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334 lines
12 KiB
C++
334 lines
12 KiB
C++
///////////////////////////////////////////////////////////////////////////////////
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// Copyright (C) 2019 Edouard Griffiths, F4EXB //
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// Copyright (C) 2023 Jon Beniston, M7RCE //
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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 <complex.h>
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#include "dsp/dspengine.h"
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#include "dsp/scopevis.h"
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#include "util/db.h"
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#include "util/popcount.h"
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#include "maincore.h"
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#include "dscdemod.h"
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#include "dscdemodsink.h"
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DSCDemodSink::DSCDemodSink(DSCDemod *packetDemod) :
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m_dscDemod(packetDemod),
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m_channelSampleRate(DSCDemodSettings::DSCDEMOD_CHANNEL_SAMPLE_RATE),
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m_channelFrequencyOffset(0),
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m_magsqSum(0.0f),
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m_magsqPeak(0.0f),
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m_magsqCount(0),
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m_messageQueueToChannel(nullptr),
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m_exp(nullptr),
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m_sampleBufferIndex(0)
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{
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m_magsq = 0.0;
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for (int i = 0; i < DSCDemodSettings::m_scopeStreams; i++) {
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m_sampleBuffer[i].resize(m_sampleBufferSize);
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}
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applySettings(m_settings, true);
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applyChannelSettings(m_channelSampleRate, m_channelFrequencyOffset, true);
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m_lowpassComplex1.create(301, DSCDemodSettings::DSCDEMOD_CHANNEL_SAMPLE_RATE, DSCDemodSettings::DSCDEMOD_BAUD_RATE * 1.1);
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m_lowpassComplex2.create(301, DSCDemodSettings::DSCDEMOD_CHANNEL_SAMPLE_RATE, DSCDemodSettings::DSCDEMOD_BAUD_RATE * 1.1);
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}
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DSCDemodSink::~DSCDemodSink()
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{
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delete[] m_exp;
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}
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void DSCDemodSink::sampleToScope(Complex sample, Real abs1Filt, Real abs2Filt, Real unbiasedData, Real biasedData)
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{
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if (m_scopeSink)
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{
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m_sampleBuffer[0][m_sampleBufferIndex] = sample;
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m_sampleBuffer[1][m_sampleBufferIndex] = Complex(m_magsq, 0.0f);
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m_sampleBuffer[2][m_sampleBufferIndex] = Complex(abs1Filt, 0.0f);
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m_sampleBuffer[3][m_sampleBufferIndex] = Complex(abs2Filt, 0.0f);
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m_sampleBuffer[4][m_sampleBufferIndex] = Complex(unbiasedData, 0.0f);
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m_sampleBuffer[5][m_sampleBufferIndex] = Complex(biasedData, 0.0f);
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m_sampleBuffer[6][m_sampleBufferIndex] = Complex(m_data, 0.0f);
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m_sampleBuffer[7][m_sampleBufferIndex] = Complex(m_clock, 0.0f);
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m_sampleBuffer[8][m_sampleBufferIndex] = Complex(m_bit, 0.0f);
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m_sampleBuffer[9][m_sampleBufferIndex] = Complex(m_gotSOP, 0.0f);
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m_sampleBufferIndex++;
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if (m_sampleBufferIndex == m_sampleBufferSize)
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{
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std::vector<ComplexVector::const_iterator> vbegin;
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for (int i = 0; i < DSCDemodSettings::m_scopeStreams; i++) {
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vbegin.push_back(m_sampleBuffer[i].begin());
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}
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m_scopeSink->feed(vbegin, m_sampleBufferSize);
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m_sampleBufferIndex = 0;
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}
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}
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}
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void DSCDemodSink::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(), it->imag());
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c *= m_nco.nextIQ();
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if (m_interpolatorDistance < 1.0f) // interpolate
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{
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while (!m_interpolator.interpolate(&m_interpolatorDistanceRemain, c, &ci))
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{
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processOneSample(ci);
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m_interpolatorDistanceRemain += m_interpolatorDistance;
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}
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}
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else // decimate
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{
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if (m_interpolator.decimate(&m_interpolatorDistanceRemain, c, &ci))
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{
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processOneSample(ci);
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m_interpolatorDistanceRemain += m_interpolatorDistance;
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}
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}
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}
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}
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void DSCDemodSink::processOneSample(Complex &ci)
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{
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// Calculate average and peak levels for level meter
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double magsqRaw = ci.real()*ci.real() + ci.imag()*ci.imag();;
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Real magsq = magsqRaw / (SDR_RX_SCALED*SDR_RX_SCALED);
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m_movingAverage(magsq);
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m_magsq = m_movingAverage.asDouble();
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m_magsqSum += magsq;
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if (magsq > m_magsqPeak)
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{
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m_magsqPeak = magsq;
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}
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m_magsqCount++;
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// Sum power while data is being received
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if (m_gotSOP)
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{
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m_rssiMagSqSum += magsq;
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m_rssiMagSqCount++;
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}
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ci /= SDR_RX_SCALEF;
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// Correlate with expected frequencies
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Complex exp = m_exp[m_expIdx];
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m_expIdx = (m_expIdx + 1) % m_expLength;
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Complex corr1 = ci * exp;
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Complex corr2 = ci * std::conj(exp);
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// Low pass filter
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Real abs1Filt = std::abs(m_lowpassComplex1.filter(corr1));
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Real abs2Filt = std::abs(m_lowpassComplex2.filter(corr2));
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// Envelope calculation
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m_movMax1(abs1Filt);
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m_movMax2(abs2Filt);
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Real env1 = m_movMax1.getMaximum();
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Real env2 = m_movMax2.getMaximum();
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// Automatic threshold correction to compensate for frequency selective fading
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// http://www.w7ay.net/site/Technical/ATC/index.html
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Real bias1 = abs1Filt - 0.5 * env1;
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Real bias2 = abs2Filt - 0.5 * env2;
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Real unbiasedData = abs1Filt - abs2Filt;
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Real biasedData = bias1 - bias2;
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// Save current data for edge detection
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m_dataPrev = m_data;
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// Set data according to stongest correlation
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m_data = biasedData > 0;
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// Calculate timing error (we expect clockCount to be 0 when data changes), and add a proportion of it
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if (m_data && !m_dataPrev) {
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m_clockCount -= m_clockCount * 0.25;
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}
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m_clockCount += 1.0;
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if (m_clockCount >= m_samplesPerBit/2.0-1.0)
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{
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// Sample in middle of symbol
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receiveBit(m_data);
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m_clock = 1;
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// Wrap clock counter
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m_clockCount -= m_samplesPerBit;
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}
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else
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{
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m_clock = 0;
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}
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sampleToScope(ci, abs1Filt, abs2Filt, unbiasedData, biasedData);
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}
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const QList<DSCDemodSink::PhasingPattern> DSCDemodSink::m_phasingPatterns = {
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{0b1011111001'1111011001'1011111001, 9}, // 125 111 125
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{0b1111011001'1011111001'0111011010, 8}, // 111 125 110
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{0b1011111001'0111011010'1011111001, 7}, // 125 110 125
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{0b0111011010'1011111001'1011011010, 6}, // 110 125 109
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{0b1011111001'1011011010'1011111001, 5}, // 125 109 125
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{0b1011011010'1011111001'0011011011, 4}, // 109 125 108
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{0b1011111001'0011011011'1011111001, 3}, // 125 108 125
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{0b0011011011'1011111001'1101011010, 2}, // 108 125 107
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{0b1011111001'1101011010'1011111001, 1}, // 125 107 125
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{0b1101011010'1011111001'0101011011, 0}, // 107 125 106
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};
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void DSCDemodSink::receiveBit(bool bit)
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{
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m_bit = bit;
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// Store in shift reg
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m_bits = (m_bits << 1) | m_bit;
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m_bitCount++;
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if (!m_gotSOP)
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{
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// Dot pattern - 200 1/0s or 20 1/0s
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// Phasing pattern - 6 DX=125 RX=111 110 109 108 107 106 105 104
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// Phasing is considered to be achieved when two DXs and one RX, or two RXs and one DX, or three RXs in the appropriate DX or RX positions, respectively, are successfully received.
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if (m_bitCount == 10*3)
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{
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m_bitCount--;
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unsigned int pat = m_bits & 0x3fffffff;
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for (int i = 0; i < m_phasingPatterns.size(); i++)
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{
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if (pat == m_phasingPatterns[i].m_pattern)
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{
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m_dscDecoder.init(m_phasingPatterns[i].m_offset);
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m_gotSOP = true;
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m_bitCount = 0;
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m_rssiMagSqSum = 0.0;
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m_rssiMagSqCount = 0;
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break;
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}
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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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if (m_bitCount == 10)
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{
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if (m_dscDecoder.decodeBits(m_bits & 0x3ff))
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{
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QByteArray bytes = m_dscDecoder.getMessage();
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DSCMessage message(bytes, QDateTime::currentDateTime());
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//qDebug() << "RX Bytes: " << bytes.toHex();
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//qDebug() << "DSC Message: " << message.toString();
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if (getMessageQueueToChannel())
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{
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float rssi = CalcDb::dbPower(m_rssiMagSqSum / m_rssiMagSqCount);
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DSCDemod::MsgMessage *msg = DSCDemod::MsgMessage::create(message, m_dscDecoder.getErrors(), rssi);
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getMessageQueueToChannel()->push(msg);
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}
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// Reset demod
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init();
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}
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m_bitCount = 0;
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}
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}
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}
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void DSCDemodSink::applyChannelSettings(int channelSampleRate, int channelFrequencyOffset, bool force)
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{
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qDebug() << "DSCDemodSink::applyChannelSettings:"
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<< " channelSampleRate: " << channelSampleRate
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<< " channelFrequencyOffset: " << channelFrequencyOffset;
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if ((m_channelFrequencyOffset != channelFrequencyOffset) ||
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(m_channelSampleRate != channelSampleRate) || force)
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{
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m_nco.setFreq(-channelFrequencyOffset, channelSampleRate);
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}
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if ((m_channelSampleRate != channelSampleRate) || force)
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{
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m_interpolator.create(16, channelSampleRate, m_settings.m_rfBandwidth / 2.2);
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m_interpolatorDistance = (Real) channelSampleRate / (Real) DSCDemodSettings::DSCDEMOD_CHANNEL_SAMPLE_RATE;
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m_interpolatorDistanceRemain = m_interpolatorDistance;
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}
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m_channelSampleRate = channelSampleRate;
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m_channelFrequencyOffset = channelFrequencyOffset;
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}
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void DSCDemodSink::init()
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{
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m_expIdx = 0;
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m_bit = 0;
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m_bits = 0;
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m_bitCount = 0;
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m_gotSOP = false;
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m_errorCount = 0;
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m_clockCount = -m_samplesPerBit/2.0;
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m_clock = 0;
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m_int = 0.0;
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m_rssiMagSqSum = 0.0;
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m_rssiMagSqCount = 0;
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m_consecutiveErrors = 0;
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m_messageBuffer = "";
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}
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void DSCDemodSink::applySettings(const DSCDemodSettings& settings, bool force)
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{
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qDebug() << "DSCDemodSink::applySettings:"
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<< " m_rfBandwidth: " << settings.m_rfBandwidth
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<< " force: " << force;
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if ((settings.m_rfBandwidth != m_settings.m_rfBandwidth) || force)
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{
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m_interpolator.create(16, m_channelSampleRate, settings.m_rfBandwidth / 2.2);
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m_interpolatorDistance = (Real) m_channelSampleRate / (Real) DSCDemodSettings::DSCDEMOD_CHANNEL_SAMPLE_RATE;
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m_interpolatorDistanceRemain = m_interpolatorDistance;
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}
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if (force)
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{
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delete[] m_exp;
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m_exp = new Complex[m_expLength];
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Real f0 = 0.0f;
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for (int i = 0; i < m_expLength; i++)
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{
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m_exp[i] = Complex(cos(f0), sin(f0));
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f0 += 2.0f * (Real)M_PI * (DSCDemodSettings::DSCDEMOD_FREQUENCY_SHIFT/2.0f) / DSCDemodSettings::DSCDEMOD_CHANNEL_SAMPLE_RATE;
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}
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init();
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m_movMax1.setSize(m_samplesPerBit * 8);
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m_movMax2.setSize(m_samplesPerBit * 8);
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}
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m_settings = settings;
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}
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