Patent ID: 8193984

Claim:
A location system comprising: a plurality of base units at known locations for enabling the locating of a device by means of one or more location signals communicated between the device and the base units; and signal processing equipment configured to: (i) determine the location of the device in dependence on the time-difference-of-arrival and angle-of-arrival of the location signal(s) as received by the base units; and (ii) derive calibration data for calibrating the clocking of each base unit from the time-difference-of-arrival and angle-of-arrival of the location signal(s) as received by the base units, wherein the signal processing unit is configured to derive the calibration data independently of any reference timing generator that is external to a subsystem consisting of the plurality of base units and the device, and the calibration data defines a timing offset in the clocking of each base unit relative to a reference clock.