Patent ID: 6433689
Filing Date: 2002-08-13
Classification: G06Q,G07C

Abstract:
A system for supervision and control of objects or persons within a limited area, comprising a plurality of electronic identification chips for placing on respective objects/persons to be supervised/controlled, each chip having stored a special ID code and being provided with a transmitter and a receiver for communication via ultrasound, a plurality of stationary detectors interconnected in a network and arranged for both-way communication with the chips, and a central control unit communicating with the chips via the detectors, wherein each chip and each detector also is provided with a transmitter and a receiver for communication via audible sound (audio), a means being provided for switching between ultrasonic and audio communication, and that each chip in operation is continuously active and is arranged to transmit its ID code at predetermined time intervals, at least one of the detectors or the control unit being arranged to trigger an alarm unit if an incorrect code is received or an approved code is not received continuously at chosen time intervals.