void watcherPositionChanged(object sender, GeoPositionChangedEventArgs<GeoCoordinate> e)
{
if (e.Position.Location.IsUnknown) { _status = false; return; }
_latitude = e.Position.Location.Latitude.ToString("0.0000");
_longitude = e.Position.Location.Longitude.ToString("0.0000");
_speed = e.Position.Location.Speed.ToString("0.0");
if (_speed == "NaN") { _speed = "0.0"; }
_heading = e.Position.Location.Course.ToString("0.0");
if (_heading == "NaN") { _heading = "0.0"; }
_altitude = e.Position.Location.Altitude.ToString("0.0");
if (_altitude == "NaN") { _altitude = "0.0"; }
_horizontalaccuracy = e.Position.Location.HorizontalAccuracy.ToString();
_verticalaccuracy = e.Position.Location.VerticalAccuracy.ToString();
_currentlocation = e.Position.Location;
_status = true;
}