A Shallow Sea Small Target Detection System and Method Based on Underwater Acoustic and Ground Acoustic Information Fusion

Abstract

This invention discloses a shallow-sea small target detection system and method based on underwater acoustic and ground acoustic information fusion, comprising: an active sound source module located in the middle of the sea for actively exciting detection signals and providing excitation time, location information, and initial frequency band information; a seabed node module located on the seabed surface for actively detecting underwater acoustic velocity signals and seismic wave signals, and passively detecting the distance to shallow-sea small targets; and a signal processing module located on the coast for processing the signals from the seabed node module and the active sound source module, plotting multi-channel signals and mining information, and outputting underwater acoustic velocity information, seismic wave information, and location information of shallow-sea small targets; the seabed node module and the active sound source module are connected to the signal processing module via a wireless network. This invention combines active detection to obtain more accurate velocity information with a passive detection method based on underwater acoustic and ground acoustic fusion, achieving more accurate detection of shallow-sea small targets.

Description

Technical Field

[0001] This invention relates to the field of underwater acoustic and ground acoustic detection technology, and in particular to a shallow sea small target detection system and method based on underwater acoustic and ground acoustic information fusion. Background Technology

[0002] In shallow waters, total internal reflection and refraction occur during underwater acoustic propagation, and their complexity significantly impacts long-distance signal propagation and the detection of distant targets. Underwater detection methods are categorized into active and passive detection. Active detection utilizes actively generated and received signals to calculate and extract target information. Passive detection analyzes received signals to detect small targets in shallow waters.

[0003] With the advancement of technology, target stealth technology has become increasingly sophisticated, placing higher demands on hydrophones and other detection equipment for detecting single underwater acoustic targets, making target detection increasingly difficult. Target movement generates seismic waves on the seabed, which can be used for target detection. However, seismic waves experience signal attenuation during propagation and are easily affected by interference from non-target signals; therefore, detecting shallow-sea targets based solely on seismic wave signals is also extremely challenging. Currently, there is a lack of systems that fuse underwater and ground acoustic information for detection. Such systems can actively detect seabed parameters in their respective shallow-sea areas and also detect targets based on the difference between the direct velocity of underwater acoustic waves and the velocity of seismic waves, enabling long-distance detection of small targets in shallow waters.

[0004] Therefore, existing technologies still need improvement. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a shallow sea small target detection system and method based on underwater acoustic and ground acoustic information fusion, in order to solve the technical problem that existing underwater detection methods cannot achieve long-distance detection of shallow sea small targets.

[0006] The technical solution adopted by this invention to solve the technical problem is as follows:

[0007] In a first aspect, the present invention provides a shallow-sea small target detection system based on underwater acoustic and ground acoustic information fusion, comprising:

[0008] An active sound source module, located in the middle of the sea, is used to actively excite detection signals and provide excitation time and location information as well as initial frequency band information;

[0009] A seabed node module, located on the seabed surface, is used to actively detect underwater acoustic velocity signals and seismic wave signals, as well as to passively detect the distance to small targets in shallow waters.

[0010] The signal processing module, located on the coast, is used to process the signals from the seabed node module and the active sound source module, plot multi-channel signals and mine information, and output underwater acoustic velocity information, seismic wave information and the location information of the small target in the shallow sea area.

[0011] The seabed node module and the active sound source module are respectively connected to the signal processing module via a wireless network.

[0012] In one implementation, the seabed node module includes: N first seabed nodes;

[0013] N first seabed nodes are arranged at equal intervals in two mutually perpendicular directions on the seabed surface, forming an L-shaped array.

[0014] In one implementation, the seabed node module further includes: P second seabed nodes;

[0015] P second seabed nodes are randomly distributed on the seabed surface.

[0016] In one implementation, each seabed node in the seabed node module includes: a clock, a seismometer, a hydrophone, and a data acquisition system, wherein the clock, the seismometer, and the hydrophone are respectively connected to the data acquisition system.

[0017] In one implementation, the active sound source module is located at a right angle to the L-shaped array.

[0018] Secondly, the present invention provides a shallow-sea small target detection method based on underwater acoustic and ground acoustic information fusion, applied to the shallow-sea small target detection system based on underwater acoustic and ground acoustic information fusion as described in the first aspect, comprising:

[0019] The control seabed node module deploys a first seabed node and a second seabed node; wherein, the first seabed node is used to actively detect seabed parameters, and the second seabed node is used to passively detect small targets in shallow water.

[0020] The seabed parameters are obtained by actively detecting the excitation signal of the active acoustic source module at the first seabed node and calculating the underwater acoustic velocity parameters and seismic wave parameters based on the actively detected signal.

[0021] The existence of the shallow-sea small target is determined based on the signal passively detected by the second seabed node;

[0022] The location of the shallow sea target is calculated and output based on the passive detection data of the second seabed node, the underwater acoustic velocity parameters, and the seismic wave parameters.

[0023] In one implementation, the deployment of the first and second seabed nodes by the control seabed node module includes:

[0024] The first seabed node is deployed by controlling the seabed node modules to be arranged in an L-shaped, equally spaced manner.

[0025] The second seabed node is deployed in a random distribution manner by controlling the seabed node module.

[0026] In one implementation, the control seabed node module deploys the first seabed node and the second seabed node, followed by:

[0027] The active sound source module is controlled to actively excite the detection signal, and the excitation time and location information of the detection signal, as well as the initial frequency band information, are obtained.

[0028] In one implementation, the step of actively detecting the excitation signal of the active acoustic source module through the first seabed node and calculating the underwater acoustic velocity parameters and seismic wave parameters based on the actively detected signal includes:

[0029] The excitation signal of the active sound source module is actively detected by the first seabed node;

[0030] The signals detected by the first seabed node on the same straight line are combined into a time-distance curve, and the underwater acoustic velocity parameters and the seismic wave parameters are calculated based on the combined time-distance curve.

[0031] In one implementation, calculating the underwater acoustic velocity parameters and the seismic wave parameters based on the composed time-distance curve includes:

[0032] Select either the hydrophone channel or the horizontal channel, and calculate the underwater acoustic velocity parameters using the initial arrival signal;

[0033] Based on the characteristics of seismic wave propagation, the z-axis channel signal of the seismometer is selected, and the seismic wave parameters are calculated.

[0034] In one implementation, the step of selecting the seismometer z-axis channel signal based on the seismic wave propagation characteristics and calculating the seismic wave parameters includes:

[0035] Wavelet transform time-frequency analysis was performed on each first seabed node, and the point with the maximum energy in the excitation frequency band was selected on the time-frequency graph to obtain the corresponding time point;

[0036] Based on the distance information of each first seabed node, the corresponding time point, and the corresponding weight, linear fitting is performed to obtain the seismic wave parameters.

[0037] In one implementation, determining the existence of the shallow-sea target based on the signal passively detected by the second seabed node includes:

[0038] Acquire the hydrophone channel signal and the seismometer z-axis channel signal of the second seabed node;

[0039] Based on the hydrophone channel signal and the seismometer z-axis channel signal of the second seabed node, determine whether the seismometer z-axis channel signal is higher than the underwater acoustic signal;

[0040] If yes, then it is determined that the aforementioned small target in shallow water exists.

[0041] In one implementation, calculating and outputting the position of the shallow-sea target based on the passive detection data of the second seabed node, the underwater acoustic velocity parameters, and the seismic wave parameters includes:

[0042] Based on the hydrophone channel signal and the seismometer z-axis channel signal of each second seabed node, combined with the underwater acoustic velocity parameter and the seismic wave parameter, the distance between each second seabed node and the shallow sea target is calculated.

[0043] The location of the shallow sea target is calculated and output based on the distance obtained from each second seabed node.

[0044] The present invention, by employing the above technical solution, has the following effects:

[0045] This invention, by setting up an active sound source module, a seabed node module, and a signal processing module, can obtain underwater and ground acoustic velocity parameters in different directions through active detection, and periodically detect the impact of changes in update time on underwater and ground acoustic velocity. Simultaneously, randomly deployed nodes are used for passive detection. Based on the data from the active detection, underwater and ground acoustic information are fused to estimate the distance to small targets in shallow water. This invention combines active and passive detection, utilizing underwater and ground acoustic signals to detect the location of small targets in shallow water, thus improving detection accuracy. Attached Figure Description

[0046] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0047] Figure 1 This is a schematic diagram of the structure of a shallow sea small target detection system based on underwater acoustic and ground acoustic information fusion in one implementation of the present invention.

[0048] Figure 2 This is a schematic diagram of the structure of the seabed node in one implementation of the present invention.

[0049] Figure 3 This is a schematic diagram of multi-channel signal display of a seabed node in one implementation of the present invention.

[0050] Figure 4 This is a flowchart of a shallow sea small target detection method based on underwater acoustic and ground acoustic information fusion in one implementation of the present invention.

[0051] Figure 5 This is a schematic diagram of the signals in the X direction (a) and Y direction (b) of the seabed node when the excitation sound source is located in the middle of the seabed node linear array in one implementation of the present invention.

[0052] Figure 6 This is a time-frequency diagram of the signal in the X direction (a) and Y direction (b) of a 4km seabed node in one implementation of the present invention.

[0053] Figure 7 This is a schematic diagram of the data fitting results of the seabed node in the X direction (a) and Y direction (b) in one implementation of the present invention.

[0054] Figure 8 This is a parameter diagram of the underwater acoustic velocity (a) in the X direction and the ground acoustic velocity (b) in the Y direction of the seabed node in one implementation of the present invention.

[0055] Figure 9 This is a flowchart of a practical application scenario for detecting small targets in shallow waters in one implementation of the present invention.

[0056] In the picture:

[0057] 100. Active sound source module; 200. Seabed node module; 300. Signal processing module; 210. Clock; 220. Seismometer; 230. Hydrophone; 240. Acquisition system.

[0058] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0059] To make the objectives, technical solutions, and advantages of this invention clearer and more explicit, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0060] Exemplary System

[0061] With the development of technology, target stealth technology has become increasingly sophisticated, placing higher demands on detection equipment such as hydrophones for detecting single underwater targets, making target detection increasingly difficult. Target movement generates seismic waves on the seabed, which can be used for target detection. However, seismic waves experience signal attenuation during propagation and are easily affected by interference from non-target signals; therefore, detecting shallow-sea targets based on a single seismic wave signal is also extremely difficult.

[0062] To address the aforementioned technical issues, this embodiment provides a shallow-sea small target detection system based on underwater acoustic and ground acoustic information fusion. This system combines active and passive detection, utilizing underwater acoustic signals and ground acoustic signals to detect the location of small targets in shallow seas, thereby improving the accuracy of detection.

[0063] like Figure 1 As shown, this embodiment of the invention provides a shallow-sea small target detection system based on underwater acoustic and ground acoustic information fusion, comprising:

[0064] An active sound source module 100 is located in the middle of the sea and is used to actively excite detection signals, providing excitation time and location information as well as initial frequency band information.

[0065] The seabed node module 200 is located on the seabed surface and is used to actively detect underwater acoustic velocity signals and seismic wave signals, as well as to passively detect the distance of small targets in shallow seas.

[0066] The signal processing module 300 is located on the coast and is used to process the signals of the seabed node module 200 and the active sound source module 100, plot multi-channel signals and mine information, and output the underwater acoustic velocity information, seismic wave information and the location information of the small target in the shallow sea area.

[0067] The seabed node module 200 and the active sound source module 100 are respectively connected to the signal processing module 300 via a wireless network.

[0068] In this embodiment, the seabed node module 200 includes: N first seabed nodes;

[0069] N first seabed nodes are arranged at equal intervals in two mutually perpendicular directions on the seabed surface, forming an L-shaped array.

[0070] In this embodiment, the seabed node module 200 further includes: P second seabed nodes;

[0071] P second seabed nodes are randomly distributed on the seabed surface.

[0072] like Figure 2As shown, in this embodiment, each seabed node in the seabed node module 200 includes: a clock 210, a seismometer 220, a hydrophone 230, and a data acquisition system 240. The clock 210, the seismometer 220, and the hydrophone 230 are respectively connected to the data acquisition system 240.

[0073] In this embodiment, the active sound source module 100 is located at a right angle to the L-shaped array.

[0074] The system in this embodiment utilizes the high sensitivity of hydrophones to underwater acoustic information and the strong ability of triaxial seismometers to receive ground acoustic information (i.e., seismic waves). By combining the advantages of both, the system displays acoustic signals through multiple channels, providing workers with more information to explore.

[0075] The system in this embodiment can actively detect signals using an L-shaped seabed node array (i.e., equally spaced nodes arranged in two mutually perpendicular directions). The active acoustic source module generates signals, and the processing module estimates the underwater acoustic velocity and seismic wave velocity (i.e., seabed surface wave). The system actively updates its data monthly, measuring the underwater acoustic velocity and seismic wave velocity over time within the array's coverage area.

[0076] In this embodiment, the actively detected underwater acoustic velocity and seismic wave velocity can provide real-time underwater acoustic velocity and seismic wave velocity for the passive detection of small targets in shallow waters. Based on the passively detected underwater acoustic velocity and ground acoustic velocity and their arrival time difference, the distance to the small targets in shallow waters is estimated. This system integrates more accurate velocity information obtained through active detection with a passive detection method based on underwater and ground acoustic fusion, achieving more accurate detection of small targets in shallow waters.

[0077] In one practical application scenario of this embodiment, the seabed node module is responsible for deploying nodes to the seabed. A single node consists of main components such as a clock, seismometer, hydrophone, and acquisition system (e.g., Figure 2 (As shown). The active sound source module provides a sound source during active detection, offering excitation time and location information, initial signal frequency band information, etc., and is primarily used at sea. The signal processing module, located on shore, processes and summarizes the information from the nodes, plots multi-channel signals, and mines information (such as...). Figure 3 (As shown). The signal processing module mainly consists of two parts: underwater acoustic seismic wave velocity estimation and small target distance estimation.

[0078] During the deployment of seabed nodes, the nodes are arranged in an L-shape with equal spacing for active detection of seabed parameters, typically spaced 50m apart. Randomly deployed nodes are used for passive detection of small targets in shallow waters. The active detection sound source, located at a right angle to the L-shaped array, generates an excitation signal, which is received by the nodes. The node signals along a straight line form a time-distance curve (e.g., ...). Figure 5 As shown in the figure, underwater acoustic velocity estimation is performed.

[0079] like Figure 9 As shown, the implementation method of a shallow sea small target detection system based on underwater acoustic and ground acoustic information fusion includes the following steps:

[0080] Step S11: Arrange L-shaped equally spaced nodes;

[0081] Step S12: Excite signals using an active sound source and collect underwater acoustic signals and ground acoustic signals through L-shaped equally spaced nodes;

[0082] Step S13: Estimate underwater acoustic signals and ground acoustic signals;

[0083] Step S14: Deploy random nodes;

[0084] Step S15: Analyze the ground acoustics of the target using the seismometer and hydrophone signals from random nodes;

[0085] Step S16: Determine if a target exists; if yes, proceed to step S17; if no, proceed to step S15.

[0086] Step S17: Detect the time difference between the underwater acoustic signal and the ground acoustic signal detected by the random node, and estimate the target distance;

[0087] Step S18: Output the target location information.

[0088] This embodiment achieves the following technical effects through the above technical solution:

[0089] This embodiment, by setting up an active sound source module, a seabed node module, and a signal processing module, can obtain underwater and ground acoustic velocity parameters in different directions through active detection, and periodically detect the impact of changes in update time on underwater and ground acoustic velocity. Simultaneously, randomly deployed nodes are used for passive detection. Based on the data from the active detection, underwater and ground acoustic information are fused to estimate the distance to small targets in shallow water. This system combines active and passive detection, utilizing underwater and ground acoustic signals to detect the location of small targets in shallow water, thus improving detection accuracy.

[0090] Exemplary methods

[0091] like Figure 4 As shown, this embodiment of the invention provides a method for detecting small targets in shallow seas based on underwater acoustic and ground acoustic information fusion, including the following steps:

[0092] Step S100: Control the deployment of the first and second seabed nodes by the seabed node module.

[0093] In this embodiment, the shallow sea small target detection method based on underwater acoustic and ground acoustic information fusion is implemented through the aforementioned shallow sea small target detection system based on underwater acoustic and ground acoustic information fusion.

[0094] The system in this embodiment utilizes the high sensitivity of hydrophones to underwater acoustic information and the strong ability of triaxial seismometers to receive ground acoustic information (i.e., seismic waves). By combining the advantages of both, the system displays acoustic signals through multiple channels, providing workers with more information to explore.

[0095] The system in this embodiment can actively detect objects using an L-shaped seabed node array (i.e., equally spaced nodes arranged in two mutually perpendicular directions). An active acoustic source module generates signals, and a processing module estimates the underwater acoustic velocity and seismic wave velocity (i.e., seabed surface wave). The system actively updates its data monthly, measuring the underwater acoustic velocity and seismic wave velocity over time within the array's coverage area. The actively detected underwater acoustic velocity and seismic wave velocity provide real-time data for the passive detection of small targets in shallow waters. Based on the passively detected underwater acoustic velocity and ground acoustic velocity and their arrival time difference, the distance to the small targets in shallow waters is estimated. This system combines more accurate velocity information obtained through active detection with a passive detection method based on underwater and ground acoustic fusion, achieving more accurate detection of small targets in shallow waters.

[0096] In this embodiment, the seabed node module is responsible for deploying nodes to the seabed. A single node consists of key components such as a clock, seismometer, hydrophone, and data acquisition system (e.g.,...). Figure 2 (As shown). The active sound source module provides a sound source during active detection, offering excitation time and location information, initial signal frequency band information, etc., and is primarily used at sea. The signal processing module, located on shore, processes and summarizes the information from the nodes, plots multi-channel signals, and mines information (such as...). Figure 3 (As shown). The signal processing module mainly consists of two parts: underwater acoustic seismic wave velocity estimation and small target distance estimation.

[0097] Specifically, in one implementation of this embodiment, step S100 includes the following steps:

[0098] Step S110: Control the seabed node modules to deploy the first seabed node in an L-shaped, equally spaced arrangement;

[0099] Step S120: Control the seabed node module to deploy the second seabed node in a random distribution manner;

[0100] Step S130: Control the active sound source module to actively excite the detection signal, and acquire the excitation time and location information and initial frequency band information of the detection signal.

[0101] In this embodiment, the first seabed node (i.e., the node of the L-shaped array) is used to actively detect seabed parameters, and the second seabed node (i.e., the random node) is used to passively detect small targets in shallow water.

[0102] In this embodiment, the deployment of seabed nodes with different functions can be controlled by the signal processing module. During the deployment of seabed nodes by the control seabed node module, the first seabed node is deployed in an L-shaped, equally spaced manner to actively detect seabed parameters, with a typical spacing of 50m. The second seabed node is deployed in a randomly distributed manner to passively detect small targets in shallow water.

[0103] The active sound source is located at a right angle to the L-shaped array and can generate an excitation signal under the control of the signal processing module. The signal excited by this active sound source can be received by the first seabed node. The node signals received by the first seabed node along a straight line can form a time-distance curve (e.g., ...). Figure 5 As shown), it is used for underwater acoustic velocity estimation; for example, Figure 5 (a) shows the signal in the X direction of the seabed node when the excitation source is located in the middle of the seabed node linear array (i.e., L-shaped node array). Figure 5 (b) represents the signal in the Y direction of the seabed node.

[0104] When the active sound source module actively excites the detection signal, the signal processing module also acquires the excitation time and location information of the detection signal as well as the initial frequency band information. Based on this information, a time-distance curve can be formed, and then the underwater acoustic velocity can be estimated.

[0105] like Figure 4 As shown, in one implementation of this invention, the shallow sea small target detection method based on underwater acoustic and ground acoustic information fusion further includes the following steps:

[0106] Step S200: The seabed parameters are obtained by actively detecting the excitation signal of the active sound source module through the first seabed node, and calculating the underwater acoustic velocity parameters and seismic wave parameters based on the actively detected signal.

[0107] In this embodiment, the first seabed node is used to actively detect the excitation signal of the active acoustic source module, so that the signal processing module can periodically and actively update the data, and can measure the underwater acoustic velocity and seismic wave velocity of the array coverage area over time. The actively detected underwater acoustic velocity and seismic wave velocity can provide real-time underwater acoustic velocity and seismic wave velocity for passive detection of small targets in shallow seas.

[0108] Specifically, in one implementation of this embodiment, step S200 includes the following steps:

[0109] Step S210: Actively detect the excitation signal of the active sound source module through the first seabed node;

[0110] Step S220: The signals detected by the first seabed node on the same straight line are combined into a time-distance curve, and the underwater acoustic velocity parameter and the seismic wave parameter are calculated based on the combined time-distance curve.

[0111] like Figure 6 As shown, in this embodiment, the underwater acoustic velocity estimation generally selects the hydrophone channel or horizontal channel of the first seabed node to estimate the underwater acoustic velocity using the first arrival signal. Figure 6 In the middle (a), the underwater acoustic velocity signal is represented. The ground acoustic velocity is estimated by selecting the vertical vibration direction signal (i.e., the z-axis signal of the seismometer) of the first seabed node based on the characteristics of ground acoustic propagation.

[0112] Specifically, in one implementation of this embodiment, step S220 includes the following steps:

[0113] Step S221: Select the hydrophone channel or the horizontal channel, and calculate the underwater acoustic velocity parameters using the initial arrival signal;

[0114] Step S222: Select the seismometer z-axis channel signal according to the characteristics of seismic wave propagation, and calculate the seismic wave parameters.

[0115] In this embodiment, Figure 6 (b) shows the z-axis of the ground acoustic signal. The method for estimating the seismic wave parameters is as follows: The ground acoustic signal has the strongest energy in the z-axis channel of a single node. Since it is easily interfered with by other signals, wavelet transform time-frequency analysis is performed on a single node.

[0116] Specifically, in one implementation of this embodiment, step S222 includes the following steps:

[0117] Step S222a: Perform wavelet transform time-frequency analysis on each first seabed node, select the point with the maximum energy in the excitation frequency band on the time-frequency diagram, and obtain the corresponding time point;

[0118] Step S222b: Based on the distance information of each first seabed node, the corresponding time point, and the corresponding weight, perform linear fitting to obtain the seismic wave parameters.

[0119] In this embodiment, during the wavelet transform time-frequency analysis, selecting the point of maximum energy within the excitation frequency band on the time-frequency graph yields the corresponding time point t. i ,i=1,2,…N, that is, the arrival time of the ground sound at each node.

[0120] like Figure 7 As shown, Figure 7 (a) shows the data fitting results in the X direction for the L-shaped seabed node. Figure 7(b) shows the data fitting results in the Y direction for the L-shaped seabed node; the signal processing module then uses (d) as the basis for the data fitting. i Given i = 1, 2, ..., N (i.e., the distance information of each node), perform linear fitting.

[0121] Since the signal-to-noise ratio decreases with increasing distance, this embodiment introduces a weight ω during the fitting process. i The values ​​i = 1, 2, ..., N are used to avoid interference from long-distance signals and improve velocity estimation accuracy. Weights are allocated based on the seismic signal energy of each node. The slope of the fitted straight line is the reciprocal of the velocity, which allows for the estimation of the ground acoustic velocity. The underwater acoustic velocity is estimated using the same process. Periodic active detection can be performed on a monthly basis to estimate the underwater and ground acoustic velocities, such as... Figure 8 As shown, Figure 8 In the middle (a), the underwater acoustic velocity parameters in the X direction of the seabed node are shown. Figure 8 Parameters of the ground acoustic velocity in the Y direction (b).

[0122] like Figure 4 As shown, in one implementation of this invention, the shallow sea small target detection method based on underwater acoustic and ground acoustic information fusion further includes the following steps:

[0123] Step S300: Determine the existence of the shallow sea target based on the signal passively detected by the second seabed node.

[0124] In this embodiment, after actively detecting the underwater acoustic velocity parameters and seismic wave parameters, the existence of a small target in shallow water is then determined by passive detection, and the target's location is estimated if its existence is confirmed.

[0125] Specifically, in one implementation of this embodiment, step S300 includes the following steps:

[0126] Step S310: Obtain the hydrophone channel signal and the seismometer z-axis channel signal of the second seabed node;

[0127] Step S320: Based on the hydrophone channel signal and the seismometer z-axis channel signal of the second seabed node, determine whether the seismometer z-axis channel signal is higher than the underwater acoustic signal;

[0128] Step S330: If yes, then it is determined that the small target in the shallow sea exists.

[0129] In this embodiment, the presence of a target can be analyzed based on the signals of randomly deployed seabed nodes (i.e., the signals of the second seabed node). Specifically:

[0130] Based on the hydrophone channel signal and the seismometer z-axis channel signal in the second seabed node, if the ground acoustic energy of the z-axis channel signal is significantly higher than that of the underwater acoustic signal, it can be determined that a target exists.

[0131] In this embodiment, after determining the presence of the small shallow sea target, the arrival time t of the underwater sound can be found in the hydrophone channel time-frequency diagram of the second seabed node through time-frequency transformation. w Find the arrival time t of the ground sound in the z-axis channel time-frequency diagram. sch The underwater acoustic velocity (v) was measured by periodicity. w ground sound v sch (i.e., underwater acoustic velocity parameters and seismic wave parameters obtained through active detection);

[0132] achievable

[0133] Simplify to:

[0134] Based on the simplified formula above, the distance between each second seabed node and the shallow sea target can be calculated. Then, by processing all the calculated distances, the location of the target can be obtained.

[0135] like Figure 4 As shown, in one implementation of this invention, the shallow sea small target detection method based on underwater acoustic and ground acoustic information fusion further includes the following steps:

[0136] Step S400: Calculate and output the position of the shallow sea target based on the passive detection data of the second seabed node, the underwater acoustic velocity parameters, and the seismic wave parameters.

[0137] In this embodiment, the existence of small targets in shallow water can be determined by passive detection. Then, the underwater acoustic velocity parameters and seismic wave parameters detected by the second seabed node are combined with the signals detected by active detection in step S200 to calculate the underwater acoustic velocity parameters and seismic wave parameters. The distance between each second seabed node and the small target in shallow water can be calculated using the simplified formula described above.

[0138] Specifically, in one implementation of this embodiment, step S400 includes the following steps:

[0139] Step S410: Based on the hydrophone channel signal and the seismometer z-axis channel signal of each second seabed node, combined with the underwater acoustic velocity parameter and the seismic wave parameter, calculate the distance between each second seabed node and the shallow sea target.

[0140] Step S420: Calculate and output the position of the shallow sea target based on the distance solved for each second seabed node.

[0141] In this embodiment, the target distance r is calculated based on each random node. iLet i = 1, 2, ..., N, (N is the number of random nodes), and estimate the target location. Then, output the target location information at the information processing center.

[0142] like Figure 9 As shown, the implementation method of a shallow sea small target detection system based on underwater acoustic and ground acoustic information fusion includes the following steps:

[0143] Step S11: Arrange L-shaped equally spaced nodes;

[0144] Step S12: Excite signals using an active sound source and collect underwater acoustic signals and ground acoustic signals through L-shaped equally spaced nodes;

[0145] Step S13: Estimate underwater acoustic signals and ground acoustic signals;

[0146] Step S14: Deploy random nodes;

[0147] Step S15: Analyze the ground acoustics of the target using the seismometer and hydrophone signals from random nodes;

[0148] Step S16: Determine if a target exists; if yes, proceed to step S17; if no, proceed to step S15.

[0149] Step S17: Detect the time difference between the underwater acoustic signal and the ground acoustic signal detected by the random node, and estimate the target distance;

[0150] Step S18: Output the target location information.

[0151] This embodiment achieves the following technical effects through the above technical solution:

[0152] This embodiment, by setting up an active sound source module, a seabed node module, and a signal processing module, can obtain underwater and ground acoustic velocity parameters in different directions through active detection, and periodically detect the impact of changes in update time on underwater and ground acoustic velocity. Simultaneously, randomly deployed nodes are used for passive detection. Based on the data from the active detection, underwater and ground acoustic information are fused to estimate the distance to small targets in shallow water. This system combines active and passive detection, utilizing underwater and ground acoustic signals to detect the location of small targets in shallow water, thus improving detection accuracy.

[0153] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a non-volatile storage medium, and when executed, it can include the processes of the embodiments of the methods described above. Any references to memory, storage, databases, or other media used in the embodiments provided by this invention can include non-volatile and / or volatile memory.

[0154] In summary, this invention provides a shallow-sea small target detection system and method based on underwater acoustic and ground acoustic information fusion, comprising: an active sound source module located in the middle of the sea for actively exciting detection signals and providing excitation time, location information, and initial frequency band information; a seabed node module located on the seabed surface for actively detecting underwater acoustic velocity signals and seismic wave signals, and passively detecting the distance of shallow-sea small targets; and a signal processing module located on the coast for processing the signals from the seabed node module and the active sound source module, plotting multi-channel signals and mining information, and outputting underwater acoustic velocity information, seismic wave information, and location information of shallow-sea small targets; the seabed node module and the active sound source module are connected to the signal processing module via a wireless network. This invention combines active detection to obtain more accurate velocity information with a passive detection method based on underwater acoustic and ground acoustic fusion, achieving more accurate detection of shallow-sea small targets.

[0155] It should be understood that the application of the present invention is not limited to the examples above. Those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.

Claims

1. A shallow sea small target detection system based on underwater acoustic and seismic information fusion, characterized in that, The application relates to a shallow sea exploration system, which comprises the following modules: an active sound source module arranged in the sea and used for actively exciting a detection signal, providing excitation time and position information and initial frequency band information; a seabed node module arranged on a seabed surface and used for laying nodes on the seabed, actively detecting water sound velocity signals and seismic wave signals and passively detecting the distance of a shallow sea small target; a signal processing module arranged on a coast and used for processing signals of the seabed node module and the active sound source module, drawing multi-channel signals, mining information and outputting water sound velocity information of a shallow sea area, seismic wave information and position information of the shallow sea small target; the seabed node module and the active sound source module are connected with the signal processing module through wireless networks; the seabed node module comprises N first seabed nodes; the N first seabed nodes are arranged on the seabed surface in two mutually perpendicular directions in an equidistant manner to form an L-shaped array; the seabed node module further comprises P second seabed nodes; the P second seabed nodes are arranged on the seabed surface in a random distribution manner; the active sound source module is located at a right angle position of the L-shaped array.

2. The shallow sea small target detection system based on underwater acoustic geoacoustic information fusion according to claim 1, characterized in that, each seabed node in the seabed node module comprises a clock, a seismometer, a hydrophone and an acquisition system, and the clock, the seismometer and the hydrophone are connected with the acquisition system.

3. A shallow sea small target detection method based on underwater acoustic and ground acoustic information fusion, applied to the shallow sea small target detection system based on underwater acoustic and ground acoustic information fusion according to any one of claims 1-2, characterized in that, The application relates to a shallow sea exploration method, which comprises the following steps: controlling a seabed node module to lay first seabed nodes and second seabed nodes; wherein the first seabed nodes are used for actively detecting seawater seabed parameters, and the second seabed nodes are used for passively detecting shallow sea small targets; actively detecting excitation signals of an active sound source module through the first seabed nodes and calculating water sound velocity parameters and seismic wave parameters according to the actively detected signals to obtain the seawater seabed parameters; determining the existence of the shallow sea small targets according to passively detected signals of the second seabed nodes; calculating and outputting the positions of the shallow sea small targets according to passively detected data of the second seabed nodes, the water sound velocity parameters and the seismic wave parameters; the step of determining the existence of the shallow sea small targets according to the passively detected signals of the second seabed nodes comprises the following steps: acquiring hydrophone channel signals and seismometer z-axis channel signals of the second seabed nodes; judging whether the seismometer z-axis channel signals are higher than water sound signals according to the hydrophone channel signals and the seismometer z-axis channel signals of the second seabed nodes; if yes, it is determined that the shallow sea small targets exist; the step of calculating and outputting the positions of the shallow sea small targets according to the passively detected data of the second seabed nodes, the water sound velocity parameters and the seismic wave parameters comprises the following steps: calculating the distances between each second seabed node and the shallow sea small targets according to the hydrophone channel signals and the seismometer z-axis channel signals of each second seabed node in combination with the water sound velocity parameters and the seismic wave parameters; calculating and outputting the positions of the shallow sea small targets according to the distances solved by each second seabed node.

4. The shallow sea small target detection method based on underwater acoustic geoacoustic information fusion according to claim 3, characterized in that, the step of controlling the seabed node module to lay the first seabed nodes and the second seabed nodes comprises the following steps: The control module controls the first seabed node to be arranged in an L-shaped equidistant manner. The control module controls the second seabed node to be arranged in a random distribution manner.

5. The shallow sea small target detection method based on underwater acoustic geoacoustic information fusion according to claim 3, characterized in that, The control module controls the first seabed node and the second seabed node to be arranged, and then includes: The control module controls the active sound source module to actively excite a detection signal, and obtains excitation time and position information and initial frequency band information of the detection signal.

6. The shallow sea small target detection method based on underwater acoustic geoacoustic information fusion according to claim 3, characterized in that, The active sound source module actively detects the excitation signal of the active sound source module through the first seabed node, and calculates the sound speed parameter and the seismic wave parameter according to the actively detected signal, and includes: The active sound source module actively detects the excitation signal of the active sound source module through the first seabed node; The signals detected by the first seabed nodes on the same straight line are composed into a time-distance curve, and the sound speed parameter and the seismic wave parameter are calculated according to the composed time-distance curve.

7. The shallow sea small target detection method based on underwater acoustic geoacoustic information fusion according to claim 6, characterized in that, The sound speed parameter and the seismic wave parameter are calculated according to the composed time-distance curve, and include: The hydrophone channel or the horizontal channel is selected, and the sound speed parameter is calculated by using the first arrival signal; According to the seismic wave propagation characteristics, the z-axis channel signal of the seismometer is selected, and the seismic wave parameter is calculated.

8. The shallow sea small target detection method based on underwater acoustic geoacoustic information fusion according to claim 7, characterized in that, According to the seismic wave propagation characteristics, the z-axis channel signal of the seismometer is selected, and the seismic wave parameter is calculated. The wavelet transform time-frequency analysis is performed on each first seabed node, the energy maximum point in the excitation frequency band is selected on the time-frequency graph, and the corresponding time point is obtained; According to the distance information, the corresponding time point and the corresponding weight of each first seabed node, linear fitting is performed to obtain the seismic wave parameter.

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