Patent ID: 7812719
Filing Date: 2010-10-12
Classification: G08B

Abstract:
1. A radio frequency identification (RFID) system for object location and tracking comprising: an RFID reader for initiating a query for an RFID tag attached to an object; an RFID tag attached to said object for responding with a first response signal to said query, said query being received directly from said RFID reader; at least one sensor-tag for passively receiving a combined signal including said first response signal from said RFID tag and said query from said RFID reader, receipt, by said at least one sensor-tag, of said first response signal and said query is substantially simultaneous, passively demodulating said combined signal and decoding the first response signal from said RFID tag, and determining if said RFID tag is in a predetermined range of said at least one sensor-tag based on said passive demodulation and decoding; the said at least one sensor-tag passively communicating a second response signal by using backscatter modulation to said RFID reader, based upon the determination, when said at least one sensor-tag receives a request signal from said RFID reader; and a data processing element for processing said second response signal received from said at least one sensor-tag to determine the location of said RFID tag using a predefined calculation, a known position of said at least one sensor-tag and said predetermined range of said at least one sensor-tag.