Radacoustic detection of projectiles by a retrodirective radar

An X-band retrodirective radar is shown experimentally to provide two signals from a firearm deployed at moderate range: (1) the normal reflection from the airborne projectile as it approaches the radar, and (2) a secondary reflection from the muzzle-blast acoustic wave. The combination of these two signals provides projectile bearing as well as an accurate estimation of range to the shooter by a differential time-of-flight calculation.