Method and apparatus for efficiently querying and identifying multiple items on a communication channel
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Abstract
Systems and methods for efficiently querying and identifying multiple items on a communication channel are disclosed. The invention is well suited to use with radio frequency identification with interrogation devices and systems that identify radio frequency identification transponders. A depth-first tree traversal protocol algorithm, including commands and symbols, is used to more efficiently interrogate a plurality of transponders in a short amount of time.
53 Citations
30 Claims
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1-29. -29. (canceled)
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30. A method for interrogating objects to be identified over a communication medium, wherein the objects provide predetermined responses indicative of object identification numbers and each include a counter, the method comprising the steps of:
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sending interrogation signals to and receiving responses from the objects over the communication medium, the interrogation signals operating to interrogate a single digit from the objects to be identified;
recording incomplete identification numbers whenever two or more predetermined responses are received from the objects;
retrieving incomplete identification numbers whenever two or more predetermined responses are received from the objects;
sending a signal to the objects to cause the objects to selectively add a number to their respective counter, wherein the number is determined by each object and is dependent upon one or more previous responses of the object to interrogation signals;
sending a signal to the objects to cause the objects to selectively subtract a number from their respective counter, wherein the number is determined by each object and is dependent upon one or more previous responses of the object to the interrogation signals; and
recording complete identification numbers as they are determined.
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Specification