IIR数字滤波器设计（matlab）.rar

Wp=0.1*2*pi/1;Ws=0.3*2*pi/1;Ap=1;As=25;% 设置通带和阻带 Fs=1;%抽样频率 wp=Wp*Fs;ws=Ws*Fs;%确定模拟BW指标 N=buttord(wp,ws,Ap,As,'s');%确定AF阶数 wc=wp/(10^(0.1*Ap)-1)^(1/2/N);%由通带确定3dB截频率 [numa,dena]=butter(N,wc,'s');%确定BW AF [numd,dend]=impinvar(numa,dena,Fs);%确定DF [bs,as]=butter(N,wc,'s');%求模拟低通滤波器的系数 [B,A]=impinvar(bs,as,Fs);%按Fs把模拟低通滤波器的系数转换成数字滤波器 [H1,f1]=freqz(B,A);%计算数字滤波器的响应曲线 plot(f1/pi,20*log10(abs(H1)),'k','linewidth',2) xlabel('频率/Hz'); ylabel('幅值/dB') title('ButterWorth低通滤波器幅频响应(脉冲响应不变法)') axis([0 1 -50 3]); %grid; line([2*2/44.1 2*2/44.1],[-50 5],'color','k','linestyle','--'); line([10*2/44.1 10*2/44.1],[-50 5],'color','k','linestyle','--'); x=[-4,-2,0,-4,-6,-4,-2,-4,-6,-6,-4,-4,-6,-6,-2,6,12,8,0,-16,-38,-60,-84,-90,-66,-32,-4,2,-4,8,12,12,10,6,6,6,4,0,0,0,0,0,-2,-4,0,0,0,-2,-2,0,0,-2,-2,-2,-2,0];%输入序列 Y=filter(B,A,x);%滤波 N=56;n=0:N-1;%设置参数N、n subplot(2,1,1);plot(n,x);%画图 title('(双线性变换法数据2)X序列（滤波前）') subplot(2,1,2);plot(n,Y); title('(双线性变换法数据2)Y序列（滤波后）')