Added simple AGC for AM demod

Readme.md

@@ -84,6 +84,8 @@ To Do
 =====
 
   - Add the possibility to change the brightness and/or color of the grid. Sometimes it is barely visible yet useful
+  - Fix and possibly enhance (stereo, RDS?) WFM. Maybe into two plugins one for plain WFM and the other for Broadcast FM
+  - Make the the SSB filter frequency bounds tunable so that it can be used for CW. Change marker overlay accordingly.
   - Possibility to completely undock the receiver in a separate window. Useful when there are many receivers
   - Larger decimation capability for narrowband and very narrowband work (32, 64, ...)
   - Even more demods ... 

include-gpl/dsp/agc.h

@@ -0,0 +1,71 @@
+/*
+ * kissagc.h
+ *
+ *  Created on: May 12, 2015
+ *      Author: f4exb
+ */
+
+#ifndef INCLUDE_GPL_DSP_AGC_H_
+#define INCLUDE_GPL_DSP_AGC_H_
+
+#include "movingaverage.h"
+
+class SimpleAGC
+{
+public:
+
+	SimpleAGC() :
+		m_squelch(false),
+		m_fill(0),
+		m_cutoff(0),
+		m_moving_average()
+	{}
+
+	SimpleAGC(int historySize, Real initial, Real cutoff) :
+		m_squelch(false),
+		m_fill(initial),
+		m_cutoff(cutoff),
+		m_moving_average(historySize, initial)
+	{}
+
+	void resize(int historySize, Real initial, Real cutoff)
+	{
+		m_fill = initial;
+		m_cutoff = cutoff;
+		m_moving_average.resize(historySize, initial);
+	}
+
+	Real getValue()
+	{
+		return m_moving_average.average();
+	}
+
+	void feed(Real value)
+	{
+		if (value > m_cutoff)
+		{
+			m_moving_average.feed(value);
+		}
+
+		m_squelch = true;
+	}
+
+	void close()
+	{
+		if (m_squelch)
+		{
+			m_moving_average.fill(m_fill);
+			m_squelch = false;
+		}
+	}
+
+private:
+	bool m_squelch;
+	Real m_fill;
+	Real m_cutoff;
+	MovingAverage m_moving_average;
+};
+
+
+
+#endif /* INCLUDE_GPL_DSP_AGC_H_ */

include-gpl/dsp/movingaverage.h

@@ -39,6 +39,13 @@ public:
 			m_ptr = 0;
 	}
 
+	void fill(Real value)
+	{
+		for(size_t i = 0; i < m_history.size(); i++)
+			m_history[i] = value;
+		m_sum = m_history.size() * value;
+	}
+
 	Real average() const
 	{
 		return m_sum / (Real)m_history.size();

plugins/channel/am/amdemod.cpp

@@ -23,6 +23,8 @@
 #include "dsp/dspcommands.h"
 #include "dsp/pidcontroller.h"
 
+#include <iostream>
+
 MESSAGE_CLASS_DEFINITION(AMDemod::MsgConfigureAMDemod, Message)
 
 AMDemod::AMDemod(AudioFifo* audioFifo, SampleSink* sampleSink) :
@@ -43,6 +45,7 @@ AMDemod::AMDemod(AudioFifo* audioFifo, SampleSink* sampleSink) :
 	m_audioBufferFill = 0;
 
 	m_movingAverage.resize(16, 0);
+	m_volumeAGC.resize(4096, 0.003, 0);
 }
 
 AMDemod::~AMDemod()
@@ -55,6 +58,7 @@ void AMDemod::configure(MessageQueue* messageQueue, Real rfBandwidth, Real afBan
 	cmd->submit(messageQueue, this);
 }
 
+/*
 float arctan2(Real y, Real x)
 {
 	Real coeff_1 = M_PI / 4;
@@ -84,6 +88,7 @@ Real angleDist(Real a, Real b)
 
 	return dist;
 }
+*/
 
 void AMDemod::feed(SampleVector::const_iterator begin, SampleVector::const_iterator end, bool firstOfBurst)
 {
@@ -138,10 +143,14 @@ void AMDemod::feed(SampleVector::const_iterator begin, SampleVector::const_itera
 					else if(demod > 1)
 						demod = 1;
 
+					m_volumeAGC.feed(demod);
+
+					demod *= (0.003 / m_volumeAGC.getValue());
 					demod *= m_running.m_volume;
-					sample = demod * 32700;
+					sample = demod * 32700 * 16;
 
 				} else {
+					m_volumeAGC.close();
 					sample = 0;
 				}
 

plugins/channel/am/amdemod.h

@@ -23,6 +23,7 @@
 #include "dsp/interpolator.h"
 #include "dsp/lowpass.h"
 #include "dsp/movingaverage.h"
+#include "dsp/agc.h"
 #include "audio/audiofifo.h"
 #include "util/message.h"
 
@@ -117,6 +118,7 @@ private:
 	Real m_lastArgument;
 	Complex m_lastSample;
 	MovingAverage m_movingAverage;
+	SimpleAGC m_volumeAGC;
 
 	AudioVector m_audioBuffer;
 	uint m_audioBufferFill;

sdrbase/gui/glspectrumgui.ui

@@ -6,7 +6,7 @@
    <rect>
     <x>0</x>
     <y>0</y>
-    <width>215</width>
+    <width>234</width>
     <height>94</height>
    </rect>
   </property>
@@ -14,7 +14,16 @@
    <string>Oscilloscope</string>
   </property>
   <layout class="QGridLayout" name="gridLayout" columnstretch="1,1,1,1">
-   <property name="margin">
+   <property name="leftMargin">
+    <number>2</number>
+   </property>
+   <property name="topMargin">
+    <number>2</number>
+   </property>
+   <property name="rightMargin">
+    <number>2</number>
+   </property>
+   <property name="bottomMargin">
     <number>2</number>
    </property>
    <property name="spacing">
@@ -258,19 +267,6 @@
      <property name="spacing">
       <number>3</number>
      </property>
-     <item>
-      <spacer name="horizontalSpacer">
-       <property name="orientation">
-        <enum>Qt::Horizontal</enum>
-       </property>
-       <property name="sizeHint" stdset="0">
-        <size>
-         <width>0</width>
-         <height>0</height>
-        </size>
-       </property>
-      </spacer>
-     </item>
      <item>
       <widget class="ButtonSwitch" name="waterfall">
        <property name="sizePolicy">
@@ -446,6 +442,31 @@
        </property>
       </widget>
      </item>
+     <item>
+      <widget class="QDial" name="gridIntensity">
+       <property name="maximumSize">
+        <size>
+         <width>24</width>
+         <height>24</height>
+        </size>
+       </property>
+       <property name="cursor">
+        <cursorShape>ArrowCursor</cursorShape>
+       </property>
+       <property name="toolTip">
+        <string>Grid intensity</string>
+       </property>
+       <property name="maximum">
+        <number>255</number>
+       </property>
+       <property name="pageStep">
+        <number>16</number>
+       </property>
+       <property name="value">
+        <number>64</number>
+       </property>
+      </widget>
+     </item>
     </layout>
    </item>
   </layout>