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Shop or store security system - uses two magnetic fields applied to security zone to detect passage of magnetic element on goods and sound alarm
Shop or store security system - uses two magnetic fields applied to security zone to detect passage of magnetic element on goods and sound alarm
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机译:商店或商店的安全系统-使用两个施加到安全区域的磁场来检测商品上磁性元素的通过并发出声音警报
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摘要
The method is designed in particular for the delection of goods (3) stolen from counters in a store. The method uses two alternating magnetic fields which are used to sweep the surveillance zone (2). These fields act on marking elements (4) attached to the stolen goods which produce and radiate at least a frequency different to that of the alternating field frequencies. In order to counteract mutual influence and to suppress formation of harmonic frequencies or modulation attributable to simple coupling, the supply to the magnetic field generators is effected by an applied current. Whilst because of the non linearity of the marking element, an harmonic signal is produced which represents at least twice or a multiple of the base or excitation frequency.
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