Location sensing using a radio frequency tag
First Claim
1. An RFID tag, comprising:
- a first receiver tuned to receive a first RFID signal, wherein the first receiver is configured to generate a first power value indicating a signal strength of the first RFID signal;
a second receiver tuned to receive a second RFID signal, wherein the second receiver is configured to generate a second power value indicating a signal strength of the second RFID signal, and wherein the first and second receivers are tuned to different frequencies;
a comparator configured to determine which of the first and second RFID signals has a greater signal strength based on the first and second power values; and
a transmitter configured to transmit a reply message using a frequency corresponding to the first or second RFID signal with the greater signal strength.
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Accused Products
Abstract
Embodiments herein describe RFID systems that include multiple RFID tag readers that each use a different frequency to communicate with an RFID tag. For example, each of the tag readers may transmit a tag query command using different modulated frequencies. In one embodiment, the RFID tag includes multiple receivers each tuned to one of the different frequencies generated by the tag readers. For example, one receiver in the tag is tuned to receive 200 MHz signals while another receiver is tuned to receive 900 MHz signals. To provide location information, the RFID tag compares power values associated with the received signals to determine which of the RFID tag readers is closest to the tag. The RFID tag conveys this location information to the tag readers by selecting one of the frequencies of the tag readers to use when generating a reply message.
11 Citations
13 Claims
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1. An RFID tag, comprising:
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a first receiver tuned to receive a first RFID signal, wherein the first receiver is configured to generate a first power value indicating a signal strength of the first RFID signal; a second receiver tuned to receive a second RFID signal, wherein the second receiver is configured to generate a second power value indicating a signal strength of the second RFID signal, and wherein the first and second receivers are tuned to different frequencies; a comparator configured to determine which of the first and second RFID signals has a greater signal strength based on the first and second power values; and a transmitter configured to transmit a reply message using a frequency corresponding to the first or second RFID signal with the greater signal strength. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. An RFID system, comprising:
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a first tag reader configured to transmit a first RFID signal using a first frequency; a second tag reader configured to transmit a second RFID signal using a second frequency different from the first frequency; a RFID tag comprising; at least one receiver configured to receive the first RFID signal and the second RFID signal; and logic configured to; select, in response to receiving the first and second RFID signals, one of the first and second frequencies by determining which of the first or second RFID signal has the greater signal strength, and output a reply message comprising a tag ID using the selected frequency. - View Dependent Claims (9, 10, 11, 12, 13)
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Specification