Method and device for calculating power frequency magnetic field intensity of underwater ferromagnetic target

Abstract

This invention provides a method and apparatus for calculating the power frequency magnetic field intensity of underwater ferromagnetic targets, belonging to the interdisciplinary field of non-acoustic underwater detection and multidimensional signal processing. The method includes: for an underwater ferromagnetic submersible, obtaining the overall power frequency magnetic field intensity of the submersible at its current position through actual measurement; and calculating the power frequency magnetic field intensity of the underwater ferromagnetic target based on the target attenuation coefficient, the mass of the underwater ferromagnetic target, the distance between the underwater ferromagnetic target and the submersible, the overall power frequency magnetic field intensity of the submersible at its current position, and the mass of the submersible. The underwater ferromagnetic target can be a large-tonnage underwater ferromagnetic target. Through inversion calculation, the power frequency magnetic field intensity generated by a large-tonnage underwater ferromagnetic target at different underwater positions and under different conditions can be obtained, thus assisting in the detection of large-tonnage underwater ferromagnetic targets concealed by ocean background noise.

Description

Technical Field

[0001] This invention belongs to the interdisciplinary field of non-acoustic underwater detection and multidimensional signal processing, and more specifically, relates to a method and apparatus for calculating the power frequency magnetic field strength of underwater ferromagnetic targets. Background Technology

[0002] For large-tonnage ferromagnetic targets, their power frequency magnetic field strength is one of their unique identifiers. Shipwrecks are representative of large-tonnage underwater ferromagnetic targets. Therefore, accurately estimating the magnetic field strength of large-tonnage underwater ferromagnetic targets is of great significance for monitoring, identifying, and locating large-tonnage underwater ferromagnetic shipwrecks.

[0003] Power frequency magnetic fields, power frequency electromagnetic waves, and power frequency magnetic field disturbances are widespread in marine environments. They are generated by globally distributed power transmission, transformation, and distribution networks, and have relatively low frequencies with sufficient penetrating power, typically between 50Hz and 60Hz. Power frequency magnetic fields can penetrate water and interact with ferromagnetic targets, causing these targets to experience power frequency magnetic field disturbances.

[0004] Sonar detection has long been considered a common method for detecting underwater targets, determining their location by receiving sonar echoes. However, using sonar to detect underwater targets such as shipwrecks has some limitations. Shipwrecks are often covered by ocean sediment, and the uneven seabed topography makes sonar detection easily susceptible to interference from these external factors, leading to significant false alarms. Furthermore, acoustic detection requires deploying large arrays, consuming substantial resources, and is highly susceptible to interference from ocean background noise. For long-range, large-area detection of underwater targets concealed by ocean background noise, acoustic detection methods are increasingly ineffective in accurately detecting them. Therefore, there is an urgent need to develop new non-acoustic remote sensing methods to aid in the detection of underwater targets.

[0005] Small-tonnage ferromagnetic targets also exist underwater and in the ocean, commonly including submersibles and small motorboats. This invention uses the power frequency magnetic field strength values ​​of small-tonnage underwater ferromagnetic targets detected in experiments as a basis, and substitutes these values ​​into the invention's inversion empirical formula to calculate the power frequency magnetic field strength generated by large-tonnage ferromagnetic targets at different underwater depths. The advantage of this inversion calculation is that it allows for further estimation of the feasibility of underwater target detection at different detection points based on the obtained power frequency magnetic field strength of large-tonnage underwater ferromagnetic targets.

[0006] The existence of power frequency magnetic fields offers a potential method for non-contact, remote estimation of the power frequency magnetic field strength of large underwater ferromagnetic targets. By analyzing the perturbation of the power frequency electromagnetic field by the ferromagnetic target, the target's magnetic field characteristics can be inferred. The advantages of this method include the ability to estimate the target's magnetic field strength at greater distances, target detection without contact, reduced operational risks, and less susceptibility to interference from seabed topography, thus aiding in the detection of large objects such as shipwrecks.

[0007] Although the presence of power frequency magnetic fields is helpful in the detection of ferromagnetic targets, no calculation method has yet been proposed for inverting the power frequency magnetic field strength of large-tonnage underwater ferromagnetic targets. How to obtain the power frequency magnetic field strength of large-tonnage underwater ferromagnetic targets is a technical problem that the industry urgently needs to solve. Summary of the Invention

[0008] To address the problems existing in the prior art, this invention provides a method and apparatus for calculating the power frequency magnetic field strength of underwater ferromagnetic targets. It enables the calculation of the power frequency magnetic field strength of large underwater ferromagnetic targets by using power frequency magnetic field strength data of small underwater ferromagnetic targets actually detected in field tests, thus providing support for the detection of large underwater ferromagnetic targets and large underwater ferromagnetic ships.

[0009] In a first aspect, the present invention provides a method for calculating the power frequency magnetic field strength of an underwater ferromagnetic target, comprising:

[0010] For a ferromagnetic underwater vehicle, the overall power frequency magnetic field strength of the ferromagnetic underwater vehicle at its current position is obtained by actual measurement.

[0011] Based on the target attenuation coefficient, the mass of the underwater ferromagnetic target, the distance between the underwater ferromagnetic target and the ferromagnetic submersible, the overall power frequency magnetic field strength of the ferromagnetic submersible at its current position, and the mass of the ferromagnetic submersible, the power frequency magnetic field strength of the underwater ferromagnetic target is calculated by inversion. The target attenuation coefficient is the attenuation coefficient of power frequency electromagnetic waves propagating in water.

[0012] Optionally, the step of inverting and calculating the power frequency magnetic field strength of the underwater ferromagnetic target based on the target attenuation coefficient, the mass of the underwater ferromagnetic target, the distance between the underwater ferromagnetic target and the ferromagnetic submersible, the overall power frequency magnetic field strength of the ferromagnetic submersible at its current position, and the mass of the ferromagnetic submersible includes:

[0013] Based on the target attenuation coefficient, the mass of the underwater ferromagnetic target, the distance between the underwater ferromagnetic target and the ferromagnetic submersible, the overall power frequency magnetic field strength of the ferromagnetic submersible at its current position, and the mass of the ferromagnetic submersible, the overall power frequency magnetic field strength of the underwater ferromagnetic target at its current position is calculated by inversion.

[0014] Based on the target attenuation coefficient, the overall power frequency magnetic field strength of the underwater ferromagnetic target at the current position, and the distance between the underwater ferromagnetic target and any underwater position, the power frequency magnetic field strength of the power frequency magnetic field disturbance generated by the underwater ferromagnetic target propagating to any underwater position is calculated by inversion.

[0015] Based on the power frequency magnetic field intensity of the power frequency magnetic field disturbance generated by the underwater ferromagnetic target propagating to the water surface and the height of any position in the air above the water surface, the magnetic field intensity of the power frequency magnetic field disturbance generated by the underwater ferromagnetic target propagating to any position in the air is calculated by inversion.

[0016] Optionally, the step of inverting and calculating the overall power frequency magnetic field strength of the underwater ferromagnetic target at its current position based on the target attenuation coefficient, the mass of the underwater ferromagnetic target, the distance between the underwater ferromagnetic target and the ferromagnetic submersible, the overall power frequency magnetic field strength of the ferromagnetic submersible at its current position, and the mass of the ferromagnetic submersible includes:

[0017] The overall power frequency magnetic field strength of the underwater ferromagnetic target at its current location is calculated using the following inversion formula:

[0018]

[0019] Wherein, B1 represents the overall power frequency magnetic field strength of the underwater ferromagnetic target at its current position, B2 represents the measured overall power frequency magnetic field strength of the ferromagnetic submersible at its current position, α represents the target attenuation coefficient, e represents the base of the natural logarithm, M represents the mass of the underwater ferromagnetic target, m represents the mass of the ferromagnetic submersible, and L represents the distance between the underwater ferromagnetic target and the ferromagnetic submersible.

[0020] Optionally, the step of inverting and calculating the power frequency magnetic field strength at any underwater location based on the target attenuation coefficient, the overall power frequency magnetic field strength of the underwater ferromagnetic target at its current position, and the distance between the underwater ferromagnetic target and any underwater location, includes:

[0021] The power frequency magnetic field strength of the disturbance generated by the underwater ferromagnetic target and propagated to any underwater location is calculated using the following inversion formula:

[0022]

[0023] Wherein, B3 represents the overall power frequency magnetic field strength of the underwater ferromagnetic target at its current position, B4 represents the power frequency magnetic field strength of the power frequency magnetic field disturbance generated by the underwater ferromagnetic target propagating to any position underwater, α represents the target attenuation coefficient, e represents the base of the natural logarithm, and L3 represents the distance between the underwater ferromagnetic target and any position underwater.

[0024] Optionally, the step of inverting and calculating the magnetic field strength of the power frequency magnetic field disturbance generated by the underwater ferromagnetic target propagating to the water surface based on the power frequency magnetic field strength at any position in the air above the water surface and the height of any position in the air above the water surface includes:

[0025] The magnetic field strength of the power frequency magnetic field disturbance generated by the underwater ferromagnetic target propagating to any position in the air is calculated using the following inversion formula:

[0026]

[0027] Wherein, B5 represents the power frequency magnetic field strength of the power frequency magnetic field disturbance generated by the underwater ferromagnetic target propagating to the water surface, B6 represents the magnetic field strength of the power frequency magnetic field disturbance generated by the underwater ferromagnetic target propagating to any position in the air, and h represents the height of any position in the air above the water surface.

[0028] Optionally, the step of obtaining the overall power frequency magnetic field strength of the ferromagnetic underwater vehicle at its current position through actual measurement includes:

[0029] The average power frequency magnetic field strength generated by the ferromagnetic underwater vehicle in different directions was measured.

[0030] Based on the average power frequency magnetic field strength generated by the ferromagnetic underwater vehicle in different directions, the overall power frequency magnetic field strength of the ferromagnetic underwater vehicle at its current position is calculated.

[0031] Optionally, before inverting and calculating the power frequency magnetic field strength of the underwater ferromagnetic target, the method further includes:

[0032] The target attenuation coefficient is determined using the following formula:

[0033]

[0034] Wherein, α represents the target attenuation coefficient, ω represents the angular frequency of the power frequency electromagnetic wave, δ represents the conductivity of water (e.g., seawater conductivity), and μ represents the magnetic permeability of water (e.g., seawater magnetic permeability).

[0035] Secondly, the present invention also provides a device for calculating the power frequency magnetic field strength of underwater ferromagnetic targets, comprising:

[0036] The measurement module is used to obtain the overall power frequency magnetic field strength of the ferromagnetic underwater vehicle at its current position through actual measurement.

[0037] The inversion module is used to invert and calculate the power frequency magnetic field strength of the underwater ferromagnetic target based on the target attenuation coefficient, the mass of the underwater ferromagnetic target, the distance between the underwater ferromagnetic target and the ferromagnetic submersible, the overall power frequency magnetic field strength of the ferromagnetic submersible at its current position, and the mass of the ferromagnetic submersible. The target attenuation coefficient is the attenuation coefficient of power frequency electromagnetic waves propagating in water.

[0038] Thirdly, the present invention provides an electronic device comprising: at least one memory for storing a program; and at least one processor for executing the program stored in the memory, wherein when the program stored in the memory is executed, the processor is configured to execute the method described in the first aspect or any possible implementation thereof.

[0039] Fourthly, the present invention provides a computer-readable storage medium storing a computer program that, when run on a processor, causes the processor to perform the method described in the first aspect or any possible implementation thereof.

[0040] It is understood that the beneficial effects of the second to fourth aspects mentioned above can be found in the relevant descriptions in the first aspect mentioned above, and will not be repeated here.

[0041] In summary, the technical solutions conceived by this invention have the following beneficial effects compared with the prior art:

[0042] By analyzing field test data, the overall power frequency magnetic field strength of the ferromagnetic underwater vehicle at its current position can be obtained. Then, based on the target attenuation coefficient, the mass of the underwater ferromagnetic target, the distance between the underwater ferromagnetic target and the ferromagnetic underwater vehicle, the overall power frequency magnetic field strength of the ferromagnetic underwater vehicle at its current position, and the mass of the ferromagnetic underwater vehicle, the power frequency magnetic field strength of the underwater ferromagnetic target can be calculated. The underwater ferromagnetic target can be a large-tonnage underwater ferromagnetic target. The power frequency magnetic field strength generated by a large-tonnage underwater ferromagnetic target at different underwater positions and under different conditions can be calculated. Furthermore, since the power frequency magnetic field is less affected by environmental factors, the method for calculating the power frequency magnetic field strength of underwater ferromagnetic targets provided by this invention can assist in the detection of large-tonnage underwater ferromagnetic targets at long distances and over large areas, concealed by ocean background noise. Attached Figure Description

[0043] To more clearly illustrate the technical solutions in this 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 some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0044] Figure 1 This is a flowchart illustrating the method for calculating the power frequency magnetic field strength of underwater ferromagnetic targets provided by the present invention.

[0045] Figure 2 This is a diagram showing the positional relationship between a small-tonnage underwater submersible and a large-tonnage underwater ferromagnetic target, provided by the present invention.

[0046] Figure 3 This is a schematic diagram of the diffusion of power frequency magnetic field disturbance generated by a large underwater ferromagnetic target in seawater, provided by the present invention.

[0047] Figure 4 This is a schematic diagram of the propagation of power frequency magnetic field disturbance to any position on the sea surface provided by the present invention;

[0048] Figure 5 This is a schematic diagram of the diffusion of power frequency magnetic field disturbance into the air provided by the present invention;

[0049] Figure 6 This is a schematic diagram of the x-axis magnetic field strength provided by the present invention;

[0050] Figure 7 This is a schematic diagram of the y-axis magnetic field strength provided by the present invention;

[0051] Figure 8 This is a schematic diagram of the z-axis magnetic field strength provided by the present invention;

[0052] Figure 9 This is a schematic diagram of the underwater vehicle provided by the present invention;

[0053] Figure 10 This is a diagram showing the positional relationship between a small-tonnage ferromagnetic submersible and a large-tonnage underwater ferromagnetic target, provided by the present invention.

[0054] Figure 11 This is a schematic diagram of the diffusion of power frequency magnetic field disturbance along the horizontal disturbance in the case provided by the present invention;

[0055] Figure 12 This is a schematic diagram of the vertical diffusion of power frequency magnetic field disturbance in the case provided by the present invention;

[0056] Figure 13 This is a schematic diagram of the structure of the power frequency magnetic field strength calculation device for underwater ferromagnetic targets provided by the present invention. Detailed Implementation

[0057] To make the objectives, technical solutions, and advantages of this invention clearer, 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 and not intended to limit the invention.

[0058] In embodiments of the present invention, the terms "exemplary" or "for example" are used to indicate that something is an example, illustration, or description. Any embodiment or design described as "exemplary" or "for example" in embodiments of the present invention should not be construed as being more preferred or advantageous than other embodiments or designs. Specifically, the use of the terms "exemplary" or "for example" is intended to present the relevant concepts in a specific manner.

[0059] In the description of the embodiments of the present invention, unless otherwise stated, "multiple" means two or more, for example, multiple processing units means two or more processing units, multiple elements means two or more elements, etc.

[0060] Next, the technical solutions provided in the embodiments of the present invention will be introduced.

[0061] Figure 1 This is a flowchart illustrating the method for calculating the power frequency magnetic field strength of underwater ferromagnetic targets provided by the present invention, as shown below. Figure 1 As shown, the subject executing this method can be an electronic device, such as a server. The method includes:

[0062] Step 101: For the ferromagnetic underwater vehicle, obtain the overall power frequency magnetic field strength of the ferromagnetic underwater vehicle at its current position through actual measurement.

[0063] Specifically, the underwater ferromagnetic submersible can be a ferromagnetic submersible in seawater.

[0064] Step 102: Based on the target attenuation coefficient, the mass of the underwater ferromagnetic target, the distance between the underwater ferromagnetic target and the ferromagnetic submersible, the overall power frequency magnetic field strength of the ferromagnetic submersible at its current position, and the mass of the ferromagnetic submersible, the power frequency magnetic field strength of the underwater ferromagnetic target is calculated by inversion. The target attenuation coefficient is the attenuation coefficient of power frequency electromagnetic waves propagating in water.

[0065] Specifically, underwater ferromagnetic targets can be seawater ferromagnetic targets, such as large-tonnage (e.g., 9,000 tons, 50,000 tons, or 100,000 tons) seawater ferromagnetic targets. When performing inversion calculations on the power frequency magnetic field strength of seawater ferromagnetic targets, the target attenuation coefficient can be the attenuation coefficient of power frequency electromagnetic waves propagating in seawater.

[0066] By analyzing field test data, the overall power frequency magnetic field strength of the ferromagnetic underwater vehicle at its current position can be obtained. Then, based on the target attenuation coefficient, the mass of the underwater ferromagnetic target, the distance between the underwater ferromagnetic target and the ferromagnetic underwater vehicle, the overall power frequency magnetic field strength of the ferromagnetic underwater vehicle at its current position, and the mass of the ferromagnetic underwater vehicle, the power frequency magnetic field strength of the underwater ferromagnetic target can be calculated. The underwater ferromagnetic target can be a large-tonnage underwater ferromagnetic target. The power frequency magnetic field strength generated by a large-tonnage underwater ferromagnetic target at different underwater positions and under different conditions can be calculated. Furthermore, since the power frequency magnetic field is less affected by environmental factors, the method for calculating the power frequency magnetic field strength of underwater ferromagnetic targets provided by this invention can assist in the detection of large-tonnage underwater ferromagnetic targets at long distances and over large areas, concealed by ocean background noise.

[0067] For example, the method for calculating the power frequency magnetic field strength of underwater ferromagnetic targets provided by the present invention obtains the power frequency magnetic field strength value generated by small-tonnage underwater ferromagnetic targets by analyzing field test data, and substitutes the value into the proposed inversion empirical formula for calculation to calculate the power frequency magnetic field strength generated by large-tonnage underwater ferromagnetic targets at different underwater locations and under different conditions. It includes the following steps: (1) obtaining test data; (2) inversion calculation of the power frequency magnetic field strength of large-tonnage underwater ferromagnetic targets under different conditions.

[0068] (1) Acquisition of experimental data;

[0069] In field tests, a small-tonnage ferromagnetic submersible is used to represent a small-tonnage ferromagnetic underwater target. First, it is necessary to obtain relevant data of the small-tonnage ferromagnetic submersible. The measured data from the field test are used to calculate the overall power frequency magnetic field strength of the small-tonnage ferromagnetic submersible, as well as the mass m of the small-tonnage ferromagnetic submersible and the depth of the small-tonnage ferromagnetic submersible underwater. The attenuation coefficient α of the power frequency electromagnetic wave propagation in seawater is also obtained.

[0070] The formula for calculating the attenuation coefficient α of power frequency electromagnetic waves propagating in seawater is as follows:

[0071]

[0072] In the above formula, ω represents the angular frequency of the power frequency electromagnetic wave, δ represents the electrical conductivity of seawater, and μ represents the magnetic permeability of seawater.

[0073] (2) Inversion calculation of power frequency magnetic field strength of large underwater ferromagnetic targets under different conditions;

[0074] Underwater, the power frequency magnetic field strength of a large-tonnage ferromagnetic target is inverted using measured power frequency magnetic field strength data of a small-tonnage ferromagnetic target. Based on the target attenuation coefficient, the mass of the underwater ferromagnetic target, the distance between the underwater ferromagnetic target and the ferromagnetic submersible, the overall power frequency magnetic field strength of the ferromagnetic submersible at its current position, and the mass of the ferromagnetic submersible, the overall power frequency magnetic field strength of the underwater ferromagnetic target at its current position is calculated.

[0075] Specifically, based on the analysis of field test data, the following empirical formula for inversion can be proposed to calculate large-tonnage underwater ferromagnetic targets:

[0076]

[0077] Wherein, B1 represents the power frequency magnetic field strength of the large-tonnage ferromagnetic target underwater, B2 represents the power frequency magnetic field strength of the small-tonnage ferromagnetic submersible underwater as measured in the field test, α represents the attenuation coefficient of power frequency electromagnetic waves propagating in seawater, e represents the base of the natural logarithm, M represents the mass of the large-tonnage ferromagnetic target, and m represents the mass of the small-tonnage ferromagnetic submersible. L represents the distance between the small-tonnage ferromagnetic submersible and the large-tonnage ferromagnetic target in the field test, which can be used to invert the large-tonnage ferromagnetic target at any underwater location. Figure 2 This invention provides a diagram showing the positional relationship between a small-tonnage underwater vehicle and a large-tonnage underwater ferromagnetic target. The specific relationship is as follows: Figure 2 As shown.

[0078] The derivation of the formula is as follows:

[0079] Based on multiple field tests, it was proposed that the primary field H1 generated by the power frequency power grid at the water inlet (the junction of the air layer and the seawater layer) is... (1) for:

[0080]

[0081] In the above formula: π represents pi, f represents frequency, usually 50 or 60 Hz; r represents the distance from the power frequency electromagnetic wave generated by the power grid to the water surface, representing the distance from the magnetic field source. μ0 represents the permeability in vacuum, its value is approximately 4π × 10⁻⁶. -7 H / m (Henry / meter) is used to represent the properties of a magnetic field in the air.

[0082] The power frequency magnetic field strength H1 generated when the power frequency electromagnetic wave enters the water and reaches the interior of the ferromagnetic target (2) for:

[0083]

[0084] In the formula, α is the attenuation coefficient of power frequency electromagnetic waves in seawater, e represents the base of the natural logarithm, and L0 is the distance that the power frequency electromagnetic waves travel through seawater to reach the ferromagnetic target.

[0085] For large-tonnage ferromagnetic targets underwater, the power frequency magnetic field strength H1 (2) The incentive will be further amplified based on its tonnage.

[0086] Therefore, the empirical formula for inversion is derived:

[0087] B1 = 1 (2) M;

[0088] In the above formula, the power frequency magnetic field strength generated by the overall excitation of the large-tonnage ferromagnetic target underwater is B1, and M represents the mass of the large-tonnage ferromagnetic target.

[0089] because:

[0090]

[0091] Therefore, it can be deduced that:

[0092]

[0093] Here, L1 represents the distance that a power frequency electromagnetic wave can travel through seawater to reach a large-tonnage ferromagnetic target.

[0094] Similarly, for small-tonnage ferromagnetic targets underwater, the power frequency magnetic field strength H1 (2) The excitation will also be amplified according to its tonnage. Let the mass of the small-tonnage ferromagnetic target be m, and the following formula can be obtained:

[0095]

[0096] L2 is the distance that a power frequency electromagnetic wave travels through seawater to reach a small-tonnage ferromagnetic target.

[0097] Based on the ratio of the power frequency magnetic field strength of ferromagnetic targets of different tonnages The inversion empirical formula is derived as follows:

[0098]

[0099] Simplifying the above equation, we get:

[0100]

[0101] In the above formula, L represents the distance between the large-tonnage ferromagnetic target and the small-tonnage ferromagnetic target.

[0102] The following describes the inversion calculation of the propagation of the power frequency magnetic field disturbance generated by a large underwater ferromagnetic target to any underwater location. Based on the target attenuation coefficient, the overall power frequency magnetic field strength of the underwater ferromagnetic target at its current location, and the distance between the underwater ferromagnetic target and any underwater location (which can be the sea surface), the power frequency magnetic field strength of the underwater ferromagnetic target's propagation to any underwater location is calculated.

[0103] Specifically, within the seawater layer, based on the known power frequency magnetic field strength generated by the large underwater ferromagnetic target at its current location, the power frequency magnetic field strength at any location in the ocean where its disturbance propagates is calculated. The value of B1, representing the power frequency magnetic field strength of the large underwater ferromagnetic target at its current location, is obtained through inversion. Using this data as a basis, the power frequency magnetic field strength at any location in the ocean (which could be the sea surface) where the large underwater ferromagnetic target's disturbance propagates can be inverted. Since the discussion focuses on the large underwater ferromagnetic target itself, at this point...

[0104] Therefore, an empirical formula for retrieving the propagation of power frequency magnetic field disturbances of large underwater ferromagnetic targets in seawater is derived:

[0105]

[0106] Where B3 represents the power frequency magnetic field strength of the large underwater ferromagnetic target at its current underwater location, and B4 represents the power frequency magnetic field strength at any location in the ocean where the power frequency magnetic field disturbance of the large underwater ferromagnetic target propagates. α represents the power frequency electromagnetic wave attenuation coefficient in seawater, e represents the base of the natural logarithm, and L3 represents the distance traveled by the power frequency magnetic field disturbance of the large underwater ferromagnetic target to any location in the ocean. Figure 3 This is a schematic diagram illustrating the diffusion of power frequency magnetic field disturbances generated by large underwater ferromagnetic targets in seawater, as provided by the present invention. (Specifically, as shown in the diagram...) Figure 3 As shown.

[0107] At this point, the power frequency magnetic field disturbance generated by the large underwater ferromagnetic target can be calculated to propagate to any location, and the power frequency magnetic field strength at that location can be calculated.

[0108] The following describes the inversion calculation of the propagation of the power frequency magnetic field disturbance generated by a large underwater ferromagnetic target to the air layer. Based on the power frequency magnetic field strength of the power frequency magnetic field disturbance generated by the underwater ferromagnetic target propagating to the water surface (e.g., sea surface) and the height of any position in the air above the water surface, the magnetic field strength of the power frequency magnetic field disturbance generated by the underwater ferromagnetic target propagating to any position in the air is calculated.

[0109] Specifically, to further obtain the power frequency magnetic field intensity data at different altitudes of the air layer where the power frequency magnetic field disturbance of the large-tonnage underwater ferromagnetic target propagates, and considering the different attenuation patterns of the air and sea layers, it is first necessary to obtain the power frequency magnetic field intensity at sea level where the disturbance reaches the sea surface. This can be achieved using the proposed inversion empirical formula: The power frequency magnetic field strength at sea level is calculated, which can be considered as the power frequency magnetic field disturbance generated by the large underwater ferromagnetic target propagating to the sea level. B4 represents the power frequency magnetic field strength at any location (sea level) in the seawater where the power frequency magnetic field disturbance of the large underwater ferromagnetic target propagates. Figure 4 This is a schematic diagram of the propagation of power frequency magnetic field disturbance to any position at sea level provided by the present invention. The schematic diagram of power frequency electromagnetic disturbance propagation is as follows: Figure 4 As shown.

[0110] By calculating the power frequency magnetic field strength at sea level, we can estimate the power frequency magnetic field strength at different heights of the air after the power frequency magnetic field disturbance at sea level propagates.

[0111] Therefore, an empirical formula for inversion is proposed:

[0112]

[0113] Inversion calculations were performed to obtain the power frequency magnetic field strength at different altitudes in the air. B5 represents the power frequency magnetic field strength at sea level, B6 represents the power frequency magnetic field strength at different altitudes in the air after the power frequency magnetic field disturbance at sea level propagates, and h represents the height of the air above sea level. Figure 5 This is a schematic diagram of the diffusion of power frequency magnetic field disturbance into the air provided by the present invention, and the positional relationships are as follows: Figure 5 As shown.

[0114] Understandably, this invention proposes an inversion empirical formula for calculating the power frequency magnetic field strength of large-tonnage underwater ferromagnetic targets. Based on the analysis results of field tests, the power frequency magnetic field strength generated by small-tonnage underwater ferromagnetic submersibles is obtained. Then, based on the already calculated power frequency magnetic field strength of large-tonnage underwater ferromagnetic targets, the power frequency magnetic field strength at any location in the ocean or in the air caused by the power frequency magnetic field disturbance generated by the large-tonnage underwater ferromagnetic target can be further estimated. In the inversion calculation process of this invention, the mass of the small-tonnage underwater ferromagnetic submersible and the underwater depth have significant weights, making the inversion calculation more accurate. At the same time, the power frequency magnetic field is less affected by environmental factors; therefore, using this invention can help detect large-tonnage underwater ferromagnetic targets at long distances and over large areas, concealed by ocean background noise.

[0115] The following example further illustrates the method for calculating the power frequency magnetic field strength of underwater ferromagnetic targets provided by this invention.

[0116] (1) Data acquisition steps;

[0117] In this implementation case, the small-tonnage submersible used in the field test represents the small-tonnage ferromagnetic underwater target in the inversion calculation. First, the power frequency magnetic field strength of the small-tonnage ferromagnetic submersible as a whole underwater, the mass m of the small-tonnage ferromagnetic submersible, and the depth of the small-tonnage ferromagnetic submersible underwater are obtained from the field test. The attenuation coefficient α of the power frequency electromagnetic wave propagation in seawater is also obtained.

[0118] The following calculations are based on the power frequency magnetic field disturbance signal data generated by the submersible at a depth of 50m under test conditions 40 kilometers offshore from Nanshan Port, Sanya, Hainan. The submersible is 8.87m long and weighs m = 8.5 tons, with the nose of the submersible being 1.87m long.

[0119] In the open ocean environment, the power frequency magnetic field is generally composed of frequencies of 50Hz and 60Hz, but it is also affected by its neighboring frequencies, resulting in a superposition effect on the power frequency magnetic field. Simultaneously, the power frequency magnetic field is directional, allowing for the measurement of the average power frequency magnetic field strength generated by a ferromagnetic underwater vehicle in different directions. Specifically, considering the above factors, the measured average power frequency magnetic field strength generated by the underwater vehicle in different directions during field tests is as follows: x-axis 21.5 nT, y-axis 29.2 nT, z-axis 90.6 nT. Figure 6 This is a schematic diagram of the x-axis magnetic field strength provided by the present invention. Figure 7 This is a schematic diagram of the y-axis magnetic field strength provided by the present invention. Figure 8 This is a schematic diagram of the z-axis magnetic field strength provided by the present invention. Figure 9 This is a schematic diagram of the underwater vehicle provided by the present invention, specifically as follows: Figures 6-9 As shown.

[0120] Therefore, through field tests, the triaxial magnetic field strengths generated by the submersible at a depth of 50m underwater after interacting with the power frequency magnetic field are: x-axis 21.5nT, y-axis 29.2nT, and z-axis 90.6nT.

[0121] Based on the average power frequency magnetic field strength generated by the ferromagnetic underwater vehicle in different directions, the overall power frequency magnetic field strength of the ferromagnetic underwater vehicle at its current position is calculated. Specifically, by substituting the power frequency magnetic field strengths in the x, y, and z axes into the formula, the overall power frequency magnetic field strength of the small-tonnage ferromagnetic underwater vehicle can be calculated. The values ​​are then substituted into the following formula:

[0122]

[0123] Based on the data calculations, the total field strength of the power frequency magnetic field of the small-tonnage ferromagnetic submersible tested in the field is B0 = 97.5 nT.

[0124] (2) Inversion calculation of power frequency magnetic field strength of large underwater ferromagnetic targets under different conditions;

[0125] Based on the data of the power frequency magnetic field disturbance intensity generated by the submersible at a depth of 50m, the power frequency magnetic field intensity generated by the large-tonnage ferromagnetic target at different depths can be inverted using empirical formulas.

[0126] In this case, the small-tonnage ferromagnetic underwater vehicle and the large-tonnage ferromagnetic underwater vehicle are positioned in the same vertical direction. Figure 10 This invention provides a positional relationship diagram between a small-tonnage ferromagnetic underwater vehicle and a large-tonnage underwater ferromagnetic target. The positional relationship between the small-tonnage ferromagnetic underwater vehicle and the large-tonnage underwater ferromagnetic target is as follows: Figure 10 As shown in the example, this implementation case uses the calculation of the power frequency magnetic field strength of a large underwater ferromagnetic target at depths of 160m, 200m, 300m, and 500m as an example, and the weights of the large underwater ferromagnetic targets are 9000 tons, 50000 tons, and 100000 tons, respectively.

[0127] Based on the proposed inversion empirical formula:

[0128]

[0129] Wherein, B1 represents the power frequency magnetic field strength of the large-tonnage underwater ferromagnetic target, B2 represents the power frequency magnetic field strength of the field test submersible, and the total power frequency field strength of the field test submersible is calculated to be B0 = 97.5nT. M represents the mass of the large-tonnage underwater ferromagnetic target. In this case, the calculations are performed for underwater large-tonnage ferromagnetic targets of 9000 tons, 50000 tons, and 100000 tons, so the values ​​of M are 9000t, 50000t, and 100000t, respectively. m represents the mass of the field test submersible, m = 8.5t. L represents the distance between the small-tonnage underwater ferromagnetic submersible and the large-tonnage underwater ferromagnetic target. For ease of calculation, in this case, the submersible and the large-tonnage underwater ferromagnetic target are in the same vertical direction. The measured depth of the submersible is 50m. The depths of the large-tonnage ferromagnetic targets to be calculated in this case are 160m, 200m, 300m, and 500m. Therefore, L takes values ​​of 110m, 150m, 250m, and 450m, respectively, and α is the attenuation coefficient of power frequency electromagnetic waves propagating in seawater.

[0130] The attenuation coefficient α of power frequency electromagnetic waves in seawater can be calculated using the following formula:

[0131]

[0132] In the above formula, ω represents the angular frequency of the power frequency electromagnetic wave, δ represents the electrical conductivity of seawater, and μ represents the magnetic permeability of seawater. Based on the physical properties and parameters of seawater, α = 0.028 can be calculated.

[0133] Substituting the above values, the calculation results can be obtained according to the inversion empirical formula, as shown in Table 1. The unit of magnetic field strength is nT:

[0134] Table 1 Power Frequency Magnetic Field Strength of Large-Ton Underwater Ferromagnetic Targets

[0135]

[0136] Obviously, as the depth increases, the power frequency magnetic field strength generated by large-tonnage ferromagnetic targets becomes weaker and weaker. Through empirical formulas, the power frequency magnetic field strength generated by ferromagnetic targets of different tonnages at different diving depths was preliminarily obtained.

[0137] Based on the data in Table 1, the power frequency magnetic field disturbance generated by a large underwater ferromagnetic target at different depths can be calculated and propagated to any location in the ocean, at which point the power frequency magnetic field strength at that location can be determined. Figure 11 This is a schematic diagram of the diffusion of power frequency magnetic field disturbance along the horizontal disturbance in the case provided by the present invention, as shown below. Figure 11 For ease of calculation, this case only calculates the power frequency magnetic field intensity at any position when the power frequency magnetic field disturbance generated by a large underwater ferromagnetic target at a certain depth propagates horizontally.

[0138] Calculated based on the inversion empirical formula:

[0139]

[0140] Here, B3 represents the power frequency magnetic field strength of large underwater ferromagnetic targets of different tonnages at the current depth. In this case, the data calculated from Table 1 for an underwater depth of 160m is used, and large underwater ferromagnetic targets with masses of 9000 tons, 50000 tons, and 100000 tons are still used as implementation cases. B4 represents the power frequency magnetic field strength at any location reached by the power frequency magnetic field disturbance generated by the large underwater ferromagnetic target at a certain depth. L3 represents the distance required for the power frequency magnetic field disturbance generated by the large underwater ferromagnetic target to propagate to this location. In this case, L3 = 500m, and the attenuation coefficient α = 0.028. Substituting the values, the calculation results are shown in Table 2 below. The unit of magnetic field strength is nT.

[0141] Table 2. Magnetic field strength at any underwater location.

[0142]

[0143] To further obtain data on the power frequency magnetic field intensity of a large underwater ferromagnetic target propagating into the air layer at different altitudes, and the power frequency magnetic field disturbance data at those altitudes, it is necessary to first determine the power frequency magnetic field intensity at sea level when the power frequency magnetic field disturbance generated by the large underwater ferromagnetic target propagates to an arbitrary location on the sea surface.

[0144] Figure 12 This is a schematic diagram of the vertical diffusion of power frequency magnetic field disturbance in the case provided by the present invention, as shown below. Figure 12 As shown, this can be considered as the power frequency magnetic field disturbance generated by the large-tonnage ferromagnetic target underwater propagating to the sea level. The power frequency magnetic field strength at the sea level can be calculated according to the proposed inversion empirical formula. In this example, only the case where the power frequency magnetic field disturbance propagates vertically upward to the sea level is considered.

[0145] Calculations are performed based on the proposed inversion empirical formula:

[0146]

[0147] Here, B3 represents the power frequency magnetic field strength of large underwater ferromagnetic targets of different tonnages at the current depth. In this case, B3 uses the power frequency magnetic field strength data of large underwater ferromagnetic targets at depths of 160m, 200m, and 300m from Table 1, still using large underwater ferromagnetic targets with masses of 9000 tons, 50000 tons, and 100000 tons as implementation cases. B4 represents the power frequency magnetic field strength at any underwater location where the power frequency magnetic field disturbance generated by the large underwater ferromagnetic target propagates at a certain depth. Here, 3 represents the distance from the power frequency magnetic field disturbance generated by the large underwater ferromagnetic target to any location at sea level. In this example, only the case where the power frequency magnetic field disturbance propagates vertically upwards to sea level is considered. α = 0.028. Substituting the values, the calculation results are shown in Table 3. The unit of magnetic field strength is nT.

[0148] Table 3 Magnetic field strength at sea level

[0149]

[0150] Based on the data in Table 3, the power frequency magnetic field intensity at sea level was obtained after the power frequency magnetic field disturbance of a large-tonnage ferromagnetic target was transmitted to the sea surface. This intensity can be used to further investigate the power frequency magnetic field intensity that can be detected when detecting large-tonnage ferromagnetic targets underwater at different altitudes.

[0151] To investigate the power frequency magnetic field strength generated by large-tonnage ferromagnetic targets underwater at different altitudes, we will use altitudes of 500m, 1000m, and 2000m as implementation cases. For ease of calculation, the altitudes in the cases are vertical heights above sea level.

[0152] According to the inversion empirical formula:

[0153]

[0154] In the above formula, B5 represents the intensity of the power frequency magnetic field at sea level. In this implementation case, the value of B5 is the power frequency magnetic field intensity of the large underwater ferromagnetic target at a depth of 160m in Table 3, which is transmitted to the sea level. B6 represents the power frequency magnetic field intensity at different heights in the air after the power frequency magnetic field disturbance at sea level propagates. h represents the height of the air above the sea level, with h values ​​of 500m, 1000m, and 2000m.

[0155] Substituting the numerical values ​​into the formula, in this case, only the large-tonnage ferromagnetic target underwater at a depth of 160m is calculated, and the data can be obtained as shown in Table 4 below. The unit of magnetic field strength is nT:

[0156] Table 4. Magnetic field strength obtained when propagating into the air.

[0157]

[0158] The inversion estimation of this invention yields the power frequency magnetic field strength values ​​of large-tonnage underwater ferromagnetic targets at any position in seawater, at any position at sea level, and at different altitudes in the air, providing assistance for detecting ferromagnetic targets and ferromagnetic ships in the ocean.

[0159] The following describes the power frequency magnetic field strength calculation device for underwater ferromagnetic targets provided by the present invention. The power frequency magnetic field strength calculation device for underwater ferromagnetic targets described below can be referred to in correspondence with the power frequency magnetic field strength calculation method for underwater ferromagnetic targets described above.

[0160] Figure 13 This is a schematic diagram of the structure of the power frequency magnetic field strength calculation device for underwater ferromagnetic targets provided by the present invention, as shown below. Figure 13 As shown, the device includes: a measurement module 10 and an inversion module 20. Wherein:

[0161] The measurement module 10 is used to measure the overall power frequency magnetic field strength of a ferromagnetic underwater vehicle at its current position.

[0162] The inversion module 20 is used to invert and calculate the power frequency magnetic field strength of the underwater ferromagnetic target based on the target attenuation coefficient, the mass of the underwater ferromagnetic target, the distance between the underwater ferromagnetic target and the ferromagnetic submersible, the overall power frequency magnetic field strength of the ferromagnetic submersible at its current position, and the mass of the ferromagnetic submersible. The target attenuation coefficient is the attenuation coefficient of power frequency electromagnetic waves propagating in water.

[0163] It should be understood that the above-described device is used to execute the methods in the above embodiments. The implementation principle and technical effect of the corresponding program modules in the device are similar to those described in the above methods. The working process of the device can be referred to the corresponding process in the above methods, and will not be repeated here.

[0164] Based on the methods described in the above embodiments, this invention provides an electronic device. The device may include at least one memory for storing a program and at least one processor for executing the program stored in the memory. When the program stored in the memory is executed, the processor performs the methods described in the above embodiments.

[0165] Based on the methods in the above embodiments, this embodiment of the invention provides a computer-readable storage medium storing a computer program that, when run on a processor, causes the processor to execute the methods in the above embodiments.

[0166] Based on the methods in the above embodiments, this embodiment of the invention provides a computer program product that, when run on a processor, causes the processor to execute the methods in the above embodiments.

[0167] It is understood that the processor in the embodiments of the present invention can be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, transistor logic devices, hardware components, or any combination thereof. A general-purpose processor can be a microprocessor or any conventional processor.

[0168] The method steps in these embodiments of the invention can be implemented in hardware or by a processor executing software instructions. The software instructions can consist of corresponding software modules, which can be stored in random access memory (RAM), flash memory, read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), registers, hard disks, portable hard disks, CD-ROMs, or any other form of storage medium known in the art. An exemplary storage medium is coupled to the processor, enabling the processor to read information from and write information to the storage medium. Of course, the storage medium can also be a component of the processor. The processor and the storage medium can reside in an ASIC.

[0169] In the above embodiments, implementation can be achieved entirely or partially through software, hardware, firmware, or any combination thereof. When implemented using software, it can be implemented entirely or partially as a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, all or part of the processes or functions described in the embodiments of the present invention are generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium or transmitted through the computer-readable storage medium. The computer instructions can be transmitted from one website, computer, server, or data center to another website, computer, server, or data center via wired (e.g., coaxial cable, fiber optic, digital subscriber line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) means. The computer-readable storage medium can be any available medium that a computer can access or a data storage device such as a server or data center that integrates one or more available media. The available medium can be a magnetic medium (e.g., floppy disk, hard disk, magnetic tape), an optical medium (e.g., DVD), or a semiconductor medium (e.g., solid-state disk (SSD)).

[0170] It is understood that the various numerical designations used in the embodiments of the present invention are merely for the convenience of description and are not intended to limit the scope of the embodiments of the present invention.

[0171] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for calculating the power frequency magnetic field strength of an underwater ferromagnetic target, characterized in that, include: For a ferromagnetic underwater vehicle, the overall power frequency magnetic field strength of the ferromagnetic underwater vehicle at its current position is obtained by actual measurement. Based on the target attenuation coefficient, the mass of the underwater ferromagnetic target, the distance between the underwater ferromagnetic target and the ferromagnetic submersible, the overall power frequency magnetic field strength of the ferromagnetic submersible at its current position, and the mass of the ferromagnetic submersible, the power frequency magnetic field strength of the underwater ferromagnetic target is calculated by inversion. The target attenuation coefficient is the attenuation coefficient of power frequency electromagnetic waves propagating in water. The calculation of the power frequency magnetic field strength of the underwater ferromagnetic target based on the target attenuation coefficient, the mass of the underwater ferromagnetic target, the distance between the underwater ferromagnetic target and the ferromagnetic submersible, the overall power frequency magnetic field strength of the ferromagnetic submersible at its current position, and the mass of the ferromagnetic submersible includes: Based on the target attenuation coefficient, the mass of the underwater ferromagnetic target, the distance between the underwater ferromagnetic target and the ferromagnetic submersible, the overall power frequency magnetic field strength of the ferromagnetic submersible at its current position, and the mass of the ferromagnetic submersible, the overall power frequency magnetic field strength of the underwater ferromagnetic target at its current position is calculated by inversion. Based on the target attenuation coefficient, the overall power frequency magnetic field strength of the underwater ferromagnetic target at the current position, and the distance between the underwater ferromagnetic target and any underwater position, the power frequency magnetic field strength of the power frequency magnetic field disturbance generated by the underwater ferromagnetic target propagating to any underwater position is calculated by inversion. Based on the power frequency magnetic field intensity of the power frequency magnetic field disturbance generated by the underwater ferromagnetic target propagating to the water surface and the height of any position in the air above the water surface, the magnetic field intensity of the power frequency magnetic field disturbance generated by the underwater ferromagnetic target propagating to any position in the air is calculated by inversion.

2. The method for calculating the power frequency magnetic field strength of an underwater ferromagnetic target according to claim 1, characterized in that, The calculation of the overall power frequency magnetic field strength of the underwater ferromagnetic target at its current position, based on the target attenuation coefficient, the mass of the underwater ferromagnetic target, the distance between the underwater ferromagnetic target and the ferromagnetic submersible, the overall power frequency magnetic field strength of the ferromagnetic submersible at its current position, and the mass of the ferromagnetic submersible, includes: The overall power frequency magnetic field strength of the underwater ferromagnetic target at its current location is calculated using the following inversion formula: ； in, This represents the overall power frequency magnetic field strength of the underwater ferromagnetic target at its current location. This represents the measured overall power frequency magnetic field strength of the ferromagnetic underwater vehicle at its current location. This represents the target attenuation coefficient. The base of the natural logarithm. This indicates the mass of the underwater ferromagnetic target. This indicates the mass of the ferromagnetic underwater vehicle. This indicates the distance between the underwater ferromagnetic target and the ferromagnetic submersible.

3. The method for calculating the power frequency magnetic field strength of an underwater ferromagnetic target according to claim 1, characterized in that, The process of inverting and calculating the power frequency magnetic field strength at any underwater location based on the target attenuation coefficient, the overall power frequency magnetic field strength of the underwater ferromagnetic target at its current position, and the distance between the underwater ferromagnetic target and any underwater location, includes: The power frequency magnetic field strength of the disturbance generated by the underwater ferromagnetic target and propagated to any underwater location is calculated using the following inversion formula: ； in, This represents the overall power frequency magnetic field strength of the underwater ferromagnetic target at its current location. This represents the power frequency magnetic field strength at any underwater location where the power frequency magnetic field disturbance generated by the underwater ferromagnetic target propagates. This represents the target attenuation coefficient. Represents the base of the natural logarithm This indicates the distance between the underwater ferromagnetic target and any location underwater.

4. The method for calculating the power frequency magnetic field strength of an underwater ferromagnetic target according to claim 1, characterized in that, The calculation of the magnetic field strength at any point in the air based on the power frequency magnetic field disturbance generated by the underwater ferromagnetic target propagating to the water surface and the height of any position in the air above the water surface includes: The magnetic field strength of the power frequency magnetic field disturbance generated by the underwater ferromagnetic target propagating to any position in the air is calculated using the following inversion formula: = ； in, This represents the power frequency magnetic field strength at the water surface caused by the power frequency magnetic field disturbance generated by the underwater ferromagnetic target. The value of h represents the magnetic field strength of the power frequency magnetic field disturbance generated by the underwater ferromagnetic target propagating to any position in the air, where h represents the height of any position in the air above the water surface.

5. The method for calculating the power frequency magnetic field strength of an underwater ferromagnetic target according to claim 1, characterized in that, The method for obtaining the overall power frequency magnetic field strength of a ferromagnetic underwater vehicle at its current location through actual measurement includes: The average power frequency magnetic field strength generated by the ferromagnetic underwater vehicle in different directions was measured. Based on the average power frequency magnetic field strength generated by the ferromagnetic underwater vehicle in different directions, the overall power frequency magnetic field strength of the ferromagnetic underwater vehicle at its current position is calculated.

6. The method for calculating the power frequency magnetic field strength of an underwater ferromagnetic target according to any one of claims 1-5, characterized in that, Before inverting and calculating the power frequency magnetic field strength of the underwater ferromagnetic target, the following steps are also included: The target attenuation coefficient is determined using the following formula: = ； in, This represents the target attenuation coefficient. This represents the angular frequency of power frequency electromagnetic waves. Indicates the electrical conductivity of water. This indicates the magnetic permeability of water.

7. A device for calculating the power frequency magnetic field strength of an underwater ferromagnetic target, characterized in that, The method for calculating the power frequency magnetic field strength of underwater ferromagnetic targets as described in any one of claims 1-6 includes: The measurement module is used to obtain the overall power frequency magnetic field strength of the ferromagnetic underwater vehicle at its current position through actual measurement. The inversion module is used to invert and calculate the power frequency magnetic field strength of the underwater ferromagnetic target based on the target attenuation coefficient, the mass of the underwater ferromagnetic target, the distance between the underwater ferromagnetic target and the ferromagnetic submersible, the overall power frequency magnetic field strength of the ferromagnetic submersible at its current position, and the mass of the ferromagnetic submersible. The target attenuation coefficient is the attenuation coefficient of power frequency electromagnetic waves propagating in water.

8. An electronic device, characterized in that, include: At least one memory for storing programs; At least one processor is configured to execute a program stored in the memory, wherein when the program stored in the memory is executed, the processor is configured to perform the method as described in any one of claims 1-6.

9. A non-transitory computer-readable storage medium storing a computer program, characterized in that, When the computer program is run on the processor, it causes the processor to perform the method as described in any one of claims 1-6.

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