Differential radio frequency identification reader
First Claim
1. A method of radio frequency identification tag reading, comprising the steps of:
- generating a transmit field for powering and interrogating a radio frequency identification (RFID) tag to be read;
sensing a receive signal based on changes in the transmit field caused by the RFID tag; and
generating an amplified signal based on the difference between the receive signal and a reference signal indicative of the transmit field substantially unaffected by the RFID tag.
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Abstract
Systems and techniques for reading a radio frequency identification transponder are described. A transmit coil produces a transmit field to power and interrogate the transponder. A reference coil and a receive coil furnish inputs to a differential amplifier, balanced so that the differential amplifier produces a predetermined signal. The receive coil senses changes produced by the transponder, while the reference coil is relatively isolated from such changes. The differential amplifier produces an amplified signal based on the difference between the inputs from the receive coil and the reference coil, so that the signal produced by the differential amplifier is based on the field effect changes produced by the transponder.
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Citations
7 Claims
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1. A method of radio frequency identification tag reading, comprising the steps of:
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generating a transmit field for powering and interrogating a radio frequency identification (RFID) tag to be read;
sensing a receive signal based on changes in the transmit field caused by the RFID tag; and
generating an amplified signal based on the difference between the receive signal and a reference signal indicative of the transmit field substantially unaffected by the RFID tag. - View Dependent Claims (2, 3)
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4. A radio frequency identification tag reader for reading a radio frequency identification (RFID) tag to be read, comprising:
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means for emitting a transmit field to interrogate the RFID tag;
means for sensing the transmit field substantially unaffected by the RFID tag;
means for sensing changes in the transmit field resulting from an effect caused by the RFID tag;
means for isolating the effect caused by the RFID tag and amplifying said isolated effect. - View Dependent Claims (5, 6, 7)
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Specification