fftdemo17.m

Fs = 10;                        % Sampling frequency
Ts = 1/Fs;                      % Sampling period
N = 128;                         % Total number of samples
n = 0:N-1;                      % Samples
t = Ts*(n);                     % Sampled times

fc1 = 1;                        % Frequency of first sinusoid
fc2 = 1.5;                      % Frequency of second sinusoid
y1 = cos(2*pi*fc1*t);           % Discrete first sinusoid
y2 = cos(2*pi*fc2*t);           % Discrete second sinusoid
y = y1+y2;                      % Total discrete signal

Y = fft(y);                     % The fft of the signal
df = 1/(N*Ts);                  % The frequency resolution
k = n;                          % Frequency spectrum samples
f = k*df;                       % Frequency values at the k samples 

% Plot the useful fft of the signal with more samples
figure
stem(f,abs(Y)./N,'filled')
title('Useful Fourier Transform of y')
ylabel('Scaled |fft(y)|')
xlabel('frequency (Hz)')