Systems and methods for RFID tag locating using constructive interference
First Claim
1. A method, comprising:
- transmitting a first signal from a first antenna towards a radio-frequency identification (RFID) tag; and
transmitting a second signal from a second antenna towards the RFID tag, the second signal constructively interfering with the first signal within a constructive interference region containing the RFID tag,wherein the first signal has a first amplitude below an activation threshold of the RFID tag, the second signal has a second amplitude below the activation threshold of the RFID tag, and the first signal and the second signal constructively interfere to produce constructive interference having an amplitude above the activation threshold within the constructive interference region.
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Accused Products
Abstract
A system and method for locating radio-frequency identification tags within a predetermined area. The method can incorporate sub-threshold superposition response mapping techniques, alone, or in combination with other methods for locating radio-frequency identification tags such as but not limited to time differential on arrival (TDOA), frequency domain phase difference on arrival (FD-PDOA), and radio signal strength indication (RSSI). The system can include a plurality of antennas dispersed in a predefined area; one or more radio-frequency identification tags; a radio-frequency transceiver in communication with said antennas; a phase modulator coupled to the ra-dio-frequency transceiver; and a system controller in communication with said transceiver and said phase modulator. Calibration techniques can be employed to map con-structive interference zones for improved accuracy.
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Citations
44 Claims
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1. A method, comprising:
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transmitting a first signal from a first antenna towards a radio-frequency identification (RFID) tag; and transmitting a second signal from a second antenna towards the RFID tag, the second signal constructively interfering with the first signal within a constructive interference region containing the RFID tag, wherein the first signal has a first amplitude below an activation threshold of the RFID tag, the second signal has a second amplitude below the activation threshold of the RFID tag, and the first signal and the second signal constructively interfere to produce constructive interference having an amplitude above the activation threshold within the constructive interference region. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A system, comprising:
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a first antenna configured to transmit a first signal from a first antenna towards a radio-frequency identification (RFID) tag; and a second antenna configured to transmit a second signal towards the RFID tag such that the second signal constructively interferes with the first signal within a constructive interference region containing the RFID tag, wherein the first antenna is configured to transmit the first signal at a first amplitude below an activation threshold of the RFID tag, the second antenna is configured to transmit the second signal at a second amplitude below the activation threshold of the RFID tag, and the first signal and the second signal constructively interfere to produce constructive interference having an amplitude above the activation threshold over the constructive interference region. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28)
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29. A method, comprising:
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transmitting a first signal from a first antenna towards a receiver; and transmitting a second signal from a second antenna towards the receiver, the second signal constructively interfering with the first signal within a constructive interference region containing the receiver, wherein the first signal has a first amplitude below an activation threshold of the receiver, the second signal has a second amplitude below the activation threshold of the receiver, and the first signal and the second signal constructively interfere to produce constructive interference having an amplitude above the activation threshold within the constructive interference region. - View Dependent Claims (30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42)
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43. A method, comprising:
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transmitting a first signal from a first antenna towards a radio-frequency identification (RFID) tag; transmitting a second signal from a second antenna towards the RFID tag, the second signal constructively interfering with the first signal within a constructive interference region containing the RFID tag; acquiring an image of the constructive interference region with a camera, the image of the constructive interference region showing an object and/or a person; and associating the object and/or the person in the image of the constructive interference region with the RFID tag.
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44. A method, comprising:
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transmitting a first signal from a first antenna towards a first known location; transmitting a second signal from a second antenna towards the known location, the second signal constructively interfering with the first signal at the first known location; receiving a first response signal, in response to the first signal and the second signal, from a reference RFID tag located at a first known location; moving the reference RFID tag to a second known location; altering a transmission parameter of the first signal so as to cause the first signal and the second signal to constructively interfere at the second known location; and receiving a second response signal from the reference RFID tag in response to the first signal and the second signal.
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Specification