RU2429507C1 - Method of reconstructing sea bottom relief in depth measurement by hydroacoustic means and device to this end - Google Patents

Abstract

FIELD: physics.

SUBSTANCE: invention may be used in executing meteorological interpolations including analysis of wind fields, radiological and chemical contamination, topographical interpolations and solving other problems, for example, research of ocean, applied problems caused by necessity in sea bed mapping to support research and design works in sea areas.

EFFECT: expanded performances, higher validity of reconstruction.

2 cl, 2 dwg

Description

The invention relates to methods for spatial interpolation of the restoration of the seabed topography with discrete depth measurements by sonar and can be used when performing meteorological interpolations, including analysis of wind fields, analysis of radiological and chemical pollution, topographic interpolations and others.

A device for recognizing sea soil by measuring the parameters of the echo signal when probing the bottom with rectangular pulses [1]. Depending on the type of soil, the echo signal during normal incidence to the bottom changes its shape over a wide range from a theoretically undistorted rectangular pulse on monoliths to a substantially wide pulse with a very shallow front and a duration several times longer than the duration of sending on the ground, which is a liquid mass . As an informative parameter, the steepness of the echo signal rise front is used, which is measured and compared with a pre-graded grid with stiffness boundaries plotted on it for different types of soil. Since it is almost impossible to cover the entire area under investigation with probing signals, linear and nonlinear interpolation methods are used to further construct the bottom topography surface or obtain a topography of a certain two-dimensional scalar geospatial characteristic (see, for example, Problems of the environment and natural resources. M., VINITI, 1999, No. 11, p.13). In addition to the main disadvantage, which is the low reliability of recognition of sea soil, due to the fact that the steepness of the increase in the echo signal is determined mainly by the acoustic properties of the water / soil interface, and not the entire thickness of the soil, then in the presence of irregularities or stony deposits on the surface of the liquid soil the rise of the echo signal front is determined by the reflective properties of irregularities or deposits, which leads to higher values of soil stiffness, and in combination with the subsequent restoration of the relief surface by interpolation of measurements can lead to unreasonable decisions and, consequently, to significant losses in the implementation of a specific task.

In the known technical solution [2], which is an echo sounder for recognizing sea soils, due to the fact that the degree of the physical condition of the soil is determined by the magnitude of the elongation of the echo pulse, based on the dependence of the elongation of the echo signal on the physical and mechanical characteristics of the soil, the accuracy of determining the parameters of the reflecting boundary is improved and the reliability of the measurement results compared with the technical solution [1]. However, the restoration of the relief over the entire investigated surface is reduced to the application of the formal method of interpolation from the measured values, which leads to significant losses in the implementation of a specific task.

In the known method [3], which is a method for determining water depths by a side-scan phase sonar and a side-view phase sonar for its implementation, including emitting a sonar signal to the bottom and receiving the reflected signals at two points located vertically at a given distance, measuring time delays of common-mode signals, pitch angle of the antenna carrier and determination of the directions of arrival of common-mode signals and the desired depths of the water area using the received data m, in which the arrival delay time of the reflected hydroacoustic signal is measured vertically, the arrival delay time of the same common-mode signals is determined in case of reflection from the flat bottom surface in each calculated direction in accordance with the mathematical expression with the convergence of the calculated and measured values of the delay time.

Determining the convergence of the calculated and measured values allows us to reduce the error in determining the depth of the water area when surveying the topography of the bottom of the water area. However, the implementation of this method requires preliminary calculations to determine the estimated directions, which is ensured provided that the results of previous surveys in this area are used. Since over time, the structure of the soil surface does not remain constant due to the variability of hydrodynamic geophysical factors, the use of calculated data is not always correct and can lead to significant errors in obtaining the final results when shooting the bottom topography. In addition, restoration of the bottom topography over the entire investigated surface, as in the well-known technical solutions [1, 2], reduces to the use of the formal interpolation method for the measured discrete values, which leads to significant losses in the implementation of specific tasks, in particular when formalizing the measurement results in cartographic products.

When using known methods, the solution to the relief reconstruction problem is reduced to constructing a continuous two-dimensional function passing through the measured discrete depth values. At the same time, at the first stage, triangulation of measurement points is performed, i.e. on the set of measurement points, the relations of "proximity" of the points are introduced, and at the second stage, the actual desired function is constructed, as a composition of elementary weight functions (linear or nonlinear). With such processing of the initial information, the properties of the relief are not taken into account in any way, and during processing, artifacts of false ridges and hollows in the form of a relief appear, and, therefore, at this stage the morphological method of restoration of the relief is violated.

The identified shortcomings are deprived of the known method of restoring the seabed topography when measuring depths using sonar tools installed on moving marine objects, including measuring the depth with the correction determined by the installation site of the sonar tool, determining the vertical distribution of the speed of sound in water by reflected signals by obtaining data on triangulation observation points with their subsequent interpolation, restoration of the bottom topography, surface construction d in which, when determining the correction, the Doppler frequency shift of the reference signal of the hydroacoustic lag is additionally measured, the speed of the moving marine object is determined by the radio receiver and satellite navigation systems, and the vertical distribution of the speed of sound in water is determined by time series of the sound energy density reflected from internal heterogeneities of the aquatic environment and the bottom, by recording all incoming signals scattered from the internal heterogeneities of the marine food, from the moment of sending a sound pulse to the moment of arrival of the signal reflected from the bottom with the formation of a time series of the density of sound energy reflected from the internal inhomogeneities of the marine environment and the bottom in accordance with the dependence U (Z = 0, t), where Z is the depth at times t, and the speed of sound in water C (Z) is determined by solving the inverse scattering problem, additionally low-frequency waves are recorded by means of artificially excited high-frequency pump waves, the relief shape is restored by relative measurements eniyam relief height in accordance with the inequality

| h (r ₂ ) -h (r ₁ ) | <A | r ₂ -r ₁ | ^λ , where h (r ₂ ) -h (r ₁ ) is the height difference at two spatial points r ₁ , r ₂ ; A (Helder constant), λ (Helder exponent) - positive numbers; 0 <λ≤1. at the same time, the accuracy of the relief reconstruction is estimated by the value of the relative change in the height of the relief depending on the spatial scale, when constructing the bottom surface relief, the data on the triangulation of observation points are interpreted as a structure of an undirected graph with the definition of the lengths (weights) of the edges of the graph, and the device for implementing the method, which is a sonar to determine the depths of the water area, containing functionally connected first and second antennas, one of which is emitting, and the second a receiving paradise forming receiving-radiating channels, a calculator, a control unit in which the control unit is connected to receiving-radiating channels, a calculator, into which an additional pump driver, a plotter, a parametric radiating path are connected, which is connected to the radiating antenna by its output, and the output is connected to the output a pump former, which is connected by its output to the output of the control unit, the plotter is connected by its inputs to the outputs of the calculator and control unit [4].

In contrast to the known technical solutions [1, 2, 3], in which the correction is determined by determining the average vertical velocity of sound in water by determining hydrological parameters by measuring temperature and salinity at standard horizons or by measuring the speed of sound in water at different horizons by installing additional sensors in the aquatic environment, connected by a communication line with the carrier of the depth measuring equipment, in the well-known technical solution [4] The Doppler shift of the reference signal and the velocity of the medium are accurately measured using external information sources, which determine the average vertical speed of sound propagation in the aquatic environment, the values of which determine the correction, which allows continuous monitoring of changes in the average vertical speed of sound propagation in seawater in the process of monitoring the state of the oceans, simplifies the process of determining the average vertical velocity of propagation of stars it is indicated in the aquatic environment with the required accuracy to determine the corrections of the measured depth values, and also eliminates the need for special additional equipment.

When using this method, the accuracy requirements for determining the depth during surveying are established, established by the current regulatory documents regarding shipping, due to the ability to measure the Doppler shift of the reference signal of the sonar lag and the speed of the carrier of the measuring equipment depth from external information sources, which determine the average vertical sound propagation speed in the aquatic environment.

The restoration of the shape of the bottom topography from discrete measurements is carried out by integral transformations, which does not lead to an increase in the observation errors in the initial data during processing, in contrast to the known methods of a differential nature.

Methods for processing sets of homogeneous polynomials are the most developed methods in computer algebra, and the combinatorial method of analyzing geospatial fields by point measurements allows us to solve applied problems taking into account the spatio-temporal dynamics of these fields.

The application of the known method for reconstructing the seabed topography when measuring depths using sonar tools installed on moving marine objects [4] is mainly limited by the solution of two technical problems — this is surveying the bottom topography with subsequent mapping to ensure navigation and determining the average vertical speed of sound propagation in aquatic environment at different horizons to study the processes of movement of water layers.

At the same time, there are a number of tasks, including carrying out the ecological state of marine water areas at the locations of offshore oil and gas terminals and determining the parameters of the boundaries of contaminated water areas and continental shelves and determining bioresources.

Determining the parameters of the boundaries of the continental shelf requires inventory and compilation of the coastal cadastre of the coastal zone, including the compilation of cadastral mapping and topographic plans.

The lack of cadastral survey maps and topographic plans of the continental shelf marine areas from a legal point of view complicates coastal hydraulic engineering construction, which is associated with determining the boundaries of the coastal zone. In addition, there are possible collisions in determining the boundaries of marine water protection zones and coastal protection zones, which, in accordance with the Water Code of the Russian Federation in 2006 as amended by Federal Law of July 14, 2008 No. 118-FZ, are counted from the maximum tide line.

The objective of the proposed technical solution is to expand the functionality while increasing the reliability of restoring the shape of the topography of the seabed with discrete depth measurements using sonar.

The problem is solved due to the fact that in the method of restoring the topography of the seabed when measuring depths using hydroacoustic means installed on moving marine objects, including measuring depth with the determination of the correction due to the installation location of the hydroacoustic means, determining the vertical distribution of the speed of sound in water by reflected signals by obtaining data on the triangulation of observation points with their subsequent interpolation, restoring the shape of the bottom topography, building the bottom surface, when determining the correction, the Doppler frequency shift of the reference signal of the hydroacoustic lag is additionally measured, the speed of the moving sea object is determined by the radio receiver and satellite navigation systems, and the vertical distribution of the speed of sound in water is determined by the time series of the density of sound energy reflected from internal inhomogeneities aquatic environment and the bottom, by recording all incoming signals scattered from internal heterogeneities of the marine food, from the moment of sending a sound pulse to the moment of arrival of the signal reflected from the bottom with the formation of a time series of the density of sound energy reflected from the internal inhomogeneities of the marine environment and the bottom in accordance with the dependence U (Z = 0, t), where Z is the depth at times t, and the sound speed in water C (Z) is determined by solving the inverse scattering problem, additionally low-frequency waves are recorded by means of artificially excited high-frequency pump waves, the relief shape is restored by relative changes the height of the relief in accordance with the inequality

| h (r ₂ ) -h (r ₁ ) | <A | r ₂ -r ₁ | ^λ , where h (r ₂ ) -h (r ₁ ) is the height difference at two spatial points r ₁ , r ₂ ; A (Helder constant), λ (Helder exponent) - positive numbers; 0 <λ≤1, at the same time, the accuracy of the relief reconstruction is estimated from the value of the relative change in the height of the relief depending on the spatial scale; when constructing the relief of the bottom surface, the data on the triangulation of observation points are interpreted as the structure of an undirected graph with the definition of the lengths (weights) of the edges of the graph, in which, unlike the prototype, in addition to the period of formation of time series of the density of sound energy, the number of echo signals from the recorded inhomogeneities is determined, simultaneously with By profiling the bottom by sonar, the bottom is profiled by a high-frequency profilograph, a low-frequency parametric profilograph and a multi-beam echo sounder, sea level fluctuations are determined, soil strength characteristics are determined from the measured drag and friction coefficients from the coastline to the borders of the continental shelf, cadastral maps are formed taking into account the reconstructed relief of the bottom and map soil strength characteristics of the soil, when visualizing the registered area of relief d do not output geospatial data in a two-dimensional and three-dimensional representation as a data structure in SVG format, the construction of the elevation profile along the section is carried out by interpolating points of the vertical section of the soil in the form of rational two-dimensional NURBS spline functions, the approximation of the characteristic section points is performed on the basis of a cubic spline with zero boundary derivatives, when mapping the results of soil characteristics of the continental shelf, the geodetic coordinates of the points of installation of penetrometers with the image of the sections of the soil, while the distance between the sections does not exceed half the minimum diameter of the heterogeneities, and when recording heterogeneities, the measurement frequency on the sections is more than 1/8 ÷ 1/10 of the diameter of the heterogeneities, and the device for implementing the method, which is a sonar to determine the depths of the water area, containing functionally connected first and second antennas, one of which is emitting, and the second receiving, forming receiving-emitting channels, a computer, a control unit, in which the control is connected to the receiving-emitting channels, a calculator, which additionally includes a pump driver, a plotter, a parametric radiating path, which is connected by its output to a radiating antenna, and an input is connected to the output of a pump driver, which is connected to the output of the control unit by its output, and a plotter with its inputs connected to the outputs of the calculator and the control unit, in contrast to the prototype, a second side-scan sonar, a multi-channel generator are additionally introduced probe pulses, a multi-channel echo receiver, a functional control unit, a multi-beam echo sounder, a high-frequency profilograph, a low-frequency parametric profilograph, a penetrometer block, a tide gauge unit, a visualization unit, while a low-frequency parametric profilograph is connected to the output of the pump driver and the output of the multi-channel probe generator pulses, which other outputs are connected to the inputs of the second side-scan sonar, high-frequency profile a raf and a multi-beam echo sounder, respectively, its multi-channel echo signal receiver is connected to the inputs of the functional control unit by its output, which is connected by its output to the input of the computer and the input to the output / input of the control unit, the unit of tide gauges and the block of penetrometers are connected to the functional block by the sonar channel control unit visualization of its inputs is connected to the outputs of the functional control unit, control unit, calculator and plotter, respectively.

New distinctive features of the proposed technical solution, namely, that in addition to the period of formation of time series of the density of sound energy, the number of echo signals from the recorded inhomogeneities is determined, while the bottom is profiled with a sonar, the bottom is profiled with a high-frequency profilograph, a low-frequency parametric profilograph and a multipath echo sounder, and strength soil characteristics by measured drag and friction coefficients from the coastline to the borders of the continental shelf, cadastral maps are formed taking into account the restored bottom topography and soil sections maps according to the strength characteristics of the soil; when visualizing the registered bottom topography region, geospatial data is output in two-dimensional and three-dimensional representation as a data structure in SVG format, and a relief profile is plotted along the section is performed by interpolating the points of the vertical section of the soil in the form of rational two-dimensional spline functions NURBS, approximation of the characteristic points of the section They are performed on the basis of a cubic spline with zero boundary derivatives, when mapping the soil characteristics of the continental shelf, the geodetic coordinates of the penetrometer installation points are plotted with the soil sections displayed, while the distance between the sections does not exceed half the minimum diameter of the inhomogeneities, and when recording heterogeneities, the measurement frequency at the sections is more than 1/8 ÷ 1/10 of the diameter of the inhomogeneities, and the device for implementing the method, which is a sonar for determining the depths of the water area, containing the first and second antennas functionally connected, one of which is emitting, and the second receiving, forming receiving-emitting channels, a calculator, a control unit, in which the control unit is connected to receiving-radiating channels, a calculator, into which an additional pump driver, plotter , a parametric radiating path, which is connected by its output to the radiating antenna, and by an input connected to the output of a pump former, which is connected by its output with the output of the control unit, the plotter is connected to the outputs of the calculator and the control unit by its inputs, in contrast to the prototype, a second side-scan sonar, a multi-channel probe pulse generator, a multi-channel echo signal receiver, a functional control unit, a multi-beam echo sounder, a high-frequency profiler, and a low-frequency parametric are additionally introduced profiler, block of penetrometers, block of tide gauges, block of visualization, while the low-frequency parametric profiler with its inputs it is single with the output of the pump signal generator and the output of the multi-channel probe pulse generator, which is connected to the inputs of the second side-scan sonar, high-frequency profilograph and multi-beam echo sounder, respectively, with the other outputs connected to the inputs of the functional control unit with its output connected to the output the input of the calculator and the input output with the input-output of the control unit, the unit of tide gauges and the block of penetrometers by hydroacoustic anal connection connected to the function control unit, imaging unit its inputs connected to the outputs of the function control unit, a control unit, and calculating a plotter, respectively, allow to solve the environmental monitoring task, determination of biological resources, determining the parameters of the continental shelf.

No new distinguishing features from the prior art have been identified, which allows us to conclude that the claimed technical solution meets the condition of patentability "inventive step".

The essence of the proposed method and device for its implementation is illustrated by drawings (figure 1, figure 2).

Figure 1. The block diagram of the device includes a pump signal generator 1, designed to generate two-frequency probe pump signals with a given duration and a given modulation, the formation of synchronization pulses and gate signals of the receiving path, a parametric radiating path 2, designed to amplify the pump signals at both frequencies to the nominal level ( at the same time, in individual channels, phase correction of the amplitudes can be carried out), the emitting pump converter 3, designed to convert the use of electrical signals into acoustic signals of the necessary directivity characteristics, a receiving antenna of differential frequency signals 4, designed to generate directivity characteristics for receiving and generating acoustic waves of a differential frequency into electrical signals, receiving path 5, intended for preliminary processing of received signals and amplifying them to a level, necessary for registration of received signals, plotter 6, control unit 7, calculator 8, sonar log 9, multipath sounder 10, a high frequency profiler 11, a low-frequency parametric profiler 12 penetrometer block 13, block 14 gauges, multi sounding pulse generator 15, a multichannel receiver echo signal 16, a second side-scan sonar 17, imaging unit 18.

Figure 2. Visualization algorithm for the registered terrain area

Schematic diagrams and the principle of operation of devices 1-9 are similar to the circuit diagrams and the principle of operation of the devices of the prototype [4].

The multi-beam echo sounder 10 is designed to search for fish accumulations, quantify stocks and bottom profiling at an operating frequency of 204 kHz, with a directivity characteristic width of 6 × 10 degrees and 12 × 20 degrees and pulse durations of 50, 200, 500 μs in depth ranges 5, 10, 20, 50, 100 and 200 m.

The second side-scan sonar 17, like the first (prototype device), is designed to capture the bottom topography on the second side of the vessel and to search and quantify fish aggregations and single fish away from the vessel. The working frequency of sonars is 286 and 320 kHz, the width of the directivity characteristics is 1.5 × 50 and 3 × 50 degrees with pulse durations of 50, 100 μs and 1 ms in the depth range of 10, 20, 50, 100 and 200 m.

High-frequency profilograph 11 is designed for accurate profiling of the bottom topography.

The low-frequency parametric profilograph 12 is designed for profiling bottom sediments with operating frequencies of 10 and 150 kHz, with a directivity characteristic width of 3 × 4 degrees and pulse durations of 0.5, 1 and 2 ms in the depth range of 10, 20, 50, 100 and 200 m.

The multi-channel probe pulse generator 15 contains the emitting paths of the multi-beam echo sounder 10 of the first and second side-scan sonars, pump generators of a low-frequency parametric profilograph 12.

The multi-channel echo receiver 16 contains the receiving paths of the multi-beam echo sounder 10 of the first and second side-scan sonars of a high-frequency profilograph 11, a low-frequency parametric profilograph 12, four signal processors designed to convert analog signals to digital form and primary processing of these signals, a communication interface, a control circuit , a signal shaper, a temporary automatic gain control circuit and a sensor signal converter.

The penetrometer 13 is designed to determine undisturbed soil structures in the conditions of its natural occurrence and is a cone-shaped projectile equipped with sensors that are buried under the influence of gravity or with the help of a drill. The measured resistance and friction coefficients determine the strength characteristics of the soil. Depending on the working depth in the range of 0.5-2000 m, a set of sensors is used with a penetration depth of 3 to 20 m into the ground. Analogs are penetrometers of the ТМ - 153 and СРТ type.

Mareograph 14 is designed to record fluctuations in sea level. Depending on the depth of the aquatic environment, automatic gauges such as AMP-20 and AMM-200 are used.

To obtain daily information about the nature of sea level fluctuations, tide gauges are installed at different points in the marine environment in the direction from the coastline. The information recorded by the tide gauges is used to correct the measured depths when surveying the bottom topography in water areas where conventional level posts do not provide sufficient accuracy or are difficult to use, and also to determine the nature of the tide and its harmonic components in solving problems associated with the safe operation of marine terminals, including oil and gas fields. The measurement results are transmitted to the ship via radio and sonar communication channel.

The visualization unit 18 is a hardware computing and video tools with software for displaying the selected information (underwater peaks, depressions, trunk pipelines, pollution areas, soil sections, biosphere products) in two-dimensional or three-dimensional representation.

The method is implemented as follows.

When a vessel moves in a given area of survey of the bottom topography with tacks located from the coastline towards the sea, using the first and second side-scan sonars installed from the right and left sides of the ship, bottom topography is surveyed, and the biosphere products (such as clusters, single instances), by means of a multi-beam echo sounder 10, profiling of the bottom and searching for biosphere products are performed, by means of a high-frequency profilograph 11, profiling of the bottom is performed by means of a low -frequency parametric profiler 12 operates profiling of bottom sediments. In parallel with the sensing of the bottom surface and the process of determining the depths, the vertical speed of sound propagation in the aquatic environment is determined using the sonar lag 9, the sea level fluctuations are determined using the unit of tide gauges 14, and the coordinates and speed of the vessel are determined by means of standard ship receiver indicators of satellite or radio navigation systems.

According to the data obtained, the correction to the depths is determined by the known dependencies and algorithms and introduced into the calculator 8. The measured depths are processed by known algorithms, as in the prototype. From the measured values of the speed of sound in water in a vertical plane, the sound velocity field is determined. The determination of the vertical distribution of the speed of sound in water over time series of the density of sound energy reflected from the internal inhomogeneities of the aquatic environment and the bottom is performed, as in the prototype, by recording all incoming signals scattered from the internal inhomogeneities of the marine environment, from the moment of sending a sound pulse to the moment the arrival of signals reflected from the bottom with the formation of a time series of the density of sound energy reflected from the internal inhomogeneities of the marine environment and the bottom. In this case, the speed of sound in water is determined by solving the inverse scattering problem with registration of low-frequency pump waves by means of artificially excited high-frequency pump waves, which are used to judge the relative orientation of the interacting waves and the value of the medium nonlinearity parameter.

Next, the processing of time series and the procedure for determining the parameters of a complex heterogeneous medium according to the algorithms proposed in the prototype are performed.

Based on the obtained discrete measurements of the depths, as well as taking into account the scattering coefficients of the sound, the bottom determines the class of functions to which the relief belongs.

Studies of the shape of the relief at different spatial scales (according to the prototype) showed that the relative changes in the height of the relief are power-law related to the spatial scale in the form

| h (r ₂ ) -h (r ₁ ) | <A | r ₂ -r ₁ | ^λ , where

h (r ₂ ) -h (r ₁ ) is the height difference at two spatial points;

r ₁ , r ₂ , A (Helder constant), λ (Helder exponent) - positive numbers; 0 <λ≤1.

In this case, the desired function H (r) is expressed as the inverse Fourier transform:

H (x, y) = ℑ (F (ζ)), where ζ is the operator of the inverse Fourier transform,

.

.

Here i is the imaginary unit, ξ = (cosφ, sinφ),

,

,

k = 0,1,2 ...

Here

- преобразование Радона функции H(x, y) на (х, у)∈R×R=Ω, т.е. интегральное преобразование, относящее функции Н(х, у) на Ω ее интегралы по всевозможным прямым (относительно евклидовой длины): х=-tsinφ+pcosφ; у=tcosφ+psinφ.

is the Radon transform of the function H (x, y) on (x, y) ∈R × R = Ω, i.e. the integral transformation relating the function H (x, y) to Ω its integrals over all possible straight lines (with respect to Euclidean length): x = -tsinφ + pcosφ; y = tcosφ + psinφ.

For a finite function H (x, y) in a simply connected domain Ω, the accuracy of the estimate will be better than the accuracy of traditional interpolation procedures.

The error Θ (N) of the relief reconstruction is determined as the maximum value of the absolute value of the difference between the true surface and the restored one:

, где К - общее число первых моментов, обеспеченных точностью. Точности оценки моментов δ(I_k) будут определяться структурой расположения точек измерения.

where K is the total number of first moments ensured by accuracy. The accuracy of the moment estimation δ (I _k ) will be determined by the arrangement of the measurement points.

For optimal distributed points (measurements), which can always be determined on the initial set of points (see, for example, Sobol I. M. Multidimensional quadrature formulas and Haar functions. M., Nauka, 1969, p. 288.) The accuracy of the moment estimate for the normalized function is selected in accordance with the expression δ (I _k ) ≤2 / Nk.

The restoration of the shape of the relief of the seabed can be performed after each series of discrete measurements.

When researching underwater objects, for example, offshore sections of trunk pipelines, underwater signals are distinguished by recorded echo signals according to their frequency characteristics and their size is estimated by the frequency interval between the minimum and maximum values of the target force on the frequency dependences (see, for example: Clay K., Medvin G. Acoustic Oceanography, Fundamentals and Applications, Moscow: Mir, 1980, 580 p.). The magnitude of the target’s strength is analyzed depending on the product ka, where a is the radius of the target, k = 2π / λ is the wave number. For acoustically rigid objects of a spherical shape, the magnitude of the target force in the intermediate region between Rayleigh and geometric scattering, i.e. in the region where 1 <ka <10, fluctuates, asymptotically approaching its constant value for ka >> 1 (see, for example: Urik R.J. Fundamentals of hydroacoustics. L .: Shipbuilding. 1978. - 448 p.). The reason for these oscillations, as shown by theoretical and experimental studies, is the re-emission of surface and diffracted waves, which contribute to the process of echo formation along with specular reflection. The resulting interference between these types of waves with a sufficient duration of the probe pulses leads to oscillations in the frequency dependences of the target force. The level of these oscillations, the number, and the interval between them are determined by the physical parameters of the object, its geometric dimensions, which makes it possible to use the frequency dependence of the target force as one of the simple and fairly informative signs of classification. Assessing the size of objects together, taking into account the absolute magnitude of the target’s strength, is quite sufficient to distinguish objects by their dimensions and, on the basis of this, make a decision about belonging to a particular class.

In the performed experimental studies, the problem of sound scattering on an acoustically rigid elastic sphere located beyond the region of effective nonlinear wave interaction was solved in accordance with the well-known technique (see, for example, W.K. Metsaveer, Ya.A. Veksler, N.D. Kutser Echo signals from elastic objects. Tallinn: Academy of Sciences of the ESSR, 1974, 214 pp.), Which makes it possible to study with a high degree of accuracy the sound fields of reflecting objects in a homogeneous medium in cases where the effect of nonlinear reflection interaction can be neglected. pump waves generated from the object. These cases include the option of scattering from bodies located in the far zone of the parametric antenna, or scattering from spheres located in a homogeneous medium with significant absorption for pump waves, for example, in a water-saturated homogeneous silt.

An analysis of the results of experimental studies showed that for objects made in the form of a solid steel sphere, the shape of the reflected signal depends on the ratio between the diameter of the sphere and the length of the acoustic wave. In the case of using spheres of acoustically soft material (foam) or a hollow sphere filled with air with a thin wall, the shape of the reflected pulses in the places of the minima in the frequency dependences of the target force differs from the shape of the pulse reflected from the solid sphere, which makes it possible to distinguish the spheres from the shape of the echo envelope made of acoustically hard and soft materials.

Quantitative assessment of biosphere products is carried out according to several algorithms depending on the structure and density of the bioproduct accumulation.

In general, the quantitative estimation algorithm determines the transition from the number of echo signals to the absolute value - the number of biological products, for which a normalized value is determined - the average density of the cluster. The patterns of depth distribution of accumulation of biological products by depth are determined by dividing the range into layers and calculating the density of accumulation for each layer.

In particular, the quantitative characteristics of rarefied clusters are estimated on the basis of the expression for the average density of a rarefied cluster (see, for example: Ermolchev V.A. Echo-counting and echo-integrating systems for quantifying fish clusters. - M.: Food Industry, 1979 . - p. 193):

,

,

where K ₁ is the number of echo signals from biological products from layer 1;

S is the cross section of the sonar area, m;

H is the thickness of the cluster, m;

Q is the repetition rate of the emitted signals;

T - the time of passage of the vessel over the cluster, hour;

m is the number of layers.

For open clusters, the direct echo counting method is used.

The measured resistance and friction coefficients using the block of penetrometers 13 determine the strength characteristics of the soil.

Penetrometers are cone-shaped shells equipped with sensors that, under the influence of gravity or with the help of a drill, are buried in the ground and are installed from the vessel in the direction from the coastline inland. In this case, the drag and friction coefficients are measured, which determine the strength characteristics of the soil at several horizons along the soil depth in the range from 3 to 20 m along the entire length of the water area from the coastline. In the subsequent analysis, the structure of the soil is established and a judgment is made on whether a particular structure of the underwater soil belongs to the soil structure of the continental shelf.

Information mapping is carried out by applying the geodetic coordinates of the reflection points of hydroacoustic signals from the seabed onto a tablet, which is built by pairing topographic and navigation raster maps in the following sequence:

- the raster of the navigation map in the Mercator projection is subjected to vectorization of the coastline of the navigation map;

- a site is selected that corresponds to the marine area on which the bottom topography is recorded taking into account the vectorization of the coastline of the navigation map;

- a record is made in the final raster of the navigation map;

- the raster of the topographic map in the Gauss-Kruger projection is reduced to the scale of the navigation map;

- the coordinates of the Gauss-Kruger projection are converted into geographical coordinates;

- the conversion of geographical coordinates to the coordinates of the Mercator projection is performed;

- a raster plot is selected that corresponds to the land (coastal) region;

- the topographic map is written to the final raster;

- based on the results of recordings in the final rasters of the navigation and topographic map, the final raster map of the combined navigation and topographic information in the Mercator projection is built;

- on the final raster map displayed on the display device, the path of the vessel is also displayed.

When mapping the results of soil characteristics of the continental shelf, the geodetic coordinates of the points of penetrometer installation are plotted with the display of soil sections. In this case, the distance between the sections does not exceed half the minimum diameter of the inhomogeneities, and when recording heterogeneities, the measurement frequency on the sections is more than 1/8 ÷ 1/10 of the diameter of the inhomogeneities.

Processing and visualization of the registered areas of the bottom, soil, underwater objects, biosphere products is carried out using a computer 8, plotter 6 and visualization unit 18.

When visualizing the registered region of the bottom topography, the data for the VRML interpreter (Fig. 2) is formed in the RAM of the computer of the computing device with subsequent loading into the interpreter. For this purpose, a JavaScript node is included in the boot VRML file, whose functions control the area of visible space. Software tools for cartographic visualization are data structures in the SVG format, which supports vector and raster data. The display in the browser of data in the SVG format is carried out by the interpreter of the declarative language SVG. The data in the SVG structure is generated similarly to the formation of data in the VRML format. Based on the data in the XML structure (geospatial information, including location coordinates relative to the coastline of marine terminals, their overall dimensions, etc.) received from the database upon request, they are converted in browser memory to SVG using XSLT-T. For the simultaneous presentation of geospatial data in a two-dimensional and three-dimensional representation, support is provided for synchronization of navigation across one and the other scene. A rectangle corresponding to the current region of space is displayed on the cartographic scene, the data of which is loaded into the memory of the VRML interpreter. Synchronization from the side of SVG is based on JavaScript functions built into SVG and HTML. Since synchronization on the part of VRML is more difficult, a JavaScript node is included in the VRML boot file with navigation functions that do not allow a three-dimensional image to go beyond the viewport and constantly monitor the coordinates of the viewport. These coordinates serve as necessary information for synchronization with the cartographic scene, which is possible using the HTML timer.

The navigation system is constructed using an alternative principle to the observation point of a three-dimensional scene, which is alternative to the well-known GA technology, in which the standard principle is used - the observation point is located outside the scene and the scene is stationary during navigation, and the coordinates of the observation point and the viewing angle are changed. In this case, the center of rotation is not clearly determined, which is one of the reasons for the loss of image during navigation. In the technology used, the observation point is constantly in the center of the observation window and is visualized by a small trihedral of axes, and the beginning of the trihedron is always the center of rotation of the image and when navigating the scene moves relative to this center.

The visualization module 18 also displays areas of bottom topography and sections of underwater soil. In this case, interpolation of height points (depths) is carried out by the methods of two-dimensional spline functions, and specifically in the form of two-dimensional irregular rational fundamental splines (NURBS) (see, for example: Golovanov N.N. Geometric modeling. M., Fizatlit, 2002, 472 s .). The advantage of this method is the interpolation of elevation points in the form of two-dimensional rational two-dimensional spline-functions NURBS, which allows you to build a smooth surface for any shape of the relief, even for cliffs with a negative angle of inclination. Secondly, the surface of the relief is determined by the analytical dependence, i.e. a finite set of parameters of a fixed set of functions (polynomial splines). The analytical form of the terrain assignment, i.e. in the form of a superposition of analytic functions of two variables, it allows you to use the entire apparatus of differential geometry to describe the morphometric properties of the relief, for example, calculating the value of a function (height, depth) or its differential (slope) at any point (points) of the domain of the function. Third, NURBS provides the ability to locally edit surface shapes. In addition, for the same area of the earth, the DEM data array using NUBRS will be at least an order of magnitude smaller than with the traditional point representation. The use of NURBS increases the efficiency of visualization of registered and stock information by reducing processing time and the required amount of memory. The use of NURBS in computing has long been a fact: in the graphics packages of all operating systems, NURBS processing and visualization algorithms are integrated, for example, in low-level graphics packages: DirectX and OpenGL for Windows. However, when constructing a DTM, there are obstacles associated with the effect of the occurrence in some situations of a violation of monotony in surface changes — the local appearance of false oscillations. In a specific technical implementation, this obstacle is eliminated either by adding new points to the array for interpolation, or by using methods of isogeometric approximation by splines (see, for example: B. Kvasov. Methods of isogeometric approximation by splines. - M. - Izhevsk: Research Center “Regular and chaotic dynamics. "Institute for Computer Research. 2006. - 416 p.).

In the first case, the solution to the problem is associated with an increase in the expert’s work in the iterative procedure for constructing NURBS, in the second, with a significant complication of the mathematical algorithms of the technology.

The proposed method implements the technology of building a DEM based on NURBS in the form of an iterative expert automated procedure. The programming language used is the MatLab language. In this system, the quality of DEM construction is determined by expert comparison of the position of contours calculated according to NURBS with the position of the corresponding isohypses (isobaths) on the original map.

In a specific implementation of the proposed method, raster maps serve as a source of terrain information.

In the general case, when approximating the profile of the relief with one-dimensional splines, one should specify the values of the first two derivatives at the end points of the section. However, such information is unknown, and it is impossible to obtain it in practice. Therefore, the simplest cubic spline with zero boundary derivatives was used as the base spline for approximating the relief profile along the section. Due to the fact that there are no explicitly defined two-dimensional splines, since it is impossible to construct an infinite system of algebraic equations for matching the first two derivatives in all directions at the adjacent boundaries of two pieces of a spline surface, the construction of a two-dimensional spline function is performed using the tensor product of one-dimensional splines (see ., for example: Zavyalov Yu.S. Kvasov B.I., Miroshnichenko V.L. Methods of spline functions. - L. - M .: Nauka, 1980. - 350 p.).

The coordination of the first two DPC differentials for adjacent rectangular map sections is ensured by overlapping task areas of adjacent NURBS.

Thus, the technology of building DEM in an analytical form based on NURBS allows you to exclude the triangulation stage and thereby eliminate the disadvantages of existing technologies. The proposed implementation of the technology can be adapted to other types of source information, and more complex types of basic splines can be included in it.

The implementation of the proposed technical solution does not present a technical difficulty, since it can be implemented on the basis of computing facilities and full-time ship depth gauges, navigation aids and navigation support aids.

Information sources:

1. Copyright certificate SU No. 1103171.

2. Patent RU No. 2045081 C1.

3. Copyright certificate SU No. 1829019 A1.

4. Patent RU No. 2326408 C1.

Claims (2)

1. A method of restoring the topography of the seabed when measuring depths using sonar tools installed on moving marine objects, including measuring the depth with a correction determined by the installation site of the sonar tool, determining the vertical distribution of the speed of sound in water by reflected signals, by obtaining data on point triangulation observations with their subsequent interpolation, restoration of the shape of the bottom topography, construction of the bottom surface, in determining the amendment will complement The Doppler frequency shift of the reference signal of the hydroacoustic lag is measured, the speed of a moving marine object is determined using a radio receiver and satellite navigation systems, and the vertical distribution of the speed of sound in water is determined by time series of the density of sound energy reflected from the internal inhomogeneities of the aquatic environment and the bottom, by registration of all incoming signals scattered from internal inhomogeneities of the marine environment, from the moment of sending a sound pulse to m the arrival time of the signal reflected from the bottom with the formation of a time series of the density of sound energy reflected from the internal heterogeneities of the marine environment and the bottom in accordance with the dependence U (Z = 0, t), where Z is the depth at time t and the speed of sound in water C (Z) is determined by solving the inverse scattering problem, low-frequency waves are additionally recorded by means of artificially excited high-frequency pump waves, the relief shape is reconstructed from the relative changes in the height of the relief in accordance with the inequality your
| h (r ₂ ) -h (r ₁ ) | <A | r ₂ -r ₁ | ^λ , where h (r ₂ ) -h (r ₁ ) is the height difference at two spatial points r ₁ , r ₂ ; A (Helder constant), λ (Helder exponent) - positive numbers; 0 <λ≤1, at the same time, the accuracy of the relief reconstruction is estimated from the value of the relative change in the height of the relief depending on the spatial scale; when constructing the relief of the bottom surface, the data on the triangulation of observation points are interpreted as the structure of an undirected graph with the definition of the lengths (weights) of the edges of the graph, characterized in that in addition to the period of formation of the time series of the density of sound energy, the number of echo signals from the recorded inhomogeneities is determined simultaneously with the profiling the bottom of the bottom of the sonar performs profiling of the bottom with a high-frequency profilograph, a low-frequency parametric profilograph and a multi-beam echo sounder, determine sea level fluctuations, determine the strength characteristics of the soil from the measured drag and friction coefficients from the coastline to the boundaries of the continental shelf, form cadastral maps taking into account the restored bottom topography and section maps soil according to the strength characteristics of the soil, when visualizing the registered area of the bottom topography they output geospatial data in two-dimensional and three-dimensional representations in the form of a data structure in SVG format, build a profile of the relief along the section by interpolating the points of the vertical section of the soil in the form of rational two-dimensional spline functions NURBS, approximate the characteristic points of the section using a cubic spline with zero boundary derivatives, when mapping the results of the characteristics of the continental shelf soils, the geodetic coordinates of the penetrometer installation points are plotted m soil incisions, the distance between the slits is less than half the minimum diameter irregularities and inhomogeneities in the registration frequency measurements in sections is more than 1/8 ÷ 1/10 diameter irregularities. 2. A device for implementing the method, which is a sonar for determining the depths of the water area, containing functionally connected first and second antennas, one of which is radiating, and the second receiving, forming receiving-emitting channels, a computer, a control unit, in which the control unit is connected to receiving-emitting channels, a calculator, which additionally includes a pump driver, a plotter, a parametric radiating path, which is connected to the radiating antenna by its output, and the odom is connected to the output of the pump driver, which is connected to the output of the control unit by its output, the plotter is connected by its inputs to the outputs of the computer and control unit, characterized in that a second side-scan sonar, a multi-channel probe pulse generator, a multi-channel echo signal receiver, and a functional control unit are additionally introduced , multi-beam echo sounder, high-frequency profilograph, low-frequency parametric profilograph, penetrometer block, tide gauge block, visualization block a case, the low-frequency parametric profilograph with its inputs is connected to the output of the pump signal shaper and the output of a multi-channel probe pulse generator, which is connected to the inputs of the second side-scan sonar, high-frequency profiler and multi-beam echo sounder, respectively, the multi-channel echo signal receiver is connected to the inputs of the functional block control, which by its output is connected to the input of the calculator and input-output with input-output of the unit a control unit and gauges on penetrometer hydroacoustic communication channel connected to the function control unit, imaging unit its inputs connected to the outputs of the function control unit, a control unit, and calculating a plotter, respectively.

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