Global Patent Index - EP 0242901 A1

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

EP 0242901 A1 19871028 (EN)

Application

EP 87200534 A 19870324

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

G08B 13/24; G08B 29/00

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)

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