fftdemo4.m

Fs = 10;                        % Sampling frequency
Ts = 1/Fs;                      % Sampling period
N = 32;                         % Total number of samples
n = 0:N-1;                      % Samples
t = Ts*(n);                     % Sampled times
y = cos(2*pi*t);                % Discrete 1 Hz signal
yp = cos(18*pi*t);              % Discrete 9 Hz signal
ypp = cos(20*pi*t);             % Discrete 10 Hz signal

% Plot the 1 Hz signal and its discrete counter-part
figure
subplot(3,1,1)
stem(t,y,'filled')
hold on;
% The 'continuous signal' (interpolated and highly sampled signal)
plot(linspace(min(t),max(t),length(0:.01:max(t))),cos(2*pi*(0:.01:max(t))))
title(['Sampled 1 Hz Signal with Fs = ',num2str(Fs)])

% Plot the 9 Hz signal and its discrete counter-part
subplot(3,1,2)
stem(t,yp,'filled')
hold on;
% The 'continuous signal' (interpolated and highly sampled signal)
plot(linspace(min(t),max(t),length(0:.01:max(t))),cos(18*pi*(0:.01:max(t))))
title(['Sampled 9 Hz Signal with Fs = ',num2str(Fs)])

% Plot the 10 Hz signal and its discrete counter-part
subplot(3,1,3)
stem(t,ypp,'filled')
hold on;
% The 'continuous signal' (interpolated and highly sampled signal)
plot(linspace(min(t),max(t),length(0:.01:max(t))),cos(20*pi*(0:.01:max(t))))
title(['Sampled 10 Hz Signal with Fs = ',num2str(Fs)])