Underwater positioning method based on single hydrophone

Abstract

The invention provides an underwater positioning method based on a single hydrophone, which belongs to the technical field of underwater azimuth measurement, and comprises the following steps: a signal acquisition step: acquiring an underwater sound signal; a signal preprocessing step; a virtual hydrophone array simulation step; a frequency domain snapshot matrix compensation step: performing phase compensation on the frequency domain snapshot matrix in the frequency domain; a beam forming and angle estimating step; and a sound source positioning step of calculating the horizontal distance of the sound source relative to the virtual hydrophone array and the depth of the sound source according to the depth-angle data so as to complete underwater target positioning. According to the underwater positioning method based on the single hydrophone, the underwater sound signals of different depths are collected through the single hydrophone, the virtual hydrophone array is constructed, the horizontal distance and depth of the sound source relative to the virtual hydrophone array are calculated, the sound source is positioned through the single hydrophone, the cost is lower, and the hydrophone is easy to arrange.

Description

Technical Field

[0001] The invention belongs to the technical field of underwater position measurement, and belongs to the technical field of position or distance measurement, and specifically relates to an underwater positioning method based on a single hydrophone. Background Art

[0002] With the increasingly urgent demand for the development of marine resources, people pay more and more attention to the positioning of underwater target sound sources. Underwater passive positioning has been widely studied as a common method for detecting underwater non-cooperative targets, and acoustic signals, as mechanical waves with low propagation attenuation in water, have become an important method for locating underwater targets. However, the commonly used positioning methods at this stage have problems such as inconvenient observation, high measurement cost, cumbersome long array deployment, and large amount of calculation to solve target position information, which greatly limits people's exploration of the ocean.

[0003] Therefore, it is necessary to propose a method for locating underwater targets based on a single hydrophone to solve the above technical problems. Summary of the invention

[0004] In order to solve the problems that the existing underwater target sound source positioning method requires the deployment of a long array of hydrophones for receiving underwater acoustic signals at different depths, and has high measurement costs and cumbersome long array deployment, the present invention proposes an underwater positioning method based on a single hydrophone, which can solve the above problems.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solutions to achieve the above problems: An underwater positioning method based on a single hydrophone, characterized by comprising: The signal collection step includes: controlling a single hydrophone to collect water acoustic signals during the process of floating up or sinking, obtaining a water acoustic signal sequence according to the collection time, and synchronously obtaining the depth information and position information of the hydrophone when collecting the water acoustic signal; The signal preprocessing step includes: calculating the spacing of the virtual hydrophone array according to the frequency of the hydroacoustic signal, and dividing the hydroacoustic signal sequence into N segments according to the spacing, wherein N is a positive integer; The virtual hydrophone array simulation step is to take each segment of the hydroacoustic signal as a signal collected by a virtual hydrophone at the current depth, obtain a virtual hydrophone array composed of N virtual hydrophones, calculate the frequency domain snapshot of each segment of the hydroacoustic signal, and all the frequency domain snapshots form a frequency domain snapshot matrix; A frequency domain snapshot matrix compensation step, performing phase compensation on the frequency domain snapshot matrix in the frequency domain; The beam forming and angle estimation step divides the virtual hydrophone array into a plurality of sub-arrays, wherein the virtual hydrophones in the same sub-array are continuous in space, and calculates the direction angle of the sound source relative to each of the sub-arrays according to the compensated frequency domain snapshot matrix to obtain a plurality of sets of depth-angle data; In the sound source localization step, the horizontal distance of the sound source relative to the virtual hydrophone array and the depth of the sound source are calculated based on the depth-angle data to complete the underwater target positioning.

[0006] In some embodiments, in the virtual hydrophone array simulation step, the method for calculating the frequency domain snapshot matrix is: performing a K-point Fourier transform on each segment of the hydroacoustic signal, and the lowest frequency of the transformed signal is There are M frequency values ​​between them, and the N-segment underwater acoustic signal corresponds to N×M frequency domain snapshots. The frequency domain snapshot matrix Y is expressed as: .

[0007] In some embodiments, the step of compensating the frequency domain snapshot matrix Y is also included. The compensation matrix for: ; in, is the signal sampling rate, T is the sampling time of each section of the hydroacoustic signal, T=d / v, v is the speed of the hydrophone, and d is the spacing of the virtual hydrophone array; Calculate the compensation matrix and the frequency domain snapshot matrix The Hadamard product is used as the compensated frequency domain snapshot signal.

[0008] In some embodiments, in the beamforming and angle estimation step, the same virtual hydrophone is divided into one of the subarrays or simultaneously divided into multiple subarrays, and the number of virtual hydrophones in each subarray is m. The beamforming and angle estimation step further includes: Each virtual hydrophone in the subarray is an array element, and the array element at one end of the subarray is used as a reference array element; Find the frequency domain snapshot sub-matrix corresponding to the sub-array from the compensated frequency domain snapshot matrix, and calculate the covariance matrix of the sub-matrix , for the search angle , construct beam output : ,in is the orientation vector, is an m-dimensional column vector, is the distance from each array element to the reference array element, is the frequency of the underwater acoustic signal, c is the signal propagation speed, and the calculation makes The search angle value corresponding to the maximum value is the direction angle of the sound source relative to the subarray.

[0009] In some embodiments, The value range is: -90°≤ ≤90°.

[0010] In some embodiments, the signal acquisition step also includes recording the horizontal displacement of the hydrophone during the process of floating or sinking. , and according to the horizontal offset Spatial phase compensation is performed on the virtual hydrophone array.

[0011] In some embodiments, the method for performing spatial phase compensation on the virtual hydrophone array includes: The spatial phase difference generated by the hydrophone during the vertical movement is calculated according to the horizontal offset : ; Calculate the steering vector and The Hadamard product is calculated and the result is reassigned to the steering vector ; The beamforming and angle estimation steps use the reassigned steering vector Calculate the direction angle.

[0012] In some embodiments, an acceleration sensor is used in the signal collection step to record the horizontal displacement of the hydrophone during the process of floating or sinking.

[0013] In some embodiments, the angle in the sound source localization step is represented by the tangent value of the directional angle, and the depth-angle data is fitted with a depth-angle linear relationship through the least squares method. The slope of the linear relationship is the horizontal distance of the sound source relative to the virtual hydrophone array. In the linear relationship, when the tangent value of the directional angle is 0, the corresponding depth is the depth of the sound source.

[0014] In some embodiments, a pressure sensor is used in the signal collection step to collect the depth of the hydrophone during its ascent or descent.

[0015] Compared with the prior art, the advantages and positive effects of the present invention are as follows: the underwater positioning method based on a single hydrophone of the present invention adopts a single hydrophone, collects hydroacoustic signals of different depths by controlling the hydrophone to float or sink, and is equivalent to the hydroacoustic signals collected by the virtual hydrophone array at different depths, which are used to construct a virtual hydrophone array, and the frequency domain snapshot matrix compensation step performs phase compensation on the frequency domain snapshot matrix in the frequency domain, thereby realizing time compensation for the virtual hydrophone array, and using the beamforming algorithm to calculate the azimuth angle of the sound source relative to each simulated virtual hydrophone array, and finally calculating the horizontal distance and depth of the sound source relative to the virtual hydrophone array according to the azimuth angle, thereby realizing the positioning of the sound source by a single hydrophone, with lower cost and simple hydrophone layout. This scheme can flexibly set the spacing of the virtual hydrophone array according to the frequency of the pre-acquired hydroacoustic signal, which is more convenient than the physical hydrophone array positioning method.

[0016] Other features and advantages of the present invention will become more apparent after reading the detailed description of the embodiments of the present invention in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is a flow chart of an embodiment of the underwater positioning method based on a single hydrophone proposed by the present invention; Figure 2 It is a schematic diagram of signal collection in one embodiment of the underwater positioning method based on a single hydrophone proposed by the present invention; Figure 3 is a schematic diagram of sound source positioning in an embodiment of an underwater positioning method based on a single hydrophone proposed by the present invention; Figure 4 is a schematic diagram of the spacing of a virtual hydrophone array in an embodiment of the underwater positioning method based on a single hydrophone proposed by the present invention; Figure 5 is an angle-depth map in one embodiment of the underwater positioning method based on a single hydrophone proposed by the present invention; Figure 6 It is a schematic diagram of fitting a linear relationship between depth and angle in an embodiment of the underwater positioning method based on a single hydrophone proposed by the present invention. DETAILED DESCRIPTION

[0018] The specific implementation modes of the present invention will be further described in detail below in conjunction with the accompanying drawings.

[0019] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0020] It should be noted that in the description of the present invention, the terms "upper", "lower", "left", "right", "vertical", "horizontal", "inside", "outside" and the like indicating directions or positional relationships are based on the directions or positional relationships shown in the drawings, which are merely for the convenience of description and do not indicate or imply that the device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance. In the description of the present invention, "multiple" means two or more, unless otherwise clearly and specifically defined.

[0021] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0022] Example 1, see Figure 1 As shown, this embodiment proposes an underwater positioning method based on a single hydrophone, including: a signal acquisition step, controlling a single hydrophone to collect water acoustic signals during the process of floating or sinking, obtaining a water acoustic signal sequence according to the acquisition time, and synchronously obtaining the depth information and position information of the hydrophone when collecting the water acoustic signal.

[0023] Signal preprocessing steps such as Figure 2 As shown, it includes: calculating the spacing of the virtual hydrophone array according to the frequency of the hydroacoustic signal, dividing the hydroacoustic signal sequence into N segments according to the spacing, wherein N is a positive integer. The N segments of hydroacoustic signals are used to simulate the hydroacoustic signals collected by the array including N virtual hydrophones.

[0024] The physical hydrophone array has a fixed spacing. When the spacing of the physical hydrophone array does not match the frequency domain of the sound source, it is either solved by adjusting the spacing, which is very inconvenient, or the spacing cannot be adjusted, resulting in poor signal acquisition accuracy, and thus reducing the accuracy of sound source positioning. In this solution, the frequency of the collected hydroacoustic signal in the frequency domain can be calculated by methods such as Fourier transform, and the spacing of the virtual hydrophone array is calculated according to the frequency of the hydroacoustic signal, making the spacing setting of the virtual hydrophone array more convenient and reasonable, and the positioning accuracy is high.

[0025] Since the data collection density is greater than the arrangement density of the physical hydrophone array during the ascent or descent of a single hydrophone, this solution reduces the amount of data processing and improves data accuracy by merging multiple collection values ​​into data collected by a virtual hydrophone.

[0026] Since the vertically moving hydrophone is insensitive to the Doppler effect, the signal collected over a period of time can be regarded as a stationary signal, and the entire sampling signal can be divided into N segments, which is regarded as synthesizing N virtual array elements.

[0027] Therefore, in some embodiments, a virtual hydrophone array simulation step is also included, in which each segment of the hydroacoustic signal is simulated as a signal collected by a virtual hydrophone at the current depth, and a virtual hydrophone array composed of N virtual hydrophones is obtained, and the frequency domain snapshots of each segment of the hydroacoustic signal are calculated, and all the frequency domain snapshots form a frequency domain snapshot matrix.

[0028] Since each hydroacoustic signal of each section is collected at different depths, when it is equivalent to a signal collected by a virtual hydrophone, the equivalent depth of the virtual hydrophone can be one of the depth values ​​of the hydroacoustic signals of the section, or it can be the average depth value of the hydroacoustic signals.

[0029] Since there is a time difference in the acquisition time of each section of the hydroacoustic signal, and the signals collected by the physical hydrophone array are collected by each hydrophone at the same time, it is necessary to perform time compensation on each section of the hydroacoustic signal so that the virtual hydrophone array can be closer to the real hydrophone array.

[0030] When locating the sound source underwater, the signal needs to be converted to the frequency domain for processing. If the signal is directly time-compensated in the time domain, the amount of calculation will increase when performing the frequency domain conversion. In order to reduce the amount of calculation, in this embodiment, the compensation of the signal in the time domain is converted into phase compensation in the frequency domain so that the signal can be complemented in time phase, including a frequency domain snapshot matrix compensation step for performing phase compensation on the frequency domain snapshot matrix in the frequency domain. This solution can reduce the amount of calculation by performing phase compensation on the signal frequency in the frequency domain. At the same time, the compensated signal can be aligned in time, and the virtual hydrophone array can be closer to the real hydrophone array.

[0031] In some embodiments, beam forming and angle estimation steps are also included, and the virtual hydrophone array is divided into multiple sub-arrays. The virtual hydrophones in the same sub-array are continuous in space. In the far-field environment in water, the sound signal emitted by the point sound source can be approximately regarded as parallel to the plane where the hydrophone is located. The vertically moving hydrophone is not sensitive to the Doppler phenomenon, so the sampling over a period of time (corresponding to one sub-array) can be regarded as a steady signal.

[0032] The direction angle of the sound source relative to each subarray is calculated according to the compensated frequency domain snapshot matrix to obtain several sets of depth-angle data, where the depth is the depth of each subarray and the angle is the direction angle of the sound source relative to each subarray.

[0033] like Figure 3 As shown, in the sound source localization step, the horizontal distance of the sound source relative to the virtual hydrophone array and the depth of the sound source are calculated according to the depth-angle data to complete the underwater target positioning.

[0034] By calculating the direction angle of the sound source relative to each sub-array and combining the geometric relationship, the horizontal distance of the sound source relative to the virtual hydrophone array and the sound source depth can be solved.

[0035] In some embodiments, in the virtual hydrophone array simulation step, the method for calculating the frequency domain snapshot matrix is: performing a K-point Fourier transform on each segment of the hydroacoustic signal. Since the signal source is usually a broadband signal, the lowest frequency of the transformed signal is , the highest frequency is , and There are M frequency values ​​between them, and the N-segment underwater acoustic signal corresponds to N×M frequency domain snapshots. The frequency domain snapshot matrix Y is expressed as: .

[0036] Since each virtual hydrophone in the virtual hydrophone array does not receive the signal at the same time, there is a certain delay between each virtual hydrophone, so it is necessary to calculate the frequency domain snapshot matrix Phase compensation is performed to make it equivalent to a large aperture array.

[0037] In some embodiments, the frequency domain snapshot matrix Y is also compensated. for:

[0038] ;

[0039] in, is the signal sampling rate, T is the sampling time of each section of the hydroacoustic signal, T=d / v, v is the speed of the hydrophone, and d is the spacing of the virtual hydrophone array, that is, the spacing between two adjacent virtual hydrophones in the virtual hydrophone array.

[0040] Calculate the compensation matrix and the frequency domain snapshot matrix The Hadamard product of is used as the compensated frequency domain snapshot matrix. The covariance matrix can be obtained by multiplying the frequency domain snapshot matrix by its conjugate transposed matrix, which is used for subsequent beamforming calculation to estimate the direction angle.

[0041] It should be noted that the length and number of signal segments should be determined according to specific needs and environment, and the size of the synthesized virtual aperture should also be adjusted accordingly based on factors such as the ocean environment, distance from the sound source, and sound frequency of the sound source.

[0042] The direction estimation of the target is achieved by using a beamforming algorithm. By performing weighting, time delay and other processing on an array of a certain geometric shape, it is possible to extract incoming signals from a specific direction and suppress signals from other directions. The beamformer can usually be regarded as a spatial filter. By continuously searching within a certain angle range, when the search angle is consistent with the actual incoming angle, the amplitude of the beam output reaches the maximum value, thereby determining the direction angle of the sound source to the receiving array.

[0043] In some embodiments, in the beamforming and angle estimation step, the same virtual hydrophone is divided into one of the subarrays or simultaneously divided into multiple subarrays, and the number of virtual hydrophones in each subarray is m. The beamforming and angle estimation step further includes:

[0044] Each virtual hydrophone in the subarray is an array element, and the array element at one end of the subarray is used as a reference array element.

[0045] Find the frequency domain snapshot sub-matrix corresponding to the sub-array from the compensated frequency domain snapshot matrix, and calculate the covariance matrix of the sub-matrix , for the search angle , construct beam output : ,in is the orientation vector, is an m-dimensional column vector, is the distance from each array element to the reference array element, is the frequency of the underwater acoustic signal, c is the signal propagation speed, and the calculation makes The search angle value corresponding to the maximum value is the direction angle of the sound source relative to the subarray.

[0046] For the virtual hydrophone array formed by the water acoustic signal collected by a single hydrophone moving at a uniform vertical speed, if the first array element is taken as the reference array element, the spacing between each array element is d, and since the far-field signal can be regarded as parallel incident, the phase shift of the Nth array element in the frequency domain compared to the reference array element is A, the signal propagation speed is c, and the incident angle is There is a certain time difference between the signals , which is reflected as a phase shift in the frequency domain .

[0047] On this basis, assuming that the virtual subarray is synthesized into m array elements, the covariance matrix calculated by the compensated frequency domain snapshot matrix is ​​recorded as , construct beam output ,when hour, Get the maximum value, from which the signal azimuth can be obtained.

[0048] In some embodiments, the search angle The value range is: -90°≤ ≤90°.

[0049] It should be noted that the length of the virtual subarray should be changed according to specific needs and environment. The principle to be followed is to choose a virtual hydrophone array with a longer length as much as possible while ensuring the consistency of time and space correlation.

[0050] Since the hydrophone is easily affected by ocean currents, waves, etc. during the ascent / sinking process, it is impossible to ensure that it floats completely vertically. It is necessary to compensate for the lateral offset of the virtual hydrophone array.

[0051] In some embodiments, the signal acquisition step also includes recording the horizontal displacement of the hydrophone during the process of floating or sinking. , and according to the horizontal offset Spatial phase compensation is performed on the virtual hydrophone array.

[0052] In some embodiments, the method for performing spatial phase compensation on the virtual hydrophone array includes:

[0053] The spatial phase difference generated by the hydrophone during the vertical movement is calculated according to the horizontal offset : .

[0054] Calculate the steering vector and The Hadamard product is calculated and the result is reassigned to the steering vector .

[0055] The beamforming and angle estimation steps use the reassigned steering vector Calculate the direction angle.

[0056] In some embodiments, an acceleration sensor is used in the signal collection step to record the horizontal displacement of the hydrophone during the process of floating or sinking.

[0057] Assuming that the horizontal offset collected by the position sensor compared to the synthesized virtual hydrophone array is x, and the far-field signal is still regarded as parallel incidence, the spatial phase compensation for the virtual hydrophone array is: ,in It is composed of the horizontal offset x of each virtual array element, and the original steering vector and The Hadamard product of is regarded as the compensated steering vector for beamforming calculation.

[0058] In some embodiments, the angle in the sound source localization step is represented by the tangent value of the directional angle, and the depth-angle data is fitted with a depth-angle linear relationship through the least squares method. The slope of the linear relationship is the horizontal distance of the sound source relative to the virtual hydrophone array. In the linear relationship, when the tangent value of the directional angle is 0, the corresponding depth is the depth of the sound source.

[0059] The angle in the sound source localization step is expressed by the tangent value of the directional angle. On the one hand, the estimated change of the angle θ during the buoyancy of the hydrophone is not linear, while the changes of tanθ and cotθ are linear. If other angles are used, the "angle-depth" graph will not show the shape of an oblique straight line, but will be obviously bent, and the slope cannot be calculated. On the other hand, according to the geometric relationship, tanθ can be directly used in the subsequent calculation of r=dz / dtanθ, so the tangent angle is used.

[0060] In some embodiments, a pressure sensor is used in the signal collection step to collect the depth of the hydrophone during its ascent or descent.

[0061] like Figure 4 As shown in the figure, a sound source with a frequency of 1kHz is located at a depth of 100m, 2km away from the detection position, and the speed of sound in water is 1500m / s. As the frequency f=1kHz, the spacing of the virtual hydrophone array should be less than or equal to f / 2c=1000 / 2*1500=0.75m, and 0.5m is selected here.

[0062] After the angles of virtual sub-arrays at different depths are estimated, an "angle-depth" graph is drawn with angle as the horizontal axis and depth as the vertical axis, and the angles corresponding to the virtual hydrophone arrays at each depth are recorded on the graph. Figure 5 As shown, after data compensation, a beamforming algorithm is performed on the compensated virtual hydrophone array to obtain an angle-depth map.

[0063] like Figure 6 As shown, the points recorded on the graph should be drawn as a straight line using the least squares method. According to the geometric relationship, if represents the angle, then the relationship between the horizontal distance of the sound source target and the depth and search angle of the virtual hydrophone array is: , that is, the slope of the straight line is equal to the horizontal distance of the sound source, and when The depth corresponding to the time, that is, the intercept of the straight line formed is numerically equal to the depth of the sound source in the water.

[0064] This principle can be understood more intuitively from the perspective of rays: the virtual sub-arrays at various depths can use the beamforming algorithm to obtain the target's azimuth information, and combined with the depth information of the virtual hydrophone array itself, the target position can be estimated.

[0065] Of course, the above description is not a limitation of the present invention, and the present invention is not limited to the above examples. Changes, modifications, additions or substitutions made by ordinary technicians in this technical field within the essential scope of the present invention should also fall within the protection scope of the present invention.

Claims

1. An underwater positioning method based on a single hydrophone, characterized in that: include: The signal collection step includes: controlling a single hydrophone to collect water acoustic signals during the process of floating up or sinking, obtaining a water acoustic signal sequence according to the collection time, and synchronously obtaining the depth information and position information of the hydrophone when collecting the water acoustic signal; The signal preprocessing step includes: calculating the spacing of the virtual hydrophone array according to the frequency of the hydroacoustic signal, and dividing the hydroacoustic signal sequence into N segments according to the spacing, wherein N is a positive integer; The virtual hydrophone array simulation step is to take each segment of the hydroacoustic signal as a signal collected by a virtual hydrophone at the current depth, obtain a virtual hydrophone array composed of N virtual hydrophones, calculate the frequency domain snapshot of each segment of the hydroacoustic signal, and all the frequency domain snapshots form a frequency domain snapshot matrix; A frequency domain snapshot matrix compensation step, performing phase compensation on the frequency domain snapshot matrix in the frequency domain; The beam forming and angle estimation step divides the virtual hydrophone array into a plurality of sub-arrays, wherein the virtual hydrophones in the same sub-array are continuous in space, and calculates the direction angle of the sound source relative to each of the sub-arrays according to the compensated frequency domain snapshot matrix to obtain a plurality of sets of depth-angle data; In the sound source localization step, the horizontal distance of the sound source relative to the virtual hydrophone array and the depth of the sound source are calculated based on the depth-angle data to complete the underwater target positioning.

2. The underwater positioning method based on a single hydrophone according to claim 1, characterized in that: In the virtual hydrophone array simulation step, the method for calculating the frequency domain snapshot matrix is: perform a K-point Fourier transform on each segment of the hydroacoustic signal, and the lowest frequency of the transformed signal is , the highest frequency is , and There are M frequency values ​​between them, and the N-segment underwater acoustic signal corresponds to N×M frequency domain snapshots. The frequency domain snapshot matrix Y is expressed as: 。 3. The underwater positioning method based on a single hydrophone according to claim 2, characterized in that: It also includes compensating the frequency domain snapshot matrix Y, the compensation matrix for: ； in, is the signal sampling rate, T is the sampling time of each section of the hydroacoustic signal, T=d / v, v is the speed of the hydrophone, and d is the spacing of the virtual hydrophone array; Calculate the compensation matrix and the frequency domain snapshot matrix The Hadamard product of is used as the compensated frequency domain snapshot matrix.

4. The underwater positioning method based on a single hydrophone according to claim 3, characterized in that: In the beamforming and angle estimation step, the same virtual hydrophone is divided into one of the subarrays or simultaneously divided into multiple subarrays, and the number of virtual hydrophones in each subarray is m. The beamforming and angle estimation step further includes: Each virtual hydrophone in the subarray is an array element, and the array element at one end of the subarray is used as a reference array element; Find the frequency domain snapshot sub-matrix corresponding to the sub-array from the compensated frequency domain snapshot matrix, and calculate the covariance matrix of the sub-matrix , for the search angle , construct beam output : ,in is the orientation vector, is an m-dimensional column vector, is the distance from each array element to the reference array element, is the frequency of the underwater acoustic signal, c is the signal propagation speed, and the calculation makes The search angle value corresponding to the maximum value is the direction angle of the sound source relative to the subarray.

5. The underwater positioning method based on a single hydrophone according to claim 4, characterized in that: The value range is: -90°≤ ≤90°.

6. The underwater positioning method based on a single hydrophone according to claim 4, characterized in that: The signal acquisition step also includes recording the horizontal displacement of the hydrophone during its ascent or descent. , and according to the horizontal offset Spatial phase compensation is performed on the virtual hydrophone array.

7. The underwater positioning method based on a single hydrophone according to claim 6, characterized in that: The method for performing spatial phase compensation on the virtual hydrophone array comprises: The spatial phase difference generated by the hydrophone during the vertical movement is calculated according to the horizontal offset : ; Calculate the steering vector and The Hadamard product is calculated and the result is reassigned to the steering vector ; The beamforming and angle estimation steps use the reassigned steering vector Calculate the direction angle.

8. The underwater positioning method based on a single hydrophone according to claim 6, characterized in that: In the signal acquisition step, an acceleration sensor is used to record the horizontal displacement of the hydrophone during the process of floating or sinking.

9. The underwater positioning method based on a single hydrophone according to any one of claims 1 to 8, characterized in that: The angle in the sound source localization step is represented by the tangent value of the directional angle. The depth-angle data is fitted into a linear relationship of depth-angle by the least squares method. The slope of the linear relationship is the horizontal distance of the sound source relative to the virtual hydrophone array. In the linear relationship, when the tangent value of the directional angle is 0, the corresponding depth is the depth of the sound source.

10. The underwater positioning method based on a single hydrophone according to any one of claims 1 to 8, characterized in that: In the signal acquisition step, a pressure sensor is used to collect the depth of the hydrophone during its ascent or descent.

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