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A Hamming Window is a weighting function used very often in digital signal processing (DSP). It is a method of achieving sidelobe suppression in an FFT operation.

A hamming window of length n is defined as follows:

For k = 0, …, n - 1

w(k + 1) = 0.54 - 0.46*cos(2*π*k / (n - 1))

Use of the Hamming Window can get you 40 dB of sidelobe suppression, which is often excellent for many applications. This is awesome compared to the 15 dB sidelobes you would get using a rectangular (uniform) window. The only drawback of the Hamming Window is that the mainlobe width is spread out by a factor of 1.5.


                                                                                                                        
                                                                                                                        
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This effect is seen above, where in the figure on the left, the first sidelobes are not much diminished from the main lobe. This is the result of the FFT of a rectangular window. The figure on the right is the FFT of the Hamming window; while the main lobe is enlarged quite a bit, its sidelobes are very far down.

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