Vertical array transmitted beam optimization method based on convergence area sound ray angle energy spectrum

Abstract

The invention relates to a convergence area sound ray angle energy spectrum-based vertical array emission beam optimization method, which is characterized in that in a deep sea environment, the front section of a vertical emission array sound field convergence area is tidy in phase and dense in sound rays, the sound intensity is close to the emission beam regulation upper limit, and the rear section of the convergence area is scattered in sound field phase and sparse in sound rays. As an adjustable region, the average sound intensity has a great improvement potential. According to the method, a convergence area sound ray angle energy spectrum is taken as an emission expected beam, a main lobe fitting and side lobe control strategy is adopted, a vertical emission array emission beam weight is optimally designed, and average sound intensity maximization of emission energy in an adjustable area is realized. Compared with a traditional beam forming method, the vertical transmitting array transmitting beam optimization design method can effectively improve the average sound intensity in an adjustable region of a convergence region under the same transmitting power, improves the sonar detection distance, provides important technical support for profound and far sea active sonar detection, and has a wide application prospect.

Description

Technical Field

[0001] The present invention belongs to the field of active sonar detection, and relates to an optimization method for the vertical array transmitting beam based on the acoustic ray angle energy spectrum in the convergence zone, which is applicable to improving the radiated sound intensity and detection range in the convergence zone when the active sonar transmitting system conducts deep-sea long-range detection. Background Art

[0002] At present, active and passive sonars mainly detect targets in the deep-sea environment through surface waveguide mode, convergence zone mode, and bottom bounce mode. Most of these methods focus on the array layout and signal processing at the sonar receiving end, while relatively few studies focus on the optimization of the channel propagation characteristics at the sonar transmitting end. Since the distribution characteristics of the deep-sea sound field are simultaneously affected by the coupling of the sound propagation mode and the excitation process at the transmitting end, if the sound field characteristics can be fully considered in the transmitting beam design and the target detection ability can be improved by utilizing the deep-sea sound propagation characteristics, the transmitting gain and detection range can be significantly improved.

[0003] Some early studies have tried to apply the sound field characteristics to the transmitting end. Guo Fuqiang et al. realized the sound energy focusing at the desired position outside the sound source through a time-reversal focusing method with variable depth and distance based on mode extraction (Guo Guoqiang, Yang Yixin, Sun Chao. A time-reversal focusing method with variable depth and distance based on mode extraction [J]. Acta Acustica, 2010, 35(4): 403-413.). Yi Xiaofeng et al. proposed a multimode focusing method, which concentrated the sound field energy to the first three modes by using multimode control transmission in the shallow sea environment, reducing the influence of environmental mismatch on sound energy focusing (Yi Xiaofeng, Peng Dayong, Hou Qiannan, et al. Multimode sound field focusing of low-frequency vertical phased arrays in shallow water [J]. Journal of Applied Acoustics, 2019, 38(04): 615-622.). However, these methods are mainly based on the shallow sea environment and require a feedback array with full-depth sampling, which is greatly limited in the deep-sea environment.

[0004] In recent years, Han Zhibin et al. from the University of Chinese Academy of Sciences proposed a method for optimizing the pitch angle of the active sonar beam by using the peak value of the acoustic ray cluster in the sound field, achieving a significant transmitting array gain in the deep-sea bottom reflection area (Han Zhibin, Peng Zhaohui, Liu Xionghou. Analysis of the angular spectrum distribution structure of the sound field in the deep-sea bottom reflection area and its application to sonar beam pitch [J]. Acta Physica Sinica, 2020, 69(11): 207-218). This study initially considered the characteristics of deep-sea sound propagation, but mainly analyzed the bottom reflection area and less studied the convergence zone mode in the deep-sea long-distance detection environment. Overall, the research on the sonar regulation technology at the transmitting end in the deep and far sea environment at home and abroad is still relatively scattered, lacking systematic theoretical support and technical framework. Therefore, it is necessary to further carry out research on the optimization method of the vertical transmitting array transmitting beam using the characteristics of the convergence zone sound field to improve the deep-sea long-range detection ability. Summary of the Invention

[0005] Technical problem to be solved

[0006] To avoid the deficiencies of the prior art, the present invention proposes an optimization method for the vertical array emission beam based on the acoustic ray angle energy spectrum in the convergence zone. The ray acoustics theory points out that different angle acoustic rays emitted from the sound source continuously reverse within a certain depth range when propagating over a long distance, and a convergence zone is formed at the acoustic ray caustic line. The number of these reversed acoustic rays and the energy they carry determine the distribution of the acoustic energy in the convergence zone. This distribution directly affects the actual emission regulation and the acoustic energy focusing effect. In the convergence zone of the vertical emission array sound field of the active sonar system, the phases of the acoustic rays in the front section are neat and the acoustic rays are dense, and the acoustic intensity has approached the upper limit of emission regulation. While in the rear section of the convergence zone, the sound field phase is scattered and the acoustic rays are sparse. As an adjustable zone, there is great potential for improving the emission acoustic intensity. The present invention proposes an optimization design method for the vertical emission array emission beam based on the acoustic ray angle energy spectrum in the convergence zone. This method utilizes the deep-sea acoustic propagation characteristics and the sound field structure characteristics to give the division criterion for the adjustable zone of the acoustic intensity in the convergence zone. Taking the acoustic ray angle energy spectrum in the convergence zone as the desired beam of the emission beam, and adopting the main lobe fitting and side lobe control strategies, the emission beam weight value of the vertical emission array is optimized and designed to maximize the average acoustic intensity in the adjustable zone of the emission energy, effectively improving the detection range of the active sonar.

[0007] Technical solution

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

[0009] Step 1: According to the deep-sea sound speed profile and the vertical array parameters, calculate the conjugate correlation |ρ w (r,z s )| of the sound field in the convergence zone, and divide the adjustable zone C i ={r|r th >r>r 2}, where r is the horizontal distance from the sound field to the vertical array, and the range of the adjustable zone is the segmentation distance r th to the end distance r 2 ;

[0010] Step 2: Calculate the angle energy spectrum of the adjustable zone C i of the acoustic intensity in the convergence zone according to the ocean environment parameters, design the emission beam, and obtain the designed weighted vector w s corresponding to each emission pointing angle β s ;

[0011] Step 3: When calculating the optimized weighted vector corresponding to each emission beam pointing angle during emission, according to the acoustic intensity of each convergence zone, obtain the average acoustic intensity after weighted regulation in the adjustable zone of each convergence zone

[0012] Step 4: Through global optimization, obtain the optimal weighted vector corresponding to each convergence area, and obtain the optimized vertical array emission beam.

[0013] The process of the said Step 1 is as follows:

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

[0015] p = [p(r, z, z 1 ), p(r, z, z 2 ), …, p(r, z, z N )] T ;

[0016] Step 1.2: Calculate the optimal weighted vector w opt at different positions of the vertical emission array sound field;

[0017] First, calculate the total sound field sound pressure p s at the central depth z N of the vertical emission array (r, z s ):

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

[0019] where w is the weighted vector, p is the sound pressure vector composed of the sound pressures of each transducer in the vertical emission array at the spatial position (r, z s ), z s is the central depth of the vertical emission array, and r is the horizontal distance;

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

[0021]

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

[0023]

[0024] Step 1.3: Calculate the conjugate correlation of the sound field and divide the convergence area by using the conjugate correlation of the sound field:

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

[0026]

[0027] After simplification, it is:

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

[0029] For the i-th convergence zone, its horizontal range of the regulation zone is:

[0030] C i ={r|r th > r > r 2}}.

[0031] The process of step 2 is:

[0032] Step 2.1: Calculate the convergence zone angular energy spectrum: In the formula, A(θ,r) is the sound ray amplitude at the emission angle θ at the depth z s , distance r, C i is the horizontal distance range of the adjustable zone of the i-th convergence zone;

[0033] Step 2.2: Design the transmitting beam: Let the beam control angle range β of the vertical transmitting array s ∈[-90°,90°], and the beam abeam direction is specified as 0°, and the direction pointing below the horizontal plane is positive; Let θ j ∈Θ(j = 1,...,J) be the discretized azimuth points in the azimuth region Θ = [-90°,90°], and J is the number of azimuth points; Design the main lobe from the obtained sound ray angle energy spectrum, and at the same time suppress the sidelobe level. The desired main lobe beam response vector B d (Θ) is:

[0034] B d (Θ)≈[E i (θ 1 ),...,E i (θ j ),...,E i (θ J ),θ j ∈Θ ML

[0035] Adopt the sidelobe control - main lobe minimum mean square error criterion to solve the designed beam weighting vector w s , satisfying:

[0036]

[0037] Among them, SLL is the specified sidelobe level, B d (Θ) is the desired beam response, Θ ML , Θ SL are the main lobe region and the sidelobe region of the angle respectively, λ i is the corresponding angle element of the error weighting vector λ. a(Θ) is 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 corresponding to 0° of the designed weighting vector w s : Set the main lobe region to Θ ML ∈[-20,20], and the sidelobe region is Θ SL ∈[-90°,-20°)∪(20°,90°], and the error weighting vector is unit weighting, i.e., λ = 1 1×M . Use the CVX toolbox to solve the optimization problem with the input parameters to obtain the designed weighting vector w s corresponding to β s = 0°;

[0041] Step 2.4: Traverse the main lobe center pointing angle β s , within the range of β s ∈[-20°,20°], keep the main lobe shape of B d (Θ) unchanged, move the angle range Θ of the main lobe region ML , and traverse the main lobe center pointing angle β s from [-20°,20]. For each β s obtained, repeat the third sub-step to obtain the designed weighting vector w corresponding to each emission pointing angle d . s .

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

[0043] Step 3.1: According to the ray theory, calculate the sound pressure at the spatial (r,z) position, and p(r,z) represents the sound field excited by the point source:

[0044]

[0045] In the formula, A m is the amplitude of the m-th sound ray, k is the wave number, is the phase of the m-th sound ray;

[0046] According to the principle of linear sound field superposition, calculate the total sound pressure of the N-element vertical emission array:

[0047]

[0048] where w s,n is the weighting coefficient of the nth transducer, and p n (r, z) is the sound pressure of the nth transducer at the spatial position (r, z);

[0049] Step 3.2: Calculate the weighting vector w for different steering angles s The average sound intensity in the latter section of the convergence area after emission is:

[0050]

[0051] where and are the conjugate correlation segmentation distance and the end distance of the adjustable area of the Kth convergence area, respectively.

[0052] The process of the said Step 4 is as follows:

[0053] Step 4.1: Adopt the global optimization method to calculate the average sound intensity of each emission steering angle at the rear of the corresponding convergence area;

[0054] Step 4.2: Select the weighting vector w that maximizes the average sound intensity s as the best choice;

[0055] Obtain the best weighting vector w s corresponding to each convergence area and the maximum average sound intensity

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

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

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

[0059] An electronic device, characterized in that it includes a processor and a memory, and the processor is used to implement the steps of the vertical array emission beam optimization method based on the convergence zone ray angle energy spectrum when executing the computer program stored in the memory.

[0060] A computer program product, characterized in that it includes computer-executable instructions, and the instructions are used to implement the vertical array emission beam optimization method based on the convergence zone ray angle energy spectrum when executed.

[0061] Beneficial effects

[0062] A vertical array emission beam optimization method based on the convergence zone ray angle energy spectrum proposed by the present invention. In the deep-sea environment, in the front section of the sound field convergence zone of the vertical emission array, the phases are neat and the rays are dense, and the sound intensity has approached the upper limit of emission beam regulation. While in the rear section of the convergence zone, the sound field phases are scattered and the rays are sparse. As an adjustable area, its average sound intensity has great potential for improvement. The present invention uses the convergence zone ray angle energy spectrum as the expected emission beam, adopts the main lobe fitting and sidelobe control strategies, optimally designs the emission beam weight vector of the vertical emission array, and realizes the maximization of the average sound intensity in the adjustable area of the emission energy. Compared with the traditional beamforming method, the vertical emission array emission beam optimization design method proposed by the present invention can effectively increase the average sound intensity in the adjustable area of the convergence zone under the same emission power, improve the sonar detection range, provide important technical support for deep and far-sea active sonar detection, and has a wide application prospect.

[0063] Specific beneficial effects are as follows:

[0064] 1. The method utilizes the inherent sound propagation law of the deep-sea sound field, the coupling relationship between the ray arrival structure and emission regulation, and gives the optimal weighted vector of the vertical emission array in each convergence zone, increasing the average sound intensity in the adjustable area of the convergence zone sound field. It has certain guiding significance for the design of the weighted vector of the vertical emission array in deep-sea convergence zone detection.

[0065] 2. Combining the ray angle energy spectrum in the convergence zone to design the emission beam, the main lobe area of the designed beam fits the ray angle-energy distribution spectrum of the convergence zone, reducing the energy loss of some reverse rays from the beam sidelobes or grooves during natural pointing emission, increasing the total sound energy carried by the reverse rays when exiting the convergence zone, and thus effectively increasing the average sound intensity in the rear section of the convergence zone; when using the optimal weighted vector, the average sound intensity level in the adjustable area of the convergence zone increases significantly, effectively improving the long-range detection distance. Description of the drawings

[0066] Figure 1 It is a schematic flow diagram of the method of the present invention;

[0067] Figure 2Diagram of the natural directivity emission sound intensity distribution of the vertical emission array under the typical deep - sea sound velocity profile in the South China Sea as an invention example;

[0068] Figure 3 For the division result of the adjustable area of the convergence zone

[0069] Figure 4 For the invention example in Figure 2 The acoustic ray angle energy spectrum in the adjustable area of the fifth convergence zone under the

[0070] Figure 5 Diagram for comparing the designed beam and the natural - directivity emission beam of the invention example (taking 0° as an example);

[0071] Figure 6 Diagram for comparing the propagation loss changes when the optimal designed beam corresponding to the adjustable areas of the first to fifth convergence zones of the invention example and the natural - directivity emission beam are emitted;

[0072] (a) The first convergence zone, (b) The second convergence zone, (c) The third convergence zone, (d) The fourth convergence zone, (e) The fifth convergence zone. Detailed implementation manners

[0073] The present invention will be further described in combination with the embodiments and the drawings:

[0074] Since the ray acoustics theory points out that different - angle acoustic rays emitted from the sound source continuously reverse within a certain depth range when propagating over a long distance, and a convergence zone is formed at the acoustic ray caustic line. The number of these reversed acoustic rays and the energy they carry determine the sound energy distribution in the convergence zone. This distribution directly affects the actual emission regulation and the sound energy focusing effect. In the convergence zone of the vertical - emission - array sound field of an active sonar system, the phases of the acoustic rays in the front section are neat and the acoustic rays are dense, and its sound intensity has approached the upper limit of emission regulation. While in the rear section of the convergence zone, the sound - field phases are scattered and the acoustic rays are sparse. As an adjustable area, its emission sound intensity has great potential for improvement. The present invention proposes an optimization design method for the emission beam of a vertical - emission array based on the acoustic ray angle energy spectrum in the convergence zone. This method uses the deep - sea sound propagation characteristics and the sound - field structure characteristics to give the division criterion for the adjustable area of the convergence - zone sound intensity. Taking the acoustic ray angle energy spectrum in the convergence zone as the desired beam of the emission beam, and adopting the main - lobe fitting and side - lobe control strategies, the emission - beam weight value of the vertical - emission array is optimized and designed to maximize the average sound intensity in the adjustable area of the emission energy, effectively improving the detection range of the active sonar.

[0075] As Figure 1 shown, the technical solutions adopted by the present invention to solve its technical problems include the following steps:

[0076] Step 1: According to the deep - sea sound velocity profile and the parameters of the vertical - emission array, calculate the conjugate correlation of the convergence - zone sound field and divide the adjustable area of the convergence - zone sound intensity.

[0077] The deployment depth is z n The sound pressure at (r, z) of the acoustic field excited by the array element can be expressed as p(r, z, z n ). The sound pressure excited by the N-element transducer vertical emission array can be represented by the sound pressure vector p = [p(r, z, z 1 ), p(r, z, z 2 ), …, p(r, z, z N )] T When the weighting vector w takes the conjugate vector p * of the sound pressure vector p at the copy field position (r, z), the phases of the sound pressures of each array element in the acoustic field can be aligned, and the upper limit of the theoretical sound intensity I opt (r, z s ) after weighting can be obtained, and the corresponding weight vector is w opt . Define the correlation between the natural pointing weighting coefficient and the optimal conjugate weighting coefficient as the conjugate correlation |ρ w |(r, z), which quantitatively describes the upper limit of the weighting regulation gain at a certain position in the acoustic field emitted by the vertical emission array. In the low conjugate correlation region, the phases of the elements of the sound pressure vector p of the acoustic field are scattered, and a large increase in sound intensity can be obtained through weighting regulation. Therefore, the convergence area is divided by the conjugate correlation of the acoustic field, and the low conjugate correlation region is used as the emission adjustable area.

[0078] Sub-step one: Calculate the conjugate correlation distribution of the acoustic field

[0079] Now only consider the total sound pressure p s of the total acoustic field at the center depth z N (r, z s ) of the vertical emission array, which can be obtained by summing the sound pressures of the array elements at depth z s on the same distance but different array element depths z n .

[0080]

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

[0082]

[0083] Sub-step two: Use the conjugate correlation of the acoustic field to divide the convergence area to obtain the range of the sound intensity adjustable area in the convergence area.

[0084] The calculation formula of the conjugate correlation |ρ w |(r, z) at the position (r, z) in the acoustic field under natural pointing emission is as follows.

[0085]

[0086] Calculate the emission weighting coefficient w in the case of natural direction emission arg , to ensure consistent emission power, ensure that the modulus value of w is 1.

[0087]

[0088] Among them, N is the number of vertical emission array elements, and I N is a unit vector of length N.

[0089] Use the Bellhop module of the MATLAB acoustic toolbox to simulate the emission sound field of the vertical emission array, and obtain the sound pressure vector p(r,z) of the sound field of the vertical emission array. And use formula (4) to calculate the conjugate correlation of the sound field in the area with the same depth as the center depth of the vertical emission array.

[0090]

[0091] Obtain n wave peaks |ρ w |(r,z s ) of the |ρ w | curve in a certain convergence area. The conjugate correlation coefficient |ρ peak (r n ,z s ) values are distributed in the range [0,1]. Select the minimum distance r n among the wave peak coordinates with all amplitudes less than 0.707 as the distance dividing line r w |(r,z s ) between the high conjugate correlation area and the low conjugate correlation area of this convergence area. n r th .

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

[0093] Divide the convergence area according to the horizontal distance. The adjustable area range of the convergence area is from the segmentation distance r th to the end distance r 2 .

[0094] Step 2: Calculate the angular energy spectrum of the convergence area according to the ocean environmental parameters and design the emission beam

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

[0096] Use the Bellhop module in the acoustic toolbox of MATLAB simulation software to simulate the transmitting sound field of a vertical transmitting array, and count the ray information A(θ, z s ) reaching within the posterior segment of different convergence zones. A(θ, z s ) is the amplitude of the ray with an emission angle of θ at the sound source depth z s . Add the amplitudes of the rays with the same emission angle to obtain the angular energy spectrum corresponding to the convergence zone.

[0097]

[0098] Among them, E i (θ) represents the angular energy spectrum of the rays with an emission angle of θ within the posterior segment of the i-th convergence zone.

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

[0100] Let the beam steering angle range β s of the vertical transmitting array be in the range of [-90°, 90°]. It is stipulated that the beam broadside direction of the vertical transmitting array is 0°, and the direction pointing below the horizontal plane is positive. When the beam steering pointing angle of the transmitting array is β s , the design weighted vector w s is obtained as follows.

[0101] Assume that θ j ∈ Θ (j = 1,..., J) are the discretized azimuth points within the azimuth region Θ, and J is the number of azimuth points. Design the main lobe from the angular energy spectrum of the rays obtained above, and at the same time suppress the sidelobe level. The desired main lobe beam response vector B d (Θ) is

[0102] B d (Θ) ≈ [E i (θ 1 ),..., E i (θ j ),..., E i (θ J )], θ j ∈ Θ ML (9)

[0103] Adopt the sidelobe control - main lobe minimum mean square error criterion to design the desired response beam. The corresponding design beam weighted vector w should satisfy

[0104]

[0105] Among them, SLL is the specified sidelobe level, B d (Θ) is the desired beam response, a(Θ) is the array manifold vector, Θ ML , Θ SL are the main lobe region and sidelobe region of the angle respectively, and λ iIs the corresponding angular element of the error weighting vector λ.

[0106] Set the main lobe region as Θ ML ∈[-20°, 20°], and the sidelobe region is Θ SL ∈[-90°, -20°) ∪ (20°, 90°], and the error weighting vector is unit weighting, that is

[0107] λ = 1 1×M (11)

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

[0109] Sub-step three: In the range of the emission pointing angle [-90°, 90°] of the vertical emission array, keep the main lobe shape of B d (Θ) unchanged, change the angular range Θ of the main lobe region ML , and point the center of the main lobe to the angle β s Traverse [-20°, 20°], and for each β s Get the corresponding B d (Θ), repeat sub-step two, and obtain the designed 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 During emission, the average sound intensity of each convergence zone:

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

[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, and k 0 = 2πf / c 0 is the wave number, where c 0 is the sound speed value at the emission depth, and f is the emission frequency. R m and respectively represent the sound pressure amplitude and eikonal of the m-th eigenray.

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

[0115]

[0116] Among them, w s,n represents the designed weighting coefficient of the nth transmitting transducer when the transmitting array beam steering angle is β s and A m,n is the mth eigen sound ray of the sound field excited by the nth transducer of the vertical transmitting array at the spatial (r, z) position.

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

[0118] I N (r, z) ∝ |p N (r, z)| 2 (14)

[0119] Find the designed weighting vector w s for different steering angles and the average sound intensity in the latter section of the Kth convergence zone after transmission

[0120]

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

[0122] Step 3: Through global optimization, find the optimal weighting vector corresponding to each convergence zone

[0123] By calculating the average sound intensity of each transmitting steering angle at the rear of the corresponding convergence zone, use the global optimization method to obtain the maximum average sound intensity, and take the corresponding weighting vector w s as the best choice. For the first to fifth convergence zones, repeat Step 3 to sequentially determine the optimal weighting vector and the corresponding maximum average sound intensity for each convergence zone.

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

[0125] To verify the feasibility of the method of the present invention and illustrate its characteristics, a simulation analysis was carried out. The schematic flow diagram is as Figure 1 shown. Taking a typical deep-sea area in the South China Sea as an example, the sea depth is 4200 m, the depth of the sound channel axis is 1100 m, the seabed is flat, the sound speed in the water near the seabed is 1531 m / s (low sound speed seabed), the seabed is a liquid half-space, the seabed sound speed is 1600 m / s, the density is 1.6 g / cm 3 , the seabed attenuation coefficient is 0.54 dB / λ, and the sound speed profile and the natural pointing emission sound intensity distribution of the vertical transmitting array are as Figure 2As shown in the figure; a 15-element vertical launch array is selected, arranged at a half-wavelength interval of 500 Hz, with a sound source level of 200 dB, and the central deployment depth of the launch array is 200 m. Figure 3 The adjustable range of the convergence zone after being divided by the acoustic field conjugate correlation. Figure 4 It is the acoustic ray angle energy spectrum of the rear section of the fifth convergence zone at a transmission frequency of 500 Hz, and it can be found that it has obvious double-peak characteristics; Figure 5 It is a comparison diagram between the natural pointing transmission beam (conventional beam when the transmission pointing angle is 0°) and the designed beam; Figure 6 They are respectively the changes in the propagation loss of the convergence zone with the transmission pointing angle when the first to fifth convergence zones are transmitted in the natural pointing and designed beam methods; by calculating the maximum average sound intensity level of the corresponding convergence zone through the propagation loss and the sound source level, compared with the natural pointing transmission, the average sound intensity levels of the adjustable zones of the first to fifth convergence zones are increased by 2.1630 dB, 2.4174 dB, 3.3226 dB, 4.3029 dB, and 4.9087 dB respectively.

Claims

1. A vertical array transmit beam optimization method based on the energy spectrum of the sound rays in the convergence zone, characterized in that Here are the steps: Step 1: Calculate the conjugate correlation of the acoustic field in the convergence zone based on the deep-sea sound velocity profile and vertical transmission array parameters |ρ w (r,z s )|, and divide the convergence area into the adjustable sound intensity area C i ={r|r th >r>r2}, r is the horizontal distance from the sound field to the vertical array, and the adjustable area range is the split distance r th To the end distance r2; Step 2: Calculate the sound intensity controllable area C of the convergence zone based on the ocean environment parameters i Angular energy spectrum, design the transmit beam, and obtain each transmit pointing angle β s The corresponding design weight vector w s ; Step 3: Calculate the optimized weighted vector corresponding to each transmitting beam pointing angle. When transmitting, according to the sound intensity of each convergence area, obtain the average sound intensity of each convergence area after weighted control. Step 4: Through global optimization, the optimal weighting vector corresponding to each focusing area is obtained to obtain the optimized vertical array transmit beam.

2. The vertical array transmit beam optimization method based on the convergence zone sound ray angle energy spectrum according to claim 1 is characterized by: The process of step 1 is: Step 1.1: Simulate and calculate the emission sound field of the vertical emission array: the 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 of the sound pressure excited by the vertical transmission array of N-element transducers is: p=[p(r,z,z1),p(r,z,z2),…,p(r,z,z N )] T ; Step 1.2: Calculate the optimal weighting vector w at different positions of the vertical transmitting array sound field opt ; First, calculate the vertical transmission array center depth z s The total sound field pressure p N (r,z s ) p N (r,z s )=w H p Where w is the weight vector, p is the spatial position (r, z) of each transducer in the vertical transmitting array. s ) is composed of the sound pressure vector, z s is the vertical launch array center depth, r is the horizontal distance; Then calculate the spatial position (r, z s ) is the theoretical upper limit of the sound intensity after conjugate weighting I opt (r,z): Get the optimal weighted vector w for the corresponding position opt : Step 1.3: Calculate the conjugate correlation of the sound field and use the conjugate correlation of the sound field to divide the convergence area: Calculate the conjugate correlation |ρ under natural directional emission w (r,z)|: After simplification, it becomes: In the formula, w avg is a uniform weight vector, p * (r,z) is the conjugate vector of the sound pressure vector, which represents the vector composed of the conjugate sound pressure of each transducer in the vertical transmitting array at the spatial position (r,z); For the i-th convergence zone, the horizontal range of its control zone is: C i ＝{r|r th ＞r＞r2}。 3. The vertical array transmit beam optimization method based on the convergence zone sound ray angle energy spectrum according to claim 1 is characterized in that: The process of step 2 is: Step 2.1: Calculate the angular energy spectrum of the convergence zone: Where A(θ,r) is the angle of incidence θ at depth z. s , the amplitude of the sound line at distance r, C i is the horizontal distance range of the controllable area of ​​the i-th convergence zone; Step 2.2: Design the transmit beam: Assume the vertical transmit array beam control angle range β s ∈[-90°,90°], the positive horizontal direction is defined as 0°, and the direction below the horizontal plane is defined as positive; let θ j ∈Θ(j=1,...,J) is the discretized azimuth point in the azimuth region Θ=[-90°,90°], and J is the number of azimuth points. The main lobe is designed based on the sound ray angle energy spectrum obtained above, while the side lobe level is suppressed. The expected main lobe beam response vector B d (Θ) is: B d (Θ)≈[E i (θ1),...,E i (i j ),...,E i (i J )],θ j ∈Θ ML The sidelobe control-mainlobe minimum mean square error criterion is used to solve the design beam weight vector w s ,satisfy: Where SLL is the specified sidelobe level, B d (Θ) is the desired beam response, Θ ML ,Θ SL are the main lobe area and side lobe area of ​​the angle, λ i is the corresponding angle element of the error weighting vector λ; a(Θ) is the array flow pattern vector, where k is the wave number and d is the array element spacing; The array of manifold vectors: Step 2.3: Calculate the main lobe center pointing angle β s =0° corresponding to the design weight vector w s : Set the main lobe area to Θ ML ∈[-20,20°], the side lobe area is Θ SL ∈[-90°,-20°)∪(20°,90°], the error weight vector is unit weighted, i.e., λ=1 1×M ; Use the CVX toolbox to input parameters to solve the optimization problem and obtain the main lobe center pointing angle β s =0° corresponding to the design weight vector w s ; Step 2.4: Traverse the main lobe center pointing angle β s , in β s ∈[-20°,20°], keep B d (Θ) The main lobe shape remains unchanged, and the angle range of the moving main lobe area is Θ ML , directing the center of the main lobe toward angle β s Traverse [-20°, 20°]; for each β s Obtained B d (Θ), repeat step 3 to obtain the design weight vector w corresponding to each transmission pointing angle s .

4. The vertical array transmit beam optimization method based on the convergence zone sound ray angle energy spectrum according to claim 1 is characterized in that: The process of step 3 is: Step 3.1: According to the ray theory, calculate the sound pressure at the spatial position (r,z), where p(r,z) represents the sound field excited by the point sound source: In the formula, A m is the amplitude of the mth sound line, k is the wave number, is the phase of the mth sound line; According to the linear sound field superposition principle, the total sound pressure of the N-element vertical transmitting array is calculated as: In the formula, w s,n is the weighting coefficient of the nth transducer, p n (r,z) is the sound pressure of the nth transducer at the spatial position (r,z); Step 3.2: Calculate the weight vector w for different pointing angles s Average sound intensity in the rear section of the convergence zone after launch for: In the formula, and are the conjugate correlation separation distance and end distance of the controllable area of ​​the Kth convergence zone, respectively.

5. The vertical array transmit beam optimization method based on the convergence zone sound ray angle energy spectrum according to claim 1 is characterized in that: The process of step 4 is: Step 4.1: Use the global optimization method to calculate the average sound intensity of each emission direction angle at the rear of the corresponding convergence area; Step 4.2: Select the average sound intensity The largest weighted vector w s As the best choice; Get the optimal weight vector w corresponding to each convergence area s and the maximum average sound intensity 6. The vertical array transmit beam optimization method based on the convergence zone sound ray angle energy spectrum according to claim 2 is characterized by: The deployment depth is the array center depth of the transmitting array.

7. The vertical array transmit beam optimization method based on the convergence zone sound ray angle energy spectrum according to claim 2 or 3, characterized in that: The emission sound field p, sound pressure vector p(r,z) and sound line information A(θ,r) of the vertical emission array are obtained by simulation calculation using the Bellhop module of MATLAB.

8. The vertical array transmit beam optimization method based on the convergence zone sound ray angle energy spectrum according to claim 2 is characterized by: The boundary line between the high conjugation correlation region and the low conjugation correlation region in the convergence zone r th =min{r||ρ w | peak (r,z s )≤0.707}。 9. An electronic device, characterized in that: The invention comprises a processor and a memory, wherein the processor is used to implement the steps of the vertical array transmit beam optimization method based on the angular energy spectrum of the sound line in the focusing area as claimed in any one of claims 1 to 8 when executing the computer program stored in the memory.

10. A computer program product, characterized in that The invention comprises computer executable instructions, which are used to implement the vertical array transmit beam optimization method based on the angle energy spectrum of sound rays in the focusing area as claimed in any one of claims 1 to 8 when being executed.

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