Bottom sediments (UP to) are media in which both longitudinal and shear acoustic vibrations can be present. The presence of several velocity components in bottom sediments makes it possible to excite various types of waves, both longitudinal and shear. In this paper, methods of excitation, generation and reception of difference frequency shear waves (RF) created by parametric systems in (DO) in location modes are analyzed. The analysis of their work in the DO is presented, and their comparative characteristics are given in comparison with the excitation, formation and propagation of the field of longitudinal RFCs in the DO. Prerequisites are given for the creation of a parametric profiler working using the method of excitation, generation and location of shear waves in a complex multiphase medium ""water-DO"". A block diagram is presented and the principle of operation of a parametric profiler on shear waves is described. The advantages and disadvantages of this method of location are shown. The conclusion is made about the possibility of creating and ration.

Keywords: parametric antenna, bottom sediments, shear waves, difference frequency waves, parametric profilogaf

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

Hydroacoustic parametric monitoring and communication systems are considered. Brief description developed at the Department electrohydroacoustical and medical technology, Institute of nanotechnologies, electronics and instrumentation, southern Federal University (Agaimt INAP SFU) is the most promising sonar systems with parametric emitting antenna. Presented appearance and radiation pattern (days) of various embodiments of converters pumping parametricheskikh antennas of small-sized profiling. The design of composite Converter and parametric pumping days seysmoprofilografa. The description of the parametric side-view sonar and traverse-view sonar is given. In addition, parametric systems of hydroacoustic communication and monitoring of the sea on long routes are considered.

Keywords: hydroacoustic parametric system, parametric antenna, data transmission system, broadband antenna, water area monitoring, parametric profilograph. parametric navigation system, traversy overview

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

Acoustic system parameters were selected and calculated: wave modes used when controlling, wave entry and frequency angles according to kind of decay process and ultrasonic attenuation. Control procedure was developed

Keywords: ultrozvuk, frequency, attenuation process, technology, acoustic system

This paper shows the results of the experimental research the passage of the ultrasonic beam through modifiable layered structure in order to obtain data on changes in levels of pressure in the front slice of the acoustic field. This paper presents the spatial distribution characteristics of the acoustic field after passing the various layers in the liquid. Celebrated not only offset the propagation path, but also change the chart pressure in the front slice on the amplitude level , the width of the chart, the position of the lateral lobe and its amplitude.

Keywords: Ultrasound, layered medium, experimental assembly, refraction.

The paper gives the definition of reversibility, which can be used in the theory of linear circuits. To determine the conditions of the processes in reverse sequence selected linear second order circuit containing two reactive elements L and C. For a linear circuit at the time of switching current (or voltage ) can be written as the sum of two components : compulsory and free. Conditions for reversibility constrained component current (or voltage ) can be obtained a corresponding change of parameters independent sources of electrical energy. For a free component of the reversibility of the process can be achieved by changing the signs of the circuit elements in such a way that the signs of the roots of the characteristic equation is reversed . This switching can be realized if all the resistors in the multipole synthesized based on analog - digital-analog elements.

Keywords: A reversible process, electrical circuit, current, switching, multipole, input impedance, the characteristic equation

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.

Solution for high-speed video transmission in hydroacoustic channel by amplitude modulation with orthogonal subcarriers is specified. Results of method experimental check are presented. Discussed method is doppler-tolerant and can be realized in many common DSPs.

Keywords: hydroacousitcs, video transmission, amplitude modulation

Information about authors of issue №4 (2013)

Keywords: authors

The article gets application multi-element piezoelectric transducers for ultrasonic high-speed flaw  detection on railway tracks. The processing algorithm of echo-signals from multi-element piezoelectric transducers was offered to get additional information about defect location to apply solution considering risk level more validly and to increase crack detection probability. The obtained algorithm was realized as software package. A set of experiments was completed for fourth-elements inclined piezoelectric transducer on a standard pattern for various positions to verify the processing algorithm. The experiment has shown that the echo-signals behavior allows to use the obtained algorithm for multi-element transducers at the high-speed flaw detection. Also it has emerged that the echo-signal shape at one element of piezoelectric transducer strongly depends on refracting prism geometry and relation position elements on prism.

Keywords: multielement piezoelectric transducers; ultrasonic methods; echo-signal; high-speed flaw detection

  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

Information about authors of issue №4 p.1 (2012)

Keywords: authors