ISO/IEC 15693 systems operate at the 13.56 MHz frequency, and offer maximum read distance of 1–1.5 meters.
Communication from the reader to the card uses an amplitude-shift keying with 10% or 100% modulation index.
Both use a subcarrier transmitted back to the reader using load modulation.
Amplitude-shift keying 100% modulation index on a 423.75 kHz subcarrier.
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).