Patent ID: 6433740
Filing Date: 2002-08-13
Classification: G01S,H04W

Abstract:
A method for operating an AMPS cellular telephone system comprising the steps of:(a) generating a SAT tone within a first base station, said SAT tone being synchronized to a received GPS signal; (b) transmitting said SAT tone from said first base station to a mobile unit; (c) re-transmitting said SAT tone from said mobile unit to a plurality of other base stations; (d) receiving said re-transmitted SAT tone at said plurality of other base stations, said plurality of other base stations each locally generating an audio comparison tone synchronized with said GPS signal, such that the plurality of other base stations do not use signals received from any other base station in order to locally generate the audio comparison tone; (e) calculating a plurality of phase differences between said received re-transmitted SAT tone and said locally generated audio comparison tone, each calculated phase difference corresponding to one of said other base stations; (f) calculating a plurality of distances between said other base stations and said mobile unit and an associated plurality of location curves using said plurality of phase differences; and (g) resolving a location of said mobile unit using said plurality of location curves.