An early radar detectorCar radar detector (Japanese)
A radar detector is an electronic device used by motorists to detect if their speed is being monitored by police or law enforcement using a radar gun. Most radar detectors are used so the driver can reduce the car's speed before being ticketed for speeding. In general sense, only emitting technologies, like doppler RADAR, or LIDAR can be detected. Visual speed estimating techniques, like ANPR or VASCAR can not be detected in daytime, but technically vulnerable to detection at night, when IR spotlight is used. There are no reports that piezo sensors can be detected. LIDAR devices require an optical-band sensor, although many modern detectors include LIDAR sensors. Most of today's radar detectors detect signals across a variety of wavelength bands: usually X, K, and Ka. In Europe the Ku band is common as well. The past success of radar detectors was based on the fact that radio-wave beams can not be narrow-enough, so the detector usually senses stray and scattered radiation, giving the driver time to slow down. Based on a focused laser-beam, LIDAR technology does not suffer this shortcoming; however it requires precise aiming. 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. These devices are also often called "radar detectors", while not necessary carrying an RF sensor.
One device law enforcement use to measure the expected speed of a moving vehicle is Doppler radar, which uses the Doppler effect to measure the relative speed of a vehicle. Doppler radar works by beaming a radio wave at a vehicle to then measure the expected change in frequency of the reflected wave (that bounces off the vehicle). Law enforcement often employs Doppler radar via hand-held radar guns, from vehicles, or from fixed objects such as traffic signals.
Radar detectors use a superheterodyne receiver to detect these electromagnetic emissions from the gun, and raise an alarm to notify the motorist when a transmission is detected. 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.
In recent years[when?], some radar detectors have added GPS technology. This allows users to manually store the locations where police frequently monitor traffic, with the detector sounding an alarm when approaching that location in the future (this is accomplished by pushing a button and does not require coordinates to be entered). These detectors also allow users to manually store the coordinates of sites of frequent false alarms, which the GPS enabled detector will then ignore. The detector can also be programmed to mute alerts when traveling below a preset speed, limiting unnecessary alerts. Some GPS enabled detectors can download the GPS coordinates of speed monitoring cameras and red-light cameras from the Internet, alerting the driver that they are approaching the camera.
Counter technology
Radar guns and detectors have evolved alternately over time to counter each other's technology in a form of civilian electronic "warfare". For example, as new frequencies have been introduced, radar detectors have initially been "blind" to them until their technology, too, has been updated. 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. Lastly, radar detectors may combine other technologies, such as GPS-based technology with a point of interest database of known speed trapping locations, into a single device to improve their chances of success.[2]
The superheterodyne receiver in radar detectors 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 10MHz). The VG-2 Interceptor was the first device developed for this purpose, but has since been eclipsed by the Spectre III and Spectre Elite.[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. This technique borrows from ELINT surveillance countermeasures. In the early 1990s, BEL-Tronics, Inc. of Ontario, Canada (where radar detector use is prohibited in most provinces) found that the local oscillator frequency of the detector could be altered to be out of the range of the VG-2 Interceptor (probably by using two local oscillator stages such that neither is near the RF frequency). This resulted in detector manufacturers responding by changing their local oscillator frequency. The VG-2 is no longer in production and radar detectors immune to the Spectre Elite are available.
Radar scrambling
It is illegal in many countries to sell or possess any products that actively transmit radar signals intended to jam radar equipment.[4] In the United States, actively transmitting on a frequency licensed by the Federal Communications Commission (FCC) without a licence is a violation of FCC regulations, which may be punishable by fines up to $10,000 and/or up to one year imprisonment.[5]
Newer speed detection devices use pulsed laser light, commonly referred to as LIDAR, rather than radio waves. Radar detectors, which detect radio transmissions, are unable to detect the infrared light emitted by LIDAR guns, so a different type of device called a LIDAR detector is required. However, LIDAR detection 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 (26m) across at 1,000 feet (300m) from their source, LIDAR's light beam diffuses to only about 6 feet (1.8m).[citation needed] 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. 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 (910m).[citation needed] This has resulted in some manufacturers producing LIDAR jammers. Unlike those of radar, LIDAR's frequencies and use are not controlled by the FCC. These jammers attempt to confuse police LIDAR into showing no speed on the display. They are often successful, and therefore many LIDAR manufacturers produce LIDAR guns that have "jam codes" that show when they are being jammed. They will work against some LIDAR jammers, but not all. In spite of this, police can often tell when they are being jammed when they see no reading on their LIDAR gun. Many jammer-equipped motorists try to counter this by reducing their speed to legal limits before turning off their jammer equipment, a technique known as "kill the equipment", referred to as "JTK" or "Jam to Kill." 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. They will then pull the offending vehicle over and look for LIDAR jammers on the front of the vehicle, potentially ticketing the motorist with an obstruction of justice charge. 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.[citation needed] In these states, the penalties can be severe.
Despite the advent of LIDAR speed detection, radar remains more prevalent because of its lower price and the amount of radar equipment already in service. In addition, proper use of LIDAR equipment requires the officer to remain stationary in order to beam a very precise signal.
Legality
Using or possessing a radar detector or jammer is illegal in certain countries, and it may result in fines, seizure of the device, or both. These prohibitions generally 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.[bettersourceneeded] The table below provides information about laws regarding radar detectors in particular nations. 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.[6]
They are illegal to use in a moving vehicle (as stated by the traffic laws in) SA,[7]NSW, ACT, NT, Queensland and Tasmania. In the state of Victoria it is an offence to sell, use or possess a radar detector, and police may confiscate such equipment if found in a vehicle.[8] Heavy fines apply, ranging from AU$200–$1,700, up to nine demerit points, and confiscation of the radar detector. However, importing a unit is permitted under Australian customs regulations. Queensland = up to 40 penalty units (approximately equal to $3,000) for being in or on a vehicle whether or not the device is operating or in working order. Effective October 12, 2020, heavy penalties for drivers with radar detectors apply in WA.[9]
In July 2006, a provisional seizure of a vehicle worth over €75,000 and destruction of the radar detector was ordered by the courts. The driver's licence was suspended for three months.[11]
Regardless of whether they are used or not, police there may confiscate radar detectors, operational or not, and impose substantial fines in provinces where radar detectors are illegal.[12] Quebec penalizes $500 CAD for use of a radar detector, along with confiscation of the device.[13]
All radar locations in China are reported and published. Map apps on a phone will report the locations. But all speeding and traffic violation radar or camera are electronic police with a police number as well as a human being police. Using a jammer will be considered as obstructing a police and subject to 15 days imprisonment. Radar jammers are also illegal in Hong Kong and Macau.
Illegal to use or have in a motor vehicle on a public road.
The fine depends on income. The detector will be confiscated. For average net income of €2200 /month, the fine would be around €640 plus possible speeding ticket.[15]
Detectors and jammers are illegal to own, use or sell.[10]
Regardless of whether they are used or not, police there may confiscate radar detectors, operational or not, and impose substantial fines. Since 2012, there are also very strict regulations regarding G.P.S. devices which locate speed cameras. Speed cameras must be signaled as "Danger zones" which are precisely 300 meters long in towns, 2km out of towns and 4km on highways.
Use of illegal radar detector is prosecuted €1500 fine & 6 points on driver's license.
According to art. 98, clause 20, it is illegal and a major offence "To use vehicles with unauthorized devices or forbidden by Law, capable of letting users skip random checkpoints or disable police surveillance devices".
Illegal to purchase, use, possess, sell or advertise
Illegal to use or have in possession in a vehicle in traffic, to sell or advertise: an apparatus or any other means of detecting or interfering with operation of vehicle speed measuring devices, or any other apparatus used for discovering and reporting traffic violations[26]
Speed camera guidance, such as by GPS, is legal and very common. Jamming speed cameras is not common in South Korea and it is difficult to find cases of punishment. However, interfering with enforcement wireless devices is punishable under the Radio Act and can be prosecuted as a serious crime.
Effective 1 July 1987, radar detectors used in motor vehicles risked being administratively fined 1200 to 2400 new Taiwan dollars and confiscated. Effective 1 July 2006, radar detectors would no longer be banned in motor vehicles.
Legal, although prior to 1998 the Police would attempt prosecutions under the Wireless and Telegraphy act 1949, laser jammers are still a grey area in the use of them.
Illegal in commercial vehicles under state law: Illinois, New York, New Jersey (specifically, commercial vehicles over 10,000 pounds (4,500kg) and all vehicles over 18,000 pounds (8,200kg)) Also illegal in all commercial vehicles over 10000lbs under US federal law
Illegal when used on the Highway. Prohibitions against affixing items to windshield - "obstructing vision"): Minnesota, California[31]
Confiscation and/or destruction of the detector was once a common practice but lawsuits raised by drivers arguing violation of property rights have resulted in temporary removal while a citation is written, then return of the device after its description (make, model and serial number) has been entered on the ticket - usually for speeding and possession/operation of a detector. Use of a radar/lidar detector on a military installation is prohibited. Persons entering a military installation with one visibly mounted to the sun visor or windshield will be asked to remove it and put it away. Those who refuse will be denied entry onto the installation at that time. Military law enforcement may not stop a vehicle solely for a detector being in use, but along with being stopped for another moving violation, active duty personnel using a detector may be ordered to report the violation to his/her unit commanding officer.
Radar is a system that uses radio waves to determine the distance (ranging), direction, and radial velocity of objects relative to the site. It is a radiodetermination method used to detect and track aircraft, ships, spacecraft, guided missiles, motor vehicles, map weather formations, and terrain.
A heterodyne is a signal frequency that is created by combining or mixing two other frequencies using a signal processing technique called heterodyning, which was invented by Canadian inventor-engineer Reginald Fessenden. Heterodyning is used to shift signals from one frequency range into another, and is also involved in the processes of modulation and demodulation. The two input frequencies are combined in a nonlinear signal-processing device such as a vacuum tube, transistor, or diode, usually called a mixer.
Lidar is a method for determining ranges by targeting an object or a surface with a laser and measuring the time for the reflected light to return to the receiver. Lidar may operate in a fixed direction or it may scan multiple directions, in which case it is known as lidar scanning or 3D laser scanning, a special combination of 3-D scanning and laser scanning. Lidar has terrestrial, airborne, and mobile applications.
A Doppler radar is a specialized radar that uses the Doppler effect to produce velocity data about objects at a distance. It does this by bouncing a microwave signal off a desired target and analyzing how the object's motion has altered the frequency of the returned signal. This variation gives direct and highly accurate measurements of the radial component of a target's velocity relative to the radar. The term applies to radar systems in many domains like aviation, police radar detectors, navigation, meteorology, etc.
This information can then be used to measure velocity or path length, or as a way to learn about the particle or medium's properties. The traveling object may be detected directly or indirectly. Time of flight technology has found valuable applications in the monitoring and characterization of material and biomaterials, hydrogels included.
A radar speed gun, also known as a radar gun, speed gun, or speed trap gun, is a device used to measure the speed of moving objects. It is commonly used by police to check the speed of moving vehicles while conducting traffic enforcement, and in professional sports to measure speeds such as those of baseball pitches, tennis serves, and cricket bowls.
A pulse-Doppler radar is a radar system that determines the range to a target using pulse-timing techniques, and uses the Doppler effect of the returned signal to determine the target object's velocity. It combines the features of pulse radars and continuous-wave radars, which were formerly separate due to the complexity of the electronics.
In electronics, a local oscillator (LO) is an electronic oscillator used with a mixer to change the frequency of a signal. This frequency conversion process, also called heterodyning, produces the sum and difference frequencies from the frequency of the local oscillator and frequency of the input signal. Processing a signal at a fixed frequency gives a radio receiver improved performance. In many receivers, the function of local oscillator and mixer is combined in one stage called a "converter" - this reduces the space, cost, and power consumption by combining both functions into one active device.
VASCAR is a type of device for calculating the speed of a moving vehicle. The first VASCAR device was created in 1966 by Arthur Marshall. It is used by police officers to enforce speed limits, and may be preferred where radar or lidar is illegal, such as some jurisdictions in Pennsylvania, or to prevent detection by those with radar detectors.
A motion detector is an electrical device that utilizes a sensor to detect nearby motion. Such a device is often integrated as a component of a system that automatically performs a task or alerts a user of motion in an area. They form a vital component of security, automated lighting control, home control, energy efficiency, and other useful systems.
A radar detector detector (RDD) is a device used by police or law enforcement in areas where radar detectors are declared illegal.
Road speed limit enforcement in Australia constitutes the actions taken by the authorities to force road users to comply with the speed limits in force on Australia's roads. Speed limit enforcement equipment such as speed cameras and other technologies such as radar and LIDAR are widely used by the authorities. In some regions, aircraft equipped with VASCAR devices are also used.
Moving target indication (MTI) is a mode of operation of a radar to discriminate a target against the clutter. It describes a variety of techniques used for finding moving objects, like an aircraft, and filter out unmoving ones, like hills or trees. It contrasts with the modern stationary target indication (STI) technique, which uses details of the signal to directly determine the mechanical properties of the reflecting objects and thereby find targets whether they are moving or not.
Optical heterodyne detection is a method of extracting information encoded as modulation of the phase, frequency or both of electromagnetic radiation in the wavelength band of visible or infrared light. The light signal is compared with standard or reference light from a "local oscillator" (LO) that would have a fixed offset in frequency and phase from the signal if the latter carried null information. "Heterodyne" signifies more than one frequency, in contrast to the single frequency employed in homodyne detection.
Speed limits are enforced on most public roadways by authorities, with the purpose to improve driver compliance with speed limits. Methods used include roadside speed traps set up and operated by the police and automated roadside 'speed camera' systems, which may incorporate the use of an automatic number plate recognition system. Traditionally, police officers used stopwatches to measure the time taken for a vehicle to cover a known distance. More recently, radar guns and automated in-vehicle systems have come into use.
Video detection and ranging (VIDAR) is a technique to measure the speed or other information of a distant vehicle using advanced stereoscopic imaging techniques. VIDAR technology has application in remote sensing, traffic enforcement.
Lidar has a wide range of applications; one use is in traffic enforcement and in particular speed limit enforcement, has been gradually replacing radar since 2000. Current devices are designed to automate the entire process of speed detection, vehicle identification, driver identification and evidentiary documentation.
Counter-IED equipment are created primarily for military and law enforcement. They are used for standoff detection of explosives and explosive precursor components and defeating the Improvised Explosive Devices (IEDs) devices themselves as part of a broader counter-terrorism, counter-insurgency, or law enforcement effort.
The present weather sensor (PWS) is a component of an automatic weather station that detects the presence of hydrometeors and determines their type and intensity. It works on a principle similar to a bistatic radar, noting the passage of droplets, or flakes, between a transmitter and a sensor. These instruments in automatic weather stations are used to simulate the observation taken by a human observer. They allow rapid reporting of any change in the type and intensity of precipitation, but include interpretation limitations.
↑ "Radar Speed Trap Warning Apparatus (Licence)". Parliamentary Debates (Hansard). 1967-03-02. Retrieved 2010-04-25. a pocket-sized instrument is being produced by Marchant House Limited of New Street, Oadby, Leicester, to be used in motor vehicles to give instant warning of a police radar speed trap ... Anyone wishing to use this type of apparatus would require a licence under the Wireless Telegraphy Act, 1949. The firm in question has recently been informed that I am not prepared to issue a licence for such purposes
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