- Radar detector
A radar detector, sometimes called a fuzz buster, is a passive electronic device used by
motorists to determine if their speed is being monitored by law enforcement agencies via a radarunit, and thereby, potentially avoiding prosecution for speeding. Only doppler radar-based devices can be detected — other speed measuring devices including those using ANPR, piezosensors and VASCARtechnology cannot be detected, while LIDARdevices require a different type of sensor. Most of today's radar detectors detect signals across a variety of wavelength bands — usually X, K and Ka (as well as Ku, in Europe, also recently approved for use in the U.S).
One of the technologies that law enforcement agencies can use to measure the speed of a moving vehicle uses
doppler radarto beam a radio waveat the vehicle, and then infer the vehicle's speed by measuring the Doppler effect-moderated change in the reflected wave's frequency. Radar guns can be hand-held, vehicle mounted or statically mounted.
Radar detectors use a
superheterodyne receiverto detect these electromagnetic emmissions from the radar gun, and raise an alarm to notify the motorist when a transmission is detected. False alarms can occur however due to the large number of devices, such as automatic door openers, that operate in the same part of the electromagnetic spectrumas radar guns.
Radar guns and detectors have evolved alternately over time to counter each other's technology in a form of civilian electronic "warfare". For example, as new frequencies have been introduced, radar detectors have initially been "blind" to them until their technology too has been updated. Similarly, the length of time and strength of the transmissions have been lowered to reduce the chance of detection, which in turn has resulted in more sensitive receivers and more sophisticated software counter technology. Lastly, radar detectors may combine other technologies, such as
GPS-based technology with a point of interestdatabase of known speed trapping locations, into a single device to improve their chances of success.
Radar Detector Detectors
superheterodyne receiverin radar detectors have a local oscillatorthat radiates slightly, so it is possible to build a radar-detector detector, which detects such emissions (usually the frequency of the radar type being detected, plus about 10 MHz). The VG-2 Interceptor was the first device developed for this purpose, but has since been eclipsed by the Spectre III. [ [http://radar.757.org/VG2.htm Radar Detector Detector (RDD)] ] This form of " electronic warfare" cuts both ways - since detector-detectors use a similar superheterodyne receiver, many early "stealth" radar detectors were equipped with a radar-detector-detector-detector circuit, which shuts down the main radar receiver when the detector-detector's signal is sensed, thus preventing detection by such equipment. This technique borrows from ELINTsurveillance countermeasures. In the early 1990s, BEL-Tronics, Inc. of Ontario, Canada (where radar detector use is prohibited) found that the local oscillator frequency of the detector could be altered to be out of the range of the VG-2 Interceptor. This resulted in detector manufacturers responding by changing their local oscillator frequency. Today, practically every radar detector on the market is immune to the VG-2 Interceptor.Fact|date=February 2007
Although some companies advertise that their radar detectors can passively 'scramble' or 'absorb' radar and LIDAR (such as Rocky Mountain Radar), many or all of their products do not affect radar and laser equipment due to the low power intake from the device versus the high power that bounces off a vehicle. [ [http://www.radarjammer.com/most-fail/passive-jammers.htm Passive Radar Jammers] ]
It is illegal in many countries to sell or possess any products that actively transmit radar signals intended to jam radar equipment. [ [http://www.radarjammer.com/its-a-felony/fcc-jammer-ban.htm FCC Ban] ] Actively transmitting on an
FCClicensed frequency without a license is a violation of FCC regulations and a felony in the USA.
Newer speed detection devices use pulsed
laserlight, commonly referred to as LIDAR, rather than radio waves. Radar detectors, which detect radio transmissions, are therefore unable to detect the infraredlight emitted by LIDAR guns so a different type of device called a LIDAR detectoris required. LIDAR detection, however, is not nearly as effective as radar detection because the output beam is very focused. While radar's radio waves can expand to convert|85|ft|m across at convert|1000|ft|m from their source, LIDAR's light beam diffuses to only about Convert|6|ft|m.Fact|date=July 2008 Also, a police officer targeting a car will most likely aim for the center mass or headlight of the vehicle and, because radar detectors are mounted on the windshield away from the beam's aim, they may not alert at all. Lastly, with such a focused beam, an officer using a LIDAR gun can target a single car in close proximity to others at ranges of up to convert|3000|ft|m.
Despite the advent of LIDAR speed detection, radar remains more prevalent because of its lower price relative to LIDAR equipment and the amount of radar equipment already in service.
Using or possessing a radar detector or jammer is illegal in certain countries, and it may result in fines, seizure of the device, or both. These prohibitions generally are introduced under the premise that a driver who uses a radar detector will pose a greater risk of accident than a driver who does not. However the [http://driverstechnology.co.uk/Morisurvey.pdf 2001 Mori report] suggests that radar detector users posed a 28% less risk of accident. The table below provides information about laws regarding radar detectors in particular nations.
Traffic enforcement camera
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Look at other dictionaries:
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