RU2727331C1 - Method for hydroacoustic search for an autonomous underwater bottom object - Google Patents

Abstract

FIELD: underwater navigation.SUBSTANCE: proposed invention relates to underwater navigation, namely to determination of autonomous bottom underwater object location by means of hydroacoustic navigation system, and can be used in hydroacoustic monitoring systems for various purposes, integrated underwater surveillance systems, positional network-centric systems for hydroacoustic search from underwater search vessel of underwater objects located at the bottom of known marine water area in sleep mode after corresponding mission.EFFECT: high stealthiness of hydroacoustic search from a surface search vessel of an autonomous bottom underwater object due to using hydroacoustic signals in the search process, masked for possible acoustic background noise of a known search water area – sounds of marine animals, fish, crustacea, sea noise, selection of appropriate structure, amplitude, time and frequency parameters of these hydroacoustic signals, implementation of corresponding actions for emission, reception and processing of hydroacoustic signals on search vessel and autonomous bottom underwater object.9 cl, 4 tbl, 14 dwg

Description

The proposed invention relates to the field of underwater navigation, namely to determining the location of an autonomous bottom underwater object by means of a hydroacoustic navigation system and can be used in hydroacoustic monitoring systems for various purposes, integrated underwater surveillance systems, positional network-centric systems for covert hydroacoustic search from a surface vessel of underwater objects, for example, an autonomous seabed monitoring station, an underwater reconnaissance robot, a multifunctional autonomous unmanned underwater vehicle located at the bottom of a known sea area in a dormant mode after completing a corresponding mission.

Known similar in functionality navigation method [1], where the investigated water area polygon is coordinated by three acoustic transponder beacons, with which the autonomous underwater object interacts, receiving a request and transmitting its acoustic signal, and the beacons transmit their distances to the underwater object to the search vessel. The ship calculates the coordinates of the object as the intersection point of the three spheres and refines them as the ship approaches the underwater object.

This method is rather cumbersome, requires a lot of ship time for deployment, is expensive to operate, and does not provide the secrecy of hydroacoustic search, since the signals of interaction of an autonomous underwater object, responder beacons and a search vessel are detected and identified by existing hydroacoustic observation and monitoring equipment, which is highly undesirable. circumstance in the performance of certain reconnaissance and monitoring tasks in various sea areas.

где h - глубина погружения подводного объекта. В этой системе также не обеспечивается скрытность, поскольку сигналы взаимодействия подводного объекта и надводного судна обнаруживаются и идентифицируются существующими гидроакустическими средствами наблюдения и мониторинга.Known hydroacoustic navigation system [2] with an ultrashort base for positioning underwater objects, in which the surface vessel is equipped with a four-element direction finding antenna of diametrically orthogonal geometry, and the requested underwater object transmits to the surface vessel a combined signal, in general, consisting of navigation and information units. Appropriate processing of this signal under conditions of large signal-to-noise ratios allows one to determine with sufficient accuracy the parameters of the location of an underwater object: bearing ϕ, elevation angle θ, range d, slope distance r _n relative to the surface vessel and receive the necessary information messages from the object. The specified location parameters are related to each other by the ratios:

where h is the immersion depth of the underwater object. In this system, secrecy is also not provided, since signals of interaction between the underwater object and the surface vessel are detected and identified by existing hydroacoustic observation and monitoring devices.

There is a method [3] for determining the location of an autonomous underwater vehicle equipped with a pinger beacon, emitting periodic tones, pre-synchronized with the ship's generator of similar reference signals, relative to the search vessel, the pinger beacon signals being received by the ship's antenna, calculating their time offset relative to of the same reference signals, multiplying which by the speed of sound in water, an oblique distance along the beam from the pinger beacon to the ship's antenna is obtained, at the same time using the ship's receiving antenna of the dipole type with a minimum radiation pattern and mechanically rotating it about the vertical axis, the bearing of the beacon is recorded. pinger of the autonomous bottom underwater vehicle relative to the ship coordinates by the minimum amplitude of the received signal, as well as using the ship's echo sounder, determine the depth of the water area under the ship, then from the geometric construction of the right-angled triangle calculate the projection the long distance to the horizontal bottom surface (range of the vehicle), which, together with the bearing angle, gives an estimate of the approximate coordinates of the autonomous bottom underwater vehicle relative to the search vessel, which are constantly updated as the vessel moves in the direction of the positioned underwater vehicle.

This method also has a disadvantage associated with the lack of secrecy of the process of hydroacoustic search for an autonomous bottom underwater object, due to the use and possible identification of unmasking, artificially originated acoustic signals, indicating, according to hydroacoustic reconnaissance data, the very fact of carrying out attention-grabbing underwater work.

Based on the features of the method [3], the navigation system [2] and obvious technical solutions, it is possible to formulate features that can be present both in the known and in the claimed methods:

- the search vessel is supplied with a receiving direction-finding and transmitting hydroacoustic antennas, equipment for receiving and processing the signal of the pinger beacon of an autonomous underwater bottom object, equipment for generating activation and ascent signals for an autonomous bottom underwater object, hydroacoustic means for measuring the depth of the search water area;

- an autonomous bottom underwater object is equipped with receiving and transmitting sonar antennas, a buoyancy change system, a pinger beacon that generates a short-term, repetitive navigation signal, and equipment for receiving and processing signals for activation and surfacing of a search vessel;

- the formation of the navigation signal of the autonomous bottom underwater object and its processing on the search vessel are carried out using highly stable reference generators;

- the transfer of an autonomous bottom underwater object from a sleeping mode to an operating mode is carried out by sending a hydroacoustic activation signal from a search vessel;

- the location of the autonomous bottom underwater object relative to the search vessel is estimated on the basis of hydroacoustic measurements of the depth of the search water area, determination of the inclined distance and distance between the search vessel and the autonomous bottom underwater object, the angular parameters of the object in the coordinate system of the direction finding antenna of the search vessel;

- the course of movement of the search vessel in the search process is adjusted as the estimates of the location of the autonomous bottom underwater object in the search water area are updated;

- ascent to the surface of an autonomous underwater object is carried out using a buoyancy change system, the actuators of which are launched by sending a hydroacoustic ascent signal from a search vessel.

The combination of the above features makes it possible to synthesize a prototype method, which assumes the following actions and operations in the process of hydroacoustic search for an autonomous bottom underwater object:

- installing on the surface search vessel a direction-finding sonar antenna of diametrically orthogonal geometry of placement of four receiving hydrophones, a weakly directional transmitting sonar antenna, equipment for receiving and processing the signal of a pinger beacon of an autonomous bottom underwater object based on a highly stable reference generator, equipment for generating activation signals and ascent of an autonomous bottom underwater object, hydroacoustic means for measuring the depth of the search water area;

- equip an autonomous bottom underwater object with weakly directional receiving and transmitting hydroacoustic antennas, equipment for generating a pinger beacon signal using a highly stable reference generator, equipment for receiving and processing activation signals and surfacing a search vessel;

- emit from the search vessel, as it moves through the search water area, into the aquatic environment of the lower hemisphere space, relative to the search vessel, a hydroacoustic activation signal of an autonomous bottom underwater object, exceeding the background noise of the water environment of the search water area;

- the hydroacoustic activation signal is received and processed at the autonomous bottom underwater object, the equipment of the autonomous bottom underwater object is transferred from sleeping to operating mode;

- using a highly stable reference generator on an autonomous bottom underwater object, a short-term, repeating with an interval longer than its duration, a navigation signal of a pinger beacon is formed, the frequency of which is known a priori on the search vessel;

- a generated pinger beacon signal is emitted by a hydroacoustic antenna of an autonomous underwater bottom object, in the directions of the upper hemisphere, relative to the seabed, which exceeds the background noise of the aquatic environment of the search area;

- the hydroacoustic signal of the pinger beacon of the autonomous bottom underwater object is received and processed on the search vessel, after which the emission of the activation signal from the search vessel is stopped;

- the depth of the search water area is measured with a ship echo sounder;

- the bearing and the elevation angle of the autonomous bottom underwater object relative to the search vessel are determined using the ship's four-element direction-finding antenna of diametrically-orthogonal geometry;

- by the calculated elevation angle and the measured depth of the water area of the search, the approximate values of the range and slope distance to the autonomous bottom underwater object are estimated using the corresponding trigonometric ratios;

- correcting the course of movement of the search vessel on the basis of the parameters of the location of the autonomous bottom underwater object relative to the search vessel, which are updated as it moves through the search water area to a predetermined safe ascent range of the autonomous bottom underwater object;

- emit from the search vessel, in the pause between the signals of the pinger beacon of the autonomous bottom underwater object, into the aquatic environment of the search area, in the space of the lower hemisphere, relative to the search vessel, a hydroacoustic signal of the ascent of the autonomous bottom underwater object exceeding the background noise of the aquatic environment of the search area;

- the hydroacoustic ascent signal is received and processed at the autonomous bottom underwater object, the corresponding actuators of the buoyancy change system are launched, and the emission of the pinger beacon signal is stopped.

The technical result of the proposed method is to increase the secrecy of hydroacoustic search from a surface search vessel of an autonomous bottom underwater object due to the use of hydroacoustic signals in the process of search actions, masked for possible acoustic background noises of the search water area - the sounds of sea animals, fish, crustaceans, sea noises, the choice of the appropriate structure , amplitude, time and frequency parameters of these hydroacoustic signals, the implementation of appropriate actions for the emission, reception and processing of hydroacoustic signals on a search vessel and an autonomous bottom underwater object.

This technical result is achieved due to the fact that in the method of hydroacoustic search from a surface search vessel of an autonomous bottom underwater object, which is in a dormant mode in a known sea area after completing a corresponding mission, which consists in equipping a search vessel with a direction finding antenna of diametrical-orthogonal geometry the location of four receiving hydrophones, a weakly directional transmitting hydroacoustic antenna, equipment for receiving and processing the signal of the pinger beacon of an autonomous underwater bottom object based on a highly stable reference generator, equipment for generating activation signals and ascent of an autonomous bottom underwater object, hydroacoustic means for measuring the depth of the search water area, equipped with an autonomous bottom underwater object with weakly directional receiving and transmitting hydroacoustic antennas, equipment for receiving and processing signals for activation and surfacing of a search vessel, m a pinger, forming, using a highly stable reference generator, a repetitive navigation signal, the frequency of which is a priori known on the search vessel, by a buoyancy change system, in the repeating, as the search vessel moves through the search water area, its radiation by a transmitting antenna into the aquatic environment of the lower hemisphere space , in relation to the search vessel, the hydroacoustic signal of activation of the autonomous bottom underwater object, exceeding the background noise of the aquatic environment of the search area, in reception by the receiving antenna and the necessary processing on the autonomous bottom underwater object of the sonar activation signal of the search vessel, in the translation of the equipment of the autonomous bottom underwater object, in fact reliable reception of the activation signal, from the sleeping mode to the operating mode, in the radiation of the transmitting antenna of the autonomous bottom underwater object into the aquatic environment of the search area, in the directions of the upper hemisphere, relative to the seabed, hydroacoustic a signal that exceeds the background noise of the aquatic environment, generated by a pinger beacon and repeated with an interval longer than its duration, in the reception of the hydroacoustic signal of the pinger beacon by the direction finding antenna of the search vessel and its corresponding processing, with subsequent termination, upon its reliable reception, of radiation transmitting antenna of a search vessel for a hydroacoustic signal of activation of an autonomous bottom underwater object, in measuring and storing the depth of the water area of a search by hydroacoustic means of measuring a search vessel, in determining and remembering the bearing and elevation angle of an autonomous bottom underwater object relative to a search vessel, in evaluating and storing at a certain elevation angle and the measured depth of the water area of the search for approximate values of the range and slope distance to the autonomous bottom underwater object using the corresponding trigonometric relations, in the correction of the course of movement search of the new vessel based on the updated parameters of the location of the autonomous bottom underwater object relative to the search vessel, as it moves through the search water area to a predetermined safe ascent range of the autonomous bottom underwater object, in the radiation of the transmitting antenna of the search vessel into the aquatic environment of the search area, in the space of the lower hemisphere, relative to the search vessel, in the pause between the signals of the pinger beacon of the autonomous bottom underwater object, the hydroacoustic signal of the ascent of the autonomous bottom underwater object exceeding the background noise of the aquatic environment, in the reception by the receiving antenna and the necessary processing on the autonomous bottom underwater object of the sonar ascent signal, in the termination, on the fact of reliable reception of the ascent signal, radiation by the transmitting antenna of the autonomous bottom underwater object of the hydroacoustic signal of the pinger beacon, in the launch of the corresponding actuators of the system for changing the luvosti of an autonomous underwater object, form and store when preparing a mission of an autonomous underwater object on an underwater object and a search vessel, signals emitted during the hydroacoustic search process: on an autonomous underwater object - signals of a pinger beacon, on a search vessel - activation and emergence signals of an autonomous bottom underwater object , having a given structure, amplitude, time and frequency parameters, by acoustic perception approaching the possible background noise of the known search water area, while the activation and surfacing signals of the search vessel consist of two components: the starting message and the identification message, the combined pinger beacon signal of the autonomous bottom of an underwater object contains four components: a starting message, an identification message, a navigation message in the form of a harmonic signal of a frequency known on the search vessel and a quasi-white noise masking the navigation message, the frequency parameters of which are selected based on and from the required accuracy of determining the angular coordinates of the autonomous bottom underwater object relative to the search vessel in the process of its hydroacoustic search, providing the necessary frequency band and the corresponding excess of the lower boundary frequency of its spectrum over the frequency of harmonic oscillations of the navigation message, the structure of the sounding pulses of the ship's echo sounder is modified so that acoustic perception the procedure for measuring the depth of the water area of the search corresponded to the possible hybrid noise background of the marine environment, in addition, the structure and parameters of the emitted signals of the pinger beacon of the autonomous bottom underwater object are a priori known on the search vessel, and the structure and parameters of the emitted signals of activation and surfacing of the search vessel are a priori known on the autonomous a bottom underwater object, before the search, the procedure for calibrating the amplifying paths of the direction finding antenna of the search vessel is performed, with the receipt and storage of calibration corrections, during the search process on the search vessel, a procedure for determining and memorizing the angular coordinates of the autonomous bottom underwater object relative to the search vessel is implemented, coordinated with the geometric parameters of the direction finding antenna and allowing positioning of the autonomous bottom underwater object relative to the search vessel with the required accuracy in conditions of low signal / noise ratios of the masked navigation signal ...

A significant difference of the proposed method is the use of hydroacoustic signals in the process of search actions, masked for possible acoustic background noise of the search water area - the sounds of sea animals, fish, crustaceans, sea noises, with the choice of their proper structure, amplitude, time and frequency parameters, the application of the procedure for determining the angular coordinates of the autonomous bottom underwater object, coordinated with the geometric parameters of the direction finding antenna of the search vessel, which, together with the procedure for calibrating the amplifying paths of the direction finding antenna of the search vessel, allows positioning of the autonomous bottom underwater object relative to the search vessel with the required accuracy in conditions of low signal-to-noise ratios of the masked navigation signal, which together makes it possible to increase the secrecy of the hydroacoustic search for an autonomous bottom underwater object.

The set of essential features of the proposed method has a causal relationship with the achieved technical result, from which it can be concluded that this technical solution is new, has an inventive step, since it does not explicitly follow from the existing level of technology, and is suitable for practical use.

The invention is illustrated by drawings.

FIG. 1 shows a simplified stylized structure of the activation signal of an autonomous bottom underwater object emitted from a search vessel to the investigated water area at the beginning of the search.

FIG. 2 shows a simplified stylized structure of the ascent signal of an autonomous bottom underwater object emitted from a search vessel into the investigated water area at the final stage of the search.

FIG. 3 shows a simplified stylized structure of the combined pinger beacon signal emitted into the investigated water area from an autonomous bottom underwater object during its search.

FIG. 4 explains the asynchronous mode of reception and transmission of signals from a search vessel and an autonomous bottom underwater object, which excludes the possibility of temporary overlap of the emitted and received signals.

FIG. 5 and FIG. 6 shows examples of fragments of sonograms of recordings of possible acoustic noises of the sea search area, intended for the formation of signals emitted during the search from a search vessel and an autonomous bottom underwater object.

FIG. 7 shows an example of a possible ensemble of four combined pinger beacon signals of an autonomous bottom underwater object, emitted into the investigated water area in the process of its search.

FIG. 8 and 9 show examples of enlarged structural diagrams of the equipment of a search vessel and an autonomous bottom underwater object.

FIG. 10 shows an example of the arrangement of four hydrophones of a ship's direction finding antenna of diametrically orthogonal geometry in a Cartesian coordinate system.

FIG. 11 shows a schematic variant of a possible design of a direction finding antenna of diametrically orthogonal geometry of a mine (well) run search vessel.

FIG. 12 explains the principle of determining the location of an autonomous bottom underwater object in the process of hydroacoustic search, where are indicated: 1 - search vessel; 2 - autonomous bottom underwater object; 3 - ship direction finding antenna; 4 - seabed; ϕ, θ are the bearing and elevation angle of the autonomous bottom underwater object, respectively; h - depth of the search area; d is the range of an autonomous underwater bottom object; r _n - the slope distance between the search vessel and the autonomous bottom underwater object.

FIG. 13 and FIG. 14 shows the dependences of the absolute errors in determining the angular coordinates of the autonomous bottom underwater object relative to the search vessel on the signal / masking noise ratio in the navigation message of the combined pinger beacon signal for the near and far zones of hydroacoustic search.

To carry out a covert hydroacoustic search, the following basic structural requirements are imposed on the signals emitted from a search vessel and an autonomous bottom underwater object into the search water area:

- the acoustic perception of the emitted signals should correspond to the possible acoustic noise background of the marine environment;

- the general structure of signals should ensure the possibility of implementing an asynchronous mode of receiving and transmitting signals from a search vessel and an autonomous bottom underwater object;

- strict repetition frequency should be excluded from the time cycles of the emitted signals;

- the emitted signals should have a structure that allows them to be differentiated against the background of fluctuation noise of the marine environment;

- the excess of the emitted signals over the background noise of the marine environment should be sufficient for their reliable reception.

The indicated structural requirements are satisfied by hydroacoustic signals of a pulsed nature, formed on the basis of the corresponding fragments of sonograms of records of marine animals, fish and crustaceans with an appropriate choice of their structure, amplitude, time and frequency parameters.

Let us consider in more detail the structural characteristics of the signals of the search vessel and the autonomous bottom underwater object, proposed for use in the process of covert hydroacoustic search.

The activation signal a (t) of the autonomous bottom underwater object (Fig. 1), emitted from the search vessel into the investigated water area with an interval T _A before the response of the pinger beacon of the autonomous bottom underwater object, has two components of the form

where q (t ₁ ) is the starting message of the activation signal; b (t ₂ ) - sending the activation signal identification; U _q is the amplitude of the starting message of the activation signal; U _b is the average amplitude of the pulses of the activation signal identification message; Δτ ₁ is the duration of the starting message of the activation signal; Δτ ₂ - duration of the activation signal identification message; T _A is the interval of the activation signal emission.

The ascent signal e (t) of the autonomous bottom underwater object (Fig. 2), emitted from the search vessel into the search water area after the surface vessel approaches the autonomous bottom underwater object at the safe distance of its ascent, has two structurally similar to the activation signal (1), which are:

where g (t ₁ ) - ascent signal starting message; j (t ₂ ) - ascent signal identification message; U _g is the amplitude of the ascent signal starting message; U _j - average pulse amplitude of the ascent signal identification message; Δτ ₃ - the duration of the ascent signal starting message; Δτ ₄ - duration of the ascent signal identification message.

Formed at intervals of repetition T _M combined signal z (t)-pinger beacon autonomous underwater object comprises a bottom in the frequency range ΔF _z four components (FIG. 3) and has the form

where y (t₁) - starting sending of the pinger beacon signal; s (t₂) - sending the identification of the pinger beacon signal; x (t₃) - harmonic navigation message of the pinger beacon; m (t₃) - quasi-white noise masking the harmonic navigation message of the pinger beacon signal; ƒ₀ - oscillation frequency of the harmonic navigation message of the pinger beacon signal; U_y - the amplitude of the starting signal of the pinger beacon; U_s - the average pulse amplitude of the pinger beacon identification message; U_x - the amplitude of the harmonic oscillations of the navigation message of the pinger beacon signal; ϕ_x - the initial phase of harmonic oscillations of the navigation message of the pinger beacon signal; Δτ_five - the duration of the starting message of the pinger beacon signal; Δτ₆ - the duration of the pinger beacon signal identification message; Δτ₇ - the duration of the harmonic navigation message and the masking noise of the pinger beacon signal; Δτ₈ - total duration of the pinger beacon signal; σ_m is the standard deviation of the quasi-white noise masking the harmonic navigation message of the pinger beacon signal.

The combined signal of the beacon-pinger z (t) of an autonomous underwater object after linear amplification, received by the hydrophones of the four-element hydroacoustic direction finding antenna of the search vessel, is characterized by the following ratios:

where μ ₁ , μ ₂ , μ ₃ , μ ₄ are the coefficients averaged over the frequency range ΔF _{z of the} signal z (t) of the pinger beacon of the autonomous bottom underwater object, caused by the attenuation of acoustic vibrations in the aquatic environment of the search area, the transfer characteristics of the corresponding hydrophones of the direction finding antenna and its line amplifiers; ϕ ₁ , ϕ ₂ , ϕ ₃ , ϕ ₄ - phase shifts of harmonic oscillations of the navigation message, introduced by the aquatic medium of signal propagation, the spatial separation of hydrophones of the direction finding antenna of the search vessel and its linear amplifiers; ξ (t) - background fluctuation noise in the water area of the search; σ _ξ is the standard deviation of the background noise.

Quadrature components Y ₁ (t) and Y ₂ (t) of the signal Y (t) of frequency ƒ ₀ with a large signal-to-noise ratio, formed on the basis of a highly stable ship reference generator and necessary for processing masked harmonic navigation messages of the pinger beacon of an autonomous bottom underwater object , are characterized as functionally related continuous harmonic oscillations:

where U ₀ , ϕ ₀ - amplitude and initial phase of oscillations.

The general structure of the activation signals a (t), ascent e (t) and the pinger beacon z (t) was selected from considerations of the implementation of the asynchronous mode of reception and transmission of signals (Fig. 4) of a search vessel and an autonomous bottom underwater object with the necessary distinction in conditions predominantly fluctuation noise of the marine environment of the search area.

Detailed structure of signals a (t), e (t), z (t) (starting messages q (t ₁ ), g (t ₁ ), у (t ₁ ) and identification messages b (t ₂ ), j (t ₂ ), s (t ₂ )) is aimed at using, as components of the indicated signals, pulse fragments of sonograms of recordings of sounds of sea animals, fish and crustaceans inherent in a known search area (provided they are recorded in advance) or archive recordings of sounds of other, similar in hydrology, marine territories.

When implementing the proposed method for the starting and identification messages, fragments of the sonogram of the recordings of the above sounds with a pronounced impulse character and an intra-impulse structure that are well distinguishable against the background of sea noise are selected.

The navigation message x (t ₃ ) of the combined signal z (t) of the pinger beacon is a harmonic signal of a given frequency and duration, masked by quasi-white noise m (t ₃ ), which is used as fragments of sonograms of recordings of shallow or deep sea noise, depending on the assumed depth of the search area.

The durations of the signals a (t), e (t), z (t) are selected taking into account four mutually contradictory requirements:

- large duty cycle (the ratio of the repetition interval to the duration) of the emitted signals - to reduce the acoustic signature of the search process for an autonomous bottom underwater object;

- sufficient duration of the emitted signals - to obtain them a good approximation to the acoustic noise background of the marine environment;

- limited duration of the emitted hydroacoustic signals - for an acceptable time to receive updated parameters of the location of the autonomous bottom underwater object during the movement of the search vessel, especially at the final stage of the search;

- sufficient duration of the harmonic navigation message of the combined pinger beacon signal masked by quasi-white noise of the same duration to determine with the required accuracy the angular coordinates of the autonomous bottom underwater object relative to the search vessel.

As an example of a balanced, compromise option, the following time parameters of the components of the emitted hydroacoustic signals used in the proposed method can be recommended:

- duration Δτ ₁ , Δτ ₃ , Δτ ₅ starting messages q (t ₁ ), g (t ₁ ), y (t ₁ ) of the emitted signals of the search vessel and the autonomous bottom underwater object - about 0.02 s;

- duration Δτ _{2 of the} identification message b (t ₂ ) of the search vessel activation signal - about 4 s;

- duration Δτ _{4 of the} identification message j (t ₂ ) of the surfacing vessel surfacing signal - about 3 s;

- the duration Δτ _{6 of the} identification message s (t ₂ ) of the combined signal of the beacon-pinger of the autonomous bottom underwater object is about 2 s;

- the duration Δτ _{7 of the} navigation message x (t ₃ ) and the masking noise m (t ₃ ) of the combined signal of the beacon-pinger of the autonomous bottom underwater object is within 0.1-0.2 s.

The requirement to exclude from the time cycles emitted during the search for hydroacoustic signals of a strict repetition rate is fulfilled by introducing the following structural and organizational components:

- random changes in the search for repetition intervals T _A , T _{M of the} hydroacoustic activation signals of the search vessel and the pinger beacon of the autonomous bottom underwater object;

- formation from fragments of sonograms of recordings of sounds of various sea animals, fish, crustacean ensembles of activation signals of a search vessel and combined signals of a pinger-beacon of an autonomous bottom underwater object with a different number of pulses at selected durations of identification messages and a random change in the order of emission of these signals during the search;

- the number of different activation signals in the ensemble, generated on the search vessel, and the number of pulses for the selected duration of the identification message for each signal of the ensemble are a priori known on the autonomous bottom underwater object;

- the number of different in the ensemble pinger beacon signals formed on the autonomous bottom underwater object, and the number of pulses at the selected duration of the identification message of each signal of the ensemble are a priori known on the search vessel.

To ensure in the search process an asynchronous transmission and reception mode (see Fig. 4), which excludes the overlap in time of the emitted and received hydroacoustic signals on the search vessel and the autonomous bottom underwater object, random intervals of repetition of the hydroacoustic activation signals T _{A of the} search vessel and the pinger beacon T _{M of an} autonomous bottom underwater object must be greater than the corresponding minimum permissible values T _A > T _{A min} , T _M > T _{M min} , which are selected using the following calculation ratios:

where Δτ ₂ is the duration of the identification message of the search vessel activation signal; Δτ ₄ is the duration of the identification message of the surfacing vessel surfacing; Δτ ₈ is the total duration of the pinger beacon signal of the autonomous bottom underwater object; c _min is the minimum possible speed of sound in seawater; r _{n max} is the predicted maximum possible slope distance from the search vessel to the autonomous bottom underwater object during their acoustic contact in the search water area.

So, for example, for the recommended above values of the duration of the emitted hydroacoustic signals Δτ ₂ = 4 s, Δτ ₄ = 3 s, Δτ ₈ = 2.2 s and values c _min = 1400 m / s, r _{n max} = 3000 m, randomly variable repetition intervals T _{A of the} hydroacoustic signals of the search vessel activation must be at least 17 s, and the repetition intervals T _{M of the} hydroacoustic signals of the pinger beacon of an autonomous bottom underwater object must be at least 8 s.

Recognition parcels from signal ensembles of a search vessel or a pinger-beacon of an autonomous bottom underwater object are considered to be reliably received if the number of impulses known a priori for the selected duration of the ensemble's parcels is accepted, taken from sonograms of recordings of sounds of one or more marine animals, fish or crustaceans, having a corresponding shape and intra-impulse structure to provide a possible acoustic noise background in the search area.

The composition and structure of sounding pulses of a ship echo sounder, based on the corresponding pulse fragments of sonograms of recordings of sounds of sea animals, fish, crustaceans, are modified in such a way that their number and intra-pulse color correspond to the possible hybrid noise background of the marine environment, and the pulse repetition intervals are set based on a priori known or assumed maximum depth of the search area. In addition, the number of echo sounder sounding pulses at a time interval equal to the ascent signal duration should not coincide with the total number of pulses in the ascent signal to exclude the possibility of receiving the echo sounder signal as an ascent signal on an autonomous bottom underwater object.

The ratios of the amplitudes of the signal components a (t), e (t), z (t) when they are formed from the fragments of the corresponding sonograms of the recordings of the sounds of marine animals, fish, crustaceans and sea noises, taking into account the main structural requirements for ensuring a possible noise background of the search area, necessary the distinction between the used pulse signals and their reliable reception under conditions of fluctuation noise of the marine environment is established on the basis of the following additional circumstances:

- when performing reliable reception with the integration of a sequence of pulses having significantly different durations, in order to obtain comparable levels of their envelopes, the amplitudes of short-duration pulses must be greater than the amplitudes of long-duration pulses;

- to ensure sufficient masking of the regular component (harmonic navigation message) in the pinger beacon signal of an autonomous bottom underwater object, the root-mean-square deviation of the quasi-white noise masking the harmonic navigation message should be much greater than the amplitude of the harmonic message.

Taking into account these circumstances, the following amplitude parameters of the components of the emitted hydroacoustic signals used in the claimed method are recommended:

- the excess of the amplitudes U _q , U _g , U _{y of the} starting signals of the activation signals, the surfacing of the search vessel and the pinger beacon of the autonomous bottom underwater object over the average amplitudes U _b , U _j , U _{s of the} pulses of the signals of the identification of these signals is about 15 dB;

- the excess of the standard deviation σ _{m of the} quasi-white noise masking the navigation message of the pinger beacon signal over the amplitude U _{x of the} harmonic oscillations of the message is about 20 dB.

- the excess of the standard deviation σ _{m of the} quasi-white noise masking the navigation message of the pinger beacon signal over the background noise σ _ξ of the search water area environment is about 30 dB.

The excess of the average amplitudes U _b , U _j , U _{s of the} pulses of the signals of the activation signals, the surfacing of the search vessel and the pinger beacon of the autonomous underwater object above the background noise σ _{ξ of} the search water area, sufficient for their reliable reception, should be within 20 dB. This parameter belongs to the category of a priori uncontrollable, since it largely depends on the acoustic power of signals emitted from objects of interaction, the frequency of pulses of identification parcels, background noise of the water area and the inclined distance from the search vessel to the autonomous bottom underwater object during their acoustic contact.

The characteristics of the receiving and transmitting equipment of the search vessel and the autonomous bottom underwater object, sufficient to obtain the specified parameters of the received signals, taking into account the possible energy of the hydroacoustic channel, are given when considering the technical implementation of the proposed method.

Spectral analysis of sonograms of recordings of sounds of sea animals, fish, crustaceans and sounds of the sea of various water areas, available to the authors of the proposed method, showed the following:

- pulse fragments of sonograms of records of sounds of sea animals, fish, crustaceans, which can be used to form the emitted signals of a search vessel and an autonomous bottom underwater object in the search process, have a predominant frequency range of oscillations from 100 Hz to 8 kHz;

- fragments of sonograms of recordings of shallow sea noises have a predominantly frequency range of oscillations from 20 Hz to 20 kHz;

- in fragments of sonograms of recordings of deep sea noise, the frequency range of oscillations prevails from 500 Hz to 20 kHz.

The indicated frequency ranges, which determine the possible frequency spectra of signals emitted during the search process, make it possible to estimate the maximum required bandwidth of the receiving and transmitting paths of the equipment of interacting objects:

- the bandwidth of the receiving path of the autonomous underwater object and the transmitting path of the search vessel - about 8 kHz;

- the bandwidth of the transmitting path of the autonomous bottom underwater object and the receiving direction finding paths of the search vessel is about 20 kHz.

For an acceptable technical implementation of the proposed method and obtaining the required accuracy in determining the angular coordinates of an autonomous underwater bottom object relative to a search vessel in the process of its hydroacoustic search, the following ratios of the frequency parameters of the navigation message signal and quasi-white masking noise during transmission and reception of the combined pinger beacon signal can be recommended:

, где c_min - минимально возможная скорость распространения звука в морской среде, А - расстояние между парами гидрофонов антенны в горизонтальной плоскости, - рекомендуемые значения частот - в пределах 2-4 кГц;- the frequency ƒ _{0 of the} harmonic oscillations of the navigation message is selected from the conditions of acceptable overall dimensions of the direction finding antenna of the search vessel and its structural placement on the vessel in compliance with the requirement:

, where c _min is the minimum possible speed of sound propagation in the marine environment, A is the distance between pairs of antenna hydrophones in the horizontal plane, - the recommended frequency values are within 2-4 kHz;

- the frequency parameters of the quasi-white noise masking the navigation message of the pinger beacon signal are selected based on the required accuracy of determining the angular coordinates of the autonomous bottom underwater object in the process of its hydroacoustic search, setting the excess of the lower boundary frequency of its spectrum F _shn over the frequency гармон _{0 of} harmonic oscillations of the navigation message at least 5 times, and the upper cutoff frequency F _wel of the noise spectrum is matched with the upper border of the passband of the transmission path of the autonomous bottom underwater object.

FIG. 5 and FIG. 6a shows examples of fragments of sonograms of records of possible acoustic noises of the sea search area, limited by the frequency range from 100 Hz to 8 kHz. FIG. 5a - a fragment of the recording of the sounds of sea lions with a duration of 5.5 s. FIG. 5b - a fragment of the recording of the sounds of fur seals with a duration of 5 s. FIG. 5c - a fragment of the recording of whale sounds with a duration of 12 s. FIG. 5d - a fragment of the recording of the sounds of croaker fish with a duration of 4.5 s. FIG. 6a - a fragment of the recording of drummer fish sounds, 2.5 s long.

FIG. 6b and FIG. 6c shows examples of fragments of sonograms of recordings of deep and shallow sea noises, respectively, limited to the frequency range from 100 Hz to 20 kHz, with a fragment duration of 2.2 s.

FIG. 6d shows a modified structure of signals from a ship echo sounder with pulses acoustically colored to the sounds of fish, fur seals and whales.

FIG. 7 shows an example of a possible ensemble of four combined pinger beacon signals of an autonomous bottom underwater object formed on the basis of the above recording sonograms: a) drummer fish, whales and deep sea noises (two pulses on the identification message); b) drummer fish, fur seals and deep sea noises (four pulses on the identification message); c) drummer fish, sea lions and deep sea noises (five impulses on the identification message); d) drummer fish, croaker fish and deep sea noises (nine pulses on the identification message). The ensemble signals have the following time parameters: the total signal duration is 2.22 s, the identification message duration is 2 s, the navigation message duration is 0.2 s, and the starting message duration is 0.02 s. The excess of the amplitudes of the starting pulses over the average amplitudes of the pulses of the identification parcels and the average amplitudes of the harmonic navigation parcels noisy with quasi-white noise in the ensemble signals are about 12 dB.

To implement the proposed method, the search vessel and the autonomous bottom underwater object are equipped with appropriate equipment.

FIG. 8 shows an example of an enlarged structural diagram of the equipment of a search vessel, where the following are indicated: hydroacoustic direction finding antenna (PGA); digital signal processing unit (DSP); pinger beacon signal identification unit (OSMP); emitted signal generating unit (FIS); 1 - hydrophones of the direction finding hydroacoustic antenna; 2, 3 - DF antenna signal switches; 4 - band signal amplifiers; 5 - analog-to-digital converters; 6 - calculator; 7 - block of auxiliary harmonic signals with a highly stable reference generator; 8 - block for centralized control, storage and display of information; 9 - threshold device; 10 - the first linear detector; 11 - the second linear detector; 12 - comparator; 13 - pulse counter; 14 - weakly directional transmitting hydroacoustic antenna; 15 - power amplifier; 16 - mp3 player.

FIG. 9 shows an example of an enlarged block diagram of the equipment of an autonomous bottom underwater object, where the following are indicated: a unit for identifying activation and surfacing signals of a search vessel (OSAV); a unit for generating combined pinger beacon signals (FKSMP); 17 - weakly directional receiving hydroacoustic antenna; 18 - switch of receiving antenna signals; 19 - weakly directional transmitting hydroacoustic antenna; 20 - band-pass signal amplifier; 21 - threshold device; 22 - the first linear detector; 23 - the second linear detector; 24 - comparator; 25 - pulse counter of activation signal; 26 - ascent signal pulse counter; 27 - power amplifier; 28 - mp3 player; 29 - block for autonomous control and storage of information with a highly stable reference generator; 30 - power supply.

The essence and an example of the technical implementation of the proposed method involves the implementation of certain actions, procedures and operations, which it is advisable to divide into the following stages.

1. On the search vessel, in preparation for the mission of the autonomous underwater object, the equipment shown in FIG. 8. In the initial state, the outputs of the hydrophones 1 of the four-element PHA are connected through switches 2 and 3 of the direction finding antenna signals to the inputs of the 4 bandpass signal amplifiers.

The four-element PHA is implemented on the basis of the geometry of a right parallelepiped with bases in the shape of a square, with pairwise placement of hydrophones at geometric points in space corresponding to opposite vertices of the upper and lower bases, ensuring the spatial perpendicularity of the lines connecting the pairs of hydrophones of the upper and lower bases, while the vertical axis of the antenna passes through the points of intersection of the diagonals of the bases, the length of the diagonals of the bases of the parallelepiped (the distance between the pairs of antenna hydrophones in the horizontal plane) is chosen from the conditions of the ship's structural arrangement of the antenna, and the height of the parallelepiped (the distance between the pairs of the antenna hydrophones in the vertical plane) is halved relative to the length of the selected diagonals grounds.

An example of the placement of PHA hydrophones in a Cartesian coordinate system is shown in Fig. 10, where G ₁ (x ₁ , y ₁ , z ₁ ), G ₂ (x ₂ , y ₂ , z ₂ ), G ₃ (x ₃ , y ₃ , z ₃ ), G ₄ (x ₄ , y ₄ , z ₄ ) - coordinates of hydrophones; A is the distance between pairs of antenna hydrophones in the horizontal plane; B is the vertical distance between the pairs of antenna hydrophones; ϕ, θ are the areas of bearings and elevation angles of the autonomous bottom underwater object, respectively. The receiving space of the presented antenna geometry is the region of the lower half-space bounded by the coordinate semiaxes X, -X, Y, -Y, -Z.

, где c_min - минимально возможная скорость распространения звука в морской среде, ƒ₀ - частота гармонических колебаний навигационной посылки. Один из вариантов возможных размеров ПГА шахтного (колодезного) спуска представлен на фиг. 11, который использован для количественной оценки точности позиционирования подводного объекта в заявляемом способе. При установке антенны согласовывают систему координат ПГА с курсом судна.The ratio of the horizontal and vertical dimensions of the direction-finding antenna of diametrically-orthogonal geometry is selected taking into account the minimization of the overall dimensions of the antenna in the conditions of ship operation and the reduction of hardware and software costs in determining the angular coordinates of the autonomous bottom underwater object relative to the search vessel. In this case, the fulfillment of the phase correspondence condition is monitored:

, where c _min is the minimum possible speed of sound propagation in the marine environment, ƒ ₀ is the frequency of harmonic oscillations of the navigation message. One of the options for the possible dimensions of the PHA of the mine (well) run is shown in Fig. 11, which is used to quantify the positioning accuracy of an underwater object in the claimed method. When installing the antenna, the PGA coordinate system is aligned with the course of the vessel.

An ensemble of activation signals a (t) with the selected amplitude parameters, frequency spectrum, the duration of the identification message Δτ _{2 is} synthesized in the mp3 format from the pulse fragments of sonograms of the recordings of the sounds of sea animals, fish, crustaceans and stored in the memory of the mp3 player 16 of the FIS unit.

The ascent signal e (t) with the selected amplitude parameters, frequency spectrum, the duration of the identification message Δτ _{4 is} synthesized from the pulse fragments of sonograms of the recordings of the sounds of sea animals, fish, crustaceans, and is also stored in the memory of the mp3 player 16 of the FIS unit.

The memory of the centralized control unit 8 is filled with data on the number of different combined signals z (t) of the pinger beacon formed on the autonomous bottom underwater object in the ensemble, and the number of pulses at the selected duration Δτ _{6 of} each signal of the ensemble identification.

Using the standard equipment of the echo sounder of the search vessel, connected with the computer 6 and the centralized control unit 8, the composition and structure of the sounding pulses of the ship echo sounder is modified on the basis of the corresponding pulse fragments of sonograms of records of sounds of sea animals, fish, crustaceans so that their number and intra-pulse color correspond to the possible the hybrid noise background of the marine environment, and the pulse repetition intervals are set based on the a priori known or assumed maximum depth of the search water area, while the number of sonar sounding pulses at the time interval equal to the ascent signal duration should not coincide with the total number of pulses in the ascent signal.

2. Equip, in mission preparation, the autonomous underwater object with the equipment shown in FIG. 9. Initialize the software of the autonomous control unit 29, which includes a highly stable reference generator. In the initial state, the output of the weakly directional receiving hydroacoustic antenna 17 is connected through the switch 18 of the receiving antenna signals to the input of the band-pass 20 signal amplifier.

Is synthesized in a format mp3 from pulsed fragments sonograms records marine animal sounds, fish, crustaceans, as well as noise marine environment ensemble combined signal z (t)-pinger beacon with selected amplitude parameters, frequency spectrum, duration parcel identification Δτ ₆ and enter into memory mp3 -player 28 block FKSMP.

The memory of the autonomous control unit 29 records data on the number of activation signals a (t), which are different in the ensemble, formed on the search vessel, and the number of pulses for the selected duration Δτ _{2 of the} identification message of each ensemble signal.

The memory of the autonomous control unit 29 also stores data on the duration of the identification message Δτ _{4 of} the ascent signal e (t) generated on the search vessel and the number of pulses on this message.

3. Before the search, the procedure for calibrating the amplifying paths of the four-element PHA of the search vessel is carried out, which assumes the following actions and operations.

On command from the block 8 of the centralized control of the switches 2, the outputs of the hydrophones 1 of the four-element PHA are disconnected from the inputs of the 4 band-pass amplifiers. Through the switches 3 of the direction finding antenna signals to the inputs of the bandpass 4 signal amplifiers, from the unit 7 of auxiliary harmonic signals, with a highly stable reference generator, a continuous harmonic signal u _to (t) of the frequency ƒ _{0 of} the navigation signal of the pinger beacon of the autonomous bottom underwater object known on the search vessel with a high signal-to-noise ratio:

where U _to , ϕ _to - amplitude and initial phase of oscillations of the calibration signal.

After amplification and filtering by 4 band-pass amplifiers, the signals in each receiving path are described by the following dependencies:

where χ ₁ , χ ₂ , χ ₃ , χ ₄ are parameters that take into account the gains of 4 bandpass amplifiers; ν ₁ , ν ₂ , ν ₃ , ν ₄ - phase shifts due to the spread of the phase-frequency characteristics of these amplifiers.

The signals H ₁ (t), H ₂ (t), H ₃ (t), H ₄ (t) are subjected by means of analog-to-digital converters 5, with appropriate control from the centralized control unit 8, to synchronous sampling with a multiple of four counts k per the oscillation period and the total number of samples L in the sample.

Four arrays H1 (n), H2 (n), H3 (n), H4 (n) of signal samples are entered into the memory of the calculator 6:

where n is the ordinal number of the sample in the sample, and the parameters k and L are related by the relations: L = 1.25k, k> 3⋅10 ³ .

Further, in the calculator 6, under the control of the centralized control unit 8, the following program operations are performed.

Standardization of samples of the arrays Н1 (n), Н2 (n), Н3 (n), Н4 (n) of signal samples is carried out by representing them with their own signs according to the rule:

The auxiliary correlation parameters β ₁ , γ ₁ , β ₂ , γ ₂ , β ₃ , γ ₃ are calculated and stored:

Calculate and store the phase differences ΔΨ ₁₂ , ΔΨ ₁₃ , ΔΨ ₁₄ , oscillations of the calibration signal u _to (t) at the outputs of three pairs of 4 bandpass amplifiers of DF antenna signals, which are calibration corrections:

After completing the calibration procedure of the amplifying paths, the outputs of the hydrophones 1 of the PHA are again connected to the inputs of the band-pass 4 signal amplifiers.

4. When the search vessel moves through the search water area, according to commands from the centralized control unit 8, supplied to the mp3 player 16 of the FIS unit, connected to the power amplifier 15 connected to the weakly directional transmitting hydroacoustic antenna 14, the space of the lower hemisphere is radiated into the aquatic environment, relative a search vessel, an ensemble of hydroacoustic activation signals a (t) of an autonomous bottom underwater object formed at stage 1 with a random alternation of the emitted signals of the ensemble and a randomly varying interval T _{A of} their repetition exceeding the background noise of the search water area, while for the time of radiation of each signal of the ensemble, the outputs of the hydrophones 1 PHA is disconnected by means of switches 2 of the direction finding antenna signals from the inputs of 4 bandpass signal amplifiers.

5. When the search vessel enters the zone of acoustic contact with the autonomous bottom underwater object and reliable reception on the autonomous bottom underwater object of one of the signals emitted by the search vessel of the ensemble of activation signals a (t), the corresponding equipment of the autonomous bottom underwater object is transferred from the sleeping mode to the operating mode ...

Reception and processing of activation signals on the autonomous bottom underwater object is carried out by means of a weakly directional receiving hydroacoustic antenna 17 and devices of the OCAV unit under the control of the autonomous control unit 29. For this:

- the band-pass amplifier 20 brings the level of the signals received by the antenna 17 to the value required for the operation of the remaining devices of the OCAV unit;

- with the help of the threshold device 21, the appearance of the starting message q (t ₁ ) of the activation signal is recorded and the pulse counters 25 and 26 are started;

- linear detectors 22 and 23, having significantly different time constants of the integration circuits, form the threshold level for detecting the received signals and extract the envelopes of the activation signal pulses on the identification message b (t ₂ ) for subsequent obtaining a sequence of pulses with digital logic levels using the comparator 24.

Since the memory of the autonomous control unit 29 contains the necessary data on the activation signals a (t) allowed for reception: the number of signals differing in the ensemble, the number of pulses for the selected duration Δτ _{2 of the} identification message of each ensemble signal (see step 2), then when the number of pulses, counted by the counter 25 for a known duration of the identification message, with the number of pulses on the identification message of one of the signals allowed to receive, a decision is made to receive the activation signal.

After that, on command from the autonomous control unit 29, the power source 30 is switched to the operating mode of supplying the supply voltages to the activated devices of the FKSMP unit.

6. Then, according to commands from the unit 29 for the autonomous control of the underwater object, supplied to the mp3 player 28 of the FKSMP unit, connected to the power amplifier 27 connected to the weakly directional transmitting hydroacoustic antenna 19, the space of the upper hemisphere, relative to the seabed, is radiated into the aquatic environment. at stage 2 of the combined signals z (t) of the pinger beacon with a random alternation of the emitted signals of the ensemble and a randomly varying interval T _{M of} their repetition exceeding the background noise of the search water area, while for the time of radiation of each signal of the ensemble, the output of the hydrophone of the weakly directional receiving hydroacoustic antenna 17 is switched off from using the switch 18 of the receiving antenna signals from the input of the bandpass 20 signal amplifier.

7. The combined signals z (t) of the pinger beacon emitted from the autonomous bottom underwater object at stage 6 are received by the hydrophones 1 of the search vessel PHA, the ensemble signals are identified by processing in the OSMP unit connected to the output of the 4-band amplifier of the signals of one of the PHA hydrophones. After the first reliable reception of the identification message s (t ₂ ) of one of the emitted signals of the ensemble, the emission of activation signals a (t) from the search vessel is stopped.

The principle of receiving the parcels for identifying the ensemble of signals z (t) of the pinger beacon on the search vessel and the functional composition of the equipment required for this are similar to the algorithmic and hardware attributes used in the processing of the ensemble of activation signals a (t) on the autonomous bottom underwater object of stage 5. For this under the control of block 8 of centralized control:

- using the threshold device 9, the appearance of the starting message y (t) of the signal z (t) is recorded and the pulse counter 13 is started;

- carried out by linear detectors 10 and 11, having significantly different time constants of the integration circuits, the formation of the threshold level of detection of the received signals and the selection of the envelope pulses of the signal z (t) on the identification message for the subsequent receipt of a sequence of pulses with the levels of digital logic using the comparator 12;

- make a decision on the reception of the signal z (t) when the number of pulses counted by the counter 13 for the known duration of the identification message coincides with the number of pulses on the identification message of one of the ensemble signals allowed to receive.

8. A procedure for determining the angular coordinates of the autonomous bottom underwater object relative to the search vessel is carried out, in which the bearing ϕ and the elevation angle θ of the underwater object are calculated and stored in the coordinate system of the ship direction finding antenna coordinated with the direction of movement of the search vessel. This procedure is coordinated with the geometric parameters of the direction finding antenna, allows positioning of the autonomous bottom underwater object relative to the search vessel with the required accuracy under conditions of low signal-to-noise ratios of the masked navigation signal and includes the following actions and operations.

In block 7 of auxiliary harmonic signals, on the basis of a highly stable reference generator, the quadrature components Y1 (t), Y2 (t) of the harmonic signal Y (t) of frequency ƒ ₀ , characterized by large signal-to-noise ratios, are formed.

After reliable reception of the identification message s (t ₂ ) of one of the signals z (t) of the pinger beacon ensemble of the autonomous bottom underwater object, the signals u ₁ (t), u ₂ (t), u ₃ (t), u ₄ (t) , Y ₁ (t), Y ₂ (t) by means of analog-to-digital 5 converters, with appropriate control from the centralized control unit 8, are subjected to a harmonic navigation message x (t ₃ ) on the time interval t ₃ ∈ [τ ₉ ... τ ₁₀ ] synchronous sampling with a multiple of four k samples on the oscillation period and the total number of samples L in the sample.

Six arrays u1 (n), u2 (n), u3 (n), u4 (n), Y1 (n), Y2 (n) signal samples are entered into the memory of calculator 6:

where n is the ordinal number of the sample in the sample, and the parameters k and L are related by the relations: L = 100k, k> 3⋅10 ³ .

Further, in the calculator 6, under the control of the centralized control unit 8, the following program operations are performed.

The weights W1 and W2 are calculated and stored, which determine the projections of the signal u ₁ (t) onto the quadrature components of the signal Y (t):

The weight coefficients W3 and W4 are calculated and stored, which determine the projections of the signal u ₂ (t) onto the quadrature components of the signal Y (t):

The weight coefficients W5 and W6 are calculated and stored, which determine the projection of the signal u ₃ (t) onto the quadrature components of the signal Y (t):

The weight coefficients W7 and W8 are calculated and stored, which determine the projection of the signal u ₄ (t) onto the quadrature components of the signal Y (t):

Performing operations (14) - (17) makes it possible to find the projections of signals u ₁ (t), u ₂ (t), u ₃ (t), u ₄ (t) (on the time interval of a harmonic navigation message) with small signal / masking ratios noise on the quadrature components Y1 (t) and Y2 (t) of the harmonic signal Y (t), having a large signal-to-noise ratio.

These projections are necessary to obtain four harmonic signals with high signal-to-noise ratios, in phase with signals u ₁ (t), u ₂ (t), u ₃ (t), u ₄ (t), having low signal-to-noise ratios, which are used in further calculations to significantly increase the accuracy of measuring the phase differences of the oscillations of the navigation signal x (t ₃ ) at the outputs of three pairs of hydrophones of the direction finding antenna of a search vessel and to ensure the required accuracy in determining the angular coordinates of an autonomous bottom underwater object relative to the search vessel in conditions of low signal-to-noise ratios on the interval of the masked navigation burst of the combined beacon-pinger signal.

The synchronization accuracy sufficient to obtain a small error in measuring the phase differences is achieved due to the correlation processing of signals of a low frequency of the navigation message against the background of higher-frequency quasi-white noises, which makes it possible to implement effective coherent accumulation, well known in the theory of noise-immune signal processing [4].

Form and store four arrays R1 (n), R2 (n), R3 (n), R4 (n) of samples of samples belonging to the signals of the block 7 of auxiliary harmonic signals, in phase with the signals u ₁ (t), u ₂ (t), u ₃ (t), u ₄ (t), respectively, and having large signal-to-noise ratios as a result of in-phase operations:

The samples of the R1 (n), R2 (n), R3 (n), R4 (n) signal samples are normalized by representing them with their own signs according to the rule:

The auxiliary correlation parameters β ₁ , γ ₁ , β ₂ , γ ₂ , β ₃ , γ ₃ are calculated and stored:

Calculate and store the phase differences of harmonic oscillations Δφ ₁₂ , Δφ ₁₃ , Δφ _{14 of the} navigation signal x (t ₃ ) at the outputs of three pairs of hydrophones (G ₁ -G ₂ , G ₁ -G ₃ , G ₁ -G ₄ ) of the direction finding antenna ( Fig. 10) of the search vessel:

Specifying and storing values phase differences Δψ _12, Δψ _13, Δψ ₁₄ combined signal harmonic navigation sending signal oscillations beacon-pinger autonomous bottom underwater object at the outputs of the three pairs of hydrophones DF antenna exploratory vessel with the calibration corrections ΔΨ _12, ΔΨ _13, ΔΨ ₁₄ calculated in the calibration procedure of the DF antenna gain paths:

The bearing ϕ (relative to the course of the search vessel) and the elevation angle θ (relative to the water surface level with vertical stabilization of the direction finding antenna of the search vessel) of the autonomous bottom underwater object are calculated and memorized according to the following trigonometric formulas:

Formulas (23) and (24) are a special case of the general algorithm for positioning underwater objects, developed by the authors of the application and presented in publication [2].

9. At the command from the unit 8 of the centralized control of the search vessel, the depth h of the water area of the search is measured with a ship echo sounder with a modernized structure of sounding pulses, which is stored in the memory of the calculator 6. The time intervals between depth measurements depend on the profile of the seabed of the search area, and the emission of sounding pulses begins only after receiving the next signal z (t) from the ensemble of combined pinger beacon signals of the autonomous bottom underwater object.

10. Estimated and stored in the computer 6 of the search vessel according to the calculated elevation angle θ of the autonomous bottom underwater object and the measured depth h of the search water area, the approximate values of the range d and slope distance r _n to the autonomous bottom underwater object (Fig. 12), using trigonometric relations:

11. Based on the location parameters ϕ, θ, d, r _{n of the} autonomous bottom underwater object relative to the search vessel, updated with the frequency of the pinger beacon signals and the intervals for measuring the depth of the search water area, the course of the search vessel to the safe ascent range of the autonomous bottom underwater object - range, excluding a possible collision during the ascent of the underwater object and the search vessel, which is estimated using the water area depth and current speed measured on the search vessel, as well as the predicted ascent trajectory of the underwater object.

12. After receiving and processing on the search vessel the next signal z (t) from the ensemble of combined signals of the beacon-pinger of the autonomous bottom underwater object, at the command from the centralized control unit 8 arriving at the mp3 player 16 of the FIS unit connected to the power amplifier 15, connected to a weakly directional transmitting hydroacoustic antenna 14, emit into the aquatic environment of the space of the lower hemisphere, relative to the search vessel, the ascent signal e (t) of the autonomous bottom underwater object, which exceeds the background noise of the search area in level, while the outputs of the hydrophones 1 of the PHA are turned off for the duration of the signal radiation using switches 2 of the direction finding antenna signals from the inputs of 4 bandpass signal amplifiers.

13. Reception and processing of the surfacing signal on the autonomous bottom underwater object is carried out by means of a weakly directional receiving hydroacoustic antenna 17 and devices of the OCAV unit under the control of the autonomous control unit 29. For this:

- the band-pass amplifier 20 brings the level of the signal received by the antenna 17 to the value required for the operation of the remaining devices of the OCAB unit;

- using the threshold device 21, the appearance of the starting message g (t ₁ ) of the ascent signal is recorded and the pulse counters 25 and 26 are started;

- linear detectors 22 and 23, having significantly different time constants of the integration circuits, form a threshold level for detecting the received signal and extract the enveloping pulses of the ascent signal on the identification message j (t ₂ ) for subsequent obtaining a sequence of pulses with digital logic levels using the comparator 24;

- when the number of pulses counted by the counter 26 over the known duration of the identification message coincides with the number of pulses on the identification message stored in the memory of the autonomous control unit 29 (see step 2), a decision is made to receive the ascent signal.

After that, on command from the autonomous control unit 29, the corresponding actuators of the buoyancy change system are started and the emission of the signal z (t) of the pinger beacon of the autonomous bottom underwater object is stopped.

14. If, after the first emission by the search vessel of the ascent signal e (t), the reception of the signals z (t) of the pinger beacon of the autonomous bottom underwater object on the search vessel does not stop, then the ascent signal is re-emitted (see step 12).

In the technical implementation of the proposed method, modern element base and digital signal processing technologies can be used. Examples of possible technical implementation of functional elements of equipment for a search vessel and an autonomous underwater object using commercially available products are presented in Table. 1 and tab. 2.

It should be noted that the synthesis of the signals of a search vessel and an autonomous underwater object necessary for a covert hydroacoustic search in the form of corresponding files of mp3-players 16, 28, from the available fragments of sonograms of recordings of the sounds of background noise of the marine environment, can be performed using standard AVS software applications Audio Editor, Audio Master and Ocen Audio for Windows operating system.

Let us calculate, on the basis of engineering relationships systematized for the hydroacoustic channel [17], the transmitter power of the underwater hydroacoustic signal transmission line required to assess the feasibility of technical implementation of transmitting hydroacoustic antennas 14, 19 of a search vessel and an autonomous underwater object.

Signal power P _p at the input of the receiver is determined by the dependence

where P _and - the power of the transmitter; G _p , G _and - the directivity of the receiving and transmitting antennas, respectively; η _p , η _and are the efficiency of the receiving and transmitting antennas, respectively; c is the speed of sound in seawater; S _p - effective area of the receiving antenna; R is the length of the underwater transmission line for hydroacoustic signals (slant distance between the receiving and transmitting antennas); ƒ is the frequency of the emitted signal; γ is a coefficient that takes into account the loss of signal power in the marine environment due to absorption.

The signal power at the receiver input, taking into account the signal-to-noise ratio h ² required for reliable reception, can be determined by the formulas:

where h ² is the required signal-to-noise ratio at reception; Δƒ is the frequency band of the receiving path; А (b) - coefficient, the value of which depends on the state b of the sea surface in points; B - coefficient determined by the temperature of sea water.

It should be borne in mind that the spectral density N _{m of the} noise of the marine environment

, а шумы водной среды для частот от 8 кГц и выше обусловлены преимущественно шумами водной поверхности, зависящими от волнения моря.has the dimension

, and the noise of the aquatic environment for frequencies from 8 kHz and above is mainly caused by the noise of the water surface, which depends on the sea state.

From relations (26) and (27), taking into account dependence (28), we obtain an expression for calculating the required power of the transmitter of hydroacoustic signals:

where the dimensions of the quantities: ƒ, Δƒ - in kHz; R - in km; h ² - in dB; P _and - in W.

The permissible specific acoustic power R _{a of} most piezomaterials used for the manufacture of hydrophones lies in the range of R _a ≈ 10 ^-1 ... 10 ² W / cm ² . For piezomaterials based on barium titanate Р _а ≤2 W / cm ² , and for PZT (lead zirconate titanate) materials Р _а ≤15 W / cm ² [18].

For example, for a variant of a possible technological execution of a spherical hydrophone with a sphere radius r _g = 4 cm of an active element made of PZT (P _a = 10 W / cm ² ) materials, the permissible acoustic power of a hydrophone in a radiation hemisphere can be at the level of 1000 W (2⋅π⋅ r _g ² ⋅P _a = 2⋅3.14⋅16⋅10 = 1000.5).

[19] для самой низкой частоты спектра излучаемых сигналов, равной 100 Гц, акустическую мощность указанного излучающего гидрофона только около 30 Вт.However, taking into account the presence of the cavitation effect, which limits the acoustic power of the emitting hydrophone, it can be assumed that at the cavitation threshold

[19] for the lowest frequency of the spectrum of emitted signals equal to 100 Hz, the acoustic power of the said emitting hydrophone is only about 30 W.

Taking into account the average efficiency of piezoceramic transducers, losses during matching and sealing, the efficiency of the emitter can be taken at the level of 0.6, then the upper limit of the transmitter power for the indicated hydrophone will be 50 W.

For the selected power P _{and the} transmitter of hydroacoustic signals, using formula (29), we calculate the length R of the underwater transmission line of hydroacoustic signals for the given: signal-to-noise ratio h ² at the reception, frequency ƒ of the emitted signal, frequency band Δƒ of the receiving path, directional action factor G _{and the} transmitting antenna, its efficiency η _and and the state b of the sea surface.

Calculations according to formula (29), which can be considered a dependence of the first approximation, the length R of the underwater transmission line of hydroacoustic signals with a receiver on a search vessel at the values: P _and = 50 W, ƒ = 8 kHz, Δƒ = 19 kHz, h ² = 20 dB , G _and = 1, η _and = 0.6 depending on the state b of the sea surface (according to the official scale of the World Maritime Organization) are presented in Table 3.

The values of the slope distances obtained in Table 3 can be used as the predicted maximum possible slope distances r _{n max} from the search vessel to the autonomous bottom underwater object during their acoustic contact in the water area with the expected state of the sea surface for calculating the minimum permissible intervals of repetition of hydroacoustic activation signals T _A vessel and beacon-pinger _TM bottom autonomous underwater object on the basis of relations (6).

With a known technically realizable power of hydroacoustic emitters, it is also possible to estimate the necessary sensitivity of hydroacoustic receivers of an autonomous underwater object and a search vessel. We will perform the estimate based on the materials of the classical monograph [19].

For an omnidirectional emitter located in a homogeneous aqueous medium, the intensity of the sound wave can be written in the following form

where P is the root-mean-square pressure, expressed in Pa; ρ is the density of water equal to 10 ³ kg / m ³ ; s is the speed of sound in water, which we take 1500 m / s.

The relationship between the indicated intensity and the transmitter power is

where P _and - transmitter power; η _and is the efficiency of the transmitting antenna; R is the length of the underwater hydroacoustic signal transmission line.

From relation (31) we find the rms pressure P:

where the dimensions of the quantities: P _and - in W; R - in km; ρ - in kg / m ³ ; s - in km / s.

The sensitivity of receiving hydrophones is usually expressed in μV / Pa, then the voltage at the output of the receiving hydrophone with sensitivity μ will be

Table 4 shows the results of calculations of the output voltage of the hydrophone (see Table 1 and Table 2) of the Brüel & Kjr company model 8105 (μ = 56 μV / Pa) with a transmitter power of 50 W and a transmitting antenna efficiency η _and = 0.6 for various values the slope distance R between the receiver and the transmitter.

The obtained signal levels at the outputs of the receiving hydrophones of the selected model of an autonomous underwater object and a search vessel allow, with the transmission coefficients of band 4, 20 amplifiers (see Table 1 and Table 2) of the receiving paths of the order of 2 обеспечивать10 ^{4, to} provide standard operating modes of the electronic components of the rest of the equipment for the indicated boundaries of the change in the slope distance during the search operations.

Let us estimate the positioning accuracy of an autonomous bottom underwater object relative to a search vessel during hydroacoustic search depending on the ratio of the harmonic signal levels of the navigation message of the pinger beacon and the quasi-white noise masking it (signal-to-noise ratio) by modeling in the mathematical environment Mathcad 15.

The initial data for modeling are set based on the acceptable conditions of the ship's structural placement of the direction finding antenna, the most probable scenarios for the relative positioning of the search vessel and the underwater object, as well as the required accuracy of determining the angular coordinates of the autonomous bottom underwater object relative to the search vessel during its hydroacoustic search:

- the frequency ƒ _{0 of} harmonic oscillations in the message x (t ₃ ) of the navigation signal of the pinger beacon of the autonomous bottom underwater object is 3 kHz;

- the frequency range of quasi-white noise, masking the message x (t ₃ ) of the navigation signal of the pinger beacon of an autonomous bottom underwater object, has a lower F _shn and upper F _shv boundaries - F _shn = 15 kHz, F _br = 20 kHz, the noise frequency band ΔF _sh = 5kHz;

- the boundaries of the passband of the receiving paths (band 4 amplifiers of the search vessel) at the half power level from 1 kHz to 20 kHz;

- Г ₁ (0.1,0,0), Г ₂ (-0.1,0,0), Г ₃ (0,0.1, -0.1), Г ₄ (0, -0.1, -0.1) - Cartesian coordinates of the ship's direction finding hydrophones antennas of the selected size (A = 0.2 m, B = 0.1 m), expressed in meters;

- range of change of bearings of an autonomous bottom underwater object in the search process ϕ = 0 °… 360 °;

- the range of variation of the elevation angles of the autonomous bottom underwater object in the search process θ = 10 °… 70 °;

- the range of variation of the slope distances from the search vessel to the autonomous bottom underwater object r _n = 50 m ... 3000 m;

- the sea water area with acoustic contact between the search vessel and the autonomous bottom underwater object is conditionally divided into the near r _n <100 m, θ = 70 ° and the far r _n > 500 m, θ = 10 ° of the search zone;

- the quasi-white noise masking the navigation message m (t ₃ ) of the pinger beacon signal has a normal probability distribution, a zero mean value and a specified variance;

- estimation of the maximum error in calculating the phase differences Δφ ₁₂ , Δφ ₁₃ , Δφ ₁₄ oscillations of the parcel x (t ₃ ) of the navigation signal of the beacon-pinger of an autonomous bottom underwater object at the outputs of three pairs of hydrophones of the ship's direction finding antenna is carried out by the method of statistical tests using 25 independent realizations of the generated quasi-white noise;

- the number of counts k on the period of harmonic oscillations of the navigation message and the total number of counts L in the sample when the procedure for determining the angular coordinates of the autonomous bottom underwater object relative to the search vessel is selected, respectively, k = 3.6⋅10 ³ , L = 3.6⋅10 ⁵ ;

- the relative discrepancy between the oscillation frequencies formed on the basis of the ship's highly stable reference generator and the oscillations of the parcel of the received navigation signal of the pinger beacon was chosen equal to 2⋅10 ^-3 , which corresponds to the variant of hydroacoustic search with a possible radial speed of the search vessel relative to the positioned autonomous bottom underwater object 3 m / s (5.84 knots).

The results of calculations of the boundary positioning accuracy (Fig. 13 and Fig. 14) show, for example, that for possible signal / masking noise ratios in the process of hydroacoustic search at a level of minus 30 dB, using the proposed method, it is possible to determine the angular coordinates ϕ and θ of an autonomous bottom underwater an object relative to the search vessel in the near search zone with an accuracy of no worse than 1 ° in bearing and 0.4 ° in elevation, and in the far search zone with greater accuracy - no worse than 0.3 ° in bearing and 0.2 ° in elevation.

The specified boundary accuracies are quite enough to ensure an effective process of covert hydroacoustic positioning of an autonomous underwater bottom object during its search from the moment of activation to ascent, implying constant correction of the search vessel's course based on functionally independent estimates of the location parameters of the autonomous bottom underwater object using the corresponding signals from it. pinger beacon.

It should be noted that the presented boundary calculation accuracy characterizes the maximum of the maximum possible (maximum maximorum) positioning errors that can occur with such combinations of bearing values ϕ, elevation angle θ of an autonomous bottom underwater object, maximum errors in determining phase differences Δφ ₁₂ , Δφ ₁₃ , Δφ ₁₄ oscillations of the message x (t ₃ ) of the navigation signal of the pinger beacon of an autonomous bottom underwater object at the outputs of three pairs of hydrophones of the ship's direction finding antenna, as well as signs of the indicated errors, which lead to the largest absolute errors in operations (23), (24) for calculating the angular coordinates of an autonomous bottom underwater object relative to a search vessel for the worst search conditions.

If we take into account that the probability of occurrence of the above unfavorable combinations of bearing values, elevation angle, errors in determining the phase differences and signs of these errors (functional positioning parameters) in the full time cycle of real search will be small, then one should count on the prevalence of high positioning accuracy in the search process in comparison with the presented boundary.

The tendency to increase the positioning accuracy with distance from the underwater object positively characterizes the positioning algorithm developed by the authors of the application [2], since the search process begins, as a rule, from large distances of the search vessel from the autonomous bottom underwater object.

Thus, the proposed technical solution allows to achieve the desired effect - increasing the secrecy of the process of hydroacoustic search for an autonomous underwater object from a surface search vessel, due to a previously unused combination: the use of hydroacoustic signals in the process of search actions, masked for possible acoustic background noise of a known water area search - sounds of sea animals, fish, crustaceans, sea noises, selection of the proper structure, amplitude, time and frequency parameters of these hydroacoustic signals, performing the procedure for determining the angular coordinates of an autonomous bottom underwater object relative to the search vessel, consistent with the geometric parameters of the direction finding antenna of the search vessel, which together with the procedure for calibrating the amplifying paths of the direction finding antenna of the search vessel, it makes it possible to position the autonomous bottom underwater object relative to the search vessel with the necessary the same accuracy in conditions of low signal-to-noise ratios of the masked navigation signal.

This set of features of a new technical solution distinguishes the proposed method from the currently known methods of hydroacoustic positioning of underwater objects.

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Claims (31)

1. A method of hydroacoustic search from a surface search vessel for an autonomous bottom underwater object in a dormant mode in a known sea area after completing a corresponding mission, which consists in equipping a search vessel with a direction finding antenna, a diametrically orthogonal geometry of the location of four receiving hydrophones, a weakly directional transmitting hydroacoustic antenna, equipment for receiving and processing the signal of the beacon-pinger of an autonomous bottom underwater object based on a highly stable reference generator, equipment for generating activation signals and ascent of an autonomous bottom underwater object, hydroacoustic means for measuring the depth of the search water area, equipping an autonomous bottom underwater object with weakly directional receiving and transmitting hydroacoustic antennas , equipment for receiving and processing signals for activation and ascent of a search vessel, a pinger beacon that forms, using a highly stable a repeating navigation signal, the frequency of which is a priori known on the search vessel, by the buoyancy change system, in the repeating, as the search vessel moves through the search water area, its radiation by the transmitting antenna into the aquatic environment of the lower hemisphere space, relative to the search vessel, the hydroacoustic activation signal of an autonomous bottom underwater object exceeding the background noise of the aquatic environment of the search area, in reception by the receiving antenna and the necessary processing at the autonomous bottom underwater object of the hydroacoustic activation signal of the search vessel, in translation of the equipment of the autonomous bottom underwater object, on the fact of reliable reception of the activation signal from the sleeping to operating mode, in the radiation of a transmitting antenna of an autonomous bottom underwater object into the aquatic environment of the search area, in the directions of the upper hemisphere, relative to the seabed, a hydroacoustic navigation signal exceeding the background noise during the bottom of the environment, formed by a pinger beacon and repeated with an interval longer than its duration, in the reception by the direction finding antenna of the search vessel of the hydroacoustic signal of the pinger beacon and its corresponding processing, with the subsequent termination, upon its reliable reception, of the emission of the sonar activation signal by the transmitting antenna of the search vessel of an autonomous bottom underwater object, in measuring and storing the depth h of the water area of the search by hydroacoustic means of measuring the search vessel, in determining and storing the bearing ϕ and the elevation angle θ of the autonomous bottom underwater object relative to the search vessel, in assessing and storing at a certain elevation angle and measured water depth the water area of the search for approximate values of the distance d and the slope distance r _n to the autonomous bottom underwater object using trigonometric relations:

, To adjust the rate of movement exploratory vessel based on the updated location φ parameters, θ, d, r _n autonomous bottom underwater object relative exploratory vessel as it moves in the water area search to a predetermined safe range ascent autonomous bottom underwater object in the radiation transmission antenna of the search vessel into the aquatic environment of the search water area, in the space of the lower hemisphere, relative to the search vessel, in the pause between the signals of the pinger beacon of the autonomous bottom underwater object, the hydroacoustic signal of the ascent of the autonomous bottom underwater object, exceeding the background noise of the aquatic environment, when received by the receiving antenna and the necessary processing on the autonomous bottom underwater object of the hydroacoustic signal of ascent, in the termination, upon the fact of reliable reception of the signal of ascent, the emission of the hydroacoustic signal of the pinger beacon by the transmitting antenna of the autonomous bottom underwater object, in the operating mechanisms of the system for changing the buoyancy of an autonomous underwater underwater object, characterized in that they form and remember when preparing a mission of an autonomous underwater object on an underwater object and a search vessel the signals emitted in the process of hydroacoustic search: on an autonomous underwater object - signals of a pinger beacon, on a search vessel - signals of activation and ascent of an autonomous bottom underwater object, having a given structure, amplitude, time and frequency parameters, according to acoustic perception, approaching possible background noise of a known search water area, while the signals of activation and ascent of a search vessel consist of two components: a starting message and a message identification, the combined pinger-beacon signal of the autonomous seabed underwater object contains four components: the starting message, the identification message, the navigation message in the form of a harmonic signal of the frequency known on the search vessel and masking the navigation quasi-white noise, the frequency parameters of which are selected based on the required accuracy of determining the angular coordinates of the autonomous underwater object relative to the search vessel during its hydroacoustic search, providing the required frequency band and the corresponding excess of the lower boundary frequency of its spectrum over the frequency of harmonic oscillations of the navigation message, are modified the structure of the sounding pulses of the ship's echo sounder so that the acoustic perception of the procedure for measuring the depth of the water area of the search corresponds to the possible hybrid noise background of the marine environment, in addition, the structure and parameters of the emitted signals of the pinger beacon of the autonomous bottom underwater object are a priori known on the search vessel, and the structure and parameters of the emitted activation and surfacing signals of the search vessel are a priori known on the autonomous bottom underwater object, before the search, the procedure for calibrating the amplifying paths of the direction finding antennas is performed s of the search vessel with the receipt and storage of calibration corrections, during the search on the search vessel, the procedure for determining and storing the angular coordinates of the autonomous bottom underwater object relative to the search vessel is carried out, coordinated with the geometric parameters of the direction finding antenna and allowing positioning of the autonomous bottom underwater object relative to the search vessel with the required accuracy in conditions of low signal-to-noise ratios of the masked navigation signal. 2. The method of hydroacoustic search for an autonomous bottom underwater object according to claim 1, characterized in that fragments of sonograms of records of sounds of sea animals, fish, crustaceans and noises are used as components of the activation signals, surfacing of the search vessel and the combined pinger signal of the autonomous bottom underwater object marine environment with specified amplitude, time and frequency parameters, while the fragments used have a pronounced impulse character with a well-distinguishable structure for reliable impulse reception, and fragments of sonograms of recordings of background noises of a shallow or deep sea, selected depending on the depth of the proposed water area of the search for an autonomous underwater object and having statistical characteristics similar to quasi-white noise, serve as the basis for the formation of noise that masks the harmonic navigation message of the pinger beacon of an autonomous underwater bottom object. 3. The method of hydroacoustic search for an autonomous bottom underwater object according to claim 1, characterized in that the frequency parameters of the quasi-white noise masking the navigation message of the combined signal of the pinger beacon of the autonomous bottom underwater object are determined based on the required accuracy of estimating the angular coordinates of the autonomous bottom underwater object relative to of the search vessel in the process of its hydroacoustic search, ensuring that the lower cutoff frequency of its spectrum over the frequency of harmonic oscillations of the navigation message is at least five times, and the upper cutoff frequency of the quasi-white noise spectrum is matched to the upper border of the transmission channel bandwidth of the autonomous bottom underwater object. 4. A method of hydroacoustic search for an autonomous bottom underwater object according to claim 2, characterized in that an ensemble of activation signals of a search vessel is formed from fragments of sonograms of recordings of sounds of various sea animals, fish, crustaceans with a different number of pulses at the selected duration of the identification message, the procedure for emitting activation signals from the above ensemble is changed randomly until a response is received from the autonomous bottom underwater object, while the number of activation signals that differ in the ensemble, generated on the search vessel, and the number of pulses for the selected duration of the identification message of each signal of the ensemble are a priori known on the autonomous bottom underwater object. 5. The method of hydroacoustic search for an autonomous bottom underwater object according to claim 2, characterized in that an ensemble of combined signals of a pinger-beacon of an autonomous bottom underwater object with a different number of pulses for the selected duration of the identification message is formed from fragments of sonograms of recordings of sounds of various marine animals, fish, crustaceans , the order of emission of pinger beacon signals from said ensemble is changed randomly until a surfacing signal is received from the search vessel, while the number of differing signals in the pinger beacon ensemble formed on the autonomous bottom underwater object and the number of pulses at the selected duration of the identification message of each ensemble signal are known a priori on the search vessel. 6. The method of hydroacoustic search for an autonomous bottom underwater object according to claim 1, characterized in that the repetition intervals of the hydroacoustic activation signals T _{A of the} search vessel and the pinger beacon T _{M of the} autonomous bottom underwater object are chosen randomly varying and exceeding the minimum permissible values T _A > T _{A min} , T _M > T _{M min} , which are determined from the condition of providing an asynchronous receive-transmit mode in the search process, excluding the overlap in time of the emitted and received hydroacoustic signals on the search vessel and the autonomous bottom underwater object, using the following calculated relations:

, where Δτ ₂ is the duration of the transmission of the identification of the search vessel activation signal, Δτ ₄ is the duration of the transmission of the identification of the search vessel ascent signal, Δτ ₈ is the total duration of the pinger beacon signal of the autonomous bottom underwater object, c _min is the minimum possible speed of sound in the marine environment, r _{h max} is the predicted maximum possible slope distance from the search vessel to the autonomous bottom underwater object during their acoustic contact in the search water area. 7. The method of hydroacoustic search for an autonomous bottom underwater object according to claim 2, characterized in that, based on the identification of pulse fragments of sonograms of records of sounds of sea animals, fish, crustaceans, the structure of sounding pulses of the ship's echo sounder is modified so that the acoustic perception of the procedure for measuring the depth of the water area in the search process corresponded to a possible hybrid noise background of the marine environment, and the number of sounding pulses of the echo sounder at a time interval equal to the ascent signal duration should not coincide with the total number of pulses in the ascent signal. 8. The method of hydroacoustic search for an autonomous bottom underwater object according to claim 1, characterized in that the procedure for calibrating the amplifying paths of the direction finding antenna of the search vessel, performed before the start of the hydroacoustic search, includes the following actions and operations: form a calibration continuous harmonic signal on the search vessel with large S / N ratio and the known frequency of harmonic oscillations navigation sending a signal beacon-pinger autonomous bottom underwater object, which is fed to the inputs of the four band signals amplifiers DF antenna disconnected at calibration time of the hydrophone output direction-finding antenna, the signals H ₁ (t), H ₂ (t), H ₃ (t), H ₄ (t) at the outputs of the band-pass amplifiers of the direction-finding antenna are subjected to synchronous sampling with a multiple of four counts k on the oscillation period and the total number of counts L in the sample, four arrays H1 (n) are stored, H2 (n), H3 (n), H4 (n) signal samples

where n is the ordinal number of the sample in the sample, and the parameters k and L are related by the relations: L = 1.25k, k> 3⋅10 ³ , normalize the counts of the arrays H1 (n), Н2 (n), Н3 (n), Н4 ( n) samples of signals by representing them with their own signs according to the rule

calculate and store auxiliary correlation parameters β ₁ , γ ₁ , β ₂ , γ ₂ , β ₃ , γ ₃

calculate and store the phase differences ΔΨ ₁₂ , ΔΨ ₁₃ , ΔΨ ₁₄ oscillations of the calibration signal at the outputs of three pairs of band-pass amplifiers of signals from the direction finding antenna of the search vessel, which are calibration corrections

9. The method of hydroacoustic search for an autonomous bottom underwater object according to claim 1, characterized in that the procedure for determining the angular coordinates of the autonomous bottom underwater object relative to the search vessel at low signal-to-noise ratios of the masked navigation signal, matched with the geometry of the direction finding antenna of the search vessel and performed in the process hydroacoustic search, includes the following actions and operations: a mixture of harmonic oscillations and masking noise of the navigation message of the combined signal of the beacon-pinger of an autonomous bottom underwater object, received by four hydrophones of the direction finding antenna of the search vessel, represented by signals u ₁ (t), u ₂ (t) , u ₃ (t), u ₄ (t) on the interval of the navigation message, and the quadrature components Y ₁ (t), Y ₂ (t) of the harmonic signal Y (t) of the frequency of the navigation message of the combined pinger beacon signal of the autonomous bottom underwater object, formed on the basis of the ship's highly stable th reference generator and having a large signal-to-noise ratio, are subjected to synchronous sampling with a multiple of four k samples per oscillation period and the total number of samples L in the sample, six arrays u1 (n), u2 (n), u3 (n), u4 are stored (n), Y1 (n), Y2 (n) signal samples

where n is the ordinal number of the sample in the sample, and the parameters k and L are related by the ratios: L = 100k, k> 3⋅10 ³ , the weight coefficients W1 - W8 are calculated and stored, which determine the corresponding projections of the signals u ₁ (t), u ₂ ( t), u ₃ (t), u ₄ (t) into the quadrature components Y ₁ (t), Y ₂ (t) of the harmonic signal Y (t)

form and store four arrays R1 (n), R2 (n), R3 (n), R4 (n) of samples of signals with high signal-to-noise ratios, in phase with the signals u ₁ (t), u ₂ (t), u ₃ (t), u ₄ (t), respectively,

normalization of the samples of the arrays R1 (n), R2 (n), R3 (n), R4 (n) of signal samples by representing them with their signs according to the rule

calculate and store auxiliary correlation parameters β ₁ , γ ₁ , β ₂ , γ ₂ , β ₃ , γ ₃

the phase differences Δφ ₁₂ , Δφ ₁₃ , Δφ _{14 of the} oscillations of the masked harmonic signal of the navigation message of the combined signal of the beacon-pinger of the autonomous bottom underwater object at the outputs of three pairs of hydrophones of the direction finding antenna of the search vessel are calculated and stored

specifying and storing values phase differences Δψ _12, Δψ _13, Δψ ₁₄ oscillations masked harmonic signal navigation sending-pinger beacon combined signal autonomous bottom underwater object at the outputs of the three pairs of hydrophones DF antenna exploratory vessel with the calibration corrections ΔΨ _12, ΔΨ _13, ΔΨ ₁₄ calculated in the procedure for calibrating the gain paths of the search vessel's direction finding antenna Δψ ₁₂ = Δφ ₁₂ -ΔΨ ₁₂ , Δψ ₁₃ = Δφ ₁₃ -ΔΨ ₁₃ , Δψ ₁₄ = Δφ ₁₄ -ΔΨ ₁₄ , determine and store, relative to the course of the search vessel, bearing ϕ and, relative to the water surface level with vertical stabilization of the direction finding antenna of the search vessel, the elevation angle θ of the autonomous bottom underwater object using the following trigonometric relations

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