Abstract: In a system for monitoring, within a preselected distance or location defining the perimeter of a preselected distance, and locating the position of persons, animals or moving objects, a base-station generates an interrogation signal which, when detected by one or more transceiver units triggers the one or more of the transceiver units to generate a return signal. Each of the transceiver units, upon being located outside the preselected distance or upon becoming inoperable, detects an interruption in the interrogation signal, ceases to generate the return signal, alerts the user of the transceiver unit and, after a delay period, triggers a homing signal. The base-station, upon detecting an interruption in the return signal from any one of the transceiver units, triggers a delay period for that transceiver unit and, upon expiration of the delay period, triggers locating circuitry to determine the position of the transceiver unit.