EP 0565481 B1 19970611 - Label detection apparatus
Title (en)
Label detection apparatus
Title (de)
Vorrichtung zur Detektion von Etiketten
Title (fr)
Dispositif de détection d'étiquettes
Publication
Application
Priority
CH 113292 A 19920407
Abstract (en)
[origin: US5349339A] An apparatus for the detection of labels used for preventing theft of goods and provided with an electric resonant circuit [(21) and] having a resonant frequency [(fr)] in the MHz range [comprises] has a transmitter [(1)] and a receiver [(2)]. The transmitter [(1)] generates a transmitting signal sequence, whose frequency is wobbled in wobble cycles over and beyond the given resonant frequency of the labels and [radiates] which is radiated by means of a transmitting antenna [(11)]. Signal generation in the transmitter [(1)] takes place digitally and with coinciding phase position with respect to each wobble cycle. In the receiver [(2)] the signals received by means of a receiving antenna [(12)] are scanned and digitized synchronously with signal generation in the transmitter [(1)]. From the digitized signal values of n wobble cycles a background is formed and subtracted from the digitized signal values of the in each case last wobble cycle. A long-term and a short-term background can be formed and the latter is subtracted from the former. By background subtraction it is in particular possible to [discriminate time] eliminate relatively [stationary] time stationary interference, such as is particularly caused by transmitting signal diffractions and reflections on objects present in the vicinity of the transmitting and/or receiving antenna.
IPC 1-7
IPC 8 full level
G08B 13/24 (2006.01)
CPC (source: EP US)
G08B 13/2414 (2013.01 - EP US); G08B 13/2471 (2013.01 - EP US); G08B 13/2488 (2013.01 - EP US)
Designated contracting state (EPC)
AT BE CH DE DK ES FR GB GR IE IT LI LU MC NL PT SE
DOCDB simple family (publication)
US 5349339 A 19940920; AT E154459 T1 19970615; DE 59306713 D1 19970717; EP 0565481 A1 19931013; EP 0565481 B1 19970611; JP H06103472 A 19940415
DOCDB simple family (application)
US 1382593 A 19930203; AT 93810137 T 19930225; DE 59306713 T 19930225; EP 93810137 A 19930225; JP 4937693 A 19930310