Method, system, and apparatus for communicating with a RFID tag population
First Claim
1. A radio frequency identification (RFID) tag device, comprising:
- an antenna that receives an electromagnetic carrier signal;
a receiver coupled to said antenna, wherein said receiver is configured to receive a symbol from said antenna, anda modulator coupled to said antenna;
wherein said modulator is configured to receive a response value, and is configured to select one of a plurality of frequencies according to said response value to be a selected frequency signal;
wherein said modulator is configured to backscatter modulate said received symbol according to said selected frequency signal to produce a backscatter modulated symbol; and
wherein said antenna is configured to transmit said backscatter modulated symbol.
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Accused Products
Abstract
A method, system, and apparatus for communicating with a radio frequency identification (RFID) tag population that includes one or more tags are described. The tags are interrogated by a reader which may be located in a network of readers. The reader interrogates the tags by transmitting data symbols to the tags. Tags respond to the reader with backscatter symbols. Bit patterns, such as identification numbers stored in the tags, are collected from the plurality of tags without collisions. Collisions are avoided because the backscatter symbols transmitted by the tags use different characteristics to represent different data bits. For example, a first backscatter symbol frequency is used by the tag to represent a “0” bit, and a second backscatter symbol frequency is used by the tag to represent a “1” bit.
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Citations
18 Claims
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1. A radio frequency identification (RFID) tag device, comprising:
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an antenna that receives an electromagnetic carrier signal; a receiver coupled to said antenna, wherein said receiver is configured to receive a symbol from said antenna, and a modulator coupled to said antenna; wherein said modulator is configured to receive a response value, and is configured to select one of a plurality of frequencies according to said response value to be a selected frequency signal; wherein said modulator is configured to backscatter modulate said received symbol according to said selected frequency signal to produce a backscatter modulated symbol; and wherein said antenna is configured to transmit said backscatter modulated symbol. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. A reader that communicates with a radio frequency identification (RFID) tag device, comprising:
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a transmitter that transmits a radio frequency carrier signal modulated with a data symbol; a receiver that receives at least one backscatter symbol related to the transmitted data symbol; and a logic module that determines at least one backscatter frequency of said at least one backscatter symbol, wherein said logic module determines that said at least one backscatter symbol represents a first data value when said at least one backscatter frequency includes a first frequency, and determines that said at least one backscatter symbol represents a second data value when said at least one backscatter frequency is determined to include a second frequency. - View Dependent Claims (17, 18)
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Specification