ISO/IEC 15693, is anISO/IEC standard forvicinity cards, i.e. cards which can be read from a greater distance as compared withproximity cards. Such cards can normally be read out by a reader without being powered themselves, as the reader will supply the necessary power to the card over the air (wireless).
ISO/IEC 15693 systems operate at the 13.56 MHzfrequency, and offer maximum read distance of 1–1.5 meters. As the vicinity cards have to operate at a greater distance, the necessarymagnetic field is less (0.15 to 5 A/m) than that for a proximity card (1.5 to 7.5 A/m). ISO/IEC 15693 is called contactless long-range standard with a lower RF speed compared to some other RFID standard such asISO/IEC 14443.
2 bits are coded as the position of a 9.44 μs pause in a 75.52 μs symbol time, giving a bit rate of 26.48kilobits per second. Theleast-significant bits are sent first.
1 out of 256 pulse-position modulation
8 bits are coded as the position of a 9.44 μs pause in a 4.833 ms symbol time, giving a bit rate of 1.65 kbit/s.
A logic 0 starts with eight pulses of 423.75 kHz followed by an unmodulated time of 18.88 μs (256/ fc); a logic 1 is the other way round. Thedata frame delimiters are code violations, a start of frame is:
Frequency-shift keying by switching between a 423.75 kHz sub carrier (operating frequency divided by 32) and a 484.25 kHz sub carrier (operating frequency divided by 28). The data rate can be:
Low 6.67 kbit/s (fc/2032)
High 26.69 kbit/s (fc/508)
A logic 0 starts with eight pulses of 423.75 kHz followed by nine pulses of 484.28 kHz; a logic 1 is the other way round. Thedata frame delimiters are code violations, a start of frame is:
μController:Texas Instruments offers a small μController entirely powered by the ISO/IEC 15693 reading field and capable of reading a simple temperature sensor, wirelessly providing the value of that to the reader.
