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iceman

Administrator

Registered: 2013-04-25

Posts: 9,537

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Legic - deviceside enhancement

Reading the "hf legic" source on the device side and testing it with a tag is clear that the current implementation could do better distance reading than now.

https://github.com/Proxmark/proxmark3/b … crf.c#L203

The original authors hints at the " hi_read_rx_xcorr" fpga mode.   ie: FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_READER_RX_XCORR)   

Now, the two ppl who still know these things which I know of,  is  @piwi  and @holiman.
Piwi usually likes to discuss these things on the forum, so I made this post.

If I want to have a go at it, I'll need to know how do I use the      FpgaWriteConfWord(FPGA_MAJOR_MODE_HF_READER_RX_XCORR) data?

Last edited by iceman (2016-02-17 20:05:23)

piwi

Contributor

Registered: 2013-06-04

Posts: 704

Re: Legic - deviceside enhancement

hi_read_rx_xcorr.v implements an IQ demodulator. Have a look at e.g. I/Q Data for Dummies for an introduction. This is a very versatile demodulator and basis for SDRs.

See iso14443b.c how to use this FPGA mode. You will get alternating I and Q values from the FPGA (without being able to tell which is which).

iceman

Administrator

Registered: 2013-04-25

Posts: 9,537

Website

Re: Legic - deviceside enhancement

Another article about I/Q values.
http://hackaday.com/2017/05/16/if-the-i … s-read-on/