Ionospheric electron density calculation method and device, and electron content calculation method and device

Abstract

Disclosed in the present invention are an ionospheric electron density calculation method and device, and an electron content calculation method and device. The ionospheric electron density calculation method comprises: acquiring an electron content observation value of an ionospheric pierce point and an ionospheric electron density background value of a three-dimensional network; performing data assimilation on the electron content observation value and the ionospheric electron density background value to obtain an expression of an ionospheric electron density analysis value; constructing an observation error analysis function on the basis of the expression of the ionospheric electron density analysis value, the electron content observation value, and the ionospheric electron density background value; taking minimization of the observation error analysis function as an objective function, solving for a target position variance factor; and on the basis of the target position variance factor, calculating a corrected ionospheric electron density analysis value. In the present invention, a calculation result of ionospheric electron density is calibrated, such that the spatial distribution of electrons can be more accurately described, thereby improving the prediction accuracy of a model.

Description

Method and device for calculating ionospheric electron density and electron content TECHNICAL FIELD

[0001] The present application relates to the technical field of GNSS atmospheric monitoring, and in particular to a method and device for calculating ionospheric electron density and electron content. BACKGROUND

[0002] The ionosphere is an important part of the space environment, and monitoring and researching various phenomena in the ionosphere can reveal the spatiotemporal variation and physical mechanism of the ionosphere. The ionospheric electron density (IED) distribution is particularly important, and plays an important role in radio and satellite communication and satellite positioning.

[0003] In the calculation of ionospheric electron density, it is important to have prior information of global empirical model of IED, such as IRI and NeQuick global empirical model. Global empirical models are usually based on simplified assumptions, which may not be accurate in describing how electrons are distributed in the actual system. The prediction accuracy of the model is not high, resulting in inaccurate calculation of ionospheric electron density. SUMMARY

[0004] The present application provides a method and device for calculating ionospheric electron density and electron content to solve the technical problem of inaccurate calculation of ionospheric electron density and electron content due to low prediction accuracy of global empirical model.

[0005] To solve the above technical problem, the present application provides a method for calculating ionospheric electron density, comprising:

[0006] Obtaining an electron content observation value of an ionospheric piercing point and an ionospheric electron density background value of a three-dimensional network; wherein the three-dimensional regular network is provided by a global empirical model;

[0007] According to the electron content observation value and the ionospheric electron density background value, data assimilation is performed to obtain an expression of ionospheric electron density analysis value; wherein the expression is an expression of ionospheric electron density with respect to position variance factor;

[0008] According to the expression of ionospheric electron density analysis value, the electron content observation value and the ionospheric electron density background value, an observation error analysis function is constructed;

[0009] Taking the minimization of the observation error analysis function as the objective function, a target position variance factor is obtained;

[0010] According to the target position variance factor, a corrected ionospheric electron density analysis value is calculated through the expression of ionospheric electron density analysis value.

[0011] As a preferred solution, before acquiring the electron content observation value of the ionospheric piercing point, further comprising:

[0012] acquiring carrier phase observation value of the ionospheric piercing point by a dual-frequency GNSS receiver;

[0013] calculating the electron content observation value of the ionospheric piercing point according to the carrier phase observation value;

[0014] wherein the electron content observation value calculation formula is:

[0015] In the formula, V R represents the electron content observation value; L represents the carrier phase observation value; f1 and f2 are signal frequencies used by the dual-frequency receiver; B is the pseudo-range hardware delay; SDCB is the dual-frequency code bias of the satellite; RDCB is the dual-frequency code bias of the dual-frequency receiver.

[0016] As a preferred solution, the data assimilation according to the electron content observation value and the ionospheric electron density background value comprises:

[0017] Taking the longitude and latitude position of the ionospheric piercing point as the reference position, the electron content observation value and the ionospheric electron density background value are assimilated to obtain the following expression of ionospheric electron density analysis value: N A (λ i,j ,φ i,j ,h k )=N B (λ i,j ,φ i,j ,h k )+G(V R (λ0,φ0))-HN B (λ i,j ,φ i,j ,h k ); i=1...nI,j=1...nJ,k=1...K; G=BH T (R+HBH T ) -1 ; R=P -1 ; B=σ B I;

[0018] In the formula, λ i,j represents the longitude of the grid point with index i in the longitude direction and index j in the dimension direction in the three-dimensional network; φ i,j represents the dimension of the grid point with index i in the longitude direction and index j in the dimension direction in the three-dimensional network; h k represents the height of the grid point with index k in the height direction in the three-dimensional network; NA (λ i,j ,φ i,j ,h k ) represents the ionospheric electron density analysis value at position (λ i,j ,φ i,j ,h k ); N B (λ i,j ,φ i,j ,h k ) represents the ionospheric electron density background value at position (λ i,j ,φ i,j ,h k ); nI represents the number of all grids in the longitude direction in the three-dimensional grid; nJ represents the number of all grids in the latitude direction in the three-dimensional grid; K represents the number of all grids in the height direction in the three-dimensional grid; G represents the assimilation weight matrix; λ0 represents the longitude of the reference position; φ0 represents the latitude of the reference position; H represents the observation value sub-matrix; B represents the observation value coefficient matrix; R represents the observation value covariance matrix; P represents the observation value weight matrix; represents the random error; σ B represents the position method factor; I is the unit matrix.

[0019] As a preferred solution, the expression of the observation error analysis function is: f(N A ) = ||V R (λ0, φ0) - HN A (λ i,j ,φ i,j ,h k )||2+||N A (λ i,j ,φ i,j ,h k )-N B (λ i,j ,φ i,j ,h k )||;

[0020] In the formula, f(N A ) represents the observation error analysis function.

[0021] As a preferred solution, the target position variance factor is solved by taking the observation error analysis function minimization as the objective function, comprising:

[0022] Under the condition that the position variance factor is greater than 0, the target position variance factor is solved by taking the observation error analysis function minimization as the objective function;

[0023] Wherein, the solving formula of the target position variance factor is:

[0024] As a preferred solution, the longitude resolution of the three-dimensional network is 0.5°, the latitude resolution is 0.5°, the height resolution is 50 km, and the height range is from 100 km to 2000 km above sea level.

[0025] The application also provides an electronic content calculation method, comprising:

[0026] obtaining the corrected ionospheric electron density analysis values of the grid where the ionospheric piercing point to be solved is located and the grid points on all height layers overlapping with the grid where the ionospheric piercing point to be solved is located in the horizontal plane; wherein the grid is a grid in a three-dimensional regular network provided by a global empirical model; the grid point is a grid point in the three-dimensional regular network provided by the global empirical model; and the corrected ionospheric electron density analysis values are calculated according to the electronic content calculation method as described in the above application embodiment;

[0027] calculating the electronic content of the ionospheric piercing point according to all the corrected ionospheric electron density analysis values.

[0028] As a preferred solution, the calculating the electronic content of the ionospheric piercing point according to all the corrected ionospheric electron density analysis values comprises:

[0029] calculating the weighted average value of the corrected ionospheric electron density analysis value corresponding to each height layer;

[0030] summing the weighted average values corresponding to all height layers to obtain the electronic content of the ionospheric piercing point;

[0031] wherein the calculation formula of the electronic content of the ionospheric piercing point is:

[0032] In the formula, V B represents the electronic content of the ionospheric piercing point; λ i,j represents the longitude of the grid point with index i in the longitude direction and index j in the latitude direction in the three-dimensional network; φ i,j represents the latitude of the grid point with index i in the longitude direction and index j in the latitude direction in the three-dimensional network; h k represents the height of the grid point with index k in the height direction in the three-dimensional network; N A (λ i,j ,φ i,j ,h k ) represents the ionospheric electron density analysis value at position (λ i,j ,φ i,j ,h k ); w t,kThe weight value of the kth height layer corresponding to the tth corrected ionospheric electron density analysis value; K represents the total number of height layers; T represents the total number of corrected ionospheric electron density analysis values corresponding to each height layer.

[0033] On the basis of the above-mentioned embodiments, another embodiment of the present application provides an ionospheric electron density calculation device, comprising: a first data acquisition module, a data assimilation module and a correction module.

[0034] The first data acquisition module is configured to acquire the electron content observation value of the ionospheric piercing point and the ionospheric electron density background value of the three-dimensional network; wherein the three-dimensional regular network is provided by a global empirical model.

[0035] The data assimilation module is configured to perform data assimilation according to the electron content observation value and the ionospheric electron density background value to obtain an expression of the ionospheric electron density analysis value; wherein the expression is an expression of the ionospheric electron density about a position variance factor.

[0036] The correction module is configured to construct an observation error analysis function according to the expression of the ionospheric electron density analysis value, the electron content observation value and the ionospheric electron density background value; to obtain a target position variance factor by taking the minimization of the observation error analysis function as an objective function; and to calculate a corrected ionospheric electron density analysis value by the expression of the ionospheric electron density analysis value according to the target position variance factor.

[0037] On the basis of the above-mentioned embodiments, another embodiment of the present application provides an electron content calculation device, comprising: a second data acquisition module and an electron content calculation module.

[0038] The second data acquisition module is configured to acquire the grid where the ionospheric piercing point to be solved is located and the corrected ionospheric electron density analysis value of the grid point corresponding to the grid on all height layers overlapping with the grid where the ionospheric piercing point is located in the horizontal plane; wherein the grid is a grid in the three-dimensional regular network provided by a global empirical model; the grid point is a grid point in the three-dimensional regular network provided by the global empirical model; and the corrected ionospheric electron density analysis value is calculated according to the electron content calculation method as described in the above-mentioned embodiments of the present application.

[0039] The electron content calculation module is configured to calculate the electron content of the ionospheric piercing point according to all the corrected ionospheric electron density analysis values.

[0040] On the basis of the above-mentioned embodiments, a terminal device is provided in another embodiment of the present application, which comprises a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor, and the processor implements the electronic content calculation method according to the above-mentioned embodiments of the present application when executing the computer program.

[0041] On the basis of the above-mentioned embodiments, a storage medium is provided in another embodiment of the present application, which comprises a stored computer program, wherein the computer program controls a device where the storage medium is located to execute the electronic content calculation method according to the above-mentioned embodiments of the present application when running.

[0042] Compared with the prior art, the embodiments of the present application have the following beneficial effects:

[0043] The present application obtains the electronic content observation value of the ionospheric piercing point and the ionospheric electron density background value of the three-dimensional network, assimilates the electronic content observation value and the ionospheric electron density background value to obtain an expression of the ionospheric electron density analysis value, constructs an observation error analysis function according to the expression of the ionospheric electron density analysis value, the electronic content observation value and the ionospheric electron density background value, takes the minimization of the observation error analysis function as an objective function, solves to obtain a target position variance factor, calibrates the ionospheric electron density through the expression of the ionospheric electron density analysis value according to the target position variance factor to obtain a corrected ionospheric electron density analysis value. The present application calibrates the calculation result of the ionospheric electron density, can more accurately describe the distribution of electrons in space, and thus improves the prediction accuracy of the model. BRIEF DESCRIPTION OF DRAWINGS

[0044] Fig. 1 is a flowchart of an ionospheric electron density calculation method according to an embodiment of the present application;

[0045] Fig. 2 is a flowchart of an electronic content calculation method according to an embodiment of the present application;

[0046] Fig. 3 is a structural diagram of an ionospheric electron density calculation device according to an embodiment of the present application;

[0047] Fig. 4 is a structural diagram of an electronic content calculation device according to an embodiment of the present application. DETAILED DESCRIPTION

[0048] With reference to the accompanying drawings, the technical solutions in the embodiments of the present application will be clearly and completely described in order to make the technical solutions in the embodiments of the present application apparent to those skilled in the art. Obviously, the described embodiments are only a part but not all of the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative efforts should fall into the scope of the present application.

[0049] Embodiment one

[0050] Please refer to Fig. 1, which is a flowchart of an ionospheric electron density calculation method provided by an embodiment of the present application, including:

[0051] S101, obtaining an electron content observation value of an ionospheric piercing point and ionospheric electron density background values of a three-dimensional network; wherein the three-dimensional regular network is provided by a global empirical model.

[0052] In step S101, an ionospheric piercing point is selected, and an electron content observation value of the ionospheric piercing point is obtained. The three-dimensional network provided by the global empirical model contains ionospheric electron density background values of each grid point, and ionospheric electron density background values of all grid points of the three-dimensional network are obtained.

[0053] In a preferred embodiment, before obtaining the electron content observation value of the ionospheric piercing point, it further includes:

[0054] obtaining a carrier phase observation value of the ionospheric piercing point by a dual-frequency GNSS receiver;

[0055] calculating the electron content observation value of the ionospheric piercing point according to the carrier phase observation value;

[0056] wherein the electron content observation value calculation formula is:

[0057] In the formula, V R represents the electron content observation value; L represents the carrier phase observation value; f1 and f2 are signal frequencies used by the dual-frequency receiver; B is a pseudo-range hardware delay; SDCB is a dual-frequency code bias of a satellite; and RDCB is a dual-frequency code bias of the dual-frequency receiver.

[0058] In the embodiment, the carrier phase observation value of the ionospheric piercing point is obtained by the dual-frequency GNSS receiver, and the electron content observation value at the ionospheric piercing point can be calculated.

[0059] In a preferred embodiment, the longitude resolution of the three-dimensional network is 0.5°, the latitude resolution is 0.5°, the height resolution is 50 kilometers, and the height range is from 100 kilometers above sea level to 2000 kilometers above sea level.

[0060] In the embodiment, the three-dimensional network obtained from the global empirical model is an equidistant regular spherical network, which is a three-dimensional regular network of ionospheric electron density. The longitude and latitude of the network are 0.5°×0.5°, respectively, and the network is composed of 39 height layers, from an altitude of 100 km to an altitude of 2000 km, with a fixed step of 50 km.

[0061] S102, according to the electron content observation value and the ionospheric electron density background value, data assimilation is carried out to obtain the expression of the ionospheric electron density analysis value; wherein the expression is the expression of the ionospheric electron density about the position variance factor.

[0062] It should be noted that the modeling time of the global empirical model is divided into 10-minute subintervals. In the middle of each subinterval, the three-dimensional regular network of ionospheric electron density is received from the global empirical model online service. In each one-hour interval, there are 6 subintervals. The electron content observation value of each subinterval is assimilated into the background ionospheric electron density grid in the middle of the subinterval, i.e., the three-dimensional regular network.

[0063] In a preferred embodiment, the data assimilation according to the electron content observation value and the ionospheric electron density background value comprises:

[0064] The longitude and latitude positions of the ionospheric piercing point are taken as the reference positions, and the electron content observation value and the ionospheric electron density background value are assimilated to obtain the following expression of the ionospheric electron density analysis value: A (λ i,j ,φ i,j ,h k )=N B (λ i,j ,φ i,j ,h k )+G(V R (λ0,φ0))-HN B (λ i,j ,φ i,j ,h k ); i=1...nI,j=1...nJ,k=1...K; G=BH T (R+HBH T ) -1 ; R=P -1 ; B=σ B I;

[0065] In the formula, λ i,j represents the longitude of the grid point with index i in the longitude direction and index j in the dimension direction in the three-dimensional network; and φ i,jdenotes the dimension of the grid point with index i in the longitude direction and index j in the latitude direction in the three-dimensional network; h k denotes the height of the grid point with index k in the height direction in the three-dimensional network; N A (λ i,j ,φ i,j ,h k ) denotes the ionospheric electron density analysis value at the position (λ i,j ,φ i,j ,h k ); N B (λ i,j ,φ i,j ,h k ) denotes the ionospheric electron density background value at the position (λ i,j ,φ i,j ,h k ); nI denotes the number of all grids in the longitude direction in the three-dimensional grid; nJ denotes the number of all grids in the latitude direction in the three-dimensional grid; K denotes the number of all grids in the height direction in the three-dimensional grid; G denotes the assimilation weight matrix; λ0 denotes the longitude of the reference position; φ0 denotes the latitude of the reference position; H denotes the observation value sub-matrix; B denotes the observation value coefficient matrix; R denotes the observation value covariance matrix; P denotes the observation value weight matrix; denotes the random error; σ B denotes the position method factor; I is a unit matrix.

[0066] It should be noted that, in this embodiment, the optimal interpolation method is used to map the ionospheric electron density background value on the equidistant regular spherical grid to the electron content observation value at the ionospheric piercing point, and the calibration is performed through data assimilation. The random error is assigned according to experience.

[0067] In this embodiment, when data assimilation is performed, the observation value covariance matrix and the observation value coefficient matrix B need to be constructed. In each sub-interval, the observation value covariance matrix can be obtained through inversion of the observation value weight matrix. When data assimilation is performed, the relationship between the background and the observation variance needs to be established, which requires a position variance factor. Finally, through data assimilation, the expression of the ionospheric electron density analysis value is constructed, which is an expression about the position variance factor.

[0068] S103, constructing an observation error analysis function according to the expression of the ionospheric electron density analysis value, the electron content observation value and the ionospheric electron density background value.

[0069] In step S103, in order to solve the optimization problem of finding the optimal position variance factor, it is necessary to construct an observation error analysis function according to the expression of the ionospheric electron density analysis value, the electron content observation value and the ionospheric electron density background value.

[0070] In a preferred embodiment, the expression of the observation error analysis function is: f(N A ) = ||V R (λ0, φ0) - HN A (λ i,j , φ i,j , h k )||2+ ||N A (λ i,j , φ i,j , h k ) - N B (λ i,j , φ i,j , h k )||;

[0071] In the formula, f(N A ) represents the observation error analysis function.

[0072] S104, taking the observation error analysis function minimization as the objective function, and solving the target position variance factor.

[0073] In step S104, the position variance factor that makes the observation error analysis function minimum is the target position variance factor to be found.

[0074] In a preferred embodiment, the taking the observation error analysis function minimization as the objective function, and solving the target position variance factor, comprises:

[0075] Under the condition that the position variance factor is greater than 0, taking the observation error analysis function minimization as the objective function, and solving the target position variance factor;

[0076] Wherein, the solving formula of the target position variance factor is:

[0077] In this embodiment, the point-in algorithm is used to solve the optimization problem, and the basis of this method is to add the constraint as a function to the objective function, and use the quasi-Newton method to minimize the newly obtained objective function.

[0078] S105, according to the target position variance factor, calculating the corrected ionospheric electron density analysis value through the expression of the ionospheric electron density analysis value.

[0079] In this embodiment, the target position variance is substituted into the ionospheric electron density expression to calculate the corrected ionospheric electron density analysis value.

[0080] Embodiment two

[0081] Please refer to Figure 2, which is a flow diagram of an electronic content calculation method according to an embodiment of the present application. The electronic content calculation method comprises the following steps:

[0082] In step S201, the grid where the ionospheric piercing point to be solved is located and the corrected ionospheric electron density analysis values of the grid points corresponding to all height layers overlapping with the grid where the ionospheric piercing point is located in the horizontal plane are obtained. The grid is a grid in the three-dimensional regular network provided by the global empirical model. The grid point is a grid point in the three-dimensional regular network provided by the global empirical model. The corrected ionospheric electron density analysis values are calculated according to the electronic content calculation method described in the above embodiment of the present application.

[0083] It should be noted that when solving the electronic content of the ionospheric piercing point, the influence of the ionospheric electron density of the four grid points of the grid where the ionospheric piercing point is located on the electronic content of each height layer should be considered. Each observation value projected vertically to the ground direction of each ionospheric piercing point may be affected by the prismatic electron density.

[0084] In step S201, the grid where all height layers vertically to the ground direction of the ionospheric piercing point to be solved are located is determined, including the grid where the ionospheric piercing point itself is located and the grid of other height layers overlapping with it in the horizontal plane. Then the corrected ionospheric electron density analysis values of the grid points corresponding to the grids are obtained. The grid points corresponding to the grids are the four vertices of the grid.

[0085] In step S202, the electronic content of the ionospheric piercing point is calculated according to all the corrected ionospheric electron density analysis values.

[0086] In a preferred embodiment, the electronic content of the ionospheric piercing point is calculated according to all the corrected ionospheric electron density analysis values, comprising:

[0087] For each height layer, the weighted average value of the corrected ionospheric electron density analysis value corresponding to the height layer is calculated;

[0088] The weighted average values corresponding to all height layers are summed to obtain the electronic content of the ionospheric piercing point;

[0089] The calculation formula of the electronic content of the ionospheric piercing point is as follows:

[0090] In the formula, V B represents the electronic content of the ionospheric piercing point; λ i,j represents the longitude of the grid point with index i in the longitude direction and index j in the dimension direction in the three-dimensional network; and φ i,jrepresents the dimension of the grid point with index i in the longitude direction and index j in the dimension direction in the three-dimensional network; h k represents the height of the grid point with index k in the height direction in the three-dimensional network; N A i,j , φ i,j , h k ) represents the ionospheric electron density analysis value at the position (λ i,j , φ i,j , h k ); w t,k represents the weight value of the tth corrected ionospheric electron density analysis value corresponding to the kth height layer; K represents the total number of height layers; T represents the total number of corrected ionospheric electron density analysis values corresponding to each height layer.

[0091] In the embodiment, the layer electron density of each height layer is first calculated, that is, the weighted average value of the corrected ionospheric electron density analysis value corresponding to each height layer is calculated; then the layer electron densities of all height layers are summed to obtain the electron content of the ionospheric piercing point to be solved.

[0092] Embodiment three

[0093] Please refer to Fig. 3, which is a structural schematic diagram of an ionospheric electron density calculation device provided by an embodiment of the present application, comprising: a first data acquisition module, a data assimilation module and a correction module.

[0094] The first data acquisition module is configured to acquire the electron content observation value of the ionospheric piercing point and the ionospheric electron density background value of the three-dimensional network; wherein the three-dimensional regular network is provided by a global empirical model.

[0095] The data assimilation module is configured to perform data assimilation according to the electron content observation value and the ionospheric electron density background value to obtain an expression of the ionospheric electron density analysis value; wherein the expression is an expression of the ionospheric electron density about the position variance factor.

[0096] The correction module is configured to construct an observation error analysis function according to the expression of the ionospheric electron density analysis value, the electron content observation value and the ionospheric electron density background value; to solve the target position variance factor by taking the minimization of the observation error analysis function as an objective function; and to calculate the corrected ionospheric electron density analysis value through the expression of the ionospheric electron density analysis value according to the target position variance factor.

[0097] Embodiment four

[0098] ​Please refer to Figure 4, it is a structural schematic diagram of an electronic content calculation device provided by an embodiment of the present application, the electronic content calculation device comprises a second data acquisition module and an electronic content calculation module.

[0099] The second data acquisition module is configured to acquire corrected ionospheric electron density analysis values of grid points corresponding to a grid where an ionospheric piercing point to be solved and all height layers overlapping with the grid in a horizontal plane; wherein the grid is a grid in a three-dimensional regular network provided by a global empirical model; the grid point is a grid point in the three-dimensional regular network provided by the global empirical model; and the corrected ionospheric electron density analysis values are calculated according to the electronic content calculation method as described in the above embodiment of the present application.

[0100] The electronic content calculation module is configured to calculate the electronic content of the ionospheric piercing point according to all the corrected ionospheric electron density analysis values.

[0101] It should be noted that the above-described device embodiments are only illustrative, wherein the units described as separate components can or can not be physically separated, and the components displayed as units can or can not be physical units, i.e., they can be located in one place or distributed on multiple network units. Part or all of the modules can be selected to achieve the purpose of the present embodiment according to actual needs. In addition, the connection relationship between the modules in the device embodiment provided by the present application indicates that there is a communication connection between them, which can be implemented as one or more communication buses or signal lines. Those skilled in the art can understand and implement it without creative labor.

[0102] Those skilled in the art can clearly understand that, in order to facilitate and be brief, the specific working process of the above-described device can refer to the corresponding process in the foregoing method embodiments, which will not be described here.

[0103] The above-described specific embodiments further detail the purpose, technical solutions and beneficial effects of the present application. It should be understood that the above-described specific embodiments are only for the present application and are not used to limit the protection scope of the present application. It is particularly pointed out that any modification, equivalent replacement, improvement, etc. made by those skilled in the art within the spirit and principles of the present application should be included in the protection scope of the present application.

[0104] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of this application; the use of terms "including," "comprising," or "having" and variations thereof herein is intended to cover the nature of the specification unless otherwise defined or indicated. Unless otherwise required by context, singular terms shall include pluralities and vice versa. The nomenclature used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of this application.

[0105] In the description of the embodiments of the present application, the technical terms "first", "second", etc. are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the technical features indicated.

Claims

1. An ionospheric electron density calculation method characterized by, The method comprises: obtaining an electron content observation value of an ionospheric piercing point and an ionospheric electron density background value of a three-dimensional network; wherein the three-dimensional regular network is provided by a global empirical model; performing data assimilation according to the electron content observation value and the ionospheric electron density background value to obtain an expression of an ionospheric electron density analysis value; wherein the expression is an expression of ionospheric electron density with respect to a position variance factor; constructing an observation error analysis function according to the expression of the ionospheric electron density analysis value, the electron content observation value and the ionospheric electron density background value; solving a target position variance factor by taking minimization of the observation error analysis function as an objective function; calculating a corrected ionospheric electron density analysis value according to the target position variance factor and the expression of the ionospheric electron density analysis value.

2. The ionospheric electron density calculation method according to claim 1, characterized by, Before obtaining the electron content observation value of the ionospheric piercing point, the method further comprises: obtaining a carrier phase observation value of the ionospheric piercing point by a dual-frequency GNSS receiver; calculating the electron content observation value of the ionospheric piercing point according to the carrier phase observation value; The electronic content observation value calculation formula is: where V R represents the electronic content observation value; L represents the carrier phase observation value; f1 and f2 are the signal frequencies used by the dual-frequency receiver; B is the pseudo-range hardware delay; SDCB is the dual-frequency code bias of the satellite; and RDCB is the dual-frequency code bias of the dual-frequency receiver.

3. The ionospheric electron density calculation method as claimed in claim 1, characterized by, the data assimilation according to the electron content observation value and the ionospheric electron density background value comprises: performing assimilation on the electron content observation value and the ionospheric electron density background value by taking the longitude and latitude position of the ionospheric piercing point as a reference position to obtain an expression of an ionospheric electron density analysis value as follows: N A (λ i,j ,φ i,j ,h k ) = N B (λ i,j ,φ i,j ,h k ) + G(V R (λ0,φ0)) - HN B (λ i,j ,φ i,j ,h k ); i = 1...nI, j = 1...nJ, k = 1...K; G = BH T (R + HBH T ) -1 ; R = P -1 ; B = σ B I; where λ i,j represents the longitude of the grid point with index i in the longitude direction and index j in the dimension direction in the three-dimensional network; φ i,j represents the dimension of the grid point with index i in the longitude direction and index j in the dimension direction in the three-dimensional network; h k represents the height of the grid point with index k in the height direction in the three-dimensional network; N A (λ i,j ,φ i,j ,h k ) represents the ionospheric electron density analysis value at the position (λ i,j ,φ i,j ,h k ); N B (λ i,j ,φ i,j ,h k ) represents the ionospheric electron density background value at the position (λ i,j ,φ i,j ,h k ); nI represents the number of all grids in the longitude direction in the three-dimensional grid; nJ represents the number of all grids in the dimension direction in the three-dimensional grid; K represents the number of all grids in the height direction in the three-dimensional grid; G represents the assimilation weight matrix; λ0 represents the longitude of the reference position; φ0 represents the dimension of the reference position; H represents the observation value sub-matrix; B represents the observation value coefficient matrix; R represents the observation value covariance matrix; and P represents the observation value weight matrix. denotes a random error; σ B denotes a position method factor; I is the identity matrix.

4. The ionospheric electron density calculation method according to claim 3, characterized by, The expression of the observation error analysis function is: f(N A ) = ||V R (λ0, φ0) - HN A (λ i,j , φ i,j , h k )||2+ ||N A (λ i,j , φ i,j , h k ) - N B (λ i,j , φ i,j , h k )||; where f(N A ) represents the observation error analysis function.

5. The ionospheric electron density calculation method according to claim 3, wherein, the solving of the target position variance factor by taking minimization of the observation error analysis function as an objective function comprises: solving the target position variance factor by taking minimization of the observation error analysis function as an objective function under the condition that the position variance factor is greater than 0; The solving formula of the target position variance factor is:

6. The ionospheric electron density calculation method of claim 1, wherein, the longitude resolution of the three-dimensional network is 0.5°, the latitude resolution is 0.5°, the height resolution is 50 kilometers, and the height range is from an altitude of 100 kilometers to an altitude of 2000 kilometers.

7. An electronic content calculating method characterized by comprising: The method comprises: obtaining corrected ionospheric electron density analysis values of grid points near an ionospheric piercing point to be solved; wherein the grid points near the ionospheric piercing point refer to grid points corresponding to a grid where the ionospheric piercing point is located and all height layers overlapping with the grid where the ionospheric piercing point is located in a horizontal plane; the grid is a grid in a three-dimensional regular network provided by a global empirical model; the grid point is a grid point in the three-dimensional regular network provided by the global empirical model; and the corrected ionospheric electron density analysis values are calculated according to any one of claims 1 to 6; calculating an electron content of the ionospheric piercing point according to all the corrected ionospheric electron density analysis values.

8. The electronic content calculating method of claim 7, wherein, The calculation of the electron content of the ionospheric piercing point according to all the corrected ionospheric electron density analysis values comprises: calculating a weighted average value of the corrected ionospheric electron density analysis value corresponding to each height layer; summing the weighted average values corresponding to all height layers to obtain the electron content of the ionospheric piercing point. The formula for calculating the electron content of the ionospheric piercing point is: In the formula, V B represents the electron content of the ionospheric piercing point; λ i,j represents the longitude of the grid point with index i in the longitude direction and index j in the dimension direction in the three-dimensional network; φ i,j represents the dimension of the grid point with index i in the longitude direction and index j in the dimension direction in the three-dimensional network; h k represents the height of the grid point with index k in the height direction in the three-dimensional network; N A (λ i,j ,φ i,j ,h k ) represents the ionospheric electron density analysis value at the position (λ i,j ,φ i,j ,h k ); w t,k represents the weight value of the kth height layer corresponding to the tth corrected ionospheric electron density analysis value; K represents the total number of height layers; and T represents the total number of corrected ionospheric electron density analysis values corresponding to each height layer.

9. An ionospheric electron density calculating apparatus characterized by comprising: The method comprises: The first data acquisition module, the data assimilation module and the correction module; The first data acquisition module is configured to acquire an electron content observation value of an ionospheric pierce point and an ionospheric electron density background value of a three-dimensional network; wherein the three-dimensional regular network is provided by a global empirical model; The data assimilation module is configured to perform data assimilation according to the electron content observation value and the ionospheric electron density background value to obtain an expression of an ionospheric electron density analysis value; wherein the expression is an expression of ionospheric electron density with respect to a position variance factor; The correction module is configured to construct an observation error analysis function according to the expression of the ionospheric electron density analysis value, the electron content observation value and the ionospheric electron density background value; to obtain a target position variance factor by solving a target function of minimizing the observation error analysis function; and to calculate a corrected ionospheric electron density analysis value by the expression of the ionospheric electron density analysis value according to the target position variance factor.

10. An electronic content calculating device, characterized by comprising: The method comprises: The second data acquisition module and the electron content calculation module; The second data acquisition module is configured to acquire a grid where an ionospheric pierce point to be solved is located and a corrected ionospheric electron density analysis value of a grid point corresponding to a grid on all height layers overlapping with the grid where the ionospheric pierce point is located in a horizontal plane; wherein the grid is a grid in a three-dimensional regular network provided by a global empirical model; the grid point is a grid point in the three-dimensional regular network provided by the global empirical model; and the corrected ionospheric electron density analysis value is calculated according to any one of claims 1 to 6; The electron content calculation module is configured to calculate the electron content of the ionospheric pierce point according to all the corrected ionospheric electron density analysis values.

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