Dienstag, 8 März 2011
Depending on the standard use, these cards are either proximity cards (according to ISO 14443) or vicinity cards (according to ISO 15693). Both standards use the so popular RFID Technology, so I’ll talk about that first. RFID standard for Radio Frequency Identification. The technology bases in the inductive coupling of two coils/antennas. Depending on the antennas and the power used to generate the electro mangentic field, distances starting from some centimeters up to several meters can be briged by using RFID Technology. There are several different frequencies used in the RFID Industry, popular ones are: 125 kHz, 13,56 Mhz (used by ISO14443, ISO15693, ISO18092) or 900 Mhz. In an RFID System there is usually an active reader, that generates the electro mangentic field and a passive transponder (tag, smartcard) that is powered by this field (and thus needs no battery). After the passive part is powered, the communication is established and both parties can exchange data. The active part (reader) emitting the field is also called initiator where as the passive one (waiting for the initiator) is called target. So far for the electro magenetic stuff (from a very basic, theoretical side) and back to the smartcards.
As already mentioned both proximity and vinicity card use 13,56 Mhz and therefore are compatible on the very low (physical) layer of communcation. ISO 15693 actually is not considered by the NFC Forum – the standardization body for NFC – thus, I will not give further details on this standard. During the standardization of ISO 14443 the two major players (Infineon, Philips; now NXP) could not agree on a modulation schema, thus there are two different one: ISO 14443-A (Philips, now NXP & Co.) and ISO 14443-B (Infineon & Co. ). There are several popular products using ISO 14443, like the RFID Passport. One of the most widely used RFID Card is Mifare. Mifare is not compliant to ISO 14443 on all levels (only 1 – 3) as it implements a proprietary cipher. Several public transport Systems, like London (Oyster) or Hongkong (Octopus) use Mifare. The cipher actually was broken in 2008. In Japan Sony has introduced its one contactless Smartcard: Felcia; there it is used for Payment & Public Transport (Suica). Felcia is neither ISO14443-A nor –B. NFC Devices in the further should be able to overcome all this different smartcard standards and should be able to talk to any of these contactless smartcards or reader.
- NFC Phones
- NFC Stickers