why is energy correction factor of hanning window eqaul to 1.63? I know Amplitude correction factor due to hanning funcion w(n)=0.5(1-cos(2npi/N)). So the signal is mulitplied by ACF of 2. How about energy correction factor?

It was discussed here:
http://maintenanceforums.com/eve/forums/a/tpc/f/3751089...921059853#3921059853

My take on the subject (based on good comments from Bill and others) is summed up in my post 14 January 2008 09:23 AM

This message has been edited. Last edited by: electricpete,

Pete,

The definition and methods of computing Fourier transforms vary.

In mathematics it is often useful to scale the transform so that it is a unitary operator - or in plain speak the spectrum has the same norm (rms value) as the time based signal (functions on a circle [Fourier series vs World Series] or on the real line).

Look at the terms of a Fourier series as +/- frequencies (i.e. sine and cosine series vs complex number series); the 0th term has a different scaling factor from the other terms. The 0th term has an extra factor of 2. Of course the non-zero terms in the sine/cosine series result from +/- frequencies as complex valued terms considering negative frequencies.

Thanks for your help.

This message has been edited. Last edited by: arvin,