Sound source direction finding method and device based on horizontal line array

Abstract

The invention discloses a sound source direction finding method and device based on a horizontal line array. The method comprises the following steps: obtaining a time domain sound pressure signal of a target sound source through a horizontal line array; converting the time domain sound pressure signal into a frequency domain to obtain a frequency domain sound pressure signal of the target sound source; performing beam forming through 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 an azimuth angle of the target sound source relative to the horizontal line array. According to the method, distance information of the target sound source is not needed, surface waveguide leakage signals are utilized, the azimuth angle of the target sound source is accurately estimated through diffraction analysis, good direction finding stability and accuracy are achieved, and the method is particularly suitable for the deep sea environment with surface waveguides.

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, so the towed horizontal array often needs to work in the sound shadow zone.

[0003] The existing horizontal line array direction finding method in the acoustic shadow zone based on the seabed reflection signal is affected by the azimuth-grazing angle coupling effect. In the absence of target distance information, it can only make a biased estimate of the target sound source azimuth. Moreover, since the seabed reflection signals that interact with the seabed at different times have different grazing angles, this multipath effect will further complicate the estimation of the target sound source azimuth based on the seabed reflection signal. In addition, the seabed reflection signal is often affected by complex seabed environmental conditions, which makes the horizontal line array direction finding algorithm based on the acoustic shadow zone of the seabed reflection signal show obvious instability. Summary of the invention

[0004] The purpose of the present invention is to overcome the defect that the prior art cannot accurately estimate the direction of the target sound source, and proposes a sound source direction finding method based on a horizontal line array. The present invention also discloses a sound source direction finding device based on a horizontal line array.

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

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

[0007] Transforming the time domain sound pressure signal into the frequency domain to obtain the frequency domain sound pressure signal of the target sound source;

[0008] Performing beamforming by using 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 line array.

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

[0011] Signal collection 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 of 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] Incoherently accumulating 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 the diffraction theory correction model to obtain the azimuth angle of the target sound source relative to the horizontal line array.

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

[0017]

[0018] In the formula, 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, and arccos represents the inverse cosine function.

[0019] As an improvement of the above method, the step of 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 ) -j2πft dt

[0022] In the formula, 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.

[0023] As an improvement of the above method, the step of 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] In the formula, c a represents the sound velocity at the array, d represents the horizontal linear array element spacing, and θ represents the search angle.

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

[0028] The spatial spectrum is incoherently accumulated on the frequency axis by the following formula to obtain the broadband spatial spectrum B of the target sound source: 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 of the above method, the horizontal line array is arranged in a deep sea environment, and the time domain sound pressure signal of the target sound source is obtained through the horizontal line array, including:

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

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

[0034] Identify whether the horizontal linear array is working in the acoustic shadow area, and if not, adjust the position of the horizontal linear array again by dragging until the horizontal linear array is working in the acoustic shadow area, and output information that the horizontal linear array is in a deep sea environment with a surface waveguide and is working 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 line array.

[0036] As an improvement of the above method, the distance between the target sound source and the horizontal line array is 5 to 15 km, and the dragging depth of the horizontal line 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] A detection module, used to obtain a time-domain sound pressure signal of a target sound source through a horizontal line array;

[0039] A conversion module, used to transform 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 module for obtaining a target sound source spatial spectrum is used to perform beamforming through the frequency domain sound pressure signal to obtain a spatial spectrum of the target sound source;

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

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

[0043] 1. Using the diffraction analysis theory, the passive sound source direction finding is performed through a horizontal line array. This method does not require the distance information of the target sound source, but can accurately estimate the azimuth of the target sound source.

[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 the deep sea environment with surface waveguide 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 the seabed reflection signal, 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 Embodiment 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 5It is a comparison diagram of the estimation results of the azimuth of the sound source under the condition that the sound source is located at different azimuths in the simulation example of the present invention and the azimuth obtained by the existing horizontal line array direction finding algorithm in the acoustic shadow area based on the seabed reflection signal (using the estimation result of a single seabed reflection signal);

[0052] Figure 6 It is a comparison diagram of the estimation result of the azimuth angle of the sound source under the condition that the sound source is located at different distances in the simulation example of the present invention and the estimation result using a single seabed reflection signal;

[0053] Figure 7 It is a comparison diagram of the estimation results of the azimuth of the sound source in 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 It 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 the 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 line 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] In order to ensure accurate estimation of the target sound source direction, a universal sound source direction finding method based on horizontal linear array is proposed, which uses the surface waveguide leakage signal to orient the target sound source. Since the surface waveguide leakage signal is more stable in terms of propagation angle characteristics, this method has stronger robustness.

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

[0063] Ocean surface duct mode: It is a special type of atmospheric duct that occurs over the ocean. This duct mode usually occurs in a relatively stable atmospheric environment, where there is a stable inversion layer in the bottom atmosphere and the atmospheric humidity decreases with height. 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 will diffract on the ocean surface below the surface waveguide, thus forming a surface waveguide leakage signal. According to research, the surface waveguide leakage signal is more stable in terms of propagation angle characteristics, so it has stronger robustness.

[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 on the upper layer and the thick cold water layer on the lower layer.

[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. Obtaining a time domain sound pressure signal of the target sound source through a 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 by using the frequency domain sound pressure signal to obtain a 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] For 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 can generally adopt the Fourier transform method.

[0076] For 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 the diffraction analysis of the spatial spectrum. In addition to the method of the following embodiment 2, a neural network or a vector machine can also be used to extract the diffraction characteristics of the spatial spectrum and input them into the neural network or the 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] Through the sequential execution of 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 the distance information of the target sound source, and does not need to consider the interference caused by the multipath effect, and has stability.

[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 line 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 collection 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 a target sound source on each array element.

[0084] It should be noted that the method for determining the presence of surface waveguides is the isothermal layer, that is, the area where the seawater temperature remains constant. Since the surface waveguide leakage signal is more stable in terms of propagation angle characteristics, the depth of the underwater environment is not limited, 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. judging whether the horizontal line array is in the isothermal layer according to the seawater temperature, and if not, adjusting the position of the horizontal line array by dragging until the horizontal line array is in the isothermal layer;

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

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

[0090] Preferably, the distance from the target sound source to the horizontal array is 5 to 15 km, and the drag depth of the horizontal array is 50 to 200 m. In addition, the element aperture of the horizontal array is not limited, and the element spacing can be set to half the wavelength of the frequency of the target sound source 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 comprises: 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 ) -j2πft dt (1)

[0094] In the formula, 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] In the formula, c a represents the sound velocity 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. Incoherently accumulate 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 values ​​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 line array.

[0102] It should be noted that step S140 to step S143 constitute the best detection scheme for the azimuth angle. The surface waveguide leakage signal is more stable in terms of propagation angle characteristics, and therefore has stronger 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 of step S143 includes:

[0107]

[0108] In the formula, Indicates the azimuth 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.

[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 layer 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 surface waveguide thickness 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 from the target sound source to the horizontal array changes from 5km to 15km. The towing depth of the horizontal array changes from 50m to 200m, the array element aperture is 256m, and the array element interval is 1m. The geometric positions of the target sound source and the horizontal array in the simulation are shown in Figure 2 shown. Figure 3 It is a deep sea sound speed 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. Use formula (1) to transform the signal to the frequency domain, intercept the signal with a frequency band of 400-450Hz, and 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°, and the angle interval is 0.5°. The result 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 analysis, it can be seen that there is only one spectrum peak representing the surface waveguide leakage signal, while there are multiple spectrum peaks representing the seabed reflection signal. This shows that the method of the present invention has the advantage of not being affected by multipath interference compared to the prior art.

[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), from the obtained broadband spatial spectrum B accum (θ) extracts the angle corresponding to the peak value and selects the smallest 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 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 5It is a comparison chart of the estimation results of the azimuth of the sound source under the condition that the sound source is located at different azimuths in the simulation example of the present invention and the azimuth 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 It is a comparison diagram of the estimation results of the azimuth angle of the sound source under the condition that the sound source is located at different distances in the simulation example of the present invention and the estimation result 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 when the array is 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, especially when the target sound source is located near the end-fire direction of the horizontal linear array and the distance is close, this advantage is more obvious.

[0117] Figure 8 The energy distribution diagram of the real received signal in the real ocean environment is given by transforming it into the frequency-angle domain through Fourier transform and beamforming. 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 compared with the spectrum peak representing the surface waveguide leakage signal on the far left, the spectrum peak representing a seabed reflection signal located near 60° is more complex. This is because after the seabed reflection signal interacts with the complex seabed environment, due to effects such as scattering and absorption, the seabed reflection signal has poor spatial coherence and high randomness, which reduces the stability of the existing technology using the seabed reflection signal in practical applications. The surface waveguide leakage signal does not interact with the complex seabed environment, and therefore exhibits stronger 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, and its specific implementation scheme can refer to the relevant description of step S110, which will not be repeated here.

[0121] The conversion module is configured to transform 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, and its specific implementation scheme can refer to the relevant description of step S120, which will not be repeated here.

[0122] The module for obtaining the spatial spectrum of the target sound source is configured to perform beamforming through the frequency domain sound pressure signal to obtain the spatial spectrum of the target sound source. This module can implement step S130, and its specific implementation scheme can refer to the relevant description of step S130, which 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 line array. This module can implement step S140, and its specific implementation scheme can refer to the relevant description of step S140, which will not be repeated here.

[0124] 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 the present invention. Although the present invention is described in detail with reference to the embodiments, it should be understood by those skilled in the art that any modification or equivalent replacement of the technical solutions of the present invention does not depart from the spirit and scope of the technical solutions of the present invention and should be included in the scope of 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; Transforming the time domain sound pressure signal into the frequency domain to obtain the frequency domain sound pressure signal of the target sound source; Performing beamforming by using the frequency domain sound pressure signal to obtain a spatial spectrum of the target sound source; A diffraction analysis is performed on the spatial spectrum to obtain the azimuth angle of the target sound source relative to the horizontal line array.

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 collection 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 linear array according to claim 1, characterized in that: 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: Incoherently accumulating 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; The minimum angle value is input into the diffraction theory correction model to obtain the azimuth angle of the target sound source relative to the horizontal line array.

4. The sound source direction finding method based on horizontal linear array according to claim 3, characterized in that: The diffraction theory correction model includes: in, Indicates 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.

5. The sound source direction finding method based on horizontal linear array according to any one of claims 1 to 4, characterized in that: The step of 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: 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 In the formula, 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, L is the number of array elements.

6. The sound source direction finding method based on horizontal line array according to claim 5, characterized in that: The performing beamforming by 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, In the formula, c a represents the sound velocity at the array, d represents the horizontal linear array element spacing, and θ represents the search angle.

7. The sound source direction finding method based on horizontal line array according to claim 3, characterized in that: The step of performing incoherent accumulation of the spatial spectrum on the frequency axis to obtain a broadband spatial spectrum of the target sound source includes: The spatial spectrum is incoherently accumulated on the frequency axis by the following formula to obtain the broadband spatial spectrum B of the target sound source: accum (θ), Wherein, f represents frequency; B(f,θ) represents the spatial spectrum B(f,θ) of the target sound source.

8. 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 the time domain sound pressure signal of the target sound source is obtained through the horizontal line array, including: Acquiring the seawater temperature at the initial position of the horizontal line array; determining whether the horizontal line array is in an isothermal layer according to the seawater temperature, and if not, adjusting the position of the horizontal line array by dragging until the horizontal line array is in the isothermal layer; Identify whether the horizontal linear array is working in the acoustic shadow area, and if not, adjust the position of the horizontal linear array again by dragging until the horizontal linear array is working in the acoustic shadow area, and output information that the horizontal linear array is in a deep sea environment with a surface waveguide and is working 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 line array.

9. The sound source direction finding method based on horizontal line array according to claim 8, characterized in that: The distance from the target sound source to the horizontal line array is 5 to 15 km, and the dragging depth of the horizontal line array is 50 to 200 m.

10. A sound source direction finding device based on a horizontal linear array, implemented based on any method described in claims 1-9, characterized in that: The device comprises: A detection module, used to obtain a time-domain sound pressure signal of a target sound source through a horizontal line array; A conversion module, used to transform the time domain sound pressure signal into the frequency domain to obtain the frequency domain sound pressure signal of the target sound source; A module for obtaining a target sound source spatial spectrum is used to perform beamforming through the frequency domain sound pressure signal to obtain a spatial spectrum of the target sound source; and The azimuth acquisition module is used to perform diffraction analysis on the spatial spectrum to obtain the azimuth of the target sound source relative to the horizontal line array.

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