Radar detector

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An early radar detector

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 K_a (as well as K_u, in Europe, also recently approved for use in the U.S).

1 Areas where illegal
2 Detecting detectors
3 See also
4 References
5 External links

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.

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.

[edit] Areas where 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 driver who uses a radar detector will pose a greater risk of accident than a driver who does not. Not all research agrees with that premise, such as the 2001 Mori report which suggested that radar detector users on average posed a 28% less risk of accident and also traveled far more miles.

Australia: All states besides Western Australia. They are illegal to sell, purchase or possess in SA, NSW, ACT & Vic. Radar Detectors are illegal to use in NT, Queensland & Tas.^[1]
Belgium: In July 2006 a provisional seisure of a vehicle worth over 75.000 EUR itself was ordered by the courts, destruction of the radar detector itself and the driver's license was suspended for 3 months.^{[citation needed]}
Canada (Illegal:Newfoundland & Labrador, Nova Scotia, Prince Edward Island,New Brunswick, Quebec, Ontario, Manitoba, the Yukon Territory, the Northwest Territories Legal: Alberta, British Columbia, Saskatchewan): Regardless of whether they are used or not, police there may confiscate radar detectors, operational or not, and impose substantial fines.^[2]
Egypt
Estonia
Finland
France
Germany 75€ fine , 4 Points, destruction of the radar detector
Greece
Ireland (Republic of)
Netherlands 250€ fine and seizure of the device (since 2004)
Norway
Poland
Portugal
Spain
Sweden
Taiwan
Turkey
United Kingdom, although not legal to own, but was technically illegal to use under a 1949 wireless act until 1998, due to legal loophole causing them to be legalised suddenly.
United States law varies from state to state, but detectors are generally legal in private vehicles under the Communications Act of 1934^[3] and illegal in commercial vehicles by DOT regulation (49 CFR 392.71). Exceptions:
- Illegal in all vehicles: Virginia, Washington D.C., U.S. military bases
- Illegal in commercial vehicles under state law: Illinois, New York (specifically, commercial vehicles over 10,000 lb. and all vehicles over 18,000 lb.)
- Indirectly illegal: Minnesota and California (illegal to hang anything from the windshield however both dashboard and visor mounting is allowed.) [1]
- Repealed: Connecticut (repealed in 1998)
- Proposed legislation: Florida [2][3]

[edit] Detecting detectors

Main article: Radar detector detector

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 Interceptor.^[4] 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 1990s, 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, practically every radar detector on the market is immune to the VG-2 Interceptor^{[citation needed]}.