Communications: electrical – Condition responsive indicating system – Specific condition
Patent
1988-09-16
1989-12-19
Eisenzopf, Reinhard J.
Communications: electrical
Condition responsive indicating system
Specific condition
324239, 340551, G08B 1324
Patent
active
048885797
ABSTRACT:
Markers in different portions of the interrogation zone of an electromagnetic article surveillance system produce signals with waveforms of different character. In one embodiment, a false alarm minimization method determines the character of the waveform of the signal induced in the detection antenna. A requirement that signals with waveforms of different character be sensed provides greater confidence that the marker is passing through, as opposed to being near one portion of, the interrogation zone. Also, false alarms produced by stationary objects such as metallic door and window frames are eliminated. In another embodiment, the direction in which the marker passes through the interrogation zone is determined.
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Belka Anthony M.
ReMine Walter J.
Eisenzopf Reinhard J.
Forrest Peter
Kirn Walter N.
Minnesota Mining and Manufacturing Company
Mueller Robert W.
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