Re: Windowed FFT power and amplitude spectrum

PS: You can find a nice explenation about coherent power gain on this page:
http://www.bores.com/courses/advanced/windows/10_cpg.htm

Karin

"Cagri" <dr_cagri_tanriover@xxxxxxxxxxx> schrieb im Newsbeitrag
news:VI2dnR3EpomGWXbfRVn-1Q@xxxxxxxxxxxxxxx
> Here is another fascinating question on FFT spectrum!!
>
> I am trying to find how to incorporate the normalisation factors when
> windowing is applied to the time series before FFT is applied.
>
> When windowing (eg Hanning, flat top etc.) is applied to the time series,
> the amplitude of the time series obviously changes. In this case, how do
> we represent the power and amplitude spectrum in the frequency domain
> after applying the FFT?
>
> My guess is P(i)=|x(i)|^2/N power expression will probably need to be
> multiplied by a scaling factor but I am not sure how this scaling factor
> will be calculated and how exactly it will be applied. This is also valid
> for the amplitude expression; A(i)=|x(i)|/N
>
> I also think that the scaling factors will depend on the type of windowing
> that is used. How are those scaling factors calculated? Is there a
> reference that I can have a look at to shed some light on this issue?
>
> Thank you to all who provide feedback.
>
> Regards,
> Cagri
>
>
>
> This message was sent using the Comp.DSP web interface on
> www.DSPRelated.com


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