Near field communication apparatus
First Claim
1. A system for use in a near field communications (NFC) reader for detecting the presence of an NFC tag, the NFC reader having an antenna tuned to a resonant frequency, the system comprising:
- a first signal generator for generating a carrier signal whose frequency varies about the resonant frequency;
a second signal generator for generating a modulating signal for modulating the carrier signal;
a modulator for modulating the carrier signal with the modulating signal;
a driver for driving the antenna with the modulated signal; and
a detection system for detecting harmonics of the modulating signal in a signal present in the antenna as a result of the modulated signal;
wherein the detection system is configured to generate an output when a third or higher order harmonic is detected.
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Accused Products
Abstract
A system for use in a near field communications (NFC) reader, for detecting the presence of an NFC tag, is disclosed. The NFC reader has an antenna tuned to a resonant frequency. The system comprises: a first signal generator for generating a carrier signal whose frequency varies about the resonant frequency; a second signal generator for generating a modulating signal for modulating the carrier signal; a modulator for modulating the carrier signal with the modulating signal; a driver for driving the antenna with the modulated signal; and a detection system for detecting harmonics of the modulating signal in a signal present in the antenna as a result of the modulated signal. The detector is configured to generate an output when a third or higher order harmonic is detected.
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Citations
12 Claims
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1. A system for use in a near field communications (NFC) reader for detecting the presence of an NFC tag, the NFC reader having an antenna tuned to a resonant frequency, the system comprising:
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a first signal generator for generating a carrier signal whose frequency varies about the resonant frequency; a second signal generator for generating a modulating signal for modulating the carrier signal; a modulator for modulating the carrier signal with the modulating signal; a driver for driving the antenna with the modulated signal; and a detection system for detecting harmonics of the modulating signal in a signal present in the antenna as a result of the modulated signal; wherein the detection system is configured to generate an output when a third or higher order harmonic is detected. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method for use in a near field communications (NFC) reader for detecting the presence of an NFC tag, the NFC reader having an antenna tuned to a resonant frequency, the method comprising:
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generating a carrier signal whose frequency varies about the resonant frequency; generating a modulating signal for modulating the carrier signal; modulating the carrier signal with the modulating signal; driving the antenna with the modulated signal; detecting harmonics of the modulating signal in a signal present in the antenna as a result of the modulated signal; and generating an output when a third or higher order harmonic is detected. - View Dependent Claims (11, 12)
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Specification