Tech. Sgt. Matthew Hoover, a Combat Shield crew leader assigned to the 16th Electronic Warfare Squadron, Eglin Air Force Base, Florida, monitors a USM-642 “Raven” signal generator during Combat Shield, Oct. 20, 2015, at Seymour Johnson Air Force Base, North Carolina. Hoover used the USM-642 to simulate real-world radar emissions and test the sensitivity of the threat detection systems of an F-15E Strike Eagle. (U.S. Air Force photo/Senior Airman Aaron J. Jenne)