GB1295189A - - Google Patents

Info

Publication number
GB1295189A
GB1295189A GB1295189DA GB1295189A GB 1295189 A GB1295189 A GB 1295189A GB 1295189D A GB1295189D A GB 1295189DA GB 1295189 A GB1295189 A GB 1295189A
Authority
GB
United Kingdom
Prior art keywords
signal
units
alarm
unit
comparator
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed filed Critical
Publication of GB1295189A publication Critical patent/GB1295189A/en
Expired legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G08—SIGNALLING
    • G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
    • G08B25/00—Alarm systems in which the location of the alarm condition is signalled to a central station, e.g. fire or police telegraphic systems
    • G08B25/01—Alarm systems in which the location of the alarm condition is signalled to a central station, e.g. fire or police telegraphic systems characterised by the transmission medium
    • G08B25/04—Alarm systems in which the location of the alarm condition is signalled to a central station, e.g. fire or police telegraphic systems characterised by the transmission medium using a single signalling line, e.g. in a closed loop
    • G08B25/045—Alarm systems in which the location of the alarm condition is signalled to a central station, e.g. fire or police telegraphic systems characterised by the transmission medium using a single signalling line, e.g. in a closed loop with sensing devices and central station in a closed loop, e.g. McCullough loop
    • G—PHYSICS
    • G08—SIGNALLING
    • G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
    • G08B29/00—Checking or monitoring of signalling or alarm systems; Prevention or correction of operating errors, e.g. preventing unauthorised operation
    • G08B29/02—Monitoring continuously signalling or alarm systems
    • G08B29/06—Monitoring of the line circuits, e.g. signalling of line faults
    • G08B29/08—Signalling of tampering with the line circuit

Abstract

1295189 Alarm systems TELEFONAKTIEBOLAGET L M ERICSSON 30 Dec 1970 [8 Jan 1970] 61894/70 Heading G4H A control signal G, e.g. a random pulse sequence is transmitted through successive protected units B1-Bn connected in a loop a with the control station C, each unit B modifies the signal supplied to it over loop a, e.g. by an exclusive OR gate E11-E1n and a characteristic pulse sequence generator G11-G1n, and the control station compares the returned signal with the original control signal. A modifying unit SK may effect the same signal changes as those normally effected by units B so that a comparator K signals an alarm if inequality is detected, while comparators K1-Kn which receive the return signal additionally modified by a respective generator G31-G3n and gate E31-E3n corresponding to G11-G1n and E11-E1n identify the alarm-signalling unit B if equality is detected. In an alternative arrangement, modifier SK is placed between the return line and comparator K and effects the opposite modifications to those normally effected in units B.
GB1295189D 1970-01-08 1970-12-30 Expired GB1295189A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
SE00162/70A SE329358B (en) 1970-01-08 1970-01-08

Publications (1)

Publication Number Publication Date
GB1295189A true GB1295189A (en) 1972-11-01

Family

ID=20256131

Family Applications (1)

Application Number Title Priority Date Filing Date
GB1295189D Expired GB1295189A (en) 1970-01-08 1970-12-30

Country Status (6)

Country Link
US (1) US3710372A (en)
DE (1) DE2064858C3 (en)
DK (1) DK124153B (en)
GB (1) GB1295189A (en)
NO (1) NO124613B (en)
SE (1) SE329358B (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2170631A (en) * 1985-02-04 1986-08-06 Mitsubishi Electric Corp A serial transmission apparatus

Families Citing this family (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3792469A (en) * 1972-07-17 1974-02-12 Johnson Service Co Multiplexed alarm transmission system having alarm storage circuits
FR2324172A1 (en) * 1975-09-15 1977-04-08 Gautier Gerard ANTI-FRAUDULENT PROTECTION DEVICE FOR TELEPHONE LINE OPERATED IN ALARM TRANSMISSION
SE7803437L (en) * 1978-03-28 1979-09-29 Saab Scania Ab PROCEDURE THAT IN THE INSTALLATION OF A UNIT'S UNITS ARE CONNECTED BY MEANS OF A COMMUNICATION LINE FOR INFORMATION SIGNALS, CONTINUOUSLY MONITOR THE CONDITION OF THOSE CONNECTED TO THE COMMUNICATION LINE ...
US4240078A (en) * 1978-06-07 1980-12-16 Minnesota Mining And Manufacturing Company Frequency selective annunciator system
US4262284A (en) * 1978-06-26 1981-04-14 Stieff Lorin R Self-monitoring seal
US4229734A (en) * 1978-10-26 1980-10-21 Honeywell Inc. Line supervision
US4268823A (en) * 1979-11-02 1981-05-19 Ici Americas Inc. Protective electrical system for providing indications of removal of objects from plural monitored locations by use of parallel-connected object-sensors
US4577184A (en) * 1983-05-23 1986-03-18 Tetra-Tech, Inc. Security system with randomly modulated probe signal
US4555930A (en) * 1984-02-14 1985-12-03 Control Instruments Corp. Digital gas sensing system
US4716401A (en) * 1985-09-19 1987-12-29 Deere & Company Tamper-resistant supervisory system
DE3878348D1 (en) * 1987-08-14 1993-03-25 Siemens Ag DATA TRANSFER PROCEDURE.

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2423649A (en) * 1944-12-08 1947-07-08 Horvitch Gerard Michael Electric burglar alarm
US3253270A (en) * 1963-08-02 1966-05-24 Downer Frank Theft alarm for shoplift prevention

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2170631A (en) * 1985-02-04 1986-08-06 Mitsubishi Electric Corp A serial transmission apparatus

Also Published As

Publication number Publication date
NO124613B (en) 1972-05-08
DE2064858A1 (en) 1971-07-15
SE329358B (en) 1970-10-05
DE2064858C3 (en) 1974-05-30
DE2064858B2 (en) 1973-10-31
US3710372A (en) 1973-01-09
DK124153B (en) 1972-09-18

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Legal Events

Date Code Title Description
PS Patent sealed [section 19, patents act 1949]
PCNP Patent ceased through non-payment of renewal fee