RU2337405C1 - Device for person or group detection by seismic signals - Google Patents

Abstract

FIELD: physics.

SUBSTANCE: device includes seismic receiver, voice filter, envelope detector, indication calculation unit and surveillance interval generator, correlation unit and reference signal matrix, maximum vector detector and reference code register, threshold device and 'AND' circuit. To maintain high detection efficiency and jamming resistance, the device calculates 200 indicators, reference signal matrix and reference code register are used. Decision on detection of effective trespasser or group is made according to the maximum product of input signal indication vector to reference matrix, and jamming resistance is achieved due to definition of reference code, at which the said maximum product was obtained, and sending prohibiting or allowing signal to 'AND' circuit.

EFFECT: high efficiency of human detection, enhanced jamming resistance of device.

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Description

A device for detecting a person and a group of people by seismic signals belongs to the field of security equipment and can be used to detect moving intruders by their seismic signals when guarding territories and approaches to various objects.

Known "Device for intrusion detection" [1], containing (Fig. 1): 1 - seismic receiver (SP), 2 - bandpass filter (PF), 3 - envelope detector (DO), 4 - block calculation of signs (BWP) 5 - the threshold device (PU) and 6 - the decisive authority (RO).

In the device under consideration, the detection of a person and a group of people is based on the calculation of signs: the duration of the exposure pulse, the pulse repetition period, and the average level of the envelope.

The disadvantage is that the probability of correct detection depends on the size of the period of steps and on the thresholds U ₁ , U ₂ , U ₃ , which are not adapted to the conditions of use.

Of the known closest in technical essence is the "Device for processing seismic signals for alarm systems" [2], containing (figure 2): 1 - seismic receiver (SP), bandpass filter (PF), 3 - threshold device (PU) 4 - correlator, 5 - shaper of the observation interval (FIN), 6 - timer, 7 and 9 - scheme "I", 8 - scheme "OR", 10 - zero level comparator (KNU), 11 - frequency comparator (ChK) .

If the input seismic signal exceeds the threshold U ₁ , the value of which is set taking into account the seismic background of the environment, the periodic nature of the sequence of input pulses is determined in the correlator, i.e. correspondence of the repetition period of the correlated pulses to the selected correlation interval Δt. In the presence of a sequence of correlated pulses, the observer of the observation interval starts. If the generated observation interval is greater than the specified averaging interval (threshold U ₂ ), and the number of correlated pulses in the received signal for the averaging interval is greater than the threshold U ₃ , then the number of crossings by the zero level signal for the generated averaging interval is calculated in the frequency comparator. The resulting attribute value is compared with a threshold value (U ₄ ). If the threshold is exceeded (with high-frequency interference) for the observation interval in the "I" circuit, a decision is made about the absence of a useful signal, otherwise a decision is made about the presence of an intruder. Depending on the value of the characteristic, a decision on the type of object is also possible.

The disadvantage is that the operational efficiency and noise immunity of the device depends on several threshold values: the level of environmental seismic noise, the correlation interval, the length of the averaging interval, and the number of correlated pulses over its duration. A predetermined correlation interval will lead to a decrease in the efficiency of the device, since the pulse repetition period in the seismic signal of the intruder varies depending on the nature and speed of the intruder and their number.

The present invention is aimed at improving the detection efficiency of the offender or group of offenders.

This is achieved by the fact that in the device for processing seismic signals for alarm systems, containing a bandpass filter connected to the output of the seismic receiver, the observer of the observation interval, the correlator, the threshold device and the circuit "And", according to the invention, an additional signal envelope detector, a calculation unit features, matrix of standards, the detector of the maximum value of the vector and the code register of the standards, and the input of the envelope detector of the signal is connected to the output of the bandpass filter, and output - to the first input of the feature calculation unit, to the second input of which the observer of the observation interval is connected, and the output of the feature calculation unit is connected to the first input of the correlator, the second input of which is connected to the matrix of standards, the output of the correlator is connected to the input of the detector of the maximum vector value, the first output of which connected to the input of the threshold device, and the second output to the input of the code register of the standards, the output of the threshold device is connected to the first input of the AND circuit, the second input of which is connected to the output standards code register.

The calculation of 200 features in the feature calculation unit according to formulas 1 and 2 allows to increase the efficiency of the device by highlighting useful information about the properties and nature of the seismic signal. At a sampling frequency of 60 Hz, 200 features are computed over a time of approximately 3.33 s.

The introduction of a matrix of standards containing values of 200 features obtained from various seismic signals of a moving intruder or group of intruders, as well as interference signals of both artificial and natural origin, allows us to assign the input signal to the signal of the intruder, seismic background or interference, without using fixed threshold values period and number of correlated pulses, and also provides the ability to adapt the device to changes in operating conditions through the procedure of "additional training" matrix standards.

The introduction of the detector of the maximum value of the vector allows you to determine the maximum value of the product of the matrix of standards and the feature vector of the input signal, the value of which will be different for the seismic signals of the intruder, the seismic background and interference.

The introduction of the code register of the standards allows to increase the noise immunity of the device by determining the code of the standard, the product of which (standard) with the vector of signs of the input signal gave the maximum result. The reference code is set to "1" for the seismic signals of the intruder or group of people and "0" for the seismic background and interference. When forming a matrix of standards, a vector is formed in parallel, consisting of codes of the corresponding standards, which is then stored in the code register of the standards.

Figure 3 presents a block diagram of the proposed device for detecting a moving person and a group of people by seismic signals.

Figure 4 graphically depicts a matrix of features.

Figure 5 graphically depicts a matrix of standards.

Figure 6 graphically presents the result of the product of the matrix of signs of the input signal with a matrix of standards.

Figure 7 presents the test result of the detector on the seismic signal of a walking person.

On Fig presents the result of testing the device on a seismic signal of a group of walking people.

Figure 9 shows the evaluation of the noise immunity of the device on the signal of the seismic background in the forest.

The device (figure 3) contains:

1 - seismic receiver;

2 - band-pass filter operating in the range of 1 ... 30 Hz;

3 - signal envelope detector;

4 - block calculation 200 features;

5 - shaper of the observation interval, the value of which is fixed and equal to 1 s;

6 - correlator;

7 - matrix of standards;

8 - detector of the maximum value of the vector;

9 - register code standards;

10 - threshold device;

11 is a diagram of the "AND".

In this case, the seismic receiver 1 is connected to a band-pass filter 2, the output of which is connected to the input of the envelope detector of the signal 3; a feature calculation unit 4, the first input is connected to the output of the envelope detector 3, and the second input is connected to the output of the observer of the observation interval 5; the correlator 6 is connected by the first input to the output of the feature calculation unit 4, and the second input is connected to the matrix of standards 7; the output of the correlator 6 is connected to the input of the detector of the maximum value of vector 8, the first output of which is connected to the input of the threshold device 10, and the second output is connected to the input of the code register of the standards 9; the output of the threshold device 10 is connected to the first input of the AND circuit 11, the second input of which is connected to the output of the code register of the standards 9.

A device for detecting a person and a group of people by seismic signals as follows.

The input of the bandpass filter 2 receives a seismic signal from the output of the seismic receiver 1, which is filtered in the range of 1 ... 30 Hz.

The smoothed envelope of the seismic signal after the envelope detector of signal 3 is supplied to the first input of the feature calculation unit 4. In the feature calculation unit 4, the feature vector is computed for the observation interval, which is fed to the second input of feature calculation unit 4 from the output of the observation interval generator 5. Its value is fixed and chosen equal to 1 s, since during this time, in the presence of a moving intruder, at least one pulse will be present in the seismic signal.

When calculating the feature matrix M1, dependencies (1, 2) are used.

Where

n is the averaging time of attributes equal to 6 s; x is the vector of discrete samples of the envelope of the signal; N is the length of the vector in samples (N = 200), j = 0, 1, ... N. Index i = 0, 1, 2 ... sets the shift of the time window for analyzing the current vector with a resolution of 1 s, which provides a decision about detection every second. The calculation of features is based on finding normalized correlation moments and their averaging.

Figure 4 shows the matrix of signs M1, calculated in a time of 60 s for a seismic signal of one person walking along a straight path in the sensitivity zone of a seismic receiver 70 ... 100 m.

In the correlator 6 is the product of the matrix of signs M1, arriving at the first input of the correlator 6 and the matrix of standards 7 (Fig. 5), arriving at the second input of the correlator 6.

The matrix of reference signals 7, containing the values of 200 signs of seismic signals of the intruder or group of intruders, seismic background and interference, is formed in the process of "training" of the device. Moreover, in the process of its formation, information about the belonging of each standard to a useful signal, seismic background or interference in the code register of standards 9 is stored. Each code in the code code register of standards 9 is respectively assigned a code “1” for a useful signal or “0” for seismic background signals or interference.

A matrix of 60 M1 standards used in a real detector of a person or group of people is shown in Fig. 5.

For a real seismic signal of a moving one person, Fig. 6 shows the result of multiplying the feature matrix M1 with the template matrix M2.

The use of the matrix of standards 7 gives ample opportunities for operational correction of the detection algorithm. When developing the algorithm, it is impossible to take into account all the features of signal formation inherent in the specific conditions of its application. Therefore, the algorithm provides for the possibility of “further training” to eliminate the false operation of the algorithm, for example, from a previously unrecorded form of interference or under previously unrecorded operating conditions. The “additional training” procedure provides a quick adjustment of the algorithm and thereby allows one to tune away from the influence of various kinds of external factors, both natural and artificial, characteristic of the area where the seismic detection system is used.

The vector obtained in correlator 6 is fed to the input of the detector of the maximum value of vector 8, in which the maximum value of the vector and the index of the standard are determined, with which this maximum was obtained by multiplying.

In the threshold device 10, the maximum value of the product of the matrix of standards and the feature vector of the input signal arriving at the first input are compared with the threshold U ₁ . When exceeding the input threshold value at the output of the threshold device 10 is formed "1". As a result of preliminary studies for the seismic signals of one person or group of people, the threshold value U _{1 is} chosen equal to 30 units.

In the register of code of standards 9, the code of the standard is determined, the index of which is input from the second output of the detector of the maximum value of vector 8. As a result, the output of the register of code of standards 9 will contain "1" ("permission") or "0" ("ban") respectively, for the seismic signal of the intruder and the seismic background or interference.

In the scheme "And" 11, a decision is made to detect the violator or its absence. If the input “I” 11 receives “0” at the second input, then a “ban” on the detection of a useful signal occurs, which increases the noise immunity of the device.

For a real seismic signal of one person, on which the matrices M1, M1 × M2 were constructed (Figs. 4, 6), Fig. 7 shows the result of the detector. Fig. 7a shows the initial signal and the detection signal; Fig. 7b shows the decision threshold and the schedule for changing the maximum value of the product of matrices M1 and M2.

On figa shows the result of the detector on the example of a seismic signal of 3 people walking in a circle with a radius of 50 m relative to the joint venture, and a graph of the maximum value of the product matrix M1 × M2 is shown in figb. From the drawing it can be seen that the detection of violators is quite confident.

A significant property of any device is the noise immunity of its operation. To assess the noise immunity of the proposed device, the signals of the seismic background were recorded in forest conditions with gusts of up to 18 m / s. The test results of the detector are shown in Fig.9.

The result shows that during 13 minutes of exposure to large seismic interference caused by the movement of tree roots under the influence of wind, the algorithm did not give a false positive.

The proposed device allows you to ensure the probability of detecting a moving person or group of people is not lower than 0.97 in a radius of 70 m from the joint venture with a probability of false positives of not more than 0.001 (in the presence of interference of natural and artificial origin). In forest conditions, the detection range of a person or group of people is reduced to 30 m. The proposed device allows to solve the detection problem for violators moving in steps, jogging, skiing, in a plastopian way.

The presented device works well on any type of soil and, as a rule, does not require individual settings for it.

Information sources

1. US patent 3879720 G08B 13/00, George James Dusheck. Energy peak / time averaging seismic intrusion detec.

2. Patent RU 2242799, G08B 13/16. Burmistrov E.C., Glazunov B.P., Gruzdov V.A., Okulov S.A., Olkhovskaya I.V., Frolov S.B. Seismic signal processing device for burglar alarm systems.

Claims (1)

A device for detecting a person and a group of people by seismic signals, containing a band-pass filter connected to the output of the seismic receiver, an observer of the observation interval, a correlator, a threshold device and an "I" circuit, characterized in that the signal envelope detector and a feature calculation unit are additionally introduced into the device , matrix of standards, the detector of the maximum value of the vector and the code register of the standards, and the input of the envelope detector of the signal is connected to the output of the bandpass filter, and the output to the first input of the block feature calculation, to the second input of which the observer of the observation interval is connected, and the output of the feature calculation unit is connected to the first input of the correlator, the second input of which is connected to the matrix of standards, the output of the correlator is connected to the input of the detector of the maximum vector value, the first output of which is connected to the input of the threshold device and the second output is to the input of the code register of the standards, the output of the threshold device is connected to the first input of the "AND" circuit, the second input of which is connected to the output of the register of the code of standards.

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