Determining speeds of radio frequency tags
First Claim
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1. A method, comprising:
- sampling a Radio Frequency (RF) signal from an RFID tag at a plurality of different times as the RFID tag approaches an RFID reader and recedes from the RFID reader;
determining a phase of the RF signal for each of the plurality of different times based, at least in part, on the sampled RF signal;
determining a slope of a Doppler curve based, at least in part, on the determined phase for the sampled RF signal for each of the plurality of different times; and
determining a speed of the RFID tag based, at least in part, on the slope of the Doppler curve.
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Abstract
The present disclosure is directed to determining speeds of radio frequency tags. In some implementations, a method includes sampling a Radio Frequency (RF) signal from an RFID tag at a plurality of different times as the RFID tag approaches an RFID reader and recedes from the RFID reader. A phase of the RF signal is determined for each of the plurality of different times based, at least in part, on the sampled RF signal. A speed of the RFID tag is determined based, at least in part, on the determined phase for the sampled signal for each of the plurality of different times.
240 Citations
17 Claims
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1. A method, comprising:
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sampling a Radio Frequency (RF) signal from an RFID tag at a plurality of different times as the RFID tag approaches an RFID reader and recedes from the RFID reader; determining a phase of the RF signal for each of the plurality of different times based, at least in part, on the sampled RF signal; determining a slope of a Doppler curve based, at least in part, on the determined phase for the sampled RF signal for each of the plurality of different times; and determining a speed of the RFID tag based, at least in part, on the slope of the Doppler curve. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A RFID reader, comprising:
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an antenna that samples a RF signal from an RFID tag at a plurality of different times as the RFID tag approaches an RFID reader and recedes from the RFID reader; an arctangent module that determines a phase of the RF signal for each of the plurality of different times based, at least in part, on the sampled RF signal; and a phase module that determines a slope of a Doppler curve based, at least in part, on the determined phase for the sampled RF signal for each of the plurality of different times and determines a speed of the RFID tag based, at least in part, on the slope of the Doppler curve. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16)
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17. A system, comprising:
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a means for sampling a Radio Frequency (RF) signal from an RFID tag at a plurality of different times as the RFID tag approaches an RFID reader and recedes from the RFID reader; a means for determining a slope of a Doppler curve based, at least in part, on the determined phase for the sampled RF signal for each of the plurality of different times; and a means for determining a speed of the RFID tag based, at least in part, on the slope of the Doppler curve.
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Specification