I served aboard the USS Bigelow (DD942) from 1975-79 which was the test platform for the CIWS. the unit was installed where the aft 3" AA battery was. The system was tested by overflying the ship dragging a tow drone. the drones were obliterated and before the gun system was shut down the radar was so effective that it could locate and target the towcable and hit it as well. the radar tracks the projectiles as well as the target. I comes as no surprise that it can track mortar rounds.