mirror of
https://github.com/f4exb/sdrangel.git
synced 2024-11-22 16:08:39 -05:00
149 lines
4.2 KiB
C++
149 lines
4.2 KiB
C++
///////////////////////////////////////////////////////////////////////////////////
|
|
// Copyright (C) 2023 Edouard Griffiths, F4EXB <f4exb06@gmail.com> //
|
|
// //
|
|
// Helper class for noise reduction //
|
|
// //
|
|
// 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 <algorithm>
|
|
#include <numeric>
|
|
|
|
#include <QDebug>
|
|
|
|
#include "fftnr.h"
|
|
|
|
FFTNoiseReduction::FFTNoiseReduction(int len) :
|
|
m_flen(len)
|
|
{
|
|
m_scheme = SchemeAverage;
|
|
m_mags = new float[m_flen];
|
|
m_tmp = new float[m_flen];
|
|
m_aboveAvgFactor = 1.0;
|
|
m_sigmaFactor = 1.0;
|
|
m_nbPeaks = m_flen;
|
|
}
|
|
|
|
FFTNoiseReduction::~FFTNoiseReduction()
|
|
{
|
|
delete[] m_mags;
|
|
delete[] m_tmp;
|
|
}
|
|
|
|
void FFTNoiseReduction::init()
|
|
{
|
|
std::fill(m_mags, m_mags + m_flen, 0);
|
|
std::fill(m_tmp, m_tmp + m_flen, 0);
|
|
m_magAvg = 0;
|
|
}
|
|
|
|
void FFTNoiseReduction::push(cmplx data, int index)
|
|
{
|
|
m_mags[index] = std::abs(data);
|
|
|
|
if ((m_scheme == SchemeAverage) || (m_scheme == SchemeAvgStdDev)) {
|
|
m_magAvg += m_mags[index];
|
|
}
|
|
}
|
|
|
|
void FFTNoiseReduction::calc()
|
|
{
|
|
if (m_scheme == SchemeAverage)
|
|
{
|
|
m_magAvg /= m_flen;
|
|
m_magAvg = m_expFilter.push(m_magAvg);
|
|
}
|
|
if (m_scheme == SchemeAvgStdDev)
|
|
{
|
|
m_magAvg /= m_flen;
|
|
|
|
auto variance_func = [this](float accumulator, const float& val) {
|
|
return accumulator + ((val - m_magAvg)*(val - m_magAvg) / (m_flen - 1));
|
|
};
|
|
|
|
float var = std::accumulate(m_mags, m_mags + m_flen, 0.0, variance_func);
|
|
m_magThr = (m_sigmaFactor/2.0)*std::sqrt(var) + m_magAvg;
|
|
m_magThr = m_expFilter.push(m_magThr);
|
|
}
|
|
else if (m_scheme == SchemePeaks)
|
|
{
|
|
std::copy(m_mags, m_mags + m_flen, m_tmp);
|
|
std::sort(m_tmp, m_tmp + m_flen);
|
|
m_magThr = m_tmp[m_flen - m_nbPeaks];
|
|
}
|
|
}
|
|
|
|
bool FFTNoiseReduction::cut(int index)
|
|
{
|
|
if (m_scheme == SchemeAverage)
|
|
{
|
|
return m_mags[index] < m_aboveAvgFactor * m_magAvg;
|
|
}
|
|
else if ((m_scheme == SchemePeaks) || (m_scheme == SchemeAvgStdDev))
|
|
{
|
|
return m_mags[index] < m_magThr;
|
|
}
|
|
|
|
return false;
|
|
}
|
|
|
|
void FFTNoiseReduction::setScheme(Scheme scheme)
|
|
{
|
|
if (m_scheme != scheme) {
|
|
m_expFilter.reset();
|
|
}
|
|
|
|
m_scheme = scheme;
|
|
}
|
|
|
|
FFTNoiseReduction::ExponentialFilter::ExponentialFilter()
|
|
{
|
|
m_alpha = 1.0;
|
|
m_init = true;
|
|
}
|
|
|
|
float FFTNoiseReduction::ExponentialFilter::push(float newValue)
|
|
{
|
|
if (m_init)
|
|
{
|
|
m_prev = newValue;
|
|
m_init = false;
|
|
}
|
|
|
|
if (m_alpha == 1.0)
|
|
{
|
|
m_prev = newValue;
|
|
return newValue;
|
|
}
|
|
else
|
|
{
|
|
float result = m_alpha*m_prev + (1.0 - m_alpha)*newValue;
|
|
m_prev = result;
|
|
return result;
|
|
}
|
|
}
|
|
|
|
void FFTNoiseReduction::ExponentialFilter::reset()
|
|
{
|
|
m_init = true;
|
|
}
|
|
|
|
void FFTNoiseReduction::ExponentialFilter::setAlpha(float alpha)
|
|
{
|
|
m_alpha = alpha < 0.0f ? 0.0f : alpha > 1.0f ? 1.0f : alpha;
|
|
qDebug("FFTNoiseReduction::ExponentialFilter::setAlpha: %f", m_alpha);
|
|
m_init = true;
|
|
}
|
|
|