Patent ID: 7974633

Claim:
In a method of locating a position of a mobile device using a sensor spaced apart a known distance from a base station in communication with the mobile device, the mobile device providing a signal transmission, the improvement comprising calculating and choosing a set of coordinates for the mobile device relative to the sensor as a function of: the known distance from the sensor to the base station, a range between the mobile device and the base station, an estimate of base station transmission timing relative to a time source known at the sensor, and a time of arrival of the signal transmission of said mobile device at the sensor, wherein the step of calculating a set of coordinates for the mobile device comprises determining the x coordinate from the following relationship: x = ± a ⁢ ⁢ sin ⁡ [ cos - 1 ⁢ { ( a 2 + b 2 - c 2 ) 2 ⁢ ⁢ a ⁢ ⁢ b } ] wherein a is a function of the time of arrival measured at the sensor, b is the known distance from the sensor to the base station, and c is the range between the mobile device and the base station.