Optimization method of vertical array transmitting beam based on convergence zone sound ray angle energy spectrum

Abstract

The present application relates to a kind of vertical array emission beam optimization method based on convergence zone sound ray angle energy spectrum, due to deep sea environment, the front phase of vertical emission array sound field convergence zone is neat sound ray dense, and sound intensity has approached emission beam regulation upper limit, and the average sound intensity of the phase dispersion sound ray sparse as adjustable control area in the rear section of convergence zone has greater potential for improvement.It is expected to emit beam with the sound ray angle energy spectrum of convergence zone, and the main lobe fitting and side lobe control strategy is used to optimize the design of vertical emission array emission beam weight, to realize the maximum average sound intensity of emission energy in adjustable control area.Compared with the traditional beam forming method, the vertical emission array emission beam optimization design method proposed in the present application can effectively improve the average sound intensity in the adjustable control area of convergence zone under the same emission power, improve the detection distance of sonar, provide important technical support for deep sea active sonar detection, and have wide application prospect.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of active sonar detection, and relates to a vertical array transmitting beam optimization method based on the angle energy spectrum of sound rays in the convergence zone, which is suitable for improving the radiation intensity in the convergence zone and the detection distance when the active sonar transmitting system is used for deep-sea long-range detection. BACKGROUND

[0002] At present, active and passive sonars mainly use surface waveguide mode, convergence zone mode and seabed bounce mode for target detection in deep-sea environment. Most of these methods focus on the arrangement of sonar receiving end and signal processing, while the optimization research on the sound channel propagation characteristics of the sonar transmitting end is relatively less. Since the distribution characteristics of deep-sea sound field are affected by the coupling of sound propagation mode and excitation process of the transmitting end, if the sound field characteristics are fully considered in the design of transmitting beam, and the deep-sea sound propagation characteristics are used to improve the target detection capability, the transmitting gain and detection distance will be significantly improved.

[0003] Some early studies have tried to apply sound field characteristics to the transmitting end. Guo FQ et al. achieved sound energy focusing at the desired position outside the sound source by using a depth and distance variable time reversal focusing method based on modal extraction (Guo FQ, Yang YX, Sun C. A depth and distance variable time reversal focusing method based on modal extraction [J]. Acta Acustica, 2010, 35(4): 403-413.). Yi XF et al. proposed a multi-modal focusing method, which used multi-mode control transmission to concentrate sound field energy into the first three modes in shallow water environment, reducing the influence of environmental mismatch on sound energy focusing (Yi XF, Peng DY, Hou QN, et al. Multi-mode sound field focusing of low-frequency vertical phased array in shallow water [J]. Applied Acoustics, 2019, 38(04): 615-622.). However, these methods are mainly based on shallow water environment and need feedback arrays with full water depth sampling, which has a great limitation in deep-sea environment.

[0004] In recent years, Han ZB et al. from the University of Chinese Academy of Sciences proposed a method of optimizing the beam elevation angle of active sonar by using the peak value of sound ray cluster, which achieved significant transmitting array gain in the deep-sea seabed reflection zone (Han ZB, Peng CH, Liu XT. Analysis of sound field angular spectrum domain distribution structure in deep-sea seabed reflection zone and its application to sonar beam elevation [J]. Acta Physica Sinica, 2020, 69(11): 207-218). This study initially considered the characteristics of deep-sea sound propagation, but mainly analyzed the seabed reflection zone, and there was little research on the convergence zone mode in deep-sea long-range detection environment. Overall, the research on transmitting end sonar control technology in deep-sea environment is still scattered at home and abroad, and there is a lack of systematic theoretical support and technical framework. Therefore, it is necessary to further study the vertical transmitting array transmitting beam optimization method using the convergence zone sound field characteristics to improve the deep-sea long-range detection capability. SUMMARY

[0005] Technical problems to be solved

[0006] In order to avoid the shortcomings of the prior art, the present application provides a vertical array emission beam optimization method based on the convergence zone sound ray angle energy spectrum. The ray acoustics theory points out that the sound rays emitted from the sound source at different angles are constantly reversed within a certain depth range when propagating to a long distance, and the convergence zone is formed at the focal line of the sound rays. The number of these reversed sound rays and the energy carried by them determine the distribution of sound energy in the convergence zone. This distribution will directly affect the actual emission regulation and the sound energy focusing effect. The phase of the sound field in the front section of the convergence zone of the vertical emission array of the active sonar system is uniform, and the sound intensity is close to the upper limit of the emission regulation. The phase of the sound field in the rear section of the convergence zone is scattered, and the sound intensity in the adjustable region has great potential for improvement. The present application provides a vertical emission array emission beam optimization design method based on the convergence zone sound ray angle energy spectrum. This method uses the deep sea sound propagation characteristics and the sound field structure characteristics to give the division criterion of the adjustable region of the convergence zone sound intensity. Taking the convergence zone sound ray angle energy spectrum as the expected beam of the emission beam, using the main lobe fitting and side lobe control strategy, the emission beam weight of the vertical emission array is optimized and designed, the average sound intensity in the adjustable region is maximized, and the detection distance of the active sonar is effectively improved.

[0007] Technical scheme

[0008] A vertical array emission beam optimization method based on the convergence zone sound ray angle energy spectrum, characterized by the following steps:

[0009] Step 1: According to the deep sea sound speed profile and the vertical emission array parameters, the convergence zone sound field conjugate correlation |ρ w (r,z s ) is calculated, and the convergence zone sound intensity adjustable region C i ={r|r th >r>r2} is divided, where r is the horizontal distance of the sound field to the vertical array, the adjustable region range is the segmentation distance r th to the end distance r2;

[0010] Step 2: According to the ocean environment parameters, the convergence zone sound intensity adjustable region C i angle energy spectrum is calculated, the emission beam is designed, and the corresponding design weighting vector w s of each emission pointing angle β s is obtained.

[0011] Step 3: When the optimized weighting vector of each emission beam pointing angle is emitted, the average sound intensity of each convergence zone adjustable region after weighting regulation is obtained according to the sound intensity of each convergence zone.

[0012] Step 4: Through global optimization, the optimal weighting vector corresponding to each convergence region is obtained, and the optimized vertical array transmission beam is obtained.

[0013] The process of step 1 is as follows:

[0014] Step 1.1: Simulate and calculate the emitted sound field of the vertical transmission array: deployment depth is z n The sound pressure of the array element excitation sound field at (r,z) is expressed as p(r,z,z). n The sound pressure vector generated by the N-element transducer vertical emission array is:

[0015] p=[p(r,z,z1),p(r,z,z2),…,p(r,z,z N )] T ;

[0016] Step 1.2: Calculate the optimal weighting vector w at different locations in the sound field of the vertical transmission array. opt ;

[0017] First, calculate the depth z of the center of the vertical launch array. s The total sound pressure level p at the location N (r,z s )

[0018] p N (r,z s ) = w H p

[0019] In the formula, w is the weighting vector, and p is the spatial position (r, z) of each transducer in the vertical emission array. s The sound pressure vector formed by the sound pressure at point z s r is the depth of the center of the vertical launch array, and r is the horizontal distance.

[0020] Then calculate the spatial position (r, z) s The theoretical upper limit of sound intensity I after conjugate weighting at ) opt (r,z):

[0021]

[0022] Obtain the optimal weighted vector w at the corresponding position. opt :

[0023]

[0024] Step 1.3: Calculate the conjugate correlation of the sound field and use the conjugate correlation of the sound field to divide the convergence region:

[0025] Calculate the conjugate correlation |ρ under natural pointing emission w (r,z)|:

[0026]

[0027] After simplifying, we have:

[0028] where w avg is a uniform weighting vector, p * (r,z) is the conjugate vector of the sound pressure vector, representing the vector composed of the conjugate sound pressure of each transducer in the vertical transmitting array at the spatial position (r,z);

[0029] For the ith convergence zone, the horizontal range of the control zone is:

[0030] C i = {r | r th > r > r2}.

[0031] The process of step 2 is:

[0032] Step 2.1: Calculate the angle energy spectrum of the convergence zone: where A(θ,r) is the sound ray amplitude at the depth z s , distance r, and C i is the horizontal distance range of the adjustable zone of the ith convergence zone.

[0033] Step 2.2: Design the transmitting beam: Let the beam steering angle range β s ∈ [-90°, 90°], with the positive transverse direction as 0° and pointing below the horizontal plane as positive; let θ j ∈ Θ (j = 1,..., J) be the discretized azimuth points in the azimuth region Θ = [-90°, 90°], and J be the number of azimuth points; the main lobe is designed by the sound ray angle energy spectrum obtained above, while the side lobe level is suppressed, and the desired main lobe beam response vector B d (Θ) is:

[0034] B d (Θ) ≈ [E i (θ1),...,E i (θ j ),...,E i (θ J )], θ j ∈ Θ ML

[0035] Using the side lobe control-main lobe minimum mean square error criterion, the design beam weighting vector w s is solved to satisfy:

[0036]

[0037] Where SLL is the specified sidelobe level, B d (Θ) represents the desired beam response, Θ ML ,Θ SL These are the main lobe region and the side lobe region, respectively, representing the angle. i Let θ be the corresponding angular element of the error weighting vector λ. Let a(Θ) be the array manifold vector, where k is the wave number and d is the element spacing.

[0038] The array manifold vector:

[0039]

[0040] Step 2.3: Calculate the main lobe center pointing angle β s =0° corresponding to the design weighting vector w s Set the main lobe region to Θ ML ∈[-20,20], the sidelobe region is Θ SL ∈[-90°,-20°)∪(20°,90°], the error weighting vector is unit weighted, i.e., λ=1 1×M Using the CVX toolbox, the input parameters are used to solve the optimization problem, and the main lobe center pointing angle β is obtained. s =0° corresponding to the design weighting vector w s ;

[0041] Step 2.4: Traverse the main lobe center pointing angle β s , in β s Within the range of [-20°, 20°], maintain B d (Θ) Main lobe shape remains unchanged, angular range of the main lobe region being moved Θ ML Point the center of the main lobe towards angle β s Iterate through [-20°, 20]. For each β s B obtained d (Θ), repeat step 3 to obtain the design weighted vector w corresponding to each launch pointing angle. s .

[0042] The process of step 3 is as follows:

[0043] Step 3.1: Calculate the sound pressure at position (r,z) in space according to ray theory, where p(r,z) represents the sound field excited by the point sound source.

[0044]

[0045] In the formula, A m Let m be the amplitude of the m-th vocal ray, and k be the wave number. The phase of the m-th vocal ray;

[0046] Calculate the total sound pressure level of the N-element vertical emission array based on the principle of linear sound field superposition:

[0047]

[0048] In the formula, w s,n p represents the weighting coefficient for the nth transducer. n (r,z) represents the sound pressure of the nth transducer at spatial position (r,z);

[0049] Step 3.2: Calculate the weighted vector w for different pointing angles. s Average acoustic intensity in the rear section of the convergence zone after launch for:

[0050]

[0051] In the formula, and These are the conjugate correlation segmentation distance and termination distance of the controllable region of the Kth convergent region, respectively.

[0052] The process of step 4 is as follows:

[0053] Step 4.1: Using a global optimization method, calculate the average sound intensity of each emission direction angle emitted at the rear of the corresponding convergence zone;

[0054] Step 4.2: Select the option that maximizes the average sound intensity The largest weighted vector w s As the best choice;

[0055] Obtain the optimal weighted vector w corresponding to each convergence region s and maximum average sound intensity

[0056] The deployment depth is the depth of the center of the launch array.

[0057] The emitted sound field p, sound pressure vector p(r,z), and ray information A(θ,r) of the vertical emission array were obtained by simulation calculation using the Bellhop module of MATLAB.

[0058] The boundary r between the high conjugate correlation region and the low conjugate correlation region of the convergence region th =min{r||ρ w | peak (r,z s )≤0.707}.

[0059] An electronic device, characterized in that it includes a processor and a memory, the processor being configured to execute a computer program stored in the memory to implement the steps of the vertical array emission beam optimization method based on the convergent region acoustic ray angle energy spectrum.

[0060] A computer program product characterized in comprising computer executable instructions for implementing the vertical array transmit beam optimization method based on the convergence zone sound ray angle energy spectrum when executed.

[0061] Advantages

[0062] The vertical array transmit beam optimization method based on the convergence zone sound ray angle energy spectrum proposed by the application, since in the deep sea environment, the front phase uniform sound rays are dense in the convergence zone of the vertical transmit array sound field, and the sound intensity has approached the upper limit of the transmit beam regulation, while the phase scattered sound rays are sparse in the rear convergence zone of the sound field, and the average sound intensity in the adjustable region has a great potential for improvement. The application takes the convergence zone sound ray angle energy spectrum as the transmit expected beam, adopts the main lobe fitting and side lobe control strategy, optimizes the design of the vertical transmit array transmit beam weight value, and realizes the maximization of the average sound intensity of the transmit energy in the adjustable region. Compared with the traditional beam forming method, the vertical transmit array transmit beam optimization design method proposed by the application can effectively improve the average sound intensity in the adjustable region of the convergence zone under the same transmit power, improve the sonar detection distance, provide important technical support for deep sea active sonar detection, and has a wide application prospect.

[0063] The specific advantages are embodied in:

[0064] 1. The method uses the inherent sound propagation law of the deep sea sound field, the coupling relationship between the sound ray arrival structure and the transmission regulation, and gives the best weighting vector of the vertical transmit array in each convergence zone, thereby increasing the average sound intensity of the adjustable region of the convergence zone sound field. The design of the weighting vector of the vertical transmit array in the deep sea convergence zone detection has certain guiding significance.

[0065] 2. The transmit beam is designed in combination with the sound ray angle energy spectrum in the convergence zone. The main lobe region of the designed beam is fitted with the sound ray angle-energy distribution spectrum in the convergence zone, which reduces the energy loss of part of the inverted sound rays from the beam side lobe or groove when the natural direct transmit is used, improves the total sound energy carried by the inverted sound rays when they exit the convergence zone, and thus effectively improves the average sound intensity in the rear convergence zone; when the best weighting vector is used, the average sound intensity level in the adjustable region of the convergence zone is significantly increased, and the long-range detection distance is effectively improved. BRIEF DESCRIPTION OF DRAWINGS

[0066] Figure 1 It is a flowchart of the method of the application;

[0067] Figure 2 It is a diagram of the natural direct transmit sound intensity distribution of the vertical transmit array transmit sound field under the typical deep sea sound speed profile in the South China Sea;

[0068] Figure 3 It is the division result of the adjustable region of the convergence zone

[0069] Figure 4 For the invention example in Figure 2 The fifth convergence zone can control the sound line angle energy spectrum in the area under the environment;

[0070] Figure 5 For the invention example, the beam is designed and compared with the natural pointing emission beam (taking 0° as an example);

[0071] Figure 6 For the invention example, the first to fifth convergence zone corresponding to the optimal design beam and the natural pointing emission beam emission propagation loss change comparison chart;

[0072] (a) first convergence zone, (b) second convergence zone, (c) third convergence zone, (d) fourth convergence zone, (e) fifth convergence zone. DETAILED DESCRIPTION

[0073] The present application will be further described in conjunction with the embodiments, drawings:

[0074] Because the ray acoustics theory points out that the sound lines of different angles emitted from the sound source are constantly reversed in a certain depth range when propagating to a long distance, and the convergence zone is formed at the focal line of the sound line. The number of these reversed sound lines and the energy they carry determine the distribution of the convergence zone sound energy. This distribution will directly affect the actual emission control and sound energy focusing effect. The phase of the vertical emission array sound field in the convergence zone is neat and the sound lines are dense in the front section, and the sound intensity has approached the upper limit of emission control, while the sound field in the rear section is phase scattered and the sound lines are sparse, and as a controllable area, the emission intensity has great potential for improvement. The present application proposes a vertical emission array emission beam optimization design method based on the convergence zone sound line angle energy spectrum. This method uses the deep sea sound propagation characteristics and the sound field structure characteristics to give the division criterion of the convergence zone sound intensity controllable area. Taking the convergence zone sound line angle energy spectrum as the expected beam of the emission beam, the main lobe fitting and side lobe control strategy is adopted to optimize the design of the vertical emission array emission beam weight, so as to realize the maximization of the average sound intensity of the emission energy in the controllable area, and effectively improve the detection distance of the active sonar.

[0075] As Figure 1 shown, the technical scheme adopted by the present application to solve its technical problems includes the following steps:

[0076] Step 1: According to the deep sea sound velocity profile and the vertical emission array parameters, the convergence zone sound field conjugate correlation is calculated and the convergence zone sound intensity controllable area is divided.

[0077] The sound pressure of the array element excited sound field at (r,z) with a laying depth of z n can be expressed as p(r,z,z n), the sound pressure excited by a vertical array of N transducers can be expressed as a sound pressure vector p = [p(r, z, z1), p(r, z, z2), …, p(r, z, zN)]T, where p(r, z, zj) is the sound pressure at the distance r and depth z of the jth transducer. N ) T When the weighting vector w is the conjugate vector p * (r, z) of the sound pressure vector p at the position (r, z) of the copy field, the phases of the sound pressures of each element of the sound field can be aligned, and the theoretical sound intensity upper limit I opt (r, z s ) after weighting is obtained, and the corresponding weight vector is w opt . The correlation between the natural directivity weighting coefficient and the optimal conjugate weighting coefficient is defined as the conjugate correlation |p w |(r, z), which quantitatively describes the upper limit of the weighting control gain at a certain position in the sound field emitted by the vertical array. In the low conjugate correlation region, the phases of the elements of the sound pressure vector p of the sound field are scattered, and a larger sound intensity can be obtained through weighting control. Therefore, the convergence region is divided by the conjugate correlation of the sound field, and the low conjugate correlation region is used as the emission controllable region.

[0078] Substep one: Calculate the conjugate correlation distribution of the sound field

[0079] Only the total sound pressure p s (r, z N ) at the center depth z s of the vertical array is considered, which can be obtained by summing the sound pressures of the z s depth elements at the same distance but different element depths z n .

[0080]

[0081] Under the condition of constant emission power, the total sound intensity I(r, z) after conjugate weighting satisfies I(r, z)≤I opt (r, z), and the corresponding conjugate upper limit sound intensity is I w (r, z) and the conjugate weighting vector.

[0082]

[0083] Substep two: Divide the convergence region using the conjugate correlation of the sound field to obtain the range of the sound intensity controllable region of the convergence region.

[0084] The conjugate correlation |p w |(r, z) of the sound field (r, z) under natural directivity emission is calculated as follows.

[0085]

[0086] The emission weighting coefficient w arg under natural directivity emission is calculated. To ensure consistent emission power, the modulus of w is 1.

[0087]

[0088] Where N is the number of vertical emission array elements, I N It is a unit vector of length N.

[0089] The emitted sound field of the vertical emission array was simulated using the Bellhop module of the MATLAB acoustic toolbox to obtain the sound pressure vector p(r,z) of the vertical emission array. The conjugate correlation of the sound field in the region with the same depth as the center of the vertical emission array was calculated using formula (4).

[0090]

[0091] Get |ρ w |(r,z s The curve has n peaks |ρ within a certain convergence region. w | peak (r n ,z s ), where r n This represents the distance corresponding to the wave crest. The conjugate correlation coefficient |ρ w |(r,z s The value is distributed in the range [0,1], and the minimum distance r among the coordinates of all peaks with amplitudes less than 0.707 is... n The distance boundary r between the high conjugate correlation region and the low conjugate correlation region of this convergence area was selected. th .

[0092] r th =min{r n ||ρ w | peak (r n ,z s )≤0.707} (7)

[0093] The convergence zone is divided according to horizontal distance, and the controllable range of the convergence zone is the dividing distance r. th Distance to the end r2.

[0094] Step 2: Calculate the convergence zone angle energy spectrum based on marine environmental parameters, and design the transmission beam.

[0095] Sub-step 1: Calculate the angular energy spectrum of the convergence region

[0096] The Bellhop module of the acoustic toolbox in MATLAB simulation software was used to simulate the emitted sound field of a vertical emission array, and the ray information A(θ,z) reaching the rear section of different convergence regions was statistically analyzed. s ), A(θ,z) s () is a sound ray with an exit angle of θ at a sound source depth z.s The angle energy spectrum of the corresponding convergence zone angle is obtained by adding the amplitudes of the sound rays with the same exit angle.

[0097]

[0098] where E i (θ) represents the angle energy spectrum of the sound rays with exit angle θ in the rear section of the ith convergence zone.

[0099] Sub-step two: design the transmitting beam

[0100] Let the beam control angle range of the vertical transmitting array be β s ∈[-90°, 90°], with the positive transverse direction of the vertical transmitting array being 0° and the direction below the horizontal plane being positive. When the beam control pointing angle of the transmitting array is β s , the design weighting vector w s is obtained. The method is as follows.

[0101] Assume that θ j ∈Θ(j = 1,...,J) is a discrete azimuth point in the azimuth region Θ, and J is the number of azimuth points. The main lobe is designed by the sound ray angle energy spectrum obtained above, and the side lobe level is suppressed. The expected main lobe beam response vector B d (Θ) is

[0102] B d (Θ) ≈ [E i (θ1),...,E i (θ j ),...,E i (θ J )], θ j ∈Θ ML (9)

[0103] The side lobe control-main lobe minimum mean square error criterion is used to design the expected response beam, and the corresponding design beam weighting vector w should satisfy

[0104]

[0105] where SLL is the specified side lobe level, B d (Θ) is the expected beam response, a(Θ) is the array flow vector, Θ ML , and Θ SL are the main lobe region and the side lobe region, respectively, and λ i is the corresponding angle element of the error weighting vector λ.

[0106] The main lobe region is set to Θ ML ∈[-20°, 20°], and the side lobe region is Θ SL∈ [-90°, -20°)∪(20°, 90°], the error weighting vector is unit weight, i.e.

[0107] λ = 1 1×M (11)

[0108] Equation (10) is a convex optimization problem of the second-order cone, and the optimal solution w can be obtained by using the CVX solving toolbox of MATLAB s .

[0109] Substep three: in the range of vertical emission array emission pointing angle [-90°, 90°], keep the main lobe shape of B unchanged, change the main lobe angle range Θ d , point the main lobe center to angle β ML , and traverse [-20°, 20°]. s For each β s , obtain B d (Θ), repeat substep two to obtain the design weighting vector w corresponding to each emission pointing angle. s .

[0110] Step 2: Calculate the optimized weighting vector w corresponding to each emission pointing angle. s When emitting, the average sound intensity of each convergence zone is:

[0111] According to the ray theory, the sound field excited by a point sound source located at depth z s can be represented by sound rays emitted at different angles in the sound channel. The sound pressure at the receiving point in space (r, z) can be represented in the frequency domain as the superposition of the sound pressures of several eigenrays:

[0112]

[0113] In the formula, r represents the horizontal distance between the sound source and the receiving point, z represents the receiving depth, M represents the number of eigenrays, k0 = 2πf / c0 is the wave number, where c0 is the transmission depth sound speed value, and f is the transmission frequency. m And respectively represent the sound pressure amplitude and eikonal of the mth eigenray.

[0114] According to the linear sound field superposition principle, the total sound pressure of the N-element vertical emission array at the space (r, z) position can be represented as

[0115]

[0116] where w s,n represents the design weighting coefficient of the nth emission transducer when the beam steering angle of the emission array is β s . m,nis the mth eigenray of the nth transducer of the vertical transmit array excited at the spatial (r,z) position.

[0117] The sound intensity of the N-element vertical transmit array can be calculated from equation (13)

[0118] I N (r,z)∝|p N (r,z)| 2 (14)

[0119] The design weighting vector w is obtained for different steering angles s The average sound intensity of the Kth convergence zone after the rear section

[0120]

[0121] wherein, and respectively represent the conjugate correlation segmentation distance and the end distance of the adjustable region of the Kth convergence zone.

[0122] Step 3: The optimal weighting vector w corresponding to each convergence zone is obtained by global optimization

[0123] By calculating the average sound intensity of each transmission steering angle in the corresponding convergence zone after the rear section, the global optimization method is used to obtain the maximum average sound intensity, and the corresponding weighting vector w is s selected as the best choice. For the first to the fifth convergence zone, step 3 is repeated to determine the optimal weighting vector and the corresponding maximum average sound intensity of each convergence zone in turn.

[0124] The present application will be further described in conjunction with the embodiments and the accompanying drawings:

[0125] To verify the feasibility of the method of the present application and illustrate its characteristics, simulation analysis is carried out, and the flowchart is shown in Figure 1 . Taking a typical deep sea area in the South China Sea as an example, the sea depth is 4200m, the sound channel axis depth is 1100m, the seafloor is flat, the water sound speed near the seafloor is 1531m / s (low sound speed seafloor), the seafloor is a liquid half-space, the seafloor sound speed is 1600m / s, the density is 1.6g / cm 3 , the seafloor attenuation coefficient is 0.54dB / λ, the sound speed profile and the natural steering sound intensity distribution of the vertical transmit array are shown in Figure 2 ; a 15-element vertical transmit array is selected, the half-wavelength array is 500Hz, the sound source level is 200dB, and the center of the transmit array is placed at a depth of 200m. Figure 3 The adjustable region range of the convergence zone after the conjugate correlation division. Figure 4 The sound ray angle energy spectrum of the fifth convergence zone after the rear section for the 500Hz transmission frequency can be found to have obvious double-peak characteristics; Figure 5Figure 6 is a comparison chart of natural directivity emission beam (regular beam when the emission directivity angle is 0°) and designed beam; Figure 6 Figures 7A-7E are charts showing the propagation loss of the first to fifth convergence zones when the natural directivity emission and the designed beam method are emitted, respectively, and the maximum average sound intensity level of the corresponding convergence zone is calculated by the propagation loss and the sound source level. Compared with the natural directivity emission, the average sound intensity level of the first to fifth convergence zones can be increased by 2.1630 dB, 2.4174 dB, 3.3226 dB, 4.3029 dB, and 4.9087 dB, respectively.

Claims

1. A method for optimizing the transmitted beam of a vertical array based on the angular energy spectrum of the convergence region acoustic rays, characterized in that... The steps are as follows: Step 1: Calculate the conjugate correlation of the sound field in the convergence region based on the deep-sea sound velocity profile and the parameters of the vertical emission array. And delineate the convergence zone and the area with adjustable sound intensity. , The horizontal distance from the sound field to the vertical array is the adjustable range, which is the segmentation distance. Distance to end ; Step 2: Calculate the adjustable acoustic intensity zone of the convergence area based on marine environmental parameters. Angular energy spectrum, design the transmission beam, and obtain the pointing angle of the transmission beam for each vertical array. Corresponding design beam weighting vector ; Step 3: Calculate the optimized weighted vector for each transmitted beam pointing angle during transmission. Based on the sound intensity of each convergence zone, obtain the average sound intensity after weighted control of the controllable area of ​​each convergence zone. ; Step 4: Through global optimization, the optimal weighting vector corresponding to each convergence region is obtained, and the optimized vertical array transmission beam is obtained.

2. The vertical array transmitted beam optimization method based on the convergent region acoustic ray angle energy spectrum according to claim 1, characterized in that: The process of step 1 is as follows: Step 1.1: Simulate and calculate the emitted sound field of the vertical transmission array: deployment depth is The array element excitation sound field in The sound pressure at that location is expressed as , N The sound pressure generated by the vertical emission array of the transducer is represented by the sound pressure vector: ； Step 1.2: Calculate the optimal weighting vector at different locations in the sound field of the vertical transmission array. ; First, calculate the center depth of the vertical launch array. Total sound pressure level at the location In the formula, For weighted vectors, The spatial position of each transducer in the vertical launch array The sound pressure vector is composed of the sound pressure at a certain point. The depth of the center of the vertical launch array. Horizontal distance; Then calculate the spatial location. The theoretical upper limit of sound intensity after conjugate weighting : Obtain the optimal weighted vector at the corresponding position. : ； Step 1.3: Calculate the conjugate correlation of the sound field and use the conjugate correlation of the sound field to divide the convergence region: Calculate the conjugate correlation under natural pointing emission : After simplification, it becomes: In the formula, For uniformly weighted vectors, , The conjugate vector of the sound pressure vector represents the spatial position of each transducer in the vertical emission array. The vector composed of the conjugate sound pressure at the location; For the For the convergence zone, the horizontal range of its control area is: 。 3. The vertical array transmitted beam optimization method based on the convergent region acoustic ray angle energy spectrum according to claim 1, characterized in that: The process of step 2 is as follows: Step 2.1: Calculate the angular energy spectrum of the convergence region: In the formula, For the angle of departure In depth ,distance The range of vocal timbre at that point For the first The horizontal distance range of the controllable area of ​​each convergence zone; Step 2.2: Design the transmission beam: Define the pointing angle range of the vertical transmission array transmission beam. The horizontal direction is defined as Pointing downwards from the horizontal plane is considered positive; let... It is a directional area Discretized internal location points This refers to the number of azimuth points; the main lobe is designed based on the acoustic angle energy spectrum obtained above, while the sidelobe levels are suppressed, resulting in the desired main lobe beam response vector. for: The design beam weighting vector is solved using the sidelobe control-main lobe minimum mean square error criterion. ,satisfy: in, SLL For the specified sidelobe level, For the desired beam response, These are the main lobe region and the side lobe region, respectively, representing the angle. Error weighting vector The corresponding angle element; Let be the array manifold vector, where For wave number, The spacing between array elements; The array manifold vector: Step 2.3: Calculate the pointing angle of the vertical array transmitted beam. Corresponding design beam weighting vector Set the main lobe region to The side lobe region is The error weighting vector is unit weighted, i.e. Using the CVX toolbox, input parameters are used to solve the optimization problem to obtain the vertical array transmit beam pointing angle. Corresponding design beam weighting vector ; Step 2.4: Traverse the vertical array transmitted beam pointing angle ,exist Within the range, maintain The shape of the main lobe remains unchanged, while the angle range of the main lobe region is shifted. The vertical array transmits beam pointing angle Traversal For each Received Repeat step 3 to obtain the design beam weighting vector corresponding to each transmission pointing angle. .

4. The vertical array transmitted beam optimization method based on the convergent region acoustic ray angle energy spectrum according to claim 1, characterized in that: The process of step 3 is as follows: Step 3.1: Calculate the space based on ray theory. Sound pressure at location Represents the sound field excited by a point sound source: In the formula, For the first The amplitude of the vocal timbre, For wave number, For the first Phase of each vocal ray; Based on the principle of linear sound field superposition, calculate Total sound pressure level of the vertical emission array: In the formula, For the first The weighting coefficients of each transducer For the first The transducer is located in space. The sound pressure at that location; Step 3.2: Calculate the design beam weighting vector for different pointing angles. Average acoustic intensity in the rear section of the convergence zone after launch for: In the formula, and The first The conjugate correlation segmentation distance and termination distance of each convergent region and controllable region.

5. The vertical array transmitted beam optimization method based on the convergent region acoustic ray angle energy spectrum according to claim 1, characterized in that: The process of step 4 is as follows: Step 4.1: Using a global optimization method, calculate the average sound intensity of each emission direction angle emitted at the rear of the corresponding convergence zone; Step 4.2: Select the option that maximizes the average sound intensity Maximum design beam weighting vector As the best choice; Obtain the design beam weighting vector corresponding to each convergence zone. and maximum average sound intensity .

6. The vertical array transmitted beam optimization method based on the convergent region acoustic ray angle energy spectrum according to claim 2, characterized in that: The deployment depth is the depth of the center of the launch array.

7. The vertical array emission beam optimization method based on the convergence region acoustic ray angle energy spectrum according to claim 2 or 3, characterized in that: The sound field emitted by the vertical emission array Sound pressure vector Harmonic information The results were obtained through simulation calculations using the Bellhop module in MATLAB.

8. The vertical array emission beam optimization method based on the convergence region acoustic ray angle energy spectrum according to claim 2, characterized in that: The boundary between the high conjugate correlation region and the low conjugate correlation region in the convergence region .

9. An electronic device, characterized in that, It includes a processor and a memory, wherein the processor is used to execute a computer program stored in the memory to implement the steps of the vertical array emission beam optimization method based on the convergent region acoustic ray angle energy spectrum as described in any one of claims 1 to 8.

10. A computer program product, characterized in that... It includes computer-executable instructions, which, when executed, are used to implement the vertical array transmit beam optimization method based on the convergent region acoustic ray angle energy spectrum as described in any one of claims 1 to 8.

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