if (event.sensor.type == Sensor.TYPE_MAGNETIC_FIELD) {
                // mGeomagnetic = event.values;
                mGeomagnetic[0] = alpha * mGeomagnetic[0] + (1 - alpha) * event.values[0]
                mGeomagnetic[1] = alpha * mGeomagnetic[1] + (1 - alpha) * event.values[1]
                mGeomagnetic[2] = alpha * mGeomagnetic[2] + (1 - alpha) * event.values[2]