Method and system for determining the distance between an RFID reader and an RFID tag using phase
First Claim
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1. A method of determining a distance between an RFID reader and an RFID tag comprising:
- transmitting two or more RF signals having corresponding two or more frequencies from said reader, and in accordance therewith, receiving two or more backscattered signals having the two or more frequencies in the one or more readers from said tag;
measuring a phase difference between the two or more frequencies of the backscattered signals; and
determining said distance between said reader and said tag using the measured phase difference.
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Abstract
Embodiments of the present invention include a method of determining a distance between an RFID reader and an RFID tag comprising transmitting two or more signals having two or more corresponding frequencies from said reader and measuring a phase difference between backscattered signals from said tag. A distance between the tag and reader may be determined using the measured phase difference. In one embodiment, multiple frequency pairs may be used and an average distance may be generated.
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Citations
21 Claims
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1. A method of determining a distance between an RFID reader and an RFID tag comprising:
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transmitting two or more RF signals having corresponding two or more frequencies from said reader, and in accordance therewith, receiving two or more backscattered signals having the two or more frequencies in the one or more readers from said tag; measuring a phase difference between the two or more frequencies of the backscattered signals; and determining said distance between said reader and said tag using the measured phase difference. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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- 12. A method of determining a distance between an RFID reader and an RFID tag comprising transmitting two or more signals having two or more corresponding frequencies from said reader and measuring a phase difference between backscattered signals from said tag.
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21. A RFID system comprising:
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an RFID tag; an RFID reader; wherein the reader transmits two or more signals having two or more corresponding frequencies and measures a phase difference between backscattered signals from the tag.
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Specification