iir2
• % filter spec
• wp=1000;
• ws=1500;
• rp=3;
• rs=20;
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• %Folding Frequency or Normalized Sampling frequency
• fF=fs/2;
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• %Normalized Analog Butterworth filter frequencies
• wpa=wp/fF;
• wsa=ws/fF;
• [n,wc]=buttord(wpa,wsa,rp,rs);
• [b,a]=butter(n,wc,"high");
• %[z,p,k]=cheb1ap(10,3);
• %[zd,pd,kd] = bilinear(z,p,k,fs);
• [H,f]=freqz(b,a,512,fs);
• subplot(3,1,2);
• plot(f,abs(H));
• figure, plot(f,angle(H))
• %plot(f,20*log10(abs(H)));
• xlabel('frequency in hz');
• ylabel('magnitude');
• title(['butterworth filter of order',num2str(n)]);
• %fs=input('enter the sampling frequency which is greater than twice
the max');
• fs=8000;
• N=1024;
• %M=2;
• n=0:N-1;
• f1=500;
• f2=2000;
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x=3*sin(2*pi*f1*n/fs)+cos(2*pi*f2*n/fs);
%Spectrum of Input
X=2*abs(fft(x,N))/N;
%X(1)=X(1)/2;
f=(0:1:N/2-1)*fs/N;
subplot(3,1,1);
plot(f,X(1:N/2));
xlabel('frequency in hz');
ylabel('magnitude of x');
title(['spectrum of input signal at ', num2str(f1), 'and at ', num2str(f2)]);
• % grid minor
• y=filter(b,a,x); % Filter the input signal
• y=2*abs(fft(y,N))/N;
• % %y(1)=y(1)/2;
• f=(0:N/2-1)*fs/N;
• subplot(3,1,3);
• plot(f,y(1:N/2));
• xlabel('frequency in hz');
• ylabel('magnitude of y');