In this matlab tutorial we show how to apply simple input signal to a digital filter designed in matlab and view the filter response.

Let us consider first the design of a simple digital filter. A digital filter is described by coefficients a and b. These are as follows,

We generated in earlier post different types of signals. These will be applied to the digital filter. The signals are again provided here,

Let us consider first the design of a simple digital filter. A digital filter is described by coefficients a and b. These are as follows,

b = 1 a = 1, -1, 0.9

We generated in earlier post different types of signals. These will be applied to the digital filter. The signals are again provided here,

n0 = 0; n1 = -20; n2 = 120; n = [n1:n2]; M= 60; N = [n1:n2]; % generate impulse sequence imp = [(N-n0) == 0]; %generate unit impulse u = [(N-n0) >= 0]; % generate real valued signal xr = (0.75).^n; % complex valued exponential signal xexp = exp((4+1*j)*n); % sinusoid signal x = 7*cos(0.4*pi*n+pi/3)+3*sin(0.5*pi*n); % uniformly distributed random signal runi = rand(1,M); % Gaussian distributed random signal rgau = randn(1,M);

Now these signals are applied to the digital filter. The code is shown below.

% Apply Filter

b = [1];

a = [1 -1 0.9];

y1 = filter(b,a,imp);

y2 = filter(b,a,u);

y3 = filter(b,a,x);

y4 = filter(b,a,xr);

y5 = filter(b,a,xexp);

y6 = filter(b,a,rgau);

figure(4)

subplot(3,2,1)

stem(N,y1)

title('Response due to Impulse Input')

xlabel('n')

ylabel('Impulse Response')

subplot(3,2,2)

stem(N,y2)

title('Response due Unit Input')

xlabel('n')

ylabel('Unit Step Response')

subplot(3,2,3)

stem(N,y3)

title('Response due x input')

xlabel('n')

ylabel('Impulse x Response')

subplot(3,2,4)

stem(y4)

title('Response due sinusoid x Input')

xlabel('n')

ylabel('xexp Response')

subplot(3,2,5)

stem(N,y3)

title('Response due x real input')

xlabel('n')

ylabel('Real x Response')

subplot(3,2,6)

stem(y4)

title('Response due to complex x Input')

xlabel('n')

ylabel('Complex x Response')

The response of the filter to the different input signal is as follows,

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