Patent ID: 6480788
Filing Date: 2002-11-12
Classification: G01S

Abstract:
A system for determining a location of a mobile terminal, comprising:the mobile terminal, which receives a plurality of global positioning system (GPS) signals and measures a signal characteristic corresponding to each of the received GPS signals; a communication satellite that sends a forward control channel to the mobile terminal, receives an access request from the mobile terminal and compares timing of the received access request to an internal reference to generate timing correction information to send to the mobile terminal to adjust its data transmission timing so that data received from the mobile terminal does not overlap data received from other mobile terminals; a SOC to which the mobile terminal sends a message containing the timing correction information and the signal characteristic for each of the received signals, the SOC determining a range arc with the communication satellite at its origin using the timing correction information, the SOC determining possible locations of the mobile terminal on or near where the range the range arc intersects a surface of the Earth and using the signal characteristic to refine the possible locations and determine a final position of the mobile terminal.