In 1904, he demonstrated the feasibility of detecting a ship in dense fog, but not its distance from the transmitter. The German inventor Christian Hülsmeyer was the first to use radio waves to detect "the presence of distant metallic objects". In his report, Popov wrote that this phenomenon might be used for detecting objects, but he did nothing more with this observation. In 1897, while testing this equipment for communicating between two ships in the Baltic Sea, he took note of an interference beat caused by the passage of a third vessel. The next year, he added a spark-gap transmitter. In 1895, Alexander Popov, a physics instructor at the Imperial Russian Navy school in Kronstadt, developed an apparatus using a coherer tube for detecting distant lightning strikes. Main article: History of radar First experiments Īs early as 1886, German physicist Heinrich Hertz showed that radio waves could be reflected from solid objects. With the emergence of driverless vehicles, radar is expected to assist the automated platform to monitor its environment, thus preventing unwanted incidents. One example is LIDAR, which uses predominantly infrared light from lasers rather than radio waves. Other systems similar to radar make use of other parts of the electromagnetic spectrum. High tech radar systems are associated with digital signal processing, machine learning and are capable of extracting useful information from very high noise levels. The modern uses of radar are highly diverse, including air and terrestrial traffic control, radar astronomy, air-defense systems, antimissile systems, marine radars to locate landmarks and other ships, aircraft anti-collision systems, ocean surveillance systems, outer space surveillance and rendezvous systems, meteorological precipitation monitoring, altimetry and flight control systems, guided missile target locating systems, self-driving cars, and ground-penetrating radar for geological observations. During RAF RADAR courses in 1954–5 at Yatesbury Training Camp "radio azimuth direction and ranging" was suggested. The term radar has since entered English and other languages as a common noun, losing all capitalization. The term RADAR was coined in 1940 by the United States Navy as an acronym for "radio detection and ranging".
A key development was the cavity magnetron in the United Kingdom, which allowed the creation of relatively small systems with sub-meter resolution. Radar was developed secretly for military use by several countries in the period before and during World War II.
Radio waves (pulsed or continuous) from the transmitter reflect off the object and return to the receiver, giving information about the object's location and speed. A radar system consists of a transmitter producing electromagnetic waves in the radio or microwaves domain, a transmitting antenna, a receiving antenna (often the same antenna is used for transmitting and receiving) and a receiver and processor to determine properties of the object(s). It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, weather formations, and terrain. Radar ( radio detection and ranging) is a detection system that uses radio waves to determine the distance ( ranging), angle, and radial velocity of objects relative to the site. It rotates steadily, sweeping the airspace with a narrow beam. Radar of the type used for detection of aircraft.
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