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#1 2018-08-21 15:21:59

Tom
Contributor
Registered: 2018-08-17
Posts: 8

looking for 13.56 Mhz demodulator ic

Hi.
I'm building a Raspberry pi based iclass sniffer and I need a 13.56 Mhz demodulation ic for the analog stage.
Any recommendation ?
Thanks!

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#2 2018-08-23 17:35:09

atmel9077
Contributor
Registered: 2017-06-25
Posts: 46

Re: looking for 13.56 Mhz demodulator ic

(Warning: this is just an idea that has not be tested) Maybe a MFRC522 module. It's supposed to support only ISO14443A however you can get the digitized complex baseband signal by repeatedly reading the TestADCReg register. This register is a byte where the 4 MSbs and the 4 LSBs form two values called "I" and "Q". sqrt((i*i)+(q*q)) will give you the amplitude (envelope) of the signal (comprised between 0 and sqrt(32). This method has the advantage of being incredibly cheap (RC522 module is less than $5) and does not require anyother circuits except the module. Another option of course is to connect a (properly tuned) antenna to an envelope detector, then smooth the envelope signal with a simple RC lowpass filter and feed it to an ADC. These methodes only demodulates the signals, you still have to perform the demodulation in software.

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#3 2018-08-24 00:24:31

0xFFFF
Administrator
From: Vic - Australia
Registered: 2011-05-31
Posts: 632

Re: looking for 13.56 Mhz demodulator ic

@atmel9077 is correct. 522 is capable of doing this and there are others from NXP. They are quite capable but I'm not sure if I'd recommend any.
TRF7970A from TI is easier to use for this case and the documentation required is not under NDA.

*Also, couldn't help but read your post in Marvin the Martian's voice.

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