Evaluation of the coupling factor of an electromagnetic transponder by capacitive detuning
First Claim
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1. A method for evaluating a current coupling factor between an electromagnetic transponder and a terminal, comprising acts of:
- obtaining, by the electromagnetic transponder, a ratio between data representative of a voltage across an oscillating circuit of the transponder for two capacitance values of the oscillating circuit; and
comparing, by the electromagnetic transponder, the ratio with at least one threshold to provide a result indicative of the current coupling factor, wherein the at least one threshold is selected based on one or both of the two capacitance values.
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Abstract
A method for evaluating the current coupling factor between an electromagnetic transponder and a terminal, and a transponder implementing this method, wherein a ratio between data representative of a voltage across an oscillating circuit of the transponder and obtained for two capacitance values of the oscillating circuit is compared with one or several thresholds.
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Citations
37 Claims
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1. A method for evaluating a current coupling factor between an electromagnetic transponder and a terminal, comprising acts of:
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obtaining, by the electromagnetic transponder, a ratio between data representative of a voltage across an oscillating circuit of the transponder for two capacitance values of the oscillating circuit; and comparing, by the electromagnetic transponder, the ratio with at least one threshold to provide a result indicative of the current coupling factor, wherein the at least one threshold is selected based on one or both of the two capacitance values. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A method for evaluating a current coupling factor between a terminal and an electromagnetic transponder having an oscillating circuit, comprising acts of:
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measuring, by the transponder, a first value representative of a voltage across the oscillating circuit with a first capacitance value associated with the oscillating circuit; measuring, by the transponder, a second value representative of the voltage across the oscillating circuit with a second capacitance value associated with the oscillating circuit; determining, by the transponder, a ratio of the first value to the second value; and comparing, by the transponder, the ratio to at least one threshold, wherein a result of the comparing is indicative of the current coupling factor, and wherein the at least one threshold is selected based on one or both of the two capacitance values. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24)
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25. An electromagnetic transponder comprising:
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an oscillating circuit; and a processing circuit configured to evaluate a current coupling factor between a terminal and the electromagnetic transponder, wherein the processing circuit is configured to; measure a first value representative of a voltage across the oscillating circuit with a first capacitance value associated with the oscillating circuit; measure a second value representative of the voltage across the oscillating circuit with a second capacitance value associated with the oscillating circuit; determine a ratio of the first value to the second value; and compare the ratio to at least one threshold, wherein a result of the comparison is indicative of the current coupling factor, and wherein the at least one threshold is selected based on one or both of the two capacitance values. - View Dependent Claims (26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37)
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Specification