A Satellite Formation Design Method and Device for Tomographic SAR Data Acquisition

Abstract

The present invention discloses a satellite formation design method and device for tomographic SAR data acquisition, belonging to the technical field of satellite formation design. The method includes determining the minimum sampling quantity required for tomographic processing according to design parameters; determining the optimal number of satellites and the transceiver mode setting according to the relationship between the number of satellites and the number of equivalent phase centers that can be generated; determining the arrangement of each satellite in the formation according to tomographic performance; calculating the maximum along-track baseline and the maximum cross-track baseline of the outermost satellite according to the arrangement of each satellite in the formation; calculating the formation parameters of the outermost satellite; determining the multi-satellite formation parameters according to the phase center approximation principle and formation geometry to obtain equally spaced equivalent phase centers; and calculating the six orbital elements of all satellites in the formation according to the multi-satellite formation parameters. The present invention does not introduce different atmospheric phases in each acquisition, reduces the data acquisition time, and improves the data reliability.

Description

Technical Field

[0001] The present invention belongs to the technical field of satellite formation design, and particularly relates to a satellite formation design method and device for tomographic SAR data acquisition. Background Art

[0002] Spaceborne tomographic SAR uses a satellite as a carrier platform, has the ability to observe the whole world, and can obtain three-dimensional information of a large-scale scene, which is of great significance in urban planning, resource statistics, etc. At present, the processing of tomographic SAR usually requires more than 20 images to achieve a reliable reconstruction result. However, most of the tomographic data comes from repeated satellite passes, which takes a long time, introduces deformation information of ground objects, and different sampling times also introduce different atmospheric phases. Therefore, additional processing steps such as phase error correction are required, and there are errors in the estimated height. In recent years, scholars at home and abroad have carried out research on tomographic processing using small datasets. Reducing the number of images required for tomographic processing reduces the data acquisition time to a certain extent, but the phase error cannot be removed.

[0003] Satellite formation technology can simultaneously acquire images of the same area from different perspectives and directly provide data with uniformly distributed baselines, providing higher-quality and faster input for tomographic processing. The development of formation satellites has greatly improved the efficiency and quality of data acquisition, but there is currently no dedicated satellite formation scheme or design method for tomographic data acquisition. Summary of the Invention

[0004] To solve the above technical problems, the present invention provides a satellite formation design method and device for tomographic SAR data acquisition. The satellite formation designed by the present invention can achieve tomographic data acquisition of the required scene in a single pass, and does not introduce different atmospheric phases in each acquisition, reducing the data acquisition time and improving the data reliability.

[0005] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0006] A satellite formation design method for tomographic SAR data acquisition, comprising the following steps:

[0007] Step 1, determine the minimum number of samples required for tomographic processing according to the design parameters;

[0008] Step 2, determine the optimal number of satellites and the transceiver mode setting according to the relationship between the number of satellites and the number of equivalent phase centers that can be generated;

[0009] Step 3, determine the arrangement of each satellite in the formation according to the tomographic performance;

[0010] Step 4: Calculate the maximum along-track baseline and the maximum cross-track baseline of the outermost satellite according to the arrangement of each satellite in the formation.

[0011] Step 5: Calculate the formation parameters of the outermost satellite.

[0012] Step 6: Determine the multi-satellite formation parameters according to the phase center approximation principle and the formation geometry to obtain equally spaced equivalent phase centers.

[0013] Step 7: Calculate the six orbital elements of all satellites in the formation according to the multi-satellite formation parameters.

[0014] On the other hand, the present invention provides a satellite formation design device for tomographic SAR data acquisition, including:

[0015] A design parameter analysis unit, configured to determine the minimum sampling number required for tomographic processing according to the required parameters in the design parameters; determine the optimal number of satellites and the transceiver mode setting according to the relationship between the number of satellites and the number of equivalent phase centers that can be generated, that is, the formation design parameters in the design parameters; determine the arrangement of each satellite in the formation according to the selected basic formation.

[0016] A formation parameter design unit, configured to calculate the maximum along-track baseline and the maximum cross-track baseline of the outermost satellite according to the arrangement of each satellite in the formation; calculate the formation parameters of the outermost satellite; determine the multi-satellite formation parameters according to the phase center approximation principle and the formation geometry to obtain equally spaced equivalent phase centers; calculate the six orbital elements of all satellites in the formation according to the multi-satellite formation parameters.

[0017] In a third aspect, the present invention provides an electronic device, including: one or more processors; a memory for storing one or more programs; wherein, when the one or more programs are executed by the one or more processors, the one or more processors implement the foregoing satellite formation design method for tomographic SAR data acquisition.

[0018] In a fourth aspect, the present invention provides a computer-readable storage medium, on which executable instructions are stored, and when the instructions are executed by a processor, the processor can implement the foregoing satellite formation design method for tomographic SAR data acquisition.

[0019] The beneficial effects of the present invention are as follows:

[0020] The satellite formation design method for tomographic SAR data acquisition provided by the present invention, according to the design parameters, gradually determines the minimum sampling quantity required for tomographic processing, the number of satellites and the transceiver mode settings, the satellite arrangement, calculates the multi-satellite formation parameters, and determines the six orbital elements of all satellites in the formation; the satellite formation scheme determined by the present invention can generate data with uniformly distributed baselines only by a single pass, providing higher-quality and faster data support for tomographic processing. Description of the Drawings

[0021] Figure 1 It is a flowchart of a satellite formation design method for tomographic SAR data acquisition according to the present invention;

[0022] Figure 2 It is a schematic diagram of the relative motion of a two-satellite formation represented by the C-W equation;

[0023] Figure 3 It is a schematic diagram of a formation scheme with a helix as the basic formation;

[0024] Figure 4 It is a schematic diagram of a formation scheme with a wheel as the basic formation;

[0025] Figure 5 It is a schematic diagram of a formation scheme with a pendulum as the basic formation;

[0026] Figure 6 It is the simulation result of the formation scheme with a helix as the basic formation within one orbital period. Among them, (a) is the relative position and relative motion trajectory of the satellites, (b) is the relative position and relative motion trajectory of the equivalent phase centers, (c) is the vertical baseline situation of the formation within one orbital period, (d) is the tomographic resolution situation within one orbital period, and (e) is the unambiguous height situation within one orbital period. Detailed Embodiment

[0027] The present invention will be further described below with reference to the drawings and embodiments.

[0028] As Figure 1 shown, it is a flowchart of a satellite formation design method for tomographic SAR data acquisition according to the present invention, which specifically includes:

[0029] Step 1, according to the design parameters, determine the minimum sampling quantity required for tomographic processing .

[0030] The design parameters include requirement parameters, formation design parameters, and other parameters;

[0031] Among them, the requirement parameters refer to the tomographic performance expected by the designer, which are respectively the number of scattering centers expected to be resolved by tomography ; Latitude range of the observation area , is the southernmost latitude, is the northernmost latitude; The minimum Rayleigh resolution requirement within the observation area .

[0032] The formation design parameters refer to the formation satellite conditions required or satisfied to achieve the target tomography performance, which are respectively the total number of satellites in the formation ; The number of satellites with both receiving and transmitting capabilities in the formation, i.e., the number of T&R satellites ; The basic formation configuration selected by the designer , including three basic formations, namely Cartwheel, Pendulum, and Helix. Among them, the number of satellites with only receiving capabilities, i.e., the number of R satellites, is .

[0033] There are three types of the basic formation configurations, including:

[0034] Cartwheel, Pendulum, and Helix. For the basic formation composed of two satellites, it can be described by the classical relative motion model - C-W equation representing the close-proximity formation flight of satellites. This equation is established in the LVLH coordinate system of the primary satellite, The axis represents the Earth's radial direction away from the center of the Earth, The axis is the motion direction of the primary satellite, The axis is the direction perpendicular to the orbital plane; When there is no external force influence and certain conditions are met, the orbital mechanical energy of the formation satellites is conserved, and the C-W equation can be described as:

[0035] ;

[0036] Among them, , is the orbital period, and the parameter is the semi-minor axis of the projection ellipse of the relative motion trajectory in the plane, is the initial phase angle in the plane, is the amplitude of the simple harmonic motion of the relative motion trajectory along the direction, is the initial phase of the motion in the direction, is the distance between the relative motion center of the secondary satellite and the primary satellite along the direction; The relative motion relationship between the primary and secondary satellites can be determined using the formation parameter

[0037] Furthermore, let other satellites in the formation form the basic formation with the reference satellite in pairs to form an equivalent phase center distribution with uniform baselines. Other alternative solutions can be adopted, such as combining different basic formations, etc.

[0038] Other parameters are the maximum along-track baseline allowed for the formation , the radar down-looking angle (positive on the left side and negative on the right side) and the six orbital elements of the reference satellite .

[0039] In the above solution, the six orbital elements include: semi-major axis , eccentricity , orbital inclination , argument of perigee , right ascension of the ascending node and mean anomaly . The true anomaly can be used to replace the mean anomaly, and the subscript represents the reference satellite.

[0040] According to the design parameters, determine the minimum sampling number required for the tomography processing , including: for an area without obvious deformation and in the case of uniform baselines, the number of resolvable scattering centers, that is, the number of scattering centers expected to complete the de-aliasing of the tomography and the minimum sampling number The relationship between them is:

[0041] ;

[0042] That is to say, at least 4 samplings are required to separate 2 aliased scattering centers, and at least 6 samplings are required to separate 3 aliased scattering centers.

[0043] Step 2, according to the relationship between the total number of satellites and the number of equivalent phase centers that can be generated , determine the optimal number of satellites and the transceiver mode settings.

[0044] Assume that when using T&R satellites with the same frequency, at most equivalent phase centers can be generated, and at least non-overlapping equivalent phase centers can be generated; when the formation satellites include both T&R satellites and R satellites at the same time, the number of equivalent phase centers that can be generated in the formation is:

[0045] ;

[0046] Among them, For the permutation and combination operation, let q = 2, p = , this parameter can be denoted as , which represents the number of ways to select items from a set of different items without considering the selection order, is the total number of satellites in the formation, is the number of T&R satellites in the formation, is the number of R satellites in the formation, satisfying . The tomographic processing needs to satisfy:

[0047] ;

[0048] When the vertical baselines formed by the equivalent phase centers are equally spaced, "=" holds.

[0049] The relationship between the number of satellites in the formation and the number of equivalent phase centers that can be generated is shown in Table 1.

[0050] Table 1

[0051]

[0052] The overlapping equivalent phase centers do not bring perspective differences to the data and are considered to provide the same tomographic information. To reduce data waste and save satellite costs, the formation scheme that can continuously generate non-overlapping equivalent phase centers is the most cost-effective. This can be achieved using the data groups corresponding to the underlines in Table 1. Thus, the formation containing two T&R satellites is taken as the object of subsequent design.

[0053] The optimal satellite number and transceiver mode settings described above include:

[0054] The formation contains two T&R satellites, and the rest are R satellites.

[0055] In the above scheme, the tomographic performance includes the Rayleigh resolution and the unambiguous height ; The Rayleigh resolution is expressed as:

[0056] ;

[0057] Among them, is the signal wavelength, is the slant range of the reference image, is the synthetic aperture length in the tomographic direction, that is, the total span of the vertical baseline; The unambiguous height is expressed as:

[0058] ;

[0059] Among them, is the vertical baseline interval.

[0060] Step 3: Determine the arrangement of each satellite in the formation according to the tomography performance.

[0061] When designing the distribution of satellites, the following points need to be considered:

[0062] While ensuring the tomography resolution, it is required that the equivalent phase centers are evenly distributed to minimize the sidelobes of the tomography signal;

[0063] Due to the existence of T&R satellites and R satellites with different volumes and masses, it is more difficult to maintain the formation flight due to different drags. Therefore, a symmetric formation structure is adopted to reduce the drag;

[0064] Signal synchronization is a prerequisite for the normal operation of the formation satellites. Therefore, the satellites are separated along the main trajectory so that the satellites do not block each other, creating conditions for synchronization.

[0065] Therefore, in order to obtain a formation with a large and evenly distributed total baseline length, two T&R satellites in the formation need to be placed on the outer side of the formation. The formation is symmetric about the center of the main trajectory, and there is a certain distance between the satellites along the main trajectory. The main trajectory is the trajectory formed by the main star in a two-satellite formation. When in a multi-satellite formation, it is the trajectory formed by the reference satellite.

[0066] Step 4: Calculate the maximum along-track baseline and the maximum vertical baseline of the outermost satellite according to the formation arrangement.

[0067] Different from a two-satellite formation that relies on the main and auxiliary satellites to form a baseline, a multi-satellite formation relies on the two outermost satellites to form the maximum baseline. For the design requirements where the along-track line does not exceed the maximum along-track baseline , the latitude range of the observation area and the inner tomography resolution reaches the minimum Rayleigh resolution requirement , the maximum along-track baseline formed by one of the outermost T&R satellites and the reference satellite along the main trajectory is:

[0068] ;

[0069] The maximum vertical baseline is:

[0070] ;

[0071] Among them, is the maximum vertical baseline formed by the formation, is the maximum vertical baseline formed by one of the outermost T&R satellites and the reference satellite. The subscript represents a T&R satellite, represents the vertical baseline. In particular, without a subscript Indicates the baseline for formation, with a subscript Indicates the baseline formed by the outermost T&R satellite and the reference satellite, and the latter is half of the former.

[0072] Is the center of the observation area The resolution to be achieved;

[0073] ;

[0074] Among them, Is the latitude range of the sub-satellite point of the reference satellite.

[0075] Step 5, calculate the formation parameters of the outermost satellite.

[0076] The C-W equation described above can represent the relative motion of a two-satellite formation. Obviously, the relative motion can be decomposed into two independent motions: one is in the orbital plane, and the other is perpendicular to the orbital plane. The former is an ellipse with an eccentricity of 2, and the latter is a simple harmonic motion. The relative motion relationship is as Figure 2 Shown.

[0077] The relative motion relationship between the primary and secondary satellites can be determined using the formation parameters For the three basic formations, the formation parameters need to meet corresponding conditions.

[0078] When the wheel formation is selected as the basic formation, the formation parameters of the two-satellite wheel can be set as:

[0079] ;

[0080] When the pendulum formation is selected as the basic formation, the formation parameters of the two-satellite pendulum can be set as:

[0081] ;

[0082] When the spiral formation is selected as the basic formation, the formation parameters of the two-satellite spiral can be set as:

[0083] ;

[0084] Among them, Is an auxiliary parameter, And Respectively represent the maximum vertical baseline and the maximum along-track baseline formed by the primary and secondary satellites, Is the initial mean anomaly of the primary satellite, Is the initial sub-satellite point latitude of the primary satellite, Is the sub-satellite point latitude range of the primary satellite, Is the center of the relative motion trajectory of the secondary satellite in the spiral formation along the primary satellite The distance from the axis. It should be noted that is sufficient, but along the track baseline, it can also be set by Extra growth is possible, but shortening is not allowed. When using multi-satellite formation, the main satellite in the above formula becomes the reference satellite, and the relative motion relationship formed by all satellites in the formation with the main satellite can be represented by different formation parameters to calculate.

[0085] According to the basic formation selected by the designer, the formation parameters of the outermost satellite and the reference satellite in the formation are calculated using the corresponding formula above, which is .

[0086] Step 6: Determine the multi-satellite formation parameters according to the phase center approximation principle and formation geometry to obtain equally spaced equivalent phase centers, that is, uniformly distributed baselines. It includes:

[0087] According to the phase center approximation principle, the transmitter and receiver not on the same platform are equivalent to a transceiver co-located platform at the center position, and then using formation geometry, the multi-satellite formation parameters are determined to obtain equally spaced equivalent phase centers, that is, uniformly distributed baselines.

[0088] Multi-satellite formation requires calculating the formation parameters between each satellite in the formation and the reference satellite , , that is, the formation parameters of the entire formation :

[0089] ;

[0090] Among them, each row represents the formation parameters of one satellite, and each column represents a certain formation parameter of all satellites in the formation.

[0091] Select the T&R satellite that has calculated the basic formation parameters as the reference, that is, the first satellite. Since an evenly distributed baseline is to be obtained, the projection of the position of the equivalent phase center on the cross-track plane should be on a straight line, and the same applies to the satellites. The remaining satellites are arranged in order of distance from the reference satellite as the , th satellite, and its formation parameters are .

[0092] Define vector to represent the satellite distribution in the cross-track plane, and each element is:

[0093] ;

[0094] Among them, symbol represents the The lateral position relationship of a satellite relative to the main trajectory. A positive value indicates that the satellite is on the same side of the main trajectory as the reference satellite, a negative value indicates the opposite side, and a value of 0 indicates that the satellite is located on the main trajectory. Indicates the relative distance between the satellite and the main trajectory. The reference satellite is defined as:

[0095] ;

[0096] When different basic formations are selected, the determination methods for subsequent multi-satellite formation parameters are different. When a relatively complex helix is selected as the basic formation, the multi-satellite formation parameters are calculated as follows:

[0097] In the C-W equation, the y-axis is the direction of the main trajectory of the satellite. The effective baseline formed by the satellite and the main trajectory is in the cross-track plane and is related to the formation parameters A and B. A and B need to change in the same proportion to ensure that the baseline is evenly distributed, that is, the equivalent phase centers are equally spaced. Define the ratio:

[0098] ;

[0099] ;

[0100] where , represents the ratio of each formation parameter of the th satellite in the formation to the corresponding parameter of the reference satellite, satisfying . Define the ratio:

[0101] ;

[0102] represents the ratio of the formation parameter of the th satellite in the formation to the formation parameter of the reference satellite.

[0103] can form a new vector , specifically:

[0104] ;

[0105] The vector represents the ratio of the formation parameters of all satellites in the formation to the formation parameter of the reference satellite. One of the elements is always 1, representing that this satellite is the reference satellite. Similarly, for the formation parameters and , the ratios and can be defined.

[0106] Formation parameters representing angles and can be calculated as follows:

[0107] ;

[0108] ;

[0109] Similarly, a new vector and are formed, specifically:

[0110] ;

[0111] ;

[0112] Thus, the complete formation parameters with a helix as the basic formation are:

[0113] ;

[0114] wherein, is the Hadamard product, and the subscript represents the multi-satellite formation parameters with a helix as the basic formation. The schematic diagram of the tomography formation scheme designed with a helix as the basic formation is shown in Figure 3 .

[0115] When a wheel is selected as the basic formation, the parameters of the multi-satellite formation need to be determined according to the formation parameters of the wheel, where and are both 0. At this time, the satellite moves along the x-axis in the cross-track plane. Define the formation parameters of all satellites to form a vector, which is:

[0116] ;

[0117] The formation parameter can still be determined by the following formula:

[0118] ;

[0119] And the vectors , and formed by other parameters are all zero vectors. The entire formation parameters with a wheel as the basic formation are:

[0120] ;

[0121] The subscript represents the multi-satellite formation parameters with a wheel as the basic formation. The schematic diagram of the tomography formation scheme designed with a pendulum as the basic formation is shown in Figure 4 .

[0122] When the pendulum is used as the basic formation, the parameters of the multi-satellite formation need to be determined according to the formation parameters of the pendulum, where and are both 0. Define the formation parameters of all satellites to form a vector, which is:

[0123] ;

[0124] Since the satellites are moving along the z-axis in the intersection plane at this time, it is necessary to separate each satellite along the main trajectory and calculate as:

[0125] ;

[0126] The column vector composed of is The formation parameter

[0127] ;

[0128] And the vectors and composed of other parameters are both zero vectors. The entire formation parameter with the pendulum as the basic formation is:

[0129] ;

[0130] The subscript represents the multi-satellite formation parameter with the pendulum as the basic formation. The schematic diagram of the tomography formation scheme designed with the pendulum as the basic formation is shown in Figure 5 .

[0131] Step 7: Calculate the six orbital elements of all satellites in the formation according to the multi-satellite formation parameters.

[0132] The satellite orbit can be described by orbital elements, which are the semi-major axis , eccentricity , orbital inclination , argument of perigee , right ascension of the ascending node and mean anomaly (true anomaly ). The relative motion can be described by the difference in orbital elements between the master and slave satellites and calculated by the following formula:

[0133] ;

[0134] Thus, the difference in orbital elements can be calculated according to the formation configuration parameter :

[0135] ;

[0136] Adding the calculated orbital element differences to the six orbital elements of the reference satellite input by the designer can obtain the six orbital elements of all satellites in the formation.

[0137] Embodiment

[0138] Selecting a helix as the basic formation and using five satellites for the formation, with the requirement that the tomography Rayleigh resolution does not exceed 20 m within the latitude range of S40° to N60°. The simulation results are as Figure 6 shown, where (a) is the relative position and relative motion trajectory of the satellites, (b) is the relative position and relative motion trajectory of the equivalent phase centers, (c) is the vertical baseline situation of the formation within one orbital period, (d) is the tomography resolution situation within one orbital period, and (e) is the unambiguous height situation within one orbital period. It can be seen that the formation designed by the design method of the present invention meets the resolution requirements.

[0139] On the other hand, the present invention provides a satellite formation design device for tomographic SAR data acquisition. Each unit included therein can implement each step of the foregoing method. Specifically, it includes:

[0140] A design parameter analysis unit, configured to determine the minimum sampling quantity required for tomographic processing according to the required parameters in the design parameters; determine the optimal number of satellites and transceiver mode settings according to the relationship between the number of satellites and the number of equivalent phase centers that can be generated, that is, the formation design parameters in the design parameters; determine the arrangement of each satellite in the formation according to the selected basic formation;

[0141] A formation parameter design unit, configured to calculate the maximum along-track baseline and maximum vertical baseline of the outermost satellite according to the arrangement of each satellite in the formation; calculate the formation parameters of the outermost satellite; determine the multi-satellite formation parameters according to the phase center approximation principle and formation geometry to obtain equally spaced equivalent phase centers; calculate the six orbital elements of all satellites in the formation according to the multi-satellite formation parameters;

[0142] Further, it may also include a formation analysis unit, configured to visualize the designed formation, display the distribution of each satellite in the formation, and display the distribution of the equivalent phase centers formed by the formation; verify whether the designed formation meets the design requirements. Specifically, whether the tomography ability of the formation in the observation area is higher than the lowest Rayleigh resolution requirement, and whether the number of non-overlapping equivalent phase centers generated in the observation area meets the tomography unfolding and masking ability requirement of the formation.

[0143] In a third aspect, the present invention provides an electronic device, comprising: one or more processors; and a memory for storing one or more programs; wherein, when the one or more programs are executed by the one or more processors, the one or more processors are caused to implement the foregoing satellite formation design method for tomographic SAR data acquisition.

[0144] In a fourth aspect, the present invention provides a computer-readable storage medium having executable instructions stored thereon, which when executed by a processor can cause the processor to implement the foregoing satellite formation design method for tomographic SAR data acquisition.

[0145] The specific embodiments described above further elaborate on the objectives, technical solutions, and beneficial effects of the present invention. It should be understood that the above are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. A satellite formation design method for tomographic SAR data acquisition, characterized in that: The steps include: Step 1: Determine the minimum number of samples required for chromatography treatment based on design parameters; Step 2: According to the relationship between the number of satellites and the number of equivalent phase centers that can be generated, the optimal number of satellites and the setting of the transmission and reception mode are determined, including: two satellites in the formation are satellites with both transmission and reception capabilities, namely, T&R satellites, and the remaining satellites are satellites with only reception capabilities, namely, R satellites; Step 3, according to the tomographic performance, determining the arrangement of each satellite in the formation, including: according to the performance indicators of tomographic SAR processing, Rayleigh resolution and unambiguous height, determining the arrangement of each satellite in the formation as follows: placing the two T&R satellites outside the formation, the formation is symmetrical along the center of the main track, and the satellites are at a preset distance along the main track; the main track is the track formed by the main star in the double-star formation, and is the track formed by the reference satellite in the case of a multi-star formation; Step 4: Calculate the maximum along-track baseline and maximum vertical baseline of the outermost satellite according to the arrangement of the satellites in the formation; Step 5, calculating the formation parameters of the outermost satellite; Step 6: According to the phase center approximation principle and formation geometry, determine the multi-star formation parameters to obtain equivalent phase centers with equal intervals; Step 7: Calculate the six orbital numbers of all satellites in the formation according to the multi-satellite formation parameters.

2. The satellite formation design method for tomographic SAR data acquisition according to claim 1, characterized in that: The step 1 comprises: Determine the design parameters required for a satellite formation for tomographic SAR data acquisition, the design parameters including demand parameters, formation design parameters and other parameters. The demand parameters refer to the tomographic performance expected by the designer, which are the number of scattering centers for tomographic de-masking, the latitude range of the observation area and the minimum Rayleigh resolution requirement in the observation area; the formation design parameters refer to the formation satellite conditions required or satisfied to achieve the target tomographic performance, which are the total number of satellites in the formation, the number of satellites in the formation with simultaneous transceiver capabilities and the basic formation configuration selected by the designer; the other parameters are the maximum along-track baseline allowed by the formation, the radar under-angle view and the six orbital numbers of the reference satellite.

3. The satellite formation design method for tomographic SAR data acquisition according to claim 2, characterized in that: The step 4 comprises: The multi-satellite formation relies on the two outermost T&R satellites to form the maximum along-track baseline and the maximum vertical baseline. The maximum along-track baseline formed by the outermost T&R satellite and the reference satellite on the main track is half of the maximum along-track baseline allowed by the formation input by the designer. The maximum vertical baseline is half of the vertical baseline calculated using the Rayleigh resolution.

4. The satellite formation design method for tomographic SAR data acquisition according to claim 3, characterized in that: The step 5 comprises: According to the basic formation selected by the designer, the formation parameters of the binary satellite relationship formed by any outermost T&R satellite in the basic formation and the reference satellite are calculated, wherein the basic formation is one of a spiral, a wheel and a pendulum.

5. The satellite formation design method for tomographic SAR data acquisition according to claim 4, characterized in that: The step 6 comprises: According to the phase center approximation principle, the transmitter and receiver that are not on the same platform are equivalent to the same transmitting and receiving platform at the center position, and then the formation geometry is used to determine the multi-satellite formation parameters to obtain equivalent phase centers with equal intervals, that is, a uniformly distributed baseline.

6. The satellite formation design method for tomographic SAR data acquisition according to claim 5, characterized in that: The step 7 comprises: According to the multi-satellite formation parameters, the difference in the number of orbital elements between each satellite in the formation and the reference satellite is calculated, and then the difference is added to the six orbital elements of the reference satellite to calculate the six orbital elements of all satellites in the formation.

7. A satellite formation design device for tomographic SAR data acquisition, characterized in that: include: A design parameter analysis unit, used to determine the minimum number of samples required for chromatography processing according to the demand parameters in the design parameters; According to the relationship between the number of satellites and the number of equivalent phase centers that can be generated, the optimal number of satellites and the setting of the receiving and transmitting mode, i.e., the formation design parameters in the design parameters, are determined, including: two satellites in the formation are satellites with both receiving and transmitting capabilities, i.e., T&R satellites, and the remaining satellites are satellites with only receiving capabilities, i.e., R satellites; according to the tomographic performance, the arrangement of each satellite in the formation is determined, including: according to the performance indicators of tomographic SAR processing, Rayleigh resolution and unambiguous height, the arrangement of each satellite in the formation is determined as follows: the two T&R satellites are placed outside the formation, the formation is symmetrical along the center of the main trajectory, and the satellites have a preset distance along the main trajectory; the main trajectory is the trajectory formed by the main star in a dual-star formation, and is the trajectory formed by the reference satellite in a multi-star formation; The formation parameter design unit is used to calculate the maximum along-track baseline and maximum vertical baseline of the outermost satellite according to the arrangement of the satellites in the formation; and calculate its formation parameters; determine the multi-satellite formation parameters according to the phase center approximation principle and formation geometry to obtain equivalent phase centers with equal intervals; calculate the six orbital numbers of all satellites in the formation according to the multi-satellite formation parameters.

8. An electronic device, characterized in that: include: one or more processors; A memory for storing one or more programs; Wherein, when one or more programs are executed by the one or more processors, the one or more processors implement the satellite formation design method for tomographic SAR data acquisition as described in any one of claims 1-6.

9. A computer-readable storage medium, characterized in that: Executable instructions are stored thereon, and when the instructions are executed by the processor, the processor can implement the satellite formation design method for tomographic SAR data acquisition as described in any one of claims 1-6.

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