gr::fft::window Class Reference

#include <gnuradio/fft/window.h>

Public Types
enum	win_type {   WIN_HAMMING = 0, WIN_HANN = 1, WIN_BLACKMAN = 2, WIN_RECTANGULAR = 3,   WIN_KAISER = 4, WIN_BLACKMAN_hARRIS = 5, WIN_BLACKMAN_HARRIS = 5, WIN_BARTLETT = 6,   WIN_FLATTOP = 7 }

Static Public Member Functions
static double	max_attenuation (win_type type, double beta=6.76)
	Given a window::win_type, this tells you the maximum attenuation you can expect. More...
static std::vector< float >	coswindow (int ntaps, float c0, float c1, float c2)
	Helper function to build cosine-based windows. 3-coefficient version. More...
static std::vector< float >	coswindow (int ntaps, float c0, float c1, float c2, float c3)
	Helper function to build cosine-based windows. 4-coefficient version. More...
static std::vector< float >	coswindow (int ntaps, float c0, float c1, float c2, float c3, float c4)
	Helper function to build cosine-based windows. 5-coefficient version. More...
static std::vector< float >	rectangular (int ntaps)
	Build a rectangular window. More...
static std::vector< float >	hamming (int ntaps)
	Build a Hamming window. More...
static std::vector< float >	hann (int ntaps)
	Build a Hann window (sometimes known as Hanning). More...
static std::vector< float >	hanning (int ntaps)
	Alias to build a Hann window. More...
static std::vector< float >	blackman (int ntaps)
	Build an exact Blackman window. More...
static std::vector< float >	blackman2 (int ntaps)
	Build Blackman window, variation 1. More...
static std::vector< float >	blackman3 (int ntaps)
	Build Blackman window, variation 2. More...
static std::vector< float >	blackman4 (int ntaps)
	Build Blackman window, variation 3. More...
static std::vector< float >	blackman_harris (int ntaps, int atten=92)
	Build a Blackman-harris window with a given attenuation. More...
static std::vector< float >	blackmanharris (int ntaps, int atten=92)
static std::vector< float >	nuttal (int ntaps)
	Build a Nuttal (or Blackman-Nuttal) window. More...
static std::vector< float >	blackman_nuttal (int ntaps)
	Alias to the Nuttal window. More...
static std::vector< float >	nuttal_cfd (int ntaps)
	Build a Nuttal continuous first derivative window. More...
static std::vector< float >	flattop (int ntaps)
	Build a Nuttal continuous first derivative window. More...
static std::vector< float >	kaiser (int ntaps, double beta)
	Build a Kaiser window with a given beta. More...
static std::vector< float >	bartlett (int ntaps)
	Build a Barlett (triangular) window. More...
static std::vector< float >	welch (int ntaps)
static std::vector< float >	parzen (int ntaps)
	Build a Parzen (or de la Valle-Poussin) window. More...
static std::vector< float >	exponential (int ntaps, double d)
	Build an exponential window with a given decay. More...
static std::vector< float >	riemann (int ntaps)
	Build a Riemann window. More...
static std::vector< float >	build (win_type type, int ntaps, double beta)
	Build a window using gr::fft::win_type to index the type of window desired. More...

Member Enumeration Documentation

enum gr::fft::window::win_type

Enumerator
WIN_HAMMING	Hamming window; max attenuation 53 dB.
WIN_HANN	Hann window; max attenuation 44 dB.
WIN_BLACKMAN	Blackman window; max attenuation 74 dB.
WIN_RECTANGULAR	Basic rectangular window; max attenuation 21 dB.
WIN_KAISER	Kaiser window; max attenuation see window::max_attenuation.
WIN_BLACKMAN_hARRIS	Blackman-harris window; max attenuation 92 dB.
WIN_BLACKMAN_HARRIS	alias to WIN_BLACKMAN_hARRIS for capitalization consistency
WIN_BARTLETT	Barlett (triangular) window; max attenuation 26 dB.
WIN_FLATTOP	flat top window; useful in FFTs; max attenuation 93 dB

Member Function Documentation

static std::vector<float> gr::fft::window::bartlett ( int  ntaps )

static

Build a Barlett (triangular) window.

See:

  A. V. Oppenheim and R. W. Schafer, "Discrete-Time
  Signal Processing," Upper Saddle River, N.J.: Prentice
  Hall, 2010, pp. 535-538.

Parameters

ntaps

Number of coefficients in the window.

static std::vector<float> gr::fft::window::blackman ( int  ntaps )

static

Build an exact Blackman window.

See:

  A. V. Oppenheim and R. W. Schafer, "Discrete-Time
  Signal Processing," Upper Saddle River, N.J.: Prentice
  Hall, 2010, pp. 535-538.

Parameters

ntaps

Number of coefficients in the window.

static std::vector<float> gr::fft::window::blackman2 ( int  ntaps )

static

Build Blackman window, variation 1.

static std::vector<float> gr::fft::window::blackman3 ( int  ntaps )

static

Build Blackman window, variation 2.

static std::vector<float> gr::fft::window::blackman4 ( int  ntaps )

static

Build Blackman window, variation 3.

static std::vector<float> gr::fft::window::blackman_harris ( int  ntaps, int  atten = 92  )

static

Build a Blackman-harris window with a given attenuation.

    f. j. harris, "On the use of windows for harmonic analysis
    with the discrete Fourier transforms," Proc. IEEE, Vol. 66,
    ppg. 51-83, Jan. 1978.

Parameters

ntaps	Number of coefficients in the window.
atten	Attenuation factor. Must be [61, 67, 74, 92]. See the above paper for details.

static std::vector<float> gr::fft::window::blackman_nuttal ( int  ntaps )

static

Alias to the Nuttal window.

Parameters

ntaps

Number of coefficients in the window.

static std::vector<float> gr::fft::window::blackmanharris ( int  ntaps, int  atten = 92  )

static

Alias to gr::fft::window::blakcman_harris.

static std::vector<float> gr::fft::window::build ( win_type  type, int  ntaps, double  beta  )

static

Build a window using gr::fft::win_type to index the type of window desired.

Parameters

type	a gr::fft::win_type index for the type of window.
ntaps	Number of coefficients in the window.
beta	Used only for building Kaiser windows.

static std::vector<float> gr::fft::window::coswindow ( int  ntaps, float  c0, float  c1, float  c2  )

static

Helper function to build cosine-based windows. 3-coefficient version.

static std::vector<float> gr::fft::window::coswindow ( int  ntaps, float  c0, float  c1, float  c2, float  c3  )

static

Helper function to build cosine-based windows. 4-coefficient version.

static std::vector<float> gr::fft::window::coswindow ( int  ntaps, float  c0, float  c1, float  c2, float  c3, float  c4  )

static

Helper function to build cosine-based windows. 5-coefficient version.

static std::vector<float> gr::fft::window::exponential ( int  ntaps, double  d  )

static

Build an exponential window with a given decay.

See: http://en.wikipedia.org/wiki/Window_function#Exponential_or_Poisson_window

Parameters

ntaps	Number of coefficients in the window.
d	Decay of d dB over half the window length.

static std::vector<float> gr::fft::window::flattop ( int  ntaps )

static

Build a Nuttal continuous first derivative window.

See: http://en.wikipedia.org/wiki/Window_function#Flat_top_window

Parameters

ntaps

Number of coefficients in the window.

static std::vector<float> gr::fft::window::hamming ( int  ntaps )

static

Build a Hamming window.

See:

  A. V. Oppenheim and R. W. Schafer, "Discrete-Time
  Signal Processing," Upper Saddle River, N.J.: Prentice
  Hall, 2010, pp. 535-538.

Parameters

ntaps

Number of coefficients in the window.

static std::vector<float> gr::fft::window::hann ( int  ntaps )

static

Build a Hann window (sometimes known as Hanning).

See:

  A. V. Oppenheim and R. W. Schafer, "Discrete-Time
  Signal Processing," Upper Saddle River, N.J.: Prentice
  Hall, 2010, pp. 535-538.

Parameters

ntaps

Number of coefficients in the window.

static std::vector<float> gr::fft::window::hanning ( int  ntaps )

static

Alias to build a Hann window.

Parameters

ntaps

Number of coefficients in the window.

static std::vector<float> gr::fft::window::kaiser ( int  ntaps, double  beta  )

static

Build a Kaiser window with a given beta.

See:

    A. V. Oppenheim and R. W. Schafer, "Discrete-Time
    Signal Processing," Upper Saddle River, N.J.: Prentice
    Hall, 2010, pp. 541-545.

Parameters

ntaps	Number of coefficients in the window.
beta	Shaping parameter of the window. See the discussion in Oppenheim and Schafer.

static double gr::fft::window::max_attenuation ( win_type  type, double  beta = 6.76  )

static

Given a window::win_type, this tells you the maximum attenuation you can expect.

For most windows, this is a set value. For the Kaiser window, the attenuation is based on the value of beta. The actual relationship is a piece-wise exponential relationship to calculate beta from the desired attenuation and can be found on page 542 of Oppenheim and Schafer (Discrete-Time Signal Processing, 3rd edition). To simplify this function to solve for A given beta, we use a linear form that is exact for attenuation >= 50 dB.

For an attenuation of 50 dB, beta = 4.55.

For an attenuation of 70 dB, beta = 6.76.

Parameters

type	The window::win_type enumeration of the window type.
beta	Beta value only used for the Kaiser window.

static std::vector<float> gr::fft::window::nuttal ( int  ntaps )

static

Build a Nuttal (or Blackman-Nuttal) window.

See: http://en.wikipedia.org/wiki/Window_function#Blackman.E2.80.93Nuttall_window

Parameters

ntaps

Number of coefficients in the window.

static std::vector<float> gr::fft::window::nuttal_cfd ( int  ntaps )

static

Build a Nuttal continuous first derivative window.

See: http://en.wikipedia.org/wiki/Window_function#Nuttall_window.2C_continuous_first_derivative

Parameters

ntaps

Number of coefficients in the window.

static std::vector<float> gr::fft::window::parzen ( int  ntaps )

static

Build a Parzen (or de la Valle-Poussin) window.

See:

  A. D. Poularikas, "Handbook of Formulas and Tables for
  Signal Processing," Springer, Oct 28, 1998

Parameters

ntaps

Number of coefficients in the window.

static std::vector<float> gr::fft::window::rectangular ( int  ntaps )

static

Build a rectangular window.

Taps are flat across the window.

Parameters

ntaps

Number of coefficients in the window.

static std::vector<float> gr::fft::window::riemann ( int  ntaps )

static

Build a Riemann window.

See:

  A. D. Poularikas, "Handbook of Formulas and Tables for
  Signal Processing," Springer, Oct 28, 1998

Parameters

ntaps

Number of coefficients in the window.

static std::vector<float> gr::fft::window::welch ( int  ntaps )

static

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The documentation for this class was generated from the following file:

• window.h