In a satellite communications system, where a satellite 10 provides a plurality of radio beams 30, and where distance and/or angle measurement from a satellite 10 or satellites 10 enables the position of the user terminal 44, on the surface of the earth 14, to be measured to within an uncertainty of...http://www.google.com.hk/patents/US6128468?utm_source=gb-gplus-share專利 US6128468 - Satellite communications terminal location system and method
