Radar
hideRadar is an object detection 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. The term RADAR was coined in 1941 as an acronym for radio detection and ranging. The term has since entered the English language as a standard word, radar, losing the capitalization. Radar was originally called RDF (Radio Direction Finder, now used as a totally different device) in the United Kingdom.
A radar system has a transmitter that emits microwaves or radio waves. These waves are in phase when emitted, and when they come into contact with an object are scattered in all directions. The signal is thus partly reflected back and it has a slight change of wavelength (and thus frequency) if the target is moving. The receiver is usually, but not always, in the same location as the transmitter. Although the signal returned is usually very weak, the signal can be amplified through use of electronic techniques in the receiver and in the antenna configuration. This enables radar to detect objects at ranges where other emissions, such as sound or visible light, would be too weak to detect. Radar is used in meteorological detection of precipitation, measuring ocean surface waves, air traffic control, police detection of speeding traffic, and by the military.
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News tagged with radar
Britain shuts down UFO-hunting unit
Dec 04, 2009 |
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The British government has shut a unit which has investigated UFO sightings for more than 50 years, judging its resources better spent on more earthly threats, it said Friday.
First phase of pan-tropical forest mapping debuting at COP15
Dec 10, 2009 |
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Tropical forest loss accounts for an estimated 17% of global emissions of carbon dioxide. As part of a strategy to reduce these greenhouse gas fluxes to the atmosphere, the UNFCCC's Conference of the Parties 15 in Copenhagen ...
New algorithms for computerized, large-scale surveillance
Dec 02, 2009 |
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A recent AFOSR-funded technology should enable the Air Force to achieve advances in object and target detection technology by using sophisticated algebraic theories called groups, rings and fields.
Researchers patent enabling technology for spread-spectrum systems
Nov 17, 2009 |
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If you've ever gotten the dreaded "network busy" message while trying to make a cell phone call, you've experienced the complication of sharing a single network with numerous other users.
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New radar helps monitor site of century-old tragedy
Space & Earth / Earth Sciences
Nov 27, 2009 |
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(PhysOrg.com) -- A University of Alberta researcher has turned the site of a southern Alberta rockslide tragedy into the proving ground for new equipment meant to avert such a disaster in the future.
Forest deal at Copenhagen must avoid creating 'carbon refugees'
Dec 03, 2009 |
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Forest dwellers must be included in the design of the upcoming forest deal at Copenhagen in order to avoid a humanitarian crisis, according to a scientist at the University of Leeds.
Facebook users can help Chase find small charities
Nov 18, 2009 |
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(AP) -- JPMorgan Chase is letting Facebook users help decide how to give away $5 million.
TRMM sees 05B winding down off the Sri Lanka coast
Space & Earth / Earth Sciences
Dec 14, 2009 |
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Tropical Depression 05B is dissipating on the east coast of Sri Lanka today and over the next couple of days, but not before bringing some moderate and heavy rain over the next couple of days to some areas ...
Tropical Cyclone Laurence menaces Northern Australia
Space & Earth / Earth Sciences
11 hours ago |
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Laurence is still a tropical cyclone even though the storm has made landfall in northern West Australia and is moving over land. The Tropical Rainfall Measuring Mission (TRMM) satellite noticed some powerful ...
NASA Global Precipitation Measurement Mission Passes Major Review
Space & Earth / Space Exploration
Dec 08, 2009 |
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(PhysOrg.com) -- NASA's effort to deploy the first satellite mission to advance global precipitation observations from space moved closer to this goal when agency officials approved critical elements for the Global Precipitation ...
New Automated Technique with Online Verification Eases Network Analyzer Calibration
10 hours ago |
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Verifying the accuracy of network analyzers—instruments that are used to measure key performance characteristics of electronic networks—was once an awkward process involving multiple steps and pieces of equipment.
UK police make 2 Trojan computer virus arrests
Nov 18, 2009 |
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(AP) -- A couple suspected of helping spread some of the Internet's most aggressive computer viruses has been arrested in the English city of Manchester, police said Wednesday.
Burned out, depressed surgeons more likely to commit more major medical errors
Nov 23, 2009 |
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Surgeons who are burned out or depressed are more likely to say they had recently committed a major error on the job, according to the largest study to date on physician burnout. The new findings suggest that the mental well-being ...
Winds drive icebergs away from New Zealand
Space & Earth / Earth Sciences
Dec 01, 2009 |
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(AP) -- Strong westerly winds in the southern Pacific Ocean have driven scores of icebergs originally headed toward New Zealand to the east, away from the country, an oceanographer said Tuesday.
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