數(shù)字信號IIR數(shù)字濾波器實驗報告

PAGEPAGE7數(shù)字信號處理實驗報告姓名：張賢輝班級：078205130第一題wp=0.4*pi;ws=0.6*pi;ap=0.5;as=50;%[b,a]=afd_butt(omgp,omgs,ap,as);[N,wc]=buttord(wp,ws,ap,as,'s');[b,a]=butter(N,wc,'s');w=[0:1:500]*pi/500;h=freqs(b,a,w);subplot(221);plot(w/pi,abs(h));title('幅度響應(yīng)');grid;subplot(223);plot(w/pi,20*log10(abs(h)));title('幅度響應(yīng)(dB)');grid;subplot(222);plot(w/pi,angle(h)*180/pi);title('相頻響應(yīng)');grid;subplot(224);impulse(b,a);tiltle('脈沖響應(yīng)');grid;第二題T=1;Fs=1/T;wpz=0.4;wsz=0.6;%[b,a]=afd_butt(omgp,omgs,ap,as);wp=(2/T)*tan(wpz*pi/2);ws=(2/T)*tan(wsz*pi/2);ap=0.5;as=50;[N,wc]=buttord(wp,ws,ap,as,'s');[b,a]=butter(N,wc,'s');%w=[0:1:500]*pi/500;[Bz,Az]=bilinear(b,a,Fs);[h,w]=freqz(Bz,Az);subplot(221);plot(w/pi,abs(h));title('幅度響應(yīng)');grid;subplot(223);plot(w/pi,20*log10(abs(h)));title('幅度響應(yīng)(dB)');grid;subplot(222);plot(w/pi,angle(h));title('相頻響應(yīng)');grid;n=[0:1:59];imp=[1;zeros(59,1)];y=filter(Bz,Az,imp);subplot(224);plot(n,y);title('脈沖響應(yīng)');grid;T=1;Fs=1/T;wpz=0.2;wsz=0.4;%[b,a]=afd_butt(omgp,omgs,ap,as);wp=(2/T)*tan(wpz*pi/2);ws=(2/T)*tan(wsz*pi/2);ap=0.25;as=50;[N,wc]=buttord(wp,ws,ap,as,'s');[b,a]=butter(N,wc,'s');%w=[0:1:500]*pi/500;[Bz,Az]=bilinear(b,a,Fs);[h,w]=freqz(Bz,Az);subplot(221);plot(w/pi,abs(h));title('幅度響應(yīng)');grid;subplot(223);plot(w/pi,20*log10(abs(h)));title('幅度響應(yīng)(dB)');grid;subplot(222);plot(w/pi,angle(h));title('相頻響應(yīng)');grid;n=[0:1:59];imp=[1;zeros(59,1)];y=filter(Bz,Az,imp);subplot(224);plot(n,y);title('脈沖響應(yīng)');grid;數(shù)字信號實驗報告姓名：張賢輝班級：078205130實驗?zāi)康氖煜るp線性變換法設(shè)計IIR數(shù)字濾波器的原理與方法熟悉用脈沖響應(yīng)不變法設(shè)計IIR數(shù)字濾波器的原理與方法實驗原理理解脈沖響應(yīng)變換和雙線性變換原理，會用MTLAB設(shè)計基本的IIR數(shù)字濾波器三、修改后的實驗程序功能函數(shù)function[b,a]=u_buttap(N,OmegaC);[z,p,k]=buttap(N);p=p*OmegaC;k=k*OmegaC^N;B=real(poly(z));b=k*B;b0=k;a=real(poly(p));功能函數(shù)function[b,a]=afd_butt(Omgp,Omgs,Ap,As);ifOmgp<=0error('passbandedgemustbelagerthan0')endifOmgs<=Omgperror('StopbandedgemustbelagerthanPassbandedge')endif(Ap<=0)|(As<0)error('PBrippleand/orSBattentionmustbelagerthan0')endN=ceil((log10((10^(Ap/10)-1)/(10^(As/10)-1)))/(2*log10(Omgp/Omgs)));fprintf('\n***ButterworthFilterOrder=%2.0f\n',N);OmegaC=Omgp/((10^(Ap/10)-1)^(1/(2*N)));[b,a]=u_buttap(N,OmegaC);第一題（1）T=1;Fs=1/T;OmegaP=0.4*pi/T;OmegaS=0.6*pi/T;Ap=0.5;As=50;%[b,a]=afd_butt(omgp,omgs,ap,as);%[N,wc]=buttord(wp,ws,ap,as,'s');%[b,a]=butter(N,wc,'s');[cs,ds]=afd_butt(OmegaP,OmegaS,Ap,As);%w=[0:1:500]*pi/500;%h=freqs(b,a,w);[b,a]=impinvar(cs,ds,Fs);[h,w]=freqz(b,a);subplot(2,2,1);plot(w/pi,abs(h));title('幅度響應(yīng)');grid;subplot(2,2,3);plot(w/pi,20*log10(abs(h)));title('幅度響應(yīng)(dB)');grid;subplot(2,2,2);plot(w/pi,angle(h)*180/pi);title('相頻響應(yīng)');grid;n=[0:1:59];imp=[1;zeros(59,1)];y=filter(b,a,imp);subplot(2,2,4);plot(n,y);title('脈沖響應(yīng)');grid;第二題（2）T=1;Fs=1/T;wpz=0.4;wsz=0.6;%[b,a]=afd_butt(omgp,omgs,ap,as);wp=(2/T)*tan(wpz*pi/2);ws=(2/T)*tan(wsz*pi/2);ap=0.5;as=50;%[N,wc]=buttord(wp,ws,ap,as,'s');%[b,a]=butter(N,wc,'s');[b,a]=afd_butt(OmegaP,OmegaS,AP,as);[BZ,AZ]=bilinear(b,a,Fs);[h,w]=freqz(Bz,Az);subplot(221);plot(w/pi,abs(h));title('幅度響應(yīng)');grid;subplot(223);plot(w/pi,20*log10(abs(h)));title('幅度響應(yīng)(dB)');grid;subplot(222);plot(w/pi,angle(h));title('相頻響應(yīng)');grid;n=[0:1:59];imp=[1;zeros(59,1)];y=filter(Bz,Az,imp);su