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.

amplitude correction = 2.0, energy correction = 1.633

The Hanning window is a general purpose window for the analysis of continuous signals and should be used in most cases, because it has the best overall filter characteristic. The Hanning window may also be used for system analysis (frequency response measurements) - for both excitation and response signal when a random excitation signal is used.

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 Hanning window causes a distortion of the wave form used by the analyzer to calculate the spectrum, and this results in the measured levels being too low, hence the corrections for amplitude or energy. When processing continuous data, this effect is compensated for, but an error is introduced if the Hanning window is used for transient data.

See also: Fast Fourier Transform, Flattop Window, Hamming Window, Hanning-Poisson Window, Kaiser Bessel Window, Leakage, Overlap Processing, 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.