I've looked at previous answers and none of the answers seem to agree (perhaps I'm missing something obvious):
I would like to know what the correct scaling to use is for
- energy and
- power density spectra
after using MATLABs
fft function to convert a signal into the frequency domain.
The problem I have is that I have been through various forums and seen a number of different answers, with some people saying to divide by length (L) of the original sample and others saying to divide by sampling frequency (Fs).
I understand that you divide by L in the case of a DFT where L is the same both before and after the fft however I don't see how this becomes Fs if the lengths are different as L does not directly relate to Fs.
Additionally I would like clarification on whether the scale factor of 1/Fs after the fft is for amplitude or energy spectrum - I understand that it comes from parsevals theorem which relates the energy before and after the fft however I am seeing answers which suggest the scale factor Fs should be applied to amplitude spectrum - surely it should be root(Fs)?