article

A radar detector is an electronic device used by motorists to determine if their speed is being monitored. The term originates from early speed-detection technologies, in which police bounced a radio wave off a moving vehicle with a device called a radar gun that determined the vehicle's speed by the Doppler-effect-moderated change in the wave's frequency. Most of today's radar detectors detect signals across a variety of wavelength bands - usually X, K, and Ka bands (and Ku, in Europe, also recently approved for use in the U.S).

Newer speed-detection technology uses pulsed laser light (LIDAR, commonly referred to as laser detection) rather than radio waves. Modern "radar detectors" have been adapted to suit that technology, by detecting the infrared light emitted by these new detection methods. LIDAR detection is not nearly as reliable as the detection of radar, since the light is much more focused and often aimed below the windscreen level, where the detector is usually mounted. (The reflective coating of the vehicle licence plate is an excellent laser beam reflector.)

There are many products that are advertised to claim to "scramble" or "absorb" radar; many of these scrambler devices do not work at all, and if they do work, it is by emitting an active radar scrambling pulse, which makes the device illegal to operate under in many jurisdictions. There are also lidar jammers that are currently legal throughout most of the US, some Canadian provinces and other countries. Lidar jammers, like police lidar guns are regulated by the FDA for eye safety as Class I devices. They operate on the principle of destructive interference to "jam" most lidar guns in most circumstances. Finally, there is a stealth coating available from Veil designed to attenuate police lidar reflection and make it harder for police lidar guns to obtain a speed reading, allowing for additional warning time from a radar detector's laser alert in most circumstances. It is normally applied to the front license plate and headlights which are the primary target locations for a trained lidar gun operator as they are the most reflective areas of an automobile.

Despite the advent of LIDAR speed detection, radar remains more prevalent for several reasons, not the least of which are the lower costs of radar (although some insurance companies supply laser guns to police departments for free) and total amount of radar equipment in historical service. Popularity of LIDAR speed detection is on the rise, though, as costs decline and ease of operability approach radar; existing radar guns reach their end-of-service life; and they are rotated out of service replaced with newer technology. LIDAR also has the advantage of being able to be used in higher traffic density areas (ie; crowded multi-lane highways of major cities) where conventional radar guns have trouble isolating a single vehicle's speed.

Popular radar detector brands include Beltronics, Cobra, Escort, K40, Valentine One, and Whistler.

Countries and areas where radar detectors are illegal

In some countries and areas, such as those listed below, using or possessing a radar detector is declared illegal and may result in fines, seizure of the device, or both. Generally these prohibitions are introduced under the premise that a radar detector driver will pose a greater risk of accident than a driver who does not. However all research on the subject has proven otherwise, such as the 2001 Mori report which showed that radar detector users on average posed a 28 % less risk of accident and also traveled far more miles.

Detecting Detectors

Because RADAR detectors are built around a superheterodyne receiver, which has a local oscillator that radiates slightly, 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). Some police radar guns are equipped with such a device, typically a VG-2 InterceptorRadar Detector Detector (RDD). This form of electronic warfare cuts both ways and since detector-detectors use a similar superheterodyne receiver , many early "stealth" radar detectors are 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 ELINT surveillance countermeasures. In the early 1990's, BEL-Tronics, Inc. of Ontario, Canada (where radar detector use is prohibited) found that merely the local oscillator frequency of the detector could be modified out of the range of the VG-2 Interceptor. This resulted in a wave of detector manufacturers changing their local oscillator frequency, with the notable exception of Whistler who continues to use the older "radar detector detector detector" approach. Today, almost every radar detector on the market is immune to the VG-2 Interceptor. However, a new radar detector detector is on the market, one that can be updated quickly to thwart any LO-shifting schemes of the detector makers. This device is produced by Stealth Micro Systems, Pty of Queensland, Australia. Called the Stalcar in Australia and the "Spectre" elswhere, this is the current leader in RDD technology. These devices will pick up any series-production radar detector on the road. To combat this new threat, Beltronics Inc. has come up with a new design of radar detector, the STI Driver. It remains to be seen if this new detector will be able to be detected at distance by a new type of RDD.

See also

References

Consumer electronics | Traffic law | Radar

Tutkanpaljastin | レーダー探知機

 

This article is licensed under the GNU Free Documentation License. It uses material from the "Radar detector".

Home Page • arts • business • computers • games • health • hospitals • home • kids & teens • news • physicians • recreation• reference • regional • science • shopping • society • sports • world