3876980 is referenced by 82 patents and cites 7 patents.

A vehicle location system having a plurality of stationary wayside stations positioned at predetermined geographical locations. The passage of a vehicle near a station references the location of the vehicle at that point in time and automatically supplies the remote headquarters with information as to the whereabouts of all vehicles operating in the system. Efficient utilization of the communication link between the vehicle and the remote headquarters is enabled by transmitting only updated location information to headquarters. The system enables low power radio frequency signals to automatically communicate error free location information between the wayside station and the vehicle by repetitively transmitting identical digitally coded messages and inhibiting utilization of the information contained in such message until receipt in succession of two location messages identical in code format.

Title
Vehicle location systems
Application Number
05/413,040
Publication Number
3876980
Application Date
November 5, 1973
Publication Date
April 8, 1975
Inventor
Gibson James A
Haemmig Adrian
Agent
Knobbe Martens Olson Hubbard & Bear
Assignee
Products of Information Technology
IPC
G08g 01/12
G08G 01/127
G08G 01/123
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