Patent ID: 8026850

Claim:
A method for computing a location of a radio beacon by using Time Difference Of Arrival (TDOA) and multiple frequencies, comprising the steps of: a) receiving arrival time t j transmitted from each of a plurality of base stations, j (1<=j<=n, n is the number of the base stations), wherein each of the base stations, j receives first and second signals respectively having first and second frequencies from the radio beacon, and detects and transmits phase difference ΔΦ j between the first and second signals and the arrival time t j of a predetermined one of the first and second signals; b) receiving the phase difference ΔΦ j from each of the base stations, j; c) acquiring calculation distance R j based on the phase difference ΔΦ j with respect to each base station j, wherein the calculation distance R j corresponds to a plurality of solution distances; d) calculating a predicted location of the radio beacon based on Time Difference Of Arrival (TDOA) (Δt 1 , . . . , Δt n ), wherein Δt i is difference between one pair of arrival times among the arrival times (t 1 , . . . , t n ); e) removing phase ambiguity from the calculation distance R j by selecting the closest solution distance to the predicted location of the radio beacon among the plurality of solution distances, with respect to each base station j; and f) determining the location of the radio beacon based on the calculation distances (R 1 , . . . , R n ) deprived of the phase ambiguity.