RU2342708C1 - Method of detecting unauthorised access into protected facilities - Google Patents

Abstract

FIELD: alarm systems.

SUBSTANCE: present invention pertains to security technology and can be used for detecting unauthorised access into facilities. The method involves transmission of an acoustic signal, reception and combined processing of the transmitted and received signals. Unauthorised access is determined from the change in parameters of mutual coupling of the signals. The acoustic signals are transmitted and received at different sides of the protected facilities. Inside the facilities and outside the facilities, a cross-correlation function of the transmitted and received signals is formed. Unauthorised access is determined from the change in the value of the maximum of the cross-correlation function of the transmitted and received signals.

EFFECT: increased efficiency of the method of detection, particularly increased accuracy.

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Description

The invention relates to security equipment and can be used to detect unauthorized access to the premises.

Known methods for the protection of premises by monitoring the integrity of walls, ceilings, windows, doors, based on the conversion of vibration, acoustic and power effects, leading to the destruction of these structural elements of the protected premises, or to their significant displacement.

Known electrical contact protection method implemented in the device according to patent RU No. 2280898, IPC G08B 13/08, 07/27/2006 - / 1 /. The alarm device includes a housing and a signal sensor, made in the form of a reed switch and a magnet. When the cover of the protected object is opened, the state of the magnetic contacts of the reed switch changes from closed to open, and information about this comes from its outputs to the alarm unit, in which this information is converted into a light or sound alarm signal about the opening of the object.

The disadvantage of this method is local control, where the monitored area is actually limited to one sensor location point.

With the acoustic protection method implemented in the alarm device (patent RU No. 2088972, IPC G08B 13/00, 08/27/1997) - / 2 /, the sound signal is analyzed in a protected room, which, when the protected structural elements are destroyed, acquires a characteristic structure, what the device signals. Most often, as in this patent, the method is implemented to identify the integrity of the glasses, since the sound of breaking the glass has the most characteristic sound features.

The disadvantage of this method is the low reliability of the information on the state of the controlled structural elements of the protected premises, since the violation of the integrity of the elements of the protected premises can be performed by an attacker in such a way that it will not be accompanied by intense sounds.

The closest in technical essence is the method implemented in the device described in the book "Security devices for home and office", publishing house "Lan", St. Petersburg, 1997 - / 3 /. Acoustic signals that are stable in frequency and amplitude (in this particular case, in the ultrasonic range) emit and convert into an electrical signal in the space of the room. In the case of unauthorized entry into a secure room, the amplitude of this signal changes significantly, and an alarm is generated by the magnitude of these changes.

The disadvantage of this method is the high probability of false positives. The system even responds to air flow, as the addition of the speed of sound with the speed of air will change the nature of the wave, which will be perceived as moving an object.

The technical result, to which the claimed invention is directed, is to increase the efficiency of the method for determining unauthorized entry, namely to increase its reliability.

The technical result is achieved by the fact that according to the method for determining unauthorized entry into a secure room, which consists in emitting an acoustic signal, receiving and co-processing the emitted and received signals, in which unauthorized entry is judged by changes in the parameters of their mutual connection, the new thing is that radiation and Acoustic signals are received on opposite sides of the protected premises, inside and outside, they form a cross-correlation function of the emitted and received signals, and unauthorized entry is judged by the change in the maximum value of the cross-correlation function of the emitted and received signals.

The drawing shows a structural diagram of a device that implements this method. The device comprises series-connected generator 1, amplifier 2 and acoustic emitter 3, as well as series-connected acoustic receiver 4, amplifier 5, moreover, acoustic emitter 3 and acoustic receiver 4 are acoustically connected through an obstacle in the form of doors, windows, walls, etc., correlator 6, the first input of which is connected to the output of the generator 1, the second input is connected to the output of the amplifier 5. The output of the correlator 6 is connected to the input of the alarm generating unit 7.

The alarm driver 7, in particular, can be made in the form of a threshold device 8, a light indicator 9, and an executive relay 10, the input of the alarm generating unit 7 being the input of a threshold device 8, the first and second outputs of which are connected respectively to the inputs of the light indicator 9 and executive relay 10.

The device operates as follows. Acoustic emitter 3, receiving a signal from generator 1 through amplifier 2, continuously emits a signal in a protected area. The receiver 4 is outside the protected zone, but within the audibility of the emitter 3. The signal from the receiver 4 through the amplifier 5 is fed to the first input of the correlator 6. At the second input of the correlator 6, the signal comes from the signal generator 1. Thus, at each moment of time, the correlator 6 generates cross-correlation function of two signals. The signal from the correlator 6 is fed to the alarm signal generation unit 7. If the room elements and the closed state of the windows and doors are kept intact, the maximum of the cross-correlation function will take on a certain value, its changes will take place within acceptable limits. Accordingly, the alarm driver 7 generates a notification about the normal state of the protected object. At the same time, the indicator light 9 does not light up, and the contacts of the executive relay 10 are closed to transmit notifications about the normal state of the protected object, for example, to a central monitoring console.

In case of unauthorized entry into a secure room due to opening a window, door, or destruction of the integrity of walls, ceilings, the maximum of the cross-correlation function increases significantly, since the acoustic coupling between the acoustic emitter 3 and the acoustic receiver 4 increases and is beyond the permissible limits. Accordingly, the alarm driver 7 generates an alarm notification, while the threshold device 8 switches the indicator light 9 to continuous light and de-energizes the executive relay 10 to transmit an alarm notification to the central monitoring station.

In the event of a device malfunction, including by intentionally incapacitating or deliberately affecting the acoustic channel, for example, by sound insulation of an acoustic emitter 3 or acoustic receiver 4, the maximum value of the cross-correlation function substantially decreases with respect to the permissible value, which will also lead to to the formation of an alarm notification by the alarm driver 7, while the threshold device 8 switches the indicator light 9 to the continuous mode and deenergizes Yelnia relay 10 for transmission to the central monitoring alarm notification.

Examples of implementation of the elements of the device.

The generator can be made according to the scheme with the Wien-Robinson bridge (see W. Titze, K. Schenk. "Semiconductor circuitry." M .: Mir, 1982, p. 303).

An example of the implementation of amplifiers 2.5 is presented in well-known schemes (see, for example, P.M. Tereshchuk. "Semiconductor receiving and amplifying devices. Radio amateur manual." Kiev: Naukova Dumka, 1981).

Correlator 6 can be performed, for example, according to the scheme proposed by the British Steel and Iron Research Association (BISRA) (see http://masters.donntu.edu.ua/2000/fvti/tolpa/diplom.htm).

An example implementation of threshold device 8 is a two-threshold comparator according to the scheme presented in A.G. Alekseenko. “The use of precision analog microcircuits” (M .: Radio and communications, 1985, p. 187).

In addition, all operations for implementing this method, except for acoustic radiation and acoustic reception, can be implemented using a computer, and musical phonograms can be used as the emitted signal.

Acoustic radiation and acoustic signal reception can be realized using standard loudspeakers and microphones, which are part of the equipment for voice notification and music broadcasting, often already available as part of a building security system, for example, manufacturer Inter-M, Korea. In this case, all of the above operations necessary for the implementation of the method can be implemented on the computer that is part of the voice alert rack.

Thus, a method has been proposed that, with minimal hardware costs, including the partial use of equipment already available at the protected facility, can improve the reliability of registration of unauthorized entry into the secure premises.

Claims (1)

A method for determining unauthorized entry into a guarded room, which consists in emitting an acoustic signal, receiving and co-processing the emitted and received signals, in which unauthorized entry is judged by changes in the parameters of their mutual connection, characterized in that the radiation and reception of acoustic signals are carried out on opposite sides of the guarded the premises, inside and outside, form a cross-correlation function of the emitted and received signals, and of unauthorized entry judged by the change in the maximum value of the cross-correlation function of the emitted and received signals.