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sdrangel/sdrbase/dsp/afsquelch.cpp

276 lines
6.9 KiB
C++

///////////////////////////////////////////////////////////////////////////////////
// Copyright (C) 2015-2019 Edouard Griffiths, F4EXB <f4exb06@gmail.com> //
// Copyright (C) 2020 Kacper Michajłow <kasper93@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 <cmath>
#include "dsp/afsquelch.h"
AFSquelch::AFSquelch() :
m_nbAvg(128),
m_N(24),
m_sampleRate(48000),
m_samplesProcessed(0),
m_samplesAvgProcessed(0),
m_maxPowerIndex(0),
m_nTones(2),
m_samplesAttack(0),
m_attackCount(0),
m_samplesDecay(0),
m_decayCount(0),
m_squelchCount(0),
m_isOpen(false),
m_threshold(0.0)
{
m_k = new double[m_nTones];
m_coef = new double[m_nTones];
m_toneSet = new double[m_nTones];
m_u0 = new double[m_nTones];
m_u1 = new double[m_nTones];
m_power = new double[m_nTones];
m_movingAverages.resize(m_nTones, MovingAverage<double>(m_nbAvg, 0.0f));
for (unsigned int j = 0; j < m_nTones; ++j)
{
m_toneSet[j] = j == 0 ? 1000.0 : 6000.0;
m_k[j] = ((double)m_N * m_toneSet[j]) / (double) m_sampleRate;
m_coef[j] = 2.0 * cos((2.0 * M_PI * m_toneSet[j])/(double) m_sampleRate);
m_u0[j] = 0.0;
m_u1[j] = 0.0;
m_power[j] = 0.0;
m_movingAverages[j].fill(0.0);
}
}
AFSquelch::~AFSquelch()
{
delete[] m_k;
delete[] m_coef;
delete[] m_toneSet;
delete[] m_u0;
delete[] m_u1;
delete[] m_power;
}
void AFSquelch::setCoefficients(
unsigned int N,
unsigned int nbAvg,
unsigned int sampleRate,
unsigned int samplesAttack,
unsigned int samplesDecay,
const double *tones)
{
m_N = N; // save the basic parameters for use during analysis
m_nbAvg = nbAvg;
m_sampleRate = sampleRate;
m_samplesAttack = samplesAttack;
m_samplesDecay = samplesDecay;
m_movingAverages.resize(m_nTones, MovingAverage<double>(m_nbAvg, 0.0));
m_samplesProcessed = 0;
m_samplesAvgProcessed = 0;
m_maxPowerIndex = 0;
m_attackCount = 0;
m_decayCount = 0;
m_squelchCount = 0;
m_isOpen = false;
m_threshold = 0.0;
// for each of the frequencies (tones) of interest calculate
// k and the associated filter coefficient as per the Goertzel
// algorithm. Note: we are using a real value (as opposed to
// an integer as described in some references. k is retained
// for later display. The tone set is specified in the
// constructor. Notice that the resulting coefficients are
// independent of N.
for (unsigned int j = 0; j < m_nTones; ++j)
{
m_toneSet[j] = tones[j] < ((double) m_sampleRate) * 0.4 ? tones[j] : ((double) m_sampleRate) * 0.4; // guarantee 80% Nyquist rate
m_k[j] = ((double)m_N * m_toneSet[j]) / (double)m_sampleRate;
m_coef[j] = 2.0 * cos((2.0 * M_PI * m_toneSet[j])/(double)m_sampleRate);
m_u0[j] = 0.0;
m_u1[j] = 0.0;
m_power[j] = 0.0;
m_movingAverages[j].fill(0.0);
}
}
// Analyze an input signal
bool AFSquelch::analyze(double sample)
{
feedback(sample); // Goertzel feedback
if (m_samplesProcessed < m_N) // completed a block of N
{
m_samplesProcessed++;
return false;
}
else
{
feedForward(); // calculate the power at each tone
m_samplesProcessed = 0;
if (m_samplesAvgProcessed < m_nbAvg)
{
m_samplesAvgProcessed++;
return false;
}
else
{
return true; // have a result
}
}
}
void AFSquelch::feedback(double in)
{
double t;
// feedback for each tone
for (unsigned int j = 0; j < m_nTones; ++j)
{
t = m_u0[j];
m_u0[j] = in + (m_coef[j] * m_u0[j]) - m_u1[j];
m_u1[j] = t;
}
}
void AFSquelch::feedForward()
{
for (unsigned int j = 0; j < m_nTones; ++j)
{
m_power[j] = (m_u0[j] * m_u0[j]) + (m_u1[j] * m_u1[j]) - (m_coef[j] * m_u0[j] * m_u1[j]);
m_movingAverages[j].feed(m_power[j]);
m_u0[j] = 0.0;
m_u1[j] = 0.0; // reset for next block.
}
evaluate();
}
void AFSquelch::reset()
{
for (unsigned int j = 0; j < m_nTones; ++j)
{
m_u0[j] = 0.0;
m_u1[j] = 0.0;
m_power[j] = 0.0;
m_movingAverages[j].fill(0.0);
}
m_samplesProcessed = 0;
m_maxPowerIndex = 0;
m_isOpen = false;
}
bool AFSquelch::evaluate()
{
double maxPower = 0.0;
double minPower;
int minIndex = 0, maxIndex = 0;
for (unsigned int j = 0; j < m_nTones; ++j)
{
if (m_movingAverages[j].sum() > maxPower)
{
maxPower = m_movingAverages[j].sum();
maxIndex = j;
}
}
if (maxPower == 0.0)
{
return m_isOpen;
}
minPower = maxPower;
for (unsigned int j = 0; j < m_nTones; ++j)
{
if (m_movingAverages[j].sum() < minPower) {
minPower = m_movingAverages[j].sum();
minIndex = j;
}
}
// m_isOpen = ((minPower/maxPower < m_threshold) && (minIndex > maxIndex));
if ((minPower/maxPower < m_threshold) && (minIndex > maxIndex)) // open condition
{
if (m_squelchCount < m_samplesAttack + m_samplesDecay)
{
m_squelchCount++;
}
}
else
{
if (m_squelchCount > m_samplesAttack)
{
m_squelchCount--;
}
else
{
m_squelchCount = 0;
}
}
m_isOpen = (m_squelchCount >= m_samplesAttack) ;
// if ((minPower/maxPower < m_threshold) && (minIndex > maxIndex)) // open condition
// {
// if ((m_samplesAttack > 0) && (m_attackCount < m_samplesAttack))
// {
// m_isOpen = false;
// m_attackCount++;
// }
// else
// {
// m_isOpen = true;
// m_decayCount = 0;
// }
// }
// else
// {
// if ((m_samplesDecay > 0) && (m_decayCount < m_samplesDecay))
// {
// m_isOpen = true;
// m_decayCount++;
// }
// else
// {
// m_isOpen = false;
// m_attackCount = 0;
// }
// }
return m_isOpen;
}
void AFSquelch::setThreshold(double threshold)
{
qDebug("AFSquelch::setThreshold: threshold: %f", threshold);
m_threshold = threshold;
reset();
}