0
\$\begingroup\$

Most cashless payment systems using RFID seem to use HF (13.5MHz) tags. My questions are:

  1. Why do RFID wristbands used for cashless payments use HF over LF transponders? Some access control applications seem to use LF transponders (tags) and I would have thought that the use-case for cashless payments (proximity of access card/wristband to a reader) is similar.

  2. There are a multitude of standards for contactless ICs:

    • ISO14443 for proximity contanctless cards [even within this, I believe there are variations.]
    • ISO15693 for vicinity contactless cards
    • ISO18000 set of standards for RFIDs EPCglobal Class 1 Gen 2 (=18000-6C)

    Would I be right in understanding that for cashless payments using RFID wristbands, I should be looking at ISO14443 compliant tags (i.e., HF tags that have a range of ~10cm)?

  3. Some existing cashless payment systems (for example, the one described in this example) seem to require a "double-tap" - once for reading wristband data and the second, for writing back (balance amount). Is a double-tap unavoidable?

EDIT: Some over-zealous moderation has resulted in this question being put on hold. I had done my research and had asked very specific questions, each of which could have been answered by someone knowledgeable in the field, with a sentence or two, so I don't understand the rationale for moderation. Luckily for me, a kind soul answered my questions just in time. Thank you Nils!

\$\endgroup\$

closed as too broad by Leon Heller, Andy aka, PeterJ, Null, Daniel Grillo Oct 20 '15 at 1:59

Please edit the question to limit it to a specific problem with enough detail to identify an adequate answer. Avoid asking multiple distinct questions at once. See the How to Ask page for help clarifying this question. If this question can be reworded to fit the rules in the help center, please edit the question.

  • \$\begingroup\$ #4 removed, because it's off-topic for EE.SE . #1 through #3 may have to be posted as separate questions (perhaps with links to each other). An overall snag with this post is that it deals with a mix of RF and financial transaction requirements (such as security). \$\endgroup\$ – Nick Alexeev Oct 19 '15 at 18:56
  • \$\begingroup\$ I'll leave the debate over relevance to others. But I believe the choice of RF in wristbands is because RF performs better around high water content objects. eg fruit and bodies :) \$\endgroup\$ – BenG Oct 19 '15 at 21:34
  • 1
    \$\begingroup\$ Sorry. That should have been HF not RF. \$\endgroup\$ – BenG Oct 29 '15 at 21:14
2
\$\begingroup\$

Why do RFID wristbands used for cashless payments use HF over LF transponders?

There was an easy migration path from contact based chip-cards to HF contactless. On the application level some of the HF tags support the same ISO7816-4 protocol that the chip based credit-cards understand.

For LF tags no such simple update was possible. That's why HF was the natural choice.

Would I be right in understanding that for cashless payments using RFID wristbands, I should be looking at ISO14443 compliant tags.

Yes, if you want to interact with existing point-of-sales terminals you're pretty forced to use ISO14443-A and ISO14443-B tags. If you roll your own payment terminals you have more choices.

Is a double-tap unavoidable?

No, it is an implementation detail of this technology. You don't need to double-tap if you use contactless credit cards for example.

\$\endgroup\$

Not the answer you're looking for? Browse other questions tagged or ask your own question.