An autonomous underwater target resolution and depth estimation method based on deep sea vertical array

Abstract

The application discloses a kind of underwater target autonomous resolution and depth estimation method based on deep sea vertical array, the method includes: step 1) according to vertical hydrophone array correlation parameter, utilize sound field calculation software simulation receiving sound field under different depths;Step 2) Fourier transform and beam forming processing are carried out to the time-domain sound field actually collected by vertical hydrophone array, and it is specified to multiple sub-band range, then the pre-calculated target navigation track is matched with the measured sound field transformed into beam-time domain, and the frequency of line spectrum is estimated using one-dimensional signal peak estimation algorithm, to obtain target track sound field;Step 3) the simulated receiving sound field and target track sound field under different depths are correlated, and the autonomous resolution and depth estimation of surface underwater target are realized.

Description

Technical Field

[0001] This invention belongs to the field of underwater acoustic physics technology, and in particular relates to a method for autonomous underwater target resolution and depth estimation based on a deep-sea vertical array. Background Technology

[0002] Acquiring underwater target depth information is a key criterion for distinguishing underwater targets from surface targets, and has always been a focus and challenge in underwater acoustics. Traditional matched-field processing target localization methods correlate simulated copy sound field data with actual measured underwater acoustic data to determine the target's distance and depth through fuzzy surfaces of distance and depth. For deep-sea underwater targets, in complex background noise environments, target depth information is also an important feature for identifying the target's line spectrum. Due to the influence of deep-sea waveguides and typical deep-sea hydrological distribution, the spatiotemporal distribution of the deep-sea sound field differs significantly from that of shallow seas. Hydrophones deployed near the seabed can receive sound fields with low propagation loss excited by underwater targets within a medium distance. The receiving sound field interference structure is extremely sensitive to target depth information and can be used to estimate the target depth. Combining the background noise characteristics of the underwater acoustic environment, extracting the line spectrum features of underwater targets based on the coupled sound field characteristics of the underwater acoustic target-environment is more advantageous in actual marine environments and is also a prerequisite for solving the urgent need for autonomous detection and differentiation of surface and underwater acoustic targets in deep-sea environments. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of the existing technology and propose an autonomous underwater target resolution and depth estimation method based on a deep-sea vertical array.

[0004] To achieve the above objectives, this invention proposes an autonomous underwater target resolution and depth estimation method based on a deep-sea vertical array, the method comprising:

[0005] Step 1) Based on the relevant parameters of the vertical hydrophone array, use sound field calculation software to simulate the received sound field at different depths;

[0006] Step 2) Perform Fourier transform and beamforming processing on the actual time-domain sound field acquired by the vertical hydrophone array, normalize it to multiple sub-frequency bands, and then match the pre-calculated target navigation trajectory with the measured sound field transformed into the beam-time domain. Use a one-dimensional signal peak estimation algorithm to estimate the frequency of the line spectrum and obtain the target trajectory sound field.

[0007] Step 3) Perform relevant processing on the simulated received sound field and target trajectory sound field at different depths to achieve autonomous discrimination and depth estimation of targets on the water surface and underwater.

[0008] As an improvement to the above method, the vertical hydrophone in step 1) is an N-element uniformly distributed vertical linear array with an element spacing of d.

[0009] As an improvement to the above method, step 1) specifically includes:

[0010] The vertical linear array at different receiving depths z was obtained using sound field calculation software. n Frequency domain simulation signal P Sim (f,z n ), f represents frequency; by N f Frequency domain simulation signal P with one frequency and N array elements Sim (f,z n The simulated receiver sound field matrix P is composed of... Sim (f,z n );

[0011] Based on the depth z of the vertical linear array r The average speed of sound in seawater c(z) r The guiding vector w(f,θ) of the pointing angle θ of the vertical line array is obtained from the following formula:

[0012]

[0013] Where f is the frequency, θ is the pointing angle, d is the element spacing of the vertical line array, and T represents transpose;

[0014] This will simultaneously form directions pointing to θ1, θ2, ..., θ L The L beams constitute the steering vector matrix A(f):

[0015] A(f,θ)=[w(f,θ1),w(f,θ2),…,w(f,θ L )]

[0016] The simulated received sound field matrix P Sim (f,z n The simulated beam response matrix B for frequency-grazing angle is obtained from the steering vector matrix A(f,θ) and the steering vector matrix A(f,θ). Sim (f,θ) is:

[0017] B Sim (f,θ)=|P Sim (f,z n A(f,θ)| 2

[0018] Among them, the simulated beam response matrix B Sim The magnitude of (f,θ) is N f ×N θ N θ It represents the number of sweep angles;

[0019] Based on the target frequency value Total N fEach frequency point; the target depth is taken as... Total N d Target depth points, receiving distance is Total N r Given N receiving distance points, calculate N. d Target depth points and N r Simulated beam response matrix B at each receiving distance point Sim (f,θ,d,r);

[0020] Take the simulated beam response matrix B at different receiving distance points Sim The maximum values ​​of (f, θ, d, r) form the copy beam response matrix B. copy (f,θ,d) is:

[0021]

[0022] As an improvement to the above method, step 2) specifically includes:

[0023] Step 2-1) Perform Fourier transform and beamforming processing on the actual time-domain sound field acquired by the vertical hydrophone array to obtain the measured beam response matrix;

[0024] Step 2-2) Normalize the measured beam response matrix to multiple sub-bands, match the pre-calculated target trajectory with the measured sound field transformed into the beam-time domain, estimate the frequency of the line spectrum using a one-dimensional signal peak estimation algorithm, and obtain the line spectrum frequency, speed and horizontal distance of the target, thereby obtaining the beam response matrix along the target trajectory.

[0025] As an improvement to the above method, step 2-1) specifically includes:

[0026] Time-domain signal p(t,z) acquired from vertical waterline array n Perform a Fast Fourier Transform to obtain the frequency domain signal P(f,z). n ):

[0027]

[0028] Where f represents frequency, t represents time, and z n Indicates the signal amplitude;

[0029] By N f A frequency domain signal P(f,z) with N frequencies and N array elements n The measured received sound field matrix P(f,z) is composed of... n );

[0030] According to the received sound field matrix P(f,z) nThe steering vector matrix A(f,θ) obtained in step 1) and step 2) are used to obtain the measured beam response matrix B(f,θ) of frequency-grazing angle by the following formula:

[0031] B(f,θ)=|P(f,z n A(f,θ)| 2 ,

[0032] The measured beam response matrix B(f,θ) has a size of N. f ×N θ N θ It represents the number of grazing angles.

[0033] As an improvement to the above method, step 2-2) specifically includes:

[0034] The measured beam response matrix B(f,θ) is normalized to a certain frequency band using a downsampling method, resulting in B′(f) n ,θ m The standardized beam response matrix B′(f,θ) is composed of , where the frequency band of the matrix is ​​the range of equally spaced frequency points. f n+1 -f n =Δf, B′(f) n ,θ m ) is (f n -Δf<f i <f n B(f) frequency band +Δf) i ,θ m The maximum value of )

[0035]

[0036] With time interval Δt, Δt = t n+1 -t n ,Will Total N t The standardized beam response matrices B′(f,θ) at each time step form a three-dimensional beam response matrix S(f,θ,t), where the elements of the three-dimensional beam response matrix are...

[0037] Based on the depth z of the vertical linear array r The average speed of sound in seawater c(z) r The depth z of the target to be measured s The average speed of sound in seawater c(z) s The glancing angle θ of the sound ray at the vertical line array. r The sound speed profile c(z) is obtained from the following formula, which gives the horizontal propagation distance r(θ) of the intrinsic sound ray. r )for:

[0038]

[0039] Then we can obtain the corresponding θ r Different values ​​of θ1, θ2, ..., θ L The corresponding horizontal propagation distances are r1(θ1), r2(θ2), ..., r L (θ L );

[0040] Based on the nearest distance r between the target and the position of the vertical linear array min Given the speed v and the horizontal distance R between the target and the nearest point on the flight path at the current time t1, the horizontal projected distance r between the target and the vertical line array is obtained by the following formula. sr for:

[0041]

[0042] According to r(θ) r Combining this with the above formula, we obtain the grazing angle θ of the vertical linear array. r The correspondence between time t and time t is as follows:

[0043]

[0044] Therefore, a two-dimensional curve is plotted, within the set parameter range of v, R, r. min Assign values ​​and calculate the trajectory energy under different assignments to obtain the frequency f. i The maximum trajectory energy E(f) at time i )for:

[0045]

[0046] For frequency range Total N f The frequencies of the underwater acoustic target line spectrum at each frequency point are used to determine the frequency f at a given frequency point. i energy If the following formula is satisfied, then the frequency point f is determined. i Target line spectrum frequency:

[0047]

[0048] Where E0 is the preset detection threshold;

[0049] The speed of the target is obtained by taking the parameter of the maximum trajectory energy corresponding to the target's line spectrum frequency. The closest distance to the location of the receiving array Combining the horizontal projection distance r between the target and the vertical linear array sr The formula yields the grazing angle θ of the receiver array depth. rThe target trajectory determined by time t for:

[0050]

[0051] As an improvement to the above method, step 3) specifically includes:

[0052] Based on the three-dimensional beam response matrix S(f,θ,t) and the target trajectory The beam response B along the trajectory of the target to be measured is obtained. real (t) is:

[0053]

[0054] According to the copy beam response matrix B copy (θ,d) and the target trajectory The beam response output B of the copy motion trajectory at different target depths is obtained. copy1 (t,d) is:

[0055]

[0056] In the formula, the range of values ​​for the target depth d is: The range of values ​​for time t is

[0057] The correlation coefficient corr(d) between the beam response along the trajectory of the target under test and the beam response output of the copied trajectory at different target depths is calculated by the following formula:

[0058]

[0059] In the formula, B real (t i ) indicates that the received data is at t i The beam response along the trajectory of the target at time B copy1 (t i ,d) represents the simulation data at depth d,t i Beam response output of the copy motion trajectory at any given time. Indicates time B within the range real (t i The mean of ) This indicates that at a depth of d, time B within the range copy1 (t i The mean of ,d);

[0060] Let d be the depth corresponding to the maximum correlation coefficient at different sound source depths. max And make the following judgment: if dmax >d surface And d max The corresponding correlation coefficient corr(d) max If the value is greater than 0.5, the target to be detected is determined to be an underwater target, and the estimated depth is d. max Otherwise, it is a surface target; where d surface The set depth for distinguishing underwater and surface targets.

[0061] An autonomous underwater target resolution and depth estimation system based on a deep-sea vertical array, the system comprising: a receiving sound field simulation module, a target trajectory sound field generation module, and a correlation processing and judgment module; wherein...

[0062] The receiving sound field simulation module is used to simulate the receiving sound field at different depths using sound field calculation software based on the relevant parameters of the vertical hydrophone array.

[0063] The target trajectory sound field generation module is used to perform Fourier transform and beamforming processing on the time-domain sound field actually acquired by the vertical hydrophone array, and normalize it to multiple sub-frequency bands. Then, the pre-calculated target navigation trajectory is matched with the measured sound field transformed into the beam-time domain. The frequency of the line spectrum is estimated using a one-dimensional signal peak estimation algorithm to obtain the target trajectory sound field.

[0064] The related processing and judgment module is used to perform related processing on the received sound field and target trajectory sound field simulated at different depths, so as to realize the autonomous discrimination and depth estimation of targets on the water surface and underwater.

[0065] Compared with the prior art, the advantages of the present invention are:

[0066] 1. The method of this invention enables autonomous estimation of the depth of underwater acoustic targets with line spectra by using pre-calculated simulated sound field data;

[0067] 2. The method of this invention enables autonomous differentiation between surface and underwater targets by matching energy and estimating depth;

[0068] 3. The method of this invention processes long-term data, resulting in high processing gain and more robust performance in autonomously distinguishing surface and underwater targets and estimating target depth.

[0069] 4. The method of this invention uses beamforming and maximum value extraction to form a copy beam response matrix from the pre-calculated simulated sound field data, which requires less storage space. Attached Figure Description

[0070] Figure 1 This is a schematic diagram of the underwater target's trajectory and the position of the vertical array;

[0071] Figure 2This is the result of underwater target line spectrum frequency estimation;

[0072] Figure 3 It is the correlation coefficient between the beam response output of the measured target trajectory at a frequency of 105Hz and the beam response output of the copied motion trajectory at different target depths;

[0073] Figure 4 It is the correlation coefficient between the beam response output of the measured target trajectory at a frequency of 126Hz and the beam response output of the copied motion trajectory at different target depths;

[0074] Figure 5 This is the result of estimating the line spectrum frequency of the target on the water surface;

[0075] Figure 6 It is the correlation coefficient between the beam response output of the measured target trajectory at a frequency of 90Hz and the beam response output of the copied motion trajectory at different target depths;

[0076] Figure 7 It is the correlation coefficient between the beam response output of the measured target trajectory at a frequency of 147Hz and the beam response output of the copied motion trajectory at different target depths. Detailed Implementation

[0077] The purpose of this invention is to use a vertical array detection system to autonomously detect and identify underwater targets with line spectrum characteristics, and to perform relevant processing based on the detected target sound field and simulated sound field to estimate the target depth, thereby achieving autonomous resolution and depth estimation of surface and underwater targets.

[0078] The technical solution of the present invention will be described in detail below with reference to the accompanying drawings and embodiments.

[0079] Example 1

[0080] This invention presents a method for estimating target depth using a vertical array detection system. First, the received sound field at different depths is simulated using sound field calculation software and environmental parameters. Then, the time-domain sound field measured by the vertical hydrophone array is processed by Fourier transform and beamforming and normalized to multiple sub-frequency bands. Next, the pre-calculated target trajectory is matched with the measured sound field transformed into the beam-time domain. Then, the frequency of the line spectrum is estimated using a one-dimensional signal peak estimation algorithm to obtain the target trajectory sound field. Finally, the depth of the target is obtained by correlation processing using the simulated sound field at different depths.

[0081] The method includes:

[0082] Step 1) Based on the relevant parameters of the vertical hydrophone array, use sound field calculation software to simulate the received sound field at different depths;

[0083] Step 2) Perform Fourier transform and beamforming processing on the actual time-domain sound field acquired by the vertical hydrophone array, normalize it to multiple sub-frequency bands, and then match the pre-calculated target navigation trajectory with the measured sound field transformed into the beam-time domain. Use a one-dimensional signal peak estimation algorithm to estimate the frequency of the line spectrum and obtain the target trajectory sound field.

[0084] Step 3) Perform correlation processing on the simulated received sound field and target trajectory sound field at different depths to achieve autonomous resolution and depth estimation of surface and underwater targets.

[0085] The specific technical solution is as follows:

[0086] Step 1:

[0087] Take the depth z of the receiving array r The average speed of sound in seawater is c(z). r For an N-element uniformly distributed vertical linear array with element spacing d, the guiding vector w(f,θ) is:

[0088]

[0089] f is the frequency point, and θ is the pointing angle. This will simultaneously form directions θ1, θ2, ..., θ L The L beams constitute the steering vector matrix A(f):

[0090] A(f,θ)=[w(f,θ1),w(f,θ2),…,w(f,θ L (2)

[0091] The beam response matrix B(f,θ) of frequency-grazing angle is:

[0092] B(f,θ)=|P(f,z n A(f,θ)| 2 (3)

[0093] Wherein, matrix P(f,z) n ) is N f Frequency domain simulation of the sound pressure field P(f,z) with N frequencies and N array elements n The sound field matrix is ​​composed of N, and the size of matrix B(f,θ) is N. f ×N θ N θ This refers to the number of grazing angles. The target frequency is set to... Total N f Each frequency point; the target depth is taken as... Total N d Target depth points; receiving distance is Total N r There are N receiving distance points. Calculate N. dTarget depth points and N r The beam response matrix B(f,θ,d,r) at each receiving distance point.

[0094] The copy beam response matrix B is formed by taking the maximum value of the beam response matrix at different receiving distance points. copy (θ,d)

[0095]

[0096] Step Two:

[0097] The following Fast Fourier Transform is used to transform the time-domain signal p(t,z) received by the vertical hydrophone array. n Transformed to the frequency domain P(f,z) n ),

[0098]

[0099] Take the depth z of the receiving array r The average speed of sound in seawater is c(z). r For an N-element uniformly distributed vertical linear array with element spacing d, the beam response matrix B(f,θ) of the frequency-grazing angle can also be obtained according to formulas (1) and (2):

[0100] B(f,θ)=|P(f,z n A(f,θ)| 2 (6)

[0101] Wherein, matrix P(f,z) n P(f,z) is the received sound field with F frequencies and N array elements. n The sound field matrix is ​​composed of F×N, and the matrix B(f,θ) has a size of F×N. θ N θ It represents the number of grazing angles.

[0102] Then, the matrix B(f,θ) is normalized to a certain frequency band using a downsampling method, with the frequency band consisting of equally spaced frequency points. f n+1 -f n =Δf, (n = 1, 2, ..., N) f -1), the newly obtained matrix B′(f,θ) is derived from B′(f n ,θ m A matrix composed of ) . Where, B′(f n ,θ m )satisfy,

[0103]

[0104] That is, B′(f n,θ m Take (f) n -Δf<f i <f n B(f) frequency band +Δf) i ,θ m The maximum value of ).

[0105] With time interval Δt, t n+1 -t n =Δt, total N t The matrices B′(f,θ) at each time step form a three-dimensional matrix S(f,θ,t), where

[0106]

[0107] Typically, the horizontal propagation distance of the intrinsic sound rays can be calculated from a given grazing angle at the target.

[0108]

[0109] In the formula, θ r Let z be the grazing angle of the sound ray at the receiving array. s and z r Let θ be the target depth and the receiving depth, respectively, and c(z) be the sound speed distribution with depth, i.e., the sound speed profile. Then assume θ r The values ​​are θ1, θ2, ..., θ L The corresponding horizontal propagation distances r1, r2, ..., r can be obtained through numerical calculation. L .

[0110] Assume the target is moving at a constant velocity in a straight line, and the closest distance to the receiving array is r. min The target's speed is v, the current time is t1, and the horizontal distance between the target's current position and the nearest point on the course is R. The horizontal projection distance r between the underwater target and the vertical array is... sr It can be represented as

[0111]

[0112] Then, based on the propagation distance r and the grazing angle θ of the receiver array depth... r The correspondence between them can be used to obtain the grazing angle θ of the receiving array depth using the above formula. r Correspondence with time t Let v be a two-dimensional curve on a two-dimensional image, where v, R, r min This is the parameter to be assigned a value. Within a certain parameter range, it is v, R, or r. min Assigning values, for example: 0 < v < 20, -10km < R < 10km, 0km ≤ r min<10km. Therefore, by calculating the trajectory energy under different parameter values ​​within the parameter range, the frequency f can be obtained. i The maximum trajectory energy E(f) at time i )

[0113]

[0114] The frequency range to be determined is Total N f The frequency of the underwater acoustic target line spectrum at each frequency point, if that frequency point f i energy The following relationship must be satisfied:

[0115]

[0116] E0 is the detection threshold, which can be set based on experimental data processing experience, and should generally be greater than 3 dB. If the frequency point... If formula (10) is satisfied, then the frequency point The output target line spectrum frequency provides the parameter for obtaining the maximum trajectory energy at that frequency. The horizontal distance between the current target position and the nearest point on the flight path is... The closest distance to the receiving array position is Target speed is By assigning the obtained parameters to formula (10), the grazing angle θ of the receiver array depth can be obtained. r The target trajectory determined by time t

[0117] Step 3:

[0118] Based on formula (8), the measured acoustic beam response matrix S(f,θ,t) and the target trajectory are obtained. The beam response output B of the measured target trajectory is obtained. real (t)

[0119]

[0120] Copy the beam response matrix B according to formula (4). copy (θ,d) and the target trajectory The beam response output B of the copy motion trajectory at different target depths is obtained. copy1 (t,d)

[0121]

[0122] In the formula, the target depth d takes values ​​ranging from 1 to 10. The range of values ​​for time t is The correlation coefficient between the beam response output of the measured target trajectory and the beam response output of the copied motion trajectory at different target depths is calculated using formulas (13) and (14).

[0123]

[0124] In the formula, and They represent time. The average value is taken within the range. The depth corresponding to the maximum correlation coefficient at different sound source depths is taken as d. max The following conditions are given as criteria for distinguishing underwater sound sources from surface sound sources.

[0125]

[0126] In the formula d surface This method defines the boundary depth between underwater and surface targets. When a target is determined to be underwater using formula (16), the estimated depth of the underwater target is d. max .

[0127] Example 2

[0128] Embodiment 2 of the present invention proposes an autonomous underwater target resolution and depth estimation system based on a deep-sea vertical array, implemented based on the method of Embodiment 1. The system includes: a receiving sound field simulation module, a target trajectory sound field generation module, and a correlation processing and judgment module; wherein,

[0129] The receiving sound field simulation module is used to simulate the receiving sound field at different depths using sound field calculation software based on the relevant parameters of the vertical hydrophone array.

[0130] The target trajectory sound field generation module is used to perform Fourier transform and beamforming processing on the time-domain sound field actually acquired by the vertical hydrophone array, and normalize it to multiple sub-frequency bands. Then, the pre-calculated target navigation trajectory is matched with the measured sound field transformed into the beam-time domain. The frequency of the line spectrum is estimated using a one-dimensional signal peak estimation algorithm to obtain the target trajectory sound field.

[0131] The related processing and judgment module is used to perform related processing on the received sound field and target trajectory sound field simulated at different depths, so as to realize the autonomous discrimination and depth estimation of targets on the water surface and underwater.

[0132] Simulation Examples

[0133] Figure 1 Let r be the target's trajectory and the vertical array position. Assume the target's motion is uniform linear motion, and the closest distance to the receiving array position is r. min=r0, the target speed is v, the current time is t1, and the horizontal distance between the target position and the nearest point on the route at the current time is R.

[0134] Figure 2 The maximum trajectory energy E(f) of the target calculated from underwater target data. i The frequency range is 50Hz-150Hz. According to formula (10), let E0 = 5dB, the target characteristic spectrum frequencies can be estimated to be 105Hz and 126Hz.

[0135] Figure 3 Let d be the correlation coefficient between the beam response output of the measured target trajectory calculated by formula (15) at f = 105 Hz and the beam response output of the copied motion trajectory at different target depths. The depth corresponding to the maximum value of the correlation coefficient is d. max =100 meters, take d surface =20, satisfying d max >d surface And corr(d) max If the value is greater than 0.5, it can be determined that the target is underwater according to formula (16), and the target depth is 100 meters.

[0136] Figure 4 Let d be the correlation coefficient between the beam response output of the measured target trajectory calculated by formula (15) at f = 126 Hz and the beam response output of the copied motion trajectory at different target depths. The depth corresponding to the maximum value of the correlation coefficient is d. max =99 meters, take d surface =20, satisfying d max >d surface And corr(d) max If the value is greater than 0.5, it can be determined that the target is underwater according to formula (16), and the target depth is 99 meters.

[0137] Figure 5 The maximum trajectory energy E(f) of the target is calculated based on the surface target data. i The frequency range is 50Hz-150Hz. According to formula (10), let E0 = 5dB, the target characteristic spectrum frequencies can be estimated to be 90Hz and 147Hz.

[0138] Figure 6 Let be the correlation coefficient between the beam response output of the measured target trajectory calculated by formula (15) at f = 90Hz and the beam response output of the copied motion trajectory at different target depths. The depth corresponding to the maximum value of the correlation coefficient is d. max =9 meters, take d surface =20, which does not satisfy d max >d surface And corr(d) maxIf the value is greater than 0.5, it can be determined that the target is a surface water target with a depth of 9 meters according to formula (16).

[0139] Figure 7 Let d be the correlation coefficient between the beam response output of the measured target trajectory calculated by formula (15) at f = 147 Hz and the beam response output of the copied motion trajectory at different target depths. The depth corresponding to the maximum value of the correlation coefficient is d. max =11 meters, take d surface =20, which does not satisfy d max >d surface And corr(d) max If the value is greater than 0.5, it can be determined that the target is underwater according to formula (16), and the target depth is 11 meters.

[0140] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to the embodiments, those skilled in the art should understand that modifications or equivalent substitutions to the technical solutions of the present invention do not depart from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for autonomous underwater target resolution and depth estimation based on a deep-sea vertical array, the method comprising: Step 1) Based on the relevant parameters of the vertical hydrophone array, use sound field calculation software to simulate the received sound field at different depths; Step 2) Perform Fourier transform and beamforming processing on the actual time-domain sound field acquired by the vertical hydrophone array, normalize it to multiple sub-frequency bands, and then match the pre-calculated target navigation trajectory with the measured sound field transformed into the beam-time domain. Use a one-dimensional signal peak estimation algorithm to estimate the frequency of the line spectrum and obtain the target trajectory sound field. Step 3) Perform relevant processing on the simulated received sound field and target trajectory sound field at different depths to achieve autonomous resolution and depth estimation of surface and underwater targets; Step 1) specifically includes: The vertical linear array at different receiving depths z was obtained using sound field calculation software. n Frequency domain simulation signal P Sim (f,z n ), f represents frequency; by N f Frequency domain simulation signal P with one frequency and N array elements Sim (f,z n The simulated receiver sound field matrix P is composed of... Sim (f,z n ); Based on the depth z of the vertical linear array r The average speed of sound in seawater c(z) r The guiding vector w(f,θ) of the pointing angle θ of the vertical line array is obtained from the following formula: Where f is the frequency, θ is the pointing angle, d is the element spacing of the vertical line array, and T represents transpose; This will simultaneously form directions pointing to θ1, θ2, ..., θ L The L beams constitute the steering vector matrix A(f): A(f,θ)=[w(f,θ1),w(f,θ2),…,w(f,θ L )] The simulated received sound field matrix P Sim (f,z n The simulated beam response matrix B for frequency-grazing angle is obtained from the steering vector matrix A(f,θ) and the steering vector matrix A(f,θ). Sim (f,θ) is: B Sim (f,θ)=|P Sim (f,z n )A(f,θ)| 2 Among them, the simulated beam response matrix B Sim The magnitude of (f,θ) is N f ×N θ N θ It represents the number of sweep angles; Based on the target frequency value Total N f Each frequency point; the target depth is taken as... Total N d Target depth points, receiving distance is Total N r Given N receiving distance points, calculate N. d Target depth points and N r Simulated beam response matrix B at each receiving distance point Sim (f,θ,d,r); Take the simulated beam response matrix B at different receiving distance points Sim The maximum values ​​of (f, θ, d, r) form the copy beam response matrix B. copy (f,θ,d) is: Step 2) specifically includes: Step 2-1) Perform Fourier transform and beamforming processing on the actual time-domain sound field acquired by the vertical hydrophone array to obtain the measured beam response matrix; Step 2-2) Normalize the measured beam response matrix to multiple sub-bands, match the pre-calculated target trajectory with the measured sound field transformed into the beam-time domain, estimate the frequency of the line spectrum using a one-dimensional signal peak estimation algorithm, and obtain the line spectrum frequency, speed and horizontal distance of the target, thereby obtaining the beam response matrix along the target trajectory.

2. The method for autonomous underwater target resolution and depth estimation based on a deep-sea vertical array according to claim 1, characterized in that, The vertical hydrophone in step 1) is an N-element uniformly distributed vertical linear array with an element spacing of d.

3. The method for autonomous underwater target resolution and depth estimation based on a deep-sea vertical array according to claim 1, characterized in that, Step 2-1) specifically includes: Time-domain signal p(t,z) acquired from vertical waterline array n Perform a Fast Fourier Transform to obtain the frequency domain signal P(f,z). n ): Where f represents frequency, t represents time, and z n Indicates the signal amplitude; By N f A frequency domain signal P(f,z) with N frequencies and N array elements n The measured received sound field matrix P(f,z) is composed of... n ); According to the received sound field matrix P(f,z) n The steering vector matrix A(f,θ) obtained in step 1) and step 2) are used to obtain the measured beam response matrix B(f,θ) of frequency-grazing angle by the following formula: B(f,θ)=|P(f,z n )A(f,θ)| 2 , The measured beam response matrix B(f,θ) has a size of N. f ×N θ N θ It represents the number of grazing angles.

4. The method for autonomous underwater target resolution and depth estimation based on a deep-sea vertical array according to claim 3, characterized in that, Step 2-2) specifically includes: The measured beam response matrix B(f,θ) is normalized to a certain frequency band using a downsampling method, resulting in B′(f) n ,θ m The standardized beam response matrix B′(f,θ) is composed of , where the frequency band of the matrix is ​​the range of equally spaced frequency points. f n+1 -f n =Δf, B′(f) n ,θ m ) is (f n -Δf<f i <f n B(f) frequency band +Δf) i ,θ m The maximum value of ) With time interval Δt, Δt = t n+1 -t n ,Will Total N t The standardized beam response matrices B′(f,θ) at each time step form a three-dimensional beam response matrix S(f,θ,t), where the elements of the three-dimensional beam response matrix are... Based on the depth z of the vertical linear array r The average speed of sound in seawater c(z) r The depth z of the target to be measured s The average speed of sound in seawater c(z) s The glancing angle θ of the sound ray at the vertical line array. r The sound speed profile c(z) is obtained from the following formula, which gives the horizontal propagation distance r(θ) of the intrinsic sound ray. r )for: Then we can obtain the corresponding θ r Different values ​​of θ1, θ2, ..., θ L The corresponding horizontal propagation distances are r1(θ1), r2(θ2), ..., r L (θ L ); Based on the nearest distance r between the target and the position of the vertical linear array min Given the speed v and the horizontal distance R between the target and the nearest point on the flight path at the current time t1, the horizontal projected distance r between the target and the vertical line array is obtained by the following formula. sr for: According to r(θ) r Combining this with the above formula, we obtain the grazing angle θ of the vertical linear array. r The correspondence between time t and time t is as follows: Therefore, a two-dimensional curve is plotted, within the set parameter range of v, R, r. min Assign values ​​and calculate the trajectory energy under different assignments to obtain the frequency f. i The maximum trajectory energy E(f) at time i )for: For frequency range Total N f The frequencies of the underwater acoustic target line spectrum at each frequency point are used to determine the frequency f at a given frequency point. i energy If the following formula is satisfied, then the frequency point f is determined. i Target line spectrum frequency: Where E0 is the preset detection threshold; The speed of the target is obtained by taking the parameter of the maximum trajectory energy corresponding to the target's line spectrum frequency. The closest distance to the location of the receiving array Combining the horizontal projection distance r between the target and the vertical linear array sr The formula yields the grazing angle θ of the receiver array depth. r The target trajectory determined by time t for:

5. The method for autonomous underwater target resolution and depth estimation based on a deep-sea vertical array according to claim 4, characterized in that, Step 3) specifically includes: Based on the three-dimensional beam response matrix S(f,θ,t) and the target trajectory The beam response B along the trajectory of the target to be measured is obtained. real (t) is: According to the copy beam response matrix B copy (θ,d) and the target trajectory The beam response output B of the copy motion trajectory at different target depths is obtained. copy1 (t,d) is: In the formula, the range of values ​​for the target depth d is: The range of values ​​for time t is The correlation coefficient corr(d) between the beam response along the trajectory of the target under test and the beam response output of the copied trajectory at different target depths is calculated by the following formula: In the formula, B real (t i ) indicates that the received data is at t i The beam response along the trajectory of the target at time B copy1 (t i ,d) represents the simulation data at depth d,t i Beam response output of the copy motion trajectory at any given time. Indicates time B within the range real (t i The mean of ) This indicates that at a depth of d, time B within the range copy1 (t i The mean of ,d); Let d be the depth corresponding to the maximum correlation coefficient at different sound source depths. max And make the following judgment: if d max >d surface And d max The corresponding correlation coefficient corr(d) max If the value is greater than 0.5, the target to be detected is determined to be an underwater target, and the estimated depth is d. max Otherwise, it is a surface target; where d surface The set depth for distinguishing underwater and surface targets.

6. A system for autonomous underwater target resolution and depth estimation based on the deep-sea vertical array described in claim 1, characterized in that, The system includes: a sound field simulation module, a target trajectory sound field generation module, and a related processing and judgment module; wherein... The receiving sound field simulation module is used to simulate the receiving sound field at different depths using sound field calculation software based on the relevant parameters of the vertical hydrophone array. The target trajectory sound field generation module is used to perform Fourier transform and beamforming processing on the time-domain sound field actually acquired by the vertical hydrophone array, and normalize it to multiple sub-frequency bands. Then, the pre-calculated target navigation trajectory is matched with the measured sound field transformed into the beam-time domain. The frequency of the line spectrum is estimated using a one-dimensional signal peak estimation algorithm to obtain the target trajectory sound field. The related processing and judgment module is used to perform related processing on the received sound field and target trajectory sound field simulated at different depths, so as to realize the autonomous discrimination and depth estimation of targets on the water surface and underwater.

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