The AN/SPG-51 is an American tracking / illumination fire-control radar for RIM-24 Tartar and RIM-66 Standard missiles. It is used for target tracking and Surface-to-air missile guidance as part of the Mk. 73 gun and missile director system, which is part of the Tartar Guided Missile Fire Control System.

A pulse-Doppler radar is a radar system that determines the range to a target using pulse-timing techniques, and uses the Doppler effect of the returned signal to determine the target object's velocity. It combines the features of pulse radars and continuous-wave radars, which were formerly separate due to the complexity of the electronics.