EXPERIMENT - 1

AIM

To demonstrate Ideal Filters .

THEORY

The ideal low-pass filter allows all signals below some cutoff of W rad/sec to pass through undistorted, while completely cutting off all other frequencies. This is sometimes said to be the ideal brick wall filter.

Ideal types of filter are impossible to realize.

MATLAB COMMANDS USED

* for loop
* if  else

MATLAB CODE

%ideal filters
%Ideal low pass
p=zeros(1,100);
for t=1:100;
    if(t>30)
        p(t)=0;
    else
        p(t)=1;
    end;
end;
subplot(2,2,1)
plot(p,'black','linesmoothing','on');
axis([0 100 -0.1 1.1]);
xlabel('Frequency (KHz)');
ylabel('Gain')
title('Ideal Low pass filter with cut off at 30 KHz')

%Ideal high pass
for t=1:100;
    if(t>40)
        p(t)=1;
    else
        p(t)=0;
    end;
end;
subplot(2,2,2)
plot(p,'black','linesmoothing','on');
axis([0 100 -0.1 1.1]);
xlabel('Frequency (KHz)');
ylabel('Gain')
title('Ideal High pass filter with cut off at
40 KHz')

%Ideal band pass
for t=1:100;
    if(t>30 && t<60)
        p(t)=1;
    else
        p(t)=0;
    end;
end;
subplot(2,2,3)
plot(p,'black','linesmoothing','on');
axis([0 100 -0.1 1.1]);
xlabel('Frequency (KHz)');
ylabel('Gain')
title('Ideal Band pass filter with band edges
at 30 KHz and 60 KHz');

%Ideal band stop
for t=1:100;
    if(t>30 && t<50)
        p(t)=0;
    else
        p(t)=1;
    end;
end;
subplot(2,2,4)
plot(p,'black','linesmoothing','on');
axis([0 100 -0.1 1.1]);
xlabel('Frequency (KHz)');
ylabel('Gain')
title('Ideal Band stop filter with band
edges at 30 KHz and 50 KHz')

RESULT

The frequency response of Ideal filters is plotted.We can see that the cut off is very sharp.