Updated spectral display to used dBm scale and removed baseline/amplification items.

Updated sample handling code to use -1.0 to 1.0 float values throughout, to support P25 decoder and symbol filter.

src/sample/adapter/ByteSampleAdapter.java

@@ -0,0 +1,54 @@
+/*******************************************************************************
+ *     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 sample.adapter;
+
+public class ByteSampleAdapter extends SampleAdapter
+{
+	private final static float[] LOOKUP_VALUES;
+
+	/**
+	 * Creates a static lookup table that converts the 8-bit valued range 
+	 * from 0 - 255 into scaled float values of -1.0 to 0 to 1.0
+	 */
+	static
+	{
+		LOOKUP_VALUES = new float[ 256 ];
+		
+		for( int x = 0; x < 256; x++ )
+		{
+			LOOKUP_VALUES[ x ] = (float)( x - 128 );
+		}
+		
+		LOOKUP_VALUES[ 128 ] = 0.0000001f;
+	}
+
+	@Override
+    public float[] convert( byte[] samples )
+    {
+		float[] convertedSamples = new float[ samples.length ];
+		int pointer = 0;
+		
+		for( byte sample: samples )
+		{
+			/* Convert byte value into float from the lookup table */
+			convertedSamples[ pointer++ ] = LOOKUP_VALUES[ ( sample & 0xFF ) ];
+		}
+		
+	    return convertedSamples;
+    }
+}

src/sample/adapter/ChannelShortAdapter.java

@@ -27,6 +27,7 @@ import source.mixer.MixerChannel;
  */
 public class ChannelShortAdapter extends SampleAdapter
 {
+	private ShortToFloatMap mMap = new ShortToFloatMap();
 	private ByteOrder mByteOrder = ByteOrder.LITTLE_ENDIAN;
 	private MixerChannel mMixerChannel;
 	
@@ -55,7 +56,7 @@ public class ChannelShortAdapter extends SampleAdapter
         {
         	if( mMixerChannel == MixerChannel.LEFT )
         	{
-            	processed[ pointer ] = (float)buffer.getShort();
+            	processed[ pointer ] = mMap.get( buffer.getShort() );
 
             	/* Throw away the right channel */
             	buffer.getShort();
@@ -65,7 +66,7 @@ public class ChannelShortAdapter extends SampleAdapter
             	/* Throw away the left channel */
             	buffer.getShort();
 
-            	processed[ pointer ] = (float)buffer.getShort();
+            	processed[ pointer ] = mMap.get( buffer.getShort() );
         	}
         	
         	pointer++;

src/sample/adapter/ShortAdapter.java

@@ -25,6 +25,7 @@ import java.nio.ByteOrder;
  */
 public class ShortAdapter extends SampleAdapter
 {
+	private ShortToFloatMap mMap = new ShortToFloatMap();
 	private ByteOrder mByteOrder = ByteOrder.LITTLE_ENDIAN;
 	
 	@Override
@@ -42,7 +43,7 @@ public class ShortAdapter extends SampleAdapter
 
         while( buffer.hasRemaining() )
         {
-        	processed[ pointer ] = (float)buffer.getShort();
+        	processed[ pointer ] = mMap.get( buffer.getShort() );
 
         	pointer++;
         }

src/sample/adapter/ShortToFloatMap.java

@@ -0,0 +1,19 @@
+package sample.adapter;
+
+public class ShortToFloatMap
+{
+	private static float[] MAP = new float[ 65536 ];
+	
+	static
+	{
+		for( int x = 0; x < 65536; x++ )
+		{
+			MAP[ x] = (float)( x - 32768 ) / 32768.0f;
+		}
+	}
+
+	public float get( short value )
+	{
+		return MAP[ 32768 + value ];
+	}
+}