why mobile phone gps provide sometime same coordinates on different location

Question

Background: I am now working on an Android app to track vehicles where I required to get device location on every 10 second as on management decision. We are already developed this app which provides us updated location on time as our expected time interval.

Problem: When Vehicles are driving on the roads, the app gives us correct coordinates as our expected time interval, but sometime 5-20 minutes it provide same coordinates yet the vehicle is in a different location.

Code Review: 1) We use a method named getLocation() inside LocationClass that provide us latitude longitude of a device current location.

private static final long MIN_DISTANCE_CHANGE_FOR_UPDATES = 5;
private static final long MIN_TIME_BW_UPDATES = 1000*20; 

public Location getLocation(Context context) {
    Location location=null;
    try {
        locationManager = (LocationManager) context
                .getSystemService(Context.LOCATION_SERVICE);

        // getting GPS status
        isGPSEnabled = locationManager
                .isProviderEnabled(LocationManager.GPS_PROVIDER);

        // getting network status
        isNetworkEnabled = locationManager
                .isProviderEnabled(LocationManager.NETWORK_PROVIDER);

        if (!isGPSEnabled && !isNetworkEnabled) {
            // no network provider is enabled
        } else {
            this.canGetLocation = true;
            if (ActivityCompat.checkSelfPermission(context, Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED && ActivityCompat.checkSelfPermission(context, Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
                Toast.makeText(context,"Please! Provide Location Access Permission.....", Toast.LENGTH_LONG).show();
                return TODO;
            }

            // if GPS Enabled get lat/long using GPS Services               

                if(isGPSEnabled) {
                    locationManager.requestLocationUpdates(
                            LocationManager.GPS_PROVIDER,
                            MIN_TIME_BW_UPDATES,
                            MIN_DISTANCE_CHANGE_FOR_UPDATES, this);
                    Log.d("GPS Enabled", "GPS Enabled");
                    if (locationManager != null) {
                        location = locationManager
                                .getLastKnownLocation(LocationManager.GPS_PROVIDER);
                        if (location != null) {
                            latitude = location.getLatitude();
                            longitude = location.getLongitude();
                            location.setProvider("GPS");                              
                        }
                    }
                }
                if (isNetworkEnabled && location==null) {
                    locationManager.requestLocationUpdates(
                            LocationManager.NETWORK_PROVIDER,
                            MIN_TIME_BW_UPDATES,
                            MIN_DISTANCE_CHANGE_FOR_UPDATES, this);
                    Log.d("Network", "Network");
                    if (locationManager != null) {
                        location = locationManager
                                .getLastKnownLocation(LocationManager.NETWORK_PROVIDER);
                        if (location != null) {
                            latitude = location.getLatitude();
                            longitude = location.getLongitude();
                            location.setProvider("AGPS");                                
                        }
                    }
                }                

        }

    } catch (Exception e) {
        e.printStackTrace();           
    }

    return location;
}

2) We repeat this method using a timer on a service named GPSTracker at fixed time interval.

public class GPSTracker extends Service implements LocationListener {
private Timer mTimer = null;
private Handler mHandler = new Handler();
Location location;
@Override
public void onCreate() {
    super.onCreate();

    if (mTimer != null) {
        mTimer.cancel();
    } else {
        // recreate new
        mTimer = new Timer();
    }
    // schedule task
    mTimer.scheduleAtFixedRate(new TimeDisplayTimerTask(), 10 * 1000, 10 * 1000);
}

class TimeDisplayTimerTask extends TimerTask {

    @Override
    public void run() {
        // run on another thread
        mHandler.post(new Runnable() {

            @Override
            public void run() {
                location=new Location("");
                LocationCls cls = new LocationCls();
                location = cls.getLocation(getBaseContext());
            }

        });
    }

}
}

I am trying to solve this issue a 2 long day but not found any coding problem or solution yet. Any Solution or Suggestion is highly appreciate.

Thanks in advance....