I could not get csvread to read the file correctly, because each number in the second column has ‘;;;;’ following it in the file you attached.
This works:
[t,S] = xlsread(filename);
X = cellfun(@(c) sscanf(c,'%f;;;;'), S);
Ts = mean(diff(t));
Fs = 1/Ts;
L = length(t);
Fn = Fs/2;
FX = fft(X)/L;
Fv = linspace(0, 1, fix(L/2)+1)*Fn;
Iv = 1:length(Fv);
figure(1);
semilogy(Fv, abs(FX(Iv))*2)
grid
title('Fourier Transform Of Original Signal ‘X’')
xlabel('Frequency (Hz)')
ylabel('Amplitude')
I changed your code slightly to correct for the sampling time interval and to define a few other variables from the data.
