A sparse array measurement system, method, program, and storage medium for measuring radiated noise from underwater targets.

Abstract

This invention belongs to the field of underwater target radiated noise measurement technology, specifically relating to a sparse combined array measurement system, method, program, and storage medium for underwater target radiated noise measurement. The invention designs a sparse combined array formed by a sparsely structured acoustic pressure spiral biconical volume array and an acoustic pressure vector nested vertical linear array. It employs a frequency-band testing scheme combining a high-frequency volume array and a low-frequency vertical linear array, utilizing a combined measurement method of acoustic pressure hydrophones and vector hydrophones to extend the measurement frequency band and achieve effective measurement of underwater target radiated noise across the entire frequency band. Through a sparse array structure and an improved constant-beam wide beamforming method, a robust two-dimensional constant-beam wide beam is obtained while reducing the number of array elements and array complexity. Furthermore, the main lobe width and low sidelobe level can be adjusted according to the measured target and measurement distance. This invention reduces the redundancy of the measurement array elements and can be flexibly applied to various application scenarios for underwater radiated noise measurement.

Description

Technical Field

[0001] This invention belongs to the field of underwater target radiated noise measurement technology, specifically relating to a sparse combined array measurement system, method, program, and storage medium for underwater target radiated noise measurement. Background Technology

[0002] With the development of vibration reduction and noise reduction technologies, the radiated noise level of underwater targets has gradually decreased. Accurately evaluating the radiated noise level of underwater targets has become a challenging problem. Underwater target radiated noise measurement systems have evolved from traditional single-barrel and multi-barrel hydrophone systems to linear array and volumetric array systems. Currently, commonly used single-barrel hydrophone systems are simple to configure but are severely susceptible to multipath interference, failing to meet the signal-to-noise ratio requirements for measuring the radiated noise of low-noise targets. Using multiple barrel hydrophones to form a vertical linear array may reduce the impact of sea surface noise and channel multipath interference, but vertical linear arrays lack horizontal directivity, resulting in lower measurement gain. Furthermore, low-frequency testing requires a large array aperture, which is limited by water depth, making deployment difficult and array configuration hard to control. Using a volumetric array system for radiated noise measurement can simultaneously obtain the directivity in the horizontal and vertical directions. Compared with the commonly used cylindrical volumetric array, the spiral biconical volumetric array has a wider horizontal main lobe width and a narrower vertical main lobe width, which can ensure that the target radiating surface is within the main lobe of the beam while suppressing the interference of interface reflections and has a higher measurement gain. However, it has the problems of difficult deployment and implementation due to the large number of array elements and the large volume of the low-frequency array base.

[0003] The successful development and engineering application of highly reliable and sensitive vector hydrophones in recent years have provided new solutions to the problem of low-frequency radiated noise measurement. Vector hydrophones can achieve unilateral directivity, gaining both horizontal and vertical spatial processing capabilities; furthermore, they can obtain additional coherent signal processing gain through combined sound pressure and vibration velocity processing techniques. Therefore, vector hydrophone arrays can maintain high measurement gain while maintaining a relatively small array aperture. However, as the number of array elements increases, the system complexity increases significantly, and the system robustness decreases sharply, which is detrimental to the accurate and reliable measurement of underwater target radiated noise. Furthermore, since underwater target radiated noise is a broadband signal, the main lobe width of conventional beamforming varies with frequency. A main lobe width that is too wide or too narrow will affect the accuracy of underwater target radiated noise measurement. Therefore, in broadband array signal processing, constant beamwidth beamforming methods are often used to obtain a constant-width main lobe, ensuring that the spectral characteristics of the array system's receiver response remain unchanged, thus stably obtaining a high broadband measurement gain. Summary of the Invention

[0004] The purpose of this invention is to provide a sparse array measurement system, method, program, and storage medium for measuring radiated noise of underwater targets.

[0005] A sparse array includes a sound pressure spiral biconical volume array and a sound pressure vector nested vertical linear array. The sound pressure spiral biconical volume array is obtained by rotating a cylindrical array with a fixed bottom ring and a top ring around the cylindrical axis by a certain angle. The cylindrical array includes multiple sets of single sparse linear arrays with the same number of array elements uniformly arranged on the circumference. The single sparse linear arrays adopt a cross-octave sparse nested array, and the sound pressure vector nested vertical linear array adopts a 2-octave sparse nested array. The sound pressure vector nested vertical linear array passes through the center of the sound pressure spiral biconical volume array, and the central array element of the sound pressure vector nested vertical linear array is located at the center of the circular cross-section with the smallest radius of the sound pressure spiral biconical volume array. The central array element of the sound pressure spiral biconical volume array and the central array element of the sound pressure vector nested vertical linear array are on the same plane.

[0006] Furthermore, the sound pressure spiral biconical volume array comprises M1 array elements of N1 single sparse linear arrays; the single sparse linear array comprises M2 array elements of N Tl It is composed of concentric nested uniform sound pressure subarrays, with element spacing of d1, 3d1, 9d1, ... in each uniform sound pressure subarray. 2≤M2≤4;

[0007] The sound pressure vector nested vertical linear array consists of M3 array elements and N elements. L It is composed of concentric nested uniform subarrays, with element spacing of d2, 4d2, 16d2, ... in each uniform subarray. Some of the uniform subarrays are sound pressure vector combination arrays, and the number of vector array elements in the sound pressure vector combination array is M. v ;2≤M3≤4.

[0008] An underwater target radiated noise measurement system with a sparse array includes a wet-end test platform and a dry-end data processing device, which are connected by a signal transmission optoelectronic composite cable. The wet-end test platform includes a sparse array, an underwater navigation and positioning array, a depth sensor, an electronic instrument compartment, a voltage stabilizing instrument compartment, and a float-swivel-weight mooring system. The float-swivel-weight mooring system includes a main float, a secondary float, a mechanical swivel, an optoelectronic slip ring, a release device, and an anchor block.

[0009] The acoustic pressure spiral biconical volume array is installed in the array frame. The upper end of the array frame is connected to the first intermediate transfer mooring member via a cable, and the lower end of the array frame is connected to the second intermediate transfer mooring member via a cable. The underwater navigation and positioning base array is installed on the top of the array frame, and the electronic instrument cabin is installed at the bottom of the array frame. The electronic instrument cabin is equipped with an attitude sensor, a signal conditioning module, and a data acquisition and control module. The first intermediate transfer mooring member is connected to the upper end of the acoustic pressure spiral biconical volume array, and the second intermediate transfer mooring member is connected to the lower end of the acoustic pressure spiral biconical volume array. The first intermediate transfer mooring member and the second intermediate transfer mooring member are equipped with a depth sensor and an attitude sensor. The first intermediate transfer mooring member and the second intermediate transfer mooring member respectively transmit upward and downward tension, so that the acoustic pressure spiral biconical volume array is vertically arranged and its central array element is on the same plane as the central array element of the nested vertical linear array of acoustic pressure vectors.

[0010] The upper end of the nested vertical linear array of sound pressure vectors is connected to a mechanical rotating ring via a cable, and the mechanical rotating ring is connected to the main float via a cable. The lower end of the nested vertical linear array of sound pressure vectors is connected to a photoelectric slip ring via a multi-core load-bearing electrical connector. The photoelectric slip ring, the pressure stabilizing instrument compartment, the release device, the secondary float, and the weight are connected in series via cables. A pressure stabilizing device is installed inside the pressure stabilizing instrument compartment. The mechanical rotating ring and the photoelectric slip ring are used to reduce the rotational torque of the sparse array and reduce the rotation of the cable with the sparse array.

[0011] A measurement method based on an underwater target radiated noise measurement system includes the following steps:

[0012] Step 1: Deploy the underwater target radiated noise measurement system in the measurement water area, receive the radiated noise signal of the target being measured, and transform the received radiated noise signal of the target being measured into the frequency domain;

[0013] Step 2: For the acoustic pressure spiral biconical volume array, an improved nested array constant-beamwidth beamforming method is adopted. A convex optimization algorithm is used to perform constant-beamwidth beamforming on the entire acoustic pressure spiral biconical volume array, obtaining an ultra-wideband two-dimensional robust constant-beamwidth beam. This allows for the acquisition of the beamforming result B of the mid- and high-frequency broadband radiated noise of the target under test. TBCA (f);

[0014] Step 3: For the nested vertical linear array of sound pressure vectors, an improved nested array constant beamwidth beamforming method is adopted, combined with a vector signal sound pressure and vibration velocity joint processing method. The sound pressure channel and vibration velocity channel of the nested vertical linear array of sound pressure vectors are respectively subjected to ultra-wideband constant beamwidth beamforming using a convex optimization algorithm to obtain a two-dimensional robust constant beamwidth, thereby obtaining the beamforming result B of the low-frequency broadband radiated noise of the target under test. ULA (f);

[0015] Step 4: After combining the beamforming results of the sound pressure helical biconical volume array and the sound pressure vector nested vertical linear array into B(f), perform spectral analysis on B(f) to obtain the power spectral density Q(f). Based on Q(f), calculate the 1 / 3 octave band sound pressure source level L of the target under test. pso (i) and broadband sound source level L p This enables effective measurement of the full-band radiated noise of the target under test;

[0016]

[0017] Where K is the number of snapshots in the time domain signal; f s The signal sampling frequency is represented by |·|; | represents the magnitude; i is the 1 / 3 octave band number; f i is the center frequency of the i-th 1 / 3 octave band; D is the distance from the reference origin to the equivalent sound center of the target being measured; I is the number of 1 / 3 octave bands included in the wideband.

[0018] Furthermore, the broadband radiated noise signal s(t) of the target being measured in step 1, represented in the frequency domain as S(f), is determined by the direction of the incoming wave. Incident on a sparse array, the elevation angle θ represents the angle between the incident direction of the sound wave and the z-axis, and the azimuth angle... Let X(f) represent the angle between the incident sound wave projected onto the horizontal plane and the x-axis. The array-received signal model X(f) is expressed as:

[0019]

[0020] in, The guide vector for the sparse composite array. f is the frequency of the broadband radiated noise signal of the target under test, and τ is the time delay of the received signal of the array element in the sparse array relative to the reference origin. c represents the propagation speed of underwater sound waves, r represents the spatial coordinates of the array elements in the sparse array, and u represents the unit direction vector of the incident sound wave.

[0021] Further, step 2 specifically involves: establishing a sound pressure spiral biconical volume array model composed of N1×M1 isotropic array elements, and determining the position coordinates of the (n1, m1)th array element in three-dimensional space. for:

[0022]

[0023] Where n1 = 1, 2, K, N1; m1 = 1, 2, ..., M1; These are the x-axis, y-axis, and z-axis coordinates of the (n1, m1)th array element, respectively. Let be the elevation angle of the (n1, m1)th array element relative to the origin; Let be the azimuth angle of the (n1, m1)th array element relative to the origin; The geometric distance between the (n,m)th element and the reference origin is expressed in the following form:

[0024]

[0025] The time delay of the received signal of the (n1, m1)th array element relative to the reference origin Represented as:

[0026]

[0027] The guiding vector of the sound pressure spiral biconical volume array for:

[0028]

[0029] The frequency domain output X of the array TBCA (f) is represented as:

[0030]

[0031] Where, N TBCA (f) represents the additive noise matrix received by each element of the acoustic pressure spiral biconical volume array; for the broadband radiated noise signal received by the acoustic pressure spiral biconical volume array, it is divided into L... TBCA The analysis is performed on the l frequency sub-band. TBCA The result of beamforming in each frequency sub-band B TBCA,lTBCA (f) is represented as:

[0032] B TBCA,lTBCA (f)=w TBCA (f lTBCA ) H X TBCA (f), f∈F lTBCA

[0033] Among them, w TBCA (f lTBCA ) indicates the lth TBCA The sound pressure spiral biconical volume matrix weighted vector for each frequency subband; f lTBCA The center frequency of this subband; the superscript H indicates the conjugate transpose; F lTBCA For the l TBCA Each frequency sub-band range;

[0034] The l-th sound pressure spiral biconical volume matrix is ​​solved using a convex optimization algorithm. TBCA The weighted vector w of each frequency sub-band TBCA (f lTBCA To achieve constant beamwidth beamforming, the expression is:

[0035]

[0036] Where Θ represents the range of the pitch angle θ, taking the value [0, π]; Ψ represents the azimuth angle. The range is [0, 2π]; B d (Θ MI ,Ψ MJ ) represents the desired main lobe amplitude of the beam; Θ MI Θ represents the range of elevation angles corresponding to the desired main lobe of the beam. SI Ψ represents the range of elevation angles corresponding to the desired beam sidelobes. MJ Ψ represents the azimuth range corresponding to the desired main lobe of the beam. SJ The desired beam sidelobe corresponds to the azimuth range, while the desired beam main lobe can be adjusted according to the actual target size and test distance; δ s As an upper bound constraint for the azimuth beam sidelobes, η s ζ0 is the upper bound constraint for the pitch angle beam sidelobe, and ζ0 is the upper bound constraint for the weighted vector 2-norm.

[0037] Further, step 3 specifically involves: the number of vector array elements in the nested vertical linear array of sound pressure vectors being N. v The number of sound pressure array elements is N p Sound pressure vector nested in a vertical linear array, sound pressure channel steering vector A p (f,θ) and vibration channel guide vector They are respectively:

[0038]

[0039]

[0040] in, The guiding vector for the acoustic pressure array elements; is the sound pressure channel guide vector of the vector array element; r0 is the distance from the reference origin to the sound center of the target being measured; For the number n p The acoustic pressure array element steering vector, n is the distance from the sound pressure element to the sound center of the target being measured. p =1,2,KN p ; For the number n v The sound pressure channel steering vector of the vector array element. n is the distance from the vector array element to the acoustic center of the target being measured. v =1,2,KN v ; The direction of arrival; the frequency domain output X of the sound pressure channel of all sound pressure elements and vector elements in the nested vertical linear array of sound pressure vectors. ULA,p (f) is represented as:

[0041] X ULA,p (f)=A p (f,θ)S(f)+N ULA,p (f)

[0042] Where, N ULA,p (f) is the additive noise matrix received by all sound pressure channels in the nested vertical linear array of sound pressure vectors;

[0043] Frequency domain output of the combined vibration velocity of the vector array elements in a nested vertical linear array of sound pressure vectors Represented as:

[0044]

[0045] Where, N ULA,v (f) is the additive noise matrix received by all vector array elements in the nested vertical linear array of sound pressure vectors;

[0046] For the broadband radiated noise signal received by the sound pressure vector nested vertical linear array, it is divided into L ULA The analysis is performed on the l frequency sub-band. ULA The result of beamforming in each frequency sub-band Represented as:

[0047]

[0048] in, The center frequency is The l ULA The sound pressure vector of each frequency sub-band is nested with the weighted vector of the vertical linear array sound pressure channels; The center frequency is The l ULA The sound pressure vector of each frequency sub-band is nested with the weighted vector of the vertical linear array vibration velocity channel; For the l ULA Each frequency sub-band range;

[0049] The l-th nested vertical linear array of sound pressure vectors is solved using a convex optimization algorithm. ULA The sound pressure channel weighted vector of each frequency sub-band and combined vibration velocity channel weighted vector To achieve constant-beam wide-beamforming, the expression is:

[0050]

[0051]

[0052] Among them, B d,p (Θ MI ) represents the desired main lobe amplitude of the beam at the pitch angle; ΘMI Θ represents the range of elevation angles corresponding to the desired main lobe of the beam. SI The desired beam sidelobe pitch angle range is defined as the range of pitch angles corresponding to the desired beam main lobe. The pitch angle range of the desired beam main lobe can be adjusted according to the actual vertical dimensions of the target being measured and the test distance. Ψ represents the desired main lobe amplitude of the azimuth angle. MJ Ψ represents the azimuth range corresponding to the desired main lobe of the beam. SJ The desired azimuth range corresponds to the sidelobes of the beam; the desired main lobe azimuth range can be adjusted according to the actual horizontal scale of the target and the test distance. δ s As an upper bound constraint for the azimuth beam sidelobes, η s ζ0 is the upper bound constraint for the pitch angle beam sidelobe, and ζ0 is the upper bound constraint for the weighted vector 2-norm.

[0053] A computer device / equipment / system includes a memory, a processor, and a computer program stored in the memory, wherein the processor executes the computer program to implement the steps of the above-described underwater target radiated noise measurement method.

[0054] A computer-readable storage medium having a computer program / instructions stored thereon, which, when executed by a processor, implements the steps of the above-described underwater target radiated noise measurement method.

[0055] A computer program product includes a computer program / instructions that, when executed by a processor, implement the steps of the above-described underwater target radiated noise measurement method.

[0056] The beneficial effects of this invention are as follows:

[0057] This invention addresses the problem of measuring radiated noise from low-noise underwater targets. It designs a sparse combination array formed by a sparsely structured acoustic pressure spiral biconical volume array and a nested acoustic pressure vector vertical linear array. By employing a frequency-band testing scheme combining a high-frequency volume array and a low-frequency vertical linear array, and utilizing a combined measurement method combining acoustic pressure hydrophones and vector hydrophones, the measurement frequency band is extended, enabling effective measurement of the full-band radiated noise of underwater targets. Through a sparse array structure and an improved constant-beam wide beamforming method, a robust two-dimensional constant-beam wide beam is obtained while reducing the number of array elements and array complexity. Furthermore, the main lobe width and low side lobe level can be adjusted according to the target and measurement distance. In the mid-to-high frequency band, for acoustic pressure spiral biconical volume arrays, an improved nested array constant-beamwidth beamforming method is used to achieve robust two-dimensional constant-beamwidth beamforming. In the low frequency band, for acoustic pressure vector nested vertical linear arrays, an improved nested array constant-beamwidth beamforming method is combined with a vector signal acoustic pressure velocity joint processing method and a near-field focusing method to obtain unilateral directivity, improve array gain, effectively extend the lower limit frequency of measurement, and improve measurement accuracy. This invention reduces the redundancy of the measurement array elements, solves the problems of limited working bandwidth and robust two-dimensional constant-beamwidth beamforming in noise measurement, and achieves accurate measurement of broadband radiated noise of underwater targets. In addition, the beam directivity of the measurement system can be adjusted through signal processing methods, making it more flexible and applicable to various application scenarios of underwater radiated noise measurement. Attached Figure Description

[0058] Figure 1 This is a schematic diagram of the deployment of an underwater target radiation noise measurement system with a sparse array.

[0059] Figure 2(a) is a diagram showing the element positions of a nested vertical linear array of sound pressure vectors.

[0060] Figure 2(b) is a three-dimensional view of the element positions of the acoustic pressure spiral biconical volume array.

[0061] Figure 3(a) shows the results of the vertical constant beamwidth beamforming of a nested vertical linear array with sound pressure vectors from 10 Hz to 1 kHz.

[0062] Figure 3(b) shows the vertical constant beamwidth beamforming result of the 1kHz to 50kHz acoustic pressure spiral biconical volume array.

[0063] Figure 3(c) shows the horizontal constant beamwidth beamforming result of a nested vertical linear array with sound pressure vectors from 10 Hz to 1 kHz.

[0064] Figure 3(d) shows the horizontal constant beamwidth beamforming result of the 1kHz~50kHz acoustic pressure spiral biconical volume array.

[0065] Figure 4 This is a graph showing the relationship between the gain of a sparse array and the measurement frequency band.

[0066] Figure 5 This is a summary table of the constant-beamwidth beamforming performance of sparse combined arrays. Detailed Implementation

[0067] The present invention will now be further described with reference to the accompanying drawings.

[0068] This invention addresses the problem of broadband radiated noise measurement for low-noise underwater targets, proposing a sparse combined array measurement system, method, program, and storage medium for underwater target radiated noise measurement. The sparse combined array measurement system employs a frequency-band testing scheme: In the mid-to-high frequency band, a sound pressure spiral biconical volume array is used. The sparse array element arrangement of the volume array and single linear array solves the problems of array element redundancy and high-frequency array difficulty. Combined with a constant-beam wide beamforming method, broadband robust constant-beam wide beamforming is performed on both the horizontal and vertical beams, extending the upper limit of the measurement frequency and achieving broadband radiated noise measurement in the mid-to-high frequency band. In the low-frequency band, a sparse structure of a vertical linear array and a combined array scheme of sound pressure hydrophones and vector hydrophones are used. Combined with the constant-beam wide beamforming method and the joint processing method of vector signal sound pressure velocity, stable unilateral directivity is obtained. This achieves a large measurement gain while having a small number of array elements and a small array aperture, extending the lower limit of the measurement frequency and achieving broadband radiated noise measurement in the low-frequency band. This invention aims to reduce the redundancy of measurement array elements, solve the problems of limited working bandwidth and two-dimensional robust constant beamwidth beamforming in noise measurement, and achieve accurate measurement of full-band radiated noise of underwater targets.

[0069] First, a sparsely structured high-frequency acoustic pressure spiral biconical volume array and a low-frequency large-aperture acoustic pressure vector nested vertical linear array are designed to form a sparse combined array. A supporting hardware system and data processing module are also designed to constitute a radiated noise measurement system. The system includes a wet-end test platform and a dry-end data processing device. The wet-end platform includes a sparse combined test array, an underwater navigation and positioning device, a depth sensor, an attitude sensor, an electronic instrument compartment, a titanium alloy array frame structure for the acoustic pressure spiral biconical volume array, a voltage-stabilized instrument compartment, a signal transmission optoelectronic composite cable, a float-swivel-weight mooring system, and a plastic-coated steel cable.

[0070] A schematic diagram of the deployment of the sparse combined array measurement system is shown below. Figure 1As shown. The system includes a wet-end test platform and a dry-end data processing device. The wet-end platform includes a sparse combined test array, an underwater navigation and positioning device, a depth sensor, an attitude sensor, an electronic instrument compartment, a titanium alloy array frame structure for an acoustic pressure spiral biconical volume array, a voltage-stabilized instrument compartment, a signal transmission optoelectronic composite cable, a float-swivel-weight mooring system, and plastic-coated steel cables. The sparse combined test array includes a high-frequency acoustic pressure spiral biconical volume array and a low-frequency large-aperture acoustic pressure vector nested vertical linear array (with depth sensors embedded at both ends of the array). The underwater navigation and positioning device includes a synchronous acoustic beacon and an underwater navigation and positioning base array. The electronic instrument compartment contains a signal conditioning module and a data acquisition and control module, and also includes an attitude sensor. The acoustic pressure spiral biconical volume array adopts a high-strength, lightweight, and corrosion-resistant mesh frame structure, and the volume array frame structure is moored to the acoustic pressure vector nesting system by eight plastic-coated steel cables on the top and bottom. The intermediate transition mooring component of the vertical linear array enables the combined installation of the nested vertical linear array of sound pressure vectors and the high-frequency sound pressure spiral double-cone volume array; the underwater navigation and positioning base array and the electronic instrument compartment are fixed on the array frame; the pressure stabilizing instrument compartment is equipped with a pressure stabilizing device; the signal transmission optoelectronic composite cable connects the wet end test platform and the dry end data processing device, and is used to power the wet end test platform and transmit data and control commands; the float-swivel-weight mooring system includes a main float, a secondary float, a mechanical swivel, an intermediate transition mooring component (containing depth and attitude sensors), an optoelectronic slip ring, a release device, and an anchor block; the sparse combined test array is vertically suspended in the water through the float-swivel-weight mooring system, ensuring its vertical attitude in the water. The upper mechanical swivel and lower optoelectronic slip ring of the sparse combined test array are used to release the rotational torque of the measurement array and reduce the rotation of the optical cable with the measurement array.

[0071] The core component of the sparse combination array measurement system is the sparse combination test array, which is composed of a sparsely structured acoustic pressure spiral biconical volume array and an acoustic pressure vector nested vertical linear array. The acoustic pressure vector nested vertical linear array passes through the center of the acoustic pressure spiral biconical volume array, and its central array element is located at the center of the circular cross-section with the smallest radius of the acoustic pressure spiral biconical volume array and is perpendicular to the cross-section, that is, the geometric centers of the two coincide. The upper end of the acoustic pressure spiral biconical volume array is connected to the tethering ring of the intermediate transition tethering component 1 through a plastic-coated steel cable, and the lower end is connected to the tethering ring of the intermediate transition tethering component 2 through a plastic-coated steel cable. The two tethering components transmit upward and downward tension respectively to ensure that the spiral biconical volume array is vertically positioned and that its central array element is on the same plane as the central array element of the acoustic pressure vector nested vertical linear array. The upper end of the acoustic pressure vector nested vertical linear array is connected to the mechanical rotating ring through a plastic-coated steel cable, and the lower end is connected to the photoelectric slip ring through a multi-core load-bearing electrical connector. The mechanical rotating ring and the photoelectric slip ring transmit upward and downward tension respectively to ensure that the acoustic pressure vector nested vertical linear array is vertically positioned.

[0072] The acoustic pressure spiral biconical volume array is used to measure the mid-to-high frequency radiated noise of underwater targets. M1 identical single sparse linear arrays with N1 array elements are evenly arranged on a circle with radius R to form a cylindrical array with radius R and height L. Then, the bottom ring is fixed and the top ring is rotated counterclockwise around the cylindrical axis by an angle α, where the value of α is between 0° and 180°.

[0073] The single sparse linear array employs a sparse nested array arrangement spanning multiple octaves, consisting of M2 array elements with N elements. Tl It is composed of concentric nested uniform sound pressure subarrays, with element spacing of d1, 3d1, 9d1, ... in each uniform sound pressure subarray. 2≤M2≤4.

[0074] For example, a single sparse linear array can consist of 3 array elements with a total number of N. Tl It is composed of concentric nested uniform sound pressure subarrays. The element spacing of subarray 1, subarray 2 and subarray 3 is d1, 3d1 and 9d1 respectively, and the total length of the linear array is 9(N1-1)d1.

[0075] The nested vertical linear array of acoustic pressure vectors is used to measure the low-frequency radiated noise of underwater targets. The array employs a sparse nested arrangement with 2 octave bands, consisting of M3 array elements and N elements. L It is composed of concentric nested uniform subarrays, with element spacing of d2, 4d2, 16d2, ... in each uniform subarray. Some of the uniform subarrays are sound pressure vector combination arrays, and the number of vector array elements in the sound pressure vector combination array is M. v ;2≤M3≤4.

[0076] For example, a nested vertical linear array of sound pressure vectors can consist of two arrays with N elements. L It is composed of concentric nested uniform subarrays. The element spacing of subarray 1 and subarray 2 is d2 and 4d2, respectively. Subarray 1 (high-frequency subarray) is a sound pressure vector combination array with N vector array elements. v The number of sound pressure array elements is N L -N v Subarray 2 is a sound pressure array, and the total length of the nested vertical linear array of sound pressure vectors is 4(N2-1)d2.

[0077] The radiated noise of the target under test is measured using the sparse combined array measurement system described above. The radiated noise signal of the target under test received by the sparse combined array is obtained and then transformed into the frequency domain.

[0078] Assuming the measured target has a broadband radiated noise signal s(t), its frequency domain representation is S(f), and the direction of the incoming wave is... The incident sound wave is projected onto a sparse array, where the elevation angle θ represents the angle between the incident direction of the sound wave and the z-axis, and the azimuth angle... Let represent the angle between the incident sound wave projected onto the horizontal plane and the x-axis. At this point, the unit direction vector u of the incident sound wave from the array is:

[0079]

[0080] The time delay τ of the received signal of the array element relative to the reference origin can be expressed as:

[0081]

[0082] In the formula, c represents the propagation speed of underwater sound waves, which is a function of depth. However, for simplicity, the sound speed can generally be approximated as a constant value; r represents the spatial coordinates of the array elements. After obtaining the time delay, the steering vector of the array can be calculated. for:

[0083]

[0084] In the formula, f is the frequency of the radiated noise signal to be measured. Let X(f) be the received signal of each array element, which generally includes the sound source signal and noise signal after propagation through the channel. Then the array received signal model X(f) can be expressed as:

[0085]

[0086] In the formula, N(f) is the received noise matrix of each array element.

[0087] By utilizing a sound pressure spiral biconical volume array, combined with a sparse array scheme and an improved nested array constant beamwidth beamforming method, the weighting vectors at different inherent frequencies of the entire volume array are solved using a convex optimization algorithm to obtain an ultra-wideband two-dimensional robust constant beamwidth beam, which is then used to measure the high-frequency broadband radiated noise of the target obtained in step 1.

[0088] A sound pressure spiral biconical volumetric array model consisting of N1×M1 isotropic array elements is established to receive the radiated noise signal from the target. The position coordinates of the (n1, m1)th array element in three-dimensional space are given. for:

[0089]

[0090] In the formula, These are the x-axis, y-axis, and z-axis coordinates of the (n1, m1)th array element, respectively. Let (n1, m1) be the elevation angle of the (n1, m1)th array element relative to the origin. Let be the azimuth angle of the (n1, m1)th array element relative to the origin. The geometric distance between the (n,m)th element and the reference origin is expressed in the following form:

[0091]

[0092] In the formula, there exists a relationship where n1 = 1, 2, K, N1; m1 = 1, 2, ..., M1. Then, the time delay of the received signal of the (n1, m1)th array element relative to the reference origin... It can be represented as:

[0093]

[0094] Then, the guiding vector of the sound pressure spiral biconical volume array for:

[0095]

[0096] The frequency domain output X of the array TBCA (f) is represented as:

[0097]

[0098] In the formula, N TBCA (f) represents the additive noise matrix received by each element of the acoustic pressure spiral biconical volume array. The broadband radiated noise signal received by the acoustic pressure spiral biconical volume array is divided into L... TBCA The analysis is performed on the l frequency sub-band. TBCA The result of beamforming in each frequency sub-band This can be simply represented as:

[0099]

[0100] In the formula, The center frequency is The l TBCA The sound pressure spiral biconical volume matrix weighted vector for each frequency subband, where H represents the conjugate transpose. For the l TBCA The frequency sub-band range. The l-th frequency sub-band of the acoustic pressure spiral biconical volume array is solved using a convex optimization algorithm. TBCA Weighted vector of each frequency sub-band

[0101]

[0102] In the formula, Θ represents the range of the elevation angle θ, which is generally taken as [0, π]; Ψ represents the azimuth angle. The range is generally [0, 2π]; B d (Θ MI ,Ψ MJ ) represents the desired main lobe amplitude of the beam; Θ MI Θ represents the range of elevation angles corresponding to the desired main lobe of the beam. SI Ψ represents the range of elevation angles corresponding to the desired beam sidelobes. MJΨ represents the azimuth range corresponding to the desired main lobe of the beam. SJ The desired beam sidelobe corresponds to the azimuth range, while the desired beam main lobe can be adjusted according to the actual target size and test distance; δ s As an upper bound constraint for the azimuth beam sidelobes, η s ζ0 is the upper bound constraint for the pitch angle beam sidelobe, and ζ0 is the upper bound constraint for the weighted vector 2-norm.

[0103] The measurement gain of the sound pressure spiral biconical volume array is mainly divided into array gain and time processing gain, which can be expressed as:

[0104] G A,TBCA =AG TBCA +G T,TBCA

[0105] In the formula, AG TBCA G represents the spatial gain of the sound pressure spiral biconical volume array. T,TBCA This indicates the time processing gain of the sound pressure spiral biconical volume array.

[0106] Assuming the signal field, noise field, and directivity function of the sound pressure spiral biconical volume array are respectively represented by the function and This means that, from the spatial azimuth angle... Within a unit spatial angle Ω incident on the array, the power of the signal and noise can be represented by the result of the mutual integration of three functions, at which point the array gain is:

[0107]

[0108] The time-processing gain of the sound pressure spiral biconical volume array is the gain obtainable by frequency domain integration, which can be expressed as:

[0109] G T,TBCA =5lgBT

[0110] In the formula, B is the bandwidth and T is the integration time.

[0111] By utilizing a nested vertical linear array of acoustic pressure vectors, based on a sparse structure and a combined array scheme of acoustic pressure hydrophones and vector hydrophones, an improved nested array constant beamwidth beamforming method is adopted, combined with a vector signal acoustic pressure velocity joint processing method and a near-field focusing beamforming method to form an ultra-wideband two-dimensional robust constant beamwidth beam. The beamforming method is combined with acoustic vector array testing technology to obtain additional coherent signal processing gain, and the low-frequency broadband radiated noise of the target obtained in step 1 is measured.

[0112] Vector hydrophones can simultaneously pick up the three orthogonal components {v} of the sound pressure signal p(t) and the particle velocity v(t) in the sound field at a single point in space. x(t),v y (t),v z (t)}. Far-field plane waves in space from The incident signal s(t) can be projected onto a three-dimensional Cartesian coordinate system based on its direction of incidence. The sound pressure signal p(t) and its three directional velocity components can be written as:

[0113] p(t) = s(t),

[0114]

[0115]

[0116] v z (t)=s(t)cosθ

[0117] In the formula, {v x (t),v y (t),v z s(t) and s(t) represent the projections of s(t) onto the three orthogonal directions x, y, and z in three-dimensional space, respectively, which are the acoustic signals received by the velocity channel of the vector hydrophone. By combining these three mutually orthogonal velocity signals, the combined velocity v can be obtained. c (t):

[0118]

[0119] In the formula, θ represents the horizontal guiding azimuth angle, and θ0 represents the vertical guiding pitch angle.

[0120] Let the number of elements in the nested vertical linear array of sound pressure vectors be N. v The number of sound pressure array elements is N p Then the sound pressure vector nested in the vertical linear array sound pressure channel guide vector A p (f,θ) and vibration channel guide vector They are respectively:

[0121]

[0122] In the formula, The guiding vector for the acoustic pressure array elements; is the sound pressure channel guide vector of the vector array element; r0 is the distance from the reference origin to the sound center of the target being measured; For the number n p The acoustic pressure array element steering vector, n is the distance from the sound pressure element to the sound center of the target being measured. p =1,2,KN p ; For the number n v The sound pressure channel steering vector of the vector array element. n is the distance from the vector array element to the acoustic center of the target being measured. v =1,2,KN v ; The guide vector for a single vector hydrophone; The direction of arrival. The frequency domain output X of all sound pressure channels (including sound pressure array elements and vector array element sound pressure channels) in the nested vertical linear array of sound pressure vectors. ULA,p (f) is represented as:

[0123] X ULA,p (f)=A p (f,θ)S(f)+N ULA,p (f)

[0124] In the formula, N ULA,p (f) represents the additive noise matrix received by all sound pressure channels in the nested vertical linear array of sound pressure vectors. The frequency domain output of the combined vibration velocity of the vector array elements in the nested vertical linear array of sound pressure vectors is also shown. Represented as:

[0125]

[0126] In the formula, N ULA,v (f) is the additive noise matrix received by all vector array elements in the nested vertical linear array of sound pressure vectors.

[0127] The sound pressure channel and the combined vibration velocity are compared using "(p+v"). c ) 2 The combined processing in the form of "" divides the broadband radiated noise signal received by the nested vertical linear array of sound pressure vectors into L ULA The analysis is performed on the l frequency sub-band. ULA The result of beamforming in each frequency sub-band This can be simply represented as:

[0128]

[0129] In the formula, The center frequency is The l ULA The sound pressure vectors of each frequency sub-band are nested with the weighted vectors of the vertical linear array sound pressure channels. The center frequency is The l ULA The sound pressure vectors of each frequency sub-band are nested into a weighted vector of the vertical linear array vibration velocity channels, where H represents the conjugate transpose. For the l ULA Each frequency sub-band range. The l-th frequency sub-band of the nested vertical linear array of sound pressure vectors is solved using a convex optimization algorithm. ULA The sound pressure channel weighted vector of each frequency sub-band and combined vibration velocity channel weighted vector To achieve constant beamwidth beamforming, the expressions are as follows:

[0130]

[0131] In the formula, B d,p (Θ MI ) represents the desired main lobe amplitude of the beam at the elevation angle. The desired main lobe amplitude can be adjusted according to the actual size of the target being measured and the test distance; Θ MI The range of elevation angles corresponding to the main lobe of the beam; Θ SI The range of elevation angles corresponding to the beam sidelobes is determined based on the size of the target being measured and the test distance. Ψ represents the desired main lobe amplitude of the azimuth angle. MJ Ψ represents the azimuth range corresponding to the main lobe of the beam. SJ The azimuth range corresponding to the beam sidelobes; δ s As an upper bound constraint for the azimuth beam sidelobes, η s ζ0 is the upper bound constraint for the pitch angle beam sidelobe, and ζ0 is the upper bound constraint for the weighted vector 2-norm.

[0132] The gain of the sound pressure vector nested vertical linear array measurement can be expressed as:

[0133] G A,ULA =AG ULA +G T,ULA

[0134] In the formula, AG ULA G represents the spatial gain of the nested vertical linear array of sound pressure vectors. T,ULA This represents the time processing gain of the nested vertical linear array of sound pressure vectors. ULA Calculation method and spatial gain AG of sound pressure spiral biconical volume array TBCA The calculation method is the same. The time processing gain G of the nested vertical linear array of the sound pressure vector. T,ULA The expression is as follows:

[0135] G T,ULA =5lgBT+k

[0136] In the formula, k is the gain of the combined sound pressure and vibration velocity processing, and its expression is:

[0137]

[0138] In the formula, and These are the sound pressure velocity coherence coefficients of the signal field and the noise field at frequency f0, respectively. When the target signal is a fully coherent signal... The noise is perfectly isotropic. When this happens, the combined processing gain tends towards infinity. Actual marine environmental noise is not completely isotropic; when the coherence coefficient of the noise field... When the values ​​are 0.5, 0.25, and 0.1 respectively, the joint processing gain k is 6dB, 12dB, and 20dB.

[0139] After obtaining the beamforming results of the sparse array, spectral analysis is performed to calculate parameters such as the 1 / 3 octave band sound pressure source level and broadband sound source level of the target under test, thereby achieving effective measurement of the full-band radiated noise of the target under test. Among them, the radiated noise in the mid-to-high frequency band is measured using a sound pressure spiral biconical volume array, while the radiated noise in the low frequency band is measured using a sound pressure vector nested vertical linear array.

[0140] The beamforming result B(f) of the sparse array can be expressed as:

[0141]

[0142] Power spectral density Q(f) is obtained by performing power spectral analysis on it:

[0143]

[0144] In the formula, K is the number of snapshots of the time-domain signal, and f s Let |·| be the signal sampling frequency, and |·| represent the magnitude.

[0145] Calculate the 1 / 3 octave band sound pressure level L based on the power spectral density. pso (i):

[0146]

[0147] In the formula, i is the 1 / 3 octave band number, f i Let be the center frequency of the i-th 1 / 3 octave band, and D be the distance from the reference origin to the equivalent sound center of the target being measured.

[0148] Broadband sound source level L p The calculation formula is as follows:

[0149]

[0150] In the formula, I represents the number of 1 / 3 octave bands within the wideband.

[0151] The actual effects of the present invention will be analyzed below with reference to simulation examples.

[0152] Simulation 1: Design of a sparse array covering the frequency range [10Hz, 50kHz]. The acoustic pressure vector nested vertical linear array is designed to operate in the frequency range [10Hz, 1kHz]. Combining an improved nested array constant-beamwidth beamforming method, the operating frequency band of a single subarray is set to two octaves. Considering limitations in array potting, transportation, and engineering deployment, the acoustic pressure vector nested vertical linear array consists of two arrays with N elements. L It is composed of 17 uniformly nested subarrays. The element spacing of subarray 1 and subarray 2 is d2 = 1m and 4d2 = 4m respectively. Subarray 1 is a sound pressure vector combination array with N vector array elements. v =9, the number of sound pressure array elements is 8, subarray 2 is a sound pressure array, the total length of the sound pressure vector nested vertical linear array is 64m, the total number of array elements is 29, the array element position diagram of the sound pressure vector nested vertical linear array is shown in Figure 2(a), where the red array elements are vector array elements and the black array elements are sound pressure array elements. Design a sound pressure spiral double cone volume array with a working frequency range of [1kHz, 50kHz]. Combined with the improved nested array constant beamwidth beamforming method, the sound pressure spiral double cone volume array single sparse linear array adopts a cross-octave sparse nested array. The number of array elements of the single sparse linear array is N1 = 29, which consists of 3 array lines with N elements. Tl The sound pressure subarray consists of 13 uniform sound pressure subarrays nested concentrically. The element spacing of subarray 1, subarray 2 and subarray 3 is d1 = 0.04m, 3d1 = 0.12m and 9d1 = 0.36m respectively. The total length of the linear array is 4.32m. The sound pressure spiral biconical volume array is formed by twisting M1 = 12 single sparse linear arrays of sound pressure spiral biconical volume arrays by 160°. The maximum radius is R = 0.72m and the overall height is 4.08m. The total number of array elements is 348. The three-dimensional view of the array element positions of the sound pressure spiral biconical volume array is shown in Figure 2(b).

[0153] Simulation 2: The simulation frequency range is [10Hz, 50kHz], and the direction of arrival is... For a nested vertical linear array with sound pressure vectors, the simulation frequency range is [10Hz, 1kHz]. An improved nested array constant beamwidth beamforming method combined with a vector signal sound pressure velocity joint processing method and a near-field focusing method is used to form a two-dimensional robust constant beamwidth, as shown in Figures 3(a) and 3(c). For a sound pressure spiral biconical volume array, the simulation frequency range is [1kHz, 50kHz]. An improved nested array constant beamwidth beamforming method is used to apply convex optimization constraints to the entire volume array, achieving constant beamwidth beamforming in both the vertical and horizontal directions, as shown in Figures 3(b) and 3(d). The gain of the sparse combined array in the frequency range [10Hz, 50kHz] is calculated as follows: Figure 4 As shown; the constant-beamwidth beamforming performance of the sparse combined array is as follows: Figure 5As shown in the figure. Simulation results show that the sparse array measurement has a relatively stable beamwidth in the [50Hz, 25kHz] frequency band and a high array gain in the [10Hz, 1kHz] frequency band, which can realize effective measurement of low-noise underwater targets.

[0154] This invention addresses the problem of measuring radiated noise from low-noise underwater targets. It designs a sparse combination array formed by a sparsely structured acoustic pressure spiral biconical volume array and a nested acoustic pressure vector vertical linear array. By employing a frequency-band testing scheme combining a high-frequency volume array and a low-frequency vertical linear array, and utilizing a combined measurement method combining acoustic pressure hydrophones and vector hydrophones, the measurement frequency band is extended, enabling effective measurement of the full-band radiated noise of underwater targets. Through a sparse array structure and an improved constant-beam wide beamforming method, a robust two-dimensional constant-beam wide beam is obtained while reducing the number of array elements and array complexity. Furthermore, the main lobe width and low side lobe level can be adjusted according to the target and measurement distance. In the mid-to-high frequency band, for acoustic pressure spiral biconical volume arrays, an improved nested array constant-beamwidth beamforming method is used to achieve robust two-dimensional constant-beamwidth beamforming. In the low frequency band, for acoustic pressure vector nested vertical linear arrays, an improved nested array constant-beamwidth beamforming method is combined with a vector signal acoustic pressure velocity joint processing method and a near-field focusing method to obtain unilateral directivity, improve array gain, effectively extend the lower limit frequency of measurement, and improve measurement accuracy. This invention reduces the redundancy of the measurement array elements, solves the problems of limited working bandwidth and robust two-dimensional constant-beamwidth beamforming in noise measurement, and achieves accurate measurement of broadband radiated noise of underwater targets. In addition, the beam directivity of the measurement system can be adjusted through signal processing methods, making it more flexible and applicable to various application scenarios of underwater radiated noise measurement.

[0155] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A system for measuring the radiated noise of an underwater target with a sparse array, characterized in that: It includes a wet-end testing platform and a dry-end data processing device, which are connected by a signal transmission optical fiber composite cable; The wet-end test platform includes a sparse combined array, an underwater navigation and positioning array, a depth sensor, an electronic instrument compartment, a pressure stabilizing instrument compartment, and a float-swivel-weight mooring system; the float-swivel-weight mooring system includes a main float, a secondary float, a mechanical swivel, an optoelectronic slip ring, a release device, and an anchor block; The sparse combination array includes a sound pressure spiral biconical volume array and a sound pressure vector nested vertical linear array; the sound pressure spiral biconical volume array is obtained by fixing the bottom ring of a cylindrical array and rotating the top ring around the cylindrical axis by a certain angle; the sound pressure vector nested vertical linear array passes through the center of the sound pressure spiral biconical volume array, and the central element of the sound pressure vector nested vertical linear array is located at the center of the circular cross-section with the smallest radius of the sound pressure spiral biconical volume array; The acoustic pressure spiral biconical volume array is installed in the array frame. The upper end of the array frame is connected to the first intermediate transfer mooring member via a cable, and the lower end of the array frame is connected to the second intermediate transfer mooring member via a cable. The underwater navigation and positioning base array is installed on the top of the array frame, and the electronic instrument cabin is installed at the bottom of the array frame. The electronic instrument cabin is equipped with an attitude sensor, a signal conditioning module, and a data acquisition and control module. The first intermediate transfer mooring member is connected to the upper end of the acoustic pressure spiral biconical volume array, and the second intermediate transfer mooring member is connected to the lower end of the acoustic pressure spiral biconical volume array. The first intermediate transfer mooring member and the second intermediate transfer mooring member are equipped with a depth sensor and an attitude sensor. The first intermediate transfer mooring member and the second intermediate transfer mooring member respectively transmit upward and downward tension, so that the acoustic pressure spiral biconical volume array is vertically arranged and its central array element is on the same plane as the central array element of the nested vertical linear array of acoustic pressure vectors. The upper end of the nested vertical linear array of sound pressure vectors is connected to a mechanical rotating ring via a cable, and the mechanical rotating ring is connected to the main float via a cable. The lower end of the nested vertical linear array of sound pressure vectors is connected to a photoelectric slip ring via a multi-core load-bearing electrical connector. The photoelectric slip ring, the pressure stabilizing instrument compartment, the release device, the secondary float, and the weight are connected in series via cables. A pressure stabilizing device is installed inside the pressure stabilizing instrument compartment. The mechanical rotating ring and the photoelectric slip ring are used to reduce the rotational torque of the sparse array and reduce the rotation of the cable with the sparse array.

2. The underwater target radiated noise measurement system with a sparse combined array according to claim 1, characterized in that: The cylindrical array includes multiple sets of single sparse linear arrays with the same number of array elements uniformly arranged on the circumference; the single sparse linear array adopts a cross-octave sparse nested array, the sound pressure vector nested vertical linear array adopts a 2-octave sparse nested array, and the central array element of the sound pressure spiral biconical volume array and the central array element of the sound pressure vector nested vertical linear array are on the same plane.

3. The underwater target radiated noise measurement system with a sparse combined array according to claim 1, characterized in that: The sound pressure spiral biconical volume array comprises M1 array elements of N1 single sparse linear arrays; the single sparse linear array comprises M2 array elements of N Tl It is composed of concentric nested uniform sound pressure subarrays, with the element spacing in each uniform sound pressure subarray being as follows: 2≤M2≤4; The sound pressure vector nested vertical linear array consists of M3 array elements and N elements. L It is composed of concentric nested uniform subarrays, and the element spacing in each uniform subarray is as follows: Some of the uniform subarrays are sound pressure vector combination arrays, and the number of vector array elements in the sound pressure vector combination array is M. v ;2≤M3≤4.

4. A measurement method based on the underwater target radiated noise measurement system with sparse combined array as described in claim 1, characterized in that, Includes the following steps: Step 1: Deploy the underwater target radiated noise measurement system in the measurement water area, receive the radiated noise signal of the target being measured, and transform the received radiated noise signal of the target being measured into the frequency domain; Step 2: For the acoustic pressure spiral biconical volume array, an improved nested array constant-beamwidth beamforming method is adopted. A convex optimization algorithm is used to perform constant-beamwidth beamforming on the entire acoustic pressure spiral biconical volume array, obtaining an ultra-wideband two-dimensional robust constant-beamwidth beam. This allows for the acquisition of the beamforming result B of the mid- and high-frequency broadband radiated noise of the target under test. TBCA (f); Step 3: For the nested vertical linear array of sound pressure vectors, an improved nested array constant beamwidth beamforming method is adopted, combined with a vector signal sound pressure and vibration velocity joint processing method. The sound pressure channel and vibration velocity channel of the nested vertical linear array of sound pressure vectors are respectively subjected to ultra-wideband constant beamwidth beamforming using a convex optimization algorithm to obtain a two-dimensional robust constant beamwidth, thereby obtaining the beamforming result B of the low-frequency broadband radiated noise of the target under test. ULA (f); Step 4: After combining the beamforming results of the sound pressure helical biconical volume array and the sound pressure vector nested vertical linear array into B(f), perform spectral analysis on B(f) to obtain the power spectral density Q(f). Based on Q(f), calculate the 1 / 3 octave band sound pressure source level L of the target under test. pso (i) and broadband sound source level L p This enables effective measurement of the full-band radiated noise of the target under test; Where K is the number of snapshots in the time domain signal; f s The signal sampling frequency is represented by |·|; | represents the magnitude; i is the 1 / 3 octave band number; f i is the center frequency of the i-th 1 / 3 octave band; D is the distance from the reference origin to the equivalent sound center of the target being measured; I is the number of 1 / 3 octave bands included in the wideband.

5. The method for measuring radiated noise of an underwater target according to claim 4, characterized in that: In step 1, the broadband radiated noise signal s(t) of the target under test is represented in the frequency domain as S(f), and the direction of the incoming wave is... Incident on a sparse array, the elevation angle θ represents the angle between the incident direction of the sound wave and the z-axis, and the azimuth angle... Let X(f) represent the angle between the incident sound wave projected onto the horizontal plane and the x-axis. The array-received signal model X(f) is expressed as: in, The guide vector for the sparse composite array. f is the frequency of the broadband radiated noise signal of the target under test, and τ is the time delay of the received signal of the array element in the sparse array relative to the reference origin. c represents the propagation speed of underwater sound waves, r represents the spatial coordinates of the array elements in the sparse array, and u represents the unit direction vector of the incident sound wave.

6. The method for measuring radiated noise of an underwater target according to claim 5, characterized in that: Step 2 specifically involves: establishing a sound pressure spiral biconical volume array model composed of N1×M1 isotropic array elements, and determining the position coordinates of the (n1, m1)th array element in three-dimensional space. for: Where n1 = 1, 2, K, N1; m1 = 1, 2, ..., M1; These are the x-axis, y-axis, and z-axis coordinates of the (n1, m1)th array element, respectively. Let be the elevation angle of the (n1, m1)th array element relative to the origin; Let be the azimuth angle of the (n1, m1)th array element relative to the origin; The geometric distance between the (n,m)th element and the reference origin is expressed in the following form: The time delay of the received signal of the (n1, m1)th array element relative to the reference origin Represented as: The guiding vector of the sound pressure spiral biconical volume array for: The frequency domain output X of the array TBCA (f) is represented as: Where, N TBCA (f) represents the additive noise matrix received by each element of the acoustic pressure spiral biconical volume array; for the broadband radiated noise signal received by the acoustic pressure spiral biconical volume array, it is divided into L... TBCA The analysis is performed on the l frequency sub-band. TBCA The result of beamforming in each frequency sub-band Represented as: in, Indicates the lth TBCA Weighted vector of sound pressure spiral biconical volume matrix for each frequency sub-band; This is the center frequency of the sub-band; the superscript H indicates the conjugate transpose. For the l TBCA Each frequency sub-band range; The l-th sound pressure spiral biconical volume matrix is ​​solved using a convex optimization algorithm. TBCA Weighted vector of each frequency sub-band The expression for achieving constant-beam wide-width beamforming is: Where Θ represents the range of the pitch angle θ, taking the value [0, π]; Ψ represents the azimuth angle. The range is [0, 2π]; B d (Θ MI ,Ψ MJ ) represents the desired main lobe amplitude of the beam; Θ MI Θ represents the range of elevation angles corresponding to the desired main lobe of the beam. SI Ψ represents the range of elevation angles corresponding to the desired beam sidelobes. MJ Ψ represents the azimuth range corresponding to the desired main lobe of the beam. SJ The desired beam sidelobe corresponds to the azimuth range, while the desired beam main lobe can be adjusted according to the actual target size and test distance; δ s As an upper bound constraint for the azimuth beam sidelobes, η s ζ0 is the upper bound constraint for the pitch angle beam sidelobe, and ζ0 is the upper bound constraint for the weighted vector 2-norm.

7. The method for measuring radiated noise of an underwater target according to claim 6, characterized in that: Step 3 specifically involves: the sound pressure vector nested vertical linear array having N vector array elements. v The number of sound pressure array elements is N p Sound pressure vector nested in a vertical linear array, sound pressure channel steering vector A p (f,θ) and vibration channel guide vector They are respectively: in, The guiding vector for the acoustic pressure array elements; is the sound pressure channel guide vector of the vector array element; r0 is the distance from the reference origin to the sound center of the target being measured; For the number n p The acoustic pressure array element steering vector, n is the distance from the sound pressure element to the sound center of the target being measured. p =1,2,KN p ; For the number n v The sound pressure channel steering vector of the vector array element. n is the distance from the vector array element to the acoustic center of the target being measured. v =1,2,KN v ; The direction of arrival; the frequency domain output X of the sound pressure channel of all sound pressure elements and vector elements in the nested vertical linear array of sound pressure vectors. ULA,p (f) is represented as: X ULA,p (f)=A p (f,θ)S(f)+N ULA,p (f) Where, N ULA,p (f) is the additive noise matrix received by all sound pressure channels in the nested vertical linear array of sound pressure vectors; Frequency domain output of the combined vibration velocity of the vector array elements in a nested vertical linear array of sound pressure vectors Represented as: Where, N ULA,v (f) is the additive noise matrix received by all vector array elements in the nested vertical linear array of sound pressure vectors; For the broadband radiated noise signal received by the sound pressure vector nested vertical linear array, it is divided into L ULA The analysis is performed on the l frequency sub-band. ULA The result of beamforming in each frequency sub-band Represented as: in, The center frequency is The l ULA The sound pressure vector of each frequency sub-band is nested with the weighted vector of the vertical linear array sound pressure channels; The center frequency is The l ULA The sound pressure vector of each frequency sub-band is nested with the weighted vector of the vertical linear array vibration velocity channel; For the l ULA Each frequency sub-band range; The l-th nested vertical linear array of sound pressure vectors is solved using a convex optimization algorithm. ULA The sound pressure channel weighted vector of each frequency sub-band and combined vibration velocity channel weighted vector To achieve constant-beam wide-beamforming, the expression is: Among them, B d,p (Θ MI ) represents the desired main lobe amplitude of the beam at the pitch angle; Θ MI Θ represents the range of elevation angles corresponding to the desired main lobe of the beam. SI The range of pitch angles corresponding to the side lobes of the desired beam is defined, while the range of pitch angles of the main lobe of the desired beam can be adjusted according to the actual vertical dimensions of the target being measured and the test distance. Ψ represents the desired main lobe amplitude of the azimuth beam. MJ Ψ represents the azimuth range corresponding to the desired main lobe of the beam. SJ The desired azimuth range corresponds to the sidelobes of the beam; the desired main lobe azimuth range can be adjusted according to the actual horizontal scale of the target and the test distance. δ s As an upper bound constraint for the azimuth beam sidelobes, η s ζ0 is the upper bound constraint for the pitch angle beam sidelobe, and ζ0 is the upper bound constraint for the weighted vector 2-norm.

8. A computer device, comprising a memory, a processor, and a computer program stored in the memory, characterized in that: The processor executes the computer program to implement the steps of the method according to any one of claims 4 to 7.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that: When executed by a processor, the computer program implements the steps of the method according to any one of claims 4 to 7.

10. A computer program product comprising computer instructions, characterized in that: When executed by a processor, the computer instructions implement the steps of the method according to any one of claims 4 to 7.

Images