Ionized layer product synthesis method and device based on differential ionized layer information

Abstract

The invention discloses an ionosphere product synthesis method and device based on differential ionosphere information, and belongs to the technical field of GNSS satellite ionospheres. The method comprises the following steps: extracting a DORIS dSTEC based on a DORIS system, wherein the dSTEC is oblique differential ionosphere information; extracting the residual error of the DORIS dSTEC and the GIM dSTEC to form a residual error sequence, and calculating the standard deviation of the residual error sequence; calculating normalized weight information, used for comprehensive calculation, of each GIM product; and calculating ionosphere grid point comprehensive TEC grid points one by one by using the normalized weight information, and generating an ionosphere comprehensive product. According to the method, independent DORIS differential ionosphere observation information is used, and integration of products is realized on the basis of realizing independent evaluation of the products.

Description

Technical Field

[0001] The present invention belongs to the technical field of GNSS satellite ionosphere, and in particular relates to an ionosphere product synthesis method and device based on differential ionosphere information. Background Art

[0002] The Global Navigation Satellite System (GNSS) is a satellite system that uses artificial satellite observations to obtain user time and space information. Accurate correction of ionospheric refraction delay is one of the effective means to improve positioning accuracy. Using the constructed ionospheric model to calculate the ionospheric total electron content (TEC) information and calculating the ionospheric delay effect at the corresponding frequency point through the frequency-related conversion factor is the main method to correct ionospheric errors and achieve high-precision positioning.

[0003] At present, many institutions have carried out research on global ionospheric TEC modeling methods and released ionospheric grid products. However, in actual applications, due to the influence of various factors such as communication environment and product accuracy changes, there are problems such as interruption of correction information products and poor correction accuracy. How to maintain the stability of real-time ionospheric services and ensure the accuracy of real-time ionospheric products has become one of the scientific issues of concern in current GNSS ionospheric work. The ionospheric product integration method is mainly based on GNSS slant differential ionospheric information (differential Slant Total Electron Content, dSTEC). It uses dSTEC extracted from GNSS reference stations that are not involved in ionospheric product modeling as a benchmark to evaluate the accuracy of multiple ionospheric products, and then determine the weight information of different ionospheric products, realize the integration of ionospheric products, and ensure the stability of ionospheric services. However, since the institutions did not disclose the GNSS reference station information they used when conducting ionospheric modeling, the independence of the GNSS reference stations used for integration cannot be guaranteed; on the other hand, both modeling and evaluation used GNSS-based ionospheric observation information. The potential correlation between the ionospheric observation information of the modeling station and the evaluation benchmark ionospheric observation information was absorbed by the evaluation results, resulting in inaccurate integrated weight information. Summary of the invention

[0004] In order to solve the above technical problems, the present invention provides an ionospheric product integration method and device based on differential ionospheric information, extracts high-precision DORIS dSTEC information, and improves the accuracy of ionospheric reference information used as a comprehensive benchmark; uses DORIS dSTEC information to determine the weight factors of various ionospheric products, and realizes normalization processing of the weight factors; produces ionospheric comprehensive products based on the weight factors, uses independent DORIS differential ionospheric observation information, and realizes product integration on the basis of realizing independent evaluation of the products.

[0005] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0006] A method for integrating ionospheric products based on differential ionospheric information, the method comprising:

[0007] Step 1, extracting DORIS dSTEC based on the DORIS system, wherein the dSTEC is oblique differential ionospheric information;

[0008] Step 2, extract the residuals of DORIS dSTEC and GIM dSTEC to form a residual sequence, and calculate the standard deviation of the residual sequence;

[0009] Step 3: Calculate the normalized weight information of each GIM product for comprehensive calculation;

[0010] Step 4: Using the normalized weight information, calculate the integrated TEC of the ionospheric grid points one by one to generate the integrated ionospheric product.

[0011] On the other hand, the present invention also provides an ionospheric product synthesis device based on differential ionospheric information, comprising:

[0012] An information extraction unit, used for extracting DORIS dSTEC based on the DORIS system, wherein the dSTEC is oblique differential ionospheric information;

[0013] A standard deviation acquisition unit is used to extract the residuals of DORIS dSTEC and GIM dSTEC to form a residual sequence and calculate the standard deviation of the residual sequence;

[0014] A calculation unit, used to calculate the normalized weight information of each GIM product for comprehensive calculation;

[0015] The product generation unit is used to calculate the comprehensive TEC of the ionospheric grid points by grid points using the normalized weight information to generate the comprehensive ionospheric products.

[0016] In a third aspect, the present invention provides an electronic device, comprising: one or more processors; a memory for storing one or more programs; wherein, when the one or more programs are executed by the one or more processors, the one or more processors implement the aforementioned ionospheric product integration method based on differential ionospheric information.

[0017] In a fourth aspect, the present invention provides a computer-readable storage medium having executable instructions stored thereon, which, when executed by a processor, enables the processor to implement the aforementioned ionospheric product integration method based on differential ionospheric information.

[0018] The beneficial effects of the present invention are:

[0019] The present invention extracts DORIS dSTEC, extracts the residuals of DORIS dSTEC and the global ionospheric grid product dSTEC, calculates the standard deviation of the residual sequence; calculates the normalized weight information of each GIM product for comprehensive calculation, generates an ionospheric comprehensive product, and improves the applicability of the invention. The ionospheric product comprehensive method involved in the present invention supports the comprehensive calculation of ionospheric products of different institutions, and does not require manual parameter changes. In addition, compared with the traditional ionospheric product comprehensive method, the method has improved accuracy, a wider calculation method, and better applicability. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a flow chart of an ionospheric product synthesis method based on differential ionospheric information of the present invention;

[0021] Figure 2 The annual average normalized weighted histogram provided by the embodiment of the present invention. DETAILED DESCRIPTION

[0022] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0023] The invention provides an ionospheric product synthesis method based on differential ionospheric information, extracts high-precision DORIS dSTEC information, and improves the precision of ionospheric reference information used as a comprehensive benchmark; uses DORIS dSTEC to determine weight factors of various ionospheric products, and realizes normalization processing of the weight factors; and produces ionospheric comprehensive products based on the weight factors; it can be seen that the invention realizes the generation of ionospheric comprehensive products through DORIS differential ionospheric information, improves the precision of ionospheric products, and further improves the precision of ionospheric total electron content model.

[0024] like Figure 1 As shown, a method for synthesizing ionospheric products based on differential ionospheric information of the present invention specifically comprises the following steps:

[0025] Step 1, extracting DORIS dSTEC based on the DORIS system, wherein the dSTEC is oblique differential ionospheric information;

[0026] It should be noted that the DORIS system is designed for precise orbit determination based on the Doppler effect principle. Since it uses dual-frequency signals for measurement, it can also be used for ionospheric TEC information extraction; although pseudo-range code observation information can be obtained from DORIS, its noise is too large (about 1 km) and is rarely used for absolute TEC extraction; compared with dual-frequency GNSS, the relative frequency ratio between the two frequencies of DORIS reaches about 5, and it can be expected that its ionospheric information detection is more precise and the measurement noise is smaller; and compared with GNSS observations, the DORIS beacon network provides more uniform global ionospheric coverage in continental and oceanic areas; therefore, DORIS can become a reliable data source for external verification of GNSS ionospheric models.

[0027] The extraction of DORIS dSTEC includes cycle slip detection and DORIS dSTEC calculation. The method of smoothing pseudorange without geometric combination observations adopts the carrier phase smoothing pseudorange method:

[0028] (1)

[0029] In the formula, For the moment DORIS dSTEC; is the ionospheric conversion factor; For the moment The geometric correction of is the DORIS geometry-free combined carrier phase observation, It is the moment when the satellite altitude angle is the maximum in the same arc segment. Ionospheric conversion factor satisfy:

[0030] (2)

[0031] In the formula, and is the frequency of DORIS dual-frequency observation.

[0032] The geometric correction is calculated by the following formula:

[0033] (3)

[0034] In the formula, is the satellite geometry correction, is the receiver geometry correction; is the satellite altitude angle.

[0035] Step 2: Extract the residuals of DORIS dSTEC and Global Ionosphere Map (GIM) dSTEC to form a residual sequence, and calculate the standard deviation of the residual sequence;

[0036] (4)

[0037] in, Latitude longitude Place dSTEC calculated from DORIS observations; Latitude longitude Place dSTEC calculated from GIM observations; For the The dSTEC calculated from the DORIS observations is consistent with that from the The residuals of dSTEC calculated from GIM observations; For the Standard deviation statistics of each GIM product; is the number of residual sequences.

[0038] Step 3: Calculate the normalized weight information of each GIM product for comprehensive calculation;

[0039] (5)

[0040] in, For the Normalized product weights of GIM products; is the number of GIM products participating in the product synthesis, and the other variables are the same as above. In this example, the annual average normalized weight of the GIM products participating in the product synthesis in 2022 is as follows Figure 2 shown.

[0041] Step 4: Using the normalized weight information, calculate the integrated TEC of the ionospheric grid points one by one to generate the integrated ionospheric product.

[0042] (6)

[0043] in, Latitude longitude time The vertical total electron content of the ionosphere at ; For the The latitude of the GIM calculation longitude time The vertical total electron content of the ionosphere at , and the other variables are the same as mentioned above.

[0044] In this example, the ionospheric composite product generated based on this method on the 190th day of 2022 was verified to meet the required accuracy.

[0045] On the other hand, the present invention provides an ionospheric product synthesis device based on differential ionospheric information, and the modules included in the device can implement the steps of the above method, specifically including:

[0046] An information extraction unit, used for extracting DORIS dSTEC based on the DORIS system, wherein the dSTEC is oblique differential ionospheric information;

[0047] A standard deviation acquisition unit is used to extract the residuals of DORIS dSTEC and GIM dSTEC to form a residual sequence and calculate the standard deviation of the residual sequence;

[0048] A calculation unit, used to calculate the normalized weight information of each GIM product for comprehensive calculation;

[0049] The product generation unit is used to calculate the comprehensive TEC of the ionospheric grid points by grid points using the normalized weight information to generate the comprehensive ionospheric products.

[0050] In a third aspect, the present invention provides an electronic device, comprising: one or more processors; a memory for storing one or more programs; wherein, when the one or more programs are executed by the one or more processors, the one or more processors implement the aforementioned ionospheric product integration method based on differential ionospheric information.

[0051] In a fourth aspect, the present invention provides a computer-readable storage medium having executable instructions stored thereon, which, when executed by a processor, enables the processor to implement the aforementioned ionospheric product integration method based on differential ionospheric information.

[0052] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for synthesizing ionospheric products based on differential ionospheric information, characterized in that: The method comprises: Step 1, extracting DORIS dSTEC based on the DORIS system, wherein the dSTEC is oblique differential ionospheric information; Step 2, extract the residuals of DORIS dSTEC and GIM dSTEC to form a residual sequence, and calculate the standard deviation of the residual sequence; Step 3: Calculate the normalized weight information of each GIM product for comprehensive calculation; Step 4: Using the normalized weight information, calculate the integrated TEC of the ionospheric grid points one by one to generate the integrated ionospheric product.

2. The ionospheric product integration method based on differential ionospheric information according to claim 1, characterized in that: In step 1, DORIS dSTEC is extracted based on the DORIS system: （1） In the formula, For the moment DORIS dSTEC; is the ionospheric conversion factor; For the moment The geometric correction of is the DORIS geometry-free combined carrier phase observation, is the moment when the satellite elevation angle is maximum in the same arc segment.

3. The ionospheric product integration method based on differential ionospheric information according to claim 2, characterized in that: The ionospheric conversion factor satisfy: （2） In the formula, and is the frequency of DORIS dual-frequency observation.

4. The ionospheric product integration method based on differential ionospheric information according to claim 3, characterized in that: The geometric correction is calculated by the following formula: （3） In the formula, is the satellite geometry correction, is the receiver geometry correction; is the satellite altitude angle.

5. The ionospheric product integration method based on differential ionospheric information according to claim 1, characterized in that: The residuals of DORIS dSTEC and GIM dSTEC extracted in step 2 are: （4） in, Latitude longitude Place dSTEC calculated from DORIS observations; Latitude longitude Place dSTEC calculated from GIM observations; For the The dSTEC calculated from the DORIS observations is consistent with that from the The residuals of dSTEC calculated from GIM observations; For the Standard deviation statistics of each GIM product; is the number of residual sequences.

6. The ionospheric product integration method based on differential ionospheric information according to claim 5, characterized in that: The normalized weight information in step 3 satisfies: （5） in, For the Normalized product weights of each GIM product; It is the number of GIM products participating in product integration.

7. The ionospheric product integration method based on differential ionospheric information according to claim 6, characterized in that: The comprehensive TEC at the grid point in step 4 satisfies: （6） in, Latitude longitude time The vertical total electron content of the ionosphere at ; For the The latitude of GIM product calculation longitude time The vertical total electron content of the ionosphere at .

8. An ionospheric product synthesis device based on differential ionospheric information, characterized in that: include: An information extraction unit, used for extracting DORIS dSTEC based on the DORIS system, wherein the dSTEC is oblique differential ionospheric information; A standard deviation acquisition unit is used to extract the residuals of DORIS dSTEC and GIM dSTEC to form a residual sequence and calculate the standard deviation of the residual sequence; A calculation unit, used to calculate the normalized weight information of each GIM product for comprehensive calculation; The product generation unit is used to calculate the comprehensive TEC of the ionospheric grid points by grid points using the normalized weight information to generate the comprehensive ionospheric products.

9. An electronic device, characterized in that: include: one or more processors; A memory for storing one or more programs; Wherein, when one or more programs are executed by the one or more processors, the one or more processors implement the ionospheric product integration method based on differential ionospheric information as described in any one of claims 1-7.

10. A computer-readable storage medium, characterized in that: Executable instructions are stored thereon, and when the instructions are executed by the processor, the processor can implement the ionospheric product integration method based on differential ionospheric information as described in any one of claims 1-7.

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