Radar detector

Modern police radars incorporate formidable computing power, producing a minimum number of ultra-short pulses, reusing wide beams for multi-target measurement,[1] which renders most detectors useless.

But, mobile Internet allows GPS navigation devices to map police radar locations in real-time.

False alarms can occur however due to the large number of devices, such as automatic door openers (such as the ones at supermarkets and drug stores), speed signs, blind spot monitoring systems, poorly designed radar detectors and adaptive cruise control, that operate in the same part of the electromagnetic spectrum as radar guns.

Radar guns and detectors have evolved alternately over time to counter each other's technology in a form of civilian electronic "warfare".

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.

[3] 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.

[5] Newer speed detection devices use pulsed laser light, commonly referred to as LIDAR, rather than radio waves.

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 3,000 feet (910 m).

Officers can often detect this by observing that their LIDAR equipment is unable to lock in a speed properly, along with visual indication of sudden deceleration of the targeted vehicle.

Some states also have laws against jamming of police radar or LIDAR: California, Colorado, Illinois, Iowa, Minnesota, Oklahoma, South Carolina, Tennessee, Texas, Utah and Virginia.

In addition, proper use of LIDAR equipment requires the officer to remain stationary in order to beam a very precise signal.

In 1967 devices to warn drivers of radar speed traps were being manufactured in the United Kingdom; they were deemed illegal under the Wireless Telegraphy Act 1949.

Eleven states specifically ban laser jammers: California, Colorado, Illinois, Iowa, Minnesota, Oklahoma, South Carolina, Tennessee, Texas, Utah, and Virginia.