171019-N-BN978-014 GREAT LAKES, Ill. (Oct. 19, 2017) A student at the Electronics Technicians and Fire Controlman "A" School prepares to troubleshoot a radar simulator partial task trainer (PTT) at the Center for Surface Combat Systems Unit, Great Lakes, Oct. 19, 2017. Over the past year students have been utilizing the PTT system after a a complete overhaul of the equipment. (U.S. Navy photo by Brian Walsh/Released)