Column barrier lower vector circular array element domain sound pressure and vibration velocity combined anti-interference beam forming method

Abstract

The invention belongs to the technical field of vector hydrophones, and particularly relates to a column barrier lower vector circular array element domain sound pressure and vibration velocity combined anti-interference beam forming method, which comprises the following steps of: constructing an element domain sound pressure steering vector, a radial vibration velocity steering vector and a tangential vibration velocity steering vector according to a cylindrical barrier lower vector circular array model; a spatial domain filtering preprocessing matrix is designed, and vector array output data preprocessing is achieved; and then a sound pressure vibration velocity cross covariance matrix is generated by using the filtered array element domain data of each channel, beam forming is performed in combination with the steering vector of each channel, passive detection of a target is realized, and simulation experiment verification shows that the result can improve the anti-interference capability of the vector circular array under the cylindrical baffle.

Description

Technical Field

[0001] This invention belongs to the field of vector hydrophone technology, specifically relating to a method for anti-interference beamforming by combining acoustic pressure and vibration velocity in the element domain of a vector circular array under a column barrier. Background Technology

[0002] Vector hydrophones can synchronously acquire sound pressure and particle velocity information at common points, and have a strong ability to suppress isotropic noise. Compared with traditional sound pressure hydrophones, their performance has been greatly improved. Vector hydrophones and related processing technologies are gradually becoming an important force in various passive sonar detection applications. Currently, vector hydrophones have been successfully used in various applications abroad. Given the many advantages of vector hydrophones, relevant domestic institutions have carried out related research on vector hydrophone development and vector signal processing methods. They have already developed the capability for vector hydrophone design, fabrication, and calibration, and have successfully applied them in fish finders, underwater acoustic communication, and other fields. Currently, they are dedicated to applying the detection advantages of vector hydrophones to sonar systems installed on ships and other carriers to comprehensively enhance the passive sonar detection capabilities.

[0003] Most sonar arrays installed on ships and other vessels are housed within the bulbous bow. To enhance the anti-interference capability of these arrays, cylindrical acoustic shields are typically fitted in practical engineering applications. However, the presence of these shields significantly deviates the operating environment of vector hydrophones from free-field conditions, altering the fundamental basis for their application. Therefore, research on vector signal processing techniques under shield conditions is crucial for improving the detection performance of vector hydrophones on ships and other vessels. Regarding the application of vector hydrophones under cylindrical shield conditions, domestic scholars have explored the characteristics of the vector acoustic field under cylindrical shields, analyzed the impact of shield conditions on the directivity of vector hydrophones, and proposed a modal domain vector array azimuth estimation method under cylindrical shield conditions. This addresses the fundamental issues in the application of vector hydrophones under cylindrical shield conditions. However, research on signal processing techniques for vector circular arrays under cylindrical shield conditions in complex environments is still lacking. Summary of the Invention

[0004] Since the actual working environment of sonar equipment is complex, strong interference can greatly affect the detection performance of sonar arrays. In order to improve the anti-interference performance of vector arrays when used under cylindrical baffle conditions, this invention proposes a method for anti-interference beamforming that combines acoustic pressure and vibration velocity in the element domain of a vector circular array under cylindrical baffle conditions.

[0005] The specific technical solution of this invention is as follows:

[0006] A method for anti-interference beamforming using a vector circular array element domain combined with acoustic pressure and vibration velocity under a cylindrical barrier, wherein a uniform circular array is installed on the central surface of the cylindrical barrier, the cylinder radius is a, the number of elements in the vector circular array is M, the distance between the hydrophone and the barrier is h, and the target azimuth angle is [missing information]. The specific steps are as follows;

[0007] S1. Establish the vector sound field model under the cylindrical baffle. The expression for the sound pressure field under the cylindrical baffle is:

[0008]

[0009] When the baffle is an absolutely rigid baffle When the baffle is an absolutely soft baffle, Where j is the imaginary unit, n is the modal order, and k is the sound wave number. The angle between the line connecting the receiving point and the origin and the x-axis, and the maximum modal order. , This represents the integer operation. , It is an nth-order Bessel function. It is the nth order Hankel function of the first kind. It is the first differential of the nth-order Bessel function. It is the first differential of the nth-order Hankel function of the first kind;

[0010] The expression for the velocity field of the mass under the cylindrical baffle is:

[0011]

[0012]

[0013] The vibration velocity of the aforementioned particles has been determined by parameters. Normalization Let be the wave impedance in water, and when the baffle is an absolutely rigid baffle. When the baffle is an absolutely soft baffle, ;

[0014] S2. Construct the sound pressure guidance vector, radial velocity guidance vector, and tangential velocity guidance vector in the array element domain, respectively.

[0015] S3. Design a spatial matrix filter based on the optimal design criteria;

[0016] S4. Use the spatial filtering matrix H to preprocess the vector circular array element domain data and output the filtered element domain data of each channel.

[0017] S5. Generate a cross-covariance matrix using the acoustic pressure array element-domain signal and the tangential vibration velocity array element-domain signal. A cross-covariance matrix is ​​generated using the acoustic pressure array element-domain signal and the radial velocity array element-domain signal. ;

[0018] S6. Combine the steering vectors and cross-covariance matrices of each channel. and cross-covariance matrix Calculate the beam output energy.

[0019] Furthermore, in step S2, the method for constructing the array element domain sound pressure steering vector, radial velocity steering vector, and tangential velocity steering vector is as follows:

[0020] Element domain acoustic pressure steering vector:

[0021]

[0022] Array element domain particle velocity steering vector:

[0023]

[0024]

[0025] The angle between the line connecting the m-th element to the origin and the x-axis is... , This is the beam steering angle.

[0026] Furthermore, in step S3, the method for designing the spatial matrix filter according to the optimal design criterion is as follows:

[0027] Assume the array manifold matrix formed by the guide vectors in the passband region is as follows: Then there is

[0028]

[0029] The array manifold matrix formed by the guide vectors in the stopband region is: Then there is

[0030]

[0031] and Let P and S be the sets of incident azimuth angles in the passband and stopband regions, respectively, and let P and S be the number of guide vectors after discretization in the passband and stopband regions, respectively. We select the minimum mean square criterion spatial matrix filter as the preprocessing filter, and let...

[0032]

[0033]

[0034] The expression for the spatial domain filtering matrix is:

[0035]

[0036] superscript H This represents performing the conjugate transpose operation on a matrix. -1 This represents the operation of inverting a matrix.

[0037] Furthermore, in step S4, the method for preprocessing the vector circular array element domain data using the spatial domain filtering matrix H is as follows:

[0038]

[0039] Where t represents time. This is the original element-domain time-domain data of a vector circular array. To preprocess the array element time-domain data, Time-domain data are received via the sound pressure channel, radial velocity channel, and tangential velocity channel, respectively. These are the preprocessed time-domain data for the sound pressure channel, radial velocity channel, and tangential velocity channel, respectively. T This represents the transpose operation on the matrix.

[0040] Furthermore, in step S5, a cross-covariance matrix is ​​generated. And generate cross-covariance matrix The method is as follows:

[0041]

[0042] .

[0043] Furthermore, in step S6, the method for calculating the beam output energy is as follows:

[0044] .

[0045] In summary, compared with the prior art, the above-described technical solutions conceived by this invention can achieve the following beneficial effects:

[0046] Based on the vector circular array model under a cylindrical baffle, this invention constructs the sound pressure steering vector, radial velocity steering vector, and tangential velocity steering vector in the array element domain. A spatial filtering preprocessing matrix is ​​then designed to preprocess the output data of the vector array. The filtered array element domain data is then used to generate a sound pressure-velocity cross-covariance matrix, which, combined with the steering vectors of each channel, performs beamforming to achieve passive target detection. Simulation experiments verify that this achievement can improve the anti-interference capability of the vector circular array under a cylindrical baffle. Attached Figure Description

[0047] Figure 1 This is a vector circular array model diagram on the cylindrical baffle of the present invention;

[0048] Figure 2 This is a flowchart of the present invention;

[0049] Figure 3 This is a simulation example of the passive target detection results using a vector circular array under a cylindrical barrier in this invention. Figure 3Figure (a) shows a comparison of spatial spectrum estimation results before spatial filtering preprocessing: independent processing of sound pressure velocity in the element domains of the sound pressure array and the vector array, and joint processing of sound pressure velocity in the element domain of the vector array. Figure 3 (b) in the figure shows the comparison results of spatial spectrum estimation of the vector array element domain sound pressure and vibration velocity joint processing before and after spatial filtering preprocessing. Detailed Implementation

[0050] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. Based on the embodiments, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this invention.

[0051] Combined with appendix Figure 1-2 As shown, a method for anti-interference beamforming using a vector circular array element domain combined with acoustic pressure and vibration velocity under a cylindrical barrier is described. A uniform circular array is installed on the central surface of the cylindrical barrier. The radius of the cylinder is *a*, the number of elements in the vector circular array is *M*, the distance between the hydrophone and the barrier is *h*, and the target azimuth angle is... The specific steps are as follows;

[0052] S1. Establish the vector sound field model under the cylindrical baffle. The expression for the sound pressure field under the cylindrical baffle is:

[0053]

[0054] When the baffle is an absolutely rigid baffle When the baffle is an absolutely soft baffle, Where j is the imaginary unit, n is the modal order, and k is the sound wave number. The angle between the line connecting the receiving point and the origin and the x-axis, and the maximum modal order. , This represents the integer operation. , It is an nth-order Bessel function. It is the nth order Hankel function of the first kind. It is the first differential of the nth-order Bessel function. It is the first differential of the nth-order Hankel function of the first kind;

[0055] The expression for the velocity field of the mass under the cylindrical baffle is:

[0056]

[0057]

[0058] The vibration velocity of the aforementioned particles has been determined by parameters. Normalization Let be the wave impedance in water, and when the baffle is an absolutely rigid baffle. When the baffle is an absolutely soft baffle, ;

[0059] S2. Construct the sound pressure guidance vector, radial velocity guidance vector, and tangential velocity guidance vector in the array element domain, respectively.

[0060] S3. Design a spatial matrix filter based on the optimal design criteria;

[0061] S4. Use the spatial filtering matrix H to preprocess the vector circular array element domain data and output the filtered element domain data of each channel.

[0062] S5. Generate a cross-covariance matrix using the acoustic pressure array element-domain signal and the tangential vibration velocity array element-domain signal. A cross-covariance matrix is ​​generated using the acoustic pressure array element-domain signal and the radial velocity array element-domain signal. ;

[0063] S6. Combine the steering vectors and cross-covariance matrices of each channel. and cross-covariance matrix Calculate the beam output energy.

[0064] Specifically, in step S2, the method for constructing the array element domain sound pressure steering vector, radial velocity steering vector, and tangential velocity steering vector is as follows:

[0065] Element domain acoustic pressure steering vector:

[0066]

[0067] Array element domain particle velocity steering vector:

[0068]

[0069]

[0070] The angle between the line connecting the m-th element to the origin and the x-axis is... , This is the beam steering angle.

[0071] Specifically, in step S3, the method for designing the spatial matrix filter according to the optimal design criterion is as follows:

[0072] Assume the array manifold matrix formed by the guide vectors in the passband region is as follows: Then there is

[0073]

[0074] The array manifold matrix formed by the guide vectors in the stopband region is: Then there is

[0075]

[0076] and Let P and S be the sets of incident azimuth angles in the passband and stopband regions, respectively, and let P and S be the number of guide vectors after discretization in the passband and stopband regions, respectively. We select the minimum mean square criterion spatial matrix filter as the preprocessing filter, and let...

[0077]

[0078]

[0079] The expression for the spatial domain filtering matrix is:

[0080] .

[0081] superscript H This represents performing the conjugate transpose operation on a matrix. -1 This represents the operation of inverting a matrix.

[0082] Specifically, in step S4, the method for preprocessing the vector circular array element domain data using the spatial domain filtering matrix H is as follows:

[0083]

[0084] Where t represents time. This is the original element-domain time-domain data of a vector circular array. To preprocess the array element time-domain data, Time-domain data are received via the sound pressure channel, radial velocity channel, and tangential velocity channel, respectively. These are the preprocessed time-domain data for the sound pressure channel, radial velocity channel, and tangential velocity channel, respectively. T This represents the transpose operation on the matrix.

[0085] Specifically, in step S5, a cross-covariance matrix is ​​generated. And generate cross-covariance matrix The method is as follows:

[0086]

[0087] .

[0088] Specifically, in step S6, the method for calculating the beam output energy is as follows:

[0089] .

[0090] The following simulation example will illustrate the invention in more detail:

[0091] Consider a vector circular array with 15 elements (M), a cylindrical baffle radius (a) of 0.5m, and a distance (h) between the uniform vector circular array and the baffle of 0.2m; the signal frequency is 1000Hz, the incident angle is 200°, the interference frequency is 1000Hz, the incident angle is 30°, the signal-to-noise ratio (SNR) is 0dB, and the signal-to-interference ratio (SINR) is 0dB. Using the minimum mean square criterion as the design criterion for the spatial matrix filter, the passband angle range is set to [50°, 250°], and the stopband angle range is... .

[0092] As attached Figure 3 This refers to the target detection results of a vector circular array when the cylindrical barrier is an absolutely soft barrier. Figure 3 (a) shows the comparison results of spatial spectrum estimation before spatial filtering preprocessing: independent processing of sound pressure velocity in the element domain of the sound pressure array and the element domain of the vector array, and joint processing of sound pressure velocity in the element domain of the vector array. Figure 3 (b) shows the comparison of spatial spectrum estimation results before and after joint processing of vector array element domain acoustic pressure and vibration velocity before and after spatial filtering preprocessing. Figure 3 As can be seen in (a) above, when the cylindrical baffle is an absolutely soft baffle, the background noise level of the vector array spatial spectrum is significantly lower than that of the sound pressure array spatial spectrum, and the proposed joint processing of sound pressure and vibration velocity in the vector circular array element domain can achieve better background noise suppression capability. From Figure 3 As can be seen from (b), after preprocessing with spatial matrix filtering, the interference is filtered out, further improving the anti-interference capability of the joint processing method of sound pressure and vibration velocity in the element domain of the vector circular array under the cylindrical barrier. In summary, the joint anti-interference beamforming method of sound pressure and vibration velocity in the element domain of the vector circular array under the cylindrical barrier has good anti-interference capability against strong interference and noise interference.

[0093] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications and substitutions based on the technical solutions and inventive concepts provided by the present invention should be covered within the scope of protection of the present invention.

Claims

1. A method for anti-interference beamforming using a combination of acoustic pressure and vibration velocity in the element domain of a vector circular array under a column barrier, characterized in that: A uniform circular array is installed on the central surface of a cylindrical baffle. The cylinder has a radius of 'a', the number of array elements is 'M', the hydrophone is 'h' away from the baffle, and the target azimuth is ''. The specific steps are as follows; S1. Establish the vector sound field model under the cylindrical baffle. The expression for the sound pressure field under the cylindrical baffle is: When the baffle is an absolutely rigid baffle When the baffle is an absolutely soft baffle, Where j is the imaginary unit, n is the modal order, and k is the sound wave number. The angle between the line connecting the receiving point and the origin and the x-axis, and the maximum modal order. , This represents the integer operation. , It is an nth-order Bessel function. It is the nth order Hankel function of the first kind. It is the first differential of the nth-order Bessel function. It is the first differential of the nth-order Hankel function of the first kind; The expression for the velocity field of the mass under the cylindrical baffle is: The vibration velocity of the aforementioned particles has been determined by parameters. Normalization Let be the wave impedance in water, and when the baffle is an absolutely rigid baffle. When the baffle is an absolutely soft baffle, ; S2. Construct the sound pressure guidance vector, radial velocity guidance vector, and tangential velocity guidance vector in the array element domain, respectively. S3. Design a spatial matrix filter based on the optimal design criteria; S4. Use the spatial filtering matrix H to preprocess the vector circular array element domain data and output the filtered element domain data of each channel. S5. Generate a cross-covariance matrix using the acoustic pressure array element-domain signal and the tangential vibration velocity array element-domain signal. A cross-covariance matrix is ​​generated using the acoustic pressure array element-domain signal and the radial velocity array element-domain signal. ; S6. Combine the steering vectors and cross-covariance matrices of each channel. and cross-covariance matrix Calculate the beam output energy.

2. The method for combined anti-interference beamforming of vector circular array element domain acoustic pressure and vibration velocity under column barrier as described in claim 1, characterized in that: In step S2, the method for constructing the array element domain acoustic pressure steering vector, radial velocity steering vector, and tangential velocity steering vector is as follows: Element domain acoustic pressure steering vector: Array element domain particle velocity steering vector: The angle between the line connecting the m-th element to the origin and the x-axis is... , This is the beam steering angle.

3. The method for combined anti-interference beamforming of vector circular array element domain acoustic pressure and vibration velocity under column barrier as described in claim 2, characterized in that: In step S3, the method for designing the spatial matrix filter according to the optimal design criterion is as follows: Assume the array manifold matrix formed by the guide vectors in the passband region is as follows: Then there is The array manifold matrix formed by the guide vectors in the stopband region is: Then there is and Let P and S be the sets of incident azimuth angles in the passband and stopband regions, respectively, and let P and S be the number of guide vectors after discretization in the passband and stopband regions, respectively. We select the minimum mean square criterion spatial matrix filter as the preprocessing filter, and let... The expression for the spatial filtering matrix is: superscript H This represents performing the conjugate transpose operation on a matrix. -1 This represents the operation of inverting a matrix.

4. The method for combined anti-interference beamforming of vector circular array element domain acoustic pressure and vibration velocity under column barrier as described in claim 3, characterized in that: In step S4, the method for preprocessing the vector circular array element domain data using the spatial domain filtering matrix H is as follows: Where t represents time. This is the original element-domain time-domain data of a vector circular array. To preprocess the array element time-domain data, Time-domain data are received via the sound pressure channel, radial velocity channel, and tangential velocity channel, respectively. These are the preprocessed time-domain data for the sound pressure channel, radial velocity channel, and tangential velocity channel, respectively. T This represents the transpose operation on the matrix.

5. The method for combined anti-interference beamforming of vector circular array element domain acoustic pressure and vibration velocity under column barrier as described in claim 4, characterized in that: In step S5, the cross-covariance matrix is ​​generated. And generate the cross-covariance matrix The method is as follows: 。 6. The method for combined anti-interference beamforming of vector circular array element domain acoustic pressure and vibration velocity under column barrier as described in claim 5, characterized in that: In step S6, the method for calculating the beam output energy is as follows: 。

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