Interrogator and interrogation system employing the same
First Claim
1. A control and processing system, comprising:
- a correlation subsystem configured to correlate a reference code at a first clock rate with a reply code from a radio frequency identification (RFID) object, correlate said reference code at a second clock rate with said reply code from said RFID object and provide correlation signals therefrom, said correlation subsystem being configured to correlate employing a Fast Fourier Transform and a convolution theorem, said first clock rate being an expected clock rate and said second clock rate varying therefrom; and
a decision subsystem configured to verify a presence of said RFID object as a function of said correlation signals.
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Accused Products
Abstract
An interrogator, methods of discerning the presence of an object, and interrogation systems employing the same. In one embodiment, the interrogation systems include multiple interrogators that communicate with a base command unit to track a location of an object. In another embodiment wherein the object is an RFID object (e.g., an object with an RFID tag), the interrogators employ signal processing techniques such as precharging the RFID object, and correlating a reference code with a reply code from the RFID object using selected techniques to increase a sensitivity of the interrogator, especially for adverse environments. In other embodiments, the interrogation systems include variations of metal instruments and sponges employed therewith. In yet another embodiment, the interrogation system includes metal interrogators capable of discerning the presence of a metal object, especially in a presence of another metal object.
262 Citations
30 Claims
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1. A control and processing system, comprising:
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a correlation subsystem configured to correlate a reference code at a first clock rate with a reply code from a radio frequency identification (RFID) object, correlate said reference code at a second clock rate with said reply code from said RFID object and provide correlation signals therefrom, said correlation subsystem being configured to correlate employing a Fast Fourier Transform and a convolution theorem, said first clock rate being an expected clock rate and said second clock rate varying therefrom; and a decision subsystem configured to verify a presence of said RFID object as a function of said correlation signals. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A method of verifying a presence of a radio frequency identification (RFID) object, comprising:
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correlating a reference code at a first clock rate with a reply code from an RFID object, correlating said reference code at a second clock rate with said reply code from said RFID object and providing correlation signals therefrom, said correlating employing a Fast Fourier Transform and a convolution theorem, said first clock rate being an expected clock rate and said second clock rate varying therefrom; and verifying a presence of said RFID object as a function of said correlation signals. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20)
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21. An interrogation system, comprising:
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a radio frequency identification (RFID) object configured to provide a reply code; and an interrogator, including; a correlation subsystem configured to correlate a reference code at a first clock rate with said reply code, correlate said reference code at a second clock rate with said reply code and provide correlation signals therefrom, said correlation subsystem being configured to correlate employing a Fast Fourier Transform and a convolution theorem, said first clock rate being an expected clock rate and said second clock rate varying therefrom, and a decision subsystem configured to verify a presence of said RFID object as a function of said correlation signals. - View Dependent Claims (22, 23, 24, 25, 26, 27, 28, 29, 30)
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Specification