A vortex beam multi-base underwater target detection device and method

Abstract

The present invention provides a vortex beam multi-base underwater target detection device. By using an annular acoustic array, a non-vortex sonar acoustic wave beam and a vortex acoustic wave beam with a central direction intensity of 0 can be formed. The non-vortex acoustic wave beam and the vortex acoustic wave beam repeatedly and alternately illuminate the detection target and complement each other, thereby obtaining signals at more azimuth angles within a 360-degree range around the target, and the amplitude of the obtained signal is stronger than that of a single working mode, thereby improving the probability of target detection. Due to the special spatial distribution characteristics of the vortex acoustic beam, the function of detecting targets in any direction can be realized, giving full play to the detection advantages of multi-base sonar, and solving the practical problem of the prior art that it is difficult to detect targets at large separation angles. The device avoids the strict requirements of the non-vortex multi-base sonar forward scattering beam on the receiving array position and shows good tolerance to the directional angle of the receiving array. The annular acoustic array forms acoustic wave beams of different shapes by adjusting the topological charge of the vortex sound field without changing the shape of the acoustic array, thereby realizing the detection of targets of different sizes.

Description

Technical Field

[0001] The present invention belongs to the technical field of sonar detection, and in particular relates to a multi-base underwater target detection device and method that alternately uses non-vortex sonar beams and vortex beams. Background Art

[0002] Sonar, a technology that uses the propagation and reflection characteristics of sound waves in water to perform navigation and ranging through electroacoustic conversion and information processing, is the most widely used and important device in underwater acoustics. Based on system composition, it can be categorized as monostatic, bistatic, and multistatic. In multistatic sonar, the transmitter and receiver are separated by a certain distance. A single or multiple sound sources transmit sound waves, and multiple receivers at different locations receive the scattered echoes from the target. Multistatic sonar offers a variety of configurations and can be flexibly combined based on available sonar platforms, subject to certain platform compatibility requirements, to create various multistatic configurations, such as submarine-based shore-based sonar networks and shore-based sonar-sonobuoy systems. This type of sonar system offers advantages such as high concealment, strong anti-interference capabilities, and flexible configuration. It is suitable for airborne sonar applications and for joint ship-aircraft submarine detection. Because scattered waves originate from a 360-degree scattering volume within the target's scattering space, the energy of scattered waves from all directions can be used to detect targets. Multistatic sonar is an effective means of countering quiet submarines.

[0003] Current sonar arrays are mostly uniform linear arrays, cross arrays, and star arrays. These arrays are symmetrically distributed. Symmetrical transmitters emit signals of equal intensity, stimulating the transducer array to emit sound waves to illuminate the target. These waves then receive scattered waves from targets in different directions to detect the target. Although this type of sonar technology is relatively mature, interference from direct waves can severely impact the detection performance of multistatic sonar systems when the separation angle is large. Furthermore, due to the high axial energy intensity, the energy in other directions is naturally significantly reduced, forming weak or blind areas, which somewhat limits the application scope of multistatic sonar systems. Summary of the Invention

[0004] The purpose of the present invention is to overcome the shortcomings of existing multi-base sonars, such as serious interference from forward scattered direct waves and weak signals in other directions. The present invention uses non-vortex acoustic wave beams and vortex acoustic wave beams to repeatedly and alternately illuminate the detection target, complementing each other, to obtain target scattered signals in more azimuth angles within a 360° range around the target, and the obtained signal amplitude is stronger than that of a single working mode, thereby increasing the probability of detecting the target.

[0005] To achieve the above-mentioned object, the present invention provides a vortex beam multi-base underwater target detection device, which includes an annular vortex wave acoustic array composed of multiple transducers and multiple hydrophones distributed around the detection target.

[0006] Furthermore, the annular vortex wave acoustic array is composed of N transducers arranged in a circular ring.

[0007] Furthermore, the target detection method based on the vortex beam multistatic underwater target detection device includes the following steps:

[0008] Step 301: Evenly arrange N transmitting transducers into a circular vortex wave acoustic array with a radius of R, and use an incremental phase modulation excitation method to make the circular vortex wave acoustic array generate a vortex sound field. In addition, the amplitude of each transducer remains the same, and the phase of each transducer increases by a fixed value at a time. Wherein, L is the topological charge of the vortex acoustic field;

[0009] Step 302: Calculate the sound pressure generated by each transducer at any point Q(r,θ,φ) in space using the following formula:

[0010]

[0011] Among them, r s,Q is the distance from the transducer Ts to the Q point, θ s,Q is the angle between the line connecting the transducer Ts and Q points and the axis, a is the radius of the piston transducer, k is the wave number of the sound wave, ω is the angular frequency of the sound wave, ρ is the density of the propagation medium, and u a is the amplitude of the piston transducer, A0=iωρu a a 2 / 2 is a constant;

[0012] Step 303: Calculate the total sound field formed by the N transducers of the vortex sound field acoustic array using the following formula:

[0013]

[0014] Step 304: Draw the background sound field formed by the annular vortex wave acoustic array under different topological loads. In the spherical coordinate system, it is expressed as

[0015]

[0016] in,

[0017] Step 305: The background sound field formed by the annular vortex wave acoustic array illuminates the target. The expression of the scattered sound field formed at any point Q(r,θ,φ) in space is:

[0018]

[0019] in, h n (x) is the first-order spherical Hankel function, The spherical coordinates of the location of the sth transducer are (r s ,θ s ,φ s );

[0020] Step 306: Calculate the radiation directivity diagram of the scattered far field under different topological charges based on the scattered sound field formed in step 305, and draw the spatial distribution diagram of the scattered sound field under different topological charges;

[0021] Step 307: Draw a radiation directivity diagram according to step 306, and deploy a receiving hydrophone in the direction where the signal of the radiation directivity diagram is larger, so as to receive the scattered waves of the target, process and analyze the scattered signals of the target, and determine the position of the target;

[0022] Step 308: cancel the incremental phase modulation excitation method of step 301, and use the same amplitude and phase method to excite the transducer array to generate non-vortex sound waves, illuminate the target, and perform data processing and analysis on the scattered signals of the target to determine the position of the target;

[0023] In step 309 , the two excitation modes of steps 301 and 308 are used alternately, and the received signals of the two modes are comprehensively analyzed to improve the target detection probability.

[0024] The advantages of the present invention are:

[0025] The present invention can form a non-vortex sonar acoustic wave beam and a vortex acoustic wave beam with a center direction intensity of 0 to alternately illuminate the detection target. The non-vortex acoustic wave beam and the vortex acoustic wave beam are used to repeatedly and alternately illuminate the detection target, complementing each other, and obtaining target scattering signals at more azimuth angles within a 360° range around the target. The amplitude of the obtained signal is stronger than that of a single working mode, thereby increasing the probability of detecting the target. The present invention provides such a vortex beam multi-base underwater target detection device, which adopts a multi-base sonar system configuration of a vortex wave annular transmitting transducer array. Multiple signal receivers located in any direction of the target scattering can receive a relatively high intensity acoustic signal, thereby achieving the purpose of detecting underwater targets. The present invention uses a circular acoustic array to form a vortex acoustic field with a center direction intensity of 0 to illuminate the detection target. Due to the special spatial distribution characteristics of the vortex acoustic beam, the function of detecting targets in any direction can be realized, giving full play to the detection advantages of multi-base sonar, and solving the practical problem of the existing technology that it is unable to detect targets at large separation angles. The vortex beam multi-base underwater target detection device can avoid the strict requirements of the non-vortex multi-base forward scattering beam forming method on the position of the receiving array, and shows good tolerance to the directional angle of the receiving array; the annular phase-modulated acoustic array can form acoustic beams of different shapes by adjusting the topological charge of the vortex sound field without changing the array shape, thereby realizing the detection of targets of different sizes; the present invention can make up for the shortcomings of non-vortex multi-base sonar detection without giving up the advantages of non-vortex multi-base sonar, effectively solve the problem of difficulty in suppressing direct waves in current multi-base sonar detection, and has positive significance for the development and application of sonar detection technology.

[0026] The present invention is described in detail below with reference to the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic diagram of the annular vortex transmitting transducer array and the hydrophone receiving position of the present invention.

[0028] Figure 2 This is a schematic diagram of the geometric mesh created by the simulation software COMSOL.

[0029] Figure 3a It is the amplitude distribution diagram of the incident vortex sound wave emitted by the acoustic array when the radius R = 0.5m and the topological charge is 0.

[0030] Figure 3b This is the amplitude distribution diagram of the incident vortex sound wave emitted by the acoustic array when the radius R = 0.5m and the topological charge is 1.

[0031] Figure 3c This is the amplitude distribution diagram of the incident vortex sound wave emitted by the acoustic array when the radius R = 0.5m and the topological charge is 2.

[0032] Figure 3d This is the amplitude distribution diagram of the incident vortex sound wave emitted by the acoustic array when the radius R = 0.5m and the topological charge is 3.

[0033] Figure 4a It is the amplitude distribution diagram of the scattered sound field formed by the detected rigid sphere when the radius R = 0.5m and the topological charge is 0.

[0034] Figure 4b It is the amplitude distribution diagram of the scattered sound field formed by the detected rigid sphere when the radius R = 0.5m and the topological charge is 1.

[0035] Figure 4c It is the amplitude distribution diagram of the scattered sound field formed by the detected rigid sphere when the radius R = 0.5m and the topological charge is 2.

[0036] Figure 4d It is the amplitude distribution diagram of the scattered sound field formed by the detected rigid sphere when the radius R = 0.5m and the topological charge is 3.

[0037] Figure 5a It is the radiation pattern of far-field scattering with the detected rigid sphere as the center when the radius R = 0.5m and the topological charge is selected as 2.

[0038] Figure 5b It is the radiation pattern of far-field scattering with the detected rigid sphere as the center when the radius R = 0.5m and the topological charge is 0.

[0039] Figure 6 It is the three-dimensional radiation pattern centered on the detected rigid sphere when the radius R = 0.5m and the topological charge is selected as 2.

[0040] Figure 7a It is the amplitude distribution diagram of the incident vortex sound wave emitted by the acoustic array when the radius R = 0.25m and the topological charge is 0.

[0041] Figure 7b This is the amplitude distribution diagram of the incident vortex sound wave emitted by the acoustic array when the radius R = 0.25m and the topological charge is 1.

[0042] Figure 7c This is the amplitude distribution diagram of the incident vortex sound wave emitted by the acoustic array when the radius R = 0.25m and the topological charge is 2.

[0043] Figure 7d This is the amplitude distribution diagram of the incident vortex sound wave emitted by the acoustic array when the radius R = 0.25m and the topological charge is 3.

[0044] Figure 8a It is simulated by simulation software. When the radius R=0.25m and the topological charge is 0, the amplitude distribution diagram of the scattered sound field formed by the detected rigid sphere is shown.

[0045] Figure 8b This is a simulation of the amplitude distribution of the scattered sound field formed by the detected rigid sphere when the radius R = 0.25m and the topological charge is 1, simulated by simulation software.

[0046] Figure 8c This is a simulation of the amplitude distribution of the scattered sound field formed by the detected rigid sphere when the radius R = 0.25m and the topological charge is 2, which is simulated by simulation software.

[0047] Figure 8d This is a simulation of the amplitude distribution of the scattered sound field formed by the detected rigid sphere when the radius R = 0.25m and the topological charge is 3, which is simulated by simulation software.

[0048] Figure 9a It is the radiation pattern of far-field scattering with the detected rigid sphere as the center when the radius R = 0.25m and the topological charge is selected as 1.

[0049] Figure 9b It is the radiation pattern of far-field scattering centered on the rigid sphere being detected when the radius R = 0.25m and the topological charge is 0.

[0050] Figure 10 It is the three-dimensional radiation pattern centered on the rigid sphere being detected when the radius R = 0.25m and the topological charge is selected as 1. DETAILED DESCRIPTION

[0051] In order to further illustrate the technical means and effects adopted by the present invention to achieve the predetermined purpose, the specific implementation methods, structural features and effects of the present invention are described in detail below with reference to the accompanying drawings and examples.

[0052] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0053] In the description of the present invention, it should be understood that the terms "center", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "aligned", "overlap", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention.

[0054] The terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of the technical features indicated. Therefore, features specified as "first" or "second" may explicitly or implicitly include one or more of such features; and in the description of the present invention, unless otherwise specified, "plurality" means two or more.

[0055] Example 1

[0056] This embodiment provides a vortex beam multi-base underwater target detection device, including an annular vortex wave acoustic array composed of multiple transducers and multiple hydrophones distributed around the detection target; the annular vortex wave acoustic array is arranged on a base, which is a circular steel plate or two circular steel frames with overlapping centers.

[0057] Furthermore, the annular vortex wave acoustic array is composed of N transducers arranged in a circular ring. The more transducers in the array, the better, but should not be less than twice the maximum topological charge used. This embodiment shows an annular vortex wave acoustic array composed of 12 transducers arranged in a circular ring.

[0058] Furthermore, the target detection method based on the vortex beam multistatic underwater target detection device includes the following steps:

[0059] Step 301: Evenly arrange N transmitting transducers into a circular vortex wave acoustic array with a radius of R, and use an incremental phase modulation excitation method to make the circular vortex wave acoustic array generate a vortex sound field. In addition, the amplitude of each transducer remains the same, and the phase of each transducer increases by a fixed value at a time. Wherein, L is the topological charge of the vortex acoustic field;

[0060] Step 302: Calculate the sound pressure generated by each transducer at any point Q(r,θ,φ) in space using the following formula:

[0061]

[0062] Among them, r s,Q is the distance from the transducer Ts to the Q point, a is the radius of the piston transducer, k is the wave number of the sound wave, ω is the angular frequency of the sound wave, ρ is the density of the propagation medium, u a is the amplitude of the piston transducer, A0=iωρu a a 2 / 2 is a constant;

[0063] Step 303: Calculate the total sound field formed by the N transducers of the vortex sound field acoustic array using the following formula:

[0064] Step 304: Draw the background sound field formed by the annular vortex wave acoustic array under different topological loads. In the spherical coordinate system, it is expressed as

[0065]

[0066] in,

[0067] Step 305: The background sound field formed by the annular vortex wave acoustic array illuminates the target. The expression of the scattered sound field formed at any point Q(r,θ,φ) in space is:

[0068]

[0069] in, h n (x) is the first-order spherical Hankel function, The spherical coordinates of the location of the sth transducer are (r s ,θ s ,φ s );

[0070] Step 306: Calculate the radiation directivity diagram of the scattered far field under different topological charges based on the scattered sound field formed in step 305, and draw the spatial distribution diagram of the scattered sound field under different topological charges;

[0071] Step 307: Based on step 306, a radiation pattern is plotted. Receiving hydrophones are deployed in the direction of the radiation pattern with the strongest signal to receive scattered waves from the target. The scattered signals are processed and analyzed to determine the target's position. For example, if the forward scattering is zero, the target can be determined to be on the array's axis. If the hydrophone signal at 0° is not at a low level, it indicates a certain distance from the axis. Based on the symmetrical hydrophone signal strengths, the approach direction can be determined.

[0072] Step 308: cancel the incremental phase modulation excitation method of step 301, and use the same amplitude and phase method to excite the transducer array to generate non-vortex sound waves, illuminate the target, and perform data processing and analysis on the scattered signals of the target to determine the position of the target;

[0073] In step 309, the two excitation modes of steps 301 and 308 are used alternately, and the received signals of the two modes are comprehensively analyzed to improve the target detection probability.

[0074] Example 2

[0075] To verify the effectiveness of the solution of the present invention, Figure 1The structure shown is that on a metal circular plate or metal bracket with a radius greater than 0.5m, 12 transducers are evenly laid out with a circle of radius 0.5m as the trajectory to form a vortex wave acoustic array. A rigid ball to be tested with a radius of 0.15m is placed in the axial direction of the vortex wave acoustic array, at a vertical distance of 0.8m from the array. The comsol model established based on this array structure is as follows Figure 2 As shown, the generated background sound field (shown in Figure 3) is Figure 3a is the amplitude of the incident vortex sound wave emitted by the acoustic array when the radius R = 0.5m and the topological charge is 0; Figure 3b is the amplitude of the incident vortex sound wave emitted by the acoustic array when the radius R = 0.5m and the topological charge is 1; Figure 3c is the amplitude of the incident vortex sound wave emitted by the acoustic array when the radius R = 0.5m and the topological charge is 2; Figure 3d It is the amplitude of the incident vortex sound wave emitted by the acoustic array when the radius R = 0.5m and the topological charge is 3; a topological charge of 2 is more appropriate.

[0076] In order to generate a vortex sound field, according to the incremental phase modulation excitation method of step 301, the amplitudes of each transducer remain the same, and the phase of transducer No. 1 is used as a reference, and the phases of other units are increased by fixed values ​​in sequence. That is, transducer No. 2 has a phase greater than No. 1 by π / 3, and transducer No. 3 has a phase greater than No. 2 by π / 3, and so on, to complete array phase modulation.

[0077] According to step 302, step 303, and step 304, we can obtain the amplitude of the incident vortex sound wave emitted by the acoustic array.

[0078]

[0079] According to this formula, the spatial distribution of the incident vortex acoustic field can be obtained, and the cases where the topological charge is equal to 0, 1, 2, and 3 can also be plotted, which is consistent with the simulation result Figure 3. Observing the four cases, it can be seen that when the topological charge is 0, it is a common sonar situation. The transmitted wave directly illuminates the rigid sphere, and the forward scattering signal is large. When the topological charge is 3, the rigid sphere with a radius of 0.15m to be measured is no longer in the strong area of ​​the direct wave signal. Therefore, when the topological charge is 1 or 2, it is more advantageous to realize vortex beam multi-base target detection.

[0080] When the vortex sound field is irradiated on the rigid sphere, the scattered sound field at any position in the space can be expressed as

[0081]

[0082] The formula results are consistent with the simulation results in Figure 4, where Figure 4aIt is the amplitude distribution diagram of the scattered sound field formed by the detected rigid sphere when the radius R = 0.5m and the topological charge is 0; Figure 4b is the amplitude distribution of the scattered sound field formed by the detected rigid sphere when the radius R = 0.5m and the topological charge is 1; Figure 4c is the amplitude distribution of the scattered sound field formed by the detected rigid sphere when the radius R = 0.5m and the topological charge is 2; Figure 4d It is the amplitude distribution diagram of the scattered sound field formed by the detected rigid sphere when the radius R = 0.5m and the topological charge is 3.

[0083] According to the scattered sound field in step 305, r = 10m is selected and substituted into the image. The radiation pattern of the scattered far field at a distance of ten meters with the rigid ball being detected as the center can be directly plotted, as shown in the figure: Figure 5a To show the characteristics of vortex waves, we can compare them with the radiation pattern when the topological charge is 0, as shown in Figure 5b As shown in Figure 2, it can be seen that the scattering signals generated by the two different excitation methods on the target are significantly different in different directions, and the two complement each other. The radiation pattern of the vortex wave in three-dimensional space is shown in Figure 2. Figure 6 As shown in the radiation pattern, deploying hydrophones in the direction of strong echo intensity can better receive signals and effectively realize multi-base detection.

[0084] According to the radiation pattern in step 306 , receiving hydrophones are arranged in different directions of the radiation pattern to receive scattered waves from the target and perform data processing on the scattered signals from the target.

[0085] According to step 308, the incremental phase modulation excitation method of step 301 is canceled, and the transducer array is excited by the traditional excitation method with the same amplitude and phase to illuminate the target, and the scattered signal of the target (such as Figure 5b As shown) perform data processing and analysis to determine the location of the target.

[0086] According to step 309, the two excitation modes of steps 301 and 308 are used alternately, and the received signals of the two modes are comprehensively analyzed to improve the target detection probability.

[0087] Example 3

[0088] Change the array structure, such as Figure 1 The structure shown is a vortex wave acoustic array composed of 12 transducers evenly laid out on a metal circular plate or metal bracket with a radius greater than 0.25m, with a circle of 0.25m as the trajectory. A rigid ball to be tested with a radius of 0.15m is placed in the axial direction of the vortex wave acoustic array, at a vertical distance of 0.8m from the array. The background sound field generated by this array structure (as shown in Figure 7) is: Figure 7aThis is a schematic diagram of the amplitude of the incident vortex sound wave emitted by the acoustic array when the radius R = 0.25m and the topological charge is 0; Figure 7b This is a schematic diagram of the amplitude of the incident vortex sound wave emitted by the acoustic array when the radius R = 0.25m and the topological charge is 1; Figure 7c This is a schematic diagram of the amplitude of the incident vortex sound wave emitted by the acoustic array when the radius R = 0.25m and the topological charge is 2; Figure 7d This is a schematic diagram of the amplitude of the incident vortex sound wave emitted by the acoustic array when the radius R = 0.25m and the topological charge is 3; a topological charge of 1 is more appropriate.

[0089] In order to generate a vortex sound field, according to the incremental phase modulation excitation method of step 301, the amplitudes of each transducer remain the same, and the phase of transducer No. 1 is used as a reference, and the phases of other units are increased by fixed values ​​in sequence. That is, transducer No. 2 has a phase greater than No. 1 by π / 6, and transducer No. 3 has a phase greater than No. 2 by π / 6, and so on, to complete array phase modulation.

[0090] According to step 302, step 3, and step 4, we can obtain the amplitude of the incident vortex sound wave emitted by the acoustic array.

[0091]

[0092] According to this formula, the spatial distribution of the incident vortex acoustic field can be obtained. The cases where the topological charge is equal to 0, 1, 2, and 3 can also be plotted, which is consistent with the simulation results in Figure 7. Observing the four cases, it can be seen that when the topological charge is 0, it is a common sonar situation. The direct wave directly illuminates the rigid sphere, and the forward scattering signal is large. When the topological charge is 2 or 3, the scatterer is no longer in the strong area of ​​the direct wave signal. Therefore, when the topological charge is 1, it is more advantageous to realize vortex beam multi-base target detection.

[0093] When the vortex sound field is irradiated on the rigid sphere, the scattered sound field at any position in the space can be expressed as

[0094]

[0095] The formula results are consistent with the simulation results in Figure 8, where Figure 8a This is the amplitude distribution diagram of the scattered sound field formed by the detected rigid sphere when the radius R=0.25m and the topological charge is 0, simulated by simulation software; Figure 8b This is the amplitude distribution diagram of the scattered sound field formed by the detected rigid sphere when the radius R = 0.25m and the topological charge is 1, simulated by simulation software; Figure 8c This is the amplitude distribution diagram of the scattered sound field formed by the detected rigid sphere when the radius R = 0.25m and the topological charge is 2, simulated by simulation software; Figure 8dThis is a simulation of the amplitude distribution of the scattered sound field formed by the detected rigid sphere when the radius R = 0.25m and the topological charge is 3, which is simulated by simulation software.

[0096] According to the scattered sound field in step 305, r = 10m is selected and substituted into the image. The radiation directivity diagram of the scattered sound field at a distance of ten meters from the center of the rigid ball to be detected can be directly plotted, as shown in FIG. Figure 9a For comparison, Figure 9b The radiation pattern of the non-vortex beam when the topological charge is 0 is given. It can be seen that the scattering signals generated by the two different excitation methods on the target are significantly different in different directions, and the spatial distribution characteristics of the two can complement each other. The radiation pattern of the three-dimensional vortex wave is shown in Figure 10 The simulation results are consistent with the formula. According to the radiation pattern, placing hydrophones in the direction of strong echo intensity can better receive signals.

[0097] According to the radiation pattern in step 306 , receiving hydrophones are arranged in different directions of the radiation pattern to receive scattered waves from the target and perform data processing on the scattered signals from the target.

[0098] According to step 308, the incremental phase modulation excitation method of step 301 is canceled, and the transducer array is excited by a non-vortex excitation method with the same amplitude and phase to illuminate the target, and the scattered signal of the target (such as Figure 9b As shown) perform data processing and analysis to determine the location of the target.

[0099] According to step 309, the two excitation modes of steps 301 and 308 are used alternately, and the received signals of the two modes are comprehensively analyzed to improve the target detection probability.

[0100] The two-dimensional and three-dimensional radiation patterns of the two application examples above show that, compared to non-vortex arrays, the phase-modulated vortex acoustic field produces very low scattered wave signal strength in the direction away from the scattering object, but at all other angles, the scattered wave signal strength is very high. This reduces the requirements for receiver placement, and the multistatic sonar system's receiver can receive a sufficiently strong signal in any direction other than away from the object, facilitating analysis and identification of the object. In practical applications, it is difficult to position the acoustic array and receiver on opposite sides of the same object. The receiver often forms various angles with the acoustic array and the object, resulting in very low received signals, even below background noise. Therefore, non-vortex back-facing sonar systems are inferior to vortex beam multistatic sonar systems in this respect. The vortex beam multistatic sonar system perfectly solves these problems by simply distributing receivers in different directions, offering significant application value.

[0101] In summary, the present invention provides a vortex beam multi-base underwater target detection device that utilizes a multi-base sonar system configuration with a vortex wave annular transmitting transducer array. Multiple signal receivers located in any direction of target scattering can receive acoustic signals of relatively high intensity, thereby achieving the purpose of detecting underwater targets. By using an annular acoustic array to form a vortex acoustic field with a central intensity of zero to illuminate the detection target, the present invention can achieve the function of detecting targets in any direction due to the special spatial distribution characteristics of the vortex acoustic beam, giving full play to the detection advantages of multi-base sonar and solving the practical problem of the prior art that targets cannot be detected at large separation angles. The vortex beam multi-base underwater target detection device can avoid the strict requirements of the non-vortex multi-base forward scattering beamforming method on the position of the receiving array, and shows good tolerance to the directional angle of the receiving array; the annular phase-modulated acoustic array can form acoustic beams of different shapes by adjusting the topological charge of the vortex sound field without changing the array shape, thereby realizing the detection of targets of different sizes; the phase modulation also includes the radiation mode of the non-vortex array without phase modulation, so that it has both the advantages of the non-vortex acoustic array and the advantages of the vortex array, and can choose to repeat the alternating working mode, so that the two modes complement each other, obtain target scattered signals at more azimuth angles within a 360° range around the target, and the obtained signal amplitude is stronger than that of a single working mode, thereby increasing the probability of target detection. The present invention can make up for the shortcomings of non-vortex multi-base sonar detection without giving up the advantages of non-vortex multi-base sonar, effectively solve the problem of direct wave suppression difficulty existing in current multi-base sonar detection, and has positive significance for the development and application of sonar detection technology.

[0102] The above is a further detailed description of the present invention in conjunction with specific preferred embodiments, and the specific implementation of the present invention should not be considered to be limited to these descriptions. For those skilled in the art of the present invention, without departing from the concept of the present invention, several simple deductions or substitutions can be made, which should be considered to fall within the scope of protection of the present invention.

Claims

1. A vortex beam multi-base underwater target detection device, characterized in that : It includes an annular vortex wave acoustic array composed of multiple transducers and multiple hydrophones distributed around the detection target; the annular vortex wave acoustic array is set on a base; the annular vortex wave acoustic array is composed of multiple transducers arranged in a circular ring; The target detection method based on the vortex beam multistatic underwater target detection device comprises the following steps: Step 301: Evenly arrange N transmitting transducers into a circular vortex wave acoustic array with a radius of R, and use an incremental phase modulation excitation method to make the circular vortex wave acoustic array generate a vortex sound field. In addition, the amplitude of each transducer remains the same, and the phase of each transducer increases by a fixed value at a time. Wherein, L is the topological charge of the vortex acoustic field; Step 302: Calculate the sound pressure generated by each transducer at any point Q(r,θ,φ) in space using the following formula: Among them, r s,Q is the distance from the transducer Ts to the Q point, a is the radius of the piston transducer, k is the wave number of the sound wave, ω is the angular frequency of the sound wave, ρ is the density of the propagation medium, u a is the amplitude of the piston transducer, A0=iωρu a a 2 / 2 is a constant; Step 303: Calculate the total sound field formed by the N transducers of the vortex sound field acoustic array using the following formula: Step 304: Draw the background sound field formed by the annular vortex wave acoustic array under different topological loads. In the spherical coordinate system, it is expressed as in, Step 305: The background sound field formed by the annular vortex wave acoustic array is irradiated on the target at any point Q(r,θ,φ) in space to form a scattered sound field represented by in, h n (x) is the first-order spherical Hankel function, The spherical coordinates of the location of the sth transducer are (r s ,θ s ,φ s ); Step 306: Calculate the radiation directivity diagram of the scattered far field under different topological charges based on the scattered sound field formed in step 305, and draw the spatial distribution diagram of the scattered sound field under different topological charges; Step 307: Draw a radiation pattern according to step 306, and deploy receiving hydrophones in the direction of the radiation pattern where the signal is larger, so as to receive scattered waves from the target, process and analyze the scattered signals of the target, and determine the position of the target; Step 308: cancel the incremental phase modulation excitation method of step 301, use the non-vortex excitation method with the same amplitude and phase to excite the transducer array, illuminate the target, process and analyze the scattered signal of the target, and determine the position of the target; Step 309: The two excitation modes of steps 301 and 309 are used alternately, and the two signals are analyzed comprehensively to improve the probability of detecting the target.

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