2018-04-02 20:48:53 +00:00
|
|
|
|
/*
|
2019-01-09 20:22:17 +00:00
|
|
|
|
* Copyright (c) 2015-2019 Sergey Bakhurin
|
2018-04-02 20:48:53 +00:00
|
|
|
|
* Digital Signal Processing Library [http://dsplib.org]
|
|
|
|
|
*
|
|
|
|
|
* This file is part of libdspl-2.0.
|
2018-10-24 17:39:51 +00:00
|
|
|
|
*
|
2018-04-02 20:48:53 +00:00
|
|
|
|
* is free software: you can redistribute it and/or modify
|
2020-07-17 18:09:28 +00:00
|
|
|
|
* it under the terms of the GNU Lesser General Public License as published by
|
2018-04-02 20:48:53 +00:00
|
|
|
|
* 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
|
2020-07-17 18:09:28 +00:00
|
|
|
|
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
2018-04-02 20:48:53 +00:00
|
|
|
|
* GNU General Public License for more details.
|
|
|
|
|
*
|
|
|
|
|
* You should have received a copy of the GNU Lesser General Public License
|
2020-07-17 18:09:28 +00:00
|
|
|
|
* along with Foobar. If not, see <http://www.gnu.org/licenses/>.
|
2018-04-02 20:48:53 +00:00
|
|
|
|
*/
|
|
|
|
|
|
|
|
|
|
#include <stdio.h>
|
|
|
|
|
#include <stdlib.h>
|
|
|
|
|
#include <string.h>
|
|
|
|
|
#include "dspl.h"
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
2020-07-23 18:55:02 +00:00
|
|
|
|
#ifdef DOXYGEN_ENGLISH
|
|
|
|
|
/*! ****************************************************************************
|
|
|
|
|
\ingroup IIR_FILTER_DESIGN_GROUP
|
|
|
|
|
\fn int butter_ap(double Rp, int ord, double* b, double* a)
|
|
|
|
|
|
|
|
|
|
\brief
|
|
|
|
|
Function calculates the transfer function \f$ H(s) \f$ coefficients of
|
|
|
|
|
analog normalized lowpass Butterworth filter.
|
|
|
|
|
|
|
|
|
|
Analog normalized lowpass filter magnitude ripple equals \f$ -R_p \f$ dB
|
|
|
|
|
for angular frequency \f$ \omega \f$ from 0 to 1 rad/s.
|
|
|
|
|
|
|
|
|
|
\param[in] Rp
|
|
|
|
|
Magnitude ripple in passband (dB). \n
|
|
|
|
|
This parameter sets maximum filter distortion from 0 to 1 rad/s frequency. \n
|
|
|
|
|
Parameter must be positive. \n
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
\param[in] ord
|
|
|
|
|
Filter order. \n
|
|
|
|
|
Filter coefficients number equals `ord+1` for numerator and denominator
|
|
|
|
|
of transfer function \f$ H(s) \f$ \n
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
\param[out] b
|
|
|
|
|
Pointer to the vector of transfer function \f$H(s)\f$
|
|
|
|
|
numerator coefficient. \n
|
|
|
|
|
Vector size is `[ord+1 x 1]`. \n
|
|
|
|
|
Memory must be allocated. \n
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
\param[out] a
|
|
|
|
|
Pointer to the vector of transfer function \f$H(s)\f$
|
|
|
|
|
denominator coefficient. \n
|
|
|
|
|
Vector size is `[ord+1 x 1]`. \n
|
|
|
|
|
Memory must be allocated. \n
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
\return
|
|
|
|
|
`RES_OK` if filter coefficients is calculated successfully. \n
|
|
|
|
|
Else \ref ERROR_CODE_GROUP "code error".
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
Example:
|
|
|
|
|
|
|
|
|
|
\include butter_ap_test.c
|
|
|
|
|
|
|
|
|
|
Result:
|
|
|
|
|
|
|
|
|
|
\verbatim
|
|
|
|
|
b[ 0] = 1.965 a[ 0] = 1.965
|
|
|
|
|
b[ 1] = 0.000 a[ 1] = 3.138
|
|
|
|
|
b[ 2] = 0.000 a[ 2] = 2.505
|
|
|
|
|
b[ 3] = 0.000 a[ 3] = 1.000
|
|
|
|
|
\endverbatim
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
In `dat` folder will be created 3 files: \n
|
|
|
|
|
|
|
|
|
|
\verbatim
|
|
|
|
|
butter_ap_test_mag.txt magnitude
|
|
|
|
|
butter_ap_test_phi.txt phase response
|
|
|
|
|
butter_ap_test_tau.txt group delay
|
|
|
|
|
\endverbatim
|
|
|
|
|
|
|
|
|
|
In addition, GNUPLOT will build the following graphs from data stored in files:
|
|
|
|
|
|
|
|
|
|
\image html butter_ap_test.png
|
|
|
|
|
|
|
|
|
|
\author Sergey Bakhurin www.dsplib.org
|
|
|
|
|
***************************************************************************** */
|
|
|
|
|
#endif
|
|
|
|
|
#ifdef DOXYGEN_RUSSIAN
|
|
|
|
|
/*! ****************************************************************************
|
|
|
|
|
\ingroup IIR_FILTER_DESIGN_GROUP
|
|
|
|
|
\fn int butter_ap(double Rp, int ord, double* b, double* a)
|
|
|
|
|
|
|
|
|
|
\brief
|
|
|
|
|
Расчет передаточной характеристики \f$ H(s) \f$ аналогового
|
|
|
|
|
нормированного ФНЧ Баттерворта.
|
|
|
|
|
|
|
|
|
|
Функция рассчитывает коэффициенты передаточной характеристики \f$H(s)\f$
|
|
|
|
|
аналогового нормированного ФНЧ Баттерворта порядка `ord` с частотой среза
|
|
|
|
|
1 рад/с по уровню \f$ -R_p \f$ дБ.
|
|
|
|
|
|
|
|
|
|
\param[in] Rp
|
|
|
|
|
Неравномерность АЧХ в полосе пропускания (дБ). \n
|
|
|
|
|
Параметр задает уровень искажений в полосе от 0 до 1 рад/с. \n
|
|
|
|
|
Значение должно быть положительным. \n
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
\param[in] ord
|
|
|
|
|
Порядок фильтра. \n
|
|
|
|
|
Количество коэффициентов числителя и знаменателя
|
|
|
|
|
передаточной функции \f$H(s)\f$ равно `ord+1`. \n
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
\param[out] b
|
|
|
|
|
Указатель на вектор коэффициентов числителя
|
|
|
|
|
передаточной функции \f$H(s)\f$. \n
|
|
|
|
|
Размер вектора `[ord+1 x 1]`. \n
|
|
|
|
|
Память должна быть выделена. \n
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
\param[out] a
|
|
|
|
|
Указатель на вектор коэффициентов знаменателя
|
|
|
|
|
передаточной функции \f$H(s)\f$. \n
|
|
|
|
|
Размер вектора `[ord+1 x 1]`. \n
|
|
|
|
|
Память должна быть выделена. \n
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
\return
|
|
|
|
|
`RES_OK` --- фильтр рассчитан успешно. \n
|
|
|
|
|
В противном случае \ref ERROR_CODE_GROUP "код ошибки". \n
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
Пример использования функции `butter_ap`:
|
|
|
|
|
|
|
|
|
|
\include butter_ap_test.c
|
|
|
|
|
|
|
|
|
|
Результат работы программы:
|
|
|
|
|
|
|
|
|
|
\verbatim
|
|
|
|
|
b[ 0] = 1.965 a[ 0] = 1.965
|
|
|
|
|
b[ 1] = 0.000 a[ 1] = 3.138
|
|
|
|
|
b[ 2] = 0.000 a[ 2] = 2.505
|
|
|
|
|
b[ 3] = 0.000 a[ 3] = 1.000
|
|
|
|
|
\endverbatim
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
В каталоге `dat` будут созданы три файла: \n
|
|
|
|
|
|
|
|
|
|
\verbatim
|
|
|
|
|
butter_ap_test_mag.txt АЧХ фильтра
|
|
|
|
|
butter_ap_test_phi.txt ФЧХ фильтра
|
|
|
|
|
butter_ap_test_tau.txt ГВЗ фильтра
|
|
|
|
|
\endverbatim
|
|
|
|
|
|
|
|
|
|
Кроме того программа GNUPLOT произведет построение следующих графиков
|
|
|
|
|
по сохраненным в файлах данным:
|
2018-04-02 20:48:53 +00:00
|
|
|
|
|
2020-07-23 18:55:02 +00:00
|
|
|
|
\image html butter_ap_test.png
|
|
|
|
|
|
|
|
|
|
\author Бахурин Сергей www.dsplib.org
|
|
|
|
|
***************************************************************************** */
|
|
|
|
|
#endif
|
2018-04-03 20:15:14 +00:00
|
|
|
|
int DSPL_API butter_ap(double rp, int ord, double* b, double* a)
|
2018-04-02 20:48:53 +00:00
|
|
|
|
{
|
2020-07-17 18:09:28 +00:00
|
|
|
|
int res;
|
|
|
|
|
complex_t *z = NULL;
|
|
|
|
|
complex_t *p = NULL;
|
|
|
|
|
int nz, np;
|
2018-10-24 17:39:51 +00:00
|
|
|
|
|
2020-07-17 18:09:28 +00:00
|
|
|
|
if(rp < 0.0)
|
|
|
|
|
return ERROR_FILTER_RP;
|
|
|
|
|
if(ord < 1)
|
|
|
|
|
return ERROR_FILTER_ORD;
|
|
|
|
|
if(!a || !b)
|
|
|
|
|
return ERROR_PTR;
|
2018-10-24 17:39:51 +00:00
|
|
|
|
|
2020-07-17 18:09:28 +00:00
|
|
|
|
z = (complex_t*) malloc(ord*sizeof(complex_t));
|
|
|
|
|
p = (complex_t*) malloc(ord*sizeof(complex_t));
|
2018-10-24 17:39:51 +00:00
|
|
|
|
|
|
|
|
|
|
2020-07-17 18:09:28 +00:00
|
|
|
|
res = butter_ap_zp(ord, rp, z, &nz, p, &np);
|
|
|
|
|
if(res != RES_OK)
|
|
|
|
|
goto exit_label;
|
2018-10-24 17:39:51 +00:00
|
|
|
|
|
2020-07-17 18:09:28 +00:00
|
|
|
|
res = filter_zp2ab(z, nz, p, np, ord, b, a);
|
|
|
|
|
if(res != RES_OK)
|
|
|
|
|
goto exit_label;
|
2018-10-24 17:39:51 +00:00
|
|
|
|
|
2020-07-17 18:09:28 +00:00
|
|
|
|
b[0] = a[0];
|
2018-04-02 20:48:53 +00:00
|
|
|
|
|
|
|
|
|
|
|
|
|
|
exit_label:
|
2020-07-17 18:09:28 +00:00
|
|
|
|
if(z)
|
|
|
|
|
free(z);
|
|
|
|
|
if(p)
|
|
|
|
|
free(p);
|
|
|
|
|
return res;
|
2018-04-02 20:48:53 +00:00
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
2020-07-23 18:55:02 +00:00
|
|
|
|
#ifdef DOXYGEN_ENGLISH
|
|
|
|
|
/*! ****************************************************************************
|
|
|
|
|
\ingroup IIR_FILTER_DESIGN_GROUP
|
|
|
|
|
\fn int butter_ap_zp(int ord, double rp, complex_t* z, int* nz,
|
|
|
|
|
complex_t* p, int* np)
|
|
|
|
|
|
|
|
|
|
\brief
|
|
|
|
|
Function calculates arrays of zeros and poles for analog normlized lowpass
|
|
|
|
|
Batterworth filter transfer function \f$ H(s) \f$ order `ord` .
|
|
|
|
|
|
|
|
|
|
Analog normalized lowpass filter magnitude ripple equals \f$ -R_p \f$ dB
|
|
|
|
|
for angular frequency \f$ \omega \f$ from 0 to 1 rad/s.
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
\param[in] ord
|
|
|
|
|
Filter order. \n
|
|
|
|
|
Number of zeros and poles of filter can be less or equal `ord`. \n
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
\param[in] rp
|
|
|
|
|
Magnitude ripple in passband (dB). \n
|
|
|
|
|
This parameter sets maximum filter distortion from 0 to 1 rad/s frequency. \n
|
|
|
|
|
Parameter must be positive. \n
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
\param[out] z
|
|
|
|
|
Pointer to the \f$ H(s) \f$ zeros array. \n
|
|
|
|
|
Maximum vector size is `[ord x 1]`. \n
|
|
|
|
|
Memory must be allocated for maximum vector size. \n
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
\param[out] nz
|
|
|
|
|
Pointer to the variable which keep number of finite zeros \f$ H(s) \f$. \n
|
|
|
|
|
Number of finite zeros which was calculated and saved in vector `z`. \n
|
|
|
|
|
Pointer cannot be `NULL`. \n
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
\param[out] p
|
|
|
|
|
Pointer to the \f$ H(s) \f$ poles array. \n
|
|
|
|
|
Maximum vector size is `[ord x 1]`. \n
|
|
|
|
|
Memory must be allocated for maximum vector size. \n
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
\param[out] np
|
|
|
|
|
Pointer to the variable which keep number of
|
|
|
|
|
calculated poles of \f$ H(s) \f$. \n
|
|
|
|
|
Pointer cannot be `NULL`. \n
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
\return
|
|
|
|
|
`RES_OK` if zeros and poles is calculated successfully. \n
|
|
|
|
|
Else \ref ERROR_CODE_GROUP "code error".
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
\note
|
|
|
|
|
Normalized Butterworth lowpass filter has no finite zeros.
|
|
|
|
|
So `z` vector will not changed and in pointer `nz` will write 0 value. \n
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Example of normalized Butterworth lowpass filter zeros and poles calculation:
|
|
|
|
|
\include butter_ap_zp_test.c
|
|
|
|
|
|
|
|
|
|
Result:
|
|
|
|
|
|
|
|
|
|
\verbatim
|
|
|
|
|
Butterworth filter zeros: 0
|
|
|
|
|
Butterworth filter poles: 7
|
|
|
|
|
p[ 0] = -1.101 +0.000 j
|
|
|
|
|
p[ 1] = -0.245 +1.074 j
|
|
|
|
|
p[ 2] = -0.245 -1.074 j
|
|
|
|
|
p[ 3] = -0.687 +0.861 j
|
|
|
|
|
p[ 4] = -0.687 -0.861 j
|
|
|
|
|
p[ 5] = -0.992 +0.478 j
|
|
|
|
|
p[ 6] = -0.992 -0.478 j
|
|
|
|
|
\endverbatim
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
In `dat` folder will be created `butter_ap_zp.txt` file. \n
|
|
|
|
|
|
|
|
|
|
In addition, GNUPLOT will build the following graphs
|
|
|
|
|
from data stored in `dat/butter_ap_zp.txt` file:
|
|
|
|
|
|
|
|
|
|
\image html butter_ap_zp_test.png
|
|
|
|
|
|
|
|
|
|
\author Sergey Bakhurin www.dsplib.org
|
|
|
|
|
***************************************************************************** */
|
|
|
|
|
#endif
|
|
|
|
|
#ifdef DOXYGEN_RUSSIAN
|
|
|
|
|
/*! ****************************************************************************
|
|
|
|
|
\ingroup IIR_FILTER_DESIGN_GROUP
|
|
|
|
|
\fn int butter_ap_zp(int ord, double rp, complex_t* z, int* nz,
|
|
|
|
|
complex_t* p, int* np)
|
|
|
|
|
|
|
|
|
|
\brief
|
|
|
|
|
Расчет массивов нулей и полюсов передаточной функции
|
|
|
|
|
\f$ H(s) \f$ аналогового нормированного ФНЧ Баттерворта.
|
|
|
|
|
|
|
|
|
|
Функция рассчитывает значения нулей и полюсов передаточной функции
|
|
|
|
|
\f$ H(s)\f$ аналогового нормированного ФНЧ Баттерворта порядка `ord`
|
|
|
|
|
с частотой среза 1 рад/с по уровню \f$-R_p\f$ дБ. \n
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
\param[in] ord
|
|
|
|
|
Порядок фильтра. \n
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
\param[in] rp
|
|
|
|
|
Неравномерность АЧХ в полосе пропускания (дБ). \n
|
|
|
|
|
Параметр задает уровень искажений в полосе от 0 до 1 рад/с. \n
|
|
|
|
|
Значение должно быть положительным. \n
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
\param[out] z
|
|
|
|
|
Указатель на массив комплексных нулей
|
|
|
|
|
передаточной характеристики \f$ H(s)\f$. \n
|
|
|
|
|
Максимальный размер вектора вектора `[ord x 1]`. \n
|
|
|
|
|
Память должна быть выделена. \n
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
\param[out] nz
|
|
|
|
|
Указатель на переменную количества нулей
|
|
|
|
|
передаточной характеристики \f$ H(s)\f$. \n
|
|
|
|
|
По данному указателю будет записано количество
|
|
|
|
|
нулей фильтра, которые были рассчитаны и
|
|
|
|
|
помещены в вектор `z`. \n
|
|
|
|
|
Память должна быть выделена. \n
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
\param[out] p
|
|
|
|
|
Указатель на массив комплексных полюсов
|
|
|
|
|
передаточной характеристики \f$ H(s)\f$. \n
|
|
|
|
|
Максимальный размер вектора вектора `[ord x 1]`. \n
|
|
|
|
|
Память должна быть выделена. \n
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
\param[out] np
|
|
|
|
|
Указатель на переменную количества полюсов
|
|
|
|
|
передаточной характеристики \f$ H(s)\f$. \n
|
|
|
|
|
По данному укащзателю будет записано количество нулей фильтра, которые
|
|
|
|
|
были рассчитны и помещены в вектор `p`. \n
|
|
|
|
|
Память должна быть выделена. \n
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
\return
|
|
|
|
|
`RES_OK` --- массивы нулей и полюсов рассчитаны успешно. \n
|
|
|
|
|
В противном случае \ref ERROR_CODE_GROUP "код ошибки". \n
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
\note
|
|
|
|
|
Нормированный ФНЧ Баттерворта не имеет нулей, поэтому массив нулей `z`
|
|
|
|
|
не будет изменен, а по указателю `nz` будет записан 0. \n
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Пример программы рассчета нулей и полюсов нормированного ФНЧ Баттерворта:
|
|
|
|
|
\include butter_ap_zp_test.c
|
|
|
|
|
|
|
|
|
|
Результат выполнения программы:
|
|
|
|
|
|
|
|
|
|
\verbatim
|
|
|
|
|
Butterworth filter zeros: 0
|
|
|
|
|
Butterworth filter poles: 7
|
|
|
|
|
p[ 0] = -1.101 +0.000 j
|
|
|
|
|
p[ 1] = -0.245 +1.074 j
|
|
|
|
|
p[ 2] = -0.245 -1.074 j
|
|
|
|
|
p[ 3] = -0.687 +0.861 j
|
|
|
|
|
p[ 4] = -0.687 -0.861 j
|
|
|
|
|
p[ 5] = -0.992 +0.478 j
|
|
|
|
|
p[ 6] = -0.992 -0.478 j
|
|
|
|
|
\endverbatim
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
В каталоге `dat` будет создан файл `butter_ap_zp.txt`. \n
|
|
|
|
|
|
|
|
|
|
Пакет GNUPLOT произведет построение карты полюсов по
|
|
|
|
|
сохранненным в `dat/butter_ap_zp.txt` данным:
|
|
|
|
|
|
|
|
|
|
\image html butter_ap_zp_test.png
|
|
|
|
|
|
|
|
|
|
\author
|
|
|
|
|
Бахурин Сергей
|
|
|
|
|
www.dsplib.org
|
|
|
|
|
***************************************************************************** */
|
|
|
|
|
#endif
|
2020-04-18 08:09:38 +00:00
|
|
|
|
int DSPL_API butter_ap_zp(int ord, double rp, complex_t* z, int* nz,
|
2018-10-24 17:39:51 +00:00
|
|
|
|
complex_t *p, int* np)
|
2018-04-02 20:48:53 +00:00
|
|
|
|
{
|
2020-07-17 18:09:28 +00:00
|
|
|
|
double alpha;
|
|
|
|
|
double theta;
|
|
|
|
|
double ep;
|
|
|
|
|
int r;
|
|
|
|
|
int L;
|
|
|
|
|
int ind = 0, k;
|
|
|
|
|
|
|
|
|
|
if(rp < 0 || rp == 0)
|
|
|
|
|
return ERROR_FILTER_RP;
|
|
|
|
|
if(ord < 1)
|
|
|
|
|
return ERROR_FILTER_ORD;
|
|
|
|
|
if(!z || !p || !nz || !np)
|
|
|
|
|
return ERROR_PTR;
|
|
|
|
|
|
|
|
|
|
ep = sqrt(pow(10.0, rp*0.1) - 1.0);
|
|
|
|
|
r = ord % 2;
|
|
|
|
|
L = (int)((ord-r)/2);
|
|
|
|
|
|
|
|
|
|
alpha = pow(ep, -1.0/(double)ord);
|
|
|
|
|
if(r)
|
|
|
|
|
{
|
|
|
|
|
RE(p[ind]) = -alpha;
|
|
|
|
|
IM(p[ind]) = 0.0;
|
|
|
|
|
ind++;
|
|
|
|
|
}
|
|
|
|
|
for(k = 0; k < L; k++)
|
|
|
|
|
{
|
|
|
|
|
theta = M_PI*(double)(2*k + 1)/(double)(2*ord);
|
|
|
|
|
RE(p[ind]) = RE(p[ind+1]) = -alpha * sin(theta);
|
|
|
|
|
IM(p[ind]) = alpha * cos(theta);
|
|
|
|
|
IM(p[ind+1]) = -alpha * cos(theta);
|
|
|
|
|
ind+=2;
|
|
|
|
|
}
|
|
|
|
|
*np = ord;
|
|
|
|
|
*nz = 0;
|
|
|
|
|
return RES_OK;
|
2018-04-02 20:48:53 +00:00
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
2020-07-23 18:55:02 +00:00
|
|
|
|
#ifdef DOXYGEN_ENGLISH
|
|
|
|
|
/*! ****************************************************************************
|
|
|
|
|
\ingroup IIR_FILTER_DESIGN_GROUP
|
|
|
|
|
\fn int cheby1_ap(double Rp, int ord, double* b, double* a)
|
|
|
|
|
|
|
|
|
|
\brief
|
|
|
|
|
Function calculates the transfer function \f$ H(s) \f$ coefficients of
|
|
|
|
|
analog normalized lowpass Chebyshev type 1 filter.
|
|
|
|
|
|
|
|
|
|
Analog normalized lowpass filter magnitude ripple equals \f$ -R_p \f$ dB
|
|
|
|
|
for angular frequency \f$ \omega \f$ from 0 to 1 rad/s.
|
|
|
|
|
|
|
|
|
|
\param[in] Rp
|
|
|
|
|
Magnitude ripple in passband (dB). \n
|
|
|
|
|
This parameter sets maximum filter distortion from 0 to 1 rad/s frequency. \n
|
|
|
|
|
Parameter must be positive. \n
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
\param[in] ord
|
|
|
|
|
Filter order. \n
|
|
|
|
|
Filter coefficients number equals `ord+1` for numerator and denominator
|
|
|
|
|
of transfer function \f$ H(s) \f$ \n
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
\param[out] b
|
|
|
|
|
Pointer to the vector of transfer function \f$H(s)\f$
|
|
|
|
|
numerator coefficient. \n
|
|
|
|
|
Vector size is `[ord+1 x 1]`. \n
|
|
|
|
|
Memory must be allocated. \n
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
\param[out] a
|
|
|
|
|
Pointer to the vector of transfer function \f$H(s)\f$
|
|
|
|
|
denominator coefficient. \n
|
|
|
|
|
Vector size is `[ord+1 x 1]`. \n
|
|
|
|
|
Memory must be allocated. \n
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
\return
|
|
|
|
|
`RES_OK` if filter coefficients is calculated successfully. \n
|
|
|
|
|
Else \ref ERROR_CODE_GROUP "code error".
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
Example:
|
|
|
|
|
|
|
|
|
|
\include cheby1_ap_test.c
|
|
|
|
|
|
|
|
|
|
Result:
|
|
|
|
|
|
|
|
|
|
\verbatim
|
|
|
|
|
b[ 0] = 0.125 a[ 0] = 0.177
|
|
|
|
|
b[ 1] = 0.000 a[ 1] = 0.405
|
|
|
|
|
b[ 2] = 0.000 a[ 2] = 1.169
|
|
|
|
|
b[ 3] = 0.000 a[ 3] = 0.582
|
|
|
|
|
b[ 4] = 0.000 a[ 4] = 1.000
|
|
|
|
|
\endverbatim
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
In `dat` folder will be created 3 files: \n
|
|
|
|
|
|
|
|
|
|
\verbatim
|
|
|
|
|
cheby1_ap_test_mag.txt magnitude
|
|
|
|
|
cheby1_ap_test_phi.txt phase response
|
|
|
|
|
cheby1_ap_test_tau.txt group delay
|
|
|
|
|
\endverbatim
|
|
|
|
|
|
|
|
|
|
In addition, GNUPLOT will build the following graphs from data stored in files:
|
|
|
|
|
|
|
|
|
|
\image html cheby1_ap_test.png
|
|
|
|
|
|
|
|
|
|
\author Sergey Bakhurin www.dsplib.org
|
|
|
|
|
***************************************************************************** */
|
|
|
|
|
#endif
|
|
|
|
|
#ifdef DOXYGEN_RUSSIAN
|
|
|
|
|
/*! ****************************************************************************
|
|
|
|
|
\ingroup IIR_FILTER_DESIGN_GROUP
|
|
|
|
|
\fn int cheby1_ap(double Rp, int ord, double* b, double* a)
|
|
|
|
|
|
|
|
|
|
\brief
|
|
|
|
|
Расчет передаточной характеристики \f$ H(s) \f$ аналогового
|
|
|
|
|
нормированного ФНЧ Чебышёва первого рода.
|
|
|
|
|
|
|
|
|
|
Функция рассчитывает коэффициенты передаточной характеристики
|
|
|
|
|
\f$ H(s)\f$ аналогового нормированного ФНЧ Чебышёва первого рода
|
|
|
|
|
порядка `ord` с частотой среза 1 рад/с по уровню \f$-R_p\f$ дБ. \n
|
|
|
|
|
|
|
|
|
|
Особенностью фильтра Чебышёва первого рода являются
|
|
|
|
|
равноволновые пульсации АЧХ в полосе пропускания.
|
|
|
|
|
|
|
|
|
|
\param[in] Rp
|
|
|
|
|
Неравномерность АЧХ в полосе пропускания (дБ). \n
|
|
|
|
|
Параметр задает уровень искажений в полосе от 0 до 1 рад/с. \n
|
|
|
|
|
Значение должно быть положительным. \n
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
\param[in] ord
|
|
|
|
|
Порядок фильтра. \n
|
|
|
|
|
Количество коэффициентов числителя и знаменателя
|
|
|
|
|
передаточной функции \f$ H(s)\f$ равно `ord+1`. \n
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
\param[out] b
|
|
|
|
|
Указатель на вектор коэффициентов числителя передаточной функции \f$H(s)\f$. \n
|
|
|
|
|
Размер вектора `[ord+1 x 1]`. \n
|
|
|
|
|
Память должна быть выделена. \n
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
\param[out] a
|
|
|
|
|
Указатель на вектор коэффициентов знаменателя
|
|
|
|
|
передаточной функции \f$H(s)\f$. \n
|
|
|
|
|
Размер вектора `[ord+1 x 1]`. \n
|
|
|
|
|
Память должна быть выделена. \n
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
\return
|
|
|
|
|
`RES_OK` --- фильтр рассчитан успешно. \n
|
|
|
|
|
В противном случае \ref ERROR_CODE_GROUP "код ошибки". \n
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
Пример использования функции `cheby1_ap`:
|
|
|
|
|
|
|
|
|
|
\include cheby1_ap_test.c
|
|
|
|
|
|
|
|
|
|
Результат работы программы:
|
|
|
|
|
|
|
|
|
|
\verbatim
|
|
|
|
|
b[ 0] = 0.125 a[ 0] = 0.177
|
|
|
|
|
b[ 1] = 0.000 a[ 1] = 0.405
|
|
|
|
|
b[ 2] = 0.000 a[ 2] = 1.169
|
|
|
|
|
b[ 3] = 0.000 a[ 3] = 0.582
|
|
|
|
|
b[ 4] = 0.000 a[ 4] = 1.000
|
|
|
|
|
\endverbatim
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
В каталоге `dat` будут созданы три файла: \n
|
|
|
|
|
|
|
|
|
|
\verbatim
|
|
|
|
|
cheby1_ap_test_mag.txt АЧХ фильтра
|
|
|
|
|
cheby1_ap_test_phi.txt ФЧХ фильтра
|
|
|
|
|
cheby1_ap_test_tau.txt ГВЗ фильтра
|
|
|
|
|
\endverbatim
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
Кроме того программа GNUPLOT произведет построение следующих графиков
|
|
|
|
|
по сохраненным в файлах данным:
|
|
|
|
|
|
|
|
|
|
\image html cheby1_ap_test.png
|
|
|
|
|
|
|
|
|
|
\author
|
|
|
|
|
Бахурин Сергей
|
|
|
|
|
www.dsplib.org
|
|
|
|
|
***************************************************************************** */
|
|
|
|
|
#endif
|
2018-04-03 20:15:14 +00:00
|
|
|
|
int DSPL_API cheby1_ap(double rp, int ord, double* b, double* a)
|
|
|
|
|
{
|
2020-07-17 18:09:28 +00:00
|
|
|
|
int res;
|
|
|
|
|
complex_t *z = NULL;
|
|
|
|
|
complex_t *p = NULL;
|
|
|
|
|
int nz, np, k;
|
|
|
|
|
complex_t h0 = {1.0, 0.0};
|
|
|
|
|
double tmp;
|
2018-10-24 17:39:51 +00:00
|
|
|
|
|
|
|
|
|
|
2020-07-17 18:09:28 +00:00
|
|
|
|
if(rp < 0.0)
|
|
|
|
|
return ERROR_FILTER_RP;
|
|
|
|
|
if(ord < 1)
|
|
|
|
|
return ERROR_FILTER_ORD;
|
|
|
|
|
if(!a || !b)
|
|
|
|
|
return ERROR_PTR;
|
2018-10-24 17:39:51 +00:00
|
|
|
|
|
2020-07-17 18:09:28 +00:00
|
|
|
|
z = (complex_t*) malloc(ord*sizeof(complex_t));
|
|
|
|
|
p = (complex_t*) malloc(ord*sizeof(complex_t));
|
2018-10-24 17:39:51 +00:00
|
|
|
|
|
|
|
|
|
|
2020-07-17 18:09:28 +00:00
|
|
|
|
res = cheby1_ap_zp(ord, rp, z, &nz, p, &np);
|
|
|
|
|
if(res != RES_OK)
|
|
|
|
|
goto exit_label;
|
2018-10-24 17:39:51 +00:00
|
|
|
|
|
2020-07-17 18:09:28 +00:00
|
|
|
|
res = filter_zp2ab(z, nz, p, np, ord, b, a);
|
|
|
|
|
if(res != RES_OK)
|
|
|
|
|
goto exit_label;
|
2018-10-24 17:39:51 +00:00
|
|
|
|
|
|
|
|
|
|
2020-07-17 18:09:28 +00:00
|
|
|
|
if(!(ord % 2))
|
|
|
|
|
RE(h0) = 1.0 / pow(10.0, rp*0.05);
|
2018-10-24 17:39:51 +00:00
|
|
|
|
|
2020-07-17 18:09:28 +00:00
|
|
|
|
for(k = 0; k < np; k++)
|
|
|
|
|
{
|
|
|
|
|
tmp = CMRE(h0, p[k]);
|
|
|
|
|
IM(h0) = CMIM(h0, p[k]);
|
|
|
|
|
RE(h0) = tmp;
|
|
|
|
|
}
|
2018-10-24 17:39:51 +00:00
|
|
|
|
|
2020-07-17 18:09:28 +00:00
|
|
|
|
b[0] = fabs(RE(h0));
|
2018-04-03 20:15:14 +00:00
|
|
|
|
|
|
|
|
|
exit_label:
|
2020-07-17 18:09:28 +00:00
|
|
|
|
if(z)
|
|
|
|
|
free(z);
|
|
|
|
|
if(p)
|
|
|
|
|
free(p);
|
|
|
|
|
return res;
|
2018-04-03 20:15:14 +00:00
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
2020-07-23 18:55:02 +00:00
|
|
|
|
#ifdef DOXYGEN_ENGLISH
|
|
|
|
|
/*! ****************************************************************************
|
|
|
|
|
\ingroup IIR_FILTER_DESIGN_GROUP
|
|
|
|
|
\fn int cheby1_ap_zp( int ord, double rp, complex_t* z, int* nz,
|
|
|
|
|
complex_t* p, int* np)
|
|
|
|
|
\brief
|
|
|
|
|
Function calculates arrays of zeros and poles for analog normlized lowpass
|
|
|
|
|
Chebyshev type 1 filter transfer function \f$ H(s) \f$ order `ord` .
|
|
|
|
|
|
|
|
|
|
Analog normalized lowpass filter magnitude ripple equals \f$ -R_p \f$ dB
|
|
|
|
|
for angular frequency \f$ \omega \f$ from 0 to 1 rad/s.
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
\param[in] ord
|
|
|
|
|
Filter order. \n
|
|
|
|
|
Number of zeros and poles of filter can be less or equal `ord`. \n
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
\param[in] rp
|
|
|
|
|
Magnitude ripple in passband (dB). \n
|
|
|
|
|
This parameter sets maximum filter distortion from 0 to 1 rad/s frequency. \n
|
|
|
|
|
Parameter must be positive. \n
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
\param[out] z
|
|
|
|
|
Pointer to the \f$ H(s) \f$ zeros array. \n
|
|
|
|
|
Maximum vector size is `[ord x 1]`. \n
|
|
|
|
|
Memory must be allocated for maximum vector size. \n
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
\param[out] nz
|
|
|
|
|
Pointer to the variable which keep number of finite zeros \f$ H(s) \f$. \n
|
|
|
|
|
Number of finite zeros which was calculated and saved in vector `z`. \n
|
|
|
|
|
Pointer cannot be `NULL`. \n
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
\param[out] p
|
|
|
|
|
Pointer to the \f$ H(s) \f$ poles array. \n
|
|
|
|
|
Maximum vector size is `[ord x 1]`. \n
|
|
|
|
|
Memory must be allocated for maximum vector size. \n
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
\param[out] np
|
|
|
|
|
Pointer to the variable which keep number of
|
|
|
|
|
calculated poles of \f$ H(s) \f$. \n
|
|
|
|
|
Pointer cannot be `NULL`. \n
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
\return
|
|
|
|
|
`RES_OK` if zeros and poles is calculated successfully. \n
|
|
|
|
|
Else \ref ERROR_CODE_GROUP "code error".
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
\note
|
|
|
|
|
Normalized Chebyshev type 1 lowpass filter has no finite zeros.
|
|
|
|
|
So `z` vector will not changed and in pointer `nz` will write 0 value. \n
|
|
|
|
|
|
|
|
|
|
Example of normalized Chebyshev type 1 lowpass filter
|
|
|
|
|
zeros and poles calculation:
|
|
|
|
|
\include cheby1_ap_zp_test.c
|
|
|
|
|
|
|
|
|
|
Result:
|
|
|
|
|
|
|
|
|
|
\verbatim
|
|
|
|
|
Chebyshev type 1 filter zeros: 0
|
|
|
|
|
Chebyshev type 1 filter poles: 7
|
|
|
|
|
p[ 0] = -0.256 +0.000 j
|
|
|
|
|
p[ 1] = -0.057 +1.006 j
|
|
|
|
|
p[ 2] = -0.057 -1.006 j
|
|
|
|
|
p[ 3] = -0.160 +0.807 j
|
|
|
|
|
p[ 4] = -0.160 -0.807 j
|
|
|
|
|
p[ 5] = -0.231 +0.448 j
|
|
|
|
|
p[ 6] = -0.231 -0.448 j
|
|
|
|
|
\endverbatim
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
In `dat` folder will be created `cheby1_ap_zp.txt` file. \n
|
|
|
|
|
|
|
|
|
|
In addition, GNUPLOT will build the following graphs
|
|
|
|
|
from data stored in `dat/cheby1_ap_zp.txt` file:
|
|
|
|
|
|
|
|
|
|
\image html cheby1_ap_zp_test.png
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
\author Sergey Bakhurin www.dsplib.org
|
|
|
|
|
***************************************************************************** */
|
|
|
|
|
#endif
|
|
|
|
|
#ifdef DOXYGEN_RUSSIAN
|
|
|
|
|
/*! ****************************************************************************
|
|
|
|
|
\ingroup IIR_FILTER_DESIGN_GROUP
|
|
|
|
|
\fn int cheby1_ap_zp(int ord, double rp, complex_t* z, int* nz, complex_t* p, int* np)
|
|
|
|
|
\brief
|
|
|
|
|
Расчет массивов нулей и полюсов передаточной функции \f$ H(s) \f$
|
|
|
|
|
аналогового нормированного ФНЧ Чебышёва первого рода.
|
|
|
|
|
|
|
|
|
|
Функция рассчитывает значения нулей и полюсов передаточной функции
|
|
|
|
|
\f$ H(s)\f$ аналогового нормированного ФНЧ Чебышёва первого рода
|
|
|
|
|
порядка `ord` с частотой среза 1 рад/с по уровню \f$-R_p\f$ дБ, с
|
|
|
|
|
неравномерностью в полосе пропускания \f$ R_p \f$ дБ. \n
|
|
|
|
|
|
|
|
|
|
\param[in] ord
|
|
|
|
|
Порядок фильтра. \n
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
\param[in] rp
|
|
|
|
|
Неравномерность АЧХ в полосе пропускания (дБ). \n
|
|
|
|
|
Параметр задает уровень искажений в полосе от 0 до 1 рад/с. \n
|
|
|
|
|
Значение должно быть положительным. \n
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
\param[out] z
|
|
|
|
|
Указатель на массив комплексных нулей
|
|
|
|
|
передаточной характеристики \f$ H(s)\f$. \n
|
|
|
|
|
Максимальный размер вектора `[ord x 1]`. \n
|
|
|
|
|
Память должна быть выделена. \n
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
\param[out] nz
|
|
|
|
|
Указатель на переменную количества нулей
|
|
|
|
|
передаточной функции \f$H(s)\f$. \n
|
|
|
|
|
По данному указателю будет записано количество нулей фильтра,
|
|
|
|
|
которые были рассчитаны и помещены в вектор `z`. \n
|
|
|
|
|
Память должна быть выделена. \n
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
\param[out] p
|
|
|
|
|
Указатель на массив комплексных полюсов
|
|
|
|
|
передаточной характеристики \f$H(s)\f$. \n
|
|
|
|
|
Максимальный размер вектора вектора `[ord x 1]`. \n
|
|
|
|
|
Память должна быть выделена. \n
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
\param[out] np
|
|
|
|
|
Указатель на переменную количества полюсов передаточной функции \f$ H(s)\f$. \n
|
|
|
|
|
По данному указателю будет записано количество нулей фильтра, которые были
|
|
|
|
|
рассчитаны и помещены в вектор `p`. \n
|
|
|
|
|
Память должна быть выделена. \n
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
\return
|
|
|
|
|
`RES_OK` --- массивы нулей и полюсов рассчитаны успешно. \n
|
|
|
|
|
В противном случае \ref ERROR_CODE_GROUP "код ошибки". \n
|
|
|
|
|
|
|
|
|
|
\note
|
|
|
|
|
Нормированный ФНЧ Чебышёва первого рода не имеет нулей, поэтому массив
|
|
|
|
|
нулей `z` не будет изменен, а по указателю `nz` будет записан 0. \n
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Пример программы рассчета нулей и полюсов нормированного
|
|
|
|
|
ФНЧ Чебышева первого рода:
|
|
|
|
|
\include cheby1_ap_zp_test.c
|
|
|
|
|
|
|
|
|
|
Результат выполнения программы:
|
|
|
|
|
|
|
|
|
|
\verbatim
|
|
|
|
|
Chebyshev type 1 filter zeros: 0
|
|
|
|
|
Chebyshev type 1 filter poles: 7
|
|
|
|
|
p[ 0] = -0.256 +0.000 j
|
|
|
|
|
p[ 1] = -0.057 +1.006 j
|
|
|
|
|
p[ 2] = -0.057 -1.006 j
|
|
|
|
|
p[ 3] = -0.160 +0.807 j
|
|
|
|
|
p[ 4] = -0.160 -0.807 j
|
|
|
|
|
p[ 5] = -0.231 +0.448 j
|
|
|
|
|
p[ 6] = -0.231 -0.448 j
|
|
|
|
|
\endverbatim
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
В каталоге `dat` будет создан файл `cheby1_ap_zp.txt`. \n
|
|
|
|
|
|
|
|
|
|
Пакет GNUPLOT произведет построение карты полюсов по
|
|
|
|
|
сохранненным в `dat/cheby1_ap_zp.txt` данным:
|
|
|
|
|
|
|
|
|
|
\image html cheby1_ap_zp_test.png
|
|
|
|
|
|
|
|
|
|
\author Бахурин Сергей www.dsplib.org
|
|
|
|
|
***************************************************************************** */
|
|
|
|
|
#endif
|
2020-04-18 08:09:38 +00:00
|
|
|
|
int DSPL_API cheby1_ap_zp(int ord, double rp, complex_t* z, int* nz,
|
2020-07-23 18:55:02 +00:00
|
|
|
|
complex_t* p, int* np)
|
2018-04-03 20:15:14 +00:00
|
|
|
|
{
|
2020-07-17 18:09:28 +00:00
|
|
|
|
double theta;
|
|
|
|
|
double ep;
|
|
|
|
|
double beta;
|
|
|
|
|
double shbeta;
|
|
|
|
|
double chbeta;
|
|
|
|
|
int r;
|
|
|
|
|
int L;
|
|
|
|
|
int ind = 0, k;
|
|
|
|
|
|
|
|
|
|
if(rp < 0 || rp == 0)
|
|
|
|
|
return ERROR_FILTER_RP;
|
|
|
|
|
if(ord < 1)
|
|
|
|
|
return ERROR_FILTER_ORD;
|
|
|
|
|
if(!z || !p || !nz || !np)
|
|
|
|
|
return ERROR_PTR;
|
|
|
|
|
|
|
|
|
|
ep = sqrt(pow(10.0, rp*0.1) - 1.0);
|
|
|
|
|
r = ord % 2;
|
|
|
|
|
L = (int)((ord-r)/2);
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
beta = asinh(1.0/ep)/(double)ord;
|
|
|
|
|
chbeta = cosh(beta);
|
|
|
|
|
shbeta = sinh(beta);
|
|
|
|
|
|
|
|
|
|
if(r)
|
|
|
|
|
{
|
|
|
|
|
RE(p[ind]) = -shbeta;
|
|
|
|
|
IM(p[ind]) = 0.0;
|
|
|
|
|
ind++;
|
|
|
|
|
}
|
|
|
|
|
for(k = 0; k < L; k++)
|
|
|
|
|
{
|
|
|
|
|
theta = M_PI*(double)(2*k + 1)/(double)(2*ord);
|
|
|
|
|
RE(p[ind]) = RE(p[ind+1]) = -shbeta * sin(theta);
|
|
|
|
|
IM(p[ind]) = chbeta * cos(theta);
|
|
|
|
|
IM(p[ind+1]) = -IM(p[ind]);
|
|
|
|
|
ind+=2;
|
|
|
|
|
}
|
|
|
|
|
*np = ord;
|
|
|
|
|
*nz = 0;
|
|
|
|
|
return RES_OK;
|
2018-04-03 20:15:14 +00:00
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
2020-07-23 18:55:02 +00:00
|
|
|
|
#ifdef DOXYGEN_ENGLISH
|
|
|
|
|
/*! ****************************************************************************
|
|
|
|
|
\ingroup IIR_FILTER_DESIGN_GROUP
|
|
|
|
|
\fn int cheby2_ap(double Rs, int ord, double *b, double *a)
|
|
|
|
|
|
|
|
|
|
\brief
|
|
|
|
|
Function calculates the transfer function \f$ H(s) \f$ coefficients of
|
|
|
|
|
analog normalized lowpass Chebyshev type 2 filter.
|
|
|
|
|
|
|
|
|
|
Analog normalized Chebyshev type 2 filter lowpass filter has \f$Rs\f$ dB
|
|
|
|
|
suppression in stopband.
|
|
|
|
|
Also analog normalized Chebyshev type 2 filter magnitude equals \f$-Rs\f$ dB
|
|
|
|
|
for angular frequency \f$\omega = 1\f$ rad/s.
|
|
|
|
|
|
|
|
|
|
\param[in] Rs
|
|
|
|
|
Suppression level in stopband (dB). \n
|
|
|
|
|
This parameter sets filter supression for \f$\omega \geq 1\f$ rad/s frequency. \n
|
|
|
|
|
Parameter must be positive. \n
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
\param[in] ord
|
|
|
|
|
Filter order. \n
|
|
|
|
|
Filter coefficients number equals `ord+1` for numerator and denominator
|
|
|
|
|
of transfer function \f$ H(s) \f$ \n
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
\param[out] b
|
|
|
|
|
Pointer to the vector of transfer function \f$H(s)\f$
|
|
|
|
|
numerator coefficient. \n
|
|
|
|
|
Vector size is `[ord+1 x 1]`. \n
|
|
|
|
|
Memory must be allocated. \n
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
\param[out] a
|
|
|
|
|
Pointer to the vector of transfer function \f$H(s)\f$
|
|
|
|
|
denominator coefficient. \n
|
|
|
|
|
Vector size is `[ord+1 x 1]`. \n
|
|
|
|
|
Memory must be allocated. \n
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
\return
|
|
|
|
|
`RES_OK` if filter coefficients is calculated successfully. \n
|
|
|
|
|
Else \ref ERROR_CODE_GROUP "code error".
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
Example:
|
|
|
|
|
|
|
|
|
|
\include cheby2_ap_test.c
|
|
|
|
|
|
|
|
|
|
Result:
|
|
|
|
|
|
|
|
|
|
\verbatim
|
|
|
|
|
b[ 0] = 0.008 a[ 0] = 0.008
|
|
|
|
|
b[ 1] = 0.000 a[ 1] = 0.068
|
|
|
|
|
b[ 2] = 0.008 a[ 2] = 0.300
|
|
|
|
|
b[ 3] = 0.000 a[ 3] = 0.774
|
|
|
|
|
b[ 4] = 0.001 a[ 4] = 1.000
|
|
|
|
|
\endverbatim
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
In `dat` folder will be created 3 files: \n
|
|
|
|
|
|
|
|
|
|
\verbatim
|
|
|
|
|
cheby2_ap_test_mag.txt magnitude
|
|
|
|
|
cheby2_ap_test_phi.txt phase response
|
|
|
|
|
cheby2_ap_test_tau.txt group delay
|
|
|
|
|
\endverbatim
|
|
|
|
|
|
|
|
|
|
In addition, GNUPLOT will build the following graphs from data stored in files:
|
|
|
|
|
|
|
|
|
|
\image html cheby2_ap_test.png
|
|
|
|
|
|
|
|
|
|
\author Sergey Bakhurin www.dsplib.org
|
|
|
|
|
***************************************************************************** */
|
|
|
|
|
#endif
|
|
|
|
|
#ifdef DOXYGEN_RUSSIAN
|
|
|
|
|
/*! ****************************************************************************
|
|
|
|
|
\ingroup IIR_FILTER_DESIGN_GROUP
|
|
|
|
|
\fn int cheby2_ap(double Rs, int ord, double *b, double *a)
|
|
|
|
|
|
|
|
|
|
\brief
|
|
|
|
|
Расчет передаточной характеристики \f$ H(s) \f$ аналогового
|
|
|
|
|
нормированного ФНЧ Чебышёва второго рода.
|
|
|
|
|
|
|
|
|
|
Функция рассчитывает коэффициенты передаточной характеристики \f$H(s)\f$
|
|
|
|
|
аналогового нормированного ФНЧ Чебышёва второго рода порядка `ord`
|
|
|
|
|
с частотой заграждения 1 рад/с по уровню \f$-R_s\f$ дБ. \n
|
|
|
|
|
|
|
|
|
|
Особенностью фильтра Чебышёва второго рода являются: \n
|
|
|
|
|
1) равноволновые пульсации АЧХ в полосе заграждения. \n
|
|
|
|
|
2) уровень АЧХ \f$H(j\cdot 1) = -R_s\f$ дБ. \n
|
|
|
|
|
|
|
|
|
|
\param[in] Rs
|
|
|
|
|
Уровень подавления в полосе пропускания (дБ). \n
|
|
|
|
|
Значение должно быть положительным. \n
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
\param[in] ord
|
|
|
|
|
Порядок фильтра. \n
|
|
|
|
|
Количество коэффициентов числителя и знаменателя
|
|
|
|
|
передаточной функции \f$H(s)\f$ равно `ord+1`. \n
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
\param[out] b
|
|
|
|
|
Указатель на вектор коэффициентов числителя
|
|
|
|
|
передаточной функции \f$H(s)\f$. \n
|
|
|
|
|
Размер вектора `[ord+1 x 1]`. \n
|
|
|
|
|
Память должна быть выделена. \n
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
\param[out] a
|
|
|
|
|
Указатель на вектор коэффициентов знаменателя
|
|
|
|
|
передаточной функции \f$H(s)\f$. \n
|
|
|
|
|
Размер вектора `[ord+1 x 1]`. \n
|
|
|
|
|
Память должна быть выделена. \n
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
Пример использования функции `cheby1_ap`:
|
|
|
|
|
|
|
|
|
|
\include cheby2_ap_test.c
|
|
|
|
|
|
|
|
|
|
Результат работы программы:
|
|
|
|
|
|
|
|
|
|
\verbatim
|
|
|
|
|
b[ 0] = 0.008 a[ 0] = 0.008
|
|
|
|
|
b[ 1] = 0.000 a[ 1] = 0.068
|
|
|
|
|
b[ 2] = 0.008 a[ 2] = 0.300
|
|
|
|
|
b[ 3] = 0.000 a[ 3] = 0.774
|
|
|
|
|
b[ 4] = 0.001 a[ 4] = 1.000
|
|
|
|
|
\endverbatim
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
В каталоге `dat` будут созданы три файла: \n
|
|
|
|
|
|
|
|
|
|
\verbatim
|
|
|
|
|
cheby2_ap_test_mag.txt АЧХ фильтра
|
|
|
|
|
cheby2_ap_test_phi.txt ФЧХ фильтра
|
|
|
|
|
cheby2_ap_test_tau.txt ГВЗ фильтра
|
|
|
|
|
\endverbatim
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
Кроме того программа GNUPLOT произведет построение следующих графиков
|
|
|
|
|
по сохраненным в файлах данным:
|
|
|
|
|
|
|
|
|
|
\image html cheby2_ap_test.png
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
\return
|
|
|
|
|
`RES_OK` --- фильтр рассчитан успешно. \n
|
|
|
|
|
В противном случае \ref ERROR_CODE_GROUP "код ошибки". \n
|
|
|
|
|
|
|
|
|
|
\author
|
|
|
|
|
Бахурин Сергей
|
|
|
|
|
www.dsplib.org
|
|
|
|
|
***************************************************************************** */
|
|
|
|
|
#endif
|
2018-05-13 13:54:37 +00:00
|
|
|
|
int DSPL_API cheby2_ap(double rs, int ord, double* b, double* a)
|
|
|
|
|
{
|
2020-07-17 18:09:28 +00:00
|
|
|
|
int res;
|
|
|
|
|
complex_t *z = NULL;
|
|
|
|
|
complex_t *p = NULL;
|
|
|
|
|
int nz, np;
|
|
|
|
|
double norm;
|
2018-10-24 17:39:51 +00:00
|
|
|
|
|
|
|
|
|
|
2020-07-17 18:09:28 +00:00
|
|
|
|
if(rs < 0.0)
|
|
|
|
|
return ERROR_FILTER_RP;
|
|
|
|
|
if(ord < 1)
|
|
|
|
|
return ERROR_FILTER_ORD;
|
|
|
|
|
if(!a || !b)
|
|
|
|
|
return ERROR_PTR;
|
2018-10-24 17:39:51 +00:00
|
|
|
|
|
2020-07-17 18:09:28 +00:00
|
|
|
|
z = (complex_t*) malloc(ord*sizeof(complex_t));
|
|
|
|
|
p = (complex_t*) malloc(ord*sizeof(complex_t));
|
2018-10-24 17:39:51 +00:00
|
|
|
|
|
|
|
|
|
|
2020-07-17 18:09:28 +00:00
|
|
|
|
res = cheby2_ap_zp(ord, rs, z, &nz, p, &np);
|
|
|
|
|
if(res != RES_OK)
|
|
|
|
|
goto exit_label;
|
2018-10-24 17:39:51 +00:00
|
|
|
|
|
2020-07-17 18:09:28 +00:00
|
|
|
|
res = filter_zp2ab(z, nz, p, np, ord, b, a);
|
|
|
|
|
if(res != RES_OK)
|
|
|
|
|
goto exit_label;
|
2018-10-24 17:39:51 +00:00
|
|
|
|
|
2020-07-17 18:09:28 +00:00
|
|
|
|
norm = a[0] / b[0];
|
2018-10-24 17:39:51 +00:00
|
|
|
|
|
2020-07-17 18:09:28 +00:00
|
|
|
|
for(nz = 0; nz < ord+1; nz++)
|
|
|
|
|
b[nz]*=norm;
|
2018-10-24 17:39:51 +00:00
|
|
|
|
|
2018-05-13 13:54:37 +00:00
|
|
|
|
exit_label:
|
2020-07-17 18:09:28 +00:00
|
|
|
|
if(z)
|
|
|
|
|
free(z);
|
|
|
|
|
if(p)
|
|
|
|
|
free(p);
|
|
|
|
|
return res;
|
2018-05-13 13:54:37 +00:00
|
|
|
|
}
|
|
|
|
|
|
2018-04-02 20:48:53 +00:00
|
|
|
|
|
2018-05-03 13:20:12 +00:00
|
|
|
|
|
2020-07-23 18:55:02 +00:00
|
|
|
|
#ifdef DOXYGEN_ENGLISH
|
|
|
|
|
|
|
|
|
|
#endif
|
|
|
|
|
#ifdef DOXYGEN_RUSSIAN
|
2018-05-03 13:20:12 +00:00
|
|
|
|
|
2020-07-23 18:55:02 +00:00
|
|
|
|
#endif
|
2019-06-09 12:25:11 +00:00
|
|
|
|
int DSPL_API cheby2_ap_wp1(double rp, double rs, int ord, double* b, double* a)
|
|
|
|
|
{
|
2020-07-17 18:09:28 +00:00
|
|
|
|
int err;
|
|
|
|
|
double es, gp, alpha, beta, y, wp;
|
2019-08-28 18:19:25 +00:00
|
|
|
|
|
2020-07-17 18:09:28 +00:00
|
|
|
|
if(rp <= 0)
|
|
|
|
|
return ERROR_FILTER_RP;
|
2019-08-28 18:19:25 +00:00
|
|
|
|
|
2020-07-17 18:09:28 +00:00
|
|
|
|
err = cheby2_ap(rs, ord, b, a);
|
|
|
|
|
if(err!=RES_OK)
|
|
|
|
|
goto exit_label;
|
2019-08-28 18:19:25 +00:00
|
|
|
|
|
2020-07-17 18:09:28 +00:00
|
|
|
|
es = sqrt(pow(10.0, rs*0.1) - 1.0);
|
|
|
|
|
gp = pow(10.0, -rp*0.05);
|
|
|
|
|
alpha = gp * es / sqrt(1.0 - gp*gp);
|
|
|
|
|
beta = alpha + sqrt(alpha * alpha - 1.0);
|
|
|
|
|
y = log(beta)/ (double)ord;
|
|
|
|
|
wp = 2.0 / (exp(y) + exp(-y));
|
|
|
|
|
|
|
|
|
|
err = low2low(b, a, ord, wp, 1.0, b, a);
|
2019-08-28 18:19:25 +00:00
|
|
|
|
|
2019-06-09 12:25:11 +00:00
|
|
|
|
exit_label:
|
2020-07-17 18:09:28 +00:00
|
|
|
|
return err;
|
2019-06-09 12:25:11 +00:00
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
2020-07-23 18:55:02 +00:00
|
|
|
|
#ifdef DOXYGEN_ENGLISH
|
|
|
|
|
/*! ****************************************************************************
|
|
|
|
|
\ingroup IIR_FILTER_DESIGN_GROUP
|
|
|
|
|
\fn int cheby2_ap_zp(int ord, double rs, complex_t* z, int* nz,
|
|
|
|
|
complex_t* p, int* np)
|
|
|
|
|
|
|
|
|
|
\brief
|
|
|
|
|
Function calculates arrays of zeros and poles for analog normlized lowpass
|
|
|
|
|
Chebyshev type 2 filter transfer function \f$ H(s) \f$ order `ord` .
|
|
|
|
|
|
|
|
|
|
Analog normalized Chebyshev type 2 filter lowpass filter has \f$Rs\f$ dB
|
|
|
|
|
suppression in stopband.
|
|
|
|
|
Also analog normalized Chebyshev type 2 filter magnitude equals \f$-Rs\f$ dB
|
|
|
|
|
for angular frequency \f$\omega = 1\f$ rad/s.
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
\param[in] ord
|
|
|
|
|
Filter order. \n
|
|
|
|
|
Number of zeros and poles of filter can be less or equal `ord`. \n
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
\param[in] rs
|
|
|
|
|
Suppression level in stopband (dB). \n
|
|
|
|
|
This parameter sets filter supression for \f$\omega \geq 1\f$ rad/s frequency. \n
|
|
|
|
|
Parameter must be positive. \n
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
\param[out] z
|
|
|
|
|
Pointer to the \f$ H(s) \f$ zeros array. \n
|
|
|
|
|
Maximum vector size is `[ord x 1]`. \n
|
|
|
|
|
Memory must be allocated for maximum vector size. \n
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
\param[out] nz
|
|
|
|
|
Pointer to the variable which keep number of finite zeros \f$ H(s) \f$. \n
|
|
|
|
|
Number of finite zeros which was calculated and saved in vector `z`. \n
|
|
|
|
|
Pointer cannot be `NULL`. \n
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
\param[out] p
|
|
|
|
|
Pointer to the \f$ H(s) \f$ poles array. \n
|
|
|
|
|
Maximum vector size is `[ord x 1]`. \n
|
|
|
|
|
Memory must be allocated for maximum vector size. \n
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
\param[out] np
|
|
|
|
|
Pointer to the variable which keep number of
|
|
|
|
|
calculated poles of \f$ H(s) \f$. \n
|
|
|
|
|
Pointer cannot be `NULL`. \n
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
\return
|
|
|
|
|
`RES_OK` if zeros and poles is calculated successfully. \n
|
|
|
|
|
Else \ref ERROR_CODE_GROUP "code error".
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
Example of normalized Chebyshev type 2 lowpass filter
|
|
|
|
|
zeros and poles calculation:
|
|
|
|
|
\include cheby2_ap_zp_test.c
|
|
|
|
|
|
|
|
|
|
Result:
|
|
|
|
|
|
|
|
|
|
\verbatim
|
|
|
|
|
Chebyshev type 2 filter zeros: 6
|
|
|
|
|
z[ 0] = 0.000 +1.026 j
|
|
|
|
|
z[ 1] = 0.000 -1.026 j
|
|
|
|
|
z[ 2] = 0.000 +1.279 j
|
|
|
|
|
z[ 3] = 0.000 -1.279 j
|
|
|
|
|
z[ 4] = 0.000 +2.305 j
|
|
|
|
|
z[ 5] = 0.000 -2.305 j
|
|
|
|
|
Chebyshev type 2 filter poles: 7
|
|
|
|
|
p[ 0] = -1.203 +0.000 j
|
|
|
|
|
p[ 1] = -0.113 +0.772 j
|
|
|
|
|
p[ 2] = -0.113 -0.772 j
|
|
|
|
|
p[ 3] = -0.398 +0.781 j
|
|
|
|
|
p[ 4] = -0.398 -0.781 j
|
|
|
|
|
p[ 5] = -0.852 +0.642 j
|
|
|
|
|
p[ 6] = -0.852 -0.642 j
|
|
|
|
|
\endverbatim
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
In `dat` folder will be created `cheby2_ap_z.txt` and
|
|
|
|
|
`cheby2_ap_z.txt` files which keeps zeros and poles vectors. \n
|
|
|
|
|
|
|
|
|
|
In addition, GNUPLOT will build the following graphs
|
|
|
|
|
from data stored in the files:
|
|
|
|
|
|
|
|
|
|
\image html cheby2_ap_zp_test.png
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
\author Sergey Bakhurin www.dsplib.org
|
|
|
|
|
***************************************************************************** */
|
|
|
|
|
#endif
|
|
|
|
|
#ifdef DOXYGEN_RUSSIAN
|
|
|
|
|
/*! ****************************************************************************
|
|
|
|
|
\ingroup IIR_FILTER_DESIGN_GROUP
|
|
|
|
|
\fn int cheby2_ap_zp(int ord, double rs, complex_t* z, int* nz,
|
|
|
|
|
complex_t* p, int* np)
|
|
|
|
|
|
|
|
|
|
\brief
|
|
|
|
|
Расчет массивов нулей и полюсов передаточной функции \f$ H(s) \f$
|
|
|
|
|
аналогового нормированного ФНЧ Чебышёва второго рода.
|
|
|
|
|
|
|
|
|
|
Функция рассчитывает значения нулей и полюсов передаточной функции
|
|
|
|
|
\f$H(s)\f$ аналогового нормированного ФНЧ Чебышёва второго рода порядка `ord` с
|
|
|
|
|
частотой заграждения 1 рад/с по уровню \f$-R_s\f$ дБ. \n
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
\param[in] ord
|
|
|
|
|
Порядок фильтра. \n
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
\param[in] rs
|
|
|
|
|
Уровень подавления АЧХ в полосе загражения (дБ). \n
|
|
|
|
|
Параметр задает уровень подавления сигнала в полосе частот от 1 рад/с и выше. \n
|
|
|
|
|
Значение должно быть положительным. \n
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
\param[out] z
|
|
|
|
|
Указатель на массив комплексных нулей передаточной функции \f$H(s)\f$. \n
|
|
|
|
|
Максимальный размер вектора вектора `[ord x 1]`. \n
|
|
|
|
|
Память должна быть выделена. \n
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
\param[out] nz
|
|
|
|
|
Указатель на переменную количества нулей передаточной функции \f$H(s)\f$. \n
|
|
|
|
|
По данному указателю будет записано количество нулей фильтра, которые были
|
|
|
|
|
рассчитаны и помещены в вектор `z`. \n
|
|
|
|
|
Память должна быть выделена. \n
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
\param[out] p
|
|
|
|
|
Указатель на массив комплексных полюсов передаточной функции \f$H(s)\f$. \n
|
|
|
|
|
Максимальный размер вектора вектора `[ord x 1]`. \n
|
|
|
|
|
Память должна быть выделена. \n
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
\param[out] np
|
|
|
|
|
Указатель на переменную количества полюсов передаточной функции \f$H(s)\f$. \n
|
|
|
|
|
По данному указателю будет записано количество нулей
|
|
|
|
|
фильтра, которые были
|
|
|
|
|
рассчитаны и помещены в вектор `p`. \n
|
|
|
|
|
Память должна быть выделена. \n
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
\return
|
|
|
|
|
`RES_OK` --- массивы нулей и полюсов рассчитаны успешно. \n
|
|
|
|
|
В противном случае \ref ERROR_CODE_GROUP "код ошибки". \n
|
|
|
|
|
|
|
|
|
|
Пример использования функции `cheby2_ap_zp`:
|
|
|
|
|
|
|
|
|
|
Пример программы рассчета нулей и полюсов нормированного
|
|
|
|
|
ФНЧ Чебышева первого рода:
|
|
|
|
|
\include cheby2_ap_zp_test.c
|
|
|
|
|
|
|
|
|
|
Результат выполнения программы:
|
|
|
|
|
|
|
|
|
|
\verbatim
|
|
|
|
|
Chebyshev type 2 filter zeros: 6
|
|
|
|
|
z[ 0] = 0.000 +1.026 j
|
|
|
|
|
z[ 1] = 0.000 -1.026 j
|
|
|
|
|
z[ 2] = 0.000 +1.279 j
|
|
|
|
|
z[ 3] = 0.000 -1.279 j
|
|
|
|
|
z[ 4] = 0.000 +2.305 j
|
|
|
|
|
z[ 5] = 0.000 -2.305 j
|
|
|
|
|
Chebyshev type 2 filter poles: 7
|
|
|
|
|
p[ 0] = -1.203 +0.000 j
|
|
|
|
|
p[ 1] = -0.113 +0.772 j
|
|
|
|
|
p[ 2] = -0.113 -0.772 j
|
|
|
|
|
p[ 3] = -0.398 +0.781 j
|
|
|
|
|
p[ 4] = -0.398 -0.781 j
|
|
|
|
|
p[ 5] = -0.852 +0.642 j
|
|
|
|
|
p[ 6] = -0.852 -0.642 j
|
|
|
|
|
\endverbatim
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
В каталоге `dat` будет создан файлы `cheby2_ap_z.txt` и `cheby2_ap_z.txt`,
|
|
|
|
|
хранящие наборы нулей и полюсов на комплексной плоскости. \n
|
|
|
|
|
|
|
|
|
|
Пакет GNUPLOT произведет построение карты полюсов по
|
|
|
|
|
сохранненным в `dat/cheby2_ap_z.txt` и `dat/cheby2_ap_p.txt` данным:
|
|
|
|
|
|
|
|
|
|
\image html cheby2_ap_zp_test.png
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
\author
|
|
|
|
|
Бахурин Сергей
|
|
|
|
|
www.dsplib.org
|
|
|
|
|
***************************************************************************** */
|
|
|
|
|
#endif
|
2020-04-18 08:09:38 +00:00
|
|
|
|
int DSPL_API cheby2_ap_zp(int ord, double rs, complex_t* z, int* nz,
|
2020-07-23 18:55:02 +00:00
|
|
|
|
complex_t *p, int* np)
|
2018-05-03 13:20:12 +00:00
|
|
|
|
{
|
2020-07-17 18:09:28 +00:00
|
|
|
|
double es;
|
|
|
|
|
int L, r, k;
|
|
|
|
|
double beta;
|
|
|
|
|
int iz, ip;
|
|
|
|
|
|
|
|
|
|
double alpha;
|
|
|
|
|
double chb, shb, sa, ca;
|
|
|
|
|
double ssh2, cch2;
|
|
|
|
|
|
|
|
|
|
if(rs < 0 || rs == 0)
|
|
|
|
|
return ERROR_FILTER_RS;
|
|
|
|
|
if(ord < 1)
|
|
|
|
|
return ERROR_FILTER_ORD;
|
|
|
|
|
if(!z || !p || !nz || !np)
|
|
|
|
|
return ERROR_PTR;
|
|
|
|
|
|
|
|
|
|
es = sqrt(pow(10.0, rs*0.1) - 1.0);
|
|
|
|
|
r = ord % 2;
|
|
|
|
|
L = (int)((ord-r)/2);
|
|
|
|
|
|
|
|
|
|
beta = asinh(es)/(double)ord;
|
|
|
|
|
|
|
|
|
|
chb = cosh(beta);
|
|
|
|
|
shb = sinh(beta);
|
|
|
|
|
|
|
|
|
|
iz = ip = 0;
|
|
|
|
|
|
|
|
|
|
if(r)
|
|
|
|
|
{
|
|
|
|
|
RE(p[0]) = -1.0 / sinh(beta);
|
|
|
|
|
IM(p[0]) = 0.0;
|
|
|
|
|
ip = 1;
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
for(k = 0; k < L; k++)
|
|
|
|
|
{
|
|
|
|
|
alpha = M_PI*(double)(2*k + 1)/(double)(2*ord);
|
|
|
|
|
sa = sin(alpha);
|
|
|
|
|
ca = cos(alpha);
|
|
|
|
|
ssh2 = sa*shb;
|
|
|
|
|
ssh2 *= ssh2;
|
|
|
|
|
|
|
|
|
|
cch2 = ca*chb;
|
|
|
|
|
cch2 *= cch2;
|
|
|
|
|
|
|
|
|
|
RE(z[iz]) = RE(z[iz+1]) = 0.0;
|
|
|
|
|
IM(z[iz]) = 1.0 / ca;
|
|
|
|
|
IM(z[iz+1]) = -IM(z[iz]);
|
|
|
|
|
iz+=2;
|
|
|
|
|
|
|
|
|
|
RE(p[ip]) = RE(p[ip+1]) = -sa*shb / (ssh2 + cch2);
|
|
|
|
|
IM(p[ip]) = ca*chb / (ssh2 + cch2);
|
|
|
|
|
IM(p[ip+1]) = -IM(p[ip]);
|
|
|
|
|
ip+=2;
|
|
|
|
|
}
|
|
|
|
|
*nz = iz;
|
|
|
|
|
*np = ip;
|
|
|
|
|
|
|
|
|
|
return RES_OK;
|
2018-05-03 13:20:12 +00:00
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
2018-05-23 20:36:00 +00:00
|
|
|
|
|
|
|
|
|
|
2020-07-23 18:55:02 +00:00
|
|
|
|
#ifdef DOXYGEN_ENGLISH
|
|
|
|
|
/*! ****************************************************************************
|
|
|
|
|
\ingroup IIR_FILTER_DESIGN_GROUP
|
|
|
|
|
\fn int ellip_ap(double rp, double rs, int ord, double* b, double* a)
|
|
|
|
|
|
|
|
|
|
\brief
|
|
|
|
|
Function calculates the transfer function \f$ H(s) \f$ coefficients of
|
|
|
|
|
analog normalized lowpass elliptic filter order `ord` with passband ripple
|
|
|
|
|
`rp` dB and stopband suppression equals `rs` dB.
|
|
|
|
|
|
|
|
|
|
\param[in] rp
|
|
|
|
|
Magnitude ripple in passband (dB). \n
|
|
|
|
|
This parameter sets maximum filter distortion from 0 to 1 rad/s frequency. \n
|
|
|
|
|
Parameter must be positive. \n
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
\param[in] rs
|
|
|
|
|
Suppression level in stopband (dB). \n
|
|
|
|
|
This parameter sets filter supression for \f$\omega \geq 1\f$ rad/s frequency. \n
|
|
|
|
|
Parameter must be positive. \n
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
\param[in] ord
|
|
|
|
|
Filter order. \n
|
|
|
|
|
Filter coefficients number equals `ord+1` for numerator and denominator
|
|
|
|
|
of transfer function \f$ H(s) \f$ \n
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
\param[out] b
|
|
|
|
|
Pointer to the vector of transfer function \f$H(s)\f$
|
|
|
|
|
numerator coefficient. \n
|
|
|
|
|
Vector size is `[ord+1 x 1]`. \n
|
|
|
|
|
Memory must be allocated. \n
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
\param[out] a
|
|
|
|
|
Pointer to the vector of transfer function \f$H(s)\f$
|
|
|
|
|
denominator coefficient. \n
|
|
|
|
|
Vector size is `[ord+1 x 1]`. \n
|
|
|
|
|
Memory must be allocated. \n
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
\return
|
|
|
|
|
`RES_OK` if filter coefficients is calculated successfully. \n
|
|
|
|
|
Else \ref ERROR_CODE_GROUP "code error".
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
Example:
|
|
|
|
|
|
|
|
|
|
\include ellip_ap_test.c
|
|
|
|
|
|
|
|
|
|
Result:
|
|
|
|
|
|
|
|
|
|
\verbatim
|
|
|
|
|
b[ 0] = 0.268 a[ 0] = 0.301
|
|
|
|
|
b[ 1] = 0.000 a[ 1] = 0.764
|
|
|
|
|
b[ 2] = 0.045 a[ 2] = 1.472
|
|
|
|
|
b[ 3] = 0.000 a[ 3] = 0.948
|
|
|
|
|
b[ 4] = 0.001 a[ 4] = 1.000
|
|
|
|
|
\endverbatim
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
In `dat` folder will be created 3 files: \n
|
|
|
|
|
|
|
|
|
|
\verbatim
|
|
|
|
|
ellip_ap_test_mag.txt magnitude
|
|
|
|
|
ellip_ap_test_phi.txt phase response
|
|
|
|
|
ellip_ap_test_tau.txt group delay
|
|
|
|
|
\endverbatim
|
|
|
|
|
|
|
|
|
|
In addition, GNUPLOT will build the following graphs from data stored in files:
|
|
|
|
|
|
|
|
|
|
\image html ellip_ap_test.png
|
|
|
|
|
|
|
|
|
|
\author Sergey Bakhurin www.dsplib.org
|
|
|
|
|
***************************************************************************** */
|
|
|
|
|
#endif
|
|
|
|
|
#ifdef DOXYGEN_RUSSIAN
|
|
|
|
|
/*! ****************************************************************************
|
|
|
|
|
\ingroup IIR_FILTER_DESIGN_GROUP
|
|
|
|
|
\fn int ellip_ap(double rp, double rs, int ord, double* b, double* a)
|
|
|
|
|
|
|
|
|
|
\brief
|
|
|
|
|
Расчет передаточной характеристики \f$ H(s) \f$ аналогового
|
|
|
|
|
нормированного эллиптического ФНЧ.
|
|
|
|
|
|
|
|
|
|
Функция рассчитывает коэффициенты передаточной характеристики \f$H(s)\f$
|
|
|
|
|
аналогового нормированного эллиптического ФНЧ порядка `ord`
|
|
|
|
|
с частотой среза 1 рад/с по уровню \f$-R_p\f$ дБ. \n
|
|
|
|
|
|
|
|
|
|
Особенностью эллиптического фильтра являются равноволновые пульсации
|
|
|
|
|
АЧХ как в полосе пропускания, так и в полосе заграждения, в результате
|
|
|
|
|
чего обеспечиваеся минимальная переходная полоса фильтра. \n
|
|
|
|
|
|
|
|
|
|
\param[in] rp
|
|
|
|
|
Уровень пульсаций в полосе пропускания (дБ). \n
|
|
|
|
|
Значение должно быть положительным. \n
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
\param[in] rs
|
|
|
|
|
Уровень подавления в полосе заграждения (дБ). \n
|
|
|
|
|
Значение должно быть положительным. \n
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
\param[in] ord
|
|
|
|
|
Порядок фильтра. \n
|
|
|
|
|
Количество коэффициентов числителя и знаменателя
|
|
|
|
|
передаточной функции \f$H(s)\f$ равно `ord+1`. \n
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
\param[out] b
|
|
|
|
|
Указатель на вектор коэффициентов числителя
|
|
|
|
|
передаточной функции \f$H(s)\f$. \n
|
|
|
|
|
Размер вектора `[ord+1 x 1]`. \n
|
|
|
|
|
Память должна быть выделена. \n
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
\param[out] a
|
|
|
|
|
Указатель на вектор коэффициентов знаменателя
|
|
|
|
|
передаточной функции \f$H(s)\f$. \n
|
|
|
|
|
Размер вектора `[ord+1 x 1]`. \n
|
|
|
|
|
Память должна быть выделена. \n
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
Пример использования функции `ellip_ap`:
|
|
|
|
|
|
|
|
|
|
\include ellip_ap_test.c
|
|
|
|
|
|
|
|
|
|
Результат работы программы:
|
|
|
|
|
|
|
|
|
|
\verbatim
|
|
|
|
|
b[ 0] = 0.268 a[ 0] = 0.301
|
|
|
|
|
b[ 1] = 0.000 a[ 1] = 0.764
|
|
|
|
|
b[ 2] = 0.045 a[ 2] = 1.472
|
|
|
|
|
b[ 3] = 0.000 a[ 3] = 0.948
|
|
|
|
|
b[ 4] = 0.001 a[ 4] = 1.000
|
|
|
|
|
\endverbatim
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
В каталоге `dat` будут созданы три файла: \n
|
|
|
|
|
|
|
|
|
|
\verbatim
|
|
|
|
|
ellip_ap_test_mag.txt АЧХ фильтра
|
|
|
|
|
ellip_ap_test_phi.txt ФЧХ фильтра
|
|
|
|
|
ellip_ap_test_tau.txt ГВЗ фильтра
|
|
|
|
|
\endverbatim
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
Кроме того программа GNUPLOT произведет построение следующих графиков
|
|
|
|
|
по сохраненным в файлах данным:
|
|
|
|
|
|
|
|
|
|
\image html ellip_ap_test.png
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
\return
|
|
|
|
|
`RES_OK` --- фильтр рассчитан успешно. \n
|
|
|
|
|
В противном случае \ref ERROR_CODE_GROUP "код ошибки". \n
|
|
|
|
|
|
|
|
|
|
\author
|
|
|
|
|
Бахурин Сергей
|
|
|
|
|
www.dsplib.org
|
|
|
|
|
***************************************************************************** */
|
|
|
|
|
#endif
|
2018-06-05 20:50:12 +00:00
|
|
|
|
int DSPL_API ellip_ap(double rp, double rs, int ord, double* b, double* a)
|
|
|
|
|
{
|
2020-07-17 18:09:28 +00:00
|
|
|
|
int res;
|
|
|
|
|
complex_t *z = NULL;
|
|
|
|
|
complex_t *p = NULL;
|
|
|
|
|
int nz, np;
|
|
|
|
|
double norm, g0;
|
2018-10-24 17:39:51 +00:00
|
|
|
|
|
|
|
|
|
|
2020-07-17 18:09:28 +00:00
|
|
|
|
if(rp < 0.0)
|
|
|
|
|
return ERROR_FILTER_RP;
|
|
|
|
|
if(rs < 0.0)
|
|
|
|
|
return ERROR_FILTER_RS;
|
|
|
|
|
if(ord < 1)
|
|
|
|
|
return ERROR_FILTER_ORD;
|
|
|
|
|
if(!a || !b)
|
|
|
|
|
return ERROR_PTR;
|
2018-10-24 17:39:51 +00:00
|
|
|
|
|
2020-07-17 18:09:28 +00:00
|
|
|
|
z = (complex_t*) malloc(ord*sizeof(complex_t));
|
|
|
|
|
p = (complex_t*) malloc(ord*sizeof(complex_t));
|
2018-10-24 17:39:51 +00:00
|
|
|
|
|
|
|
|
|
|
2020-07-17 18:09:28 +00:00
|
|
|
|
res = ellip_ap_zp(ord, rp, rs, z, &nz, p, &np);
|
|
|
|
|
if(res != RES_OK)
|
|
|
|
|
goto exit_label;
|
2018-10-24 17:39:51 +00:00
|
|
|
|
|
2020-07-17 18:09:28 +00:00
|
|
|
|
res = filter_zp2ab(z, nz, p, np, ord, b, a);
|
|
|
|
|
if(res != RES_OK)
|
|
|
|
|
goto exit_label;
|
2018-10-24 17:39:51 +00:00
|
|
|
|
|
|
|
|
|
|
2020-07-17 18:09:28 +00:00
|
|
|
|
g0 = 1.0;
|
|
|
|
|
if(!(ord % 2))
|
|
|
|
|
{
|
|
|
|
|
g0 = 1.0 / pow(10.0, rp*0.05);
|
|
|
|
|
}
|
2018-10-24 17:39:51 +00:00
|
|
|
|
|
|
|
|
|
|
2020-07-17 18:09:28 +00:00
|
|
|
|
norm = g0 * a[0] / b[0];
|
2018-10-24 17:39:51 +00:00
|
|
|
|
|
2020-07-17 18:09:28 +00:00
|
|
|
|
for(nz = 0; nz < ord+1; nz++)
|
|
|
|
|
b[nz]*=norm;
|
2018-10-24 17:39:51 +00:00
|
|
|
|
|
2020-07-17 18:09:28 +00:00
|
|
|
|
exit_label:
|
|
|
|
|
if(z)
|
|
|
|
|
free(z);
|
|
|
|
|
if(p)
|
|
|
|
|
free(p);
|
|
|
|
|
return res;
|
2018-06-05 20:50:12 +00:00
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
2018-05-23 20:36:00 +00:00
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
2020-07-23 18:55:02 +00:00
|
|
|
|
#ifdef DOXYGEN_ENGLISH
|
|
|
|
|
/*! ****************************************************************************
|
|
|
|
|
\ingroup IIR_FILTER_DESIGN_GROUP
|
|
|
|
|
\fn int ellip_ap_zp(int ord, double rp, double rs, complex_t* z, int* nz,
|
|
|
|
|
complex_t* p, int* np)
|
|
|
|
|
|
|
|
|
|
\brief
|
|
|
|
|
Function calculates arrays of zeros and poles for analog normlized lowpass
|
|
|
|
|
elliptic filter transfer function \f$ H(s) \f$ order `ord` .
|
|
|
|
|
|
|
|
|
|
\param[in] ord
|
|
|
|
|
Filter order. \n
|
|
|
|
|
Number of zeros and poles of filter can be less or equal `ord`. \n
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
\param[in] rp
|
|
|
|
|
Magnitude ripple in passband (dB). \n
|
|
|
|
|
This parameter sets maximum filter distortion from 0 to 1 rad/s frequency. \n
|
|
|
|
|
Parameter must be positive. \n
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
\param[in] rs
|
|
|
|
|
Suppression level in stopband (dB). \n
|
|
|
|
|
This parameter sets filter suppression
|
|
|
|
|
for \f$\omega \geq 1\f$ rad/s frequency. \n
|
|
|
|
|
Parameter must be positive. \n
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
\param[out] z
|
|
|
|
|
Pointer to the \f$ H(s) \f$ zeros array. \n
|
|
|
|
|
Maximum vector size is `[ord x 1]`. \n
|
|
|
|
|
Memory must be allocated for maximum vector size. \n
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
\param[out] nz
|
|
|
|
|
Pointer to the variable which keep number of finite zeros \f$ H(s) \f$. \n
|
|
|
|
|
Number of finite zeros which was calculated and saved in vector `z`. \n
|
|
|
|
|
Pointer cannot be `NULL`. \n
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
\param[out] p
|
|
|
|
|
Pointer to the \f$ H(s) \f$ poles array. \n
|
|
|
|
|
Maximum vector size is `[ord x 1]`. \n
|
|
|
|
|
Memory must be allocated for maximum vector size. \n
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
\param[out] np
|
|
|
|
|
Pointer to the variable which keep number of
|
|
|
|
|
calculated poles of \f$ H(s) \f$. \n
|
|
|
|
|
Pointer cannot be `NULL`. \n
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
\return
|
|
|
|
|
`RES_OK` if zeros and poles is calculated successfully. \n
|
|
|
|
|
Else \ref ERROR_CODE_GROUP "code error".
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
Example of normalized elliptic lowpass filter zeros and poles calculation:
|
|
|
|
|
\include ellip_ap_zp_test.c
|
|
|
|
|
|
|
|
|
|
Result:
|
|
|
|
|
|
|
|
|
|
\verbatim
|
|
|
|
|
Elliptic filter zeros: 6
|
|
|
|
|
z[ 0] = 0.000 +1.053 j
|
|
|
|
|
z[ 1] = 0.000 -1.053 j
|
|
|
|
|
z[ 2] = 0.000 +1.136 j
|
|
|
|
|
z[ 3] = 0.000 -1.136 j
|
|
|
|
|
z[ 4] = 0.000 +1.626 j
|
|
|
|
|
z[ 5] = 0.000 -1.626 j
|
|
|
|
|
Elliptic filter poles: 7
|
|
|
|
|
p[ 0] = -0.358 +0.000 j
|
|
|
|
|
p[ 1] = -0.011 +1.000 j
|
|
|
|
|
p[ 2] = -0.011 -1.000 j
|
|
|
|
|
p[ 3] = -0.060 +0.940 j
|
|
|
|
|
p[ 4] = -0.060 -0.940 j
|
|
|
|
|
p[ 5] = -0.206 +0.689 j
|
|
|
|
|
p[ 6] = -0.206 -0.689 j
|
|
|
|
|
\endverbatim
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
In `dat` folder will be created `ellip_ap_z.txt` and
|
|
|
|
|
`ellip_ap_z.txt` files which keeps zeros and poles vectors. \n
|
|
|
|
|
|
|
|
|
|
In addition, GNUPLOT will build the following graphs
|
|
|
|
|
from data stored in the files:
|
|
|
|
|
|
|
|
|
|
\image html ellip_ap_zp_test.png
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
\author Sergey Bakhurin www.dsplib.org
|
|
|
|
|
***************************************************************************** */
|
|
|
|
|
#endif
|
|
|
|
|
#ifdef DOXYGEN_RUSSIAN
|
|
|
|
|
/*! ****************************************************************************
|
|
|
|
|
\ingroup IIR_FILTER_DESIGN_GROUP
|
|
|
|
|
\fn int ellip_ap_zp(int ord, double rp, double rs, complex_t* z, int* nz,
|
|
|
|
|
complex_t* p, int* np)
|
|
|
|
|
|
|
|
|
|
\brief
|
|
|
|
|
Расчет массивов нулей и полюсов передаточной функции \f$ H(s) \f$
|
|
|
|
|
аналогового нормированного эллиптического ФНЧ.
|
|
|
|
|
|
|
|
|
|
\param[in] ord
|
|
|
|
|
Порядок фильтра. \n
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
\param[in] rp
|
|
|
|
|
Неравномерность АЧХ в полосе пропускания (дБ). \n
|
|
|
|
|
Параметр задает уровень искажений в полосе от 0 до 1 рад/с. \n
|
|
|
|
|
Значение должно быть положительным. \n
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
\param[in] rs
|
|
|
|
|
Уровень подавления АЧХ в полосе загражения (дБ). \n
|
|
|
|
|
Параметр задает уровень подавления сигнала в полосе частот от 1 рад/с и выше. \n
|
|
|
|
|
Значение должно быть положительным. \n
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
\param[out] z
|
|
|
|
|
Указатель на массив комплексных нулей передаточной функции \f$H(s)\f$. \n
|
|
|
|
|
Максимальный размер вектора вектора `[ord x 1]`. \n
|
|
|
|
|
Память должна быть выделена. \n
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
\param[out] nz
|
|
|
|
|
Указатель на переменную количества нулей передаточной функции \f$H(s)\f$. \n
|
|
|
|
|
По данному указателю будет записано количество нулей фильтра, которые были
|
|
|
|
|
рассчитаны и помещены в вектор `z`. \n
|
|
|
|
|
Память должна быть выделена. \n
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
\param[out] p
|
|
|
|
|
Указатель на массив комплексных полюсов передаточной функции \f$H(s)\f$. \n
|
|
|
|
|
Максимальный размер вектора вектора `[ord x 1]`. \n
|
|
|
|
|
Память должна быть выделена. \n
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
\param[out] np
|
|
|
|
|
Указатель на переменную количества полюсов передаточной функции \f$H(s)\f$. \n
|
|
|
|
|
По данному указателю будет записано количество нулей
|
|
|
|
|
фильтра, которые были
|
|
|
|
|
рассчитаны и помещены в вектор `p`. \n
|
|
|
|
|
Память должна быть выделена. \n
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
\return
|
|
|
|
|
`RES_OK` --- массивы нулей и полюсов рассчитаны успешно. \n
|
|
|
|
|
В противном случае \ref ERROR_CODE_GROUP "код ошибки". \n
|
|
|
|
|
|
|
|
|
|
Пример использования функции `cheby2_ap_zp`:
|
|
|
|
|
|
|
|
|
|
Пример программы рассчета нулей и полюсов нормированного
|
|
|
|
|
эллиптического ФНЧ :
|
|
|
|
|
\include ellip_ap_zp_test.c
|
|
|
|
|
|
|
|
|
|
Результат выполнения программы:
|
|
|
|
|
|
|
|
|
|
\verbatim
|
|
|
|
|
Elliptic filter zeros: 6
|
|
|
|
|
z[ 0] = 0.000 +1.053 j
|
|
|
|
|
z[ 1] = 0.000 -1.053 j
|
|
|
|
|
z[ 2] = 0.000 +1.136 j
|
|
|
|
|
z[ 3] = 0.000 -1.136 j
|
|
|
|
|
z[ 4] = 0.000 +1.626 j
|
|
|
|
|
z[ 5] = 0.000 -1.626 j
|
|
|
|
|
Elliptic filter poles: 7
|
|
|
|
|
p[ 0] = -0.358 +0.000 j
|
|
|
|
|
p[ 1] = -0.011 +1.000 j
|
|
|
|
|
p[ 2] = -0.011 -1.000 j
|
|
|
|
|
p[ 3] = -0.060 +0.940 j
|
|
|
|
|
p[ 4] = -0.060 -0.940 j
|
|
|
|
|
p[ 5] = -0.206 +0.689 j
|
|
|
|
|
p[ 6] = -0.206 -0.689 j
|
|
|
|
|
\endverbatim
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
В каталоге `dat` будет создан файлы `ellip_ap_z.txt` и `ellip_ap_z.txt`,
|
|
|
|
|
хранящие наборы нулей и полюсов на комплексной плоскости. \n
|
|
|
|
|
|
|
|
|
|
Пакет GNUPLOT произведет построение карты полюсов по
|
|
|
|
|
сохранненным в `dat/ellip_ap_z.txt` и `dat/ellip_ap_p.txt` данным:
|
|
|
|
|
|
|
|
|
|
\image html ellip_ap_zp_test.png
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
\author
|
|
|
|
|
Бахурин Сергей
|
|
|
|
|
www.dsplib.org
|
|
|
|
|
***************************************************************************** */
|
|
|
|
|
#endif
|
2018-10-24 17:39:51 +00:00
|
|
|
|
int DSPL_API ellip_ap_zp(int ord, double rp, double rs,
|
2020-07-23 18:55:02 +00:00
|
|
|
|
complex_t* z, int* nz, complex_t* p, int* np)
|
2018-05-23 20:36:00 +00:00
|
|
|
|
{
|
2020-07-17 18:09:28 +00:00
|
|
|
|
double es, ep;
|
|
|
|
|
int L, r, n, res;
|
|
|
|
|
int iz, ip;
|
|
|
|
|
double ke, k, u, t;
|
|
|
|
|
complex_t tc, v0, jv0;
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
if(rp < 0 || rp == 0)
|
|
|
|
|
return ERROR_FILTER_RP;
|
|
|
|
|
if(rs < 0 || rs == 0)
|
|
|
|
|
return ERROR_FILTER_RS;
|
|
|
|
|
if(ord < 1)
|
|
|
|
|
return ERROR_FILTER_ORD;
|
|
|
|
|
if(!z || !p || !nz || !np)
|
|
|
|
|
return ERROR_PTR;
|
|
|
|
|
|
|
|
|
|
es = sqrt(pow(10.0, rs*0.1) - 1.0);
|
|
|
|
|
ep = sqrt(pow(10.0, rp*0.1) - 1.0);
|
|
|
|
|
ke = ep / es;
|
|
|
|
|
|
|
|
|
|
r = ord % 2;
|
|
|
|
|
L = (int)((ord-r)/2);
|
|
|
|
|
|
|
|
|
|
res = ellip_modulareq(rp, rs, ord, &k);
|
|
|
|
|
if(res != RES_OK)
|
|
|
|
|
return res;
|
|
|
|
|
// v0
|
|
|
|
|
RE(tc) = 0.0;
|
|
|
|
|
IM(tc) = 1.0 / ep;
|
2018-10-24 17:39:51 +00:00
|
|
|
|
|
2020-07-17 18:09:28 +00:00
|
|
|
|
ellip_asn_cmplx(&tc, 1, ke, &v0);
|
2018-10-24 17:39:51 +00:00
|
|
|
|
|
2020-07-17 18:09:28 +00:00
|
|
|
|
t = RE(v0);
|
|
|
|
|
RE(v0) = IM(v0) / (double)ord;
|
|
|
|
|
IM(v0) = -t / (double)ord;
|
2018-10-24 17:39:51 +00:00
|
|
|
|
|
2020-07-17 18:09:28 +00:00
|
|
|
|
RE(jv0) = -IM(v0);
|
|
|
|
|
IM(jv0) = RE(v0);
|
2018-10-24 17:39:51 +00:00
|
|
|
|
|
2020-07-17 18:09:28 +00:00
|
|
|
|
iz = ip = 0;
|
2018-10-24 17:39:51 +00:00
|
|
|
|
|
2020-07-17 18:09:28 +00:00
|
|
|
|
if(r)
|
|
|
|
|
{
|
|
|
|
|
res = ellip_sn_cmplx(&jv0, 1, k, &tc);
|
|
|
|
|
if(res != RES_OK)
|
|
|
|
|
return res;
|
|
|
|
|
RE(p[0]) = -IM(tc);
|
|
|
|
|
IM(p[0]) = RE(tc);
|
|
|
|
|
ip = 1;
|
|
|
|
|
}
|
2018-10-24 17:39:51 +00:00
|
|
|
|
|
2020-07-17 18:09:28 +00:00
|
|
|
|
for(n = 0; n < L; n++)
|
|
|
|
|
{
|
|
|
|
|
u = (double)(2 * n + 1)/(double)ord;
|
2018-10-24 17:39:51 +00:00
|
|
|
|
|
2020-07-17 18:09:28 +00:00
|
|
|
|
res = ellip_cd(& u, 1, k, &t);
|
|
|
|
|
if(res != RES_OK)
|
|
|
|
|
return res;
|
2018-10-24 17:39:51 +00:00
|
|
|
|
|
2020-07-17 18:09:28 +00:00
|
|
|
|
RE(z[iz]) = RE(z[iz+1]) = 0.0;
|
|
|
|
|
IM(z[iz]) = 1.0/(k*t);
|
|
|
|
|
IM(z[iz+1]) = -1.0/(k*t);
|
|
|
|
|
iz+=2;
|
2018-10-24 17:39:51 +00:00
|
|
|
|
|
2020-07-17 18:09:28 +00:00
|
|
|
|
RE(tc) = u - RE(jv0);
|
|
|
|
|
IM(tc) = - IM(jv0);
|
2018-10-24 17:39:51 +00:00
|
|
|
|
|
2020-07-17 18:09:28 +00:00
|
|
|
|
res = ellip_cd_cmplx(&tc, 1, k, p+ip+1);
|
|
|
|
|
if(res != RES_OK)
|
|
|
|
|
return res;
|
2018-10-24 17:39:51 +00:00
|
|
|
|
|
2020-07-17 18:09:28 +00:00
|
|
|
|
RE(p[ip]) = -IM(p[ip+1]);
|
|
|
|
|
IM(p[ip]) = RE(p[ip+1]);
|
2018-10-24 17:39:51 +00:00
|
|
|
|
|
2020-07-17 18:09:28 +00:00
|
|
|
|
RE(p[ip+1]) = RE(p[ip]);
|
|
|
|
|
IM(p[ip+1]) = -IM(p[ip]);
|
2018-10-24 17:39:51 +00:00
|
|
|
|
|
2020-07-17 18:09:28 +00:00
|
|
|
|
ip+=2;
|
|
|
|
|
}
|
|
|
|
|
*nz = iz;
|
|
|
|
|
*np = ip;
|
2018-10-24 17:39:51 +00:00
|
|
|
|
|
2020-07-17 18:09:28 +00:00
|
|
|
|
return RES_OK;
|
2018-05-23 20:36:00 +00:00
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
2020-07-23 18:55:02 +00:00
|
|
|
|
#ifdef DOXYGEN_ENGLISH
|
|
|
|
|
/*! ****************************************************************************
|
|
|
|
|
\ingroup IIR_FILTER_DESIGN_GROUP
|
|
|
|
|
\fn int filter_zp2ab(complex_t *z, int nz, complex_t *p, int np, int ord,
|
|
|
|
|
double* b, double* a)
|
|
|
|
|
\brief
|
|
|
|
|
Function recalculates complex zeros and poles of transfer function \f$ H(s) \f$
|
|
|
|
|
to the coefficients of \f$ H(s) \f$ numerator and denominator polynomials.
|
|
|
|
|
|
|
|
|
|
Transfer function can we described as:
|
|
|
|
|
\f[
|
|
|
|
|
H(s) =
|
|
|
|
|
\frac{\sum\limits_{n = 0}^{N_z} b_n s^n}{\sum\limits_{m = 0}^{N_p} a_m s^m} =
|
|
|
|
|
\frac{\prod\limits_{n = 0}^{N_z}(s-z_n)}{\prod\limits_{m = 0}^{N_p} (s-p_m)}
|
|
|
|
|
\f]
|
|
|
|
|
|
|
|
|
|
\param[in] z
|
|
|
|
|
Pointer to the vector of transfer function zeros. \n
|
|
|
|
|
Vector size is `[nz x 1]`. \n
|
|
|
|
|
Pointer can be `NULL` if filter has no finite zeros (`nz=0`). \n
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
\param[in] nz
|
|
|
|
|
Number of fitite zeros (can be zero). \n
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
\param[in] p
|
|
|
|
|
Pointer to the vector of transfer function poles. \n
|
|
|
|
|
Vector size is `[np x 1]`. \n
|
|
|
|
|
This pointer cannot be `NULL`. \n
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
\param[in] np
|
|
|
|
|
Size of vector of transfer function poles (`p` vector size). \n
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
\param[in] ord
|
|
|
|
|
Filter order. \n
|
|
|
|
|
Number of \f$H(s)\f$ numerator and denominator coefficients equals `ord+1`. \n
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
\param[out] b
|
|
|
|
|
Pointer to the vector of transfer function \f$H(s)\f$
|
|
|
|
|
numerator coefficient. \n
|
|
|
|
|
Vector size is `[ord+1 x 1]`. \n
|
|
|
|
|
Memory must be allocated. \n
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
\param[out] a
|
|
|
|
|
Pointer to the vector of transfer function \f$H(s)\f$
|
|
|
|
|
denominator coefficient. \n
|
|
|
|
|
Vector size is `[ord+1 x 1]`. \n
|
|
|
|
|
Memory must be allocated. \n
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
\return
|
|
|
|
|
`RES_OK` if filter coefficients is calculated successfully. \n
|
|
|
|
|
Else \ref ERROR_CODE_GROUP "code error".
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
\note
|
|
|
|
|
Function calculates real `b` and `a` coefficients of \f$H(s)\f$.
|
|
|
|
|
It means that zeros and poles vectors must have real values or conjugate pairs
|
|
|
|
|
to get zeros image part of `b` and `a` coefficients. This function ignores
|
|
|
|
|
image part of `b` and `a` coeeffitients if the requirements for zeros
|
|
|
|
|
and poles are not fulfilled.
|
|
|
|
|
|
|
|
|
|
\author Sergey Bakhurin www.dsplib.org
|
|
|
|
|
***************************************************************************** */
|
|
|
|
|
#endif
|
|
|
|
|
#ifdef DOXYGEN_RUSSIAN
|
|
|
|
|
/*! ****************************************************************************
|
|
|
|
|
\ingroup IIR_FILTER_DESIGN_GROUP
|
|
|
|
|
\fn int filter_zp2ab(complex_t *z, int nz, complex_t *p, int np, int ord,
|
|
|
|
|
double* b, double* a)
|
|
|
|
|
\brief Функция пересчета нулей и полюсов аналогового фильтра в коэффициенты
|
|
|
|
|
передаточной характеристики \f$ H(s) \f$
|
|
|
|
|
|
|
|
|
|
\f[
|
|
|
|
|
H(s) =
|
|
|
|
|
\frac{\sum_{n = 0}^{N_z} b_n \cdot s^n}{\sum_{m = 0}^{N_p} a_m \cdot s^m} =
|
|
|
|
|
\frac{\prod_{n = 0}^{N_z}(s-z_n)}{\prod_{m = 0}^{N_p} (s-p_m)}
|
|
|
|
|
\f]
|
|
|
|
|
|
|
|
|
|
\param[in] z
|
|
|
|
|
Указатель на массив нулей передаточной характеристики. \n
|
|
|
|
|
Размер вектора `[nz x 1]`. \n
|
|
|
|
|
Указатель может быть `NULL` если фильтр не имеет конечных нулей (`nz=0`). \n
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
\param[in] nz
|
|
|
|
|
Размер вектора нулей передаточной характеристики (может быть равен 0). \n
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
\param[in] p
|
|
|
|
|
Указатель на массив полюсов передаточной характеристики. \n
|
|
|
|
|
Размер вектора `[np x 1]`. \n
|
|
|
|
|
Указатель не может быть `NULL`. \n
|
|
|
|
|
Память должна быть выделена. \n
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
\param[in] np
|
|
|
|
|
Размер вектора полюсов передаточной характеристики (не может быть равен 0). \n
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
\param[in] ord
|
|
|
|
|
Порядок фильтра для которого рассчитаны нули и полюса. \n
|
|
|
|
|
Количество коэффициентов числителя и знаменателя
|
|
|
|
|
передаточной функции \f$H(s)\f$ равно `ord+1`. \n \n
|
|
|
|
|
|
|
|
|
|
\param[out] b
|
|
|
|
|
Указатель на вектор коэффициентов числителя передаточной функции \f$H(s)\f$. \n
|
|
|
|
|
Размер вектора `[ord+1 x 1]`. \n
|
|
|
|
|
Память должна быть выделена. \n
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
\param[out] a
|
|
|
|
|
Указатель на вектор коэффициентов знаменателя
|
|
|
|
|
передаточной функции \f$H(s)\f$. \n
|
|
|
|
|
Размер вектора `[ord+1 x 1]`. \n
|
|
|
|
|
Память должна быть выделена. \n
|
|
|
|
|
\n
|
|
|
|
|
|
|
|
|
|
\return
|
|
|
|
|
`RES_OK` --- пересчет произведен успешно. \n
|
|
|
|
|
В противном случае \ref ERROR_CODE_GROUP "код ошибки". \n
|
|
|
|
|
|
|
|
|
|
\note
|
|
|
|
|
Функция возвращает вещественные значения коэффициентов `b` и `a`
|
|
|
|
|
передаточной функции. Это означает, что вектора нулей и полюсов
|
|
|
|
|
должны хранить вещественные значения или комплексно-сопряженные пары
|
|
|
|
|
нулей и полюсов, потому что мнимая часть коэффициентов `b` и `a`
|
|
|
|
|
игнорируется и не сохраняется.
|
|
|
|
|
|
|
|
|
|
\author
|
|
|
|
|
Бахурин Сергей
|
|
|
|
|
www.dsplib.org
|
|
|
|
|
***************************************************************************** */
|
|
|
|
|
#endif
|
2020-04-18 08:09:38 +00:00
|
|
|
|
int DSPL_API filter_zp2ab(complex_t* z, int nz, complex_t* p, int np,
|
2020-07-23 18:55:02 +00:00
|
|
|
|
int ord, double* b, double* a)
|
2018-04-02 20:48:53 +00:00
|
|
|
|
{
|
2020-07-17 18:09:28 +00:00
|
|
|
|
complex_t *acc = NULL;
|
|
|
|
|
int res;
|
|
|
|
|
|
|
|
|
|
if(!z || !p || !b || !a)
|
|
|
|
|
return ERROR_PTR;
|
|
|
|
|
if(nz < 0 || np < 0)
|
|
|
|
|
return ERROR_SIZE;
|
|
|
|
|
if(nz > ord || np > ord)
|
|
|
|
|
return ERROR_POLY_ORD;
|
|
|
|
|
|
|
|
|
|
acc = (complex_t*) malloc((ord+1) * sizeof(complex_t));
|
|
|
|
|
res = poly_z2a_cmplx(z, nz, ord, acc);
|
|
|
|
|
if(res != RES_OK)
|
|
|
|
|
goto exit_label;
|
2018-10-24 17:39:51 +00:00
|
|
|
|
|
2020-07-17 18:09:28 +00:00
|
|
|
|
res = cmplx2re(acc, ord+1, b, NULL);
|
|
|
|
|
if(res != RES_OK)
|
|
|
|
|
goto exit_label;
|
2018-04-02 20:48:53 +00:00
|
|
|
|
|
2020-07-17 18:09:28 +00:00
|
|
|
|
res = poly_z2a_cmplx(p, np, ord, acc);
|
|
|
|
|
if(res != RES_OK)
|
|
|
|
|
goto exit_label;
|
2018-04-02 20:48:53 +00:00
|
|
|
|
|
2020-07-17 18:09:28 +00:00
|
|
|
|
res = cmplx2re(acc, ord+1, a, NULL);
|
|
|
|
|
if(res != RES_OK)
|
|
|
|
|
goto exit_label;
|
2018-04-02 20:48:53 +00:00
|
|
|
|
|
2018-10-24 17:39:51 +00:00
|
|
|
|
exit_label:
|
2020-07-17 18:09:28 +00:00
|
|
|
|
if(acc)
|
|
|
|
|
free(acc);
|
|
|
|
|
return res;
|
2018-04-02 20:48:53 +00:00
|
|
|
|
|
2018-10-24 17:39:51 +00:00
|
|
|
|
}
|
2018-04-02 20:48:53 +00:00
|
|
|
|
|