Hamming Window

This is the sum of a rectangle and a Hanning window. An amplitude weighting of the time signal used with gated continuous signals to give them a slow onset and cut-off in order to reduce the generation of side lobes in their frequency spectrum. This window has similar properties to the Hanning window with the added feature that it suppresses the first sidelobe. However, the fall-off rate of the sidelobes is only 20dB per decade compared to 60dB per decade for the Hanning window.

amplitude correction = 1.855, energy correction = 1.586

In the time domain this function is shown below:

The frequency response of this window is shown along with that of a rectangular window for comparison:

The Hamming has better selectivity for large signals, but it suffers from the disadvantage that the rest of the sidelobes are higher, and in fact fall off slowly at 20 dB per octave like those of the rectangular window. The Hamming window had some advantage in the days when FFT analyzers only had 50 dB or so of dynamic range, but nowadays it is essentially obsolete.

See also: Blackman Window, Blackman-Harris Window, Bohman Window, Cauchy Window, Fast Fourier Transform, Hanning Window, Leakage, Rectangular Window, Windowing.

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Subjects: Noise & Vibration Signal Processing

Bruel & Kjaer - Technical Reviews These documents give detailed articles on measurement and signal processing theory.