RTLSDR: impemented RTLSDR AGC control

plugins/samplesource/rtlsdr/readme.md

@@ -76,6 +76,8 @@ The I/Q stream from the RTLSDR ADC is doensampled by a power of two before being
 
 Use this checkbox to activate the special RTLSDR direct sampling. This can be used to tune to HF frequencies.
 
-<h3>9: RF gain</h2>
+<h3>9: RF gain and AGC</h2>
 
-This is the RF gain setting in dB. The values are defined in the RTLSDR device and generally are: 0.0, 0.9, 1.4, 2.7, 3.7, 7.7, 8.7, 12.5, 14.4, 15.7, 16.6, 19.7, 20.7, 22.9, 25.4, 28.0, 29.7, 32.8, 33.8, 36.4, 37.2, 38.6, 40.2, 42.1, 43.4, 43.9, 44.5, 48.0, 49.6
+The slider sets RF gain in dB. The values are defined in the RTLSDR device and generally are: 0.0, 0.9, 1.4, 2.7, 3.7, 7.7, 8.7, 12.5, 14.4, 15.7, 16.6, 19.7, 20.7, 22.9, 25.4, 28.0, 29.7, 32.8, 33.8, 36.4, 37.2, 38.6, 40.2, 42.1, 43.4, 43.9, 44.5, 48.0, 49.6
+
+The AGC checkbox can be used to switch on or off the RTL2838 AGC. This is independent of the gain setting as this AGC acts after the gain block. 

plugins/samplesource/rtlsdr/rtlsdrgui.cpp

@@ -407,6 +407,12 @@ void RTLSDRGui::on_checkBox_stateChanged(int state)
 	sendSettings();
 }
 
+void RTLSDRGui::on_agc_stateChanged(int state)
+{
+    m_settings.m_agc = (state == Qt::Checked);
+    sendSettings();
+}
+
 void RTLSDRGui::on_sampleRate_changed(quint64 value)
 {
     m_settings.m_devSampleRate = value;

plugins/samplesource/rtlsdr/rtlsdrgui.h

@@ -80,6 +80,7 @@ private slots:
 	void on_gain_valueChanged(int value);
 	void on_sampleRate_currentIndexChanged(int index);
 	void on_checkBox_stateChanged(int state);
+    void on_agc_stateChanged(int state);
 	void on_startStop_toggled(bool checked);
     void on_record_toggled(bool checked);
 	void updateHardware();

plugins/samplesource/rtlsdr/rtlsdrgui.ui

@@ -483,6 +483,16 @@
      <property name="spacing">
       <number>3</number>
      </property>
+     <item row="0" column="3">
+      <widget class="QCheckBox" name="agc">
+       <property name="toolTip">
+        <string>Toggles RTLSDR AGC</string>
+       </property>
+       <property name="text">
+        <string>AGC</string>
+       </property>
+      </widget>
+     </item>
      <item row="0" column="0">
       <widget class="QLabel" name="gainLabel">
        <property name="sizePolicy">

plugins/samplesource/rtlsdr/rtlsdrinput.cpp

@@ -256,6 +256,18 @@ bool RTLSDRInput::applySettings(const RTLSDRSettings& settings, bool force)
 {
     bool forwardChange = false;
 
+    if ((m_settings.m_agc != settings.m_agc) || force)
+    {
+        if (rtlsdr_set_agc_mode(m_dev, settings.m_agc ? 1 : 0) < 0)
+        {
+            qCritical("could not set AGC mode %s", settings.m_agc ? "on" : "off");
+        }
+        else
+        {
+            m_settings.m_agc = settings.m_agc;
+        }
+    }
+
     if ((m_settings.m_gain != settings.m_gain) || force)
     {
         m_settings.m_gain = settings.m_gain;

plugins/samplesource/rtlsdr/rtlsdrplugin.cpp

@@ -11,7 +11,7 @@
 
 const PluginDescriptor RTLSDRPlugin::m_pluginDescriptor = {
 	QString("RTL-SDR Input"),
-	QString("3.5.0"),
+	QString("3.5.2"),
 	QString("(c) Edouard Griffiths, F4EXB"),
 	QString("https://github.com/f4exb/sdrangel"),
 	true,

plugins/samplesource/rtlsdr/rtlsdrsettings.cpp

@@ -34,6 +34,7 @@ void RTLSDRSettings::resetToDefaults()
 	m_fcPos = FC_POS_CENTER;
 	m_dcBlock = false;
 	m_iqImbalance = false;
+	m_agc = false;
 }
 
 QByteArray RTLSDRSettings::serialize() const
@@ -48,6 +49,7 @@ QByteArray RTLSDRSettings::serialize() const
 	s.writeS32(7, (int) m_fcPos);
     s.writeS32(8, m_devSampleRate);
     s.writeBool(9, m_lowSampleRate);
+    s.writeBool(10, m_agc);
 
 	return s.final();
 }
@@ -75,6 +77,7 @@ bool RTLSDRSettings::deserialize(const QByteArray& data)
 		m_fcPos = (fcPos_t) intval;
         d.readS32(8, &m_devSampleRate, 1024*1000);
         d.readBool(9, &m_lowSampleRate, false);
+        d.readBool(10, &m_agc, false);
 
 		return true;
 	}

plugins/samplesource/rtlsdr/rtlsdrsettings.h

@@ -33,6 +33,7 @@ struct RTLSDRSettings {
 	fcPos_t m_fcPos;
 	bool m_dcBlock;
 	bool m_iqImbalance;
+	bool m_agc;
 
 	RTLSDRSettings();
 	void resetToDefaults();