iir.rar_IIR数字滤波器_数字录波器_波形 滤波_频率滤波

clear t=0:0.001:0.25; x=sin(2*pi*10*t)+sin(2*pi*50*t)+sin(2*pi*200*t); y0=x+0.6*x.*rand(1,size(x)); x1=sin(2*pi*50*t); plot(t,y0,'r-',t,x,'k-',t,x1,'b-+') hold on dt=0.001; F1=36; F2=90; w=tan(pi*(F2-F1)*dt); B=cos(pi*(F2+F1)*dt)/cos(pi*(F2-F1)*dt); f0=w^2/(1+2^0.5*w+w^2);%给定二阶递推滤波器系数 f1=0; f2=-2*f0; f3=0; f4=f0; g1=-2*B*(2+w*2^0.5)/(1+2^0.5*w+w^2); g2=2*(1+2*B^2-w^2)/(1+2^0.5*w+w^2); g3=-2*B*(2-w*2^0.5)/(1+2^0.5*w+w^2); g4=(1-2^0.5*w+w^2)/(1+2^0.5*w+w^2); for k=1:251 if k<=7 y(k)=0; else y(k)=f0*x(k)+f1*x(k-1)+f2*x(k-2)+f3*x(k-3)+f4*x(k-4)-g1*y(k-1)-g2*y(k-2)-g3*y(k-3)-g4*y(k-4); end end for k=1:251 if k<=7 y1(k)=0; else y1(k)=f0*y(k)+f1*y(k-1)+f2*y(k-2)+f3*y(k-3)+f4*y(k-4)-g1*y1(k-1)-g2*y1(k-2)-g3*y1(k-3)-g4*y1(k-4); end end for k=1:251 if k<=7 y2(k)=0; else y2(k)=f0*y1(k)+f1*y1(k-1)+f2*y1(k-2)+f3*y1(k-3)+f4*y1(k-4)-g1*y2(k-1)-g2*y2(k-2)-g3*y2(k-3)-g4*y2(k-4); end end for k=1:251 if k<=7 y3(k)=0; else y3(k)=f0*y2(k)+f1*y2(k-1)+f2*y2(k-2)+f3*y2(k-3)+f4*y2(k-4)-g1*y3(k-1)-g2*y3(k-2)-g3*y3(k-3)-g4*y3(k-4); end end plot(t,y3,'g-o'); legend('加入白噪声后的信号','给定信号曲线','滤波后理想曲线','八阶IIR带通滤波器滤波后曲线');