Method and device for determining high-low orbit satellite visible time window

Abstract

The specification relates to the technical field of satellite detection, and particularly discloses a high-low orbit satellite visible time window determination method and device, wherein the method comprises: acquiring high-orbit satellite parameters, low-orbit satellite parameters and task start-stop time; the high-orbit satellite parameters comprise high-orbit satellite orbit parameters and high-orbit satellite track point data; the low-orbit satellite parameters comprise low-orbit satellite orbit parameters and low-orbit satellite track point data; establishing an R-tree index of the low-orbit satellite track point data; constructing a search area according to the high-orbit satellite track point data, the high-orbit satellite orbit parameters and the low-orbit satellite orbit parameters; searching in the R-tree index by using the search area to obtain an earth unobstructed arc segment; performing visibility judgment on each track point in the multiple low-orbit satellite track points in the earth unobstructed arc segment to determine a high-low orbit satellite visible time window. The above scheme can reduce the calculation amount of calculating the visible time window while ensuring the calculation accuracy.

Description

TECHNICAL FIELD

[0001] The present specification relates to the technical field of satellite detection, and in particular to a high-low orbit satellite visible time window determination method and device. BACKGROUND

[0002] High orbit satellites are located in an orbit 35800km above the equator, keep relatively stationary with the earth, and cover a fixed area. Due to the high orbit height, the earth field of view is large, and therefore the coverage range is large. In theory, three satellites can cover the global area except the two poles. Medium-low orbit satellites are satellites with a flight height less than 1000km (low orbit) and between 1000-20000km (medium orbit), and are in a motion state relative to the earth. High orbit imaging satellites can continuously track and monitor targets for a long time, and obtain continuous positioning information and speed and heading information of the targets, but due to the high orbit height, the imaging resolution is low and the targets cannot be identified and confirmed. Low orbit high resolution imaging satellites can accurately identify and confirm targets and accurately position them, but are limited by the imaging width and it is difficult to discover targets autonomously, and need to be guided by other information to identify and confirm the targets. Therefore, a single satellite detection method cannot meet the requirements of situation awareness and target indication tasks in the current complex environment, and high and low orbit satellites need to be cooperatively guided, reasonably divided, and orderly coordinated to comprehensively achieve search and discovery, identification and confirmation, and tracking and monitoring of targets, and other combat task requirements. At the same time, low orbit satellites can significantly improve the data transmission time and efficiency through high orbit satellites.

[0003] The visible time window of the high orbit satellite and the low orbit satellite refers to the communication duration of the low orbit satellite in the field of view of the high orbit satellite, and the calculation of the visible time window of the high and low orbit satellites is a prerequisite for the cooperative guidance and data transmission of the high and low orbit satellites. In satellite mission planning, data transmission resource scheduling, and space-based target monitoring, and various tasks, the visible time window calculation function needs to be supported. Efficient and accurate calculation of the high and low orbit visible time window helps to significantly improve the efficiency of satellite mission planning, and therefore has important research value and engineering significance. How to reduce the calculation amount while ensuring the accuracy is also one of the important problems to be solved in the calculation of the visible time window.

[0004] At present, no effective solution has been proposed for the above problems. SUMMARY

[0005] The embodiments of the present specification provide a high-low orbit satellite visible time window determination method and device to reduce the calculation amount of the visible time window while ensuring the calculation accuracy.

[0006] The embodiments of the present specification provide a high-low orbit satellite visible time window determination method, comprising:

[0007] obtain high orbit satellite parameters, low orbit satellite parameters and mission start and end time; the high orbit satellite parameters include high orbit satellite orbit parameters and high orbit satellite track point data; the low orbit satellite parameters include low orbit satellite orbit parameters and low orbit satellite track point data;

[0008] establish an R-tree index of the low orbit satellite track point data; construct a search region according to the high orbit satellite track point data, the high orbit satellite orbit parameters and the low orbit satellite orbit parameters;

[0009] search in the R-tree index using the search region to obtain an earth unblocked arc segment; perform visibility judgment on low orbit satellite track points in the earth unblocked arc segment to determine high and low orbit satellite visibility time windows.

[0010] In one embodiment, establishing the R-tree index of the low orbit satellite track point data comprises:

[0011] initialize the R-tree;

[0012] add a track point in the low orbit satellite track point data to the R-tree, determine a leaf node with the smallest volume increment after adding the track point, judge whether the number of track points in the leaf node is less than a preset number, if yes, add the track point to the leaf node, otherwise, split the track point and the track points in the leaf node into two leaf nodes according to the principle of the smallest volume increment, adjust parent nodes level by level according to the split condition, and adjust the structure of the R-tree; and add multiple track points in the low orbit satellite track point data.

[0013] In one embodiment, constructing a search region according to the high orbit satellite track point data, the high orbit satellite orbit parameters and the low orbit satellite orbit parameters comprises:

[0014] determine a first intersection position parameter between a line connecting the high orbit satellite and the center of the earth and a low orbit satellite orbit based on the high orbit satellite track point data and the low orbit satellite orbit parameters;

[0015] calculate a second intersection position parameter between a tangent line of the high orbit satellite and the earth and the low orbit satellite orbit according to the high orbit satellite orbit parameters and the low orbit satellite orbit parameters;

[0016] construct a search region according to the first intersection position parameter and the second intersection position parameter.

[0017] In one embodiment, searching in the R-tree index using the search region to obtain an earth unblocked arc segment comprises:

[0018] Starting from a root node of the R-tree index, it is determined whether there is an overlap between the root node and the search area, if yes, the search is continued in the child nodes corresponding to the root node, if a leaf node is searched, it is determined whether the searched leaf node is within the search area, if yes, the leaf node is added to the search result; until the minimum bounding rectangle intersecting the search area is accessed;

[0019] According to the search result, an earth unblocked arc segment is generated.

[0020] In an embodiment, a visibility judgment is performed on a low-orbit satellite track point in the earth unblocked arc segment, and a high-low-orbit satellite visible time window is determined, including:

[0021] The plurality of low-orbit satellite track points contained in the earth unblocked arc segment are sorted in a corresponding time sequence, and a first low-orbit satellite track point closest to the high-orbit satellite is determined;

[0022] It is determined whether the first low-orbit satellite track point satisfies the visibility condition;

[0023] In a case where it is determined that the first low-orbit satellite track point satisfies the visibility condition, a binary search method is used to search from the time corresponding to the first low-orbit satellite track point to the front in the earth unblocked arc segment to determine the visible start and end time of the high-low-orbit satellite visible time window.

[0024] In an embodiment, after determining whether the first low-orbit satellite track point satisfies the visibility condition, further including:

[0025] In a case where it is determined that the first low-orbit satellite track point does not satisfy the visibility condition, it is determined whether there is a visible time from the time corresponding to the first low-orbit satellite track point to the front in the earth unblocked arc segment;

[0026] In a case where there is no visible time, it is determined that there is no visible time window in the earth unblocked arc segment.

[0027] In an embodiment, the high-orbit satellite parameters include high-orbit satellite orbit parameters and high-orbit satellite track point data corresponding to each high-orbit satellite in the plurality of high-orbit satellites; and the low-orbit satellite parameters include low-orbit satellite orbit parameters and low-orbit satellite track point data corresponding to each low-orbit satellite in the plurality of low-orbit satellites;

[0028] Correspondingly, before constructing the search area according to the high-orbit satellite track point data, the high-orbit satellite orbit parameters and the low-orbit satellite orbit parameters, further including:

[0029] For each high-orbit satellite in the plurality of high-orbit satellites, a subtask corresponding to the high-orbit satellite is constructed, to obtain a plurality of subtasks; the plurality of subtasks are distributed to different node servers for parallel execution; the subtask corresponding to each high-orbit satellite includes a high-low-orbit satellite visible time window determination task between the high-orbit satellite and each low-orbit satellite.

[0030] The embodiments of the present specification also provide a high-low-orbit satellite visible time window determination device, comprising:

[0031] An acquisition module is configured to acquire high-orbit satellite parameters, low-orbit satellite parameters, and task start and end times; the high-orbit satellite parameters include high-orbit satellite orbit parameters and high-orbit satellite track point data; the low-orbit satellite parameters include low-orbit satellite orbit parameters and low-orbit satellite track point data;

[0032] An index module is configured to establish an R-tree index of the low-orbit satellite track point data; and to construct a search area according to the high-orbit satellite track point data, the high-orbit satellite orbit parameters, and the low-orbit satellite orbit parameters.

[0033] A determination module is configured to search in the R-tree index using the search area to obtain an earth unobstructed arc segment; and to perform visibility judgment on low-orbit satellite track points in the earth unobstructed arc segment to determine a high-low-orbit satellite visible time window.

[0034] The embodiments of the present specification also provide a computer device, comprising a processor and a memory for storing processor-executable instructions, wherein the processor executes the instructions to implement the steps of the high-low-orbit satellite visible time window determination method described in any of the above embodiments.

[0035] The embodiments of the present specification also provide a computer-readable storage medium having computer instructions stored thereon, wherein the instructions are executed to implement the steps of the high-low-orbit satellite visible time window determination method described in any of the above embodiments.

[0036] This specification provides a method for determining the visible time window of high-Earth orbit (HEO) and low-Earth orbit (LEO) satellites. The method involves acquiring HEO satellite parameters, LEO satellite parameters, and mission start and end times. HEO satellite parameters include HEO orbital parameters and HEO trajectory point data. LEO satellite parameters include LEO orbital parameters and LEO trajectory point data. An R-tree index of the LEO satellite trajectory point data is established. Based on the HEO trajectory point data, HEO orbital parameters, and LEO satellite orbital parameters, a search region is constructed. This search region is then used to search the R-tree index to obtain the Earth-free arc segment. Visibility is assessed for LEO satellite trajectory points within the Earth-free arc segment to determine the visible time window for HEO and LEO satellites. This scheme, by constructing an R-tree index for LEO satellite trajectory point data, only considers satellite trajectory points within the Earth-free arc segment, significantly reducing computational load. Simulation results demonstrate that this algorithm achieves the same visibility accuracy as STK (Survey-to-Knowledge) satellites, but its efficiency is 10,000 times faster than the 1ms tracking propagation method, ensuring the algorithm's reliability and efficiency. This method can provide theoretical guidance for satellite mission planning. Furthermore, in practical applications, parallel computing can be used to achieve fast computation. Attached Figure Description

[0037] The accompanying drawings, which are included to provide a further understanding of this specification and form part of it, do not constitute a limitation thereof. In the drawings:

[0038] Figure 1 A schematic diagram showing the relationship between high and low orbit satellites and Earth's shadow is shown;

[0039] Figure 2 A schematic diagram showing the antenna azimuth and elevation angles is provided.

[0040] Figure 3 A flowchart of a method for determining the visible time window of high and low orbit satellites according to an embodiment of this specification is shown;

[0041] Figure 4 A schematic diagram of the construction of an R-tree search box in one embodiment of this specification is shown;

[0042] Figure 5 A schematic diagram of the R-tree construction process in one embodiment of this specification is shown;

[0043] Figure 6 A schematic diagram of a device for determining the visible time window of high and low orbit satellites according to an embodiment of this specification is shown;

[0044] Figure 7 A schematic diagram of a computer device according to one embodiment of this specification is shown. Detailed Implementation

[0045] The principles and spirits of the present specification will be described below with reference to a number of exemplary embodiments. It should be understood that these embodiments are given only for the purpose of better illustrating and thus enabling a better understanding of the present specification, and in no way limit the scope of the present specification. On the contrary, these embodiments are provided in order to make the disclosure of the present specification more thorough and complete, and to enable the scope of the present disclosure to be fully conveyed to those skilled in the art.

[0046] Those skilled in the art understand that the embodiments of the present specification can be implemented as a system, a device, a method or a computer program product. Therefore, the present disclosure can be specifically implemented in the following forms: complete hardware, complete software (including firmware, resident software, microcode, etc.), or a combination of hardware and software.

[0047] The embodiment of the present specification provides a high-low orbit satellite visible time window determination method. Before high orbit satellite and low orbit satellite establish data transmission link, both sides of the antenna should point to each other, the relative position between satellites, the attitude of low orbit satellite and the installation mode of antenna affect the visibility of both sides. Based on the position of high orbit satellite and low orbit satellite, the earth blocking and the pointing azimuth and elevation angle of the relay antenna of low orbit satellite are calculated. When both are within the constraint range and there is no earth blocking between high orbit satellite and low orbit satellite, it is considered that low orbit satellite and high orbit satellite are visible.

[0048] Please refer to Figure 1 , which shows the high-low orbit satellite and earth blocking relationship schematic diagram. As Figure 1 shown, when the low orbit satellite is in the AB segment, the low orbit satellite and the high orbit satellite exist earth blocking.

[0049] Then, the low orbit satellite antenna pointing angle can be calculated. Since the antenna motion is based on the antenna coordinate system, all vectors need to be converted to the antenna coordinate system for operation. The conversion matrix from the geocentric inertial coordinate system to the barycentric orbit coordinate system is C OI :

[0050]

[0051] The conversion matrix from the barycentric orbit coordinate system to the satellite body coordinate system is C BO :

[0052]

[0053] In the formula, is the roll angle; θ is the pitch angle; ψ is the yaw angle, ω is the perigee amplitude, f is the true anomaly, i is the satellite orbit inclination, and Ω is the right ascension of the ascending node.

[0054] The conversion matrix from the star coordinate system to the antenna coordinate system is CAB The pointing vector of the LEO satellite relay antenna in the antenna coordinate system is calculated as follows:

[0055]

[0056] where [x TU y TU z TU ] is the pointing vector of the LEO satellite relay antenna to the GEO satellite; [x T y T z T ] and [x U y U z U ] are the positions of the GEO satellite and the LEO satellite in the Earth-Centered Inertial (ECI) coordinate system, respectively.

[0057] Please refer to Figure 2 , which shows a schematic diagram of the azimuth and elevation angles of the antenna. As shown in Figure 2 , it is assumed that the antenna rotates around the X-axis by an azimuth angle a and rotates around the Y-axis by an elevation angle b to point to the GEO satellite.

[0058] The azimuth and elevation angles of the antenna are calculated as follows:

[0059]

[0060] Based on the positions of the LEO satellite and the GEO satellite and the attitude of the LEO satellite, if the calculated pointing angles a and b of the relay antenna are within the constraint range and there is no Earth occlusion, it is considered that the LEO satellite and the GEO satellite are visible.

[0061] Figure 2 A flowchart of a method for determining a visible time window of a LEO satellite and a GEO satellite according to an embodiment of the present specification is shown. Although the present specification provides the method operation steps or the device structure as shown in the following embodiments or the accompanying drawings, more or fewer operation steps or module units can be included in the method or device based on conventional or non-creative labor. The execution order of the steps or the module structure of the device is not limited to the execution order or the module structure shown in the embodiment description and the accompanying drawings of the present specification in the absence of necessary causal relationships between the steps or the structures in logic. When the method or the module structure is applied to an actual device or a terminal product, the method or the module structure can be sequentially executed or executed in parallel (for example, in a parallel processor or a multi-thread processing environment, or even in a distributed processing environment) according to the method or the module structure shown in the embodiment or the accompanying drawings.

[0062] Specifically, as shown in Figure 3 , the method for determining a visible time window of a LEO satellite and a GEO satellite according to an embodiment of the present specification can include the following steps:

[0063] In step S301, high-orbit satellite parameters, low-orbit satellite parameters and task start and end time are obtained. The high-orbit satellite parameters include high-orbit satellite orbit parameters and high-orbit satellite track point data. The low-orbit satellite parameters include low-orbit satellite orbit parameters and low-orbit satellite track point data.

[0064] The method in this embodiment can be applied to a computer device. The computer device can be a server or a server cluster, etc. High-orbit satellite parameters, low-orbit satellite parameters and task start and end time can be obtained.

[0065] The high-orbit satellite parameters can include high-orbit satellite orbit parameters and high-orbit satellite track point data. The high-orbit satellite orbit parameters can include high-orbit satellite orbit radius or high-orbit satellite orbit altitude, etc. The high-orbit satellite track point data can include high-orbit satellite track point data in an earth-centered inertial system and high-orbit satellite track point data in a geodetic coordinate system. In the geodetic coordinate system, the track point of the high-orbit satellite is stationary by default, that is, the high-orbit satellite track point data in the geodetic coordinate system is a position coordinate.

[0066] The low-orbit satellite parameters can include low-orbit satellite orbit parameters and low-orbit satellite track point data. The low-orbit satellite orbit parameters can include low-orbit satellite orbit radius or low-orbit satellite orbit altitude, etc. The low-orbit satellite track point data can be low-orbit satellite track point data in an earth-centered inertial system and low-orbit satellite track point data in a geodetic coordinate system.

[0067] The task start and end time can be used to represent the task time period range to which the visible time window determination method is directed.

[0068] In some embodiments, the server can receive a task request sent by a client, and the task request can include high-orbit satellite identification, low-orbit satellite identification and task start and end time. In response to the task request, the server can obtain high-orbit satellite parameters corresponding to the high-orbit satellite identification and low-orbit satellite parameters corresponding to the low-orbit satellite identification. These parameters can be stored locally on the server or in a database in the server.

[0069] In step S302, an R-tree index of the low-orbit satellite track point data is established, and a search area is constructed according to the high-orbit satellite track point data, the high-orbit satellite orbit parameters and the low-orbit satellite orbit parameters.

[0070] The corresponding R-tree index can be established based on the low-orbit satellite track point data in the geodetic coordinate system.

[0071] The approximately area without earth blockage can be determined based on the high-orbit satellite track point data in the geodetic coordinate system, the high-orbit satellite orbit parameters and the low-orbit satellite orbit parameters, to obtain the search area. Please refer to Figure 4FIG. 3 shows a schematic diagram of an R-tree search box construction. In one embodiment, as shown in FIG. 3, a region containing the AGB surface corresponding to the low earth orbit satellite track point can be determined as a search region. Figure 4

[0072] Step S303, search in the R-tree index using the search region to obtain an earth unblocked arc segment; perform visibility judgment on the low earth orbit satellite track point in the earth unblocked arc segment to determine a high-low earth orbit satellite visible time window.

[0073] After the search region is established, the search region can be used to search in the R-tree index of the low earth orbit satellite track point data to obtain a plurality of unblocked low earth orbit satellite track points, and generate an earth unblocked arc segment. Visibility judgment can be performed on the low earth orbit satellite track point in the earth unblocked arc segment to determine a high-low earth orbit satellite visible time window. The visibility judgment can be to calculate a pointing vector of the low earth orbit satellite antenna to the high earth orbit satellite corresponding to each track point, determine whether the angle corresponding to the pointing vector satisfies the constraint range of the antenna azimuth and elevation angle, and if so, determine that it is visible. In performing the visibility judgment, the low earth orbit satellite track point data in the geocentric inertial system and the high earth orbit satellite track point data in the geocentric inertial system can be used to calculate the pointing vector of the low earth orbit satellite antenna to the high earth orbit satellite corresponding to each track point.

[0074] In the above embodiment, by constructing the R-tree index of the low earth orbit satellite track point data, only the satellite track points in the range without earth blocking are considered, which can reduce a large amount of calculation. The simulation results prove that the algorithm is on par with STK in terms of visibility accuracy, and is 10000 times faster than the tracking propagation method with 1ms time step in terms of efficiency, which guarantees the reliability and efficiency of the algorithm and can provide theoretical guidance for satellite mission planning.

[0075] In some embodiments of the present specification, establishing the R-tree index of the low earth orbit satellite track point data can include: initializing the R-tree; adding a track point in the low earth orbit satellite track point data to the R-tree, determining a leaf node with the smallest volume increment after adding the track point; judging whether the number of track points in the leaf node is less than a preset number; if so, adding the track point to the leaf node; otherwise, splitting the track point and the track points in the leaf node into two leaf nodes according to the principle of the smallest volume increment, adjusting the parent nodes level by level according to the splitting situation, and adjusting the structure of the R-tree; and adding a plurality of track points in the low earth orbit satellite track point data until the adding is completed.

[0076] ​R-tree is a highly balanced tree data structure, commonly used for spatial multi-dimensional information indexing, such as geographic coordinates and polygon regions, to access spatial data composed of multi-dimensional objects, and can achieve efficient search of any spatial position. It contains two types of nodes: leaf nodes and non-leaf nodes. Each node is composed of several index items. For leaf nodes, the index item is composed of a spatial data object and a minimum bounding box (MBB) that encloses all spatial data objects of the node. For non-leaf nodes, the index item points to its child node and contains an MBB that encloses the MBBs of all index items on the child node. R-tree needs to set the maximum number of node index items M.

[0077] Referring to Figure 5 , an R-tree construction flowchart is shown. Specifically, as Figure 5 indicated, when a new track point is inserted into the R-tree, all leaf nodes of the R-tree need to be traversed to find the leaf node with the smallest MBB volume increment after adding the new track point coordinate. If the number of original track points in the leaf node is less than M, the new track point is directly inserted. If it is equal to M, the leaf node needs to be split into two new nodes, including the original track points in the leaf node and the newly inserted track point. Depending on the split, the parent nodes are adjusted in turn. If the root node capacity is greater than M, the existing root node needs to be split into two nodes, and a new root node is generated, the depth of the R-tree is increased by one, and the structure of the entire R-tree is adjusted. When splitting the node, the MBB volume increment minimization principle also needs to be followed, that is: the newly inserted track point and the original track points in the leaf node are combined as the endpoints of the body diagonal to form an MBB, and the two track points in the MBB with the largest volume are selected and placed in the two new leaf nodes after splitting, at this time the minimum bounding box of the two new leaf nodes is a special MBB with a volume of 0. The remaining track points are sequentially combined with the MBBs in the two nodes to form new MBBs, and compared with the original MBB, the track point with the smallest volume increment is selected and placed in the corresponding node, and the above steps are repeated until all track points are inserted to obtain a complete R-tree index. Through the above method, the R-tree index of low-orbit satellite track point data can be constructed.

[0078] In some embodiments of the present specification, searching in the R-tree index using the search region to obtain the earth unobstructed arc segment can include: starting from the root node of the R-tree index, determining whether there is an overlap between the root node and the search region, if yes, continuing to search in the child node corresponding to the root node, if a leaf node is searched, determining whether the searched leaf node is within the search region, if yes, adding the leaf node to the search result; until the smallest boundary rectangle intersecting the search region is accessed; generating the earth unobstructed arc segment according to the search result.

[0079] Due to the segmentation of R-tree to spatial data, the retrieval efficiency of data in R-tree can be greatly improved. Starting from the root node, for each node on the search path, traverse its MBB, if it intersects with the search box, continue to search in the child node corresponding to it, until all intersecting MBBs are accessed. For the searched leaf node, try to compare the search box with its MBB and data, if the data of the leaf node is in the search box, add it to the search result. Therefore, for any spatial position, the structure can be used to efficiently search the set of track points meeting the conditions.

[0080] In some embodiments of the present specification, constructing a search region according to the high-orbit satellite track point data, the high-orbit satellite orbit parameters and the low-orbit satellite orbit parameters can include: determining a first intersection position parameter between the line connecting the high-orbit satellite and the center of the earth and the low-orbit satellite orbit based on the high-orbit satellite track point data and the low-orbit satellite orbit parameters; calculating a second intersection position parameter between the tangent line of the high-orbit satellite and the earth and the low-orbit satellite orbit according to the high-orbit satellite orbit parameters and the low-orbit satellite orbit parameters; and constructing a search region according to the first intersection position parameter and the second intersection position parameter.

[0081] Please continue to refer to Figure 4 , which shows an R-tree search box establishment schematic diagram. Based on the high-orbit satellite track point data (here referring to the high-orbit satellite track point data in the earth-fixed coordinate system) and the low-orbit satellite orbit parameters, the first intersection position parameter between the line connecting the high-orbit satellite and the center of the earth and the low-orbit satellite orbit can be determined, that is, the coordinate data of G. According to the high-orbit satellite orbit parameters and the low-orbit satellite orbit parameters, the second intersection position parameter between the tangent line of the high-orbit satellite and the earth and the low-orbit satellite orbit can be calculated, that is, the coordinate data of A and B. The search region can be constructed according to the first intersection position parameter and the second intersection position parameter.

[0082] In one embodiment, the spatial search region used in the three-dimensional R-tree is a cube with the intersection G of the line connecting the center of the earth O and the high-orbit satellite on the low-orbit satellite orbit as the center, combined with the flight orbit height H of the high-orbit satelliteT with low orbit satellite flight orbit height H L , earth radius R E , according to the high and low orbit satellite and earth blocking relationship given in the necessary condition of satellite visibility judgment, the size of the edge length of the cube is twice AG, which can ensure that the low orbit satellite track point searched in the R-tree contains the corresponding low orbit satellite track point in the non-earth blocking arc segment of the high and low orbit satellite. Among them,

[0083] Among them,

[0084] In some embodiments of the present specification, the visibility judgment is performed on the low orbit satellite track point in the earth non-blocking arc segment, and the determination of the high and low orbit satellite visible time window can include: sorting the multiple low orbit satellite track points contained in the earth non-blocking arc segment in the corresponding time order, determining the first low orbit satellite track point closest to the high orbit satellite; judging whether the first low orbit satellite track point satisfies the visibility condition; in the case where it is determined that the first low orbit satellite track point satisfies the visibility condition, searching from the time corresponding to the first low orbit satellite track point to the rear using the binary search method to determine the visible start and end time of the high and low orbit satellite visible time window.

[0085] In the case where the time period corresponding to the task start and end time is greater than the running period of the low orbit satellite, the low orbit satellite may rotate more than one time around the earth in the time period corresponding to the task start and end time, therefore, the obtained earth non-blocking arc segment includes multiple earth non-blocking arc segments. After obtaining the earth non-blocking arc segment, the multiple low orbit satellite track points contained in each earth non-blocking arc segment can be sorted in the corresponding time order. Through binary search, the low orbit satellite track point closest to the high orbit satellite in each earth non-blocking arc segment can be found. It can be checked whether the high and low orbit satellites are visible at the time corresponding to the track point. If visible, the visible time corresponding to the track point is taken as the starting point, and the start and end time of the visible time window is searched forward and backward at the same time using the binary method. Since time is continuous, the accuracy of the start and end time is determined by the selected interpolation accuracy. If the target is within the visible range of the satellite at a certain time, the target is not within the visible range of the satellite at the previous time, then this time is the visible start time; if the target is within the visible range of the satellite at a certain time, the target is not within the visible range of the satellite at the next time, then this time is the visible end time.

[0086] In some embodiments of the present specification, after determining whether the first low-orbit satellite track point satisfies the visibility condition, further comprising: in the case where it is determined that the first low-orbit satellite track point does not satisfy the visibility condition, determining whether there is a visible time from the time corresponding to the first low-orbit satellite track point to the past; in the case where there is no visible time, determining that there is no visible time window in the earth unblocked arc segment.

[0087] If the time corresponding to the low-orbit satellite track point closest to the high-orbit satellite is not visible, then starting from this time, the other times in this arc segment are traversed forward and backward, and the visibility is calculated. If there is no visible time, this arc segment is discarded. If there is a visible time, the visible start and end times are calculated.

[0088] In some embodiments of the present specification, the high-low-orbit satellite visible time window calculation step based on R-tree index can include the following steps.

[0089] Step 1, establish an R-tree index of low-orbit satellites.

[0090] Step 2, according to the high-low-orbit satellite position information, construct a search area, and search all possible low-orbit satellite track point sets corresponding to the earth unblocked arc segment through R-tree.

[0091] Step 3, sort the track points in each potential visible arc segment by time, and find the low-orbit satellite track point closest to the high-orbit satellite through binary search.

[0092] Step 4, check whether the high-low-orbit satellites at the time corresponding to the track point are visible:

[0093] a if visible, execute step 5;

[0094] b if not visible, then starting from this time, the other times in this arc segment are traversed forward and backward, and the visibility is calculated. If there is no visible time, this arc segment is discarded; otherwise, step 5 is executed.

[0095] Step 5, calculate the visible start and end times. Starting from the visible time, the start and end times of the visible time window are searched forward and backward at the same time using binary search. Since time is continuous, the accuracy of the start and end times is determined by the selected interpolation accuracy. If the target is within the visible range of the satellite at a certain time, and the target is not within the visible range of the satellite at the previous time, then this time is the visible start time; if the target is within the visible range of the satellite at a certain time, and the target is not within the visible range of the satellite at the next time, then this time is the visible end time.

[0096] With the increasing number of satellites and the expanding user demand, joint observation of multi-satellite networking has become a hot research topic, which puts forward higher requirements for accuracy and efficiency. Therefore, for the visibility calculation problem between multiple high-orbit satellites and multiple low-orbit satellites, the divide-and-conquer idea is used. In the actual task execution, the task information can be distributed to different node servers according to the service configuration, each server processes the assigned task, and finally the execution results of all node tasks are output.

[0097] Therefore, in some embodiments of the present specification, the high-orbit satellite parameters include high-orbit satellite orbit parameters and high-orbit satellite trajectory point data corresponding to each high-orbit satellite in the plurality of high-orbit satellites, and the low-orbit satellite parameters include low-orbit satellite orbit parameters and low-orbit satellite trajectory point data corresponding to each low-orbit satellite in the plurality of low-orbit satellites. Correspondingly, before constructing the search area according to the high-orbit satellite trajectory point data, the high-orbit satellite orbit parameters and the low-orbit satellite orbit parameters, it further includes: for each high-orbit satellite in the plurality of high-orbit satellites, constructing a sub-task corresponding to the high-orbit satellite to obtain a plurality of sub-tasks; distributing the plurality of sub-tasks to different node servers for parallel execution; and the sub-task corresponding to each high-orbit satellite includes a high-low-orbit satellite visible time window determination task between the high-orbit satellite and each low-orbit satellite.

[0098] According to the configuration information of the satellite, the total task information can be first decomposed into multiple satellite sub-tasks, combined with parallel computing, and then the satellite sub-tasks can be further decomposed into single-pair visibility solving problems. Finally, all sub-problem results are summarized as total task results to form a high-low-orbit satellite visible time window real-time calculation algorithm based on R-tree. The main calculation steps are as follows:

[0099] Step 1, high-orbit satellite sub-task construction. Construct a low-orbit satellite trajectory point R-tree index, and each high-orbit satellite sub-task contains all low-orbit satellites. In addition, the sub-task also contains high-orbit satellite information, low-orbit satellite R-tree index, task start and end time, etc.

[0100] Step 2, parallel solving of high-low-orbit satellite visible time window information, decompose the observation task for each high-orbit satellite sub-task.

[0101] Step 3, according to the high-low-orbit satellite position information, construct a search area, and search all possible low-orbit satellite trajectory point sets corresponding to the non-geosynchronous arc segment through R-tree.

[0102] Step 4, sort the trajectory points in each potential visible arc segment by time, and find the nearest trajectory point to the high-orbit satellite through binary search.

[0103] Step 5, check whether the high-low-orbit satellites at the time corresponding to the trajectory point are visible:

[0104] a. If visible, go to step 6;

[0105] b. If not visible, traverse other time instants in this arc segment forward and backward, and calculate the visibility, if there is no visible time instant, discard this arc segment; otherwise, go to step 6.

[0106] Step 6, calculate the visible start and end time instants. Use the binary search method forward and backward to search the start and end time instants of the visible time window with the visible time instant as the starting point. Since time is continuous, the accuracy of the start and end time instants is determined by the selected interpolation accuracy. If the target is within the visible range of the satellite at a certain time instant, and the target is not within the visible range of the satellite at the previous time instant, then this time instant is the visible start time instant; if the target is within the visible range of the satellite at a certain time instant, and the target is not within the visible range of the satellite at the next time instant, then this time instant is the visible end time instant.

[0107] Step 7, merge and output the satellite sub-task results.

[0108] The method in this embodiment will be compared with the tracking propagation method and the results of STK software. The results of STK are taken as the benchmark, the accuracy is confirmed to 1 ms, and the deviation of the results of this algorithm from the STK results is in the brackets. A positive value indicates that the obtained visible start time instant is after the STK result, or the duration of the obtained visible time window is longer than the STK result; on the contrary, a negative value indicates that the obtained visible start time instant is before the STK result, or the duration of the obtained visible time window is shorter than the STK result.

[0109] The simulation start time instant and the satellite orbit root number corresponding time instant are both 2022-03-23 16:00:00.000 (UTCG), the simulation end time instant is 2022-03-24 16:00:00.000 (UTCG), the simulation duration is 1 day, the satellite orbit position calculation step is 1 s, the linear interpolation time instant accuracy is 1 ms, the maximum capacity of the R-tree node is set to M = 4, and the rotation range of the relay antenna azimuth and elevation is both -90° to +90°. The development language is java, and the running environment is a computer with Intel(R) Xeon(R) CPU E5-2640v4 @ 2.40GHz.

[0110] In this embodiment, the satellite root number information is set as shown in Table 1 below.

[0111] Table 1

[0112] Satellite Semi-major axis / km Eccentricity Orbital inclination / ° Argument of perigee / ° Longitude of ascending node / ° Mean anomaly / ° Leo 7009.835 0 97.814 0 204.456 44.242 Geo 42166.3 0 0 0 181.121 0

[0113] Please refer to Table 2 for the comparison results of the visible time window information of the observation of the low-orbit satellite by the high-orbit satellite.

[0114] Table 2

[0115] Window number Visible start time Visible duration 1 2022-03-23 17:18:07.572(-0.015) 873.616(0.008) 2 2022-03-23 18:55:25.723(-0.001) 886.261(0.014) 3 2022-03-24 03:50:42.485(-0.006) 887.839(0.018) 4 2022-03-24 05:28:14.121(-0.005) 873.508(0.005) 5 2022-03-24 07:05:30.374(-0.002) 581.584(0.002)

[0116] From the above, in the embodiment, by introducing the R-tree index, only considering the satellite track points in the range without the earth blockage, a large amount of calculation can be reduced, the simulation result proves that the algorithm can be on par with the STK in terms of accuracy, and the efficiency is 10000 times of the tracking propagation method with 1ms as the time step, thereby guaranteeing the reliability and high efficiency of the algorithm, and providing strong help for satellite mission planning. In actual application, parallel computing is adopted to realize fast calculation.

[0117] Each of the embodiments in the specification is described in a progressive manner, and the same and similar parts between the embodiments can be referred to each other, and each embodiment mainly describes the difference from other embodiments. Specifically, the description of the related embodiments of the foregoing related processing can be referred to, and will not be described here.

[0118] The foregoing describes specific embodiments of the specification. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps recited in the claims can be performed in an order different than the order in which the embodiments are presented, and still achieve desirable results. In addition, the processes depicted in the figures do not necessarily require the particular order shown, or sequential order, to achieve the desired results. In some implementations, multitasking and parallel processing can be utilized, or can be advantageous.

[0119] Based on the same inventive concept, the embodiments of the specification also provide a high-low orbit satellite visible time window determination device, as described in the following embodiments. Since the principle of solving the problem of the high-low orbit satellite visible time window determination device is similar to that of the high-low orbit satellite visible time window determination method, the implementation of the high-low orbit satellite visible time window determination device can be referred to the implementation of the high-low orbit satellite visible time window determination method, and the repeated parts will not be described here. The term "unit" or "module" used below can be a combination of software and / or hardware that achieves a predetermined function. Although the device described in the following embodiments is preferably implemented in software, hardware, or a combination of software and hardware is also possible and is contemplated. Figure 6 is a structural block diagram of the high-low orbit satellite visible time window determination device of the embodiments of the specification, as shown in Figure 6 The structure is described below.

[0120] The acquisition module 601 is configured to acquire high-orbit satellite parameters, low-orbit satellite parameters, and mission start and end time; the high-orbit satellite parameters include high-orbit satellite orbit parameters and high-orbit satellite track point data; the low-orbit satellite parameters include low-orbit satellite orbit parameters and low-orbit satellite track point data;

[0121] The index module 602 is configured to establish an R-tree index of the low-orbit satellite track point data, and is further configured to construct a search region according to the high-orbit satellite track point data, the high-orbit satellite orbit parameter and the low-orbit satellite orbit parameter.

[0122] The determination module 603 is configured to search in the R-tree index by using the search region to obtain an earth unblocked arc segment, and is further configured to perform visibility judgment on the low-orbit satellite track point in the earth unblocked arc segment to determine a high-low-orbit satellite visible time window.

[0123] In some embodiments of the present specification, the index module can be specifically configured to initialize an R-tree, add a track point in the low-orbit satellite track point data to the R-tree, determine a leaf node with the smallest volume increment after adding the track point, judge whether the number of track points in the leaf node is less than a preset number, if yes, add the track point to the leaf node, otherwise, split the track point and the track points in the leaf node into two leaf nodes according to the principle of the smallest volume increment, adjust the parent nodes level by level according to the splitting condition, and adjust the structure of the R-tree, until adding a plurality of track points in the low-orbit satellite track point data.

[0124] In some embodiments of the present specification, the index module can be further configured to determine a first intersection position parameter between a connecting line between the high-orbit satellite and the center of the earth and a low-orbit satellite orbit based on the high-orbit satellite track point data and the low-orbit satellite orbit parameter, calculate a second intersection position parameter between a tangent line of the high-orbit satellite and the earth and the low-orbit satellite orbit according to the high-orbit satellite orbit parameter and the low-orbit satellite orbit parameter, and construct a search region according to the first intersection position parameter and the second intersection position parameter.

[0125] In some embodiments of the present specification, the determination module can be specifically configured to start from a root node of the R-tree index, determine whether there is an overlap between the root node and the search region, if yes, continue searching in the child nodes corresponding to the root node, if a leaf node is searched, determine whether the searched leaf node is in the search region, if yes, add the leaf node to the search result, until the smallest boundary rectangle intersecting with the search region is accessed, and generate an earth unblocked arc segment according to the search result.

[0126] In some embodiments of the present specification, the determining module can be further configured to: sort the plurality of low-orbit satellite track points contained in the earth-unblocked arc segment according to corresponding time sequences, determine a first low-orbit satellite track point closest to the high-orbit satellite, determine whether the first low-orbit satellite track point meets the visibility condition, and in the case that the first low-orbit satellite track point is determined to meet the visibility condition, search backward from the time corresponding to the first low-orbit satellite track point in the earth-unblocked arc segment to determine the visible start and end time of the high-low-orbit satellite visible time window using a binary search method.

[0127] In some embodiments of the present specification, after determining whether the first low-orbit satellite track point meets the visibility condition, the method further comprises: in the case that the first low-orbit satellite track point is determined not to meet the visibility condition, determining whether there is a visible time in the earth-unblocked arc segment from the time corresponding to the first low-orbit satellite track point; and in the case that there is no visible time, determining that the earth-unblocked arc segment has no visible time window.

[0128] In some embodiments of the present specification, the high-orbit satellite parameters include high-orbit satellite orbit parameters and high-orbit satellite track point data corresponding to each high-orbit satellite of the plurality of high-orbit satellites, and the low-orbit satellite parameters include low-orbit satellite orbit parameters and low-orbit satellite track point data corresponding to each low-orbit satellite of the plurality of low-orbit satellites. Correspondingly, the device can further comprise a task allocation module, which can be specifically configured to: before the index module constructs the search region according to the high-orbit satellite track point data, the high-orbit satellite orbit parameters and the low-orbit satellite orbit parameters, construct a subtask corresponding to each high-orbit satellite of the plurality of high-orbit satellites to obtain a plurality of subtasks; and distribute the plurality of subtasks to different node servers for parallel execution. The subtask corresponding to each high-orbit satellite includes a high-low-orbit satellite visible time window determination task between the high-orbit satellite and the low-orbit satellites.

[0129] From the above description, it can be seen that the embodiments of the present specification achieve the following technical effects: by constructing an R-tree index of low-orbit satellite track point data, only considering satellite track points in the earth-unblocked range, a large amount of calculation can be reduced. Simulation results prove that the algorithm is on par with STK in terms of visibility accuracy, and the efficiency is 10000 times that of the tracking propagation method with a time step of 1ms, ensuring the reliability and efficiency of the algorithm, and providing theoretical guidance for satellite mission planning. In addition, in actual application, parallel computing can be used to achieve fast calculation.

[0130] The present specification also provides a computer device, which can be specifically referred to Figure 7A computer device structure diagram of the high and low orbit satellite visible time window determination method provided by the embodiments of the present application is shown, and the computer device specifically can include an input device 71, a processor 72, and a memory 73. The memory 73 is used to store processor executable instructions. The processor 72 executes the instructions to implement the steps of the high and low orbit satellite visible time window determination method described in any of the above embodiments.

[0131] In the present embodiment, the input device can be one of the main devices for information exchange between the user and the computer system. The input device can include a keyboard, a mouse, a camera, a scanner, a light pen, a handwriting input board, a voice input device, etc.; the input device is used to input raw data and programs for processing the data into the computer. The input device can also obtain data transmitted by other modules, units, and devices. The processor can be implemented in any appropriate manner. For example, the processor can take the form of, for example, a microprocessor or a processor and a computer readable medium storing computer readable program code (such as software or firmware) executable by the (micro) processor, logic gates, switches, application specific integrated circuits (ASIC), programmable logic controllers, and embedded microcontrollers, etc. The memory can be a memory device used to save information in modern information technology. The memory can include multiple levels, and in a digital system, as long as it can save binary data, it can be a memory; in an integrated circuit, a circuit without a physical form with a storage function is also called a memory, such as RAM, FIFO, etc.; in a system, a storage device with a physical form is also called a memory, such as a memory stick, a TF card, etc.

[0132] In the present embodiment, the functions and effects realized by the computer device can be explained in comparison with other embodiments, and will not be repeated here.

[0133] The embodiments of the present application also provide a computer storage medium based on the high and low orbit satellite visible time window determination method, which stores computer program instructions. When the computer program instructions are executed, the steps of the high and low orbit satellite visible time window determination method described in any of the above embodiments are implemented.

[0134] In the present embodiment, the storage medium includes, but is not limited to, a random access memory (RAM), a read-only memory (ROM), a cache, a hard disk drive (HDD), or a memory card. The storage medium can be used to store computer program instructions. The network communication unit can be an interface configured according to a standard set by a communication protocol, and used to perform network connection communication.

[0135] In the present embodiment, the functions and effects realized by the program instructions stored in the computer storage medium can be explained in comparison with other embodiments, and will not be described here again.

[0136] Obviously, those skilled in the art should understand that each module or each step of the above-described embodiments of the present specification can be implemented by a general computing device, which can be concentrated on a single computing device, or distributed on a network composed of multiple computing devices, and optionally, they can be implemented by program codes executable by a computing device, so that they can be stored in a storage device and executed by a computing device, and in some cases, the steps shown or described can be executed in an order different from here, or they can be manufactured into each integrated circuit module respectively, or a plurality of modules or steps among them can be manufactured into a single integrated circuit module to realize. Thus, the embodiments of the present specification are not limited to any specific combination of hardware and software.

[0137] It should be understood that the above description is intended for illustration only and not for the purpose of limiting. Many implementations and many applications other than the examples provided would be apparent to those skilled in the art from the above description. The scope of the present specification should therefore not be determined with reference to the above description, but instead should be determined with reference to the appended claims along with their full scope of equivalents.

[0138] The above only describes the preferred embodiments of the present specification and is not intended to limit the present specification. The embodiments of the present specification can have various modifications and changes for those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present specification shall be included in the protection scope of the present specification.

Claims

1. A method for determining a high-low orbit satellite visible time window, characterized in that, The method comprises the following steps: obtaining high-orbit satellite parameters, low-orbit satellite parameters and task start and end time; the high-orbit satellite parameters comprise high-orbit satellite orbit parameters and high-orbit satellite track point data; the low-orbit satellite parameters comprise low-orbit satellite orbit parameters and low-orbit satellite track point data; establishing an R-tree index of the low-orbit satellite track point data; constructing a search area according to the high-orbit satellite track point data, the high-orbit satellite orbit parameters and the low-orbit satellite orbit parameters; searching in the R-tree index by using the search area to obtain an earth unblocked arc segment; judging the visibility of the low-orbit satellite track points in the earth unblocked arc segment to determine a high-low-orbit satellite visible time window; wherein, constructing a search area according to the high-orbit satellite track point data, the high-orbit satellite orbit parameters and the low-orbit satellite orbit parameters comprises: determining a first intersection position parameter between a line connecting the high-orbit satellite and the center of the earth and a low-orbit satellite orbit based on the high-orbit satellite track point data and the low-orbit satellite orbit parameters; calculating a second intersection position parameter between a tangent line of the high-orbit satellite and the earth and the low-orbit satellite orbit according to the high-orbit satellite orbit parameters and the low-orbit satellite orbit parameters; constructing a search area according to the first intersection position parameter and the second intersection position parameter. 2.The high-low orbit satellite visible time window determination method according to claim 1, characterized in that, establishing an R-tree index of the low-orbit satellite track point data comprises: initializing the R-tree; adding a track point in the low-orbit satellite track point data to the R-tree to determine a leaf node with the minimum volume increment after adding the track point; judging whether the number of track points in the leaf node is less than a preset number; if yes, adding the track point to the leaf node; otherwise, splitting the track point and the track points in the leaf node into two leaf nodes according to the minimum volume increment principle, adjusting the parent nodes level by level according to the splitting condition, and adjusting the structure of the R-tree; until adding all the track points in the low-orbit satellite track point data. 3.The high-low orbit satellite visible time window determination method according to claim 1, characterized in that, searching in the R-tree index by using the search area to obtain an earth unblocked arc segment comprises: starting from the root node of the R-tree index, determining whether there is an overlap between the root node and the search area; if yes, continuing to search in the child nodes corresponding to the root node; if a leaf node is searched, determining whether the searched leaf node is in the search area; if yes, adding the leaf node to the search result; until all the minimum boundary rectangles intersecting with the search area are accessed; generating an earth unblocked arc segment according to the search result. 4.The method of claim 1, wherein, judging the visibility of the low-orbit satellite track points in the earth unblocked arc segment to determine a high-low-orbit satellite visible time window comprises: sorting the low-orbit satellite track points contained in the earth unblocked arc segment according to the corresponding time sequence to determine a first low-orbit satellite track point closest to the high-orbit satellite; judging whether the first low-orbit satellite track point meets the visibility condition; In a case where it is determined that the first low earth orbit satellite trajectory point satisfies the visibility condition, a binary search method is used to search from a time corresponding to the first low earth orbit satellite trajectory point to a time before the earth unblocked arc segment, to determine a visible start and end time of a high-low earth orbit satellite visible time window. 5.The high-low orbit satellite visible time window determination method according to claim 4, characterized in that, After judging whether the first low earth orbit satellite trajectory point satisfies the visibility condition, the method further includes: In a case where it is determined that the first low earth orbit satellite trajectory point does not satisfy the visibility condition, it is judged whether there is a visible time from a time corresponding to the first low earth orbit satellite trajectory point to a time before the earth unblocked arc segment; In a case where there is no visible time, it is determined that there is no visible time window in the earth unblocked arc segment. 6.The high-low orbit satellite visible time window determination method according to claim 1, characterized in that, The high orbit satellite parameters include high orbit satellite orbit parameters and high orbit satellite trajectory point data of each high orbit satellite in the plurality of high orbit satellites; and the low orbit satellite parameters include low orbit satellite orbit parameters and low orbit satellite trajectory point data of each low orbit satellite in the plurality of low orbit satellites. Correspondingly, before constructing a search region according to the high orbit satellite trajectory point data, the high orbit satellite orbit parameters and the low orbit satellite orbit parameters, the method further includes: For each high orbit satellite in the plurality of high orbit satellites, a subtask corresponding to the high orbit satellite is constructed, to obtain a plurality of subtasks. The plurality of subtasks are distributed to different node servers for parallel execution; and the subtask corresponding to each high orbit satellite includes a high-low earth orbit satellite visible time window determination task between the high orbit satellite and the low orbit satellites. 7.A device for determining high-low orbit satellite visible time window, characterized in that, The method includes: an acquisition module configured to acquire high orbit satellite parameters, low orbit satellite parameters and task start and end times; The high orbit satellite parameters include high orbit satellite orbit parameters and high orbit satellite trajectory point data; and the low orbit satellite parameters include low orbit satellite orbit parameters and low orbit satellite trajectory point data. an index module configured to establish an R-tree index of the low orbit satellite trajectory point data; The index module is further configured to construct a search region according to the high orbit satellite trajectory point data, the high orbit satellite orbit parameters and the low orbit satellite orbit parameters; a determination module configured to search in the R-tree index by using the search region, to obtain an earth unblocked arc segment; and further configured to perform a visibility judgment on a low orbit satellite trajectory point in the earth unblocked arc segment, to determine a high-low earth orbit satellite visible time window. The index module is specifically configured to: determine a first intersection position parameter between a line connecting a high orbit satellite and a center of the earth and a low orbit satellite orbit based on the high orbit satellite trajectory point data and the low orbit satellite orbit parameters; and calculate a second intersection position parameter between a tangent of the high orbit satellite and the earth and the low orbit satellite orbit based on the high orbit satellite orbit parameters and the low orbit satellite orbit parameters; The search region is constructed according to the first intersection position parameter and the second intersection position parameter.

8. A computer device, comprising: The instructions are executed by the processor to implement the steps of the method in any one of claims 1 to 6.

9. A computer readable storage medium having stored thereon computer instructions, wherein, The instructions are executed by the processor to implement the steps of the method in any one of claims 1 to 6.

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