On Sat, 10 Apr 2004 17:16:24 -0400, Jerry Avins <jya@ieee.org> wrote:>Don't ask me to prove it, but windows, in effect, smear the smearing. In >exchange for reducing the smearing if off-center frequencies, they add >some to the centered ones. The best a good window can do is equalize >smearing and confine it to near-by bins. It's that no-free-lunch thing. > >Jerry >--(snipped) Yep, non-rectangular windows smear the spectral energy, that's centered right on a DFT bin, to neighboring bins. When spectral energy is centered right on a DFT bin, there will be no DFT leakage with rectangular windowing. In that case windowing with a non-rectangular window is not a good idea. If you take the Fourier transform of a Hann (also known as Hanning, von Hann, raised cosine) function, you'll get the sum of three sin(x)/x spectral components. There will be sin(x)/x-shaped spectral energy centered at DC (0 Hz), a sin(x)/x centered at a positive freq, and a sin(x)/x centered at a negative frequency. [-Rick-]
Window function
Started by ●April 10, 2004
Reply by ●April 12, 20042004-04-12