RFID_Demod [HW]

Challenge description

Solution

At first, I confused it with the trace files that a proxmark stores. Later, after quite long, when nothing worked out, taking a closer look at the wav file, something stood out.

Initial Analysis

I opened the file on Audacity to take a look at it. At a first glance, it seemed like noise. Zooming in a bit, we can see some patterns.

To understand the format of the signal, I had to dig up the datasheet and find something that made sense of this trace. The datasheet can be found on proxmark3’s github

Getting the DATA bits

Manually writing and separating the bits according to the datasheet.

10 0 10110001011000110101110010101101 011
     |<----------- data ----------->|

Converting this to UPPERCASE_HEX, we get B1635CAD.