Add true heading when available to track on surface position

Author: Douglasdc3

src/main/java/aero/t2s/modes/decoder/df/df17/SurfacePosition.java

@@ -8,8 +8,9 @@ public class SurfacePosition extends ExtendedSquitter {
     private int velocityEncoded = 0;
     private double velocity = 0;
 
-    private boolean trackValid = false;
+    private boolean trackAvailable = false;
     private int trackEncoded = 0;
+    private double track = 0;
 
     private double lat;
     private double lon;
@@ -27,8 +28,9 @@ public SurfacePosition decode() {
         velocityAvailable = velocityEncoded != 0;
         velocity = decodeEncodedVelocity();
 
-        trackValid = ((data[5] >>> 3) & 0x1) == 0x1;
+        trackAvailable = ((data[5] >>> 3) & 0x1) == 0x1;
         trackEncoded = ((data[5] & 0x7) << 4) | (data[6] >>> 4);
+        track = trackEncoded * 360.0 / 128.0;
 
         // Decode position
         int time = (data[6] >>> 3) & 0x1;
@@ -65,6 +67,10 @@ public void apply(Track track) {
         if (velocityAvailable) {
             track.setGs(velocity);
         }
+
+        if (trackAvailable) {
+            track.setTrueHeading(this.track);
+        }
     }
 
     public boolean isPositionAvailable() {
@@ -75,6 +81,10 @@ public boolean isVelocityAvailable() {
         return this.velocityAvailable;
     }
 
+    public boolean isTrackAvailable() {
+        return trackAvailable;
+    }
+
     public double getLat() {
         return lat;
     }
@@ -95,16 +105,12 @@ public double getVelocity() {
         return this.velocity;
     }
 
-    public boolean isTrackValid() {
-        return trackValid;
-    }
-
     public int getTrackEncoded() {
         return trackEncoded;
     }
 
     public double getTrack() {
-        return trackEncoded * 360.0 / 128.0;
+        return track;
     }
 
     private double decodeEncodedVelocity() {

src/test/java/aero/t2s/modes/decoder/df/df17/SurfacePositionTest.java

@@ -27,7 +27,7 @@ public void test_surface_position_aircraft() throws UnknownDownlinkFormatExcepti
         SurfacePosition positionA = (SurfacePosition) exSqA;
         assertEquals(13, positionA.getVelocityEncoded());
         assertEquals(2.0, positionA.getVelocity());
-        assertTrue(positionA.isTrackValid());
+        assertTrue(positionA.isTrackAvailable());
         assertEquals(82, positionA.getTrackEncoded());
         assertEquals(230.625, positionA.getTrack(), 0.001);
         // We should NOT have a valid position after only one frame
@@ -48,7 +48,10 @@ public void test_surface_position_aircraft() throws UnknownDownlinkFormatExcepti
         assertEquals(-2.2671, positionB.getLon(), 0.001);
 
         assertTrue(positionB.isVelocityAvailable());
-        assertEquals(1.75, positionB.getVelocity());
+        assertEquals(1.75, positionB.getVelocity(), 0.1);
+
+        assertTrue(positionB.isTrackAvailable());
+        assertEquals(230.625, positionB.getTrack(), 0.1);
     }
 
     @Test
@@ -63,7 +66,7 @@ public void test_surface_position_vehicle() throws UnknownDownlinkFormatExceptio
         SurfacePosition position = (SurfacePosition) exSq;
         assertEquals(1, position.getVelocityEncoded());
         assertEquals(0.0, position.getVelocity());
-        assertFalse(position.isTrackValid());
+        assertFalse(position.isTrackAvailable());
     }
 
     private DownlinkFormat testMessage(String message) throws UnknownDownlinkFormatException {