Abstract: An object tracking system for locating radio-tagged objects has a plurality tag transmission readers that detect tag transmissions, and generate time-of-arrival output signals representative of the time-of-arrival of first-to-arrive tag transmissions on the basis of clock signals generated by local clock generators at the tag reader sites. The tag reader sites may transmit time-of-arrival signals to an object location processor by way of a wireless local area network. Measurements made on transmissions from a fixed position reference tag are used to update a reader clock offset database employed by the processor to maintain the reader clocks effectively time aligned.