A high-precision calculation method of sea clutter average backscattering coefficient in high sea state

Abstract

The application relates to the technical field of sea clutter, in particular to a high-precision calculation method of high-sea-state sea clutter average backscattering coefficient. The method comprises the following steps: generating a three-dimensional sea surface geometric model in the form of surface elements according to a sea spectrum function; wherein the sea surface geometric model comprises a plurality of surface elements; applying a ray tracing method to the sea surface geometric model under the irradiation of a plane wave to generate a ray set; wherein the ray set comprises a plurality of rays; for each ray, sequentially marking the surface elements intersecting the ray to obtain a plurality of intersecting surface element sets; calculating total scattering fields by applying a small slope approximation method according to the plurality of intersecting surface element sets; and calculating the average backscattering coefficient according to the plurality of total scattering fields. The application provides a high-precision calculation method of high-sea-state sea clutter average backscattering coefficient, which can calculate the high-sea-state sea clutter average backscattering coefficient with high precision and high efficiency.

Description

Technical Field

[0001] This invention relates to the field of sea clutter technology, and in particular to a high-precision method for calculating the average backscattering coefficient of sea clutter in high sea states. Background Technology

[0002] Sea clutter significantly impacts the detection and identification of sea surface targets at various incident angles. Therefore, studying the scattering characteristics of sea clutter, especially the average backscattering coefficient, is of great significance.

[0003] In related technologies, there are various electromagnetic calculation methods for the average backscattering coefficient of sea clutter, such as the Kirchhoff approximation method, the two-scale method, the small slope approximation method, the integral equation method, and the ray tracing method. The first four methods are analytical / semi-analytical methods, with high computational efficiency, and are suitable for low-sea-state sea clutter. The small slope approximation method, in particular, is widely used due to its wide range of applicable incident angles and high computational accuracy. While the ray tracing method can simulate the multipath scattering effect of sea clutter under high sea-state conditions, it requires detailed pixel subdivision of the sea surface geometry and multiple ray tracing operations, resulting in low computational efficiency and its less frequent use.

[0004] Therefore, in order to address the above shortcomings, there is an urgent need for a method that can calculate the average backscattering coefficient of sea clutter in high sea state with high accuracy and high efficiency. Summary of the Invention

[0005] This invention provides a high-precision method for calculating the average backscattering coefficient of sea clutter in high sea states, which enables high-precision and high-efficiency calculation of the average backscattering coefficient of sea clutter in high sea states.

[0006] This invention provides a high-precision method for calculating the average backscattering coefficient of sea clutter in high sea states, comprising:

[0007] A three-dimensional sea surface geometry model in the form of surface elements is generated based on the sea surface spectral function; wherein, the sea surface geometry model includes multiple surface elements;

[0008] Under the illumination of a plane wave, a ray tracing method is applied to the geometric model of the sea surface to generate a ray set; wherein the ray set includes multiple rays;

[0009] For each ray, the surface elements that intersect the ray are marked sequentially to obtain a set of multiple intersecting surface elements;

[0010] The total scattered field is calculated using the small slope approximation method based on the multiple sets of intersecting surface elements.

[0011] The average backscattering coefficient is calculated based on the total scattered fields.

[0012] In one possible design, the generation of a three-dimensional sea surface geometry model in the form of surface elements based on the spectral function includes:

[0013] Let the specific form of the spectral function be: ;in, The traveling wave vector of seawater, Wind speed over sea surface;

[0014] A 3D sea surface geometry model in the form of surface elements is generated using nonlinear generation techniques; wherein, the projection of the sea surface geometry model onto the horizontal plane is a side length of... a square, , This refers to the radar's lateral resolution.

[0015] The geometric model of the sea surface is divided into equal parts. The side length is A square element.

[0016] In one possible design, the process of applying ray tracing to the sea surface geometry model under plane wave illumination to generate a ray set includes:

[0017] The sea surface geometry model is subjected to hidden surface removal processing to determine the hidden surface. Directly illuminated surface elements, generating a set of rays. ;in, It is a plane wave.

[0018] In one possible design, for each ray, the intersecting face elements are sequentially labeled to obtain a plurality of intersecting face element sets, including:

[0019] Calculate with each of the aforementioned rays The intersecting surface elements; wherein, for One of the rays mentioned above, where α is a positive integer representing the ray number;

[0020] Mark the rays in the order of intersection. The intersecting face elements are combined to form an intersecting face element set, which includes multiple face element elements. α is the sequence number of the ray, and β is the sequence number of the intersection between the surface element and the ray.

[0021] In one possible design, the calculation of the total scattered field based on the set of intersecting surface elements using the small slope approximation method includes:

[0022] Calculate the surface element reflection field ;

[0023] The surface element is calculated using the small slope approximation method. Scattering field ;

[0024] Calculate the total scattered field.

[0025] In one possible design, the calculation of the surface element... reflection field ,include:

[0026]

[0027] in, For the reflected field, , For Fresnel reflection coefficient, Let α be the wave vector of the seawater, β be the index of the ray, and β be the index of the intersection between the surface element and the ray. for β -1 The surface element and β Optical path difference between surface elements.

[0028] In one possible design, the small slope approximation method is used to calculate the surface element. Scattering field ,include:

[0029]

[0030] in, To and The corresponding small slope approximate scattering coefficient.

[0031] In one possible design, calculating the total scattered field includes:

[0032]

[0033] in, This represents the total scattered field.

[0034] In one possible design, calculating the average backscattering coefficient based on the plurality of total scattered fields includes:

[0035] generate The geometric model of the sea surface described in the figure was calculated to obtain Group Calculate the average backscattering coefficient :

[0036]

[0037] in, For the total scattered field, It is a plane wave. , This refers to the radar's lateral resolution.

[0038] Compared with the prior art, the present invention has at least the following beneficial effects:

[0039] In this invention, the small slope approximation method and the ray tracing method are combined to calculate the average backscattering coefficient of sea clutter. The method provided in this application has high calculation efficiency, a wide range of applicable incident angles, and high calculation accuracy. Attached Figure Description

[0040] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0041] Figure 1 This is a flowchart illustrating a high-precision calculation method for the average backscattering coefficient of sea clutter in high sea state, provided by an embodiment of the present invention.

[0042] Figure 2 This is a schematic diagram of the calculation results of the HH polarization average backscattering coefficient, which is a high-precision calculation method for the average backscattering coefficient of sea clutter in high sea state provided by an embodiment of the present invention.

[0043] Figure 3 This is a schematic diagram of the calculation results of the VV polarization average backscattering coefficient, which is a high-precision calculation method for the average backscattering coefficient of sea clutter in high sea state provided by an embodiment of the present invention. Detailed Implementation

[0044] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0045] In the description of the embodiments of the present invention, unless otherwise expressly specified and limited, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance; unless otherwise specified or stated, the term "multiple" refers to two or more; the terms "connected," "fixed," etc., should be interpreted broadly. For example, "connected" can be a fixed connection, a detachable connection, an integral connection, or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in the present invention according to the specific circumstances.

[0046] In this specification, it should be understood that the directional terms such as "upper" and "lower" used in the description of the embodiments of the present invention are used to describe the angles shown in the accompanying drawings and should not be construed as limiting the embodiments of the present invention. Furthermore, in the context, it should also be understood that when it is mentioned that one element is connected "upper" or "lower" to another element, it can be directly connected to the other element "upper" or "lower," or indirectly connected to the other element "upper" or "lower" through an intermediate element.

[0047] like Figures 1 to 3 As shown, this embodiment of the invention provides a high-precision method for calculating the average backscattering coefficient of sea clutter in high sea states, including:

[0048] A three-dimensional sea surface geometry model in the form of surface elements is generated based on the sea surface spectral function; wherein, the sea surface geometry model includes multiple surface elements;

[0049] Under the illumination of plane waves, the ray tracing method is applied to the geometric model of the sea surface to generate a ray set; the ray set includes multiple rays.

[0050] For each ray, the intersecting surface elements are labeled sequentially to obtain multiple sets of intersecting surface elements;

[0051] The total scattered field is calculated by applying the small slope approximation method based on a set of multiple intersecting surface elements.

[0052] The average backscattering coefficient is calculated based on multiple total scattered fields.

[0053] In this invention, the small slope approximation method and the ray tracing method are combined to calculate the average backscattering coefficient of sea clutter, such as... Figure 2 , Figure 3 As shown, the method provided in this application has high computational efficiency, a wide range of applicable incident angles, and high computational accuracy. , These are the average backscattering coefficients of sea clutter waves with HH and VV polarizations, respectively. The angle of incidence is denoted as .

[0054] In some embodiments of the present invention, generating a three-dimensional sea surface geometry model in the form of surface elements based on a spectral function includes:

[0055] Let the specific form of the spectral function be: ;in, The traveling wave vector of seawater, Wind speed over sea surface;

[0056] A 3D sea surface geometry model in the form of surface elements is generated using nonlinear generation techniques; wherein, the projection of the sea surface geometry model onto the horizontal plane is a side length of... a square, , This refers to the radar's lateral resolution.

[0057] The geometric model of the sea surface is divided into equal parts. The side length is A square element.

[0058] In some embodiments of the present invention, under the illumination of a plane wave, a ray tracing method is applied to the geometric model of the sea surface to generate a ray set, including:

[0059] The sea surface geometry model is subjected to hidden surface removal processing to determine the hidden surface. Directly illuminated surface elements, generating a set of rays. ;in, It is a plane wave.

[0060] In some embodiments of the present invention, for each ray, the intersecting surface elements are sequentially labeled to obtain a plurality of intersecting surface element sets, including:

[0061] Calculate with each ray Intersecting face elements; among them, for A ray in the array, where α is a positive integer representing the ray's index;

[0062] Mark the intersections with the rays in order of their order. Intersecting face elements result in an intersecting face element set, which contains multiple face element elements. α is the ray number, and β is the intersection number of the surface element and the ray.

[0063] In some embodiments of the present invention, the total scattered field is calculated using the small slope approximation method based on a plurality of intersecting surface element sets, including:

[0064] Calculate surface elements reflection field ;

[0065] Calculating surface element using the small slope approximation method Scattering field ;

[0066] Calculate the total scattered field.

[0067] In some embodiments of the present invention, surface element calculation is performed. reflection field ,include:

[0068]

[0069] in, For the reflected field, , For Fresnel reflection coefficient, Let α be the wave vector of the seawater, β be the index of the ray, and β be the index of the intersection between the surface element and the ray. for β -1 square meter and β Optical path difference between surface elements.

[0070] Specifically, first calculate the reflection field when β equals 1. In the above formula, the right side of the equal sign... for , , , , Given the conditions, we can then obtain... 1. 1. Substitute into the above formula to calculate 2. Iterate through all β values ​​to obtain all scattered fields. Using the same method, we first set α to 1, then iterate through all α values, eventually obtaining all... .

[0071] In some embodiments of the present invention, the small slope approximation method is applied to calculate surface element. Scattering field ,include:

[0072]

[0073] in, To and The corresponding small slope approximate scattering coefficient.

[0074] The small slope approximation method is existing technology, and the specific method will not be described in detail in this application.

[0075] In some embodiments of the present invention, calculating the total scattering field includes:

[0076]

[0077] in, This represents the total scattered field.

[0078] In some embodiments of the present invention, the average backscattering coefficient is calculated based on multiple total scattered fields, including:

[0079] generate The geometric model of the sea surface was calculated to obtain Group Calculate the average backscattering coefficient :

[0080]

[0081] in, For the total scattered field, It is a plane wave. , This refers to the radar's lateral resolution.

[0082] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A high-precision calculation method for the average backscattering coefficient of sea clutter in high sea state, characterized in that, include: A three-dimensional sea surface geometry model in the form of surface elements is generated based on the sea surface spectral function; wherein, the sea surface geometry model includes multiple surface elements; Under the illumination of a plane wave, a ray tracing method is applied to the geometric model of the sea surface to generate a ray set; wherein the ray set includes multiple rays; For each ray, the surface elements that intersect the ray are marked sequentially to obtain a set of multiple intersecting surface elements; The total scattered field is calculated using the small slope approximation method based on the multiple sets of intersecting surface elements. The average backscattering coefficient is calculated based on the total scattered fields. The method of generating a three-dimensional sea surface geometry model in the form of surface elements based on the spectral function includes: Let the specific form of the spectral function be: ;in, The traveling wave vector of seawater, Wind speed over sea surface; A 3D sea surface geometry model in the form of surface elements is generated using nonlinear generation techniques; wherein, the projection of the sea surface geometry model onto the horizontal plane is a side length of... a square, , This refers to the radar's lateral resolution. The geometric model of the sea surface is divided into equal parts. The side length is A square element.

2. The high-precision calculation method according to claim 1, characterized in that, The process of applying ray tracing to the sea surface geometry model under plane wave illumination to generate a ray set includes: The sea surface geometry model is subjected to hidden surface removal processing to determine the hidden surface. Directly illuminated surface elements, generating a set of rays. ;in, It is a plane wave.

3. The high-precision calculation method according to claim 2, characterized in that, For each ray, the intersecting surface elements are sequentially labeled to obtain a set of multiple intersecting surface elements, including: Calculate with each of the aforementioned rays The intersecting surface elements; wherein, for One of the rays mentioned above, where α is a positive integer representing the ray number; Mark the intersecting rays in order of their sequence. The intersecting face elements are combined to form an intersecting face element set, which includes multiple face element elements. α is the sequence number of the ray, and β is the sequence number of the intersection between the surface element and the ray.

4. The high-precision calculation method according to claim 3, characterized in that, The step of calculating the total scattered field based on multiple sets of intersecting surface elements using the small slope approximation method includes: Calculate the surface element reflection field ; The surface element is calculated using the small slope approximation method. Scattering field ; Calculate the total scattered field.

5. The high-precision calculation method according to claim 4, characterized in that, The calculation of the surface element reflection field ,include: in, For the reflected field, , For Fresnel reflection coefficient, Let α be the wave vector of the seawater, β be the index of the ray, and β be the index of the intersection between the surface element and the ray. for β -1 square meter and β Optical path difference between surface elements.

6. The high-precision calculation method according to claim 4, characterized in that, The small slope approximation method is used to calculate the surface element. Scattering field ,include: in, To and The corresponding small slope approximate scattering coefficient.

7. The high-precision calculation method according to claim 1, characterized in that, The calculation of the total scattered field includes: in, For the total scattered field, For surface element The scattered field.

8. The high-precision calculation method according to claim 1, characterized in that, The calculation of the average backscattering coefficient based on the plurality of total scattered fields includes: generate The geometric model of the sea surface described in the figure was calculated to obtain Group Calculate the average backscattering coefficient : in, For the total scattered field, It is a plane wave. , This refers to the radar's lateral resolution.

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