js8call/Modulator.cpp

#include "Modulator.hpp"
#include <limits>
#include <qmath.h>
#include <QDateTime>
#include <QDebug>
#include "mainwindow.h"
#include "soundout.h"
#include "commons.h"

#include "DriftingDateTime.h"

#include "moc_Modulator.cpp"

extern float gran();		// Noise generator (for tests only)

#define RAMP_INCREMENT 64  // MUST be an integral factor of 2^16

#if defined (WSJT_SOFT_KEYING)
# define SOFT_KEYING WSJT_SOFT_KEYING
#else
# define SOFT_KEYING 1
#endif

double constexpr Modulator::m_twoPi;

namespace
{
  unsigned
  delayMS(qint32 const trPeriod)
  {
    switch (trPeriod)
    {
      case JS8A_TX_SECONDS: { return JS8A_START_DELAY_MS; }
      case JS8B_TX_SECONDS: { return JS8B_START_DELAY_MS; }
      case JS8C_TX_SECONDS: { return JS8C_START_DELAY_MS; }
      case JS8E_TX_SECONDS: { return JS8E_START_DELAY_MS; }
      case JS8I_TX_SECONDS: { return JS8I_START_DELAY_MS; }
      default:              { return 0;                   }
    }
  }
}

//    float wpm=20.0;
//    unsigned m_nspd=1.2*48000.0/wpm;
//    m_nspd=3072;                           //18.75 WPM

Modulator::Modulator (unsigned frameRate, unsigned periodLengthInSeconds,
                      QObject * parent)
  : AudioDevice {parent}
  , m_quickClose {false}
  , m_phi {0.0}
  , m_toneSpacing {0.0}
  , m_fSpread {0.0}
  , m_frameRate {frameRate}
  , m_period {periodLengthInSeconds}
  , m_state {Idle}
  , m_tuning {false}
  , m_j0 {-1}
  , m_toneFrequency0 {1500.0}
{
}

void Modulator::start (unsigned symbolsLength, double framesPerSymbol,
                       double frequency, double toneSpacing,
                       SoundOutput * stream, Channel channel,
                       bool synchronize, bool fastMode, double dBSNR, int TRperiod)
{
  // qDebug () << "mode:" << mode << "symbolsLength:" << symbolsLength << "framesPerSymbol:" << framesPerSymbol << "frequency:" << frequency << "toneSpacing:" << toneSpacing << "channel:" << channel << "synchronize:" << synchronize << "fastMode:" << fastMode << "dBSNR:" << dBSNR << "TRperiod:" << TRperiod;
  Q_ASSERT (stream);
// Time according to this computer which becomes our base time
  qint64   const ms0  = DriftingDateTime::currentMSecsSinceEpoch() % 86400000;
  unsigned const mstr = ms0 % int(1000.0*m_period); // ms into the nominal Tx start time

  if(m_state != Idle) stop();
  m_quickClose = false;
  m_symbolsLength = symbolsLength;
  m_isym0 = std::numeric_limits<unsigned>::max (); // big number
  m_frequency0 = 0.;
  m_phi = 0.;
  m_addNoise = dBSNR < 0.;
  m_nsps = framesPerSymbol;
  m_frequency = frequency;
  m_amp = std::numeric_limits<qint16>::max ();
  m_toneSpacing = toneSpacing;
  m_bFastMode=fastMode;
  m_TRperiod=TRperiod;

  unsigned const delay_ms = delayMS(m_TRperiod);

  // noise generator parameters
  if (m_addNoise) {
    m_snr = qPow (10.0, 0.05 * (dBSNR - 6.0));
    m_fac = 3000.0;
    if (m_snr > 1.0) m_fac = 3000.0 / m_snr;
  }

  m_silentFrames = 0;
  m_ic=0;
  if (!m_tuning && !m_bFastMode)
    {
      // calculate number of silent frames to send, so that audio will
      // start at the nominal time "delay_ms" into the Tx sequence.
      if (synchronize)
        {
          if(delay_ms > mstr) m_silentFrames = (delay_ms - mstr) * m_frameRate / 1000;
        }
 
      // adjust for late starts
      if(!m_silentFrames && mstr >= delay_ms)
        {
          m_ic = (mstr - delay_ms) * m_frameRate / 1000;
        }
    }

  initialize (QIODevice::ReadOnly, channel);
  Q_EMIT stateChanged ((m_state = (synchronize && m_silentFrames) ?
                        Synchronizing : Active));

  // qDebug() << "delay_ms:" << delay_ms << "mstr:" << mstr << "m_silentFrames:" << m_silentFrames << "m_ic:" << m_ic << "m_state:" << m_state;

  m_stream = stream;
  if (m_stream)
    {
      m_stream->restart (this);
    }
  else
    {
      qDebug () << "Modulator::start: no audio output stream assigned";
    }
}

void Modulator::tune (bool newState)
{
  m_tuning = newState;
  if (!m_tuning) stop (true);
}

void Modulator::stop (bool quick)
{
  m_quickClose = quick;
  close ();
}

void Modulator::close ()
{
  if (m_stream)
    {
      if (m_quickClose)
        {
          m_stream->reset ();
        }
      else
        {
          m_stream->stop ();
        }
    }
  if (m_state != Idle)
    {
      Q_EMIT stateChanged ((m_state = Idle));
    }
  AudioDevice::close ();
}

qint64 Modulator::readData (char * data, qint64 maxSize)
{
  double toneFrequency=1500.0;
  if(m_nsps==6) {
    toneFrequency=1000.0;
    m_frequency=1000.0;
    m_frequency0=1000.0;
  }
  if(maxSize==0) return 0;
  Q_ASSERT (!(maxSize % qint64 (bytesPerFrame ()))); // no torn frames
  Q_ASSERT (isOpen ());

  qint64 numFrames (maxSize / bytesPerFrame ());
  qint16 * samples (reinterpret_cast<qint16 *> (data));
  qint16 * end (samples + numFrames * (bytesPerFrame () / sizeof (qint16)));
  qint64 framesGenerated (0);

  switch (m_state)
    {
    case Synchronizing:
      {
        if (m_silentFrames)	{  // send silence up to end of start delay
          framesGenerated = qMin (m_silentFrames, numFrames);
          do
            {
              samples = load (0, samples); // silence
            } while (--m_silentFrames && samples != end);
          if (!m_silentFrames)
            {
              Q_EMIT stateChanged ((m_state = Active));
            }
        }
      }
      // fall through

    case Active:
      {

        double const baud (12000.0 / m_nsps);
        // fade out parameters (no fade out for tuning)
        unsigned int i0,i1;
        if(m_tuning) {
          i1 = i0 = (m_bFastMode ? 999999 : 9999) * m_nsps;
        } else {
          i0=(m_symbolsLength - 0.017) * 4.0 * m_nsps;
          i1= m_symbolsLength * 4.0 * m_nsps;
        }
        if(m_bFastMode and !m_tuning) {
          i1=m_TRperiod*48000 - 24000;
          i0=i1-816;
        }

        qint16       sample;
        unsigned int isym;

        while (samples != end && m_ic <= i1) {
          isym=0;
          if(!m_tuning and m_TRperiod!=3) isym=m_ic / (4.0 * m_nsps);   //Actual fsample=48000
          if(m_bFastMode) isym=isym%m_symbolsLength;
          if (isym != m_isym0 || m_frequency != m_frequency0) {
            if(itone[0]>=100) {
              m_toneFrequency0=itone[0];
            } else {
              if(m_toneSpacing==0.0) {
                m_toneFrequency0=m_frequency + itone[isym]*baud;
              } else {
                m_toneFrequency0=m_frequency + itone[isym]*m_toneSpacing;
              }
            }
            m_dphi = m_twoPi * m_toneFrequency0 / m_frameRate;
            m_isym0 = isym;
            m_frequency0 = m_frequency;         //???
          }

          int j=m_ic/480;
          if(m_fSpread>0.0 and j!=m_j0) {
            float x1=QRandomGenerator::global ()->generateDouble ();
            float x2=QRandomGenerator::global ()->generateDouble ();
            toneFrequency = m_toneFrequency0 + 0.5*m_fSpread*(x1+x2-1.0);
            m_dphi = m_twoPi * toneFrequency / m_frameRate;
            m_j0=j;
          }

          m_phi += m_dphi;
          if (m_phi > m_twoPi) m_phi -= m_twoPi;
          if (m_ic > i0) m_amp = 0.98 * m_amp;
          if (m_ic > i1) m_amp = 0.0;

          sample=qRound(m_amp*qSin(m_phi));

          samples = load(postProcessSample(sample), samples);
          ++framesGenerated;
          ++m_ic;
        }

        if (m_amp == 0.0) { // TODO G4WJS: compare double with zero might not be wise
          Q_EMIT stateChanged ((m_state = Idle));
          return framesGenerated * bytesPerFrame ();
          m_phi = 0.0;
        }

        m_frequency0 = m_frequency;
        // done for this chunk - continue on next call

//        qDebug() << "Mod B" << m_ic << i1 << 0.001*(QDateTime::currentMSecsSinceEpoch() % (1000*m_TRperiod));

        while (samples != end)  // pad block with silence
          {
            samples = load (0, samples);
            ++framesGenerated;
          }
        return framesGenerated * bytesPerFrame ();
      }
      // fall through

    case Idle:
      break;
    }

  Q_ASSERT (Idle == m_state);
  return 0;
}

qint16 Modulator::postProcessSample (qint16 sample) const
{
  if (m_addNoise) {  // Test frame, we'll add noise
    qint32 s = m_fac * (gran () + sample * m_snr / 32768.0);
    if (s > std::numeric_limits<qint16>::max ()) {
      s = std::numeric_limits<qint16>::max ();
    }
    if (s < std::numeric_limits<qint16>::min ()) {
      s = std::numeric_limits<qint16>::min ();
    }
    sample = s;
  }
  return sample;
}