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From: "Steve Amphlett" <Firstname.Lastname@Where-I-Work.com>
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Subject: Re: FFT of signal segments
Date: Mon, 20 Oct 2008 21:29:02 +0000 (UTC)
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<snip, correction factors...


> > Your 0.5 will correct the amplitude. =A0For energy correction, use sqrt(3=
> /8). =A0Most people would express the correction the other way up:
> >
> > Multiply by 2 for amplitude, sqrt(8/3) for energy.
> 
> 
> just to clarify, is the correction of energy the one to use when
> plotting power?
> 
> also, I don't think the problem of the different FFT peak magnitudes
> is to do with this correction factor as this just scales it by the
> same amount.
> cheers.

If you integrate the hanning window, you'll get the amplitude correction.  If you integrate the square of the window, you'll get the energy correction.

Which correction you use is your choice and depends on your application.  In the software that I write, I use amplitude for all plots of dB (I do acoustics) vs frequency.  But anything that involves summation to get an overall level will require energy correction.