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#1 2020-05-19 01:52:54

thetruth
Contributor
Registered: 2020-05-17
Posts: 4

Help in understanding how CmdHIDdemodFSK works?

I've traced through a few functions to go from raw HID waveform --> Card ID.

The steps I've seen so far:

1. FSK decode the raw HID waveform (lf hid demod; data printdemodbuffer;)
2. Find the preamble for Manchester (00011101)
3. After preamble, Manchester decode the rest (data manrawdecode)
4. Decode Manchester decoded data into a card ID

It's step 4 that I'm having trouble with.

The Manchester decoded data I have is:

1111110111111111101111110001011100010011011

The Card ID is 18276.

I've read through the code in function CmdHIDdemodFSK but I'm having a hard time understanding how hi and lo are used in this process.

Could someone walk me through the process? Thanks!

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#2 2020-05-19 08:43:58

mwalker
Moderator
Registered: 2019-05-11
Posts: 318

Re: Help in understanding how CmdHIDdemodFSK works?

This is more just a hint for things to try to see what happens.

Your decoded data : 1111110111111111101111110001 011100010011011
Your Card ID in bin:                             100011101100100

mmm maybe its inverted.

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