发明名称 |
Variable frequency RF electronic surveillance system |
摘要 |
An electronic article surveillance system is disclosed, having a transmitter means for producing in an interrogation zone sequences containing a plurality of discrete different radio frequencies thereby causing a circuit present within the zone to resonate at its resonant frequency in response to energy absorbed at at least three different frequencies. A receiver means is provided to cause an alarm in the event of detection of three such resonances over two successive sequences.
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申请公布号 |
US4609911(A) |
申请公布日期 |
1986.09.02 |
申请号 |
US19850756703 |
申请日期 |
1985.07.19 |
申请人 |
MINNESOTA MINING AND MANUFACTURING COMPANY |
发明人 |
NOURSE, GARY E.;DOWDLE, DEAN M. |
分类号 |
G08B13/24;(IPC1-7):G08B13/24 |
主分类号 |
G08B13/24 |
代理机构 |
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代理人 |
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主权项 |
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地址 |
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