Patent ID: 6563457
Filing Date: 2003-05-13
Classification: G01S

Abstract:
A method for determining a position of an object, the method comprising:transmitting a first ranging signal from a satellite ground station to the object via a first satellite at a first known location; transmitting a second ranging signal from the object to the first satellite in response to the first ranging signal for receipt by the satellite ground station; transmitting a third ranging signal from the satellite ground station to the object via a second satellite at a second known location; transmitting a fourth ranging signal from the object to the first satellite in response to the third ranging signal for receipt by the satellite ground station; transmitting a fifth ranging signal from the satellite ground station to the object via a third satellite at a third known location; transmitting a sixth ranging signal from the object to the first satellite in response to the fifth ranging signal for receipt by the satellite ground station; determining a first delay corresponding to a time difference between transmission of the first ranging signal by the satellite ground station and receipt of the second ranging signal by the satellite ground station; determining a second delay corresponding to a time difference between transmission of the third ranging signal by the satellite ground station and receipt of the fourth ranging signal by the satellite ground station; determining a third delay corresponding to the time difference between transmission of the fifth ranging signal by the satellite ground station and receipt of the sixth ranging signal by the satellite ground station; and determining the position of the object based on the first, second, and third known locations and the first, second, and third delays.