electromagnetic sensor used for detecting, locating, tracking, and recognizing objects of various kinds at considerable distances. It operates by transmitting electromagnetic energy toward objects, commonly referred to as targets, and observing the...

For the last century, much of the world's scientific research has been conducted at the request of governments, and most often under the supervision of the military. The technological advances resulting from such research--from the development of the...

Although they rely on two fundamentally different types of wave transmission, Radio Detection and Ranging (RADAR) and Sound Navigation and Ranging (SONAR) both are remote sensing systems with important military, scientific and commercial applications....

In the latter part of the nineteenth century electricity and magnetism were a prime area of research in Europe. In 1887, Heinrich Hertz in Germany was the first to realize the significance of the behavior of radio waves. Hertz found that, like most...

System that uses electromagnetic echoes to detect and locate objects. It can also measure precisely the distance (range) to an object and the speed at which the object is moving toward or away from the observing unit. Radar (the name is derived from...

Used to address a radar officer in the Royal Navy in Sylvester, by Edward Hyams. The term would now suggest to a wide audience the nickname of Radar O’Reilly, the character in the long-running television series M.A.S.H. starring Alan Alda as...

A system for the detection of the position and speed of distant objects such as aircraft through the detection of reflected very high-frequency radio pulses emitted specifically for the purpose. The name derives from Radio Detection And Ranging. See...

The transmission of radiant energy in the form of electromagnetic waves, streams of particles, sound or heat. The term is particularly applied to those particles or energy emitted during the process of nuclear decay. See also: NUCLEAR FISSION; NUCLEAR...

in electronics, the process of rectifying a radio wave and recovering any information superimposed on it; it is essentially the reverse of modulation...

Radar is a system that uses electromagnetic waves to identify the range, altitude, direction, or speed of both moving and fixed objects such as aircraft, ships, motor vehicles, weather formations, and terrain. A transmitter emits radio waves, which are...