I've been implementing a Welch method FFT and I am trying to work out the correct scaling factor that should be applied to the output of the function so the PSD is accurate because at the moment it's too low.
I am using scipy, signal.welch.
I know what the Power per resolution from a measurement of my signal and ive also calculated manually. I also know my manual calculation is correct because a straight forward FFT produces power around what I calculate but it fluctuates wildly across frequency (+ - 4 dB along what visually appears to be the average in the signal bandwidth).
So I needed a Welch method for a better spectral estimation. However this Welch method output it needs to be shifted vertically in dB. Meaning there must be a scaling factor applied.
Would anyone be able to say what it should be, perhaps the scaling factor varies with fftsize, percent of overlap, length of each segment etc?
Many thanks for your help