Method of locating a fixed terminal using a constellation of satellites

摘要

A method of locating a fixed terminal of a telecommunication system comprising a constellation of satellites, a plurality of gateway stations and a plurality of fixed terminals includes “coarse”, “intermediate” and “fine” location phases.;During the “intermediate” location phase, the terminal calculates at least three hyperboloids and their intersection, assuming a “coarse” estimated position of the terminal is known. Each hyperboloid can be written:; $PTEXTHILITALICPDATH/PDAT/ITALIC/HILHILSBPDATi,j/PDAT/SB/HILHILITALICPDAT:dj\−di/PDAT/ITALIC/HILPDAT\=(/PDATHILITALICPDATtj\′\−tj/PDAT/ITALIC/HILPDAT)./PDATHILITALICPDATc/PDAT/ITALIC/HILPDAT\−(/PDATHILITALICPDATti\′\−ti/PDAT/ITALIC/HILPDAT)./PDATHILITALICPDATc/PDAT/ITALIC/HIL/PTEXT$ ;where:;di is the distance between the terminal and the position pi of the ith active satellite at time ti,;dj is the distance between the terminal and the position pj of the jth active satellite at time tj,;ti and tj are the ith and jth times of transmission by the ith and jth satellites, respectively, of ith and jth information relating to ti and di and to tj and dj, respectively,;ti′ and tj′ are the ith and jth times of reception by the terminal of the ith and jth information, and;c is the speed of light.