Validation of the presence of an electromagnetic transponder in the field of an amplitude demodulation reader
First Claim
1. A terminal for generating an electromagnetic field adapted to communicating with at least one transponder entering this field, including:
- an oscillating circuit adapted to being excited by a high-frequency remote supply signal of the transponder;
an amplitude demodulator for detecting possible data transmitted by the transponder by modulating, at the rate of a sub-carrier, a load that the transponder forms on the terminal'"'"'s oscillating circuit;
and including;
means for regulating a signal phase in the terminal'"'"'s oscillating circuit in response to a reference value, the means having a long response time as compared to the rate of said sub-carrier;
means for measuring variables linked to a current in the oscillating circuit and to a voltage thereacross; and
means for comparing present values of these variables to predetermined values.
1 Assignment
0 Petitions
Accused Products
Abstract
A terminal for generating an electromagnetic field adapted to communicating with at least one transponder, and a method for controlling such a terminal including: an oscillating circuit adapted to being excited by a remote supply signal of the transponder; an amplitude demodulator for detecting possible data transmitted by the transponder; circuitry for regulating the signal phase in the terminal'"'"'s oscillating circuit on a reference value; circuitry for measuring variables linked to the current in the oscillating circuit and to the voltage thereacross; and circuitry for comparing current values of these variables to predetermined values, to determine the presence of a transponder.
102 Citations
33 Claims
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1. A terminal for generating an electromagnetic field adapted to communicating with at least one transponder entering this field, including:
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an oscillating circuit adapted to being excited by a high-frequency remote supply signal of the transponder; an amplitude demodulator for detecting possible data transmitted by the transponder by modulating, at the rate of a sub-carrier, a load that the transponder forms on the terminal'"'"'s oscillating circuit; and including; means for regulating a signal phase in the terminal'"'"'s oscillating circuit in response to a reference value, the means having a long response time as compared to the rate of said sub-carrier; means for measuring variables linked to a current in the oscillating circuit and to a voltage thereacross; and means for comparing present values of these variables to predetermined values. - View Dependent Claims (2, 3, 4, 27)
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5. A method for controlling a terminal for generating an electromagnetic field adapted to communicating with at least one transponder entering this field, the terminal including:
- an oscillating circuit adapted to being excited by a high-frequency remote supply signal of the transponder;
an amplitude demodulator for detecting possible data transmitted by the transponder by demodulating, at the rate of a sub-carrier, a load that it forms on the terminal'"'"'s oscillating circuit;
means for regulating a signal phase in the terminal'"'"'s oscillating circuit in response to a reference value having a long response time as compared to said sub-carrier;
means for measuring variables linked to a current in the oscillating circuit and to a voltage thereacross; and
means for comparing present values of these variables to predetermined values the method comprising;exploiting the results of the comparison means to detect a presence of a transponder in the terminal'"'"'s field. - View Dependent Claims (6, 7, 8)
- an oscillating circuit adapted to being excited by a high-frequency remote supply signal of the transponder;
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9. A system for generating an electromagnetic field adapted to communicate with at least one transponder entering the electromagnetic field, comprising:
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an oscillating circuit adapted to being excited by a high-frequency remote supply signal of the transponder; an amplitude demodulator to detect possible data transmitted by the at least one transponder by demodulating a load formed on the oscillating circuit by the at least one transponder; and detection circuitry to detect that the at least one transponder is present in the electromagnetic field even if the amplitude demodulator has not detected any data transmitted by the at least one transponder. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16, 17, 28, 29, 30)
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18. A method of detecting a presence of at least one transponder within an electromagnetic field generated by a terminal that comprises an oscillating circuit, the method comprising:
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determining that the at least one transponder is not present in the electromagnetic field by performing amplitude demodulation on the oscillating circuit; and ascertaining whether the determination is correct based on a voltage measured across the oscillating circuit and a current measured in the oscillating circuit. - View Dependent Claims (19, 20, 21, 22, 23, 24, 25, 26, 31, 32, 33)
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Specification