I want to perform offline sniffing for an ISO 15693 reader using my Proxmark3 Easy device. When I place the ISO 15693 (NXP ICODE SLIX2) card on the Proxmark reader and scan it very closely with my phone’s application, I can successfully sniff the data.
However, the actual device I want to sniff can read my ISO 15693 card from 10 cm away, but my Proxmark, positioned right behind it, is unable to capture any sniffing data. I also tried placing the Proxmark between the reader and the card, but the sniffing data still shows as zero.
Should I use a different positioning? Are there any software settings I can adjust for the antenna?
Have you tried placing the proxmark directly against the reader? What the proxmark is doing is trying to read data from the magnetic field produced by the reader. Since both the card and proxmark are operating in passive mode, placing the proxmark against the reader should get you data even if the card is far away because the magnetic field emitted from the reader is what is being modulated.
Feeling that, I would place the proxmark against the reader and place a metal sheet or shield over top of that. Then present the card very close to the shield, but due to the shield it will not be read. Then quickly yank the shield away. This should get the best coupling between card and reader with the proxmark in between.