Abstract: Position detection methods and apparatus include transmitters, coupled to each object to be tracked, for transmitting signals uniquely identifying each transmitter. Receivers disposed at known locations receive the transmitted signals and generate received signals representative of the transmitted signals. Arrival-time elements, responsive to a selected zero-crossing or other event in each received signal, determine the respective arrival time of each transmitted signal at each receiver. A processor calculates differences in arrival times of the transmitted signals at each receiver, and determines the spatial position of each object with respect to the known locations of the receivers.