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NFM demod: new discriminator

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This commit is contained in:
f4exb 2017-01-30 23:28:06 +01:00
parent 2f515d9379
commit 0861f71ff3
3 changed files with 44 additions and 5 deletions
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10
plugins/channelrx/demodnfm/nfmdemod.cpp
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@ -150,9 +150,13 @@ void NFMDemod::feed(const SampleVector::const_iterator& begin, const SampleVecto
qint16 sample; qint16 sample;
m_AGC.feed(ci); //m_AGC.feed(ci);
//double magsqRaw = m_AGC.getMagSq();
long double magsqRaw; // = ci.real()*ci.real() + c.imag()*c.imag();
Real demod = m_phaseDiscri.phaseDiscriminator3(ci, magsqRaw);
double magsqRaw = m_AGC.getMagSq();
Real magsq = magsqRaw / (1<<30); Real magsq = magsqRaw / (1<<30);
m_movingAverage.feed(magsq); m_movingAverage.feed(magsq);
m_magsqSum += magsq; m_magsqSum += magsq;
@ -164,8 +168,6 @@ void NFMDemod::feed(const SampleVector::const_iterator& begin, const SampleVecto
m_magsqCount++; m_magsqCount++;
Real demod = m_phaseDiscri.phaseDiscriminator2(ci);
//m_m2Sample = m_m1Sample; //m_m2Sample = m_m1Sample;
//m_m1Sample = ci; //m_m1Sample = ci;
m_sampleCount++; m_sampleCount++;

2
plugins/channelrx/demodnfm/nfmplugin.cpp
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@ -7,7 +7,7 @@
const PluginDescriptor NFMPlugin::m_pluginDescriptor = { const PluginDescriptor NFMPlugin::m_pluginDescriptor = {
QString("NFM Demodulator"), QString("NFM Demodulator"),
QString("3.1.1"), QString("3.2.0"),
QString("(c) Edouard Griffiths, F4EXB"), QString("(c) Edouard Griffiths, F4EXB"),
QString("https://github.com/f4exb/sdrangel"), QString("https://github.com/f4exb/sdrangel"),
true, true,

37
sdrbase/dsp/phasediscri.h
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@ -70,10 +70,47 @@ public:
return (h1 - h2) * m_fmScaling; return (h1 - h2) * m_fmScaling;
} }
/**
* Second alternative
*/
Real phaseDiscriminator3(const Complex& sample, long double& magsq)
{
Real fltI = sample.real();
Real fltQ = sample.imag();
double fltNorm;
Real fltNormI;
Real fltNormQ;
Real fltVal;
magsq = fltI*fltI + fltQ*fltQ;
fltNorm = std::sqrt(magsq);
fltNormI= fltI/fltNorm;
fltNormQ= fltQ/fltNorm;
fltVal = m_fltPreviousI*(fltNormQ - m_fltPreviousQ2);
fltVal -= m_fltPreviousQ*(fltNormI - m_fltPreviousI2);
fltVal += 2.0f;
fltVal /= 2.0f; // normally it is /4
m_fltPreviousQ2 = m_fltPreviousQ;
m_fltPreviousI2 = m_fltPreviousI;
m_fltPreviousQ = fltNormQ;
m_fltPreviousI = fltNormI;
return fltVal * m_fmScaling;
}
private: private:
Complex m_m1Sample; Complex m_m1Sample;
Complex m_m2Sample; Complex m_m2Sample;
Real m_fmScaling; Real m_fmScaling;
Real m_fltPreviousI;
Real m_fltPreviousQ;
Real m_fltPreviousI2;
Real m_fltPreviousQ2;
}; };
#endif /* INCLUDE_DSP_PHASEDISCRI_H_ */ #endif /* INCLUDE_DSP_PHASEDISCRI_H_ */