Intrusion detection system and signal processing circuitry therefor

(19)

(11)

EP 0 448 290 A3

(12)	EUROPEAN PATENT APPLICATION

(88)	Date of publication A3:
	30.09.1992 Bulletin 1992/40

(43)	Date of publication A2:
	25.09.1991 Bulletin 1991/39

(21)	Application number: 91302176.2

(22)	Date of filing: 14.03.1991

(51)	International Patent Classification (IPC)⁵: G08B 13/16

(84)	Designated Contracting States:
	AT BE CH DE DK ES FR GR IT LI LU NL SE

(30)

Priority:

14.03.1990 GB 9005751

(71)	Applicant: GEOQUIP LIMITED
	Melbourne, Derbyshire (GB)

(72)	Inventor:
	Macalindin, Ian, c/o Geoquip Limited Melbourne, Derbyshire (GB)

(74)	Representative: Ayers, Martyn Lewis Stanley et al
	J.A. KEMP & CO. 14 South Square Gray's Inn London WC1R 5LX London WC1R 5LX (GB)

(56)

References cited: :

(54)	Intrusion detection system and signal processing circuitry therefor

(57) An intrusion sensor apparatus comprises a microphonic cable and signal processing circuitry for monitoring the output of the cable to signal an attempted intrusion. The signal processing circuit comprises a number of parallel signal processing channels each adapted to respond to characteristics of the output of the cable indicative of the type of mechanical stimulation of the cable which correlates with the type of intrusion. The characteristics to which the channels respond are the time dependent behaviour of parts of the frequency spectrum of the cable output.

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