mirror of
https://github.com/f4exb/sdrangel.git
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470 lines
16 KiB
C++
470 lines
16 KiB
C++
///////////////////////////////////////////////////////////////////////////////////
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// Copyright (C) 2023 Edouard Griffiths, F4EXB <f4exb06@gmail.com> //
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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 <complex.h>
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#include "dsp/dspengine.h"
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#include "dsp/scopevis.h"
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#include "util/stepfunctions.h"
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#include "util/db.h"
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#include "ilsdemod.h"
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#include "ilsdemodsink.h"
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ILSDemodSink::ILSDemodSink() :
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m_spectrumSink(nullptr),
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m_scopeSink(nullptr),
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m_channel(nullptr),
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m_channelSampleRate(ILSDemodSettings::ILSDEMOD_CHANNEL_SAMPLE_RATE),
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m_channelFrequencyOffset(0),
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m_audioSampleRate(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_fftSequence(-1),
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m_fft(nullptr),
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m_fftCounter(0),
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m_squelchLevel(0.001f),
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m_squelchCount(0),
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m_squelchOpen(false),
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m_squelchDelayLine(9600),
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m_volumeAGC(0.003),
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m_audioFifo(48000),
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m_sampleBufferIndex(0)
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{
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m_audioBuffer.resize(1<<14);
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m_audioBufferFill = 0;
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m_magsq = 0.0;
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m_sampleBuffer.resize(m_sampleBufferSize);
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m_spectrumSampleBuffer.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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m_fftWindow.create(FFTWindow::Flattop, m_fftSize);
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}
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ILSDemodSink::~ILSDemodSink()
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{
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}
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void ILSDemodSink::sampleToScope(Complex sample, Real demod)
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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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m_spectrumSampleBuffer[m_sampleBufferIndex] = Sample(demod * SDR_RX_SCALEF, 0);
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m_sampleBufferIndex++;
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if (m_sampleBufferIndex == m_sampleBufferSize)
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{
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if (m_scopeSink)
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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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}
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if (m_spectrumSink)
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{
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m_spectrumSink->feed(m_spectrumSampleBuffer.begin(), m_spectrumSampleBuffer.end(), false);
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}
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m_sampleBufferIndex = 0;
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}
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}
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void ILSDemodSink::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 ILSDemodSink::processOneSample(Complex &ci)
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{
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Complex ca;
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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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ci /= SDR_RX_SCALEF;
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// AM demodulation
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Complex demod = std::abs(ci);
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// Resample as audio
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if (m_audioInterpolatorDistance < 1.0f) // interpolate
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{
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while (!m_audioInterpolator.interpolate(&m_audioInterpolatorDistanceRemain, demod, &ca))
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{
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processOneAudioSample(ca);
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m_audioInterpolatorDistanceRemain += m_audioInterpolatorDistance;
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}
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}
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else // decimate
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{
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if (m_audioInterpolator.decimate(&m_audioInterpolatorDistanceRemain, demod, &ca))
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{
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processOneAudioSample(ca);
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m_audioInterpolatorDistanceRemain += m_audioInterpolatorDistance;
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}
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}
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// Decimate again for spectral analysis
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Complex demodDecim;
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if (m_decimator.decimate(demod, demodDecim))
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{
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// Use FFT to calculate sidebands modulation depth
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m_fft->in()[m_fftCounter] = demodDecim;
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m_fftCounter++;
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if (m_fftCounter == m_fftSize)
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{
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calcDDM();
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m_fftCounter = 0;
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// Send results to GUI
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if (getMessageQueueToChannel())
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{
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Real modDepth90, modDepth150, sdm, ddm;
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if (m_settings.m_average)
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{
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modDepth90 = m_modDepth90Average.instantAverage();
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modDepth150 = m_modDepth150Average.instantAverage();
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sdm = m_sdmAverage.instantAverage();
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ddm = m_ddmAverage.instantAverage();
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}
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else
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{
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modDepth90 = m_modDepth90;
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modDepth150 = m_modDepth150;
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sdm = m_sdm;
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ddm = m_ddm;
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}
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Real angle;
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if (m_settings.m_mode == ILSDemodSettings::LOC)
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{
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// For localiser, angle depends on runway length
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// At ILS datum (over threshold) (or ILS point B for short runways (<=1200m), which is 1050m from threshold)
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// the displacement sensitivity is 0.00145 DDM/metre (3.1.3.7)
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// The points at which DDM is 0.155 (i.e a displacement of 0.155/0.00154=~105m) define the course sector (3.1.3.7.3 Note 1)
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// And this must be <= 6 degrees (typically between 3-6degrees) (3.1.3.7.1)
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// Localilzer to threshold distances (geometric angle)
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// EGKK 3150m (3.8deg), EGKB 1840m (6.5deg), EGLL 3960m (3.0deg), EGLC 1570m(27) 1510m(09) (7.6/8deg) EGJJ 1710m (7deg)
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// FAS data for EGJJ https://nats-uk.ead-it.com/cms-nats/export/sites/default/en/Publications/AIP/Current-AIRAC/graphics/196515.pdf
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// LTP (Landing threshold point) 491231.8010N 0021105.6645W = 49.20883361 -2.18490681
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// FPAP 491224.8745N 0021228.7365W = 49.20690958 -2.20798236
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// Length offset 136m (distance from near threshold??)
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// LTP-FPAP=1690m D=1690+305=1995 (GARP is 305m/1000ft from FPAP)
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// EGJJ angle for 1995m = 6deg
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angle = ddm / 0.155f * (m_settings.m_courseWidth / 2.0f);
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}
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else
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{
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// For glide slope, sector is 0.175 DDM = 0.7 degrees
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// Displacement sensitivity 0.0875 at 0.12*theta (0.12*3=0.36deg) (3.1.5.6.2)
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// GP coverage is from 0.45*theta to 1.75*theta (5.25-1.35=4.9deg for 3deg GP)
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angle = 0.12f * m_settings.m_glidePath * ddm / 0.0875f;
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}
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ILSDemod::MsgAngleEstimate *msg = ILSDemod::MsgAngleEstimate::create(m_powerCarrier, m_power90, m_power150, modDepth90, modDepth150, sdm, ddm, angle);
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getMessageQueueToChannel()->push(msg);
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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(demod.real());
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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(demod.real());
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break;
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}
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sampleToScope(scopeSample, demod.real());
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}
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}
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void ILSDemodSink::processOneAudioSample(Complex &ci)
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{
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Real re = ci.real();
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Real im = ci.imag();
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Real magsq = re*re + im*im;
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m_audioMovingAverage(magsq);
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double magsqAvg = m_movingAverage.asDouble();
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m_squelchDelayLine.write(magsq);
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if (magsqAvg < m_squelchLevel)
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{
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if (m_squelchCount > 0) {
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m_squelchCount--;
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}
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}
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else
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{
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if (m_squelchCount < (unsigned int)m_audioSampleRate / 10) {
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m_squelchCount++;
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}
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}
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qint16 sample;
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m_squelchOpen = (m_squelchCount >= (unsigned int)m_audioSampleRate / 20);
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if (m_squelchOpen && !m_settings.m_audioMute)
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{
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Real demod;
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{
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demod = sqrt(m_squelchDelayLine.readBack(m_audioSampleRate/20));
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m_volumeAGC.feed(demod);
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demod = (demod - m_volumeAGC.getValue()) / m_volumeAGC.getValue();
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}
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demod = m_bandpass.filter(demod);
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Real attack = (m_squelchCount - 0.05f * m_audioSampleRate) / (0.05f * m_audioSampleRate);
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sample = demod * StepFunctions::smootherstep(attack) * (m_audioSampleRate/24) * m_settings.m_volume;
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}
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else
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{
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sample = 0;
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}
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m_audioBuffer[m_audioBufferFill].l = sample;
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m_audioBuffer[m_audioBufferFill].r = sample;
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++m_audioBufferFill;
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if (m_audioBufferFill >= m_audioBuffer.size())
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{
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std::size_t res = m_audioFifo.write((const quint8*)&m_audioBuffer[0], std::min(m_audioBufferFill, m_audioBuffer.size()));
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if (res != m_audioBufferFill)
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{
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qDebug("ILSDemodSink::processOneAudioSample: %lu/%lu audio samples written", res, m_audioBufferFill);
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m_audioFifo.clear();
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}
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m_audioBufferFill = 0;
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}
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m_morseDemod.processOneSample(ci);
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}
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Real ILSDemodSink::magSq(int bin) const
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{
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Complex c = m_fft->out()[bin];
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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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return magsq;
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}
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// Calculate the difference in the depth of modulation (DDM)
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void ILSDemodSink::calcDDM()
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{
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// 3.1.3.5.3 - the modulating tones shall be 90 Hz and 150 Hz within plus or minus 2.5 per cent
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// At 88/92Hz, some energy is lost in adjacent bin, so we use flat top windowing for accurate
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// amplitude measurement, which is what is needed for calculating depth of modulation
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m_fftWindow.apply(m_fft->in());
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// Perform FFT
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m_fft->transform();
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// Convert bin to frequency offset
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double frequencyResolution = ILSDemodSettings::ILSDEMOD_SPECTRUM_SAMPLE_RATE / (double)m_fftSize;
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int bin90 = 90.0 / frequencyResolution;
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int bin150 = 150.0 / frequencyResolution;
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double mag90, mag150;
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double magSqCarrier = magSq(0);
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double magCarrier = sqrt(magSqCarrier);
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// Add both sidebands
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mag90 = sqrt(magSq(bin90)) + sqrt(magSq(m_fftSize-bin90));
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mag150 = sqrt(magSq(bin150)) + sqrt(magSq(m_fftSize-bin150));
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// Calculate power in dB
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m_powerCarrier = CalcDb::dbPower(magSqCarrier);
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m_power90 = CalcDb::dbPower(mag90 * mag90);
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m_power150 = CalcDb::dbPower(mag150 * mag150);
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// Calculate modulation depth as % of carrier
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m_modDepth90 = mag90 / magCarrier * 100.0;
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m_modDepth150 = mag150 / magCarrier * 100.0;
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// Calculate modulation depth difference (https://www.youtube.com/watch?v=71iww_ERoYc)
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m_ddm = (m_modDepth90 - m_modDepth150) / 100.0;
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// Calculate sum of difference of modulation
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m_sdm = (m_modDepth90 + m_modDepth150) / 100.0;
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// Calculate moving averages
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m_modDepth90Average(m_modDepth90);
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m_modDepth150Average(m_modDepth150);
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m_sdmAverage(m_sdm);
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m_ddmAverage(m_ddm);
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}
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void ILSDemodSink::applyChannelSettings(int channelSampleRate, int channelFrequencyOffset, bool force)
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{
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qDebug() << "ILSDemodSink::applyChannelSettings:"
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<< " channelSampleRate: " << channelSampleRate
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<< " channelFrequencyOffset: " << channelFrequencyOffset;
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if ((m_channelFrequencyOffset != channelFrequencyOffset) ||
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(m_channelSampleRate != channelSampleRate) || force)
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{
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m_nco.setFreq(-channelFrequencyOffset, channelSampleRate);
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}
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if ((m_channelSampleRate != channelSampleRate) || force)
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{
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m_interpolator.create(16, channelSampleRate, m_settings.m_rfBandwidth / 2.2);
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m_interpolatorDistance = (Real) channelSampleRate / (Real) ILSDemodSettings::ILSDEMOD_CHANNEL_SAMPLE_RATE;
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m_interpolatorDistanceRemain = m_interpolatorDistance;
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}
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m_channelSampleRate = channelSampleRate;
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m_channelFrequencyOffset = channelFrequencyOffset;
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}
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void ILSDemodSink::applySettings(const ILSDemodSettings& settings, bool force)
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{
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qDebug() << "ILSDemodSink::applySettings:"
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<< " m_rfBandwidth: " << settings.m_rfBandwidth
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<< " m_volume: " << settings.m_volume
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<< " m_squelch: " << settings.m_squelch
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<< " m_audioMute: " << settings.m_audioMute
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<< " m_audioDeviceName: " << settings.m_audioDeviceName
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<< " force: " << force;
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if ((m_settings.m_squelch != settings.m_squelch) || force) {
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m_squelchLevel = CalcDb::powerFromdB(settings.m_squelch);
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}
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if ((settings.m_rfBandwidth != m_settings.m_rfBandwidth) || force)
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{
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m_interpolator.create(16, m_channelSampleRate, settings.m_rfBandwidth / 2.2);
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m_interpolatorDistance = (Real) m_channelSampleRate / (Real) ILSDemodSettings::ILSDEMOD_CHANNEL_SAMPLE_RATE;
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m_interpolatorDistanceRemain = m_interpolatorDistance;
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}
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if ((settings.m_identThreshold != m_settings.m_identThreshold) || force) {
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m_morseDemod.applySettings(settings.m_identThreshold);
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}
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if (force)
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{
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m_modDepth90Average.reset();
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m_modDepth150Average.reset();
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m_ddmAverage.reset();
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m_decimator.setLog2Decim(ILSDemodSettings::ILSDEMOD_SPECTRUM_DECIM_LOG2);
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}
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m_settings = settings;
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}
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void ILSDemodSink::applyAudioSampleRate(int sampleRate)
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{
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if (sampleRate < 0)
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{
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qWarning("ILSDemodSink::applyAudioSampleRate: invalid sample rate: %d", sampleRate);
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return;
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}
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qDebug("ILSDemodSink::applyAudioSampleRate: sampleRate: %d channelSampleRate: %d", sampleRate, ILSDemodSettings::ILSDEMOD_CHANNEL_SAMPLE_RATE);
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if (sampleRate != m_audioSampleRate)
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{
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m_audioInterpolator.create(16, ILSDemodSettings::ILSDEMOD_CHANNEL_SAMPLE_RATE, 3500.0f);
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m_audioInterpolatorDistanceRemain = 0;
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m_audioInterpolatorDistance = (Real) ILSDemodSettings::ILSDEMOD_CHANNEL_SAMPLE_RATE / (Real) sampleRate;
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m_bandpass.create(301, sampleRate, 300.0f, 3000.0f);
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//m_bandpass.printTaps("audio_bpf");
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m_audioFifo.setSize(sampleRate);
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m_squelchDelayLine.resize(sampleRate/5);
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m_volumeAGC.resizeNew(sampleRate/10, 0.003f);
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m_morseDemod.applyChannelSettings(sampleRate);
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}
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m_audioSampleRate = sampleRate;
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}
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