| 摘要 |
A system and a method are described for detection of individuals ( 8 ) or objects in a plurality of delimited spaces ( 10 ), each having at least one entrance ( 6 ). The detection system comprises LF transmission means ( 4, 4*, 5, 5 *) located at the entrance, for transmitting a LF electromagnetic signal, HF transmission-reception means ( 12, 13 ) for transmitting-receiving a HF electromagnetic signal (C, ACK), cards or portable electronic units ( 36 ) equipping each individual or object, for receiving the LF signal and for transmitting and receiving the HF signal, and a central processing unit ( 20 ) for recording data relating to the entry and exit of the portable electronic units. The system can operate according to at least two distinct modes of operation and the LF signal comprises selection information (SELECT) indicating which of the two modes of operation should be used by the electronic units during their passage through the entrance. The system is preferably configured to pass, at least temporarily, in one of the said delimited spaces, from one mode of operation to the other. |
