International Mobile Satellite Organization

Inmarsat Limited

Samuel G Munoz-Garcia

Dennis Roy Mullins

Patrick Chomet

Shinichi Nomoto

Peter Poskett

Ben Hutchinson

A method and apparatus are disclosed for a system where a user terminal can communicate with satellites A-C, the satellites A-C can communicate with earth stations A-E which in turn can communicate with the terrestrial telephone system . The user terminal can register with one of the earth stations C which has an associated mobile satellite switching center C which acts as a gateway into the terrestrial system . When attempting to contact the user terminal from the terrestrial system the mobile satellite switching center C of visitor registration, if it cannot make the contact itself, instructs other earth stations , in turn, according to different methods of alternative earth station selection, until contact is made, and then routes all voice messages through itself C to retain the single and original gateway into the terrestrial system

Satellite communications gateway management system

A communication station for generating or receiving an angularly dispersed array of radiation beams, comprising an array of radiating elements ( ) defining an array antenna ( ); and a beam former ( ), the beam former comprising a passive network having a first side (X) carrying a plurality of beam ports for electrical signals corresponding to the beams and a second side (Y) carrying a plurality of antenna ports corresponding to the radiating elements, each beam port being connected to a plurality of antenna ports via a network ( ) of power divider ( ) and phase shifter ( ) components, the phase shifts of which are in integer multiples of a predetermined constant, so as to generate the array of beams; in which the array antenna ( ) has triangular or hexagonal symmetry and the array of beams has triangular or hexagonal symmetry.

Antenna system

A satellite communications system comprises satellites 9A-C, earth stations 7A-E, user terminals 11 and controlling gateways 3 in the form of mobile satellite switching centers 5A-E. Access with a user terminal 11 may be gained to a terrestrial telephone system 1 by earth stations 7A-E contacting the satellites 9A-C and by the satellites contacting the user terminals 11. The satellites 9A-C periodically broadcast messages indicative of the earth station 7A-E with which they are instantly in contact. The user terminal 11 listens to and logs these broadcasts to keep a list of the relative number of times each earth station 7A-E can be heard. When calling into the system, the user terminal pages earth stations in descending order of number of entries in the log. When in contact, the user terminal 11 sends the log to the system. When subsequently trying to contact the user terminal 11, the system uses earth stations in descending order of number of entries on the log, last received from the user terminal.

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London, United Kingdom

Samuel G Munoz-Garcia