RU2724962C1 - Method of determining coordinates of a marine noisy target - Google Patents

Abstract

FIELD: hydro acoustics.SUBSTANCE: invention relates to hydro acoustics, namely to methods and devices for detecting marine targets by their noise emission, and more specifically to methods of determining coordinates of targets using interference maxima in autocorrelation function of target noise. Technical result is achieved by determining maximally compact area of possible location of target in space "distance-depth", in which the position of the signal source is searched for by distance and depth, for which the interference maxima in ACF of the broadband target noise calculated by the beam program, best match the interference peaks in the ACF measured at the output of the antenna.EFFECT: high accuracy of determining coordinates of a noisy target.1 cl, 7 dwg

Description

The invention relates to the field of hydroacoustics, and in particular to methods and devices for detecting marine targets by their sound emission.

One of the urgent practical tasks of hydroacoustics is to determine the coordinates of a sea noisy target (hereinafter referred to as the target) according to the data of the direction finding station (hereinafter referred to as ShPS). To solve this problem, a large number of methods are known, an overview of which is given in [1].

One of the methods is based on the use of the measured autocorrelation function (ACF) of a broadband acoustic signal (hereinafter referred to as the signal) to determine the coordinates (distance and depth) of its source [1-6]. Information on the coordinates of the signal source (target) in the measured ACF is contained in the location on the abscissa (time) axis of narrow-band interference maxima (hereinafter referred to as MI) due to interference of the correlated source signals arriving at the input of the receiving sonar antenna (hereinafter referred to as antennas) of the NPS on different beams . Each pair of beams in the ACF (with a sufficient signal / noise ratio (hereinafter referred to as SIR) [7, 8]) corresponds to one IM with a width equal to the reciprocal of the effective frequency band of the signal at the antenna input and a position on the abscissa equal to the absolute value of the difference signal propagation times through interfering rays. In FIG. Figure 1 shows, by way of illustration, the ACF of the source signal arriving at the antenna through four acoustic beams.

The determination of the coordinates of the signal source by the considered method consists in searching for the position of the signal source by distance and depth, for which the calculation of the parameters of the acoustic rays using the acoustic calculation program [9] shows the presence in the ACF of the antenna output MI, the number of which and the location on the abscissa axis are as close as possible the number and location of MI in the measured ACF.

Modeling and experimental testing of this method showed that it is objectively inherent in the ambiguity in determining the location of the signal source in a number of hydroacoustic conditions. In this case, the ambiguity manifests itself less often, the more compact the region of space in distance and depth in the vicinity of the actual coordinates of the source, in which the search for the position of the signal source is performed.

изображены результаты определения рассматриваемым способом координат источника сигнала на 14-ти последовательных интервалах времени в условиях дальних зон акустической освещенности (ДЗАО). Маркер

демонстрирует фактическое положение источника сигнала в 1-й ДЗАО на дистанции 47 м и на глубине 198 м. Соответствующее этим условиям вертикальное распределение скорости звука (ВРСЗ), используемое программой гидроакустических расчетов, изображено на фиг. 3. Ввиду отсутствия априорной информации о классе цели, поиск ее координат осуществлялся в широкой области: по дистанции в 1-й (40-55 км) и 2-й (80-110 км) ДЗАО, по глубине в интервале 5-300 м.This fact is illustrated by the example in FIG. 2 on which markers

The results of determining the coordinates of the signal source in 14 consecutive time intervals in the conditions of far zones of acoustic illumination (DZAO) are shown. Marker

demonstrates the actual position of the signal source in the 1st DZAO at a distance of 47 m and at a depth of 198 m. The vertical distribution of sound velocity (ARSS) used by the hydroacoustic calculation program corresponding to these conditions is shown in FIG. 3. Due to the lack of a priori information about the target class, its coordinates were searched for in a wide area: by distance in the 1st (40-55 km) and 2nd (80-110 km) DZAO, in depth in the interval 5-300 m .

From consideration of FIG. 2 follows:

), а в 4-х случаях оно оказалось вместо 1-й ДЗАО во 2-й ДЗАО и на значительно меньших глубинах по сравнению с фактической глубиной источника сигнала;- in 10 cases, the calculated location of the signal source lies close to its actual location (marked with a marker

), and in 4 cases it turned out to be instead of the 1st DZAO in the 2nd DZAO and at much shallower depths compared to the actual depth of the signal source;

- if the location of the signal source was searched only in the 1st DZAO (i.e., in the range of distances of 45-55 km), large errors could be avoided.

As a prototype method, we select the invention [10]. In FIG. 4 shows its block diagram. Processing of incoming information is carried out along two parallel branches. The first (left) branch includes sequentially performed operations of detecting the broadband signal of the target at the output of the antenna (block 1.1); measuring the ACF set of the detected broadband target signal at time intervals that make up the analysis interval (block 1.2); detection of narrowband MI in each measured ACF and measuring their abscissas (block 1.3); combining the abscissas of MI found in all measured ACF of the analysis interval into a single array (block 1.4). Performing the above operations ensures the formation of an array of all MIs measured on the analysis interval and ready for comparison with the calculated data generated by the blocks of the second branch.

The second branch (right) includes the operations of determining the area of the possible location of the target in the space "distance - depth" (block 2.1); calculations for each point of this region, taking into account the current hydroacoustic conditions of the beam structure of the signal at the input of the ShPS antenna, (block 2.2); computing for each point of this region and for each pair of rays of the calculated radiation structure the values of the abscissa and signal-to-noise ratio (SIR) of the MI generated by this pair of rays (calculated MI) (block 2.3) and the operation of generating for each point of the region an array of calculated MI which calculated OSBs exceed a predetermined threshold value for their detection in the ACF (block 2.4). The operations of the second branch can be performed once for the current state of hydrological conditions, which determines the beam structure of the signals at the input of the antenna. Performing operations of the second branch ensures the formation of an array of calculated data ready for comparison with the measurement results generated by the first branch.

The comparison is performed by sequentially placed blocks 3 and 4, performing the determination operations in arrays of calculated MIs, formed for each point in space, the number of MIs, the abscissas of which, taking into account the accuracy of their measurement, are equal to the MI abscissas in the combined array of MIs found in the entire set of ACFs measured over the interval analysis (block 3) and, finally, the operation of determining the coordinates of the target by selecting the coordinates of that point of the possible location of the target in the "distance - depth" space, which corresponds to the largest number of calculated MIs whose abscissas are equal to the MI abscissas in the combined array of MIs found in the whole set measured ACF (block 4).

The disadvantage of the prototype method is the possibility of abnormally large errors in determining the coordinates of the target due to the arbitrary selection of the area in the space "distance - depth", in which the coordinates of the target are determined.

The technical problem to be solved is an increase in the operational characteristics of the noise-detecting station.

The technical result provided by the invention is to increase the accuracy of determining the coordinates of a sea noisy target.

The specified technical result is achieved by determining the most compact area of the possible location of the target in the space "distance - depth", in which the coordinates of the source are further determined according to the prototype method. To determine this area, one of the known methods for determining the coordinates of the signal source is used, which give a less accurate (compared to the considered method), but unambiguous result.

As such a method, we choose a method described by the following sequence of actions [1].

сигнала обнаруженной цели на входе антенны в рабочей полосе частот Δƒ = ƒ_в - ƒ_н, где ƒ_в, ƒ_н - соответственно верхняя и нижняя граничные частоты рабочей полосы частот.1) Pressure is measured

the signal of the detected target at the antenna input in the working frequency band Δƒ = ƒ _in - ƒ _n , where ƒ _in , ƒ _n are the upper and lower boundary frequencies of the working frequency band, respectively.

2) One of the known methods [11-18] defines the class K of the target (for example, a submarine, surface ship).

3) The interval [H _min , H _max ] of possible immersion depths of the class K target is determined. This is achieved by solving the equation for H _min and H _max

given that

Where

g _H (h) is the probability distribution density (PRD) of the target depth corresponding to class K;

P _H is the given probability of the actual depth of the target falling into the interval [H _min , H _max ].

Formulas (1) and (2) mean that the depth boundaries should be such that the probability of finding the actual depth of the signal source in them is equal to the given probability P _H and the depth interval would be the minimum possible.

4) The interval [R _min , R _max ] of possible distances to the target is determined by solving the equation for R _mm and R _max

given that

Where

P _R - the given probability of getting the actual distance R to the sea noisy target in the interval [R _min , R _max ];

- условная (в зависимости от измеренного давления

сигнала цели в рабочей полосе частот на входе антенны) ПРВ фактической дистанции R до морской шумящей цели, вычисляемая по формуле [19]

- conditional (depending on the measured pressure

target signal in the working frequency band at the antenna input) PRV of the actual distance R to the sea noisy target, calculated by the formula [19]

;r, r '- nonrandom arguments

;

- ПРВ давления шума цели класса K в рабочем диапазоне частот антенны Δƒ, приведенного к расстоянию 1 м от цели;

- PRV of the noise pressure of a class K target in the operating frequency range of the antenna Δƒ, reduced to a distance of 1 m from the target;

W (g) is the dependence of the signal pressure drop on the distance in the working frequency range of the antenna, calculated for current sonar conditions;

.g _ΔP (x) - PRV errors ΔP measure the signal pressure of the target

.

Formulas (3) and (4) mean that the distance boundaries must be such that the probability of finding the actual distance to the source in them is equal to the given probability P _R and the distance interval

was the least possible.

5) As a result, enumeration of points of a possible target location is performed in the interval [H _min , H _max ] in depth and in the interval [R _min , R _max ] in distance.

A block diagram of the functioning of the proposed method is shown in FIG. 5. Processing of incoming information is carried out along two parallel branches. The first (left) branch includes sequentially performed operations of detecting the broadband signal of the target at the output of the antenna (block 1.1); measuring the ACF set of the detected broadband target signal at time intervals that make up the analysis interval (block 1.2); detection of narrowband MI in each measured ACF and measuring their abscissas (block 1.3); combining the abscissas of MI found in all measured ACF of the analysis interval into a single array (block 1.4). Performing the above operations ensures the formation of an array of all MIs measured on the analysis interval and ready for comparison with the calculated data generated by the blocks of the second branch.

The second branch (right) begins with the definition of the class of the detected target (block 2.1). Methods for determining the class of the detected target are described in [11-18]. In block 2.2, the pressure of the target signal is measured in the operating frequency range of the receiving antenna according to the algorithm described in [20]. In block 2.3, using the formulas (1) ... (5), the boundaries of the regions are determined by depth and distance in which the coordinates of the target will be determined. For each point in this region, taking into account the current hydroacoustic conditions, the beam structure of the signal at the input of the antenna is calculated (block 2.4). Further, for each point of this region and for each pair of rays of the calculated ray structure, the abscissa and the SIR of the MI generated by this pair of rays (calculated MI) are calculated (block 2.5). Then, for each point of the region, an array of calculated MIs is formed, for which the calculated SIRs exceed the specified threshold value for their detection in the ACF (block 2.6). The operations of the second branch can be performed once for the current state of hydrological conditions, which determines the beam structure of the signals at the input of the antenna. Performing operations of the second branch ensures the formation of an array of calculated data ready for comparison with the measurement results generated by the first branch.

The comparison is performed by sequentially placed blocks 3 and 4, performing the determination operations in arrays of calculated MIs, formed for each point in space, the number of MIs, the abscissas of which, taking into account the accuracy of their measurement, are equal to the MI abscissas in the combined array of MIs found in the entire set of ACFs measured over the interval analysis (block 3) and, finally, the operation of determining the coordinates of the target by selecting the coordinates of that point of the possible location of the target in the "distance - depth" space, which corresponds to the largest number of calculated MIs whose abscissas are equal to the MI abscissas in the combined array of MIs found in the whole set measured ACF (block 4).

Check the effectiveness of the proposed method for the conditions of the above example (Fig. 2 and 3).

In this example, a submarine (PL) located in the 1st DZAO at a distance of 47 km from the receiving antenna and at a depth of 198 m was considered as the signal source. The noise pressure of the submarine in the frequency band 2-4 kHz, reduced to a distance of 1 m from target is 58.5 dB.

на входе антенны в полосе частот Δƒ 2-4 кГц. Пусть это давление составило 1,6 дБ.ШПС, the antenna of which is located at a depth of 116 m, detects the noise signal of the target and measures its pressure

at the antenna input in the frequency band Δƒ 2-4 kHz. Let this pressure be 1.6 dB.

Under the conditions of the DZAO, the classification into the classes “submarine - surface ship” is most effectively carried out according to the angle in the vertical plane of the maximum signal arrival to the receiving antenna of the target: the submarine signal, depending on its depth, arrives at the antenna in the range of vertical angles from -5 ° to + 5 ° ; the surface ship signal comes from above or below at an angle of more than 5 ° [21]. This fact for the hydroacoustic conditions under consideration is illustrated in FIG. 6, which shows the dependences of the angles of arrival of the source signal at the receiving antenna for the conditions of the DZAO. From consideration of FIG. 6 it follows that at all distances, including in the regions of the Far Eastern Administrative District, in the immediate vicinity of the vertical angle of 0 °, only the signal of a deeply immersed object can come, i.e. Sub. In our case, measuring the angle of arrival of the maximum signal at the antenna gives + 1 °, which indicates that the detected target is a submarine.

The PRV g _H (h) of the depth of the submarine in the deep sea is described by a limited normal law with the following parameters: minimum depth 50 m, maximum depth 300 m, mathematical expectation (MO) of a depth of 150 m, standard deviation (RMS) of a depth of 70 m. Substituting this The PRV in the formula (1), taking into account condition (2) for a given probability P _H = 0.9, we obtain: H _min = 58 m, H _max = 280 m.

максимальная шумность

МО

СКО

В результате ПРВ

давления ее шумоизлучения в полосе частот 2-4 кГц будет распределена также по ограниченному нормальному закону в интервале 78-93 дБ с МО 85 дБ и СКО 3 дБ. ПРВ g_ΔP (х) ошибки ΔР измерения давления

сигнала цели на входе антенны аппроксимируется нормальным законом с нулевым МО и СКО 3 дБ. Вычислим для заданных гидроакустических условий передаточную характеристику канала распространения сигнала W (r).The PRV of reduced submarine noise at a low noise speed is approximated by a limited normal law with the parameters: minimum noise

maximum noise

MO

SKO

As a result of PRV

the pressure of its noise emission in the frequency range 2-4 kHz will also be distributed according to the limited normal law in the range of 78-93 dB with MO 85 dB and RMS 3 dB. PDP g _ΔP (x) error ΔP pressure measurement

The target signal at the antenna input is approximated by a normal law with zero MO and a standard deviation of 3 dB. For given hydroacoustic conditions, we calculate the transfer characteristic of the signal propagation channel W (r).

Substituting the obtained dependences into formulas (5) and (3), taking into account condition (4) for a given probability P _H = 0.9, we obtain: R _min = 42 km, R _max = 54 km.

Performing enumeration of points of a possible target location in the interval [58; 280] m in depth and in the interval [42; 54] km over the distance, we will be convinced (Fig. 7) that when choosing the search area for the coordinates of a noisy object using the proposed method, all 14 estimates of the coordinates of the noise source are located closely around the actual location of the source.

Thus, the claimed technical result - improving the accuracy of determining the coordinates of a noisy target based on the information contained in the ACF of its signal - can be considered achieved.

Sources of information:

1. Mashoshin A.I. Synthesis of the optimal algorithm for the passive determination of the distance to the target // Marine Radioelectronics. 2012. No2 (40). S. 30-34.

2. Hassab I. C. Contact Localization and Motion Analysis in the Ocean Environment: a Perspective // IEEE Journal of Oceanic Engineering. 1983. Vol. OE-8, No. 3. P. 136-147.

3. Quazi A.H., Lerro D.T. Passive localization using time-delay estimates with sensor positional errors // JASA. 1985. Vol. 78, No. 5. P. 1664-1670.

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5. Orlov E.F., Fokin B.H., Sharonov G.A. The study of the parameters of interference modulation of broadband sound in the deep ocean // Acoustic journal. 1988.V. 34, no. 5, pp. 902-907.

6. Lazarev V.A., Orlov E.F., Fokin V.N., Sharonov G.A. Frequency dependence of the parameters of interference modulation of broadband sound in a shallow sea // Acoustic Journal. 1989. Volume 35, no. 4, p. 685-688.

7. Mashoshin A.I. Interference immunity of maximums in the correlation function of the broadband noise signal of a marine object due to multipath signal propagation in the aquatic environment // Acoustic Journal. 2001. Volume 47, No. 6. S. 823-829.

8. Mashoshin A.I. Investigation of the applicability conditions of the correlation function of a broadband multipath signal for estimating the source coordinates // Acoustic Journal. 2017. Volume 63, No. 3. S. 307-313.

9. Certificate of state registration of computer programs No. 2008612137 dated April 29, 2008 "LUNA".

10. RF patent No. 2 690 223 with priority dated 08/28/2018 by application No. 2018131060. A method for determining the coordinates of a sea noisy target.

11. Telyatnikov V.I. Methods and devices for the classification of hydroacoustic signals // Foreign Radio Electronics, 1979, No. 9, p. 19-38.

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13. Mashoshin A.I. Features of the synthesis of algorithms for classifying marine objects by their sonar field // Marine Radioelectronics, 2009, No. 2 (28), p. 8-12.

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Claims (19)

A method for determining the coordinates of a sea noisy target, including detecting a broadband target signal at the output of the noise finder, measuring its autocorrelation function (ACF) at each of a series of successive time intervals, detecting narrow-band interference maxima (MI) in each measured ACF, measuring their abscissas, combining them into a single an array of all IMs detected in the ACF at a number of consecutive time intervals, enumerating points of the possible target location in the distance – depth space, calculating for each point, taking into account the current hydroacoustic conditions of the beam structure of the signal at the input of the hydroacoustic antenna of the noise finder, calculating for each possible pair of rays the calculated radial structure of the abscissas and the signal-to-noise ratio of the calculated MI that is formed in the ACF by this pair of rays, the formation for all pairs of rays of an array of calculated MI, the calculated signal-to-noise ratios exceed the specified threshold value for their detection in the ACF, about distribution of the number of MIs in the formed array, the abscissas of which, taking into account the accuracy of their measurement, are equal to the MI abscissas in the combined array of all MIs found in the ACF at a number of consecutive time intervals, taking the coordinates of that point in the “distance - depth” space as the target’s coordinates , which corresponds to the largest number of MI, the abscissas of which are equal to the abscissas of the MI found in the combined array of all MI found in the ACF at a number of consecutive time intervals, characterized in that the pressure is additionally measured

the signal of the marine noise target at the antenna input, determine the class K of the marine noise target, determine the minimum H _min and maximum H _max depth of the marine noise target by solving the equation for H _mjn and H _max

given that

, Where g _H (h) is the probability distribution density (PRD) of the depth of the sea noisy class K target, P _H - the given probability of falling the actual depth of the sea noisy target in the interval [H _min , H _max ], determine the minimum R _min and maximum R _max distance finding the sea noisy target by solving relative to R _min and R _max equation

given that

, Where

- conditional (depending on pressure

signal at the input of the receiving antenna) PRV distance R to the sea noisy target, calculated by the formula

, r, r '- arguments PRV distance R; g _Δƒ (p) - PRV of the noise pressure of a marine noisy class K target in the operating frequency range of the receiving antenna at a distance of 1 m from the source, W (r) is the transfer characteristic of the signal propagation channel, calculated for the current sonar conditions, g _ΔP (x) - PRV errors ΔP measuring the pressure of the signal in the operating frequency range of the receiving antenna, P _R - the given probability of getting the actual distance to the sea noisy target in the interval [R _min , R _max ], enumeration of points of a possible target location in the “distance - depth” space is performed in the interval [H _min , H _max ] in depth and in the interval [R _min , R _max ] in distance.

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