EP 0289641 B1 19920226 - SECURITY FENEE WITH SECURITY WIRES ATTACHED TO POSTS VIA DETECTORS
Title (en)
SECURITY FENEE WITH SECURITY WIRES ATTACHED TO POSTS VIA DETECTORS
Publication
Application
Priority
EP 87106681 A 19870508
Abstract (en)
[origin: US4803468A] A security fence, in which contact sensors produce corresponding signals when the security wires are touched. Each sensor is attached to two low-pass filters, the cutoff frequency of one filter being above, and below the cutoff frequency of the other filter being below the frequency spectrum of a sensor signal which occurs when the wire is deflected by a person. The output signals of the low-pass filters are subtracted in a subtraction circuit. If the subtracted output signal of the subtraction circuit exceeds a predetermined threshold, an alarm signal is released. Deflections of the wire due to other circumstances and, therefore being in another frequency spectrum do not result in the alarm being released.
IPC 1-7
IPC 8 full level
G08B 13/12 (2006.01)
CPC (source: EP US)
G08B 13/122 (2013.01 - EP US)
Designated contracting state (EPC)
AT BE CH DE ES FR GB GR IT LI NL SE
DOCDB simple family (publication)
US 4803468 A 19890207; AT E72906 T1 19920315; CA 1276256 C 19901113; DE 3776899 D1 19920402; EP 0289641 A1 19881109; EP 0289641 B1 19920226
DOCDB simple family (application)
US 7180887 A 19870710; AT 87106681 T 19870508; CA 542193 A 19870715; DE 3776899 T 19870508; EP 87106681 A 19870508