| 摘要 |
<p>The invention refers to a system for admission control at passage and for locating of persons or objects within an area covered by radio communication from stationary and/or mobile devices (7, 12, 15, and 16). Persons, or objects, are thereby equipped with means, preferably in the form of smart cards (1), comprising aerial (5), memory (6), passive (8) and active (9) receivers, active transmitter (10), battery (11), which may have a battery charge indicator, a sound emitting device (13) and a watch/timer (14). For users of the system a procedure has been invented where from a computer (3) by the devices (7, 12, 15, 16) emanate radio signals to one or more cards (1), which transmits answer signals to the devices. The devices can transmit signals on more than one frequency and receive two or more answer signals on fundamental, harmonic and/or interference frequencies.</p> |
