A method, apparatus and storage medium for sound field cancellation

Abstract

This invention provides a sound field cancellation method, apparatus, and storage medium thereof. The sound field cancellation method acquires the primary source sound field reflected from a primary source; it calculates the secondary source sound field based on the primary source sound field, wherein the secondary source sound field is the sound field emitted by a preset secondary source transmitting device, so as to minimize the total sound field after cancellation between the secondary source sound field and the primary source sound field. By minimizing the total sound field formed by the primary source sound field reflected from the primary source and the secondary source sound field, the detection of sonar signals is weakened, helping to solve the technical problem of the lack of methods for weakening sonar signals in the prior art.

Description

Technical fields:

[0001] This invention relates to the field of sound field control, and in particular to a sound field cancellation method, apparatus and storage medium thereof. Background technology:

[0002] With continuous advancements in vibration and noise reduction technologies, the radiated noise of submarines in various countries has steadily decreased. Under these circumstances, detecting, locating, and continuously tracking submarines using passive sonar (between submarines, and between surface ships) has become increasingly difficult. Meanwhile, long-range low-frequency detection from airborne dipping active sonar, surface submarine active sonar, and combined active-passive towed sonar poses a growing threat to submarines. The minimum operating frequency of active sonar on US Navy underwater reconnaissance ships, exemplified by the USS Impeccable, has already dropped below 500Hz, and this trend shows further reduction. Therefore, low-frequency acoustic stealth is a key technology in modern underwater warfare.

[0003] Acoustic stealth of underwater targets is divided into passive stealth and active stealth. Passive stealth has a longer development history and higher technological maturity. Passive stealth methods mainly include shape and structural design and the application of acoustic metamaterials on the target surface. However, passive stealth is limited by physical conditions, and its acoustic stealth performance deteriorates in the low-frequency range. Active stealth can reduce the target's strength without limiting the target's own performance, thereby reducing the probability of detection. Therefore, whether in the field of stealth against radar electromagnetic waves for aircraft or in the field of acoustic stealth for underwater targets, active stealth is a very important direction of stealth technology.

[0004] There is an urgent need for a sound field cancellation method, which would help solve the technical problem of the lack of methods to weaken sonar signals in existing technologies. Summary of the Invention:

[0005] In one embodiment, the present invention provides a sound field cancellation method that minimizes the total sound field formed by the primary source sound field reflected from the primary source and the secondary source sound field, thereby weakening the detection of sonar signals and helping to solve the technical problem of the lack of methods for weakening sonar signals in the prior art.

[0006] Obtain the primary source sound field reflected from the primary source;

[0007] The secondary source sound field is calculated based on the primary source sound field, wherein the secondary source sound field is the sound field emitted by a preset secondary source emitting device, so as to minimize the total sound field after the secondary source sound field cancels out the primary source sound field.

[0008] In one embodiment, calculating the secondary source sound field based on the primary source sound field includes:

[0009] The primary source sound field is decomposed into a first-direction sound field and a second-direction sound field using matrix SVD.

[0010] The first emission weight vector matrix and the second generation weight vector matrix are calculated based on the first directional sound field and the second directional sound field, respectively.

[0011] The secondary source sound field is calculated based on the first emission weight vector matrix and the second generation weight vector matrix.

[0012] In one embodiment, the first direction is the pitch direction, and the second direction is the horizontal direction.

[0013] In one embodiment, the primary source sound field is a scattered sound field.

[0014] In one embodiment, the scattered sound field is a rigid column with a limited length.

[0015] In one embodiment, the primary source is the surface of a submarine.

[0016] In one embodiment, the secondary source emission device is positioned on the surface of the submarine.

[0017] In one embodiment, the present invention also provides a sound field cancellation device, the device comprising:

[0018] The acquisition module is used to acquire the primary source sound field reflected from the primary source;

[0019] The calculation module is used to calculate the secondary source sound field based on the primary source sound field, wherein the secondary source sound field is the sound field emitted by a preset secondary source emitting device, so as to minimize the total sound field after the secondary source sound field cancels out the primary source sound field.

[0020] In one embodiment, the present invention also provides a sound field cancellation device, the device comprising: a processor and a memory;

[0021] The memory stores an application program that can be executed by the processor, which causes the processor to perform the steps of the sound field cancellation method as described above.

[0022] In one embodiment, the present invention also provides a computer-readable storage medium having a computer program stored thereon that, when executed by a processor, implements the steps of any of the sound field cancellation methods described herein. Attached image description:

[0023] Figure 1 This is a schematic diagram of the sound field cancellation method in one embodiment of the present invention (flow 100).

[0024] Figure 2 This is a schematic diagram of the sound field cancellation method in another embodiment of the present invention, 200.

[0025] Figure 3This is a schematic diagram of the scattering sound field model of a finite-length rigid cylinder in another embodiment of the present invention;

[0026] Figure 4 This is a schematic diagram showing the distribution of far-field scattered sound pressure in different directions in another embodiment of the present invention;

[0027] Figure 5 This is a schematic diagram of the secondary source location distribution in another embodiment of the present invention;

[0028] Figure 6 This is a schematic diagram of the circumferential distribution in another embodiment of the present invention;

[0029] Figure 7 This is a schematic diagram of a linear distribution in another embodiment of the present invention;

[0030] Figure 8 This is a schematic diagram of the feature value sequence number in another embodiment of the present invention;

[0031] Figure 9 This is a schematic diagram of the amplitude and phase of the sound pressure field of the maximum eigenvalue scattered sound field obtained by SVD decomposition with respect to theta in another embodiment of the present invention;

[0032] Figure 10 This is a schematic diagram of the sound pressure amplitude and phase of the maximum eigenvalue scattered sound field obtained by SVD decomposition in another embodiment of the present invention with respect to phi;

[0033] Figure 11 This is a schematic diagram of the scattered sound field corresponding to the maximum eigenvalue obtained by SVD decomposition in another embodiment of the present invention;

[0034] Figure 12 This is a schematic diagram illustrating the difference between the original scattered sound field and the scattered sound field corresponding to the maximum eigenvalue obtained from SVD decomposition in another embodiment of the present invention.

[0035] Figure 13 This is a schematic diagram comparing the emitted controlled sound field in the phi direction with the scattered sound field corresponding to the maximum eigenvalue obtained by SVD decomposition in another embodiment of the present invention.

[0036] Figure 14 This is a schematic diagram comparing the sound pressure amplitude of the scattered sound field before and after active cancellation in the phi direction in another embodiment of the present invention;

[0037] Figure 15 This is a schematic diagram comparing the emitted controlled sound field in the theta direction with the scattered sound field corresponding to the maximum eigenvalue obtained by SVD decomposition in another embodiment of the present invention.

[0038] Figure 16This is a schematic diagram comparing the sound pressure amplitude of the scattered sound field before and after active cancellation in the theta direction in another embodiment of the present invention;

[0039] Figure 17 This is a schematic diagram comparing the sound pressure amplitude of the scattered sound field before and after active cancellation in a three-dimensional spatial direction 10km away from the target center, according to another embodiment of the present invention.

[0040] Figure 18 This is a schematic diagram comparing the sound pressure amplitude of the scattered sound field before and after active cancellation at different distances from the target center, with directions theta = 45°, phi = 180° and distances from the target center ranging from 5km to 100km.

[0041] Figure 19 This is a schematic diagram comparing the sound pressure amplitude of the scattered sound field before and after active cancellation at different distances from the target center, with the direction theta = 45°, phi = 0° and a distance from the target center of 5km-100km.

[0042] Figure 20 This is a schematic diagram comparing the sound pressure amplitude of the scattered sound field before and after active cancellation at different distances from the target center, with directions theta = 135°, phi = 180° and distances from the target center ranging from 5km to 100km.

[0043] Figure 21 This is a schematic diagram comparing the sound pressure amplitude of the scattered sound field before and after active cancellation at different distances from the target center, with directions theta = 135°, phi = 0°, and distances from the target center ranging from 5km to 100km.

[0044] Figure 22 This is a schematic diagram comparing the sound pressure amplitude of the scattered sound field before and after active cancellation at different distances from the target center, with directions theta = 45°, phi = 90° and distances from the target center ranging from 5km to 100km.

[0045] Figure 23 This is a schematic diagram comparing the sound pressure amplitude of the scattered sound field before and after active cancellation at different distances from the target center, with directions theta = 60°, phi = 180°, and distances from the target center ranging from 5km to 100km. Specific implementation examples:

[0046] For this invention, we take submarines as an example. For underwater combat targets, active stealth can be divided into the elimination of radiated sound fields and the elimination of scattered sound fields, depending on the target being eliminated. Active elimination of radiated sound fields mainly involves eliminating the line spectrum noise of the platform itself, and the noise source can be represented by several equivalent sources. Active elimination of scattered sound fields involves eliminating the scattered sound field generated by the scattering of sound waves emitted by enemy active sonar on the target surface. The sound wave signal depends on the emitted signal of the enemy active sonar and the overall scattering characteristics of the target. Research on active elimination of radiated sound fields is more extensive and mature than that on active elimination of scattered sound fields. This invention mainly addresses the control of the scattered sound field of underwater targets.

[0047] It should be noted that the underwater submarine method is only for better illustrating the present invention and is not a specific limitation of the present invention.

[0048] Figure 1 This is a schematic diagram of the sound field cancellation method in one embodiment of the present invention, specifically flow 100. Figure 1 As shown, in one embodiment, the present invention provides a sound field cancellation method, the sound field cancellation method comprising:

[0049] S101, Obtain the primary source sound field reflected from the primary source.

[0050] This step provides a specific procedure for obtaining the primary source sound field reflected from the primary source.

[0051] S102, calculate the secondary source sound field based on the primary source sound field, wherein the secondary source sound field is the sound field emitted by a preset secondary source emitting device, so as to minimize the total sound field after the secondary source sound field cancels out the primary source sound field.

[0052] This step provides a specific method for calculating the secondary source sound field based on the primary source sound field, wherein the secondary source sound field is the sound field emitted by a preset secondary source emitting device, so as to minimize the total sound field after the secondary source sound field cancels out the primary source sound field.

[0053] This embodiment provides a specific implementation of a sound field cancellation method. Firstly, the primary source sound field is acquired. This primary source sound field is the sound field reflected from the sonar detection itself, and our goal is to cancel this sound field. Therefore, the first step is to acquire this sound field. Then, based on the primary source sound field, a secondary source device is used to generate a sound field that can cancel it out, ultimately achieving the goal of minimizing the total sound field. This helps to solve the technical problem of the lack of methods for weakening sonar signals in the prior art.

[0054] Figure 2 This is a schematic diagram of flow 200 for a sound field cancellation method in another embodiment of the present invention. (See diagram 200.) Figure 2As shown, in one embodiment, calculating the secondary source sound field based on the primary source sound field includes:

[0055] S201, the primary source sound field is decomposed into a first direction sound field and a second direction sound field by matrix SVD.

[0056] This step provides a specific procedure for decomposing the primary source sound field into a first-direction sound field and a second-direction sound field using matrix SVD.

[0057] S202, the first emission weight vector matrix and the second generation weight vector matrix are calculated based on the first directional sound field and the second directional sound field, respectively.

[0058] This step provides a specific procedure for calculating the first emission weight vector matrix and the second generation weight vector matrix based on the first directional sound field and the second directional sound field, respectively.

[0059] S203, the secondary source sound field is calculated based on the first emission weight vector matrix and the second generation weight vector matrix.

[0060] This step provides a specific procedure for calculating the secondary source sound field based on the first emission weight vector matrix and the second generation weight vector matrix.

[0061] This embodiment provides a specific implementation method for calculating the secondary source sound field based on the primary source sound field. The specific calculation method will be described in detail later and will not be repeated here.

[0062] In one embodiment, the first direction is the pitch direction, and the second direction is the horizontal direction.

[0063] This embodiment provides a specific implementation of the first direction and the second direction.

[0064] In one embodiment, the primary source sound field is a scattered sound field.

[0065] This embodiment provides a specific implementation of the primary source sound field. The scattered sound field...

[0066] The scattered sound field of the target (the primary source) can be obtained through theoretical calculation, numerical simulation, and experimental measurement. Regular targets can be obtained through theoretical calculation, while irregular targets can only be obtained through simulation or actual measurement. The scattered sound field matrix at a certain distance in the target's original field is obtained at a discretized full-space angle.

[0067] Figure 3 This is a schematic diagram of the scattering sound field model of a finite-length rigid cylinder in another embodiment of the present invention, as shown below. Figure 3As shown, in one embodiment, the scattered sound field is a rigid column with a limited length.

[0068] This embodiment provides a specific model of the scattered sound field.

[0069] In one embodiment, the primary source is the surface of a submarine.

[0070] This embodiment provides a specific application scenario for the primary source.

[0071] In one embodiment, the secondary source emission device is positioned on the surface of the submarine.

[0072] This embodiment provides a specific implementation of the secondary source emission device.

[0073] Figure 4 This is a schematic diagram showing the distribution of far-field scattered sound pressure in different directions in another embodiment of the present invention; Figure 5 This is a schematic diagram of the secondary source location distribution in another embodiment of the present invention; Figure 6 This is a schematic diagram of the circumferential distribution in another embodiment of the present invention; Figure 7 This is a schematic diagram of a linear distribution in another embodiment of the present invention; Figure 8 This is a schematic diagram of the feature value sequence number in another embodiment of the present invention;

[0074] Figure 9 This is a schematic diagram of the amplitude and phase of the sound pressure field of the maximum eigenvalue scattered sound field obtained by SVD decomposition with respect to theta in another embodiment of the present invention; Figure 10 This is a schematic diagram of the sound pressure amplitude and phase of the maximum eigenvalue scattered sound field obtained by SVD decomposition in another embodiment of the present invention with respect to phi; Figure 11 This is a schematic diagram of the scattered sound field corresponding to the maximum eigenvalue obtained by SVD decomposition in another embodiment of the present invention; Figure 12 This is a schematic diagram illustrating the difference between the original scattered sound field and the scattered sound field corresponding to the maximum eigenvalue obtained from SVD decomposition in another embodiment of the present invention. Figure 13 This is a schematic diagram comparing the emitted controlled sound field in the phi direction with the scattered sound field corresponding to the maximum eigenvalue obtained by SVD decomposition in another embodiment of the present invention. Figure 14 This is a schematic diagram comparing the sound pressure amplitude of the scattered sound field before and after active cancellation in the phi direction in another embodiment of the present invention; Figure 15 This is a schematic diagram comparing the emitted controlled sound field in the theta direction with the scattered sound field corresponding to the maximum eigenvalue obtained by SVD decomposition in another embodiment of the present invention. Figure 16 This is a schematic diagram comparing the sound pressure amplitude of the scattered sound field before and after active cancellation in the theta direction in another embodiment of the present invention; Figure 17This is a schematic diagram comparing the sound pressure amplitude of the scattered sound field before and after active cancellation in a three-dimensional spatial direction 10km away from the target center, according to another embodiment of the present invention. Figure 18 This is a schematic diagram comparing the sound pressure amplitude of the scattered sound field before and after active cancellation at different distances from the target center, with directions theta = 45°, phi = 180° and distances from the target center ranging from 5km to 100km. Figure 19 This is a schematic diagram comparing the sound pressure amplitude of the scattered sound field before and after active cancellation at different distances from the target center, with the direction theta = 45°, phi = 0° and a distance from the target center of 5km-100km. Figure 20 This is a schematic diagram comparing the sound pressure amplitude of the scattered sound field before and after active cancellation at different distances from the target center, with directions theta = 135°, phi = 180° and distances from the target center ranging from 5km to 100km. Figure 21 This is a schematic diagram comparing the sound pressure amplitude of the scattered sound field before and after active cancellation at different distances from the target center, with directions theta = 135°, phi = 0°, and distances from the target center ranging from 5km to 100km. Figure 22 This is a schematic diagram comparing the sound pressure amplitude of the scattered sound field before and after active cancellation at different distances from the target center, with directions theta = 45°, phi = 90° and distances from the target center ranging from 5km to 100km. Figure 23 This is a schematic diagram comparing the sound pressure amplitude of the scattered sound field before and after active cancellation at different distances from the target center, with directions theta = 60°, phi = 180°, and distances ranging from 5km to 100km. Based on the above embodiments, the specific calculation process is described in detail below. It should be noted that this is for better illustration of the invention and not for limiting its specific application.

[0075] First, taking a submarine as the research object, a finite-length rigid cylinder scattering sound field model is adopted based on the submarine's shape, as this type of model most closely resembles the actual shape of a submarine. A three-dimensional rectangular coordinate system is established with the center of the finite-length rigid cylinder as the origin O and the axis direction as the z-axis, as follows: Figure 3 As shown, there is a finite-length rigid cylinder with radius *a* and length *2L*. A point on the axis is at a distance *t* from its center *O*. Any receiving point in space is perpendicularly *r* from the axis, *d0* from the center *O* of the finite-length rigid cylinder, and *d* from a point on the axis. The point makes an angle θ with the z-axis, and its projection onto the xy-plane makes an angle θ with the x-axis. A plane sound wave is incident along the xz plane, with the wave vector making an angle with the z-axis. Assume that the two ends of the finite-length rigid cylinder satisfy simply supported boundary conditions, and neglect the sound scattering effect at the two ends of the finite-length rigid cylinder.

[0076] The sound field p at any point in the free field outside a finite-length rigid cylindere It can be written as:

[0077] p e =p i +p s

[0078] Where P i It is the incident sound field, P rig It is a scattered sound field, and the scattered sound field takes the following form as a solution:

[0079]

[0080] Based on experience, for infinite series, take the highest number of terms:

[0081] nmax≥ka+5

[0082] The accuracy of the calculation can be guaranteed by the above formula.

[0083] The simulation parameters are set as follows: sound speed is 1500 m / s, incident plane wave frequency is 300 Hz, and incident direction is:

[0084]

[0085] The cylinder has a radius of 5m and a length of 30m. Based on the theoretical model described above, the scattered sound field can be calculated.

[0086]

[0087] For a plane wave incident along the above incident direction, calculate the far-field scattered sound pressure P (at a distance of 10000m from the target center) for discrete spatial angles (theta = 1°, 3°..., 179°, phi = 1°, 3°..., 359°). P is a complex matrix of 180 rows and 90 columns. The distribution of the far-field scattered sound pressure P in different directions is as follows: Figure 4 As shown in the diagram. Based on the distribution of the scattered sound pressure in different directions in the far field, it can be seen that the direction of strongest scattering is...

[0088]

[0089] Secondary sources are distributed on the target, i.e., the primary sources, such as the surface of a submarine, with 180 equally spaced sources in the circumferential direction and 90 equally spaced sources in the longitudinal direction, such as... Figure 5 and Figure 6 ,as well as Figure 7 As shown.

[0090] SVD decomposition of the far-field scattered sound pressure P yields P = USV HWhere U is a 180x180 complex matrix, S is a 180x90 real matrix, and V is a 90x90 complex matrix, with only the first 90 values ​​on the diagonal of matrix S being non-zero, and eigenvalues ​​accounting for a significant portion of the matrix. Figure 8 As shown, the first eigenvalue accounts for 0.85, meaning the eigenvector corresponding to the first eigenvalue contributes 85%. Therefore, only the first eigenvalue s1 and its eigenvectors U1 and V1 are retained (as shown in Figures 1-5). Figure 9 and Figure 10 As shown in the figure, the scattered acoustic field corresponding to the largest eigenvalue obtained by SVD decomposition is denoted as like Figure 11 As shown. The difference between the scattered sound field corresponding to the largest eigenvalue obtained from SVD decomposition and the original scattered sound field is as follows. Figure 12 As shown, the difference is small, indicating that the scattered sound field corresponding to the largest eigenvalue obtained by SVD decomposition can be used as a simplified approximation of the original scattered sound field.

[0091] The emission weight vector C1 is solved using the eigenvector U1 on a circularly distributed two-dimensional array. Then, the contrast between the scattered sound field and the secondary sound field in the phi direction is calculated, such as... Figure 13 As shown, the sound field comparison before and after cancellation is calculated, as follows: Figure 14 As shown.

[0092] The emission weight vector C2 is solved using the eigenvector V1 on a linear array distributed along its length. Then, the contrast between the scattered sound field and the secondary sound field in the theta direction is calculated, such as... Figure 15 As shown, the sound field comparison before and after cancellation is calculated, as follows: Figure 16 As shown.

[0093] The three-dimensional secondary sound field is calculated based on the emission weight vector C1 of the circular array and the emission weight vector C2 of the linear array. The secondary sound field and the scattered sound field are superimposed in space to obtain the canceled three-dimensional sound field, which is then compared with the original three-dimensional scattered sound field. Figure 17 As shown, the sound pressure level of the sound field decreases by an order of magnitude after cancellation.

[0094] Finally, multiple directions were selected to calculate the control effect of the above-obtained emission weight vector at different distances, such as... Figures 18-23 As shown, the sound pressure level reduction is greatest at a distance of 10km, exceeding 10dB. The reduction is less than 10km as the distance decreases or increases. The sound pressure level reduction is smallest at 100km, not less than 3dB.

[0095] In one embodiment, the present invention also provides a sound field cancellation device, the device comprising:

[0096] The acquisition module is used to acquire the primary source sound field reflected from the primary source;

[0097] The calculation module is used to calculate the secondary source sound field based on the primary source sound field, wherein the secondary source sound field is the sound field emitted by a preset secondary source emitting device, so as to minimize the total sound field after the secondary source sound field cancels out the primary source sound field.

[0098] In one embodiment, the present invention also provides a sound field cancellation device, the device comprising: a processor and a memory;

[0099] The memory stores an application program that can be executed by the processor, which causes the processor to perform the steps of the sound field cancellation method as described above.

[0100] In one embodiment, the present invention also provides a computer-readable storage medium having a computer program stored thereon that, when executed by a processor, implements the steps of any of the sound field cancellation methods described herein.

Claims

1. A method for sound field cancellation, characterized in that, The sound field cancellation method: Obtain the primary source sound field reflected from the primary source; The secondary source sound field is calculated based on the primary source sound field, wherein the secondary source sound field is the sound field emitted by a preset secondary source emitting device, so as to minimize the total sound field after the secondary source sound field cancels out the primary source sound field; The calculation of the secondary source sound field based on the primary source sound field includes: The primary source sound field is decomposed into a first-direction sound field and a second-direction sound field using matrix SVD. The first emission weight vector matrix and the second generation weight vector matrix are calculated based on the first direction sound field and the second direction sound field, respectively. The secondary source sound field is calculated based on the first emission weight vector matrix and the second generation weight vector matrix.

2. The sound field cancellation method according to claim 1, characterized in that, The first direction is the pitch direction, and the second direction is the horizontal direction.

3. The sound field cancellation method according to claim 2, characterized in that, The primary source sound field is a scattered sound field.

4. The sound field cancellation method according to claim 3, characterized in that, The scattered sound field is a rigid column with a limited length.

5. The sound field cancellation method according to claim 4, characterized in that, The primary source is the surface of the submarine.

6. The sound field cancellation method according to claim 5, characterized in that, The secondary source emission device is deployed on the surface of the submarine.

7. A sound field cancellation device, characterized in that, The device includes: The acquisition module is used to acquire the primary source sound field reflected from the primary source; The calculation module is used to calculate the secondary source sound field based on the primary source sound field, wherein the secondary source sound field is the sound field emitted by a preset secondary source emitting device, so as to minimize the total sound field after the secondary source sound field cancels out the primary source sound field; The calculation of the secondary source sound field based on the primary source sound field includes: The primary source sound field is decomposed into a first-direction sound field and a second-direction sound field using matrix SVD. The first emission weight vector matrix and the second generation weight vector matrix are calculated based on the first directional sound field and the second directional sound field, respectively. The secondary source sound field is calculated based on the first emission weight vector matrix and the second generation weight vector matrix.

8. A sound field cancellation device, characterized in that, The device includes: a processor and a memory; The memory stores an application program that can be executed by the processor, which causes the processor to perform the steps of the sound field cancellation method as described in any one of claims 1 to 6.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that, When executed by a processor, the program implements the steps of the sound field cancellation method according to any one of claims 1 to 6.

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