Proxmark3 community

somemadeupname

Contributor

From: Western Australia

Registered: 2016-05-25

Posts: 19

UHF tag communication

Hi all,

Has anyone played around with reading / emulating UHF tags at all? I'm trying to wrap my head around what kind of hardware implementation would be required - e.g. for a PM4. Would standard SDR like, full-duplex RF communication be compatible?

There are plenty of devices (garage door openers, remote keyless entry, etc.) that use a RF transmitter, so SDR works fine for those. I'm worried about the UHF RFID tags that use backscatter to communicate with the reader - basically, applying a load to the antenna to change the signal that gets reflected back, in a similar way that LF and HF are changing the load on the inductor to communicate.

I also came across a series of white-papers that discuss using a combination of resistors and capacitors as the load to enable low power QAM backscatter communication (changing both amplitude and phase of the reflected signal). However, the method used doesn't seem to be particularly flexible for a device that we'd want to be able to emulate / communicate with all tags...