These cameras make use of laser technology. Speed is determined by measuring the time of flight of very short pulses of infrared light from the laser to the target and back again to the laser. As the speed of light is known and constant the time it takes the light to travel to the target and back is directly proportional to the distance to the target so by firing two pulses a known time apart two distances can be calculated and from these measurements a speed calculated. When the trigger is pressed a short burst of light pulses strike the target vehicle and return making a number of measurements in a matter of milliseconds. The software then profiles these measurements and compares them to ensure consistency and if consistent, a speed and range reading is made in 0.3 seconds. If not consistent an error message will be displayed and no speed or distance will be shown.
Mobile cameras are also used within the signed areas at fixed camera sites.