GNSS-R satellite average revisit time calculation method, electronic device and storage medium

Abstract

The present application discloses a method for calculating the average revisit time of a GNSS-R satellite, an electronic device, and a storage medium. The embodiment of the present application determines a grid map of the earth's surface based on a preset unit distance, and determines the longitude and latitude range of each grid; obtains the number of continuous sampling points falling within each grid according to the longitude and latitude range and GNSS-R satellite data, and determines the number of revisits corresponding to a single grid; determines a revisit time matrix based on the number of revisits and time parameters corresponding to a single grid; determines the average revisit time corresponding to each latitude interval based on the revisit time matrix, the number of grids contained in the longitude variation range corresponding to each latitude interval in the target longitude and latitude data, the longitude variation range, and the preset unit distance. The present application can calculate the revisit time of a GNSS-R satellite and evaluate the spatial coverage capability of a GNSS-R satellite.

Description

Technical Field

[0001] The present application relates to the field of GNSS-R satellite technology, and in particular to a method for calculating an average revisit time of a GNSS-R satellite, an electronic device, and a storage medium. Background Art

[0002] The Global Navigation Satellite System-Reflectometry (GNSS-R) technology utilizes existing GNSS-R satellites and does not require active signal reflection. It has the advantages of miniaturization, low cost, and low power consumption. It is very suitable for being carried by small satellites to form constellations and achieve high temporal and spatial resolution observations of the earth. The main difference between GNSS-R technology and traditional remote sensing technology is that the observation points of GNSS-R are strip-shaped, and the sampling points within the strips are relatively dense. The analysis of the temporal and spatial resolution of GNSS-R satellites is very important for the design of GNSS-R constellations and the evaluation of detection capabilities. The average revisit time is an important indicator for measuring the temporal and spatial resolution of satellite constellations. It is defined as the average time interval between two observations of the same grid at a certain spatial resolution of the constellation observation data. The smaller the average revisit time, the higher the temporal and spatial resolution of the constellation and the better the observation effect.

[0003] At present, due to the unique observation system of GNSS-R technology, the calculation of its average revisit time also needs to be specifically considered based on its technical characteristics. There are few calculation methods for the average revisit time in the existing technology, and the average revisit time calculated by the method does not take into account the continuous and intensive sampling characteristics of GNSS-R in a short period of time. The accuracy is low, which is not conducive to accurately evaluating the spatial coverage capability of GNSS-R satellites. Summary of the invention

[0004] The purpose of the embodiments of the present application is to provide a method for calculating the average revisit time of GNSS-R satellites, an electronic device and a storage medium, which can solve the problem of low calculation accuracy in the process of calculating the average revisit time of GNSS-R satellites in related technologies. Since the average revisit time is an important indicator for measuring the spatiotemporal resolution of GNSS-R satellites, the smaller the average revisit time, the higher the spatiotemporal resolution of the GNSS-R satellites and the better the observation effect. When the calculation accuracy of the average revisit time is low, the spatiotemporal resolution of the GNSS-R satellites will be misestimated.

[0005] In order to solve the above technical problems, the embodiments of the present application are implemented as follows:

[0006] In a first aspect, an embodiment of the present application provides a method for calculating an average revisit time of a GNSS-R satellite, which is applied to a GNSS-R system, and the method includes:

[0007] Determine a grid map of the earth's surface based on a preset unit distance, and determine the latitude and longitude range of each grid;

[0008] According to the latitude and longitude range and the GNSS-R satellite data, the number of continuous sampling points falling within each grid is obtained, and the number of revisits corresponding to the single grid is determined;

[0009] Determine a revisit time matrix based on the number of revisits and time parameters corresponding to the single grid;

[0010] Based on the revisit time matrix, the number of grids contained in the longitude variation range corresponding to each latitude interval in the target longitude and latitude data, the longitude variation range and the preset unit distance, the average revisit time corresponding to each latitude interval is determined.

[0011] Optionally, determining a revisit time matrix based on the number of revisits and time parameters corresponding to the single grid includes:

[0012] Determine a revisit number matrix based on the revisit number corresponding to the single grid;

[0013] A revisit time matrix is ​​determined based on the revisit number matrix and a time parameter.

[0014] Optionally, obtaining the number of continuous sampling points falling within each grid according to the latitude and longitude range and the GNSS-R satellite data, and determining the number of revisits corresponding to the single grid includes:

[0015] According to the longitude and latitude range and the longitude and latitude data corresponding to the mirror reflection point in the GNSS-R satellite data, the GNSS-R satellite data is mapped into a grid map on the earth's surface to obtain the number of continuous sampling points falling within each grid;

[0016] Based on the longitude data and latitude data corresponding to each mirror reflection point, determine the coordinate data corresponding to each mirror reflection point in the revisit number matrix;

[0017] Based on the coordinate data and the single grid, the number of revisits corresponding to the single grid is determined.

[0018] Optionally, determining the number of revisits corresponding to the single grid based on the coordinate data and the single grid includes:

[0019] Determine the number of specular reflection points in a single grid based on the diagonal length corresponding to the single grid and the moving speed of the specular reflection points;

[0020] When the time threshold between the coordinate data corresponding to two adjacent mirror reflection points is greater than or equal to the preset time threshold, the number of revisits corresponding to the single grid is determined to be increased by 1;

[0021] When the time threshold between the coordinate data corresponding to two adjacent mirror reflection points is less than the preset time threshold, the number of revisit times corresponding to the single grid is determined to be increased by 0.

[0022] Optionally, the longitude data corresponding to a single grid map in the earth surface grid map and latitude data It is expressed as:

[0023] ;

[0024] ;

[0025] in, is the preset unit distance, , , , 360 / d+1.

[0026] Optionally, the revisit time matrix is ​​expressed as:

[0027] ;

[0028] in, is the time parameter, is the revisit count matrix, , , , 360 / d+1.

[0029] Optionally, the average revisit time corresponding to each latitude interval is expressed as:

[0030] ;

[0031] in, is the preset unit distance, is the longitude variation range corresponding to each latitude interval in the target longitude and latitude data, is the revisit time matrix, It is the number of grids contained in the longitude variation range corresponding to each latitude interval in the target longitude and latitude data.

[0032] In a second aspect, an embodiment of the present application provides a device for calculating an average revisit time of a GNSS-R satellite, the device comprising:

[0033] The first determination module is used to determine the earth surface grid map based on a preset unit distance and determine the longitude and latitude range of each grid; obtain the number of continuous sampling points falling within each grid according to the longitude and latitude range and GNSS-R satellite data, and determine the number of revisits corresponding to the single grid; determine the revisit time matrix based on the number of revisits and time parameters corresponding to the single grid; determine the average revisit time corresponding to each latitude interval based on the revisit time matrix, the number of grids contained in the longitude variation range corresponding to each latitude interval in the target longitude and latitude data, the longitude variation range and the preset unit distance.

[0034] Optionally, the device further comprises:

[0035] The second determination module is used to determine a revisit number matrix based on the revisit number corresponding to the single grid; and determine a revisit time matrix based on the revisit number matrix and a time parameter.

[0036] Optionally, the device further comprises:

[0037] A first acquisition module is used to map the GNSS-R satellite data into a grid map on the earth's surface according to the longitude and latitude range and the longitude data and latitude data corresponding to the mirror reflection point in the GNSS-R satellite data, and obtain the number of continuous sampling points falling within each grid;

[0038] The first determination submodule is used to determine the coordinate data corresponding to each mirror reflection point in the revisit number matrix based on the longitude data and latitude data corresponding to each mirror reflection point; and determine the revisit number corresponding to the single grid based on the coordinate data and the single grid.

[0039] Optionally, the device further comprises:

[0040] The second determination submodule is used to determine the number of mirror reflection points in a single grid based on the diagonal length corresponding to the single grid and the moving speed of the mirror reflection points; when the time threshold between the coordinate data corresponding to two adjacent mirror reflection points is greater than or equal to the preset time threshold, determine that the number of revisits corresponding to the single grid is increased by 1; when the time threshold between the coordinate data corresponding to two adjacent mirror reflection points is less than the preset time threshold, determine that the number of revisits corresponding to the single grid is increased by 0.

[0041] Optionally, the longitude data corresponding to a single grid map in the earth surface grid map and latitude data It is expressed as:

[0042] ;

[0043] ;

[0044] in, is the preset unit distance, , , , 360 / d+1.

[0045] Optionally, the revisit time matrix is ​​expressed as:

[0046] ;

[0047] in, is the time parameter, is the revisit count matrix, , , , 360 / d+1.

[0048] Optionally, the average revisit time corresponding to each latitude interval is expressed as:

[0049] ;

[0050] in, is the preset unit distance, is the longitude variation range corresponding to each latitude interval in the target longitude and latitude data, is the revisit time matrix, It is the number of grids contained in the longitude variation range corresponding to each latitude interval in the target longitude and latitude data.

[0051] In a third aspect, an embodiment of the present application provides an electronic device, comprising a processor, a memory, a communication interface and a communication bus, wherein the processor, the memory and the communication interface communicate with each other through the communication bus; the memory is used to store executable instructions, and the executable instructions enable the processor to execute the method for calculating the average revisit time of GNSS-R satellites as described in any one of the above items.

[0052] In a fourth aspect, an embodiment of the present application provides a readable storage medium, on which a program or instruction is stored. When the program or instruction is executed by a processor, the method for calculating the average revisit time of GNSS-R satellites as described in any of the above items is implemented.

[0053] In an embodiment of the present application, a method for calculating the average revisit time of a GNSS-R satellite is provided. A grid map of the earth's surface is determined based on a preset unit distance, and the longitude and latitude range of each grid is determined; the number of continuous sampling points falling within each grid is obtained according to the longitude and latitude range and GNSS-R satellite data, and the number of revisits corresponding to a single grid is determined; a revisit time matrix is ​​determined based on the number of revisits and time parameters corresponding to a single grid; based on the revisit time matrix, the number of grids contained in the longitude variation range corresponding to each latitude interval in the target longitude and latitude data, the longitude variation range and the preset unit distance, the average revisit time corresponding to each latitude interval is determined, and the average revisit time of the GNSS-R satellite is calculated. In the process of calculating the revisit time, the GNSS-R system can first determine the earth surface grid map based on the preset unit distance, and determine the longitude and latitude range of each grid, that is, by mapping the GNSS-R satellite data to the earth surface grid map, the longitude and latitude range of each grid can be determined. Then, the GNSS-R system can first determine the revisit time matrix based on the number of revisits and time parameters corresponding to a single grid, and then determine the average revisit time corresponding to each latitude interval according to the revisit time matrix, the number of grids contained in the longitude change range corresponding to each latitude interval in the target longitude and latitude data, the longitude change range and the preset unit distance, and then evaluate the spatial coverage capability of the GNSS-R satellite.

[0054] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the description of the embodiments of the present application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0056] Figure 1 The steps of the method for calculating the average revisit time of GNSS-R satellites provided in the embodiment of the present application are as follows: Figure 1 ;

[0057] Figure 2 The steps of the method for calculating the average revisit time of GNSS-R satellites provided in the embodiment of the present application are as follows: Figure 2 ;

[0058] Figure 3 A schematic diagram of the position and grid of a mirror reflection point provided in an embodiment of the present application;

[0059] Figure 4 The average revisit time of the GNSS-R satellite at different latitudes in a 0.25 degree grid provided in the embodiment of the present application;

[0060] Figure 5 A logic block diagram of a device for calculating the average revisit time of a GNSS-R satellite provided in an embodiment of the present application;

[0061] Figure 6 A schematic diagram of the structure of an electronic device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0062] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0063] The terms "first", "second", etc. in the specification and claims of the present application are used to distinguish similar objects, and are not used to describe a specific order or sequence. It should be understood that the data used in this way can be interchangeable under appropriate circumstances, so that the embodiments of the present application can be implemented in an order other than those illustrated or described here, and the objects distinguished by "first", "second", etc. are generally of one type, and the number of objects is not limited. For example, the first object can be one or more. In addition, "and / or" in the specification and claims represents at least one of the connected objects, and the character " / " generally indicates that the objects associated with each other are in an "or" relationship.

[0064] Method Embodiment

[0065] The following is a detailed description of the method for calculating the average revisit time of GNSS-R satellites provided in the embodiment of the present application through specific embodiments and application scenarios in conjunction with the accompanying drawings.

[0066] Reference Figure 1 , showing the steps of a method for calculating the average revisit time of a GNSS-R satellite provided in an embodiment of the present application Figure 1 ,like Figure 1 As shown, the method specifically includes steps S101 to S104:

[0067] Step S101: determine a grid map of the earth's surface based on a preset unit distance, and determine the longitude and latitude range of each grid.

[0068] In this step, in the process of calculating the average revisit time of the GNSS-R satellite, the GNSS-R system may first determine a grid map of the earth's surface based on a preset unit distance, and determine the longitude and latitude range of each grid.

[0069] In this step, the grid map of the earth's surface can be determined according to a preset unit distance, and the preset unit distance can be 0.25°, 0.5°, 1°, etc., which is not limited in the embodiments of the present application.

[0070] In this step, the GNSS-R satellite data may include GNSS-R satellite data composed of 22 polar-orbiting satellites (orbit altitude 520 km), which is not limited in the embodiments of the present application.

[0071] In this step, the target longitude and latitude data may be the longitude and latitude data obtained by mapping the GNSS-R satellite data into a grid map of the earth's surface, which is not limited in the embodiments of the present application.

[0072] Furthermore, the longitude data corresponding to a single grid map in the earth surface grid map and latitude data It is expressed as:

[0073] ;

[0074] ;

[0075] in, is the preset unit distance, , , , 360 / d+1.

[0076] In this step, a single grid map may be the smallest unit in the grid map of the earth's surface, which is not limited in the embodiments of the present application.

[0077] In this step, the longitude data corresponding to a single grid map can be obtained with the center of the earth as the origin, which is not limited in the embodiments of the present application.

[0078] Exemplarily, in this step, taking the center of the earth as the origin, the longitude data corresponding to a single grid map can be 116 degrees 20 minutes east longitude, or 45°, etc., which is not limited in the embodiments of the present application.

[0079] In this step, the latitude data corresponding to a single grid map can be obtained with the center of the earth as the origin, which is not limited in the embodiments of the present application.

[0080] Exemplarily, in this step, taking the center of the earth as the origin, the latitude data corresponding to a single grid map can be obtained as 39 degrees 54 minutes north latitude, or 45°, etc., which is not limited in the embodiments of the present application.

[0081] Step S102: According to the latitude and longitude range and the GNSS-R satellite data, the number of continuous sampling points falling within each grid is obtained, and the number of revisits corresponding to a single grid is determined.

[0082] In this step, after determining the earth's surface grid map based on the preset unit distance and determining the longitude and latitude range of each grid, the GNSS-R system can also obtain the number of continuous sampling points falling within each grid based on the longitude and latitude range and GNSS-R satellite data, and determine the number of revisits corresponding to a single grid.

[0083] In this step, the number of continuous sampling points falling within a single grid of the target longitude and latitude data may be any value greater than 0, for example, the number of continuous sampling points may be 100, or 300, etc., which is not limited in the embodiments of the present application.

[0084] Illustratively, in this step, the number of revisits corresponding to a single grid may be 5, which is not limited in the embodiments of the present application.

[0085] In this step, when the number of continuous sampling points falling within each grid is obtained according to the latitude and longitude range and the GNSS-R satellite data, and the number of revisits corresponding to a single grid is determined, the method for calculating the average revisit time of the GNSS-R satellite may further include steps S1021 to S1023:

[0086] Step S1021: Map the GNSS-R satellite data to a grid map of the earth's surface according to the longitude and latitude range and the longitude and latitude data corresponding to the mirror reflection point in the GNSS-R satellite data, and obtain the number of continuous sampling points falling within each grid.

[0087] In this step, when obtaining the number of continuous sampling points falling within each grid based on the longitude and latitude range and the GNSS-R satellite data and determining the number of revisits corresponding to a single grid, the GNSS-R system can map the GNSS-R satellite data to the earth's surface grid map based on the longitude and latitude range and the longitude data and latitude data corresponding to the mirror reflection point in the GNSS-R satellite data to obtain the number of continuous sampling points falling within each grid.

[0088] In this step, the longitude data corresponding to each reflection point may be 100 degrees 20 minutes east longitude, or 45°, etc., which is not limited in the embodiments of the present application.

[0089] Exemplarily, in this step, the latitude data corresponding to each reflection point may be 40 degrees and 50 minutes north latitude, or 35°, etc., which is not limited in the embodiments of the present application.

[0090] Step S1022: Determine the coordinate data corresponding to each mirror reflection point in the revisit times matrix based on the longitude data and latitude data corresponding to each mirror reflection point.

[0091] In this step, after mapping the GNSS-R satellite data to the grid map of the earth's surface according to the longitude and latitude range and the longitude data and latitude data corresponding to the mirror reflection points in the GNSS-R satellite data, and obtaining the number of continuous sampling points falling within each grid, the GNSS-R system can also determine the coordinate data corresponding to each mirror reflection point in the revisit count matrix based on the longitude data and latitude data corresponding to each mirror reflection point.

[0092] In this step, in the process of calculating the average revisit time of the GNSS-R satellite, the GNSS-R system can also determine the coordinate data corresponding to each mirror reflection point in the revisit number matrix based on the longitude data and latitude data corresponding to each mirror reflection point.

[0093] In this step, the coordinate data corresponding to each mirror reflection point in the revisit frequency matrix may include abscissa data and ordinate data, the abscissa data corresponds to latitude data, and the ordinate data corresponds to longitude data.

[0094] Exemplarily, the coordinate data may be the coordinate data of the 175th row and the 306th column in the revisit frequency matrix, etc., which is not limited in the embodiments of the present application.

[0095] Step S1023: Determine the number of revisits corresponding to the single grid based on the coordinate data and the single grid.

[0096] In this step, after determining the coordinate data corresponding to each mirror reflection point in the revisit number matrix based on the longitude data and latitude data corresponding to each mirror reflection point, the GNSS-R system can also determine the revisit number corresponding to a single grid based on the coordinate data and the single grid.

[0097] Furthermore, in the process of determining the number of revisit times corresponding to a single grid based on the coordinate data and the single grid, the method for calculating the average revisit time of the GNSS-R satellite may further include steps S10231 to S10233:

[0098] Step S10231: Determine the number of specular reflection points in a single grid based on the length of the diagonal corresponding to the single grid and the moving speed of the specular reflection points.

[0099] In this step, in the process of determining the number of revisits corresponding to a single grid based on the coordinate data and the single grid, the GNSS-R system can also determine the number of mirror reflection points in the single grid based on the diagonal length corresponding to the single grid and the moving speed of the mirror reflection points.

[0100] In this step, the diagonal length corresponding to a single grid can be determined based on the length and width of the single grid. For example, when the length and width of a single grid are both 25 km, the diagonal length corresponding to the single grid can be determined to be 25, which is not limited in the embodiments of the present application.

[0101] Exemplarily, in this step, the moving speed of the mirror reflection point may be 6 km / s, which is not limited in the embodiments of the present application.

[0102] In this step, the number of mirror reflection points in a single grid can be determined according to the diagonal length corresponding to the single grid and the moving speed of the mirror reflection point. For example, the diagonal length corresponding to the single grid is divided by the moving speed of the mirror reflection point to obtain the number of mirror reflection points in a single grid. For example, when the diagonal length is approximately and the moving speed of the mirror reflection point is 6 km / s, the number of mirror reflection points in a single grid can be obtained, which is not limited in the embodiments of the present application.

[0103] Step S10232: when the time threshold between the coordinate data corresponding to two adjacent mirror reflection points is greater than or equal to the preset time threshold, determine the corresponding number of revisits in a single grid and add 1.

[0104] In this step, after determining the number of mirror reflection points in a single grid based on the diagonal length corresponding to the single grid and the moving speed of the mirror reflection point, the GNSS-R system can also determine the corresponding number of revisits in the single grid plus 1 when the time threshold between the coordinate data corresponding to two adjacent mirror reflection points is greater than or equal to the preset time threshold.

[0105] In this step, the time threshold between two adjacent mirror reflection points may be 5 seconds, or 7 seconds, etc., which is not limited in the embodiments of the present application.

[0106] In this step, the preset time threshold may be equivalent to the number of mirror reflection points in a single grid. For example, when the number of mirror reflection points in a single grid is 5, the preset time threshold may be 5s, etc., which is not limited in the embodiments of the present application.

[0107] In this step, when the time threshold between two adjacent mirror reflection points is greater than or equal to the preset time threshold, the corresponding number of revisits in a single grid is increased by 1. For example, when the time threshold between two adjacent mirror reflection points is 6s and the preset time threshold is 5s, the corresponding number of revisits in a single grid is increased by 1, which is not limited in the embodiments of the present application.

[0108] Step S10233: when the time threshold between the coordinate data corresponding to two adjacent mirror reflection points is less than the preset time threshold, determine the corresponding number of revisits in a single grid and add 0.

[0109] In this step, after determining the number of mirror reflection points in a single grid based on the diagonal length corresponding to the single grid and the moving speed of the mirror reflection point, the GNSS-R system can also determine that the corresponding number of revisits in the single grid is plus 0 when the time threshold between the coordinate data corresponding to two adjacent mirror reflection points is less than the preset time threshold.

[0110] In this step, when the time threshold between two adjacent mirror reflection points is less than the preset time threshold, the corresponding number of revisits in a single grid is increased by 0. For example, when the time threshold between two adjacent mirror reflection points is 5s and the preset time threshold is 6s, the corresponding number of revisits in a single grid is increased by 0, which is not limited in the embodiments of the present application.

[0111] Step S103: Determine a revisit time matrix based on the number of revisits and time parameters corresponding to a single grid.

[0112] In this step, after obtaining the number of continuous sampling points falling within each grid according to the longitude and latitude range and GNSS-R satellite data and determining the number of revisits corresponding to a single grid, the GNSS-R system can also determine the revisit time matrix based on the number of revisits corresponding to a single grid and the time parameters.

[0113] In this step, the time parameter may be any data greater than 0, for example, the time parameter may be 10 days, or 5 days, etc., which is not limited in the embodiments of the present application.

[0114] In this step, the revisit time matrix may be determined based on the revisit number matrix and the time parameter.

[0115] Exemplarily, the revisit time matrix may be a time matrix with 181 rows and 361 columns, and the dimensions of the revisit time matrix and the revisit number matrix are the same.

[0116] In this step, when determining the revisit time matrix based on the number of revisits and time parameters corresponding to a single grid, the method for calculating the average revisit time of the GNSS-R satellite may further include steps S1031 to S1032:

[0117] Step S1031: Determine a revisit number matrix based on the revisit number corresponding to a single grid.

[0118] In this step, when determining the revisit time matrix based on the number of revisits and time parameters corresponding to a single grid, the GNSS-R system may also determine the revisit number matrix based on the number of revisits corresponding to a single grid.

[0119] In this step, the revisit frequency matrix may be a matrix of 181 rows and 361 columns, and the elements in the matrix are determined by comparing the time threshold between two adjacent reflection points with a preset time threshold.

[0120] Step S1032: Determine a revisit time matrix based on the revisit number matrix and the time parameter.

[0121] In this step, after determining the revisit number matrix based on the number of revisits corresponding to a single grid, the GNSS-R system may also determine the revisit time matrix based on the revisit number matrix and the time parameter.

[0122] Furthermore, the revisit time matrix is ​​expressed as:

[0123] ;

[0124] in, is the time parameter, is the revisit count matrix, , , , 360 / d+1.

[0125] Exemplarily, in this step, Can be Etc., are not limited in the embodiments of the present application.

[0126] Furthermore, the average revisit time corresponding to each latitude interval is expressed as:

[0127] ;

[0128] in, is the preset unit distance, is the longitude variation range corresponding to each latitude interval in the target longitude and latitude data, is the revisit time matrix, It is the number of grids contained in the longitude variation range corresponding to each latitude interval in the target longitude and latitude data.

[0129] Exemplarily, in this step, It can be 361, etc., which is not limited in the embodiments of the present application.

[0130] Step S104, determining the average revisit time corresponding to each latitude interval based on the revisit time matrix, the number of grids contained in the longitude variation range corresponding to each latitude interval in the target longitude and latitude data, the longitude variation range and the preset unit distance.

[0131] In this step, after determining the revisit time matrix based on the number of revisits and time parameters corresponding to a single grid, the GNSS-R system can also determine the average revisit time corresponding to each latitude interval based on the revisit time matrix, the number of grids contained in the longitude variation range corresponding to each latitude interval in the target longitude and latitude data, the longitude variation range, and the preset unit distance.

[0132] In this step, the number of grids contained in the longitude variation range corresponding to each latitude interval in the target longitude and latitude data may be 361, etc., which is not limited in the embodiments of the present application.

[0133] In this step, the longitude variation range can be determined based on the average distance of the earth, the average radius of the earth and the longitude variation function.

[0134] In this step, the preset unit distance may be 0.25°, 0.5°, 1°, etc., which is not limited in the embodiments of the present application.

[0135] In this step, the average revisit time corresponding to each latitude interval can be determined according to the revisit time matrix, the number of grids contained in the longitude variation range corresponding to each latitude interval in the target longitude and latitude data, the longitude variation range, and the preset unit distance. For example, the average revisit time is determined by the following expression:

[0136] ;

[0137] in, is the preset unit distance, is the longitude variation range corresponding to each latitude interval in the target longitude and latitude data, is the revisit time matrix, It is the number of grids contained in the longitude variation range corresponding to each latitude interval in the target longitude and latitude data.

[0138] In summary, the present application provides a method for calculating the average revisit time of a GNSS-R satellite. The method determines a grid map of the earth's surface based on a preset unit distance, and determines the longitude and latitude range of each grid. According to the longitude and latitude range and GNSS-R satellite data, the number of continuous sampling points falling within each grid is obtained, and the number of revisits corresponding to a single grid is determined. Based on the number of revisits and time parameters corresponding to a single grid, a revisit time matrix is ​​determined. Based on the revisit time matrix, the number of grids contained in the longitude variation range corresponding to each latitude interval in the target longitude and latitude data, the longitude variation range and the preset unit distance, the average revisit time corresponding to each latitude interval is determined, and the GNSS-R satellite average is calculated. In the process of calculating the revisit time, the GNSS-R system can first determine the grid map of the earth's surface based on the preset unit distance, and determine the longitude and latitude range of each grid, that is, by mapping the GNSS-R satellite data to the grid map of the earth's surface, the longitude and latitude range of each grid can be determined. Then, the GNSS-R system can first determine the revisit time matrix based on the number of revisits and time parameters corresponding to a single grid, and then determine the average revisit time corresponding to each latitude interval based on the revisit time matrix, the number of grids contained in the longitude change range corresponding to each latitude interval in the target longitude and latitude data, the longitude change range and the preset unit distance, and then evaluate the spatial coverage capability of the GNSS-R satellite.

[0139] GNSS-R technology uses existing GNSS-R satellites and does not require active signal reflection. It has the advantages of miniaturization, low cost, and low power consumption. It is very suitable for being carried by small satellites to form constellations and achieve high temporal and spatial resolution observations of the earth. The main difference between GNSS-R technology and traditional remote sensing technology is that the observation points of GNSS-R are strip-shaped, and the sampling points in the strip are relatively dense. The analysis of the temporal and spatial resolution of GNSS-R satellites is very important for the constellation design and detection capability evaluation of GNSS-R. The average revisit time is an important indicator for measuring the temporal and spatial resolution of satellite constellations. It is defined as the average time interval between two observations of the same grid at a certain spatial resolution for constellation observation data. The smaller the average revisit time, the higher the temporal and spatial resolution of the constellation and the better the observation effect. Due to the unique observation system of GNSS-R technology, the calculation of its average revisit time also needs to be specifically considered based on its technical characteristics.

[0140] In order to calculate the average revisit time of GNSS-R satellites, this solution will first divide the earth into grids of a certain size, and then use the mirror reflection point positions in the GNSS-R satellite observation data over a period of time to calculate the number of revisits within each grid point. Since GNSS-R sampling is relatively dense, in order to better reflect the temporal and spatial resolution of the constellation, it is necessary to eliminate continuous observation data within the same grid.

[0141] After obtaining the number of revisits in each grid, the average revisit time needs to be calculated at different latitudes because the coverage of the earth by GNSS-R satellites varies greatly with latitude. The average revisit time is defined as the average time interval between two observations of the same grid at different latitudes.

[0142] Using GNSS-R satellite data composed of 22 polar-orbiting satellites (orbit altitude 520km), calculate the temporal and spatial resolution under the grid size d, d is generally 0.25°, 0.5°, 1°. In this case, d is 0.25 degrees (the average distance of 0.25° on the earth is about 100d=25km).

[0143] Reference Figure 2 , showing the steps of a method for calculating the average revisit time of a GNSS-R satellite provided in an embodiment of the present application Figure 2 ,like Figure 2 As shown, the method specifically includes steps S201 to S206:

[0144] Step S201: determine the grid size based on a preset unit distance.

[0145] In the process of calculating the average revisit time, the GNSS-R system may first determine the grid size based on a preset unit distance.

[0146] Step S202: Initialize the global grid.

[0147] After determining the grid size based on a preset unit distance, the GNSS-R system can initialize the global grid.

[0148] Step S203: Obtain the longitude and latitude of the mirror reflection point corresponding to the GNSS-R satellite.

[0149] During the calculation of the average revisit time, the GNSS-R system can also obtain the longitude and latitude of the GNSS-R mirror reflection point.

[0150] Step S204: Calculate the revisit frequency matrix based on the longitude and latitude of the mirror reflection point corresponding to the GNSS-R satellite.

[0151] After obtaining the longitude and latitude of the GNSS-R mirror reflection point, the GNSS-R system can also calculate a revisit number matrix based on the longitude and latitude of the GNSS-R mirror reflection point.

[0152] Step S205: Calculate the revisit time matrix based on the revisit frequency matrix.

[0153] After calculating the revisit number matrix based on the longitude and latitude of the GNSS-R mirror reflection point, the GNSS-R system can also calculate the revisit time matrix based on the revisit number matrix.

[0154] Step S206: Calculate the average revisit time at different latitudes based on the revisit time matrix.

[0155] After calculating the revisit time matrix based on the revisit number matrix, the GNSS-R system can also calculate the average revisit time at different latitudes based on the revisit time matrix.

[0156] Specifically, the process of calculating the number of revisits of a GNSS-R satellite within k hours is as follows:

[0157] Grid the Earth The latitude of each grid can be expressed as:

[0158] (1)

[0159] in, is the preset unit distance, , .

[0160] The longitude corresponding to each grid can be expressed as:

[0161] (2)

[0162] in, is the preset unit distance, , 360 / d+1.

[0163] Initialize the revisit count matrix , the dimension is , The elements in are initialized to 0.

[0164] For each mirror reflection point in the k-hour GNSS-R data, its latitude and longitude are extracted. The subscript corresponding to the mirror reflection point in the revisit number matrix can be expressed as:

[0165] (3)

[0166] (4)

[0167] The {} symbol indicates rounding.

[0168] In order to avoid repeated calculation of revisit times due to consecutive sampling points of GNSS-R data falling in the same grid, it is necessary to consider when calculating the revisit times matrix that the moving speed of the GNSS-R mirror reflection point on the earth's surface is about 6 km / s, and the average diagonal length of a grid is about d, so there are at most Continuous observation points. Traverse all GNSS-R data and calculate the subscript in the revisit count matrix C for each mirror reflection point , ,when When is 0, or the difference in observation time between two observation data in the same grid is greater than m, the corresponding number of revisits is increased by one, which can be expressed as:

[0169] (5)

[0170] Reference Figure 3 , shows a schematic diagram of the position and grid of a mirror reflection point provided in an embodiment of the present application, such as Figure 3 shown.

[0171] Specifically, the process of calculating the average revisit time at different latitudes is as follows:

[0172] For example, 10 days of GNSS-R satellite observation data can be used to first calculate the revisit time matrix using the revisit number matrix obtained by calculating the revisit number of GNSS-R satellites within k hours. The dimension is the same as that of C, and the unit is hours.

[0173] (6)

[0174] Generally, 10 days of data are used. There is no data equal to 0. If it is 0, then =1, is the time parameter, is the revisit count matrix, , , , 360 / d+1.

[0175] Also traverse the latitude, latitude range , calculate the average revisit time at each latitude. , the average revisit time calculation can be expressed as:

[0176] (7)

[0177] in The unit is hours, is the preset unit distance, is the longitude variation range corresponding to each latitude interval in the target longitude and latitude data, is the revisit time matrix, It is the number of grids contained in the longitude variation range corresponding to each latitude interval in the target longitude and latitude data.

[0178] Reference Figure 4, which shows the average revisit time of the GNSS-R satellite at different latitudes under a 0.25 degree grid provided by the embodiment of the present application, such as Figure 4 shown.

[0179] In summary, when calculating the number of revisits, it is necessary to consider the GNSS-R data sampling interval and eliminate the continuous sampling in the same grid to reflect the actual situation; the definition of average revisit time and analysis at different latitudes.

[0180] Device Embodiment

[0181] like Figure 5 As shown, Figure 5 A logic block diagram of a device for calculating an average revisit time of a GNSS-R satellite provided in an embodiment of the present application is shown, the device comprising:

[0182] The first determination module 1001 is used to determine the earth surface grid map based on a preset unit distance, and determine the longitude and latitude range of each grid; obtain the number of continuous sampling points falling within each grid according to the longitude and latitude range and GNSS-R satellite data, and determine the number of revisits corresponding to the single grid; determine the revisit time matrix based on the number of revisits and time parameters corresponding to the single grid; determine the average revisit time corresponding to each latitude interval based on the revisit time matrix, the number of grids contained in the longitude variation range corresponding to each latitude interval in the target longitude and latitude data, the longitude variation range and the preset unit distance.

[0183] Optionally, the device further comprises:

[0184] The second determining module 1002 is configured to determine a revisit number matrix based on the number of revisits corresponding to the single grid; and determine a revisit time matrix based on the revisit number matrix and a time parameter.

[0185] Optionally, the device further comprises:

[0186] A first obtaining module 1003 is used to map the GNSS-R satellite data into a grid map of the earth's surface according to the longitude and latitude range and the longitude and latitude data corresponding to the mirror reflection point in the GNSS-R satellite data, and obtain the number of continuous sampling points falling within each grid;

[0187] The first determination submodule is used to determine the coordinate data corresponding to each mirror reflection point in the revisit number matrix based on the longitude data and latitude data corresponding to each mirror reflection point; and determine the revisit number corresponding to the single grid based on the coordinate data and the single grid.

[0188] Optionally, the device further comprises:

[0189] The second determination submodule is used to determine the number of mirror reflection points in a single grid based on the diagonal length corresponding to the single grid and the moving speed of the mirror reflection points; when the time threshold between the coordinate data corresponding to two adjacent mirror reflection points is greater than or equal to the preset time threshold, determine that the number of revisits corresponding to the single grid is increased by 1; when the time threshold between the coordinate data corresponding to two adjacent mirror reflection points is less than the preset time threshold, determine that the number of revisits corresponding to the single grid is increased by 0.

[0190] Optionally, the longitude data corresponding to a single grid map in the earth surface grid map and latitude data It is expressed as:

[0191] ;

[0192] ;

[0193] in, is the preset unit distance, , , , 360 / d+1.

[0194] Optionally, the revisit time matrix is ​​expressed as:

[0195] ;

[0196] in, is the time parameter, is the revisit count matrix, , , , 360 / d+1.

[0197] Optionally, the average revisit time corresponding to each latitude interval is expressed as:

[0198] ;

[0199] in, is the preset unit distance, is the longitude variation range corresponding to each latitude interval in the target longitude and latitude data, is the revisit time matrix, It is the number of grids contained in the longitude variation range corresponding to each latitude interval in the target longitude and latitude data.

[0200] As for the device embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiment.

[0201] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0202] The calculation device of the average revisit time of GNSS-R satellites in the embodiment of the present application can be an electronic device, or a component in the electronic device, such as a calculation circuit or chip for the average revisit time of GNSS-R satellites. The electronic device can be a terminal, or it can be other devices other than the terminal. Exemplarily, the electronic device can be a GPU BOX, a mobile phone, a tablet computer, a laptop computer, a PDA, a vehicle-mounted electronic device, a mobile Internet device (Mobile Internet Device, MID), an augmented reality (augmented reality, AR) / virtual reality (virtual reality, VR) device, a robot, a wearable device, an ultra-mobile personal computer (ultra-mobile personal computer, UMPC), a netbook or a personal digital assistant (personal digital assistant, PDA), etc. It can also be a server, a network attached storage (Network Attached Storage, NAS), a personal computer (personal computer, PC), a television (television, TV), a teller machine or a self-service machine, etc., which is not specifically limited in the embodiment of the present application.

[0203] The device for calculating the average revisit time of GNSS-R satellites in the embodiment of the present application may be a device having an operating system. The operating system may be an Android operating system, a Linux operating system, a Windows operating system, or other possible operating systems, which are not specifically limited in the embodiment of the present application.

[0204] The calculation device for the average revisit time of GNSS-R satellites provided in the embodiment of the present application can achieve Figure 1 To avoid repetition, the various processes implemented by the method embodiment are not described here.

[0205] Alternatively, if Figure 6 As shown, an embodiment of the present application further provides an electronic device 1100, including a processor 1101 and a memory 1102, wherein the memory 1102 stores a program or instruction that can be executed on the processor 1101, and when the program or instruction is executed by the processor 1101, each step of the above-mentioned GNSS-R satellite average revisit time calculation method embodiment is implemented, and the same technical effect can be achieved. To avoid repetition, it will not be repeated here.

[0206] In an embodiment of the present application, the memory 1102 may be used to store software programs and various data. The memory 1102 may mainly include a first storage area for storing programs or instructions and a second storage area for storing data, wherein the first storage area may store an operating system, an application program or instructions required for at least one function (such as a sound playback function, an image playback function, etc.), etc. In addition, the memory 1102 may include a volatile memory or a non-volatile memory, or the memory 1102 may include both volatile and non-volatile memories. Among them, the non-volatile memory may be a read-only memory (ROM), a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), an electrically erasable programmable read-only memory (EEPROM), or a flash memory. The volatile memory may be a random access memory (RAM), a static random access memory (SRAM), a dynamic random access memory (DRAM), a synchronous dynamic random access memory (SDRAM), a double data rate synchronous dynamic random access memory (DDRSDRAM), an enhanced synchronous dynamic random access memory (ESDRAM), a synchronous link dynamic random access memory (SLDRAM) and a direct memory bus random access memory (DRRAM). The memory 1102 in the embodiment of the present application includes but is not limited to these and any other suitable types of memory.

[0207] The processor 1101 may include one or more processing units; optionally, the processor 1101 includes an application processor and a modem processor, wherein the application processor mainly processes operations involving an operating system, a user interface, and application programs, and the modem processor mainly processes wireless communication signals, such as a baseband processor. It is understandable that the above-mentioned modem processor may also be incorporated into the processor 1101.

[0208] An embodiment of the present application also provides an electronic device, which includes a processor, a memory, a communication interface and a communication bus, wherein the processor, the memory and the communication interface communicate with each other through the communication bus; the memory is used to store executable instructions, and the executable instructions enable the processor to execute the various processes of the embodiment of the method for calculating the average revisit time of GNSS-R satellites as described above, and can achieve the same technical effect. To avoid repetition, they will not be repeated here.

[0209] An embodiment of the present application also provides a readable storage medium, on which a program or instruction is stored. When the program or instruction is executed by a processor, each process of the above-mentioned GNSS-R satellite average revisit time calculation method embodiment is implemented, and the same technical effect can be achieved. To avoid repetition, it will not be repeated here.

[0210] The processor is the processor in the electronic device described in the above embodiment. The readable storage medium includes a computer readable storage medium, such as a computer read-only memory ROM, a random access memory RAM, a magnetic disk or an optical disk.

[0211] An embodiment of the present application further provides a chip, which includes a processor and a communication interface, wherein the communication interface is coupled to the processor, and the processor is used to run programs or instructions to implement the various processes of the above-mentioned GNSS-R satellite average revisit time calculation method embodiment, and can achieve the same technical effect. To avoid repetition, it will not be repeated here.

[0212] It should be understood that the chip involved in the embodiments of the present application can also be called a system-level chip, a system chip, a chip system or a system-on-chip chip, etc.

[0213] An embodiment of the present application provides a computer program product, which is stored in a storage medium. The program product is executed by at least one processor to implement the various processes of the above-mentioned GNSS-R satellite average revisit time calculation method embodiment, and can achieve the same technical effect. To avoid repetition, it will not be repeated here.

[0214] It should be noted that, in this article, the terms "comprise", "include" or any other variant thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprises one..." does not exclude the presence of other identical elements in the process, method, article or device including the element. In addition, it should be pointed out that the scope of the method and device in the embodiment of the present application is not limited to performing functions in the order shown or discussed, and may also include performing functions in a substantially simultaneous manner or in reverse order according to the functions involved, for example, the described method may be performed in an order different from that described, and various steps may also be added, omitted or combined. In addition, the features described with reference to certain examples may be combined in other examples.

[0215] Through the description of the above implementation methods, those skilled in the art can clearly understand that the above-mentioned embodiment methods can be implemented by means of software plus a necessary general hardware platform, and of course by hardware, but in many cases the former is a better implementation method. Based on such an understanding, the technical solution of the present application, or the part that contributes to the relevant technology, can be embodied in the form of a computer software product, which is stored in a storage medium (such as ROM / RAM, disk, CD), and includes a number of instructions for a terminal (which can be a mobile phone, computer, server, or network device, etc.) to execute the methods described in each embodiment of the present application.

[0216] The embodiments of the present application are described above in conjunction with the accompanying drawings, but the present application is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the guidance of the present application, ordinary technicians in this field can also make many forms without departing from the purpose of the present application and the scope of protection of the claims, all of which are within the protection of the present application.

Claims

1. A method for calculating the average revisit time of a GNSS-R satellite, characterized in that: Applied to a GNSS-R system, the method comprises: Determine a grid map of the earth's surface based on a preset unit distance, and determine the latitude and longitude range of each grid; According to the latitude and longitude range and the GNSS-R satellite data, the number of continuous sampling points falling within each grid is obtained, and the number of revisits corresponding to a single grid is determined; Determine a revisit time matrix based on the number of revisits and time parameters corresponding to the single grid; Determine the average revisit time corresponding to each latitude interval based on the revisit time matrix, the number of grids contained in the longitude variation range corresponding to each latitude interval in the target longitude and latitude data, the longitude variation range, and a preset unit distance; The method of obtaining the number of continuous sampling points falling within each grid according to the latitude and longitude range and the GNSS-R satellite data and determining the number of revisits corresponding to a single grid includes: According to the longitude and latitude range and the longitude and latitude data corresponding to the mirror reflection point in the GNSS-R satellite data, the GNSS-R satellite data is mapped into a grid map on the earth's surface to obtain the number of continuous sampling points falling within each grid; Based on the longitude data and latitude data corresponding to each mirror reflection point, determine the coordinate data corresponding to each mirror reflection point in the revisit number matrix; Based on the coordinate data and the single grid, determining the number of revisits corresponding to the single grid; The revisit time matrix is ​​expressed as: ； in, is the time parameter, is the revisit count matrix, , , , 360 / d+1; The average revisit time corresponding to each latitude interval is expressed as: ； in, is the preset unit distance, is the longitude variation range corresponding to each latitude interval in the target longitude and latitude data, is the revisit time matrix, It is the number of grids contained in the longitude variation range corresponding to each latitude interval in the target longitude and latitude data.

2. The method according to claim 1, characterized in that The determining of the revisit time matrix based on the number of revisit times and the time parameter corresponding to the single grid includes: Determine a revisit number matrix based on the revisit number corresponding to the single grid; A revisit time matrix is ​​determined based on the revisit number matrix and a time parameter.

3. The method according to claim 1, characterized in that The determining, based on the coordinate data and the single grid, the number of revisits corresponding to the single grid comprises: Determine the number of specular reflection points in a single grid based on the diagonal length corresponding to the single grid and the moving speed of the specular reflection points; When the time threshold between the coordinate data corresponding to two adjacent mirror reflection points is greater than or equal to the preset time threshold, the number of revisits corresponding to the single grid is determined to be increased by 1; When the time threshold between the coordinate data corresponding to two adjacent mirror reflection points is less than the preset time threshold, the number of revisit times corresponding to the single grid is determined to be increased by 0.

4. The method according to claim 1, characterized in that Longitude data corresponding to a single grid map in the earth surface grid map and latitude data It is expressed as: ； ； in, is the preset unit distance, , , , 360 / d+1.

5. A device for calculating the average revisit time of a GNSS-R satellite, characterized in that: The device comprises: The first determination module is used to determine the earth surface grid map based on a preset unit distance and determine the longitude and latitude range of each grid; obtain the number of continuous sampling points falling within each grid according to the longitude and latitude range and GNSS-R satellite data, and determine the number of revisits corresponding to a single grid; determine the revisit time matrix based on the number of revisits and time parameters corresponding to the single grid; determine the average revisit time corresponding to each latitude interval based on the revisit time matrix, the number of grids included in the longitude variation range corresponding to each latitude interval in the target longitude and latitude data, the longitude variation range and the preset unit distance; The device is further used to map the GNSS-R satellite data to a grid map on the earth's surface according to the longitude and latitude range and the longitude data and latitude data corresponding to the mirror reflection point in the GNSS-R satellite data, and obtain the number of continuous sampling points falling within each grid; determine the coordinate data corresponding to each mirror reflection point in the revisit number matrix based on the longitude and latitude data corresponding to each mirror reflection point; and determine the number of revisits corresponding to the single grid based on the coordinate data and the single grid; The revisit time matrix is ​​expressed as: ； in, is the time parameter, is the revisit count matrix, , , , 360 / d+1; The average revisit time corresponding to each latitude interval is expressed as: ； in, is the preset unit distance, is the longitude variation range corresponding to each latitude interval in the target longitude and latitude data, is the revisit time matrix, It is the number of grids contained in the longitude variation range corresponding to each latitude interval in the target longitude and latitude data.

6. An electronic device, characterized in that: The electronic device comprises a processor, a memory, a communication interface and a communication bus, and the processor, the memory and the communication interface communicate with each other via the communication bus; The memory is used to store executable instructions, and the executable instructions enable the processor to execute the method for calculating the average revisit time of GNSS-R satellites according to any one of claims 1 to 4.

7. A readable storage medium, characterized in that: The readable storage medium stores a program or instruction, and when the program or instruction is executed by a processor, the method for calculating the average revisit time of GNSS-R satellites according to any one of claims 1 to 4 is implemented.

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