Patent ID: 6169484
Filing Date: 2001-01-02
Classification: G07C,G08B

Abstract:
A monitoring and location system comprising: a service center to monitor the movement of mobile objects to and from a prescribed local area and a prescribed wide area, a personal radio frequency (RF) transponder unit (RFTU) for each mobile object of a group being monitored, each RF transponder unit having a digital electronic identification number (DEIN) embedded therein for transmission by a radio frequency signal upon request from a radio frequency (RF) transceiver interrogation unit, wherein said prescribed local areas comprise a plurality of zones which includes egress zones and ingress zones; each zone has its own RF transceiver interrogation unit for monitoring the ingress and egress, respectively, of its own group of RFTUS; when an RFTU has egressed or ingressed one of said zones, said RFTU transmits its own DEIN to the RF transceiver interrogation unit of said one of said zones; when said RF transceiver interrogation unit received said DEIN, said RF transceiver interrogation unit transmit a signal includes said DEIN to said service center; and wherein said RF transceiver interrogation unit includes a distance and bearing detection for determining a distance and bearing between said RF transceiver interrogation unit and a RFTU; wherein said prescribed wide area comprises a plurality of cell sites, each cell site having areas encompassing said prescribed local area and a second transceiver interrogation unit at each cell site, respectively, to communicate with each RFTU located within a respective cell site and an interrogator at said service center for interrogating each cell site to determine whether a give RFTU and DEIN is within a given cell site.