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411 lines
13 KiB
C++
411 lines
13 KiB
C++
///////////////////////////////////////////////////////////////////////////////////
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// Copyright (C) 2020 Edouard Griffiths, F4EXB <f4exb06@gmail.com> //
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// //
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// This program is free software; you can redistribute it and/or modify //
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// it under the terms of the GNU General Public License as published by //
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// the Free Software Foundation as version 3 of the License, or //
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// (at your option) any later version. //
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// //
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// This program is distributed in the hope that it will be useful, //
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// but WITHOUT ANY WARRANTY; without even the implied warranty of //
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the //
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// GNU General Public License V3 for more details. //
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// //
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// You should have received a copy of the GNU General Public License //
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// along with this program. If not, see <http://www.gnu.org/licenses/>. //
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///////////////////////////////////////////////////////////////////////////////////
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#include <QDebug>
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#include "chirpchatmodsource.h"
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const int ChirpChatModSource::m_levelNbSamples = 480; // every 10ms
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ChirpChatModSource::ChirpChatModSource() :
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m_channelSampleRate(48000),
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m_channelFrequencyOffset(0),
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m_phaseIncrements(nullptr),
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m_repeatCount(0),
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m_active(false),
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m_modPhasor(0.0f),
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m_levelCalcCount(0),
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m_peakLevel(0.0f),
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m_levelSum(0.0f)
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{
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m_magsq = 0.0;
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initSF(m_settings.m_spreadFactor);
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initTest(m_settings.m_spreadFactor, m_settings.m_deBits);
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reset();
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applySettings(m_settings, true);
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applyChannelSettings(m_channelSampleRate, m_channelFrequencyOffset, true);
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}
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ChirpChatModSource::~ChirpChatModSource()
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{
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delete[] m_phaseIncrements;
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}
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void ChirpChatModSource::initSF(unsigned int sf)
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{
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m_fftLength = 1 << sf;
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m_state = ChirpChatStateIdle;
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m_quarterSamples = (m_fftLength/4)*ChirpChatModSettings::oversampling;
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float halfAngle = M_PI/ChirpChatModSettings::oversampling;
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float phase = -halfAngle;
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if (m_phaseIncrements) {
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delete[] m_phaseIncrements;
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}
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m_phaseIncrements = new double[2*m_fftLength*ChirpChatModSettings::oversampling];
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phase = -halfAngle;
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for (unsigned int i = 0; i < m_fftLength*ChirpChatModSettings::oversampling; i++)
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{
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m_phaseIncrements[i] = phase;
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phase += (2*halfAngle) / (m_fftLength*ChirpChatModSettings::oversampling);
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}
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std::copy(
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m_phaseIncrements,
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m_phaseIncrements+m_fftLength*ChirpChatModSettings::oversampling,
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m_phaseIncrements+m_fftLength*ChirpChatModSettings::oversampling
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);
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}
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void ChirpChatModSource::initTest(unsigned int sf, unsigned int deBits)
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{
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unsigned int fftLength = 1<<sf;
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unsigned int symbolRange = fftLength/(1<<deBits);
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m_symbols.clear();
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for (unsigned int seq = 0; seq < 1; seq++)
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{
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for (unsigned int symbol = 0; symbol < symbolRange; symbol += symbolRange/4)
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{
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m_symbols.push_back(symbol);
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m_symbols.push_back(symbol+1);
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}
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}
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}
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void ChirpChatModSource::reset()
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{
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m_chirp = 0;
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m_chirp0 = 0;
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m_sampleCounter = 0;
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m_fftCounter = 0;
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m_chirpCount = 0;
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}
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void ChirpChatModSource::pull(SampleVector::iterator begin, unsigned int nbSamples)
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{
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std::for_each(
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begin,
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begin + nbSamples,
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[this](Sample& s) {
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pullOne(s);
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}
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);
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}
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void ChirpChatModSource::pullOne(Sample& sample)
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{
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if (m_settings.m_channelMute)
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{
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sample.m_real = 0.0f;
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sample.m_imag = 0.0f;
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m_magsq = 0.0;
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return;
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}
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Complex ci;
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if (m_interpolatorDistance > 1.0f) // decimate
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{
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modulateSample();
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while (!m_interpolator.decimate(&m_interpolatorDistanceRemain, m_modSample, &ci))
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{
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modulateSample();
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}
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}
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else
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{
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if (m_interpolator.interpolate(&m_interpolatorDistanceRemain, m_modSample, &ci))
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{
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modulateSample();
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}
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}
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m_interpolatorDistanceRemain += m_interpolatorDistance;
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ci *= m_carrierNco.nextIQ(); // shift to carrier frequency
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if (!(m_state == ChirpChatStateIdle))
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{
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double magsq = std::norm(ci);
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magsq /= (SDR_TX_SCALED*SDR_TX_SCALED);
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m_movingAverage(magsq);
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m_magsq = m_movingAverage.asDouble();
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}
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sample.m_real = (FixReal) ci.real();
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sample.m_imag = (FixReal) ci.imag();
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}
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void ChirpChatModSource::modulateSample()
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{
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if (m_state == ChirpChatStateIdle)
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{
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m_modSample = Complex{0.0, 0.0};
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m_sampleCounter++;
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if (m_sampleCounter == m_quietSamples*ChirpChatModSettings::oversampling) // done with quiet time
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{
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m_chirp0 = 0;
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m_chirp = m_fftLength*ChirpChatModSettings::oversampling - 1;
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if (m_symbols.size() != 0) // some payload to transmit
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{
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if (m_settings.m_messageRepeat == 0) // infinite
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{
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m_state = ChirpChatStatePreamble;
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m_active = true;
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}
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else
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{
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if (m_repeatCount != 0)
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{
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m_repeatCount--;
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m_state = ChirpChatStatePreamble;
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m_active = true;
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}
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else
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{
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m_active = false;
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}
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}
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}
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else
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{
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m_active = false;
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}
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}
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}
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else if (m_state == ChirpChatStatePreamble)
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{
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m_modPhasor += m_phaseIncrements[m_chirp]; // up chirps
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m_modSample = Complex(std::polar(0.891235351562 * SDR_TX_SCALED, m_modPhasor));
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m_fftCounter++;
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if (m_fftCounter == m_fftLength*ChirpChatModSettings::oversampling)
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{
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m_chirpCount++;
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m_fftCounter = 0;
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if (m_chirpCount == m_settings.m_preambleChirps)
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{
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m_chirpCount = 0;
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if (m_settings.hasSyncWord())
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{
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m_chirp0 = ((m_settings.m_syncWord >> ((1-m_chirpCount)*4)) & 0xf)*8;
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m_chirp = (m_chirp0 + m_fftLength)*ChirpChatModSettings::oversampling - 1;
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m_state = ChirpChatStateSyncWord;
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}
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else
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{
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m_sampleCounter = 0;
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m_chirp0 = 0;
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m_chirp = m_fftLength*ChirpChatModSettings::oversampling - 1;
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m_state = ChirpChatStateSFD;
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}
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}
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}
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}
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else if (m_state == ChirpChatStateSyncWord)
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{
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m_modPhasor += m_phaseIncrements[m_chirp]; // up chirps
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m_modSample = Complex(std::polar(0.891235351562 * SDR_TX_SCALED, m_modPhasor));
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m_fftCounter++;
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if (m_fftCounter == m_fftLength*ChirpChatModSettings::oversampling)
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{
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m_chirpCount++;
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m_chirp0 = ((m_settings.m_syncWord >> ((1-m_chirpCount)*4)) & 0xf)*8;
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m_chirp = (m_chirp0 + m_fftLength)*ChirpChatModSettings::oversampling - 1;
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m_fftCounter = 0;
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if (m_chirpCount == 2)
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{
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m_sampleCounter = 0;
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m_chirpCount = 0;
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m_chirp0 = 0;
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m_chirp = m_fftLength*ChirpChatModSettings::oversampling - 1;
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m_state = ChirpChatStateSFD;
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}
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}
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}
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else if (m_state == ChirpChatStateSFD)
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{
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m_modPhasor -= m_phaseIncrements[m_chirp]; // down chirps
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m_modSample = Complex(std::polar(0.891235351562 * SDR_TX_SCALED, m_modPhasor));
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m_fftCounter++;
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m_sampleCounter++;
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if (m_fftCounter == m_fftLength*ChirpChatModSettings::oversampling)
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{
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m_chirp0 = 0;
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m_chirp = m_fftLength*ChirpChatModSettings::oversampling - 1;
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m_fftCounter = 0;
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}
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if (m_sampleCounter == m_quarterSamples)
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{
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m_chirpCount++;
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m_sampleCounter = 0;
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}
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if (m_chirpCount == m_settings.getNbSFDFourths())
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{
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m_fftCounter = 0;
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m_chirpCount = 0;
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m_chirp0 = encodeSymbol(m_symbols[m_chirpCount]);
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m_chirp = (m_chirp0 + m_fftLength)*ChirpChatModSettings::oversampling - 1;
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m_state = ChirpChatStatePayload;
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}
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}
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else if (m_state == ChirpChatStatePayload)
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{
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m_modPhasor += m_phaseIncrements[m_chirp]; // up chirps
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m_modSample = Complex(std::polar(0.891235351562 * SDR_TX_SCALED, m_modPhasor));
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m_fftCounter++;
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if (m_fftCounter == m_fftLength*ChirpChatModSettings::oversampling)
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{
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m_chirpCount++;
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if (m_chirpCount == m_symbols.size())
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{
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reset();
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m_state = ChirpChatStateIdle;
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}
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else
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{
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m_chirp0 = encodeSymbol(m_symbols[m_chirpCount]);
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m_chirp = (m_chirp0 + m_fftLength)*ChirpChatModSettings::oversampling - 1;
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m_fftCounter = 0;
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}
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}
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}
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// limit phasor range to ]-pi,pi]
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if (m_modPhasor > M_PI) {
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m_modPhasor -= (2.0f * M_PI);
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}
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m_chirp++;
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if (m_chirp >= (m_chirp0 + m_fftLength)*ChirpChatModSettings::oversampling) {
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m_chirp = m_chirp0*ChirpChatModSettings::oversampling;
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}
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}
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unsigned short ChirpChatModSource::encodeSymbol(unsigned short symbol)
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{
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if (m_settings.m_deBits == 0) {
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return symbol;
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}
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unsigned int deWidth = 1<<m_settings.m_deBits;
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unsigned int baseSymbol = symbol % (m_fftLength/deWidth); // symbols range control
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return deWidth*baseSymbol;
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// return deWidth*baseSymbol + (deWidth/2) - 1;
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}
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void ChirpChatModSource::calculateLevel(Real& sample)
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{
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if (m_levelCalcCount < m_levelNbSamples)
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{
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m_peakLevel = std::max(std::fabs(m_peakLevel), sample);
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m_levelSum += sample * sample;
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m_levelCalcCount++;
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}
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else
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{
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m_rmsLevel = sqrt(m_levelSum / m_levelNbSamples);
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m_peakLevelOut = m_peakLevel;
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m_peakLevel = 0.0f;
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m_levelSum = 0.0f;
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m_levelCalcCount = 0;
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}
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}
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void ChirpChatModSource::applySettings(const ChirpChatModSettings& settings, bool force)
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{
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if ((settings.m_spreadFactor != m_settings.m_spreadFactor)
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|| (settings.m_deBits != m_settings.m_deBits)
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|| (settings.m_preambleChirps != m_settings.m_preambleChirps)|| force)
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{
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initSF(settings.m_spreadFactor);
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initTest(settings.m_spreadFactor, settings.m_deBits);
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reset();
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}
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if ((settings.m_quietMillis != m_settings.m_quietMillis) || force)
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{
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m_quietSamples = (m_bandwidth*settings.m_quietMillis) / 1000;
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reset();
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}
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if ((settings.m_messageRepeat != m_settings.m_messageRepeat) || force) {
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m_repeatCount = settings.m_messageRepeat;
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}
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m_settings = settings;
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}
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void ChirpChatModSource::applyChannelSettings(int channelSampleRate, int bandwidth, int channelFrequencyOffset, bool force)
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{
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qDebug() << "ChirpChatModSource::applyChannelSettings:"
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<< " channelSampleRate: " << channelSampleRate
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<< " channelFrequencyOffset: " << channelFrequencyOffset
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<< " bandwidth: " << bandwidth
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<< " SR: " << bandwidth * ChirpChatModSettings::oversampling;
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if ((channelFrequencyOffset != m_channelFrequencyOffset)
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|| (channelSampleRate != m_channelSampleRate) || force)
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{
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m_carrierNco.setFreq(channelFrequencyOffset, channelSampleRate);
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}
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if ((channelSampleRate != m_channelSampleRate)
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|| (bandwidth != m_bandwidth) || force)
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{
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m_interpolatorDistanceRemain = 0;
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m_interpolatorConsumed = false;
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m_interpolatorDistance = (Real) (bandwidth*ChirpChatModSettings::oversampling) / (Real) channelSampleRate;
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m_interpolator.create(16, bandwidth, bandwidth / 2.2);
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}
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m_channelSampleRate = channelSampleRate;
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m_channelFrequencyOffset = channelFrequencyOffset;
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m_bandwidth = bandwidth;
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m_quietSamples = (bandwidth*m_settings.m_quietMillis) / 1000;
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m_state = ChirpChatStateIdle;
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reset();
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}
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void ChirpChatModSource::setSymbols(const std::vector<unsigned short>& symbols)
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{
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m_symbols = symbols;
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qDebug("ChirpChatModSource::setSymbols: m_symbols: %lu", m_symbols.size());
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m_repeatCount = m_settings.m_messageRepeat;
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m_state = ChirpChatStateIdle; // first reset to idle
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reset();
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m_sampleCounter = m_quietSamples*ChirpChatModSettings::oversampling - 1; // start immediately
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}
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