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Radar Detectors and Laser Detectors
Radar Detectors
A radar detector is an electronic device used by motorists
to determine if their speed is being monitored by a radar
unit. To do so, police bounce a radio wave off of a moving
vehicle with a radar gun or other radar device that
determines 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 (as well as Ku, in
Europe, which was also recently approved for use in the
U.S.).
These devices should not be confused with LIDAR detectors
and jammers, or GPS-based warning systems that use a speed
camera Point of Interest database to warn a driver who is
approaching a speed camera location.
Laser Detectors
Newer speed detection devices use pulsed laser light, commonly referred to as
LIDAR, rather than radio waves. Modern radar detectors have been modified to
alert to the infrared light emitted by such LIDAR guns. 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 85 feet across at 1000
feet from their source, LIDAR's light beam expands to only about 6 feet. 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 3000 feet.
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. A severe limitation of LIDAR is that it cannot be
used while the police car is in motion, because it requires the operator to
actively target each target vehicle whereas traditional radar can be operated
while the police officer is driving his car. Popularity of LIDAR speed detection
is on the rise and is replacing radar use.
Radar Scrambling
Although some companies
advertise that their radar detectors can 'scramble' or 'absorb' radar and LIDAR
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.
In the USA, it is illegal to sell or possess any such products that transmit
radar signals intended to jam radar equipment. LIDAR jammers are legal in most
states and are regulated, much like police LIDAR guns, by the FCC as Class I
laser devices.
Detector Detectors
RADAR detectors are built around a superheterodyne receiver, which has a
local oscillator that 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. 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. Today, practically every
radar detector on the market is immune to the VG-2 Interceptor.
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