Truvelo Combi

The reflected light provides the film with the correct exposure resulting in a clear picture of the driver committing the offence (considered as incriminating evidence).

Piezo-electric road strips, a known distance apart (1.53 cm from 1 - 3, 2 - 4) are set into the road in front of the camera, and the time between compressions is measured using an impededance converter and two clocks in the camera to give the resulting speed of the vehicle.

The system takes a single photograph (front-facing only, two for rear photography) and uses the time from the clocks to calculate the resulting speed.

For front-facing photography there are two sets of Piezo sensors that are linked as 1 - 3 and 2 - 4 in the road for Truvelo camera, both taking independent readings, if the two do not match (±2 mph) the offence is discarded.

[5] In the United Kingdom, the single incriminating photograph will not be sent unless the car owner asks for it – a Home Office ruling aimed at avoiding embarrassing situations if a driver is photographed with someone they would prefer not to be seen with.