About Radar Detectors

You're speeding down the highway, going a few miles above the posted limited, when suddenly you hear a siren and see red and blue lights flashing in your rearview mirror. You've just been busted for speeding. To prevent this scenario, many people turn to radar detectors. These little devices provide an early warning when radar traps are ahead.

Function

A radar detector is a small electronic device used in cars and other passenger vehicles to determine whether the vehicle's speed is being monitored via radar by a police officer. If the vehicle's operator gets an early warning that there's a radar trap ahead, he can slow and potentially avoid getting a speeding tickets. Radar detectors work by employing a superheterodyne receiver that detects electromagnetic emissions from the radar gun. When they detect a transmission, it triggers an alarm to warn the driver that a radar trap is in close proximity.

Features

Virtually all modern radar detectors can detect signals across the most widely used wavelength bands. They are continually updated as law enforcement technology is improved. For example, to make detection more difficult, the time and strength of modern radar gun transmissions has been lowered. Manufacturers of radar detectors responded by making their devices more sensitive. Most are also immune to the devices used by police to detect radar detector users. However, this sensitivity can also lead to false alarms. A radar detector's alarm may be triggered by other devices, such as automatic garage door openers. This is because such devices often use the same part of the electromagnetic spectrum that radar guns do.

Misconceptions

Some drivers view a radar detector as a free pass to disregard speed limits However, these devices are far from 100 percent effective. Radar detectors don't work with every type of radar monitoring that a motorist may encounter, and they're totally useless against other technologies such as LIDAR, which uses light waves rather than radar to calculate speed. Typical radar detectors can only detect doppler radar-based devices. Law enforcement officers might use a variety of other speed measuring devices, such as ANPR, piezo sensors and VASCAR technology, none of which can be detected by a standard radar detector.

Prevention/Solution

As law enforcement technically morphs and changes, radar detectors have to change along with it in order to remain effective. In addition to evolving technologically to match advances in radar speed detection, radar detectors are beginning to combine other technologies in order to boost their effectiveness. For example, some units incorporate a GPS system and database of known speed trap locations.

Warning

Although radar detectors are legal in private vehicles in most parts of the United States, they are forbidden in some areas. For example, they are illegal to use in any vehicle in Virginia and Washington D.C. and on all United States military bases. Some states try to stop the use of radar detectors through the use of indirect restrictions. For example, states such as California, Minnesota and New Work have laws again affixing objects in a vehicle's windshield or obstructing the driver's vision. Thus, even though the detector itself is technically legal, a police officer might judge that it is an illegal obstruction.