trying to get rid of implausible locations delivered by the network provider

app/build.gradle

@@ -25,6 +25,6 @@ dependencies {
     testCompile 'junit:junit:4.12'
     compile 'com.android.support:appcompat-v7:24.2.1'
     compile 'com.android.support:design:24.2.1'
-    compile 'org.osmdroid:osmdroid-android:5.2@aar'
+    compile 'org.osmdroid:osmdroid-android:5.4.1:release@aar'
     compile 'com.google.code.gson:gson:2.7'
 }

app/src/main/java/org/y20k/trackbook/MainActivity.java

@@ -372,6 +372,8 @@ public class MainActivity extends AppCompatActivity implements TrackbookKeys, Di
             startService(intent);
 
         } else {
+            // TODO ask if user wants to save the last track before starting a new recording
+            // TODO alternatively only ask if last track was very short
             // show snackbar
             Snackbar.make(view, R.string.snackbar_message_tracking_started, Snackbar.LENGTH_SHORT).setAction("Action", null).show();
 

app/src/main/java/org/y20k/trackbook/MainActivityMapFragment.java

@@ -396,6 +396,7 @@ public class MainActivityMapFragment extends Fragment implements TrackbookKeys {
         // save track object
         SaveTrackAsyncHelper saveTrackAsyncHelper = new SaveTrackAsyncHelper();
         saveTrackAsyncHelper.execute();
+        // TODO add toast indicating track save
     }
 
 
@@ -587,7 +588,7 @@ public class MainActivityMapFragment extends Fragment implements TrackbookKeys {
 
 
     /**
-     * Inner class: Saves track to external storage using an AsyncTask
+     * Inner class: Saves track to external storage using AsyncTask
      */
     private class SaveTrackAsyncHelper extends AsyncTask<Void, Void, Void> {
 

app/src/main/java/org/y20k/trackbook/TrackerService.java

@@ -250,7 +250,17 @@ public class TrackerService extends Service implements TrackbookKeys, SensorEven
         } else {
             // get last WayPoint and compare it to current location
             Location lastWayPoint = mTrack.getWayPointLocation(trackSize - 1);
-            if (LocationHelper.isNewWayPoint(lastWayPoint, mCurrentBestLocation)) {
+
+            // compute average speed
+            float averageSpeed = 0f;
+            if (trackSize > 1) {
+                Location firstWayPoint = mTrack.getWayPointLocation(0);
+                float distance = firstWayPoint.distanceTo(lastWayPoint);
+                long timeDifference = lastWayPoint.getElapsedRealtimeNanos() - firstWayPoint.getElapsedRealtimeNanos();
+                averageSpeed = distance / ((float)timeDifference / ONE_NANOSECOND);
+            }
+
+            if (LocationHelper.isNewWayPoint(lastWayPoint, mCurrentBestLocation, averageSpeed)) {
                 // if new, add current best location to track
                 newWayPoint = mTrack.addWayPoint(mCurrentBestLocation);
             }

app/src/main/java/org/y20k/trackbook/helpers/LocationHelper.java

@@ -136,19 +136,33 @@ public final class LocationHelper implements TrackbookKeys {
 
 
     /* Checks if given location is a new WayPoint */
-    public static boolean isNewWayPoint(Location lastLocation, Location newLocation) {
+    public static boolean isNewWayPoint(Location lastLocation, Location newLocation, float averageSpeed) {
         float distance = newLocation.distanceTo(lastLocation);
         long timeDifference = newLocation.getElapsedRealtimeNanos() - lastLocation.getElapsedRealtimeNanos();
 
-        // TODO check for sudden location jump errors
+        if (newLocation.getProvider().equals(LocationManager.NETWORK_PROVIDER)) {
+            // SPECIAL CASE network: plausibility check for network provider. looking for sudden location jump errors
+            float speedDifference;
+            float currentSpeed = distance / ((float)timeDifference / ONE_NANOSECOND);
+            if (currentSpeed > averageSpeed) {
+                speedDifference = currentSpeed / averageSpeed;
+            } else {
+                speedDifference = averageSpeed / currentSpeed;
+            }
+            // check if speed is high (10 m/s == 36km/h) and has doubled
+            if (averageSpeed != 0f && currentSpeed > 10f && speedDifference > 2f) {
+                // implausible location
+                return false;
+            }
+
+            // DEFAULT network: distance is bigger than 50 meters and time difference bigger than 12 seconds
+            return distance > 50 && timeDifference >= 12 * ONE_NANOSECOND;
 
-        if (newLocation.getProvider().equals(LocationManager.GPS_PROVIDER)) {
-            // CASE GPS: distance is bigger than 10 meters and time difference bigger than 12 seconds
-            return distance > 10 && timeDifference >= TWELVE_SECONDS_IN_NANOSECONDS;
         } else {
-            // CASE network: distance is bigger than 50 meters and time difference bigger than 12 seconds
+            // DEFAULT GPS: distance is bigger than 10 meters and time difference bigger than 12 seconds
-            return distance > 50 && timeDifference >= TWELVE_SECONDS_IN_NANOSECONDS;
+            return distance > 10 && timeDifference >= 12 * ONE_NANOSECOND;
         }
+
     }
 
 

app/src/main/java/org/y20k/trackbook/helpers/TrackbookKeys.java

@@ -67,11 +67,11 @@ public interface TrackbookKeys {
     /* RESULTS */
 
     /* CONSTANTS */
+    long ONE_NANOSECOND = 1000000000L;
     long EIGHT_HOURS_IN_MILLISECONDS = 43200000; // maximum tracking duration
     long FIFTEEN_SECONDS_IN_MILLISECONDS = 15000; // timer interval for tracking
     long FIVE_MINUTES_IN_NANOSECONDS = 5L * 60000000000L; // determines a stop over
     long TWO_MINUTES_IN_NANOSECONDS = 2L * 60000000000L; // defines an old location
-    long TWELVE_SECONDS_IN_NANOSECONDS = 12000000000L; // defines a new location
 
 
     /* MISC */