Haemmig Adrian, Gibson James A: Vehicle location systems. Products of Information Technology, Knobbe Martens Olson Hubbard & Bear, April 8, 1975: US3876980 (82 worldwide citation)

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 ...