Patent ID: 6163295
Filing Date: 2000-12-19
Classification: G01S

Abstract:
A method using satellite signal transmission for determining the geographic location of a receiver on the earth's surface, comprising:receiving a first signal transmitted at a known frequency from a first satellite having a known orbital position;receiving a second signal transmitted at the same frequency as the first signal from a second satellite having a known orbital position;calculating measured distances .lambda..sup.1 and .lambda..sup.2 of the respective first and second satellites from the receiver based at least in part on the transmission times of the first and second signals; andcalculating actual distances .rho..sup.1 and .rho..sup.2 of the respective first and second satellites from the receiver based on the measured distances .lambda..sup.1 and .lambda..sup.2, according to the relationships ##EQU14## where .o slashed. is the angle formed between a first vector extending from the receiver to the first satellite and a second vector extending from the receiver to the second satellite, the respective first and second vectors determined by the measured distances .lambda..sup.1 and .lambda..sup.2,.rho..sup.1-2 is the distance between the first and second satellites as determined by the measured distances .lambda..sup.1 and .lambda..sup.2, andwhere F.sub.pp.sup.1 and F.sub.pp.sup.2 are obliquity factors for the first and second satellites based on the respective angles .phi..sub.1 and .phi..sub.2 they form with a plane tangent to the earth's surface at the geographic location of the receiver, with ##EQU15## where R.sub.e is the radius of the earth and H.sub.r is the height of maximum electron density in the ionosphere surrounding the earth's surface.