| 摘要 |
The device uses thin card transponder circuits attached to items to be monitored. These circuits comprise a unit for transmitting and receiving information and includes an aerial and a microprocessor. Transmission is via. an omni-directional aerial which may be wire, micro-strip or helicoidal. The electronic system for surveillance comprises a central unit and at least one transponder. The central unit comprises a device for transmitting and receiving information and includes at least one aerial, and a microprocessor. Transmission is via an omni-directional aerial which may be wire, micro-strip or helicoidal of a size appropriate to the wavelength transmitted. The transponders also comprise aerials, and are formed within integrated circuits formed in cards of thickness between 0,1 and 5 mm. Transponder cards may be attached to objects of value, or indeed children to be watched, so that movement outside a defined area causes an alarm signal.
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