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/spectrum/menu/DBScaleItem.java

@@ -0,0 +1,58 @@
+package spectrum.menu;
+
+import java.awt.event.MouseEvent;
+import java.awt.event.MouseListener;
+
+import javax.swing.JSlider;
+import javax.swing.event.ChangeEvent;
+import javax.swing.event.ChangeListener;
+
+import spectrum.SpectralDisplayAdjuster;
+
+public class DBScaleItem extends JSlider implements ChangeListener
+{
+    private static final long serialVersionUID = 1L;
+
+    private SpectralDisplayAdjuster mAdjuster;
+    private int mDefaultValue;
+    
+    public DBScaleItem( SpectralDisplayAdjuster adjuster, int defaultValue )
+    {
+    	super( JSlider.HORIZONTAL, -160, -30, adjuster.getDBScale() );
+    	mDefaultValue = defaultValue;
+    	
+    	mAdjuster = adjuster;
+    	
+    	setMajorTickSpacing( 40 );
+    	setMinorTickSpacing( 10 );
+    	setPaintTicks( true );
+    	setPaintLabels( true );
+    	
+    	addChangeListener( this );
+    	
+    	addMouseListener( new MouseListener()
+		{
+			@Override
+			public void mouseClicked( MouseEvent event )
+			{
+				if( event.getClickCount() == 2 )
+				{
+					DBScaleItem.this.setValue( mDefaultValue );
+				}
+			}
+			
+			public void mouseReleased( MouseEvent arg0 ) {}
+			public void mousePressed( MouseEvent arg0 ) {}
+			public void mouseExited( MouseEvent arg0 ) {}
+			public void mouseEntered( MouseEvent arg0 ) {}
+		} );
+    }
+
+	@Override
+    public void stateChanged( ChangeEvent event )
+    {
+		int value = ((JSlider)event.getSource()).getValue();
+		
+		mAdjuster.setDBScale( value );
+    }
+}