[Hackrf-dev] Help with NFC decoding.

[evilsocket]

Hi everyone, I'm trying to decode NFC-A ( 13.56Mhz ) data from the HackRF
using C/C++ code instead of GNU Radio, mostly because I want to understand
the logic of demodulation and decoding itself instead of using pre made
tools.

As far as I read on the web, NFC uses ASK modulation, so what I'm currently
doing on the rx callback is taking each IQ, computing amplitude,
thresholding it to get a 1 or 0 bit, appending each bit to a bit stream and
print the hex value every 8 bits, you can see the code here:

https://github.com/evilsocket/hackrfpp/blob/master/main.cpp#L63

Although I don't know if the actual values I'm getting are correct, I can
definitely see some "activity" while putting my android phone ( with a NFC
reader app ) near a NFC tag ( with the hackrf antenna between them ).

I have two questions:

1. Am I on the right track or am I doing everything wrong? :)
2. If what I'm doing is correct, could someone point me to the right
documentation on how to decode those hex streams I get?


Thanks.



_________________________
Simone '*evilsocket*' Margaritelli
http://www.evilsocket.net/  <http://www.evilsocket.net/>
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