Tech. Sgt. Matthew Hoover, a Combat Shield crew leader assigned to the 16th Electronic Warfare Squadron, Eglin Air Force Base, Florida, operates a USM-642 “Raven” signal generator during Combat Shield, Oct. 20, 2015, at Seymour Johnson Air Force Base, North Carolina. The USM-642 is used to determine the sensitivity of an aircraft’s defensive EW systems. (U.S. Air Force photo/Senior Airman Aaron J. Jenne)