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NFM demod: channel power calculation and squelch corrections

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This commit is contained in:
f4exb 2016-12-05 03:46:42 +01:00
parent 9cadb3a44f
commit 317836ac92
3 changed files with 23 additions and 20 deletions
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32
plugins/channelrx/demodnfm/nfmdemod.cpp
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@ -35,7 +35,7 @@ NFMDemod::NFMDemod() :
m_ctcssIndex(0),
m_sampleCount(0),
m_squelchCount(0),
m_agcAttack(2400),
m_squelchGate(2400),
m_audioMute(false),
m_squelchOpen(false),
m_magsqSum(0.0f),
@ -66,7 +66,8 @@ NFMDemod::NFMDemod() :
m_audioBufferFill = 0;
m_agcLevel = 1.0;
m_AGC.resize(m_agcAttack, m_agcLevel);
m_AGC.resize(m_squelchGate, m_agcLevel);
m_movingAverage.resize(16, 0);
m_ctcssDetector.setCoefficients(3000, 6000.0); // 0.5s / 2 Hz resolution
m_afSquelch.setCoefficients(24, 600, 48000.0, 200, 0); // 4000 Hz span, 250us, 100ms attack
@ -149,16 +150,18 @@ void NFMDemod::feed(const SampleVector::const_iterator& begin, const SampleVecto
qint16 sample;
m_AGC.feed(ci);
Real magsq = m_AGC.getMagSq();
magsq /= (1<<30);
m_magsqSum += magsq;
if (magsq > m_magsqPeak)
{
m_magsqPeak = magsq;
}
double magsqRaw = m_AGC.getMagSq();
Real magsq = magsqRaw / (1<<30);
m_movingAverage.feed(magsq);
m_magsqSum += magsq;
m_magsqCount++;
if (magsq > m_magsqPeak)
{
m_magsqPeak = magsq;
}
m_magsqCount++;
Real demod = m_phaseDiscri.phaseDiscriminator2(ci);
@ -168,9 +171,9 @@ void NFMDemod::feed(const SampleVector::const_iterator& begin, const SampleVecto
// AF processing
if (m_AGC.getAverage()/(1<<30) > m_squelchLevel)
if (m_movingAverage.average() > m_squelchLevel)
{
if (m_squelchCount < m_agcAttack)
if (m_squelchCount < m_squelchGate)
{
m_squelchCount++;
}
@ -181,7 +184,7 @@ void NFMDemod::feed(const SampleVector::const_iterator& begin, const SampleVecto
}
//squelchOpen = (getMag() > m_squelchLevel);
m_squelchOpen = m_squelchCount == m_agcAttack; // wait for AGC to stabilize
m_squelchOpen = m_squelchCount == m_squelchGate; // wait for AGC to stabilize
/*
if (m_afSquelch.analyze(demod))
@ -374,8 +377,7 @@ void NFMDemod::apply()
if (m_config.m_squelchGate != m_running.m_squelchGate)
{
m_agcAttack = 480 * m_config.m_squelchGate; // gate is given in 10s of ms at 48000 Hz audio sample rate
m_AGC.resize(m_agcAttack, m_agcLevel);
m_squelchGate = 480 * m_config.m_squelchGate; // gate is given in 10s of ms at 48000 Hz audio sample rate
m_squelchCount = 0; // reset squelch open counter
}

7
plugins/channelrx/demodnfm/nfmdemod.h
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@ -68,7 +68,7 @@ public:
m_ctcssIndexSelected = selectedCtcssIndex;
}
Real getMag() { return m_AGC.getAverage() / (1<<15); }
Real getMag() { return m_movingAverage.average(); }
bool getSquelchOpen() const { return m_squelchOpen; }
void getMagSqLevels(Real& avg, Real& peak, int& nbSamples)
@ -192,10 +192,10 @@ private:
int m_ctcssIndexSelected;
int m_sampleCount;
int m_squelchCount;
int m_agcAttack;
int m_squelchGate;
bool m_audioMute;
double m_squelchLevel;
Real m_squelchLevel;
bool m_squelchOpen;
Real m_magsqSum;
Real m_magsqPeak;
@ -205,6 +205,7 @@ private:
//Complex m_m1Sample;
//Complex m_m2Sample;
MagAGC m_AGC;
MovingAverage<Real> m_movingAverage;
AFSquelch m_afSquelch;
Real m_agcLevel; // AGC will aim to this level
Real m_agcFloor; // AGC will not go below this level

4
sdrbase/dsp/agc.cpp
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@ -82,9 +82,9 @@ MagAGC::~MagAGC()
void MagAGC::feed(Complex& ci)
{
m_magsq = sqrt(ci.real()*ci.real() + ci.imag()*ci.imag());
m_magsq = ci.real()*ci.real() + ci.imag()*ci.imag();
m_moving_average.feed(m_magsq);
m_u0 = m_R / m_moving_average.average();
m_u0 = m_R / sqrt(m_moving_average.average());
ci *= m_u0;
}