Device detection using load modulation in near-field communications
First Claim
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1. A method of establishing communications between near-field communications (NFC) devices, the method comprising:
- at a first NFC device;
first, modulating a load in a transceiver of the first NFC device to signal its presence to other NFC devices without using a carrier signal;
then, while still modulating the load, detecting a waveform transmitted on an NFC channel by a second NFC device; and
in response to detecting the waveform while modulating the load, communicating with the second NFC device over the channel.
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Abstract
First and second NFC devices both seek to determine whether the other device is present and available for communication across an NFC channel. The first NFC device modulates a load in its transceiver. The second NFC device transmits a waveform. If the first NFC device detects the waveform while modulating its load, and if the second NFC device detects the load modulation while transmitting the waveform, then the two NFC devices initiate communication in accordance with a communication protocol.
13 Citations
30 Claims
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1. A method of establishing communications between near-field communications (NFC) devices, the method comprising:
at a first NFC device; first, modulating a load in a transceiver of the first NFC device to signal its presence to other NFC devices without using a carrier signal; then, while still modulating the load, detecting a waveform transmitted on an NFC channel by a second NFC device; and in response to detecting the waveform while modulating the load, communicating with the second NFC device over the channel. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method of establishing communications between near-field communications (NFC) devices, the method comprising:
at a first NFC device; first, transmitting a waveform on an NFC channel; then, while still transmitting the waveform, detecting a presence of a second NFC device by detecting modulation of a load in the second NFC device, the load modulation independent of the waveform and independent of a carrier signal; and in response to detecting the load modulation while transmitting the waveform, communicating with the second NFC device over the channel. - View Dependent Claims (9, 10, 11, 12, 13, 14)
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15. A near-field communications (NFC) device, comprising:
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an NFC antenna; a transmitter to modulate a load, coupled to the NFC antenna, to signal its presence to other NFC devices without using a carrier signal; a receiver to receive a waveform from another NFC device via the NFC antenna while the transmitter modulates the load; and a controller to initiate a first portion of a protocol for communicating with the other NFC device in response to the receiver receiving the waveform while the transmitter modulates the load. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22)
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23. A non-transitory computer-readable medium storing instructions that, when executed by one or more processors of a first near-field communications (NFC) device, cause the first NFC device to perform operations comprising:
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first, modulating a load in a transceiver of the first NFC device to signal its presence to other NFC devices without using a carrier signal; then, while still modulating the load, detecting a waveform transmitted on an NFC channel by a second NFC device; and in response to detecting the waveform while modulating the load, communicating with the second NFC device over the channel. - View Dependent Claims (24, 25, 26, 27, 28, 29, 30)
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Specification