IIR数字滤波器设计及软件实现1.docx

1、IIR数字滤波器设计及软件实现1实验四function st=mstgN=800;Fs=10000;T=1/Fs;Tp=N*T;t=0:T:(N-1)*T;k=0:N-1;f=k/Tp;fc1=Fs/10;fm1=fc1/10;fc2=Fs/20;fm2=fc2/10;fc3=Fs/40;fm3=fc3/10;xt1=cos(2*pi*fm1*t).*cos(2*pi*fc1*t);xt2=cos(2*pi*fm2*t).*cos(2*pi*fc2*t);xt3=cos(2*pi*fm3*t).*cos(2*pi*fc3*t);st=xt1+xt2+xt3;fxt=fft(st,N);subp

2、lot(2,1,1);plot(t,st);grid;xlabel(t(s);ylabel(s(t);axis(0 Tp/4 min(st) max(st);title(a) s(t)的波形);subplot(2,1,2);stem(f,abs(fxt)/max(abs(fxt),.);grid;title(b) s(t)的频谱);axis(0 Fs/5 0 1.2);xlabel(f(Hz);ylabel(幅度);function st=mstg1N=800;Fs=10000;T=1/Fs;Tp=N*T;t=0:T:(N-1)*T;k=0:N-1;f=k/Tp;fc1=Fs/10;fo1=f

3、c1/10;fc2=Fs/20;fo2=fc2/10;fc3=Fs/40;fo3=fc3/10;xt1=(2+cos(2*pi*fo1*t).*cos(2*pi*fc1*t);xt2=(2+cos(2*pi*fo2*t).*cos(2*pi*fc2*t);xt3=(2+cos(2*pi*fo3*t).*cos(2*pi*fc3*t);st=xt1+xt2+xt3;fxt=fft(st,N);subplot(2,1,1);plot(t,st);grid;xlabel(t(s);ylabel(s(t);axis(0 Tp/4 min(st) max(st);title(a) s(t)的波形);su

4、bplot(2,1,2);stem(f,abs(fxt)/max(abs(fxt),.);grid;title(b) s(t)的频谱);axis(0 Fs/5 0 1.2);xlabel(f(Hz);ylabel(幅度);Fa=10000;T=1/Fs;st=mstg;fp=280;fs=450;wp=2*fp/Fs;ws=2*fs/Fs;Rp=0.1;As=60;N,wpo=ellipord(wp,ws,Rp,As);B,A=ellip(N,Rp,As,wpo);y1t=filter(B,A,st);figure(2)subplot(2,1,1);H,W=freqz(B,A,1000);k=

5、abs(H);plot(W/pi,20*log10(k/max(k);grid on;xlabel(w/pi);ylabel(幅度(dB);axis(0 1 -80 5);title(损耗函数曲线);subplot(2,1,2);n=0:length(y1t)-1;t=n*T;plot(t,y1t);xlabel(t(s);ylabel(y1(t);title(低通滤波器分离出的信号y1(t);axis(0 0.08 -1.5 1.5);fpl=440;fpu=560;fsl=275;fsu=900;wp=2*fpl/Fs,2*fpu/Fs;ws=2*fsl/Fs,2*fsu/Fs;Rp=0.

6、1;As=60;N,wpo=ellipord(wp,ws,Rp,As);B,A=ellip(N,Rp,As,wpo);y2t=filter(B,A,st);figure(3)subplot(2,1,1);H,W=freqz(B,A,1000);k=abs(H);plot(W/pi,20*log10(k/max(k);grid on;xlabel(w/pi);ylabel(幅度(dB);axis(0 1 -80 5);title(损耗函数曲线);subplot(2,1,2);n=0:length(y2t)-1;t=n*T;plot(t,y2t);xlabel(t(s);ylabel(y2(t);

7、title(带通滤波器分离出的信号y2(t);axis(0 0.08 -1.5 1.5);fp=890;fs=600;wp=2*fp/Fs;ws=2*fs/Fs;Rp=0.1;As=60;N,wpo=ellipord(wp,ws,Rp,As);B,A=ellip(N,Rp,As,wpo,high);y3t=filter(B,A,st);figure(4)subplot(2,1,1);H,W=freqz(B,A,1000);k=abs(H);plot(W/pi,20*log10(k/max(k);grid on;xlabel(w/pi);ylabel(幅度(dB);axis(0 1 -80 5)

8、;title(损耗函数曲线);subplot(2,1,2);n=0:length(y3t)-1;t=n*T;plot(t,y3t);xlabel(t(s);ylabel(y3(t);title(高通滤波器分离出的信号y3(t);axis(0 0.08 -1.5 1.5);Fs=10000;T=1/Fs;st=mstg1;fp=280;fs=450;wp=2*fp/Fs;ws=2*fs/Fs;Rp=0.1;As=60;N,wpo=ellipord(wp,ws,Rp,As);B,A=ellip(N,Rp,As,wpo);y1t=filter(B,A,st);figure(2)subplot(2,1

9、,1);H,W=freqz(B,A,1000);k=abs(H);plot(W/pi,20*log10(k/max(k);grid on;xlabel(w/pi);ylabel(幅度(dB);axis(0 1 -80 5);title(损耗函数曲线);subplot(2,1,2);n=0:length(y1t)-1;t=n*T;plot(t,y1t);xlabel(t(s);ylabel(y1(t);title(低通滤波器分离出的信号y1(t);axis(0 0.08 -3 3);fpl=440;fpu=560;fsl=275;fsu=900;wp=2*fpl/Fs,2*fpu/Fs;ws=2

10、*fsl/Fs,2*fsu/Fs;Rp=0.1;As=60;N,wpo=ellipord(wp,ws,Rp,As);B,A=ellip(N,Rp,As,wpo);y2t=filter(B,A,st);figure(3)subplot(2,1,1);H,W=freqz(B,A,1000);k=abs(H);plot(W/pi,20*log10(k/max(k);grid on;xlabel(w/pi);ylabel(幅度(dB);axis(0 1 -80 5);title(损耗函数曲线);subplot(2,1,2);n=0:length(y2t)-1;t=n*T;plot(t,y2t);xla

11、bel(t(s);ylabel(y2(t);title(带通滤波器分离出的信号y2(t);axis(0 0.08 -3 3);fp=890;fs=600;wp=2*fp/Fs;ws=2*fs/Fs;Rp=0.1;As=60;N,wpo=ellipord(wp,ws,Rp,As);B,A=ellip(N,Rp,As,wpo,high);y3t=filter(B,A,st);figure(4)subplot(2,1,1);H,W=freqz(B,A,1000);k=abs(H);plot(W/pi,20*log10(k/max(k);grid on;xlabel(w/pi);ylabel(幅度(d

12、B);axis(0 1 -80 5);title(损耗函数曲线);subplot(2,1,2);n=0:length(y3t)-1;t=n*T;plot(t,y3t);xlabel(t(s);ylabel(y3(t);title(高通滤波器分离出的信号y3(t);axis(0 0.08 -3 3);改的Fs=10000;T=1/Fs;st=mstg1;fp=280;fs=450;wp=2*fp/Fs;ws=2*fs/Fs;Rp=0.1;As=60;N,wpo=ellipord(wp,ws,Rp,As);B,A=ellip(N,Rp,As,wpo);y1t=filter(B,A,st);figu

13、re(2)subplot(2,1,1);H,W=freqz(B,A,1000);k=abs(H);plot(W/pi,20*log10(k/max(k);grid on;xlabel(w/pi);ylabel(幅度(dB);axis(0 1 -80 5);title(损耗函数曲线);subplot(2,1,2);n=0:length(y1t)-1;t=n*T;plot(t,y1t);xlabel(t(s);ylabel(y1(t);title(低通滤波器分离出的信号y1(t);axis(0 0.08 -5 5);fpl=440;fpu=560;fsl=275;fsu=900;wp=2*fpl/

14、Fs,2*fpu/Fs;ws=2*fsl/Fs,2*fsu/Fs;Rp=0.1;As=60;N,wpo=ellipord(wp,ws,Rp,As);B,A=ellip(N,Rp,As,wpo);y2t=filter(B,A,st);figure(3)subplot(2,1,1);H,W=freqz(B,A,1000);k=abs(H);plot(W/pi,20*log10(k/max(k);grid on;xlabel(w/pi);ylabel(幅度(dB);axis(0 1 -80 5);title(损耗函数曲线);subplot(2,1,2);n=0:length(y2t)-1;t=n*T

15、;plot(t,y2t);xlabel(t(s);ylabel(y2(t);title(带通滤波器分离出的信号y2(t);axis(0 0.08 -5 5);fp=890;fs=600;wp=2*fp/Fs;ws=2*fs/Fs;Rp=0.1;As=60;N,wpo=ellipord(wp,ws,Rp,As);B,A=ellip(N,Rp,As,wpo,high);y3t=filter(B,A,st);figure(4)subplot(2,1,1);H,W=freqz(B,A,1000);k=abs(H);plot(W/pi,20*log10(k/max(k);grid on;xlabel(w

16、/pi);ylabel(幅度(dB);axis(0 1 -80 5);title(损耗函数曲线);subplot(2,1,2);n=0:length(y3t)-1;t=n*T;plot(t,y3t);xlabel(t(s);ylabel(y3(t);title(高通滤波器分离出的信号y3(t);axis(0 0.08 -5 5);function st=mstg1N=800;Fs=10000;T=1/Fs;Tp=N*T;t=0:T:(N-1)*T;k=0:N-1;f=k/Tp;fc1=Fs/10;fo1=fc1/10;fc2=Fs/20;fo2=fc2/10;fc3=Fs/40;fo3=fc3

17、/10;xt1=(3+2*cos(2*pi*fo1*t).*cos(2*pi*fc1*t);xt2=(3+2*cos(2*pi*fo2*t).*cos(2*pi*fc2*t);xt3=(3+2*cos(2*pi*fo3*t).*cos(2*pi*fc3*t);st=xt1+xt2+xt3;fxt=fft(st,N);subplot(2,1,1);plot(t,st);grid;xlabel(t(s);ylabel(s(t);axis(0 Tp/4 min(st) max(st);title(a) s(t)的波形);subplot(2,1,2);stem(f,abs(fxt)/max(abs(fxt),.);grid;title(b) s(t)的频谱);axis(0 Fs/5 0 1.2);xlabel(f(Hz);ylabel(幅度);