Geolocation method and apparatus for satellite based telecommunications system
First Claim
1. A method for determining a geolocation of a mobile terminal in a satellite based telecommunications system which supports first and second forward communications links from first and second earth stations through first and second satellites to a common mobile terminal and which supports at least one return communications link from the mobile terminal through the first satellite to the first earth station, said method comprising the steps of:
- transmitting first and second communications signals over the first and second forward communications links to the mobile terminal from the first and second earth stations through the first and second satellites, respectively;
obtaining, at the mobile terminal, synchronization differential data based on the first and second communications signals received by the mobile terminal, said synchronization differential data corresponding to a difference in synchronization between the first and second communications signals received by the mobile terminal;
transmitting, from the mobile terminal, the synchronization differential data to the first earth station over the first return link;
determining, at the first earth station, return link synchronization data for the mobile terminal necessary to maintain incoming telecommunications signals received over the return link synchronized with the earth station;
calculating, at the first earth station, at least first and second geoposition lines, along which the mobile terminal is positioned, based on the return link synchronization data and the received synchronization differential data;
determining a geographic point of intersection of the at least first and second geoposition lines; and
outputing the geographic point of intersection as a geolocation of the mobile terminal.
4 Assignments
0 Petitions
Accused Products
Abstract
A method is provided for determining the geolocation of a mobile terminal within a telecommunications satellite system. The system supports first and second forward communications links from first and second earth stations through first and second satellites to a common mobile terminal. The method includes receiving, at the mobile terminal, first and second forward link communications signals from the first and second earth stations and, based thereon, obtaining synchronization differential data. The synchronization differential data may include timing and frequency synchronization data necessary to maintain synchronization between the first and second communications at the mobile terminal. The mobile terminal transmits the synchronization differential data to the first earth station over the return link. The first earth station receives communications signals from the mobile terminal and based thereon calculates return link synchronization data. The earth station further calculates at least first and second geoposition lines, along which the mobile terminal is positioned, based on the return link synchronization data and the synchronization differential data received from the mobile terminal. The first and second geoposition lines define a point of intersection at which the mobile terminal is located.
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Citations
15 Claims
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1. A method for determining a geolocation of a mobile terminal in a satellite based telecommunications system which supports first and second forward communications links from first and second earth stations through first and second satellites to a common mobile terminal and which supports at least one return communications link from the mobile terminal through the first satellite to the first earth station, said method comprising the steps of:
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transmitting first and second communications signals over the first and second forward communications links to the mobile terminal from the first and second earth stations through the first and second satellites, respectively; obtaining, at the mobile terminal, synchronization differential data based on the first and second communications signals received by the mobile terminal, said synchronization differential data corresponding to a difference in synchronization between the first and second communications signals received by the mobile terminal; transmitting, from the mobile terminal, the synchronization differential data to the first earth station over the first return link; determining, at the first earth station, return link synchronization data for the mobile terminal necessary to maintain incoming telecommunications signals received over the return link synchronized with the earth station; calculating, at the first earth station, at least first and second geoposition lines, along which the mobile terminal is positioned, based on the return link synchronization data and the received synchronization differential data; determining a geographic point of intersection of the at least first and second geoposition lines; and outputing the geographic point of intersection as a geolocation of the mobile terminal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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Specification