Patent ID: 9698871
Date: 2017-07-04
CPC Classifications: G06K,H04B

Claim:
1. A near field communications (NFC) apparatus comprising: a transmit antenna; a signal source configured to generate a chirp signal which is transmitted using the transmit antenna, the chirp signal having a frequency that increases from an initial frequency to a final frequency over a period of time; a receive section coupled to the transmit antenna and configured to detect changes in an input impedance of the transmit antenna as the frequency of the chirp signal changes; and a processor configured to determine, based on the detected changes in the input impedance of the transmit antenna, whether a compatible NFC device is within an operating range of the NFC apparatus and whether the compatible NFC device is either a passive NFC device or an active NFC device; wherein the receive section is configured to detect a change in a real part or an imaginary part of the input impedance of the transmit antenna, and wherein the processor is configured to: