RU2602770C1 - Method of hydrophysical and geophysical fields acoustic tomography in marine environment - Google Patents

Abstract

FIELD: hydrophysics.

SUBSTANCE: invention relates to hydrophysics, geophysics and can be used in solving tasks of hydrophysical and geophysical fields complex monitoring generated by natural and artificial sources, ocean and Earth's crust processes and effects. Such fields are generated by sea objects, dynamic and seismic, as well as synoptic processes and hazardous phenomena. Disclosed method of hydrophysical and geophysical fields acoustic tomography in marine environment, includes placement of monitoring system transmitting and receiving units on opposite boundaries of controlled environment, environment insonation with stable frequency scanning low-frequency signals and formation of nonlinear interaction zone in it and parametric conversion of luminal and measured information waves. Reception, amplification and spectral analysis of nonlinearly converted scanning signals, determination of information waves characteristics in them. Method is characterized by that monitoring system receiving unit is formed as discrete linear antenna, including n elements (acoustic transducers), which are placed horizontally in emitting unit direction. Scanning signals are received by discrete antenna converters, preliminary amplified and transmitted to system receiving channel by means of multicore cable, into their frequency-time scale into high-frequency domain converting unit, then into channel switching and continuous transmission signal formation unit, formed continuous signals are amplified in parametric conversion band, their narrow-band spectra are measured, selected in spectra upper and/or lower side bands, which are generated and presented in 2D and (or) 3D, recorded and hydrophysical and geophysical fields signs and their spatial-time dynamics is determined taking into account of parametric and frequency-time conversion. Besides, number of receiving transducers n in linear receiving antenna is set in amount of 10 articles, and distances between them is half of scanned acoustic wave length. Besides, number of antenna elements n corresponds to receiving scanned signals frequency-time conversion scale. Besides, controlled environment is sounded by stable frequency scanned acoustic signals within range of tens-hundreds Hertz. Besides, operations of measurement and generation of measured fields spectra in 2D and (or) 3D form are synchronized with receiving channels cyclic switching and continuous signal forming mode.

EFFECT: technical result is development of hydrophysical and geophysical fields characteristics in marine environment scanning tracing acoustic tomography technologies, as well as continuous monitoring and control over their space-time dynamics on water areas with length of tens-hundreds of kilometers in frequency range, making hundreds-tens-points of kilohertz, hundreds-tens-points-fractions of Herz.

5 cl, 10 dwg

Description

The method relates to hydrophysics, geophysics and can be used in integrated monitoring systems of hydrophysical and geophysical fields formed by natural and artificial sources, processes and phenomena of the ocean and the earth's crust. Such fields are formed by marine objects, dynamic and seismic, as well as synoptic processes and dangerous phenomena. A new scientific and technical solution of the invention is the long-range parametric reception of hydrophysical and geophysical waves in the marine environment, the measurement and presentation of the spectra of the measured waves in the 2D and (or) 3D format, as well as the observation of their spatio-temporal dynamics. In this case, information fields are measured and recorded in a wide range of frequencies, comprising hundreds - tens - units of kilohertz, hundreds - tens - units - fractions of hertz, including the range of VLF vibrations of moving objects and hydrodynamic inhomogeneities of the marine environment as a whole.

In recent decades, in the problem of monitoring and developing the ocean environment, research and scientific and technical development of methods and tools for low-frequency hydroacoustics have become an increasingly relevant area. Moreover, the most complex and urgent problem of low-frequency ocean acoustics is the development of acoustic tomography methods of the marine environment, and in a broader sense, the development of methods for acoustic diagnostics of the spatio-temporal characteristics of hydrophysical fields of objects and medium inhomogeneities in an extended ocean waveguide. This direction combines both the solution of the problem of sound propagation in an extended oceanic waveguide (direct problem) and the solution of the inverse problem, namely, reconstruction of the characteristics of the hydrophysical and geophysical fields of a controlled marine environment from measurements. Such environmental characteristics include, for example, a vertical profile of sound velocity inhomogeneous along the track, fields of objects present in the medium, as well as heterogeneities and accumulations of the marine environment and the seabed of natural or artificial origin in a wide frequency range.

Known developments of methods and systems of acoustic tomography of spatial images of heterogeneities and objects of the ocean environment are based on the reconstruction of their spatial structure. At the same time, restoration of images of objects and heterogeneities of the environment is performed by acoustic measurements of their projections followed by special processing of the measured data, ensuring the formation of their spatial contour (see Goncharov V.V., Zaitsev V.Yu. and others. Acoustic tomography of the ocean. N Novgorod: IAP RAS, 1997, p. 5-13).

These developments do not exhaust the known variety of practical problems of acoustic tomography of the ocean. These tasks, first of all, include the development of technologies for long-range low-frequency tomography of the fields of objects and heterogeneities of the marine environment of various physical nature (acoustic, electromagnetic and hydrodynamic) in a wide range of frequencies formed by them. Such a task of acoustic tomography can be effectively solved on the basis of the development of measuring technologies of nonlinear translucent hydroacoustics (NPGA). Nonlinear translucent hydroacoustics as a new multifunctional direction, combining the classical directions of active, passive and high-frequency nonlinear acoustics, has been intensively developed and implemented in monitoring systems of hydrophysical and geophysical fields of objects and the marine environment in recent decades (See Mironenko M.V., Malashenko A.E. ., Karachun L.E., Vasilenko AM Low-frequency translucent method for long-range sonarization of hydrophysical fields of the marine environment. Vladivostok: SKB SAMI FEB RAS, 2006. 172 p.).

Measuring technologies developed on the basis of regularities of NPGAs provide long-range parametric reception of information fields of objects, the marine environment and the seabed of various physical nature. Such designs are protected by invention patents. So, for example, with the participation of the authors of the claimed invention, “Methods and systems implementing their long-range parametric reception of waves of various physical nature in the marine environment” have been developed that are implemented on the basis of patterns and measuring technologies of nonlinear translucent hydroacoustics: RU 2158029 C2 15.12 1998, RU 2167454 C2 12/15/1998 , RU 2453930 C1 11.10.2010, RU 2452040 C1 11/10/2010, RU 2452041 C1 11.10.2010, RU 2472236 C1 06/15/2011, RU 2472116 C1 15.06.2011, RU 2474793 C1 15.06.2011, RU 2474794 C1 15.06.2011, RU 2503977 C1 18.07.2012, RU 2503036 C1 17.07.2012), RU 25.36836 C1 10.29.2014, RU 2536837 C1 10.29.2014, RU 2550588 C1 03/10/2015.

A common drawback of the above technical solutions is the lack of the ability to measure and represent the spectra of the measured information fields in 2D and (or) 3D format, as well as the ability to observe and control their spatio-temporal dynamics. So, in the well-known technical solutions for the development of methods and systems for the long-range parametric reception of information hydrophysical and geophysical fields of objects and the environment, there is no solution to the problem of long-range acoustic tomography of the characteristics of the measured information fields, as well as the possibility of observing their spatio-temporal dynamics. They are analogues of the invention.

The closest of them in technical essence to the claimed invention is the "Method of parametric reception of waves of various physical nature in the marine environment" RU No. 2453930 C1 from 10.10.2010, which is selected as the prototype method.

The problem to which the invention is directed is to further develop a prototype method for its implementation as a method of translucent acoustic tomography of hydrophysical and geophysical fields in a marine environment. Moreover, the proposed method should provide long-range parametric reception of hydrophysical and geophysical fields of objects, the marine environment and the seabed, the formation and presentation of their spectral characteristics in the 2D and (or) 3D format, as well as constant monitoring of their spatial and temporal dynamics. It should be noted that this drawback (the constant measurement of the spectra of information fields and the control of their spatial and temporal dynamics) in the solutions of analogs and the prototype method is due to the use of the necessary operation in them - the time-frequency conversion of received translucent signals and transfer of their scale to the high-frequency region. The development of such systems is known and published (See Chernitser VG, Kaduk B.G. Time-domain converters. M: “Sov. Radio - 1972. 144 p.). The indicated operation increases the energy concentration of the received nonlinearly transformed luminal signals, and during processing increases the efficiency of extracting information waves from them, but at the same time excludes the implementation of continuous acoustic tomography of information fields. In addition, in methods and systems of nonlinear translucent hydroacoustics, information fields are distinguished from the side bands of the frequency spectrum, nonlinearly transformed translucent signals, which provides automatic “suppression” of intense pump signals and environmental noise characteristic of methods and systems of classical acoustic tomography of the marine environment (See Attenuation of the sounding field and noise during observation (in the book by N. Pronchatov and others. Development of effective methods and means of acoustic observation. N. Novgorod. NSU, 2006, pp. 30-35). This indicates the advantages of choosing NPHA technologies as a prototype method. To implement continuous acoustic tomography technologies, it is necessary to apply additional signal processing operations, as well as changing the sequence of their implementation, which is justified and considered in the description of the application for the invention.

The technical result of the invention consists in the development of measuring technologies for translucent acoustic tomography of hydrophysical and geophysical waves in the marine environment, providing the formation and presentation of their spectra in the format of 2D and (or) 3D, as well as the control of their spatial and temporal dynamics in water areas of tens to hundreds of kilometers . The frequency range of the measured information waves is hundreds - tens - units of kilohertz, hundreds - tens - units - fractions of hertz.

To solve this problem, the method of translucent acoustic tomography of hydrophysical and geophysical fields in the marine environment includes placing the emitting and receiving units of the monitoring system at opposite edges of the controlled area, scoring it with low-frequency translucent signals of a stable frequency and forming in it a working zone of nonlinear interaction and parametric transformation of the translucent and measured information waves, reception of nonlinearly transformed luminous waves, measurement their narrow-band spectra, the allocation in the spectra of the upper and (or) lower side bands and the definition of information waves in them, characterized in that the receiving unit of the measuring system is formed as a discrete linear antenna consisting of n acoustic elements (hydrophones) that are horizontally placed in the direction of the radiating unit, the luminal signals received by the antenna elements are pre-amplified and transmitted via a multicore cable to the receiving path of the measuring system - to their frequency-time conversion unit scale to the high-frequency region, and from it to the switching unit of the receiving channels and generating a total signal in which the signals from the 1st to the n-th channel are continuously and cyclically switched and sequentially summed on each switching cycle, then they are further amplified in the frequency band parametric transformations, measure their narrow-band spectra, select the upper and (or) lower side bands of the spectrum in them, which form and represent in 2D and (or) 3D format, the formed spectra are recorded and taking into account the frequencies The temporal and parametric transformations determine in them the information features of hydrophysical and geophysical fields and their spatio-temporal dynamics. In addition, the number of receiving elements n in the linear discrete antenna is set at 10, and the distance between them is half the length of the translucent acoustic wave. In addition, the number of antenna elements n corresponds to the scale of the time-frequency conversion of the received translucent signals. In addition, the controlled environment is voiced by transparent acoustic signals of a stable frequency in the range of tens to hundreds of hertz. In addition, the operation of forming the spectrum of information fields in the format 2 and (or) 3 is synchronized with the cyclic switching mode of the receiving channels and the formation of a continuous signal.

A comparative analysis of the features of the claimed and well-known technical solutions indicates its compliance with the criterion of "novelty." The features of the characterizing part of the claims solve the following functional tasks.

The signs "the receiving unit of the measuring system is formed as a discrete linear antenna of n acoustic elements (hydrophones) horizontally placed in the direction of the emitting unit", provide a preliminary operation for receiving translucent signals with time delays equal to half the wavelength for their subsequent phase addition. The principles of the formation and operation of linear discrete sonar antennas are developed and set forth in a well-known monograph (See Smaryshev MD Linear discrete antennas. In the book. Orientation of sonar antennas. Shipbuilding. L. 1973, p. 140-152).

The signs “the multi-channel signals received by the antenna are preliminarily amplified and transmitted via a multicore cable to the receiving path of the measuring system - to the input of the unit for converting their frequency-time scale to the high-frequency region”, they ensure the formation of reduced segments of the received signal for their subsequent addition as continuous.

The signs “signals from the 1st to the nth elements are continuously and cyclically switched and summed sequentially on each cycle” provide the final operation — continuous acoustic tomography of the fields using the technology of their spatio-temporal transformation.

The signs “formed continuous signals additionally amplify, measure their narrow-band spectra, distinguish their upper and (or) lower sidebands” provide a preparatory operation for the effective measurement of the spectra of the received luminal signals and the separation of the information wave spectra from them.

The signs “the measured spectra are formed and presented in 2D and (or) 3D format, recorded and, taking into account the time-frequency and parametric transformations, they determine the signs of hydrophysical and geophysical fields and their spatio-temporal dynamics” provide a distinctive feature of the processing of the measured spectra for their spatial submission and subsequent registration, which is the final operation of the method. The signal processing used in the method (measuring spectra, generating, presenting and recording them in 2D and (or) 3D format) is carried out using digital devices and (or) computers.

The feature of the second paragraph “the number of receiving elements n in a linear discrete antenna is set in the amount of 10 products, and the distance between them is half the length of the translucent acoustic wave” ensures the operation of the receiving unit of the system as a linear discrete antenna, which is the initial condition for implementing the acoustic tomography method.

The feature of the third paragraph "the number of antenna elements n corresponds to the scale of the time-frequency conversion of the received translucent signals", ensures the continuation of the further operations of the acoustic tomography method.

The sign of the fourth paragraph “the controlled environment is voiced by transparent acoustic signals of a stable frequency in the range of tens to hundreds of hertz”, provides the implementation of long-range and ultra-long parametric reception of information waves, which is the subject of a scientific and technical solution of the presented method of translucent acoustic tomography.

The feature of the fifth paragraph “the operations of forming the spectra of the measured fields in the format 2 and (or) 3 synchronize with the cyclic switching of the receiving channels and generating a continuous signal” provides control of the measurement system in accordance with the formation of the spectra of the measured information fields in the 2D and (or) 3D format and control of their spatio-temporal dynamics.

The invention is illustrated by drawings. The figure 1 shows a structural diagram of a hydro-acoustic monitoring system that implements the claimed method of acoustic tomography of hydrophysical and geophysical fields of the marine environment with the representation of the spatio-temporal characteristics of their spectra in the format of 2D and (or) 3D.

In figures 2 and 3 shows the test results of the method of acoustic tomography of geophysical (seismic) fields. The spatio-temporal characteristics of the spectra of the seismic background (Fig. 2), as well as a strong earthquake (Fig. 3) in 3D format are presented. Signals recorded on the coast of. Sakhalin, the place of origin is the Kuril ridge, a distance of about 500 km, 2014. Figures 4 and 5 show the results of tests of an acoustic tomography method for the hydrophysical (acoustic and hydrodynamic) fields of a marine vessel with representation and spectral characteristics in 2D format. The tests were carried out on routes with a length of 45 km (Fig. 4) and 310 km (Fig. 5).

In FIG. 6a and 6b show the test results of a method for acoustic tomography of the electromagnetic field of a marine vessel, implemented by the method of nonlinear translucent hydroacoustics on a route length of 45 km, with the representation of the spatio-temporal characteristics of the measured information field in 2D format. In FIG. 6a and 6b show the spectrogram and the spectrum of the electromagnetic field of the ship in 2D format, the recordings were made on the 45 km long Bering Sea light path. In FIG. Figures 7a and b show the spectrogram and spectrum of electromagnetic and acoustic (shaft-lobed) radiations of a marine vessel (in 2D format) on a 30 km long light path (Kamchatka, Avacha Bay). In FIG. Figures 8 and 9 show spectrograms of the seismic background and strong earthquake (in 3D format) that took place in the Kuril ridge in 2013. Registration of signals on the sea field about. Sakhalin. In FIG. 10 shows a spatio-temporal picture of discrete spectrum components of a noise poly marine vessel in 2D format. Parametric measurements were performed in the transition zone of the Sea of Okhotsk and the Sea of Japan on a 345 km long route. The spectrogram shows discrete resonant vibrations of the hull and their VLF modulation by vibrations as a whole, in the steady state mode of motion.

To implement the claimed method, a hardware complex is required that contains a path for generating and amplifying low-frequency translucent signals of stable frequency 1, equipped with a radiating unit (acoustic transducer) 2 that radiates translucent signals at a frequency of tens to hundreds of hertz. The receiving path of the system 5, connected to a linear discrete antenna 4, provides reception and analysis of nonlinearly transformed luminal signals and the selection of signs of informational hydrophysical and geophysical fields from them.

As sources of information waves 3a and 3b were used: acoustic, electromagnetic and hydrodynamic radiation of marine vessels, as well as waves of seismic processes and phenomena.

Structurally, the path for generating and amplifying acoustic pump signals 1 is an electronic circuit containing a stabilized frequency generator 6, a power amplifier of emitted luminal signals 7, and an output matching unit with cable 8 and then with an underwater unit (acoustic transducer) 2 (see Fig. 1) .

Structurally, the path of reception and analysis of translucent signals, the extraction and registration of information waves 5 is an electronic circuit including: a multi-channel preamplifier 4a (receiving discrete antenna 4), the inputs of which are connected via multi-wire submarine cable (preferably optical fiber) to the inputs of multi-channel block 9 frequency -temporal conversion of signals to the high-frequency region, then with the inputs of the channel switching unit and the formation of a continuous signal 10, the output of which dinene with the input of the broadband amplifier of the translucent signal 11, and its output is connected to the input of the narrowband analysis unit of the spectra of 12 received signals, which provides the measurement of the spectra and the formation of the spatio-temporal characteristics of the spectra of information waves in the 2D and (or) 3D format, as well as functionally associated with it the registrar of the formed characteristics of the spectra 13, while the narrow-band analysis of the spectra 12 is functionally connected with the switching unit of the receiving channels and the formation of a continuous signal 10. Cro Moreover, the drawing shows: the region of nonlinear interaction and parametric transformation of the luminal and information waves 14, the seabed 15, the marine environment 16, the sea surface 17.

The claimed method is implemented as follows.

The emitter of acoustic transmissive acoustic signals 2 and the linear receiving antenna 4 are placed at opposite boundaries of the controlled medium and set them on the horizons, taking into account the patterns of wave propagation in an extended sonar channel. In this case, an extended linear antenna is placed in the direction of the radiating unit and held at a predetermined horizon using buoys and anchors. This ensures the effective formation and use of the region of interaction between the luminal and information waves on the luminal path.

The work of sources of information waves 3a 3b on the line of radiation - reception of translucent signals leads to a change in the mechanical characteristics of the conductive liquid (density, and (or) temperature, and (or) heat capacity, etc.), which, depending on their physical nature, change the phase the speed of the luminal signals, which leads to their amplitude-phase modulation. The spectrum of an elastic wave changes; low-frequency and high-frequency harmonics appear in it. Harmonics arising as a result of nonlinear interaction of waves manifest themselves as modulation components of the amplitude and phase of the lumen. The modulation components of information waves are an inextricably linked component of the lumen wave, as a result of which they are transported over long distances and then are allocated (detected) in the blocks of the receiving path of the monitoring system.

By technical solutions of the proposed method, practical ways have been developed and confirmed by sea trials to build a system for monitoring the hydrophysical and geophysical fields of objects and the marine environment, as well as monitoring and controlling their amplitude-phase structure and spatial-temporal dynamics using acoustic tomography. Information fields of various physical nature, formed by objects and the environment, are measured by nonlinear translucent hydroacoustic technology, then their spectra are formed, which are presented in 2D and 3D. The method provides monitoring of the spatio-temporal characteristics of information fields in the sound and fractional frequency ranges in marine areas with a length of tens to hundreds of kilometers.

The length of the acoustic tomography system under consideration (a large scale of the range of parametric wave reception) is provided by sounding (pumping) the medium with low-frequency translucent signals in the frequency range of tens to hundreds of hertz, which is realized by existing radio-acoustic means.

The main features of the technical effect of the claimed invention are as follows.

The ability to monitor information fields by low-frequency acoustic tomography technologies has been achieved, providing a measurement of the spectrum of their amplitude-phase characteristics and the presentation of their spatial-temporal dynamics in the 2D and (or) 3D format.

The possibility of distant parametric reception of informational hydrophysical and geophysical waves by the method of transverse acoustic tomography is achieved by forming an extended volume of the working area of their nonlinear interaction and parametric transformation in the marine environment, which is realized due to the formation of a luminous parametric antenna along a controlled path.

Using in the receiving path of the measuring system the conversion of the time scale of the received luminal signals to the high-frequency region increases the concentration of their energy (in accordance with the scale of the time conversion), which, in turn, ensures the efficient separation of information waves in a wide frequency range, including existing means narrowband spectral analysis.

The developed method of acoustic tomography and its technology provide the creation and reliable implementation of the low-frequency translucent parametric system of long-distance measurement and integrated monitoring of the hydrophysical and geophysical fields of objects and the environment of various physical nature of the low-frequency, infrasound and fractional frequency ranges with the possibility of measuring amplitude-phase characteristics and controlling their spatial- time dynamics.

The measuring technology of the presented method and the models of the luminaire systems implementing it have passed sea tests in the regions of the Far Eastern seas and have proved their effectiveness.

Claims (5)

1. The method of acoustic tomography of hydrophysical and geophysical fields in the marine environment, including the placement of the emitting and receiving units of the monitoring system at opposite edges of the controlled area, sounding it with low-frequency transmissive signals of a stable frequency and forming in it a working zone of nonlinear interaction and parametric conversion of the luminal and measured information waves, reception, amplification, spectral analysis and separation in the spectra of the upper and (or) lower side bands, dividing into them, taking into account the time and parametric transformation of the initial characteristics of the measured information waves, characterized in that the receiving unit of the measuring system is formed as a discrete linear antenna consisting of n acoustic elements (hydrophones) horizontally placed in the direction of the emitting unit, while the signals of each receiving the antenna element is pre-amplified and transmitted through the multicore cable to the receiving path of the system into a time-frequency conversion unit of their scale to the high-frequency region, then to the block for switching the receiving channels and generating a continuous total signal, in which the signals from the 1st to the nth elements are continuously and cyclically switched and summed sequentially on each cycle, the generated total signals are further amplified, their narrow-band spectra are measured, they identify the upper and (or) lower side bands that form and represent in the 2D and (or) 3D format, register and, taking into account the time-frequency and parametric transformations, determine the information in them nnye signs of hydro and geophysical fields and their spatial and temporal dynamics. 2. The method according to p. 1, characterized in that the number of receiving elements n in the linear discrete antenna is set in the amount of 10 products, and the distance between them is half the length of the translucent acoustic wave. 3. The method according to p. 1, characterized in that the number of antenna elements n corresponds to the scale of the time-frequency conversion of the received translucent signals. 4. The method according to p. 1, characterized in that the operations of forming the spectra of the measured fields in the 2D and (or) 3D format synchronize with the cyclic switching mode of the receiving channels and the formation of a continuous signal. 5. The method according to p. 1, characterized in that the controlled environment is voiced by transparent acoustic signals of a stable frequency in the range of tens to hundreds of hertz.

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