ISO/IEC 15693

ISO/IEC 15693 is an ISO standard for vicinity cards, i.e. cards which can be read from a greater distance as compared to proximity cards.

ISO/IEC 15693 systems operate at the 13.56 MHz frequency, and offer maximum read distance of 1-1.5 metres. As the vicinity cards have to operate at a greater distance, the necessary magnetic field is less (0.15 to 5 A/m) than that for a proximity card (1.5 to 7.5 A/m).

Contents

Communication to the card

Communication from the reader to the card uses an amplitude-shift keying with 10% or 100% modulation index.

The data coding is:

1 out of 4 pulse position modulation 
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 26.48 kilobits per second The least-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.

Communication to the reader

The card has two ways to send its data back to the reader:

Amplitude shift keying

Amplitude-shift keying 100% modulation index on a 423.75 kHz subcarrier. The data rate can be:

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. The data frame delimitors are code violations, a start of frame is:

  1. an unmodulated time of 56.64 µs (768/ fc),
  2. 24 pulses of 423.75 kHz
  3. a logic 1

and the end of a frame is:

  1. a logic 0
  2. 24 pulses of 423.75 kHz
  3. an unmodulated time of 56.64 µs

The data is sent using a Manchester code.

Frequency shift keying

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:

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. The data frame delimitors are code violations, a start of frame is:

  1. 27 pulses of 484.28 kHz
  2. 24 pulses of 423.75 kHz
  3. a logic 1

and the end of a frame is:

  1. a logic 0
  2. 24 pulses of 423.75 kHz
  3. 27 pulses of 484.28 kHz

The data is sent using a Manchester code.

Implementations

iCLASS family of cards and tags by HID Global, with a maximum read range 45 centimetres (18 in).

External links