EP0094279A1 - Verfahren zum Schutz eines Fernüberwachungssystemes gegen Sabotage und System zur Ausführung dieses Verfahrens - Google Patents

Verfahren zum Schutz eines Fernüberwachungssystemes gegen Sabotage und System zur Ausführung dieses Verfahrens Download PDF

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Publication number
EP0094279A1
EP0094279A1 EP83400810A EP83400810A EP0094279A1 EP 0094279 A1 EP0094279 A1 EP 0094279A1 EP 83400810 A EP83400810 A EP 83400810A EP 83400810 A EP83400810 A EP 83400810A EP 0094279 A1 EP0094279 A1 EP 0094279A1
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EP
European Patent Office
Prior art keywords
sensor
sensors
signal
central station
outputs
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Application number
EP83400810A
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English (en)
French (fr)
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EP0094279B1 (de
Inventor
Marc Tonello
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EUROPEENNE DE TELETRANSMISSION C E T T Cie
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EUROPEENNE DE TELETRANSMISSION C E T T Cie
EUROPEENE DE TELETRANSMISSION C E T T Cie
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    • 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
    • G—PHYSICS
    • G08—SIGNALLING
    • G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
    • G08B26/00—Alarm systems in which substations are interrogated in succession by a central station
    • G08B26/001—Alarm systems in which substations are interrogated in succession by a central station with individual interrogation of substations connected in parallel
    • G08B26/002—Alarm systems in which substations are interrogated in succession by a central station with individual interrogation of substations connected in parallel only replying the state of the sensor

Definitions

  • the invention relates to the protection of a telesurveillance system against sabotage intended to neutralize it, that is to say to render it inoperative while keeping it apparently functioning normally.
  • a remote monitoring system intended to detect an intrusion into a room is deactivated if someone modifies the system in such a way that the sensors give a normal response when in fact they should report an intrusion.
  • each sensor of a conventional telemonitoring system is connected to the central station of the system by a line comprising four conductors: two constituting a protection loop to detect sabotage of the line, and two constituting a loaded detection loop to convey alarm information.
  • This line may be supplemented by other conductors to carry out a remote test of the sensors. It is known to detect sabotage of such a line by detecting a variation in current, voltage, or impedance. These processes are simple and easily neutralizable for those who have a little time and a minimum of technical knowledge. On the other hand, several sensors are generally connected on the same line and it is not possible to distinguish which sensor transmits alarm information.
  • German patent D 1 259 230 describes a remote monitoring device, consisting of a central station and a plurality of satellite stations to which sensors are connected, and where each satellite station is interrogated by sending on a first line negative pulses whose number designates a satellite station and positive pulses whose number designates one of the sensors of this satellite station, and where the interrogated satellite station responds by sending on a second line a pulses, of fixed amplitude, for each sensor detecting an anomaly.
  • This device makes it possible to individually locate each sensor detecting an anomaly, while requiring only two transmission lines, and makes it possible to detect a fault affecting these two lines.
  • it is quite vulnerable to sabotage because it is relatively easy to observe and then simulate the signals traveling on the second line; these signals being simple, in particular because they are pulses whose amplitude, frequency and duration are constant.
  • the object of the method according to the invention is to remedy these drawbacks by simple means.
  • the remote monitoring system represented in FIG. 1 consists of a central station 6 and sensors n ° 1, n ° 2, n ° 3, ... each having an input terminal 2 connected to a bus line 4 and an output terminal 3 connected to a bus line 5, the bus lines 4 and 5 being connected to the central station 6.
  • each sensor is connected to a switch 1 for which it is responsible for transmitting the state when the central station 6 interrogates the sensors.
  • This switch 1 makes it possible to detect, for example, the opening of a door.
  • the system can include up to 16 sensors. To detect the change of state of a switch l, or an abnormal functioning of a sensor, each sensor is tested cyclically by interrogating it periodically from the central station 6.
  • the central station 6 comprises a signal generator 8, a separator 7 of synchronization signals and clock signals, a binary counter 9, a read only memory 10, a digital-analog converter 11, and an analog comparator 12.
  • the generator signal 8 provides a periodic binary signal V I which is shown in Figure 2a.
  • the signal generator 8 supplies a synchronization pulse 22 between instants t. and t, then 256 periodic pulses, of period much less than the duration t i -t o .
  • the output of the signal generator 8 is connected to the bus line 4 and therefore supplies this signal to the input terminal 2 of each sensor.
  • FIG. 2b represents the signal V2 supplied on the bus line 5 by all of the outputs of the sensors of the system.
  • the sensor n ° 1 supplies a variable voltage 19 made up of a succession of constant levels. During this time, the output of the other sensors does not provide voltage and has a high impedance.
  • the output of the sensor n ° 2 provides on the bus line 5 another signal 20 whose voltage is variable, while the outputs of all the other sensors have a high impedance.
  • the output of sensor no During the time interval (t 2 , t 3 ) the output of sensor no.
  • each sensor provides a variable voltage 21, having a shape different from the previous two, while the outputs of the other sensors have a high impedance.
  • Each sensor in turn provides a signal on the bus line 5 during a time interval corresponding to 16 periodic pulses from the signal generator 8.
  • the signal transmitted by each sensor has a complex shape, different for each of the sensors. If the switch 1 connected to a sensor changes state, the shape of the signal transmitted by this sensor is modified to transmit this information. For example, the response signal V 2 can be replaced by a signal of zero value.
  • FIG. 3 represents the block diagram of an exemplary embodiment of a sensor, such as sensor n ° 1.
  • the sensor comprises a separator 13 of synchronization signals and clock signals, a binary counter 14, a read only memory 15, a digital-analog converter 16 and an analog gate 17.
  • the input terminal 2 is connected to an input of the separator 13 which provides a logic signal on a first output when the central station sends an input terminal 2 synchronization signal characterized by its duration t.-t, and which provides on a second output a clock signal constituted by the periodic pulses which follow the synchronization signal sent by the central station 6 on the bus line 4.
  • These signals are applied respectively to a reset input and to a clock input of the binary counter 14.
  • This counter 14 comprises eight stages, the outputs of which are connected to eight address inputs of the read-only memory 15.
  • the read-only memory 15 comprises eight data outputs, seven of which are connected to seven inputs of the digital-analog converter 16, and one eighth of which is connected to a first control input of the analog gate 17.
  • One output of the digital-analog converter 16 supplies an analog value to an input of door 17.
  • the output of door 17 is connected to the output terminal 3 of the sensor.
  • the input terminal 2 first receives a synchronization pulse, which is transmitted by the separator 13 to the binary counter 14 to reset it, then 256 clock pulses which are transmitted to the binary counter 14 so that it successively supplies 256 address values to the memory 15.
  • the memory 15 provides on its eighth output a logic signal of value 1 for 16 consecutive address values corresponding to 16 clock pulses consecutive and thus validates the analog gate 17.
  • the analog gate 17 is validated during the time interval (t 0, t l ).
  • the other seven outputs of the memory 15 successively supply 16 binary words of 7 bits to the digital-analog converter 16 which thus synthesizes a waveform composed of 16 steps whose amplitude can take 128 values.
  • the signals emitted successively by sensors n ° 1, n ° 2, n ° 3, ... are transmitted by the bus line 5 to the central station 6 where they are authenticated to check that there is no fraud and change of state of one of the switches 1.
  • the output of the signal generator 8 is connected to an input of the separator 7 of synchronization signals and clock signals, identical to the separator 13 of the sensors.
  • the separator 7 provides a reset signal and a clock signal to the binary counter 9, identical to the counter 14 of the sensors.
  • the binary counter 9 has eight outputs which supply, during each interrogation cycle, 256 8-bit binary words to the address input of the read-only memory 10 which stores all the data stored in the read-only memories 15 of the sensors .
  • the output of the read-only memory 10 supplies 256 7-bit binary words to the inputs of the digital-analog converter 11, one output of which is connected to a first input of the comparator 12.
  • a second input of the comparator 12 is connected to the bus line 5, and an output from this comparator constitutes the exit terminal 18 of the central station.
  • the output of the digital-analog converter 11 provides an analog signal whose waveform consists of the series of waveforms of the signals expected as a response from the sensors.
  • the comparator 12 compares the series of waveforms supplied by the analog-converter 11 and the series of waveforms transmitted by the sensors and generates an alarm signal on the output terminal 18 if these two series of forms d are not identical. This case arises when there is a change in the state of a switch 1 or when there is sabotage of a sensor or one of the bus lines.
  • the interrogation mode described above has the advantage of great simplicity since a single bus line is sufficient to transmit addressing information, synchronization information, and a clock signal. It is possible to make the addressing more complex, to make it even more difficult to neutralize the system, for example by generating the addresses in a pseudo-random order.
  • the waveforms transmitted in response by the sensors can be very complex, and are therefore difficult to simulate, neutralizing the system is therefore practically impossible to achieve.
  • the sensors include simple logic means which it is easy to integrate into a compact hybrid circuit, which can be located in the immediate vicinity of switches 1 or other means generating an alarm to be transmitted.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Computer Security & Cryptography (AREA)
  • Business, Economics & Management (AREA)
  • Emergency Management (AREA)
  • Alarm Systems (AREA)
EP83400810A 1982-04-30 1983-04-22 Verfahren zum Schutz eines Fernüberwachungssystemes gegen Sabotage und System zur Ausführung dieses Verfahrens Expired EP0094279B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8207523 1982-04-30
FR8207523A FR2526190B1 (fr) 1982-04-30 1982-04-30 Procede de protection d'un systeme de telesurveillance contre un sabotage et systeme mettant en oeuvre ce procede

Publications (2)

Publication Number Publication Date
EP0094279A1 true EP0094279A1 (de) 1983-11-16
EP0094279B1 EP0094279B1 (de) 1986-02-19

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EP83400810A Expired EP0094279B1 (de) 1982-04-30 1983-04-22 Verfahren zum Schutz eines Fernüberwachungssystemes gegen Sabotage und System zur Ausführung dieses Verfahrens

Country Status (4)

Country Link
US (1) US4536748A (de)
EP (1) EP0094279B1 (de)
DE (1) DE3362154D1 (de)
FR (1) FR2526190B1 (de)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0173735A1 (de) * 1984-03-01 1986-03-12 Ultrak Inc Multiplexier-alarmsystem.
FR2578372A1 (fr) * 1985-03-01 1986-09-05 Fichet Bauche Procede de transmission de signaux, destines notamment a la surveillance d'un ensemble de zones a proteger, entre un poste central et une pluralite de circuits de detection relies a celui-ci par un support de transmission et systeme pour la mise en oeuvre d'un tel procede
FR2651938A1 (fr) * 1989-09-12 1991-03-15 Santerne Sa Procede de surveillance de l'etat d'au moins un moyen de detection, moyens en vue de la mise en óoeuvre de ce procede et installation de surveillance pourvue de ces moyens.

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JPH079680B2 (ja) * 1985-04-01 1995-02-01 ホーチキ株式会社 アナログ火災報知装置
US4691346A (en) * 1986-03-06 1987-09-01 American Telephone And Telegraph Company PBX integrity arrangement for maintaining the functional integrity of PBX communication devices and associated facilities
US4751498A (en) * 1986-03-11 1988-06-14 Tracer Electronics, Inc. Single-wire loop alarm system
US5140622A (en) * 1990-04-04 1992-08-18 Idec Izumi Corporation Data transmission system with double lines
US5272476A (en) * 1991-04-04 1993-12-21 The United States Of America As Represented By The Secretary Of The Navy Data acquisition system having novel, low power circuit for time-division-multiplexing sensor array signals
US5440293A (en) * 1992-05-29 1995-08-08 Pittway Corporation Detector supervision apparatus and method
GB2285157B (en) * 1993-12-23 1997-07-16 Talondale Limited An alarm system
US6614347B2 (en) 2001-01-30 2003-09-02 Ranco Inc. Apparatus and method for providing alarm synchronization among multiple alarm devices
US7184480B1 (en) * 2002-09-25 2007-02-27 O2Micro International Limited Digital PWM generator
US8183982B2 (en) * 2007-08-14 2012-05-22 Infineon Technologies Ag System including reply signal that at least partially overlaps request
US9785150B2 (en) 2015-12-11 2017-10-10 Uber Technologies, Inc. Formatting sensor data for use in autonomous vehicle communications platform
US10101747B2 (en) 2015-12-11 2018-10-16 Uber Technologies, Inc. Formatting sensor data for use in autonomous vehicle communications platform
US9596666B1 (en) 2015-12-11 2017-03-14 Uber Technologies, Inc. System for processing asynchronous sensor data
US9537956B1 (en) * 2015-12-11 2017-01-03 Uber Technologies, Inc. System for acquiring time-synchronized sensor data
US10114103B2 (en) 2016-03-31 2018-10-30 Uber Technologies, Inc. System and method for sensor triggering for synchronized operation
US10482559B2 (en) 2016-11-11 2019-11-19 Uatc, Llc Personalizing ride experience based on contextual ride usage data

Citations (4)

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Publication number Priority date Publication date Assignee Title
US3171108A (en) * 1960-11-23 1965-02-23 Mackeen John Crerar Valuable protection system
DE1259230B (de) * 1964-06-13 1968-01-18 Omron Tateisi Electronics Co Einrichtung zur Fernueberwachung
CH483683A (de) * 1967-11-27 1969-12-31 Securiton Ag Alarmübertragungsanlage mit einer Vielzahl von Alarmgebern
US3735396A (en) * 1971-08-10 1973-05-22 Signatron Alarm signalling network

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Publication number Priority date Publication date Assignee Title
US3665399A (en) * 1969-09-24 1972-05-23 Worthington Corp Monitoring and display system for multi-stage compressor
US4077030A (en) * 1976-02-19 1978-02-28 The Bendix Corporation Sensor data input by means of analog to pulse width-to digital converter
DE2638068C3 (de) * 1976-08-24 1986-11-13 Siemens AG, 1000 Berlin und 8000 München Brandmeldeanlage mit mehreren über eine Meldeschleife betreibbaren Meldern

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3171108A (en) * 1960-11-23 1965-02-23 Mackeen John Crerar Valuable protection system
DE1259230B (de) * 1964-06-13 1968-01-18 Omron Tateisi Electronics Co Einrichtung zur Fernueberwachung
CH483683A (de) * 1967-11-27 1969-12-31 Securiton Ag Alarmübertragungsanlage mit einer Vielzahl von Alarmgebern
US3735396A (en) * 1971-08-10 1973-05-22 Signatron Alarm signalling network

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0173735A1 (de) * 1984-03-01 1986-03-12 Ultrak Inc Multiplexier-alarmsystem.
EP0173735A4 (de) * 1984-03-01 1986-08-21 Ultrak Inc Multiplexier-alarmsystem.
FR2578372A1 (fr) * 1985-03-01 1986-09-05 Fichet Bauche Procede de transmission de signaux, destines notamment a la surveillance d'un ensemble de zones a proteger, entre un poste central et une pluralite de circuits de detection relies a celui-ci par un support de transmission et systeme pour la mise en oeuvre d'un tel procede
FR2651938A1 (fr) * 1989-09-12 1991-03-15 Santerne Sa Procede de surveillance de l'etat d'au moins un moyen de detection, moyens en vue de la mise en óoeuvre de ce procede et installation de surveillance pourvue de ces moyens.

Also Published As

Publication number Publication date
DE3362154D1 (en) 1986-03-27
FR2526190A1 (fr) 1983-11-04
US4536748A (en) 1985-08-20
FR2526190B1 (fr) 1985-11-08
EP0094279B1 (de) 1986-02-19

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