%		     The University of Queensland
%     School of Information Technology & Electrical Engineering
%	     COMS3100/7100 Introduction to Communications

f = -40000:100:40000;

H = zeros(size(f));
fc = 20000;
i = find(abs(f) <= fc);
H(i) = 1;

subplot(3,2,5);
plot(f, H);
hndl = get(gcf, 'CurrentAxes');
set(hndl, 'FontName', 'times', 'YLim', [0, 1.2]);
xlabel('\fontname{times}\omega (\times 2\pi)');
ylabel('\fontname{times}\itH_{\rmlp}\rm(\itj \omega\rm)');

t = -2e-4:1e-6:2e-4;
h = 2 * fc * sinc(2 * fc * t);

subplot(3,2,6);
plot(t,h,'m');
hndl = get(gcf, 'CurrentAxes');
set(hndl, 'FontName', 'times');
xlabel('\fontname{times}\omega (\times 2\pi)');
ylabel('\fontname{times}\ith_{\rmlp}\rm(\itt\rm)');