VEHICLE SPEED MONITORING SYSTEM

摘要

A vehicle speed monitoring system comprises a plurality of cameras (10, 40) for capturing images of vehicle registration marks of passing vehicles. An electronic processing means produces electronic records for each vehicle recognition mark with an associated time of image capture. When a match is found between a vehicle registration mark stemming from a first camera (10) and from a second camera (40) then a central electronic processing means (20) uses the image capture times to calculate a travel time of the vehicle. This time is compared with a minimum travel time for a journey between the first and second cameras. Each camera (10, 40) is provided with clock means individual thereto which produces the times of image capture and each camera is also provided with timing verification means which accesses a plurality of independent time sources. The independent time sources originate time signals independently of the central electronic processing means, and the verification means is capable of checking whether the clock means is generating a time within a predetermined tolerance of the time signals obtained from the independent sources.