Wireless tag ranging
First Claim
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1. A method of determining a distance between a reader and a wireless tag, the method comprising the steps of:
- transmitting a query signal from the reader to the wireless tag;
transmitting a modulated signal from the reader during at least a portion of a response period for the wireless tag, wherein the response period begins following transmission of the query signal;
receiving a modulated backscatter response from the wireless tag at the reader; and
using the modulated backscatter response to calculate a distance between the reader and the wireless tag.
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Abstract
Disclosed are embodiments of methods, systems, and apparatus for ranging or determining a distance between a reader and a wireless tag. In one embodiment, a query signal is transmitted from the reader to the wireless tag. The carrier signal from the reader may then be modulated and the modulated signal transmitted from the reader during at least a portion of a response period for the wireless tag. A modulated backscatter response from the wireless tag is received at the reader and is used to calculate a distance between the reader and the wireless tag.
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Citations
44 Claims
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1. A method of determining a distance between a reader and a wireless tag, the method comprising the steps of:
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transmitting a query signal from the reader to the wireless tag; transmitting a modulated signal from the reader during at least a portion of a response period for the wireless tag, wherein the response period begins following transmission of the query signal; receiving a modulated backscatter response from the wireless tag at the reader; and using the modulated backscatter response to calculate a distance between the reader and the wireless tag. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. A method of determining a distance between a reader and an electronic tag, the method comprising the steps of:
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singulating a wireless tag; transmitting a query signal from a reader to the wireless tag; modulating a signal at the reader; transmitting a modulated signal from the reader to the wireless tag during at least a portion of the time during which the wireless tag responds to the query signal; detecting the modulated signal in a backscatter response from the wireless tag at the reader; measuring a delay between the transmitted modulated signal and the backscatter response; and calculating the distance between the wireless tag and the reader using the delay. - View Dependent Claims (18, 19, 20, 21, 22, 23, 24, 25, 26)
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27. A data reader comprising:
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a radio frequency identification (RFID) interrogator; a transmission component for transmitting a query signal to a wireless tag; a modulation component for modulating a signal for transmission via the transmission component, wherein the data reader is configured to modulate the signal while the data reader is waiting for a response to the query signal, to transmit a modulated signal to the RFID tag, and to detect a modulated backscatter response from the RFID tag; and a ranging component for calculating a distance between the RFID tag and the data reader. - View Dependent Claims (28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38)
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39. A data reader comprising:
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means for transmitting a query signal to a wireless tag; means for modulating a carrier signal; means for detecting at least one modulation in a backscattered response signal from the wireless tag; means for measuring a delay between the modulated carrier signal and the backscattered response signal; and means for calculating a distance between the data reader and the wireless tag from the delay. - View Dependent Claims (40, 41, 42, 43, 44)
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Specification