Scans the ground for anomalous radio reflectors. This particular unit is earmarked for archeology purposes -- finding shallow graves in open fields. Basically you're looking for anything in the ground that will changed how the radio wave reflects back up to the surface (could be anything, but sometimes it's graves!)
So it makes a heat nap of how stuff in the ground messes with the transmitted radio waves?
Does the wheels have encoders to track the movement of the cart, or does it use a GPS fix?