P25 - Automatic Gain Control for P25 decoder

src/controller/channel/Channel.java

@@ -59,7 +59,7 @@ import controller.system.System;
 import decode.config.AuxDecodeConfiguration;
 import decode.config.DecodeConfigFactory;
 import decode.config.DecodeConfiguration;
-import dsp.afc.AutomaticFrequencyControl;
+import dsp.frequency.AutomaticFrequencyControl;
 import eventlog.config.EventLogConfiguration;
 
 @XmlSeeAlso( { Configuration.class } )

src/controller/channel/ProcessingChain.java

@@ -62,7 +62,7 @@ import controller.state.ChannelState;
 import controller.state.ChannelState.State;
 import decode.Decoder;
 import decode.DecoderFactory;
-import dsp.afc.AutomaticFrequencyControl;
+import dsp.frequency.AutomaticFrequencyControl;
 import eventlog.EventLogType;
 import eventlog.EventLogger;
 

src/decode/DecoderType.java

@@ -68,7 +68,7 @@ public enum DecoderType
     					   DecoderType.LTR_STANDARD,
     					   DecoderType.MPT1327,
     					   DecoderType.NBFM,
-//    					   DecoderType.P25_PHASE1,
+    					   DecoderType.P25_PHASE1,
     					   DecoderType.PASSPORT );
     }
 

src/decode/am/AMDecoder.java

@@ -4,14 +4,14 @@ import sample.real.RealSampleListener;
 import source.Source.SampleType;
 import decode.Decoder;
 import decode.DecoderType;
-import dsp.agc.ComplexAutomaticGainControl;
-import dsp.agc.RealAutomaticGainControl;
 import dsp.am.AMDemodulator;
 import dsp.filter.ComplexFIRFilter;
 import dsp.filter.DCRemovalFilter2;
 import dsp.filter.FilterFactory;
 import dsp.filter.FloatFIRFilter;
 import dsp.filter.Window.WindowType;
+import dsp.gain.ComplexAutomaticGainControl;
+import dsp.gain.RealAutomaticGainControl;
 
 public class AMDecoder extends Decoder
 {

src/decode/p25/P25Decoder.java

@@ -35,13 +35,13 @@ import source.tuner.FrequencyChangeListener;
 import alias.AliasList;
 import decode.Decoder;
 import decode.DecoderType;
-import dsp.agc.RealAutomaticGainControl;
 import dsp.filter.ComplexFIRFilter;
 import dsp.filter.FilterFactory;
 import dsp.filter.Window.WindowType;
 import dsp.fsk.C4FMSlicer;
 import dsp.fsk.C4FMSymbolFilter;
 import dsp.fsk.P25MessageFramer;
+import dsp.gain.DirectGainControl;
 import dsp.nbfm.FMDiscriminator;
 
 public class P25Decoder extends Decoder 
@@ -60,8 +60,9 @@ public class P25Decoder extends Decoder
 			FilterFactory.getLowPass( 48000, 5000, 31, WindowType.HAMMING ), 1.0 );
 
 	private FMDiscriminator mDemodulator = new FMDiscriminator( 1 );
-	private RealAutomaticGainControl mAGC = new RealAutomaticGainControl();
-	private C4FMSymbolFilter mSymbolFilter = new C4FMSymbolFilter();
+	private DirectGainControl mGainControl = 
+						new DirectGainControl( 15.0f, 0.1f, 25.0f, 0.3f );
+	private C4FMSymbolFilter mSymbolFilter;
 	private C4FMSlicer mSlicer = new C4FMSlicer();
 	private P25MessageFramer mNormalFramer;
 	private P25MessageFramer mInvertedFramer;
@@ -74,6 +75,8 @@ public class P25Decoder extends Decoder
 		super( sampleType );
 		
 		mAliasList = aliasList;
+		
+		mSymbolFilter = new C4FMSymbolFilter( mGainControl );
 
 		/**
 		 * Only setup a demod chain if we're receiving complex samples.  If
@@ -94,8 +97,8 @@ public class P25Decoder extends Decoder
 			mDemodulator.setListener( getRealReceiver() );
 		}
 
-		addRealSampleListener( mAGC );
-		mAGC.setListener( mSymbolFilter );
+		addRealSampleListener( mGainControl );
+		mGainControl.setListener( mSymbolFilter );
 		
 		mSymbolFilter.setListener( mSlicer );
 		
@@ -147,13 +150,13 @@ public class P25Decoder extends Decoder
 		{
 			case INSTRUMENT_INPUT_TO_AGC:
 				FloatTap inputAGC = (FloatTap)tap;
-				removeRealListener( mAGC );
+				removeRealListener( mGainControl );
 				addRealSampleListener( inputAGC );
-				inputAGC.setListener( mAGC );
+				inputAGC.setListener( mGainControl );
 				break;
 			case INSTRUMENT_AGC_TO_SYMBOL_FILTER:
 				FloatTap agcSymbol = (FloatTap)tap;
-				mAGC.setListener( agcSymbol );
+				mGainControl.setListener( agcSymbol );
 				agcSymbol.setListener( mSymbolFilter );
 				break;
 			case INSTRUMENT_SYMBOL_FILTER_TO_SLICER:
@@ -178,10 +181,10 @@ public class P25Decoder extends Decoder
 			case INSTRUMENT_INPUT_TO_AGC:
 				FloatTap inputAGC = (FloatTap)tap;
 				removeRealListener( inputAGC );
-				addRealSampleListener( mAGC );
+				addRealSampleListener( mGainControl );
 				break;
 			case INSTRUMENT_AGC_TO_SYMBOL_FILTER:
-				mAGC.setListener( mSymbolFilter );
+				mGainControl.setListener( mSymbolFilter );
 				break;
 			case INSTRUMENT_SYMBOL_FILTER_TO_SLICER:
 				mSymbolFilter.setListener( mSlicer );

src/dsp/filter/Gain.java

@@ -1,45 +0,0 @@
-/*******************************************************************************
- *     SDR Trunk 
- *     Copyright (C) 2014 Dennis Sheirer
- * 
- *     This program is free software: you can redistribute it and/or modify
- *     it under the terms of the GNU General Public License as published by
- *     the Free Software Foundation, either version 3 of the License, or
- *     (at your option) any later version.
- * 
- *     This program is distributed in the hope that it will be useful,
- *     but WITHOUT ANY WARRANTY; without even the implied warranty of
- *     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- *     GNU General Public License for more details.
- * 
- *     You should have received a copy of the GNU General Public License
- *     along with this program.  If not, see <http://www.gnu.org/licenses/>
- ******************************************************************************/
-package dsp.filter;
-
-import sample.Listener;
-
-public class Gain implements Listener<Float>
-{
-	private double mGain;
-	private Listener<Float> mListener;
-	
-	public Gain( double gain )
-	{
-		mGain = gain;
-	}
-
-	@Override
-    public void receive( Float sample )
-    {
-		if( mListener != null )
-		{
-			mListener.receive( (float)( sample * mGain ) );
-		}
-    }
-	
-    public void setListener( Listener<Float> listener )
-    {
-		mListener = listener;
-    }
-}

src/dsp/frequency/AutomaticFrequencyControl.java

@@ -1,4 +1,4 @@
-package dsp.afc;
+package dsp.frequency;
 
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;

src/dsp/fsk/C4FMDecoder.java

@@ -1,85 +0,0 @@
-package dsp.fsk;
-
-import instrument.Instrumentable;
-import instrument.tap.Tap;
-import instrument.tap.stream.FloatTap;
-
-import java.util.ArrayList;
-import java.util.List;
-
-import sample.real.RealSampleListener;
-
-public class C4FMDecoder implements RealSampleListener, Instrumentable
-{
-	private static final String TAP_C4FM_INPUT = "C4FM Decoder Input";
-	private static final String TAP_SYMBOL_FILTER_OUTPUT = "C4FM Symbol Filter Output";
-
-	private ArrayList<Tap> mTaps;
-	private FloatTap mInputTap;
-	private FloatTap mSymbolFilterOutputTap;
-	
-	private C4FMSymbolFilter mSymbolFilter = new C4FMSymbolFilter();
-	
-	private RealSampleListener mInput;
-	
-	public C4FMDecoder()
-	{
-		mInput = mSymbolFilter;
-	}
-
-	@Override
-    public void receive( float sample )
-    {
-		mInput.receive( sample );
-    }
-
-	@Override
-    public List<Tap> getTaps()
-    {
-		if( mTaps == null )
-		{
-			mTaps = new ArrayList<Tap>();
-
-			FloatTap floatTap = new FloatTap( TAP_C4FM_INPUT, 0, 1.0f );
-			mTaps.add( floatTap );
-
-			FloatTap symbolTap = new FloatTap( TAP_SYMBOL_FILTER_OUTPUT, 10, 0.1f );
-			mTaps.add(  symbolTap );
-		}
-		
-	    return mTaps;
-    }
-
-	@Override
-    public void addTap( Tap tap )
-    {
-		switch( tap.getName() )
-		{
-			case TAP_C4FM_INPUT:
-				mInputTap = (FloatTap)tap; 
-				mInput = mInputTap;
-				mInputTap.setListener( mSymbolFilter );
-				break;
-			case TAP_SYMBOL_FILTER_OUTPUT:
-				mSymbolFilterOutputTap = (FloatTap)tap;
-				mSymbolFilter.setListener( mSymbolFilterOutputTap );
-				break;
-		}
-    }
-
-	@Override
-    public void removeTap( Tap tap )
-    {
-		switch( tap.getName() )
-		{
-			case TAP_C4FM_INPUT:
-				mInput = mSymbolFilter;
-				mInputTap = null;
-				break;
-			case TAP_SYMBOL_FILTER_OUTPUT:
-				mSymbolFilter.removeListener( mSymbolFilterOutputTap );
-				mSymbolFilterOutputTap = null;
-				break;
-		}
-    }
-}

src/dsp/fsk/C4FMSymbolFilter.java

@@ -17,6 +17,7 @@ import source.tuner.FrequencyChangeBroadcaster;
 import source.tuner.FrequencyChangeEvent;
 import source.tuner.FrequencyChangeEvent.Attribute;
 import source.tuner.FrequencyChangeListener;
+import dsp.gain.GainController;
 
 public class C4FMSymbolFilter implements FrequencyChangeBroadcaster,
 										 RealSampleListener, 
@@ -201,10 +202,11 @@ public class C4FMSymbolFilter implements FrequencyChangeBroadcaster,
 	
 	private RealSampleListener mListener;
 	
+	public static final long MAX_FREQUENCY_CORRECTION = 7000;
 	private FrequencyChangeListener mFrequencyChangeListener;
 	private long mFrequencyCorrection;
 
-	private float mGain = 15.4f;
+	private GainController mGainController;
 	
 	/**
 	 * C4FM Symbol Filter
@@ -219,13 +221,9 @@ public class C4FMSymbolFilter implements FrequencyChangeBroadcaster,
 	 * setting for this filter is 15.4 and that yields a symbol spread that
 	 * is centered on 2.0, ranging 1.92 to 2.08.
 	 */
-	public C4FMSymbolFilter( float gain )
-	{
-		mGain = gain;
-	}
-	
-	public C4FMSymbolFilter()
+	public C4FMSymbolFilter( GainController gainController )
 	{
+		mGainController = gainController;
 	}
 	
 	public long getFrequencyCorrection()
@@ -238,7 +236,8 @@ public class C4FMSymbolFilter implements FrequencyChangeBroadcaster,
     {
 		mSymbolClock += mSymbolTime;
 		
-		mHistory[ mHistoryLast++ ] = sample * mGain;
+		mHistory[ mHistoryLast++ ] = sample;
+		
 		mHistoryLast %= NUMBER_FILTER_TAPS;
 		
 		if( mSymbolClock > 1.0f )
@@ -317,9 +316,19 @@ public class C4FMSymbolFilter implements FrequencyChangeBroadcaster,
 				mSymbolClock -= symbolError * K_SYMBOL_TIMING;
 			}
 			
-			mSymbolSpread = Math.max( mSymbolSpread, SYMBOL_SPREAD_MIN );
-			mSymbolSpread = Math.min( mSymbolSpread, SYMBOL_SPREAD_MAX );
-			
+			if( mSymbolSpread < SYMBOL_SPREAD_MIN )
+			{
+				mGainController.increase();
+				
+				mSymbolSpread = SYMBOL_SPREAD_MIN;
+			}
+			else if( mSymbolSpread > SYMBOL_SPREAD_MAX )
+			{
+				mGainController.decrease();
+
+				mSymbolSpread = SYMBOL_SPREAD_MAX;
+			}
+
 			mCoarseFrequencyCorrection += ( ( mFineFrequencyCorrection - 
 					mCoarseFrequencyCorrection ) * K_COARSE_FREQUENCY );
 			
@@ -333,14 +342,21 @@ public class C4FMSymbolFilter implements FrequencyChangeBroadcaster,
 					mFrequencyCorrection += ( 
 						500 * ( mCoarseFrequencyCorrection > 0 ? 1 : -1 ) );
 					
+					if( mFrequencyCorrection > MAX_FREQUENCY_CORRECTION )
+					{
+						mFrequencyCorrection = MAX_FREQUENCY_CORRECTION;
+					}
+					else if( -mFrequencyCorrection > MAX_FREQUENCY_CORRECTION )
+					{
+						mFrequencyCorrection = -MAX_FREQUENCY_CORRECTION;
+					}
+					
 					mFrequencyChangeListener.frequencyChanged( 
 						new FrequencyChangeEvent( Attribute.FREQUENCY_ERROR, 
 								mFrequencyCorrection ) );
 
 					/* reset internal frequency error tracker */
 					mCoarseFrequencyCorrection = 0;
-
-					mLog.debug( "Frequency Corrected: " + mFrequencyCorrection );
 				}
 			}
 			

src/dsp/gain/ComplexAutomaticGainControl.java

@@ -1,4 +1,4 @@
-package dsp.agc;
+package dsp.gain;
 
 import java.util.concurrent.atomic.AtomicBoolean;
 

src/dsp/gain/DirectGainControl.java

@@ -0,0 +1,95 @@
+/*******************************************************************************
+ *     SDR Trunk 
+ *     Copyright (C) 2014 Dennis Sheirer
+ * 
+ *     This program is free software: you can redistribute it and/or modify
+ *     it under the terms of the GNU General Public License as published by
+ *     the Free Software Foundation, either version 3 of the License, or
+ *     (at your option) any later version.
+ * 
+ *     This program is distributed in the hope that it will be useful,
+ *     but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *     GNU General Public License for more details.
+ * 
+ *     You should have received a copy of the GNU General Public License
+ *     along with this program.  If not, see <http://www.gnu.org/licenses/>
+ ******************************************************************************/
+package dsp.gain;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import sample.real.RealSampleListener;
+
+public class DirectGainControl implements GainController, RealSampleListener
+{
+	private final static Logger mLog = 
+			LoggerFactory.getLogger( DirectGainControl.class );
+
+	private float mGain;
+	private float mMinimum;
+	private float mMaximum;
+	private float mIncrement;
+	
+	private RealSampleListener mListener;
+
+	/**
+	 * Gain Control.
+	 * 
+	 * Note: does not perform null checking on output listener in order to 
+	 * streamline sample processing.
+	 * 
+	 * @param gain - initial value
+	 * @param minimum - minimum value greater than 0
+	 * @param maximum - maximum permitted value
+	 * @param increment - amount gain is adjusted when increase() or decrease()
+	 * is invoked
+	 */
+	public DirectGainControl( float gain, float minimum, float maximum, float increment )
+	{
+		assert( minimum > 0 );
+		
+		mGain = gain;
+		mMinimum = minimum;
+		mMaximum = maximum;
+		mIncrement = increment;
+	}
+
+	@Override
+    public void receive( float sample )
+    {
+		mListener.receive( (float)( sample * mGain ) );
+    }
+
+	@Override
+	public void increase()
+	{
+		mGain += mIncrement;
+		
+		if( mGain > mMaximum )
+		{
+			mGain = mMaximum;
+		}
+		
+		mLog.debug( "Gain Increased: " + mGain );
+	}
+	
+	@Override
+	public void decrease()
+	{
+		mGain -= mIncrement;
+		
+		if( mGain < mMinimum )
+		{
+			mGain = mMinimum;
+		}
+		
+		mLog.debug( "Gain Decreased: " + mGain );
+	}
+	
+    public void setListener( RealSampleListener listener )
+    {
+		mListener = listener;
+    }
+}

src/dsp/gain/GainController.java

@@ -0,0 +1,8 @@
+package dsp.gain;
+
+public interface GainController
+{
+	public abstract void increase();
+
+	public abstract void decrease();
+}

src/dsp/gain/RealAutomaticGainControl.java

@@ -1,4 +1,4 @@
-package dsp.agc;
+package dsp.gain;
 
 import java.util.concurrent.atomic.AtomicBoolean;
 

src/source/mixer/RealMixerSource.java

@@ -29,7 +29,7 @@ import javax.sound.sampled.TargetDataLine;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
-import dsp.agc.RealAutomaticGainControl;
+import dsp.gain.RealAutomaticGainControl;
 import sample.Listener;
 import sample.adapter.SampleAdapter;
 import sample.real.RealBuffer;