Detecting a presence of near field communications (NFC) devices

摘要

A near field communications (NFC) device is disclosed that detects a presence of another NFC capable device within its magnetic field. The NFC device generates an unmodulated frequency varying detection sequence to generate a frequency varying magnetic field and/or a modulated frequency invariant detection sequence to generate a carrier-frequency invariant magnetic field. The NFC device samples these magnetic fields and compares these samples to various a priori known responses of various objects to determine whether another NFC device is present within the frequency varying magnetic field and/or the carrier-frequency invariant magnetic field.

主权项

1. A method for detecting a presence of a first near field communication (NFC) capable device, comprising:
generating, by a second NFC capable device, a carrier-frequency invariant magnetic field to detect for the presence of the first NFC capable device; comparing the magnetic field with an a priori known response of the first NFC capable device to the carrier-frequency invariant magnetic field; and determining the first NFC capable device to be present within an environment of the second NFC capable device when the carrier-frequency invariant magnetic field substantially matches the a priori known response.