| 摘要 |
<p>A system for recognizing the presence of a second portable data carrier by a first portable data carrier, wherein the data carriers have respectively a contactless interface with an antenna and an electronic circuit for storing and/or processing data. An RFID reading device supplies the data carriers with energy and for the respective communication of the data carriers with the reading device. In the first and the second data carrier there is respectively provided a further communication device, via which an additional, direct communication channel, independent of the field of the reading device, is made available between the first and the second data carrier, to thereby check the immediate presence of the second data carrier in the field of the reading device by the first data carrier.</p> |
