I am a newbie in need of help tuning a Kalman filter. The tuning knobs I have are the process noise of the filter. I have measurements statistics characterized by the sensor manufacturer and I am using that as the measurement noise. Other than the measurements, I do not have any other truth data. So how do I tell if the tuning is resulting in a better filter or not. In a crude sense, I can tell a bad filter if the filter output diverges from the measurements. But other than that, how do I tell if the filter output is converging to the truth. How do I tell if one set of process noise figures are better than another?