Inventors:
Simon Desai - San Jose CA
James G. MacKnight - Morgan Hill CA
Assignee:
Trimble Navigation Limited - Sunnyvale CA
International Classification:
G01S 124, G01S 502, G01S 302, G04C 1102
Abstract:
Method and apparatus for providing precise universal time coordination or synchronization for each of a plurality of N vehicles, numbered consecutively i=1, 2,. . . , N (N. gtoreq. 2) that move within a selected geographic region and that communicate by radiowaves with one or more base stations located within or adjacent to the selected region. Each vehicle is provided with a sequence of Satellite Positioning System (SPS) signals, with a sequence of SPS timing signals, and with a SPS signal transceiver/processor that receives the SPS signals and SPS timing signals and determines the present location of the vehicle and the time the vehicle location determination is made. One or more base stations broadcast a sequence of base station timing signals that are received by each vehicle. A timing signal choice means on each vehicle receives the SPS timing signals sequence and the base station timing signals sequence and chooses the timing signal sequence that is both presently available and presently the most accurate. A sequence of nonoverlapping time slots is determined that includes substantially all times within a selected time interval.