RU2273867C1 - Seismic arrangement for determination of objects' coordinates - Google Patents

Abstract

FIELD: the invention refers to technical means of guarding.

SUBSTANCE: it may be used for determination of the coordinates of detected objects, their middle speed and trajectory of movement, computation of quantity of objects in a group target and classification of detected objects. The seismic arrangement for determination of the objects' coordinates uses mode of scattered passive location. The main informative indication for determination of the direction on an object in each system of coordinates is a function of mutual correlation of signals in the channels of a signals correlative processing block. In accord with the value of a signal's delay decision is made about the value of an azimuth on the object in each system of coordinates. The determined azimuths on the object and fixed distance between the centers of coordinate systems allow to determine current coordinates of the object.

EFFECT: increases informative functions of seismic means of detecting.

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Description

The invention relates to technical means of protection and can be used to determine the coordinates of the detected object and its classification when protecting extended sections of the terrain, territories and approaches to the objects.

Known methods of spaced acoustic passive location for determining the azimuth to detectable objects implemented in the correlator [1], where the main information sign for determining the direction to the object is the function of the mutual correlation of two signals, as well as a seismic correlation direction finder of objects [2], designed to determine the azimuth to the detected object and its classification by seismic channel

Closest to the proposed is a seismic correlation direction finder of objects (Figure 1) [2], implemented on the principle of a multi-channel correlation meter for the difference in time delay [1]. In each of its channels, inter-correlation processing is carried out, calculated for a certain value of the signal delay.

The structural diagram of the seismic correlation direction finder of objects includes a delay line of the channel of the first signal at ₁ (t), a delay line with taps of the channel of the second signal at ₂ (t), correlators X1, X2, ... Xn, a resolver, a maximum signal selector, and a classifier. Two channels receive signals at ₁ (t) and at ₂ (t), formed by the same, spaced apart, sensitive elements. The nature of the signals is determined by the class of the detected object. The first signal is considered to be the reference signal and is supplied to the first inputs of all correlators. The second signal with various delay times is supplied to the second inputs of all correlators. At the outputs of the correlators, a mutual correlation function of two signals is formed. The maximum value of the mutual correlation function is formed at the output of the correlator, the input of which receives a signal delayed by the delay of the wave front entering one geophones relative to the other geophones, i.e. the compensation condition for the difference in the wave travel is fulfilled. The delay time of the signal depends on the direction to the object and, therefore, allows you to estimate the azimuth to the object.

The disadvantage of this device is the presence of a imaginary imaginary azimuth to the object relative to the axis on which the geophones are located, as well as the inability to obtain additional information about the coordinates of the object, its trajectory and speed.

The proposed device provides an increase in the information content of seismic detection tools by eliminating the imaginary imaginary azimuth, determining the current coordinates of the detected object, and therefore determining the trajectory and average speed of the object.

For this, another group of two seismic detectors SP2-1, SP2-2 with an identical correlation processing unit (Figure 2), operating independently of the first group of seismic detectors SP1-1, SP1-2, is added to the seismic correlation direction finder of the objects.

Seismic waves are received by four seismic receivers with amplifiers, spaced a certain distance L between each other, forming a square or rectangle (Figure 3), where L is the seismic base for receiving seismic oscillations, D is the distance between the parallel axes OX and O ₁ X ₁ , on which there are, respectively, the group of geophones SP1-1, SP1-2 and the group of geophones SP2-1, SP2-2. Seismic receivers and amplifiers are identical.

The distances traveled by the seismic waves from the sources of seismic oscillations to the geophones are not the same, and therefore, they differ in the phase of the received signal. The delay of one of the signals depends on the position of the source of the seismic waves relative to the geophones and the distance L (seismic base).

The speed of propagation of seismic waves depending on the type of soil is 400 ... 1000 m / s [3], therefore, it is possible to calculate the delay time of the arrival of the wave.

Since the signal in all channels is the same, and microseisms and some types of interference (rain noise, grass rustling ...) in the channels are independent, in each channel there will be oscillations of the form ₁ (t), ₂ (t), ₃ (t) and ₄ (t):

where y ₁ (t), y ₂ (t), y ₃ (t) and y ₄ (t) are the input oscillations in the first, second, third and fourth channels, which are an additive mixture of the signal S (t) and noise n ₁ (t), n ₂ (t), n ₃ (t) and n ₄ (t) in each channel, respectively.

In the correlators, the signals are multiplied in pairs n ₁ (t) with n ₂ (t), n ₃ (t) with n ₄ (t), and the interference signals are mutually suppressed.

The implementation of the cross-correlation function of signals from one source in two independent channels takes maximum values in case of compensation of the delay time of a signal in one of the channels due to the inclusion of a delay line. The number of correlators equal to n is determined by the convenience of using n delay lines with a fixed delay time. The number of correlators is determined by the required accuracy of determining the azimuth to the object.

In the general case, it is necessary to provide a total signal delay in the range from −Δt to Δt using n delay lines. The time interval Δt is determined by:

where L is the seismic base;

U is the propagation velocity of seismic waves.

The presence at the outputs of several correlators of local maxima of the mutual correlation function corresponds to the situation when several objects are present at the boundary. On this basis, the number of objects in the controlled area is estimated.

The seismic base L and the distance D between the parallel axes OX and O ₁ X ₁ are selected based on the requirements for the coordinate determination device.

The mutual correlation function of the signal from the detection object received by two identical channels, formed by the correlator (Figure 2), is nothing more than an autocorrelation function, but with different signal delay times.

At the outputs of all the correlator signal multipliers, there will be signals obtained as a result of multiplying the input signals. The signal raised to the second degree will be observed at the output of that multiplier, the second input of which receives a signal delayed by the arrival time of the seismic wave. Consequently, the signal at the output of the multiplier will contain complete information about the class of the object being bearings, which allows further classification according to some characteristic (frequency band, behavior of the signal function, ...).

The operation of the device is implemented as follows (Fig.2, 3). The first block of correlation processing 8 receives seismic signals from geophones SP1-1, SP1-2. In the initial state, seismic signals are received by two SP1-1, SP1-2 seismic receivers spaced in space. Seismic signals arrive at two processing channels. The first channel, including cascades of pre-processing and one delay line 1, is conditionally adopted as a reference. The second channel includes a set of delay lines 2 and the same number of correlators consisting of a multiplier 4 and an integrator 5 each (3, 6, 7 - correlators of the first, second, and nth channels). The signals at the outputs of all correlators are compared by a decider 11. If the signals generated at the outputs of all correlators are the same or slightly different, then the decision about the azimuth to the object is not made, and the maximum signal selector 9 and classifier 10 are not involved. This corresponds to a situation where an object is absent in the detection zone or a disturbance dispersed in space is present.

If an object appears in the detection zone at the outputs of the correlators, the signals will not be the same. The solving device 11 according to the criterion of the maximum of the mutual correlation function at the outputs of the correlators, a decision is made on the azimuth to the detected object in the XOY coordinate system (angle α) (Figure 3). The solver 11 determines the correlator with the maximum output signal; it generates a command for the maximum signal selector 9 to connect the output of the multiplier 4 of this correlator to the classifier 10. Classifier 10 decides on the proposed class of the detected object.

Switching the correlator outputs by the maximum signal selector 9 means controlling the direction finder pattern. In the case of the presence of several objects at the guarded line, maximums are observed at the outputs of several correlators. Alternate switching of the maximum signal selector 9 outputs of the correlators to the classifier 10 allows you to sequentially classify detected objects. It is possible to count the number of objects at the guarded border if the objects are located at a distance from each other that allows them to be fixed separately, i.e. in the case of a narrow radiation pattern, in which the system of seismic sensors has an azimuth resolution.

The second block of correlation processing 12 works in a similar way, to which seismic signals from seismic detectors SP2-1, SP2-2 come with the only difference being that the resolver 13 determines the azimuth to the detected object (angle β) in its auxiliary coordinate system X ₁ O ₁ Y shifted downward along the Y axis by a distance D (Figure 3).

Having determined the angles α and β, according to the rules of geometry of addition and subtraction of angles, all angles of the triangle ΔOAO ₁ are calculated. The angle φ = 180 ° -α-β (Figure 3), since the sum of the angles in the triangle is 180 degrees. For known angles of the triangle and a fixed distance D (set when installing the geophones in the ground), the OA distance is determined by the sine theorem:

where the sign for β is determined depending on which half-space relative to the X axis the detected object is located.

This operation is performed by computing device 14, which calculates the current polar coordinates of the detected object (OA, β). The set of current coordinates in time determines the trajectory and average speed of the object:

where Δr ₁ , Δr ₂ , ..., Δr _n are the distance segments traveled by the object;

Δt ₁ , Δt ₂ , ..., Δt _n - time intervals corresponding to the distance segments traveled by the object.

The proposed seismic device for determining the coordinates of objects allows you to increase the information content of seismic detection tools by eliminating the imaginary imaginary azimuth, as well as the ability to determine coordinates with a 360-degree field of view, speed and trajectory of the object, counting the number of objects and their separate classification.

Information sources

1. Radio-electronic systems: the basics of construction and theory. Reference book / Shirman Y.D. Losev Yu.I., Minervin N.N., et al. / Ed. Y.D. Shirman - M .: ZAO MAKVIS, 1998. - 828 p.

2. RU No. 2204849, Moscow, VNIIGPE, 2003. - Bull. No.14 of 05.20.2003 - 16 s. Kryukov I.N., Ivanov V.A., Dyugovanets A.P. Seismic correlation direction finder of objects.

3. Gurvich I.I. Bogannik G.N. Seismic Intelligence: A Textbook for High Schools. - 3rd ed., Revised. - M .: Nedra, 1980 .-- 551 p.

Claims (1)

A seismic device for determining the coordinates of an object, consisting of a correlation processing unit, including a first channel for processing seismic signals with a delay line, a second processing channel with a set of delay lines with different delay times and correlators in the number of delay lines, a signal from the output of the line is received at the first input of each correlator the delay of the first channel for processing the seismic signal, the second input of each correlator receives a signal from the output of the delay line with a certain delay time, input the correlation processing unit is connected to the outputs of the geophones, the outputs of the correlators are connected to the inputs of the resolver, the maximum signal selector, which is connected to the outputs of the correlators multipliers, the classifier, the input of which is connected to the output of the maximum signal selector, the output of the resolver is connected to the control input of the maximum signal selector, different the fact that additionally introduced a second solving device, a computing device and a second block of correlation processing, the first channel for processing seismic signals with a delay line, the second channel for processing with a set of delay lines with different delay times and correlators by the number of delay lines, the inputs of the correlation processing unit are connected to two other seismic receivers, the signal from the output of the delay line of the first channel processing the seismic signal, the second input of each correlator receives a signal from the output of the delay line with a certain delay time, the outputs of the correlators are connected inen with inputs of the maximum signal selector, the second solving device, the output of the second solving device is connected to the control input of the maximum signal selector, the output of each of the solving devices is connected to the input of the computing device.

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