US Patent 7327251 RFID system for locating people, objects and things

A monitoring and location system for mobile objects is shown which includes a control center to monitor the movement of mobile objects to and from a prescribed local area and a prescribed wide area. Each mobile object is provided with a separate RFID tag which has a unique electronic indicia stored thereon for transmission by a radio frequency signal upon request from an RFID interrogation unit. The local areas includes egress zones and ingress zones, each zone having its own RFID interrogation unit for monitoring the ingress and egress, respectively, of its own group of RFID tags. When an RFID tag has egressed or ingressed one of the zones, the RFID transmits its unique electronic indicia to the RFID interrogation unit of one of the zones, and when the RFID interrogation unit has received the indicia, the RFID interrogation unit transmits a signal including such indicia to the control center. The control center transmits information concerning the location of the mobile object to an end user by means of a dedicated personal electronic device carried or worn by the end user.