Signal Processing Toolbox™

blackman - Blackman window

Syntax

w = blackman(L) w = blackman(L,'sflag')

Description

w = blackman(L) returns the L-point symmetric Blackman window in the column vector w, where L is a positive integer.

w = blackman(L,'sflag') returns an L-point Blackman window using the window sampling specified by 'sflag', which can be either 'periodic' or 'symmetric' (the default). The 'periodic' flag is useful for DFT/FFT purposes, such as in spectral analysis. The DFT/FFT contains an implicit periodic extension and the periodic flag enables a signal windowed with a periodic window to have perfect periodic extension. When 'periodic' is specified, blackman computes a length L+1 window and returns the first L points. When using windows for filter design, the 'symmetric' flag should be used.

Note If you specify a one-point window (set L=1), the value 1 is returned.

Examples

Create a 64-point Blackman window and display the result using WVTool:

L=64;
wvtool(blackman(L))

Algorithm

The equation for computing the coefficients of a Blackman window is

The window length .

Blackman windows have slightly wider central lobes and less sideband leakage than equivalent length Hamming and Hann windows.

References

[1] Oppenheim, A.V., and R.W. Schafer. Discrete-Time Signal Processing. Upper Saddle River, NJ: Prentice-Hall, 1999, pp. 468-471.

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