ISO/IEC 14443 Type B

ISO/IEC 14443 Type B is one of two internationally recognized protocols for contactless smart cards and RFID devices operating at 13.56 MHz. Developed and maintained by the International Organization for Standardization and the International Electrotechnical Commission, this standard defines how proximity cards communicate with readers at distances typically ranging from a few centimeters up to 10 centimeters. Unlike its sibling Type A, Type B uses a different modulation scheme and initialization process, though both operate in the same high-frequency band and share similar physical characteristics. At the physical layer, ISO 14443 Type B employs NRZ encoding with 10 percent amplitude shift keying modulation for reader-to-card communication. The card responds back to the reader using load modulation with BPSK subcarrier at 847 kHz. This asymmetric communication approach allows passive cards to harvest energy from the electromagnetic field generated by the reader while simultaneously transmitting data back. The standard specifies data rates of 106 kbit/s, 212 kbit/s, 424 kbit/s, and 848 kbit/s, giving designers flexibility to balance speed against reliability based on their application requirements. The anticollision mechanism in Type B differs significantly from Type A. Type B uses a probabilistic slot-based approach where each card responds in a randomly selected time slot during the reader's polling sequence. The reader sends an REQB or WUPB command, and cards respond with their unique identifiers in designated time slots. If collisions occur, the reader adjusts its polling parameters to isolate individual cards. This method proves particularly effective in environments with moderate card populations, though Type A's deterministic binary tree anticollision can be more efficient in heavily populated fields. Typical applications for ISO 14443 Type B include government identification documents, electronic passports, and access control systems. China's second-generation national ID card is perhaps the most prominent deployment, representing hundreds of millions of cards in circulation. Financial payment cards in some regions also implement Type B, though Type A has gained more traction in contactless payment systems globally. The standard's robust error detection and correction capabilities make it suitable for secure transactions where data integrity is paramount.