Frequency synchronization for a near field communication (NFC) device

摘要

A first near field communication (NFC) device is disclosed that synchronizes a first carrier wave of the first NFC device to a second carrier wave of a second NFC device. The first NFC device observes a magnetic field having the first carrier wave modulated with information corresponding to the first NFC device and the second carrier wave modulated with information corresponding to the second NFC device. The first NFC device isolates the information corresponding to the second NFC device from the combined sequence of information to determine a frequency error and/or a phase error between the carrier waves. Finally, the first NFC device adjusts the frequency of the first carrier wave in accordance with the first frequency error and/or the phase of the first carrier wave in accordance with the first phase error to synchronize the carrier waves.

主权项

1. A first near field communication (NFC) device, comprising:
a modulator configured to modulate first information onto a first carrier wave in accordance with a bipolar modulation scheme; a demodulator configured to demodulate a recovered communication signal in accordance with the bipolar modulation scheme to provide a recovered sequence of bits, the recovered communication signal including the first information modulated onto the first carrier wave and second information modulated onto a second carrier wave by a second NFC device; and a controller configured to:
determine an integration window using a pattern matching procedure,integrate the recovered sequence of bits over the integration window to isolate the second information from the recovered sequence of bits,measure a characteristic of the isolated second information to determine an error between the first carrier wave and the second carrier wave, andcause the first carrier wave to be adjusted in accordance with the error to substantially synchronize the first carrier wave and the second carrier wave.