Importance

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Abstract

A system and method to distinguish an RFID tag which is moving synchronously with an RFID reader from other RFID tags which are not moving synchronously with the reader. In one embodiment, the reader emits read signals at a fixed frequency with a corresponding period. A determination is made by the RFID reader as to the signal strengths received from an RFID tag at time intervals which are integer multiples of the half-period of the signal. Signal strengths from the tag which are the same or substantially the same at these prescribed measurement intervals are taken as an indication that the tag is moving synchronously with the RFID reader. In an alternative embodiment, the frequency of the read signals may vary over time. Correlations between received tag signal strengths with particular frequencies are an indication that the RFID tag is moving synchronously with the RFID reader.

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First Claim