Abstract: Disclosed is a system for determining if a human being, object or animal has moved beyond a predetermined radius. The system includes a base station, and at least one slave associated with the base station. Each of the slaves is located on the human being, object or animal, and each slave is adapted to receive and emit a coded signal at predetermined intervals. The base station is adapted to transmit and receive the coded signal, decode the coded signal and, if the coded signal represents a slave associated with the base station, determine a signal strength of the coded signal, the signal strength of the coded signal indicating that the human being, object or animal has moved beyond a predetermined area if the signal strength is below a predetermined threshold.