A Doppler radar is a specialized radar that uses the Doppler effect to produce velocity data about objects at a distance. It does this by bouncing a microwave signal off a desired target and analyzing how the object's motion has altered the frequency of the returned signal. This variation gives direct and highly accurate measurements of the radial component of a target's velocity relative to the radar. The term applies to radar systems in many domains like aviation, police radar detectors, navigation, meteorology, etc.
U.S. Army soldier using a radar gun, an application of Doppler radar, to catch speeding violators.
AN/APN-81 Doppler radar navigation system, mid-1950s
The US Weather Bureau's first experimental Doppler weather radar unit was obtained from the US Navy in the 1950s
Doppler navigation system in the National Electronics Museum
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.
Airborne pulse-Doppler radar antenna