Contents

% IIR system in lattice-ladder structure
% lab9_3.m * mw * 04/12/2007

Frequency responses

alpha = [-.5 0 .5];
w = 0:511; w = pi*w/512; % radian frequency
FIG1 = figure('Name','lab9_3 : Complementary lowpass and highpass',...
    'NumberTitle','off');
hold on
for k=1:length(alpha)
    H_ap = freqz([-alpha(k) 1],[1 -alpha(k)],w); % allpass
    H_lp = .5*(1+H_ap);  % low pass
    H_hp = .5*(1-H_ap);  % high pass
    plot(w/pi,abs(H_lp),w/pi,abs(H_hp))
end
grid, axis([0 1 0 1]);
xlabel('\Omega / \pi\rightarrow'),ylabel('|H(e^{j\Omega})| \rightarrow')
title('Frequency response')
legend(['alpha = ',num2str(alpha(1))],['alpha = ',num2str(alpha(2))],...
    ['alpha = ',num2str(alpha(3))],'Location','Best')
hold off

Published with MATLAB® 7.3