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Motorcycle "RFID" HITAG2 key emulation with microcontroller
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kilohercas:
Hello, My understanding that in this forum where are few smart people, and I need your help :)
I am making system for my motorcycle that could capture and replay emergency RFID key that is used to start motorcycle once. So basically I would be able to start my motorcycle with phone if my key get stolen or lost.
So I was probing excitation coil on my motorcycle by directly attaching scope to it. I was able to capture unlock signals, problem is, this is not what I expected
Problem is that signals are the same amplitude. IF RFID tag is re transmitting signal, it should be lower amplitude, not 60Vpp, while if it shorting magnetic field, Modulation should not go to zero.
So question, how does communication is working, and why I can't see it in scope?
Miti:
I think that’s pretty much a perfect capture of the communication between the exciter and the card. You’re on 10V per division on the scope so probably it doesn’t go to zero, but by shorting the coil in the card, you throw everything out of resonance and the peak voltage on the LC should drop significantly, depending how close the card is.
Edit: Make a coil, connect the ends together, and move it close to the exciter. See how that changes the amplitude.
kilohercas:
That's the problem, shorting field with loop does not effect much exciter amplitude captured
Also if I place key further from coil, amplitude remains the same.
This is why it is puzzling me... :-//
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