Blackman-Harris Window

A weighting that is applied in the time domain to reduce leakage within a Fourier Transform analysis.
The Blackman-Harris windows are a family of three and four term windows. The variations on the coefficients allow a trade between main-lobe width and side-lobe level.

3 term -67dB side-lobe
where
w(t) = weighting as a function of time
t = time
N = total length of window

3 term -61dB side-lobe

4 term -92dB side-lobe
The Blackman-Harris window has much the same performance as the Kaiser-Bessel window, except that it suppreses the sidelobes more than 92dB at a cost of an 11% wider noise bandwidth.

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:

4 term -74dB side-lobe

See also: Bohman Window, Cauchy Window, Hamming Window, Rectangular Window, Windowing.

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Subjects: Noise & Vibration Signal Processing