EP 0242901 A1 19871028 - An electromagnetic detection system with improved false-alarm suppression.
Title (en)
An electromagnetic detection system with improved false-alarm suppression.
Title (de)
Elektromagnetische Detektionsanlage mit Falschalarmunterdrückung.
Title (fr)
Système de détection électromagnétique avec suppression de fausses alarmes.
Publication
Application
Priority
NL 8600738 A 19860324
Abstract (en)
An electromagnetic detection system which, in operation, by means of at least one transmission aerial coil, generates a sweeping frequency interrogation field in a detection zone, which field can be disturbed by the presence in said zone of a responder equipped with a tuned circuit, there being provided detection means for detecting such disturbance and activating an alarm device, and wherein said detection means comprise a channel (33-35) for processing signals (R, S) in a frequency band corresponding to the frequency band of a signal (R) caused by a responder, and that a blanking circuit (12) is connected to said channel for detecting the occurrence in said channel (33-35) of signals exceeding a pre-determined threshold value (D) and, after detecting a first signal exceeding said threshold value, in response to one or more further signals exceeding said predetermined threshold value, producing a blanking signal (Pb) for a pre-determined time interval to prevent activation of said alarm device (43).
IPC 1-7
IPC 8 full level
G08B 13/24 (2006.01); G08B 29/18 (2006.01)
CPC (source: EP)
G08B 13/2414 (2013.01); G08B 29/24 (2013.01)
Citation (search report)
- [AD] EP 0100128 A1 19840208 - NEDAP NV [NL]
- [AD] US 3868669 A 19750225 - MINASY ARTHUR J
- [A] FR 2384306 A1 19781013 - LICHTBLAU GEORGE [US]
- [A] WO 8301331 A1 19830414 - I D ENGINEERING INC [US]
- [A] US 3110007 A 19631105 - FRIELINGHAUS KLAUS H
Designated contracting state (EPC)
BE DE FR GB NL
DOCDB simple family (publication)
EP 0242901 A1 19871028; EP 0242901 B1 19901212; DE 3766644 D1 19910124; NL 8600738 A 19871016
DOCDB simple family (application)
EP 87200534 A 19870324; DE 3766644 T 19870324; NL 8600738 A 19860324