mirror of
https://github.com/f4exb/sdrangel.git
synced 2024-11-14 12:22:00 -05:00
89 lines
3.0 KiB
C++
89 lines
3.0 KiB
C++
///////////////////////////////////////////////////////////////////////////////////
|
|
// Copyright (C) 2012 maintech GmbH, Otto-Hahn-Str. 15, 97204 Hoechberg, Germany //
|
|
// written by Christian Daniel //
|
|
// Copyright (C) 2014 John Greb <hexameron@spam.no> //
|
|
// Copyright (C) 2015, 2019 Edouard Griffiths, F4EXB <f4exb06@gmail.com> //
|
|
// //
|
|
// This program 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 as version 3 of the License, or //
|
|
// (at your option) any later version. //
|
|
// //
|
|
// This program 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 V3 for more details. //
|
|
// //
|
|
// You should have received a copy of the GNU General Public License //
|
|
// along with this program. If not, see <http://www.gnu.org/licenses/>. //
|
|
///////////////////////////////////////////////////////////////////////////////////
|
|
|
|
#include <QDebug>
|
|
#include "dsp/filterrc.h"
|
|
|
|
// Construct 1st order low-pass IIR filter.
|
|
LowPassFilterRC::LowPassFilterRC(Real timeconst) :
|
|
m_timeconst(timeconst),
|
|
m_y1(0)
|
|
{
|
|
m_a1 = - exp(-1/m_timeconst);
|
|
m_b0 = 1 + m_a1;
|
|
}
|
|
|
|
// Reconfigure
|
|
void LowPassFilterRC::configure(Real timeconst)
|
|
{
|
|
m_timeconst = timeconst;
|
|
m_y1 = 0;
|
|
m_a1 = - exp(-1/m_timeconst);
|
|
m_b0 = 1 + m_a1;
|
|
|
|
qDebug() << "LowPassFilterRC::configure: t: " << m_timeconst
|
|
<< " a1: " << m_a1
|
|
<< " b0: " << m_b0;
|
|
}
|
|
|
|
// Process samples.
|
|
void LowPassFilterRC::process(const Real& sample_in, Real& sample_out)
|
|
{
|
|
/*
|
|
* Continuous domain:
|
|
* H(s) = 1 / (1 - s * timeconst)
|
|
*
|
|
* Discrete domain:
|
|
* H(z) = (1 - exp(-1/timeconst)) / (1 - exp(-1/timeconst) / z)
|
|
*/
|
|
|
|
m_y1 = (sample_in * m_b0) - (m_y1 * m_a1);
|
|
sample_out = m_y1;
|
|
}
|
|
|
|
// Construct 1st order high-pass IIR filter.
|
|
HighPassFilterRC::HighPassFilterRC(Real timeconst) :
|
|
m_timeconst(timeconst),
|
|
m_y1(0)
|
|
{
|
|
m_a1 = 1 - exp(-1/m_timeconst);
|
|
m_b0 = 1 + m_a1;
|
|
}
|
|
|
|
// Reconfigure
|
|
void HighPassFilterRC::configure(Real timeconst)
|
|
{
|
|
m_timeconst = timeconst;
|
|
m_y1 = 0;
|
|
m_a1 = 1 - exp(-1/m_timeconst);
|
|
m_b0 = 1 + m_a1;
|
|
|
|
qDebug() << "HighPassFilterRC::configure: t: " << m_timeconst
|
|
<< " a1: " << m_a1
|
|
<< " b0: " << m_b0;
|
|
}
|
|
|
|
// Process samples.
|
|
void HighPassFilterRC::process(const Real& sample_in, Real& sample_out)
|
|
{
|
|
m_y1 = (sample_in * m_b0) - (m_y1 * m_a1);
|
|
sample_out = m_y1;
|
|
}
|