Communication, Tag to Reader

This page describes how tags (VICCs) use the 13.56 MHz radio frequency operating field to send information to the tag reader (VCD). The ISO/IEC standard refers to this as the Communications Signal Interface VICC to VCD. As for the reader to tag direction, by "information" we mean a binary data packet and the packet contents will be dealt with elsewhere. Again, we will be concerned with the representation of binary digits (zeros and ones) and how the beginning and the end of a packet are established.