ISO 15693

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ISO 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 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

[edit] 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.

[edit] Communication to the reader

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

[edit] Amplitude Shift Keying

Amplitude Shift Keying 100% modulation index on a 423.75 kHz Subcarrier The data rate can be:

Low 6.62 kbit/s ( fc/2048)

High 26.48 kbit/s ( fc/512)

A logic 0 starts with 8 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.

[edit] 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:

Low 6.67 kbit/s ( fc/2032)

High 26.69 kbit/s ( fc/508)

A logic 0 starts with 8 pulses of 423.75 kHz followed by 9 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.

[edit] External links

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