EE342.01: MATLAB M-FILE FOR PLOTTING DISCRETE-TIME SIGNAL SPECTRA

%
% Filename: example9.m
%
% Description: m-file to plot spectra of x[n]=(.5^n)u[n]
%

n = 0:10;                       % plot x[n]
x = 0.5.^n;
subplot(3,1,1);
stem(n,x,'filled');
xlabel('n'); ylabel('x[n]');
title('DT Signal x[n] = (0.5^n)u[n]');

W = -3*pi:0.01:3*pi;            % compute X(W)
X = 1./(1 - 0.5*exp(-j*W));

subplot(3,1,2);                 % plot |X(W)|
plot(W,abs(X));
xlabel('W '); ylabel('|X(W)|');
title('Magnitude (Amplitude) Spectra of x[n]');
gtext('1/(1-.5)'); gtext('1/(1+.5)');

subplot(3,1,3);                 % plot /_X(W)
plot(W,angle(X)*180/pi);    
xlabel('W '); ylabel('Angle(X(W)) ');
title('Phase Spectra of x[n]');