/* -*- c++ -*- */
/*
* Copyright 2002,2007,2008,2012,2013 Free Software Foundation, Inc.
*
* This file is part of GNU Radio
*
* GNU Radio is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 3, or (at your option)
* any later version.
*
* GNU Radio is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with GNU Radio; see the file COPYING. If not, write to
* the Free Software Foundation, Inc., 51 Franklin Street,
* Boston, MA 02110-1301, USA.
*/
#ifndef INCLUDED_FFT_WINDOW_H
#define INCLUDED_FFT_WINDOW_H
#include <gnuradio/fft/api.h>
#include <vector>
#include <cmath>
#include <gnuradio/gr_complex.h>
namespace gr {
namespace fft {
class FFT_API window {
public:
enum win_type {
WIN_HAMMING = 0, //!< Hamming window; max attenuation 53 dB
WIN_HANN = 1, //!< Hann window; max attenuation 44 dB
WIN_BLACKMAN = 2, //!< Blackman window; max attenuation 74 dB
WIN_RECTANGULAR = 3, //!< Basic rectangular window; max attenuation 21 dB
WIN_KAISER = 4, //!< Kaiser window; max attenuation see window::max_attenuation
WIN_BLACKMAN_hARRIS = 5, //!< Blackman-harris window; max attenuation 92 dB
WIN_BLACKMAN_HARRIS = 5, //!< alias to WIN_BLACKMAN_hARRIS for capitalization consistency
WIN_BARTLETT = 6, //!< Barlett (triangular) window; max attenuation 26 dB
WIN_FLATTOP = 7, //!< flat top window; useful in FFTs; max attenuation 93 dB
};
/*!
* \brief Given a window::win_type, this tells you the maximum
* attenuation you can expect.
*
* \details
* 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.
*
* \param type The window::win_type enumeration of the window type.
* \param beta Beta value only used for the Kaiser window.
*/
static double max_attenuation(win_type type, double beta=6.76);
/*!
* \brief Helper function to build cosine-based windows. 3-coefficient version.
*/
static std::vector<float> coswindow(int ntaps, float c0, float c1, float c2);
/*!
* \brief Helper function to build cosine-based windows. 4-coefficient version.
*/
static std::vector<float> coswindow(int ntaps, float c0, float c1, float c2, float c3);
/*!
* \brief Helper function to build cosine-based windows. 5-coefficient version.
*/
static std::vector<float> coswindow(int ntaps, float c0, float c1, float c2, float c3, float c4);
/*!
* \brief Build a rectangular window.
*
* Taps are flat across the window.
*
* \param ntaps Number of coefficients in the window.
*/
static std::vector<float> rectangular(int ntaps);
/*!
* \brief Build a Hamming window.
*
* See:
* <pre>
* A. V. Oppenheim and R. W. Schafer, "Discrete-Time
* Signal Processing," Upper Saddle River, N.J.: Prentice
* Hall, 2010, pp. 535-538.
* </pre>
*
* \param ntaps Number of coefficients in the window.
*/
static std::vector<float> hamming(int ntaps);
/*!
* \brief Build a Hann window (sometimes known as Hanning).
*
* See:
* <pre>
* A. V. Oppenheim and R. W. Schafer, "Discrete-Time
* Signal Processing," Upper Saddle River, N.J.: Prentice
* Hall, 2010, pp. 535-538.
* </pre>
*
* \param ntaps Number of coefficients in the window.
*/
static std::vector<float> hann(int ntaps);
/*!
* \brief Alias to build a Hann window.
*
* \param ntaps Number of coefficients in the window.
*/
static std::vector<float> hanning(int ntaps);
/*!
* \brief Build an exact Blackman window.
*
* See:
* <pre>
* A. V. Oppenheim and R. W. Schafer, "Discrete-Time
* Signal Processing," Upper Saddle River, N.J.: Prentice
* Hall, 2010, pp. 535-538.
* </pre>
*
* \param ntaps Number of coefficients in the window.
*/
static std::vector<float> blackman(int ntaps);
/*!
* \brief Build Blackman window, variation 1.
*/
static std::vector<float> blackman2(int ntaps);
/*!
* \brief Build Blackman window, variation 2.
*/
static std::vector<float> blackman3(int ntaps);
/*!
* \brief Build Blackman window, variation 3.
*/
static std::vector<float> blackman4(int ntaps);
/*!
* \brief Build a Blackman-harris window with a given attenuation.
*
* <pre>
* 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.
* </pre>
*
* \param ntaps Number of coefficients in the window.
* \param atten Attenuation factor. Must be [61, 67, 74, 92].
* See the above paper for details.
*/
static std::vector<float> blackman_harris(int ntaps, int atten=92);
/*!
* Alias to gr::fft::window::blakcman_harris.
*/
static std::vector<float> blackmanharris(int ntaps, int atten=92);
/*!
* \brief Build a Nuttall (or Blackman-Nuttall) window.
*
* See: http://en.wikipedia.org/wiki/Window_function#Blackman.E2.80.93Nuttall_window
*
* \param ntaps Number of coefficients in the window.
*/
static std::vector<float> nuttall(int ntaps);
/*!
* Deprecated: use nuttall window instead.
*/
static std::vector<float> nuttal(int ntaps);
/*!
* \brief Alias to the Nuttall window.
*
* \param ntaps Number of coefficients in the window.
*/
static std::vector<float> blackman_nuttall(int ntaps);
/*!
* Deprecated: use blackman_nuttall window instead.
*/
static std::vector<float> blackman_nuttal(int ntaps);
/*!
* \brief Build a Nuttall continuous first derivative window.
*
* See: http://en.wikipedia.org/wiki/Window_function#Nuttall_window.2C_continuous_first_derivative
*
* \param ntaps Number of coefficients in the window.
*/
static std::vector<float> nuttall_cfd(int ntaps);
/*!
* Deprecated: use nuttall_cfd window instead.
*/
static std::vector<float> nuttal_cfd(int ntaps);
/*!
* \brief Build a flat top window.
*
* See: http://en.wikipedia.org/wiki/Window_function#Flat_top_window
*
* \param ntaps Number of coefficients in the window.
*/
static std::vector<float> flattop(int ntaps);
/*!
* \brief Build a Kaiser window with a given beta.
*
* See:
* <pre>
* A. V. Oppenheim and R. W. Schafer, "Discrete-Time
* Signal Processing," Upper Saddle River, N.J.: Prentice
* Hall, 2010, pp. 541-545.
* </pre>
*
* \param ntaps Number of coefficients in the window.
* \param beta Shaping parameter of the window. See the
* discussion in Oppenheim and Schafer.
*/
static std::vector<float> kaiser(int ntaps, double beta);
/*!
* \brief Build a Barlett (triangular) window.
*
* See:
* <pre>
* A. V. Oppenheim and R. W. Schafer, "Discrete-Time
* Signal Processing," Upper Saddle River, N.J.: Prentice
* Hall, 2010, pp. 535-538.
* </pre>
*
* \param ntaps Number of coefficients in the window.
*/
static std::vector<float> bartlett(int ntaps);
static std::vector<float> welch(int ntaps);
/*!
* \brief Build a Parzen (or de la Valle-Poussin) window.
*
* See:
* <pre>
* A. D. Poularikas, "Handbook of Formulas and Tables for
* Signal Processing," Springer, Oct 28, 1998
* </pre>
*
* \param ntaps Number of coefficients in the window.
*/
static std::vector<float> parzen(int ntaps);
/*!
* \brief Build an exponential window with a given decay.
*
* See: http://en.wikipedia.org/wiki/Window_function#Exponential_or_Poisson_window
*
* \param ntaps Number of coefficients in the window.
* \param d Decay of \p d dB over half the window length.
*/
static std::vector<float> exponential(int ntaps, double d);
/*!
* \brief Build a Riemann window.
*
* See:
* <pre>
* A. D. Poularikas, "Handbook of Formulas and Tables for
* Signal Processing," Springer, Oct 28, 1998
* </pre>
*
* \param ntaps Number of coefficients in the window.
*/
static std::vector<float> riemann(int ntaps);
/*!
* \brief Build a window using gr::fft::win_type to index the
* type of window desired.
*
* \param type a gr::fft::win_type index for the type of window.
* \param ntaps Number of coefficients in the window.
* \param beta Used only for building Kaiser windows.
*/
static std::vector<float> build(win_type type, int ntaps, double beta);
};
} /* namespace fft */
} /* namespace gr */
#endif /* INCLUDED_FFT_WINDOW_H */