RU2265866C1 - Method for increasing radiolocation resolution, system for realization of method and method for remote detection of small objects by system - Google Patents

Abstract

FIELD: technology for scanning minefields.

SUBSTANCE: method includes receiving reflected signals during appropriate analysis of surface, these signals are received using coherent radiolocation probing of portions of surface in observation sectors, determined by width of antenna direction diagram (10-50°) under observation angles within range ±75°, received signals are memorized in form of appropriate radio-images, after that for each observation angle radio-images are formed, appropriate for a set of signals of radio-images, received along sections, parallel to direction of appropriate analysis angle, in projections on a plane, perpendicular to these directions, and then Fourier transformation of formed projections of radio-images is performed, on basis of total of which for each portion by means of reconstructive computing tomography method, like Radon transformation, appropriate total quasi-hologram is formed with following restoration on its basis of two-dimensional reversed Fourier transformation of radio-image of appropriate portions with increased resolution. System for remote detection of small objects has radiolocation sensor, connected to computing device, by its output connected to indicator, synchronization block, block for forming radiolocation image, classification device, two memory blocks, coordinates determining block, synchronization block, printing transmitting and receiving devices, and also additional indicator and computing device. Method for remote detection of small objects by system, includes surveillance of substrate surface in zone of assumed location of small objects, for example, subject minefield, performed during aircraft reconnaissance of this field by its scanning with concurrent radiolocation probing, for example, in decimeter radio-wave range by means of onboard radiolocation station or radiolocation detectors of synthesized aperture, mounted onboard the aircraft, and also by means of step by step discontinuous rotation of antenna beam for given angles in each pre-selected elementary analysis range and determining coordinates of reflection spots of appropriate signals during each step of rotation of radiolocation station antenna beam in these analysis ranges, while reflected signals and coordinates of appropriate sections received during probing of substrate surface are memorized, and ten signals of radio-imaging of sections are formed, appropriate for these reflected signals, and coordinates of surveyed field appropriate for them.

EFFECT: possible non-contact search with high probability of detection and recognition of small objects, like mines, including those buried in soil and appropriately concealed.

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Description

The present invention relates to techniques for examining, for example, minefields and, accordingly, can be used for search, detection and recognition of mines, including, for example, anti-tank mines and landmines, covered with a layer of soil.

There is a method of obtaining information about the terrain, based on frame-by-frame shooting of the underlying surface using a camera mounted on an aircraft (LA) [1].

This method provides the ability to obtain information about the underlying surface, but does not solve the problem of identifying small objects, for example min.

The closest analogue to the prototype is a method of obtaining information about objects on the ground, based on aerial photographing of the underlying surface using a photo and television equipment installed on the carrier and subsequent processing of the obtained data [2].

The known method makes it possible to obtain high-resolution information about the underlying surface, however, when using it, it is not possible to identify buried objects.

A device for synthesizing a radar image containing a driver of the reference function in the form of read-only memory (ROM), a complex multiplier, two blocks of fast Fourier transform, an amplitude detector, as well as a driver of a two-dimensional matrix signal and a drive [3].

In the known device, the computing environment is invariant, invariant to the trajectory and motion parameters, and the possibility of incoherent synthesis of the radar image of the probed region is provided. However, this device does not provide the ability to conduct searches, as well as the detection and recognition of small objects.

The closest analogue prototype is a subsurface sounding system based on the principle of multi-frequency sounding of conservative media (building structures, soils, etc.) and containing a radar sensor connected to a computing device connected to an indication device [4].

This system provides the possibility of scanning and, respectively, sensing the surface and allows the detection and identification of plastic and metal anti-tank and anti-personnel mines buried in the ground at (1-10) cm, however, the possibility of using it to remotely search for small-sized objects has not yet been constructively developed.

A known method for the remote detection of small objects, for example, mines using robotic systems that use the effect of nuclear magnetic resonance in the examination of mine fields with subsequent processing of the obtained spectra [5].

This method provides the ability to obtain the information required for the detection and recognition of mines with a probability close enough to a similar characteristic of a contact mine detector, however, it does not solve the problem of online processing of such information in large volumes, and, moreover, is not intended for remote search of small objects, for example, the same minutes

The closest analogue prototype is a method for remote detection of small objects, for example, mines, from air carriers, for example helicopters, based on obtaining, using appropriate sensors, aerial photographs of the studied areas of the underlying surface, including in the infrared or radio range, and subsequent processing and decryption obtained data [6].

The known method provides the ability to obtain the required information about small objects and its operational analysis, however, its use does not provide the ability to detect, for example, mines buried in the ground.

The objective of the invention is to develop a method that provides the ability to increase resolution when radar sensing the underlying surface, a system for implementing the method, as well as a method for remote detection, for example from the aircraft, by searching, detecting and recognizing this system installed both on the underlying surface and buried small objects, for example, different types of min.

The essence of the invention lies in the fact that in a method of increasing radar resolution, including obtaining reflected signals with an appropriate surface survey, these signals are obtained using coherent radar sensing of surface areas in the observation sectors determined by the antenna radiation pattern width (10-50) ° under viewing angles in ± 75 ° range, the received signals are stored in the form of corresponding radio images, after which, for each view of the survey, radioiso the lesions corresponding to the totality of the radio image signals obtained over sections parallel to the direction of the corresponding survey angle, in projections onto a plane perpendicular to these directions, and then the Fourier transform of the generated projections of the radio images is performed, the totality of which for each plot using the method of reconstructive computational tomography, for example Radon transformations, form the corresponding total quasi-hologram with subsequent recovery from it using A two-dimensional inverse Fourier transform of the radio image of the corresponding sections with increased resolution.

The essence of the invention lies in the fact that in the system for the remote detection of small objects, including a radar sensor connected to a computing device connected to the indicator by its output, a matching unit, a radar image forming unit, a classifier, two memory units, a coordinate determination unit, a synchronization unit are introduced printing and radio transmitting and receiving devices, as well as an additional indicator and a computing device, the radar sensor being the first output ohm is connected to the first input of the matching unit, its output connected to the first input of the radar image forming unit, connected to the first input of the first memory unit, the output connected to the first input of the radio transmitting device, the second (control) input connected to the first output of the computing device, the second output of the connected with the second (control) input of the first memory block, the third output connected to the control input of the radar sensor, and the fourth output is connected to the input of the synchronization unit, with its first and second outputs connected to the second (synchronizing) inputs of the matching unit and the radar image forming unit, and a group of outputs connected to the group of corresponding inputs of the radar sensor, the second output connected to the third input of the matching unit, while the computational the device input-output is connected to the input-output of the first memory unit, and the fifth and sixth outputs are connected respectively to the first inputs of the indicator and the coordinate determination unit, with its first and second outputs respectively connected to the first input of the computing device and the second input of the indicator, and the radio input associated with the radio input of the system, and the transmitting device with its radio output is connected to the radio input of the radio receiving device, the output connected to the first input of the second memory unit, its output connected to the first input of the classifier, the output connected to the first input of an additional computing device, with its first, second the second and third outputs connected respectively to the second inputs of the radio receiver, the second memory block and the classifier, the fourth and fifth outputs connected to the first inputs of the second indicator and the printing device, respectively, and the input-output connected to the input-output of the second memory block, while the inputs of the computing and additional computing devices are connected respectively to the first and second inputs of the system, the output of the printing device is connected to the output of the system, optical outputs are indie the cores are connected to the corresponding optical outputs of the system, and the group of radio inputs and outputs of the radar sensor is connected to the corresponding group of inputs and outputs of the system.

Moreover, the radar sensor contains two phased antenna arrays, each of which consists of M independently connected transceiver modules, where, for example, M = 1, ..., 12, an adder, two switches, a generator, a modulator and a unit for generating a given distribution amplitudes and phases of the signals to control the position of the antenna beam for each of the transceiver modules, the transceiver modules being connected by the first electrical inputs to the corresponding outputs of the first switch, the first input connected to the first the output of the generator, the first (control) input connected to the input of the radar sensor, and the second input connected to the output of the modulator, the input connected to the first input of the group of inputs of the radar sensor, while the second input of the group of inputs of the radar sensor is connected to the input of the unit for the formation of a given distribution of amplitudes and phases of the signals to control the position of the antenna beam for each of the transceiver modules of the arrays, its first and second outputs connected respectively to the second the first switch and the first input of the second switch, its second input connected to the third input of the group of inputs of the radar sensor, and the corresponding N = 2M outputs connected to the second electrical inputs of the respective transceiver modules, and the electrical outputs of the transceiver modules are connected to the corresponding inputs of the adder output connected to the first (electrical) output of the radar sensor, the second output of the generator is connected to the second output of the radar sensor ka, the radio inputs and outputs of which are associated with the corresponding radio inputs and outputs of the transceiver modules.

The essence of the invention lies in the fact that in the method for remote detection by the system of small objects, including their search, detection and recognition and based on inspection from the aircraft (LA) of the underlying surface by means of its radar sensing and processing of the received reflected signals, examination of the underlying surface in the area the alleged location of small objects, for example, in the proposed minefield, is produced when flying around the aircraft of this field by scanning it at the same time radar sensing, for example, in the decimeter range of radio waves using the synthesized aperture formed on the aircraft radar station or installed onboard the aircraft radar sensors (RLD), as well as by incremental discrete rotation of the antenna beam at predetermined angles in each preselected elementary interval survey and determining the coordinates of the places of reflection of the corresponding signals at each step of the rotation of the beam of the radar antenna in these inspection intervals, and the reflected signals and coordinates of the corresponding sections of the underlying surface are memorized and then formed, corresponding to these reflected signals, the radio image signals of the sections and the corresponding coordinates of the examined field, after which, for example, by the magnitude of the intensity of the reflected signals and the density of their location on these sections of signals of the corresponding intensity First, the presence of small objects and the coordinates of their locations are determined, and then reflected by the corresponding the signals produce the formation of signs characterizing the objects located in these places and compare these signs with the corresponding standards, and the examination is carried out in a “binding”, for example, to the characteristic points of the underlying surface and / or to special beacons, for example, to radio beacons and / or optical reflectors that are installed in the area of the alleged location of small objects.

In this case, the sounding of the underlying surface is carried out in the range of, for example, decimeter waves, and the probing signals are formed in the form of a time-repeated limited sequence of coherent pulses at different carrier frequencies.

In addition, the synthesis of the aperture of the antenna is carried out during the time duration of the pulses having the same carrier frequencies at each elementary inspection interval.

In this case, the elementary inspection interval is chosen equal to (0.5-2.0) seconds, and the reflected signals are stored in the form of an array of data, which is, for example, an n-dimensional (where, for example, n = 4) representation of the values of these reflected signals, as well as signals corresponding to the coordinates of the places of reflection, and the scan angles of the corresponding places of reflection in the studied areas of the underlying surface.

At the same time, the values of the signal intensity when detecting small and buried small objects located on this surface are obtained by summing the values of the signals received at each flight of the aircraft, but reflected from the same points on the surface, followed by comparing these total signals with a given threshold signal and appropriate selection with reference to the coordinates on this surface of the resulting signals and their aggregates, and the signs used for recognition using, for example, transformation I receive Radon in the form of quasi-holograms of the radio image of the corresponding small-sized object with appropriate processing of the stored sets of signals reflected from the corresponding locations of these objects.

Moreover, the selection of features, their comparison with the relevant standards and the subsequent classification of objects is carried out using algorithms that work on the principles of processing using neural networks, for example, according to the Kohonen algorithm.

In addition, the alleged minefield is surveyed by flying around it with a scan and with appropriate probing of each area of the investigated underlying surface in three or more angles, and after finding the locations of small objects around these places, they fly around with the appropriate scanning and sensing of these areas of the underlying surface.

In this case, the step size of the discrete rotation of the radar beam of the radar antenna is selected by the corresponding width of this beam in the horizontal plane, and the predetermined rotation angle is selected by the corresponding angle of coverage of the sector by the beam deflection sector of the radar antenna of the aircraft.

In addition, beacons and / or optical reflectors are installed by, for example, dropping them from the aircraft during its flight, and these beacons are installed at the borders of the minefield, for example, along its perimeter, and the distance between the beacons installed on the perimeter is chosen corresponding to the inspection bandwidth at one-time flight of LA.

In addition, lighthouses are installed around the perimeter of the minefield and in areas of the underlying surface where small objects are found.

In addition, in areas of the underlying surface on which small objects are detected, optical marking devices are installed.

In addition, when examining a minefield, it is circled along a route from each established, for example, along the perimeter of a given lighthouse field to every other lighthouse, and the coordinates of these lighthouses are determined in advance, for example, in the earth's coordinate system, while the initial (initial) the points select the location of, for example, a beacon installed on the perimeter, and these beacons are installed at a distance corresponding, for example, (0.3-0.9) to the viewing width when flying.

In this case, the signals of radio beacons installed at the boundaries of the minefield and on the areas of the underlying surface where small objects are detected are selected with emitted signals differing in frequency.

The proposed method for increasing the resolution of radar sensing, the system for its implementation, and the method for remote detection of small objects by the system make it possible to conduct a contactless search for a mine with a high probability of detection and recognition of mines, including those buried in the ground and masked accordingly.

The fact is that when solving the problem of detecting and recognizing small targets, including different types of mines, the determining factor is the ratio of the reflection powers of the radar signal from the object and directly from its environment (signal / background ratio).

In this case, the background power in the resolution element depends on the specific effective scattering surface (EPR) of the background and the linear resolution of the radar sensor (RLD) and is determined by the relation [7]:

P _f = kσ _f δρδD,

where k is the coefficient taking into account the attenuation of the signal during propagation in the medium, σ _f is the specific ESR of the background, δρ and δD are the linear resolution along the transverse and longitudinal coordinates of the area of the area irradiated when the object is detected, and the power of the signal reflected from the object is determined as

P _c = kσ _o ,

where σ _o is the EPR value of a small-sized object.

Features associated with the subsurface location of the object (mines) significantly complicate the structure of signal formation P _c , therefore, the problem of its production is usually solved experimentally. It is known [8] that when a radar is detected on a site 1 m × 1 m in size and uses radar radiation in the decimeter range of radio waves at a frequency of 1 GHz (0.3 m) for the buried metal anti-tank mine of the M-20 type, the ratio R _c / R _f ~ 2 (or 3 dB), and the probability of detecting mines in such conditions is less than 0.1.

The detection probability in this case can be increased by improving the resolution of the RLD due to, for example, the use of a broadband (in the range of operating frequencies) active phased array antenna (AFAR) as a part of the RLD.

Focusing on the magnitude of the operating frequency band (Δf) of the AFAR of the order of (250-300) MHz, in accordance with the dependence [9]:

τ _u = 1 / Δf,

where τ _u is the equivalent duration of the compressed pulse, we obtain the value of the equivalent duration of the compressed pulse τ _u = (3.3-4) ns.

Then, according to the relation δρ _r = сτ _u / 2, where c = 3 × 10 ⁸ m / s is the propagation velocity of radio waves, the radial range resolution is δρ _r = (0.5 ... 0.6) m.

In this case, the horizontal resolution (underlying surface) will be:

δD = ρ _r / cosθ _y ,

where θ _y is the angle between the direction of observation and the underlying surface (angle of observation). Given this feature, at the near boundary of the radar observation section, we have θ _y ~ 60 ° and, accordingly, we obtain δD = (1.0-1.2) m.

The potential resolution of the RLD with a side view of the underlying surface along the path line (δρ _x ) is described by the relation

δρ _x = λr _o / 2Lsinθ _x , (1)

where λ is the length of the radio wave of the RLD sounding signals, r _o is the slant range to the middle of the section, L is the length of the path of the RLD antenna, θ _x is the observation angle relative to the aircraft ground speed vector.

Substituting into the formula (1) the value of the carrier frequency of the probing RLD signals from a certain portion of the decimeter range (0.5-1.5) GHz, for example, its average value equal to 1 GHz, and also taking the angle θ _x = 90 °, the value of r _o = 85 m and the path length L = 25 m during the flight of the aircraft for ~ 1 s, we obtain the radial resolution δρ _x ~ 0.5 m.

However, in reality, when used to compensate for the influence of various factors, such as, for example, the formation of false marks due to the high level of the side lobes of coherent signal processing of approximately -13 dB with respect to the main maximum, and to increase the stability of the information processing, the use of weight smoothing functions, there is a deterioration in resolution [11]. So, taking into account such processing, the real value of resolution in the transverse direction (in cross-range) at θ _x = 90 ° can be expected to be δρ _x = (0.7-1) m, and taking into account the fact that the “frames” of observation are accepted and at θ _x = 30 °, the value of δρ _x in these frames will double. However, for them the range resolution will be almost 2 times better than for the “frames” of observation at θ _x = 90 °. On average, for all “frames” of coherent processing at a selected elementary inspection interval of ~ 1 s, we can take δρ _x = ~ 1 m and δD = ~ 1 m.

A further improvement in the resolution of SAR is possible by introducing incoherent processing of separately formed “frames” of observation during coherent processing. Obtaining these results is based on the use of reconstructive computational tomography methods, in particular, on the basis of the application of the Radon transform [12].

An assessment of the achievable resolution using such methods can be obtained, for example, by constructing a two-dimensional portrait in a Cartesian coordinate system from a set of projections — one-dimensional portraits synthesized at small angular intervals, shifted by angle relative to each other, where the corresponding values of the potential resolution for the central points the synthesized two-dimensional portrait obtained in the form of the following dependencies [13]:

Here β _о is the angular interval of observation, equivalent to the total angle of projections - one-dimensional portraits synthesized at small angular intervals, shifted in angle relative to each other.

Hence, for β _o = π we have

и

and

The presented estimates are obtained on the basis of the formation of the uncertainty function (FN), which corresponds to coherent signal processing [9]. In this method of synthesizing at small angular intervals, a two-dimensional portrait according to its one-dimensional projections is carried out without taking into account the nonlinear dependence of the phase on the angle, which in fact degrades the resolution characteristics that are relatively achievable.

The spatial selection along the segment ρ = (ρ _x , ρ _y ) in the polar coordinate system is estimated based on the determination of the width of the FN modulus at the level of 0.7 (-3 dB) [10]. In this case, for a circular survey with an angular size of PCA β _о = 2π, the potential resolution in all spatial coordinates is δρ = 0.18λ, which at a hypothetically accepted wavelength λ = 0.3 m gives δρ = 0.05 m.

When forming a quasi-hologram, the formal possibility for each radio image of a site of the area is taken into account, using the subsequent Fourier transform procedure, to get the original radio hologram again. In this case, such a procedure is carried out for each projection corresponding to the Radon transform of the radio image of the selected area, and for all the received projections of this area, a set of individual radio holograms is formed, each of which is characterized by the display of the area under different observation angles. The combination of such radio holograms with the provision of their necessary phasing gives a combined radio hologram of the total interval of observation angles of the selected area. However, the implementation of such a procedure is fraught with difficulties in realizing the necessary phasing and taking into account the nonlinearity of the formation of the integrated radio hologram, which becomes circular at large viewing angles. In this regard, the actually obtained representation of such a radio hologram is called a quasi-hologram.

In the absence of coherence during the “stitching” of individual “frames” of coherent processing at elementary intervals of the survey, there is an expansion of the FN and, as a result, a significant deterioration in resolution. However, this circumstance can be compensated, for example, by the mode of conducting a telescopic survey of a site of terrain proposed in this technical solution, in which the resolution decreases only by 2–3 times and reaches a value of δρ ~ 0.15 m, respectively. The value of resolution in all spatial coordinates is δρ ~ 0.25 m should be expected with a 3-fold review of the terrain with a change in the course angle of the rectilinear trajectories of the helicopter above the probed terrain, and with a single survey tnosti and non-coherent processing of information, such as the seven frames coherent processing review, resolution of all spatial coordinates will be δρ ~ 0.5 m.

Providing a resolution of δρ ~ 0.5 m in all coordinates compared with a resolution of δρ ~ 1 m gives an additional increase in the signal-to-background ratio by 4 times (by 6 dB) and its total value is 9 dB. In this case, in accordance with the data cited in the literature close to this topic [10], the probability of detecting an anti-tank mine will be 0.25. Using the following resolution level δρ ~ 0.25 m will ensure the detection of such mines with a probability of at least 0.95. In the case of smaller mines, in particular anti-personnel mines, a resolution of δρ ~ 0.25 m will allow them to be detected with a probability of no less than 0.95. Higher resolution δρ ~ 0.15 m in the telescopic viewing mode will make it possible to record the radio image of the detected mines with the peculiarities of the formation of their “brilliant” during radio exposure (radio sounding). This, in turn, when using this technical solution allows the recognition of mine types using, for example, neurostructures that in this case recognize, in particular, anti-tank mines with a probability of at least 0.95 and anti-personnel mines with a probability of at least 0.9 .

Figure 1 shows a structural diagram of a system for remote detection of small objects, figure 2 shows a structural diagram of a radar sensor, figure 3 shows an example of a conventional marking of the examined field, figure 4 shows a diagram of a scan during an elementary time interval during a flyby, figure 5 shows the scanning scheme for the "telescopic" examination, figure 6 shows an example of exceeding the signals reflected from different parts of the underlying surface, the signals of the threshold level, set equal to 8 dB, f D.7 compares the detection probabilities using known methods and the proposed method based on the reconstruction tomography using the Radon transform.

The system for remote detection of small objects, for the implementation of the method (Fig. 1) contains a radar sensor (RLD) 1, designed to respectively provide radiation of signals, for example, the decimeter range of radio waves, receive reflected signals when sensing the underlying surface and generate appropriate signals for subsequent processing. RLD 1 with the first output connected to the first input of block 2 matching (BS), made in the form (not shown) of a series-connected frequency converter and ADC [11] and its output connected to the first input of block 3 of the formation of radar image (BFRLI), made in the form, for example, of the processor device "Baguette" [14].

The output of the radar image forming unit 3 is connected to the input of the memory unit 4 ₁ , made in the form of random access memory, for example, on a board of the RSL-6646B type [15], with an output connected to the first input of the radio transmitting device 5, designed to transmit received during the flight of the aircraft and the information recorded in block 4 ₁ for subsequent processing to the corresponding ground center (not shown in FIG.) and made in the form of a corresponding device of the UURE series SHC series UC4 Marcad Delivery Receiver [16].

The second (control) input of the radio transmitting device 5 is connected to the first output of the computing device 6 ₁ , designed to control the operation of the associated blocks and devices of the system and to process and transmit signals of these blocks and related devices and made in the form of an industrial computer IPPC-950T by Advantech [15], its second output connected to the second (control) input of the first memory block 4 ₁ , a group of outputs connected to the first group of inputs of the RLD 1, and the third output connected to the input of the block 7 synchronization, made in the form of a clock generator [17].

In addition, the computing device 6 _{1 is} connected with its input-output to the input-output of the first memory block 4 ₁ , and the fourth and fifth outputs are connected respectively to the first inputs of the indicator 8 ₁ and the coordinate determination unit 9, connected with the first and second outputs respectively to the first the input of the computing device 6 ₁ and the second input of the indicator 8 ₁ , and the radio input associated with the radio input of the system.

Indicator 8 _{1 is} designed to create a visual representation, for example, of an aircraft pilot, about a given minefield flight path and the degree of completion of this task and is made in the form of a corresponding device of the GV-D900 type [16].

Block 9 coordinate determination (BOC) is designed to obtain information about the coordinates of the studied sections of the underlying surface and the location of the detected small objects, as well as the coordinate reference of the aircraft and is made in the form of satellite radio navigation complex SRNK-21DM [18].

The synchronization unit 7 is connected with its first and second outputs to the second (synchronizing) inputs of the matching unit 2 and the radar image forming unit 3, and the output group is connected to the group of corresponding inputs of the RLD 1, the second output connected to the third input of the matching unit 2.

The radio transmitting device 5 is connected with its radio output to the radio input of the radio receiving device 10, intended for receiving information from the aircraft for subsequent processing by the respective devices of the system and made in the form of a corresponding device of the UURE type SHC series UC1 radio system from the company [16].

The radio receiver 10 is connected by an output to the first input of the second memory block 4 ₂ , made in the form of random access memory, for example, on a PCL-6646B type board [15] and with its output connected to the first input of the classifier 11, which is designed to implement procedures for detecting small objects and their recognition and made in the form of a neural network microprocessor NM 6403 [19].

An output classifier 11 is connected to the first input of an additional computing device 6 ₂ , designed to process incoming information signals and construct a map of the location and coordinate reference of small objects, for example, mines in the examined area, as well as to ensure the interaction of the corresponding units and devices of the system and in the form of an industrial computer IPPC-950T by Advantech [15].

Computing device 6 ₂ with its first, second and third outputs is connected respectively to the second inputs of the radio receiver 10, the second memory unit 4 ₂ and classifier 11, the fourth and fifth outputs to the first inputs of the additional indicator 8 ₂ and the printing device 12, respectively, and the input is the output is connected to the input-output of the second block 4 ₂ memory.

The additional indicator 82 is made in the form of a corresponding device of the GV-D900 type [16], and the printing device 12 is made in the form of an hp LaserJet 1200 printer.

In this case, the group of radio inputs-outputs of the RLD 1 is connected with the corresponding group of inputs and outputs of the system, the inputs of the computing devices 6 ₁ and 6 _{2 are} connected respectively to the first and second inputs of the system, the optical outputs of the indicators 8 ₁ and 8 ₂ are connected with the corresponding outputs of the system, and the output of the printing device is connected to the output of the system.

The radar sensor 1 (Fig. 2) contains an antenna device (not shown in Fig.), Made in the form of an active phased antenna array (AFAR) [20], consisting of two antenna arrays (not shown in Fig.) Along M independently connected receivers - transmitting modules 13 in each, where M = 1, ..., 12, and is a separately installed antenna array, as well as an adder 14, two switches 15, a generator 16, a modulator 17 and a block 18 for generating a given distribution of signal amplitudes and phases to control the position of the antenna beam for each of mo-transmitting module 13, wherein the transceiver modules 13 of the first electrical input connected to the corresponding first switch outputs Jan. _15, a first input connected to the first output of generator 16 and a second input coupled to a first output 18 forming a predetermined distribution of amplitudes and phases of the signals for controlling the position of each antenna beam transceiver modules 13, the second inputs of which are electrically connected to respective second outputs of the switches 15 ₂ connected to a first input of Mo the direct output of the unit 18 for generating a given distribution of amplitudes and phases of the signals to control the position of the antenna beam of each of the transceiver modules 13, and the second input connected to the first input of the first group of inputs of the radar sensor 1, the first output connected to the output of the adder 14, the corresponding inputs connected to the outputs of the respective transceiver modules 13, and the second output connected to the output of the generator 16, the first input connected to the output of the modulator 17, is connected to its first input go with the third input of the first group of inputs, and the second input connected to the first input of the second group of inputs of the radar sensor 1, while the second and third inputs of the second group of inputs of the radar sensor 1 are connected to the second inputs of the generator 16 and the block 18 for the formation of a given distribution of amplitudes and phases signals for controlling the position of the antenna beam of each of the transceiver modules 13, which are radio inputs-outputs connected to the corresponding radio inputs-outputs of the radar sensor 1.

Transceiver modules 13 are designed to emit microwave signals of the decimeter range and receive the corresponding reflected signals, for example, from the underlying surface when it is probed, and are made in the form, for example, of M-2730 type elements [21]. The adder 14 is made in the form of a microwave distributor [22] and electrical inputs connected to the respective outputs.

The switches 15 are made in the form of corresponding devices [17], and the switch 15 _{1 is} designed to switch modes (transmission or reception) of the operation of the transceiver modules 13 and the corresponding distribution of power of the microwave signals supplied to these modules from the generator 16, made on the basis of a high-frequency transistor , for example, a transistor type 2T634A-2 [20], and the switch 15 _{2 is} designed to transmit to each of the transceiver modules 13 the corresponding parameter values of the corresponding signals from the forming unit 18 distribution of amplitudes and phases of the signals to control the position of the antenna beam.

The modulator 17 is designed to generate parameters of the emitted pulse signal, namely: duration, repetition period and frequency modulation, and is made in the form of a chip of the type AT90S4433 [21], and the block 18 of the formation of the current law of the distribution of amplitudes and phases of the signals to control the position of the antenna beam is made a form of read-only memory (ROM) type 82S191 [17].

A way to increase the resolution of radar sensing is based on developments in the relevant fields of science and technology and can be briefly illustrated by the example of considering the problem of remote from an aircraft, such as a helicopter, detection, including search, detection and recognition, installed both on the underlying surface and in-depth small objects, including various types of mines.

The ability to detect small objects is determined by the ratio of the power of the reflection signals from the object and the background, determined by the size of the underlying surface, the dimensions of which, in turn, are due to the resolution of the radar sensor (RLD) in the longitudinal and transverse directions of its beam. In the case when the object of radar sensing is located below the surface, additional factors of deterioration of the ratio of signal powers from the object to the background are the passage of radio emission through the soil layer to the object and vice versa, as well as the dispersion of the energy of the reflected signal at the interface [7].

A generalized representation of the depth of penetration of radio waves into the soil, depending on the frequency of radiation of the probing signals and soil moisture, is presented in the indicated materials for radio waves of the mm-, cm-, dm- and meter (m) -bands of radio waves [23]. On most of the earth's surface, soil moisture is such that cm-band signals penetrate units of centimeters, and dm-range signals - units of decimeters. The best subsoil penetration is provided by meter-long m-band radio waves, characteristic of the composition of the spectrum of short-pulse radiation in the form of a single oscillation period of the probing signals. However, their use is associated with large energy losses due, in particular, to a significant deterioration in the directional properties of radio waves with a decrease in their carrier frequency.

Acceptable penetration into the soil for the detection and recognition of, for example, anti-tank mines at a depth of up to 0.3 m is provided by dm-band radio waves, and a significant increase in the resolution of radar sensing when using dm-band radio waves is achieved by using the aperture radar synthesizer (PCA) mode of the antenna at discrete viewing mode using electronic beam control of the RLD antenna, and a feature of the organization of the SAR antenna of the RLD is to provide the requirement, consisting in that each dot plot under review in this case was observed within a few seconds.

The obtained information on the intensity of reflection from the underlying surface at 8 positions of the AFAR beam for an elementary inspection interval of ~ 1 s is algorithmically transferred to a horizontal surface corresponding to the display of 7 sections of the underlying surface measuring 60 m × 25 m, occupying a total of ± 60 ° lateral sector overview of the terrain when moving during this time, the real RLD antenna along the helicopter path. This information obtained (see Fig. 3) from the right and left sides of the helicopter along its path at each elementary inspection interval is recorded in the RAM of the processor device “Baget” of the RLD.

The stored information about the reflection intensity at 7 sections of the underlying surface on each side of the helicopter along its straight path during 7 elementary inspection intervals allows, as shown in Fig. 4, to compile a matrix (7 × 7) of data of coherent processing of reflection signals at each of these intervals . The main diagonal of such a matrix corresponds to information, in particular, for the VII section of Fig. 4, under 7 different angles of observation along the path of a direct flight of a helicopter.

A similar accumulation of coherent processing data at successive elementary inspection intervals takes place when organizing the telescopic survey mode shown in FIG. In the case where at the turn the helicopter speed is the same as in the case of a straight flight of Fig. 4, during circular flight of one section with a diameter of ~ 25 m, there is an accumulation of coherent information from 15 different angles of its radar observation from the helicopter.

By processing information on 7-15 sections of the underlying surface for an elementary inspection interval, a synthesized antenna pattern is formed with incoherent processing of information corresponding to a certain sector of its sight from the side of the helicopter. According to the above calculation results, using this technical solution and applying received signals during processing, for example, Radon transforms, the sounding resolution can reach (0.15-0.5) m.

The Radon transform [12] is applied in the case under consideration to the definition of the projection of some unknown function g (x, y) that describes the location in Cartesian coordinates of the object’s points on the ground, and the image of the desired object is formed from measurements of an available limited set of projections. These projections as functions of the observation angle β, taking into account the introduction of the δ-function, are determined by the expression:

where u is the length of the perpendicular dropped from the origin to each of the straight lines intersecting the display region of the function g (x, y).

In addition, it is assumed that one- and two-dimensional Fourier transforms of the functions p (u, β) and g (x, y) can be obtained, denoted respectively by P ₁ (ω, β) and G ₁ (ωcosβ, ωsinβ).

Then, in accordance with the theorem, which states that by enumerating all possible values of the angle β, we can obtain all possible values of the central section of the function G ₁ (ωcosβ, ωsinβ), which is equivalent to its full definition [27], we have:

and, if we then perform the inverse Fourier transform for this function, then the desired function g (x, y) will be determined (restored).

A more detailed analysis of the formation of relation (4) allows us to draw an analogy for the formation of the resulting hologram for individual holograms of objects with scattering functions that coincide in a certain region. However, in contrast to a rigorous solution to this problem [28], in this case, the concept of a quasi-hologram should be used.

A perceived analogy to the formation of the resulting hologram is that on a limited segment of each isodal of the radar image along it there is a restored partial image of the object, which, in accordance with expression (3), is its projection under the angle β. The displacement parameter u relative to the origin of the coordinate system of parallel lines intersecting the geometric object g (x, y) characterizes the location of the total scattering intensities at the points of the narrow strip of each radar isodal.

Performing a one-dimensional Fourier transform of such a projection of an object returns it to the complex domain of representing it as quasi-holograms for recording the field scattered by the object. The subsequent combination of all such quasi-holograms based on expression (4) characterizes the formation of the resulting quasi-hologram. If now, under this condition, the inverse two-dimensional Fourier transform of the resulting quasi-hologram is performed, then the geometric image of the object g (x, y) is restored from the totality of its projections of the form p (u, β) from different angles.

Such an interpretation of relation (4) allows the conditional use of estimates of potential resolving power in the area of radar sensing, calculated using formulas of type (2), which are valid for coherent processing of radar information. However, this determines a convenient computing scheme for processing incoherent radar information. In this case, such a scheme is provided by using the convolution and reverse projection algorithm. The starting point of such an algorithm is the inverse Fourier transform of equality (4), which corresponds to the following calculation formula

where the weight function of the influence of the “range” of the projections p (u, β)

The image reconstruction algorithm g (x, y) is implemented on the basis of formula (5) in the form of the following step-by-step procedure [29]:

Step 1: convolution or filtering. For each projection p (u, β), a convolution with the function (core) h _c (u) is performed, forming filtered projections:

When determining the values of the core h _c (u) in its calculation formula (6), the integrand is multiplied by the window function W (ω).

к исходной функции g₁(x,y) в каждой точке осуществляют суммированием значений вдоль каждой проходящей через эту точку прямой u¹=xcosβ+ysinβ:Step 2: Reverse Projection Zoom Restore

to the original function g ₁ (x, y) at each point, carry out the summation of values along each line passing through this point u ¹ = xcosβ + ysinβ:

Thus, the considered RWT algorithm realizes obtaining filtered values of the projections of the object for each observation angle, and then integrating the results of the observations over the variable. The combination of dependences (7) and (8) forms expression (5) and formally leads to the exact solution when for all ω the value W (ω) = 1. However, in this case the integral (6) diverges and the concept of an exact solution loses its meaning. Therefore, the window function W (ω) is chosen so as to limit the contribution to the solution of frequencies above a certain cutoff frequency ω _s .

к исходной функции g₁(x,y) [30].Ideally, the Fourier transform of the function h _c (u) taking into account the window function, i.e. | ω | W (ω) should have an approximately linear response up to a certain boundary frequency, after which it should fall to zero at ω = ω _s . This requirement is satisfied by atomic functions, which in this case provide a better approximation.

to the original function g ₁ (x, y) [30].

To illustrate the presented relations, an example explaining them in a simplified formulation is considered. Suppose that a number of local radar inhomogeneities (LHs) of the observed area are clearly detected by radio holographic processing of information at elementary intervals of the survey. Another part of the LV, including small-sized objects, including mines, can be detected by increasing the resolution of the RLD in the process of further processing of radar information based on the use of relations (7) and (8).

The task is to construct a two-dimensional portrait in a Cartesian coordinate system from the totality of projections - one-dimensional portraits synthesized at small angular intervals, shifted in angle from one another [13]. It is assumed that the analyzed radar images, both detected at the first stage of processing and undetected, are located in the vicinity of the origin of the coordinates of the viewing zone at the current inspection interval. Relative to the point at the origin of this zone, the movement of the helicopter from the RLD along an arc of a circle of radius R _{o is considered} .

In reality, there is a more complicated displacement of the RLD relative to the origin, however, to simplify the task, we assume that the change in the angle of the observation site on the elementary inspection interval is small and then R _o ≈const. Additionally, it is also accepted that the points of intense radio reflection of the object (“shiny” points of the LN), hereinafter referred to as BT, are located in the plane of the RLD movement along the radius R _o .

The amplitude-phase characteristic of the reflected signal model y (β) has a peak structure, which determines the possibility of identifying and tracking peaks due to the same BT of neighboring portraits. Joint processing of Doppler frequencies ω _j (β _l ) of peaks (l is the number of the portrait of the object with the middle of the observation interval β _l ), identified in neighboring portraits, allows one to obtain the radar image of the object in the form of an estimate of the Cartesian components of the radius vectors of its BT: ρ _j = ( ρ _jx , ρ _jy ). It is also assumed that in the measuring device, along with the useful signal y (β), there is an additive normally distributed noise with a zero mean and a dispersion of σ _W ² .

Within the framework of the adopted model, the signal y (β) is a superposition of harmonic signals with unknown amplitudes, frequencies, and phases. Using the maximum likelihood method allows you to determine these unknown parameters, provided that the peaks of the harmonic signal are resolved. The resulting estimate of ω _j (β _l ) by the maximum likelihood method in asymptotics obeys the normal law with an average equal to the true value of the Doppler frequency of the BT at a given β _l : Мω _j (β) = (p _jx cosβ _l -ρ _jy sinβ _l ) and dispersion D (ω _j (β _l )), which is equal to the potential accuracy of measuring the harmonic signal frequency 6 dβ / qΔβ ³ , where q = а ² / σ _ш ² is the signal-to-noise ratio for a given BT and dβ is the angular step of measuring the observation of the radar of the object.

The structured formulas presented in [13] correspond to expression (8) in structure. In this case, due to the linear dependence on the frequency ω (β), when measuring its average value, we have the average value of the coordinate estimates ρ _jx , ρ _jy and they coincide with their true values. The latter determine the position on the BT plane of the two-dimensional portrait of the restored object. The quality of constructing a two-dimensional portrait of an object can be characterized by a fluctuation error in measuring the coordinates of the radius vectors ρ _jx and ρ _{jy of} its BT and their potential resolution.

In the presented research materials, with some restrictions on the location of BT reflections of the surveyed limited area, the above (2) potentially achievable estimates of the resolution of the tomography method under consideration are obtained. The obtained potentially achievable resolution of the considered signal model when using the synthesized aperture method needs to be adjusted, due to the presence of noise measurements of Doppler frequencies ω in the formation of coordinate estimates.

The operation of the remote detection system for small-sized objects to implement a method for increasing radar resolution will be examined using the specific conditions of its implementation as an example of the remote detection of small-sized objects using RLDs such as a helicopter coherent-pulse radar complex [25].

Before conducting radar sensing of a selected area (presumably not more than (5-10) km ² ), on which the presence of mines is assumed, the generated radar image (RLI) of the underlying surface is linked to real landmarks (frames) that frame this field. There should be at least 3 such landmarks (see FIG. 3), if they are lacking, they can be created artificially, while such landmarks can be radio beacons, radios or retroreflectors, or, finally, for example, numbered cubes or shields with distinguishable from the aircraft numbers. Relative to these landmarks, at the end of the work, they present a radar map of the location of the desired small-sized objects on the underlying surface, including their subsurface location.

On one of the landmarks of the selected area of the terrain, a satellite radio navigation complex (SRNK) of the SRNK-21DV type is installed (see Fig. 3) to ensure the determination of the relative coordinates between it and the aircraft, for example, a helicopter conducting radar sounding of the field and having a similar radio navigation complex (block 9 coordinates). Other landmarks framing the field are tied to a landmark with a satellite radio navigation complex, for example, with geodetic means using theodolites and portable rods. In this case, the guidelines are set around the perimeter of the field being examined, at a distance from each other equal to (0.3-0.9) the width of the sensing strip during the passage. Radio beacons are installed on selected landmarks with a geodetic reference so that when controlling the helicopter by their radiation, organize flights over the minefield with its uniform multiple coverage of the radar observation sections from the angles, providing sufficient information to complete the above procedures. At the same time, it is assumed that georeferencing is performed in an operatively formed earth coordinate system (GMS) with respect to the location of the landmark with the radio navigation complex and the coordinate measurement along the {X, Y, Z} axes of the GCC is 1 m, that is, the resolution characteristic of the points is actually set in a windproof complex corresponding to the detection of small objects, including mines, taking into account the uncertainty of their position at the resolution sites of the underlying surface with a size of 1 m × 1 m.

In addition, immediately before conducting work on probing the minefield, they write off the systematic error of determining the mutual coordinates of the helicopter and the landmark with the SRNK. This procedure is performed by “hovering” the helicopter over a landmark with SRNK and visually fixing it from the helicopter using, for example, a video camera (not shown in FIG.) With a viewing angle of up to 20 ° relative to the vertical axis of the helicopter and with a resolution that provides fixation with one pixel sites measuring 1.5 × 1.5 cm ² on the underlying surface from a height of ~ 60 m, for example, a TRV830E type camera placed on a gyro platform (not shown in Fig.) near the center of mass of the helicopter. When using 2-3 pixels to distinguish a landmark with a size on the underlying surface, such a camera with an accuracy of several cm allows you to determine the position of the landmark relative to the projection of the center of mass of the helicopter on the ground. Such an adjustment of the mutual coordinates of two objects with SRNK with the elimination of a systematic error actually allows us to regularly determine the position of the projection point of the center of mass of the helicopter on the underlying surface relative to the landmark with SRNK located on it for a long period of time sufficient to conduct mine sensing fields.

To determine the coordinates of the detected RLD of small-sized objects, it is necessary to measure with an accuracy of about 1 m the flight height of the helicopter above the probed underlying surface. In the case under consideration, these measurements are carried out by radio engineering in the framework of standard equipment and the algorithm for ensuring the operation of the RLD.

The organization of the processing of radar information on the observation of terrain from the side in an operatively formed ZSC makes it possible to filter on-board measurement errors and fundamentally obtain the binding of the observed objects to their location on the ground with an accuracy of about 1 dm. This new quality provides an increase in the resolution of sounding of sites on the ground when observing them from different angles. In turn, this provides an increase in the signal / background ratio for small-sized objects, which gives a more reliable detection and recognition.

As an example, we consider the process of obtaining a radar image (RLI) of a minefield section from the side of a helicopter, performing a side view in relation to the direction of its flight using the on-board radar sensor 1 (RLD 1) when flying a helicopter with a constant speed of ~ 90 km / h at altitude (50-60) m. Antenna (position of the transceiver modules 13) RLD 1 of the helicopter is inclined to the underlying surface, providing in a vertical plane at an angle of radar sensing (20-60) ° overview of the terrain from 30 m about 90 m relative to the projection onto the underlying surface of the flight path of the helicopter (figure 3).

The deflection sector of the RLD 1 antenna beam in the horizontal plane is about ± 60 °, which determines the coverage by this sector of the length of the section of the surveyed terrain band of ~ 175 m along the helicopter path line. This length corresponds to a segment of the helicopter’s path, during which for ~ 7 s each point of a portion of the surveyed band is located in the beam deflection sector of the RLD 1 antenna.

Using the task of coherent radiation of the RLD 1, a synthesized aperture mode of the antenna is organized, which makes it possible to obtain, with a high resolution, the radar image of the sensed area terrain during the observation time of ~ 1 s. The time of observation of a site using RLD for ~ 1 s was selected based on the practice of SAR formation using coherent signal processing [11]. The entire sector of the 1 ± 60 ° RLD field of view is divided into 8 partial sectors with a width of 15 ° under the assumption that it is possible to simultaneously receive information in all 8 sectors for 1.024 s. This can be achieved when the AFAR RLD 1 beam, being in the same sector for 1 ms for the formation of 128 isodals in distance (in the radial direction from the radar) with a 0.5 m increment, is sequentially moved at the same time intervals to other sectors and after 7 ms, they are again returned to their original position. As a result of this, with the corresponding receipt of reflected signals, they have data for the formation of 8 radio holograms in the form of 128 × 128 square matrices for determining the reflection intensity of 8x2 ¹⁴ points of the underlying surface. According to the general approach to reconstructing radar data from a radio hologram [26], they are processed using the two-dimensional fast Fourier transform (FFT) procedure. The obtained values of the detection intensity in the polar coordinate system approximate 10,500 nodes of the Earth’s Cartesian coordinate system, separated by 1 m × 1 m cells, the area of the surveyed area is 175 m × 60 m in size.

At the next ~ 1 with a time interval, the considered procedure for obtaining information for the formation of 8 radio holograms is repeated on a new segment of the helicopter flight path, corresponding to a certain averaged observation angle. This view of the observation of the selected area for each i-th segment of the helicopter flight path is hereinafter referred to as β _i (i = 1, 2, ..., 7). In parallel with receiving RLD 1 data for the i-th observation angle using block 3, information is processed for the (i-1) th angle value.

The minefield section in the field of view of the RLD antenna with a width of 60 m and a length of 175 m along the helicopter path, which it overcomes in ~ 7 s, is divided into 7 adjacent parts of strips 60 m × 25 m in size, corresponding to ~ 1 with the formation cycle frame "image of the area in the coherent processing of information. Figure 4 illustrates the nature of the intersection of these strips with a fan-shaped arrangement of RLD 1 rays of a helicopter, in particular, on a segment of its trajectory from time t ₇ to time t ₁₄ , counted from the beginning of the data accumulation time for incoherent information processing.

When the helicopter moves, each ~ 1 s the data is received corresponding to those reflected from the areas of the underlying surface, the numbers of which relative to the current position of the helicopter are shown in Fig. 4, signals for conducting in the block 3 the formation of the radar image of their coherent processing of 49 "frames". If there is data for such a matrix every 7 s, it becomes possible to organize incoherent processing of information for one of the strips for 7 substantially different ranges of angles of its radar exposure: ± (60 ° -51 °), ± (51 ° -40 °), ± ( 40 ° -22 °) and ± 22 °. Figure 4 illustrates this situation with a matrix of "frames" of size (7 × 7), the main diagonal of which corresponds to a strip of terrain with 7 "frames" for incoherent processing of information.

At subsequent (~ 1 s) time intervals (elementary intervals), the considered procedure for obtaining information for generating 8 radio holograms from each new segment of the helicopter flight path corresponding to a certain average observation angle is repeated. As a result of processing information of 8 channels in ~ 1 s, a synthesized antenna radiation pattern (SDN) is formed corresponding to the sector of the angle ± 60 ° of the side view of the terrain when moving the real RLD 1 antenna along the helicopter path.

In addition, the length of each control section is chosen taking into account the possibility of covering such a section with the deflection sector of the radar antenna of the aircraft, the step of the discrete rotation step of the radar beam of the radar antenna is selected according to the horizontal width of this beam, and the specified angle of rotation of the beam is chosen corresponding to the angle of coverage of the section by the deflection sector radar antenna radar.

In this case, as signs defining either areas with the possible location of small objects, or the location of objects on them, or objects located in these places, choose the characteristics of the intensity and / or length of the discrete signals of the corresponding radio image.

Carrying out additional incoherent processing of information on 7 “frames” allows several times to increase the linear resolution on the ground. If, due to the smallness of the signal / background ratios obtained in some areas, the processing results may not be sufficient to make a decision on the detection of, in particular, mines, an additional examination of “suspicious” areas is carried out. A natural way to further reduce the linear resolution on the ground is to re-probe these areas with a significant increase in the range of angles of observation, by, for example, circular (also called telescopic) flying around these sites.

The telescopic observation mode with a radar probe beam width θ ₀₅ = 15 ° allows for an inclined range of 85 m to cover a terrain area with a diameter of about 25 m and to ensure its linear resolution in the central part up to half the length of the radio wave of the radar probe 1 signal.

If there is insufficient one-time inspection of the minefield and frequent calls to the telescopic viewing mode, another option is possible for organizing a search with multiple observation of sections of the minefield from different angles. In this version of the mine search organization, the helicopter repeatedly crosses this field without changing course and making turns out of the field to cross it under a different directional direction of flight.

To maintain the helicopter heading during manual piloting, optically noticeable buoys can be previously dropped onto the surface of the minefield, which serve as the pilot's guides during helicopter flight. These buoys when conducting radar sounding of the minefield are also fixed with a video camera (not shown in Fig.), Located, for example, under the bottom of the helicopter cabin. Video shooting allows you to organize the binding of the radar image generated on board the helicopter to landmarks on the terrain, including to the buoys in the minefield, relative to which they subsequently perform the operation related to the clearance.

Three-time flight of a helicopter with a constant course over small-sized terrain objects at heading angles of 0, 120 ° and 240 ° is practically equivalent to a circular fly-by in the entire range of angles of 360 ° of the telescopic view of the selected area. In this case, subject to the above flight parameters, a regular moving 7-second cycle of processing cartographic information covers ~ 1 ha of terrain, which is almost 20 times larger than the observed area in the telescopic viewing mode. However, such a review requires the accumulation of a huge amount of information of individual “frames” of the area with an area of 0.15 ha. With a 3-fold coverage of a minefield with an area of 1 km ^2, such processing will require a memory space for recording radar data of almost 15,000 “frames” of terrain.

Processing is carried out in the command center (KP) computing center (not numbered in FIG. 3), where the corresponding information is automatically transmitted using radio transmitting and receiving devices (respectively, devices 5 and 10).

An additional increase in linear resolution in the mode of telescopic viewing of a terrain is possible by increasing the flight speed of the helicopter so as to cover the entire range of viewing angles of small objects on a regular rolling 7 with a cycle of processing cartographic information. In this case, for an inclined range of 85 m to the center of the observed area at a helicopter flight speed of 90 km / h, the angle range does not exceed 120 °.

When organizing a search, a sequential scan of sections of a given area (the proposed minefield) is performed. The detection and recognition of small objects is carried out in accordance with the algorithm implemented in the computing device 6 ₂ .

Object Discovery

Each "frame" of radar data obtained as a result of sounding and recorded in the memory unit of BP 4 ₁ and then transferred to BP 4 ₂ is a matrix in which the position of the elements corresponds to the positions of elementary sites in the geodetic grid. The dimensions of such sites are determined by the resolution of the system that it possesses at the stage of detection (for example, 1 × 1 m). In a visual image, such a discrete area will correspond to one pixel, the brightness of which is determined by the sum of the radar signals from the earth's surface, re-reflections from subsurface layers and from an object located on or below the surface. It is quite obvious that, depending on the terrain, the slopes of the elementary sites will change, but in most cases these changes are characteristic not of one elementary site, but of a certain group of them. For such a group, the average power level of the received signals P _cf can be calculated. Next, the threshold P _k is set, which provides a given probability of false alarms, which must be kept constant for all subsequent groups of sites. The fact of detecting an object will be considered established if the threshold is exceeded by a signal with a power P _cij in the matrix cell S _ij . In this case, the probability of detecting P _obn depends on the relation K _sf = P _ij / P _cf. When observing the site in one flight above it at a certain heading angle K _sf can be (3-9) dB [8] depending on the wavelength emitted. When K _sf = 9 dB, the probability of detecting an object against the background of reflections from the underlying surface, according to [10], will be P _obn = (0.2-0.3). Repeated observations of this site at the same course angle of flight of the aircraft will increase the likelihood of detection. As a further consideration, we took a section from which the signal barely exceeded the threshold level and had K _sf = 9 dB (section No. 4 of Fig. 6) with a resolution of radar with a synthesized aperture equal to 1 × 1 m

With an increase in the number of repeated flights over section No. 4 using the method of synthesized aperture, P _obn will increase (Fig. 7). The first case corresponds to N flights (1, 2, 3, 4) over section 4, and the second corresponds to the same number of flights at different heading angles M over the same section. With the same initial ratio K _sf = 9 dB for both options, with each subsequent flight over section No. 4, the resolution in the proposed system increases by 2 times in each coordinate, as a result of which the observed area decreases by 4 times (6 dB), by the same increases K _sf . This leads to a rapid increase in the probability of detection to the level of (0.95-0.98) when viewing the same area repeatedly. At the same time, it can be seen from Fig. 7 that when using existing systems with a synthesized aperture, an increase in the number of spans does not lead to an increase in resolution, and an increase in P _obn is explained only by the result of processing the accumulated information.

The object detection algorithm can be represented as follows:

The first pass of groups of sites with a resolution of 1 × 1 m:

Defining a threshold for site groups:

where N = 5

The formation of the threshold matrix K [L, M], the element of which is denoted by K _ij

The second pass of groups of sites with a resolution of 0.5 × 0.5

The third pass of groups of sites with a resolution of 0.5 × 0.5

Thus, after processing the primary information, we obtain the matrix K [L, M], the elements of which K _ij will have values 0; one; 2; 3, which determines the appropriate degree of reliability of detection of an object.

After the detection procedure is carried out with varying degrees of confidence in different areas, the small-sized objects are automatically selected. If, when analyzing the contents of the matrix K [L, M], a compact group of values ≥1 is detected, this will mean the presence of an extended object. In the opposite case, i.e. when disjoint values other than zero are present in the matrix, these places will correspond to the location of small objects. Moreover, the value “1” means the lowest reliability of detection of a small-sized object, and this place on the earth's surface must be checked additionally because there could be a false alarm.

Small Object Selection Algorithm

After the selection of small-sized objects over one of them having high reliability, a flyby is performed in the telescopic observation mode, in which they provide a system resolution of the order of 0.15 m × 0.15 m.

In this mode, super-resolution radios are transmitted to a neural network structure, which, by comparing with the standard it is trained in, should recognize the detected object. A small object can be, for example, a fragment of a shell, a piece of pipe or a mine of a certain type. Classifier 11 at its output should give an answer to the belonging of the detected object to one or another class of small-sized objects.

Object recognition is based on the use of neural network structures (NSS) [34]. The NSS consists of a Kohonen scheme and a multilayer perceptron. At the first stage of the operation of the NSS, the Kohonen scheme works, which is used as a detector, and at the second (recognition), a multilayer perceptron (MP).

Known NSS paradigms (schemes) are based on the artificial neuron (IN) scheme, which in general terms copies the structure of a natural neuron. The basis of the ID is an adder, a multiplier and a threshold circuit (not shown in FIG.). The input signals arriving at the IN through the multipliers are superimposed in a certain way defined by weighting coefficients, and the total signal is fed to a threshold circuit in which a nonlinear activation function is realized. The form of this function can take the form of a sigmoid, a single jump, a quadratic, or other dependence. The output of the ID can be 0 or 1 for the function of a single jump, or intermediate values between 0 and 1 (or -1 and 1) for other functions. As a result, the neuron will be considered excited (positive values or 1 at its output), or inhibited (negative values or 0 at the output). In multilayer HCC schemes, one or more intermediate layers may exist between the input and output layers, connected in a certain way with previous and subsequent layers. At the outputs of the neurons of the last layer, the result of the work of the entire neural network will be formed.

A common property for all types of NSS is that they have two operating modes - training and reproduction. Therefore, if the NSS is a learning structure, then it is not pre-programmed, but learning without programming, the NSS is an adaptive or self-organizing computer.

The operation of the Kohonen scheme is based on the principle of competition and is best suited for identifying heterogeneities that are most often found in the image during the initial processing, which is an important property for using this scheme as a detector for identifying characteristic inhomogeneities. When scanning an image with a sliding window, clusters are formed in this NSS that correspond to the appearance of signals from the “victorious” neurons. These clusters strengthen or weaken as the window moves along the lines. After scanning the entire image in the middle layer of the NSS, clusters of heterogeneities will be formed, most often found in the image. After that, the contents of the clusters are transferred to a multilayer perceptron, which is preliminarily trained to recognize some figures (rectangle, ellipse, square, etc.) of different orientations and their combinations. After processing the entire image, the filtered information is obtained at the MP output, in which there are no images unrelated to the reference images and their combinations.

The Kohonen (SC) scheme used in the created NSS is designed as a two-layer neural network. The input layer is actually a buffer between the input signals and the inner layer of neurons, therefore it is not considered a layer of neurons. Neurons of all layers have interconnections with certain weighting factors, for example, m _ij , W _ij . The coefficients m _{ij are} initially assigned randomly, and then at each step of the calculations

m _ij = m _ij + С (E _i -m _ij ) Y _j , where 0 <С <1,

E _i - normalized values of the input signals,

Y _j is the output value of the J-neuron,

Y _j = fW _jk Σm _ki E _i - (ΣΣm _ji E _i -G),

where G is the threshold value.

In the process of functioning (self-organization) at the output of the Kohonen network, clusters are formed - groups of active neurons that characterize certain categories of input vectors corresponding to one spatial situation.

If the image obtained from the Kohonen network is similar to the corresponding reference image, the output of the perceptron activates information about one of the image classes, for example, either a mine, or a shell fragment, or a piece of pipe, or an unidentified object.

The operation algorithm of block 3 of the formation of the radar image is given in the description of the receipt of radio holograms and the Radon transform.

Input information is received via digital communication lines (not shown in FIG.):

- from BSogl 2 in the form of a sequence of pulses (16 bits) with a frequency of 300 MHz;

- from BSync 7 via a synchronization channel with a pulse transmission frequency of 1 GHz;

- from WU 6 ₁ through the transmission channel of the trajectory data on the movement of the helicopter in the form of 16 bit words with a frequency of 1 kHz.

The output of the algorithm is an array of data that is transferred to the memory block 4 ₁ for operational storage with a view to their subsequent transmission to processing.

The BFRLI algorithm includes the following sequence of actions:

1) a digital phase detection procedure for intermediate frequency signal information;

2) the formation for each burst of 8 reflected pulses with a duration of, for example, 0.2 μs and a repetition period of 1 μs of complex numbers, taking into account the correcting phase factor of signal delay compensation for the average value of the carrier frequency of the burst pulses and the general index of the frequency modulation of the LFM, for example, μ = 300 MHz / s;

3) recording a sequence of complex numbers in the form of an array of the i-th line of each sequentially formed m-th zone of the beam survey (m = 1, 2, ..., 8) when it is moved with a discrete in time of 1024 μs in the sector of side-view ± 60 ° RLD relative to the straight flight of the helicopter;

4) the formation on an elementary inspection interval of 1.048 s for 8 viewing areas of the beam of the matrix of the original data size (128 × 128);

5) determination of the coordinates of the center of each m-th beam viewing area and the value of the slant range depending on the height of the helicopter;

6) estimation of the radial and tangential components of the speed of the helicopter relative to the centers of each m-th beam viewing area in the middle of the elementary inspection interval;

7) determination of the Doppler shift caused by the speed of the helicopter along the radial component for each of the 128 sounding frequencies;

8) adjusting the values of the complex elements of 8 matrices in size (128 × 128) in order to exclude the influence of the radial approximation of the helicopter;

9) the definition of the sector of the viewing angles of each center of the m-th beam viewing area;

10) the formation of 8 matrices in size (128 × 128), corresponding to discrete two-dimensional radio holograms of rotating objects;

11) the implementation of two-dimensional FFT 8 of these matrices;

12) obtaining discrete images of reconstructed radar images of the underlying surface areas of the corresponding radio holograms;

13) representation of 128 × 128 values of the elements of 8 matrixes for viewing the X-rays of the XRD in the polar coordinate system in the Cartesian coordinate system of the underlying surface, covered by the “frame” of observation 175 m × 60 m, and interpolating the spacing of these “frame” data into 7 matrices corresponding to sites 60 m × 25 m;

14) entering data into memory for each of the sites recorded on the current elementary inspection interval;

15) the formation of similar data for 7 consecutive “frames” in the form of a cell matrix (7 × 7) of the values of the points of the sites;

16) selection of the main diagonal of the formed cell matrix;

17) carrying out the procedure for compiling projections p (u, β) of the reconstructed image of the object, observed from 7 angles;

18) performing, in accordance with formula (7), the operation of convolution of the projections p (u, β) with a pre-calculated core value h _c (u), and the filtered value p _h (u, β) is determined in the frequency domain using the Fourier transform the projections p (u, β) and the nucleus h _c (u) and the subsequent inverse Fourier transform of the product of their images;

к исходной функции g₁(x,y) по фильтрованным значениям р_h(u,β) в каждой точке суммированием значений данных вдоль каждой прямой xcosβ+ysinβ=u¹, проходящей через эту точку [31];19) recovery according to the formula (8) approximations

to the original function g ₁ (x, y) by the filtered values of p _h (u, β) at each point by summing the data values along each line xcosβ + ysinβ = u ¹ passing through this point [31];

, полученных для каждой прямой xcosβ+ysinβ=u¹ декартовой системы координат с разбиением сетки узлов 1 м × 1 м, в сетку узлов 0.1 м × 0.1 м [32];20) recalculation using 4th order interpolation splines of data values

obtained for each straight line xcosβ + ysinβ = u ^{1 of the} Cartesian coordinate system with a meshing of nodes 1 m × 1 m into a grid of nodes 0.1 m × 0.1 m [32];

21) determination of excesses over the adaptive threshold of the accumulated values of reflection intensities from the underlying surface for each section measuring 60 m × 25 m;

22) conducting cluster analysis to determine the assessment of the location of small objects, including mines;

23) regular repetition of the above computational procedures at each elementary inspection interval;

24) transfer of current information to BP 4 ₁ to perform a more detailed analysis of the data obtained during the flight or after the flight to the CP.

The volume of computational costs, by analogy with the calculation of the computational load of a digital computer when solving similar problems [14] to ensure the operation of all BFRLI algorithms in real time, will be about 45 million per second. In general, the implementation of all the computational procedures for the formation of radar images of small-sized objects on the ground in real-time information flow will require about 50 million op./s, which can be implemented, for example, with reprogrammed signal processors of the "Baguette" type [14].

Block WU 6 ₁ performs the following tasks:

the launch of the synchronization unit 7, which forms a grid of clock pulses to synchronize the operation of all blocks of the system;

selection, at the request of the operator, from the memory block 4 ₁ , in which the matrix S _{ij is} actually filled and stored, local sections of the matrix S _ij for visual assessment of the possible presence of mine-like objects in them;

transmitting information about radar data for current terrain to a radio transmitting device 5 for its transmission to a ground processing center (CP) and to a cabin indicator 8 ₁ ;

the issuance in RLD 1 information on controlling the current position of the antenna beam and the values of the parameters of the emitted signal for each mode of operation of the system;

control the operation of block 9 determine the coordinates.

The fundamental point is the implementation of the last function, the implementation of which determines the accuracy of the entire system. Indeed, the accuracy of determining the coordinates of detected objects and, ultimately, the efficiency of the system’s functioning depend on the accuracy of linking the positions of the aircraft and the AFAR beam to the terrain map. Therefore, we will gradually consider the preparatory operations and the work of block 6 ₁ .

Stage 1.

Before the start of the minefield flight, the coordinates of the aircraft (in the hovering mode or when moving at low speed) and the radio beacon (RM) are determined using GPS satellite signals with an accuracy of (3-5) cm. At the same time, the camera is calibrated using the reflector located on RM (not shown in FIG.). The resulting point video image from this reflector will be taken as the origin in the visual image of the area. In this case, the GPS GPS coordinates obtained from the communication channel through the coordinate determination unit 9 are ascribed to the visual coordinate origin. Further, all objects falling into the field of view of the camera will have coordinates relative to the position of the RM. Relative to the starting point, the current position of the aircraft is highlighted, the coordinates of which are determined through the GPS system and, therefore, also tied to the visual origin.

Stage 2.

During a systematic viewing of the terrain using RLD 1, the systems for detecting small objects are displayed on the indicator screen 8 ₁ and subsequently save the bands that increase in length during the flight during the flight, corresponding to the current and viewed “frames” of the earth's surface. These bands also correspond to the intersection of the radiation pattern of the main lobe of the antenna beam in its current positions by the plane of the earth’s surface at a given flight height of the aircraft. At the same time, the coordinates of the indicated intersection sections are calculated in WU 6 ₁ and presented on the indicator screen 8 ₁ .

Stage 3.

A visual map of the area to improve the observability of radar reflections is eliminated by disconnecting the camcorder from the indicator. Its connection will occur only at the moments of observation of bright points from the optical reflectors installed along the contour of the field to adjust the course of the aircraft. Thus, the indicator displays: stripes corresponding to the viewed sections of the earth's surface; memorized and current radar data; positions of reference points from optical reflectors. After the flight is completed, those areas that were missed during a radar inspection of the entire field or were viewed only along one course route (faded areas) will be visible on the screen.

Stage 4.

When radar inspection of the terrain on the screen of the indicator 8 ₂ output radar data in the form of a set of points corresponding to the detected objects in the "frames" of the scanned sections of the earth's surface. Moreover, in the search mode, each point will correspond to an elementary resolution area of 1 × 1 m in size. The brightness of the point, in turn, will depend on the degree of reliability of the detection of the object in this place. In WU 6 ₁ , the coordinates of the detected objects are recalculated from the polar system, in which the antenna of the airborne radar device operates, into a Cartesian system, tied to a map of the area.

Block 6 ₂ , like the on-board unit 6 ₁ , is a computing and control device whose main function is to control the flow of information coming from the on-board part of the system. All radar images in the “frames” of the earth’s surface and video images go to the memory block BP 4 ₂ . The memory in BP 4 _{2 is} divided into two areas. In one of them, incoming video images and radar images are stored, and in the other part, radar images that have been processed in classifier 11 and transmitted from VU 6 ₂ are stored. The control functions of the VU 6 ₂ are manifested in the transfer of commands for the issuance of any information from the PSU requested by the operator, and its output to the indicator 8 ₂ or to the printing device PU 12.

Unit VU 6 ₂ operates in 3 main modes:

Mode 1. Receiving information from block 11 and transmitting it to indicator 8 ₂ .

“Frames” with radar images are transmitted by command from WU 6 ₂ to the classifier 11, in which all the necessary procedures for processing radar images are performed: object detection, selection and recognition of small objects. Each "frame" has its own number, according to which VU 6 ₂ makes its "binding" to the map of the area, i.e. to the video image received from the video camera stored in the PSU 4 ₂ and displayed on the indicator 8 ₂ . Upon receipt from the classifier of the next RI WU 6 ₂ carries out its coordinate reference.

Mode 2. Transfer of processed radar data to the power supply unit 4 ₂ .

Mode 3. Control of the transmission of information at the request of the operator: output of the search results to the indicator or / and to the printing device PU 12.

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Claims (24)

1. A method of increasing radar resolution, including obtaining reflected signals with an appropriate surface survey, characterized in that these signals are obtained using coherent radar sensing of surface areas in the observation sectors of 10-50 ° under survey angles in the range of ± 75 °, the received signals are stored in in the form of corresponding radio images, after which, for each angle of examination, radio images are formed corresponding to the set of signals of the radio images obtained cross sections parallel to the direction of the corresponding angle, in projections onto a plane perpendicular to these directions, and then Fourier transform the generated projections of the radio images, which together for each section using the method of reconstructive computational tomography, for example, the Radon transform, form the corresponding total quasi-hologram with subsequent restoration of it using a two-dimensional inverse Fourier transform of the radio image of the corresponding sections s with increased resolution. 2. A system for remote detection of small objects, including a radar sensor, a computing device and an indicator, characterized in that it includes a matching unit, a radar imaging unit, a classifier, two memory units, a coordinate determination unit, a synchronization unit, printing and radio transmitting and radio receiving devices, as well as an additional indicator and a computing device, the radar sensor being connected with the first output to the first input of the matching unit with its the output connected to the first input of the radar image forming unit connected to the first input of the first memory unit, the output connected to the first input of the radio transmitting device, the second - the control input connected to the first output of the computing device, the second output connected to the second control input of the first memory unit, a group of outputs connected to the first group of inputs of the radar sensor, and the third output connected to the input of the synchronization unit, its first and second in the outputs connected to the second - the synchronizing inputs of the matching unit and the radar image forming unit, respectively, and the group of outputs connected to the second group of inputs of the radar sensor, the second output connected to the third input of the matching unit, while the computing device is connected to the input-output of the first block by an input-output memory, and the fifth and sixth outputs are connected respectively to the first inputs of the indicator and the coordinate determination unit, with their first and second outputs respectively connected to the first input of the computing device and the second input of the indicator, and the radio input associated with the radio input of the system, moreover, the radio transmitting device is connected with its radio output to the radio input of the radio receiving device, the output connected to the first input of the second memory unit, its output connected to the first input of the classifier, the output connected to the first input of the additional computing device with its first, second and third outputs connected respectively to the second input I will give a radio receiver, a second memory block and a classifier, the fourth and fifth outputs connected to the first inputs of an additional indicator and a printing device, respectively, and the input-output connected to the input-output of the second memory block, while the inputs of the computing and additional computing devices are connected respectively to the first and to the second inputs of the system, the output of the printing device is connected to the output of the system, the optical outputs of the indicators are connected to the corresponding optical outputs system, and the group of radio inputs and outputs of the radar sensor is associated with the corresponding group of inputs and outputs of the system. 3. The system according to claim 2, characterized in that the radar sensor contains a phased antenna array consisting of N independently connected transceiver modules, where, for example, N = 1, ..., 24, an adder, two switches, a generator, a modulator and a unit for generating a predetermined distribution of amplitudes and phases of the signals to control the position of the antenna beam of each of the transceiver modules, the transceiver modules being connected with the first electrical inputs to the corresponding outputs of the first switch, the first input connected to the first output of the generator, and the second input connected to the first output of the formation unit for a given distribution of amplitudes and phases of the signals to control the position of the antenna beam of each of the transceiver modules, the second electrical inputs of which are connected to the corresponding outputs of the second switch, the first input connected to the second output of the formation unit a given distribution of amplitudes and phases of the signals to control the position of the antenna beam of each of the transceiver modules, and the second input connected to the first input of the first group of inputs of the radar sensor, the first output connected to the output of the adder, the corresponding inputs connected to the outputs of the respective transceiver modules, and the second output connected to the output of the generator, the first input connected to the output of the modulator, its first input connected to the third input of the first group inputs, and the second input connected to the first input of the second group of inputs of the radar sensor, while the second and third inputs of the second group of inputs of the radar of the second sensor are connected to the second inputs of the generator and the unit for generating a predetermined distribution of amplitudes and phases of the signals to control the position of the antenna beam of each of the transceiver modules, which are the radio inputs and outputs associated with the corresponding radio inputs and outputs of the radar sensor. 4. A method for the remote detection of small objects, including their search, detection and recognition and based on inspection from the aircraft (LA) of the underlying surface by radar sensing and processing the received reflected signals, characterized in that the examination of the underlying surface in the area of the alleged location of small objects, for example in a minefield, is produced when flying around the aircraft of this field by scanning it with simultaneous radar sounding at framing, for example, by an on-board radar station (RLS) or on-board radar sensors (RLD) of the synthesized aperture mode, as well as by incremental discrete rotation of the beam of the RLD antennas at a predetermined angle in each pre-selected elementary inspection interval and determining the coordinates of the reflection places of the corresponding signals at each step of the beam rotation in these inspection intervals, the reflected signals obtained during sounding and the coordinates corresponding to these signals astkov of the underlying surface are memorized, and then radio images corresponding to these reflected signals are formed, which are also memorized, and at the same time they accumulate radio images obtained by sounding each section from different angles, and after this accumulation they are converted into radio images of these sections with an increased resolution of sounding, then they are compared the magnitude of the intensities of the signals from the converted radio images with a threshold signal level, and in areas where the intensity it exceeds the threshold level, by the density of the location on the corresponding sections of these signals, first determine the presence of small objects and the coordinates of their locations, then additionally form radio images of the locations of small objects and compare them with the corresponding reference images, and the examination is carried out in a “binding”, for example to characteristic points of the underlying surface and / or to special reference points pre-installed in the examination area, for example, to beacons and / or optical reflectors. 5. The method according to claim 4, characterized in that the sounding of the underlying surface is carried out in the range of, for example, decimeter radio waves, and the probing signals are generated in the form of a time-limited limited sequence of coherent pulses at different carrier frequencies. 6. The method according to claim 4, characterized in that the synthesis of the aperture of the antenna is carried out during the duration of the pulses having the same carrier frequencies at each elementary inspection interval. 7. The method according to claim 4, characterized in that the elementary inspection interval is selected equal to 0.5-2.0 s. 8. The method according to claim 4, characterized in that the reflected signals are stored in the form of an array of data representing, for example, an n-dimensional (where, for example, n = 4) representation of the values of these reflected signals, as well as signals corresponding to the coordinates of the places reflection, and scanning angles of the corresponding reflection sites in the examined areas of the underlying surface. 9. The method according to claim 4, characterized in that the values of the intensity of the signals for detecting located on the underlying surface and / or buried small objects are obtained by, for example, summing the values of the signals of the converted radio images obtained during each flight of the aircraft and reflected from the same same surface points, with subsequent corresponding assignment to the coordinates on this surface of the resulting signals after comparing them with threshold signals. 10. The method according to claim 4, characterized in that the converted radio images are obtained by forming, for example, using the Radon transform, from the radio images of the reflected signals obtained by examining the corresponding sections of the underlying surface, quasi-holograms with their subsequent restoration into radio images of these sections with increased resolution . 11. The method according to claim 4, characterized in that the recognition uses signs obtained by processing the stored sets of signals reflected from the locations of small objects at different angles of their examination, in the form of restored from quasi-hologram radio images of the corresponding small-sized object. 12. The method according to claim 4, characterized in that the selection of features, their comparison with the relevant standards and the subsequent classification of objects is carried out using algorithms that work on the principles of processing using neural networks, for example, according to the Kohonen algorithm. 13. The method according to claim 4, characterized in that the alleged minefield is inspected by flying around it with scanning and corresponding sounding of each area of the underlying surface at three or more angles. 14. The method according to claim 4, characterized in that after detecting the locations of small objects around these places, they fly around with appropriate scanning and sensing of these areas of the underlying surface in the "telescopic" mode. 15. The method according to claim 4, characterized in that the step size of the discrete rotation of the radar beam of the radar antenna is selected according to the width of this beam in the horizontal plane. 16. The method according to claim 4, characterized in that the predetermined angle of rotation of the radar beam of the antenna is selected corresponding to the angle of coverage of the sector sector of the maximum deviations of this beam of the antenna. 17. The method according to claim 4, characterized in that the beacons and / or reflectors are installed by, for example, dropping them from the aircraft during its flight. 18. The method according to claim 4, characterized in that the beacons and / or reflectors are installed at the borders of the minefield, for example, along its perimeter. 19. The method according to p. 18, characterized in that the distance between the beacons and / or reflectors is chosen corresponding to the width of the examination strip with a single flight of the aircraft. 20. The method according to claim 4, characterized in that the beacons and / or reflectors are installed around the perimeter of the minefield and in areas of the underlying surface on which small objects are detected. 21. The method according to claim 4, characterized in that optical marking devices are installed in the areas of the underlying surface on which small objects are detected. 22. The method according to claim 4, characterized in that when examining the minefield, it is circled along the route from each installed, for example, along the perimeter of the beacon to each other beacon, and the coordinates of these beacons are determined in advance, for example, in the earth coordinate system. 23. The method according to p. 22, characterized in that when examining the minefield, the location of the beacon, for example, installed at the point of the perimeter of the minefield, is selected as the initial (initial) point. 24. The method according to claim 4, characterized in that the signals of the beacons installed at the boundaries of the minefield and on the areas of the underlying surface, on which small objects are detected, are selected with radiated signals that differ in frequency.

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