Fixed NFM strong signals handling

include-gpl/dsp/agc.h

@@ -87,19 +87,25 @@ public:
 	EvenSimplerAGC() :
 		m_u0(1.0),
 		m_R(1.0),
-		m_moving_average()
+		m_moving_average(),
+		m_historySize(0),
+		m_count(0)
 	{}
 
 	EvenSimplerAGC(int historySize, Real R) :
 		m_u0(1.0),
 		m_R(R),
-		m_moving_average(historySize, m_R)
+		m_moving_average(historySize, m_R),
+		m_historySize(historySize),
+		m_count(0)
 	{}
 
 	void resize(int historySize, Real R)
 	{
 		m_R = R;
 		m_moving_average.resize(historySize, R);
+		m_historySize = historySize;
+		m_count = 0;
 	}
 
 	Real getValue()
@@ -107,28 +113,49 @@ public:
 		return m_u0;
 	}
 
+	Real getDelayedValue()
+	{
+		if (m_count < m_historySize*m_mult)
+		{
+			return 0;
+		}
+		else
+		{
+			return m_u0;
+		}
+	}
+
 	void feed(Complex& ci)
 	{
 		ci *= m_u0;
-		Real magsq = ci.real()*ci.real() + ci.imag()*ci.imag();
+		Real mag = sqrt(ci.real()*ci.real() + ci.imag()*ci.imag());
-		m_moving_average.feed(magsq);
+		m_moving_average.feed(mag);
 	}
 
 	void openedSquelch()
 	{
+		if (m_count < m_historySize*m_mult)
+		{
+			m_count++;
+		}
+
 		m_u0 = m_R / m_moving_average.average();
 	}
 
 	void closedSquelch()
 	{
 		//m_moving_average.fill(m_R); // Valgrind optim
-		m_u0 = 1.0;
+		m_count = 0;
+		m_u0 = m_R / m_moving_average.average();
 	}
 
 private:
 	Real m_u0;
-	Real m_R;       // objective magsq
+	Real m_R;       // objective mag
 	MovingAverage<Real> m_moving_average; // Averaging engine. The stack length conditions the smoothness of AGC.
+	int m_historySize;
+	int m_count;
+	static const int m_mult = 4;
 };
 
 class AlphaAGC
@@ -140,7 +167,9 @@ public:
 		m_R(1.0),
 		m_alpha(0.1),
 		m_squelchOpen(true),
-		m_moving_average()
+		m_moving_average(),
+		m_historySize(0),
+		m_count(0)
 	{}
 
 	AlphaAGC(int historySize, Real R, Real alpha) :
@@ -148,7 +177,9 @@ public:
 		m_R(R),
 		m_alpha(alpha),
 		m_squelchOpen(true),
-		m_moving_average(historySize, m_R)
+		m_moving_average(historySize, m_R),
+		m_historySize(historySize),
+		m_count(0)
 	{}
 
 	void resize(int historySize, Real R, Real alpha)
@@ -157,6 +188,8 @@ public:
 		m_alpha = alpha;
 		m_squelchOpen = true;
 		m_moving_average.resize(historySize, R);
+		m_historySize = historySize;
+		m_count = 0;
 	}
 
 	Real getValue()
@@ -164,25 +197,42 @@ public:
 		return m_u0;
 	}
 
+	Real getDelayedValue()
+	{
+		if (m_count < m_historySize)
+		{
+			return 0;
+		}
+		else
+		{
+			return m_u0;
+		}
+	}
+
 	void feed(Complex& ci)
 	{
 		ci *= m_u0;
-		Real magsq = ci.real()*ci.real() + ci.imag()*ci.imag();
+		Real mag = sqrt(ci.real()*ci.real() + ci.imag()*ci.imag());
 
-		if (m_squelchOpen && (magsq < m_moving_average.average()))
+		if (m_squelchOpen && (mag < m_moving_average.average()))
 		{
-			m_moving_average.feed(m_moving_average.average() - m_alpha*(m_moving_average.average() - magsq));
+			m_moving_average.feed(m_moving_average.average() - m_alpha*(m_moving_average.average() - mag));
 		}
 		else
 		{
 			//m_squelchOpen = true;
-			m_moving_average.feed(magsq);
+			m_moving_average.feed(mag);
 		}
 
 	}
 
 	void openedSquelch()
 	{
+		if (m_count < m_historySize)
+		{
+			m_count++;
+		}
+
 		m_u0 = m_R / m_moving_average.average();
 		m_squelchOpen = true;
 	}
@@ -190,7 +240,9 @@ public:
 	void closedSquelch()
 	{
 		//m_moving_average.fill(m_R); // Valgrind optim
-		m_u0 = 1.0;
+		m_count = 0;
+		//m_u0 = 1.0;
+		m_u0 = m_R / m_moving_average.average();
 		m_squelchOpen = false;
 	}
 
@@ -200,6 +252,8 @@ private:
 	Real m_alpha;
 	bool m_squelchOpen;
 	MovingAverage<Real> m_moving_average; // Averaging engine. The stack length conditions the smoothness of AGC.
+	int m_historySize;
+	int m_count;
 };
 
 

plugins/channel/nfm/nfmdemod.cpp

@@ -55,9 +55,9 @@ NFMDemod::NFMDemod() :
 	m_audioBufferFill = 0;
 
 	m_movingAverage.resize(16, 0);
-	m_agcLevel = 0.003; // 0.003
+	m_agcLevel = 0.25; // 0.003
 	//m_AGC.resize(480, m_agcLevel, 0, 0.1*m_agcLevel);
-	m_AGC.resize(240, m_agcLevel*m_agcLevel, 0.3);
+	m_AGC.resize(600, m_agcLevel*m_agcLevel); //, 0.3);
 
 	m_ctcssDetector.setCoefficients(3000, 6000.0); // 0.5s / 2 Hz resolution
 	m_afSquelch.setCoefficients(24, 48000.0, 5, 1); // 4000 Hz span, 250us
@@ -165,7 +165,7 @@ void NFMDemod::feed(const SampleVector::const_iterator& begin, const SampleVecto
 				Real qp = ci.imag() - m_m2Sample.imag();
 				Real h1 = m_m1Sample.real() * qp;
 				Real h2 = m_m1Sample.imag() * ip;
-				Real demod = (h1 - h2) * 10000;
+				Real demod = (h1 - h2) * 30; // 10000
 
 				m_m2Sample = m_m1Sample;
 				m_m1Sample = ci;
@@ -218,7 +218,7 @@ void NFMDemod::feed(const SampleVector::const_iterator& begin, const SampleVecto
 					{
 						demod = m_bandpass.filter(demod);
 						demod *= m_running.m_volume;
-						sample = demod * ((1<<15)/301); // denominator = bandpass filter number of taps
+						sample = demod * ((1<<15)/301) * m_AGC.getDelayedValue(); // denominator = bandpass filter number of taps
 					}
 
 					m_AGC.openedSquelch();

plugins/channel/nfm/nfmdemod.h

@@ -163,7 +163,7 @@ private:
 	Complex m_m1Sample;
 	Complex m_m2Sample;
 	MovingAverage<Real> m_movingAverage;
-	AlphaAGC m_AGC;
+	EvenSimplerAGC m_AGC;
 	Real m_agcLevel; // AGC will aim to  this level
 	Real m_agcFloor; // AGC will not go below this level
 

sdrbase/dsp/channelizer.cpp

@@ -86,6 +86,8 @@ bool Channelizer::handleMessage(const Message& cmd)
 {
 	qDebug() << "Channelizer::handleMessage: " << cmd.getIdentifier();
 
+	// TODO: apply changes only if input sample rate or requested output sample rate change. Change of center frequency has no impact.
+
 	if (DSPSignalNotification::match(cmd))
 	{
 		DSPSignalNotification& notif = (DSPSignalNotification&) cmd;