Radar has many different types and applications: "Search radars" scan a wide area with pulses of short radio waves. They usually scan the area two to four times a minute. The waves are usually less than a meter long. Ships and planes are metal, and reflect radio waves. The radar measures the distance to the reflector by measuring the time from emission of a pulse to reception, and dividing by the speed of light. To be accepted, the received pulse has to lie within a period of time called the range gate. The radar determines the direction because the short radio waves behave like a search light when emitted from the reflector of the radar set's antenna. "Targeting radars" use the same principle but scan a much smaller area far more often, usually several times a second or more, where a search radar might scan a few times per minute. Some targeting radars have a range gate that can track a target, to eliminate clutter and electronic counter-measures. "Radar proximity fuzes" are attached to anti-aircraft artillery shells or other explosive devices, and detonate the device when it approaches a large object. They use a small rapidly pulsing omnidirectional radar, usually with a powerful battery that has a long storage life, and a very short operational life. The fuzes used in anti-aircraft artillery have to be mechanically designed to accept fifty thousand gravities of acceleration, yet still be cheap enough to throw away. "Weather radars" can resemble search radars. These radar use radio waves with horizontal, dual (horizontal and vertical), or circular polarization. The frequency selection of weather radar is a performance compromise between precipitation reflectivity and attenuation due to atmospheric water vapor. Some weather radars uses doppler to measure wind speeds. "Marine radars" are used by ships for collision avoidance and navigation purposes. The frequency band of radar used on most ships is x-band (9 GHz/3 cm), but s-band (3 GHz/10 cm) radar is also installed on most ocean going ships to provide better detection of ships in rough sea and heavy rain condition. Vessel Traffic Centre also use marine radars (x or s band) for tracking ARPA and provides collision avoidance or traffic regulation of ships in the survallence area. "Navigational radars" resemble search radar, but use very short waves that reflect from earth and stone. They are common on commercial ships and long-distance commercial aircraft. "General purpose radars" are increasingly being substituted for pure navigational radars. These generally use navigational radar frequencies, but modulate the pulse so the receiver can determine the type of surface of the reflector. The best general-purpose radars distinguish the rain of heavy storms, as well as land and vehicles. Some can superimpose sonar and map data from GPS position. "Radar altimeters" measure an aircraft's true height above ground. Air traffic control uses Primary and Secondary Radars Primary radar is a "classical" radar which reflects all kind of echoes, including aircraft and clouds. Secondary radar emits pulses and listens for special answer of digital data emitted by an Aircraft Transponder as an answer. Transponders emit different kind of data like a 4 octal ID (mode A), the onboard calculated altitude (mode C) or the Callsign (not the flight number) (mode S). Military use transponders to establish the nationality and intention of an aircraft, so that air defenses can identify possibly hostile radar returns. This military system is called IFF (Identification Friend or Foe). Mapping radars" are used to scan a large region for remote sensing and geography applications. They generally use synthetic aperture radar, which limits them to relatively static targets, normally terrain. Wearable radar and miniature radar systems are used as electric seeing aids for the visually impaired, as well as early warning collision detection and situational awareness. This long range RADAR antenna, known as ALTAIR, is used to detect and track space objects in conjunction with ABM testing at the Ronald Reagan Test Site on the Kwajalein atoll[1]. RADAR is a system that uses radio waves to determine and map the location, direction, and/or speed... Look up Proximity fuze in Wiktionary, the free dictionary A proximity fuze (also called a VT fuze) is a fuze that is designed to detonate an explosive automatically when close enough to the target to destroy it. ... American troops man an anti-aircraft gun near the Algerian coastline in 1943 Anti-aircraft, or air defense, is any method of combating military aircraft from the ground. ... This article is concerned solely with chemical explosives. ... For other uses, see g force. ... To meet Wikipedias quality standards, this article or section may require cleanup. ... Doppler radar uses the Doppler effect to measure the relative velocity information from a radar system. ... This long range RADAR antenna, known as ALTAIR, is used to detect and track space objects in conjunction with ABM testing at the Ronald Reagan Test Site on the Kwajalein atoll[1]. RADAR is a system that uses radio waves to determine and map the location, direction, and/or speed... The X band, ranging from 8. ... The S band ranges from 2. ... The acronym ARPA has several meanings: It is the former abbreviation of a U.S. military organization now known as the Defense Advanced Research Projects Agency (DARPA). ... Over fifty GPS satellites such as this NAVSTAR have been launched since 1978. ... Air Traffic Control Towers (ATCTs) at Schiphol Airport Air traffic control (ATC) is a service provided by ground-based controllers who direct aircraft on the ground and in the air. ... An Airbus A380, currently the worlds largest airliner An aircraft is any vehicle or craft capable of atmospheric flight. ... A Secondary Surveillance Radar (SSR) is a radar device installed in air traffic control facilities to allow the precise identification of aircraft. ... In telecommunication, the term transponder (sometimes abbreviated to XPDR or TPDR) has the following meanings: An automatic device that receives, amplifies, and retransmits a signal on a different frequency (see also broadcast translator). ... A flight number, when combined with the name of the airline and the date, identifies a particular flight. ... In telecommunications, identification, friend or foe (IFF) is a crypto identification system designed for command and control. ... Synthetic aperture radar image of Death Valley colored using polarimetry In the broadest sense, remote sensing is the measurement or acquisition of information of an object or phenomenon, by a recording device that is not in physical or intimate contact with the object. ... The surface of Venus, as imaged by the Magellan probe using SAR Synthetic aperture radar (SAR) is a form of radar in which sophisticated post-processing of radar data is used to produce a very narrow effective beam. ... In physical simulations, video games and computational geometry, collision detection includes algorithms from checking for intersection between two given solids, to calculating trajectories, impact times and impact points in a physical simulation. ... // Situation Awareness is a human factors term which of late has become something of a buzzword. ...

 addd work cited!!!!!!! 

--68.160.123.37 22:48, 27 November 2006 (UTC)STAS GROZNYY