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https://github.com/f4exb/sdrangel.git
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437 lines
14 KiB
C++
437 lines
14 KiB
C++
///////////////////////////////////////////////////////////////////////////////////
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// Copyright (C) 2023 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 <cctype>
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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 "rttymod.h"
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#include "rttymodsource.h"
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#include "util/messagequeue.h"
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#include "maincore.h"
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RttyModSource::RttyModSource() :
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m_channelSampleRate(48000),
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m_channelFrequencyOffset(0),
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m_spectrumRate(2000),
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m_fmPhase(0.0),
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m_spectrumSink(nullptr),
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m_specSampleBufferIndex(0),
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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_byteIdx(0),
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m_bitIdx(0),
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m_bitCount(0)
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{
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m_bits.append(0);
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m_lowpass.create(301, m_channelSampleRate, 400.0 / 2.0);
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m_pulseShape.create(0.5, 6, m_channelSampleRate / 45.45, true);
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m_demodBuffer.resize(1<<12);
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m_demodBufferFill = 0;
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m_specSampleBuffer.resize(m_specSampleBufferSize);
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m_interpolatorDistanceRemain = 0;
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m_interpolatorConsumed = false;
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m_interpolatorDistance = (Real)m_channelSampleRate / (Real)m_spectrumRate;
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m_interpolator.create(48, m_spectrumRate, m_spectrumRate / 2.2, 3.0);
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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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RttyModSource::~RttyModSource()
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{
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}
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void RttyModSource::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 RttyModSource::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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// Calculate next sample
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modulateSample();
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// Shift to carrier frequency
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Complex ci = m_modSample;
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ci *= m_carrierNco.nextIQ();
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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 RttyModSource::sampleToSpectrum(Complex sample)
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{
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if (m_spectrumSink)
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{
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Complex out;
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if (m_interpolator.decimate(&m_interpolatorDistanceRemain, sample, &out))
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{
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m_interpolatorDistanceRemain += m_interpolatorDistance;
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Real r = std::real(out) * SDR_TX_SCALEF;
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Real i = std::imag(out) * 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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}
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void RttyModSource::modulateSample()
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{
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Real mod;
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if (m_sampleIdx == 0)
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{
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if (m_bitCount == 0)
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{
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if (!m_textToTransmit.isEmpty())
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{
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// Encode a character at a time, so we get a TxReport after each character
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QString s = m_textToTransmit.left(1);
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m_textToTransmit = m_textToTransmit.mid(1);
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encodeText(s);
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}
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else
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{
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// Transmit "diddle"
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encodeText(">");
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}
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initTX();
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}
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m_bit = getBit();
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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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// FSK
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if (m_settings.m_pulseShaping)
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{
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if (m_sampleIdx == 1) {
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mod = m_pulseShape.filter(m_bit ? 1.0f : -1.0f);
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} else {
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mod = m_pulseShape.filter(0.0f);
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}
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}
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else
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{
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mod = m_bit ? 1.0f : -1.0f;
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}
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// FM
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m_fmPhase += m_phaseSensitivity * mod * (m_settings.m_spaceHigh ? -1.0f : 1.0f);
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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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if (!m_settings.m_rfNoise)
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{
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m_modSample.real(m_linearGain * cos(m_fmPhase));
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m_modSample.imag(m_linearGain * sin(m_fmPhase));
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}
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else
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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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// Apply low pass filter to limit RF BW
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m_modSample = m_lowpass.filter(m_modSample);
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// Display in spectrum analyser
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sampleToSpectrum(m_modSample);
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Real s = std::real(m_modSample);
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calculateLevel(s);
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// Send to demod analyser
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m_demodBuffer[m_demodBufferFill] = 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 RttyModSource::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 RttyModSource::applySettings(const RttyModSettings& settings, bool force)
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{
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if ((settings.m_baud != m_settings.m_baud) || force)
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{
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m_samplesPerSymbol = m_channelSampleRate / settings.m_baud;
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qDebug() << "m_samplesPerSymbol: " << m_samplesPerSymbol << " (" << m_channelSampleRate << "/" << settings.m_baud << ")";
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}
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if ((settings.m_lpfTaps != m_settings.m_lpfTaps) || (settings.m_rfBandwidth != m_settings.m_rfBandwidth) || force)
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{
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qDebug() << "RttyModSource::applySettings: Creating new lpf with taps " << settings.m_lpfTaps << " rfBW " << settings.m_rfBandwidth;
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m_lowpass.create(settings.m_lpfTaps, m_channelSampleRate, settings.m_rfBandwidth / 2.0);
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}
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if ((settings.m_beta != m_settings.m_beta) || (settings.m_symbolSpan != m_settings.m_symbolSpan) || (settings.m_baud != m_settings.m_baud) || force)
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{
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qDebug() << "RttyModSource::applySettings: Recreating pulse shaping filter: "
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<< " beta: " << settings.m_beta
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<< " symbolSpan: " << settings.m_symbolSpan
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<< " channelSampleRate:" << m_channelSampleRate
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<< " baud:" << settings.m_baud;
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m_pulseShape.create(settings.m_beta, settings.m_symbolSpan, m_channelSampleRate/settings.m_baud, true);
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}
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if ((settings.m_characterSet != m_settings.m_characterSet) || force) {
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m_rttyEncoder.setCharacterSet(settings.m_characterSet);
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}
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if ((settings.m_unshiftOnSpace != m_settings.m_unshiftOnSpace) || force) {
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m_rttyEncoder.setUnshiftOnSpace(settings.m_unshiftOnSpace);
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}
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if ((settings.m_msbFirst != m_settings.m_msbFirst) || force) {
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m_rttyEncoder.setMsbFirst(settings.m_msbFirst);
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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_phaseSensitivity = 2.0f * M_PI * (m_settings.m_frequencyShift/2.0f) / (double)m_channelSampleRate;
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m_linearGain = powf(10.0f, m_settings.m_gain/20.0f);
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}
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void RttyModSource::applyChannelSettings(int channelSampleRate, int channelFrequencyOffset, bool force)
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{
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qDebug() << "RttyModSource::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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qDebug() << "RttyModSource::applyChannelSettings: Recreating filters";
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m_lowpass.create(m_settings.m_lpfTaps, channelSampleRate, m_settings.m_rfBandwidth / 2.0);
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qDebug() << "RttyModSource::applyChannelSettings: Recreating bandpass filter: "
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<< " channelSampleRate:" << channelSampleRate;
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qDebug() << "RttyModSource::applyChannelSettings: Recreating pulse shaping filter: "
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<< " beta: " << m_settings.m_beta
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<< " symbolSpan: " << m_settings.m_symbolSpan
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<< " channelSampleRate:" << m_channelSampleRate
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<< " baud:" << m_settings.m_baud;
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m_pulseShape.create(m_settings.m_beta, m_settings.m_symbolSpan, channelSampleRate/m_settings.m_baud, true);
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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_interpolatorConsumed = false;
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m_interpolatorDistance = (Real) channelSampleRate / (Real) m_spectrumRate;
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m_interpolator.create(48, m_spectrumRate, m_spectrumRate / 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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m_samplesPerSymbol = m_channelSampleRate / m_settings.m_baud;
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qDebug() << "m_samplesPerSymbol: " << m_samplesPerSymbol << " (" << m_channelSampleRate << "/" << m_settings.m_baud << ")";
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// Precalculate FM sensensity to save doing it in the loop
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m_phaseSensitivity = 2.0f * M_PI * (m_settings.m_frequencyShift/2.0f) / (double)m_channelSampleRate;
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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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int RttyModSource::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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{
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qDebug() << "RttyModSource::getBit: Called when empty";
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bit = 1;
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}
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return bit;
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}
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void RttyModSource::addBit(int bit)
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{
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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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if (m_bits.size() <= m_byteIdx) {
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m_bits.append(0);
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}
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m_bitIdx = 0;
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}
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}
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void RttyModSource::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_bit = 0;
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}
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void RttyModSource::addTXText(QString text)
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{
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int count = m_settings.m_repeat ? m_settings.m_repeatCount : 1;
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for (int i = 0; i < count; i++) {
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QString s = text;
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if (m_settings.m_prefixCRLF) {
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s.prepend("\r\r\n>"); // '>' switches to letters
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}
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if (m_settings.m_postfixCRLF) {
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s.append("\r\r\n");
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}
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m_textToTransmit.append(s);
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}
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}
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void RttyModSource::encodeText(const QString& text)
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{
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// RTTY encoding
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m_byteIdx = 0;
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m_bitIdx = 0;
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m_bitCount = 0;
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m_bitCountTotal = 0;
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for (int i = 0; i < m_bits.size(); i++) {
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m_bits[i] = 0;
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}
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QString s = text.toUpper(); // RTTY only supports upper case
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for (int i = 0; i < s.size(); i++)
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{
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unsigned bits;
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unsigned bitCount;
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m_rttyEncoder.encode(s[i], bits, bitCount);
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for (unsigned int j = 0; j < bitCount; j++)
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{
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int txBit = (bits >> j) & 1;
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addBit(txBit);
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}
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}
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if (getMessageQueueToGUI())
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{
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RttyMod::MsgReportTx* msg = RttyMod::MsgReportTx::create(s, m_textToTransmit.size());
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getMessageQueueToGUI()->push(msg);
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}
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}
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