Speed camera film being recovered for processing. This piece of equipment is used to photograph vehicles exceeding the local speed limit. As well as a camera, the yellow unit also includes an electronic flash that is used at night. The camera measures a vehicle's speed using either piezoelectric strips embedded in the road or high- frequency radio waves. The photograph taken shows the number plate of the vehicle and has details encoded on the frame (time, date, location and speed). Processed photographs are sent out with penalty notices. As of 1993, the photograph is admissible in court as evidence in the case of disputed offences.