The search and determination of the amount of biological resources is an urgent task, both from the point of view of food security of the Russian Federation and from the point of view of ecology. Most of the biological resources in the ocean are concentrated in shallow water zones (at depths from 1 to 200 m). The paper presents the results of the development of a parametric traverse survey sonar for searching for biological resources in shallow water. The calculation of the energy range of the parametric traverse sonar is given. The full-scale sea tests of the developed model of the traverse survey sonar in the Taganrog Bay of the Sea of Azov (shallow water conditions) are given. The average depth of the landfill was 2.2 meters. The oscillogram of the echogram recording line when determining the maximum detection range of a target in shallow water (reflected signal from a target at a distance of 1100 m) and an echogram from a target that moves away from the traverse sonar antenna at a distance of up to 800 m are given. Conclusions are drawn about the prospects of using parametric traverse-view sonars to search for fish aggregations in shallow water.

Keywords: traverse survey, parametric sonar, search for biological resources, shallow water, energy range

The method of local positioning of underwater vehicles by hydroacoustic system with linearly-frequency-modulated probing signals is considered. The method is based on measuring the range to the object and calculating the angles of arrival of echo signals on two or more spaced antennas. To increase energy and noise immunity signals with linear frequency modulation (LFM) are used. The scheme of towing an underwater vehicle with an acoustic beacon and the location of a hydroacoustic interferometer with two receiving antennas on a towing vessel are presented. The possibility of practical use of this method for high-precision measurement of the spatial position of an underwater towed or Autonomous vehicle relative to a surface vessel and, accordingly, the possibility of geographical reference of acoustic images and sea-bottom profilograms obtained by an underwater vehicle is experimentally shown. The results of full-scale tests of the experimental positioning system for its testing in the coastal zone of a small pond are presented. The block diagram of the local positioning equipment is presented. Examples of experimental distributions of the power module of echoes over the range are given for correlation processing of the acoustic beacon LFM signals. The paper also proposes the use of narrow-band traverse broadband parametric systems for communication between Autonomous unmanned underwater vehicles (ANPA) moving "in a flock". Describes the main specifications of the system and the experimentally measured in hydroacoustic basin of the directivity pattern of the antenna at the average rate of pumping and difference frequencies. The features of signal propagation in shallow sea are presented.

Keywords: hydroacoustic systems, side-view interferometric sonar, local positioning systems, parametric antenna, data transmission system, broadband antenna

This paper discusses the features of the construction of broadband sonar antennas, intended for environmental monitoring of the aquatic environment, and bottom sediment. The aim of this work is the research and development of broadband antennas sonar systems for environmental monitoring of water environment and the bottom sediment. The goal is achieved by solving two problems: - the application of broadband by its nature, parametric radiating antenna, the principle of which is based on nonlinear interaction of pump waves in the propagation medium; - the application of different frequency transducers to produce the desired band frequency characteristics. The results of studies of broadband antennas illustrate the possibility of constructing broadband signals. The characteristics of broadband parametric sonar antennas, whose operation is based on using the effect of nonlinear interaction of acoustic waves. The results of experimental research of amplitude-frequency characteristics of the broadband parametric antennas. Special attention is paid to the possibility of building broadband hydroacoustic antenna consisting of different frequency converters, mechanical related field. For example, calculations of impedance characteristics of such antennas. Calculated frequency dependence of the active component of the impedance of the antenna and the directivity. In conclusion, the conclusion that the use of different frequency converters allows not only to solve the problem of constructing a broadband antenna systems transmit information to underwater vehicles, but also to provide approximately the same antenna directivity in a wide frequency range. Presents images of the bottom and benthic structures, obtained by using models of parametric profilograph and ultra-wideband sonar.

Keywords: broadband signal; ultra broadband signal; hydroacoustic monitoring; information transfer; parametric hydroacoustic antenna; different frequency converters

The bulk of the pollutants accumulate in marine sediments. Hence the importance of the problem of the continuous monitoring of the state of the bottom and the bottom of sedimentary structures of inland waters and seas. The paper presents a method of remote sensing bottom soil to determine the speed of sound in the bottom ground. The proposed method allows to carry out measurements at the joint location of the emitter and receiver. The proposed method is a method of beam parameter. For measurements by the method of beam parameter must either have extended the receiving antenna system capable to determine the direction of arrival of the reflected acoustic signals from the bottom with a simple omnidirectional radiator or emit highly directional sound source and relatively easy to take an extended receiving antenna. Using parametric array can be formed acoustic beam width several degrees. This beam width is sufficient to implement the method of beam parameter. The authors have proposed an approximate method of beam parameter allows you to combine the location of the transmitter and the receiver, thus greatly simplifying the receiving antenna. To test the adequacy of the method was carried out modeling and experimental studies. In the simulation, the real parameters laid marine bottom of the layered structure and foster and radiating systems. As a result of the simulation were defined the limits of applicability of the proposed method in the study of marine soils. To determine the velocity of sound in the sea bed sediments with acceptable accuracy must emit acoustic signals at an angle less than 10 degrees. Experimental studies in acoustic basin showed qualitative agreement with the theoretical findings.

Keywords: remote sensing acoustic, classification of marine sediments, parametric profiler

We study the problems in the propagation of acoustic waves of a sound range near the boundaries of media. The features of the wave processes occurring at the water-air interface, due to the influence of inhomogeneous waves. Considered in detail the properties and parameters of an inhomogeneous plane wave. The mathematical calculations of the transmission coefficients L.M. Brekhovskikh for spherical and cylindrical waves through this boundary, allowing to take into account the contribution of inhomogeneous components. It is shown that than the frequency of radiation of a source is lower and the closer it is located to water-air interface, the acoustic transparency of this border is higher. Study of the dependence of the transmission coefficient of the water-air interface at low frequencies can have important consequences in a number of fundamental and applied problems. Increase the transparency of the interface requires a reassessment of the feasibility of acoustic communication from water in the air, the detection of underwater sources without dipping into the water and acoustic monitoring of the physical processes occurring in the water.

Keywords: Inhomogeneous plane wave, water-air interface, transmission coefficient, wavelength, spherical wave, acoustic impedance.

  This paper discusses the problem of controlling the characteristics of sonar multibeam receiver antennas. Hydro acoustic means, such as side-scan sonar, profiler, sonar, multibeam sonar, are used extensively for remote determination of the parameters of media for environmental management. In the article the technique of controlling the phase-frequency characteristics of the receiving antennas multibeam echoes sounders. The study method allows the measurement of the phase-frequency characteristics of antennas in a hydro acoustic tank which size is less than length of a near field of the reception aerial.

Keywords: Conservancy, multibeam echo-sounder, seabed research, underwater acoustic

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