A method and system for estimating the depth of a deep-sea sound source using a single hydrophone based on two interference time intervals

Abstract

The present application provides a method and system for estimating the depth of a deep-sea sound source based on two interference time intervals. The method includes the following steps: First, in the deep-sea environment, a single hydrophone at a depth near the sea surface is used for continuous observation and the depth where the receiving array element is located is recorded. Second, for the target radiated noise signal, time-frequency analysis is performed on the signal collected by the hydrophone, and two interference time intervals are extracted according to the narrowband interference structure presented by the LOFAR spectrum, or for the target active pulse sound signal, two interference time intervals are extracted through the change curves of two types of multi-path time delays with time. Then, the ratio of the two interference time intervals is calculated to initially estimate the depth of the sound source. Finally, the depth estimation result of the sound source is corrected using the distance information of the interference cancellation point. This method is applicable to broadband sound sources and narrowband sound sources. The advantage of the present application is that the depth of a narrowband sound source can be estimated using the beam signal output by a single hydrophone or a single horizontal array.

Description

Technical Field

[0001] This application belongs to the technical field of underwater acoustic positioning, and specifically relates to a method and system for estimating the depth of a deep-sea sound source using a single hydrophone based on two interference time intervals. Background Art

[0002] Passive sonar detection is the main technical approach for underwater mobile platforms such as submarines and unmanned underwater vehicles (UUVs) to conduct stealth detection. The method for estimating the depth of a deep-sea sound source can be applied to scenarios such as underwater mobile platforms against surface / underwater ships, and is an important step for underwater mobile platforms to achieve deep-sea target positioning. In addition, for passive sonar systems, the single-hydrophone positioning method can be used not only for single elements but also for equivalent single elements formed by array signal processing, and has good applicability for various array installation platforms.

[0003] Wu Junnan et al. studied the relationship between the two interference periods in the frequency domain and the multi-path time delay difference of the first bottom reflection in the deep-sea bottom reflection working mode, and used a horizontal array to achieve the distance estimation of surface targets (Reference: Wu Junnan, Zhou Shihong, Zhang Yan. Passive ranging of surface sound sources using the characteristics of deep-sea bottom reflection sound fields [J]. Science China: Physics, Mechanics & Astronomy, 2016, 46(9): 7). Weng Jinbao and Yang Yanming proposed to use the variation relationship of the frequency-dimensional interference periods corresponding to two interference fringes with the sound source depth, receiving depth, and sound source distance to achieve the joint estimation of the distance-depth of broadband sound sources. (Reference: Weng Jinbao, Yang Yanming. A method for passive ranging and depth measurement of shadow-zone sound sources using a single hydrophone in the deep sea [J]. Acta Acustica, 2018, 43(06): 905-914.).

[0004] Similar to the frequency dimension, the sound intensity at a single frequency point also shows regular changes with the change of the sound source distance, that is, the narrowband sound intensity interference structure. In fact, the law of the narrowband sound intensity changing with distance also has a certain corresponding relationship with the changes of the sound source depth, receiving depth, and sound source distance. This change characteristic can also be used for underwater sound source positioning. Wei Runyu et al. observed the line spectrum interference structure in the direct sound area through a fixed vertical array on the seabed, realized the separation of the multi-path arrival elevation angles, and then solved the sound source depth. (Reference: WEI R, MAX, Li X. Depth estimation of deep water moving source based on ray separation [J] Applied Acoustics, 2021, 174: 107739). However, the existing methods are difficult to be applicable to underwater narrowband sound sources in the shadow zone.

[0005] In the existing methods for estimating the sound source depth, usually in the shadow zone, the broadband radiation noise of underwater low-noise targets such as submarines and UUVs is easily submerged by the background noise, resulting in the limitation or failure of broadband positioning methods. Summary of the Invention

[0006] The purpose of the present application is to overcome the defects of existing sound source depth estimation methods. Usually in the sound shadow area, the broadband radiation noise of underwater low-noise targets such as submarines and UUVs is easily submerged by background noise, resulting in the limitation or failure of broadband positioning methods.

[0007] To achieve the above purpose, the present application proposes a single hydrophone deep-sea sound source depth estimation method based on two interference time intervals, including:

[0008] Step S1: In the deep-sea environment, use a near-surface depth hydrophone for continuous observation and record the depth where the hydrophone is located;

[0009] Step S2: Use a narrowband interference structure to extract two interference time intervals, or use the variation curves of two types of multi-path time delays with time to extract two interference time intervals;

[0010] Step S3: Calculate the ratio of the two interference time intervals to initially measure the sound source depth;

[0011] Step S4: Use the distance information of the interference cancellation point to correct the initial measurement result of the sound source depth.

[0012] As an improvement of the above method, the near-surface depth hydrophone is located shallower than one-fifth of the sea depth.

[0013] As an improvement of the above method, the use of a narrowband interference structure to extract two interference time intervals includes:

[0014] Perform time-frequency analysis on the received signal to obtain the LOFAR diagram of the received signal; select the narrowband interference structure at the preferred frequency point from the LOFAR diagram of the received signal as the observation object and distinguish two types of narrowband interference structures;

[0015] Extract two narrowband interference cancellation points from the two types of narrowband interference structures respectively, and record the moments when the interference cancellation points appear;

[0016] Perform sound source ranging on the target to obtain the target distance information, and record the sound source distance corresponding to the moment when the interference cancellation point appears;

[0017] Calculate the ratio of the two interference time intervals through the time when the interference cancellation point appears.

[0018] As an improvement of the above method, the preferred frequency point is the maximum frequency under the condition of ensuring clear interference structure.

[0019] As an improvement of the above method, the use of the variation curves of two types of multi-path time delays with time to extract two interference time intervals includes:

[0020] Extract two types of multi-path time delay differences from the pulse signals received by the hydrophone, and plot the curves of the time delay differences changing with time;

[0021] Calculate the arrival time delay differences between the sea surface-seabed reflection path and the seabed reflection path, and between the seabed-sea surface reflection path and the seabed reflection path, and perform interpolation fitting on the calculation results;

[0022] Calculate the interference cancellation points using the curves of the time delay differences changing with time, obtain two types of interference time intervals, and acquire the source distances corresponding to the interference cancellation points.

[0023] As an improvement to the above method, the initial measurement of the source depth by calculating the ratio of the two interference time intervals includes:

[0024]

[0025] where z s represents the initially measured source depth; Δr1 and Δr2 respectively represent the two interference distance intervals corresponding to the two types of narrowband interference structures; z r represents the receiver depth.

[0026] As an improvement to the above method, the correction of the initially measured result of the source depth using the distance information of the interference cancellation points includes:

[0027]

[0028] where T1 and T2 respectively represent the time intervals between the appearances of two adjacent interference cancellation points of the two types of interference structures; α represents the correction coefficient:

[0029]

[0030] where r represents the source distance.

[0031] This application also provides a single hydrophone deep-sea source depth estimation system based on two interference time intervals, which is implemented based on the above method. The system includes:

[0032] An extraction module for two interference time intervals, which is used to extract two interference time intervals using narrowband interference structures, or to extract two interference time intervals using the curves of the two types of multi-path time delay differences changing with time;

[0033] An initial measurement module for the source depth, which is used to calculate the initial measurement of the source depth by calculating the ratio of the two interference time intervals;

[0034] A module for correcting the initially measured result, which is used to correct the initially measured result of the source depth using the distance information of the interference cancellation points.

[0035] Compared with the prior art, the advantages of this application are:

[0036] 1. It can be achieved by using the beam signals output by a single hydrophone or a single horizontal array.

[0037] 2. The spectral feature information of the sound source is not required.

[0038] 3. The prior information of accurate ocean environmental parameters is not required, avoiding the cumbersome copy field calculation process of traditional sound field matching positioning.

[0039] 4. It is applicable to both broadband and narrowband sound sources. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 The figure shows a schematic diagram of the sound ray propagation path in the first shadow zone of the deep sea;

[0041] Figure 2 The figure shows a schematic diagram of the virtual source model in the deep sea under the primary bottom reflection propagation mode;

[0042] Figure 3 The figure shows the distance - amplitude diagram under the condition of upward transmission and downward reception (z s = 50m, z r = 300m);

[0043] Figure 4 The figure shows the distance - amplitude diagram under the condition of downward transmission and upward reception (z s = 300m, z r = 50m);

[0044] Figure 5 The figure shows the distance - amplitude diagram under the condition of equal depth of transmission and reception (z s = 300m, z r = 300m);

[0045] Figure 6 The figure shows the sound velocity profile used in Embodiment 1 of the present application;

[0046] Figure 7 The figure shows the method flow chart of Embodiment 1 of the present application;

[0047] Figure 8 The figure shows the LOFAR diagram of the signal received by the hydrophone in Embodiment 1 of the present application;

[0048] Figure 9 The figure shows the narrowband interference structure diagram at the 200Hz frequency point in Embodiment 1 of the present application;

[0049] Figure 10 The figure shows the sound source depth estimation result and correction result diagram in Embodiment 1 of the present application;

[0050] Figure 11 The figure shows the sound velocity profile used in Embodiment 2 of the present application;

[0051] Figure 12 The following is the flowchart of the method according to Embodiment 2 of the present application;

[0052] Figure 13(a) shows the schematic diagram of the first type of time delay difference in the calculation results of two types of time delay differences and the fitting results (f = 200 Hz) in the data processing according to Embodiment 2 of the present application;

[0053] Figure 13(b) shows the schematic diagram of the second type of time delay difference in the calculation results of two types of time delay differences and the fitting results (f = 200 Hz) in the data processing according to Embodiment 2 of the present application;

[0054] Figure 14 The following shows the calculation results of two types of cycle numbers and two types of interference cancellation points in Embodiment 2 of the present application;

[0055] Figure 15 The following shows the sound source depth estimation result in Embodiment 2 of the present application;

[0056] Figure 16 The following is the flowchart of the single hydrophone deep-sea sound source depth estimation method using two interference time intervals. Detailed implementation manners

[0057] The technical solution of the present application will be described in detail below with reference to the accompanying drawings.

[0058] The present invention aims at the problem of underwater sound source depth estimation in the deep-sea acoustic shadow zone, and proposes a single hydrophone deep-sea sound source depth estimation method using two interference time intervals, which is applicable to broadband sound sources and narrowband sound sources. In the present application, the deep sea refers to a marine environment with a depth greater than 1000 m. As Figure 16 shown, the implementation steps of the method include:

[0059] Step 1: In the deep-sea environment, place the hydrophone near the sea surface (shallower than one-fifth of the sea depth), and continuously conduct observations; at the same time, measure the deployment depth of the hydrophone.

[0060] Step 2: Perform time-frequency analysis on the received signals of the array element. According to the narrowband interference structure presented by the LOFAR spectrum, extract two interference time intervals corresponding to the two types of narrowband interference structures, or for the target active pulse sound signal, through methods such as arrival time delay estimation and matched filtering, and extract and calculate two interference time intervals using the change curves of two types of multi-path time delay differences with time;

[0061] Step 3: Calculate the ratio of the two interference time intervals to initially estimate the sound source depth;

[0062] Step 4: Use the distance information of the interference cancellation points to correct the estimation result (fine measurement).

[0063] As Figure 1Shown is a typical deep - sea Munk sound - speed profile. According to ray - acoustics theory, the acoustic energy in the first deep - sea shadow zone is mainly contributed by the primary bottom - reflected ray, and there are four propagation paths in total, namely the bottom - reflection path (BR), the surface - bottom - reflection path (SBR), the bottom - surface - reflection path (BSR), and the surface - bottom - surface - reflection path (SBSR). For the convenience of subsequent research, the rays of different propagation paths are numbered. The serial numbers 1, 2, 3, and 4 represent the four rays BR, SBR, BSR, and SBSR respectively. The schematic diagrams of the propagation paths of the four rays are as shown in Figure 1 as follows.

[0064] In the sound field excited by a sound source at a depth of zs, the sound pressure of frequency f received by a receiver located at the receiving point (r, z r ) can be expressed as the coherent superposition of the four sound rays with different propagation paths shown in Figure 1 as follows:

[0065]

[0066] where r represents the source distance (the horizontal distance between the receiver and the source), z r represents the receiver depth, k i (i = 1, 2, 3, 4) are the number of surface reflections of the four rays (the values are 0, 1, 1, and 2 respectively), and t i is the propagation time of the sound signals corresponding to the four rays.

[0067] When both the sound source and the receiver are near the sea surface, the sound intensity at the receiving point (r, z r ) satisfies:

[0068]

[0069] where Δt1 = t2 - t1 is the arrival - time delay difference between the SBR ray and the BR ray, and Δt2 = t3 - t1 is the arrival - time delay difference between the BSR ray and the BR ray. Here, Δt1 is denoted as the first - type time - delay difference, and Δt2 is denoted as the second - type time - delay difference. In fact, Δt1 and Δt2 are functions of the source depth z s , the receiving depth z r and the source distance r.

[0070] Next, according to the virtual - source theory, the analytical expressions of the first - type time - delay difference Δt1 and the second - type time - delay difference Δt2 in the deep - sea bottom - reflection sound zone are given. As shown in Figure 2 is the schematic diagram of the virtual - source model in the deep - sea bottom - reflection propagation mode. In the figure, the source depth is z s , the receiving depth is z r , H is the sea depth, c is the equivalent sound speed, R is the horizontal distance of the source, and They respectively represent the slant ranges between the sound source and the receiver, the sound source and the mirror receiver, the mirror sound source and the receiver, and the mirror sound source and the mirror receiver. Under the condition that the sound speed profile is simplified to the equal sound speed approximation, according to the geometric relationship, we can obtain:

[0071]

[0072] Meanwhile, the two types of time delay differences can be respectively expressed as:

[0073]

[0074] In the deep - sea long - range bottom - reflection propagation mode, when (2H + z s + z r ) / R < 1, it can be proved that Δt1 and Δt2 can be simplified into the following forms

[0075]

[0076] When both the sound source and the receiver are located at the sea surface, 2z s << 4H, 2z r << 4H, Equation (5) can be further simplified to

[0077]

[0078] It can be seen from Equation (6) that in the deep - sea bottom - reflection propagation mode, when both the sound source and the receiver are located at the sea surface and the distance of the sound source is fixed, Δt1 is approximately only related to the depth of the sound source, and Δt2 is approximately only related to the depth of the receiver; when the depths of the sound source and the receiver are fixed, the two types of time delay differences are approximately inversely proportional to the distance of the sound source.

[0079] The acoustic - field interference structure means that in the acoustic field, sound waves propagate in the form of normal modes, and different - order normal modes interfere with each other, making the acoustic field have a stable frequency - space interference structure, which is manifested as bright and dark fringes appearing on the frequency - distance diagram of sound intensity. And there are two types of acoustic - field interference structures in the shadow - zone acoustic field, that is, there are two types of bright and dark fringes. When both the sound source and the receiver are located at the sea surface, four primary bottom - reflection sound rays interfere and superpose, forming two types of interference structures in the frequency - distance dimension, and two types of bright and dark fringes appear on the frequency - distance diagram of sound intensity. The horizontal distance between two adjacent interference cancellation (constructive interference) points of the same type of interference structure at a certain frequency is called the interference distance interval of this type of narrow - band interference structure. The two types of narrow - band interference structures correspond to two interference distance intervals Δr1 and Δr2.

[0080] According to the definition of the interference distance interval, for the two types of narrow - band interference structures at frequency f, the time delay differences Δt1 and Δt2 corresponding to the interference cancellation positions satisfy:

[0081] fΔt1 = N, fΔt2 = M (N, M = 1, 2, 3,...). (7)

[0082] That is, when the value of f·Δt i , (i = 1, 2) is an integer, the corresponding Δt i corresponds to the interference cancellation point in the sound field. Among them, both N and M are positive integers. For the convenience of description, in this article, the value of f·Δt1 is called the first type of period number, and f·Δt2 is called the second type of period number.

[0083] For an underwater sound source at a distance r from the sound source, in three cases of upward transmission and downward reception, downward transmission and upward reception, and equal-depth transmission and reception, the relationships between the two interference distance intervals Δr1 and Δr2 and the sound source distance r, the sound source depth z s and the receiving depth z r are derived respectively.

[0084] When the sound source depth is less than the receiving depth (upward transmission and downward reception), z s < z r . At this time, Δr1 > Δr2. Assume that the sound source distance of the previous interference cancellation position of the first type of interference structure is r, corresponding to Figure 3 the R s1 at; then the next interference cancellation position is located at r + Δr1, corresponding to Figure 3 the R s2 at. Δr1 satisfies the following defining formula:[[]]

[0085]

[0086] Substituting Equation (6) into Equation (8), the relational formula between Δr1 and r, the sound source depth z s can be obtained:[[]]

[0087]

[0088] Here, further assumptions are made:[[]]

[0089] ① The position of the interference maximum point of the first type of interference structure is located at the midpoint between two adjacent interference cancellation points.[[]]

[0090] ② The next interference cancellation point of the second type of interference structure just appears at the position of the interference maximum point of the first type of interference structure, that is, the sound source distance is at, corresponding to Figure 3 the R r2 at.[[]]

[0091] Under the above assumed conditions, near the interference maximum point of the first type of interference structure, the sound source distance of the previous interference cancellation position of the second type of interference structure is corresponding to Figure 3 the R r1 at. Δr2 satisfies the following expression:[[]]

[0092]

[0093] Substituting Equation (6) into Equation (10), the relationship between Δr2, the distance r from the sound source, and the receiving depth z can be obtained: r between:

[0094]

[0095] Combining Equation (9) and Equation (11) gives an analytical expression for the sound source depth:

[0096]

[0097] When the sound source depth is greater than the receiving depth (lowering while receiving), z s > z r . At this time, Δr1 < Δr2. Assuming that the distance from the sound source at the previous interference cancellation position of the second type of interference structure is r, corresponding to Figure 4 the R r1 at; its subsequent interference cancellation position is at r + Δr2, corresponding to Figure 4 the R r2 at. Δr2 satisfies the expression:

[0098]

[0099] Similar to the case of raising while receiving, assuming that the subsequent interference cancellation point of the first type of interference structure just appears near the interference enhancement point of the second type of interference structure, that is, the distance from the sound source is position, corresponding to Figure 4 the R s2 at. Near the interference enhancement point of the second type of interference structure, the distance from the sound source at the previous interference cancellation position of the first type of interference structure is corresponding to Figure 4 the R s1 at. Δr1 satisfies the following expression:

[0100]

[0101] Substituting Equation (6) into Equation (13) and Equation (14), the analytical expression for the sound source depth under the condition of lowering while receiving can be obtained:

[0102]

[0103] When the sound source depth is equal to the receiving depth (equal depth of transmission and reception), z s = z r . At this time, Δr1 = Δr2, and the two types of interference structures coincide. As Figure 5 shown, z s and z r satisfy:

[0104]

[0105] To make the above expressions more concise and intuitive, let:

[0106]

[0107] The analytical expression of the sound source depth can be simplified to:

[0108]

[0109] Define α as the correction coefficient. Taking the upward emission and downward reception as an example, as Figure 5 shown, only the sound source distances R s1 、R s2 corresponding to two adjacent interference cancellation points of the first interference structure and the sound source distances R r1 、R r2 corresponding to two adjacent interference cancellation points of the second interference structure need to be known, and then Equation (18) can be expressed in the following form:

[0110]

[0111] It can be seen from Equation (19) that the value of α is equal to the ratio of the product of the sound source distances of two interference cancellation points of the first interference structure to the product of the sound source distances of two interference cancellation points of the second interference structure. In fact, in the first shadow region, for an underwater sound source, usually Δr1 and Δr2 are much smaller than the reference distance r, so α is a constant approximately equal to 1. Equation (14) can be simplified to

[0112]

[0113] It can be seen from Equation (20) that the ratio of the sound source depth to the receiving depth is approximately equal to the ratio of the second interference distance interval to the first interference distance interval. Therefore, under the condition that only the receiving depth is known, by extracting the two narrowband interference distance intervals in the received signal of the receiver and using Equation (20), the estimation of the sound source depth can be realized.

[0114] For a uniformly moving sound source, the interference distance intervals in Equations (18) and (20) can be replaced with interference time intervals. Assume that a certain uniformly moving sound source has a constant radial velocity of v r , the time interval between the appearances of two adjacent interference cancellation points of the first interference structure is T1, and the time interval between the appearances of two adjacent interference cancellation points of the second interference structure is T2. Then T1 and T2 respectively satisfy Δr1 = v r T1, Δr2 = v r T2. Substituting this equation into Equation (20) can transform the corresponding sound source depth expression into

[0115]

[0116] As can be seen from Equation (21), for a sound source with a constant radial velocity, only two interference time intervals need to be extracted to preliminarily estimate the depth of the sound source. At the same time, the distance information of the sound source corresponding to the interference cancellation point can be used to calculate the correction coefficient, so as to correct the estimation result using Equation (22).

[0117]

[0118] Example 1

[0119] Taking the above-mentioned case of transmitting from above and receiving from below as an example, the specific implementation steps of the method are introduced through simulation. In the embodiment of the present invention, the method of extracting the interference cancellation points from the narrowband interference structure in the LOFAR diagram is adopted to obtain two interference time intervals. The sound speed profile used in the simulation environment is as Figure 6 shown, the seabed density is 1.8 g / cm 3 , the seabed absorption coefficient is 0.8 dB / λ, and the seabed sound speed is 1600 m / s. The depth of the sound source is set to 50 m, the sound source starts from a distance of 45 km from the receiving hydrophone and approaches the receiving hydrophone at a radial velocity of 5 m / s, and moves to a distance of 10 km from the receiving hydrophone. The deployment depths of the receiving hydrophones are 300 m respectively, and the whole observation time is from 0 s to 6000 s.

[0120] The method for estimating the depth of an underwater sound source using a single hydrophone based on the line spectrum interference structure of the present invention has a basic implementation process as Figure 7 shown.

[0121] The specific implementation steps are as follows:

[0122] Step 1: Use the hydrophone to observe at a certain depth and record the deployment depth of the hydrophone;

[0123] Step 2: Perform time-frequency analysis on the received signal to obtain the Figure 8 shown LOFAR diagram of the received signal; and take the narrowband interference structure at a certain frequency point (under the condition of ensuring clear interference structure, the larger the observation frequency, the better, and the larger the frequency, the more conducive to observation) from the LOFAR diagram of the received signal as the observation object, Figure 9 which is the narrowband interference structure at the 200 Hz frequency point.

[0124] Step 3: Select the narrowband interference structure at the 200 Hz frequency point as the observation object and distinguish two types of interference structures; and extract two narrowband interference cancellation points from the two types of narrowband interference structures, respectively as Figure 9as shown by the black circles and black boxes in; record the moment when the interference cancellation point appears; use existing mature methods to measure the sound source range of the target and obtain the target distance information, and record the sound source distance corresponding to the moment when the interference cancellation point appears. Existing mature methods include broadband methods, etc. (Reference: Weng Jinbao, Yang Yanming. Passive ranging method and verification of deep-sea surface target with a single hydrophone [J]. Acta Oceanologica Sinica, 2017, 39(01): 36-45).

[0125] Step Four: Calculate the ratio of the two interference time intervals T1 and T2 through the time when the interference cancellation point appears, and preliminarily estimate the sound source depth using Equation (21).

[0126] Step Five: Use the distance information corresponding to the interference cancellation point to calculate the correction coefficient through Equation (19), and correct the estimated result of the sound source depth. The preliminary measurement result and the corrected result of the sound source depth are as Figure 10 shown.

[0127] This embodiment realizes the estimation of the underwater sound source depth in the first deep-sea shadow zone by using two interference time intervals of two types of narrowband interference structures. Compared with the existing sound field matching-based deep-sea sound source depth estimation methods, the method used in this embodiment can be realized by using a single hydrophone, does not require the spectral characteristic information of the sound source, nor the prior information of accurate ocean environment parameters, avoids the cumbersome copy field calculation process of traditional sound field matching positioning, and is applicable to both broadband and narrowband sound sources.

[0128] Embodiment 2

[0129] In Embodiment 2 of this application, the receiving array is a submerged buoy vertical array composed of 18 hydrophones, and the receiving signal sampling frequency is 16 kHz, which is optional. During the experiment, a towed sound source with a depth of about 120 m was towed by a surface ship and traveled from a distance of 182 km from the submerged buoy to a closer distance. During the whole process, the sound source emitted a dual-tone frequency modulation signal with a center frequency of 300 Hz, a bandwidth of 100 Hz, and a sound source level of 193 dB. The signal of the receiving hydrophone at a depth of 378 m was taken for sound source depth estimation. The seabed is relatively flat in most areas of the experimental sea area, and the average sea depth is about 4312 m. The sound speed profile of the experimental sea area is as Figure 11 shown.

[0130] In Embodiment 2, the data processing is for the target active pulse sound signal. Through arrival time delay estimation, two types of narrowband interference time intervals are calculated using the variation curves of two types of multi-path time delays with time. The specific implementation process is as Figure 12 shown.

[0131] The specific implementation steps are as follows:

[0132] Step One: Extract two types of multi-path time delays from the pulse signals received by the hydrophones, and draw the variation curves of the time delays with time.

[0133] Select a section of data during the movement of a moving sound source from 40 km to 20 km away from the receiver for analysis (during this experimental process, there is less interference nearby and the data quality is relatively high), calculate the values of Δt1 and Δt2, and then perform interpolation fitting on the calculation results. The fitting results are shown in Figure 13.

[0134] Step 2: Calculate the interference cancellation points using the curve of the time delay difference varying with time, obtain two types of interference time intervals, and simultaneously acquire and record the sound source distance information corresponding to the interference cancellation points.

[0135] Take the narrowband sound intensity interference structure at the frequency point f = 300 Hz as the research object (the center frequency of the signal emitted by the simulated sound source is 300 Hz) for sound source depth estimation. Using Equation (7), the following can be calculated Figure 14 The variation relationships of the two types of cycle numbers with time as shown. The circles and squares respectively represent the first type and the second type of interference cancellation points. By calculation, two types of interference time intervals can be obtained. Subtract the sound source distances corresponding to two adjacent interference cancellation points to obtain the interference distance interval, and obtain the interference time interval through the interference distance interval.

[0136] Step 3: Calculate the ratio of the two types of interference time intervals and preliminarily measure the sound source depth.

[0137] Calculate the ratio of the two types of interference time intervals, and use Equation (21) to preliminarily measure the sound source depth. The preliminary measurement results are as Figure 15 shown by the black circles in. The average error between the preliminary measurement results and the reference value of the sound source depth is about 11.7%.

[0138] Step 4: Correct the estimation results using the distance information of the interference cancellation points.

[0139] Substitute the measured distance information of the two types of interference cancellation points into Equation (19) to correct the sound source depth estimation results. The correction results are as Figure 15 shown by the black squares in. After correction, the average error between the sound source depth estimation results and the reference value of the sound source depth is about 7.5%. Compared with before correction, the coincidence degree between the sound source depth estimation results and the reference value is significantly improved.

[0140] Example 3

[0141] This application also provides a single hydrophone deep-sea sound source depth estimation system based on two types of interference time intervals, which is implemented based on the above method. The system includes:

[0142] A module for extracting two types of interference time intervals, which is used to extract two types of interference time intervals using the narrowband interference structure, or to extract two types of interference time intervals using the curves of the two types of multi-path time delays varying with time;

[0143] The initial measurement sound source depth module is used to calculate the ratio of two interference time intervals for the initial measurement of the sound source depth;

[0144] The module for correcting the initial measurement result is used to correct the initial measurement result of the sound source depth by using the distance information of the interference cancellation point.

[0145] This application can also provide a computer device, including: at least one processor, a memory, at least one network interface, and a user interface. Each component in the device is coupled together through a bus system. It can be understood that the bus system is used to realize the connection and communication between these components. In addition to the data bus, the bus system also includes a power bus, a control bus, and a status signal bus.

[0146] Among them, the user interface can include a display, a keyboard, or a pointing device. For example, a mouse, a trackball, a touchpad, or a touch screen, etc.

[0147] It can be understood that the memory in the disclosed embodiments of this application can be a volatile memory or a non-volatile memory, or can include both volatile and non-volatile memories. Among them, the non-volatile memory can be a read-only memory (ROM), a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), an electrically erasable programmable read-only memory (EEPROM), or a flash memory. The volatile memory can be a random access memory (RAM), which is used as an external cache. By way of example but not limitation, many forms of RAM are available, such as static random access memory (SRAM), dynamic random access memory (DRAM), synchronous dynamic random access memory (SDRAM), double data rate synchronous dynamic random access memory (DDR SDRAM), enhanced synchronous dynamic random access memory (ESDRAM), synchlink dynamic random access memory (SLDRAM), and direct rambus random access memory (DRRAM). The memory described herein is intended to include, but not be limited to, these and any other suitable types of memory.

[0148] In some embodiments, the memory stores the following elements, executable modules or data structures, or subsets thereof, or extended sets thereof: an operating system and application programs.

[0149] Among them, the operating system includes various system programs, such as a framework layer, a core library layer, a driver layer, etc., and is used to implement various basic services and handle hardware-based tasks. The application programs include various application programs, such as a Media Player, a Browser, etc., and are used to implement various application services. The program for implementing the method of the embodiments of the present disclosure may be included in the application programs.

[0150] In the above embodiments, by calling the program or instruction stored in the memory, specifically, the program or instruction stored in the application program, the processor is used for:

[0151] Executing the steps of the above method.

[0152] The above method can be applied to the processor or implemented by the processor. The processor may be an integrated circuit chip with signal processing capabilities. In the implementation process, each step of the above method can be completed by the integrated logic circuit in the hardware of the processor or in the form of software instructions. The above processor may be a general-purpose processor, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components. It can implement or execute the various methods, steps, and logic block diagrams disclosed above. The general-purpose processor may be a microprocessor or the processor may also be any conventional processor, etc. Combining the steps of the above-disclosed method can be directly embodied as being executed and completed by the hardware decoding processor, or by a combination of the hardware and software modules in the decoding processor. The software module may be located in a mature storage medium in the art such as a random access memory, a flash memory, a read-only memory, a programmable read-only memory, or an electrically erasable programmable memory, a register, etc. This storage medium is located in the memory, and the processor reads the information in the memory and combines its hardware to complete the steps of the above method.

[0153] It can be understood that these embodiments described in the present application can be implemented by hardware, software, firmware, middleware, microcode, or a combination thereof. For hardware implementation, the processing unit can be implemented in one or more application specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), field-programmable gate arrays (FPGAs), general-purpose processors, controllers, microcontrollers, microprocessors, other electronic units for performing the functions described in the present application, or a combination thereof.

[0154] For software implementation, the techniques of the present application can be implemented by executing the functional modules of the present application (such as procedures, functions, etc.). The software code can be stored in a memory and executed by a processor. The memory can be implemented inside or outside the processor.

[0155] The present application can also provide a non-volatile storage medium for storing a computer program. When the computer program is executed by a processor, the various steps in the above method embodiments can be implemented.

[0156] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application and not to limit them. Although the present application has been described in detail with reference to the embodiments, those of ordinary skill in the art should understand that any modification or equivalent replacement of the technical solutions of the present application does not depart from the spirit and scope of the technical solutions of the present application, and they should all be covered by the scope of the claims of the present application.

Claims

1. A method for estimating the depth of a deep - sea sound source based on two interference time intervals, comprising: Step S1: In the deep - sea environment, use a near - surface depth hydrophone for continuous observation and record the depth where the hydrophone is located; Step S2: Use a narrow - band interference structure to extract two interference time intervals, or use the variation curves of two types of multi - path time delays with time to extract two interference time intervals; Step S3: Calculate the ratio of the two interference time intervals to preliminarily measure the sound - source depth; Step S4: Use the distance information of the interference cancellation points to correct the preliminary measurement result of the sound - source depth.

2. The method for estimating the depth of a deep-sea sound source using a single hydrophone based on two interference time intervals according to claim 1, characterized in that The near - surface depth hydrophone is located shallower than one - fifth of the sea depth.

3. The method for estimating the depth of a deep-sea sound source using a single hydrophone based on two interference time intervals according to claim 1, wherein The method of using a narrow - band interference structure to extract two interference time intervals includes: Perform time - frequency analysis on the received signal to obtain the LOFAR diagram of the received signal; Take the narrow - band interference structure at the preferred frequency point from the LOFAR diagram of the received signal as the observation object and distinguish two types of narrow - band interference structures; Extract two narrow - band interference cancellation points from the two types of narrow - band interference structures respectively, and record the moments when the interference cancellation points appear; Perform sound - source ranging on the target to obtain the target distance information, and record the sound - source distance corresponding to the moment when the interference cancellation point appears; Calculate the ratio of the two interference time intervals through the time when the interference cancellation points appear.

4. The method for estimating the deep-sea sound source depth based on two interference time intervals according to claim 3, characterized in that, The preferred frequency point is the maximum frequency under the condition of ensuring clear interference structure.

5. The method for estimating the depth of a deep-sea sound source using a single hydrophone based on two interference time intervals according to claim 1, characterized in that, The method of using the variation curves of two types of multi - path time delays with time to extract two interference time intervals includes: Extract two types of multi - path time delays from the pulse signal received by the hydrophone and draw the variation curve of the time delay with time; Calculate the arrival time delay difference between the sea - surface - seabed reflection path and the seabed reflection path, and the arrival time delay difference between the seabed - sea - surface reflection path and the seabed reflection path, and perform interpolation fitting on the calculation results; Use the variation curve of the time delay with time to calculate the interference cancellation points, obtain two interference time intervals, and acquire the sound - source distance corresponding to the interference cancellation points.

6. The method for estimating the deep-sea sound source depth based on two interference time intervals according to claim 1, characterized in that The calculation of the ratio of the two interference time intervals to preliminarily measure the sound - source depth includes: Among them, z s represents the sound source depth of the initial measurement; Δr1 and Δr2 respectively represent two interference distance intervals corresponding to two types of narrowband interference structures; z r represents the receiver depth.

7. The method for estimating the depth of a deep-sea sound source using a single hydrophone based on two interference time intervals according to claim 6, wherein The use of the distance information of the interference cancellation points to correct the preliminary measurement result of the sound - source depth includes: Wherein, T1 and T2 respectively represent the time intervals between the appearances of two adjacent interference cancellation points of two types of interference structures; α represents the correction coefficient: Wherein, r represents the sound - source distance.

8. A single hydrophone deep-sea sound source depth estimation system based on two interference time intervals, which is implemented based on the method described in any one of claims 1-7, and is characterized in that The system includes: A module for extracting two interference time intervals, which is used to extract two interference time intervals by using a narrow - band interference structure or by using the variation curves of two types of multi - path time delays with time; A module for preliminarily measuring the sound - source depth, which is used to calculate the ratio of the two interference time intervals to preliminarily measure the sound - source depth; and A module for correcting the preliminary measurement result, which is used to correct the preliminary measurement result of the sound - source depth by using the distance information of the interference cancellation points.

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