METHOD FOR DETECTING PRESENCE OF CONTACTLESS COMMUNICATION ELEMENT BY TERMINAL

摘要

PROBLEM TO BE SOLVED: To provide a method for detecting presence of a transponder in an electromagnetic field even when the transponder and/or a terminal oscillating circuit is not tuned.

SOLUTION: In the method for detecting presence of a contactless communication element by the terminal forming the electromagnetic field and having the oscillating circuit, the oscillating circuit of the terminal is excited at a variable frequency between two values surrounding a nominal tuning frequency of the oscillating circuit; and a signal representative of the load of the oscillating circuit is interpreted to detect that a reference voltage has not been exceeded, which indicates the presence of the element in the field.

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