mirror of
https://github.com/f4exb/sdrangel.git
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672 lines
21 KiB
C++
672 lines
21 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 <QDebug>
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#include <QRegularExpression>
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#include <complex.h>
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#include "dsp/dspengine.h"
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#include "dsp/fftfactory.h"
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#include "dsp/scopevis.h"
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#include "util/db.h"
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#include "rttydemod.h"
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#include "rttydemodsink.h"
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RttyDemodSink::RttyDemodSink(RttyDemod *packetDemod) :
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m_rttyDemod(packetDemod),
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m_channelSampleRate(RttyDemodSettings::RTTYDEMOD_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_expLength(600),
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m_prods1(nullptr),
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m_prods2(nullptr),
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m_exp(nullptr),
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m_sampleIdx(0),
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m_clockHistogram(100),
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m_shiftEstMag(m_fftSize),
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m_fftSequence(-1),
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m_fft(nullptr),
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m_fftCounter(0),
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m_sampleBufferIndex(0)
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{
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m_magsq = 0.0;
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m_sampleBuffer.resize(m_sampleBufferSize);
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applySettings(m_settings, true);
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applyChannelSettings(m_channelSampleRate, m_channelFrequencyOffset, true);
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FFTFactory *fftFactory = DSPEngine::instance()->getFFTFactory();
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if (m_fftSequence >= 0) {
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fftFactory->releaseEngine(m_fftSize, false, m_fftSequence);
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}
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m_fftSequence = fftFactory->getEngine(m_fftSize, false, &m_fft);
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m_fftCounter = 0;
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}
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RttyDemodSink::~RttyDemodSink()
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{
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delete[] m_exp;
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delete[] m_prods1;
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delete[] m_prods2;
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}
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void RttyDemodSink::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_sampleBuffer[m_sampleBufferIndex++] = Sample(r, i);
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if (m_sampleBufferIndex == m_sampleBufferSize)
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{
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std::vector<SampleVector::const_iterator> vbegin;
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vbegin.push_back(m_sampleBuffer.begin());
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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 RttyDemodSink::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 RttyDemodSink::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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// Use FFT to estimate frequency shift
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m_fft->in()[m_fftCounter] = ci;
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m_fftCounter++;
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if (m_fftCounter == m_fftSize)
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{
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estimateFrequencyShift();
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m_fftCounter = 0;
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}
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// Correlate with expected mark and space 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 exp = m_exp[m_sampleIdx];
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//qDebug() << "IQ " << real(ci) << imag(ci);
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Complex corr1 = ci * std::conj(exp); // Conj is high/mark freq (as for matched filter, we need to time reverse and take conjugate)
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Complex corr2 = ci * exp; // Low/space freq
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// Filter
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Real abs1, abs2;
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Real abs1Filt, abs2Filt;
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if (m_settings.m_filter == RttyDemodSettings::LOWPASS)
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{
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// Low pass filter
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abs1Filt = abs1 = std::abs(m_lowpassComplex1.filter(corr1));
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abs2Filt = abs2 = std::abs(m_lowpassComplex2.filter(corr2));
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}
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else if ( (m_settings.m_filter == RttyDemodSettings::COSINE_B_1)
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|| (m_settings.m_filter == RttyDemodSettings::COSINE_B_0_75)
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|| (m_settings.m_filter == RttyDemodSettings::COSINE_B_0_5)
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)
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{
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// Rasised cosine filter
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abs1Filt = abs1 = std::abs(m_raisedCosine1.filter(corr1));
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abs2Filt = abs2 = std::abs(m_raisedCosine2.filter(corr2));
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}
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else
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{
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// Moving average
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// Calculating moving average (well windowed sum)
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Complex old1 = m_prods1[m_sampleIdx];
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Complex old2 = m_prods2[m_sampleIdx];
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m_prods1[m_sampleIdx] = corr1;
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m_prods2[m_sampleIdx] = corr2;
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m_sum1 += m_prods1[m_sampleIdx] - old1;
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m_sum2 += m_prods2[m_sampleIdx] - old2;
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m_sampleIdx = (m_sampleIdx + 1) % m_samplesPerBit;
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// Square signals (by calculating absolute value of complex signal)
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abs1 = std::abs(m_sum1);
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abs2 = std::abs(m_sum2);
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// Apply optional low-pass filter to try to avoid extra zero-crassings above the baud rate
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if (m_settings.m_filter == RttyDemodSettings::FILTERED_MAV)
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{
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abs1Filt = m_lowpass1.filter(abs1);
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abs2Filt = m_lowpass2.filter(abs2);
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}
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else
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{
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abs1Filt = abs1;
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abs2Filt = abs2;
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}
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}
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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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if (m_settings.m_spaceHigh) {
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m_data = m_settings.m_atc ? biasedData < 0 : unbiasedData < 0;
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} else {
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m_data = m_settings.m_atc ? biasedData > 0 : unbiasedData > 0;
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}
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if (!m_gotSOP)
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{
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// Look for falling edge which indicates start bit
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if (!m_data && m_dataPrev)
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{
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m_gotSOP = true;
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m_bits = 0;
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m_bitCount = 0;
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m_clockCount = 0;
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m_clock = false;
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m_cycleCount = 0;
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m_rssiMagSqSum = 0.0;
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m_rssiMagSqCount = 0;
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}
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}
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else
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{
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// Sample in middle of symbol
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if (m_clockCount == m_samplesPerBit/2)
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{
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receiveBit(m_data);
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m_clock = true;
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}
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m_clockCount = (m_clockCount + 1) % m_samplesPerBit;
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if (m_clockCount == 0) {
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m_clock = false;
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}
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// Count cycles between edges, to estimate baud rate
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m_cycleCount++;
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if (m_data != m_dataPrev)
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{
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if (m_cycleCount < m_clockHistogram.size())
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{
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m_clockHistogram[m_cycleCount]++;
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m_edgeCount++;
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// Every 100 edges, calculate estimate
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if (m_edgeCount == 100) {
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estimateBaudRate();
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}
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}
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m_cycleCount = 0;
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}
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}
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// Select signals to feed to scope
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Complex scopeSample;
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switch (m_settings.m_scopeCh1)
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{
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case 0:
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scopeSample.real(ci.real());
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break;
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case 1:
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scopeSample.real(ci.imag());
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break;
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case 2:
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scopeSample.real(magsq);
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break;
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case 3:
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scopeSample.real(m_sampleIdx);
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break;
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case 4:
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scopeSample.real(abs(m_sum1));
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break;
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case 5:
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scopeSample.real(abs(m_sum2));
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break;
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case 6:
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scopeSample.real(m_bit);
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break;
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case 7:
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scopeSample.real(m_bitCount);
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break;
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case 8:
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scopeSample.real(m_gotSOP);
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break;
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case 9:
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scopeSample.real(real(exp));
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break;
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case 10:
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scopeSample.real(imag(exp));
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break;
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case 11:
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scopeSample.real(abs1Filt);
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break;
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case 12:
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scopeSample.real(abs2Filt);
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break;
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case 13:
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scopeSample.real(abs2 - abs1);
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break;
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case 14:
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scopeSample.real(abs2Filt - abs1Filt);
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break;
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case 15:
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scopeSample.real(m_data);
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break;
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case 16:
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scopeSample.real(m_clock);
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break;
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case 17:
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scopeSample.real(env1);
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break;
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case 18:
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scopeSample.real(env2);
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break;
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case 19:
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scopeSample.real(bias1);
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break;
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case 20:
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scopeSample.real(bias2);
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break;
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case 21:
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scopeSample.real(unbiasedData);
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break;
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case 22:
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scopeSample.real(biasedData);
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break;
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}
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switch (m_settings.m_scopeCh2)
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{
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case 0:
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scopeSample.imag(ci.real());
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break;
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case 1:
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scopeSample.imag(ci.imag());
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break;
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case 2:
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scopeSample.imag(magsq);
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break;
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case 3:
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scopeSample.imag(m_sampleIdx);
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break;
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case 4:
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scopeSample.imag(abs(m_sum1));
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break;
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case 5:
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scopeSample.imag(abs(m_sum2));
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break;
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case 6:
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scopeSample.imag(m_bit);
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break;
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case 7:
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scopeSample.imag(m_bitCount);
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break;
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case 8:
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scopeSample.imag(m_gotSOP);
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break;
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case 9:
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scopeSample.imag(real(exp));
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break;
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case 10:
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scopeSample.imag(imag(exp));
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break;
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case 11:
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scopeSample.imag(abs1Filt);
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break;
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case 12:
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scopeSample.imag(abs2Filt);
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break;
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case 13:
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scopeSample.imag(abs2 - abs1);
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break;
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case 14:
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scopeSample.imag(abs2Filt - abs1Filt);
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break;
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case 15:
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scopeSample.imag(m_data);
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break;
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case 16:
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scopeSample.imag(m_clock);
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break;
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case 17:
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scopeSample.imag(env1);
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break;
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case 18:
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scopeSample.imag(env2);
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break;
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case 19:
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scopeSample.imag(bias1);
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break;
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case 20:
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scopeSample.imag(bias2);
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break;
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case 21:
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scopeSample.imag(unbiasedData);
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break;
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case 22:
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scopeSample.imag(biasedData);
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break;
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}
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sampleToScope(scopeSample);
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}
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void RttyDemodSink::estimateFrequencyShift()
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{
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// Perform FFT
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m_fft->transform();
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// Calculate magnitude
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for (int i = 0; i < m_fftSize; i++)
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{
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Complex c = m_fft->out()[i];
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Real v = c.real() * c.real() + c.imag() * c.imag();
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Real magsq = v / (m_fftSize * m_fftSize);
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m_shiftEstMag[i] = magsq;
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}
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// Fink peaks in each half
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Real peak1 = m_shiftEstMag[0];
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int peak1Bin = 0;
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for (int i = 1; i < m_fftSize/2; i++)
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{
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if (m_shiftEstMag[i] > peak1)
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{
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peak1 = m_shiftEstMag[i];
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peak1Bin = i;
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}
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}
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Real peak2 = m_shiftEstMag[m_fftSize/2];
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int peak2Bin = m_fftSize/2;
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for (int i = m_fftSize/2+1; i < m_fftSize; i++)
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{
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if (m_shiftEstMag[i] > peak2)
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{
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peak2 = m_shiftEstMag[i];
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peak2Bin = i;
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}
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}
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// Convert bin to frequency offset
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double frequencyResolution = RttyDemodSettings::RTTYDEMOD_CHANNEL_SAMPLE_RATE / (double)m_fftSize;
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double freq1 = frequencyResolution * peak1Bin;
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double freq2 = -frequencyResolution * (m_fftSize - peak2Bin);
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m_freq1Average(freq1);
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m_freq2Average(freq2);
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//int shift = m_freq1Average.instantAverage() - m_freq2Average.instantAverage();
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//qDebug() << "Freq est " << freq1 << freq2 << shift;
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}
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int RttyDemodSink::estimateBaudRate()
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{
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// Find most frequent entry in histogram
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auto histMax = max_element(m_clockHistogram.begin(), m_clockHistogram.end());
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int index = std::distance(m_clockHistogram.begin(), histMax);
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// Calculate baud rate as weighted average
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Real baud1 = RttyDemodSettings::RTTYDEMOD_CHANNEL_SAMPLE_RATE / (Real)(index-1);
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int count1 = m_clockHistogram[index-1];
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Real baud2 = RttyDemodSettings::RTTYDEMOD_CHANNEL_SAMPLE_RATE / (Real)(index);
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int count2 = m_clockHistogram[index];
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Real baud3 = RttyDemodSettings::RTTYDEMOD_CHANNEL_SAMPLE_RATE / (Real)(index+1);
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int count3 = m_clockHistogram[index+1];
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Real total = count1 + count2 + count3;
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Real estBaud = count1/total*baud1 + count2/total*baud2 + count3/total*baud3;
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m_baudRateAverage(estBaud);
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// Send estimate to GUI
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if (getMessageQueueToChannel())
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{
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int estFrequencyShift = m_freq1Average.instantAverage() - m_freq2Average.instantAverage();
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RttyDemod::MsgModeEstimate *msg = RttyDemod::MsgModeEstimate::create(m_baudRateAverage.instantAverage(), estFrequencyShift);
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getMessageQueueToChannel()->push(msg);
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}
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// Restart estimation
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std::fill(m_clockHistogram.begin(), m_clockHistogram.end(), 0);
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m_edgeCount = 0;
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return estBaud;
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}
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void RttyDemodSink::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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if (m_settings.m_msbFirst) {
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m_bits = (m_bit & 0x1) | (m_bits << 1);
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} else {
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m_bits = (m_bit << 6) | (m_bits >> 1);
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}
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m_bitCount++;
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if (m_bitCount == 7)
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{
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if ( (!m_settings.m_msbFirst && ((m_bits & 0x40) != 0x40))
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|| (m_settings.m_msbFirst && ((m_bits & 0x01) != 0x01)))
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{
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//qDebug() << "No stop bit";
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}
|
|
else
|
|
{
|
|
QString c = m_rttyDecoder.decode((m_bits >> 1) & 0x1f);
|
|
if ((c != "\0") && (c != "<") && (c != ">") && (c != "^"))
|
|
{
|
|
// Calculate average power over received byte
|
|
float rssi = CalcDb::dbPower(m_rssiMagSqSum / m_rssiMagSqCount);
|
|
if (rssi > m_settings.m_squelch)
|
|
{
|
|
// Slow enough to send individually to be displayed
|
|
if (getMessageQueueToChannel())
|
|
{
|
|
RttyDemod::MsgCharacter *msg = RttyDemod::MsgCharacter::create(c);
|
|
getMessageQueueToChannel()->push(msg);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
m_gotSOP = false;
|
|
}
|
|
}
|
|
|
|
void RttyDemodSink::applyChannelSettings(int channelSampleRate, int channelFrequencyOffset, bool force)
|
|
{
|
|
qDebug() << "RttyDemodSink::applyChannelSettings:"
|
|
<< " channelSampleRate: " << channelSampleRate
|
|
<< " channelFrequencyOffset: " << channelFrequencyOffset;
|
|
|
|
if ((m_channelFrequencyOffset != channelFrequencyOffset) ||
|
|
(m_channelSampleRate != channelSampleRate) || force)
|
|
{
|
|
m_nco.setFreq(-channelFrequencyOffset, channelSampleRate);
|
|
}
|
|
|
|
if ((m_channelSampleRate != channelSampleRate) || force)
|
|
{
|
|
m_interpolator.create(16, channelSampleRate, m_settings.m_rfBandwidth / 2.2);
|
|
m_interpolatorDistance = (Real) channelSampleRate / (Real) RttyDemodSettings::RTTYDEMOD_CHANNEL_SAMPLE_RATE;
|
|
m_interpolatorDistanceRemain = m_interpolatorDistance;
|
|
}
|
|
|
|
m_channelSampleRate = channelSampleRate;
|
|
m_channelFrequencyOffset = channelFrequencyOffset;
|
|
}
|
|
|
|
void RttyDemodSink::init()
|
|
{
|
|
m_sampleIdx = 0;
|
|
m_expIdx = 0;
|
|
m_sum1 = 0.0;
|
|
m_sum2 = 0.0;
|
|
for (int i = 0; i < m_samplesPerBit; i++)
|
|
{
|
|
m_prods1[i] = 0.0f;
|
|
m_prods2[i] = 0.0f;
|
|
}
|
|
m_bit = 0;
|
|
m_bits = 0;
|
|
m_bitCount = 0;
|
|
m_gotSOP = false;
|
|
m_clockCount = 0;
|
|
m_clock = 0;
|
|
m_rssiMagSqSum = 0.0;
|
|
m_rssiMagSqCount = 0;
|
|
m_rttyDecoder.init();
|
|
}
|
|
|
|
void RttyDemodSink::applySettings(const RttyDemodSettings& settings, bool force)
|
|
{
|
|
qDebug() << "RttyDemodSink::applySettings:"
|
|
<< " m_rfBandwidth: " << settings.m_rfBandwidth
|
|
<< " m_baudRate: " << settings.m_baudRate
|
|
<< " m_frequencyShift: " << settings.m_frequencyShift
|
|
<< " m_characterSet: " << settings.m_characterSet
|
|
<< " m_unshiftOnSpace: " << settings.m_unshiftOnSpace
|
|
<< " force: " << force;
|
|
|
|
if ((settings.m_rfBandwidth != m_settings.m_rfBandwidth) || force)
|
|
{
|
|
m_interpolator.create(16, m_channelSampleRate, settings.m_rfBandwidth / 2.2);
|
|
m_interpolatorDistance = (Real) m_channelSampleRate / (Real) RttyDemodSettings::RTTYDEMOD_CHANNEL_SAMPLE_RATE;
|
|
m_interpolatorDistanceRemain = m_interpolatorDistance;
|
|
}
|
|
|
|
if ((settings.m_baudRate != m_settings.m_baudRate) || (settings.m_filter != m_settings.m_filter) || force)
|
|
{
|
|
m_envelope1.create(301, RttyDemodSettings::RTTYDEMOD_CHANNEL_SAMPLE_RATE, 2);
|
|
m_envelope2.create(301, RttyDemodSettings::RTTYDEMOD_CHANNEL_SAMPLE_RATE, 2);
|
|
m_lowpass1.create(301, RttyDemodSettings::RTTYDEMOD_CHANNEL_SAMPLE_RATE, m_settings.m_baudRate * 1.1);
|
|
m_lowpass2.create(301, RttyDemodSettings::RTTYDEMOD_CHANNEL_SAMPLE_RATE, m_settings.m_baudRate * 1.1);
|
|
//m_lowpass1.printTaps("lpf");
|
|
|
|
m_lowpassComplex1.create(301, RttyDemodSettings::RTTYDEMOD_CHANNEL_SAMPLE_RATE, m_settings.m_baudRate * 1.1);
|
|
m_lowpassComplex2.create(301, RttyDemodSettings::RTTYDEMOD_CHANNEL_SAMPLE_RATE, m_settings.m_baudRate * 1.1);
|
|
//m_lowpass1.printTaps("lpfc");
|
|
|
|
// http://w7ay.net/site/Technical/Extended%20Nyquist%20Filters/index.html
|
|
// http://w7ay.net/site/Technical/EqualizedRaisedCosine/index.html
|
|
float beta = 1.0f;
|
|
float bw = 1.0f;
|
|
if (settings.m_filter == RttyDemodSettings::COSINE_B_0_5) {
|
|
beta = 0.5f;
|
|
} else if (settings.m_filter == RttyDemodSettings::COSINE_B_0_75) {
|
|
beta = 0.75f;
|
|
} else if (settings.m_filter == RttyDemodSettings::COSINE_B_1_BW_0_75) {
|
|
bw = 0.75f;
|
|
} else if (settings.m_filter == RttyDemodSettings::COSINE_B_1_BW_1_25) {
|
|
bw = 1.25f;
|
|
}
|
|
m_raisedCosine1.create(beta, 7, RttyDemodSettings::RTTYDEMOD_CHANNEL_SAMPLE_RATE/(m_settings.m_baudRate/bw), false);
|
|
m_raisedCosine2.create(beta, 7, RttyDemodSettings::RTTYDEMOD_CHANNEL_SAMPLE_RATE/(m_settings.m_baudRate/bw), false);
|
|
//m_raisedCosine1.printTaps("rcos");
|
|
}
|
|
|
|
if ((settings.m_characterSet != m_settings.m_characterSet) || force) {
|
|
m_rttyDecoder.setCharacterSet(settings.m_characterSet);
|
|
}
|
|
if ((settings.m_unshiftOnSpace != m_settings.m_unshiftOnSpace) || force) {
|
|
m_rttyDecoder.setUnshiftOnSpace(settings.m_unshiftOnSpace);
|
|
}
|
|
|
|
if ((settings.m_baudRate != m_settings.m_baudRate) || (settings.m_frequencyShift != m_settings.m_frequencyShift) || force)
|
|
{
|
|
delete[] m_exp;
|
|
delete[] m_prods1;
|
|
delete[] m_prods2;
|
|
m_samplesPerBit = RttyDemodSettings::RTTYDEMOD_CHANNEL_SAMPLE_RATE / settings.m_baudRate;
|
|
m_exp = new Complex[m_expLength];
|
|
m_prods1 = new Complex[m_samplesPerBit];
|
|
m_prods2 = new Complex[m_samplesPerBit];
|
|
Real f0 = 0.0f;
|
|
for (int i = 0; i < m_expLength; i++)
|
|
{
|
|
m_exp[i] = Complex(cos(f0), sin(f0));
|
|
f0 += 2.0f * (Real)M_PI * (settings.m_frequencyShift/2.0f) / RttyDemodSettings::RTTYDEMOD_CHANNEL_SAMPLE_RATE;
|
|
}
|
|
init();
|
|
|
|
// Due to start and stop bits, we should get mark and space at least every 8 bits
|
|
// while something is being transmitted
|
|
m_movMax1.setSize(m_samplesPerBit * 8);
|
|
m_movMax2.setSize(m_samplesPerBit * 8);
|
|
|
|
m_edgeCount = 0;
|
|
std::fill(m_clockHistogram.begin(), m_clockHistogram.end(), 0);
|
|
|
|
m_baudRateAverage.reset();
|
|
m_freq1Average.reset();
|
|
m_freq2Average.reset();
|
|
}
|
|
|
|
m_settings = settings;
|
|
}
|
|
|