PREAMBLE DETECTION CIRCUIT, AND DETECTION METHOD THEREIN

摘要

PROBLEM TO BE SOLVED: To solve the problem wherein radio tag reader/writers including conventional preamble detection circuits have weak reception sensitivity in communication with radio tags.

SOLUTION: The preamble detection circuit is used for the radio tag reader/writers for performing noncontact communication with the radio tag. The preamble detection circuit includes a reference data output circuit 201 for outputting reference data corresponding to the radio tag, and a comparison circuit 202 for comparing a data pattern of a preamble included in a signal transmitted from the radio tag with that of the reference data and for determining that the preamble has been read when the number of bits different in both the data patterns is not more than N (N is a natural number), thus improving the reception sensitivity in the communication with the radio tag by such a circuit configuration.

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