SAR satellite calibration test site construction method, device and electronic equipment

Abstract

The present invention provides a method, device and electronic equipment for constructing a SAR satellite calibration and inspection site, wherein the method for constructing a SAR satellite calibration and inspection site includes: obtaining a target layout area for SAR satellite calibration and inspection; determining target calibration equipment that can meet the coverage requirements of different modes of SAR satellites; and arranging the target calibration equipment in the target layout area based on a preset central hierarchical construction principle, wherein the preset central hierarchical construction principle includes expanding outward layer by layer with a core layout sub-area in the target layout area as the center and arranging the target calibration equipment in the expanded sub-areas and the core layout sub-areas. The method of the present invention can achieve the goal of constructing a multi-mode SAR satellite calibration and inspection site, thereby also being able to realize different calibration and inspection tasks of multi-model, multi-band and multi-mode SAR satellites according to different widths and resolutions of SAR satellites, and meeting the requirements of comprehensive multi-task calibration and inspection of SAR satellites.

Description

Technical Field

[0001] The present invention relates to the field of satellite detection technology, and in particular to a method, device and electronic equipment for constructing a SAR satellite calibration inspection site. Background Art

[0002] Synthetic Aperture Radar (SAR) satellites have the ability to observe the earth around the clock and in all weather conditions, and are not affected by bad weather such as clouds and rain. They play an important role in disaster emergency monitoring, agricultural monitoring, land and resources surveys, topographic surveys, and ocean dynamic environment measurements, which have high timeliness requirements. Radiation calibration is the basis for quantitative applications, and authenticity verification is an effective means to evaluate the quality of remote sensing products. The calibration and verification site is the source of ground reference, which is crucial to SAR satellite radiation calibration and authenticity verification. Therefore, the design and construction of ground calibration and verification sites can promote the process of quantitative application of SAR satellite data.

[0003] In the related art, a calibration and inspection field construction method of temporary deployment, small scale and single function is usually adopted to determine the calibration field, and the determined calibration field is mostly temporarily deployed with active calibrators or corner reflectors during in-orbit testing. The scale is generally small and it is impossible to realize the calibration and inspection of wide-bandwidth SAR satellites, resulting in low reliability and accuracy of the calibration and inspection. Summary of the invention

[0004] The present invention provides a SAR satellite calibration and inspection site construction method, device and electronic equipment, which are used to solve the defects of low reliability and accuracy of calibration and inspection caused by the calibration and inspection site construction method of the prior art that adopts a temporary layout, small scale and single function to determine the calibration site, realize different calibration and inspection tasks of multi-model, multi-band and multi-mode SAR satellites, and meet the needs of comprehensive multi-task calibration and inspection of SAR satellites.

[0005] The present invention provides a method for constructing a SAR satellite calibration inspection site, comprising:

[0006] Obtain the target deployment area for SAR satellite calibration verification;

[0007] Determine target calibration equipment that can meet the coverage requirements of different modes of the SAR satellite;

[0008] Based on the preset center level construction principle, the target calibration equipment is deployed in the target deployment area;

[0009] Among them, the preset central level construction principle includes expanding outward layer by layer with the core layout sub-area in the target layout area as the center and deploying the target calibration equipment in the expanded sub-areas and the core layout sub-area.

[0010] According to a SAR satellite calibration inspection site construction method provided by the present invention, when the preset center level construction principle includes a preset single center multi-level construction principle, the target calibration equipment is arranged in the target arrangement area based on the preset center level arrangement principle, including:

[0011] Based on the preset single-center multi-level construction principle, determine the core layout sub-area within the target layout area;

[0012] Determine to perform outward expansion operations layer by layer with the core layout sub-area as the center and the preset value of the standard width of each mode of the SAR satellite as the size of the layout sub-area corresponding to each mode, so as to obtain each outward expansion layout sub-area;

[0013] The target calibration equipment is respectively arranged in the external expansion sub-area and the core sub-area.

[0014] According to a SAR satellite calibration inspection site construction method provided by the present invention, when the preset center level construction principle includes a multi-center multi-level construction principle, the target calibration equipment is arranged in the target arrangement area based on the preset center level arrangement principle, including:

[0015] Based on the multi-center and multi-level construction principle, determine a core layout sub-area and at least one sub-center layout sub-area within the target layout area;

[0016] Determine the size of the sub-regions corresponding to the modes with the core layout sub-region as the center and the preset value of the standard width of each mode of the SAR satellite as the size of the sub-regions corresponding to the modes, and perform layer-by-layer outward expansion operations along the direction of the expanded layout area of ​​the core layout sub-region and / or along the sub-center layout sub-region to obtain each outward expansion sub-region;

[0017] The target calibration equipment is respectively arranged in the outer expansion sub-area, the core sub-area and the sub-center sub-area.

[0018] According to a SAR satellite calibration inspection site construction method provided by the present invention, the target calibration equipment that can meet the coverage requirements of different modes of the SAR satellite is determined, including:

[0019] Determine the minimum radar cross-sectional area of ​​the target deployment area under different modes of the SAR satellite;

[0020] According to the relationship between the minimum radar cross-sectional area and the radar cross-sectional area of ​​the initial calibration device, a target calibration device that can meet the coverage requirements of different modes of the SAR satellite is determined.

[0021] According to a SAR satellite calibration test site construction method provided by the present invention, the determining of the minimum radar cross-sectional area of ​​the target deployment area in different modes of the SAR satellite includes:

[0022] Determining a backscatter coefficient map of the target deployment area;

[0023] Based on the backscatter coefficient map, dividing the target deployment area into a plurality of deployment areas of interest;

[0024] Determining an average backscatter coefficient for each of the deployment areas of interest;

[0025] Based on the average backscatter coefficient, the minimum target radar cross-sectional area of ​​each of the deployment areas of interest under different modes of the SAR satellite is calculated.

[0026] According to a SAR satellite calibration test site construction method provided by the present invention, the minimum target radar cross-sectional area of ​​each of the deployment areas of interest under different modes of the SAR satellite is calculated based on the average backscatter coefficient, and the calculation formula is:

[0027]

[0028] Wherein, SCR represents the preset signal-to-noise ratio target value, represents the average backscatter coefficient of the kth deployment area of ​​interest, λ a represents the pixel spacing of the SAR satellite mode λ in azimuth, λ r represents the pixel spacing of the SAR satellite mode λ in the range direction, represents the minimum radar cross section of the kth deployment area of ​​interest of the SAR satellite in mode λ.

[0029] According to a SAR satellite calibration test site construction method provided by the present invention, the target calibration equipment that can meet the coverage requirements of different modes of the SAR satellite is determined according to the relationship between the minimum radar cross-sectional area and the radar cross-sectional area of ​​the initial calibration equipment, including:

[0030] Calculate the radar cross section of the initial calibration equipment;

[0031] Determining whether the radar cross section area of ​​the initial calibration device meets the minimum radar cross section area;

[0032] When the radar cross section of the initial calibration device meets the minimum radar cross section, the initial calibration device is determined as the target calibration device.

[0033] The present invention also provides a SAR satellite calibration test site construction device, comprising:

[0034] An acquisition module is used to acquire a target deployment area for SAR satellite calibration verification;

[0035] A determination module, used to determine a target calibration device that can meet the coverage requirements of different modes of the SAR satellite;

[0036] A deployment module is used to deploy the target calibration equipment in the target deployment area based on a preset central hierarchical construction principle; wherein the preset central hierarchical construction principle includes expanding outward layer by layer with a core deployment sub-area in the target deployment area as the center and deploying the target calibration equipment in the expanded sub-areas and the core deployment sub-areas.

[0037] The present invention also provides an electronic device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the program, the steps of any of the above-mentioned methods for constructing a SAR satellite calibration and inspection site are implemented.

[0038] The present invention also provides a non-transitory computer-readable storage medium having a computer program stored thereon. When the computer program is executed by a processor, the steps of the method for constructing a SAR satellite calibration and verification site as described in any one of the above are implemented.

[0039] The present invention provides a SAR satellite calibration and inspection site construction method, device and electronic equipment, wherein the SAR satellite calibration and inspection site construction method obtains a target layout area for SAR satellite calibration and inspection and determines a target calibration device that can meet the coverage requirements of different modes of SAR satellites, and then based on a preset center level construction principle, the target calibration device is deployed in the target layout area. Since the preset center level construction principle includes expanding outward layer by layer with the core layout sub-area in the target layout area as the center and deploying the target calibration device in the expanded sub-area and the core layout sub-area, it is possible to achieve the goal of multi-mode SAR satellite calibration and inspection site construction by fixing the target calibration device in the target layout area according to different calibration and inspection task requirements, thereby being able to achieve different calibration and inspection tasks of multi-model, multi-band and multi-mode SAR satellites according to different widths and resolutions of SAR satellites, meeting the requirements of SAR satellite comprehensive multi-task calibration and inspection. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0041] Figure 1 It is a flow chart of the method for constructing a SAR satellite calibration and inspection site provided by the present invention;

[0042] Figure 2 It is a schematic diagram of a single-center multi-level layout method for a SAR satellite high-resolution and small-width mode provided by the present invention;

[0043] Figure 3 It is a schematic diagram of a multi-center and multi-level layout method for a low-resolution and wide-bandwidth mode of a SAR satellite provided by the present invention;

[0044] Figure 4 It is a schematic diagram of the layout of the radiation calibration test for the SAR satellite small-width mode provided by the present invention;

[0045] Figure 5 It is a schematic diagram of the layout of the SAR satellite geometric calibration test provided by the present invention;

[0046] Figure 6 This is a schematic diagram of the layout of the polarization calibration test for SAR satellites provided by the present invention;

[0047] Figure 7 It is a structural schematic diagram of the SAR satellite calibration and inspection field construction device provided by the present invention;

[0048] Figure 8 It is a structural schematic diagram of the electronic device provided by the present invention. DETAILED DESCRIPTION

[0049] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0050] With the development of remote sensing application technology, industry applications have put forward higher requirements for the accuracy of SAR satellite data and the reliability of quantitative products. However, my country has not yet formed a quantitative support system that can effectively serve the business operations of industry departments. Radiometric calibration is the basis of quantitative application, and authenticity verification is an effective means to evaluate the quality of remote sensing products. The calibration and inspection field is the source of ground reference, which is crucial for SAR satellite radiometric calibration and authenticity verification.

[0051] Commonly used methods for SAR calibration verification include radiation calibration verification based on point targets and distributed targets. In actual work, point targets are easier to implement than large-area distributed targets with known scattering characteristics and uniform stability, and can achieve the calibration accuracy required by the design. Therefore, calibration verification based on point targets is a commonly used method. SAR satellite calibration verification methods based on point targets include methods using active calibrators (Active Radar Calibrator, ARC) and passive point targets (such as corner reflectors, Corner Reflectors, CR); active calibrators can simulate ground point targets with accurately known radar cross-sectional areas by forwarding SAR signals. Corner reflectors have simple structures, stable performance, convenient deployment, and low cost. They can be used as ground point targets with accurately known radar cross-sectional areas and are practical equipment for SAR satellite calibration verification.

[0052] In order to realize the multi-characteristic calibration and inspection of multi-mode spaceborne SAR systems, the design of the calibration and inspection site construction plan is crucial. Most of the existing calibration sites in China are temporarily deployed with active calibrators or corner reflectors during the in-orbit period. They are generally small in scale and cannot realize the calibration and inspection of wide-bandwidth SAR satellites. In addition, the ground equipment does not have the ability of fixed deployment and remote control, and lacks a multifunctional calibration and inspection equipment array for periodic inspection and long-term operation. During the mission, not only a lot of manpower and material resources are required for equipment debugging, but also the frequency of data acquisition and the stability and reliability of the data are seriously affected. At present, most calibration and inspection sites are built for a certain type of SAR satellite, and their comprehensive service capabilities are relatively weak, which cannot meet the field deployment requirements of "one site for multiple uses".

[0053] At present, the construction of SAR satellite radiation calibration and authenticity verification sites in my country has just started, and there are still many shortcomings: (1) The number of SAR satellite calibration and verification sites is seriously insufficient, and the representativeness and credibility of the "true value" are poor; (2) The "true value" data observations are scattered, lacking standardization and systematization, and have poor sustainability; (3) The level of automation in "true value" data collection is low, which seriously affects the frequency and stability of data acquisition; (4) There is no networked observation scale, and it is difficult to share and synchronously cross-validate the "true value" data between sites.

[0054] Based on the above problems, the present invention provides a SAR satellite calibration and verification site construction method. The SAR satellite calibration and verification site construction method can be executed by a SAR satellite calibration and verification site construction device. The SAR satellite calibration and verification site construction device can be implemented as part or all of a terminal device through software, hardware, or a combination of software and hardware. Optionally, the terminal device can be a personal computer (PC), a portable device, a laptop computer, a smart phone, a tablet computer, a portable wearable device, or other electronic devices. The present invention does not limit the specific form of the terminal device.

[0055] It should be noted that the execution subject of the following method embodiment may be part or all of the above terminal device. The following method embodiment is described by taking the execution subject as the terminal device as an example.

[0056] Figure 1 The schematic diagram of the process of constructing the SAR satellite calibration test site provided by the present invention is as follows: Figure 1 As shown, the SAR satellite calibration test site construction method includes the following steps:

[0057] Step 110: Acquire a target deployment area for SAR satellite calibration verification.

[0058] Specifically, the target deployment area can be manually selected by pre-setting the calibration inspection field deployment principle, and then the target deployment area can be imported into the terminal device according to the latitude and longitude of the selected target deployment area, the features of the terrain, the features of the deployment point and other information, so that the terminal device can perform quantitative calibration inspection and analysis on the target deployment area. Among them, the deployment point can be the location of the deployment calibration device, and the calibration device can include an automatic corner reflector and an active calibrator.

[0059] It should be noted that the layout principles of the preset calibration test site may include: the layout points need to be located in the overlapping area of ​​SAR satellite orbit coverage; the background characteristics of the layout points are required to be flat, uniform and have low backscattering intensity, and they should be as far away as possible from places where perspective contraction, shadows and overlaps may occur; adjacent layout points should avoid mutual interference, especially for active calibrators with time delays, possible imaging overlap between adjacent layout points should be avoided, and the distance between adjacent layout points should be greater than 300 meters; the layout points should be as far away as possible from strong targets or interference signals (such as power towers, communication towers, etc.) strong reflectors); there should be no obstruction in the direction of the path of electromagnetic waves emitted by SAR near the deployment point, and it should be far away from objects that are prone to multiple scattering (such as room corners, sculptures, abandoned building materials, etc.). At the same time, it is necessary to reduce the backscattering effect of other components such as the equipment base on the SAR radar signal, such as laying absorbing cotton, etc.; the deployment point and its surrounding areas must have a certain degree of stability; the traffic conditions at the deployment point must ensure the normal passage of equipment transport vehicles; there is a 4G signal near the deployment point; the deployment point has good security; priority is given to deployment points with AC power and wired networks.

[0060] In addition, when calibration equipment such as automatic corner reflectors and active calibrators are placed in the target deployment area, the backscatter coefficient displayed on the SAR image obtained for the target deployment area includes the backscatter coefficient of other ground objects as the background in addition to the backscatter coefficient of the calibration equipment. Therefore, the backscatter coefficients of other ground objects as the background can be calculated on the SAR image measured without the calibration equipment.

[0061] Step 120: Determine a target calibration device that can meet the coverage requirements of different modes of the SAR satellite.

[0062] Specifically, since the types of SAR satellites are different, the corresponding bands are also different. Each SAR satellite includes multiple incident angles, multiple imaging modes and resolutions. In addition, each SAR satellite has a fixed calibration equation and is determined at the factory. Therefore, in order to ensure that a sufficient number of calibration devices are covered in each mode of the SAR satellite, the terminal device can determine the calibration inspection index of the corresponding calibration device based on the parameters of each calibration device, and then match the calculated calibration inspection index of each calibration device with the width requirements of each mode of the SAR satellite. When the calibration index of a certain calibration device matches the width requirement of the target mode of the SAR satellite, the calibration device can be determined as a target calibration device that meets the coverage requirements of different modes of the SAR satellite. The target mode can be at least one of the multiple modes of the SAR satellite, so that multiple different types of target calibration devices can be determined, so that the deployed target calibration devices can cover the width requirements of each mode of the SAR satellite.

[0063] Step 130: Based on a preset central level construction principle, the target calibration equipment is deployed in the target deployment area.

[0064] Among them, the preset central level construction principle includes expanding outward layer by layer with the core layout sub-area in the target layout area as the center and deploying the target calibration equipment in the expanded sub-areas and the core layout sub-area.

[0065] Specifically, the terminal device can first select a core deployment sub-area in the target calibration area for the target deployment area and the determined target calibration equipment. The core deployment sub-area needs to meet the selection conditions of uniform flatness and large area. The terminal device can select the core deployment sub-area in the target deployment area according to the preset selection conditions, and then perform layer-by-layer expansion operations with the core deployment sub-area as the center. The size of each expanded sub-area can be determined based on the shape of the core deployment sub-area and the standard width of each SAR satellite mode, and the target calibration equipment is correspondingly deployed in each expanded sub-area and the core deployment sub-area, so that a sufficient number of calibration equipment is covered in each mode of the SAR satellite. It should be noted that the preset center level construction principle can be a "one field, multiple uses" design principle.

[0066] The SAR satellite calibration and inspection site construction method provided by the present invention obtains the target layout area for SAR satellite calibration and inspection and determines the target calibration equipment that can meet the coverage requirements of different modes of SAR satellites, and then deploys the target calibration equipment in the target layout area based on the preset center level construction principle. Since the preset center level construction principle includes expanding outward layer by layer with the core layout sub-area in the target layout area as the center and deploying the target calibration equipment in the expanded sub-area and the core layout sub-area, it is possible to achieve the goal of building a multi-mode SAR satellite calibration and inspection site by fixing the target calibration equipment in the target layout area according to different calibration and inspection task requirements, so that different calibration and inspection tasks of multi-model, multi-band, and multi-mode SAR satellites can be realized according to the different widths and resolutions of the SAR satellites, meeting the requirements of comprehensive multi-task calibration and inspection of SAR satellites.

[0067] Optionally, the implementation process of step 120 may include:

[0068] First, the minimum radar cross-sectional area of ​​the target deployment area in different modes of the SAR satellite is determined; then, according to the relationship between the minimum radar cross-sectional area and the radar cross-sectional area of ​​the initial calibration equipment, the target calibration equipment that can meet the coverage requirements of the different modes of the SAR satellite is determined.

[0069] Specifically, the terminal device first obtains the SAR image data when the SAR satellite passes through the target deployment area, and analyzes it in combination with the SAR image data, various parameter information of the SAR satellite itself, and the geographical features of the target deployment area to determine the minimum radar scattering cross-sectional area of ​​the target deployment area under different modes of the SAR satellite, and then further matches the minimum radar scattering cross-sectional area with the radar scattering cross-sectional area of ​​the initial calibration device, so as to determine the target calibration device that meets the coverage requirements of different modes of the SAR satellite. Among them, when the initial calibration device includes an automatic corner reflector and an active calibrator, the radar scattering cross-sectional area of ​​the automatic corner reflector with different side lengths and different wavelengths and the radar scattering cross-sectional area of ​​the active calibrator with different gears can be matched with the minimum radar scattering cross-sectional area respectively, and the active calibrator and automatic corner reflector that meet the coverage requirements of different modes of the SAR satellite after matching are determined as the target calibration device.

[0070] The SAR satellite calibration and inspection field construction method provided by the present invention selects target calibration equipment that can meet the coverage requirements of different modes of the SAR satellite from the initial calibration equipment according to the relationship between the minimum radar scattering cross-section of the target layout area under different modes of the SAR satellite and the radar scattering cross-section of the initial calibration equipment, so that the target calibration equipment can be remotely controlled and adjusted according to the requirements of different calibration and inspection tasks, meeting the requirements of long-term fixation, periodic inspection, and automatic operation, effectively improving the frequency of ground data acquisition, ensuring the stability and reliability of ground reference data, and effectively reducing the manual repetitive work in the field calibration and inspection experiment, saving a lot of manpower, material and financial resources.

[0071] Optionally, determining the minimum radar cross-sectional area of ​​the target deployment area in different modes of the SAR satellite includes:

[0072] First, a backscatter coefficient map of the target layout area is determined; then, based on the backscatter coefficient map, the target layout area is divided into a plurality of layout areas of interest; then, an average backscatter coefficient of each of the layout areas of interest is further determined; finally, based on the average backscatter coefficient, a minimum target radar cross-sectional area of ​​each of the layout areas of interest under different modes of the SAR satellite is calculated.

[0073] Specifically, when the target deployment area is determined, one or more SAR image data for the target deployment area can be obtained when the SAR satellite passes by, and the one or more SAR image data are subjected to relative radiation correction and absolute radiation correction to obtain a backscatter coefficient map of the target deployment area. The commonly used backscatter coefficient calculation formula for each pixel in the backscatter coefficient map of the target deployment area is: σ0 represents the backscattering coefficient corresponding to the ground object, K represents the absolute radiation calibration constant; DN 2 Represents the intensity value corresponding to the SAR image data, and the value of DN can be calculated from the real part I and imaginary part Q of the SAR image data. 2 =I 2 +Q 2 .

[0074] It should be noted that one or more SAR image data for the target deployment area taken when the SAR satellite passes over can be obtained from the image data stored in the terminal device, or one or more SAR image data for the target deployment area can be retrieved from an image database taken when the SAR satellite passes over the deployment area.

[0075] Furthermore, M layout areas of interest are drawn from the backscatter coefficient map of the target layout area. The M layout areas of interest can be manually selected when determining the target layout area. For example, the vector files of the M layout areas of interest of the target layout area can be imported into the terminal device, so that the terminal device frames M layout areas of interest on the target layout area according to the vector files, where M is a positive integer; each layout area of ​​interest can also be manually determined according to the longitude and latitude or some surrounding positioning features, and the longitude and latitude or positioning features of each layout area of ​​interest can be imported into the terminal device; the position of each layout area of ​​interest can also be found by visual interpretation by the human eye, so that each layout area of ​​interest can be displayed in the backscatter coefficient map.

[0076] In addition, the average backscatter coefficient of each layout area of ​​interest can be obtained by statistically averaging the backscatter coefficients of the corresponding layout area of ​​interest, and then the minimum target radar cross-sectional area of ​​each layout area of ​​interest under different SAR satellite modes is calculated based on the average backscatter coefficient of each layout area of ​​interest. The calculation formula is shown in formula (1):

[0077]

[0078] Wherein, SCR represents the preset signal-to-noise ratio target value, represents the average backscatter coefficient of the kth deployment area of ​​interest, λ a represents the pixel spacing of the SAR satellite mode λ in azimuth, λ r represents the pixel spacing of the SAR satellite mode λ in the range direction, represents the minimum radar cross section of the kth deployment area of ​​interest of the SAR satellite in mode λ.

[0079] It should be noted that when SCR is greater than 20dB, the target and the background can be effectively distinguished and the interference of the target by the background clutter can be guaranteed to be within 0.5dB. Therefore, the present invention takes the signal-to-clutter ratio of 20dB as a target example to calculate the minimum radar cross-sectional area RCS required for each mode of the SAR satellite, wherein the signal-to-clutter ratio calculation formula is shown in formula (2):

[0080]

[0081] Among them, σ T is the radar cross-section area corresponding to each initial calibration device, <σ C > is the average background clutter radar cross-sectional area, θ i is the local angle of incidence for each initial calibration device, δ a is the pixel spacing size of the SAR satellite azimuth, δ r is the pixel spacing of the SAR satellite in the range direction, <σo > is the normalized average background clutter radar cross section.

[0082] In actual operation, the local incident angle θ can be ignored. i The influence caused by this is that the nominal resolution λ of the SAR satellite target mode in azimuth and range is a and λ r Instead of the pixel spacing δ in the azimuth and distance directions a and δ r , taking the average backscatter coefficient of the target deployment area as Instead of the normalized average background clutter radar cross section <σ o >After that, the minimum target radar cross-section area of ​​each deployment area of ​​interest under different SAR satellite modes can be estimated when SCR = 20dB

[0083] Based on the above principle, the minimum target radar cross-section of each layout area of ​​interest in different SAR satellite modes is calculated, that is, when SCR = 20 dB, according to the nominal resolution in azimuth and range directions of different SAR satellite modes (which can be obtained through the data header file) and the average backscatter coefficient of each layout area of ​​interest, the minimum target radar cross-section of each layout area of ​​interest in different SAR satellite modes is estimated.

[0084] The satellite calibration test site construction method provided by the present invention first divides the target deployment area into a plurality of deployment areas of interest based on the backscatter coefficient map of the target deployment area, and then calculates the minimum target radar scattering cross-sectional area of ​​each deployment area of ​​interest under different SAR satellite modes by determining the average backscatter coefficient of each deployment area of ​​interest, thereby achieving the purpose of quickly and accurately calculating the minimum radar scattering cross-sectional area of ​​the target deployment area under different SAR satellite modes, thereby providing a strong basis for the subsequent flexible and sufficient deployment of target calibration equipment in the target calibration area.

[0085] Optionally, determining the target calibration device that can meet the coverage requirements of different modes of the SAR satellite according to the relationship between the minimum radar cross-sectional area and the radar cross-sectional area of ​​the initial calibration device includes:

[0086] First, the radar cross-section of the initial calibration device is calculated; then, it is determined whether the radar cross-section of the initial calibration device meets the minimum radar cross-section; finally, when the radar cross-section of the initial calibration device meets the minimum radar cross-section, the initial calibration device is determined as the target calibration device.

[0087] Specifically, when the initial calibration device includes an automatic corner reflector and an active calibrator, the radar scattering area of ​​each automatic corner reflector can be calculated according to formula (3) and the radar scattering cross-sectional area of ​​the active calibrator of each gear can be calculated according to formula (4).

[0088]

[0089]

[0090] Where, σ represents the theoretical value of the radar cross-sectional area of ​​the automatic corner reflector, a represents the length of the right-angle side of the automatic corner reflector, λ represents the wavelength of the SAR satellite payload, G c represents the SAR satellite transmit and receive antenna gain, G a represents the gain of the SAR satellite forwarding channel, σ ARC Indicates the nominal value of the radar cross-section for each gear position of the active calibrator.

[0091] Then determine whether the radar cross-section of the automatic corner reflector with different modes (i.e. different wavelengths λ) and different side lengths a can meet the minimum target radar cross-section of each deployment area of ​​interest under different modes of the SAR satellite when SCR = 20dB. The minimum target radar cross-section of each deployment area of ​​interest in different modes of SAR satellites is calculated when the radar cross-section of automatic corner reflectors with different modes (i.e. different wavelengths λ) and different side lengths a is greater than or equal to SCR = 20dB. The corresponding automatic corner reflectors can be deployed as target calibration devices, so that each automatic corner reflector used as a target calibration device can be deployed within a width range that meets the corresponding radar cross-sectional area requirements; for example, when an automatic corner reflector meets the minimum target radar cross-sectional area of ​​10km width but does not meet the minimum target radar cross-sectional area of ​​100km width, the automatic corner reflector can be deployed within a width range of 10km.

[0092] Further, it is determined whether the radar cross-sectional area of ​​each gear of the active calibrator meets the minimum target radar cross-sectional area of ​​each deployment area of ​​interest under different SAR satellite modes when SCR = 20dB. The minimum target radar cross-section of each deployment area of ​​interest in different SAR satellite modes when the radar cross-section of each gear of the active calibrator is greater than or equal to SCR = 20dB The corresponding active calibrator can be deployed as a target calibration device to allocate the active calibrator that meets the gear requirements for use, so that each active calibrator is deployed within the width that meets the corresponding radar cross-sectional area requirements. For example, when the radar cross-sectional area of ​​an active calibrator in the second gear meets the minimum target radar cross-sectional area of ​​80km width and does not meet the minimum target radar cross-sectional area of ​​160km width, the automatic corner reflector can be deployed within the 80km width.

[0093] It should be noted that each SAR satellite contains multiple modes, and the width of each mode is different. Therefore, when making a judgment, the minimum target radar cross-section of each deployment area of ​​interest under different modes of the SAR satellite is used when SCR = 20dB. To match the radar cross-section of the initial calibration equipment (such as the radar cross-section of the automatic corner reflector or the radar cross-section of each gear of the active calibrator) requirements, when the radar cross-section of the initial calibration equipment meets SCR = 20dB, the minimum target radar cross-section of each deployment area of ​​interest in different SAR satellite modes When there is a need, the corresponding initial calibration device can be considered as the target calibration device for subsequent calibration inspection.

[0094] In addition, when the SAR satellite passes by for imaging, the azimuth and elevation pointing angles of the automatic corner reflector or active calibrator in the target calibration area are remotely adjusted to ensure that the calibration equipment is pointed in the same direction as the incident radar beam. The azimuth and elevation pointing accuracy of the automatic corner reflector can reach 0.1°, and the pointing accuracy of the active calibrator antenna can reach 0.2°, which reduces the impact of the deviation of the radar wave incident direction from the device pointing on the RCS and can provide high-precision ground reference point targets. Therefore, using the automatic corner reflector as a ground reference can provide an accurately known theoretical value of the radar cross-sectional area. By accurately measuring the side length a of the corner reflector, the theoretical value of the radar cross-sectional area of ​​the corner reflector is obtained by theoretical calculation; when the active calibrator is manufactured, the radar cross-sectional area range of the simulated point target will be designed according to the index requirements, and it will be set through different gears to calculate the radar cross-sectional area of ​​different gears.

[0095] The SAR satellite calibration and inspection field construction method provided by the present invention achieves the purpose of determining the target calibration equipment from the initial calibration equipment by judging whether the radar scattering cross-section of the initial calibration equipment meets the minimum target radar scattering cross-section of each of the interested deployment areas under different modes of the SAR satellite; further, when the determined target calibration equipment includes an automatic corner reflector and an active calibrator, the purpose of SAR satellite calibration and inspection can be achieved based on the active calibrator and the automatic corner reflector with fixed deployment, unattended, remote control, self-powered, and automatic operation capabilities, and the automatic corner reflector and the active calibrator can be remotely controlled and adjusted according to different calibration and inspection task requirements, meeting the requirements of long-term fixation, periodic inspection, and automatic operation, effectively improving the frequency of ground data acquisition, ensuring the stability and reliability of ground reference data, and effectively reducing manual repetitive work in field calibration and inspection experiments, saving a lot of manpower, material and financial resources.

[0096] Optionally, when the preset center-level construction principle includes a preset single-center multi-level construction principle, the implementation process of step 130 may include:

[0097] Firstly, based on the preset single-center multi-level construction principle, the core deployment sub-area in the target deployment area is determined; then, a layer-by-layer expansion operation is performed with the core deployment sub-area as the center and the preset value of the standard width of each mode of the SAR satellite as the size of the deployment sub-area corresponding to each mode to obtain each expanded deployment sub-area; finally, the target calibration equipment is respectively deployed in the expanded deployment sub-area and the core deployment sub-area.

[0098] Specifically, for the high-resolution and small-width mode of SAR satellites, the terminal equipment can be based on the preset single-center and multi-level construction principle. First, a uniformly flat and large area is selected in the target deployment area as the core deployment sub-area. For example, the core deployment sub-area can be a rectangular area. Then, in order to ensure that a sufficient number of target calibration devices are covered when there are differences in the orbital coverage of multiple SAR satellites or deviations in the orbital position of a single SAR satellite, 4 / 5 of the standard width of each mode can be used as the size of the corresponding rectangular deployment area of ​​each mode, and the target calibration equipment can be deployed in the four deployment quadrants divided by a diagonal line in the target deployment area. Through a layer-by-layer nesting method, it is ensured that a sufficient number of target calibration devices are covered in each mode.

[0099] For example, Figure 2As shown in the figure, when the SAR satellite is in high-resolution and small-width mode, a uniformly flat and large area is selected in the target layout area as the core layout sub-area, and it is divided into four layout quadrants. Then, with the core layout sub-area as the center and 4 / 5 of the standard width of each mode as the size of the rectangular layout area corresponding to each mode, it is expanded in a nested manner (for example, when the minimum width of the SAR satellite is 10km, the size of the core layout sub-area can be a rectangular area of ​​8km*8km), and the corresponding target calibration equipment that meets the minimum radar scattering cross-section required by each mode of the SAR satellite is determined in each layer of the expanded layout sub-area, and the determined target calibration equipment is evenly arranged in the four layout quadrants of each layer of the expanded layout sub-area, so as to ensure that a sufficient number of calibration equipment are covered in each standard width mode of the SAR satellite.

[0100] The SAR satellite calibration and inspection field construction method provided by the present invention realizes the purpose of respectively deploying target calibration equipment in each expanded deployment sub-area and the core deployment sub-area by taking the core deployment sub-area in the target deployment area as the center and taking the preset value of the standard width of each mode of the SAR satellite as the size of the deployment sub-area corresponding to each mode for layer-by-layer expansion operation, thereby meeting the various calibration and inspection task requirements of the SAR satellite high-resolution and small-width mode, and improving the flexibility and reliability of SAR satellite calibration and inspection.

[0101] Optionally, when the preset center-level construction principle includes a multi-center and multi-level construction principle, the implementation process of step 130 may include:

[0102] Firstly, based on the multi-center and multi-level construction principle, a core deployment sub-area and at least one sub-center deployment sub-area in the target deployment area are determined; then, with the core deployment sub-area as the center and the preset value of the standard width of each mode of the SAR satellite as the size of the deployment sub-area corresponding to each mode, a layer-by-layer expansion operation is performed along the direction of the expanded deployment area of ​​the core area deployment sub-area and / or along the direction of the sub-center deployment sub-area expansion to obtain each expanded deployment sub-area; finally, the target calibration equipment is respectively deployed in the expanded deployment sub-area, the core deployment sub-area and the sub-center deployment sub-area.

[0103] Specifically, when determining the outer expansion sub-area by expanding along the core deployment sub-area and / or along the sub-center deployment sub-area with the core deployment sub-area as the center and the preset value of the standard width of each mode of the SAR satellite as the size of the deployment sub-area corresponding to each mode, the core deployment sub-area, the sub-center deployment sub-area and the corresponding outer expansion sub-area can be further divided into four deployment quadrants, so as to evenly deploy the target calibration equipment in the four deployment quadrants of the outer expansion sub-area, the core deployment sub-area and the sub-center deployment sub-area.

[0104] It should be noted that for the low-resolution and wide-width mode of SAR satellites, the terminal equipment can be based on the principle of multi-center and multi-level construction, and can be divided into four quadrants along the diagonal of the target deployment area. On the basis of the layout based on the preset single-center and multi-level construction principle, a core deployment sub-area and several sub-center deployment sub-areas are selected to cooperate in the calibration test of the wide-width SAR satellite mode. For medium-width, such as 150km, the layout method based on the preset single-center and multi-level construction principle cannot meet the calibration test requirements of uniform layout of target calibration equipment. Therefore, the core deployment sub-area and the sub-center deployment sub-area are selected in the two diagonal quadrants upward from the SAR satellite distance, and nested layer by layer according to the multi-level method to cooperate in the calibration test of medium-width SAR satellites; and for the wide-width mode such as 300km, in order to ensure that the target calibration equipment is evenly distributed and sufficient in number, a core deployment sub-area can be selected in the target deployment area, and two sub-center deployment sub-areas can be selected on both sides of the core deployment sub-area along the SAR satellite distance, and the wide-width comprehensive task can be achieved in cooperation with the core deployment area.

[0105] For example, Figure 3 As shown in the figure, when the SAR satellite is in the low-resolution and wide-width mode, the target deployment area can be first divided into four quadrants along the diagonal line, and then a core deployment sub-area and several sub-center deployment sub-areas are selected in the target deployment area. For example, two sub-center deployment sub-areas are selected on both sides of the core deployment sub-area along the SAR satellite distance direction. When the core deployment sub-area is the center, the SAR satellite distance direction can be expanded to the left layer by layer, and the SAR satellite distance direction can be expanded to the right layer by layer. In this way, the two sub-center deployment sub-areas cooperate with the core deployment sub-area to complete the wide-width deployment task. At this time, the two sub-center deployment sub-areas can be used as the inspection area of ​​the core deployment area. The purpose of expansion and supporting the calibration inspection of the wide width can be achieved by placing calibration equipment with a larger radar scattering cross-section area, and the purpose of meeting the small-width SAR image inspection demand after the calibration of the core deployment area can be achieved by placing calibration equipment with a smaller radar scattering cross-section area as an inspection station.

[0106] It should be noted that by selecting two sub-center deployment sub-areas on both sides of the core deployment sub-area along the SAR satellite distance, the deployment range can be widened in the distance direction, so that when a certain number of deployment ranges are nested with the core deployment sub-area as the center and still cannot meet the large-scale width deployment requirements or the calibration equipment cannot be evenly deployed, it can continue to expand outward under the action of the sub-center deployment sub-area.

[0107] The SAR satellite calibration and inspection field construction method provided by the present invention realizes the purpose of respectively deploying target calibration equipment in the extended deployment sub-area, the core deployment sub-area and the sub-center deployment sub-area by taking the core deployment sub-area in the target deployment area as the center and the preset value of the standard width of each mode of the SAR satellite as the side length of the deployment sub-area corresponding to each mode, so as to meet the calibration and inspection task requirements of the SAR satellite multi-resolution and wide-width mode, not only supports long-term deployment and automatic operation under complex multi-SAR satellite multi-width mode conditions, but also can periodically serve the calibration and inspection of multi-mode SAR satellites, and provide strong technical support for the quantitative application of SAR images.

[0108] In the actual processing, when the target calibration equipment includes an active calibrator and an automatic corner reflector, for the small width mode radiation calibration test, the layout of the target calibration equipment can be implemented according to the "cross" plan, such as Figure 4 As shown. Several automatic corner reflectors or active calibrators with equal radar scattering cross-sections are arranged at equal intervals in the SAR satellite range direction. On the basis of avoiding the change of the antenna pattern caused by the SAR satellite attitude change, the relative radiation calibration accuracy of the SAR satellite, the range antenna pattern and the absolute radiation calibration constant are verified; in the azimuth direction, several active calibrators and automatic corner reflectors are arranged at equal intervals according to the size of the SAR radar scattering cross-section to verify the linear performance and absolute radiation calibration of the SAR system.

[0109] For geometric calibration inspection, please refer to Figure 5 Due to the slant range imaging principle of SAR satellites, different distances produce different geometric distortions. Therefore, during geometric calibration inspection, the target calibration equipment should be distributed as fully and evenly as possible in the SAR satellite range and azimuth directions. In order to meet the requirements of uniformly distributed geometric calibration inspection, the target deployment area is divided into four deployment quadrants along the diagonal line to ensure that all four deployment quadrants are covered by equipment.

[0110] For polarization calibration verification, please refer to Figure 6 For example, when the active calibrator is at 0°, 90°, and 45° relative to the SAR radar line of sight, the following can be generated: Three polarization scattering matrices. In the target deployment area, three active calibrators with orientation angles of 0°, 90° and 45° relative to the SAR radar line of sight form a triangle to solve the transmit and receive polarization distortion matrices; at the same time, an active calibrator with a default radar line of sight orientation angle (45°) is deployed at a position close to and far from the active calibrator group. While supporting polarization testing, it can also cooperate with radiation calibration and testing. If necessary, it can be combined with several motorized corner reflectors for multiple testing.

[0111] In the actual processing process, taking the construction of Xilinhot authenticity inspection station as an example, the Xilinhot Observatory field test base is taken as the deployment center. For 10km width, 5 active calibrators and 4 1m automatic corner reflectors are planned and designed in the 8km*8km core deployment sub-area; for 30km width, within the 25km*25km range around the core deployment sub-area, a total of 5 active calibrators, 7 1m automatic corner reflectors and 1 2m automatic corner reflector are deployed; for 100km width, within the 80k*80km range around the core deployment sub-area, a total of 5 active calibrators, 11 1m automatic corner reflectors and 2 2m automatic corner reflectors are deployed. For a swath width of 200 km, a total of 5 active calibrators, 11 1m automatic corner reflectors, and 2 2m automatic corner reflectors are planned and designed within the range of 160km*160km. The core deployment sub-area has 1 active calibrator and 3 1m automatic corner reflectors. For a swath width greater than 300km, 5 active calibrators, 11 1m automatic corner reflectors, and 2 2m automatic corner reflectors are deployed in the core deployment sub-area. Two sub-center deployment sub-areas are selected on both sides of the SAR satellite distance, and 1 1m active calibrator and 3 1m automatic corner reflectors are deployed respectively, to cooperate with the core deployment sub-area to achieve the wide-swath comprehensive task.

[0112] The results show that the SAR satellite calibration and inspection site construction method provided by the present invention is a multi-level SAR satellite calibration and inspection site construction method based on multi-site fixed deployment, which has good effects and can effectively meet the calibration and inspection requirements of multi-model, multi-band and multi-mode SAR satellites. In addition, the construction of the SAR satellite calibration and inspection site using the method of the present invention can make full use of the active calibrators and automatic corner reflectors that are fixedly deployed, unattended, automatically operated, self-powered and remotely controlled, effectively improve the frequency of ground data acquisition, ensure the stability and reliability of ground reference data, and save a lot of manpower, material and financial resources. In addition, the construction of the calibration and inspection site strictly follows the construction principle of "one site for multiple uses", which can meet the comprehensive multi-task calibration and inspection of multi-model, multi-band and multi-mode satellite-borne SAR radiation, polarization and geometry, etc., break through the limitations of the existing calibration and inspection sites that are temporarily deployed, small in scale and single in function, provide periodic inspection for SAR satellite data, and ensure the quality of SAR satellite data.

[0113] The SAR satellite calibration and verification site construction device provided by the present invention is described below. The SAR satellite calibration and verification site construction device described below and the SAR satellite calibration and verification site construction method described above can be referenced to each other.

[0114] Figure 7 An example of a SAR satellite calibration test site construction device is shown below. Figure 7 As shown, the SAR satellite calibration and inspection site construction device 700 includes: an acquisition module 710, used to acquire a target layout area for SAR satellite calibration and inspection; a determination module 720, used to determine a target calibration device that can meet the coverage requirements of different modes of the SAR satellite; a layout module 730, used to layout the target calibration device in the target layout area based on a preset center-level construction principle; wherein the preset center-level construction principle includes expanding outward layer by layer with a core layout sub-area in the target layout area as the center and arranging the target calibration device in the expanded sub-area and the core layout sub-area.

[0115] Optionally, the deployment module 730 can be specifically used to determine the core deployment sub-area in the target deployment area based on the preset single-center multi-level construction principle; determine the size of the deployment sub-area corresponding to each mode with the core deployment sub-area as the center and the preset value of the standard width of each mode of the SAR satellite as the size of each outward expansion operation to obtain each outward expansion sub-area; and respectively deploy the target calibration equipment in the outward expansion sub-area and the core deployment sub-area.

[0116] Optionally, the deployment module 730 can also be used to determine a core deployment sub-area and at least one sub-center deployment sub-area in the target deployment area based on the principle of multi-center and multi-level construction; determine the size of the deployment sub-area corresponding to each mode with the core deployment sub-area as the center and the preset value of the standard width of each mode of the SAR satellite, and perform layer-by-layer expansion operations in the direction of the expanded deployment area by expanding along the core deployment sub-area and / or along the sub-center deployment sub-area to obtain each expanded deployment sub-area; and respectively deploy the target calibration equipment in the expanded deployment sub-area, the core deployment sub-area and the sub-center deployment sub-area.

[0117] Optionally, determination module 720 can be specifically used to determine the minimum radar cross-sectional area of ​​the target deployment area under different modes of the SAR satellite; based on the relationship between the minimum radar cross-sectional area and the radar cross-sectional area of ​​the initial calibration device, determine the target calibration device that can meet the coverage requirements of different modes of the SAR satellite.

[0118] Optionally, the determination module 720 can also be specifically used to determine a backscatter coefficient map of the target deployment area; based on the backscatter coefficient map, divide the target deployment area into multiple deployment areas of interest; determine the average backscatter coefficient of each of the deployment areas of interest; based on the average backscatter coefficient, calculate the minimum target radar scattering cross-section of each of the deployment areas of interest under different modes of the SAR satellite.

[0119] Optionally, the determination module 720 may be specifically configured to calculate the minimum target radar cross-sectional area of ​​each deployment area of ​​interest under different modes of the SAR satellite based on the average backscatter coefficient, and the calculation formula is:

[0120]

[0121] Wherein, SCR represents the preset signal-to-noise ratio target value, represents the average backscatter coefficient of the kth deployment area of ​​interest, λ a represents the pixel spacing of the SAR satellite mode λ in azimuth, λ r represents the pixel spacing of the SAR satellite mode λ in the range direction, represents the minimum radar cross section of the kth deployment area of ​​interest of the SAR satellite in mode λ.

[0122] Optionally, the determination module 720 can also be used to calculate the radar cross-section of the initial calibration device; determine whether the radar cross-section of the initial calibration device meets the minimum radar cross-section; when the radar cross-section of the initial calibration device meets the minimum radar cross-section, determine the initial calibration device as the target calibration device.

[0123] Figure 8 An example of a physical structure diagram of an electronic device is shown in FIG. Figure 8 As shown, the electronic device 800 may include: a processor 810, a communication interface 820, a memory 830 and a communication bus 840, wherein the processor 810, the communication interface 820 and the memory 830 communicate with each other through the communication bus 840. The processor 810 may call the logic instructions in the memory 830 to execute the SAR satellite calibration test site construction method, which includes:

[0124] Obtain the target deployment area for SAR satellite calibration verification;

[0125] Determine target calibration equipment that can meet the coverage requirements of different modes of the SAR satellite;

[0126] Based on the preset center level construction principle, the target calibration equipment is deployed in the target deployment area;

[0127] Among them, the preset central level construction principle includes expanding outward layer by layer with the core layout sub-area in the target layout area as the center and deploying the target calibration equipment in the expanded sub-areas and the core layout sub-area.

[0128] In addition, the logic instructions in the above-mentioned memory 830 can be implemented in the form of a software functional unit and can be stored in a computer-readable storage medium when it is sold or used as an independent product. Based on this understanding, the technical solution of the present invention is essentially or the part that contributes to the prior art or the part of the technical solution can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including a number of instructions to enable a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk and other media that can store program codes.

[0129] On the other hand, the present invention further provides a computer program product, the computer program product includes a computer program, the computer program can be stored in a non-transitory computer-readable storage medium, when the computer program is executed by a processor, the computer can execute the SAR satellite calibration test site construction method provided by the above methods, the method includes:

[0130] Obtain the target deployment area for SAR satellite calibration verification;

[0131] Determine target calibration equipment that can meet the coverage requirements of different modes of the SAR satellite;

[0132] Based on the preset center level construction principle, the target calibration equipment is deployed in the target deployment area;

[0133] Among them, the preset central level construction principle includes expanding outward layer by layer with the core layout sub-area in the target layout area as the center and deploying the target calibration equipment in the expanded sub-areas and the core layout sub-area.

[0134] In another aspect, the present invention further provides a non-transitory computer-readable storage medium having a computer program stored thereon, and when the computer program is executed by a processor, the method for constructing a SAR satellite calibration inspection site provided by the above methods is implemented, and the method comprises:

[0135] Obtain the target deployment area for SAR satellite calibration verification;

[0136] Determine target calibration equipment that can meet the coverage requirements of different modes of the SAR satellite;

[0137] Based on the preset center level construction principle, the target calibration equipment is deployed in the target deployment area;

[0138] Among them, the preset central level construction principle includes expanding outward layer by layer with the core layout sub-area in the target layout area as the center and deploying the target calibration equipment in the expanded sub-areas and the core layout sub-area.

[0139] The device embodiments described above are merely illustrative, wherein the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the scheme of this embodiment. Ordinary technicians in this field can understand and implement it without paying creative labor.

[0140] Through the description of the above implementation methods, those skilled in the art can clearly understand that each implementation method can be implemented by means of software plus a necessary general hardware platform, and of course, it can also be implemented by hardware. Based on this understanding, the above technical solution is essentially or the part that contributes to the prior art can be embodied in the form of a software product, and the computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, a disk, an optical disk, etc., including a number of instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in each embodiment or some parts of the embodiments.

[0141] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for constructing a SAR satellite calibration test site, characterized in that: include: Obtain the target deployment area for SAR satellite calibration verification; Determine target calibration equipment that can meet the coverage requirements of different modes of the SAR satellite; Based on the preset center level construction principle, the target calibration equipment is deployed in the target deployment area; The preset center level construction principle includes expanding outwards layer by layer with the core layout sub-area in the target layout area as the center and arranging the target calibration equipment in the expanded sub-areas and the core layout sub-areas; Wherein, the target calibration device that can meet the coverage requirements of different modes of the SAR satellite is determined, including: Determine the minimum radar cross-sectional area of ​​the target deployment area under different modes of the SAR satellite; Determining a target calibration device that can meet the coverage requirements of different modes of the SAR satellite according to the relationship between the minimum radar cross-sectional area and the radar cross-sectional area of ​​the initial calibration device; Determining the minimum radar cross-sectional area of ​​the target deployment area in different modes of the SAR satellite includes: Determining a backscatter coefficient map of the target deployment area; Based on the backscatter coefficient map, dividing the target deployment area into a plurality of deployment areas of interest; Determining an average backscatter coefficient for each of the deployment areas of interest; Based on the average backscatter coefficient, calculating the minimum target radar cross-sectional area of ​​each of the deployment areas of interest under different modes of the SAR satellite; Based on the average backscatter coefficient, the minimum target radar cross-sectional area of ​​each of the deployment areas of interest under different modes of the SAR satellite is calculated, and the calculation formula is: Wherein, SCR represents the preset signal-to-noise ratio target value, represents the average backscatter coefficient of the kth deployment area of ​​interest, λ a represents the pixel spacing of the SAR satellite mode λ in azimuth, λ r represents the pixel spacing of the SAR satellite mode λ in the range direction, represents the minimum radar cross section of the kth deployment area of ​​interest of the SAR satellite in mode λ.

2. The SAR satellite calibration test site construction method according to claim 1, characterized in that: When the preset center level construction principle includes a preset single center multi-level construction principle, the target calibration device is arranged in the target arrangement area based on the preset center level arrangement principle, including: Based on the preset single-center multi-level construction principle, determine the core layout sub-area within the target layout area; Determine to perform outward expansion operations layer by layer with the core layout sub-area as the center and the preset value of the standard width of each mode of the SAR satellite as the size of the layout sub-area corresponding to each mode, so as to obtain each outward expansion layout sub-area; The target calibration equipment is respectively arranged in the external expansion sub-area and the core sub-area.

3. The SAR satellite calibration test site construction method according to claim 1, characterized in that: When the preset center level construction principle includes a multi-center multi-level construction principle, the target calibration device is arranged in the target arrangement area based on the preset center level arrangement principle, including: Based on the multi-center and multi-level construction principle, determine a core layout sub-area and at least one sub-center layout sub-area within the target layout area; Determine the size of the sub-regions corresponding to the modes with the core layout sub-region as the center and the preset value of the standard width of each mode of the SAR satellite as the size of the sub-regions corresponding to the modes, and perform layer-by-layer outward expansion operations along the direction of the expanded layout area of ​​the core layout sub-region and / or along the sub-center layout sub-region to obtain each outward expansion sub-region; The target calibration equipment is respectively arranged in the outer expansion sub-area, the core sub-area and the sub-center sub-area.

4. The SAR satellite calibration test site construction method according to claim 1 is characterized in that: The determining, according to the relationship between the minimum radar cross-sectional area and the radar cross-sectional area of ​​the initial calibration device, a target calibration device that can meet the coverage requirements of different modes of the SAR satellite comprises: Calculate the radar cross section of the initial calibration equipment; Determining whether the radar cross section area of ​​the initial calibration device meets the minimum radar cross section area; When the radar cross section of the initial calibration device meets the minimum radar cross section, the initial calibration device is determined as the target calibration device.

5. A SAR satellite calibration test site construction device, characterized in that: include: An acquisition module is used to acquire a target deployment area for SAR satellite calibration verification; A determination module, used to determine a target calibration device that can meet the coverage requirements of different modes of the SAR satellite; A deployment module, configured to deploy the target calibration equipment in the target deployment area based on a preset central hierarchical construction principle; wherein the preset central hierarchical construction principle includes expanding outward layer by layer with a core deployment sub-area in the target deployment area as the center and deploying the target calibration equipment in the expanded sub-areas and the core deployment sub-areas; Wherein, the target calibration device that can meet the coverage requirements of different modes of the SAR satellite is determined, including: Determine the minimum radar cross-sectional area of ​​the target deployment area under different modes of the SAR satellite; Determining a target calibration device that can meet the coverage requirements of different modes of the SAR satellite according to the relationship between the minimum radar cross-sectional area and the radar cross-sectional area of ​​the initial calibration device; Determining the minimum radar cross-sectional area of ​​the target deployment area in different modes of the SAR satellite includes: Determining a backscatter coefficient map of the target deployment area; Based on the backscatter coefficient map, dividing the target deployment area into a plurality of deployment areas of interest; Determining an average backscatter coefficient for each of the deployment areas of interest; Based on the average backscatter coefficient, calculating the minimum target radar cross-sectional area of ​​each of the deployment areas of interest under different modes of the SAR satellite; Based on the average backscatter coefficient, the minimum target radar cross-sectional area of ​​each of the deployment areas of interest under different modes of the SAR satellite is calculated, and the calculation formula is: Wherein, SCR represents the preset signal-to-noise ratio target value, represents the average backscatter coefficient of the kth deployment area of ​​interest, λ a represents the pixel spacing of the SAR satellite mode λ in azimuth, λ r represents the pixel spacing of the SAR satellite mode λ in the range direction, represents the minimum radar cross section of the kth deployment area of ​​interest of the SAR satellite in mode λ.

6. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the program, the steps of the SAR satellite calibration and verification site construction method as described in any one of claims 1 to 4 are implemented.

7. A non-transitory computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method for constructing a SAR satellite calibration and verification site as claimed in any one of claims 1 to 4 are implemented.

Images