Abstract: A local clock network can have a reference control unit with a reference clock. Coupled to each reference clock can be a plurality of remote stations. User units are in the form of clock indicator units which provided clock signals for use by internal client systems. The network(s) is/are closed loop system(s) between the associated reference and remote user stations. Each reference station determines the latency associated with each remote user station and generates an offset for each user station. Each reference station then generates a specific clock signal for each remote user station on the basis of its reference clock signal adjusted by the appropriate user station offset. A plurality of separate networks can be synchronized by reference to their local Coordinated Universal Time clocks, with one reference station acting as a master station.

Abstract: In the field of vehicle occupant detectors there is a need for an improved vehicle occupant detector which is able to consistently identify the number of occupants in vehicles having windscreens with different infrared transmission characteristics. A vehicle occupant detector comprises a first infrared illuminator that is operable at a first infrared wavelength to illuminate an interior of a vehicle, and a second infrared illuminator that is operable at a second infrared wavelength to illuminate an interior of a vehicle. The vehicle occupant detector also includes a first infrared detector to capture a first image of the interior of the vehicle illuminated at the first infrared wavelength, and a second infrared detector to capture a second image of the interior of the vehicle illuminated at the second infrared wavelength. The first and second infrared detectors have the same infrared detection characteristics.