From 52eb869b7c04e295ae81d9b674f37380a2763a47 Mon Sep 17 00:00:00 2001
From: f4exb <f4exb06@gmail.com>
Date: Wed, 26 Jul 2017 00:08:29 +0200
Subject: [PATCH] SSB demod: AGC: implemented threshold gate to mitigate
 transients

---
 plugins/channelrx/demodssb/ssbdemod.cpp    | 17 ++++++++++++++---
 plugins/channelrx/demodssb/ssbdemod.h      | 22 +++++++++++++++-------
 plugins/channelrx/demodssb/ssbdemodgui.cpp |  8 +++++---
 plugins/channelrx/demodssb/ssbdemodgui.ui  | 12 ++++++------
 4 files changed, 40 insertions(+), 19 deletions(-)

diff --git a/plugins/channelrx/demodssb/ssbdemod.cpp b/plugins/channelrx/demodssb/ssbdemod.cpp
index fc28113ad..7c3f62329 100644
--- a/plugins/channelrx/demodssb/ssbdemod.cpp
+++ b/plugins/channelrx/demodssb/ssbdemod.cpp
@@ -37,6 +37,7 @@ SSBDemod::SSBDemod(BasebandSampleSink* sampleSink) :
     m_agcActive(false),
     m_agcNbSamples(12000),
     m_agcPowerThreshold(1e-2),
+    m_agcThresholdGate(0),
     m_sampleSink(sampleSink),
     m_audioFifo(4, 24000),
     m_settingsMutex(QMutex::Recursive)
@@ -91,7 +92,8 @@ void SSBDemod::configure(MessageQueue* messageQueue,
 		bool audioMute,
 		bool agc,
         int agcTimeLog2,
-        int agcPowerThreshold)
+        int agcPowerThreshold,
+        int agcThresholdGate)
 {
 	Message* cmd = MsgConfigureSSBDemod::create(
 	        Bandwidth,
@@ -104,7 +106,8 @@ void SSBDemod::configure(MessageQueue* messageQueue,
 	        audioMute,
 	        agc,
 	        agcTimeLog2,
-	        agcPowerThreshold);
+	        agcPowerThreshold,
+	        agcThresholdGate);
 	messageQueue->push(cmd);
 }
 
@@ -313,6 +316,7 @@ bool SSBDemod::handleMessage(const Message& cmd)
 
 		int agcNbSamples = 48 * (1<<cfg.getAGCTimeLog2());
 		double agcPowerThreshold = CalcDb::powerFromdB(cfg.getAGCPowerThershold()) * (1<<30);
+		int agcThresholdGate = 48 * cfg.getAGCThersholdGate(); // ms
 
 		if (m_agcNbSamples != agcNbSamples)
 		{
@@ -326,6 +330,12 @@ bool SSBDemod::handleMessage(const Message& cmd)
 		    m_agcPowerThreshold = agcPowerThreshold;
 		}
 
+		if (m_agcThresholdGate != agcThresholdGate)
+		{
+		    m_agc.setGate(agcThresholdGate);
+		    m_agcThresholdGate = agcThresholdGate;
+		}
+
 		m_settingsMutex.unlock();
 
 		qDebug() << "SBDemod::handleMessage: MsgConfigureSSBDemod: m_Bandwidth: " << m_Bandwidth
@@ -338,7 +348,8 @@ bool SSBDemod::handleMessage(const Message& cmd)
 				<< " m_audioMute: " << m_audioMute
 				<< " m_agcActive: " << m_agcActive
 				<< " agcNbSamples: " << agcNbSamples
-				<< " agcPowerThreshold: " << agcPowerThreshold;
+				<< " agcPowerThreshold: " << agcPowerThreshold
+				<< " agcThresholdGate: " << agcThresholdGate;
 
 		return true;
 	}
diff --git a/plugins/channelrx/demodssb/ssbdemod.h b/plugins/channelrx/demodssb/ssbdemod.h
index 17914be4c..2edaea576 100644
--- a/plugins/channelrx/demodssb/ssbdemod.h
+++ b/plugins/channelrx/demodssb/ssbdemod.h
@@ -47,7 +47,8 @@ public:
 			bool audioMute,
 			bool agc,
 			int agcTimeLog2,
-			int agcPowerThreshold);
+			int agcPowerThreshold,
+			int agcThresholdGate);
 
 	virtual void feed(const SampleVector::const_iterator& begin, const SampleVector::const_iterator& end, bool positiveOnly);
 	virtual void start();
@@ -81,8 +82,9 @@ private:
 		bool getDSB() const { return m_dsb; }
 		bool getAudioMute() const { return m_audioMute; }
 		bool getAGC() const { return m_agc; }
-		int  getAGCTimeLog2() { return m_agcTimeLog2; }
-		int  getAGCPowerThershold() { return m_agcPowerThreshold; }
+		int  getAGCTimeLog2() const { return m_agcTimeLog2; }
+		int  getAGCPowerThershold() const { return m_agcPowerThreshold; }
+        int  getAGCThersholdGate() const { return m_agcThresholdGate; }
 
 		static MsgConfigureSSBDemod* create(Real Bandwidth,
 				Real LowCutoff,
@@ -94,7 +96,8 @@ private:
 				bool audioMute,
                 bool agc,
                 int  agcTimeLog2,
-                int  agcPowerThreshold)
+                int  agcPowerThreshold,
+                int  agcThresholdGate)
 		{
 			return new MsgConfigureSSBDemod(
 			        Bandwidth,
@@ -107,7 +110,8 @@ private:
 			        audioMute,
 			        agc,
 			        agcTimeLog2,
-			        agcPowerThreshold);
+			        agcPowerThreshold,
+			        agcThresholdGate);
 		}
 
 	private:
@@ -122,6 +126,7 @@ private:
 		bool m_agc;
 		int  m_agcTimeLog2;
 		int  m_agcPowerThreshold;
+		int  m_agcThresholdGate;
 
 		MsgConfigureSSBDemod(Real Bandwidth,
 				Real LowCutoff,
@@ -133,7 +138,8 @@ private:
 				bool audioMute,
 				bool agc,
 				int  agcTimeLog2,
-				int  agcPowerThreshold) :
+				int  agcPowerThreshold,
+				int  agcThresholdGate) :
 			Message(),
 			m_Bandwidth(Bandwidth),
 			m_LowCutoff(LowCutoff),
@@ -145,7 +151,8 @@ private:
 			m_audioMute(audioMute),
 			m_agc(agc),
 			m_agcTimeLog2(agcTimeLog2),
-			m_agcPowerThreshold(agcPowerThreshold)
+			m_agcPowerThreshold(agcPowerThreshold),
+			m_agcThresholdGate(agcThresholdGate)
 		{ }
 	};
 
@@ -177,6 +184,7 @@ private:
     bool m_agcActive;
     int m_agcNbSamples;         //!< number of audio (48 kHz) samples for AGC averaging
     double m_agcPowerThreshold; //!< AGC power threshold (linear)
+    int m_agcThresholdGate;     //!< Gate length in number of samples befor threshold triggers
 
 	NCOF m_nco;
 	Interpolator m_interpolator;
diff --git a/plugins/channelrx/demodssb/ssbdemodgui.cpp b/plugins/channelrx/demodssb/ssbdemodgui.cpp
index f47d5d440..95acabc26 100644
--- a/plugins/channelrx/demodssb/ssbdemodgui.cpp
+++ b/plugins/channelrx/demodssb/ssbdemodgui.cpp
@@ -82,6 +82,7 @@ QByteArray SSBDemodGUI::serialize() const
 	s.writeBool(11, ui->agc->isChecked());
 	s.writeS32(12, ui->agcTimeLog2->value());
 	s.writeS32(13, ui->agcPowerThreshold->value());
+    s.writeS32(14, ui->agcThresholdGate->value());
 	return s.final();
 }
 
@@ -138,7 +139,7 @@ bool SSBDemodGUI::deserialize(const QByteArray& data)
         ui->agcPowerThresholdText->setText(s);
         d.readS32(14, &tmp, 5);
         ui->agcThresholdGate->setValue(tmp);
-        s = QString::number(tmp*10, 'f', 0);
+        s = QString::number(tmp, 'f', 0);
         ui->agcThresholdGateText->setText(s);
 
 		blockApplySettings(false);
@@ -304,7 +305,7 @@ void SSBDemodGUI::on_agcPowerThreshold_valueChanged(int value)
 
 void SSBDemodGUI::on_agcThresholdGate_valueChanged(int value)
 {
-    QString s = QString::number(value * 10, 'f', 0);
+    QString s = QString::number(value, 'f', 0);
     ui->agcThresholdGateText->setText(s);
     applySettings();
 }
@@ -515,7 +516,8 @@ void SSBDemodGUI::applySettings()
 			ui->audioMute->isChecked(),
 			ui->agc->isChecked(),
 			ui->agcTimeLog2->value(),
-			ui->agcPowerThreshold->value());
+			ui->agcPowerThreshold->value(),
+			ui->agcThresholdGate->value());
 	}
 }
 
diff --git a/plugins/channelrx/demodssb/ssbdemodgui.ui b/plugins/channelrx/demodssb/ssbdemodgui.ui
index a4fb0ec03..e634ea148 100644
--- a/plugins/channelrx/demodssb/ssbdemodgui.ui
+++ b/plugins/channelrx/demodssb/ssbdemodgui.ui
@@ -6,7 +6,7 @@
    <rect>
     <x>0</x>
     <y>0</y>
-    <width>435</width>
+    <width>370</width>
     <height>160</height>
    </rect>
   </property>
@@ -36,7 +36,7 @@
     <rect>
      <x>0</x>
      <y>0</y>
-     <width>421</width>
+     <width>360</width>
      <height>151</height>
     </rect>
    </property>
@@ -568,13 +568,13 @@
          <string>Set threshiold gate (ms)</string>
         </property>
         <property name="maximum">
-         <number>50</number>
+         <number>20</number>
         </property>
         <property name="pageStep">
          <number>1</number>
         </property>
         <property name="value">
-         <number>5</number>
+         <number>4</number>
         </property>
        </widget>
       </item>
@@ -582,7 +582,7 @@
        <widget class="QLabel" name="agcThresholdGateText">
         <property name="minimumSize">
          <size>
-          <width>24</width>
+          <width>16</width>
           <height>0</height>
          </size>
         </property>
@@ -590,7 +590,7 @@
          <string>Threshiold gate (ms)</string>
         </property>
         <property name="text">
-         <string>000</string>
+         <string>00</string>
         </property>
         <property name="alignment">
          <set>Qt::AlignRight|Qt::AlignTrailing|Qt::AlignVCenter</set>