The Navy will purchase hydroacoustic complexes of the Mallard family. Pl hydroacoustic systems in anti-submarine warfare Features of the propagation of acoustic waves in water
Russian underwater hydroacoustics at the turn of the 21st century
Military hydroacoustics is an elite science, the development of which can only be afforded by a strong state
German ALEXANDROV
Possessing the highest scientific and technical potential (the company employs 13 doctors and more than 60 candidates of sciences), the concern develops the following priority areas of domestic hydroacoustics:
Multifunctional passive and active sonar systems (GAC) and systems (GAS) for illuminating the underwater environment in the ocean, including for submarines, surface ships, aircraft, detection systems for underwater swimmers;
Systems with flexible extended towed antennas for operation in a wide frequency range for surface ships and submarines, as well as stationary;
Active, passive and active-passive stationary hydroacoustic systems to protect the shelf zone from unauthorized entry by surface ships and submarines;
Hydroacoustic navigation and search and survey systems ";
Hydroacoustic transducers, antennas, phased antenna arrays of complex shapes with up to several thousand receiving channels;
Acoustic screens and sound-transparent fairings;
Information transmission systems via hydroacoustic channel;
adaptive systems for processing hydroacoustic information in a complex hydroacoustic and signal-jamming environment;
Target classifiers by their signatures and by the fine structure of the sound field;
Sound speed meters for surface ships and submarines.
The concern today is ten enterprises located in St. Petersburg and the Leningrad Region, Taganrog, Volgograd, Severodvinsk, the Republic of Karelia, including research institutes, factories for the serial production of hydroacoustic equipment, specialized enterprises for servicing equipment at facilities, training grounds. These are five thousand highly qualified specialists - engineers, workers, scientists, more than 25% of whom are young people.
The team of the enterprise has developed almost all serially produced SJSC pl ("Rubin", "Ocean", "Rubicon", "Skat", "Skat-BDRM", "Skat-3"), a number of hydroacoustic complexes and systems for surface ships ("Platina", "Polynom", station for detection of underwater swimmers "Pallada"), stationary systems "Liman", "Volkhov", "Agam", "Dniester".
The hydroacoustic complexes for submarines created by the enterprise are unique technical means, the creation of which requires the highest knowledge and vast experience in hydroacoustics. As one wit said, the task of detecting a submarine with a noise finder is similar in complexity to the task of detecting a candle flame at a distance of several kilometers on a bright sunny day, and nevertheless, for a submarine in a submerged position, the SAC is practically the only source of information about the environment. ... The main tasks solved by the submarine sonar system are the detection of submarines, surface ships, torpedoes in the noise direction finding mode, automatic tracking of targets, determining their coordinates, target classification, target detection and direction finding in sonar mode, intercepting sonar signals in a wide frequency range, providing sound underwater communications at long distances, providing an overview of the near situation and the safety of navigation, lighting the ice situation when sailing under the ice, providing mine and torpedo protection for the ship, solving navigation problems - measuring the speed, depth of the place, etc. In addition to these tasks, the complex must have a powerful automated control system, a system for monitoring its own noise, must continuously perform the most complex hydrological calculations to ensure the functioning of all systems and to predict the situation in the area of operations of the submarine. The complex has simulators for all systems of the hydroacoustic complex, providing training and training of personnel.
The basis of any hydroacoustic complex is antennas, phased discrete arrays of complex shape, consisting of piezoceramic transducers, which must ensure the reception of signals from the water environment on a boat experiencing enormous loads due to hydrostatic pressure. The task of the SAC is to detect these signals against the background of its own noise, flow noise when the boat is moving, sea noise interfering with targets, and a host of factors masking the useful signal.
A modern SAC is a complex digital complex that processes huge streams of information in real time (each antenna of the complex consists of thousands, or even tens of thousands of individual elements, each of which must be processed synchronously with all the others). Its operation is possible only when using the latest multiprocessor systems that provide the task of simultaneous, in space, and multiband, in frequency, observation of the surrounding acoustic fields.
The most important and most critical element of the complex is the devices for displaying the information received. When creating these devices, not only scientific and technical, but also ergonomic, psychological problems are solved - it is not enough to receive a signal from the external environment; the safety of the ship, and the movement of many targets, surface, submarine, air, representing a potential threat or interest to a submarine. And the developers are constantly balancing on the brink of the problem - on the one hand, display the maximum amount of information processed by the complex, and required by the operator on the other hand, do not violate the "Miller rule" limiting the amount of information that can be assimilated by a person at the same time.
An important feature of hydroacoustic systems, especially antennas, is the requirements for their strength, durability, the ability to work without repair or replacement for a very long time - in combat service, it is usually impossible to repair a sonar antenna.
A modern SAC cannot be considered as a self-sufficient, closed system, but only as an element of an integrated surveillance system, which receives and uses continuously updated a priori information about targets from non-acoustic detection systems, reconnaissance, etc., and outputs information about the changing underwater environment to the system analyzing tactical situations and making recommendations on the use of various modes of the SAC in this situation.
The development of sonar systems for a submarine is a continuous competition with the developers of a potential enemy, on the one hand, since the most important task of the SAC is to ensure at least parity in a duel situation (the enemy hears and recognizes you, and you him at the same distance), and it is necessary by all means and means to increase the range of the SAC, and mainly in a passive noise direction finding mode, which allows you to detect targets without revealing your own location, and with shipbuilders, submarine designers, on the other, since the noise of submarines decreases with each new generation, with each new project , even with each new ship built, and you need to detect a signal at a level lower by orders of magnitude than the surrounding noise of the sea. And it is obvious that the creation of a modern hydroacoustic complex for submarines of the XXI century is a joint work of the developers of the complex and the developers of the boat, jointly designing and placing the elements of the SAC on the ship in such a way that its work under these conditions is most effective.
The experience in the design of SJSC pl, available at our institute, allows us to highlight the main problem areas from which we can expect a significant increase in efficiency in the near future.
1. SAC with conformal and conformal-cover antenna
Reducing the noise level of the pl, associated with the efforts of the designers to optimize technical solutions designs of its body and mechanisms, led to a noticeable decrease in the range of the SAC on modern square. The increase in the aperture of traditional antennas (spherical or cylindrical) is limited by the geometry of the nose end of the housing. An obvious solution in this situation was the creation of a conformal (combined with the contours of the pl) antenna, the total area, and hence the energy potential of which significantly exceeds the analogous indicators for traditional antennas. The first experience in creating such antennas turned out to be quite successful.
An even more promising direction is the creation of conformal-integumentary antennas located along the side of the square. The length of such antennas can be tens of meters, and the area - more than a hundred square meters... The creation of such systems is associated with the need to resolve a number of technical problems.
The conformal-sheath antenna is located in the area of the predominant influence of inhomogeneous waves caused by structural interference, as well as interference of hydrodynamic origin, including that arising due to the excitation of the body by the incident flow. Acoustic screens, traditionally used to reduce the effect of interference on the antenna, are not effective enough in the low-frequency range of onboard antennas. Possible ways to ensure the effective operation of on-board antennas, judging by foreign experience, are, firstly, the constructive placement of the most noisy machines and mechanisms of the spacecraft in such a way that their effect on the on-board systems is minimal, and secondly, the use of algorithmic methods to reduce the effect of structural interference to the SAC path (adaptive methods for compensating for structural interference, including using vibration sensors located in the immediate vicinity of the antenna). The use of the so-called "vector-phase" methods of information processing seems to be very promising, which make it possible to increase the efficiency of the complex operation due to the joint processing of pressure and vibrational velocity fields. Another way to reduce the influence of hydrodynamic interference affecting the efficiency of conformal-sheath antennas is the use of film transducers (PVDF plates), which, due to averaging over an area of 1.0x0.5 m, significantly (judging by the data in the literature - up to 20 dB) the influence of hydrodynamic interference on the GAK tract.
2. Adaptive algorithms for processing hydroacoustic information, consistent with the propagation environment
“Adaptation” is traditionally understood as the ability of a system to change its parameters depending on changes in environmental conditions in order to maintain its efficiency. As applied to processing algorithms, the term "adaptation" means the alignment (in space and time) of the processing path with the characteristics of signals and interference. Adaptive algorithms are widely used in modern complexes, and their efficiency is determined mainly by the hardware resources of the complex. More modern are algorithms that take into account the space-time variability of the signal propagation channel. The use of such algorithms makes it possible to simultaneously solve the problems of detection, target designation and classification, using a priori information about the signal propagation channel. The source of such information can be adaptive dynamic oceanological models predicting with sufficient reliability the distributions of temperature, density, salinity and some other environmental parameters in the area of action of the square. Such models exist and are widely used abroad. The use of sufficiently reliable estimates of the parameters of the propagation channel allows, judging by theoretical estimates, to significantly increase the accuracy of determining the coordinates of the target.
3. Acoustic systems located on controlled unmanned underwater vehicles, critical tasks polystatic detection in active mode, as well as the tasks of searching for silted bottom objects
The submarine itself is a huge structure, more than a hundred meters long, and far from all the tasks the solution of which is necessary to ensure its own safety can be solved by placing hydroacoustic systems on the ship itself. One of these tasks is the detection of near-bottom and silted objects that pose a danger to the ship. To view an object, you need to approach it as close as possible, without creating threats to your own safety. One of the possible ways to solve this problem is to create a controlled underwater unmanned vehicle, placed on a submarine, capable of independently or by controlling via wire or underwater communication to approach the object of interest and classify it, and, if necessary, destroy it. In fact, the task is similar to the creation of the hydroacoustic complex itself, but miniature, having a battery propulsion unit, located on a small self-propelled device capable of undocking from a submarine in a submerged state, and then docking back, while providing constant two-way communication. In the United States, such devices have been created and are included in the armament of the latest generation submarines (of the Virginia class).
4. Development and creation of new materials for hydroacoustic transducers, which are less weight and cost
The piezoceramic transducers that make up submarine antennas are extremely complex structures, piezoelectric ceramics itself is a very fragile material, and it takes considerable effort to make it strong while maintaining efficiency. And for a long time there has been a search for a material that has the same properties of converting vibration energy into electrical energy, but which is a polymer, durable, lightweight, and technological.
Technological efforts abroad have led to the creation of polymer films of the PVDF type, which have a piezoelectric effect and are convenient for use in the design of cover antennas (placed on board a boat). The problem here is primarily in the technology of creating thick films that provide sufficient antenna efficiency. Even more promising seems to be the idea of creating a material with the properties of piezoelectric ceramics, on the one hand, and the properties protective screen, drowning out (or scattering) enemy sonar signals, and reducing the ship's own noises. Such material (piezoresin), applied to the submarine's hull, actually makes the entire hull of the ship a sonar antenna, providing a significant increase in the efficiency of sonar means. An analysis of foreign publications shows that in the United States such developments have already passed into the stage of prototypes, while in our country in recent decades there has been no progress in this direction.
5. Classification of goals
The task of classification in hydroacoustics is the most difficult problem associated with the need to determine the target class based on the information received in the noise direction finding mode (to a lesser extent, according to the active mode data). At first glance, the problem can be easily solved - it is enough to register the spectrum of a noisy object, compare it with the database, and get an answer - what kind of object it is, down to the name of the commander. In fact, the spectrum of the target depends on the speed of movement, the angle of the target, the spectrum observed by the hydroacoustic complex contains distortions due to the passage of the signal through a randomly inhomogeneous propagation channel (aquatic environment), which means it depends on the distance, weather, area of action and many other reasons that make the problem of spectrum recognition practically insoluble. Therefore, in the domestic classification, other approaches are used related to the analysis of characteristic features inherent in a particular class of goals. Another problem requiring serious scientific research, but urgently needed, is the classification of bottom and silted objects associated with the recognition of mines. It is known and confirmed experimentally that dolphins quite confidently recognize air- and water-filled objects made of metal, plastic, wood. The researchers' task is to develop methods and algorithms that implement the same procedure that a dolphin performs when solving a similar problem.
6. The task of self-defense
Self-defense is a complex task of ensuring the safety of a ship (including anti-torpedo protection), including detection, classification, target designation, and the issuance of initial data for the use of weapons and (or) technical means of countermeasures. The peculiarity of this task is the integrated use of data from various subsystems of the SAC, identification of data coming from various sources, and ensuring information interaction with other ship systems that ensure the use of weapons.
The above is only a small part of those promising areas of research that need to be addressed in order to increase the effectiveness of the hydroacoustic weapons being created. But from an idea to a product is a long way, requiring advanced technologies, a modern research and experimental base, a developed infrastructure for the production of the necessary materials for hydroacoustic transducers and antennas, etc. It should be noted that recent years have been characterized for our enterprise by a serious technical re-equipment of the production and testing base, which became possible thanks to funding within the framework of a number of federal target programs, both civil and special purpose, conducted by the Ministry of Industry and Trade of the Russian Federation. Thanks to this financial support, over the past five years, it was possible to completely repair and significantly modernize Europe's largest hydroacoustic experimental pool, located on the territory of Okeanpribor Concern, the most advanced instrument-making enterprise in the south of Russia. We are creating new productions - piezo materials, printed circuit boards, in the future - the construction of new production and scientific areas, stands for setting up and commissioning equipment. In 2 - 3 years, the production and scientific capacities of the enterprise, backed up by the "data bank" of new ideas and developments, will make it possible to start creating the fifth generation hydroacoustic weapons, which are so necessary for the Navy.
In the foreseeable future, submarines and anti-submarine aircraft of the Russian navy will have to receive a new type of sonar systems. According to the latest reports, by the end of the decade, the military department intends to acquire a large number of underwater surveillance equipment. Such purchases will make it possible to equip many submarines, aircraft, etc. under construction or modernization with modern means of detection.
At the end of March, a new order was placed on the official website of public procurement by the Ministry of Defense concerning further development the material part of the Navy. According to the published information on the tender, the ministry plans to purchase 55 hydroacoustic complexes (GAK) of the MGK-335EM-03 "Mallard" family in various modifications. For the purchase of all the required products, the military department is going to spend no more than 194.6 million rubles - an average of over 5.3 million for the complex. The first complexes within the framework of a future order should be delivered this year. Completion of deliveries is scheduled for 2019.
General scheme of the MGK-335EM-05 complex
According to the published data, the armed forces intend to purchase the Mallard complexes of three modifications, which will enable them to equip submarines, anti-submarine aircraft and stationary systems. 16 Kryakva-A complexes are being purchased for the submarine forces. The same number of systems should be received by naval aviation. 23 sets of the Mallard-V version will be purchased for hydroacoustic reconnaissance stations.
Applications for the tender are accepted until April 17. Shortly thereafter, a contract will be signed for the supply of the required products, after which their production will start. As already mentioned, the military department wants to receive the first hydroacoustic complexes of the required types this year.
According to available data, the MGK-335EM-03 Kryakva hydroacoustic complex was created by the Oceanpribor concern (St. Petersburg). This complex is designed for installation on ships of small and medium displacement. It is possible to install all the necessary equipment both during the construction of ships and during repair and modernization. In the latter case, the Mallard system is a replacement for the older MGK-355MS complex. According to reports, new modifications were created on the basis of the ship complex, intended for operation on other carriers. As a result, the SACs of the Mallard family can also be used by submarines, aircraft and stationary reconnaissance systems.
Regardless of the carrier, the complexes have similar tasks and are maximally unified. Their main task is to search for submarines. Targets are detected in active mode using echolocation or in passive mode - in this case, the intrinsic noises of targets are tracked. In addition, it is possible to detect signals from other complexes operating in active mode. Also, the "Mallard" automatic equipment is capable of independently tracking the found target and issuing target designation data to the carrier's anti-submarine defense fire control device. There is a possibility of automated classification of the detected object. Complexes MGK-335EM-03 "Mallard" have the function of hydroacoustic communication at low and high frequencies. It also provides for the use of code communication and identification.
Architecture of SJSC MGK-335EM-03
In order to improve operational characteristics, the complexes have a number of important features and functions. During the operation of the hydroacoustic complex, the level of acoustic interference is automatically monitored. Also, the automation is able to predict the expected range of the system, depending on the current conditions. There are automated tools for monitoring the operation of all components of the complex and tracking their condition. Automation independently monitors the operation of the units and makes diagnostics. If there is a problem with automatic mode their localization is carried out. Operator training is available using simulated targets.
In the basic configuration, intended for installation on surface ships, the MGK-335EM-03 "Mallard" SJC includes several main instruments that solve various problems. In this case, the main and only means of observing and detecting targets is a subtle active-passive antenna. It is made in the form of a cylindrical body equipped with a large number of sensitive elements. To maintain the required position of the antenna during operation, a special suspension system with stabilization devices is used. The antenna has a height of 1 m and a diameter of 1 m. There are 36 pillars with 12 elements on each around the circumference of the cylinder.
Also, a generator device, a receiving-amplifying and matching device, as well as devices for digital signal processing and control and stabilization control should be mounted on board the launch vehicle. All these elements of the complex are interconnected. Electricity is supplied to all components of the complex using a separate power supply device connected to general ship electrical systems.
At the operator's workplace of the complex, it is proposed to mount a console with all the necessary controls. Data on the underwater situation, detected targets and the operation of hydroacoustic equipment are displayed on two color monitors. The main controls are the keyboard and trackball located on the front console. Some of the buttons and switches are placed next to the monitors. The developer of the Mallard system also proposes the use of an external indicator. At some distance from the main console, an additional monitor can be installed, displaying information about the current situation.
Duck antenna "Mallard"
According to available data, the Mallard family includes hydroacoustic systems of several models, differing from each other in the composition of special equipment, primarily antennas and other detection means. So, in the MGK-335EM-01 project, the keel antenna is supplemented by a towed flexible extended antenna. The MGK-335EM-02 complex includes a towed emitting and flexible extended antenna. The MGK-335EM-04 product is distinguished by an extended frequency range when operating in active mode, which makes it possible to detect torpedoes, and the Mallard version of the MGK-335EM-05 version has a sinking receiving and transmitting antennas.
According to the official data of the Okeanpribor concern, the MGK-335EM-03 Mallard is capable of detecting a submarine with an equivalent radius of Re = 10 m at distances of up to 10-12 km. Target coordinates are determined with an accuracy of 30 'by bearing. Range accuracy reaches 1% of the distance scale. In the noise direction finding mode, the complex is capable of capturing sounds with a frequency of 1.5 to 7 kHz. After detecting the target and taking it for tracking, the bearing determination accuracy is 30 '. The hydroacoustic signal detection mode, which implies the detection of other people's SACs operating in an active mode, allows you to control the frequency range of 1.5-7 kHz. The bearing to the source of the detected signal is determined with an accuracy of 10 °.
By analyzing the nature of the received reflected or intercepted signals, the MGK-335EM-03 complex is able to determine the belonging of the detected object to one or another class of equipment. With some help from the operator, the sonar system is able to distinguish a submarine from a torpedo. At the same time, it is possible to simultaneously issue target designation to anti-submarine weapons systems.
Complex "Mallard" is distinguished by rather high characteristics of hydroacoustic communication, and also has some special capabilities. Low-frequency or high-frequency communication is carried out at ranges of up to 20 km. Code communication, identification of a detected object or changing the distance to it can be performed at distances up to 30 km. With the help of GAK MGK-335EM-03, the crew of the carrier ship can support telephone connection both with Russian submarines and with ships using the NATO frequency band.
Complex control panel
According to the latter, in 2017-19, the navy will have to receive 55 sets of the MGK-335EM-03 "Mallard" SAC family in different configurations, designed for mounting on carriers of various classes. Most of this equipment is planned to be installed at hydroacoustic reconnaissance stations, while other complexes will be used by submarines and aircraft. Accurate information about the future carriers of the ordered complexes, for obvious reasons, on this moment absent. So far, all that remains is to make forecasts and try to predict what kind of equipment will be equipped with such equipment.
In the case of anti-submarine aviation, the Il-38 and Tu-142 aircraft of the latest modifications can be considered as possible carriers of the new type of complexes. Now this technique is undergoing repairs and modernization, during which it receives various new equipment. In the next project for the renewal of equipment, the latest hydroacoustic systems can also be used.
16 complexes in the configuration for submarines will be purchased. Probably, this equipment will be used in the future repair of existing ships of relatively old projects. Given the age and equipment of the submarines in service, it can be assumed that any domestic nuclear and diesel-electric submarines of all existing projects... Not all ships of the Russian submarine forces are equipped with modern means of monitoring the underwater situation, which is why they need new similar products. As the repair progresses, they will be able to receive new devices with improved characteristics.
It is curious that in the conditions of the current tender there is no clause on the purchase of hydroacoustic systems intended for installation on surface ships. The MGK-335EM-03 product was originally developed precisely as a shipborne observation device and only then developed, as a result of which it could be installed on other carriers. For some not entirely understandable reasons, the military department's immediate plans for the purchase of ship-based SJSC "Mallard" are absent.
Scheme of the ship complex MGK-335EM-05 with an additional drop antenna
According to the domestic media, it is already known where the purchased hydroacoustic systems will go. The resulting products will be distributed by the Ministry of Defense among several formations of the navy and naval aviation responsible for the implementation of anti-submarine defense. The equipment will go to Kronstadt, Severomorsk and Novorossiysk, as well as to some bases in the Primorsky Territory. Other details of the future operation of promising systems have not yet been reported.
From the available data, it follows that equipping submarines, aircraft and stationary sonar systems with new complexes of the MGK-335EM-03 Mallard family will have positive consequences for the entire anti-submarine defense of the fleet as a whole. During the construction or modernization of submarines, aircraft, etc. will receive modern equipment for tracking underwater objects, which will accordingly affect the efficiency of their work. As a result, the range and probability of detecting potentially dangerous objects will noticeably increase.
In addition to the main tasks associated with the detection and tracking of various objects, the new SACs can be used to identify targets found, issue target designation to control systems, etc. A training regime is also provided to facilitate the training of hydroacoustic operators.
According to official data, in mid-April, the military department will finish accepting applications for the recently launched tender and will begin to select a supplier of the required equipment. Soon a supply agreement should appear, after which the serial production of the SJSC of the required modifications will begin. The first samples of such equipment are planned to be received this year, the last - no later than the end of 2019. Obviously, the supply of such products will be carried out simultaneously with the construction / modernization of their carriers. This means that no later than the beginning of the next decade, the domestic anti-submarine defense will receive new equipment, and with it new capabilities. All this will have a positive effect on the potential of the navy as a whole.
Based on materials from sites:
http://zakupki.gov.ru/
http://i-mash.ru/
http://oceanpribor.ru/
http://armsdata.net/
http://flot.com/
Russian underwater hydroacoustics at the turn of the 21st century
Military hydroacoustics is an elite science, the development of which can only be afforded by a strong state
German ALEXANDROV
Possessing the highest scientific and technical potential (the company employs 13 doctors and more than 60 candidates of sciences), the concern develops the following priority areas of domestic hydroacoustics:
Multifunctional passive and active sonar systems (GAC) and systems (GAS) for illuminating the underwater environment in the ocean, including for submarines, surface ships, aircraft, detection systems for underwater swimmers;
Systems with flexible extended towed antennas for operation in a wide frequency range for surface ships and submarines, as well as stationary;
Active, passive and active-passive stationary hydroacoustic systems to protect the shelf zone from unauthorized entry by surface ships and submarines;
Hydroacoustic navigation and search and survey systems ";
Hydroacoustic transducers, antennas, phased antenna arrays of complex shapes with up to several thousand receiving channels;
Acoustic screens and sound-transparent fairings;
Information transmission systems via hydroacoustic channel;
adaptive systems for processing hydroacoustic information in a complex hydroacoustic and signal-jamming environment;
Target classifiers by their signatures and by the fine structure of the sound field;
Sound speed meters for surface ships and submarines.
The concern today is ten enterprises located in St. Petersburg and the Leningrad Region, Taganrog, Volgograd, Severodvinsk, the Republic of Karelia, including research institutes, factories for the serial production of hydroacoustic equipment, specialized enterprises for servicing equipment at facilities, training grounds. These are five thousand highly qualified specialists - engineers, workers, scientists, more than 25% of whom are young people.
The company's team has developed almost all serially produced SJSC pl (Rubin, Ocean, Rubikon, Skat, Skat-BDRM, Skat-3), a number of sonar systems and systems for surface ships (Platina "," Polynom ", station of detection of underwater swimmers" Pallada "), stationary systems" Liman "," Volkhov "," Agam "," Dniester ".
The hydroacoustic complexes for submarines created by the enterprise are unique technical means, the creation of which requires the highest knowledge and vast experience in hydroacoustics. As one wit said, the task of detecting a submarine with a noise finder is similar in complexity to the task of detecting a candle flame at a distance of several kilometers on a bright sunny day, and nevertheless, for a submarine in a submerged position, the SAC is practically the only source of information about the environment. ... The main tasks solved by the submarine sonar system are the detection of submarines, surface ships, torpedoes in the noise direction finding mode, automatic tracking of targets, determining their coordinates, target classification, target detection and direction finding in sonar mode, intercepting sonar signals in a wide frequency range, providing sound underwater communications at long distances, providing an overview of the near situation and the safety of navigation, lighting the ice situation when sailing under the ice, providing mine and torpedo protection for the ship, solving navigation problems - measuring the speed, depth of the place, etc. In addition to these tasks, the complex must have a powerful automated control system, a system for monitoring its own noise, must continuously perform the most complex hydrological calculations to ensure the functioning of all systems and to predict the situation in the area of operations of the submarine. The complex has simulators for all systems of the hydroacoustic complex, providing training and training of personnel.
The basis of any hydroacoustic complex is antennas, phased discrete arrays of complex shape, consisting of piezoceramic transducers, which must ensure the reception of signals from the water environment on a boat experiencing enormous loads due to hydrostatic pressure. The task of the SAC is to detect these signals against the background of its own noise, flow noise when the boat is moving, sea noise interfering with targets, and a host of factors masking the useful signal.
A modern SAC is a complex digital complex that processes huge streams of information in real time (each antenna of the complex consists of thousands, or even tens of thousands of individual elements, each of which must be processed synchronously with all the others). Its operation is possible only when using the latest multiprocessor systems that provide the task of simultaneous, in space, and multiband, in frequency, observation of the surrounding acoustic fields.
The most important and most critical element of the complex is the devices for displaying the information received. When creating these devices, not only scientific and technical, but also ergonomic, psychological problems are solved - it is not enough to receive a signal from the external environment; the safety of the ship, and the movement of many targets, surface, submarine, air, representing a potential threat or interest to a submarine. And the developers are constantly balancing on the edge of the problem - on the one hand, to display the maximum amount of information processed by the complex and necessary for the operator, on the other hand, not to violate the "Miller rule" limiting the amount of information that can be mastered simultaneously by a person.
An important feature of hydroacoustic systems, especially antennas, is the requirements for their strength, durability, the ability to work without repair or replacement for a very long time - in combat service, it is usually impossible to repair a sonar antenna.
A modern SAC cannot be considered as a self-sufficient, closed system, but only as an element of an integrated surveillance system, which receives and uses continuously updated a priori information about targets from non-acoustic detection systems, reconnaissance, etc., and outputs information about the changing underwater environment to the system analyzing tactical situations and making recommendations on the use of various modes of the SAC in this situation.
The development of sonar systems for a submarine is a continuous competition with the developers of a potential enemy, on the one hand, since the most important task of the SAC is to ensure at least parity in a duel situation (the enemy hears and recognizes you, and you him at the same distance), and it is necessary by all means and means to increase the range of the SAC, and mainly in a passive noise direction finding mode, which allows you to detect targets without revealing your own location, and with shipbuilders, submarine designers, on the other, since the noise of submarines decreases with each new generation, with each new project , even with each new ship built, and you need to detect a signal at a level lower by orders of magnitude than the surrounding noise of the sea. And it is obvious that the creation of a modern hydroacoustic complex for submarines of the XXI century is a joint work of the developers of the complex and the developers of the boat, jointly designing and placing the elements of the SAC on the ship in such a way that its work under these conditions is most effective.
The experience in the design of SJSC pl, available at our institute, allows us to highlight the main problem areas from which we can expect a significant increase in efficiency in the near future.
1. SAC with conformal and conformal-cover antenna
The decrease in the noise level of the pl, associated with the efforts of the designers to optimize the technical solutions for the structures of its hull and mechanisms, led to a noticeable decrease in the range of the SAC on modern pl. The increase in the aperture of traditional antennas (spherical or cylindrical) is limited by the geometry of the nose end of the housing. An obvious solution in this situation was the creation of a conformal (combined with the contours of the pl) antenna, the total area, and hence the energy potential of which significantly exceeds the analogous indicators for traditional antennas. The first experience in creating such antennas turned out to be quite successful.
An even more promising direction is the creation of conformal-integumentary antennas located along the side of the square. The length of such antennas can be tens of meters, and the area is more than a hundred square meters. The creation of such systems is associated with the need to resolve a number of technical problems.
The conformal-sheath antenna is located in the area of the predominant influence of inhomogeneous waves caused by structural interference, as well as interference of hydrodynamic origin, including that arising due to the excitation of the body by the incident flow. Acoustic screens, traditionally used to reduce the effect of interference on the antenna, are not effective enough in the low-frequency range of onboard antennas. Possible ways to ensure the effective operation of on-board antennas, judging by foreign experience, are, firstly, the constructive placement of the most noisy machines and mechanisms of the spacecraft in such a way that their effect on the on-board systems is minimal, and secondly, the use of algorithmic methods to reduce the effect of structural interference to the SAC path (adaptive methods for compensating for structural interference, including using vibration sensors located in the immediate vicinity of the antenna). The use of the so-called "vector-phase" methods of information processing seems to be very promising, which make it possible to increase the efficiency of the complex operation due to the joint processing of pressure and vibrational velocity fields. Another way to reduce the influence of hydrodynamic interference affecting the efficiency of conformal-sheath antennas is the use of film transducers (PVDF plates), which, due to averaging over an area of 1.0x0.5 m, significantly (judging by the data in the literature - up to 20 dB) the influence of hydrodynamic interference on the GAK tract.
2. Adaptive algorithms for processing hydroacoustic information, consistent with the propagation environment
“Adaptation” is traditionally understood as the ability of a system to change its parameters depending on changes in environmental conditions in order to maintain its efficiency. As applied to processing algorithms, the term "adaptation" means the alignment (in space and time) of the processing path with the characteristics of signals and interference. Adaptive algorithms are widely used in modern complexes, and their efficiency is determined mainly by the hardware resources of the complex. More modern are algorithms that take into account the space-time variability of the signal propagation channel. The use of such algorithms makes it possible to simultaneously solve the problems of detection, target designation and classification, using a priori information about the signal propagation channel. The source of such information can be adaptive dynamic oceanological models predicting with sufficient reliability the distributions of temperature, density, salinity and some other environmental parameters in the area of action of the square. Such models exist and are widely used abroad. The use of sufficiently reliable estimates of the parameters of the propagation channel allows, judging by theoretical estimates, to significantly increase the accuracy of determining the coordinates of the target.
3. Acoustic systems located on controlled unmanned underwater vehicles, solving problems of polystatic detection in an active mode, as well as the problem of searching for silted bottom objects
The submarine itself is a huge structure, more than a hundred meters long, and far from all the tasks the solution of which is necessary to ensure its own safety can be solved by placing hydroacoustic systems on the ship itself. One of these tasks is the detection of near-bottom and silted objects that pose a danger to the ship. To view an object, you need to approach it as close as possible, without creating threats to your own safety. One of the possible ways to solve this problem is to create a controlled underwater unmanned vehicle, placed on a submarine, capable of independently or by controlling via wire or underwater communication to approach the object of interest and classify it, and, if necessary, destroy it. In fact, the task is similar to the creation of the hydroacoustic complex itself, but miniature, having a battery propulsion unit, located on a small self-propelled device capable of undocking from a submarine in a submerged state, and then docking back, while providing constant two-way communication. In the United States, such devices have been created and are included in the armament of the latest generation submarines (of the Virginia class).
4. Development and creation of new materials for hydroacoustic transducers, which are less weight and cost
The piezoceramic transducers that make up submarine antennas are extremely complex structures, piezoelectric ceramics itself is a very fragile material, and it takes considerable effort to make it strong while maintaining efficiency. And for a long time there has been a search for a material that has the same properties of converting vibration energy into electrical energy, but which is a polymer, durable, lightweight, and technological.
Technological efforts abroad have led to the creation of polymer films of the PVDF type, which have a piezoelectric effect and are convenient for use in the design of cover antennas (placed on board a boat). The problem here is primarily in the technology of creating thick films that provide sufficient antenna efficiency. Even more promising seems to be the idea of creating a material that has the properties of piezoelectric ceramics, on the one hand, and the properties of a protective screen, damping (or scattering) the enemy's sonar signals, and reducing the ship's own noises. Such material (piezoresin), applied to the submarine's hull, actually makes the entire hull of the ship a sonar antenna, providing a significant increase in the efficiency of sonar means. An analysis of foreign publications shows that in the United States such developments have already passed into the stage of prototypes, while in our country in recent decades there has been no progress in this direction.
5. Classification of goals
The task of classification in hydroacoustics is the most difficult problem associated with the need to determine the target class based on the information received in the noise direction finding mode (to a lesser extent, according to the active mode data). At first glance, the problem can be easily solved - it is enough to register the spectrum of a noisy object, compare it with the database, and get an answer - what kind of object it is, down to the name of the commander. In fact, the spectrum of the target depends on the speed of movement, the angle of the target, the spectrum observed by the hydroacoustic complex contains distortions due to the passage of the signal through a randomly inhomogeneous propagation channel (aquatic environment), which means it depends on the distance, weather, area of action and many other reasons that make the problem of spectrum recognition practically insoluble. Therefore, in the domestic classification, other approaches are used related to the analysis of characteristic features inherent in a particular class of goals. Another problem requiring serious scientific research, but urgently needed, is the classification of bottom and silted objects associated with the recognition of mines. It is known and confirmed experimentally that dolphins quite confidently recognize air- and water-filled objects made of metal, plastic, wood. The researchers' task is to develop methods and algorithms that implement the same procedure that a dolphin performs when solving a similar problem.
6. The task of self-defense
Self-defense is a complex task of ensuring the safety of a ship (including anti-torpedo protection), including detection, classification, target designation, and the issuance of initial data for the use of weapons and (or) technical means of countermeasures. The peculiarity of this task is the integrated use of data from various subsystems of the SAC, identification of data coming from various sources, and ensuring information interaction with other ship systems that ensure the use of weapons.
The above is only a small part of those promising areas of research that need to be addressed in order to increase the effectiveness of the hydroacoustic weapons being created. But from an idea to a product is a long way, requiring advanced technologies, a modern research and experimental base, a developed infrastructure for the production of the necessary materials for hydroacoustic transducers and antennas, etc. It should be noted that recent years have been characterized for our enterprise by a serious technical re-equipment of the production and testing base, which became possible thanks to funding within the framework of a number of federal target programs, both civil and special purpose, conducted by the Ministry of Industry and Trade of the Russian Federation. Thanks to this financial support, over the past five years, it was possible to completely repair and significantly modernize Europe's largest hydroacoustic experimental pool, located on the territory of Okeanpribor Concern, the most advanced instrument-making enterprise in the south of Russia. We are creating new productions - piezo materials, printed circuit boards, in the future - the construction of new production and scientific areas, stands for setting up and commissioning equipment. In 2 - 3 years, the production and scientific capacities of the enterprise, backed up by the "data bank" of new ideas and developments, will make it possible to start creating the fifth generation hydroacoustic weapons, which are so necessary for the Navy.
Hydroacoustics (from the Greek. hydor- water, akusticoc- auditory) - the science of phenomena occurring in the aquatic environment and associated with the propagation, emission and reception of acoustic waves. It includes the development and creation of hydroacoustic devices intended for use in the aquatic environment.
The history of development
Basics of hydroacoustics
Features of the propagation of acoustic waves in water
Components of the echo occurrence event.
The beginning of comprehensive and fundamental research on the propagation of acoustic waves in water was laid during the Second World War, which was dictated by the need to solve practical problems of the navies and, first of all, submarines. Experimental and theoretical work was continued in the post-war years and was summarized in a number of monographs. As a result of these works, some features of the propagation of acoustic waves in water were identified and refined: absorption, attenuation, reflection and refraction.
The absorption of the energy of an acoustic wave in seawater is caused by two processes: internal friction of the medium and the dissociation of salts dissolved in it. The first process converts the energy of an acoustic wave into heat, and the second, converting into chemical energy, removes the molecules from an equilibrium state, and they decay into ions. This type of absorption increases sharply with an increase in the frequency of the acoustic vibration. The presence of suspended particles, microorganisms and temperature anomalies in the water also leads to attenuation of the acoustic wave in the water. As a rule, these losses are small, and they are included in the total absorption, however, sometimes, as, for example, in the case of scattering from the trail of a ship, these losses can be up to 90%. The presence of temperature anomalies leads to the fact that the acoustic wave enters the acoustic shadow zones, where it can undergo multiple reflections.
The presence of water - air and water - bottom interfaces leads to the reflection of an acoustic wave from them, and if in the first case the acoustic wave is reflected completely, then in the second case the reflection coefficient depends on the bottom material: poorly reflects the muddy bottom, well - sandy and stony ... At shallow depths, due to multiple reflections of the acoustic wave between the bottom and the surface, an underwater sound channel appears, in which the acoustic wave can propagate over long distances. A change in the magnitude of the speed of sound at different depths leads to the curvature of sound "rays" - refraction.
Sound refraction (bending the path of the sound beam)
|
Refraction of sound in water: a - in summer; b - in winter; on the left - the change in speed with depth. The speed of sound propagation changes with depth, and the changes depend on the time of year and day, the depth of the reservoir, and a number of other reasons. Sound rays emanating from the source at a certain angle to the horizon are bent, and the direction of the bend depends on the distribution of sound velocities in the environment: in summer, when the upper layers are warmer than the lower ones, the rays bend downward and are mostly reflected from the bottom, losing a significant portion of their energy ; in winter, when the lower layers of the water retain their temperature, while the upper layers are cooled, the rays bend upward and repeatedly reflect from the water surface, while much less energy is lost. Therefore, in winter, the range of sound propagation is greater than in summer. The vertical distribution of the speed of sound (VDS) and the speed gradient have a decisive influence on the propagation of sound in the marine environment. The distribution of the speed of sound in different regions of the World Ocean is different and changes over time. There are several typical cases of HRVD: |
Scattering and absorption of sound by inhomogeneities of the medium.
Sound propagation in underwater sound. channel: a - change in the speed of sound with depth; b - path of rays in the sound channel. To spread sounds high frequency when the wavelengths are very small, small irregularities usually occurring in natural reservoirs are affected: gas bubbles, microorganisms, etc. These irregularities act in two ways: they absorb and dissipate the energy of sound waves. As a result, with an increase in the frequency of sound vibrations, the range of their propagation decreases. This effect is especially pronounced in the surface layer of water, where there are most inhomogeneities. Sound scattering by irregularities, as well as irregularities in the surface of the water and the bottom, causes the phenomenon underwater reverb accompanying the sending of a sound impulse: sound waves, reflecting from a set of inhomogeneities and merging, give a tightening of the sound impulse, continuing after its end. The limits of the propagation range of underwater sounds are also limited by the intrinsic noise of the sea, which has a double origin: some of the noise arises from the impacts of waves on the water surface, from the sea surf, from the noise of rolling pebbles, etc .; the other part is associated with marine fauna (sounds produced by aquatic organisms: fish and other marine animals). Biohydroacoustics deals with this very serious aspect. |
Sound wave propagation distance
The range of propagation of sound waves is a complex function of the radiation frequency, which is uniquely related to the wavelength of the acoustic signal. As you know, high-frequency acoustic signals are quickly attenuated due to strong absorption by the aqueous medium. Low-frequency signals, on the other hand, are capable of propagating over long distances in the aquatic environment. Thus, an acoustic signal with a frequency of 50 Hz can propagate in the ocean over distances of thousands of kilometers, while a signal with a frequency of 100 kHz, typical for side-looking sonar, has a propagation range of only 1-2 km. Approximate operating ranges of modern sonars with different acoustic signal frequency (wavelength) are given in the table:
Areas of use.
Hydroacoustics has received wide practical application, since an effective system for transmitting electromagnetic waves under water at any significant distance has not yet been created, and therefore sound is the only possible means of communication under water. For these purposes, they use sound frequencies from 300 to 10,000 Hz and ultrasounds from 10,000 Hz and above. Electrodynamic and piezoelectric emitters and hydrophones are used as emitters and receivers in the sound region, and piezoelectric and magnetostrictive in the ultrasonic region.
The most significant applications of hydroacoustics:
- To solve military problems;
- Marine navigation;
- Underwater communication;
- Fish exploration;
- Oceanological research;
- Areas of activity for the development of the riches of the bottom of the World Ocean;
- Using acoustics in the pool (at home or in a synchronized swimming training center)
- Training of marine animals.
Notes (edit)
Literature and sources of information
LITERATURE:
- V.V. Shuleikin Physics of the sea... - Moscow: "Science", 1968 .. - 1090 p.
- I.A. Romanian Basics of hydroacoustics... - Moscow: "Shipbuilding", 1979 - 105 p.
- Yu.A. Koryakin Hydroacoustic systems... - St. Petersburg: "Science of St. Petersburg and the sea power of Russia", 2002 .. - 416 p.
Alternatives to Replace Microsoft Office Visio Command Line Key
Mhotspot installation and setup Computer did not restart after installation
A tale of three buttons. Column by Evgeny Zobnin. We get customizable on-screen Home, Back and Menu buttons on any Android device (Floating Soft Keys) Assigning buttons on the phone