EE342: MATLAB M-FILE FOR VIEWING DISCRETE-TIME SIGNAL SPECTRA

%
% Filename: example7.m
%
% Description: m-file to plot spectra of f1[k]=(.95^k)u[k]
%              and f2[k]=(-.95^k)u[k].
%

clear;                          % clear matlab memory

k = 0:20;                       % define k, f1[k], f2[k]
f1 = 0.95.^k;
f2 = (-0.95).^k;

W = -15:0.01:15;                % define W, F1(W), F2(W)
F1 = 1./(1 - 0.95*exp(-j*W));
F2 = 1./(1 + 0.95*exp(-j*W));

figure(1); clf;                 % open and clear figure 1

subplot(3,1,1);                 % plot f1[k]
stem(k,f1,'filled'); grid;
xlabel('k'); ylabel('f_1[k]');
title('Slowly Varying DT Signal: f_1[k]=(0.95^k)u[k]');

subplot(3,1,2);                 % plot |F1(W)|
plot(W,abs(F1)); grid;
xlabel('\Omega rad'); ylabel('|F_1(\Omega)|');
title('Magnitude (Amplitude) Spectra of f_1[k]');

subplot(3,1,3);                 % plot /_F1(W)
plot(W,angle(F1)*180.0/pi); grid;
xlabel('\Omega rad'); ylabel('\angle(F_1(\Omega)) ^o');
title('Phase Spectra of f_1[k]');

figure(2); clf;                 % open and clear figure 2

subplot(3,1,1);                 % plot f2[k]
stem(k,f2,'filled'); grid;
xlabel('k'); ylabel('f_2[k]');
title('Fast Varying DT Signal: f_2[k]=(-0.95^k)u[k]');

subplot(3,1,2);                 % plot |F2(W)|
plot(W,abs(F2)); grid;
xlabel('\Omega rad'); ylabel('|F_2(\Omega)|');
title('Magnitude (Amplitude) Spectra of f_2[k]');

subplot(3,1,3);                 % plot /_F2(W)
plot(W,angle(F2)*180.0/pi); grid;
xlabel('\Omega rad'); ylabel('\angle(F_2(\Omega)) ^o');
title('Phase Spectra of f_2[k]');