A transmission sequence is broadcast from a locator to a group of transponder devices. Each transponder identified with the group is arranged to receive and capture at least a portion of the transmission, correlate the captured information with an internally stored reference sequence for the identified group, and identify a correlation when the captured information correlates with the internally stored reference sequence. Each transponder that finds a correlation is arranged to broadcast a transmission reply sequence at a precisely determined time interval so that the transponders in a group transmit at different times. A series of locators receive the transmission reply sequence(s), each at a precisely logged time of arrival, and the locators forward the received results to a central processing unit for time synchronization, location tracking, and inventory logging.