I am trying to minimize the noise in a spectrum of a variable. I am trying to to divide the time history in equal parts, to do the FFT of this time history parts and to do an average between these FFT.
Doing this procedure I have find that the trend, at the high frequencies seems to be a little bit different from the one without doing this procedure. I have multiplied every part of the time history by a Tukey window, using the command with Matlab
Using the Tukey window, I have find that the trends seems more similar with the first one. Can someone explain me why? I have tried to search the theory of this window, but I always find the definition of the filter, but I cannot understand which could be the effect of this window.
A other fact that I have noticed is the fact that obviously using the Tukey window the energy content is reduced, are there technique to reduce the noise avoiding this reduction?
I just need a suggestion to start, it is difficult to understand which is the correct technique to reduce the noise.