Glossary of Terms - Laser / Gatso / Radar Detectors
See Also ' Methods of Detection ' (below)
Radar stands for R adio D etecting A nd R anging.
The system operates by transmitting radio waves at certain frequencies which reflect off objects and are picked up by the receiver. When the beam reflects off a moving object, a measurable frequency shift occurs which is then converted into miles per hour to determine the object's speed.
There are 3 main sets of frequencies used by the manufacturers of speed trap equipment. These are known as X, K & KA. The majority of traps use K band (e.g. GATSO cameras and most hand held guns). X band is the oldest and is used by some older gun based systems, it is also the band where most false alarms occur since other pieces of equipment use this frequency range. KA band is used by the new 'Stalker' radar guns and is one of the most popular, having been extended twice since 1991.
GATSO is the name given to the Dutch made "photographic trap" system used in the UK and Europe. The GATSO traps are unmanned and take a photo of the rear of the speeding vehicle. GATSO traps operate on K band and are therefore detectable by most good detectors. The majority of GATSO cameras are inactive - the average ratio is one "live" camera site for every ten boxes. Even "inactive" sites will appear to take photographs of passing vehicles by flashing at them, but since no photographic equipment is installed no photographs can be taken. If the GATSO system is fully loaded it is transmitting K band signals constantly monitoring the speed of every vehicle that passes.
The laser speed Detection System uses a gun that emits infrared light pulses just outside the spectrum of visible light. Each pulse measures the distance to any object that reflects the laser. The speed of the object coming towards the gun is measured using a very narrow beam of light so
that it can pinpoint a speeding car in the traffic. A radar detector will pick up the signal due to "splattering" caused by the beam hitting warm and cold pockets this "splattering" makes the beam appear much wider.
VG-2 is a microwave receiver used by some police forces to detect signals radiated by the local oscillator of a radar detector, because of this VG-2 has become known as a 'radar detector' detector. It is primarily used to identify radar detector equipped vehicles, as, in the past drivers
faced losing their detector if caught. VG-2 immunity prevents electronic detection of your unit.
VASCAR is an acronym for Visual Average Speed Computer And Recorder. This is little more than a glorified stopwatch, whereby the vehicle is timed over a set distance (for example over two white markings in the road surface or over two bridges) an average speed is then automatically calculated. No radio waves or beams of light are emitted and thus this system is unable to be detected by any form of electronic detector.
Radar Facts
RADAR: Acronym for RAdio Detection And Ranging. A remote sensor that emits electromagnetic waves on order to measure reflections for the purpose of detection
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X Band Radar : Frequency tolerance 10.525 GHz25 Mhz Frequency range 10.500-10.550 GHz. X band Radars have been around since the 1960s and operate on a single frequency. Typically their operational range was 20 mph- 90 mph or more. U.K. and Australia ceased using X Band Radar many years ago when the frequency was licensed out to other industries that required access to Microwave transmitters (alarm systems etc.).
K Band Radar: Frequency Tolerance 24.150 GHz100Mhz Frequency Range 24.050-24.250 GHz. K Band Radars have been around since the 1970s and operate on a single frequency. With K BAnd operating in the limits of the water vapour absorption band (centred at about 22.24 GHz) signals in the absorption band tend to become absorbed by moisture in the atmosphere and do not have the range that other frequency bands offer. Primarily this is why the FCC allocated this frequency for short range Police use. The most well known Radar devise operating on this frequency is the HAWK.
Ka Band Radar: The available bandwidth allocated to Ka Band traffic radar is 2.6 GHz operating between 33.4GHz-36GHz. Most Ka traffic radar have a frequency tolerance of 100Mhz (200MHz band width). Therefore 2.600 MHz (available band width) divided by 200MHz (Channel Bandwidth) equals 13 channels. A traffic radar in the Ka band with a frequency tolerance of 100MHz may have more channels, but some or all the channels will overlap. Some models transmit on a single frequency only. Others may allow the operator to select one of the several fixed frequencies. Some can hop from one frequency to the next in a Phase Loop.
The Doppler Principle: Everyday life has a multitude of examples of the Doppler effect with sound. The whistle from a train is a good example. As the train approaches a stationary listener, the pitch (frequency) of the whistle sounds higher than when the train passes by, at which point the train and the person standing are technically stationary.
Electromagnetic waves radiated by the traffic radar obey the same principle, although electromagnetic waves travel at the speed of light and audio waves at the speed of sound. The Doppler Effect that enables police radar to work is a frequency shift that results from relative motion between a frequency source and the listener. The Doppler shift is proportional to speed between source and listener, frequency of source, and the speed the waves travel at (speed of light for electromagnetic waves).
Instant ON (Pulse Radar): Intended to defeat radar detectors. Instant ON radar allows the operator to control the radar transmission. The operator only transmits after selecting the target, and only long enough to get a speed reading. In practice most police find this a difficult mode to operate in and are more likely to have the radar on all the time unless two officers are present in the car, one driving and one working the radar.
Cosine Effect on Moving Radar: Moving Radar measures closing speed between the radar and target. The radar also measures patrol car speed (from the ground echo) to calculate the target speed. (Target speed=closing-patrol car). This introduces additional sources of cosine error. In most situations the angle between the radar and target is the major error source and favours the target (measure too low). However if the antenna is misaligned (off patrol car direction) the patrol car speed may measure low resulting in target speed measured too high.
Moving Radar Variables: Target speed will only measure higher than true speed when the target is approaching the patrol car AND the cosine angle between radar and target are small, (typically less than 5%) AND the angle between the patrol car and the ground is large, (typically greater than 5%). Patrol car and target speeds are significant, patrol car speed greater than target speed increases the error. (The greater the difference the larger the error and the higher the measured speed).
Shadowing: Radars identify ground echoes as the strongest signal (most of the time). The ground echo cosine angle is a function of the radar antenna alignment and beam width. More reflective terrain in only part of the beam could change the angle of the ground return (shadowing) which can change the measured speed of the patrol car. Large and or reflective objects such as overpasses or billboards and road signs may have a momentary effect on radar. Guard-rails, bridge trusses and construction zones may have a longer effect.
Ka Band Radar: Photo Radar: Automatic unattended photo radar started appearing in the late 80s and came to U.K. in 1993. With Photo radar systems a human operator does not observe any speeding violation, but is replaced by electronic circuits and a photo recording device. No one has to see the alleged violation; the process is automatic. The registered owner of the vehicle usually receives a ticket in the mail. Photo radar is across the road radar and designed to point a narrow beam of radar (typically 5 degree horizontal beam width) across the road at an angle of 22.5 degrees. Speed measurement is then adjusted for the angle.
Some units operate with an amber (orange) flash filter. This is not as bright to the human eye and causes minimum disruption to a driver even at night.
Power output is very low (2.5mW typically) which makes detection for radar detectors difficult, but not impossible.
How Laser Guns Work
The word Laser actually stands for "Light Amplification by Stimulated Emission of Radiation." It is a form of electromagnetic radiation the same as radio and microwaves. The difference is that light has a much higher frequency than radio or microwaves.
The light emitted by a laser is no different than any other source except that it has a unique method of generating light. The type of laser used is an infrared semiconductor laser diode. The generated light energy has a wavelength of approx. 900 nanometers, with a beam divergence of 3 milliradians, equal to a beam width of about 3 m (or ft) at 1000 m (ft). Target acquisition times range from 0.3 to 0.7 seconds.
This laser is completely eye safe, meeting FDA Class 1 specifications. This means that you could stare directly into the laser for 3 hours without any harm to your eyesight. The radiated light power on MOST lasers is in the order of 50 micro watts, or in other terms, it outputs only one twentieth the light power of a typical TV remote control, and far less than a flashlight.
Which is why Diffusers using industry standard laser LED diodes are effective against laser guns.
The products calculate distance by measuring the time of flight of very short pulses of infrared light. This method is different from the traditional surveying instrument method of measuring phase shifts by comparing the incoming wavelength with the phase of the reflected light. Any solid object will reflect back a certain percentage of the emitted light energy - it need only be small for the sensitive detector to pick it up. The guns measure the time it takes a laser pulse to travel to the target and back with a precision, crystal-controlled time base. Knowing the speed of light, you then calculate the distance travelled. To increase accuracy, the laser measures as many as sixty pulses, utilizing a least squares method of determining the range. Sophisticated error trapping algorithms are in place to ensure a reliable reading.
However Diffusers generate an off phase pulse which infills the phasing cycle of the laser guns making them easy to defeat.
LIDAR: Laser Radar as it's sometimes called. LAser Detection And Ranging, or LIDARS (LIght Detection And Ranging). These systems radiate in the upper infrared 9IR) band and have extremely low beams compared to radar. Very fast to establish your speed and with high accuracy. Laser is a real challenge for detectors.
You should avoid products without Laser detection built in (Q4000 Whistlers and old two band radar detectors). Competent Radar and Laser detectors can detect laser up to 3 km away in the right circumstances. Operational effective range for laser is around 800 metres. It's just too hard for an operator to stabilise a target much beyond this distance.
'Methods of Detection'
The Metropolitan Police Services use several methods for the detection and prosecution of speeding drivers:
Hand held speed detection guns using either radar or laser technology.
- Truvelo – a system that requires two ‘wires’ to be fixed to the road which detect the speed for display on a piece of equipment nearby.
- Automatic Camera Technology – GATSO etc.
- Police Pilot.
- In car video cameras (linked to Police Pilot).
The following provides a detailed list of all current technologies known and in use by Police forces in the UK.‘The primary object of camera detection devices is deterrence’, Metropolitan Police.
Click on one of the links below:
Radar Detection
Laser Detection
Digital Camera
Legal Police Devices
Radar Detection
Radar is an acronym for radio detection and ranging. It works by emitting a ‘blip’ of ultra-high radio waves, which bounce off the target and arrive back at the radar. By comparing the difference in wavelengths the radar can work out the speed of the vehicle. It’s called the Doppler effect
THE STATIONARY GATSO AUTO SPEED DETECTION CAMERA
Also known as FIP (Fixed Installation Post/Position)
GATSO cameras are designed to photograph speeding motorists, thus freeing up valuable police resources This can be done in two ways: Two photos are taken, each 0.9 seconds apart, by using piezo-electric strips embedded in the road (Truvelo). Detecting your wheels over the strips at a known distance apart, the time it takes between the two strips is measured which gives the speed (speed equals distance divided by time)
Another way is to use radar checking the speed of a vehicle within a certain range. By emitting suitably high-frequency radio waves they can bounce these from the vehicle and the rate-of-change of distance is detected by a frequency shift from the reflection. If this rate-of-change is higher than the rate-of-change for the speed limit, you’re caught 70% of all points deducted from licence's are from this method of detection.
Photographs rear of vehicle.
Majority of sites are inactive.
Police forces use only two bands for speed monitoring K band for radar and laser (infra-red). K band is the radar frequency where GATSO cameras (plus portable mini GATSO system) and hand held radar, are broadcast, therefore detectable by radar detectors
The next generation GATSO is being made to work off inductive loops under the road like the RLCs. The reason is simply to prevent the new generation of radar detectors.
The cost for one GATSO is £35,000.
THE DOUBLE-SIDED GATSO
This is a derivative of the fixed-installation post as described above.
The difference is that the camera box is mounted in the central reservation of a road instead of at the side.
RED LIGHT GATSO
Known as the Red Light Camera (RLC) they are positioned between 12 and 20 meters before the stop line. The state of the signals is monitored and the device is armed when the red light is illuminated. When the vehicle crosses the stop line against the red light it passes over loops situated under the road surface just past the stop line
When the light turns red, the loop is powered up, and anything passing over it triggering the camera which takes two photographs
One is taken immediately and one a second later to show the passage of the vehicle through the signals.
The date and time of the offence, together with the time that elapses after the red light is illuminated, are recorded onto the film
Two photographs are taken so there is manual confirmation for the officer examining the film later.
The camera also records data regarding the amber light so that the correct sequence of the lights can be proved
In addition the camera monitors the speed of the vehicles as they cross the stop line.
Recent changes mean that some of these RLC (which are in a smaller box) are having radar’s fitted so they become speed cameras when the lights are green or amber, and red-light cameras when the lights go red
MUNIQUIP
Hand held radar.
Radar sees over a wide angle until the automatic gain control kicks in when a target appears.
Unit displays the speed.
Expect to be stopped above 5%.
Used in K-band frequency.
MULTANOVA
6F–2 and 9F radar based systems.
Pole or box mounted, mobile or built in to a vehicle but are mostly used as mobile traps set up on Motorway bridges.
6F –2 takes 4 or 5 speed readings before taking a photo and shoots 3 pics per second.
9F system can further determine vehicle type.
Both units can be front and rear facing and look like miniature rocket launchers.
They are shielded to prevent external interference and, because of the highly targeted radar beam, are invisible to over-the-counter radar detectors.
VG2
Interceptor VG-2 microwave receiver used to detect signals radiated by local oscillator of a radar detector.
Reputed to be “Radar Detector Detector” used to identify radar detective equipped vehicles.
Most new radar detectors have anti GV-2 features which stop electronic detection.
In use USA, Canada, France and Switzerland.
SWS
Safety radar produced as a way of combating the “irresponsible” image of radar detectors.
Installed in US police cars owners of equipped radar detectors receive warning in advance of dangerous situations i.e. Roadside accident or poor road conditions.
Scheduled to appear early next year.
Laser Detection
Laser speed detection system, unlike radar, signals the output in a narrow beam of light and can therefore pinpoint a car through a telescopic sight, which can fix a target 900 m away. Light amplification by stimulated emission radian works on the same principle as radar – a beam of infra-red laser light is emitted, the time taken for its return calculated and compared with next reading.
MAROM
Another new system entering service after trials, Marom uses electro-optic and infra-red technologies.
Automated, lane-based traffic system that measures speed and distance between vehicles travelling in a given lane.
Every vehicle passing between the electro-optic head and retro-reflectors breaks the two beams and triggers computer to measure speed, acceleration, headway and vehicle length.
Operates 24 hours in all weather and lighting conditions.
If any vehicle exceeds any present parameters the high resolution digital cameras photograph front and rear of vehicle, and all violation data are stored on digital audio tapes.
These are relayed to a Data Processing Unit which, when connected to DVLA computers in Swansea, can automatically process unlimited numbers of notices per day.
Can be deployed at roadside, mounted or on overhead structures, permanently or temporarily, or used from a parked vehicles
Technology immune to countermeasures like radar and laser detectors.
AUTO VISION
Portable Auto Vision is a video-based system that superimposes speed/time/distance information on a video image.
Linked to a laser, the system is placed in a unmarked van and is aimed at the front of the car.
Costs £10,500 compared to £33,00 for a single GATSO, which makes it an increasingly popular choice.
SPEED VIOLATION DETECTION DETERRENT
Digital infra-red cameras photograph cars passing two fixed points.
Average speed worked out.
VASCAR
Visual Average Speed computer and recorder (Police Pilot).
Glorified stopwatch from unmarked police car.
Works by calculating your speed between two set points. This means the police may need to follow you for miles before two suitable markers appear by the side of the road.
No radio waves or beams of light emitted therefore unable to be detected.
Work for 7 days and then deactivate and won’t work until they’ve been recalibrated.
A question mark hangs over speeding convictions after James McDonald, who was fined £350, appealed to the High Court arguing that the speed detection system did not appear on a list of prescribed devices approved by the Secretary of State for Scotland in the Road Traffic Offenders Act 1988, and evidence from it was therefore inadmissible. Before the case could be heard the prosecution agreed to the setting aside of the conviction (The Telegraph, Richard Savill, 2 August 1999).
Cost £120 000
Only used in daylight or well lit areas as needs good visibility.
Digital Camera
This system does not use instantaneous speed like the cameras we’re all familiar with. Instead the camera measures the average speed of every vehicle over the distance of about a mile. Images of speeding bikers and drives are sent down phone lines to a central police camera and notices for three points and a £40 fine can be sent straight away. Cameras are moved at regular intervals. The equipment will initially be expensive but cheaper to run. The ‘Super GATSO’ will be added to the present 1500 already in use.
SPEEDCHECK (SVDD)
Sure way Video Detection Device similar to GATSO.
SVDD costs £120,000 each to install.
Deploys cameras either end of a measured baseline (up to 500metres) to monitor vehicles 24hrs.
Using ‘machine vision’, vehicle number-plates are read and the time of each observation recorded. As the vehicle passes the second camera, the number-plate records are matched, and an average speed for the vehicle is calculated. If it’s above the trigger speed, the vehicles registration is recorded along with it’s speed.
Speedcheck check, therefore, measures average speed over know distance which SVVD say imposes a smoother flow of traffic which eliminates slow-fast driving provoked by GATSO cameras.
Illuminated sign flashes further down the road to driver into slowing down.
Automatically records the date, precise time, location and speed of the offending vehicle, along with a full colour image of the front of the vehicle, which clearly records number plate, make, model and even the colour.
No film, no radar, 99% accurate in almost all weather conditions, 24 hours.
Because it’s automated it’s self-sufficient.
If hooked up to DVLA computers, SVVD system automatically processes fines and sends out notices in the post.
Director Dave Robertson claimed SVVD would cut speeding by 30% plus.
SPECS
‘The proposed introduction of the scheme nation-wide follows successful trials in Kent and Leicestershire which have resulted in a 30% reduction in recorded speeding offences’ (Gateshead Post, 28 October 1999).
Twin digital technology cameras capture vehicle registration number and flash on to huge roadside screen whilst simultaneously issuing a warning to the shamed driver to slow down without involving any police manpower.
Equipment inexpensive and virtually maintenance free because it uses digital technology.
Transmits offending registrations instantly to DVLA at Swansea where they are recorded. Three hits and drive likely to face automatic prosecution.
Low cost way of tracking registrations wanted by police which it is programmed to recognised.
Automatically alerts nearest patrol car via satellite navigation.
RACAL
“Big Brother” surveillance cameras – reads car number plates regardless of speed and at night convert them to computer data
DVLA setting up nation wide network to spot untaxed cars, data shared with police.
Expanding network makes finding or tracking any vehicle in Britain by tapping registration number into a computer thus movements will be tracked and logged on computer.
Automatic number-plate recognition is exclusively an image processing technology. It clearly has a number of applications on the periphery of the road space management task, including criminal investigations and access control for certain areas. But apart for the speed warning application there are other traffic management uses or potential uses of vehicle identification.
Speeding tickets issued automatically based on times between cameras and tolls.
GOLDEN RIVER MARKSMAN 850
Developed to monitor traffic, it is now being tested to determine speed as well.
It is like a CCTV system, which runs constantly. The live feed is transmitted to a control room.
Now being adapted to focus on number-plates.
IMAGE-PROCESSED VIDEO
Speed and Red Light Cameras dramatically reduce accidents caused by speeding and red-light jumping.
Capable of providing automatic and evidential recording.
It’s status is technique operational.
Since the process is passive, are not vulnerable to the evasive capability of vehicles with radar detector equipment.
There is some doubt about the legal allow ability of image-processed video evidence.
Control exercised through static regulatory process: speed limits, one-way systems, clear way designations, Motorway exclusion rules, bus priority and cycle lanes.
Legal Police Devices
After the 1999 Scottish case where the police failed to make a prosecution stick when they implied that using the Police Pilot must be legal ‘because they’d been using if for years’, here’s a table of what the police can actually use legally. Simply put, if it’s not a home-office type-approved device, the police cannot use it to secure a conviction against you. This table is correct and valid as of 19 November 1999.
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Device Type
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Restrictions / usage
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Manufacturer
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Type Approval/Renewal Date
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SVDD
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n/a
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Speedcheck
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Riegl Laser Measurement System GmbH
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Riegl Laser Measurement System GmbH
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Jenoptic UK
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15 October 1999
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1 April 1996
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Unipar Services
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Use with Autovision 3 (AV3)
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Use with Kustom Prolaser II
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Cleartone Stealth Speedlaser
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Speedmaster DS3
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Use with Autovision 3 (AV3)
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Use with M4 Squared piezo sensors, MPC Speedmeter and Robot DCE camera
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Lasercam Digital Camera System
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LASTEC Local Video System
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Laser Technology
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Micro Mercury Speed measuring system 90500
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Micro Mercury Vision system 92600
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Use only with Speedmaster DS2
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Traffiphot S Speed Detection Device
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Peek Traffic |
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Speed man Enforcement System
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GATSO BV
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Kustom Signals Inc
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SERCO Speed Enforcement System Type 1
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