MOVABLE SUBSCRIBER DEVICE LOCATION USING DUAL SATELLITES

摘要

In a communication system where two orbiting satellites (10, 20) travel in nonparallel paths, a movable subscriber device (100) is accurately located. Each satellite transmits geolocation information which is received by the movable subscriber device (100). The movable subscriber device (100) then uses Doppler frequency shift information as well as time of arrival to locate itself along a first strip on the surface of the earth (30) which extends perpendicular to the direction of motion of the first satellite (10). When geolocation information from the second satellite (20) is received by the movable subscriber device (100), the device locates itself along a second strip on the surface of the earth (30) which extends perpendicular to the direction of motion of the second satellite (20). The movable subscriber device (100) can then be accurately located at the intersection of the first and second strips.