A passive sound source localization method and system based on vertical array in deep-sea environment

Abstract

This invention relates to the fields of underwater acoustic engineering, marine engineering, and sonar technology, and particularly to a passive sound source localization method and system based on a vertical array in a deep-sea environment. The method includes: receiving the time-domain signal radiated by a target sound source using a large-aperture vertical array deployed on the seabed in the deep sea; performing a fast Fourier transform on the time-domain signal to obtain the corresponding signal spectrum; using a spatial power spectrum estimation method to obtain the frequency-domain beam output sound field of the signal spectrum of different array elements at different angles of arrival; calculating template values ​​for the direct wave angle of arrival, the sea surface reflected wave angle of arrival, the direct wave arrival time delay, and the sea surface reflected wave arrival time delay under different assumed sound source distances and depths; combining the four template values ​​with the frequency-domain beam output sound field at different angles of arrival to obtain a passive sound source localization cost function for different sound source distances and depths, thereby achieving the estimation of the target sound source distance and depth.

Description

Technical Field

[0001] This invention relates to the fields of underwater acoustic engineering, marine engineering and sonar technology, and in particular to a passive sound source localization method and system based on a vertical array in a deep-sea environment. Background Technology

[0002] The deep-sea sound field exhibits a distinct multipath arrival structure. Multipath arrival information, such as multipath angle of arrival, arrival delay between multiple paths, and interference characteristics, contains distance and depth information of the target sound source, which can be used to estimate the target distance and depth.

[0003] However, traditional passive target localization methods based on matched fields require significant computational resources for both the copy sound field calculation and the matching of the measured field with the copy field, making real-time target localization difficult. Localization methods based on the multipath arrival structure characteristics of matched sound fields, due to their clear physical meaning and low computational cost, have become a research hotspot in recent years. Taking the deep-sea direct sound zone as an example, existing target distance and depth estimation methods based on vertical arrays generally employ a step-by-step estimation approach. First, the target distance is estimated by matching the average angle of arrival of the direct wave and the sea surface reflected wave. After determining the target distance, the target depth is estimated by matching the multipath arrival delays of these two paths or by matching the frequency domain interference period. However, for these methods, the influence of noise at low signal-to-noise ratios introduces errors in the target angle of arrival estimation, and the resulting error in target distance estimation further affects the accuracy of target depth estimation. Furthermore, when the array aperture is large enough to distinguish the angle of arrival of the direct wave and the sea surface reflected wave, these methods still need to first screen and confirm the two angles of arrival corresponding to the same target from the spatial power spectrum estimation results before proceeding with subsequent localization processing.

[0004] To address the issue of distinguishable arrival angles of direct waves and sea-reflected waves in spatial power spectrum estimation results, patent application number 2021111809965, entitled "A Passive Sound Source Localization Method Based on Direct Wave and Sea-Reflected Wave Arrival Angles," discloses a passive sound source localization method based on matching the arrival angles of direct waves and sea-reflected waves. However, this method also faces the challenge of not being able to accurately obtain both arrival angles of the target sound source under low signal-to-noise ratio conditions, leading to significant errors in target distance and depth estimation due to estimation errors in the two angles. Furthermore, even with high signal-to-noise ratios, insufficiently dense angle grid division during spatial power spectrum estimation can result in grid-related errors in angle estimation, still causing substantial errors in distance and depth estimation. Summary of the Invention

[0005] The purpose of this invention is to overcome the above-mentioned defects of the prior art, thereby providing a passive sound source localization method and system based on a vertical array in a deep-sea environment, which has a wider range of application scenarios and further reduces the error of passive sound source localization.

[0006] To solve the above-mentioned technical problems, the present invention provides a passive sound source localization method based on a vertical array in a deep-sea environment, comprising:

[0007] Step 1: Receive the time-domain signal radiated by the target sound source by deploying a large-aperture vertical array on the seabed.

[0008] Step 2: Perform a Fast Fourier Transform on the time-domain signal received by each array element to obtain the corresponding signal spectrum;

[0009] Step 3: Using the spatial power spectrum estimation method, obtain the frequency domain beam output sound field of the signal spectrum of different elements of the vertical array at different angles of arrival;

[0010] Step 4: Based on the ray theory, the BELLHOP sound field calculation model calculates the template values ​​for the direct wave angle of arrival, the sea surface reflected wave angle of arrival, the direct wave arrival time delay, and the sea surface reflected wave arrival time delay under different assumed sound source distances and depths.

[0011] Step 5: Combine the four template values ​​obtained in Step 4 with the frequency domain beam output sound fields at different angles of arrival obtained in Step 3 to obtain the passive localization cost function of the sound source at different sound source distances and depths, thereby realizing the estimation of the target sound source distance and depth.

[0012] As an improvement to the above method, the vertical array is deployed at a depth of 400-6000m, and the ocean depth H in the deep sea ranges from 1000-6000m.

[0013] As an improvement to the above method, the depths of each element of the vertical array are d1,...,d... m ,...,d M Where d1 is the depth of the first array element, d m Let d be the depth of the m-th element. M Let f be the depth of the Mth element; the total number of elements in the vertical array is M, and the sampling rate of the vertical array is f. s The sampling rate f s The range is 100Hz to 40kHz.

[0014] As an improvement to the above method, in step 2, the time-domain signal received by the m-th array element undergoes a fast Fourier transform to obtain the signal at frequency f. l The signal spectrum at point x m (f l ); where l = 1, 2, ..., L, L is the number of frequency points processed, f1 is the preset lower bound of the frequency range for spatial power spectrum estimation and target sound source localization, f LThe preset upper bound of the frequency range for spatial power spectrum estimation and target sound source localization is defined as follows: f1 is the preset lower bound of the frequency range for spatial power spectrum estimation and target sound source localization, ranging from 0.1 Hz to 3.5 kHz; f1 is the preset upper bound of the frequency range for spatial power spectrum estimation and target sound source localization, ranging from 0.1 Hz to 3.5 kHz. L The range is 5Hz to 4kHz.

[0015] As an improvement to the above methods, spatial power spectrum estimation methods include: conventional beamforming spatial power spectrum estimation methods.

[0016] As an improvement to the above method, step 3 specifically includes:

[0017] Calculate at frequency point f l And angle θ k Frequency domain beam output sound field B(θ) k ,f l ):

[0018] B(θ k ,f l )=A(θ k ,f l ) H X(f l )

[0019] Wherein, the angle of arrival θ k A(θ) takes a value every 0.01° to 1° within the 0 to 90° angle range; k ,f l X(f) is the steering vector used during beamforming; l () represents the target sound source radiated signal received by the vertical array at frequency f l The spectral vector at the specified location; the superscript H denotes the conjugate transpose operator; where...

[0020]

[0021] in, c is the speed of sound of seawater at the center of the receiving array, d1 is the depth of the first array element, d2 is the depth of the second array element, and d m Let d be the depth of the m-th element. M Let T be the depth of the Mth element, and the superscript T denotes the transpose operator;

[0022] X(f l )=[x1(f l ),x2(f l ),…,x m (f l ),…,x M (f l )] T

[0023] Where, x1(f l ) is the first array element at frequency point f l The signal spectrum at x2(f) l ) is the second array element at frequency point f l The signal spectrum at x; m (f l ) represents the m-th array element at frequency point f l The signal spectrum at x M (f l ) represents the frequency point f of the Mth array element. l The signal spectrum at the location; the total number of array elements of the vertical array is M.

[0024] As an improvement to the above method, step 4 specifically includes:

[0025] Combining seawater sound velocity profiles from the vertical array deployment area in the database or seawater sound velocity profiles measured in marine experiments, the BELLHOP sound field calculation model based on ray theory is used to calculate the template values ​​of the direct wave angle of arrival corresponding to different assumed sound source distances and assumed sound source depths. Template value of the angle of arrival of the sea surface reflected wave and the template value of the arrival delay of the direct wave. Template value for arrival delay of sea surface reflected waves

[0026] Wherein, it is assumed that the depth of the sound source is z s The range is between 1m and 1000m, with depth intervals set between 0.1m and 10m; assuming the sound source distance r... s The range is set to 0 to 30 km, and the distance interval is set to 1 m to 200 m.

[0027] Obtain the arrival time delay between the direct wave and the sea surface reflected wave.

[0028]

[0029] As an improvement to the above method, step 5 specifically includes: obtaining the passive localization cost function E(r) for different sound source distances and depths. s ,z s ):

[0030]

[0031] Where, real represents the operator for taking the real part of a complex number. For frequency point f l And the template value of the direct wave angle of arrival Frequency domain beam output sound field, For frequency point f l And the template value of the angle of arrival of the sea surface reflected wave The frequency domain beam output sound field at f, where the superscript * represents the conjugate operator; l Here, f1 is the preset lower bound of the frequency range for spatial power spectrum estimation and target sound source localization, and f... L This serves as a preset upper bound for the frequency range used in spatial power spectrum estimation and target sound source localization.

[0032] Maximize the cost function E(r) s ,z s The corresponding distance is used as the distance estimate of the target sound source. Maximize the cost function E(r) s ,z s The corresponding depth is used as the depth estimate of the target sound source.

[0033] As an improvement to the above method, the horizontal distance between the target sound source and the vertical array ranges from 0.1 to 30 km; the depth range of the target sound source is greater than 10 m.

[0034] To achieve another objective of the present invention, the present invention also provides a passive sound source localization system based on a vertical array in a deep-sea environment, comprising:

[0035] A large-aperture vertical array, placed on the bottom of the sea, is used to receive time-domain signals radiated by target sound sources.

[0036] The transformation module is used to perform fast Fourier transform on the time-domain signals received by each array element to obtain the corresponding signal spectrum;

[0037] The spatial power spectrum estimation module is used to obtain the frequency domain beam output sound field of the signal spectrum of different array elements of the vertical array at different angles of arrival by means of spatial power spectrum estimation method.

[0038] The template value module is used to calculate template values ​​for the direct wave angle of arrival, the sea surface reflected wave angle of arrival, the direct wave arrival time delay, and the sea surface reflected wave arrival time delay under different assumed sound source distances and depths based on the ray theory-based sound field calculation model BELLHOP.

[0039] The target sound source estimation module combines the four template values ​​obtained by the template value module with the frequency domain beam output sound field at different angles of arrival obtained by the spatial power spectrum estimation module to obtain the passive localization cost function of the sound source at different sound source distances and depths, thereby realizing the estimation of the target sound source distance and depth.

[0040] Compared to existing technologies, the advantages of this invention lie in its provision of a passive sound source localization method and system based on a vertical array in deep-sea environments. This method constructs a novel cost function for estimating target distance and depth, fully utilizing the multipath angle of arrival (AOA) and multipath arrival delay (ADD) information obtained from the vertical array. Compared to existing methods that only match AOA, this invention simultaneously utilizes the ADD information between multiple paths, thus achieving smaller target distance and depth estimation errors. The proposed method and system are applicable to scenarios where the direct wave and sea surface reflected wave are angularly distinguishable in the spatial power spectrum estimation results, as well as scenarios where the direct wave and sea surface reflected wave are angularly indistinguishable. Compared to localization methods that only match AOA and are only applicable to scenarios where the multipath AOA is distinguishable, this invention has a wider range of applications. Furthermore, compared to existing step-by-step estimation methods that first estimate the target sound source distance and then estimate the target sound source depth, this invention can simultaneously estimate the target distance and depth, achieving more accurate target distance and depth estimation results even at low signal-to-noise ratios. Attached Figure Description

[0041] Figure 1 This is a schematic diagram of the simulated deep-sea environment in Example 1;

[0042] Figure 2 This is the seawater sound velocity profile used in the simulation experiment of Example 1;

[0043] Figure 3(a) shows the motion trajectory of the sound source in the simulation experiment of Example 1;

[0044] Figure 3(b) shows the sound source transmission and reception distance in the simulation experiment of Example 1;

[0045] Figure 4 The spatial power spectrum estimation results of the target sound source obtained by conventional beamforming at all times in the simulation experiment of Example 1 are the results of the spatial power spectrum estimation obtained by the target sound source at all times.

[0046] Figure 5 The spatial power spectrum estimation results obtained by conventional beamforming of a vertical array when the transmission and reception distance is 3.51km in the simulation experiment of Example 1 are as follows;

[0047] Figure 6 It is the positioning cost function when the transmission and reception distance is 3.51km in the simulation experiment of Example 1;

[0048] Figure 7 These are the sound source distance estimation results at all times during the simulation experiment in Example 1;

[0049] Figure 8 These are the sound source depth estimation results at all times during the simulation experiment in Example 1;

[0050] Figure 9 This is a flowchart of the passive sound source localization method based on a vertical array in a deep-sea environment provided in Example 1. Detailed Implementation

[0051] The technical solutions provided by the present invention will be further illustrated below with reference to the embodiments.

[0052] Example 1

[0053] like Figure 9 As shown, this embodiment provides a passive sound source localization method based on a vertical array in a deep-sea environment. The method is characterized by: firstly, deploying a vertical array near the seabed to receive the time-domain signal radiated by the target sound source; then performing a Fast Fourier Transform on the time-domain signal to obtain the signal spectrum; processing the signal spectrum received by different array elements of the vertical array using conventional beamforming azimuth spectrum estimation methods to obtain the frequency-domain beam output sound field at different angles of arrival; then calculating the direct wave angle of arrival, the sea surface reflected wave angle of arrival, and the arrival delay template values ​​for these two paths under different assumed sound source distances and depths using the BELLHOP sound field calculation model based on ray theory; combining the angle of arrival and arrival delay template values ​​calculated by the above model with the measured frequency-domain beam output sound field of the vertical array at different angles of arrival, constructing a cost function to obtain the passive sound source localization cost function at different sound source distances and depths, thereby achieving the estimation of the target sound source distance and depth. The specific steps are as follows:

[0054] Step 1: An M-element vertical hydrophone receiving array is deployed near the seabed in the deep sea to collect the time-domain signal radiated by the target sound source. The depths of the vertical array elements are d1,...,d... m ,...,d M M is the number of elements in the vertical array, and the sampling rate of the vertical array is f. s The value range is 100Hz to 40kHz;

[0055] Step 2: Perform a Fast Fourier Transform on the time-domain signal acquired by the vertical hydrophone array to obtain the frequency f of the m-th hydrophone. l The spectrum at x m (f l ), where l = 1, 2, ..., L, L is the number of frequency points processed, f1 and f L These represent the lower and upper bounds of the frequency range selected for subsequent spatial power spectrum estimation and target localization, respectively. The range of f1 is 0.1Hz to 3.5kHz. L The range is 50Hz to 4kHz. The target sound source radiated signal received by the vertical array at frequency f l The spectral vector at point X(f) is l )=[x1(f l ),x2(f l ),...,x M (f l )] T, where the superscript T indicates the transpose operator;

[0056] Step 3: Calculate the beam output sound field of the vertical array at different angles and frequencies using conventional beamforming and other spatial power spectrum estimation methods. Taking conventional beamforming as an example, the following formula is used to calculate the beam output sound field at frequency f. l Angle θ k Beam output sound field at: B(θ) k ,f l )=A(θ k ,f l ) H X(f l ), where the angle of arrival θ k A(θ) takes a value every 0.01° to 1° within the 0 to 90° angle range; k ,f l ) is the steering vector used during beamforming. c represents the speed of sound of seawater at the center of the receiving array, and the superscript H indicates the conjugate transpose operator.

[0057] Step 4: Combining the seawater sound velocity profiles of the array deployment area retrieved from the database or the seawater sound velocity profiles measured in marine experiments, the BELLHOP sound field calculation model based on ray theory is used to calculate the template values ​​of the angle of arrival of the direct wave and the sea surface reflected wave corresponding to different assumed distances and assumed depths of the sound source. and And template values ​​for the arrival times of direct waves and sea-reflected waves. and Further obtain the arrival time delay of direct waves and sea surface reflected waves. When calculating the template value, the receiving depth is set to the array center depth, assuming the sound source depth is z. s The range is between 1m and 1000m, with depth intervals set between 0.1m and 10m; assuming the sound source distance r... s The range is set to 0 to 30 km, and the distance interval is set to 1 m to 200 m.

[0058] Step 5: Calculate the passive localization cost function of the sound source according to the following formula. Here, the superscript * represents the conjugate operator. The distance and depth corresponding to the maximum value of the cost function are the estimated values ​​of the target distance and depth, i.e.

[0059] The sea depth H ranges from 1000 to 6000 m.

[0060] The deployment depth of the receiving array is 400-6000m.

[0061] The horizontal distance between the sound source and the receiving array ranges from 0.1 to 30 km.

[0062] The depth range of the sound source is greater than 10m.

[0063] This embodiment proposes a passive sound source localization method based on a vertical array in a deep-sea environment. The vertical array is deployed near the seabed to receive the time-domain signal radiated by the target sound source. The frequency-domain beam output sound field of the vertical array at different angles of arrival is obtained through processing such as Fast Fourier Transform and spatial power spectrum estimation. Then, the multipath angle of arrival and time of arrival template values ​​under different assumed sound source distances and depths are calculated using the Bellhop sound field calculation model based on ray theory. A cost function is constructed to obtain the passive localization cost function under different assumed sound source distances and depths, thereby achieving the estimation of sound source distance and depth. This embodiment starts from the multipath propagation characteristics of the deep-sea sound field, mainly utilizing the multipath arrival characteristics of the strongest direct wave and the sea surface reflected wave in the direct sound zone. By constructing a localization cost function, the measured beam output sound field of the vertical array is combined with the multipath arrival characteristics calculated by the model, thereby obtaining more accurate target distance and depth estimation results.

[0064] The present embodiment will now be further described with reference to the accompanying drawings:

[0065] The method is illustrated using a simulation experiment of underwater acoustic source radiation signals received by a deep-sea vertical array deployed near the seabed as an example.

[0066] Figure 1 This diagram illustrates the multiple propagation paths for vertical array reception in a deep-sea environment. Figure 1 The diagram shows the direct wave and sea surface reflected wave, which contribute significantly to the sound field, while neglecting the weaker seabed reflected wave. The sea depth used in the simulation was 1507m, and the seawater sound velocity profile used in the simulation is shown below. Figure 2 The receiving array is a 16-element synchronous, equally spaced vertical linear array deployed near the seabed. The array aperture is 112.5m, the element spacing is 7.5m, and the array center depth is approximately 1392m. The array deployment depth is detailed in [link to relevant documentation]. Figure 2 The sound source depth is set to 200m. The sound source first approaches and then moves away from the receiving array. The transmission and reception distance first decreases from 6km to 1km and then increases to 7km. Figure 3(a) shows the trajectory information of the sound source target relative to the vertical array, and Figure 3(b) shows the transmission and reception distance information of the sound source target relative to the vertical array. After receiving the sound source signal, the vertical array performs Fourier transform, beamforming, multipath arrival feature template value calculation, cost function calculation, etc., to estimate the distance and depth of the target sound source. The process is divided into the following steps:

[0067] Step 1: A 16-element synchronous vertical linear array is deployed near the seabed to collect the time-domain signal p radiated by the target sound source. m (t), the depth of each element in the vertical array increased from 1335.5m to 1448m. The sampling rate of the vertical array is 16kHz.

[0068] Step 2: Perform a Fourier transform on the time-domain signal acquired by each element of the vertical linear array to obtain the frequency of the m-th element at frequency f. l The spectrum at x m (f l ), where l = 1, 2, ..., L; f1 and f L These represent the lower and upper bounds of the frequency range selected for subsequent spatial power spectrum estimation and target localization, respectively. The range of f1 is 0.1Hz to 3.5kHz. L The range is 50Hz to 4kHz. In this embodiment, f1 and f L The values ​​are taken as 150Hz and 200Hz respectively. The target sound source radiated signal received by the vertical array at frequency point f l The spectral vector at point X(f) is l )=[x1(f l ),x2(f l ),...,x M (f l )] T The superscript T indicates the transpose operator.

[0069] Step 3: Calculate the beam output sound field of the vertical array at different angles and frequencies using conventional beamforming and other spatial power spectrum estimation methods. Taking conventional beamforming as an example, the following formula is used to calculate the beam output sound field at frequency f. l Angle θ k Beam output sound field at: B(θ) k ,f l )=A(θ k ,f l ) H X(f l ), where the angle of arrival θ k A(θ) takes a value every 0.5° within the 0 to 90° angle range; k ,f l ) is the steering vector used during beamforming. c represents the speed of sound of seawater at the center of the receiving array, and the superscript H indicates the conjugate transpose operator. Figure 4 The figure shows the spatial power spectrum estimation results obtained by conventional beamforming during the movement of the target sound source. The two peak curves in the figure correspond to the angle of arrival of the direct wave from the target sound source and the reflected wave from the sea surface, respectively.

[0070] Step 4: Combining the seawater sound velocity profiles of the array deployment area retrieved from the database or the seawater sound velocity profiles measured in marine experiments, the BELLHOP sound field calculation model based on ray theory is used to calculate the template values ​​of the angle of arrival of the direct wave and the sea surface reflected wave corresponding to different assumed distances and assumed depths of the sound source. and And template values ​​for the arrival times of direct waves and sea-reflected waves. and Further obtain the arrival time delay of direct waves and sea surface reflected waves. In this embodiment, the receiving depth is set to 1392m at the center of the array when calculating the template value, and the sound source depth is assumed to be z. s The range is set to 100m to 300m, and the depth interval is set to 1m; assuming the sound source distance r... s The range is set to 0km to 8km, and the distance interval is set to 10m.

[0071] Step 5: Calculate the passive localization cost function of the sound source. Where, real represents the operator for taking the real part of a complex number. For frequency point f l And angle Frequency domain beam output sound field, For frequency point f l And angle The frequency domain beamout sound field at that location, with the superscript * representing the conjugate operator. The distance and depth corresponding to the maximum value of the cost function are the estimated values ​​of the target distance and depth, i.e. Taking the received signal at the 10.5-minute mark, when the distance between the sound source and the receiving array is 3.51 km, as an example, Figure 5 The spatial power spectrum estimation results obtained by conventional beamforming of a vertical array are presented. The values ​​of the two dashed lines in the figure correspond to the angle of arrival of the direct wave and the sea surface reflected wave, respectively. Figure 6 The cost functions for estimating the target distance and depth are given. Figure 6 The square frame in the middle represents the actual location of the target. Figure 6 The middle circle represents the estimated location of the target. The estimated depth of the target sound source is 202m, and the estimated distance is 3.54km, which is consistent with the actual location. Figure 7 and Figure 8 The distance and depth estimation results for the sound source at all time points are presented. For comparison, both figures show the passive target localization results of existing angle-of-arrival-only localization methods. It can be seen that, compared with existing methods, the method proposed in this invention achieves smaller distance and depth estimation errors. Furthermore, the method proposed in this invention is applicable to both scenarios where the direct wave and sea-reflected wave are angularly distinguishable in the spatial power spectrum estimation results, and scenarios where the direct wave and sea-reflected wave are angularly indistinguishable in the spatial power spectrum estimation results. Compared to localization methods that only match the angle of arrival and are only applicable to scenarios where multiple paths of arrival are distinguishable, the method of this invention has a wider range of application scenarios.

[0072] Example 2

[0073] This embodiment provides a passive sound source localization system based on a vertical array in a deep-sea environment, including:

[0074] A large-aperture vertical array, placed on the bottom of the sea, is used to receive time-domain signals radiated by target sound sources.

[0075] The transformation module is used to perform fast Fourier transform on the time-domain signals received by each array element to obtain the corresponding signal spectrum;

[0076] The spatial power spectrum estimation module is used to obtain the frequency domain beam output sound field of the signal spectrum of different array elements of the vertical array at different angles of arrival by means of spatial power spectrum estimation method.

[0077] The template value module is used to calculate template values ​​for the direct wave angle of arrival, the sea surface reflected wave angle of arrival, the direct wave arrival time delay, and the sea surface reflected wave arrival time delay under different assumed sound source distances and depths based on the ray theory-based sound field calculation model BELLHOP.

[0078] The target sound source estimation module combines the four template values ​​obtained by the template value module with the frequency domain beam output sound field at different angles of arrival obtained by the spatial power spectrum estimation module to obtain the passive localization cost function of the sound source at different sound source distances and depths, thereby realizing the estimation of the target sound source distance and depth.

[0079] 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 passive sound source localization method based on a vertical array in a deep-sea environment, comprising: Step 1: Receive the time-domain signal radiated by the target sound source by deploying a large-aperture vertical array on the seabed. Step 2: Perform a Fast Fourier Transform on the time-domain signal received by each array element to obtain the corresponding signal spectrum; Step 3: Using the spatial power spectrum estimation method, obtain the frequency domain beam output sound field of the signal spectrum of different elements of the vertical array at different angles of arrival; Step 4: Based on the ray theory, the BELLHOP sound field calculation model calculates the template values ​​for the direct wave angle of arrival, the sea surface reflected wave angle of arrival, the direct wave arrival time delay, and the sea surface reflected wave arrival time delay under different assumed sound source distances and depths. Step 5: Combine the four template values ​​obtained in Step 4 with the frequency domain beam output sound fields at different angles of arrival obtained in Step 3 to obtain the passive localization cost function of the sound source at different sound source distances and depths, thereby realizing the estimation of the target sound source distance and depth. Step 5 specifically includes: obtaining the passive localization cost function E(r) for sound sources at different distances and depths. s ,z s ): Where, real represents the operator for taking the real part of a complex number. For frequency point f l And the template value of the direct wave angle of arrival Frequency domain beam output sound field, For frequency point f l And the template value of the angle of arrival of the sea surface reflected wave The frequency domain beam output sound field at f, where the superscript * represents the conjugate operator; l Here, f1 is the preset lower bound of the frequency range for spatial power spectrum estimation and target sound source localization, and f... L This serves as a preset upper bound for the frequency range used in spatial power spectrum estimation and target sound source localization. The arrival time delay between the direct wave and the sea surface reflected wave; Maximize the cost function maxE(r) s ,z s The corresponding distance is used as the distance estimate of the target sound source. Maximize the cost function maxE(r) s ,z s The corresponding depth is used as the depth estimate of the target sound source.

2. The passive sound source localization method based on a vertical array in a deep-sea environment according to claim 1, characterized in that, The vertical array is deployed at a depth of 400-6000m, and the ocean depth H ranges from 1000-6000m in the deep sea.

3. The passive sound source localization method based on a vertical array in a deep-sea environment according to claim 1, characterized in that, The depths of the elements of the vertical array are d1,...,d1,... m ,...,d M ; Where d1 is the depth of the first array element, d m Let d be the depth of the m-th element. M Let f be the depth of the Mth element; the total number of elements in the vertical array is M, and the sampling rate of the vertical array is f. s The sampling rate f s The range is 100Hz to 40kHz.

4. The passive sound source localization method based on a vertical array in a deep-sea environment according to claim 1, characterized in that, In step 2, the time-domain signal received by the m-th array element undergoes a Fast Fourier Transform to obtain the signal at frequency f. l The signal spectrum at point x m (f l ); where l = 1, 2, ..., L, L is the number of frequency points processed, f1 is the preset lower bound of the frequency range for spatial power spectrum estimation and target sound source localization, f L The preset upper bound of the frequency range for spatial power spectrum estimation and target sound source localization is defined as follows: f1 is the preset lower bound of the frequency range for spatial power spectrum estimation and target sound source localization, ranging from 0.1 Hz to 3.5 kHz; f1 is the preset upper bound of the frequency range for spatial power spectrum estimation and target sound source localization, ranging from 0.1 Hz to 3.5 kHz. L The range is 5Hz to 4kHz.

5. The passive sound source localization method based on a vertical array in a deep-sea environment according to claim 4, characterized in that, Step 3 specifically includes: Calculate at frequency point f l And angle θ k Frequency domain beam output sound field B(θ) k ,f l ): B(θ k ,f l )=A(θ k ,f l ) H X(f l ) Wherein, the angle of arrival θ k A(θ) takes a value every 0.01° to 1° within the 0 to 90° angle range; k ,f l X(f) is the steering vector used during beamforming; l () represents the target sound source radiated signal received by the vertical array at frequency f. l The spectral vector at the specified location; the superscript H denotes the conjugate transpose operator; where... in, c is the speed of sound of seawater at the center of the receiving array, d1 is the depth of the first array element, d2 is the depth of the second array element, and d m Let d be the depth of the m-th element. M Let T be the depth of the Mth element, and the superscript T denotes the transpose operator; X(f l )=[x1(f l ),x2(f l ),…,x m (f l ),…,x M (f l )] T Where, x1(f l ) is the first array element at frequency point f l The signal spectrum at x2(f) l ) is the second array element at frequency point f l The signal spectrum at x; m (f l ) represents the m-th array element at frequency point f l The signal spectrum at x M (f l ) represents the frequency point f of the Mth array element. l The signal spectrum at the location; the total number of array elements of the vertical array is M.

6. The passive sound source localization method based on a vertical array in a deep-sea environment according to claim 1, characterized in that, Step 4 specifically includes: Combining seawater sound velocity profiles from the vertical array deployment area in the database or seawater sound velocity profiles measured in marine experiments, the BELLHOP sound field calculation model based on ray theory is used to calculate the template values ​​of the direct wave angle of arrival corresponding to different assumed sound source distances and assumed sound source depths. Template value of the angle of arrival of the sea surface reflected wave and the template value of the arrival delay of the direct wave. Template value for arrival delay of sea surface reflected waves Wherein, it is assumed that the depth of the sound source is z s The range is between 1m and 1000m, with depth intervals set between 0.1m and 10m; assuming the sound source distance r... s The range is set to 0 to 30 km, and the distance interval is set to 1 m to 200 m. Obtain the arrival time delay between the direct wave and the sea surface reflected wave.

7. The passive sound source localization method based on a vertical array in a deep-sea environment according to claim 1, characterized in that, The horizontal distance between the target sound source and the vertical array ranges from 0.1 to 30 km; the depth range of the target sound source is greater than 10 m.

8. A passive sound source localization system based on a vertical array in a deep-sea environment, used to implement the passive sound source localization method based on a vertical array in a deep-sea environment as described in any one of claims 1-7, comprising: A large-aperture vertical array, placed on the bottom of the sea, is used to receive time-domain signals radiated by target sound sources. The transformation module is used to perform fast Fourier transform on the time-domain signals received by each array element to obtain the corresponding signal spectrum; The spatial power spectrum estimation module is used to obtain the frequency domain beam output sound field of the signal spectrum of different array elements of the vertical array at different angles of arrival by means of spatial power spectrum estimation method. The template value module is used to calculate the template values ​​of the direct wave arrival angle, the sea surface reflected wave arrival angle, the direct wave arrival time delay, and the sea surface reflected wave arrival time delay under different assumed sound source distances and depths in the BELLHOP sound field calculation model based on ray theory. and The target sound source estimation module combines the four template values ​​obtained by the template value module with the frequency domain beam output sound field at different angles of arrival obtained by the spatial power spectrum estimation module to obtain the passive localization cost function of the sound source at different sound source distances and depths, thereby realizing the estimation of the target sound source distance and depth.

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