发明名称 |
VARIABLE FREQUENCY RF ELECTRONIC SURVEILLANCE SYSTEM |
摘要 |
<p>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.</p> |
申请公布号 |
CA1219932(A) |
申请公布日期 |
1987.03.31 |
申请号 |
CA19840458083 |
申请日期 |
1984.07.04 |
申请人 |
MINNESOTA MINING AND MANUFACTURING COMPANY |
发明人 |
NOURSE, GARY E.;DOWDLE, DEAN M. |
分类号 |
H04B17/00;G08B13/24;G08B15/00;G08B21/00;G08B21/24;H04B1/18;(IPC1-7):G01N27/72 |
主分类号 |
H04B17/00 |
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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