Merge pull request #50 from terminal2/EvenOddPositions

Move from local position decoding to global unambiguous position decoding when possible

Author: Douglasdc3

gradle.properties

@@ -1,5 +1,5 @@
 GROUP=aero.t2s
-VERSION_NAME=0.2.5-SNAPSHOT
+VERSION_NAME=0.2.6-SNAPSHOT
 
 POM_ARTIFACT_ID=mode-s
 POM_NAME=Mode-S/ADS-B (1090Mhz)

src/main/java/aero/t2s/modes/CprPosition.java

@@ -1,9 +1,28 @@
 package aero.t2s.modes;
 
+import java.time.Instant;
+
 public class CprPosition {
     private double lat;
     private double lon;
-    private int time;
+    private boolean valid;
+    private long time;
+
+    public CprPosition() {
+        this.lat = 0.0;
+        this.lon = 0.0;
+        this.valid = false;
+    }
+    public CprPosition(double lat, double lon) {
+        setLatLon(lat ,lon);
+    }
+
+    public void setLatLon(double lat, double lon) {
+        this.lat = lat;
+        this.lon = lon;
+        this.time = Instant.now().toEpochMilli();
+        this.valid = true;
+    }
 
     public void setLat(double lat) {
         this.lat = lat;
@@ -21,15 +40,19 @@ public double getLon() {
         return lon;
     }
 
-    public void setTime(int time) {
+    public void setTime(long time) {
         this.time = time;
     }
 
-    public int getTime() {
+    public long getTime() {
         return time;
     }
 
     public boolean isValid() {
-        return lat != 0d && lon != 0;
+        return valid;
+    }
+
+    public boolean isExpired() {
+        return time < Instant.now().minusSeconds(10).toEpochMilli();
     }
 }

src/main/java/aero/t2s/modes/ModeSHandler.java

@@ -1,6 +1,7 @@
 package aero.t2s.modes;
 
 import aero.t2s.modes.decoder.df.DownlinkFormat;
+import aero.t2s.modes.decoder.df.df17.AirbornePosition;
 
 import java.util.function.Consumer;
 
@@ -42,10 +43,10 @@ protected short[] toData(final String input) throws EmptyMessageException, ModeA
     }
 
     public void start() {
-
+        AirbornePosition.start();
     }
 
     public void stop() {
-
+        AirbornePosition.stop();
     }
 }

src/main/java/aero/t2s/modes/Track.java

@@ -11,6 +11,7 @@ public class Track {
     private Altitude altitude = new Altitude();
     private double lat;
     private double lon;
+    private boolean positionAvailable = false;
     private int vx;
     private int vy;
     private double gs;
@@ -172,7 +173,13 @@ public boolean isGroundBit() {
         return groundBit;
     }
 
+    public void setLatLon(double lat, double lon) {
+        this.lat = lat;
+        this.lon = lon;
+        this.positionAvailable = true;
+    }
     public void setLat(double lat) {
+        //TODO How do we know if position really is available if we only set the lat? Can we remove this method?
         this.lat = lat;
     }
 
@@ -181,6 +188,7 @@ public double getLat() {
     }
 
     public void setLon(double lon) {
+        //TODO How do we know if position really is available if we only set the lon? Can we remove this method?
         this.lon = lon;
     }
 
@@ -245,7 +253,7 @@ public int getModeA() {
     }
 
     public boolean isPositionAvailable() {
-        return lat != 0 & lon != 0;
+        return positionAvailable;
     }
 
     public void setGeometricHeightOffset(int geometricHeightOffset) {

src/main/java/aero/t2s/modes/decoder/Decoder.java

@@ -50,7 +50,7 @@ public DownlinkFormat decode(short[] data) throws UnknownDownlinkFormatException
                 df = new DF16(data);
                 break;
             case 17:
-                df = new DF17(data, originLat, originLon);
+                df = new DF17(data);
                 break;
             case 18:
                 df = new DF18(data);

src/main/java/aero/t2s/modes/decoder/df/DF17.java

@@ -4,15 +4,10 @@
 import aero.t2s.modes.decoder.df.df17.*;
 
 public class DF17 extends DownlinkFormat {
-    private final double originLat;
-    private final double originLon;
-
     private ExtendedSquitter extendedSquitter;
 
-    public DF17(short[] data, double originLat, double originLon) {
+    public DF17(short[] data) {
         super(data, IcaoAddress.FROM_MESSAGE);
-        this.originLat = originLat;
-        this.originLon = originLon;
     }
 
     @Override
@@ -34,7 +29,7 @@ public DF17 decode() {
             case 20:
             case 21:
             case 22:
-                extendedSquitter = new AirbornePosition(data, originLat, originLon);
+                extendedSquitter = new AirbornePosition(data, getIcao());
                 break;
             case 1:
             case 2: