Electromagnetic transponder reader
First Claim
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1. A circuit for demodulating a signal transmitted by an electromagnetic transponder, comprising:
- a sensor of a variable which is a function of the load formed by the transponder on an oscillating circuit;
a phase demodulator and an amplitude demodulator at least functionally in parallel and receiving a signal coming from said sensor;
a summer of the results provided by said demodulators; and
a delay element in series with a first one of said demodulators, to compensate for a possible propagation time difference therebetween.
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Abstract
A method and a circuit for demodulating a signal transmitted by an electromagnetic transponder, including a sensor of a variable which is a function of the load formed by the transponder on an oscillating circuit, a phase demodulator and an amplitude demodulator at least functionally in parallel and receiving a signal coming from said sensor, a summer of the results provided by the demodulators, and a delay element in series with a first one of said demodulators, to compensate for a possible propagation time difference therebetween.
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Citations
12 Claims
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1. A circuit for demodulating a signal transmitted by an electromagnetic transponder, comprising:
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a sensor of a variable which is a function of the load formed by the transponder on an oscillating circuit;
a phase demodulator and an amplitude demodulator at least functionally in parallel and receiving a signal coming from said sensor;
a summer of the results provided by said demodulators; and
a delay element in series with a first one of said demodulators, to compensate for a possible propagation time difference therebetween. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method for demodulating a signal transmitted by an electromagnetic transponder, comprising:
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measuring a variable which is a function of the load formed by the transponder on an oscillating circuit;
demodulating in phase the measured signal;
demodulating in amplitude the measured signal;
delaying a first result of at least one of the demodulations with respect to the other;
summing up the results of the two demodulations; and
regulating the delay brought to said first demodulation result according to the result of the sum integration. - View Dependent Claims (11, 12)
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Specification