Patent ID: 7030761
Filing Date: 2006-04-18
Classification: G01S

Abstract:
1. An object location system for locating an object having an RFID tag, the object location system comprising: an object locator, the object locator receiving at least one transmission from the object and determining a general location of the object from the at least one transmission; an RFID reader, the RFID reader transmitting a plurality of transmitted signals to the RFID tag and receiving a plurality of backscatter-modulated signals from the RFID tag, at least two of the plurality of transmitted signals having a different fundamental frequency; and a distance calculator, the distance calculator determining a phase for each of the plurality of backscatter-modulated signals from the RFID tag, the distance calculator determining a distance to the RFID tag by determining a rate of change of the phase in the plurality of backscatter-modulated signals with respect to rate of change in the fundamental frequency of the plurality of transmitted signals.