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libdspl-2.0/dspl/src/filter_design/fir_linphase.c

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New project structure for filter design algorithms Changes to be committed: deleted: dspl/src/conv.c new file: dspl/src/convolution.c new file: dspl/src/convolution/conv.c new file: dspl/src/convolution/conv_cmplx.c new file: dspl/src/convolution/conv_fft.c new file: dspl/src/convolution/conv_fft_cmplx.c new file: dspl/src/convolution/filter_iir.c deleted: dspl/src/ellipj.c deleted: dspl/src/filter_an.c deleted: dspl/src/filter_ap.c new file: dspl/src/filter_design.c new file: dspl/src/filter_design/bilinear.c new file: dspl/src/filter_design/butter_ap.c new file: dspl/src/filter_design/butter_ap_zp.c new file: dspl/src/filter_design/cheby1_ap.c new file: dspl/src/filter_design/cheby1_ap_zp.c new file: dspl/src/filter_design/cheby2_ap.c new file: dspl/src/filter_design/cheby2_ap_wp1.c new file: dspl/src/filter_design/cheby2_ap_zp.c new file: dspl/src/filter_design/ellip_ap.c new file: dspl/src/filter_design/ellip_ap_zp.c new file: dspl/src/filter_design/filter_freq_resp.c new file: dspl/src/filter_design/filter_ws1.c new file: dspl/src/filter_design/filter_zp2ab.c renamed: dspl/src/filter_fir.c -> dspl/src/filter_design/fir_linphase.c new file: dspl/src/filter_design/fir_linphase_lpf.c new file: dspl/src/filter_design/freqs.c new file: dspl/src/filter_design/freqs2time.c new file: dspl/src/filter_design/freqs_cmplx.c new file: dspl/src/filter_design/freqz.c new file: dspl/src/filter_design/group_delay.c renamed: dspl/src/filter_iir.c -> dspl/src/filter_design/iir.c new file: dspl/src/filter_design/iir_ap.c new file: dspl/src/filter_design/low2bp.c new file: dspl/src/filter_design/low2bs.c new file: dspl/src/filter_design/low2high.c new file: dspl/src/filter_design/low2low.c new file: dspl/src/filter_design/phase_delay.c new file: dspl/src/filter_design/ratcompos.c deleted: dspl/src/filter_ft.c new file: dspl/src/math_ellipj.c new file: dspl/src/math_ellipj/ellip_acd.c new file: dspl/src/math_ellipj/ellip_acd_cmplx.c new file: dspl/src/math_ellipj/ellip_asn.c new file: dspl/src/math_ellipj/ellip_asn_cmplx.c new file: dspl/src/math_ellipj/ellip_cd.c new file: dspl/src/math_ellipj/ellip_cd_cmplx.c new file: dspl/src/math_ellipj/ellip_landen.c new file: dspl/src/math_ellipj/ellip_modulareq.c new file: dspl/src/math_ellipj/ellip_rat.c new file: dspl/src/math_ellipj/ellip_sn.c new file: dspl/src/math_ellipj/ellip_sn_cmplx.c new file: dspl/src/types.c renamed: dspl/src/complex.c -> dspl/src/types/cmplx2re.c new file: dspl/src/types/re2cmplx.c new file: dspl/src/unwrap.c
2021-12-29 13:31:00 +00:00
/*
* Copyright (c) 2015-2019 Sergey Bakhurin
* Digital Signal Processing Library [http://dsplib.org]
*
* This file is part of libdspl-2.0.
*
* is free software: you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* DSPL 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 Lesser General Public License
* along with Foobar. If not, see <http://www.gnu.org/licenses/>.
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "dspl.h"
#include "dspl_internal.h"
#ifdef DOXYGEN_ENGLISH
/*! ****************************************************************************
\ingroup FIR_FILTER_DESIGN_GROUP
\fn int DSPL_API fir_linphase(int ord, double w0, double w1, int filter_type,
int win_type, double win_param, double* h)
\brief
Function calculates linear-phase FIR filter coefficients by window method
FIR filter transfer function is
\f[
H(z) = \sum_{n = 0}^{ord} h_n z^{-n}.
\f]
\param[in] ord
Filter order. \n
Number of FIR filter coefficients is `ord+1`. \n
\n
\param[in] w0
Normalized cutoff frequency for lowpass and highpass filter,
or left cutoff frequency for bandpass or bandstop filter. \n
\n
\param[in] w1
Right normalized cutoff frequency for bandpass or bandstop filter. \n
This parameter is ignored for lowpass or highpass filters. \n
Frequecny `w1` must be higher than `w0`. \n
\n
\param[in] filter_type
Filter type. \n
This parameter can be one of follow: \n
\verbatim
DSPL_FILTER_LPF - lowpass filter;
DSPL_FILTER_HPF - highpass filter;
DSPL_FILTER_BPASS - bandpass filter;
DSPL_FILTER_BSTOP - bandstop filter.
\endverbatim
\n
\n
\param [in] win_type
Window function type. \n
This parameter can be one of follow: \n
\verbatim
-------------------------------------------------------------------------
win_type | Description
-----------------------------|-------------------------------------------
DSPL_WIN_BARTLETT | Nonparametric Bartlett window
-----------------------------|-------------------------------------------
DSPL_WIN_BARTLETT_HANN | Nonparametric Bartlett-Hann window
-----------------------------|-------------------------------------------
DSPL_WIN_BLACKMAN | Nonparametric Blackman window
-----------------------------|-------------------------------------------
DSPL_WIN_BLACKMAN_HARRIS | Nonparametric Blackman-Harris window
-----------------------------|-------------------------------------------
DSPL_WIN_BLACKMAN_NUTTALL | Nonparametric Blackman-Nuttall
-----------------------------|-------------------------------------------
DSPL_WIN_CHEBY | Parametric Dolph-Chebyshev window.
| Parametr `win_param` sets sidelobe attenuation
| level in dB.
-----------------------------|-------------------------------------------
DSPL_WIN_COS | Nonparametric Cosine window
-----------------------------|-------------------------------------------
DSPL_WIN_FLAT_TOP | Nonparametric maxflat window
-----------------------------|-------------------------------------------
DSPL_WIN_GAUSSIAN | Nonparametric Gauss window
-----------------------------|-------------------------------------------
DSPL_WIN_HAMMING | Nonparametric Hamming window
-----------------------------|-------------------------------------------
DSPL_WIN_HANN | Nonparametric Hann window
-----------------------------|-------------------------------------------
DSPL_WIN_KAISER | Parametric Kaiser window
-----------------------------|-------------------------------------------
DSPL_WIN_LANCZOS | Nonparametric Lanczos window
-----------------------------|-------------------------------------------
DSPL_WIN_NUTTALL | Nonparametric Nuttall window
-----------------------------|-------------------------------------------
DSPL_WIN_RECT | Nonparametric rectangular window
-------------------------------------------------------------------------
\endverbatim
\n
\n
\param [in] win_param
Parameter value for parametric windows. \n
This parameter is used for parametric windows only and is ignored for
nonparametric windows. \n
\n
\param[out] h
Pointer to the linear-phase FIR filter coefficients vector. \n
Vector size is `[ord+1 x 1]`. \n
Memoru must be allocated. \n
\n
\note
Only symmetric windows can achieve linear-phase FIR filter. \n \n
Bandstop filter type (`filter_type = DSPL_FILTER_BSTOP`) requires
only even filter order `ord`.
If `filter_type = DSPL_FILTER_BSTOP` and `ord` is odd then function
returns `ERROR_FILTER_ORD` code.
\n
\return
`RES_OK` if filter coefficients is calculated successfully. \n
Else \ref ERROR_CODE_GROUP "code error".
Example:
\include fir_linphase_test.c
This function calculates coeffictiens of lowpass, highpass, bandpass
and bandstop linear-phase FIR filters by using different kind of windows.
Also program calculates filter magnitudes and plots. \n
\image html fir_linphase_test.png
\author Sergey Bakhurin www.dsplib.org
***************************************************************************** */
#endif
#ifdef DOXYGEN_RUSSIAN
/*! ****************************************************************************
\ingroup FIR_FILTER_DESIGN_GROUP
\fn int DSPL_API fir_linphase(int ord, double w0, double w1, int filter_type,
int win_type, double win_param, double* h)
\brief
Расчет коэффициентов линейно-фазового КИХ-фильтра
методом оконного взвешивания.
Функция рассчитывает коэффициенты передаточной характеристики
\f[
H(z) = \sum_{n = 0}^{ord} h_n z^{-n}
\f]
цифрового линейно-фазового КИХ-фильтра фильтра.
\param[in] ord
Порядок фильтра (количество элементов задержки). \n
Количество коэффициентов фильтра равно `ord+1`. \n
\n
\param[in] w0
Нормированная частота среза ФНЧ или ФВЧ,
или левая частота среза для полосового и режекторного фильтра. \n
\n
\param[in] w1
Правая частота среза полосового и режекторного фильтра. \n
Данный параметр игнорируется для ФНЧ и ФВЧ. \n
Частота `w1` должна быть больше `w0`. \n
\n
\param[in] filter_type
Тип фильтра. \n
Данный параметр определяет тип фильтра
и может принимать одно из значений: \n
\verbatim
DSPL_FILTER_LPF - фильтр нижних частот;
DSPL_FILTER_HPF - фильтр верхних частот;
DSPL_FILTER_BPASS - полосовой фильтр;
DSPL_FILTER_BSTOP - режекторный фильтр.
\endverbatim
\n
\n
\param [in] win_type
Тип оконной функции. \n
Может принимать одно из следующих значений: \n
\verbatim
-------------------------------------------------------------------------
Значение win_type | Описание
-----------------------------|-------------------------------------------
DSPL_WIN_BARTLETT | Непараметрическое окно Бартлетта
-----------------------------|-------------------------------------------
DSPL_WIN_BARTLETT_HANN | Непараметрическое окно Бартлетта-Ханна
-----------------------------|-------------------------------------------
DSPL_WIN_BLACKMAN | Непараметрическое окно Блэкмана
-----------------------------|-------------------------------------------
DSPL_WIN_BLACKMAN_HARRIS | Непараметрическое окно Блэкмана-Харриса
-----------------------------|-------------------------------------------
DSPL_WIN_BLACKMAN_NUTTALL | Непараметрическое окно Блэкмана-Натталла
-----------------------------|-------------------------------------------
DSPL_WIN_CHEBY | Параметрическое окно Дольф-Чебышева.
| Параметр win_param задает уровень
| боковых лепестков в дБ.
-----------------------------|-------------------------------------------
DSPL_WIN_COS | Непараметрическое косинус-окно
-----------------------------|-------------------------------------------
DSPL_WIN_FLAT_TOP | Непараметрическое окно с максимально
| плоской вершиной
-----------------------------|-------------------------------------------
DSPL_WIN_GAUSSIAN | Параметрическое окно Гаусса
-----------------------------|-------------------------------------------
DSPL_WIN_HAMMING | Непараметрическое окно Хемминга
-----------------------------|-------------------------------------------
DSPL_WIN_HANN | Непараметрическое окно Ханна
-----------------------------|-------------------------------------------
DSPL_WIN_KAISER | Параметрическое окно Кайзера
-----------------------------|-------------------------------------------
DSPL_WIN_LANCZOS | Непараметрическое окно Ланкзоса
-----------------------------|-------------------------------------------
DSPL_WIN_NUTTALL | Непараметрическое окно Натталла
-----------------------------|-------------------------------------------
DSPL_WIN_RECT | Непараметрическое прямоугольное окно
-------------------------------------------------------------------------
\endverbatim
\n
\n
\param [in] win_param
Параметр окна. \n
Данный параметр применяется только для параметрических оконных функций. \n
Для непараметрических окон игнорируется. \n
\n
\param[out] h
Указатель на вектор коэффициентов линейно-фазового КИХ-фильтра \f$H(z)\f$. \n
Размер вектора `[ord+1 x 1]`. \n
Память должна быть выделена. \n
\n
\note
Для соблюдения условия линейной ФЧХ используются
только симметричные окна. \n \n
Расчет режекторного линейно-фазового КИХ-фильтра
(если `filter_type = DSPL_FILTER_BSTOP`) производится только
для фильтров чётного порядка `ord`.
В случае нечетного порядка `ord` функция вернет код ошибки `ERROR_FILTER_ORD`.
\n
\return
`RES_OK`
Фильтр рассчитан успешно. \n
В противном случае \ref ERROR_CODE_GROUP "код ошибки". \n
Пример использования функции:
\include fir_linphase_test.c
Программа расчитывает коэффициенты и АЧХ линейно-фазовых КИХ-фильтров нижних,
верхних частот, полосовых и режекторных с применением различных весовых окон:
прямоугольное, Хемминга, Блэкмана и Блэкмана-Харриса. \n
Полученные АЧХ выводятся на график
\image html fir_linphase_test.png
\author Бахурин Сергей www.dsplib.org
***************************************************************************** */
#endif
int DSPL_API fir_linphase(int ord, double w0, double w1, int filter_type,
int win_type, double win_param, double* h)
{
int n, err;
double wc, b, del;
if(ord<1)
return ERROR_FILTER_ORD;
if(w0 <= 0.0)
return ERROR_FILTER_WP;
if(!h)
return ERROR_PTR;
switch(filter_type & DSPL_FILTER_TYPE_MASK)
{
/* Lowpass FIR coefficients calculation */
case DSPL_FILTER_LPF:
err = fir_linphase_lpf(ord, w0, win_type, win_param, h);
break;
/* Highpass FIR coefficients calculation */
case DSPL_FILTER_HPF:
err = fir_linphase_lpf(ord, 1.0-w0, win_type, win_param, h);
if(err == RES_OK)
{
/* LPF filter frequency inversion */
for(n = 0; n < ord+1; n+=2)
h[n] = -h[n];
}
break;
/* Bandpass FIR coefficients calculation */
case DSPL_FILTER_BPASS:
if(w1 < w0)
{
err = ERROR_FILTER_WS;
break;
}
wc = (w0 + w1) * 0.5; /* central frequency */
b = w1 - w0; /* bandwidth */
err = fir_linphase_lpf(ord, b*0.5, win_type, win_param, h);
if(err == RES_OK)
{
/* LPF frequency shifting to the central frequency */
del = 0.5 * (double)ord;
for(n = 0; n < ord+1; n++)
h[n] *= 2.0 * cos(M_PI * ((double)n - del) * wc);
}
break;
/* BandStop FIR coefficients calculation */
/* ATTENTION! Bandstop filter must be even order only! */
case DSPL_FILTER_BSTOP:
{
double *h0 = NULL;
/* check filter order. Return error if order is odd. */
if(ord%2)
return ERROR_FILTER_ORD;
/* check frequency (w1 must be higher than w0) */
if(w1 < w0)
{
err = ERROR_FILTER_WS;
break;
}
/* temp coeff vector */
h0 = (double*)malloc((ord+1) * sizeof(double));
/* calculate LPF */
err = fir_linphase(ord, w0, 0.0, DSPL_FILTER_LPF,
win_type, win_param, h0);
if(err!=RES_OK)
{
free(h0);
return err;
}
/* calculate HPF */
err = fir_linphase(ord, w1, 0.0, DSPL_FILTER_HPF,
win_type, win_param, h);
if(err==RES_OK)
{
/* Bandstop filter is sum of lowpass and highpass filters */
for(n = 0; n < ord+1; n++)
h[n] += h0[n];
}
free(h0);
break;
}
default:
err = ERROR_FILTER_FT;
}
return err;
}