Improved LTR FSK decoder for LTR, LTR-Net and Passport decoders. Added IIR DC blocking filter and used improved slicer from the FSK decoder.

Added instrumentation to Passport decoder and updated some of the instrumentation components.

src/buffer/BooleanAveragingBuffer.java

@@ -0,0 +1,107 @@
+/*******************************************************************************
+ *     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 buffer;
+
+import java.util.Arrays;
+
+
+/**
+ * Circular Buffer - implements a circular buffer with a method to get the 
+ * current head of the buffer, and put a new value in its place at the same
+ * time
+ * 
+ * Also provides averaging over the elements in the buffer
+ */
+public class BooleanAveragingBuffer {
+
+	private boolean[] mBuffer;
+	private int mBufferPointer;
+	
+	public BooleanAveragingBuffer( int length )
+	{
+		mBuffer = new boolean[ length ];
+		
+		//Preload the array with false values
+		Arrays.fill( mBuffer, false );
+	}
+	
+	public boolean get( boolean newValue )
+	{
+		//Fetch current boolean value
+		boolean retVal = mBuffer[ mBufferPointer ];
+
+		//Load the new value into the buffer
+		put( newValue );
+		
+		return retVal;
+	}
+
+	/**
+	 * Loads the newValue into this buffer and adjusts the buffer pointer
+	 * to prepare for the next get/put cycle
+	 */
+	private void put( boolean newValue )
+	{
+		//Store the new value to the buffer
+		mBuffer[ mBufferPointer ] = newValue;
+		
+		//Increment the buffer pointer
+		mBufferPointer++;
+
+		//Wrap the buffer pointer around to 0 when necessary
+		if( mBufferPointer >= mBuffer.length )
+		{
+			mBufferPointer = 0;
+		}
+	}
+
+	/**
+	 * Loads the newValue into the buffer, calculates the average
+	 * and returns that average from this method
+	 * 
+	 * This effectively performs low-pass filtering
+	 */
+	public boolean getAverage( boolean newValue )
+	{
+		//Load the new value into the buffer
+		put( newValue );
+		
+		int trueCount = 0;
+		
+		for( int x = 0; x < mBuffer.length; x++ )
+		{
+			if( mBuffer[ x ] )
+			{
+				trueCount++;
+			}
+		}
+
+		/**
+		 * If the number of true values in the buffer is 
+		 * more than half, return true, otherwise, false
+		 */
+		if( trueCount > (int)( mBuffer.length / 2 ) )
+		{
+			return true;
+		}
+		else
+		{
+			return false;
+		}
+	}
+}