A radar speed gun (also radar gun and speed gun) is a small device used to measure the speed of moving objects. It is used in law-enforcement to measure the speed of moving vehicles and is often used in professional spectator sport, for such things as the measurement of the speed of pitched baseballs, runners and tennis serves.
A radar speed gun is a Doppler radar unit that may be hand-held, vehicle-mounted or static. It measures the speed of the objects at which it is pointed by detecting a change in frequency of the returned radar signal caused by the Doppler effect, whereby the frequency of the returned signal is increased in proportion to the object's speed of approach if the object is approaching, and lowered if the object is receding. Such devices are frequently used for speed limit enforcement, although more modern LIDAR speed gun instruments, which use pulsed laser light instead of radar, have begun to replace radar guns in the past decade, because of limitations associated with small radar systems.
The radar speed gun was invented by Bryce K. Brown of Decatur Electronics in March 1954, and was first used in Chicago, Illinois in April 1954. Patrolman Leonard Baldy was the first officer to issue a speeding ticket using the new device.
Read more about Radar Gun: Limitations, Associated Cameras, Newer Instruments
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