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Pub. No.:    WO/1979/000844    International Application No.:    PCT/SE1979/000068
Publication Date: 01.11.1979 International Filing Date: 28.03.1979
G08B 26/00 (2006.01), G08B 29/08 (2006.01)
Priority Data:
7803437 28.03.1978 SE
Abstract: front page image
(EN)In a security system, for status reporting from detectors (D1, D2, D3) set up in a protected local (P) to a monitoring centre (C), and monitoring the operational condition of communication lines (3) which are arranged to connect the detectors to the monitoring centre, an interrogation signal (F) is produced and transmitted from an interrogation unit (1) in the monitoring centre to an answering unit (2) connected to the interrogation unit and located in the detector. The answering unit replies by producing and sending back to the interration unit an answering signal (Sf) which is dependent on he interrogation signal. When alarm/sabotage status is indicated by the detector, the answering unit recognises this and sends an alarm/sabotage signal (sa/Ss) to the interrogation unit which is different from the answering signal (Sf) depending on the interrogation signal. In order to prevent or make unauthorised manipulation of the security system with a view to misleading the monitoring centre (C) extremely difficult, and to obtain a functionally-reliable arrangement in which both monitoring of the communication lines (3) and status reporting from the detectors (D1, D2, D3) is effected simultaneously with the aid of the same functional units by integrated communication, the interrogation signal (F) transmitted by the interrogation unit (1) is arranged to be transmitted continuously and also to be information-bearing with a stochastically varying content. The answering unit (2) is arranged to endow the answering signal with an information content which, in addition to the instantaneous information content of the interrogation signal, also depends on the actual status (a, s) of the detector, and to send back the answering signal continuously.
(FR)Dans un systeme de securite, des detecteurs (D1, D2, D3) montes dans un local protege (P) informent un centre de surveillance (C) sur l"etat des lieux, controlent l"etat de fonctionnement des lignes de communication (3) qui etablissent la connexion entre les detecteurs et le centre de surveillance, et une unite d"interrogation (1) placee dans le centre de surveillance produit et transmet un signal d"interrogation (F) a une unite de reponse (2) connectee a l"unite d"interrogation et situee dans le detecteur. L"unite de reponse repond en produisant et en renvoyant a l"unite d"interrogation un signal de reponse (Sf) qui depend du signal d"interrogation. Lorsqu"un etat alarme/sabotage est indique par le detecteur, l"unite de reponse le reconnait et envoie un signal alarme/sabotage (sa/Ss) a l"unite d"interrogation, different du signal de reponse (Sf) dependant du signal d"interrogation. De maniere a empecher ou a rendre extremement difficile une manipulation non autorisee du systeme de securite ayant pour objet de tromper le centre de surveillance, et de maniere a obtenir un dispositif d"un fonctionnement sur dans lequel le controle des lignes de communication (3) et l"information sur l"etat des lieux provenant des detecteur (D1, D2, D3) s"effectuent simultanement au moyen des memes unites fonctionnelles par communication integree, le signal d"interrogation (F) transmis par l"unite d"interrogation (1) est transmis de maniere continue et avec variation stochastique de l"information contenue. L"unite de reponse (2) est concue pour doter le signal de reponse d"un contenu d"informations qui, en plus de l"information instantanee du signal d"interrogation, depend aussi de l"etat actuel (a, s) du detecteur, et pour renvoyer le signal de reponse de maniere continue.
Designated States:
Publication Language: English (EN)
Filing Language: English (EN)