Add velocity information to track when available

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

@@ -6,13 +6,15 @@
 public class SurfacePosition extends ExtendedSquitter {
  private final String address;
  private int velocityEncoded = 0;
+ private double velocity = 0;
 
  private boolean trackValid = false;
  private int trackEncoded = 0;
 
  private double lat;
  private double lon;
  private boolean positionAvailable = false;
+ private boolean velocityAvailable = false;
 
  public SurfacePosition(short[] data, String address) {
  super(data);
@@ -22,6 +24,8 @@ public SurfacePosition(short[] data, String address) {
  @Override
  public SurfacePosition decode() {
  velocityEncoded = ((data[4] & 0x7) << 4) | (data[5] >>> 4);
+ velocityAvailable = velocityEncoded != 0;
+ velocity = decodeEncodedVelocity();
 
  trackValid = ((data[5] >>> 3) & 0x1) == 0x1;
  trackEncoded = ((data[5] & 0x7) << 4) | (data[6] >>> 4);
@@ -46,20 +50,31 @@ public SurfacePosition decode() {
  } else {
  this.positionAvailable = false;
  }
- return this; }
+
+ return this;
+ }
 
  @Override
  public void apply(Track track) {
  track.setGroundBit(true);
+
  if (positionAvailable) {
  track.setLatLon(lat, lon);
  }
+
+ if (velocityAvailable) {
+ track.setGs(velocity);
+ }
  }
 
  public boolean isPositionAvailable() {
  return positionAvailable;
  }
 
+ public boolean isVelocityAvailable() {
+ return this.velocityAvailable;
+ }
+
  public double getLat() {
  return lat;
  }
@@ -77,6 +92,22 @@ public int getVelocityEncoded() {
  }
 
  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;
+ }
+
+ private double decodeEncodedVelocity() {
  if (this.velocityEncoded == 1) {
  return 0;
  }
@@ -104,18 +135,7 @@ public double getVelocity() {
  if (this.velocityEncoded == 124) {
  return 175.0;
  }
- return 0; // Could be either "not available" or "reserved"... just assume zero speed for now
- }
 
- public boolean isTrackValid() {
- return trackValid;
- }
-
- public int getTrackEncoded() {
- return trackEncoded;
- }
-
- public double getTrack() {
- return trackEncoded * 360.0 / 128.0;
+ return 0; // Could be either "not available" or "reserved"... just assume zero speed for now
  }
 }

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

@@ -46,6 +46,9 @@ public void test_surface_position_aircraft() throws UnknownDownlinkFormatExcepti
  assertTrue(positionB.isPositionAvailable());
  assertEquals(53.3604, positionB.getLat(), 0.001);
  assertEquals(-2.2671, positionB.getLon(), 0.001);
+
+ assertTrue(positionB.isVelocityAvailable());
+ assertEquals(1.75, positionB.getVelocity());
  }
 
  @Test