A sound source direction finding method and device based on horizontal linear array

Abstract

The present invention discloses a sound source direction-finding method and device based on a horizontal linear array. The method comprises: obtaining a time-domain sound pressure signal of a target sound source through a horizontal linear array; transforming the time-domain sound pressure signal into the frequency domain to obtain a frequency-domain sound pressure signal of the target sound source; performing beamforming on the frequency-domain sound pressure signal to obtain a spatial spectrum of the target sound source; and performing diffraction analysis on the spatial spectrum to obtain the azimuth of the target sound source relative to the horizontal linear array. This method does not require distance information to the target sound source, but utilizes surface waveguide leakage signals to accurately estimate the azimuth of the target sound source through diffraction analysis. It has good direction-finding stability and accuracy and is particularly suitable for deep-sea environments where surface waveguides exist.

Description

Technical Field

[0001] The present invention relates to the technical field of underwater acoustic array signal processing, and in particular to a sound source direction finding method and device based on a horizontal linear array. Background Art

[0002] Under deep-sea waveguide conditions, when the sound source is located within a few hundred meters near the sea surface, the direct sound zone formed can only extend to a smaller range near the sea surface. Therefore, the towed horizontal array often needs to work in the acoustic shadow zone.

[0003] Existing horizontal line array direction-finding methods based on seabed reflection signals in acoustic shadow zones are affected by the azimuth-grazing angle coupling effect. In the absence of target range information, they can only provide biased estimates of the target sound source's azimuth. Furthermore, since seabed reflection signals, which interact with the seabed at different times, have different grazing angles, this multipath effect further complicates the estimation of the target sound source's azimuth based on seabed reflection signals. Furthermore, seabed reflection signals are often affected by complex seabed environmental conditions, making these algorithms for horizontal line array direction-finding in acoustic shadow zones significantly unstable. Summary of the Invention

[0004] The purpose of the present invention is to overcome the defect of the prior art that the target sound source direction cannot be accurately estimated. A sound source direction finding method based on a horizontal linear array is proposed. The present invention also discloses a sound source direction finding device based on a horizontal linear array.

[0005] In order to achieve the above object, the present invention proposes a sound source direction finding method based on a horizontal linear array, comprising:

[0006] The time domain sound pressure signal of the target sound source is obtained through the horizontal line array;

[0007] Converting the time-domain sound pressure signal to the frequency domain to obtain a frequency-domain sound pressure signal of the target sound source;

[0008] Performing beamforming on the frequency-domain sound pressure signal to obtain a spatial spectrum of the target sound source;

[0009] A diffraction analysis is performed on the spatial spectrum to obtain the azimuth angle of the target sound source relative to the horizontal linear array.

[0010] As an improvement to the above method, obtaining the time-domain sound pressure signal of the target sound source through the horizontal line array includes:

[0011] Signal acquisition is performed by using a horizontal linear array pre-deployed in an underwater environment where a surface waveguide exists and working in an acoustic shadow area to obtain a time-domain sound pressure signal from the target sound source on each array element.

[0012] As an improvement to the above method, performing diffraction analysis on the spatial spectrum to obtain the azimuth angle of the target sound source relative to the horizontal linear array includes:

[0013] performing incoherent accumulation on the spatial spectrum on the frequency axis to obtain a broadband spatial spectrum of the target sound source;

[0014] Extracting the angle values ​​corresponding to the peaks of the broadband spatial spectrum and selecting the smallest angle value;

[0015] The minimum angle value is input into a diffraction theory correction model to obtain the azimuth angle of the target sound source relative to the horizontal linear array.

[0016] As an improvement to the above method, the diffraction theory correction model includes:

[0017]

[0018] Where, represents the azimuth angle of the target sound source relative to the horizontal line array, Indicates the minimum angle value, c a represents the speed of sound at the horizontal line array, c surb represents the speed of sound at the interface between the surface waveguide and the thermocline, and arccos represents the inverse cosine function.

[0019] As an improvement to the above method, transforming the time-domain sound pressure signal into the frequency domain to obtain the frequency-domain sound pressure signal of the target sound source includes:

[0020] The time domain sound pressure signal is transformed into the frequency domain by the following formula: l ),

[0021] P(f,r l )=∫p(t,r l )e -j2πft dt

[0022] Where, p(t,r l ) represents the time domain sound pressure signal of the target sound source, f represents the frequency, j is the imaginary unit, t represents the time, r l Represents the distance between the lth array element and the target sound source, l = 0, 1, ..., L-1, where L is the number of array elements.

[0023] As an improvement to the above method, performing beamforming on the frequency domain sound pressure signal to obtain the spatial spectrum of the target sound source includes:

[0024] The frequency domain sound pressure signal P(f,r) of the target sound source on each array element is calculated by the following formula:l ) to perform beamforming to obtain the spatial spectrum B(f,θ) of the target sound source,

[0025]

[0026] Where c a represents the speed of sound at the array, d represents the horizontal linear array element spacing, and θ represents the search angle.

[0027] As an improvement to the above method, performing incoherent accumulation on the frequency axis to obtain the broadband spatial spectrum of the target sound source includes:

[0028] The broadband spatial spectrum B of the target sound source is obtained by incoherently integrating the spatial spectrum on the frequency axis using the following formula: accum (θ),

[0029]

[0030] Wherein, f represents frequency; B(f,θ) represents the spatial spectrum B(f,θ) of the target sound source.

[0031] As an improvement to the above method, the horizontal linear array is arranged in a deep-sea environment, and obtaining the time-domain sound pressure signal of the target sound source through the horizontal linear array includes:

[0032] Acquiring the seawater temperature at the initial position of the horizontal linear array;

[0033] determining whether the horizontal array is in an isothermal layer according to the seawater temperature, and if not, adjusting the position of the horizontal array by dragging until the horizontal array is in the isothermal layer;

[0034] identifying whether the horizontal linear array is operating in an acoustic shadow area; if not, adjusting the position of the horizontal linear array again by dragging until the horizontal linear array is operating in the acoustic shadow area, and outputting information indicating that the horizontal linear array is in a deep-sea environment with a surface waveguide and is operating in the acoustic shadow area;

[0035] The time domain sound pressure signal of the target sound source is obtained respectively through each array element of the horizontal linear array.

[0036] As an improvement to the above method, the distance between the target sound source and the horizontal linear array is 5 to 15 km, and the dragging depth of the horizontal linear array is 50 to 200 m.

[0037] The present invention also proposes a sound source direction finding device based on a horizontal linear array, comprising:

[0038] The detection module is used to obtain the time domain sound pressure signal of the target sound source through a horizontal line array;

[0039] a conversion module, configured to convert the time-domain sound pressure signal into the frequency domain to obtain the frequency-domain sound pressure signal of the target sound source;

[0040] A target sound source spatial spectrum acquisition module is configured to perform beamforming on the frequency domain sound pressure signal to obtain the spatial spectrum of the target sound source;

[0041] The azimuth angle acquisition module is used to perform diffraction analysis on the spatial spectrum to obtain the azimuth angle of the target sound source relative to the horizontal linear array.

[0042] Compared with the prior art, the advantages of the present invention are:

[0043] 1. Utilizing diffraction analysis theory, a horizontal array is used to perform passive sound source direction finding. This method accurately estimates the azimuth of a target sound source without requiring distance information.

[0044] 2. Under deep-sea waveguide conditions, the time-domain sound pressure signal of the target sound source contains the surface waveguide leakage signal. This method utilizes the surface waveguide leakage signal, which is more stable in terms of propagation angle characteristics and therefore has stronger robustness.

[0045] 3. The time-domain sound pressure signal received by the horizontal line array working in the acoustic shadow zone in a deep-sea environment with surface waveguides is more stable in terms of propagation angle characteristics than the existing horizontal line array direction-finding algorithm in the acoustic shadow zone based on seabed reflection signals, and therefore has stronger robustness.

[0046] 4. Compared with the existing horizontal line array direction finding algorithm in the acoustic shadow zone based on the seabed reflection signal, it does not need to consider the interference caused by the multipath effect, so it is more practical. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 is a flow chart of the method of embodiment 1 of the present invention;

[0048] Figure 2 This is an example of the positional relationship between the horizontal line array and the target sound source in Example 1 of the present invention;

[0049] Figure 3 is a deep-sea sound velocity profile used in the simulation example of the present invention;

[0050] Figure 4 The simulation example of the present invention transforms the signal received on the horizontal linear array into an energy distribution diagram in the frequency-angle domain through Fourier transform and beamforming, and obtains a broadband spatial spectrum by incoherent accumulation on the frequency axis;

[0051] Figure 5This is a comparison chart of the azimuth angle estimation results of the sound source under different azimuth conditions of the simulation example of the present invention and the azimuth angle obtained by the existing horizontal line array direction finding algorithm in the acoustic shadow area based on the seabed reflection signal (the estimation result using a single seabed reflection signal);

[0052] Figure 6 This is a comparison chart of the estimation results of the sound source azimuth angle under the conditions that the sound source is located at different distances from the simulation example of the present invention and the estimation results using a single seabed reflection signal;

[0053] Figure 7 This is a comparison chart of the estimation results of the sound source azimuth angle of the simulation example of the present invention when the array is located at different depths and the estimation results using a single seabed reflection signal;

[0054] Figure 8 This is an energy distribution diagram in the frequency-angle domain obtained by transforming the actual received signal into the energy distribution diagram in the simulation example of the present invention in an actual ocean environment through Fourier transform and beamforming.

[0055] Reference numerals

[0056] θ'-the true azimuth of the target sound source relative to the horizontal line array;

[0057] The azimuth angle of the target sound source relative to the horizontal linear array obtained by the method of the present invention;

[0058] Δθ - the estimated error of the azimuth angle of the method of the present invention;

[0059] θ1-the azimuth angle obtained by the existing horizontal line array direction finding algorithm in the acoustic shadow zone based on the seabed reflection signal. DETAILED DESCRIPTION

[0060] To ensure accurate estimation of the target sound source's direction, a general sound source direction-finding method based on a horizontal linear array is proposed. This method uses surface waveguide leakage signals to determine the target sound source's orientation. Because surface waveguide leakage signals are more stable in terms of propagation angle characteristics, this method is more robust.

[0061] In order to introduce the present invention more clearly, the professional terms involved in the present invention are first described below.

[0062] Acoustic shadow zone: refers to the area where sound cannot reach due to obstacles or refraction, that is, the area with almost no sound.

[0063] Ocean surface ducting mode: A special type of atmospheric ducting occurs over the ocean. This ducting mode typically occurs in relatively stable atmospheric conditions, characterized by a stable temperature inversion layer in the lower atmosphere and a decreasing humidity with altitude. These conditions cause the atmospheric modified refractive index to decrease upward, thus forming a surface duct.

[0064] Surface waveguide leakage signal: The signal emitted by the target sound source diffracts on the ocean surface beneath the surface waveguide, forming a surface waveguide leakage signal. Research has shown that this surface waveguide leakage signal has more stable propagation angle characteristics, making it more robust.

[0065] Deep sea: sea areas with a depth of 200m or more.

[0066] Thermocline: A layer located about 100-200m below the sea surface with huge changes in temperature and density. It is a layer where the water temperature drops sharply between the thin warm water layer above and the thick cold water layer below.

[0067] The technical solution of the present invention is described in detail below with reference to the accompanying drawings and embodiments.

[0068] Example 1

[0069] Embodiment 1 of the present invention proposes a sound source direction finding method based on a horizontal line array, such as Figure 1 As shown, the method includes:

[0070] S110. Obtain the time domain sound pressure signal of the target sound source through the horizontal line array;

[0071] S120. Transform the time domain sound pressure signal into the frequency domain to obtain the frequency domain sound pressure signal of the target sound source;

[0072] S130. Perform beamforming on the frequency-domain sound pressure signal to obtain the spatial spectrum of the target sound source;

[0073] S140. Perform diffraction analysis on the spatial spectrum to obtain the azimuth angle of the target sound source relative to the horizontal linear array.

[0074] Regarding step S110, the positional relationship between the horizontal line array and the target sound source is as follows: Figure 2 As shown in Figure 2, the time domain sound pressure signal of the target sound source obtained by the horizontal line array contains the surface waveguide leakage signal.

[0075] For step S120, the signal conversion method from the time domain to the frequency domain may generally adopt the Fourier transform method.

[0076] In step S130 , the frequency domain beamforming method only selects the frequency of the target sound source (which is also the frequency of the surface waveguide leakage signal) for beamforming.

[0077] For step S140, there are many methods for obtaining the target sound source based on diffraction analysis of the spatial spectrum. In addition to the method in Example 2 below, a neural network or vector machine can also be used to extract the diffraction characteristics of the spatial spectrum and input them into the neural network or vector machine to obtain the azimuth angle of the target sound source relative to the horizontal line array.

[0078] It should be noted that this method can accurately estimate the azimuth of the target sound source without the distance information of the target sound source.

[0079] By sequentially executing steps S110 to S140, compared with the existing horizontal line array direction-finding algorithm in the acoustic shadow zone based on the seabed reflection signal, the method of this embodiment can accurately estimate the azimuth of the target sound source without requiring the distance information of the target sound source, and does not need to consider the interference caused by the multipath effect, and is stable.

[0080] This method can be applied to any target sound source positioning scenario where diffraction phenomena exist, including but not limited to placing a horizontal linear array in the deep sea, which can be understood by those skilled in the art.

[0081] Example 2

[0082] Based on the method of Example 1, step S110 is improved and further includes sub-step S111:

[0083] S111. Signal acquisition is performed by using a horizontal linear array pre-deployed in an underwater environment where a surface waveguide exists and operating in an acoustic shadow zone to obtain a time-domain sound pressure signal from a target sound source on each array element.

[0084] It should be noted that the presence of surface waveguides is determined by the presence of an isothermal layer, i.e., an area where the seawater temperature remains constant. Since the propagation angle characteristics of surface waveguide leakage signals are more stable, the depth of the underwater environment is not restricted, and the horizontal array can be moved by dragging.

[0085] Optionally, step S110 may further include sub-steps S112 to S115:

[0086] S112. Obtaining the seawater temperature at the initial position of the horizontal array;

[0087] S113. Determine whether the horizontal array is in the isothermal layer based on the seawater temperature. If not, adjust the position of the horizontal array by dragging until the horizontal array is in the isothermal layer.

[0088] S114. Identify whether the horizontal linear array is operating in the acoustic shadow zone. If not, adjust the position of the horizontal linear array again by dragging until the horizontal linear array is operating in the acoustic shadow zone, and output information indicating that the horizontal linear array is in a deep-sea environment with a surface waveguide and is operating in the acoustic shadow zone.

[0089] S115. Obtain the time-domain sound pressure signal of the target sound source through each array element of the horizontal linear array.

[0090] Preferably, the distance from the target sound source to the horizontal array is 5 to 15 km, and the towing depth of the horizontal array is 50 to 200 m. Furthermore, the element aperture of the horizontal array is not limited, and the element spacing can be set to half the wavelength of the target sound source frequency until no fan lobes appear.

[0091] In summary, through step S110, the time domain sound pressure signal of the target sound source is obtained using the horizontal line array.

[0092] Preferably, step S120 further includes: transforming the time domain sound pressure signal into the frequency domain by the following formula to obtain the frequency domain sound pressure signal P(f,r l ),

[0093] P(f,r l )=∫p(t,r l )e -j2πft dt (1)

[0094] Where, p(t,r l ) represents the time domain sound pressure signal of the target sound source, f represents the frequency, j is the imaginary unit, t represents the time, r l represents the distance between the lth array element and the target sound source, l = 0, 1, ..., L-1, L is the number of array elements, e and π are constants, which are common knowledge in the art.

[0095] Preferably, step S130 includes: converting the frequency domain sound pressure signal P(f,r) of the target sound source on each array element into: l ) to perform beamforming and obtain the spatial spectrum B(f,θ) of the target sound source.

[0096]

[0097] Where c a represents the speed of sound at the array, d represents the horizontal linear array element spacing, and θ represents the search angle.

[0098] Preferably, step S140 includes sub-steps S141 to S143:

[0099] S141. Perform incoherent accumulation of the spatial spectrum on the frequency axis to obtain a broadband spatial spectrum of the target sound source;

[0100] S142. Extract the angle values ​​corresponding to each peak of the broadband spatial spectrum (specifically the angle value of the signal source, which is common knowledge), and select the smallest angle value;

[0101] S143. Input the minimum angle value into the diffraction theory correction model to obtain the azimuth angle of the target sound source relative to the horizontal linear array.

[0102] It should be noted that steps S140 to S143 constitute the optimal azimuth angle detection scheme. Utilizing the surface waveguide leakage signal, the propagation angle characteristics are more stable, and thus have greater robustness.

[0103] Preferably, sub-step S141 includes: performing incoherent accumulation of the spatial spectrum on the frequency axis by the following formula to obtain the broadband spatial spectrum B of the target sound source accum (θ),

[0104]

[0105] Where B(f,θ) represents the spatial spectrum B(f,θ) of the target sound source.

[0106] Preferably, the diffraction theory correction model in step S143 includes:

[0107]

[0108] Where, Indicates the azimuth angle of the target sound source relative to the horizontal line array, Indicates the minimum angle value, c a represents the speed of sound at the horizontal linear array, c surb represents the speed of sound at the interface between the surface waveguide and the thermocline, and arccos represents the inverse cosine function.

[0109] Preferably, the horizontal linear array is deployed in a deep sea environment.

[0110] Simulation Example

[0111] Simulation parameters: The waveguide environment is a deep-sea acoustic waveguide with a surface waveguide at a depth of 4193m and a density of 1g / cm 3 The sound velocity of the lower sediment is 1600m / s and the density is 1.6g / cm 3 , the seabed attenuation coefficient is 0.1dB / λ, where λ represents the wavelength of the sound wave. The thickness of the surface waveguide is 60m, and the sound velocity gradient is 0.008s -1 The signal frequency band of the target sound source is 400-450Hz, the frequency sampling interval is 1Hz, and the distance between the target sound source and the horizontal array varies from 5km to 15km. The towing depth of the horizontal array varies from 50m to 200m, the array element aperture is 256m, and the array element spacing is 1m. The geometric positions of the target sound source and the horizontal array in the simulation are as follows: Figure 2 shown. Figure 3 It is a deep sea sound velocity profile diagram used in the simulation example of the present invention.

[0112] Step 1: Use a horizontal linear array with an array aperture of 256m and an array element spacing of 1m, and select the array element closest to the target sound source as the reference array element. Perform a time domain Fourier transform on the time domain sound pressure signal recorded by the horizontal linear array, and use formula (1) to transform the signal into the frequency domain. Cut the signal with a frequency band of 400-450Hz to obtain the frequency domain signal P(f,r l ),l=0,1,...,256.

[0113] Step 2: Convert the frequency domain signal P(f,r l ) is transformed into the angle domain to obtain the spatial spectrum B(f,θ). The search angle range is from 0° to 180°, with an angle interval of 0.5°. The result of the first attempt at a receiving depth of 100m, a distance of 8km, and a sound source azimuth of 0° is shown in Figure 4 middle. Figure 4 The simulation example of the present invention transforms the signal received on the horizontal line array into an energy distribution diagram in the frequency-angle domain through Fourier transform and beamforming, and obtains a broadband spatial spectrum by incoherent accumulation on the frequency axis. In the simulation experiment, under the conditions of a fixed sound source azimuth, sound source depth and distance, the signal received on the horizontal line array is transformed into an energy distribution diagram in the frequency-angle domain through Fourier transform and beamforming, and obtains a broadband spatial spectrum by incoherent accumulation on the frequency axis. According to Figure 4 Using ocean acoustics theory, we can see that there is only one spectral peak representing the surface waveguide leakage signal, while there are multiple spectral peaks representing the seabed reflection signal. This shows that the method of the present invention is more immune to multipath interference than existing technologies.

[0114] Step 3: Perform incoherent accumulation on the frequency axis of the obtained spatial spectrum B(f,θ) to obtain the broadband spatial spectrum B accum (θ), obtained from the broadband spatial spectrum B accum (θ) extracts the angle corresponding to the peak value and selects the minimum angle value as like Figure 4 The location marked by the red dotted line is shown.

[0115] Step 4: Correct the minimum angle value, where the sound velocity c at the horizontal array is a =1518m / s, surface waveguide boundary sound velocity c surb =1539m / s, get the estimated azimuth angle The difference between the azimuth angle and the actual sound source is small.

[0116] The azimuth estimation results under different sound source azimuths, sound source distances and receiving depths are recorded and compared with the azimuths estimated by the existing technology. The test results are displayed on Figure 5-Figure 7 Among them, Figure 5This is a comparison chart of the azimuth angle estimation results of the sound source under the conditions that the sound source is located at different azimuth angles in the simulation example of the present invention and the azimuth angle obtained by the existing horizontal line array direction finding algorithm in the acoustic shadow zone based on the seabed reflection signal (using the estimation result of a single seabed reflection signal). Figure 6 This is a comparison chart of the estimation results of the sound source azimuth angle of the simulation example of the present invention under the conditions that the sound source is located at different distances and the estimation results using a single seabed reflection signal. Figure 7 This is a comparison chart of the estimation results of the sound source azimuth angle of the simulation example of the present invention under the conditions of the array being located at different depths and the estimation results using a single seabed reflection signal. Figure 5-Figure 7 It can be seen that under different conditions, the method of the present invention has obvious advantages in estimation error compared with the existing method of estimating the azimuth of the sound source using the seabed reflection signal. This advantage is especially obvious when the target sound source is located near the end-fire direction of the horizontal linear array and at a close distance.

[0117] Figure 8 The energy distribution diagram of the real received signal in the real ocean environment is given by Fourier transform and beamforming into the frequency-angle domain. The spatial spectrum energy distribution of the real signal is obtained by repeating steps 1 and 2 using the towed array experimental data measured in the real ocean environment. Figure 8 It can be seen that the spectral peak representing the single seabed reflection signal located near 60° is more complex than the spectral peak representing the surface waveguide leakage signal on the far left. This is because the seabed reflection signal, after interacting with the complex seabed environment, has poor spatial coherence and high randomness due to effects such as scattering and absorption. This reduces the stability of existing technologies using seabed reflection signals in practical applications. However, the surface waveguide leakage signal does not interact with the complex seabed environment and therefore exhibits greater stability.

[0118] Example 3

[0119] Embodiment 3 of the present invention proposes a sound source direction finding device based on a horizontal line array, including a detection module, a conversion module, a first processing module, and a second processing module.

[0120] The detection module is configured to obtain the time domain sound pressure signal of the target sound source through the horizontal line array. The detection module can implement step S110. The specific implementation scheme thereof can refer to the relevant description of step S110 and will not be repeated here.

[0121] The conversion module is configured to convert the time domain sound pressure signal into the frequency domain to obtain the frequency domain sound pressure signal of the target sound source. The conversion module can implement step S120. The specific implementation scheme can refer to the relevant description of step S120 and will not be repeated here.

[0122] The module for obtaining the target sound source spatial spectrum is configured to perform beamforming on the frequency domain sound pressure signal to obtain the target sound source spatial spectrum. This module can implement step S130. The specific implementation scheme can refer to the relevant description of step S130 and will not be repeated here.

[0123] The azimuth acquisition module is configured to perform diffraction analysis on the spatial spectrum to obtain the azimuth of the target sound source relative to the horizontal array. This module can implement step S140. The specific implementation scheme can refer to the relevant description of step S140 and will not be repeated here.

[0124] Finally, it should be noted that the above embodiments are intended only to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the embodiments, it should be understood by those skilled in the art 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 are intended to be encompassed by the claims of the present invention.

Claims

1. A sound source direction finding method based on a horizontal linear array, comprising: The time domain sound pressure signal of the target sound source is obtained through the horizontal line array; Converting the time-domain sound pressure signal to the frequency domain to obtain a frequency-domain sound pressure signal of the target sound source; Performing beamforming on the frequency-domain sound pressure signal to obtain a spatial spectrum of the target sound source; Performing diffraction analysis on the spatial spectrum to obtain an azimuth angle of the target sound source relative to the horizontal linear array; The performing diffraction analysis on the spatial spectrum to obtain the azimuth angle of the target sound source relative to the horizontal linear array includes: performing incoherent accumulation on the spatial spectrum on the frequency axis to obtain a broadband spatial spectrum of the target sound source; Extracting the angle values ​​corresponding to the peaks of the broadband spatial spectrum and selecting the smallest angle value; Inputting the minimum angle value into a diffraction theory correction model to obtain the azimuth angle of the target sound source relative to the horizontal linear array; The diffraction theory correction model includes: in, represents the azimuth angle of the target sound source relative to the horizontal line array; Represents the minimum angle value; c a represents the speed of sound at the horizontal line array; c surb represents the speed of sound at the interface between the surface waveguide and the thermocline; arccos represents the inverse cosine function.

2. The sound source direction finding method based on horizontal linear array according to claim 1, characterized in that: The step of obtaining the time domain sound pressure signal of the target sound source through the horizontal line array includes: Signal acquisition is performed by using a horizontal linear array pre-deployed in an underwater environment where a surface waveguide exists and working in an acoustic shadow area to obtain a time-domain sound pressure signal from the target sound source on each array element.

3. The sound source direction finding method based on horizontal line array according to claim 1 or 2, characterized in that: The converting the time domain sound pressure signal into the frequency domain to obtain the frequency domain sound pressure signal of the target sound source includes: The time domain sound pressure signal is transformed into the frequency domain by the following formula: l ), P(f,r l )=∫p(t,r l )e -j2πft dt Where, p(t,r l ) represents the time domain sound pressure signal of the target sound source; f represents frequency; j is an imaginary unit; t represents time; r l Represents the distance between the lth array element and the target sound source, l = 0, 1, ..., L-1, where L is the number of array elements.

4. The sound source direction finding method based on horizontal line array according to claim 3, characterized in that: The performing beamforming on the frequency domain sound pressure signal to obtain the spatial spectrum of the target sound source includes: The frequency domain sound pressure signal P(f,r) of the target sound source on each array element is calculated by the following formula: l ) to perform beamforming to obtain the spatial spectrum B(f,θ) of the target sound source, Where c a represents the speed of sound at the array, d represents the horizontal linear array element spacing, and θ represents the search angle.

5. The sound source direction finding method based on horizontal linear array according to claim 1, characterized in that: The performing incoherent accumulation of the spatial spectrum on the frequency axis to obtain the broadband spatial spectrum of the target sound source includes: The broadband spatial spectrum B of the target sound source is obtained by incoherently integrating the spatial spectrum on the frequency axis using the following formula: accum (θ), Wherein, f represents frequency; B(f,θ) represents the spatial spectrum B(f,θ) of the target sound source.

6. The sound source direction finding method based on horizontal linear array according to claim 1, characterized in that: The horizontal line array is arranged in a deep-sea environment, and obtaining a time-domain sound pressure signal of a target sound source through the horizontal line array includes: Acquiring the seawater temperature at the initial position of the horizontal linear array; determining whether the horizontal array is in an isothermal layer according to the seawater temperature, and if not, adjusting the position of the horizontal array by dragging until the horizontal array is in the isothermal layer; identifying whether the horizontal linear array is operating in an acoustic shadow area; if not, adjusting the position of the horizontal linear array again by dragging until the horizontal linear array is operating in the acoustic shadow area, and outputting information indicating that the horizontal linear array is in a deep-sea environment with a surface waveguide and is operating in the acoustic shadow area; The time domain sound pressure signal of the target sound source is obtained respectively through each array element of the horizontal linear array.

7. The sound source direction finding method based on horizontal linear array according to claim 6, characterized in that: The distance between the target sound source and the horizontal linear array is 5 to 15 km, and the towing depth of the horizontal linear array is 50 to 200 m.

8. A sound source direction finding device based on a horizontal linear array, implemented based on the method according to any one of claims 1 to 7, characterized in that: The device comprises: The detection module is used to obtain the time domain sound pressure signal of the target sound source through a horizontal line array; a conversion module, configured to convert the time-domain sound pressure signal into the frequency domain to obtain the frequency-domain sound pressure signal of the target sound source; a target sound source spatial spectrum acquisition module, configured to perform beamforming on the frequency domain sound pressure signal to obtain the spatial spectrum of the target sound source; and The azimuth angle acquisition module is used to perform diffraction analysis on the spatial spectrum to obtain the azimuth angle of the target sound source relative to the horizontal linear array.

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