Cameras record the speed of all passing vehicles. If some of the vehicles exceed the permitted speed limit, the camera will take a picture of the vehicle and its driver. All recorded data (including the photo) will be sent to the proceedings centre of the police, where the person authorised to use the motor vehicle will be identified based on the licence plate of the car as seen on the photo.
The measuring principle of the measurement system is based on measuring the time difference of light impulses travelling to the object under measurement and back and calculating the speed on the basis of that and comparing that speed to the maximum value of the predetermined speed that activates the camera and preparing the necessary documentation if that value is exceeded.
The speed measurement system is based on LIDAR technology that generates a digital version of the image and emits short light impulses with the measuring beam. The beam covers the surroundings of the road during measuring activities and the system automatically determines the best distance for taking a picture in that particular environment.
Beams reflecting back from the object under measurement is received and processed by the LIDAR receiver. The system automatically calculates the distance between the measuring system and the object covered, using the readings determined by measuring the time it takes for light impulses to travel to the object under measurement and back. The speed of the vehicle is then calculated based on the estimated time derived from the readings acquired while measuring the distance.
Measuring speed is characterised by measurement uncertainty, which is caused by:
imperfections in the measurement system;
imperfections in the measuring method (meaning that the speed of the vehicle is not measured directly, but indirectly by calculating the distance and changes in the angle and measuring time);
environmental conditions at the measuring site during the measuring;
the object being measured (the vehicle).
Measurement uncertainty is taken into account when measuring the speed of vehicles – it is considered an admissible deviation, so to speak.
Cameras can measure the speed of vehicles driving on up to three parallel lanes, but pictures are only ever taken of vehicles that exceed the permitted speed limit. If there are more than one vehicle exceeding the permitted speed limit, each vehicle will be recorded separately. Taking a picture will allow the speeding vehicle to be identified regardless of which lane it is in. However, bear in mind that we are still subject to the rules of physics. If the vehicle exceeding the permitted speed limit happens to be fully behind a bus at the exact moment the picture is taken, the camera cannot look through the bus.
Cameras also work at night. The technical solutions of the cameras take into account any lighting conditions, allowing the vehicles’ registration plates to be identified in the dark. A flash is used both day and night. The flash on the cameras is equipped with a red filter to make sure the flash does not blind drivers. Drivers can see the red flash as the pictures are taken and will always know if the camera has recorded their speeding.