| Iso 15693 |
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| #15693 | |
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ISO 15693 is an ISO standard for " Vicinity Card s", i.e. cards which can be read from a greater distance as compared to Proximity Card s. 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). 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 kilo Bits Per Second The Least-significant Bit s 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: 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: # an unmodulated time of 56,64 µs (768/ fc), # 24 pulses of 423,75 kHz # a logic 1 and the end of a frame is: # a logic 0 # 24 pulses of 423,75 kHz # 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: 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: # 27 pulses of 484,28 kHz # 24 pulses of 423,75 kHz # a logic 1 and the end of a frame is: # a logic 0 # 24 pulses of 423,75 kHz # 27 pulses of 484,28 kHz The data is sent using a Manchester Code . |
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