Modulation index (depth) based grouping, addressing, and fingerprinting RFID tags
First Claim
1. A method of addressing one or more RFID devices within a group of RFID devices, comprising:
- transmitting, to the group of RFID devices at a first modulation depth, a first command to respond;
receiving a response to the first command from a first sub-group of RFID devices in the group that have a minimum modulation depth less than or equal to the first modulation depth;
transmitting, to the group at a second modulation depth higher than the first modulation depth, a second command to respond;
receiving a response to the second command from a second sub-group of RFID devices within the group that have a minimum modulation depth less than or equal to the second modulation depth; and
identifying the second sub-group of RFID devices from the first sub-group of RFID devices based on the second sub-group of RFID devices not responding to the first command sent but responding to the second command.
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Abstract
A method of addressing one or more RFID devices within a group of RFID devices includes transmitting a command to respond to the group at a first modulation depth. The method further includes receiving a response from a first sub-group of RFID devices in the group that have a minimum modulation depth less than or equal to the first modulation depth. The method further includes transmitting the command to respond to the group at a second modulation depth higher than the first modulation depth. The method further includes receiving a response from a second sub-group of RFID devices within the group that have a minimum modulation depth less than or equal to the second modulation depth. The method is also directed to authenticating RFIDs by comparing a measured minimum modulation depth to a known minimum modulation depth.
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Citations
20 Claims
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1. A method of addressing one or more RFID devices within a group of RFID devices, comprising:
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transmitting, to the group of RFID devices at a first modulation depth, a first command to respond; receiving a response to the first command from a first sub-group of RFID devices in the group that have a minimum modulation depth less than or equal to the first modulation depth; transmitting, to the group at a second modulation depth higher than the first modulation depth, a second command to respond; receiving a response to the second command from a second sub-group of RFID devices within the group that have a minimum modulation depth less than or equal to the second modulation depth; and identifying the second sub-group of RFID devices from the first sub-group of RFID devices based on the second sub-group of RFID devices not responding to the first command sent but responding to the second command. - View Dependent Claims (2, 3, 4, 5, 6)
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7. An RFID system, comprising;
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a transmitter that transmits signals to a first group of RFID devices and a second group of RFID devices, the first group of RFID devices having a first minimum modulation depth, and the second group of RFID devices having a second minimum modulation depth higher than the first minimum modulation depth; and a controller that uses the transmitter to send a first signal to the first and second groups of RFID devices at a first modulation depth, and send a second signal to the first and second groups of RFID devices at a second modulation depth, wherein the first modulation depth being greater than or equal to the first minimum modulation depth and less than the second minimum modulation depth, wherein the second modulation depth being greater than or equal to the second minimum modulation depth, wherein the first group of RFID devices responding to the first and second signals, and wherein the second group of RFID devices responding to the second signal and not responding to the first signal. - View Dependent Claims (8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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18. A method of authenticating an RFID identification, comprising:
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transmitting, at a first modulation depth, a first signal comprising a command to respond to an RFID device installed on the RFID identification; determining if a response is received from the RFID device; transmitting a second signal comprising a command to respond to the RFID device at a higher modulation depth; receiving identifying information from the RFID device; obtaining a known minimum modulation depth of the RFID identification using the identifying information; comparing a measured minimum modulation depth of the RFID identification to the known minimum modulation depth; and determining that the RFID identification is not authentic if the measured minimum modulation depth varies more than a predetermined amount from the known minimum modulation depth. - View Dependent Claims (19, 20)
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Specification