Systems and methods to determine motion parameters using RFID tags
First Claim
Patent Images
1. A method, comprising:
- transmitting at least one first radio frequency signal to a plurality of devices positioned in a field, each respective device in the plurality of devices configured tostore an identifier to uniquely identify the respective device among the plurality of devices, andselectively respond to radio frequency signals broadcast to the field based on the identifier stored in the respective device and commands modulated on the radio frequency signals,wherein the at least one first radio frequency signal is configured to request a first device having a first identifier in the plurality of devices to response to a subsequent radio frequency signal and to request second devices having second identifiers different from the first identifier in the plurality of devices to generate no response to the subsequent radio frequency signal;
transmitting the subsequent radio frequency signal to the field;
receiving at least one second radio frequency signal, responsive to the subsequent radio frequency signal, from the first device having the first identifier;
removing data modulation from the at least one second radio frequency signal to determine a Doppler frequency shift in the at least one second radio frequency signal; and
identifying a motion of the first device, based on the Doppler frequency shift.
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Abstract
Systems and methods to determine motion parameters of physical objects using radio frequency identification (RFID) tags attached to the objects. In one embodiment, a method implemented in a radio frequency identification (RFID) system includes determining a motion parameter of the RFID tag based on detecting a Doppler frequency shift in a radio frequency signal received from the RFID tag.
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Citations
17 Claims
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1. A method, comprising:
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transmitting at least one first radio frequency signal to a plurality of devices positioned in a field, each respective device in the plurality of devices configured to store an identifier to uniquely identify the respective device among the plurality of devices, and selectively respond to radio frequency signals broadcast to the field based on the identifier stored in the respective device and commands modulated on the radio frequency signals, wherein the at least one first radio frequency signal is configured to request a first device having a first identifier in the plurality of devices to response to a subsequent radio frequency signal and to request second devices having second identifiers different from the first identifier in the plurality of devices to generate no response to the subsequent radio frequency signal; transmitting the subsequent radio frequency signal to the field; receiving at least one second radio frequency signal, responsive to the subsequent radio frequency signal, from the first device having the first identifier; removing data modulation from the at least one second radio frequency signal to determine a Doppler frequency shift in the at least one second radio frequency signal; and identifying a motion of the first device, based on the Doppler frequency shift. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method, comprising:
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transmitting at least one first radio frequency signal to a plurality of devices positioned in a field, each respective device in the plurality of devices configured to store an identifier to uniquely identify the respective device among the plurality of devices, and selectively respond to radio frequency signals broadcast to the field based on the identifier stored in the respective device and commands modulated on the radio frequency signals, wherein the at least one first radio frequency signal is configured to request a first device having a first identifier in the plurality of devices to response to a subsequent radio frequency signal and to request second devices having second identifiers different from the first identifier in the plurality of devices to generate no response to the subsequent radio frequency signal; transmitting the subsequent radio frequency signal to the field; receiving at least one second radio frequency signal, responsive to the subsequent radio frequency signal, from the first device having the first identifier;
wherein the receiving of the at least one second radio frequency signal includes receiving a first signal using a first antenna and receiving a second signal using a second antennadetermining a frequency difference between the first signal received via the first antenna and the second signal received at the second antenna; determining a Doppler frequency shift in the at least one second radio frequency signal, wherein the Doppler frequency shift is determined based on the frequency difference; and identifying a motion of the first device, based on the Doppler frequency shift. - View Dependent Claims (11, 12, 13)
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14. A system, comprising:
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a plurality of devices disposed in a field, each respective device in the plurality of devices having a memory to store an identifier to uniquely identify the respective device among the plurality of devices, the respective device configured to selectively respond to radio frequency signals broadcast to the field based on the identifier stored in the memory and commands modulated on the radio frequency signals; and a reader configured to transmit at least one first radio frequency signal to the plurality of devices to request a first device having a first identifier in the plurality of devices to response to a subsequent radio frequency signal and to request second devices having second identifiers different from the first identifier in the plurality of devices to generate no response to the subsequent radio frequency signal, the reader further configured to transmit the subsequent radio frequency signal in response to which the first device having the first identifier is configured to provide at least one second radio frequency signal; wherein the reader comprises; a data processing system configured to determine a motion of the first device, based on a Doppler frequency shift detected in the at least one second radio frequency signal; a first antenna configured to receive a first signal of the at least one second radio frequency signal at a first location; and a second antenna configured to receive a second signal of the at least one second radio frequency signal at a second location; wherein the reader is configured to determine a frequency difference between the first signal received at the first antenna and the second signal received at the second antenna and to determine the Doppler frequency shift from the frequency difference.
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15. A system, comprising:
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a plurality of devices disposed in a field, each respective device in the plurality of devices having a memory to store an identifier to uniquely identify the respective device among the plurality of devices, the respective device configured to selectively respond to radio frequency signals broadcast to the field based on the identifier stored in the memory and commands modulated on the radio frequency signals; and a reader configured to transmit at least one first radio frequency signal to the plurality of devices to request a first device having a first identifier in the plurality of devices to response to a subsequent radio frequency signal and to request second devices having second identifiers different from the first identifier in the plurality of devices to generate no response to the subsequent radio frequency signal, the reader further configured to transmit the subsequent radio frequency signal in response to which the first device having the first identifier is configured to provide at least one second radio frequency signal; wherein the reader comprises a data processing system configured to determine a motion of the first device, based on a Doppler frequency shift detected in the at least one second radio frequency signal; wherein the first device is configured to modulate data on the subsequent radio frequency signal. - View Dependent Claims (16)
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17. A reader, comprising:
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a signal generator having an oscillator and configured to generate radio frequency signals to a plurality of devices positioned in a field, each respective device in the plurality of devices having a memory to store an identifier to uniquely identify the respective device among the plurality of devices, the respective device configured to selectively respond to the radio frequency signals broadcast to the field based on commands modulated on the radio frequency signals; at least one transceiver coupled with the signal generator to transmit at least one first radio frequency signal to the plurality of devices to request a first device having a first identifier in the plurality of devices to response to a subsequent radio frequency signal and to request second devices having second identifiers different from the first identifier in the plurality of devices to generate no response to the subsequent radio frequency signal; a first antenna positioned at a first location to receive a first signal from the first device having the first identifier responsive to the subsequent radio frequency signal; a second antenna positioned at a second location to receive a second signal from the first device having the first identifier responsive to the subsequent radio frequency signal; and a processor coupled with the at least one transceiver to determine a motion of the first device, based on a Doppler frequency shift detected from the first signal received via the first antenna and the second signal received via the second antenna, wherein the processor is configured to determine a frequency difference between the first signal received at the first antenna and the second signal received at the second antenna to determine the Doppler frequency shift.
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Specification