RU2414002C1 - Security alarm device - Google Patents

Abstract

FIELD: information technology.

SUBSTANCE: security alarm device has a signalling barrier fitted with a detecting element which is connected through a measuring amplifier to a gain-controlled amplifier and an operation indicator, as well as a digital signal processor whose first output is connected to the operation indicator, the second output - to a mode indicator, the third output - to the input of programmable memory, whose output is connected to the first input of the digital signal processor, the second input of which is connected to the output of the gain-controlled amplifier.

EFFECT: high functional reliability and detecting power owing to high noise immunity to natural factors.

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Description

The invention relates to alarm devices, signaling the fact of the intruder's invasion of the territory of the protected object upon the fact of mechanical vibrations created by the intruder in the structural elements of the physical barriers installed on the possible routes of the intruder's invasion of the guarded object, as well as the formation of an alarm message about the local deformation of the barrier and fixed to of a sensitive element in case of unauthorized penetration by a method of climbing over a barrier without using tions technology.

The technical result is to increase the functional reliability of detecting the fact that the intruder overcomes a physical obstacle both by climbing and by destroying the obstacle with a mechanical tool by increasing the noise immunity to the effects of natural factors.

The technical result is achieved by the fact that in the device, when analyzing the useful and interfering (caused by the influence of the wind on the obstacle) signals, a “floating” (adaptive) threshold level is formed, the dynamics of which are greater than the dynamics of changes in the levels of interfering signals, but less than the dynamics of changes in the levels of useful signals caused by the impact of the intruder on the fence.

As a result, the “floating” threshold signal fully monitors the interfering signal, but does not “keep pace” with changes in the useful signal, which causes a trigger when trying to overcome the obstacle.

A security alarm device is known (US patent No. 4090180, NKI 340/261, MKI G08B 13/22, published in 1978), in which the conversion of mechanical vibrations of the soil is carried out using sensitive elements (geophones) into an electrical signal, then amplification takes place and signal filtering, envelope selection, the formation of an adaptive threshold with constant and variable components.

The disadvantages of this device are the lack of functional reliability, low detectability with a given probability of false positives.

The closest in technical essence and the achieved positive effect to the claimed invention is a security alarm device (US patent No. 4742338, NKI 340/566, MKI G08B 13/00, published in 1988 - prototype), containing an alarm fence attached to it sensitive element, measuring amplifier, variable gain amplifier, band-pass filter, envelope detector, buffer, reference signal generation circuit, resistive divider, comparator, timer, 2I-NOT circuit, comparator, 2I-NOT circuit, score chik, clock generator, operation indicator. In this device, the conversion of mechanical vibrations of the signal barrage is carried out using a sensing element mounted on the signal barrage into an electrical signal, then amplification, filtering, envelope detection, the formation of a “floating” threshold level, comparison of the rectified signal with a threshold are performed.

The disadvantages of this device include the fact that the scheme for the formation of a “floating” threshold level (dynamic reference signal) has constant parameters determined based on the experience of the devices on these specific signaling barriers and under given environmental conditions. As convincingly shown in the dissertation, V. Ivanov “Systems for vibrometric detection of intruders in security alarm systems”, Penza, 2005, the parameters of signals generated by a sensitive element fixed to an alarm fence are largely determined by the physical and mechanical properties of the barrier (in particular, the degree of rigidity) and vary not only in depending on the type of fence (brick, wood, metal, wire, etc.), but also on its specific design (for example, the degree of mesh tension in the wire fence). Without adapting the parameters of the signaling device to the parameters of a particular signaling barrier, it is impossible to obtain a high detecting ability at a given probability of false alarms.

This drawback in the inventive device is eliminated by the fact that the mode of adaptation of the device parameters to the parameters of the signaling fence with a sensing element fixed to it is introduced. Moreover, this mode consists of two parts. In the first part, an alarm fence should only be under the influence of natural factors: wind, rain, snow, etc. In the second part, the user is invited to make a test overcoming the alarm barriers. The signals generated by the sensing element in the first and second parts are stored in memory. Based on the analysis of the stored signals, the transfer function of the link generating the dynamic reference signal is formed. The formation of the transfer function is based on the fact that the effect of gusts of wind on the signal barrage, as a rule, is more “soft” than the effect of the intruder when overcoming it. Thus, the envelope of signals caused by the influence of the intruder lies in a higher frequency region than the envelope of signals caused by the influence of the wind. The link generating the dynamic reference signal is a low-pass filter, the cutoff frequency and the number of poles of which are selected so that the envelope spectrum of the signals caused by the action of natural factors on the signal barrage lies in the passband, and the spectrum of signals caused by the intruder is in suppression band. A dynamic reference signal generated by a link with such a transfer function will completely repeat the envelope of signals caused by the influence of natural factors, and will differ from the envelope of signals caused by the influence of the intruder.

The aim of this invention is to increase the functional reliability of the device through the use of adaptive settings of the signal processing unit and to increase the detecting ability of the device at a given probability of false positives.

To achieve this goal, new significant features, functional elements and communications have been introduced into the known technical solution, which allow to increase the functional reliability and detecting ability of the device.

To achieve this goal, a digital signal processor, the first output of which is connected to the indicator of operation, and the second output, with a signal amplifier, are connected to a device containing an alarm barrier with a sensitive element fixed to it and connected through a measuring amplifier to an amplifier with an adjustable gain mode indicator, the third output is from the inputs of the reprogrammable storage device, the output of which is connected to the first input of the digital signal processor, the second input of which is connected to the output of an amplifier with an adjustable gain.

A comparative analysis of the claimed device with the prototype shows that the proposed device is distinguished by a new structural embodiment of the elements, their location in the circuit, the proposed device introduces a mode of adaptation of the device parameters to the parameters of the signaling fence with a sensitive element fixed to it.

Comparison of the claimed solution with other technical solutions in this technical field did not reveal the signs that distinguish the proposed technical solution from the prototype, which makes it possible to conclude that the criteria of the invention are met: “novelty”, “significant differences” and “positive effect”.

Figure 1 presents the structural diagram of the proposed device alarm, containing an alarm fence with a sensitive element (SE) 1 attached to it, connected through a measuring amplifier 2, with an amplifier with adjustable gain 3 and a trip indicator 4, digital signal processor (DSP) 5, the first output of which is connected to the operation indicator 4, the second output - with the mode indicator 6, the third output - with the input of the programmable storage device (EPROM) 7, the output of which is dinen with the first input of the digital signal processor 5, the second input of which is connected to the output of the amplifier with an adjustable gain of 3;

figure 2 - sequence of operations performed by the DSP, where:

8 - analog-to-digital Converter (ADC);

9 - notch filter;

10 - envelope detector;

11 - low-pass filter (low-pass filter);

12 - adder;

13 - a comparator;

figure 3 - graphs explaining the operation of the device:

a - interfering signal;

b - dynamic reference signal;

in - a useful signal.

The proposed device alarm is as follows.

As a sensitive element mounted on the signal fence 1, the telephone cable TPPep 10 × 2 × 05 (GOST R 51311-99) is used, two wires of which are fed to the direct and inverse inputs of the measuring amplifier 2. The signal from the output of the measuring amplifier 2 is fed to the input an amplifier with an adjustable gain of 3 installed on a particular signal barrier 1 so that the dynamic range of the signals from the output of this amplifier does not exceed the dynamic range of the ADC 8 built into the DSP 5. By the sequence of operations performed by the DSP 5 is shown in figure 2. The digitized ADC 8 signal is fed to a notch filter 9, which “cuts out” the industrial frequency of 50 Hz, then to the envelope detector 10. The rectified signal is fed to the “-” input of the comparator 13. A dynamic reference signal received from the rectified is received to the “+” input of the comparator 13 the signal by filtering in the low-pass filter 11 with an adjustable cutoff frequency and summing with a constant component in the adder 12. The cut-off frequency of the low-pass filter 11 is selected so that the spectrum of the rectified signal caused by exposure to the barrage of natural factors ( Specifically, wind gusts) is in the filter passband, and the rectified signal spectrum caused by exposure to the offending barrier, located in the stopband. Figure 3 shows the waveforms: a - interfering signal caused by wind; b - dynamic reference signal; c - a useful signal caused by the influence of the intruder. The shaded area is the area when the signal exceeds the threshold and, accordingly, the response of the device, which is displayed on the state of the operation indicator 4 (Fig. 1). The procedure for selecting the cutoff frequency of the low-pass filter 11 is as follows. After switching on, the device enters the parameter settings mode. Moreover, each current mode in which the device is currently located corresponds to a certain state of the indicator of mode 6 (Fig. 1). The parameter setting mode consists of two parts. In the first part, an alarm fence with a sensitive element fixed on it should only be under the influence of natural factors: wind, rain, snow, etc. In the second part, the user is invited to make a test overcoming the alarm barriers. In this case, the signals from the output of the envelope detector 10 (Fig. 2) are stored in the EEPROM 7. Based on the analysis of the stored signals, the transfer function of the link generating the dynamic reference signal is formed. The formation of the transfer function is based on the fact that the effect of gusts of wind on the signal barrage, as a rule, is more “soft” than the effect of the intruder when overcoming it. Thus, the envelope of signals caused by the influence of the intruder lies in a higher frequency region than the envelope of signals caused by the influence of the wind. The link generating the dynamic reference signal is a low-pass filter of the low-pass filter 11, the cutoff frequency and the number of poles of which are selected so that the envelope spectrum of the signals caused by the action of natural factors on the signal barrier 1 lies in the passband, and the spectrum of the signals caused by the intruder , - in the suppression band. The dynamic reference signal generated by the link with such a transfer function will completely repeat the envelope of the signals caused by natural factors, and will differ from the envelope of the signals caused by the intruder, as shown in Fig.3. The signal stored during the first part of the tuning mode is declared as interfering. The signal memorized in the second part is as useful. The procedure for selecting the cutoff frequency of the low-pass filter 11 begins with the maximum and is iterative. In each iteration, the stored useful signal is “driven” through the algorithm shown in FIG. 2 (with the exception of blocks 8, 9, 10) and the result is analyzed. The constant component supplied to the second input of the adder 12 (figure 2) is selected based on the maximum value of the change in the useful signal per clock cycle of the algorithm. If the device does not work, the cutoff frequency of the low-pass filter 11 is reduced by one discrete and the next iteration is performed. So, until a response occurs. Then, through the algorithm with the cutoff frequency thus found, the stored interfering signal is “driven” and the result is analyzed. If the device does not work, the parameter setting procedure is completed and the device enters the operating mode. If a trip occurs, the device declares the alarm fence 1 faulty (for example, an insufficient degree of tension of the wire fence mesh) and switches to the “Fault” mode.

The operating models of the security alarm device were tested for three years at security facilities in various climatic zones of the Russian Federation. In each case, the steady operation of laboratory models for detecting intruders was confirmed, including under conditions of wind, rain and thunderstorms.

Claims (1)

A security alarm device containing an alarm fence with a sensing element fixed to it and connected through a measuring amplifier to an amplifier with an adjustable gain and an operation indicator, characterized in that, in order to increase functional reliability and increase detection ability, a digital signal processor is introduced into it whose first output is connected to the operation indicator, the second output is with the mode indicator, the third output is with the reprogrammable input memory whose output is connected to a first input of the digital signal processor, a second input coupled to an output of the amplifier with adjustable amplification factor.

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