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sigwin.nuttallwin class

Package: sigwin

Construct Nuttall defined four-term Blackman-Harris window object

Description

    Note:   The use of sigwin.nuttallwin is not recommended. Use nuttallwin instead.

sigwin.nuttallwin creates a handle to a Nuttall defined four-term Blackman-Harris window object for use in spectral analysis and FIR filtering by the window method. Object methods enable workspace import and ASCII file export of the window values.

Construction

H = sigwin.nuttallwin returns a Nuttall defined four-term Blackman-Harris window object window object H of length 64.

H = sigwin.nuttallwin(Length) returns a Nuttall defined four-term Blackman-Harris window object H of length Length. Entering a positive noninteger value for Length rounds the length to the nearest integer. Entering a 1 for Length results in a window with a single value of 1. The SamplingFlag property defaults to 'symmetric'.

Properties

Length

Nuttall defined four-term Blackman-Harris window length. The window length must be a positive integer. Entering a positive noninteger value for Length rounds the length to the nearest integer. Entering a 1 for Length results in a window with a single value of 1.

SamplingFlag

The type of window returned as one of 'symmetric' or 'periodic'. The default is 'symmetric'. A symmetric window exhibits perfect symmetry between halves of the window. Setting the SamplingFlag property to 'periodic' results in a N-periodic window. The equations for the Nuttall defined 4–term Blackman-Harris window differ slightly based on the value of the SamplingFlag property. See Algorithms for details.

Methods

generateGenerates Nuttall defined four-term Blackman-Harris window
infoDisplay information about Nuttall defined four-term Blackman-Harris window object
winwriteSave Nuttall defined four-term Blackman-Harris window object values in ASCII file

Copy Semantics

Handle. To learn how copy semantics affect your use of the class, see Copying Objects (MATLAB) in the MATLAB® Programming Fundamentals documentation.

Examples

expand all

Generate two Nuttall-defined four-term Blackman-Harris windows:

  • The first window has N = 64 and is symmetric.

  • The second window has N = 63 and is periodic.

Display the two windows.

Hs = sigwin.nuttallwin(64);
Hp = sigwin.nuttallwin(63);
Hp.SamplingFlag = 'periodic';

wvt = wvtool(Hs,Hp);
legend(wvt.CurrentAxes,'Symmetric','Periodic')

Generate a symmetric Nuttall-defined four-term Blackman-Harris window with N = 16. Return the window values as a column vector. Write the coefficients to an ASCII file in the current directory. Show information about the window object. Display the window.

H = sigwin.nuttallwin(16);

win = generate(H)
win = 

    0.0004
    0.0048
    0.0306
    0.1105
    0.2778
    0.5292
    0.7983
    0.9755
    0.9755
    0.7983

winwrite(H,'nuttallwin_16');
wininfo = info(H)
wininfo = 4×26 char array
    'Nuttall Window            '
    '--------------            '
    'Length         : 16       '
    'Sampling Flag  : symmetric'
wvtool(H)

Algorithms

The following equation defines the symmetric Nuttall defined four-term Blackman-Harris window of length N.

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

The following equation defines the periodic Nuttall defined four-term Blackman-Harris window of length N.

w(n)=a0a1cos2πnN+a2cos4πnNa3cos6πnN,0nN1

The following table lists the coefficients:

CoefficientValue
a00.3635819
a10.4891775
a20.1365995
a30.0106411

References

Nuttall, A. H. "Some Windows with Very Good Sidelobe Behavior." IEEE® Transactions on Acoustics, Speech, and Signal Processing. Vol. 29, 1981, pp. 84–91.

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