Land mobile communications and position fixing using satellites

Relay of land mobile communications directly between the vehicles and central stations using VHF repeaters on satellites in geosynchronous orbits is examined. Experiments demonstrated effective satellite-aided land mobile communications, analog and digital data relay, automatic real-time vehicle position fixing; specially designed satellite antenna, and a digital tone-code ranging responder which operates within the communications bandwidth. A commercial VHF base station with a satellite antenna received communications from NASA ATS-3 geosynchronous satellite which were used for position fixing the vehicle. The experiments demonstrated continent-wide communication of a quality comparable to fringe area reception of present local VHF mobile communications without multipath flutter. Vehicle positions to within one quarter mile were achieved in real time and within several hundred feet.