EP0286897A1 - Méthode et dispositif de surveillance d'espaces clos - Google Patents

Méthode et dispositif de surveillance d'espaces clos Download PDF

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Publication number
EP0286897A1
EP0286897A1 EP88104957A EP88104957A EP0286897A1 EP 0286897 A1 EP0286897 A1 EP 0286897A1 EP 88104957 A EP88104957 A EP 88104957A EP 88104957 A EP88104957 A EP 88104957A EP 0286897 A1 EP0286897 A1 EP 0286897A1
Authority
EP
European Patent Office
Prior art keywords
room
volume
changes
alarm device
frequency
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.)
Withdrawn
Application number
EP88104957A
Other languages
German (de)
English (en)
Inventor
Peter Ryser
Sigfrid Straessler
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Cerberus AG
Original Assignee
Cerberus AG
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 by Cerberus AG filed Critical Cerberus AG
Publication of EP0286897A1 publication Critical patent/EP0286897A1/fr
Withdrawn legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G08—SIGNALLING
    • G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
    • G08B13/00—Burglar, theft or intruder alarms
    • G08B13/16—Actuation by interference with mechanical vibrations in air or other fluid
    • G08B13/1609—Actuation by interference with mechanical vibrations in air or other fluid using active vibration detection systems
    • G—PHYSICS
    • G08—SIGNALLING
    • G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
    • G08B13/00—Burglar, theft or intruder alarms
    • G08B13/16—Actuation by interference with mechanical vibrations in air or other fluid
    • G08B13/1654—Actuation by interference with mechanical vibrations in air or other fluid using passive vibration detection systems
    • G08B13/1681—Actuation by interference with mechanical vibrations in air or other fluid using passive vibration detection systems using infrasonic detecting means, e.g. a microphone operating below the audible frequency range

Definitions

  • the invention relates to a method for monitoring closed rooms against unauthorized opening and penetration according to the preamble of claim 1, and a device for carrying out the method according to claim 1.
  • the method according to the invention can be used for monitoring any closed rooms which have a closed, relatively tight envelope with respect to the outside world, e.g. of exhibition showcases, museum showcases, safes, window displays, cars or closed boats. Since windows with double glazing also represent a space that is closed off from the outside world, such windows can also be protected using this method.
  • an anti-theft device for vehicles with a vibration detector US-A-3 ⁇ 721 ⁇ 956)
  • a protective curtain for windows as an anti-theft device for cars CH-A-453 ⁇ 961
  • an anti-theft alarm device for car radios DE -A1-35 ⁇ 13 ⁇ 114 with a spring contact or a system for securing car radios with a memory for a code word, whereby the commissioning of the device after removal is made impossible without entering the code word.
  • DE-C1-35 ⁇ 29 ⁇ 402 proposes a method for monitoring the state of rooms in which the natural frequency of a motor vehicle body, which is in the audio frequency or ultrasound range, and the harmonics which form when the body is impacted are used.
  • the change in the harmonic spectrum caused by breaking a window or opening a door is measured and used to trigger an alarm.
  • a disadvantage of this method is that the character The harmonic spectrum also changes when it rains, snows or hails on the car.
  • Methods for securing rooms have also become known which use the characteristic changes in air pressure which occur when doors and windows are opened to trigger an alarm.
  • a sound sensor in the manner of a barometer serves as a sensor.
  • a pyrodetector is used, i.e. the temperature changes caused by the infrasonic waves are recorded. Both methods are passive systems. In order to detect slow changes in air pressure, they have to be set very sensitively. This increases their tendency to false alarms considerably.
  • the invention has for its object to provide a method and a device for monitoring rooms, which does not have the disadvantages of the methods of the prior art, and in particular to provide such a method that is safe against interference and false alarms and a low circuit - And apparatus expenditure, and has a low power consumption.
  • the volume of a room that has a shell that is sealed to the outside world is changed periodically in a defined manner as a function of time.
  • the resulting pressure fluctuations are detected by a sensor and processed by means of an evaluation circuit.
  • the evaluation circuit preferably comprises a microprocessor which controls the periodic volume changes and the pressure detected by the sensor evaluates and stores fluctuations.
  • a violation of the outer shell causes a change in the pressure fluctuations in the room, which causes a corresponding change in the output signal of the sensor.
  • Switching elements are provided in the evaluation circuit, which register the changes in the pressure fluctuations and compare them with the pressure fluctuations in the normal state. Further switching elements are also provided which trigger an alarm in the event of deviations in the pressure fluctuations downwards or upwards.
  • the invention is explained with reference to the embodiment shown in the drawing.
  • the figure shows a circuit diagram of an example of a monitoring system that can be used in the method according to the invention.
  • the volume V of a space 1 delimited by an envelope 2 is changed periodically by moving the membrane 4 of a loudspeaker 3 in motion.
  • the frequency of the vibrations is selected depending on the size of the room to be monitored and its relative tightness to the outside world.
  • the working frequency f must be chosen so that the relationship is satisfied.
  • S is the minimum area of the intrusion opening to be detected
  • c is the speed of sound in the medium.
  • the upper limit is the area of perception of human hearing. In theory there is no lower limit. In practice, however, there is a limit in that the commercially available inexpensive microphones in the range of less than 5 Hz are no longer sufficiently sensitive to receive easily amplifiable signals. A preferred frequency range of approximately 5 Hz to approximately 15 Hz is thus obtained.
  • the excitation signal for the loudspeaker is supplied by a microprocessor 8, converted into an analog signal by a digital / analog converter 7 and, after amplification in a first amplifier 9, the loudspeaker 3 fed.
  • the microprocessor 8 can be programmed in a simple manner in such a way that when it is installed in the system, it is too tight guarding room or each time the system is armed within the preferred range, scans the wavelengths and then operates the system at the wavelength that is optimal for the room size.
  • the loudspeaker 3 is then preferably operated at this frequency with a sinusoidal signal of constant amplitude.
  • the signal at the output of the digital / analog converter 7 can be used, for example, to control the AF amplifier of a car hi-fi stereo system if the existing speakers are suitably installed, i.e. either form part of the shell 2 or are closed systems to the rear.
  • the invention is therefore particularly suitable for protecting the closed interior of vehicles by using existing, standard equipment.
  • p 0 is the pressure that prevails in the closed space 1 with the casing 2 undamaged.
  • the pressure variation ⁇ p which has the same change over time as the vibrations of the loudspeaker membrane 4, is detected with a microphone 5, which has a sufficient sensitivity in the frequency range between 5 Hz and 15 Hz.
  • the pressure variation can also be detected with any other commercially available sensor that is able to measure pressure changes in the frequency range mentioned.
  • the signal picked up by the microphone 5 is amplified in a second amplifier 6, converted into a digital signal in an analog / digital converter 11 and fed to the microprocessor 8, in which it is evaluated using a suitable correlation method.
  • This correlation method has the task of realizing a narrow-band filter that only evaluates the vibrations that are emitted by the loudspeaker 3. Doing this from the start eliminates interference from noise outside the area used.
  • ⁇ p (t) kpV (t) / V, where ⁇ p (t) is the change in pressure detected by the microphone as a function of time, V (t) the volume change induced by the loudspeaker as a function of time, k the adiabatic constant, P 0 the pressure in the closed space 1 and V is the volume of the enclosed space mean.
  • the volume V is increased. With a rapid increase in volume, e.g. when opening a door or breaking a window, this results in a rapid decrease in the detected signal ⁇ p (t). However, if the volume of the room 1 to be monitored is slowly increased, e.g. by carefully opening a sliding door of an exhibition showcase, the signal can experience a sharp increase if the Helmoltz resonance conditions are met.
  • the amplified and digitized signals of the sensor 5 are compared in the microprocessor 8 with the signals stored for the normal state.
  • the microprocessor 8 is programmed so that an alarm relay 10 is activated when the detected and correlated signal ⁇ p (t) deviates upwards or downwards from the stored values by a predetermined value.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Burglar Alarm Systems (AREA)
EP88104957A 1987-04-09 1988-03-28 Méthode et dispositif de surveillance d'espaces clos Withdrawn EP0286897A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
CH1373/87 1987-04-09
CH137387 1987-04-09

Publications (1)

Publication Number Publication Date
EP0286897A1 true EP0286897A1 (fr) 1988-10-19

Family

ID=4208901

Family Applications (1)

Application Number Title Priority Date Filing Date
EP88104957A Withdrawn EP0286897A1 (fr) 1987-04-09 1988-03-28 Méthode et dispositif de surveillance d'espaces clos

Country Status (1)

Country Link
EP (1) EP0286897A1 (fr)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1992006456A1 (fr) * 1990-10-04 1992-04-16 Nordic Technology A/S Dispositif d'alarme domestique
DE4303388A1 (de) * 1993-02-05 1993-09-30 Dirk Meyer Verfahren und Vorrichtung zur Überwachung von geschlossenen Räumen
EP0609932A2 (fr) * 1993-02-01 1994-08-10 General Motors Corporation Détecteur d'intrusion pour véhicules
EP0916969A2 (fr) * 1997-11-11 1999-05-19 GRUNDIG Aktiengesellschaft Appareil d'alarme pour autoradio
EP1375269A1 (fr) * 2002-06-25 2004-01-02 Siemens Aktiengesellschaft Procédé de surveillance acoustique
DE202009000500U1 (de) * 2009-01-16 2010-03-18 Klafs Gmbh & Co. Kg Saunakabine mit Zugangsüberwachung

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3898640A (en) * 1972-07-31 1975-08-05 Romen Faser Kunststoff Method and apparatus for providing space security based upon the acoustical characteristics of the space
FR2542116A1 (fr) * 1983-02-25 1984-09-07 Verdon Roger Dispositif d'elimination des fausses alarmes

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3898640A (en) * 1972-07-31 1975-08-05 Romen Faser Kunststoff Method and apparatus for providing space security based upon the acoustical characteristics of the space
FR2542116A1 (fr) * 1983-02-25 1984-09-07 Verdon Roger Dispositif d'elimination des fausses alarmes

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1992006456A1 (fr) * 1990-10-04 1992-04-16 Nordic Technology A/S Dispositif d'alarme domestique
EP0609932A2 (fr) * 1993-02-01 1994-08-10 General Motors Corporation Détecteur d'intrusion pour véhicules
EP0609932A3 (fr) * 1993-02-01 1995-04-05 Gen Motors Corp Détecteur d'intrusion pour véhicules.
DE4303388A1 (de) * 1993-02-05 1993-09-30 Dirk Meyer Verfahren und Vorrichtung zur Überwachung von geschlossenen Räumen
EP0916969A2 (fr) * 1997-11-11 1999-05-19 GRUNDIG Aktiengesellschaft Appareil d'alarme pour autoradio
EP0916969A3 (fr) * 1997-11-11 1999-11-03 GRUNDIG Aktiengesellschaft Appareil d'alarme pour autoradio
EP1375269A1 (fr) * 2002-06-25 2004-01-02 Siemens Aktiengesellschaft Procédé de surveillance acoustique
DE202009000500U1 (de) * 2009-01-16 2010-03-18 Klafs Gmbh & Co. Kg Saunakabine mit Zugangsüberwachung

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