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535 lines
16 KiB
C++
535 lines
16 KiB
C++
///////////////////////////////////////////////////////////////////////////////////
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// Copyright (C) 2021-2022 Edouard Griffiths, F4EXB <f4exb06@gmail.com> //
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// Copyright (C) 2021 Jon Beniston, M7RCE <jon@beniston.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 "dsp/basebandsamplesink.h"
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#include "dsp/datafifo.h"
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#include "dsp/scopevis.h"
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#include "aismodsource.h"
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#include "util/crc.h"
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#include "util/messagequeue.h"
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#include "maincore.h"
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#include "channel/channelapi.h"
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AISModSource::AISModSource() :
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m_channelSampleRate(AISModSettings::AISMOD_SAMPLE_RATE),
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m_channelFrequencyOffset(0),
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m_fmPhase(0.0),
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m_spectrumSink(nullptr),
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m_scopeSink(nullptr),
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m_magsq(0.0),
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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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m_state(idle),
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m_byteIdx(0),
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m_bitIdx(0),
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m_last5Bits(0),
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m_bitCount(0),
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m_scopeSampleBufferIndex(0),
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m_specSampleBufferIndex(0)
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{
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m_demodBuffer.resize(1<<12);
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m_demodBufferFill = 0;
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m_scopeSampleBuffer.resize(m_scopeSampleBufferSize);
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m_specSampleBuffer.resize(m_specSampleBufferSize);
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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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AISModSource::~AISModSource()
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{
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}
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void AISModSource::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 AISModSource::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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return;
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}
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Complex ci;
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if (m_interpolatorDistance > 1.0f)
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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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// Calculate power
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double magsq = ci.real() * ci.real() + ci.imag() * ci.imag();
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m_movingAverage(magsq);
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m_magsq = m_movingAverage.asDouble();
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// Convert from float to fixed point
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sample.m_real = (FixReal) (ci.real() * SDR_TX_SCALEF);
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sample.m_imag = (FixReal) (ci.imag() * SDR_TX_SCALEF);
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}
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void AISModSource::sampleToSpectrum(Complex sample)
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{
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if (m_spectrumSink)
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{
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Real r = std::real(sample) * SDR_TX_SCALEF;
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Real i = std::imag(sample) * SDR_TX_SCALEF;
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m_specSampleBuffer[m_specSampleBufferIndex++] = Sample(r, i);
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if (m_specSampleBufferIndex == m_specSampleBufferSize)
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{
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m_spectrumSink->feed(m_specSampleBuffer.begin(), m_specSampleBuffer.end(), false);
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m_specSampleBufferIndex = 0;
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}
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}
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}
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void AISModSource::sampleToScope(Complex sample)
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{
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if (m_scopeSink)
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{
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Real r = std::real(sample) * SDR_RX_SCALEF;
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Real i = std::imag(sample) * SDR_RX_SCALEF;
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m_scopeSampleBuffer[m_scopeSampleBufferIndex++] = Sample(r, i);
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if (m_scopeSampleBufferIndex == m_scopeSampleBufferSize)
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{
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std::vector<SampleVector::const_iterator> vbegin;
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vbegin.push_back(m_scopeSampleBuffer.begin());
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m_scopeSink->feed(vbegin, m_scopeSampleBufferSize);
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m_scopeSampleBufferIndex = 0;
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}
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}
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}
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void AISModSource::modulateSample()
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{
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Real mod;
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Real linearRampGain;
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if ((m_state == idle) || (m_state == wait))
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{
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m_modSample.real(0.0f);
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m_modSample.imag(0.0f);
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sampleToSpectrum(m_modSample);
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sampleToScope(m_modSample);
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Real s = std::abs(m_modSample);
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calculateLevel(s);
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if (m_state == wait)
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{
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m_waitCounter--;
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if (m_waitCounter == 0) {
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initTX();
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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_sampleIdx == 0)
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{
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if (bitsValid())
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{
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// NRZI encoding - encode 0 as change of freq, 1 no change
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if (getBit() == 0) {
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m_nrziBit = m_nrziBit == 1 ? 0 : 1;
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}
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}
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// Should we start ramping down power?
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if ((m_bitCount < m_settings.m_rampDownBits) || ((m_bitCount == 0) && !m_settings.m_rampDownBits))
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{
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m_state = ramp_down;
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if (m_settings.m_rampDownBits > 0) {
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m_powRamp = -m_settings.m_rampRange/(m_settings.m_rampDownBits * (Real)m_samplesPerSymbol);
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}
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}
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}
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m_sampleIdx++;
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if (m_sampleIdx >= m_samplesPerSymbol) {
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m_sampleIdx = 0;
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}
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// Apply Gaussian pulse shaping filter
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mod = m_pulseShape.filter(m_nrziBit ? 1.0f : -1.0f);
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// FM
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m_fmPhase += m_phaseSensitivity * mod;
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// Keep phase in range -pi,pi
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if (m_fmPhase > M_PI) {
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m_fmPhase -= 2.0f * M_PI;
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} else if (m_fmPhase < -M_PI) {
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m_fmPhase += 2.0f * M_PI;
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}
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linearRampGain = powf(10.0f, m_pow/20.0f);
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m_modSample.real(m_linearGain * linearRampGain * cos(m_fmPhase));
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m_modSample.imag(m_linearGain * linearRampGain * sin(m_fmPhase));
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if (m_iqFile.is_open()) {
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m_iqFile << mod << "," << m_modSample.real() << "," << m_modSample.imag() << "\n";
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}
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if (m_settings.m_rfNoise)
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{
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// Noise to test filter frequency response
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m_modSample.real(m_linearGain * ((Real)rand()/((Real)RAND_MAX)-0.5f));
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m_modSample.imag(m_linearGain * ((Real)rand()/((Real)RAND_MAX)-0.5f));
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}
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// Display baseband in spectrum analyser and scope
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sampleToSpectrum(m_modSample);
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sampleToScope(m_modSample);
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// Ramp up/down power at start/end of packet
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if ((m_state == ramp_up) || (m_state == ramp_down))
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{
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m_pow += m_powRamp;
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if ((m_state == ramp_up) && (m_pow >= 0.0f))
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{
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// Finished ramp up, transmit at full gain
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m_state = tx;
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m_pow = 0.0f;
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}
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else if ((m_state == ramp_down) && ( (m_settings.m_rampRange == 0)
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|| (m_settings.m_rampDownBits == 0)
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|| (m_pow <= -(Real)m_settings.m_rampRange)
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))
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{
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m_state = idle;
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// Do we need to retransmit the packet?
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if (m_settings.m_repeat)
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{
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if (m_packetRepeatCount > 0)
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m_packetRepeatCount--;
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if ((m_packetRepeatCount == AISModSettings::infinitePackets) || (m_packetRepeatCount > 0))
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{
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if (m_settings.m_repeatDelay > 0.0f)
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{
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// Wait before retransmitting
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m_state = wait;
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m_waitCounter = m_settings.m_repeatDelay * AISModSettings::AISMOD_SAMPLE_RATE;
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}
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else
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{
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// Retransmit immediately
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initTX();
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}
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}
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}
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}
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}
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Real s = std::abs(m_modSample);
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calculateLevel(s);
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}
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// Send Gaussian filter output to mod analyzer
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m_demodBuffer[m_demodBufferFill] = std::real(mod) * std::numeric_limits<int16_t>::max();
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++m_demodBufferFill;
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if (m_demodBufferFill >= m_demodBuffer.size())
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{
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QList<ObjectPipe*> dataPipes;
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MainCore::instance()->getDataPipes().getDataPipes(m_channel, "demod", dataPipes);
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if (dataPipes.size() > 0)
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{
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QList<ObjectPipe*>::iterator it = dataPipes.begin();
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for (; it != dataPipes.end(); ++it)
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{
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DataFifo *fifo = qobject_cast<DataFifo*>((*it)->m_element);
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if (fifo) {
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fifo->write((quint8*) &m_demodBuffer[0], m_demodBuffer.size() * sizeof(qint16), DataFifo::DataTypeI16);
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}
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}
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}
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m_demodBufferFill = 0;
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}
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}
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void AISModSource::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 AISModSource::applySettings(const AISModSettings& settings, bool force)
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{
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if ((settings.m_bt != m_settings.m_bt)
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|| (settings.m_symbolSpan != m_settings.m_symbolSpan)
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|| (settings.m_baud != m_settings.m_baud) || force)
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{
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qDebug() << "AISModSource::applySettings: Recreating pulse shaping filter: "
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<< " SampleRate:" << AISModSettings::AISMOD_SAMPLE_RATE
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<< " bt: " << settings.m_bt
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<< " symbolSpan: " << settings.m_symbolSpan
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<< " baud:" << settings.m_baud
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<< " data:" << settings.m_data;
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m_pulseShape.create(settings.m_bt, settings.m_symbolSpan, AISModSettings::AISMOD_SAMPLE_RATE/settings.m_baud);
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}
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if ((settings.m_data != m_settings.m_data) || force)
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{
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qDebug() << "AISModSource::applySettings: new data: " << settings.m_data;
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addTXPacket(settings.m_data);
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}
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m_settings = settings;
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// Precalculate FM sensensity and linear gain to save doing it in the loop
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m_samplesPerSymbol = AISModSettings::AISMOD_SAMPLE_RATE / m_settings.m_baud;
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Real modIndex = m_settings.m_fmDeviation / (Real)m_settings.m_baud;
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m_phaseSensitivity = 2.0f * M_PI * modIndex / (Real)m_samplesPerSymbol;
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m_linearGain = powf(10.0f, m_settings.m_gain/20.0f);
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}
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void AISModSource::applyChannelSettings(int channelSampleRate, int channelFrequencyOffset, bool force)
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{
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qDebug() << "AISModSource::applyChannelSettings:"
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<< " channelSampleRate: " << channelSampleRate
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<< " channelFrequencyOffset: " << channelFrequencyOffset
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<< " rfBandwidth: " << m_settings.m_rfBandwidth;
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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 ((m_channelSampleRate != channelSampleRate) || force)
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{
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m_interpolatorDistanceRemain = 0;
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m_interpolatorDistance = (Real) AISModSettings::AISMOD_SAMPLE_RATE / (Real) channelSampleRate;
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m_interpolator.create(48, AISModSettings::AISMOD_SAMPLE_RATE, m_settings.m_rfBandwidth / 2.2, 3.0);
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}
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m_channelSampleRate = channelSampleRate;
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m_channelFrequencyOffset = channelFrequencyOffset;
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QList<ObjectPipe*> pipes;
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MainCore::instance()->getMessagePipes().getMessagePipes(m_channel, "reportdemod", pipes);
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if (pipes.size() > 0)
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{
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for (const auto& pipe : pipes)
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{
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MessageQueue* messageQueue = qobject_cast<MessageQueue*>(pipe->m_element);
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MainCore::MsgChannelDemodReport *msg = MainCore::MsgChannelDemodReport::create(m_channel, m_channelSampleRate);
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messageQueue->push(msg);
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}
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}
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}
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bool AISModSource::bitsValid()
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{
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return m_bitCount > 0;
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}
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int AISModSource::getBit()
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{
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int bit;
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if (m_bitCount > 0)
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{
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bit = (m_bits[m_byteIdx] >> m_bitIdx) & 1;
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m_bitIdx++;
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m_bitCount--;
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if (m_bitIdx == 8)
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{
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m_byteIdx++;
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m_bitIdx = 0;
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}
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}
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else
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bit = 0;
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return bit;
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}
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void AISModSource::addBit(int bit)
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{
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// Transmit LSB first
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m_bits[m_byteIdx] |= bit << m_bitIdx;
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m_bitIdx++;
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m_bitCount++;
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m_bitCountTotal++;
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if (m_bitIdx == 8)
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{
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m_byteIdx++;
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m_bits[m_byteIdx] = 0;
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m_bitIdx = 0;
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}
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m_last5Bits = ((m_last5Bits << 1) | bit) & 0x1f;
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}
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void AISModSource::initTX()
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{
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m_byteIdx = 0;
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m_bitIdx = 0;
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m_bitCount = m_bitCountTotal; // Reset to allow retransmission
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m_nrziBit = 1;
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if (m_settings.m_rampUpBits == 0)
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{
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m_state = tx;
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m_pow = 0.0f;
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}
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else
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{
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m_state = ramp_up;
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m_pow = -(Real)m_settings.m_rampRange;
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m_powRamp = m_settings.m_rampRange/(m_settings.m_rampUpBits * (Real)m_samplesPerSymbol);
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}
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}
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void AISModSource::addTXPacket(const QString& data)
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{
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QByteArray ba = QByteArray::fromHex(data.toUtf8());
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addTXPacket(ba);
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}
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void AISModSource::addTXPacket(QByteArray data)
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{
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uint8_t packet[AIS_MAX_BYTES];
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uint8_t *crc_start;
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uint8_t *packet_end;
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uint8_t *p;
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crc16x25 crc;
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uint16_t crcValue;
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int packet_length;
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// Create AIS message
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p = packet;
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// Training
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*p++ = AIS_TRAIN;
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*p++ = AIS_TRAIN;
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*p++ = AIS_TRAIN;
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// Flag
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*p++ = AIS_FLAG;
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crc_start = p;
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// Copy packet payload
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for (int i = 0; i < data.size(); i++) {
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*p++ = data[i];
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}
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// CRC (do not include flags)
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crc.calculate(crc_start, p-crc_start);
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crcValue = crc.get();
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*p++ = crcValue & 0xff;
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*p++ = (crcValue >> 8);
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packet_end = p;
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// Flag
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*p++ = AIS_FLAG;
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// Buffer
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*p++ = 0;
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packet_length = p-&packet[0];
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encodePacket(packet, packet_length, crc_start, packet_end);
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}
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void AISModSource::encodePacket(uint8_t *packet, int packet_length, uint8_t *crc_start, uint8_t *packet_end)
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{
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// HDLC bit stuffing
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m_byteIdx = 0;
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m_bitIdx = 0;
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m_last5Bits = 0;
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m_bitCount = 0;
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m_bitCountTotal = 0;
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for (int i = 0; i < packet_length; i++)
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{
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for (int j = 0; j < 8; j++)
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{
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int tx_bit = (packet[i] >> j) & 1;
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// Stuff 0 if last 5 bits are 1s, unless transmitting flag
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// Except for special case of when last 5 bits of CRC are 1s
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if ( ( (packet[i] != AIS_FLAG)
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|| ( (&packet[i] >= crc_start)
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&& ( (&packet[i] < packet_end)
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|
|| ((&packet[i] == packet_end) && (j == 0))
|
|
)
|
|
)
|
|
)
|
|
&& (m_last5Bits == 0x1f)
|
|
)
|
|
addBit(0);
|
|
addBit(tx_bit);
|
|
}
|
|
}
|
|
//m_samplesPerSymbol = AISMOD_SAMPLE_RATE / m_settings.m_baud;
|
|
m_packetRepeatCount = m_settings.m_repeatCount;
|
|
}
|
|
|
|
void AISModSource::transmit()
|
|
{
|
|
initTX();
|
|
// Only reset phases at start of new packet TX, not in initTX(), so that
|
|
// there isn't a discontinuity in phase when repeatedly transmitting a
|
|
// single tone
|
|
m_sampleIdx = 0;
|
|
m_fmPhase = 0.0;
|
|
|
|
if (m_settings.m_writeToFile)
|
|
m_iqFile.open("aismod.csv", std::ofstream::out);
|
|
else if (m_iqFile.is_open())
|
|
m_iqFile.close();
|
|
}
|