Method and device for constructing global three-dimensional ionosphere

Abstract

The invention provides a global three-dimensional ionosphere construction method and device. The method comprises the following steps: acquiring direct signal data received by a ground-based observation station, direct signal data received by a space-based satellite and ionosphere occultation observation data; a first absolute total electron content is determined based on the total electron content of the pseudo-range observed value and the total electron content of the carrier phase observed value. The total grid electron content is determined based on the electron densities of the plurality of normalized three-dimensional grids, the grid center electron densities, and the path lengths of the rays in the plurality of grids. And optimizing the grid center electron density of the three-dimensional grid based on the absolute total electron content to obtain an optimized three-dimensional grid. And constructing a global three-dimensional ionosphere based on the optimized three-dimensional grid, the total electron content of the pseudo-range observation value, the total electron content of the carrier phase observation value, the absolute total electron content, the relative total electron content and the optimized three-dimensional grid. According to the method provided by the invention, the global three-dimensional ionosphere with better performance can be constructed.

Description

Technical Field

[0001] This application relates to the technical field of data processing, and particularly to a method and device for constructing a global three-dimensional ionosphere. Background Art

[0002] With the continuous development of technology, people's demand for data accuracy is also getting higher and higher. The ionosphere is an important near-Earth space environment, which has effects such as reflection, scattering, refraction, and absorption on radio waves, affecting the performance of systems such as short-wave communication, satellite communication, and navigation and positioning. With the wide application of radio communication technology and satellite navigation technology, the need to obtain a globally uniformly distributed three-dimensional structure of the ionosphere is becoming more and more urgent. The existing technology constructs a global three-dimensional ionosphere through Global Navigation Satellite System (GNSS) ionospheric tomography technology. However, the global three-dimensional ionosphere constructed by GNSS ionospheric tomography technology often has poor usability.

[0003] Therefore, how to construct a global three-dimensional ionosphere with better performance has become a technical problem that needs to be solved urgently by those skilled in the art. Summary of the Invention

[0004] Based on the above problems, this application provides a method and device for constructing a global three-dimensional ionosphere to improve the performance of the constructed global three-dimensional ionosphere.

[0005] This application provides a method for constructing a global three-dimensional ionosphere, and the method includes: Obtain the direct signal data received by ground-based observation stations, the direct signal data received by space-based satellites, and ionospheric occultation observation data, where the categories of the direct signal data received by the ground-based observation stations are pseudorange observations and carrier phase observations; Based on the pseudorange observations, determine the total electron content of pseudorange observations on the pseudorange observations, and based on the carrier phase observations, determine the total electron content of carrier phase observations on the carrier phase observations; Based on the total electron content of pseudorange observations and the total electron content of carrier phase observations, determine the first absolute total electron content; Based on the ionospheric occultation observation data, determine the relative total electron content, and based on the relative total electron content, determine the second absolute total electron content; Divide the outer space where the ionosphere is located into normalized three-dimensional grids according to time resolution, longitude resolution, latitude resolution, ionospheric height range, and ionospheric height levels; Based on the electron density of multiple normalized three-dimensional grids, the electron density at the grid center, and the path length of the ray in multiple grids, determine the total electron content of the grid; Optimizing the grid center electron density of the three-dimensional grid based on the total grid electron content, the first absolute total electron content, and the second absolute total electron content to obtain an optimized three-dimensional grid; Constructing a global three-dimensional ionosphere based on the optimized three-dimensional grid, the total electron content of the pseudorange observations, the total electron content of the carrier phase observations, the first absolute total electron content, the second absolute total electron content, the relative total electron content, and the optimized three-dimensional grid.

[0006] In a possible implementation, determining the total electron content of the pseudorange observations on the pseudorange observations and determining the total electron content of the carrier phase observations on the carrier phase observations includes: The total electron content of the pseudorange observations on the pseudorange observations is determined by the following formula: ; where represents the total electron content of the pseudorange observations on the signal path combined on the pseudorange observations, represents the pseudorange observation, represents the observation epoch identifier, represents the satellite identifier, represents the receiver identifier, represents the square of the frequency of the first carrier signal, represents the square of the frequency of the second carrier signal, represents the first pseudorange observation decoded from the ranging code modulated on the first carrier signal; represents the second pseudorange observation decoded from the ranging code modulated on the second carrier signal, represents the speed of light in vacuum, represents the hardware delay at the satellite end, represents the hardware delay at the receiver end, represents the multipath effect residual between the first carrier signal and the second carrier signal, represents the observation noise residual between the first carrier signal and the second carrier signal; The total electron content of the carrier phase observations on the carrier phase observations is determined by the following formula: ; where represents the total electron content of the carrier phase observations on the signal path combined on the carrier phase observations, represents the carrier phase observation, represents the wavelength of the first carrier signal, represents the phase on the first carrier signal, represents the wavelength of the second carrier signal, represents the phase on the second carrier signal, represents the difference in ambiguity, represents the multipath effect residual between the first carrier signal and the second carrier signal, represents the observation noise residual between the first carrier signal and the second carrier signal;

[0007] The difference in ambiguity is determined by the following formula: ; where, represents the difference in ambiguity, represents the wavelength of the first carrier signal, represents the integer number of ambiguity cycles on the first carrier signal, represents the wavelength of the second carrier signal, represents the integer number of ambiguity cycles on the second carrier signal.

[0008] In a possible implementation, the determining of the absolute total electron content based on the total electron content of the pseudorange observations and the total electron content of the carrier phase observations includes: The absolute total electron content is determined by the following formula: ; where, represents the first absolute total electron content, represents the total electron content of the carrier phase observations on the signal path combined from the carrier phase observations, represents the equivalent ambiguity of the total electron content; The equivalent ambiguity of the total electron content is determined by the following formula: ; where, represents the equivalent ambiguity of the total electron content, N represents the number of terms in the summation in the formula is N, represents the weight, represents the identification of the observation epoch within the arc segment, represents the satellite identification, represents the receiver identification, represents the total electron content of the pseudorange observations on the signal path combined from the pseudorange observations, represents the total electron content of the carrier phase observations on the signal path combined from the carrier phase observations.

[0009] In a possible implementation, determining the relative total electron content based on the ionospheric occultation observation data includes: Performing data processing on the additional phase observation value data in the ionospheric occultation observation data to obtain a smoothed additional phase value; The relative total electron content is determined by the following formula: ; Wherein, represents the relative total electron content on the signal path of the ionospheric occultation observation data, represents the smoothed additional phase value on the first carrier signal, represents the smoothed additional phase value on the second carrier signal, represents the square of the frequency of the first carrier signal, represents the square of the frequency of the second carrier signal.

[0010] In a possible implementation, the grid total electron content is determined by the following formula: ; Wherein, represents the grid total electron content on the ray path in the three-dimensional grid, n represents the number of terms in the summation in the formula as n, represents the relationship coefficient between the electron density of the i-th grid on the ray path in the grid and the electron density at the center of the i-th grid, represents the electron density at the center of the i-th grid, represents the path length of the ray in the i-th grid.

[0011] In a possible implementation, the electron density at the center of the grid of the three-dimensional grid is optimized by the following formula: ; Wherein, represents the iteration number, represents the grid number, represents the number of iterations, represents the electron density at the center of the grid of the grid numbered at the -th iteration, represents the electron density at the center of the grid of the grid numbered at the -th iteration, represents the -th absolute total electron content, represents the observation matrix, represents the -th row of the observation matrix, represents all grids at the The grid center electron density vector of the i-th iteration denotes the dot product with and denotes the relaxation factor denotes the element in the th row and th column of the observation matrix

[0012] The present application also provides a device for constructing a global three-dimensional ionosphere. The device includes the following modules: An acquisition module, configured to acquire direct signal data received by a ground-based observation station, direct signal data received by a space-based satellite, and ionospheric occultation observation data. The categories of the direct signal data received by the ground-based observation station are pseudorange observations and carrier phase observations; A first determination module, configured to determine the total electron content of pseudorange observations based on the pseudorange observations, and determine the total electron content of carrier phase observations based on the carrier phase observations; A second determination module, configured to determine a first absolute total electron content based on the total electron content of pseudorange observations and the total electron content of carrier phase observations; A third determination module, configured to determine a relative total electron content based on the ionospheric occultation observation data, and determine a second absolute total electron content based on the relative total electron content; A three-dimensional grid module, configured to divide the outer space where the ionosphere is located into standardized three-dimensional grids according to time resolution, longitude resolution, latitude resolution, ionospheric height range, and ionospheric height levels; A fourth determination module, configured to determine the total electron content of the grid based on the electron density of multiple standardized three-dimensional grids, the grid center electron density, and the path lengths of the rays in multiple grids; An optimization module, configured to optimize the grid center electron density of the three-dimensional grid based on the total electron content of the grid, the first absolute total electron content, and the second absolute total electron content to obtain an optimized three-dimensional grid; A construction module, configured to construct a global three-dimensional ionosphere based on the optimized three-dimensional grid, the total electron content of pseudorange observations, the total electron content of carrier phase observations, the first absolute total electron content, the second absolute total electron content, the relative total electron content, and the optimized three-dimensional grid.

[0013] The present application also provides an electronic device, which includes a processor and a memory: The memory is configured to store a computer program and transmit the computer program to the processor; The processor is configured to execute the steps of the above-mentioned method for constructing the global three-dimensional ionosphere according to the instructions in the computer program.

[0014] The present application also provides a computer-readable storage medium for storing a computer program, which when executed by an electronic device implements the steps of the above-mentioned method for constructing the global three-dimensional ionosphere.

[0015] Compared with the prior art, the present application has the following beneficial effects: The method provided by the present application comprehensively utilizes GNSS navigation signals and ionospheric occultation observation data, not only effectively compensating for the sparsity of observation data in traditional methods, but also improving the accuracy of electron density inversion through the combination of pseudorange observations and carrier phase observations. Specifically, the calculation of the total electron content based on pseudorange observations and carrier phase observations can not only provide more comprehensive electron density information, but also further improve the accuracy and stability of the model by comparing the relationship between the absolute total electron content and the relative total electron content. In addition, the present application also divides the outer space where the ionosphere is located into normalized three-dimensional grids, and combines information such as the electron density and ray path length of multiple grids to accurately determine the total electron content of the grids. This method can refine the construction process of the ionospheric three-dimensional structure, especially optimizing the electron density at the grid center in the ionospheric three-dimensional model, thus significantly improving the stability and accuracy of the reconstruction algorithm. Most importantly, the optimization process of the present application greatly improves the accuracy and performance of the ionospheric three-dimensional model, enabling a more detailed and reliable global three-dimensional ionospheric structure to be stably obtained. This not only compensates for the limitations of traditional methods, especially having important advantages in issues such as uneven ionospheric distribution and uneven land-sea distribution, but also can significantly improve the performance of systems such as shortwave communication, satellite communication, and navigation and positioning in complex environments. Therefore, the method proposed by the present application demonstrates better performance and broad application prospects in the construction and application of the global three-dimensional ionosphere. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0017] Figure 1 It is a flowchart of a method for constructing a global three-dimensional ionosphere provided by the present application; Figure 2 It is a schematic structural diagram of a device for constructing a global three-dimensional ionosphere provided by the present application. Detailed implementation manners

[0018] To enable those skilled in the art to better understand the solution of this application, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of this application. Obviously, the described embodiments are only a part of the embodiments of this application, rather than all the embodiments. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of this application.

[0019] It can be understood that the method provided by this application can be applied to a processing device, which is a processing device that can obtain navigation signals and ionospheric occultation observation data transmitted by the global navigation satellite system, such as a terminal device or a server that can obtain navigation signals and ionospheric occultation observation data transmitted by the global navigation satellite system. The method provided by this application can be independently executed by a terminal device or a server, or can be applied to a network scenario where a terminal device and a server communicate, and is executed in cooperation with the terminal device and the server. Among them, the terminal device can be a device such as a computer or a mobile phone. The server can be understood as an application server or a Web server. In actual deployment, the server can be an independent server or a cluster server.

[0020] Figure 1 FIG. is a flowchart of a method for constructing a global three-dimensional ionosphere provided by this application. The method includes the following steps: S101: Obtain direct signal data received by a ground-based observatory, direct signal data received by a space-based satellite, and ionospheric occultation observation data.

[0021] The processing device obtains direct signal data received by a ground-based observatory, direct signal data received by a space-based satellite, and ionospheric occultation observation data. The categories of the direct signal data received by the ground-based observatory are pseudorange observations and carrier phase observations.

[0022] The ground-based station receives the navigation signal transmitted by GNSS and obtains two types of observations, pseudorange and carrier phase, therefrom. The pseudorange is the product of the signal propagation time calculated from the ranging code modulated in the navigation signal and the speed of light in vacuum. The carrier phase is the phase value accumulated from the initial phase at a certain moment to the signal reception moment.

[0023] S102: Determine the total electron content of the pseudorange observation value based on the pseudorange observation value, and determine the total electron content of the carrier phase observation value based on the carrier phase observation value.

[0024] The processing device determines the total electron content of the pseudorange observations based on the pseudorange observations, and determines the total electron content of the carrier phase observations based on the carrier phase observations.

[0025] In a possible implementation, the processing device can respectively obtain the corresponding total electron content (Total Electron Content, TEC) by linearly combining the pseudorange observations and the carrier phase observations according to the basic GNSS positioning observation equation.

[0026] The total electron content of the pseudorange observations is determined by the following formula: ; Where, represents the total electron content of the pseudorange observations on the signal path combined from the pseudorange observations, represents the pseudorange observation, represents the observation epoch identifier, represents the satellite identifier, represents the receiver identifier, represents the square of the frequency of the first carrier signal, represents the square of the frequency of the second carrier signal, represents the first pseudorange observation decoded from the ranging code modulated on the first carrier signal; represents the second pseudorange observation decoded from the ranging code modulated on the second carrier signal, represents the speed of light in vacuum, represents the hardware delay at the satellite end, represents the hardware delay at the receiver end, represents the multipath effect residual between the first carrier signal and the second carrier signal, represents the observation noise residual between the first carrier signal and the second carrier signal.

[0027] The total electron content of the carrier phase observations is determined by the following formula: ; Where, represents the total electron content of the carrier phase observations on the signal path combined from the carrier phase observations, represents the carrier phase observation, represents the wavelength of the first carrier signal, represents the phase on the first carrier signal, represents the wavelength of the second carrier signal, represents the phase on the second carrier signal, represents the ambiguity difference, represents the multipath effect residual between the first carrier signal and the second carrier signal, represents the observation noise residual between the first carrier signal and the second carrier signal.

[0028] The ambiguity difference is determined by the following formula: ; where, represents the ambiguity difference, represents the wavelength of the first carrier signal, represents the integer number of ambiguity cycles on the first carrier signal, represents the wavelength of the second carrier signal, represents the integer number of ambiguity cycles on the second carrier signal.

[0029] S103: Determine the first absolute total electron content based on the total electron content of the pseudorange observation and the total electron content of the carrier phase observation.

[0030] The processing device can determine the first absolute total electron content based on the total electron content of the pseudorange observation and the total electron content of the carrier phase observation.

[0031] In a possible implementation, the first absolute total electron content is determined by the following formula: ; where, represents the first absolute total electron content, represents the total electron content of the carrier phase observation on the signal path combined from the carrier phase observations, represents the equivalent ambiguity of the total electron content; The equivalent ambiguity of the total electron content is determined by the following formula: ; where, represents the equivalent ambiguity of the total electron content, N represents the number of terms in the summation formula is N, represents the weight, represents the identification of the observation epoch within the arc segment, represents the satellite identification, represents the receiver identification, represents the total electron content of the pseudorange observation on the signal path combined from the pseudorange observations, represents the total electron content of the carrier phase observation on the signal path combined from the carrier phase observations.

[0032] S104: Determine the relative total electron content based on the ionospheric occultation observation data, and determine the second absolute total electron content based on the relative total electron content.

[0033] The processing device determines the relative total electron content based on the ionospheric occultation observation data, and determines the second absolute total electron content based on the relative total electron content.

[0034] The ionospheric occultation observation data provides additional phase observation data obtained by a low-earth orbit satellite receiving GNSS navigation signals during the occultation phase. After cycle slip detection and repair, a sliding window smoothing filter is used to suppress high-frequency noise to obtain a smoothed additional phase, and then the relative total electron content can be calculated.

[0035] In a possible implementation, the processing device can perform data processing on the additional phase observation value data in the ionospheric occultation observation data to obtain a smoothed additional phase value. The data processing can include cycle slip detection and repair, and sliding window smoothing filtering.

[0036] The relative total electron content is determined by the following formula: ; where, represents the relative total electron content on the signal path of the ionospheric occultation observation data, represents the smoothed additional phase value on the first carrier signal, represents the smoothed additional phase value on the second carrier signal, represents the square of the frequency of the first carrier signal, represents the square of the frequency of the second carrier signal.

[0037] To obtain the absolute TEC, it is necessary to correct the TEC using the auxiliary observation data on the non-occultation side. Since the duration of ionospheric occultation is generally from a few minutes to more than ten minutes, the ionospheric changes are usually small. At the same time, due to the large difference in the orbital heights between GNSS satellites and occultation satellites, the change of the occultation plane is usually small during the occultation process. Therefore, the relative TEC observed by the occultation satellite on the non-occultation side often has an approximately overlapping signal path with the relative TEC observed on the occultation side. Therefore, the corrected absolute TEC can be obtained through simple subtraction calculation. Considering the observation interval of the receiver, in order to perform the correction more strictly, it is necessary to interpolate the relative TEC observed on the non-occultation side to the same collision height as the relative TEC observed on the occultation side.

[0038] S105: Divide the outer space where the ionosphere is located into a normalized three-dimensional grid according to the time resolution, longitude resolution, latitude resolution, ionospheric height range, and ionospheric height hierarchy.

[0039] The processing device divides the outer space where the ionosphere is located into a normalized three-dimensional grid according to the time resolution, longitude resolution, latitude resolution, ionospheric height range, and ionospheric height levels.

[0040] In a possible implementation, the processing device divides the outer space where the ionosphere is located into a normalized three-dimensional grid according to the time resolution, longitude and latitude resolutions, ionospheric height range, and height levels, etc. To characterize the electron density distribution in the ionosphere, it is combined with a three-dimensional empirical model of the ionosphere, such as the International Reference Ionosphere (IRI) model, the NeQuick model, etc., so as to calculate the electron density field of the three-dimensional empirical model of the ionosphere and use it as the initial field for subsequent optimization.

[0041] S106: Determine the total electron content of the grid based on the electron density of multiple normalized three-dimensional grids, the electron density at the grid center, and the path length of the ray in multiple grids.

[0042] The processing device determines the total electron content of the grid based on the electron density of multiple normalized three-dimensional grids, the electron density at the grid center, and the path length of the ray in multiple grids.

[0043] Although the navigation satellite signals in a specific frequency band are continuously refracted vertically in the ionosphere, generally the bending angle of the signal path is very small, even during magnetic storms. Therefore, the radio wave path can be approximated as a ray, and thus a simplified model of the radio wave propagation in the ionosphere is constructed, that is, the ray tracing technique. The ray tracing technique is used in the normalized three-dimensional grid, so that the ray is decomposed into the sum of the paths belonging to each grid. For the path in the grid, its electron density distribution is determined by the electron density at the grid center and its spatial relationship with the grid center. Therefore, the TEC of the ray can be discretized into the sum of the path TECs of each grid passed by the ray, and further the TEC of the ray can be discretized into a linear equation of the central electron densities of each grid.

[0044] In a possible implementation, the total electron content of the grid is determined by the following formula: ; where represents the total electron content of the grid on the ray path in the three-dimensional grid, n represents the number of terms in the summation in the formula is n, represents the relationship coefficient between the electron density of the i-th grid on the ray path in the grid and the electron density at the center of the i-th grid, represents the electron density at the center of the i-th grid, represents the path length of the ray in the i-th grid.

[0045] In the process of constructing a linear equation system of TEC on the ray path and the electron density at the grid center, for the sake of simplifying the calculation, it is generally considered that the electron density on the path within the grid is equal to the electron density at the grid center. The constructed linear equation system is as follows: ; Wherein, represents the observation matrix, represents the vector of electron densities at the centers of all grids, represents the vector of all observed TECs.

[0046] S107: Optimize the electron density at the grid center of the three-dimensional grid based on the total electron content of the grid, the first absolute total electron content, and the second absolute total electron content to obtain an optimized three-dimensional grid.

[0047] The processing device optimizes the electron density at the grid center of the three-dimensional grid based on the total electron content of the grid, the first absolute total electron content, and the second absolute total electron content to obtain an optimized three-dimensional grid.

[0048] In a possible implementation, the electron density at the grid center of the three-dimensional grid is optimized through the following formula: ; Wherein, represents the iteration number, represents the grid number, represents the number of iterations, represents the electron density at the grid center of the grid numbered in the th iteration, represents the electron density at the grid center of the grid numbered in the th iteration, represents the th absolute total electron content, represents the observation matrix, represents the th row of the observation matrix, represents the vector of electron densities at the grid centers of all grids in the th iteration, represents the dot product of and represents the relaxation factor, represents the element in the th row and th column of the observation matrix.

[0049] For each ray, by calculating the ratio of the actually observed TEC to the TEC calculated by the current grid, and then splitting and distributing this ratio to each grid according to the length percentage index of the ray in each grid, each grid is corrected one by one. The grids are iteratively corrected according to each actually observed TEC in a loop until the difference between two consecutive iterations of all grids is less than the given tolerance.

[0050] Since the initial field of electron density is calculated using the three-dimensional empirical model of the ionosphere and the TEC of ionospheric occultation observations is incorporated into the reconstruction calculation, the situation that there are no rays passing through the bottom grids far from the stations caused by the sparsity of ground-based GNSS observation stations and the uneven distribution of land and sea is greatly improved, and the reconstruction calculation converges through iteration.

[0051] S108: Construct a global three-dimensional ionosphere based on the optimized three-dimensional grid, the total electron content of pseudorange observations, the total electron content of carrier phase observations, the absolute total electron content, the relative total electron content, and the optimized three-dimensional grid.

[0052] The processing device can construct a global three-dimensional ionosphere based on the optimized three-dimensional grid, the total electron content of pseudorange observations, the total electron content of carrier phase observations, the absolute total electron content, the relative total electron content, and the optimized three-dimensional grid.

[0053] In a possible implementation, the processing device can obtain a refined three-dimensional reconstruction grid model of the ionosphere through multiplicative algebraic reconstruction calculation. Further, the peak height and peak density of the F2 layer can be searched in the three-dimensional reconstruction grid, and its grid model can be output; the path integral can also be performed in the vertical direction of the three-dimensional reconstruction grid to obtain the total electron content in the vertical direction, that is, VTEC, and the VTEC grid model can be output.

[0054] The method provided by this application comprehensively utilizes GNSS navigation signals and ionospheric occultation observation data, not only effectively making up for the sparsity of observation data in traditional methods, but also improving the accuracy of electron density inversion through the combination of pseudorange observation values and carrier phase observation values. Specifically, based on the calculation of the total electron content using pseudorange observation values and carrier phase observation values, it can not only provide more comprehensive electron density information, but also further improve the accuracy and stability of the model by comparing the relationship between the absolute total electron content and the relative total electron content. In addition, this application also divides the outer space where the ionosphere is located into normalized three-dimensional grids, and combines information such as the electron density and ray path length of multiple grids to accurately determine the total electron content of the grids. This method can refine the construction process of the three-dimensional ionospheric structure, especially optimizing the electron density at the grid center in the three-dimensional ionospheric model, thus significantly improving the stability and accuracy of the reconstruction algorithm. Most importantly, the optimization process of this application greatly improves the accuracy and performance of the three-dimensional ionospheric model, enabling it to stably obtain a more detailed and reliable global three-dimensional ionospheric structure. This not only makes up for the limitations of traditional methods, especially having important advantages in issues such as uneven ionospheric distribution and uneven land-sea distribution, but also can significantly improve the performance of systems such as shortwave communication, satellite communication, and navigation positioning in complex environments. Therefore, the method proposed in this application demonstrates more excellent performance and broad application prospects in the construction and application of the global three-dimensional ionosphere.

[0055] Next, an example is used for illustration. The processing device collects ionospheric occultation detection data of 15 satellites of the first type (about 500 ionospheric occultation events per satellite per day) and 3 satellites of the second type (about 500 ionospheric occultation events per satellite per day) in January 2024; collects 200 station observation files, corresponding station coordinate files, and precise ephemeris of GNSS globally in January 2024.

[0056] The processing device processes the occultation detection signal, obtains the smoothed additional phase data through cycle slip detection and repair, and sliding window smoothing, performs dual-frequency combination calculation on it to obtain the relative ionospheric TEC on different paths, then performs height reordering on the relative TEC on both sides of the maximum collision height, and finally interpolates the relative TEC on the non-occultation side to the same collision height as the relative TEC on the occultation side through cubic spline interpolation, and differentiates to obtain the absolute TEC.

[0057] The processing device processes the observation files of the stations, combines the pseudorange P1 and P2 and the differential code bias to obtain a relatively low-precision absolute TEC, combines the carrier phases L1 and L2 to obtain a relatively higher-precision relative TEC, estimates the ambiguity magnitude within the arc segment, and thus resolves the high-precision absolute TEC.

[0058] The processing device sets the range to global, the longitude and latitude resolution to 2.5°×5°, the altitude to 60 km to 2000 km, and divides it into 37 layers to set up a three-dimensional regular grid, and divides the IRI model according to the three-dimensional grid to obtain the initial electron density field.

[0059] The processing device maps each corrected total electron content and its corresponding low-earth orbit satellite position or station position, and navigation star position into the electron density field by using the ionospheric ray tracing technology.

[0060] The processing device makes full use of multi-satellite ionospheric sounding data, and uses the multiplicative algebraic reconstruction algorithm to refine the reconstruction of the ionosphere, and obtains a refined global ionospheric three-dimensional reconstruction grid model under the grid setting.

[0061] The processing device searches for the peak density of the F2 layer in the vertical direction of the refined global ionospheric three-dimensional reconstruction grid model, obtains the corresponding peak height hmF2 and critical frequency foF2, obtains the global ionospheric hmF2 grid model and the global ionospheric foF2 grid model, and integrates the refined global ionospheric three-dimensional reconstruction grid model in the vertical direction to obtain the global vertical total electron content grid model.

[0062] This application also provides a Figure 2 structural schematic diagram of the construction device of the global three-dimensional ionosphere as shown, and the construction device 200 of the global three-dimensional ionosphere includes: An acquisition module 201, configured to acquire the direct signal data received by the ground-based observation station, the direct signal data received by the space-based satellite, and the ionospheric occultation observation data, and the categories of the direct signal data received by the ground-based observation station are pseudorange observations and carrier phase observations; A first determination module 202, configured to determine the total electron content of the pseudorange observations based on the pseudorange observations, and determine the total electron content of the carrier phase observations based on the carrier phase observations; A second determination module 203, configured to determine the first absolute total electron content based on the total electron content of the pseudorange observations and the total electron content of the carrier phase observations; A third determination module 204, configured to determine the relative total electron content based on the ionospheric occultation observation data, and determine the second absolute total electron content based on the relative total electron content; A three-dimensional grid module 205, configured to divide the outer space where the ionosphere is located into a standardized three-dimensional grid according to the time resolution, longitude resolution, latitude resolution, ionospheric height range, and ionospheric height level; A fourth determination module 206, configured to determine the total electron content of the grid based on the electron density of multiple normalized three-dimensional grids, the electron density at the grid center, and the path length of the ray in multiple grids; An optimization module 207, configured to optimize the electron density at the grid center of the three-dimensional grid based on the total electron content of the grid, the first absolute total electron content, and the second absolute total electron content to obtain an optimized three-dimensional grid; A construction module 208, configured to construct a global three-dimensional ionosphere based on the optimized three-dimensional grid, the total electron content of the pseudorange observation value, the total electron content of the carrier phase observation value, the first absolute total electron content, the second absolute total electron content, the relative total electron content, and the optimized three-dimensional grid.

[0063] The device provided in this application comprehensively utilizes GNSS navigation signals and ionospheric occultation observation data, not only effectively making up for the sparsity of observation data in traditional methods, but also improving the accuracy of electron density inversion through the combination of pseudorange observation values and carrier phase observation values. Specifically, the calculation of the total electron content based on pseudorange observation values and carrier phase observation values can not only provide more comprehensive electron density information, but also further improve the accuracy and stability of the model by comparing the relationship between the absolute total electron content and the relative total electron content. In addition, this application also divides the outer space where the ionosphere is located into normalized three-dimensional grids, and combines information such as the electron density and ray path length of multiple grids to accurately determine the total electron content of the grid. This method can refine the construction process of the three-dimensional ionospheric structure, especially optimizing the electron density at the grid center in the three-dimensional ionospheric model, thereby significantly improving the stability and accuracy of the reconstruction algorithm. The most crucial point is that the optimization process of this application greatly improves the accuracy and performance of the three-dimensional ionospheric model, and can stably obtain a more detailed and reliable global three-dimensional ionospheric structure. This not only makes up for the limitations of traditional methods, especially having important advantages in issues such as uneven ionospheric distribution and uneven land-sea distribution, but also can significantly improve the performance of systems such as short-wave communication, satellite communication, and navigation and positioning in complex environments. Therefore, the method proposed in this application demonstrates more excellent performance and broad application prospects in the construction and application of the global three-dimensional ionosphere.

[0064] The embodiment of this application also provides a device for constructing a global three-dimensional ionosphere. The device includes a memory and a processor. The memory is used to store instructions or codes, and the processor is used to execute the instructions or codes so that the device executes the steps of the construction method based on the global three-dimensional ionosphere according to any embodiment of this application.

[0065] In practical applications, the computer-readable storage medium may adopt any combination of one or more computer-readable media. The computer-readable medium may be a computer-readable signal medium or a computer-readable storage medium.

[0066] The computer-readable storage medium may be, for example, but not limited to, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any combination of the above. More specific examples (a non-exhaustive list) of the computer-readable storage medium include: an electrical connection having one or more wires, a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the above. In this embodiment, the computer-readable storage medium may be any tangible medium that contains or stores a program that can be used by or in conjunction with an instruction execution system, apparatus, or device.

[0067] The computer-readable signal medium may include a data signal propagated in a baseband or as part of a carrier wave, which carries the computer-readable program code. Such a propagated data signal may take various forms, including but not limited to electromagnetic signals, optical signals, or any suitable combination of the above. The computer-readable signal medium may also be any computer-readable medium other than the computer-readable storage medium, which can send, propagate, or transmit a program for use by or in conjunction with an instruction execution system, apparatus, or device.

[0068] The program code contained on the computer-readable medium may be transmitted by any appropriate medium, including but not limited to wireless, wire, optical fiber, RF, etc., or any suitable combination of the above.

[0069] The computer program code for performing the operations of the present invention may be written in one or more programming languages or combinations thereof. The programming languages include object-oriented programming languages such as Java, Smalltalk, C++, and also include conventional procedural programming languages such as the "C" language or similar programming languages. The program code may be executed entirely on the user's computer, partially on the user's computer, executed as a stand-alone software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In the case of a remote computer, the remote computer may be connected to the user's computer through any type of network, including a local area network (LAN) or a wide area network (WAN), or may be connected to an external computer (for example, by using an Internet service provider to connect through the Internet).

[0070] It should be noted that the various embodiments in this specification are described in a progressive manner. For the same or similar parts among the embodiments, reference can be made to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the device embodiments, since they are basically similar to the method embodiments, they are described relatively simply. For the relevant parts, reference can be made to the corresponding descriptions in the method embodiments. The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separated, and the components referred to as units may or may not be physical units, that is, they may be located in one place or distributed to multiple network units. Some or all of the modules can be selected according to actual needs to achieve the purpose of the solution of this embodiment. A person of ordinary skill in the art can understand and implement it without creative work.

[0071] As described above, this is only a specific implementation manner of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed in the present application should be covered by the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A method for constructing a global three-dimensional ionosphere, characterized in that: include: Acquire direct signal data received by ground-based observation stations, direct signal data received by space-based satellites, and ionospheric occultation observation data, wherein the direct signal data received by the ground-based observation stations are of pseudorange observation values ​​and carrier phase observation values; Determining a total electron content of pseudorange observations on the pseudorange observations based on the pseudorange observations, and determining a total electron content of carrier phase observations on the carrier phase observations based on the carrier phase observations; Determine a first absolute total electron content based on the total electron content of the pseudorange observation value and the total electron content of the carrier phase observation value; Determine a relative total electron content based on the ionospheric occultation observation data, and determine a second absolute total electron content based on the relative total electron content; The outer space where the ionosphere is located is divided into a standardized three-dimensional grid according to time resolution, longitude resolution, latitude resolution, ionosphere height range and ionosphere height level; Determine the total electron content of the grid based on the electron density of the plurality of normalized three-dimensional grids, the electron density at the center of the grid, and the path length of the ray in the plurality of grids; Optimizing the grid center electron density of the three-dimensional grid based on the grid total electron content, the first absolute total electron content, and the second absolute total electron content to obtain an optimized three-dimensional grid; A global three-dimensional ionosphere is constructed based on the optimized three-dimensional grid, the total electron content of the pseudorange observations, the total electron content of the carrier phase observations, the first absolute total electron content, the second absolute total electron content, the relative total electron content and the optimized three-dimensional grid.

2. The method according to claim 1, characterized in that The determining of the total electron content of the pseudorange observation value on the pseudorange observation value based on the pseudorange observation value, and the determining of the total electron content of the carrier phase observation value on the carrier phase observation value based on the carrier phase observation value comprises: The total electron content of the pseudorange observations on the pseudorange observations is determined by the following formula: ； in, represents the total electron content of the pseudorange observations on the signal path obtained by combining the pseudorange observations, represents the pseudorange observation value, Represents the observation epoch identifier, Indicates the satellite ID. Indicates the receiver identification, represents the square of the frequency of the first carrier signal, represents the square of the frequency of the second carrier signal, represents a first pseudorange observation value obtained by decoding a ranging code modulated on a first carrier signal; represents a second pseudorange observation value obtained by decoding the ranging code modulated on the second carrier signal, is the speed of light in vacuum, Indicates the hardware delay of the satellite end. Indicates the hardware delay at the receiver end, represents the multipath effect residual between the first carrier signal and the second carrier signal, represents the observed noise residual between the first carrier signal and the second carrier signal; The total electron content of the carrier phase observations on the carrier phase observations is determined by the following formula: ； in, represents the total electron content of the carrier phase observations on the signal path combined on the carrier phase observations, represents the carrier phase observation value, represents the wavelength of the first carrier signal, represents the phase on the first carrier signal, represents the wavelength of the second carrier signal, represents the phase of the second carrier signal, represents the difference in blurriness, represents the multipath effect residual between the first carrier signal and the second carrier signal, represents the observed noise residual between the first carrier signal and the second carrier signal; The difference in ambiguity is determined by the following formula: ； in, represents the difference in blurriness, represents the wavelength of the first carrier signal, represents the integer number of ambiguities on the first carrier signal, represents the wavelength of the second carrier signal, Represents the integer number of ambiguities on the second carrier signal.

3. The method according to claim 2, characterized in that Determining the first absolute total electron content based on the total electron content of the pseudorange observation value and the total electron content of the carrier phase observation value comprises: The first absolute total electron content is determined by the following formula: ； in, represents the first absolute total electron content, represents the total electron content of the carrier phase observations on the signal path combined on the carrier phase observations, represents the equivalent ambiguity of the total electron content; The equivalent ambiguity of the total electron content is determined by the following formula: ； in, represents the equivalent ambiguity of the total electron content, N represents the number of terms to be summed in the formula, represents the weight, Indicates the observation epoch identifier within the arc segment. Indicates the satellite ID. Indicates the receiver identification, represents the total electron content of the pseudorange observations on the signal path obtained by combining the pseudorange observations, Represents the total electron content of the carrier phase observations on the signal path combined on the carrier phase observations.

4. The method according to claim 1, characterized in that Determining the relative total electron content based on the ionospheric occultation observation data comprises: Processing the additional phase observation value data in the ionospheric occultation observation data to obtain a smoothed additional phase value; The relative total electron content is determined by the following formula: ； in, represents the relative total electron content on the signal path of ionospheric occultation observation data, represents the smoothed additional phase value on the first carrier signal, represents the smoothed additional phase value on the second carrier signal, represents the square of the frequency of the first carrier signal, Represents the square of the frequency of the second carrier signal.

5. The method according to claim 1, characterized in that The total electron content of the grid is determined by the following formula: ； in, represents the total electron content of the grid on the ray path in the three-dimensional grid, n represents the number of terms to be summed in the formula, represents the relationship coefficient between the electron density of the ith grid on the ray path in the grid and the electron density at the center of the ith grid, represents the electron density at the center of the ith grid, Represents the path length of the ray in the i-th grid.

6. The method according to claim 1, characterized in that The grid center electron density of the three-dimensional grid is optimized by the following formula: ； in, Represents the iteration number, Indicates the grid number, represents the number of iterations, Indicates the number Grid The grid center electron density of the iteration, Indicates the number Grid The grid center electron density of the iteration, Indicates The absolute total electron content, represents the observation matrix, The observation matrix is OK, Indicates that all grids in The grid center electron density vector of the iteration, express and The number product of represents the relaxation factor, Indicates the observation matrix Line Elements of a column.

7. A device for constructing a global three-dimensional ionosphere, characterized in that: include: An acquisition module is used to acquire direct signal data received by ground-based observation stations, direct signal data received by space-based satellites, and ionospheric occultation observation data, wherein the categories of the direct signal data received by the ground-based observation stations are pseudorange observation values ​​and carrier phase observation values; A first determination module is used to determine the total electron content of the pseudorange observation value on the pseudorange observation value based on the pseudorange observation value, and to determine the total electron content of the carrier phase observation value on the carrier phase observation value based on the carrier phase observation value; A second determination module, configured to determine a first absolute total electron content based on the total electron content of the pseudorange observation value and the total electron content of the carrier phase observation value; A third determination module is used to determine a relative total electron content based on the ionospheric occultation observation data, and determine a second absolute total electron content based on the relative total electron content; A three-dimensional grid module is used to divide the outer space where the ionosphere is located into a standardized three-dimensional grid according to time resolution, longitude resolution, latitude resolution, ionosphere height range and ionosphere height level; A fourth determination module, for determining a total electron content of a grid based on the electron density of a plurality of normalized three-dimensional grids, the electron density at the center of the grid, and the path length of the ray in the plurality of grids; An optimization module, configured to optimize the grid center electron density of the three-dimensional grid based on the grid total electron content, the first absolute total electron content, and the second absolute total electron content to obtain an optimized three-dimensional grid; A construction module is used to construct a global three-dimensional ionosphere based on the optimized three-dimensional grid, the total electron content of the pseudorange observations, the total electron content of the carrier phase observations, the first absolute total electron content, the second absolute total electron content, the relative total electron content and the optimized three-dimensional grid.

8. An electronic device, characterized in that: comprising a memory and a processor, wherein: The memory is used to store the computer program; The processor is used to execute the computer program to implement the method for constructing the global three-dimensional ionosphere as described in any one of claims 1-6.

9. A computer-readable storage medium, characterized in that: Used to store a computer program, wherein when the computer program is executed by a processor, the method for constructing a global three-dimensional ionosphere as described in any one of claims 1 to 6 is implemented.

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