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 it 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 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.
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.
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Citations
8 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 it 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 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. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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Specification