fit) 0

9、.7cos(2 f?t 0.1 ) 0.4cos(2 fst),其中fi 100Hz, f2 130Hz, fi 600Hz.设计最低阶数IIR数字滤波器，按下图所示对x(t)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-21F0.4+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(h n, M);k=0:M/2-1;wk