Decoding NFC-F Based on Manchester-encoded ASK Modulation
应用文章
Decoding NFC-F communication and verifying proper exchange of data between poller and listener devices is often required during the turn-on and debug phase of development. NFC-F is based on amplitude-shift keying (ASK) modulation with Manchester encoding. Keysight’s InfiniiVision 3000T X- and 4000 X-Series oscilloscopes can automatically demodulate and then decode NFC-F (212 kbps) and NFC-F (424 kbps) communication between polling and listening devices if licensed with the user-definable Manchester/NRZ trigger and decode option (DSOXT3NRZ/DSOX4NRZ). This application note begins with an overview of Manchester encoding and explains how to capture NFC signals using an RF “pick-up” antenna. This document then provides step-by-step instructions on how to setup the oscilloscope to properly decode and trigger on NFC-F poller and listener communication for two specific cases. CASE 1 documents how to decode and trigger on NFC-F (212 kbps) signals based on “obverse” polarity encoding with both poller and listener modulation “within” the non-modulated carrier amplitude. CASE 2 documents how to decode and trigger on NFC-F (424 kbps) signals based on “reverse” polarity encoding with poller modulation “within” the non-modulated carrier amplitude and listener modulation “above” the non-modulated carrier amplitude.