A subsurface acoustic detector

Abstract

The application discloses a liquid surface under sonar detection target, which is used for liquid surface under detection of a sonar device. The detection target comprises a target head, a support and a sound shadow tracking mechanism. When the detection target and the sonar device are simultaneously located on a liquid surface, the support is located in a sound shadow area range caused by the sonar wave emitted by the sonar device acting on the target head. When the detection target and the sonar device are simultaneously submerged under the liquid surface and the detection target is deformed, the support is kept in the sound shadow area range caused by the sonar wave emitted by the sonar device acting on the target head by the action of the sound shadow tracking mechanism. The sound shadow area formed by the detection target in the sonar wave range of the sonar device is utilized, the deformation of the support caused by the action force is reduced by the sound shadow tracking mechanism, the influence of the deformation on the test result is reduced, the support can be completely hidden in the sound shadow area, the reflection effect and the diffraction effect of the support are avoided, and the influence on the performance test result of the active sonar is greatly reduced.

Description

Technical Field

[0001] This invention relates to the field of sonar detection technology, and in particular to a sonar detection target under liquid surface. Background Technology

[0002] In testing the performance of active sonar, a sonar device is required to detect a target. A sonar device detection target is a known geometric object that reflects the sound waves emitted by the sonar device. To ensure the accuracy of the sonar device test, the sonar device detection target needs to be stably and accurately fixed in a specific position in the water. The positioning and fixing of the sonar device detection target is usually achieved through a target support.

[0003] However, during the testing of active sonar, the support structure itself also reflects and diffracts the detection sound waves emitted by the active sonar. Both the reflection and diffraction effects of the support structure can adversely affect the detection and testing of the target by the sonar equipment.

[0004] The reflection effect of the support structure: The acoustic signals reflected from the sonar equipment by the support structure and those reflected from the target are mixed together, affecting the sonar equipment's observation and measurement of the target. Especially when the support structure and the target are very close, the sonar equipment will simultaneously detect the very close target and the support structure, making it extremely difficult to distinguish whether the signal comes from the target or the support structure.

[0005] Diffraction effect of the support: The diffraction effect generates background noise, which propagates through multipath channels to the sonar equipment's receiving unit, causing specific patterns of interference within the sonar equipment's range. Because this background noise frequency is the same as the sonar equipment's operating frequency, the sonar equipment cannot filter out the background noise.

[0006] The reflection and diffraction effects of the support structure affect the evaluation of sonar equipment characteristics, especially for imaging sonar, where the impact is more severe, posing challenges to the research and development and verification of high-precision sonar systems.

[0007] Current solutions to this problem involve using low-reflectivity materials to fabricate the support frame, commonly plastics and composites. However, these materials have poor mechanical properties, leading to larger support frames to achieve the required mechanical strength. Larger frames generate more interference, ultimately worsening the acoustic environment for sonar testing. Another approach is to wrap the support frame with sound-absorbing material to reduce sound wave reflection. However, placing sound-absorbing material near the target can affect the sound field in that area, causing unpredictable changes in the sonar equipment's operating state. Neither using low-reflectivity materials nor wrapping with sound-absorbing material can reduce, but not eliminate, interference noise. Therefore, a detection target is needed to prevent interference with test results during active sonar performance testing. Summary of the Invention

[0008] The purpose of this invention is to provide a submerged sonar detection target that, during active sonar performance testing, ensures that the target support does not reflect the echo of the sonar equipment and does not affect the sound field near the detection target, thereby avoiding interference with the test results.

[0009] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0010] A submerged sonar detection target is provided for submerged detection by a sonar device. The detection target includes a target head, a support, and a sound shadow tracking mechanism. When the detection target and the sonar device are both on the liquid surface, the support is located within the sound shadow zone generated by the sonar waves emitted by the sonar device acting on the target head. When the detection target and the sonar device are both submerged and the detection target deforms, the support is maintained within the sound shadow zone generated by the sonar waves emitted by the sonar device acting on the target head by the sound shadow tracking mechanism.

[0011] Furthermore, the acoustic shadow tracking mechanism includes a float material arranged within the acoustic shadow zone. When the detection target and the sonar equipment are simultaneously submerged below the liquid surface, the float material provides a force to the detection target that is opposite to the direction of the target's deformation, thereby keeping the support within the acoustic shadow zone generated by the sonar waves emitted by the sonar equipment acting on the target head.

[0012] Furthermore, the float material wraps around the surface of the support and / or the float material is arranged near the target head to provide a force to the test target that is opposite to the direction of the test target's deformation.

[0013] Furthermore, the target and the support are rigidly connected.

[0014] Furthermore, the acoustic shadow tracking mechanism includes a fixing mechanism, which is located in the area below the center of the target head and formed on the support. When the detection target and the sonar equipment are simultaneously submerged in the liquid, the fixing mechanism between the support and the target head undergoes relative deformation, so that the support remains within the acoustic shadow zone generated by the sonar waves emitted by the sonar equipment acting on the target head.

[0015] Furthermore, the fixing mechanism can be in the form of a fixed rod.

[0016] Furthermore, the sound shadow tracking mechanism includes a balancing component formed on the target head. When the detection target and the sonar equipment are simultaneously submerged in the liquid, the support is adjusted relative to the target head by the balancing component, thereby maintaining its position within the sound shadow zone generated by the sonar waves emitted by the sonar equipment acting on the target head.

[0017] Furthermore, the balancing components include bearings, and the support is connected to the target head via the bearings with rotational freedom to adjust the relative angle.

[0018] Furthermore, the balancing components also include a counterweight rod and a counterweight block. The counterweight rod is connected to the counterweight block and located within the sound shadow zone. The counterweight rod is arranged below the bearing position.

[0019] Furthermore, the counterweight is a weight with a negative net buoyancy in water, which will sink in the water to adjust the center of gravity of the target.

[0020] Furthermore, the sound tracking mechanism also includes a damper that generates damping when the balancing components adjust their relative angles.

[0021] Furthermore, a damper is a device that uses friction or resistance to reduce vibration or oscillation effects, thereby consuming the energy of the detection target system and gradually reducing the amplitude of vibration or oscillation until it stops.

[0022] Furthermore, one end of the damper is connected to the support, and the other end is connected to the target head. During the oscillation of the target head, the energy of the target oscillation is dissipated through stretching and compression damping until the target stops oscillating and finally stabilizes at the equilibrium position.

[0023] Furthermore, the detection target also includes a base, which is set outside the range boundary of the sonar. The base is generally planar or spherical in shape, and the end of the support away from the target head is connected to the base, thereby generating different ranges of acoustic shadow zones depending on the shape of the base.

[0024] As used herein, sonar refers to an electronic device that utilizes the propagation and reflection characteristics of sonar waves in water to navigate and range underwater through electroacoustic conversion and information processing for detection (presence, location, properties, direction of movement, etc.) and communication with underwater targets. In this invention, "sonar device" is defined as a sonar used in active sonar performance testing to detect and evaluate targets, and to assess and calibrate sonar performance by examining the detection results.

[0025] Preferably, the sonar device in this invention is an active sonar device, which can detect targets by emitting sound waves and receiving the reflected sound waves. More preferably, the active sonar transmitter and receiver in this invention can be located in different positions.

[0026] As used in this article, the emitted sound field refers to the emitted sound field of a sonar device, that is, the sound wave distribution area formed in water when the sonar device emits sound waves. Preferably, depending on the shape and characteristics of the sonar emitting device, the emitted sound field can be distributed in a spherical, cylindrical, or other forms.

[0027] As used herein, a test target refers to an object that simulates a real marine environment in active sonar performance testing to test the detection performance of sonar equipment. The test target involved in this invention is a test target that is not independently movable relative to the support frame, in order to evaluate and calibrate the performance of the sonar equipment. Preferably, the size, shape, and arrangement of the test target are determined by the testing requirements, depending on the marine object it simulates.

[0028] As used in this article, a support refers to a device used to fix a test target in the test position, thereby maintaining the stability of the test target's position and orientation to facilitate the testing and evaluation of sonar equipment.

[0029] As used herein, the base refers to a device for fixing the support. In this invention, the base and the support work together to limit the position of the detection target. Preferably, depending on the test water area, the base can be placed on the bottom of the water, the seabed, the bottom of a pool, or fixed to a platform floating on the water surface.

[0030] As used in this article, the sound shadow zone refers to a region where the intensity of sonar waves is significantly reduced or almost nonexistent due to the propagation characteristics of sonar waves. Typically, the sound shadow zone is located behind an obstacle, where sonar waves are blocked or significantly weakened. This is because the obstacle creates a barrier, preventing sonar waves from reaching the area behind it.

[0031] As used in this article, the range boundary refers to the farthest distance that a sonar system can detect. For targets outside the range boundary, the sonar equipment cannot detect them or the detection effect is poor.

[0032] Preferably, the floating material refers to a material with a density lower than that of water.

[0033] More preferably, the float material includes materials such as polystyrene, polyurethane foam, polyethylene, PVC, or wood.

[0034] This invention provides a submerged sonar detection target. By utilizing the acoustic shadow zone formed by the detection target within the range of sonar waves generated by the sonar device, and through an acoustic shadow tracking mechanism, the influence of the deformation of the support caused by the force applied is reduced on the test results. This allows the support to be completely hidden within the acoustic shadow zone, thereby avoiding the reflection and diffraction effects of the support and greatly reducing the impact on the active sonar performance test results. Attached Figure Description

[0035] The above description of the present invention and the following detailed embodiments will be better understood when read in conjunction with the accompanying drawings. It should be noted that the drawings are merely examples of the claimed technical solutions.

[0036] Figure 1 This is a schematic diagram of a detection target in existing technology;

[0037] Figure 2 This is a schematic diagram of a detection target in the performance testing of active sonar in existing technology;

[0038] Figure 3 This is a test result diagram of the detection target in the existing technology;

[0039] Figure 4 This is a schematic diagram of the detection target of the first embodiment of the present invention in the performance test of a spherical wavefront active sonar.

[0040] Figure 5 This is a partial schematic diagram of the detection target of the first embodiment of the present invention in the performance test of a plane wavefront active sonar.

[0041] Figure 6 This is a test result diagram of the detection target according to the first embodiment of the present invention;

[0042] Figure 7 This is a schematic diagram of the force analysis of the target head and support in the detection target according to the first embodiment of the present invention;

[0043] Figure 8 This is a schematic diagram showing the position of the float material in the detection target according to the second embodiment of the present invention;

[0044] Figure 9 This is a schematic diagram of another location of the float material in the detection target according to the second embodiment of the present invention;

[0045] Figure 10 This is a schematic diagram of the connection between the target head and the support in the detection target according to the second embodiment of the present invention;

[0046] Figure 11 This is a schematic diagram of the force analysis of the float material in the detection target according to the second embodiment of the present invention;

[0047] Figure 12 This is a schematic diagram of the fixing mechanism in the detection target according to the third embodiment of the present invention;

[0048] Figure 13 This is a schematic diagram of the balancing component in the detection target according to the fourth embodiment of the present invention;

[0049] Figure 14 This is a schematic diagram of the force analysis of the balancing component in the detection target according to the fourth embodiment of the present invention;

[0050] Figure 15 This is a schematic diagram of the force analysis of the balancing component when detecting target deviation according to the fourth embodiment of the present invention;

[0051] Figure 16This is a schematic diagram of the cooperation between the balancing component and the damper in the detection target according to the fourth embodiment of the present invention;

[0052] Figure 17 This is a schematic diagram of a detection target in a plane wave front sonar device according to the fifth embodiment of the present invention.

[0053] Figure 18 yes Figure 17 Top view of the detection target;

[0054] Figure 19 yes Figure 17 A schematic diagram of the detection target in a sonar device on a spherical wavefront;

[0055] Figure 20 This is a schematic diagram of the detection target in the sonar device of the spherical wavefront according to the fifth embodiment of the present invention.

[0056] Figure 21 yes Figure 20 A schematic diagram of the detection target in a plane wavefront sonar device.

[0057] The reference numerals in the attached figures are explained as follows:

[0058] Sonar equipment: 1

[0059] Sound and shadow zone: 11

[0060] Emission sound field: 12

[0061] Range boundary: 13

[0062] Target: 21

[0063] Bracket: 22

[0064] Base: 23

[0065] Center line: 24

[0066] Sound and shadow tracking agency: 3

[0067] Floating material: 31

[0068] Balance components: 32

[0069] Bearings: 3211, 3221

[0070] Equivalent center of gravity: 3212

[0071] Counterweights: 3213, 3223

[0072] Counterweight bars: 3214, 3224

[0073] plumb line: 325

[0074] Dampers: 33

[0075] Fixed rod: 34

[0076] Groove: 35 Detailed Implementation

[0077] The following detailed description of the features and advantages of the present invention is sufficient to enable any person skilled in the art to understand the technical content of the present invention and implement it accordingly. Furthermore, based on the specification, claims and drawings disclosed herein, those skilled in the art can easily understand the related objects and advantages of the present invention.

[0078] It should be noted that in this specification, similar reference numerals and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0079] In the description of this embodiment, it should be noted that the terms "upper", "lower", "inner", "bottom", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the product is usually placed during use. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting the present invention.

[0080] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0081] like Figure 1-2 The detection target proposed in the prior art, in the test of active sonar performance, is fixed by selecting the shortest route to extend the bracket 22 through the emission sound field 12 to the base 23 for fixation. Therefore, the bracket 22 will be exposed to the emission sound field 12 of the sonar device 1.

[0082] like Figure 3 As shown, when the support 22 is exposed to the emitted sound field 12 of the sonar device 1, the support 22 will simultaneously form an image with the target 21 in the detection image of the sonar device 1. When evaluating sonar performance, the images of the support 22 and the target 21 are mixed together, which is not conducive to the tester's evaluation of the image quality of the sonar device and often affects the evaluation of the characteristics of the sonar device.

[0083] To address the shortcomings of existing detection targets, such as... Figure 4-5The first embodiment of the present invention shown is a submerged sonar detection target for submerged detection of a sonar device 1. The detection target includes a target head 21 and a support 22. When the detection target and the sonar device 1 are both located on the liquid surface, the support 22 is located within the range of different shaped acoustic shadow zones 11 generated by the sonar waves emitted by the sonar device 1 acting on the target head 21. This facilitates the placement of the support 22 within the acoustic shadow zone 11 generated by the target head 21, thereby achieving the undetectability of the support 22 by the sonar device 1. When in use, the sonar wave emitted by the sonar device 1 encounters the target head 21 and will reflect the signal (i.e., echo signal) to the receiver of the sonar device 1 to form an image detection result. The sonar wave forms a sound shadow zone 11 behind the target head 21, where the sonar wave is blocked or significantly weakened. This invention utilizes the sound shadow zone 11 formed behind the target head 21 and sets up a support 22 for the detection target in the sound shadow zone 11 to hide it, thereby avoiding the interaction between the support 22 and the sound field emitted by the sonar device 1 and avoiding errors in the test results of the sonar device 1.

[0084] The present invention also provides an upward force to the support 22 by setting an acoustic shadow tracking mechanism 3 to avoid deformation of the support 22 caused by the downward force in seawater, which would lead to errors in the detection results. When the detection target and the sonar device 1 are submerged in the liquid and the detection target deforms, the support 22 is kept within the acoustic shadow zone 11 generated by the sonar wave emitted by the sonar device 1 acting on the target head 21 by the action of the acoustic shadow tracking mechanism 3.

[0085] like Figure 6 The active sonar performance test results of the present invention clearly show the detection target (i.e., target head 21) without any interference. In particular, the support 22 is located in the undetectable area (sound shadow area 11) behind the target head 21 to eliminate the image interference of the support. This shows that the active sonar performance test of the detection target provided by the present invention does not reflect the echo of the sonar device 1 and does not affect the sound field near the detection target, which greatly reduces the impact on the active sonar performance test results.

[0086] This invention discovers that in practical applications, detection targets often employ a horizontally arranged support 22 in the form of a cantilever beam. In this case, one end of the support 22 is fixed to the base, and the other end supports the target head 21 to form the acoustic shadow zone 11. When the application length of the support 22 is relatively long or the weight of the target head 21 is large, according to... Figure 7It can be seen that the target head 21 and support 22, submerged in the liquid (i.e., seawater), are subjected to forces. The target, under the influence of gravity and buoyancy, exhibits negative buoyancy in seawater, with these forces distributed throughout the target. At this point, the gravity acting on the target is greater than the buoyancy provided by the seawater, resulting in a downward force. The support 22 experiences a downward force, causing it to bend and deform downwards. In particular, when the density of the material used for the support 22 is greater than that of seawater, its gravity further exceeds the buoyancy, exacerbating the downward bending deformation of the support 22 and generating shear stress.

[0087] However, the bending deformation of the support 22 will have two adverse effects on the measurement of the target. The first effect is the downward shift of the fulcrum of the target head 21; the second effect is the downward rotation caused by the torsion of the cantilever beam of the support 22.

[0088] The downward shift of the fulcrum of the target head 21 will cause the acoustic shadow zone 11 generated by the sonar device 1 acting on the target head 21 to move downward, which may cause the support structure 22 to detach from the acoustic shadow zone 11 and be detected by the sonar device 1. In addition, when the target offset is too large, there is also a possibility that the target may go beyond the area of ​​the sound field 12 emitted by the sonar device 1.

[0089] The downward rotation of the support 22 will cause a change in the projection of the detection target on the wavefront, resulting in errors when the sonar device 1 receives the detection results from the detection target. In addition, since the size and shape of the acoustic shadow zone 11 depend on the size and shape of the target head 21, the rotation of the detection target will also cause the cross-section of the acoustic shadow zone 11 to shrink, affecting the range of the acoustic shadow zone 11 generated by the sonar device 1 acting on the target head 21.

[0090] These two adverse effects stem from the deformation of the support 22. This deformation occurs because the support 22 is not subjected to buoyancy neutrality in seawater. The forces acting on the support 22 come from three sources: the support force provided to the target by the fixed device, the weight of the support 22 itself, and the buoyancy provided by the water. Specifically, the support force on the end of the support 22 closest to the fixed device is vertical and equal to the sum of the weight and buoyancy. The end of the support 22 furthest from the fixed device deforms downwards due to the weight of the target head 21. Existing active sonar performance test results for the target are as follows... Figure 2 As shown, it can be seen Figure 2 The resulting chaotic light and shadow patterns are caused by the deformation of the support 22, which causes it to appear in the emitted sound field 12 region, thus reflecting and diffracting the sonar waves and causing interference. This significantly affects the performance testing results of the sonar device 1 and the judgment of its practical application. Therefore, this invention solves the above-mentioned adverse effects by proposing a sound and shadow tracking mechanism 3.

[0091] In a second embodiment of the present invention, a submerged sonar detection target is provided for submerged detection of a sonar device 1. The detection target includes a target head 21, a support 22, and a sound shadow tracking mechanism 3. When the detection target and the sonar device 1 are simultaneously located on the liquid surface, the support 22 is located within the sound shadow zone 11 generated by the sonar waves emitted by the sonar device 1 acting on the target head 21. When the detection target and the sonar device 1 are simultaneously submerged and the detection target deforms, the support 22 is maintained within the sound shadow zone 11 generated by the sonar waves emitted by the sonar device 1 acting on the target head 21 by the sound shadow tracking mechanism 3.

[0092] like Figure 8 As shown, the sound shadow tracking mechanism 3 is a float 31, which is arranged within the sound shadow zone 11. When the detection target and the sonar device 1 are simultaneously submerged in the liquid, the float 31 wraps around the surface of the support 22 to provide a force to the support 22 opposite to the direction of deformation, thereby keeping the support 22 within the sound shadow zone 11 generated by the sonar waves emitted by the sonar device 1 acting on the target head 21. The cross-sectional area of ​​the sound shadow zone 11 generated by the sonar waves emitted by the sonar device 1 acting on the target head 21 is larger than the cross-sectional area required for the structural strength of the support 22. This invention utilizes this space to arrange the float 31 to generate more buoyancy, providing additional buoyancy to the support 22, reducing the counterforce required by the support 22, offsetting the weight of the support 22, and preventing the support 22 from moving downwards beyond the range of the sound shadow zone 11, affecting the emitted sound field 12 of the sonar device 1, and causing the support 22 to be detected by the sonar, thus affecting the test results.

[0093] Specifically, float 31 is a solid material with a density less than that of water. When float 31 is immersed in water, it can generate positive buoyancy to provide additional buoyancy for the detection target, so that the buoyancy generated by float 31 and the detection target is equal to the weight of the detection target and float 31. In this way, the weight of the detection target itself is completely offset by the buoyancy generated by float 31, and the detection target can eliminate bending deformation and present an ideal horizontal state.

[0094] In another implementation, such as Figure 9 As shown, the float 31 can be arranged near the target head 21 to provide a force opposite to the deformation direction of the target head 21, providing additional buoyancy to counteract the weight of the target head 21. By adding counterweights or float 31, the target head 21 can achieve a neutral buoyancy state. This prevents the downward displacement of the fulcrum of the target head 21 from causing changes in the range of the acoustic shadow zone 11, and further provides the support 22 with deformation margin within the acoustic shadow zone 11, thereby ensuring that the support 22 remains within the acoustic shadow zone 11 generated by the sonar waves emitted by the sonar device 1 acting on the target head 21 when it deforms.

[0095] Specifically, the float 31 can also simultaneously wrap the surface of the support 22 and be arranged near the target 21. At this time, the structure of the support 22 is in a state of neutral stress in the seawater and does not undergo any deformation. The resultant force on the structures of the support 22 and the target 21 in the seawater is zero, and the support 22 does not need to provide any shear stress. Therefore, the detection target can remain in a state of no deformation.

[0096] It should be noted that although the force applied to the target head 21 and the float 31 is equal in magnitude and opposite in direction through the sound and shadow tracking mechanism, resulting in a net force of 0, a torque is generated because the force points are not at the same point. This torque tends to rotate the overall structure formed by the target head 21 and the float 31, thus causing a change in the range of the sound and shadow zone 11. Therefore, this invention discovers that the generated torque can be canceled out by the rigid connection between the target head 21 and the support 22. In this way, the rigid connection between the target head 21 and the support 22 locks the angle of the target head 21, thereby avoiding affecting the stability of the target head 21 at that angle.

[0097] More specifically, such as Figure 10 As shown, the target head 21 and the support 22 can be connected by a fixing rod 34. The fixing rod 34 is embedded in the groove 35 provided on the support 22 to form a rigid connection between the target head 21 and the support 22. By configuring the volume of the float 31, the positive buoyancy provided by the float 31 and the negative buoyancy (the resultant force of gravity and buoyancy) of the target head 21 and the fixing rod 34 are equal in magnitude and opposite in direction, so that the net buoyancy of the target head 21, float 31 and fixing rod 34 structure is zero, forming a neutral buoyancy detection target.

[0098] pass Figure 11 The force analysis of the detection target shown yields Formula 1:

[0099] F 检测标靶重力 +F 浮材重力 =F 检测标靶浮力 +F 浮材浮力 (Formula 1)

[0100] In a third embodiment of the present invention, a submerged sonar detection target is provided for submerged detection of a sonar device 1. The detection target includes a target head 21, a support 22, and a sound shadow tracking mechanism 3. When the detection target and the sonar device 1 are simultaneously located on the liquid surface, the support 22 is located within the sound shadow zone 11 generated by the sonar waves emitted by the sonar device 1 acting on the target head 21. When the detection target and the sonar device 1 are simultaneously submerged and the detection target deforms, the support 22 is maintained within the sound shadow zone 11 generated by the sonar waves emitted by the sonar device 1 acting on the target head 21 by the sound shadow tracking mechanism 3.

[0101] like Figure 12As shown, the acoustic shadow tracking mechanism 3 is a fixed rod type fixing mechanism. The fixed rod 34 is located in the area below the center line 24 of the target head 21 and is formed on the support 22. The fixed rod 34 is connected to both the target head 21 and the support 22. When the detection target and the sonar device 1 are simultaneously submerged in the liquid, the fixed rod 34 between the support 22 and the target head 21 undergoes relative deformation. When the support 22 is subjected to the downward bending force of gravity, more allowance is left within the acoustic shadow zone 11 generated by the sonar waves emitted by the sonar device 1 acting on the target head 21 for the support 22 to deform. This ensures that when the support 22 deforms, it remains within the acoustic shadow zone 11 generated by the sonar waves emitted by the sonar device 1 acting on the target head 21, preventing the support 22 from exceeding the acoustic shadow zone 11 and affecting the test results. Specifically, when the maximum length and minimum distance of the test target surface are not the same, the maximum length of the test target can be arranged in the vertical direction, and the fixing rod 34 can be arranged below the center of the test target in the vertical direction. This can obtain a larger sound shadow zone 11 in the vertical direction, providing a larger margin for the deformation of the support 22 to be hidden in the sound shadow zone 11. More specifically, in order to facilitate storage or flexible replacement of the target head 21, the target head 21 and the support 22 are often designed as a separable structure, and the two are fixed together by the fixing rod 34.

[0102] In a fourth embodiment of the present invention, a submerged sonar detection target is provided for submerged detection of a sonar device 1. The detection target includes a target head 21, a support 22, and a sound shadow tracking mechanism 3. When the detection target and the sonar device 1 are simultaneously located on the liquid surface, the support 22 is located within the sound shadow zone 11 generated by the sonar waves emitted by the sonar device 1 acting on the target head 21. When the detection target and the sonar device 1 are simultaneously submerged and the detection target deforms, the support 22 is maintained within the sound shadow zone 11 generated by the sonar waves emitted by the sonar device 1 acting on the target head 21 by the sound shadow tracking mechanism 3.

[0103] like Figure 13-15 As shown, the sound and shadow tracking mechanism 3 includes a balancing component 32, which is formed on the target head 21. The balancing component 32 has a bearing 3211, a counterweight rod 3214, and a counterweight block 3213. The support 22 is connected to the target head 21 with rotational freedom via the bearing 3211 to adjust the relative angle between the target head 21 and the support 22. The counterweight rod 3214 is connected to the counterweight block 3213 and located within the sound and shadow zone 11. The counterweight rod 3214 is arranged below the bearing 3211. When the detection target and the sonar device 1 are simultaneously submerged in the liquid, the target head 21 is connected via the counterweight rod 3214 and the counterweight block 3213, and a suitable length of the counterweight rod 3214 and weight of the counterweight block 3213 are set. At this time, the equivalent center of gravity 3212 of the target head 21, the counterweight rod 3214, and the counterweight block 3213 is formed directly below the bearing 3211. Figure 10As shown by the dashed line. In this way, the target head 21 can rotate along the horizontal axis, thereby allowing the target head 21 to automatically balance. Figure 11 The balancing component 32 forms an adaptive calibration structure for the detection target, positioning the target's center of gravity below the vertical line 325 of the target connection point. Angle adjustment is achieved through a rotational connection between the target head 21 and the support 22. The stable equilibrium position of the target head 21 is its designed working position, preventing changes in the acoustic shadow zone 11 caused by target head 21 fulcrum offset. This ensures the target head 21 always faces the correct direction, providing the support 22 with deformation margin within the acoustic shadow zone 11, keeping the support 22 within the acoustic shadow zone 11 created by the sonar waves emitted by the sonar device 1 acting on the target head 21. Simultaneously, during the adaptive calibration of the detection target by the balancing component 32, the rotational deformation of the support 22 is also eliminated by the balancing component 32.

[0104] like Figure 15 As shown, when the target rotates, its center of gravity shifts off the vertical line 325 below bearing 3211, with a horizontal displacement of D. The gravitational force F and the supporting force F are equal in magnitude and opposite in direction, resulting in a force balance on the target. However, since the gravitational force F and the supporting force F are not on the same straight line, a torque will be generated, with a magnitude of F_gravity × D. This torque will return the target to its equilibrium position.

[0105] In another implementation, such as Figure 16 As shown, the sound shadow tracking mechanism 3 also includes a damper 33. The damper 33 generates damping when the balancing component 32 adjusts its relative angle. The balancing component 32 has a bearing 3221, a counterweight rod 3224, and a counterweight block 3223. The support 22 is connected to the target head 21 with rotational freedom via the bearing 3221 to adjust the relative angle between the target head 21 and the support 22. The counterweight rod 3224 is connected to the counterweight block 3223 and is located within the sound shadow zone 11. The counterweight rod 3224 is arranged below the bearing 3221. The damping device used in this invention does not affect the stable balance position of the target head 21, and can absorb energy to prevent the target head 21 from swinging near the stable balance position for a long time, which would prevent the active sonar performance from being tested.

[0106] In a fifth embodiment of the present invention, multiple detection targets can be arranged on a base 23, which is located outside the range boundary 13 of the sonar device 1. The end of the bracket 22 away from the target head 21 is connected to the base 23. Since the detection range of the sonar device 1 is limited, it cannot detect objects outside the range boundary 13. The present invention discovers that the property that the sonar device 1 cannot detect objects outside its range can be utilized by extending the bracket 22 beyond the range boundary 13 of the sonar device 1 through the acoustic shadow zone 11 and then fixing it to the base, thereby ensuring that the bracket 22 of the detection target is undetectable during the testing of sonar performance.

[0107] In this invention, since the transmitting units of sonar device 1 have different types, the shape (wavefront) of the emitted sound field 12 is different for different types of transmitting units. The wavefront of a point source is part of a sphere. In the region close to sonar device 1, the wavefront should be modeled as a sphere; while in the region far from sonar device 1, the wavefront can be approximated as a plane. A planar wavefront can be generated by controlling the phase of the sound source matrix. In the testing of active sonar performance, the range of the sound shadow zone 11 needs to be adjusted accordingly based on the different wavefronts to prevent the support 22 from being exposed in the emitted sound field 12 of sonar device 1 and thus being detected by sonar device 1, affecting the echo signal of the detection target. Therefore, the design of the detection target must be modified to adapt to the pattern of the sound shadow zone 11 to ensure that the support 22 remains in the sound shadow zone 11 during active sonar performance testing.

[0108] Specifically, the base 23 is flat. For example... Figure 17-18 As shown, for the plane wavefront sonar device 1, the edges of the sound shadow zone 11 generated by the detection target are parallel to each other. Supports 22 are arranged in a parallel pattern on the plane base 23, preferably with a centrally symmetrical arrangement. This minimizes the possibility of the supports 22 entering the sound field 12 emitted by the sonar device 1, thus keeping the supports 22 within the sound shadow zone 11. In use, the target head 21 is fixed to the base 23 by the supports 22. When the plane wavefront propagates in a direction parallel to the axis of the supports 22, the supports 22 can be completely hidden within the sound shadow zone 11, without interfering with the sound field reflected by the target head 21.

[0109] like Figure 19 As shown, when the planar base 23 is applied to the sonar device 1 with a spherical wavefront, the sonar waves of the sonar device 1 will reach part of the support 22 and be reflected, resulting in a shadowed area in the test results, which affects the detection effect and the judgment of the performance of the sonar device 1.

[0110] Specifically, the base 23 is spherical. In this invention, for the active sonar device 1 with a point sound source, the wavefront is spherical. In this case, the acoustic shadow zone 11 generated by the target 21 diverges in a centrally symmetrical manner, especially when multiple targets 21 exist, the contour of the acoustic shadow zone 11 of the detected target is centrally symmetrical. Therefore, arranging the support 22 on the spherical base 23 in a spherical outward divergence pattern centered on the point emission array of the sonar device 1 minimizes the possibility of the support 22 entering the emitted sound field 12 of the sonar device 1. Figure 20 As shown, a linearly and equally spaced detection target is displayed, wherein the brackets 22 are arranged along the radial direction of the spherical wavefront. At this time, the extended lines of the central axes of the brackets 22 intersect at the center of the wavefront, that is, the center of the transmitting unit of the active sonar device 1, which further ensures that the brackets 22 are always kept in the acoustic shadow zone 11 to avoid affecting the test results.

[0111] like Figure 21 As shown, the spherical base 23 is poorly suited for use in the plane wave array sonar device 1. It can be seen that part of the support 22 is exposed in the emitted sound field 12 of the sonar device 1. For the plane wave array, the exposed support 22 structure will generate reflection, which will be imaged in the sonar device 1 and interfere with the detection of the target.

[0112] Specifically, the bracket 22 ultimately needs to be fixed to the base 23, but the base 23 cannot necessarily be completely hidden outside the measurement range. This problem can be solved in two ways. The first method is to use a sufficiently long bracket 22 to hide the base 23 outside the measurement range boundary 13 of the sonar device 1. This method has no impact on the imaging of the target. The second method is to design the base 23 in a location that is not of interest to the emitted sound field 12 of the sonar device 1. In the performance testing of the sonar device 1, a position far from the target has no impact on the imaging of the target. Therefore, the base can be placed far from the target, and the target can be fixed by the bracket 22 hidden in the sound shadow zone 11.

[0113] More specifically, when the detection range of sonar device 1 is much greater than the distance between the target and sonar device 1, it may be difficult to extend the support 22 beyond its measurement range. In this case, the support 22 must be fixed within the measurement range boundary 13 of sonar device 1, away from the acoustic shadow zone 11. In this situation, it is impossible to completely hide the support 22 and the base 23, but the impact of the support 22 and the base 23 on the target measurement can be minimized. In this testing scenario, the key area of ​​concern is the space near the target; areas far from the target and sonar device 1 have less impact on the measurement. Therefore, the portion of the support 22 near the target can be hidden using the acoustic shadow zone 11. After the support 22 leaves the area of ​​concern using the acoustic shadow zone 11, it leaves the acoustic shadow zone 11 again and is fixed to the base 23, thus achieving the undetectability of the support 22 within the target in the key testing area.

[0114] The terminology and expressions used herein are for descriptive purposes only, and the invention should not be limited to these terms and expressions. The use of these terms and expressions does not imply the exclusion of any illustrative and descriptive equivalents (or parts thereof), and it should be recognized that various modifications that may exist should also be included within the scope of the claims. Other modifications, variations, and substitutions may also exist. Accordingly, the claims should be considered to cover all such equivalents.

[0115] Similarly, it should be noted that although the present invention has been described with reference to the specific embodiments described above, those skilled in the art should recognize that the above embodiments are only used to illustrate the present invention, and various equivalent changes or substitutions can be made without departing from the spirit of the present invention. Therefore, any changes or modifications to the above embodiments within the scope of the essential spirit of the present invention will fall within the scope of the claims of the present invention.

Claims

1. A submerged sonar detection target, used for submerged detection in sonar equipment, characterized in that, The detection target includes a target head, a support, and a sound shadow tracking mechanism. When the detection target and the sonar device are both on the liquid surface, the support is located within the sound shadow zone generated by the sonar waves emitted by the sonar device acting on the target head. When the detection target and the sonar device are both submerged below the liquid surface, causing the detection target to deform, the support is maintained within the sound shadow zone generated by the sonar waves emitted by the sonar device acting on the target head by the sound shadow tracking mechanism.

2. The submerged sonar detection target according to claim 1, characterized in that, The acoustic shadow tracking mechanism includes a float material arranged within the acoustic shadow zone. When the detection target and the sonar device are simultaneously submerged in the liquid, the float material provides a force to the detection target that is opposite to the direction of the target's deformation, thereby keeping the support within the acoustic shadow zone generated by the sonar waves emitted by the sonar device acting on the target head.

3. The submerged sonar detection target according to claim 2, characterized in that, The float wraps around the surface of the support and / or the float is arranged near the target head to provide a force to the detection target opposite to the direction of the target's deformation.

4. The submerged sonar detection target according to claim 3, characterized in that, The target head and the support are rigidly connected.

5. The submerged sonar detection target according to claim 1, characterized in that, The sound and shadow tracking mechanism includes a fixing mechanism, which is located in the area below the center of the target and formed on the support. When the detection target and the sonar device are simultaneously submerged in the liquid, the fixing mechanism between the support and the target undergoes relative deformation, so that the support remains within the sound and shadow zone generated by the sonar waves emitted by the sonar device acting on the target.

6. The submerged sonar detection target according to claim 1, characterized in that, The sound and shadow tracking mechanism includes a balancing component formed on the target head. When the detection target and the sonar device are simultaneously submerged in the liquid, the support is adjusted relative to the target head by the balancing component, thereby maintaining its position within the sound and shadow zone generated by the sonar waves emitted by the sonar device acting on the target head.

7. The submerged sonar detection target according to claim 6, characterized in that, The balancing component includes a bearing, and the bracket is connected to the target head via the bearing with rotational freedom to adjust the relative angle.

8. The submerged sonar detection target according to claim 7, characterized in that, The balancing component also includes a counterweight rod and a counterweight block. The counterweight rod is connected to the counterweight block and located within the sound shadow zone. The counterweight rod is arranged below the bearing position.

9. The submerged sonar detection target according to claim 6, characterized in that, The sound and shadow tracking mechanism also includes a damper that generates damping when the balancing component adjusts the relative angle.

10. The submerged sonar detection target according to claim 1, characterized in that, The detection target also includes a base, which is located outside the range boundary of the sonar. The base is generally planar or spherical in shape. The end of the support away from the target head is connected to the base, thereby generating different ranges of the acoustic shadow zone according to the shape of the base.

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