Band limited input sequence

Use fir2 to create a bandlimited input sequence

clf;

freq = [0 0.45 0.5 1];

mag = [0 1 0 0];

x = fir2(99, freq, mag);

% Evaluate and plot the input spectrum

[Xz, w] = freqz(x, 1, 512, ’whole’);

subplot(2,1,1);

plot(w/pi, abs(Xz)); axis([0 1 0 1]); grid

xlabel(’\omega/\pi’); ylabel(’Magnitude’);

title(’Input Spectrum’);

subplot(2,1,2);

% Generate the up-sampled sequence

L = input(’Type in the up-sampling factor = ’);

y = zeros(1, L*length(x));

y([1: L: length(y)]) = x;

% Evaluate and plot the output spectrum

[Yz, w] = freqz(y, 1, 512, ’whole’);

plot(w/pi, abs(Yz)); axis([0 1 0 1]); grid

xlabel(’\omega/\pi’); ylabel(’Magnitude’);

title(’Output Spectrum’);