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blackmanharris

Minimum four-term Blackman-Harris window

Description

w = blackmanharris(L) returns an L-point symmetric four-term Blackman-Harris window.

example

w = blackmanharris(L,sflag) returns a Blackman-Harris window using the window sampling method specified by sflag.

w = blackmanharris(___,typeName) specifies the option to return the window w with single or double precision.

Examples

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Create a 32-point symmetric Blackman-Harris window. Display the result using wvtool.

L = 32;
wvtool(blackmanharris(L))

Figure Window Visualization Tool contains 2 axes objects and other objects of type uimenu, uitoolbar, uipanel. Axes object 1 with title Time domain, xlabel Samples, ylabel Amplitude contains an object of type line. Axes object 2 with title Frequency domain, xlabel Normalized Frequency (\times\pi rad/sample), ylabel Magnitude (dB) contains an object of type line.

Input Arguments

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Window length, specified as a positive integer.

Note

If you specify L as noninteger, the function rounds it to the nearest integer value.

Data Types: single | double | int8 | int16 | int32 | int64 | uint8 | uint16 | uint32 | uint64

Window sampling method, specified as:

  • "symmetric" — Use this option when using windows for filter design.

  • "periodic" — Use this option when using windows for spectral analysis. When you specify "periodic", blackmanharris computes a window of length L + 1 and returns the first L points. The missing endpoint is the beginning of the next period of the periodic extension of the sequence. Therefore, the sequence satisfies the periodicity assumption of the discrete Fourier transform.

Data Types: char | string

Since R2024b

Output data type (class), specified as one of these:

  • "double" — Use this option to return a double-precision output w.

  • "single" — Use this option to return a single-precision output w.

Data Types: char | string

Output Arguments

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Blackman-Harris window, returned as a column vector.

Algorithms

The equation for the symmetric four-term Blackman-Harris window of length N is

w(n)=a0a1cos(2πnN1)+a2cos(4πnN1)a3cos(6πnN1),0nN1

The equation for the periodic four-term Blackman-Harris window of length N is

w(n)=a0a1cos2πnN+a2cos4πnNa3cos6πnN,0nN1

The periodic window is N-periodic.

CoefficientValue
a00.35875
a10.48829
a20.14128
a30.01168

References

[1] harris, fredric j. “On the Use of Windows for Harmonic Analysis with the Discrete Fourier Transform.” Proceedings of the IEEE®. Vol. 66, January 1978, pp. 51–83.

Extended Capabilities

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C/C++ Code Generation
Generate C and C++ code using MATLAB® Coder™.

Version History

Introduced before R2006a

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