Identifying RFID Tag Moving Coherently with Reader
First Claim
1. A method for identifying an RFID tag moving with an RFID reader, comprising:
- (a) transmitting by the reader over a period of time a plurality of reading signals, wherein said signals have a signal period;
(b) receiving by the reader reply signals from any RFID tags within range of the reader;
(c) determining for each reply;
a particular RFID tag from which the reply was received; and
a received signal strength from the RFID tag;
(d) analyzing the received signal strengths and noting any consistencies of signal strengths correlated with the period of the signal period; and
(e) determining from the consistencies whether the particular RFID tag is moving coherently with the RFID reader.
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Accused Products
Abstract
A system and method to distinguish an RFID tag which is moving synchronously with an RFID reader from other RFID tags which are not moving synchronously with the reader. In one embodiment, the reader emits read signals at a fixed frequency with a corresponding period. A determination is made by the RFID reader as to the signal strengths received from an RFID tag at time intervals which are integer multiples of the half-period of the signal. Signal strengths from the tag which are the same or substantially the same at these prescribed measurement intervals are taken as an indication that the tag is moving synchronously with the RFID reader. In an alternative embodiment, the frequency of the read signals may vary over time. Correlations between received tag signal strengths with particular frequencies are an indication that the RFID tag is moving synchronously with the RFID reader.
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Citations
22 Claims
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1. A method for identifying an RFID tag moving with an RFID reader, comprising:
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(a) transmitting by the reader over a period of time a plurality of reading signals, wherein said signals have a signal period; (b) receiving by the reader reply signals from any RFID tags within range of the reader; (c) determining for each reply; a particular RFID tag from which the reply was received; and a received signal strength from the RFID tag; (d) analyzing the received signal strengths and noting any consistencies of signal strengths correlated with the period of the signal period; and (e) determining from the consistencies whether the particular RFID tag is moving coherently with the RFID reader. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method for identifying an RFID tag moving with an RFID reader, comprising:
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(a) transmitting by the reader over a period of time a plurality of reading signals at a plurality of frequencies within a transmission band; (b) receiving by the reader reply signals from any RFID tags within range of the reader; (c) determining for each reply; a particular RFID tag from which the reply was received; a received signal strength from the RFID tag; and a frequency associated therewith; (d) analyzing the received signal strengths and noting any correlations of signal strengths with particular RFID tags and particular frequencies; and (e) determining from the correlations whether the particular RFID tag is moving coherently with the RFID reader. - View Dependent Claims (10, 11, 12, 13, 14)
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15. A method for identifying an RFID tag moving with an RFID reader, comprising:
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(a) transmitting by the reader over a period of time a plurality of reading signals at a plurality of frequencies within a transmission band; (b) receiving by the reader reply signals from any RFID tags within range of the reader; (c) determining over the plurality of reading signals a distribution of reading signals for which a specific RFID tag is within range of the reader; and (d) determining based on the distribution whether the particular RFID tag is moving coherently with the RFID reader. - View Dependent Claims (16, 17, 18)
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19. A system for identifying an RFID tag moving with an RFID reader, comprising:
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the RFID reader, wherein said RFID reader is configured to transmit over a period of time a plurality of reading signals; an RF receiver associated with said RFID reader, wherein said RFID receiver is configured to receive reply signals from any RFID tags within range of the reader; a processor associated with said RFID reader, wherein said processor is configured to determine at least one of; any consistencies of a received signal strength from a particular RFID tag correlated with a period of the plurality of reading signals; a correlation between a signal strength received from the particular RFID tag and a particular frequency of the plurality of reading signals; and a distribution of reading signals for which the particular RFID tag is within range of the reader. - View Dependent Claims (20, 21, 22)
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Specification