Method and system for standing wave detection for radio frequency identification marker readers
First Claim
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1. A system for determining the absence and presence of items in an RFID interrogation zone, the system comprising:
- at least one RFID reader transmitting interrogation signals in an interrogation zone, wherein each RFID reader transmits interrogation signals having a forward amount of RF energy and receives response signals from the items in the interrogation zone having a reflected amount of RF energy; and
a detection circuit, the detection circuit determining the presence and absence of items within the interrogation zone based at least in part on the reflected amount of RF energy.
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Abstract
A method and system for determining the absence and presence of items in an RFID interrogation zone. At least one RFID reader transmits interrogation signals in an interrogation zone. Each RFID reader transmits interrogation signals having a forward amount of RF energy and receives response signals from the items in the interrogation zone having a reflected amount of RF energy. A detection circuit determines the presence and absence of items within the interrogation zone based at least in part on the reflected amount of RF energy.
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Citations
23 Claims
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1. A system for determining the absence and presence of items in an RFID interrogation zone, the system comprising:
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at least one RFID reader transmitting interrogation signals in an interrogation zone, wherein each RFID reader transmits interrogation signals having a forward amount of RF energy and receives response signals from the items in the interrogation zone having a reflected amount of RF energy; and a detection circuit, the detection circuit determining the presence and absence of items within the interrogation zone based at least in part on the reflected amount of RF energy. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A method for determining the absence and presence of items within an RFID interrogation zone, the method comprising:
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transmitting interrogation signals within the interrogation zone, the interrogation signals having a forward RF energy; receiving responsive signals in response to the transmitted interrogation signals, the response signals having a reflected RF energy; and analyzing the reflected RF energy to determine whether any items within the interrogation zone have been removed. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20, 21)
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22. An RFID reader for determining the absence and presence of items in an RFID interrogation zone, the reader comprising:
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an RF source for generating RF signals; an antenna coupled to the RF source, the antenna transmitting forward RF energy within the RFID interrogation zone; a receiver for receiving reflected RF energy from items in the RFID interrogation zone; and a detection circuit, the detection circuit comparing an amount of the reflected RF energy with an amount of the forward RF energy at the antenna to obtain a standing wave ratio, the standing wave ratio usable to determine if items have been removed from the interrogation zone. - View Dependent Claims (23)
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Specification