Patent ID: 7325723
Filing Date: 2008-02-05
Classification: G06K,G07C

Abstract:
1. A system for detecting individuals or objects in a plurality of delimited spaces each having at least one entrance, the detection system comprising, for each of said delimited spaces: low frequency transmission means associated with said each delimited space and located at said at least one entrance to transmit at least one low frequency electromagnetic signal in a communication region substantially covering said entrance; and high frequency transmission-reception means associated with the delimited space for receiving and transmitting at least one higher frequency electromagnetic signal; the detection system further comprising: cards or portable electronic units, each equipping an individual or object, each electronic unit comprising a low frequency reception module for receiving said at least one low frequency electromagnetic signal and a high frequency transmission-reception module for transmitting and receiving said at least one higher frequency electromagnetic signal; and at least one central processing unit associated with the said delimited spaces and connected to the said low frequency transmission means as well as to the said high frequency transmission-reception means for recording data relative to said at least one entrance and exit of the said portable electronic units, wherein the system is configured to operate according to at least two distinct modes of operation in which said electronic units communicate with said high-frequency transmission-reception means, and wherein said low frequency electromagnetic signal comprises selection information indicating to said electronic units, during their passage through an entrance of any one of said plurality of delimited spaces, which of the said at least two modes of operation should be utilised by said electronic units.