mirror of https://github.com/f4exb/sdrangel.git
746 lines
25 KiB
C++
746 lines
25 KiB
C++
///////////////////////////////////////////////////////////////////////////////////
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// Copyright (C) 2019-2020 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 <QTime>
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#include <QDebug>
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#include <stdio.h>
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#include "dsp/dsptypes.h"
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#include "dsp/basebandsamplesink.h"
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#include "dsp/dspengine.h"
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#include "dsp/fftfactory.h"
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#include "dsp/fftengine.h"
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#include "util/db.h"
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#include "chirpchatdemodmsg.h"
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#include "chirpchatdemodsink.h"
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ChirpChatDemodSink::ChirpChatDemodSink() :
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m_decodeMsg(nullptr),
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m_decoderMsgQueue(nullptr),
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m_fftSequence(-1),
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m_fftSFDSequence(-1),
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m_downChirps(nullptr),
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m_upChirps(nullptr),
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m_spectrumLine(nullptr),
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m_spectrumSink(nullptr),
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m_spectrumBuffer(nullptr)
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{
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m_demodActive = false;
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m_bandwidth = ChirpChatDemodSettings::bandwidths[0];
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m_channelSampleRate = 96000;
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m_channelFrequencyOffset = 0;
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m_nco.setFreq(m_channelFrequencyOffset, m_channelSampleRate);
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m_interpolator.create(16, m_channelSampleRate, m_bandwidth / 1.9f);
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m_interpolatorDistance = (Real) m_channelSampleRate / (Real) m_bandwidth;
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m_sampleDistanceRemain = 0;
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m_state = ChirpChatStateReset;
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m_chirp = 0;
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m_chirp0 = 0;
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initSF(m_settings.m_spreadFactor, m_settings.m_deBits, m_settings.m_fftWindow);
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}
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ChirpChatDemodSink::~ChirpChatDemodSink()
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{
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FFTFactory *fftFactory = DSPEngine::instance()->getFFTFactory();
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if (m_fftSequence >= 0)
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{
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fftFactory->releaseEngine(m_interpolatedFFTLength, false, m_fftSequence);
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fftFactory->releaseEngine(m_interpolatedFFTLength, false, m_fftSFDSequence);
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}
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delete[] m_downChirps;
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delete[] m_upChirps;
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delete[] m_spectrumBuffer;
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delete[] m_spectrumLine;
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}
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void ChirpChatDemodSink::initSF(unsigned int sf, unsigned int deBits, FFTWindow::Function fftWindow)
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{
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if (m_downChirps) {
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delete[] m_downChirps;
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}
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if (m_upChirps) {
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delete[] m_upChirps;
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}
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if (m_spectrumBuffer) {
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delete[] m_spectrumBuffer;
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}
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if (m_spectrumLine) {
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delete[] m_spectrumLine;
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}
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FFTFactory *fftFactory = DSPEngine::instance()->getFFTFactory();
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if (m_fftSequence >= 0)
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{
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fftFactory->releaseEngine(m_interpolatedFFTLength, false, m_fftSequence);
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fftFactory->releaseEngine(m_interpolatedFFTLength, false, m_fftSFDSequence);
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}
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m_nbSymbols = 1 << sf;
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m_nbSymbolsEff = 1 << (sf - deBits);
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m_deLength = 1 << deBits;
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m_fftLength = m_nbSymbols;
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m_fftWindow.create(fftWindow, m_fftLength);
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m_fftWindow.setKaiserAlpha(M_PI);
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m_interpolatedFFTLength = m_fftInterpolation*m_fftLength;
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m_preambleTolerance = (m_deLength*m_fftInterpolation)/2;
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m_fftSequence = fftFactory->getEngine(m_interpolatedFFTLength, false, &m_fft);
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m_fftSFDSequence = fftFactory->getEngine(m_interpolatedFFTLength, false, &m_fftSFD);
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m_state = ChirpChatStateReset;
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m_sfdSkip = m_fftLength / 4;
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m_downChirps = new Complex[2*m_nbSymbols]; // Each table is 2 chirps long to allow processing from arbitrary offsets.
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m_upChirps = new Complex[2*m_nbSymbols];
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m_spectrumBuffer = new Complex[m_nbSymbols];
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m_spectrumLine = new Complex[m_nbSymbols];
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std::fill(m_spectrumLine, m_spectrumLine+m_nbSymbols, Complex(std::polar(1e-6*SDR_RX_SCALED, 0.0)));
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float halfAngle = M_PI;
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float phase = -halfAngle;
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double accumulator = 0;
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for (unsigned int i = 0; i < m_fftLength; i++)
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{
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accumulator = fmod(accumulator + phase, 2*M_PI);
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m_downChirps[i] = Complex(std::conj(std::polar(1.0, accumulator)));
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m_upChirps[i] = Complex(std::polar(1.0, accumulator));
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phase += (2*halfAngle) / m_nbSymbols;
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}
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// Duplicate table to allow processing from arbitrary offsets
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std::copy(m_downChirps, m_downChirps+m_fftLength, m_downChirps+m_fftLength);
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std::copy(m_upChirps, m_upChirps+m_fftLength, m_upChirps+m_fftLength);
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}
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void ChirpChatDemodSink::feed(const SampleVector::const_iterator& begin, const SampleVector::const_iterator& end)
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{
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Complex ci;
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for (SampleVector::const_iterator it = begin; it < end; ++it)
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{
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Complex c(it->real() / SDR_RX_SCALEF, it->imag() / SDR_RX_SCALEF);
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c *= m_nco.nextIQ();
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if (m_interpolator.decimate(&m_sampleDistanceRemain, c, &ci))
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{
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processSample(ci);
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m_sampleDistanceRemain += m_interpolatorDistance;
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}
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}
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}
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void ChirpChatDemodSink::processSample(const Complex& ci)
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{
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if (m_state == ChirpChatStateReset) // start over
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{
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m_demodActive = false;
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reset();
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std::queue<double>().swap(m_magsqQueue); // this clears the queue
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m_state = ChirpChatStateDetectPreamble;
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}
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else if (m_state == ChirpChatStateDetectPreamble) // look for preamble
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{
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m_fft->in()[m_fftCounter++] = ci * m_downChirps[m_chirp]; // de-chirp the up ramp
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if (m_fftCounter == m_fftLength)
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{
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m_fftWindow.apply(m_fft->in());
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std::fill(m_fft->in()+m_fftLength, m_fft->in()+m_interpolatedFFTLength, Complex{0.0, 0.0});
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m_fft->transform();
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m_fftCounter = 0;
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double magsq, magsqTotal;
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unsigned int imax = argmax(
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m_fft->out(),
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m_fftInterpolation,
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m_fftLength,
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magsq,
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magsqTotal,
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m_spectrumBuffer,
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m_fftInterpolation
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) / m_fftInterpolation;
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if (m_magsqQueue.size() > m_settings.m_preambleChirps) {
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m_magsqQueue.pop();
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}
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m_magsqTotalAvg(magsqTotal);
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m_magsqQueue.push(magsq);
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m_argMaxHistory[m_argMaxHistoryCounter++] = imax;
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if (m_argMaxHistoryCounter == m_requiredPreambleChirps)
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{
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m_argMaxHistoryCounter = 0;
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bool preambleFound = true;
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for (unsigned int i = 1; i < m_requiredPreambleChirps; i++)
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{
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int delta = m_argMaxHistory[i] - m_argMaxHistory[i-1];
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// qDebug("ChirpChatDemodSink::processSample: search: delta: %d / %d", delta, m_deLength);
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if ((delta < -m_preambleTolerance) || (delta > m_preambleTolerance))
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{
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preambleFound = false;
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break;
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}
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// if (m_argMaxHistory[0] != m_argMaxHistory[i])
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// {
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// preambleFound = false;
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// break;
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// }
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}
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if ((preambleFound) && (magsq > 1e-9))
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{
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if (m_spectrumSink) {
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m_spectrumSink->feed(m_spectrumBuffer, m_nbSymbols);
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}
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qDebug("ChirpChatDemodSink::processSample: preamble found: %u|%f", m_argMaxHistory[0], magsq);
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m_chirp = m_argMaxHistory[0];
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m_fftCounter = m_chirp;
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m_chirp0 = 0;
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m_chirpCount = 0;
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m_state = ChirpChatStatePreambleResyc;
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}
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else
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{
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m_magsqOffAvg(m_magsqQueue.front());
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}
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}
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}
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}
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else if (m_state == ChirpChatStatePreambleResyc)
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{
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m_fftCounter++;
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if (m_fftCounter == m_fftLength)
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{
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if (m_spectrumSink) {
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m_spectrumSink->feed(m_spectrumLine, m_nbSymbols);
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}
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m_fftCounter = 0;
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m_demodActive = true;
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m_state = ChirpChatStatePreamble;
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}
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}
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else if (m_state == ChirpChatStatePreamble) // preamble found look for SFD start
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{
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m_fft->in()[m_fftCounter] = ci * m_downChirps[m_chirp]; // de-chirp the up ramp
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m_fftSFD->in()[m_fftCounter] = ci * m_upChirps[m_chirp]; // de-chirp the down ramp
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m_fftCounter++;
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if (m_fftCounter == m_fftLength)
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{
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m_fftWindow.apply(m_fft->in());
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std::fill(m_fft->in()+m_fftLength, m_fft->in()+m_interpolatedFFTLength, Complex{0.0, 0.0});
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m_fft->transform();
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m_fftWindow.apply(m_fftSFD->in());
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std::fill(m_fftSFD->in()+m_fftLength, m_fftSFD->in()+m_interpolatedFFTLength, Complex{0.0, 0.0});
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m_fftSFD->transform();
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m_fftCounter = 0;
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double magsqPre, magsqSFD;
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double magsqTotal, magsqSFDTotal;
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unsigned int imaxSFD = argmax(
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m_fftSFD->out(),
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m_fftInterpolation,
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m_fftLength,
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magsqSFD,
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magsqTotal,
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nullptr,
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m_fftInterpolation
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) / m_fftInterpolation;
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unsigned int imax = argmax(
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m_fft->out(),
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m_fftInterpolation,
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m_fftLength,
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magsqPre,
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magsqSFDTotal,
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m_spectrumBuffer,
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m_fftInterpolation
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) / m_fftInterpolation;
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m_preambleHistory[m_chirpCount] = imax;
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m_chirpCount++;
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double preDrop = magsqPre - magsqSFD;
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double dropRatio = -preDrop / magsqSFD;
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if ((preDrop < 0.0) && (dropRatio > 0.5)) // preamble drop
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{
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m_magsqTotalAvg(magsqSFDTotal);
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if (m_chirpCount < 1 + (m_settings.hasSyncWord() ? 2 : 0)) // too early
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{
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m_state = ChirpChatStateReset;
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qDebug("ChirpChatDemodSink::processSample: SFD search: signal drop is too early");
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}
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else
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{
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if (m_settings.hasSyncWord())
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{
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m_syncWord = round(m_preambleHistory[m_chirpCount-2] / 8.0);
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m_syncWord += 16 * round(m_preambleHistory[m_chirpCount-3] / 8.0);
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qDebug("ChirpChatDemodSink::processSample: SFD found: pre: %4u|%11.6f - sfd: %4u|%11.6f sync: %x", imax, magsqPre, imaxSFD, magsqSFD, m_syncWord);
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}
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else
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{
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qDebug("ChirpChatDemodSink::processSample: SFD found: pre: %4u|%11.6f - sfd: %4u|%11.6f", imax, magsqPre, imaxSFD, magsqSFD);
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}
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int sadj = 0;
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int nadj = 0;
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int zadj;
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int sfdSkip = m_sfdSkip;
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for (unsigned int i = 0; i < m_chirpCount - 1 - (m_settings.hasSyncWord() ? 2 : 0); i++)
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{
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sadj += m_preambleHistory[i] > m_nbSymbols/2 ? m_preambleHistory[i] - m_nbSymbols : m_preambleHistory[i];
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nadj++;
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}
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zadj = nadj == 0 ? 0 : sadj / nadj;
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zadj = zadj < -(sfdSkip/2) ? -(sfdSkip/2) : zadj > sfdSkip/2 ? sfdSkip/2 : zadj;
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qDebug("ChirpChatDemodSink::processSample: zero adjust: %d (%d)", zadj, nadj);
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m_sfdSkipCounter = 0;
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m_fftCounter = m_fftLength - m_sfdSkip + zadj;
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m_chirp += zadj;
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m_state = ChirpChatStateSkipSFD; //ChirpChatStateSlideSFD;
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}
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}
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else if (m_chirpCount > (m_settings.m_preambleChirps - m_requiredPreambleChirps + 2)) // SFD missed start over
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{
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qDebug("ChirpChatDemodSink::processSample: SFD search: number of possible chirps exceeded");
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m_magsqTotalAvg(magsqTotal);
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m_state = ChirpChatStateReset;
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}
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else
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{
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if (m_spectrumSink) {
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m_spectrumSink->feed(m_spectrumBuffer, m_nbSymbols);
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}
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qDebug("ChirpChatDemodSink::processSample: SFD search: pre: %4u|%11.6f - sfd: %4u|%11.6f", imax, magsqPre, imaxSFD, magsqSFD);
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m_magsqTotalAvg(magsqTotal);
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m_magsqOnAvg(magsqPre);
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}
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}
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}
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else if (m_state == ChirpChatStateSkipSFD) // Just skip the rest of SFD
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{
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m_fftCounter++;
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if (m_fftCounter == m_fftLength)
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{
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m_fftCounter = m_fftLength - m_sfdSkip;
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m_sfdSkipCounter++;
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if (m_sfdSkipCounter == m_settings.getNbSFDFourths() - 4U) // SFD chips fourths less one full period
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{
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qDebug("ChirpChatDemodSink::processSample: SFD skipped");
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m_chirp = m_chirp0;
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m_fftCounter = 0;
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m_chirpCount = 0;
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m_magsqMax = 0.0;
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m_decodeMsg = ChirpChatDemodMsg::MsgDecodeSymbols::create();
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m_decodeMsg->setSyncWord(m_syncWord);
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m_state = ChirpChatStateReadPayload;
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}
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}
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}
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else if (m_state == ChirpChatStateReadPayload)
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{
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m_fft->in()[m_fftCounter] = ci * m_downChirps[m_chirp]; // de-chirp the up ramp
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m_fftCounter++;
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if (m_fftCounter == m_fftLength)
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{
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m_fftWindow.apply(m_fft->in());
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std::fill(m_fft->in()+m_fftLength, m_fft->in()+m_interpolatedFFTLength, Complex{0.0, 0.0});
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m_fft->transform();
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m_fftCounter = 0;
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double magsq, magsqTotal;
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unsigned short symbol;
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if (m_settings.m_codingScheme == ChirpChatDemodSettings::CodingFT)
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{
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std::vector<float> magnitudes;
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symbol = evalSymbol(
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extractMagnitudes(
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magnitudes,
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m_fft->out(),
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m_fftInterpolation,
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m_fftLength,
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magsq,
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magsqTotal,
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m_spectrumBuffer,
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m_fftInterpolation
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)
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) % m_nbSymbolsEff;
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m_decodeMsg->pushBackSymbol(symbol);
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m_decodeMsg->pushBackMagnitudes(magnitudes);
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}
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else
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{
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int imax;
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if (m_settings.m_deBits > 0)
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{
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double magSqNoise;
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imax = argmaxSpreaded(
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m_fft->out(),
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m_fftInterpolation,
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m_fftLength,
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magsq,
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magSqNoise,
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magsqTotal,
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m_spectrumBuffer,
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m_fftInterpolation
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);
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// double dbS = CalcDb::dbPower(magsq);
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// double dbN = CalcDb::dbPower(magSqNoise);
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// qDebug("ChirpChatDemodSink::processSample: S: %5.2f N: %5.2f S/N: %5.2f", dbS, dbN, dbS - dbN);
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}
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else
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{
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imax = argmax(
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m_fft->out(),
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m_fftInterpolation,
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m_fftLength,
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magsq,
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magsqTotal,
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m_spectrumBuffer,
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m_fftInterpolation
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);
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}
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symbol = evalSymbol(imax) % m_nbSymbolsEff;
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m_decodeMsg->pushBackSymbol(symbol);
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}
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if (m_spectrumSink) {
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m_spectrumSink->feed(m_spectrumBuffer, m_nbSymbols);
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}
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if (magsq > m_magsqMax) {
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m_magsqMax = magsq;
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}
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m_magsqTotalAvg(magsq);
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if ((m_chirpCount == 0)
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|| (m_settings.m_eomSquelchTenths == 121) // max - disable squelch
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|| ((m_settings.m_eomSquelchTenths*magsq)/10.0 > m_magsqMax))
|
|
{
|
|
qDebug("ChirpChatDemodSink::processSample: symbol %02u: %4u|%11.6f", m_chirpCount, symbol, magsq);
|
|
m_magsqOnAvg(magsq);
|
|
m_chirpCount++;
|
|
|
|
if (m_chirpCount > m_settings.m_nbSymbolsMax)
|
|
{
|
|
qDebug("ChirpChatDemodSink::processSample: message length reached");
|
|
m_state = ChirpChatStateReset;
|
|
m_decodeMsg->setSignalDb(CalcDb::dbPower(m_magsqOnAvg.asDouble() / (1<<m_settings.m_spreadFactor)));
|
|
m_decodeMsg->setNoiseDb(CalcDb::dbPower(m_magsqOffAvg.asDouble() / (1<<m_settings.m_spreadFactor)));
|
|
|
|
if (m_decoderMsgQueue && m_settings.m_decodeActive) {
|
|
m_decoderMsgQueue->push(m_decodeMsg);
|
|
} else {
|
|
delete m_decodeMsg;
|
|
}
|
|
}
|
|
}
|
|
else
|
|
{
|
|
qDebug("ChirpChatDemodSink::processSample: end of message");
|
|
m_state = ChirpChatStateReset;
|
|
m_decodeMsg->popSymbol(); // last symbol is garbage
|
|
m_decodeMsg->setSignalDb(CalcDb::dbPower(m_magsqOnAvg.asDouble() / (1<<m_settings.m_spreadFactor)));
|
|
m_decodeMsg->setNoiseDb(CalcDb::dbPower(m_magsqOffAvg.asDouble() / (1<<m_settings.m_spreadFactor)));
|
|
|
|
if (m_decoderMsgQueue && m_settings.m_decodeActive) {
|
|
m_decoderMsgQueue->push(m_decodeMsg);
|
|
} else {
|
|
delete m_decodeMsg;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
else
|
|
{
|
|
m_state = ChirpChatStateReset;
|
|
}
|
|
|
|
m_chirp++;
|
|
|
|
if (m_chirp >= m_chirp0 + m_nbSymbols) {
|
|
m_chirp = m_chirp0;
|
|
}
|
|
}
|
|
|
|
void ChirpChatDemodSink::reset()
|
|
{
|
|
m_chirp = 0;
|
|
m_chirp0 = 0;
|
|
m_fftCounter = 0;
|
|
m_argMaxHistoryCounter = 0;
|
|
m_sfdSkipCounter = 0;
|
|
}
|
|
|
|
unsigned int ChirpChatDemodSink::argmax(
|
|
const Complex *fftBins,
|
|
unsigned int fftMult,
|
|
unsigned int fftLength,
|
|
double& magsqMax,
|
|
double& magsqTotal,
|
|
Complex *specBuffer,
|
|
unsigned int specDecim)
|
|
{
|
|
magsqMax = 0.0;
|
|
magsqTotal = 0.0;
|
|
unsigned int imax = 0;
|
|
double magSum = 0.0;
|
|
|
|
for (unsigned int i = 0; i < fftMult*fftLength; i++)
|
|
{
|
|
double magsq = std::norm(fftBins[i]);
|
|
magsqTotal += magsq;
|
|
|
|
if (magsq > magsqMax)
|
|
{
|
|
imax = i;
|
|
magsqMax = magsq;
|
|
}
|
|
|
|
if (specBuffer)
|
|
{
|
|
magSum += magsq;
|
|
|
|
if (i % specDecim == specDecim - 1)
|
|
{
|
|
specBuffer[i/specDecim] = Complex(std::polar(magSum, 0.0));
|
|
magSum = 0.0;
|
|
}
|
|
}
|
|
}
|
|
|
|
magsqTotal /= fftMult*fftLength;
|
|
|
|
return imax;
|
|
}
|
|
|
|
unsigned int ChirpChatDemodSink::extractMagnitudes(
|
|
std::vector<float>& magnitudes,
|
|
const Complex *fftBins,
|
|
unsigned int fftMult,
|
|
unsigned int fftLength,
|
|
double& magsqMax,
|
|
double& magsqTotal,
|
|
Complex *specBuffer,
|
|
unsigned int specDecim)
|
|
{
|
|
magsqMax = 0.0;
|
|
magsqTotal = 0.0;
|
|
unsigned int imax = 0;
|
|
double magSum = 0.0;
|
|
unsigned int spread = fftMult * (1<<m_settings.m_deBits);
|
|
unsigned int istart = fftMult*fftLength - spread/2 + 1;
|
|
float magnitude = 0.0;
|
|
|
|
for (unsigned int i2 = istart; i2 < istart + fftMult*fftLength; i2++)
|
|
{
|
|
int i = i2 % (fftMult*fftLength);
|
|
double magsq = std::norm(fftBins[i]);
|
|
magsqTotal += magsq;
|
|
magnitude += magsq;
|
|
|
|
if (i % spread == (spread/2)-1) // boundary (inclusive)
|
|
{
|
|
if (magnitude > magsqMax)
|
|
{
|
|
imax = (i/spread)*spread;
|
|
magsqMax = magnitude;
|
|
}
|
|
|
|
magnitudes.push_back(magnitude);
|
|
magnitude = 0.0;
|
|
}
|
|
|
|
if (specBuffer)
|
|
{
|
|
magSum += magsq;
|
|
|
|
if (i % specDecim == specDecim - 1)
|
|
{
|
|
specBuffer[i/specDecim] = Complex(std::polar(magSum, 0.0));
|
|
magSum = 0.0;
|
|
}
|
|
}
|
|
}
|
|
|
|
magsqTotal /= fftMult*fftLength;
|
|
|
|
return imax;
|
|
}
|
|
|
|
unsigned int ChirpChatDemodSink::argmaxSpreaded(
|
|
const Complex *fftBins,
|
|
unsigned int fftMult,
|
|
unsigned int fftLength,
|
|
double& magsqMax,
|
|
double& magsqNoise,
|
|
double& magsqTotal,
|
|
Complex *specBuffer,
|
|
unsigned int specDecim)
|
|
{
|
|
magsqMax = 0.0;
|
|
magsqNoise = 0.0;
|
|
magsqTotal = 0.0;
|
|
unsigned int imax = 0;
|
|
double magSum = 0.0;
|
|
unsigned int nbsymbols = 1<<(m_settings.m_spreadFactor - m_settings.m_deBits);
|
|
unsigned int spread = fftMult * (1<<m_settings.m_deBits);
|
|
unsigned int istart = fftMult*fftLength - spread/2 + 1;
|
|
double magSymbol = 0.0;
|
|
|
|
for (unsigned int i2 = istart; i2 < istart + fftMult*fftLength; i2++)
|
|
{
|
|
int i = i2 % (fftMult*fftLength);
|
|
double magsq = std::norm(fftBins[i]);
|
|
magsqTotal += magsq;
|
|
magSymbol += magsq;
|
|
|
|
if (i % spread == (spread/2)-1) // boundary (inclusive)
|
|
{
|
|
if (magSymbol > magsqMax)
|
|
{
|
|
imax = (i/spread)*spread;
|
|
magsqMax = magSymbol;
|
|
}
|
|
|
|
magsqNoise += magSymbol;
|
|
magSymbol = 0.0;
|
|
}
|
|
|
|
if (specBuffer)
|
|
{
|
|
magSum += magsq;
|
|
|
|
if (i % specDecim == specDecim - 1)
|
|
{
|
|
specBuffer[i/specDecim] = Complex(std::polar(magSum, 0.0));
|
|
magSum = 0.0;
|
|
}
|
|
}
|
|
}
|
|
|
|
magsqNoise -= magsqMax;
|
|
magsqNoise /= (nbsymbols - 1);
|
|
magsqTotal /= nbsymbols;
|
|
// magsqNoise /= fftLength;
|
|
// magsqTotal /= fftMult*fftLength;
|
|
|
|
return imax;
|
|
}
|
|
|
|
void ChirpChatDemodSink::decimateSpectrum(Complex *in, Complex *out, unsigned int size, unsigned int decimation)
|
|
{
|
|
for (unsigned int i = 0; i < size; i++)
|
|
{
|
|
if (i % decimation == 0) {
|
|
out[i/decimation] = in[i];
|
|
}
|
|
}
|
|
}
|
|
|
|
int ChirpChatDemodSink::toSigned(int u, int intSize)
|
|
{
|
|
if (u > intSize/2) {
|
|
return u - intSize;
|
|
} else {
|
|
return u;
|
|
}
|
|
}
|
|
|
|
unsigned int ChirpChatDemodSink::evalSymbol(unsigned int rawSymbol)
|
|
{
|
|
unsigned int spread = m_fftInterpolation * (1<<m_settings.m_deBits);
|
|
|
|
if (spread < 2 ) {
|
|
return rawSymbol;
|
|
} else {
|
|
return (rawSymbol + spread/2 - 1) / spread; // middle point goes to symbol below (smear to the right)
|
|
}
|
|
}
|
|
|
|
void ChirpChatDemodSink::applyChannelSettings(int channelSampleRate, int bandwidth, int channelFrequencyOffset, bool force)
|
|
{
|
|
qDebug() << "ChirpChatDemodSink::applyChannelSettings:"
|
|
<< " channelSampleRate: " << channelSampleRate
|
|
<< " channelFrequencyOffset: " << channelFrequencyOffset
|
|
<< " bandwidth: " << bandwidth;
|
|
|
|
if ((channelFrequencyOffset != m_channelFrequencyOffset) ||
|
|
(channelSampleRate != m_channelSampleRate) || force)
|
|
{
|
|
m_nco.setFreq(-channelFrequencyOffset, channelSampleRate);
|
|
}
|
|
|
|
if ((channelSampleRate != m_channelSampleRate) ||
|
|
(bandwidth != m_bandwidth) || force)
|
|
{
|
|
m_interpolator.create(16, channelSampleRate, bandwidth / 1.25f);
|
|
m_interpolatorDistance = (Real) channelSampleRate / (Real) bandwidth;
|
|
m_sampleDistanceRemain = 0;
|
|
qDebug() << "ChirpChatDemodSink::applyChannelSettings: m_interpolator.create:"
|
|
<< " m_interpolatorDistance: " << m_interpolatorDistance;
|
|
}
|
|
|
|
m_channelSampleRate = channelSampleRate;
|
|
m_bandwidth = bandwidth;
|
|
m_channelFrequencyOffset = channelFrequencyOffset;
|
|
}
|
|
|
|
void ChirpChatDemodSink::applySettings(const ChirpChatDemodSettings& settings, bool force)
|
|
{
|
|
qDebug() << "ChirpChatDemodSink::applySettings:"
|
|
<< " m_inputFrequencyOffset: " << settings.m_inputFrequencyOffset
|
|
<< " m_bandwidthIndex: " << settings.m_bandwidthIndex
|
|
<< " m_spreadFactor: " << settings.m_spreadFactor
|
|
<< " m_rgbColor: " << settings.m_rgbColor
|
|
<< " m_title: " << settings.m_title
|
|
<< " force: " << force;
|
|
|
|
if ((settings.m_spreadFactor != m_settings.m_spreadFactor)
|
|
|| (settings.m_deBits != m_settings.m_deBits)
|
|
|| (settings.m_fftWindow != m_settings.m_fftWindow) || force) {
|
|
initSF(settings.m_spreadFactor, settings.m_deBits, settings.m_fftWindow);
|
|
}
|
|
|
|
m_settings = settings;
|
|
}
|