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sdrangel/plugins/channeltx/modpacket/packetmodsource.cpp

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///////////////////////////////////////////////////////////////////////////////////
// Copyright (C) 2020-2021, 2023 Jon Beniston, M7RCE <jon@beniston.com> //
// Copyright (C) 2020-2022 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 <cctype>
#include <QDebug>
#include "dsp/basebandsamplesink.h"
#include "dsp/datafifo.h"
#include "packetmodsource.h"
#include "util/crc.h"
#include "util/messagequeue.h"
#include "maincore.h"
#include "channel/channelapi.h"
PacketModSource::PacketModSource() :
m_channelSampleRate(48000),
m_channelFrequencyOffset(0),
m_spectrumRate(0),
m_audioPhase(0.0f),
m_fmPhase(0.0),
m_preemphasisFilter(48000, FMPREEMPHASIS_TAU_US),
m_spectrumSink(nullptr),
m_magsq(0.0),
m_levelCalcCount(0),
m_peakLevel(0.0f),
m_levelSum(0.0f),
m_state(idle),
m_byteIdx(0),
m_bitIdx(0),
m_last5Bits(0),
m_bitCount(0),
m_scrambler(0x10800, 0x0)
{
m_lowpass.create(301, m_channelSampleRate, 22000.0 / 2.0);
qDebug() << "PacketModSource::PacketModSource creating BPF : " << m_channelSampleRate;
m_bandpass.create(301, m_channelSampleRate, 800.0, 2600.0);
m_pulseShape.create(0.5, 6, m_channelSampleRate/9600);
m_demodBuffer.resize(1<<12);
m_demodBufferFill = 0;
applySettings(m_settings, true);
applyChannelSettings(m_channelSampleRate, m_channelFrequencyOffset, true);
}
PacketModSource::~PacketModSource()
{
}
void PacketModSource::pull(SampleVector::iterator begin, unsigned int nbSamples)
{
std::for_each(
begin,
begin + nbSamples,
[this](Sample& s) {
pullOne(s);
}
);
}
void PacketModSource::pullOne(Sample& sample)
{
if (m_settings.m_channelMute)
{
sample.m_real = 0.0f;
sample.m_imag = 0.0f;
return;
}
// Calculate next sample
modulateSample();
// Shift to carrier frequency
Complex ci = m_modSample;
ci *= m_carrierNco.nextIQ();
// Calculate power
double magsq = ci.real() * ci.real() + ci.imag() * ci.imag();
m_movingAverage(magsq);
m_magsq = m_movingAverage.asDouble();
// Convert from float to fixed point
sample.m_real = (FixReal) (ci.real() * SDR_TX_SCALEF);
sample.m_imag = (FixReal) (ci.imag() * SDR_TX_SCALEF);
}
void PacketModSource::sampleToSpectrum(Real sample)
{
if (m_spectrumSink)
{
Complex out;
Complex in;
in.real(sample);
in.imag(0.0f);
if (m_interpolator.decimate(&m_interpolatorDistanceRemain, in, &out))
{
sample = std::real(out);
m_sampleBuffer.push_back(Sample(sample * 0.891235351562f * SDR_TX_SCALEF, 0.0f));
m_spectrumSink->feed(m_sampleBuffer.begin(), m_sampleBuffer.end(), true);
m_sampleBuffer.clear();
m_interpolatorDistanceRemain += m_interpolatorDistance;
}
}
}
void PacketModSource::modulateSample()
{
Real audioMod;
Real linearRampGain;
if ((m_state == idle) || (m_state == wait))
{
audioMod = 0.0f;
m_modSample.real(audioMod);
m_modSample.imag(0);
calculateLevel(audioMod);
sampleToSpectrum(audioMod);
if (m_state == wait)
{
m_waitCounter--;
if (m_waitCounter == 0)
initTX();
}
}
else
{
if (m_sampleIdx == 0)
{
if (bitsValid())
{
// NRZI encoding - encode 0 as change of freq, 1 no change
if (getBit() == 0)
m_nrziBit = m_nrziBit == 1 ? 0 : 1;
// Scramble to ensure lots of transitions
if (m_settings.m_scramble)
m_scrambledBit = m_scrambler.scramble(m_nrziBit);
else
m_scrambledBit = m_nrziBit;
}
// Should we start ramping down power?
if ((m_bitCount < m_settings.m_rampDownBits) || ((m_bitCount == 0) && !m_settings.m_rampDownBits))
{
m_state = ramp_down;
if (m_settings.m_rampDownBits > 0)
m_powRamp = -m_settings.m_rampRange/(m_settings.m_rampDownBits * (Real)m_samplesPerSymbol);
}
}
m_sampleIdx++;
if (m_sampleIdx >= m_samplesPerSymbol)
m_sampleIdx = 0;
if (!m_settings.m_bbNoise)
{
if (m_settings.m_modulation == PacketModSettings::AFSK)
{
// Bell 202 AFSK
audioMod = sin(m_audioPhase);
if ((m_state == tx) || m_settings.m_modulateWhileRamping)
m_audioPhase += (M_PI * 2.0f * (m_scrambledBit ? m_settings.m_markFrequency : m_settings.m_spaceFrequency)) / (m_channelSampleRate);
if (m_audioPhase > M_PI)
m_audioPhase -= (2.0f * M_PI);
}
else
{
// FSK
if (m_settings.m_pulseShaping)
{
if ((m_sampleIdx == 1) && (m_state != ramp_down))
audioMod = m_pulseShape.filter(m_scrambledBit ? 1.0f : -1.0f);
else
audioMod = m_pulseShape.filter(0.0f);
}
else
audioMod = m_scrambledBit ? 1.0f : -1.0f;
}
}
else
audioMod = (Real)rand()/((Real)RAND_MAX)-0.5; // Noise to test filter frequency response
// Baseband bandpass filter
if (m_settings.m_bpf)
audioMod = m_bandpass.filter(audioMod);
// Preemphasis filter
if (m_settings.m_preEmphasis)
audioMod = m_preemphasisFilter.filter(audioMod);
if (m_audioFile.is_open())
m_audioFile << audioMod << "\n";
// Display baseband audio in spectrum analyser
sampleToSpectrum(audioMod);
// FM
m_fmPhase += m_phaseSensitivity * audioMod;
// Keep phase in range -pi,pi
if (m_fmPhase > M_PI)
m_fmPhase -= 2.0f * M_PI;
else if (m_fmPhase < -M_PI)
m_fmPhase += 2.0f * M_PI;
linearRampGain = powf(10.0f, m_pow/20.0f);
if (!m_settings.m_rfNoise)
{
m_modSample.real(m_linearGain * linearRampGain * cos(m_fmPhase));
m_modSample.imag(m_linearGain * linearRampGain * sin(m_fmPhase));
}
else
{
// Noise to test filter frequency response
m_modSample.real(m_linearGain * ((Real)rand()/((Real)RAND_MAX)-0.5f));
m_modSample.imag(m_linearGain * ((Real)rand()/((Real)RAND_MAX)-0.5f));
}
// Apply low pass filter to limit RF BW
m_modSample = m_lowpass.filter(m_modSample);
// Ramp up/down power at start/end of packet
if ((m_state == ramp_up) || (m_state == ramp_down))
{
m_pow += m_powRamp;
if ((m_state == ramp_up) && (m_pow >= 0.0f))
{
// Finished ramp up, transmit at full gain
m_state = tx;
m_pow = 0.0f;
}
else if ((m_state == ramp_down) && ( (m_settings.m_rampRange == 0)
|| (m_settings.m_rampDownBits == 0)
|| (m_pow <= -(Real)m_settings.m_rampRange)
))
{
m_state = idle;
// Do we need to retransmit the packet?
if (m_settings.m_repeat)
{
if (m_packetRepeatCount > 0)
m_packetRepeatCount--;
if ((m_packetRepeatCount == PacketModSettings::infinitePackets) || (m_packetRepeatCount > 0))
{
if (m_settings.m_repeatDelay > 0.0f)
{
// Wait before retransmitting
m_state = wait;
m_waitCounter = m_settings.m_repeatDelay * m_channelSampleRate;
}
else
{
// Retransmit immediately
initTX();
}
}
}
}
}
Real s = std::real(m_modSample);
calculateLevel(s);
}
m_demodBuffer[m_demodBufferFill] = audioMod * std::numeric_limits<int16_t>::max();
++m_demodBufferFill;
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 PacketModSource::calculateLevel(Real& sample)
{
if (m_levelCalcCount < m_levelNbSamples)
{
m_peakLevel = std::max(std::fabs(m_peakLevel), sample);
m_levelSum += sample * sample;
m_levelCalcCount++;
}
else
{
m_rmsLevel = sqrt(m_levelSum / m_levelNbSamples);
m_peakLevelOut = m_peakLevel;
m_peakLevel = 0.0f;
m_levelSum = 0.0f;
m_levelCalcCount = 0;
}
}
void PacketModSource::applySettings(const PacketModSettings& settings, bool force)
{
// Only recreate filters if settings have changed
if ((settings.m_lpfTaps != m_settings.m_lpfTaps) || (settings.m_rfBandwidth != m_settings.m_rfBandwidth) || force)
{
qDebug() << "PacketModSource::applySettings: Creating new lpf with taps " << settings.m_lpfTaps << " rfBW " << settings.m_rfBandwidth;
m_lowpass.create(settings.m_lpfTaps, m_channelSampleRate, settings.m_rfBandwidth / 2.0);
}
if ((settings.m_preEmphasisTau != m_settings.m_preEmphasisTau) || (settings.m_preEmphasisHighFreq != m_settings.m_preEmphasisHighFreq) || force)
{
qDebug() << "PacketModSource::applySettings: Creating new preemphasis filter with tau " << settings.m_preEmphasisTau << " highFreq " << settings.m_preEmphasisHighFreq << " sampleRate " << m_channelSampleRate;
m_preemphasisFilter.configure(m_channelSampleRate, settings.m_preEmphasisTau, settings.m_preEmphasisHighFreq);
}
if ((settings.m_bpfLowCutoff != m_settings.m_bpfLowCutoff) || (settings.m_bpfHighCutoff != m_settings.m_bpfHighCutoff)
|| (settings.m_bpfTaps != m_settings.m_bpfTaps)|| force)
{
qDebug() << "PacketModSource::applySettings: Recreating bandpass filter: "
<< " m_bpfTaps: " << settings.m_bpfTaps
<< " m_channelSampleRate:" << m_channelSampleRate
<< " m_bpfLowCutoff: " << settings.m_bpfLowCutoff
<< " m_bpfHighCutoff: " << settings.m_bpfHighCutoff;
m_bandpass.create(settings.m_bpfTaps, m_channelSampleRate, settings.m_bpfLowCutoff, settings.m_bpfHighCutoff);
}
if ((settings.m_beta != m_settings.m_beta) || (settings.m_symbolSpan != m_settings.m_symbolSpan) || (settings.m_baud != m_settings.m_baud) || force)
{
qDebug() << "PacketModSource::applySettings: Recreating pulse shaping filter: "
<< " beta: " << settings.m_beta
<< " symbolSpan: " << settings.m_symbolSpan
<< " channelSampleRate:" << m_channelSampleRate
<< " baud:" << settings.m_baud;
m_pulseShape.create(settings.m_beta, settings.m_symbolSpan, m_channelSampleRate/settings.m_baud);
}
if ((settings.m_polynomial != m_settings.m_polynomial) || force)
m_scrambler.setPolynomial(settings.m_polynomial);
if ((settings.m_spectrumRate != m_settings.m_spectrumRate) || force)
{
m_interpolatorDistanceRemain = 0;
m_interpolatorConsumed = false;
m_interpolatorDistance = (Real) m_channelSampleRate / (Real) settings.m_spectrumRate;
m_interpolator.create(48, settings.m_spectrumRate, settings.m_spectrumRate / 2.2, 3.0);
}
m_settings = settings;
// Precalculate FM sensensity and linear gain to save doing it in the loop
m_phaseSensitivity = 2.0f * M_PI * m_settings.m_fmDeviation / (double)m_channelSampleRate;
m_linearGain = powf(10.0f, m_settings.m_gain/20.0f);
}
void PacketModSource::applyChannelSettings(int channelSampleRate, int channelFrequencyOffset, bool force)
{
qDebug() << "PacketModSource::applyChannelSettings:"
<< " channelSampleRate: " << channelSampleRate
<< " channelFrequencyOffset: " << channelFrequencyOffset
<< " rfBandwidth: " << m_settings.m_rfBandwidth
<< " spectrumRate: " << m_settings.m_spectrumRate;
if ((channelFrequencyOffset != m_channelFrequencyOffset)
|| (channelSampleRate != m_channelSampleRate) || force)
{
m_carrierNco.setFreq(channelFrequencyOffset, channelSampleRate);
}
if ((m_channelSampleRate != channelSampleRate) || force)
{
qDebug() << "PacketModSource::applyChannelSettings: Recreating filters";
m_lowpass.create(m_settings.m_lpfTaps, channelSampleRate, m_settings.m_rfBandwidth / 2.0);
qDebug() << "PacketModSource::applyChannelSettings: Recreating bandpass filter: "
<< " bpfTaps: " << m_settings.m_bpfTaps
<< " channelSampleRate:" << channelSampleRate
<< " bpfLowCutoff: " << m_settings.m_bpfLowCutoff
<< " bpfHighCutoff: " << m_settings.m_bpfHighCutoff;
m_bandpass.create(m_settings.m_bpfTaps, channelSampleRate, m_settings.m_bpfLowCutoff, m_settings.m_bpfHighCutoff);
m_preemphasisFilter.configure(channelSampleRate, m_settings.m_preEmphasisTau);
qDebug() << "PacketModSource::applyChannelSettings: Recreating pulse shaping filter: "
<< " beta: " << m_settings.m_beta
<< " symbolSpan: " << m_settings.m_symbolSpan
<< " channelSampleRate:" << m_channelSampleRate
<< " baud:" << m_settings.m_baud;
m_pulseShape.create(m_settings.m_beta, m_settings.m_symbolSpan, channelSampleRate/m_settings.m_baud);
}
if ((m_channelSampleRate != channelSampleRate) || (m_spectrumRate != m_settings.m_spectrumRate) || force)
{
m_interpolatorDistanceRemain = 0;
m_interpolatorConsumed = false;
m_interpolatorDistance = (Real) channelSampleRate / (Real) m_settings.m_spectrumRate;
m_interpolator.create(48, m_settings.m_spectrumRate, m_settings.m_spectrumRate / 2.2, 3.0);
}
m_channelSampleRate = channelSampleRate;
m_channelFrequencyOffset = channelFrequencyOffset;
m_spectrumRate = m_settings.m_spectrumRate;
m_samplesPerSymbol = m_channelSampleRate / m_settings.m_baud;
qDebug() << "m_samplesPerSymbol: " << m_samplesPerSymbol << " (" << m_channelSampleRate << "/" << m_settings.m_baud << ")";
// Precalculate FM sensensity to save doing it in the loop
m_phaseSensitivity = 2.0f * M_PI * m_settings.m_fmDeviation / (double)m_channelSampleRate;
QList<ObjectPipe*> pipes;
MainCore::instance()->getMessagePipes().getMessagePipes(m_channel, "reportdemod", pipes);
if (pipes.size() > 0)
{
for (const auto& pipe : pipes)
{
MessageQueue* messageQueue = qobject_cast<MessageQueue*>(pipe->m_element);
MainCore::MsgChannelDemodReport *msg = MainCore::MsgChannelDemodReport::create(m_channel, m_channelSampleRate);
messageQueue->push(msg);
}
}
}
static bool ax25_ssid(QByteArray& b, int i, int len, uint8_t& ssid)
{
if (b[i] == '-')
{
if (len > i + 1)
{
ssid = b[i+1] - '0';
if ((len > i + 2) && isdigit(b[i+2])) {
ssid = (ssid*10) + (b[i+2] - '0');
}
if (ssid >= 16)
{
qDebug() << "ax25_address: SSID greater than 15 not supported";
ssid = ssid & 0xf;
return false;
}
else
{
return true;
}
}
else
{
qDebug() << "ax25_address: SSID number missing";
return false;
}
}
else
return false;
}
static uint8_t *ax25_address(uint8_t *p, QString address, uint8_t crrl)
{
int len;
int i;
QByteArray b;
uint8_t ssid = 0;
bool hyphenSeen = false;
len = address.length();
b = address.toUtf8();
ssid = 0;
for (i = 0; i < 6; i++)
{
if ((i < len) && !hyphenSeen)
{
if (b[i] == '-')
{
ax25_ssid(b, i, len, ssid);
hyphenSeen = true;
*p++ = ' ' << 1;
}
else
{
*p++ = b[i] << 1;
}
}
else
{
*p++ = ' ' << 1;
}
}
if (b[i] == '-')
{
ax25_ssid(b, i, len, ssid);
}
*p++ = crrl | (ssid << 1);
return p;
}
bool PacketModSource::bitsValid()
{
return m_bitCount > 0;
}
int PacketModSource::getBit()
{
int bit;
if (m_bitCount > 0)
{
bit = (m_bits[m_byteIdx] >> m_bitIdx) & 1;
m_bitIdx++;
m_bitCount--;
if (m_bitIdx == 8)
{
m_byteIdx++;
m_bitIdx = 0;
}
}
else
bit = 0;
return bit;
}
void PacketModSource::addBit(int bit)
{
// Transmit LSB first
m_bits[m_byteIdx] |= bit << m_bitIdx;
m_bitIdx++;
m_bitCount++;
m_bitCountTotal++;
if (m_bitIdx == 8)
{
m_byteIdx++;
m_bits[m_byteIdx] = 0;
m_bitIdx = 0;
}
m_last5Bits = ((m_last5Bits << 1) | bit) & 0x1f;
}
void PacketModSource::initTX()
{
m_byteIdx = 0;
m_bitIdx = 0;
m_bitCount = m_bitCountTotal; // Reset to allow retransmission
m_nrziBit = 0;
if (m_settings.m_rampUpBits == 0)
{
m_state = tx;
m_pow = 0.0f;
}
else
{
m_state = ramp_up;
m_pow = -(Real)m_settings.m_rampRange;
m_powRamp = m_settings.m_rampRange/(m_settings.m_rampUpBits * (Real)m_samplesPerSymbol);
}
m_scrambler.init();
}
void PacketModSource::addTXPacket(QString callsign, QString to, QString via, QString data)
{
uint8_t packet[AX25_MAX_BYTES];
uint8_t *crc_start;
uint8_t *packet_end;
uint8_t *p;
crc16x25 crc;
uint16_t crcValue;
int len;
int packet_length;
// Create AX.25 packet
p = packet;
// Flag
for (int i = 0; i < std::min(m_settings.m_ax25PreFlags, AX25_MAX_FLAGS); i++)
*p++ = AX25_FLAG;
crc_start = p;
// Dest
p = ax25_address(p, to, 0xe0);
// From
p = ax25_address(p, callsign, 0x60);
// Via
p = ax25_address(p, via, 0x61);
// Control
*p++ = m_settings.m_ax25Control;
// PID
*p++ = m_settings.m_ax25PID;
// Data
len = data.length();
memcpy(p, data.toUtf8(), len);
p += len;
// CRC (do not include flags)
crc.calculate(crc_start, p-crc_start);
crcValue = crc.get();
*p++ = crcValue & 0xff;
*p++ = (crcValue >> 8);
packet_end = p;
// Flag
for (int i = 0; i < std::min(m_settings.m_ax25PostFlags, AX25_MAX_FLAGS); i++)
*p++ = AX25_FLAG;
packet_length = p-&packet[0];
encodePacket(packet, packet_length, crc_start, packet_end);
}
void PacketModSource::addTXPacket(QByteArray data)
{
uint8_t packet[AX25_MAX_BYTES];
uint8_t *crc_start;
uint8_t *packet_end;
uint8_t *p;
crc16x25 crc;
uint16_t crcValue;
int packet_length;
// Create AX.25 packet
p = packet;
// Flag
for (int i = 0; i < std::min(m_settings.m_ax25PreFlags, AX25_MAX_FLAGS); i++)
*p++ = AX25_FLAG;
crc_start = p;
// Copy packet payload
for (int i = 0; i < data.size(); i++)
*p++ = data[i];
// CRC (do not include flags)
crc.calculate(crc_start, p-crc_start);
crcValue = crc.get();
*p++ = crcValue & 0xff;
*p++ = (crcValue >> 8);
packet_end = p;
// Flag
for (int i = 0; i < std::min(m_settings.m_ax25PostFlags, AX25_MAX_FLAGS); i++)
*p++ = AX25_FLAG;
packet_length = p-&packet[0];
encodePacket(packet, packet_length, crc_start, packet_end);
}
void PacketModSource::encodePacket(uint8_t *packet, int packet_length, uint8_t *crc_start, uint8_t *packet_end)
{
// HDLC bit stuffing
m_byteIdx = 0;
m_bitIdx = 0;
m_last5Bits = 0;
m_bitCount = 0;
m_bitCountTotal = 0;
for (int i = 0; i < packet_length; i++)
{
for (int j = 0; j < 8; j++)
{
int tx_bit = (packet[i] >> j) & 1;
// Stuff 0 if last 5 bits are 1s, unless transmitting flag
// Except for special case of when last 5 bits of CRC are 1s
if ( ( (packet[i] != AX25_FLAG)
|| ( (&packet[i] >= crc_start)
&& ( (&packet[i] < packet_end)
|| ((&packet[i] == packet_end) && (j == 0))
)
)
)
&& (m_last5Bits == 0x1f)
)
addBit(0);
addBit(tx_bit);
}
}
m_samplesPerSymbol = m_channelSampleRate / m_settings.m_baud;
m_packetRepeatCount = m_settings.m_repeatCount;
initTX();
// Only reset phases at start of new packet TX, not in initTX(), so that
// there isn't a discontinuity in phase when repeatedly transmitting a
// single tone
m_sampleIdx = 0;
m_audioPhase = 0.0f;
m_fmPhase = 0.0;
if (m_settings.m_writeToFile)
m_audioFile.open("packetmod.csv", std::ofstream::out);
else if (m_audioFile.is_open())
m_audioFile.close();
}
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