Patent ID: 6850737

Claim:
A communication system having at least one primary radio station (PS) and at least one secondary radio station (SS) intended to be in motion (MOT), said secondary radio station having at least one controllable structure (CS) for communicating with said primary radio station, and control means (CONT) for controlling said controllable structure depending on said motion, said control means comprising magnetic field sensors (MFS) for providing measurements of the earth magnetic field (H), characterized in that said control means comprise also gravitational field sensors (GFS) for providing measurements of the earth gravitational field (G), and computing means (COMP) for computing control information from said measurements, wherein said control means comprise a memory for storing inclination (ι) and declination (δ) values of the earth magnetic field, and said computing means include a converting step for converting coordinates (rl) of positioning information in a moving coordinate system attached to the secondary radio station, said coordinates being called local coordinates, into corresponding coordinates (rg) in a fixed coordinate system attached to earth, said coordinates being called global coordinates, this conversion being calculated from said values and measurements of said magnetic field and gravitational field sensors.