Patent ID: 7932858

Claim:
A method for positioning a user on Earth, using a plurality of navigation satellites which are placed in medium-altitude orbits and which are managed by at least one terrestrial control center, comprising: transmitting first time and position information from each of said navigation satellites; managing a plurality of reference beacons by said terrestrial control centre, each of the reference beacons configured to transmit second time and position information and distribute a radioelectric signal in space; and aboard each of said navigation satellites: detecting said second time and position information transmitted by at least one of said reference beacons; computing first values and second values, respectively, representative of distances between said navigation satellite and each of said beacons and of a rate of variation of the distances based on said first and second time and position information; measuring a variation in Doppler frequency appearing in said radioelectric signals transmitted by said reference beacons; computing third values and fourth values, respectively, representative of the distances between said navigation satellite and each of said beacons and of the rate of variation of the distances based on said variations in Doppler frequency; comparing, for each reference beacon, said first values and said third values, and said second values of rate of variation of distance and said fourth values of rate of variation of distance; generating a signal representative of results of said comparisons; and transmitting via said navigation satellite the result signal to said user, at least when said comparisons reveal an anomaly.