Hi all. Used the site for a while to browse topics but this is my first post.

I'm doing a MatLab project analysing the frequency components of various data sets of signals from a SimuLink electrical generator that I have created. The data has been collated using the 'sink' blocks in SimuLink. It has been calulated with a 0.0005 timestep.

Each data set is 24001 long and is of type 'double'.

This is what ive tried, but I seem to be having problems.

Fs=2000;
T=1/Fs;
N=24001;
t=(0:N-1)*T;
NFFT=2^nextpow2(N);
f=Fs/2*linspace(0,1,NFFT/2+1);
TESS=fft(Tess,NFFT)/N;
plot(f,2*abs(TESS(1:NFFT/2+1)))

The problem is the magnitudes of frequencies are slightly less than the values I would expect. I was thinking this may be a common mistake and I was wondering if anyone could shed any light on why this is?

Any advice would be appreciated.

Lodgi

 

I think that you could try to create a sin wave that you are sure about the amplitude and use this script. At a first glance the script is the same that I normally use.