Piierre
Newbie level 4
I have a question regarding using FFT i MATLAB
When I make an FFT of a small number of periods of a signal the frequencys are moved up to a larger value, for example a signal with the frequency 3Hz are shown in the FFT plot as 3.5Hz and so on. If I increase the number of periods used to make the FFT the value closes in to the real one. It seems like the offset has an exponential relation to the number of periods
Anybody knows why this is? Is it rounding in Matlab or limitations in the FFT algorithm or what?
When I make an FFT of a small number of periods of a signal the frequencys are moved up to a larger value, for example a signal with the frequency 3Hz are shown in the FFT plot as 3.5Hz and so on. If I increase the number of periods used to make the FFT the value closes in to the real one. It seems like the offset has an exponential relation to the number of periods
Anybody knows why this is? Is it rounding in Matlab or limitations in the FFT algorithm or what?