P25 - work in progress to improve CQPSK LSM audio output. Audio output is still choppy but greatly improved over the previous test release.

src/dsp/psk/QPSKStarSlicer.java

@@ -0,0 +1,58 @@
+package dsp.psk;
+
+import sample.Broadcaster;
+import sample.Listener;
+import sample.complex.ComplexSample;
+import dsp.symbol.Dibit;
+
+public class QPSKStarSlicer implements Listener<ComplexSample>
+{
+	private Broadcaster<Dibit> mBroadcaster = new Broadcaster<Dibit>();
+
+	/**
+	 * Slices a ComplexSample representing a phase shifted symbol according to
+	 * the following constellation pattern:
+	 * 
+	 *    11 | 01
+	 *    ---|---
+	 *    10 | 00
+	 */
+	public QPSKStarSlicer()
+	{
+	}
+	
+	public void dispose()
+	{
+		mBroadcaster.dispose();
+		mBroadcaster = null;
+	}
+
+	public void addListener( Listener<Dibit> listener )
+	{
+		mBroadcaster.addListener( listener );
+	}
+
+	public void removeListener( Listener<Dibit> listener )
+	{
+		mBroadcaster.removeListener( listener );
+	}
+
+	@Override
+	public void receive( ComplexSample sample )
+	{
+		mBroadcaster.broadcast( decide( sample ) );
+	}
+	
+	public static Dibit decide( ComplexSample sample )
+	{
+		if( sample.inphase() > 0 )
+		{
+			return sample.quadrature() > 0 ? Dibit.D00_PLUS_1 : Dibit.D10_MINUS_1;
+		}
+		else
+		{
+			return sample.quadrature() > 0 ? Dibit.D01_PLUS_3 : Dibit.D11_MINUS_3;
+		}
+	}
+	
+}