mirror of
https://github.com/f4exb/sdrangel.git
synced 2024-11-13 20:01:46 -05:00
454 lines
18 KiB
C++
454 lines
18 KiB
C++
///////////////////////////////////////////////////////////////////////////////////
|
|
// Copyright (C) 2021, 2023 Jon Beniston, M7RCE <jon@beniston.com> //
|
|
// Copyright (C) 2021-2022 Edouard Griffiths, F4EXB <f4exb06@gmail.com> //
|
|
// //
|
|
// This program is free software; you can redistribute it and/or modify //
|
|
// it under the terms of the GNU General Public License as published by //
|
|
// the Free Software Foundation as version 3 of the License, or //
|
|
// (at your option) any later version. //
|
|
// //
|
|
// This program is distributed in the hope that it will be useful, //
|
|
// but WITHOUT ANY WARRANTY; without even the implied warranty of //
|
|
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the //
|
|
// GNU General Public License V3 for more details. //
|
|
// //
|
|
// You should have received a copy of the GNU General Public License //
|
|
// along with this program. If not, see <http://www.gnu.org/licenses/>. //
|
|
///////////////////////////////////////////////////////////////////////////////////
|
|
|
|
#include <QDebug>
|
|
|
|
#include <complex.h>
|
|
|
|
#include "dsp/datafifo.h"
|
|
#include "dsp/scopevis.h"
|
|
#include "device/deviceapi.h"
|
|
#include "channel/channelwebapiutils.h"
|
|
#include "maincore.h"
|
|
|
|
#include "aisdemod.h"
|
|
#include "aisdemodsink.h"
|
|
|
|
AISDemodSink::AISDemodSink(AISDemod *aisDemod) :
|
|
m_scopeSink(nullptr),
|
|
m_aisDemod(aisDemod),
|
|
m_channelSampleRate(AISDemodSettings::AISDEMOD_CHANNEL_SAMPLE_RATE),
|
|
m_channelFrequencyOffset(0),
|
|
m_magsqSum(0.0f),
|
|
m_magsqPeak(0.0f),
|
|
m_magsqCount(0),
|
|
m_messageQueueToChannel(nullptr),
|
|
m_rxBuf(nullptr),
|
|
m_train(nullptr),
|
|
m_sampleBufferIndex(0)
|
|
{
|
|
m_magsq = 0.0;
|
|
|
|
m_demodBuffer.resize(1<<12);
|
|
m_demodBufferFill = 0;
|
|
for (int i = 0; i < AISDemodSettings::m_scopeStreams; i++) {
|
|
m_sampleBuffer[i].resize(m_sampleBufferSize);
|
|
}
|
|
|
|
applySettings(m_settings, true);
|
|
applyChannelSettings(m_channelSampleRate, m_channelFrequencyOffset, true);
|
|
}
|
|
|
|
AISDemodSink::~AISDemodSink()
|
|
{
|
|
delete[] m_rxBuf;
|
|
delete[] m_train;
|
|
}
|
|
|
|
void AISDemodSink::sampleToScope(Complex sample, Real magsq, Real fmDemod, Real filt, Real rxBuf, Real corr, Real thresholdMet, Real dcOffset, Real crcValid)
|
|
{
|
|
if (m_scopeSink)
|
|
{
|
|
m_sampleBuffer[0][m_sampleBufferIndex] = sample;
|
|
m_sampleBuffer[1][m_sampleBufferIndex] = Complex(magsq, 0.0f);
|
|
m_sampleBuffer[2][m_sampleBufferIndex] = Complex(fmDemod, 0.0f);
|
|
m_sampleBuffer[3][m_sampleBufferIndex] = Complex(filt, 0.0f);
|
|
m_sampleBuffer[4][m_sampleBufferIndex] = Complex(rxBuf, 0.0f);
|
|
m_sampleBuffer[5][m_sampleBufferIndex] = Complex(corr, 0.0f);
|
|
m_sampleBuffer[6][m_sampleBufferIndex] = Complex(thresholdMet, 0.0f);
|
|
m_sampleBuffer[7][m_sampleBufferIndex] = Complex(dcOffset, 0.0f);
|
|
m_sampleBuffer[8][m_sampleBufferIndex] = Complex(crcValid, 0.0f);
|
|
m_sampleBufferIndex++;
|
|
if (m_sampleBufferIndex == m_sampleBufferSize)
|
|
{
|
|
std::vector<ComplexVector::const_iterator> vbegin;
|
|
|
|
for (int i = 0; i < AISDemodSettings::m_scopeStreams; i++) {
|
|
vbegin.push_back(m_sampleBuffer[i].begin());
|
|
}
|
|
|
|
m_scopeSink->feed(vbegin, m_sampleBufferSize);
|
|
m_sampleBufferIndex = 0;
|
|
}
|
|
}
|
|
}
|
|
|
|
void AISDemodSink::feed(const SampleVector::const_iterator& begin, const SampleVector::const_iterator& end)
|
|
{
|
|
Complex ci;
|
|
|
|
for (SampleVector::const_iterator it = begin; it != end; ++it)
|
|
{
|
|
Complex c(it->real(), it->imag());
|
|
c *= m_nco.nextIQ();
|
|
|
|
if (m_interpolatorDistance < 1.0f) // interpolate
|
|
{
|
|
while (!m_interpolator.interpolate(&m_interpolatorDistanceRemain, c, &ci))
|
|
{
|
|
processOneSample(ci);
|
|
m_interpolatorDistanceRemain += m_interpolatorDistance;
|
|
}
|
|
}
|
|
else // decimate
|
|
{
|
|
if (m_interpolator.decimate(&m_interpolatorDistanceRemain, c, &ci))
|
|
{
|
|
processOneSample(ci);
|
|
m_interpolatorDistanceRemain += m_interpolatorDistance;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
void AISDemodSink::processOneSample(Complex &ci)
|
|
{
|
|
Complex ca;
|
|
|
|
// FM demodulation
|
|
double magsqRaw;
|
|
Real deviation;
|
|
Real fmDemod = m_phaseDiscri.phaseDiscriminatorDelta(ci, magsqRaw, deviation);
|
|
|
|
// Calculate average and peak levels for level meter
|
|
Real magsq = magsqRaw / (SDR_RX_SCALED*SDR_RX_SCALED);
|
|
m_movingAverage(magsq);
|
|
m_magsq = m_movingAverage.asDouble();
|
|
m_magsqSum += magsq;
|
|
if (magsq > m_magsqPeak)
|
|
{
|
|
m_magsqPeak = magsq;
|
|
}
|
|
m_magsqCount++;
|
|
|
|
// Gaussian filter
|
|
Real filt = m_pulseShape.filter(fmDemod);
|
|
|
|
// An input frequency offset corresponds to a DC offset after FM demodulation
|
|
// AIS spec allows up to +-1kHz offset
|
|
// We need to remove this, otherwise it may effect the sampling
|
|
// To calculate what it is, we sum the training sequence, which should be zero
|
|
|
|
// Clip, as large noise can result in high correlation
|
|
// Don't clip to 1.0 - as there may be some DC offset (1k/4.8k max dev=0.2)
|
|
Real filtClipped;
|
|
filtClipped = std::fmax(-1.4, std::fmin(1.4, filt));
|
|
|
|
// Buffer filtered samples. We buffer enough samples for a max length message
|
|
// before trying to demod, so false triggering can't make us miss anything
|
|
m_rxBuf[m_rxBufIdx] = filtClipped;
|
|
m_rxBufIdx = (m_rxBufIdx + 1) % m_rxBufLength;
|
|
m_rxBufCnt = std::min(m_rxBufCnt + 1, m_rxBufLength);
|
|
|
|
Real corr = 0.0f;
|
|
bool scopeCRCValid = false;
|
|
bool scopeCRCInvalid = false;
|
|
Real dcOffset = 0.0f;
|
|
bool thresholdMet = false;
|
|
if (m_rxBufCnt >= m_rxBufLength)
|
|
{
|
|
Real trainingSum = 0.0f;
|
|
|
|
// Correlate with training sequence
|
|
// Note that DC offset doesn't matter for this
|
|
// Calculate sum to estimate DC offset
|
|
for (int i = 0; i < m_correlationLength; i++)
|
|
{
|
|
int j = (m_rxBufIdx + i) % m_rxBufLength;
|
|
corr += m_train[i] * m_rxBuf[j];
|
|
trainingSum += m_rxBuf[j];
|
|
}
|
|
|
|
// If we meet threshold, try to demod
|
|
// Take abs value, to account for both initial phases
|
|
thresholdMet = fabs(corr) >= m_settings.m_correlationThreshold;
|
|
if (thresholdMet)
|
|
{
|
|
// Use mean of preamble as DC offset
|
|
dcOffset = trainingSum/m_correlationLength;
|
|
|
|
// Start demod after (most of) preamble
|
|
int x = (m_rxBufIdx + m_correlationLength*3/4 + 4) % m_rxBufLength;
|
|
|
|
// Attempt to demodulate
|
|
bool gotSOP = false;
|
|
int bits = 0;
|
|
int bitCount = 0;
|
|
int onesCount = 0;
|
|
int byteCount = 0;
|
|
int symbolPrev = 0;
|
|
int totalBitCount = 0; // Count of bits after start flag, before bit stuffing removal, including stop flag
|
|
for (int sampleIdx = 0; sampleIdx < m_rxBufLength; sampleIdx += m_samplesPerSymbol)
|
|
{
|
|
// Sum and slice
|
|
// Summing 3 samples seems to give a very small improvement vs just using 1
|
|
int sampleCnt = 3;
|
|
int sampleOffset = -1;
|
|
Real sampleSum = 0.0f;
|
|
for (int i = 0; i < sampleCnt; i++) {
|
|
sampleSum += m_rxBuf[(x + sampleOffset + i) % m_rxBufLength] - dcOffset;
|
|
}
|
|
int symbol = sampleSum >= 0.0f ? 1 : 0;
|
|
|
|
// Move to next symbol
|
|
x = (x + m_samplesPerSymbol) % m_rxBufLength;
|
|
|
|
// HDLC deframing
|
|
|
|
// NRZI decoding
|
|
int bit;
|
|
if (symbol != symbolPrev) {
|
|
bit = 0;
|
|
} else {
|
|
bit = 1;
|
|
}
|
|
symbolPrev = symbol;
|
|
|
|
// Store in shift reg
|
|
bits |= bit << bitCount;
|
|
bitCount++;
|
|
|
|
if (bit == 1)
|
|
{
|
|
onesCount++;
|
|
// Shouldn't ever get 7 1s in a row
|
|
if ((onesCount == 7) && gotSOP)
|
|
{
|
|
gotSOP = false;
|
|
byteCount = 0;
|
|
break;
|
|
}
|
|
}
|
|
else if (bit == 0)
|
|
{
|
|
if (onesCount == 5)
|
|
{
|
|
// Remove bit-stuffing (5 1s followed by a 0)
|
|
bitCount--;
|
|
}
|
|
else if (onesCount == 6)
|
|
{
|
|
// Start/end of packet
|
|
if (gotSOP && (bitCount == 8) && (bits == 0x7e) && (byteCount > 0))
|
|
{
|
|
// End of packet
|
|
// Check CRC is valid
|
|
m_crc.init();
|
|
m_crc.calculate(m_bytes, byteCount - 2);
|
|
uint16_t calcCrc = m_crc.get();
|
|
uint16_t rxCrc = m_bytes[byteCount-2] | (m_bytes[byteCount-1] << 8);
|
|
if (calcCrc == rxCrc)
|
|
{
|
|
scopeCRCValid = true;
|
|
QByteArray rxPacket((char *)m_bytes, byteCount - 2); // Don't include CRC
|
|
//qDebug() << "RX: " << rxPacket.toHex();
|
|
if (getMessageQueueToChannel())
|
|
{
|
|
// Calculate slot number based on time of start of transmission
|
|
// This is unlikely to be accurate in absolute terms, given we don't know latency from SDR or buffering within SDRangel
|
|
// But can be used to get an idea of congestion
|
|
QDateTime currentTime = QDateTime::currentDateTime();
|
|
if (m_settings.m_useFileTime)
|
|
{
|
|
QString hardwareId = m_aisDemod->getDeviceAPI()->getHardwareId();
|
|
|
|
if ((hardwareId == "FileInput") || (hardwareId == "SigMFFileInput"))
|
|
{
|
|
QString dateTimeStr;
|
|
int deviceIdx = m_aisDemod->getDeviceSetIndex();
|
|
|
|
if (ChannelWebAPIUtils::getDeviceReportValue(deviceIdx, "absoluteTime", dateTimeStr)) {
|
|
currentTime = QDateTime::fromString(dateTimeStr, Qt::ISODateWithMs);
|
|
}
|
|
}
|
|
}
|
|
|
|
int txTimeMs = (totalBitCount + 8 + 24 + 8) * (1000.0 / m_settings.m_baud); // Add ramp up, preamble and start-flag
|
|
QDateTime startDateTime = currentTime.addMSecs(-txTimeMs);
|
|
int ms = startDateTime.time().second() * 1000 + startDateTime.time().msec();
|
|
float slotTime = 60.0f * 1000.0f / 2250.0f; // 2250 slots per minute, 26.6ms per slot
|
|
int slot = ms / slotTime;
|
|
int totalSlots = std::ceil(txTimeMs / slotTime);
|
|
AISDemod::MsgMessage *msg = AISDemod::MsgMessage::create(rxPacket, currentTime, slot, totalSlots);
|
|
getMessageQueueToChannel()->push(msg);
|
|
}
|
|
|
|
// Skip over received packet, so we don't try to re-demodulate it
|
|
m_rxBufCnt -= sampleIdx;
|
|
}
|
|
else
|
|
{
|
|
//qDebug() << QString("CRC mismatch: %1 %2").arg(calcCrc, 4, 16, QLatin1Char('0')).arg(rxCrc, 4, 16, QLatin1Char('0'));
|
|
scopeCRCInvalid = true;
|
|
}
|
|
break;
|
|
}
|
|
else if (gotSOP)
|
|
{
|
|
// Repeated start flag without data or misalignment, something not right
|
|
break;
|
|
}
|
|
else
|
|
{
|
|
// Start of packet
|
|
gotSOP = true;
|
|
bits = 0;
|
|
bitCount = 0;
|
|
byteCount = 0;
|
|
totalBitCount = 0;
|
|
}
|
|
}
|
|
onesCount = 0;
|
|
}
|
|
|
|
if (gotSOP)
|
|
{
|
|
totalBitCount++;
|
|
if (bitCount == 8)
|
|
{
|
|
// Could also check count according to message ID as that varies
|
|
if (byteCount >= AISDEMOD_MAX_BYTES)
|
|
{
|
|
// Too many bytes
|
|
break;
|
|
}
|
|
else
|
|
{
|
|
// Got a complete byte
|
|
m_bytes[byteCount] = bits;
|
|
byteCount++;
|
|
}
|
|
bits = 0;
|
|
bitCount = 0;
|
|
}
|
|
}
|
|
|
|
// Abort demod if we haven't found start flag within a couple of bytes of presumed preamble
|
|
if (!gotSOP && (sampleIdx >= 16 * m_samplesPerSymbol)) {
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
// Select signals to feed to scope
|
|
sampleToScope(ci / SDR_RX_SCALEF, magsq, fmDemod, filt, m_rxBuf[m_rxBufIdx], corr / 100.0, thresholdMet, dcOffset, scopeCRCValid ? 1.0 : (scopeCRCInvalid ? -1.0 : 0));
|
|
|
|
// Send demod signal to Demod Analzyer feature
|
|
m_demodBuffer[m_demodBufferFill++] = fmDemod * std::numeric_limits<int16_t>::max();
|
|
|
|
if (m_demodBufferFill >= m_demodBuffer.size())
|
|
{
|
|
QList<ObjectPipe*> dataPipes;
|
|
MainCore::instance()->getDataPipes().getDataPipes(m_channel, "demod", dataPipes);
|
|
|
|
if (dataPipes.size() > 0)
|
|
{
|
|
QList<ObjectPipe*>::iterator it = dataPipes.begin();
|
|
|
|
for (; it != dataPipes.end(); ++it)
|
|
{
|
|
DataFifo *fifo = qobject_cast<DataFifo*>((*it)->m_element);
|
|
|
|
if (fifo) {
|
|
fifo->write((quint8*) &m_demodBuffer[0], m_demodBuffer.size() * sizeof(qint16), DataFifo::DataTypeI16);
|
|
}
|
|
}
|
|
}
|
|
|
|
m_demodBufferFill = 0;
|
|
}
|
|
}
|
|
|
|
void AISDemodSink::applyChannelSettings(int channelSampleRate, int channelFrequencyOffset, bool force)
|
|
{
|
|
qDebug() << "AISDemodSink::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) AISDemodSettings::AISDEMOD_CHANNEL_SAMPLE_RATE;
|
|
m_interpolatorDistanceRemain = m_interpolatorDistance;
|
|
}
|
|
|
|
m_channelSampleRate = channelSampleRate;
|
|
m_channelFrequencyOffset = channelFrequencyOffset;
|
|
m_samplesPerSymbol = AISDemodSettings::AISDEMOD_CHANNEL_SAMPLE_RATE / m_settings.m_baud;
|
|
qDebug() << "AISDemodSink::applyChannelSettings: m_samplesPerSymbol: " << m_samplesPerSymbol;
|
|
}
|
|
|
|
void AISDemodSink::applySettings(const AISDemodSettings& settings, bool force)
|
|
{
|
|
qDebug() << "AISDemodSink::applySettings:"
|
|
<< " 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) AISDemodSettings::AISDEMOD_CHANNEL_SAMPLE_RATE;
|
|
m_interpolatorDistanceRemain = m_interpolatorDistance;
|
|
}
|
|
if ((settings.m_fmDeviation != m_settings.m_fmDeviation) || force)
|
|
{
|
|
m_phaseDiscri.setFMScaling(AISDemodSettings::AISDEMOD_CHANNEL_SAMPLE_RATE / (2.0f * settings.m_fmDeviation));
|
|
}
|
|
|
|
if ((settings.m_baud != m_settings.m_baud) || force)
|
|
{
|
|
m_samplesPerSymbol = AISDemodSettings::AISDEMOD_CHANNEL_SAMPLE_RATE / settings.m_baud;
|
|
qDebug() << "AISDemodSink::applySettings: m_samplesPerSymbol: " << m_samplesPerSymbol << " baud " << settings.m_baud;
|
|
m_pulseShape.create(0.5, 3, m_samplesPerSymbol);
|
|
|
|
// Recieve buffer, long enough for one max length message
|
|
delete[] m_rxBuf;
|
|
m_rxBufLength = AISDEMOD_MAX_BYTES*8*m_samplesPerSymbol;
|
|
m_rxBuf = new Real[m_rxBufLength];
|
|
m_rxBufIdx = 0;
|
|
m_rxBufCnt = 0;
|
|
|
|
// Create 24-bit training sequence for correlation
|
|
delete[] m_train;
|
|
m_correlationLength = 24*m_samplesPerSymbol;
|
|
m_train = new Real[m_correlationLength]();
|
|
const int trainNRZ[24] = {1, 0, 0, 1, 1, 0, 0, 1, 1, 0, 0, 1, 1, 0, 0, 1, 1, 0, 0, 1, 1, 0, 0, 1};
|
|
|
|
// Pulse shape filter takes a few symbols before outputting expected shape
|
|
for (int j = 0; j < m_samplesPerSymbol; j++)
|
|
m_pulseShape.filter(-1.0f);
|
|
for (int j = 0; j < m_samplesPerSymbol; j++)
|
|
m_pulseShape.filter(1.0f);
|
|
for (int i = 0; i < 24; i++)
|
|
{
|
|
for (int j = 0; j < m_samplesPerSymbol; j++)
|
|
{
|
|
m_train[i*m_samplesPerSymbol+j] = m_pulseShape.filter(trainNRZ[i] * 2.0f - 1.0f);
|
|
}
|
|
}
|
|
}
|
|
|
|
m_settings = settings;
|
|
}
|