Method and device for eliminating abnormal value in VTEC, equipment and medium

Abstract

The invention discloses a method, device, equipment and medium for eliminating abnormal values in VTEC, and the method comprises the steps: generating a global ionosphere grid model based on a global ionosphere VTEC model which is established based on ionosphere observation information; determining abnormal grid points in the global ionospheric grid model; generating a statistical value of the abnormal grid point based on the peripheral data of the abnormal grid point; and eliminating the abnormal grid points in the global ionospheric grid model based on the statistical values of the abnormal grid points. By adopting the technical scheme of the invention, the problem that the compensation effect depends on the size of the accumulated quantity of the introduced measured data and whether the weight precision of the selected empirical model is appropriate or not when the ionized layer VTEC is an abnormal value in the traditional technology is solved.

Description

Technical Field

[0001] The present application relates to, but is not limited to, the field of geophysics or atmospheric physics, and in particular to a method, device, equipment and medium for eliminating abnormal values ​​in vertical total electron content (VTEC). Background Art

[0002] The ionosphere refers to the entire space between 60 kilometers (km) above the earth's surface and the top of the magnetosphere. There are a large number of free electrons and ions in it, which can change the propagation speed of radio waves, refract, reflect and scatter, rotate the polarization plane and be absorbed to varying degrees, and cause changes in the propagation speed and direction of electromagnetic wave signals from Global Navigation Satellite System (GNSS) satellites, that is, ionospheric delay. The physical characteristics of the ionosphere are complex and changeable, and it is one of the most important sources of error in satellite navigation and positioning.

[0003] The use of spherical harmonics to establish a global ionosphere model is the most commonly used method for global ionosphere inversion. However, the use of spherical harmonics to establish a global ionosphere model will result in some grid points being abnormal values ​​(negative or maximum values), especially in areas where there are no observation stations. Traditional technologies use empirical models to compensate for the abnormal ionospheric VTEC problem, but they rely on a large amount of measured data and the selection of empirical models with appropriate weights. That is, the compensation effect depends on the amount of measured data introduced and the accuracy of the selected empirical model weights. Summary of the invention

[0004] In view of this, embodiments of the present application provide a method, apparatus, device and medium for eliminating abnormal values ​​in VTEC.

[0005] The technical solution of the embodiment of the present application is implemented as follows:

[0006] In a first aspect, an embodiment of the present application provides a method for eliminating outliers in VTEC, the method comprising: generating a global ionospheric grid model based on a global ionospheric VTEC model, wherein the VTEC model is established based on ionospheric observation information; determining abnormal grid points in the global ionospheric grid model; generating statistical values ​​of the abnormal grid points based on surrounding data of the abnormal grid points; and eliminating abnormal grid points in the global ionospheric grid model based on the statistical values ​​of the abnormal grid points.

[0007] In a second aspect, an embodiment of the present application provides a device for eliminating abnormal values ​​in VTEC, the device comprising: a first generating module, used to generate a global ionospheric grid model based on a global ionospheric VTEC model, wherein the VTEC model is established based on ionospheric observation information; a determining module, used to determine abnormal grid points in the global ionospheric grid model; a second generating module, used to generate statistical values ​​of the abnormal grid points based on surrounding data of the abnormal grid points; and an eliminating module, used to eliminate abnormal grid points in the global ionospheric grid model based on the statistical values ​​of the abnormal grid points.

[0008] In a third aspect, an embodiment of the present application provides a device for eliminating abnormal values ​​in VTEC, comprising a processor and a memory, wherein the memory is used to store a computer program; the processor is used to execute the computer program stored in the memory to implement the method for eliminating abnormal values ​​in VTEC.

[0009] In a fourth aspect, an embodiment of the present application provides a computer-readable storage medium, wherein a computer program is stored in the computer-readable storage medium. When the computer program is executed by a processor, the method for eliminating abnormal values ​​in VTEC is implemented.

[0010] In this embodiment, firstly, a global ionospheric VTEC model is established based on ionospheric observation information, and then a global ionospheric grid model is generated based on the global ionospheric VTEC model, so as to facilitate reading the VTEC data value of each grid point in the global ionospheric grid model as a basis for subsequent judgment of abnormal grid points; secondly, the abnormal grid points in the global ionospheric grid model are determined as a prerequisite for subsequent acquisition of peripheral data of the abnormal grid points; thirdly, based on the peripheral data of the abnormal grid points, statistical values ​​of the abnormal grid points are generated, where the statistical values ​​of the abnormal grid points are generated according to the VTEC data values ​​of the peripheral grid points of the abnormal grid points, where the statistical values ​​of the abnormal grid points are used as a basis for subsequent recalculation of the spherical harmonic coefficients of the VTEC model; finally, based on the statistical values ​​of the abnormal grid points, the abnormal grid points in the global ionospheric grid model are eliminated, where the spherical harmonic coefficients of the VTEC model are cyclically iterated and solved by the statistical values ​​of the abnormal grid points until no abnormal values ​​of VTEC appear at all grid points in the global ionospheric grid model. By adopting the technical solution of the present application, it is only necessary to rely on the original data and parameter estimation method in the VTEC model, without introducing a large amount of external measured data, and there is no need to select an empirical model. This solves the problem that when the traditional technology is used to compensate for the abnormal value of ionospheric VTEC, the compensation effect depends on the amount of accumulated measured data introduced and whether the weight accuracy of the selected empirical model is appropriate.

[0011] It should be understood that the above general description and the following detailed description are merely exemplary and explanatory, and are not intended to limit the technical solutions of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] In the accompanying drawings (which are not necessarily drawn to scale), like reference numerals may describe similar components in different views. Like reference numerals with different letter suffixes may represent different examples of similar components. The accompanying drawings generally illustrate various embodiments discussed herein by way of example and not limitation.

[0013] Figure 1 A schematic diagram of a method for eliminating abnormal values ​​in VTEC provided in an embodiment of the present application;

[0014] Figure 2 A schematic diagram of an implementation flow of implementing step S102 provided in an embodiment of the present application;

[0015] Figure 3 A schematic diagram of the composition structure of a device for eliminating abnormal values ​​in VTEC provided in an embodiment of the present application Figure 1 ;

[0016] Figure 4 A schematic diagram of the composition structure of a device for eliminating abnormal values ​​in VTEC provided in an embodiment of the present application Figure 2 ;

[0017] Figure 5 A schematic diagram of a hardware entity of a device for eliminating abnormal values ​​in VTEC provided in an embodiment of the present application. DETAILED DESCRIPTION

[0018] In order to make the purpose, technical solutions and advantages of the present application clearer, the following figure will further describe the present application in detail in conjunction with the accompanying drawings. The described embodiments should not be regarded as limiting the present application. All other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present application.

[0019] The exemplary embodiments disclosed in the present application will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present application are shown in the accompanying drawings, it should be understood that the present application can be implemented in various forms and should not be limited by the specific embodiments described herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present application and to fully convey the scope disclosed in the present application to those skilled in the art.

[0020] In the following description, a large number of specific details are given to provide a more thorough understanding of the present application. However, it is obvious to those skilled in the art that the present application can be implemented without one or more of these details. In other examples, in order to avoid confusion with the present application, some technical features known in the art are not described; that is, all features of the actual embodiments are not described here, and well-known functions and structures are not described in detail.

[0021] In the drawings, the sizes of layers, regions, elements and their relative sizes may be exaggerated for clarity. Like reference numerals denote like elements throughout.

[0022] It should be understood that when an element or layer is referred to as "on ...", "adjacent to ...", "connected to" or "coupled to" other elements or layers, it can be directly on other elements or layers, adjacent to, connected to or coupled to other elements or layers, or there can be intervening elements or layers. On the contrary, when an element is referred to as "directly on ...", "directly adjacent to ...", "directly connected to" or "directly coupled to" other elements or layers, there is no intervening element or layer. It should be understood that although the terms first, second, third, etc. can be used to describe various elements, components, regions, layers and / or parts, these elements, components, regions, layers and / or parts should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or part from another element, component, region, layer or part. Therefore, without departing from the gist of the present application, the first element, component, region, layer or part discussed below can be expressed as a second element, component, region, layer or part. And when the second element, component, region, layer or part discussed, it does not indicate that the present application necessarily has a first element, component, region, layer or part.

[0023] The purpose of the terms used herein is only to describe specific embodiments and is not intended to be limiting of the present application. When used herein, the singular forms "one", "an" and "said / the" are also intended to include plural forms, unless the context clearly indicates otherwise. It should also be understood that the terms "consisting of" and / or "comprising", when used in this specification, determine the presence of the features, integers, steps, operations, elements and / or parts, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, parts and / or groups. When used herein, the term "and / or" includes any and all combinations of the relevant listed items.

[0024] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The technical and scientific terms used herein are only for the purpose of describing the embodiments of this application and are not intended to limit this application.

[0025] The embodiments of the present application provide a method, apparatus, device and medium for eliminating abnormal values ​​in VTEC. It is only necessary to determine the abnormal grid points of ionospheric VTEC and form a normal equation. There is no need to introduce external ionospheric data and no empirical model is selected. Only the original input data and a specific parameter estimation method are relied on to eliminate the abnormal grid points in the global ionospheric grid model.

[0026] Figure 1 A schematic diagram of the implementation flow of a method for eliminating abnormal values ​​in VTEC provided in this application is shown as follows: Figure 1 As shown, the method includes the following steps S101 to S104:

[0027] Step S101, generating a global ionospheric grid model based on a global ionospheric VTEC model, wherein the VTEC model is established based on ionospheric observation information;

[0028] Here, the global ionospheric VTEC model is established by acquiring the ionospheric observation information and using spherical harmonics; and a global ionospheric grid model in a standard format is generated through the global ionospheric VTEC model.

[0029] When implemented, step S101 includes step S1011 and step S1012, wherein:

[0030] Step S1011, establishing the global ionospheric VTEC model using spherical harmonics based on the ionospheric observation information;

[0031] Here, the ionospheric observation information is extracted based on GNSS dual-frequency data, wherein the ionospheric observation information includes information such as ionospheric delay value, puncture point position, satellite altitude angle and azimuth angle, and the GNSS dual-frequency data includes ionospheric combined observation values ​​based on pseudorange and ionospheric combined observation values ​​based on carrier phase. In some embodiments, the ionospheric delay value can be extracted using a carrier smoothing pseudorange method. Compared with the ionospheric combined observation value based on pseudorange or the ionospheric combined observation value based on carrier phase, the error of extracting the ionospheric delay value using the carrier smoothing pseudorange method is smaller.

[0032] Spherical harmonics refers to a modeling method on a sphere that uses orthogonal functions as the basis. It has the characteristics of standard orthogonality, rotational invariance, and the integral of the function product is equal to the dot product of its spherical harmonic coefficient vector. The input of the spherical harmonic function is the geomagnetic latitude and the solar longitude of the ionosphere piercing point, and the output is the vertical total electron content of the VTEC model.

[0033] Step S1012: Generate a global ionospheric grid model in a standard format based on the global ionospheric VTEC model.

[0034] Here, the global ionospheric VTEC model is used to generate a global ionospheric grid model in a standard format using a computer program. The global ionospheric grid model in a standard format refers to a grid model in the IONEX format, which is the most commonly used space ionospheric data exchange format.

[0035] In this embodiment, firstly, a VTEC model is established through spherical harmonics based on ionospheric observation information, and then a global ionospheric grid model in a standard format is generated based on the VTEC model. This facilitates reading the VTEC data value of each grid point on the basis of the global ionospheric grid model in a standard format, which serves as the basis for subsequent judgment of whether there are abnormal grid points.

[0036] Step S102, determining abnormal grid points in the global ionospheric grid model;

[0037] Here, after reading the VTEC data value of each grid point, the grid point with abnormal VTEC data value is determined as an abnormal grid point, and the abnormal grid point is marked to facilitate the subsequent acquisition of surrounding data of the abnormal grid point.

[0038] Step S103, generating a statistical value of the abnormal grid point based on the surrounding data of the abnormal grid point;

[0039] When implemented, step S103 includes steps S1031 to S1033, wherein:

[0040] Step S1031: Acquire VTEC data values ​​of grid points surrounding the abnormal grid point;

[0041] Here, after the abnormal grid point is determined, VTEC data values ​​of grid points surrounding the abnormal grid point are obtained.

[0042] Step S1032: generating a weighted average value of the abnormal grid point based on the VTEC data values ​​of the surrounding grid points;

[0043] Here, based on the VTEC data values ​​of the surrounding grid points, a weighted average value of the VTEC data values ​​of the surrounding grid points is determined, and the weighted average value of the VTEC data values ​​of the surrounding grid points is determined as the weighted average value of the abnormal grid points.

[0044] Step S1033: determining the weighted average value of the abnormal grid points as the statistical value of the abnormal grid points.

[0045] In this embodiment, first, the VTEC data values ​​of the surrounding grid points of the abnormal grid point are obtained as the basis for the subsequent calculation of the weighted average value of the abnormal grid point; then, the weighted average value of the abnormal grid point is generated based on the VTEC data values ​​of the surrounding grid points; finally, the weighted average value of the abnormal grid point is determined as the statistical value of the abnormal grid point, and the obtained statistical value is used to facilitate the subsequent cyclic solution of the spherical harmonic coefficients of the VTEC model.

[0046] Step S104: eliminating abnormal grid points in the global ionospheric grid model based on the statistical values ​​of the abnormal grid points.

[0047] Here, the statistical values ​​of the abnormal grid points are substituted for the virtual observation values ​​in the normal equation matrix, wherein the normal equation is obtained based on the actual observation equation and the virtual observation equation, the virtual observation values ​​are obtained by the spherical harmonic coefficients of the VTEC model through the virtual observation equation, and the actual observation values ​​are obtained by the spherical harmonic coefficients of the VTEC model through the actual observation equation; then, the spherical harmonic coefficients of the VTEC model are solved to obtain the re-estimated spherical harmonic coefficients. After that, the re-estimated spherical harmonic coefficients are substituted into the VTEC model to redetermine the abnormal grid points; and based on the peripheral data of the re-determined abnormal grid points, the statistical values ​​of the re-determined abnormal grid points are generated again, and the spherical harmonic coefficients of the VTEC model are solved again to obtain the second re-estimated spherical harmonic coefficients, and this iterative solution process is executed repeatedly until there are no abnormal values ​​of VTEC at all grid points in the global ionosphere grid model, and the abnormal grid points in the global ionosphere grid model are eliminated.

[0048] In this embodiment, firstly, a global ionospheric VTEC model is established based on ionospheric observation information, and then a global ionospheric grid model is generated based on the global ionospheric VTEC model, so as to facilitate reading the VTEC data value of each grid point in the global ionospheric grid model as a basis for subsequent judgment of abnormal grid points; secondly, the abnormal grid points in the global ionospheric grid model are determined as a prerequisite for subsequent acquisition of peripheral data of the abnormal grid points; thirdly, based on the peripheral data of the abnormal grid points, statistical values ​​of the abnormal grid points are generated, where the statistical values ​​of the abnormal grid points are generated according to the VTEC data values ​​of the peripheral grid points of the abnormal grid points, where the statistical values ​​of the abnormal grid points are used as a basis for subsequent recalculation of the spherical harmonic coefficients of the VTEC model; finally, based on the statistical values ​​of the abnormal grid points, the abnormal grid points in the global ionospheric grid model are eliminated, where the spherical harmonic coefficients of the VTEC model are cyclically iterated and solved by the statistical values ​​of the abnormal grid points until no abnormal values ​​of VTEC appear at all grid points in the global ionospheric grid model. By adopting the technical solution of the present application, it is only necessary to rely on the original data and parameter estimation method in the VTEC model, without introducing a large amount of external measured data, and there is no need to select an empirical model. This solves the problem that when the traditional technology is used to compensate for the abnormal value of ionospheric VTEC, the compensation effect depends on the amount of accumulated measured data introduced and whether the weight accuracy of the selected empirical model is appropriate.

[0049] In some embodiments, Figure 2 As shown, step S102 includes step S1021 and step S1022, wherein:

[0050] Step S1021: obtaining VTEC data values ​​of grid points in the global ionospheric grid model;

[0051] Here, after the global ionospheric grid model is determined, the VTEC data value of each grid point in the global ionospheric grid model is automatically read.

[0052] Step S1022: Determine the grid point where the VTEC data value is less than the minimum VTEC constraint value or greater than the maximum VTEC constraint value as the abnormal grid point.

[0053] Here, the minimum VTEC constraint value and / or the maximum VTEC constraint value can be set according to the requirements, for example, the minimum VTEC constraint value can be set to 0TECU, and the maximum VTEC constraint value can be set to 180TECU, wherein the unit of the VTEC data value (Total Electron Content Unit, TECU) is used to represent the total electron content of the ionosphere per square meter. In some cases, the VTEC data value of each grid point in the global ionospheric grid model should be between the minimum VTEC constraint value and the maximum VTEC constraint value; if the VTEC data value is lower than the minimum VTEC constraint value, the VTEC data value is a negative anomaly; if the VTEC data value is greater than the maximum VTEC constraint value, the VTEC data value is a positive anomaly; therefore, the grid point whose VTEC data value is less than the minimum VTEC constraint value or greater than the maximum VTEC constraint value can be determined as the abnormal grid point.

[0054] In this embodiment, firstly, the VTEC data value of each grid point in the global ionospheric grid model is obtained as a prerequisite for subsequent determination of whether there are abnormal grid points; secondly, the grid points whose VTEC data values ​​are less than the minimum VTEC constraint value or greater than the maximum VTEC constraint value are determined as the abnormal grid points, thereby realizing the selection of abnormal grid points in the global ionospheric grid model, and facilitating the subsequent acquisition of VTEC data values ​​of grid points surrounding the abnormal grid points.

[0055] In some embodiments, step S1022 includes steps S1221 to S1223, wherein:

[0056] Step S1221: determining the grid points where the VTEC data value is less than the minimum VTEC constraint value or greater than the maximum VTEC constraint value as candidate grid points;

[0057] Step S1222: Obtaining the grid point mean square error and unit weight mean square error of the candidate grid point;

[0058] Here, the unit weighted mean error is calculated based on the weights calculated from the observed satellite altitude angle, the error matrix, the number of observations, and the number of unknown parameters using the least squares parameter estimation method; the grid point mean error can be calculated based on the unit weighted mean error.

[0059] Step S1223: Determine the candidate grid point whose grid point mean error is greater than N times the unit weight mean error as the abnormal grid point; wherein N is an integer between 3 and 5.

[0060] Here, the value of N is preferably 5, and the grid points whose VTEC data values ​​are less than the minimum VTEC constraint value or greater than the maximum VTEC constraint value and whose mean square error of the grid points is greater than 5 times the mean square error of the unit weight are determined as the abnormal grid points, and the abnormal grid points are marked.

[0061] In this embodiment, the grid point whose VTEC data value is less than the minimum VTEC constraint value or greater than the maximum VTEC constraint value and whose mean square error of the grid point is greater than N times the mean square error of the unit weight is determined as the abnormal grid point, thereby achieving the final selection of the abnormal grid point, which facilitates the subsequent acquisition of the VTEC data values ​​of the surrounding grid points of the abnormal grid point.

[0062] In some embodiments, step S104 specifically includes step S1041 and step S1042, wherein:

[0063] Step S1041: Calculating the spherical harmonic coefficients of the VTEC model based on the statistical values ​​of the abnormal grid points;

[0064] Here, the statistical values ​​of the abnormal grid points replace the virtual observation values ​​in the normal equation matrix, wherein the normal equation is obtained based on the actual observation equation and the virtual observation equation, the virtual observation values ​​are obtained from the spherical harmonic coefficients of the VTEC model through the virtual observation equation, the actual observation values ​​are obtained from the spherical harmonic coefficients of the VTEC model through the actual observation equation, and the spherical harmonic coefficients of the VTEC model are solved to obtain the re-estimated spherical harmonic coefficients.

[0065] Step S1042: Based on the spherical harmonic coefficients of the VTEC model, iteratively replace the grid points in the global ionospheric grid model where VTEC has no anomalies.

[0066] Here, after solving the spherical harmonic coefficients of the VTEC model to obtain re-estimated spherical harmonic coefficients, the re-estimated spherical harmonic coefficients are substituted into the VTEC model, the abnormal grid points are re-determined, the statistical values ​​of the re-determined abnormal grid points are re-generated based on the surrounding data of the re-determined abnormal grid points, the spherical harmonic coefficients of the VTEC model are solved again to obtain the second re-estimated spherical harmonic coefficients, and this solving iterative process is executed repeatedly until there are no abnormal values ​​of VTEC for all grid points in the global ionosphere grid model, and the abnormal grid points in the global ionosphere grid model are eliminated.

[0067] In this embodiment, the spherical harmonic coefficients of the VTEC model are first calculated based on the statistical values ​​of the abnormal grid points, so that the re-estimated spherical harmonic coefficients can be obtained; then, based on the spherical harmonic coefficients of the VTEC model, the grid points with no VTEC abnormalities in the global ionosphere grid model are cyclically and iteratively replaced until no abnormal VTEC values ​​appear at all grid points in the global ionosphere grid model, thereby achieving the effect of eliminating the abnormal grid points in the global ionosphere grid model.

[0068] In some embodiments, step S1041 includes step S1411 and step S1412, wherein:

[0069] Step S1411: replacing the virtual observation values ​​in the normal equation matrix with the statistical values ​​of the abnormal grid points; wherein the normal equation is obtained based on the actual observation equation and the virtual observation equation, and the virtual observation values ​​are obtained from the spherical harmonic coefficients of the VTEC model through the virtual observation equation;

[0070] Step S1412: Calculate the spherical harmonic coefficients of the VTEC model.

[0071] In this embodiment, first, the statistical values ​​of the abnormal grid points are substituted for the virtual observation values ​​in the normal equation matrix to facilitate the subsequent solution of the spherical harmonic coefficients of the VTEC model; then, the spherical harmonic coefficients of the VTEC model are solved. The re-estimated spherical harmonic coefficients are obtained as the basis for subsequent cyclic iterations, thereby realizing the cyclic solution of the spherical harmonic coefficients of the VTEC model.

[0072] Before introducing the embodiments of the present application, the traditional scheme is introduced first. The traditional scheme is to obtain the ionospheric VTEC based on the inversion of GNSS dual-frequency pseudorange and carrier observation data. The basic principle is to combine the ionospheric observation equation according to the GNSS dual-frequency observation data, eliminate the parameters unrelated to the ionospheric parameters, including geometric position, troposphere, clock error and other information; then, use the carrier phase observation value and pseudorange observation value to form the carrier phase smoothed pseudorange observation value; finally, eliminate the influence of the differential code deviation between the satellite end and the receiver end, and extract the ionospheric VTEC. Among them, using spherical harmonics to establish a global ionospheric VTEC model is the most commonly used method for global ionospheric inversion. However, using spherical harmonics to establish a global ionospheric VTEC model has the problem that some grid points are outliers (negative values ​​or maximum values), especially in areas where there are no observation stations. In traditional technology, empirical models are used to compensate for the problem of ionospheric VTEC being an outlier, but it needs to rely on a large amount of measured data and the accuracy of the empirical model with appropriate weights, that is, there is a problem that the compensation effect depends on the amount of measured data accumulation introduced and whether the accuracy of the selected empirical model weights is appropriate.

[0073] In the technical solution of the present application, only the original data and parameter estimation method need to be relied upon, and there is no need to introduce a large amount of measured data or select an empirical model. The data processing method is simple, convenient and flexible, and solves the problem that when the traditional technology is used to compensate for the abnormal value of ionospheric VTEC, the compensation effect depends on the amount of accumulated measured data introduced and whether the weight accuracy of the selected empirical model is appropriate.

[0074] The present application provides a method for eliminating outliers in VTEC, which uses a spherical harmonic function model to invert the global ionospheric VTEC total electron content, searches for and counts ionospheric VTEC abnormal grid points, generates a weighted average value based on the peripheral data of the VTEC abnormal grid points, regards the weighted average value as a virtual observation value and adds it to the normal equation matrix, re-estimates the coefficients of the spherical harmonic function model, and eliminates the VTEC abnormal values ​​of the grid points in the global ionospheric model.

[0075] Step 1: extract ionospheric observation information, which specifically includes ionospheric delay value, puncture point position, satellite altitude angle and azimuth information. The specific values ​​of the puncture point position, satellite altitude angle and azimuth angle can be directly read from the GNSS RINEX 3.0 (standard format observation file in GNSS dual-frequency data) file by a computer program, and the ionospheric delay value is calculated by the following method:

[0076] The ionospheric observation equation is composed according to the ionospheric combined observation value based on pseudorange and the ionospheric combined observation value based on carrier phase, as shown in the following equations (1-1) and (1-2):

[0077]

[0078]

[0079] In formulas (1-1) and (1-2), represents the ionospheric combined observation value based on pseudorange; Indicates frequency f 1 The corresponding ionospheric combined observation value based on pseudorange at time; Indicates frequency f 2 The corresponding ionospheric combined observation value based on pseudorange at time; represents the combined ionospheric observation value based on carrier phase; represents the geometry-independent ionospheric delay value; and represent the differential code deviation of the receiver and the satellite respectively; f 1 and f 2 Respectively represent the frequencies corresponding to the dual-frequency carrier phases; Indicates frequency f 1 The ionospheric combined observation value based on the carrier phase corresponding to the time; Indicates frequency f 2 The ionospheric combined observation value based on the carrier phase corresponding to the time; and Respectively represent the frequency f 1 and f 2 The wavelength corresponding to the phase of the dual-frequency carrier wave; and Respectively represent the frequency f 1 and f 2 The ambiguity corresponding to the dual-frequency carrier phase at time i represents the station number, and k represents the satellite number.

[0080] Since the combined ionospheric observations based on carrier phase contain ambiguity parameters, the combined ionospheric observations based on pseudorange have large noises, which will cause the ionospheric observations obtained by equations (1-1) and (1-2) to be The error is large, so the carrier smoothing pseudorange method is used to extract the ionospheric delay value, as shown in the following formula (1-3):

[0081]

[0082] In formula (1-3), Represents the combined ionospheric observation value based on carrier-smoothed pseudorange.

[0083] The ionospheric delay value can be calculated by formula (1-3), and together with the specific values ​​of the puncture point position, satellite altitude angle and azimuth angle directly read by the computer program, they constitute the ionospheric observation information.

[0084] Step 2: Based on the ionospheric observation information, a global ionospheric VTEC model is established through spherical harmonics, and a global ionospheric grid model in the IONEX standard format is generated. The computer program defaults to setting the maximum model order of the spherical harmonics to 15, the time resolution to 2 hours, the latitude difference to 2.5 degrees, and the longitude difference to 5.0 degrees.

[0085] The expression of the global ionospheric VTEC model established using spherical harmonics is shown in the following equation (2-1):

[0086]

[0087] In formula (2-1), β represents the geomagnetic latitude of the ionospheric piercing point; s = λ-λ 0 represents the solar longitude of the puncture point; λ represents the geomagnetic longitude of the puncture point; λ 0 =π-t represents the geomagnetic longitude of the sun; t represents the universal time at the time of observation; represents the orthogonalized associated Legendre function; P nm represents the classical Legendre function of order n times and m; represents the orthogonalization factor; Represents Kronecker delta; n max represents the maximum order of spherical harmonics; and represents the spherical harmonic coefficients.

[0088] The global ionospheric VTEC model is established through spherical harmonic functions, and the total electron content in the vertical direction of the global ionosphere can be obtained.

[0089] The process of calculating the spherical harmonic coefficients X according to the least squares parameter estimation method is shown in the following equations (2-2) to (2-5):

[0090]

[0091] N BB =B T P L B (2-3);

[0092] W BB =B T P L L (2-4);

[0093]

[0094] In formulas (2-2) to (2-5), X represents the spherical harmonic coefficient, which is and N BB Representation equation matrix; W BB represents the observation matrix; B represents the design matrix generated by the observation data, which is calculated based on the spherical harmonic function; P L Represents the weight P of the observation satellite altitude angle ele calculation L =1 / sin 2 ele; L represents the actual observation value vector. Among them, formula (2-2) represents the spherical harmonic coefficient X according to the normal equation matrix N BB and the observation matrix W BB Calculated, formula (2-3) represents the equation matrix N BB The calculation formula of , formula (2-4) represents the observation matrix W BB The calculation formula is: Formula (2-5) represents the transposed matrix B of the design matrix B generated by the observation data T The calculation formula of B and B T Used to calculate the normal equation matrix N in equations (2-3) and (2-4) respectively BB and the observation matrix W BB .

[0095] The unit weighted mean error σ calculated by the least squares parameter estimation method STD As shown in the following formula (2-6)

[0096]

[0097] In formula (2-6), V represents the error matrix; n SH Indicates the number of observations; u SH Indicates the number of unknown parameters.

[0098] Step 3, determine the abnormal grid points in the global ionosphere grid model. The computer program defaults to the global ionosphere model for each day including 13 time points (from 0:00 on the current day to 0:00 on the next day), and automatically searches for the value of each grid point at each time, determines the ionospheric VTEC abnormal grid points and automatically marks them. The standard for judging abnormal values ​​is shown in the following formula (3-1):

[0099]

[0100] In formula (3-1), || is || means "or"; B UNM represents the design matrix generated by the abnormal grid points, which is calculated based on the spherical harmonics; X represents the spherical harmonic coefficients, which are solved in the above steps. and B UNM X represents the vertical total electron content of the abnormal grid point; σ GRID It represents the RMS error in the grid points, and the calculation formula is expressed as σ STD Represents the unit weighted mean square error RMS; N is an integer between 3 and 5, and N represents the multiple relationship between the grid point mean square error RMS and the unit weighted mean square error RMS; 0 represents the minimum VTEC constraint value, in TECU, and 180 represents the maximum VTEC constraint value, in TECU;

[0101] Among them, B UNM The calculation formula is shown in the following formula (3-2):

[0102]

[0103] In formula (3-2), β UNM Indicates the geomagnetic latitude of the ionospheric piercing point corresponding to the anomaly grid point; s UNM Indicates the solar longitude of the puncture point corresponding to the anomaly grid point.

[0104] Step 4: Generate a weighted average value of the grid points based on the surrounding data of the VTEC abnormal grid points, and treat the weighted average value of the grid points as a virtual observation value and add it to the normal equation matrix to participate in the solution of the spherical harmonic coefficients.

[0105] The normal equation matrix is ​​constructed by the actual observation equation and the virtual observation equation.

[0106] The virtual observation equation is shown in equation (4-1):

[0107] W ITP =B UNM X NEW (4-1);

[0108] In formula (4-1), W ITP represents the weighted average of the abnormal grid points, W i represents the grid point ionospheric VTEC, p i =1 / l 1 represents the weight of the grid point, l 1 Indicates the distance between the surrounding grid points and the abnormal grid points;

[0109] The actual observation equation is shown in equation (4-2):

[0110] L=BX NEW (4-2);

[0111] The actual observation equation and the virtual observation equation can be expressed as shown in the following formula (4-3):

[0112]

[0113] The variance matrix of the random model can be expressed as shown in the following formula (4-4):

[0114]

[0115] In formulas (4-2) to (4-4), L represents the actual observation value vector, B represents the actual observation data design matrix, and X NEW represents the re-estimated spherical harmonic coefficients; D represents the variance matrix of the random model; σ i (i=l,W ITP ) represents the prior unit weighted mean error, P L =1 / sin 2 ele represents the weight of the actual observation data, ele represents the satellite altitude angle; D L represents the variance matrix represented by the observation equation; represents the variance matrix of abnormal grid points; σ l represents the unit weight error of the observation equation; represents the unit weight error of abnormal grid points; Represents the weight of the virtual observation value of the abnormal grid point.

[0116] By using the above equations (4-3) and (4-4), the re-estimated spherical harmonic coefficients X are calculated. NEW .

[0117] Step 5, loop through the above steps 2 to 4, iteratively replace the grid points with no VTEC anomalies in the global ionospheric grid model, and regenerate the global ionospheric grid model in a standard format.

[0118] The method for eliminating VTEC outliers in ionospheric modeling provided in the above embodiment can be applied to satellite-based enhanced positioning of future new products. Satellite-based enhanced positioning is aimed at intelligent driving, drones, marine construction, surveying and mapping and other fields to provide high-precision positioning services, including: marking VTEC outliers based on grid point ionospheric VTEC and mean square error RMS information; and replacing VTEC outliers with the weighted average method of surrounding grid points, and adding them as virtual observation values ​​to the normal equation matrix to re-estimate the ionospheric model parameters.

[0119] Based on the above method, the embodiment of the present application also provides a device for eliminating abnormal values ​​in VTEC, such as Figure 3 As shown, the device 300 for eliminating abnormal values ​​in VTEC includes the following modules:

[0120] The ionospheric observation information extraction module 301 is used to extract ionospheric observation information according to the GNSS dual-frequency data, wherein the ionospheric observation information includes information such as ionospheric delay value, puncture point position, satellite altitude angle and azimuth angle, and the ionospheric delay value is extracted using a carrier smoothing pseudorange method;

[0121] A modeling module 302 is used to establish a global ionospheric VTEC model using spherical harmonics and generate a global ionospheric grid model in a standard format, wherein the VTEC model is established based on ionospheric observation information, wherein the system defaults to setting the maximum model order of the spherical harmonics to 15, the time resolution to 2 hours, the latitude difference to 2.5 degrees, and the longitude difference to 5.0 degrees;

[0122] An abnormal grid point marking module 303 is used to determine and mark abnormal grid points in the global ionospheric grid model, wherein the minimum VTEC constraint value is set to 0TECU and the maximum VTEC constraint value is set to 180TECU;

[0123] The spherical harmonic coefficient estimation module 304 is used to generate a weighted average value according to the VTEC data values ​​of the surrounding grid points of the abnormal grid point, and regard the weighted average value as a virtual observation value to add into the normal equation matrix to re-estimate the spherical harmonic coefficients of the spherical harmonic function model;

[0124] The outlier processing module 305 is used to perform cyclic processing through the modeling module 302, the outlier grid point marking module 303 and the spherical harmonic coefficient estimation module 304 until there are no VTEC outliers in the global ionosphere grid model, and regenerate the global ionosphere grid model in a standard format.

[0125] Compared with the traditional technology, the embodiment of the present application has the following advantages: 1. The data processing method is simple, and only needs to mark the ionospheric VTEC abnormal grid points that do not meet the range to form a normal equation; 2. There is no need to introduce external ionospheric data, and there is no need to select an empirical model, only relying on the original input data and a specific parameter estimation method; 3. It has no impact on the ionospheric VTEC of other non-abnormal grid points.

[0126] The embodiment of the present application provides a device for eliminating abnormal values ​​in VTEC, such as Figure 4 As shown, the device 400 for eliminating abnormal values ​​in VTEC includes: a first generating module 410, used to generate a global ionospheric grid model based on a global ionospheric VTEC model, wherein the VTEC model is established based on ionospheric observation information; a determining module 420, used to determine abnormal grid points in the global ionospheric grid model; a second generating module 430, used to generate statistical values ​​of the abnormal grid points based on surrounding data of the abnormal grid points; and an eliminating module 440, used to eliminate abnormal grid points in the global ionospheric grid model based on the statistical values ​​of the abnormal grid points.

[0127] In some embodiments, the first generation module 410 includes: a modeling submodule, used to establish the global ionospheric VTEC model using spherical harmonic functions based on the ionospheric observation information; and a first generation submodule, used to generate a global ionospheric grid model in a standard format based on the global ionospheric VTEC model.

[0128] In some embodiments, the determination module 420 includes: a first acquisition submodule, used to obtain the VTEC data value of the grid point in the global ionospheric grid model; a first determination submodule, used to determine the grid point whose VTEC data value is less than the minimum VTEC constraint value or greater than the maximum VTEC constraint value as the abnormal grid point.

[0129] In some embodiments, the first determination submodule includes: a first determination unit, used to determine the grid points whose VTEC data values ​​are less than the minimum VTEC constraint value or greater than the maximum VTEC constraint value as candidate grid points; a first acquisition unit, used to acquire the grid point mean error and the unit weighted mean error of the candidate grid points; and a second determination unit, used to determine the candidate grid points whose grid point mean error is greater than N times the unit weighted mean error as the abnormal grid points, where N is an integer between 3 and 5.

[0130] In some embodiments, the second generation module 430 includes: a second acquisition submodule, used to acquire VTEC data values ​​of surrounding grid points of the abnormal grid point; a second generation submodule, used to generate a weighted average value of the abnormal grid point based on the VTEC data values ​​of the surrounding grid points; and a second determination submodule, used to determine the weighted average value of the abnormal grid point as the statistical value of the abnormal grid point.

[0131] In some embodiments, the elimination module 440 includes: a solver module, used to solve the spherical harmonic coefficients of the VTEC model based on the statistical values ​​of the abnormal grid points; a loop submodule, used to iteratively replace the spherical harmonic coefficients of the VTEC model with grid points without VTEC anomalies in the global ionospheric grid model based on the spherical harmonic coefficients of the VTEC model.

[0132] In some embodiments, the solver module includes: a replacement unit, used to replace the virtual observation values ​​in the normal equation matrix with the statistical values ​​of the abnormal grid points; wherein the normal equation is obtained by forming an actual observation equation and a virtual observation equation, and the virtual observation value is obtained by the spherical harmonic coefficients of the VTEC model through the virtual observation equation; and a solver unit, used to solve the spherical harmonic coefficients of the TEC model.

[0133] The description of the above embodiment of the device for eliminating abnormal values ​​in VTEC is similar to the description of the embodiment of the method for eliminating abnormal values ​​in VTEC, and has similar beneficial effects as the method embodiment. In some embodiments, the functions or modules included in the device for eliminating abnormal values ​​in VTEC provided in the embodiment of the present application can be used to execute the method described in the embodiment of the method for eliminating abnormal values ​​in VTEC. For technical details not disclosed in the embodiment of the device of the present application, please refer to the description of the embodiment of the method for eliminating abnormal values ​​in VTEC of the present application for understanding.

[0134] An embodiment of the present application provides a device for eliminating abnormal values ​​in VTEC. When implemented, the device can be a computer device (such as a laptop computer, a desktop computer, a server cluster, etc.), including a processor and a memory, wherein the memory is used to store a computer program; the processor is used to execute the computer program stored in the memory to implement the above method.

[0135] The embodiment of the present application provides a computer-readable storage medium, wherein the computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the above method is implemented. The computer-readable storage medium may be transient or non-transient.

[0136] It should be noted that in the embodiment of the present application, if the above method is implemented in the form of a software function module and sold or used as an independent product, it can also be stored in a computer-readable storage medium. Based on such an understanding, the technical solution of the embodiment of the present application is essentially or the part that contributes to the relevant technology can be embodied in the form of a software product, which is stored in a storage medium, including several instructions for executing all or part of the above methods of each embodiment of the present application. The aforementioned storage medium includes: various media that can store program codes, such as a U disk, a mobile hard disk, a read-only memory (ROM), a disk or an optical disk. In this way, the embodiment of the present application is not limited to any specific hardware, software or firmware, or any combination of hardware, software and firmware.

[0137] An embodiment of the present application provides a computer program, including a computer-readable code. When the computer-readable code is run in the computer program, the processor executes some or all of the steps in the above method.

[0138] The embodiment of the present application provides a computer program product, which includes a non-transitory computer-readable storage medium storing a computer program, and when the computer program is read and executed by a computer, some or all of the steps in the above method are implemented. The computer program product can be implemented specifically by hardware, software or a combination thereof. In some embodiments, the computer program product is specifically embodied as a computer storage medium, and in other embodiments, the computer program product is specifically embodied as a software product, such as a software development kit (SDK).

[0139] It should be noted here that the description of the various embodiments above tends to emphasize the differences between the various embodiments, and the same or similar aspects can be referenced to each other. The description of the above device, storage medium, computer program and computer program product embodiments is similar to the description of the above method embodiment, and has similar beneficial effects as the method embodiment. For technical details not disclosed in the embodiments of the device, storage medium, computer program and computer program product of the present application, please refer to the description of the method embodiment of eliminating abnormal values ​​in VTEC of the present application for understanding.

[0140] In the embodiment of the present application, a device for eliminating abnormal values ​​in VTEC is provided, such as Figure 5 As shown, the hardware entity of the device 500 for eliminating abnormal values ​​in VTEC includes: a processor 501, a communication interface 502 and a memory 503, wherein:

[0141] Processor 501 generally controls the overall operation of device 500 .

[0142] The communication interface 502 enables the device to communicate with other terminals or servers through a network.

[0143] The memory 503 is configured to store instructions and applications executable by the processor 501, and can also cache data to be processed or processed by the processor 501 and each module in the device 500 (for example, image data, audio data, voice communication data, and video communication data), which can be implemented by flash memory (FLASH) or random access memory (Random Access Memory, RAM). Data transmission can be performed between the processor 501, the communication interface 502, and the memory 503 through the bus 504.

[0144] It should be understood that "one embodiment" or "an embodiment" mentioned throughout the specification means that specific features, structures or characteristics related to the embodiment are included in at least one embodiment of the present application. Therefore, "in one embodiment" or "in an embodiment" appearing throughout the specification does not necessarily refer to the same embodiment. In addition, these specific features, structures or characteristics can be combined in one or more embodiments in any suitable manner. It should be understood that in various embodiments of the present application, the size of the serial number of each step / process mentioned above does not mean the order of execution, and the execution order of each step / process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiment of the present application. The serial numbers of the embodiments of the present application mentioned above are for description only and do not represent the advantages and disadvantages of the embodiments.

[0145] It should be noted that, in this article, the terms "include", "comprises" or any other variations 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 a ..." does not exclude the existence of other identical elements in the process, method, article or device including the element.

[0146] In several embodiments provided in the present application, it should be understood that the disclosed devices, equipment and methods can be implemented in other ways. The above-described device and equipment embodiments are merely schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation, such as: multiple units or components can be combined, or can be integrated into another system, or some features can be ignored or not executed. In addition, the coupling, direct coupling, or communication connection between the components shown or discussed can be through some interfaces, and the indirect coupling or communication connection of the devices or units can be electrical, mechanical or other forms.

[0147] The units described above as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units; they may be located in one place or distributed on multiple network units; some or all of the units may be selected according to actual needs to achieve the purpose of the present embodiment.

[0148] In addition, all functional units in the embodiments of the present application may be integrated into one processing unit, or each unit may be a separate unit, or two or more units may be integrated into one unit; the above-mentioned integrated units may be implemented in the form of hardware or in the form of hardware plus software functional units.

[0149] A person skilled in the art can understand that all or part of the steps of implementing the above method embodiment can be completed by hardware related to program instructions, and the aforementioned program can be stored in a computer-readable storage medium. When the program is executed, it executes the steps of the above method embodiment; and the aforementioned storage medium includes: mobile storage devices, read-only memories (ROM), magnetic disks or optical disks, etc., various media that can store program codes.

[0150] Alternatively, if the above-mentioned integrated unit of the present application is implemented in the form of a software function module and sold or used as an independent product, it can also be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application can essentially or in other words, the part that contributes to the relevant technology can be embodied in the form of a software product, which is stored in a storage medium and includes a number of instructions for a device to execute all or part of the methods described in each embodiment of the present application. The aforementioned storage medium includes: various media that can store program codes, such as mobile storage devices, ROMs, magnetic disks or optical disks.

[0151] The above is only an implementation method of the present application, but the protection scope of the present application is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application.

Claims

1. A method for eliminating abnormal values ​​in VTEC, characterized in that: include: Generate a global ionospheric grid model based on a global ionospheric VTEC model, wherein the VTEC model is established based on ionospheric observation information; Determining abnormal grid points in the global ionospheric grid model; Generate a statistical value of the abnormal grid point based on the surrounding data of the abnormal grid point; Based on the statistical values ​​of the abnormal grid points, the abnormal grid points in the global ionospheric grid model are eliminated.

2. The method according to claim 1, characterized in that Determining abnormal grid points in the global ionospheric grid model includes: Obtaining VTEC data values ​​of grid points in the global ionospheric grid model; The grid points where the VTEC data value is less than the minimum VTEC constraint value or greater than the maximum VTEC constraint value are determined as the abnormal grid points.

3. The method according to claim 2, characterized in that The step of determining the grid point where the VTEC data value is less than the minimum VTEC constraint value or greater than the maximum VTEC constraint value as the abnormal grid point includes: Determine a grid point where the VTEC data value is less than a minimum VTEC constraint value or greater than a maximum VTEC constraint value as a candidate grid point; Obtaining a grid point mean square error and a unit weight mean square error of the candidate grid point; The candidate grid points whose mean square error is greater than N times the mean square error of the unit weight are determined as the abnormal grid points; wherein N is an integer between 3 and 5.

4. The method according to any one of claims 1 to 3, characterized in that The generating the statistical value of the abnormal grid point based on the surrounding data of the abnormal grid point includes: Obtain VTEC data values ​​of surrounding grid points of the abnormal grid point; generating a weighted average value of the abnormal grid point based on the VTEC data values ​​of the surrounding grid points; The weighted average value of the abnormal grid points is determined as the statistical value of the abnormal grid points.

5. The method according to any one of claims 1 to 3, characterized in that The generating of the global ionospheric grid model based on the global ionospheric VTEC model comprises: Based on the ionospheric observation information, establishing the global ionospheric VTEC model using spherical harmonic functions; Based on the global ionospheric VTEC model, a global ionospheric grid model in a standard format is generated.

6. The method according to claim 5, characterized in that The step of eliminating abnormal grid points in the global ionospheric grid model based on the statistical values ​​of the abnormal grid points comprises: Calculating the spherical harmonic coefficients of the VTEC model based on the statistical values ​​of the abnormal grid points; Based on the spherical harmonic coefficients of the VTEC model, the grid points with no VTEC anomalies in the global ionospheric grid model are replaced iteratively.

7. The method according to claim 6, characterized in that The step of calculating the spherical harmonic coefficients of the VTEC model based on the statistical values ​​of the abnormal grid points includes: The statistical values ​​of the abnormal grid points are used to replace the virtual observation values ​​in the normal equation matrix; wherein the normal equation is obtained based on the actual observation equation and the virtual observation equation, and the virtual observation values ​​are obtained from the spherical harmonic coefficients of the VTEC model through the virtual observation equation; The spherical harmonic coefficients of the VTEC model are solved.

8. A device for eliminating abnormal values ​​in VTEC, characterized in that: include: A first generating module is used to generate a global ionospheric grid model based on a global ionospheric VTEC model, wherein the VTEC model is established based on ionospheric observation information; A determination module, used to determine abnormal grid points in the global ionospheric grid model; A second generating module, configured to generate a statistical value of the abnormal grid point based on surrounding data of the abnormal grid point; An elimination module is used to eliminate abnormal grid points in the global ionospheric grid model based on the statistical values ​​of the abnormal grid points.

9. A device for eliminating abnormal values ​​in VTEC, characterized in that: Including processor and memory: The memory is used to store computer programs; The processor is used to execute the computer program stored in the memory to implement the method according to any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the method according to any one of claims 1 to 7 is implemented.

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