Method and apparatus for improving the efficiency and accuracy of RFID systems
First Claim
Patent Images
1. A method for interrogating RFID tags comprising:
- transmitting a data signal that causes said RFID tags to respond,transmitting one or more scramble signals that do not cause said RFID tags to respond, wherein at least one of said one or more scramble signals charges said RFID tags when said RFID tags are not being interrogated, andadjusting said data signal and said one or more scramble signals such that said one or more scramble signals overshadow said data signal in all but selected regions.
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Abstract
A method and apparatus for transmitting a narrow signal beam are disclosed that allow the precise location of RFID tags to be determined and reduce tag collisions. Also disclosed are a method and apparatus for improving the efficiency of RFID systems.
81 Citations
18 Claims
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1. A method for interrogating RFID tags comprising:
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transmitting a data signal that causes said RFID tags to respond, transmitting one or more scramble signals that do not cause said RFID tags to respond, wherein at least one of said one or more scramble signals charges said RFID tags when said RFID tags are not being interrogated, and adjusting said data signal and said one or more scramble signals such that said one or more scramble signals overshadow said data signal in all but selected regions. - View Dependent Claims (2, 3, 4, 5, 6, 7, 13, 14, 15, 16, 17, 18)
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8. A method for interrogating RFID tags comprising:
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transmitting a data signal that causes said RFID tags to respond, transmitting one or more scramble signals that do not cause said RFID tags to respond, wherein said one or more scramble signals have approximately constant amplitudes away from a central null for each scramble signal, and the total radiated power is approximately omni-directional, and adjusting said data signal and said one or more scramble signals such that said one or more scramble signals overshadow said data signal in all but selected regions. - View Dependent Claims (9, 10)
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11. A method for interrogating RFID tags comprising:
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transmitting a data signal that causes said RFID tags to respond, transmitting one or more scramble signals that do not cause said RFID tags to respond, adjusting said data signal and said one or more scramble signals such that said one or more scramble signals overshadow said data signal in all but selected regions, employing two or more array readers that scan an area with data and scramble signals to determine the angular positions of each tag within range, and determining the absolute position of said RFID tags through triangulation using the angular positions obtained with said two or more array readers. - View Dependent Claims (12)
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Specification