Guide to Speed Detection Devices

Systems used in the UK are generally type approved and require regular calibration. You are likely to come across the following types:


Usually linked to radar or sensors in the road with a back-up of lines in the road as a visual confirmation of the distance travelled over time.

Laser speed detection systems

These emit infrared light pulses using a very narrow beam. The time taken for the beam to be reflected is used to determine the distance to the object and a number of timed readings are used to calculate the distance over time (i.e. speed).

Radar systems

Using a combined transmitter and receiver. The device transmits radio waves at a specific frequency. When the waves are reflected back off moving objects this causes a change in frequency which is detected by the receiver. The device then calculates the speed as a result of the amount of change in frequency.

The 3 main frequencies used are known as X, K & KA. Most traps, such as the Gatso and most hand-held detectors, use the K band. Older systems may use the X band, which has been around since around the 1920’s, is less reliable and gives rise to a lot of false readings due to interference from other devices. The KA band is used by some new radar guns.

Some modern systems use Pulse Radar which means that a radar detector will not pick them up until they are actually reading your vehicle.

Stopwatch systems

May sound laughable, but stopwatch systems are relied on more and more due to the fact that they are very cheap. Put simply you are timed over a set distance and the system then automatically calculates your average speed. They are completely passive, so unless you spot them visually you will never know they are there.

Video systems

Video systems will either video everyone in view and then automatically send out notifications to all speeding cars or can be used to target specific vehicles. Again, these are passive so cannot be detected electronically.

Please click on the relevant link below to gain specific information relating to the speed camera, in car speed detection or radar device used by the police in your case.

Autopatrol PR-100

This is a speed camera system coupled to radar. The system is highly portable and can be mounted in a vehicle or on a tripod. It uses a very narrow radar beam and will not work (so they say) when more than 1 vehicle is within the beam. It has a digital camera with telephoto lens and can either be attended or left unattended (for example on a bridge). It has to be calibrated and technical issues arise. For help obtaining the evidence and assessing the case against you call us.

Auto Vision

This is a highly portable video-based system, linked to a laser, that is usually used in an unmarked van or car. The system is aimed at the front of passing vehicles and superimposes speed, time and distance information on a video image. It is popular due to its portability and the fact that it costs less than 1/3 of the price of a Gatso.

Calibrated Speedometers

Speed can be measured using a calibrated speedometer and this can be used in Court in support of a speeding offence. However the Association of Chief Police Officers (ACPO) gives clear guidance on the manner in which this may be done. A police officer must demonstrate that he has kept the target vehicle in line of sight and maintained an even distance from the vehicle over no less than 2/10 of a mile before he is able to attribute the speed to your vehicle.

A calibrated speedometer is more accurate than the standard speedometer fitted to a vehicle, so just because your vehicle said a different speed will not work as a defence. Manufacturers are allowed tolerances in accuracy of standard speedometers, which is why a satellite navigation device will usually provide a different speed reading for your vehicle.

Digital Camera

The camera is used to measure the average speed of every vehicle over a given distance of about a mile. The images are sent down phone lines to a central police camera where vehicle identification technology is used before sending out automatic notices to all the offending drivers. The cameras are portable, so can be moved at regular intervals. The system is most likely to be found added to the Gatso to create a super Gatso.

Gatso Speed Camera

The Gatso measures speed using radar technology and/or piezo sensors in the road. The Home Office have given approval for these devices to be used if there is independent corroboration that can provide a secondary check of the accuracy of the speed measured. This is usually done by line markings on the road. Radar devices are known to produce inaccurate readings due to interference from large vehicles, road furniture or any large reflective surface that is close by at the time the speed is measured. If an allegation of speed has been brought against you contact our team of expert lawyers to be advised on the merit of the police’s case against you. You will be advised as to whether there is a defence on which you can rely on in order to escape punishment.

Gatso’s are probably the most versatile of systems used by the police and it is estimated that 70% of speed camera points come from Gatso’s. They can be fixed (taking a photo of the rear of a passing vehicle), double sided (to catch vehicles in both directions) or red light based. They generally take 2 photos, providing visual back-up of their readings and new products with induction loops in the road are being developed. Red light cameras are also being adapted so that they act as speed cameras when the lights are amber or green and are activated to catch people running the lights once the lights go red.

Golden River Marksman 850

This is a CCTV system which runs constantly and was originally developed to monitor traffic. The system focusses on number plates, linked to number plate recognition software. The live feed is transmitted to a control room, so visual checks can be performed if you try to obscure your number plate.

Hand-held Radar

This is the most likely device used when a police officer steps out in front of you or jumps up at the side of the road. The reading is instant and they have a range of 500m. There are known problems where more than one vehicle is in range at the same time, as it may read the wrong vehicle or obtain a reflected reading. Also, it is not supposed to be used in rain, snow or high dust environments. If you are stopped by an officer using one of these we recommend you contact us as soon as possible.

LTI 2020 Speed Gun

The LTI 2020 (along with the Prolaser and Riegl) is a hand-held or tripod mounted laser speed gun regularly used by police officers during planned road police enforcement. The LTI 2020 has been banned from use in some countries throughout Europe and various states in the USA due to accuracy issues, however in the UK the Home Office has given approval for its use in capturing speeds. Inaccurate readings are obtained when ‘panning’ or ‘slippage’ occurs during the speed measurement process. It is not authorised for use at distances over 1,000m, but can detect that you are running a jammer device. If you deny speeding and need help with assessing the police’s case against you then call our team of expert lawyers. We seek disclosure of the evidence, assess it and advise you on any defence that you may have.


This system is an automated traffic system using electro-optic and infra-red technologies which can be used fixed, mobile or from parked vehicles. It is lane-based, measuring the progress of vehicles in a given lane of traffic. Parameters are set for speed, distance between vehicles and acceleration. If you break pre-set parameters it is linked to digital cameras which take photos of both the front and rear of your vehicle. The system works 24 hours a day and is not affected by weather or lighting conditions. The date is stored on DAT, sent to a Data Processing Unit linked to the DVLA and automatically processes notices to all offending drivers. As it does not use radar most detectors will not pick it up.


This is a radar based system which can be pole or box mounted, mobile or built in to a vehicle. They are mostly used as mobile traps set up on bridges over Motorways or main roads. The system takes a number of readings (usually 4 or above) of a vehicle before taking a photo and can take 3 photos per second. The units can be either front or rear facing and look like small rocket launchers. They use a highly targeted radar beam, which makes them almost invisible to most radar detectors.


This is a version of hand held radar (see above) using a “K-band” frequency.


This is an in-car video camera. It can be placed to look forwards or back, so tailing the police car at speed may not be sensible. The video is usually played back to the driver at the roadside. If they do not play it back then there is a distinct possibility it was not switched on or facing you at the time. Again, it must be calibrated and if you intend to challenge a prosecution based on this type of evidence you need expert assistance.


These are “Big Brother” surveillance cameras which can read your number plate at any time of day and in any weather conditions. They are primarily used to detect untaxed cars, but with an ever expanding network they are being used to track and log vehicle movements. Speeding tickets are then issued automatically based upon the time taken to pass between cameras.


Riegl manufacture a number of speed detection devices, including the LR90-235/P and FG21-P, which are authorised for use in the UK. These devices are hand-held laser guns accurate up to 600m (LR90) or 1000m (FG21). The LR90 is claimed to be more accurate, with a 1km/h accuracy rating as opposed to the FG21-P rating of +/-3km/h up to 100km/h and +/-3% of measured value over 100km/h

Robic Portable Speed Calculator

In essence this is a hand-held stopwatch activated manually to record the time it takes a vehicle to travel a fixed distance. It then immediately calculates the speed of the vehicle involved. It is cheap (about £20) and is starting to be deployed to beat officers, not just traffic officers. However, they have to be able to show the distance was measured accurately for this offence to be proven. We recommend you instruct us to raise the challenge with the police.


This is a speed camera system which takes a photo of the front of your car. There is no flash and there is no film to run out, it is all digital. The next camera you go by then calculates your average speed between the two and the first you know about it is when the NIP drops through the door. While it reads the number plate digitally, if there is a problem then the picture is checked manually. However it is front facing and cannot catch motorcycles. It is very difficult to defeat this system and you need expert assistance if you intend to try.

The system transmits registrations directly to the DVLA. It is a low cost system of tracking registrations by the police and where appropriate the nearest patrol car can be alerted via satellite navigation. As the equipment is inexpensive and virtually maintenance free it is likely to become more common.

Speedcheck (SVDD)

This stands for the Sure way Video Detection Device and works in a similar fashion to a GATSO. The SVDD costs £120,000 each to install and works by deploying cameras at either end of a measured baseline which can be up to 500 metres long. It is able to monitor vehicles 24hrs a day, with number plate recognition ability built in. It records the time when you pass the first camera, matches this to the time you pass the second camera and calculates your average speed. A digital photo is taken of the offending vehicle to prove the case in Court. The system is 99% accurate, works in almost all weather conditions, records all information digitally and is completely self-sufficient. Where connected to the DVLA it can automatically process fines and send out any notices in the post. As it does not have radar it is impossible to detect electronically.


This is a generic name for speed camera vans used by the police or speed camera partnership. The livery of the vans varies and they will often have amber, instead of blue, lights on top. They may often be parked illegally at the side of the road and the speed detection devices they use vary around the country. It has been reported that certain areas are reducing the use of the Talivan, although this is probably in favour of alternative speed detection methods.


This is an in-car system fitted to your own car to identify the location of the car if it is stolen. The police use it to recover stolen vehicles, but can also use the data to prove speeding offences. However, they can only switch it on once a car is reported as stolen. You are unlikely to be facing prosecution based on this evidence, but if you are you definitely need legal advice because it raises all manner of complicated human rights arguments.

Traffiphot S Piezo

The Traffiphot works on strips laid into the road at known distances apart. When the strips are compressed a reading is taken. The system then uses the average time between compressions to calculate the speed of the vehicle while a photo is taken. The speed camera is operated in an unmanned mode, so the evidence of speed must be corroborated from an independent source. The authorities are required to prove that the device is in current calibration, that the sensors are laid to engineering standards and there is sufficient independent evidence to prove that the speed was correctly measured. If you have received a notice of intended prosecution for a speeding offence that you dispute then we recommend you contact us to be advised on the accuracy of the allegation and any options you may have to avoid being punished for the offence.


The Truvelo DS2 speed camera uses 3 rubber hoses across the carriageway, about 1m apart, with piezo sensors at one end. They can be either permanent or temporary. Permanent sites are harder to spot as the sensors are laid within the road. The authorities are required to prove that the device is in current calibration, that the sensors are laid to engineering standards and there is sufficient independent evidence to prove that the speed was correctly measured. The system is often linked to either the Autovision (video) or Speedmaster (police hiding by the road) systems, but they still have to show that there is independent evidence to show the speed was accurately measured. If you have received a notice of intended prosecution then we recommend you call us for advice on how this can be challenged.

Vascar/Police Pilot

The Vascar and Police Pilot are in-car speed detection devices used by police officers. They are manually controlled, usually fitted in a patrol car and the machine can either be used to measure time taken over a pre-determined distance or while following you along the road. Both devices operate like stop watches, however speeds are incorrectly measured when the user miscalculates the distance over which the vehicle travelled or the time in which it took a vehicle to travel between the switching points. There are known inaccuracies attributable to the manner in which operators use these devices, so it is the Association of Chief Police Officers (ACPO) and not the Home Office that have approved the Vascar and Police Pilot to measure speeds.

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