Total electron amount calculation and correction method for space-based detection ionosphere data

Abstract

The invention provides a total electron amount calculation and correction method for space-based detection ionosphere data. The method comprises the following steps: converting an earth-fixed coordinate system; calculating collision parameters; sorting collision parameters and phase arrays; performing phase calibration; and obscuration correction of the total electron amount. The method has the beneficial effects that according to the forward relation between the total electron content of the ionosphere and the additional time delay of radio wave propagation caused by the ionosphere, the accurate total electron content is obtained from the satellite-ground radio detection ionosphere data by using a calculation and correction method; the method is of great significance in the aspects of satellite positioning navigation radio wave correction, space environment monitoring and the like.

Description

Technical Field

[0001] The present invention belongs to the field of ionospheric sounding, and particularly relates to a method for calculating and correcting the total electron content of space-based ionospheric sounding data. Background Art

[0002] The total electron content (TEC) is the total number of free electrons contained in a column with a bottom area of 1 in the observation line-of-sight direction. The ionosphere is an ionized region of the Earth's atmosphere, starting from about 50 km to 60 km above the ground and extending to the high-altitude airspace of the Earth's upper atmosphere at about 1000 km. There are quite a lot of free electrons and ions in it, which can change the propagation speed of radio waves, causing refraction, reflection and scattering. The total electron content of the ionosphere is an ionospheric parameter that describes the state and characteristics of the ionosphere, and at the same time reflects the influence of the ionosphere on the propagation of radio waves. The occultation sounding of the total electron content of the ionosphere is mainly obtained by inverting the navigation signals transmitted by the Global Navigation Satellite System (GNSS) received by a low-orbit satellite. The rapid development of satellite-related technologies enables the transmission of space-ground information through radio wave bands above ultra-high frequency. During the transmission process, it will mainly propagate through the ionosphere in a transmission manner. The emergence of the important ionospheric parameter of the total electron content TEC of the ionosphere is of great significance for reflecting the influence of the ionosphere during the propagation process. The GNSS occultation sounding technology has the characteristics of low power consumption, light weight, and flexible sounding all day and all weather. The obtained data has advantages such as global distribution and high spatio-temporal resolution. With the completion of a large number of GNSS occultation sounding satellite constellations, the GNSS occultation sounding data processing technology also needs to be further developed and improved. Based on the urgent need for ionospheric information from space-ground radio wave propagation, according to the fact that the total electron content of the ionosphere is proportional to the additional time delay of radio wave propagation caused by the ionosphere, a method is used to calculate and obtain the total electron content from space-ground radio sounding ionospheric data and on this basis, a phase calibration method is used to correct it to obtain more accurate results, which is of great significance in aspects such as radio wave correction for satellite positioning and navigation and space environment monitoring. Summary of the Invention

[0003] In view of this, the present invention aims to propose a method for calculating and correcting the total electron content of space-based ionospheric sounding data to meet the urgent need for obtaining ionospheric information based on space-ground radio wave propagation.

[0004] To achieve the above object, the technical solution of the present invention is realized as follows: A method for calculating and correcting the total electron content of space-based ionospheric sounding data includes the following steps: S1. Geocentric coordinate system conversion; S2. Calculation of collision parameters; S3. Sorting of collision parameters and phase arrays; S4. Phase calibration; S5, occultation correction total electron content; In step S3, the impact parameter and phase array sorting includes: S31, identifying the sample with the maximum impact parameter and determining whether the parameter sample contains a positive elevation angle sample; S32, for the occultation side negative elevation angle data and the auxiliary side positive elevation angle data, reordering the impact parameter and phase array into separate arrays; S33, reordering the satellite position and the tangent point coordinates and storing them on the occultation side; In step S4, the phase calibration includes: S41, performing altitude range occultation screening based on the tangent point altitude and the satellite orbital altitude; S42, performing time difference occultation screening based on the sampling rate; S43, spline interpolating the phase data samples on the auxiliary side onto the impact parameter grid on the occultation side; S44, calibrating the phase data according to the selected calibration mode.

[0005] Furthermore, in step S1, the geodetic coordinate system transformation includes: Geocentric inertial coordinate system: The origin of the coordinate system is the Earth's center of mass, the z-axis points along the Earth's axis of rotation towards the conventional geodetic pole, the x-axis lies in the equatorial plane and points towards the vernal equinox, and the y-axis conforms to the right-handed Cartesian coordinate system; S11, estimating the position and velocity of the satellite orbiting the Earth in the geocentric inertial coordinate system; S12, converting the coordinates in the geocentric inertial coordinate system to the actual geographical coordinates; S13, converting the satellite position in Cartesian coordinates from the geocentric inertial coordinate system frame to the geodetic reference frame.

[0006] Furthermore, in step S2, the impact parameter calculation includes: Based on the assumptions of local spherical symmetry and the straight-line propagation of GNSS signals, the impact parameter characterizes the perpendicular distance from the Earth's center to the line connecting the LEO satellite and the GNSS occultation, and the calculation formula is as follows: (1); In the formula, is the angle between the GNSS satellite and the LEO satellite with respect to the vector connecting the Earth's center; and are the geocentric radius vectors of the GNSS satellite and the LEO satellite respectively.

[0007] Furthermore, in step S5, the occultation correction total electron content includes: The calibrated occultation TEC is obtained from the calibrated phase It is calculated that the calculation formula is as follows: (2); In the formula, and are the L1 and L2 carrier frequencies of GPS respectively. When is related to the L1 - L2 phase, this formula holds.

[0008] Furthermore, in step S31, identifying the sample with the maximum impact parameter includes: If the collected data contains positive elevation angle samples, the maximum impact parameter is at the middle position of the impact parameter array. If only negative elevation angle data is collected, the maximum impact parameter is at or near the first sample.

[0009] Furthermore, in step S41, altitude range occultation screening includes: S412. Find the occultations whose tangent point altitude covers the default altitude range from 150 km below the satellite orbit altitude to 1 km, and exclude the occultations not within this altitude range; S413. If calibration is performed using the data on the auxiliary side, it is required that the impact parameter range on the auxiliary side includes the impact parameter on the occultation side, and exclude the occultations that do not meet the requirements.

[0010] Furthermore, in step S42, time difference occultation screening includes: Perform time interval checks on both the occultation side and the auxiliary side. If any time interval is detected, the occultation is excluded.

[0011] Furthermore, in step S43, spline interpolation includes: Interpolate the square of the phase as a function of the impact parameter.

[0012] Furthermore, in step S44, calibrating the phase data includes: S441. Calibration mode 1 includes subtracting the interpolated auxiliary phase data from the phase data on the occultation side; S442. If there is no data on the auxiliary side, select to use calibration mode 0, and subtract the observed phase of the maximum impact parameter from the phase data of all samples on the occultation side.

[0013] Furthermore, the TEC calculated by formula (1) is the total amount of electrons in the entire path from the GNSS satellite to the LEO satellite.

[0014] Compared with the prior art, the method for calculating and correcting the total amount of electrons in space - based ionospheric detection data according to the present invention has the following beneficial effects: Based on the positive relationship between the total electron content in the ionosphere and the additional time delay of radio wave propagation caused by the ionosphere, the present invention uses a calculation and correction method to obtain accurate total electron content from satellite-ground radio sounding ionospheric data, which is of great significance in aspects such as radio wave correction for satellite positioning and navigation and space environment monitoring. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The drawings forming a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments and descriptions thereof of the present invention are used to explain the present invention and do not constitute an improper limitation to the present invention. In the drawings: Figure 1 It is a schematic diagram of the calculation principle of the collision parameter and phase array sorting described in the embodiment of the present invention; Figure 2 It is a schematic diagram of the phase calibration principle described in the embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0016] It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other.

[0017] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus cannot be understood as a limitation to the present invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first", "second", etc. may explicitly or implicitly include one or more of such features. In the description of the present invention, unless otherwise specified, the meaning of "a plurality" is two or more.

[0018] In the description of the present invention, it should be noted that, unless otherwise clearly defined and limited, the terms "installed", "connected", "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood through specific situations.

[0019] The present invention will be described in detail below with reference to the drawings and in combination with the embodiments.

[0020] As Figures 1 to 2 shown, a method for calculating and correcting the total electron content of ionospheric data detected by a space-based detector includes the following steps: S1. Geodetic coordinate system conversion; S2. Calculation of collision parameter; S3. Sorting of collision parameters and phase arrays; S4. Phase calibration; S5. Correcting the total electron content of occultation.

[0021] The specific implementation method is as follows: 1. Geodetic coordinate system conversion A coordinate system that remains stationary or moves in a uniform straight line (without acceleration) in space is called an inertial coordinate system. Usually, the satellite orbit is in the Earth-centered inertial coordinate system (ECI). The position and velocity of the satellite orbiting the Earth are estimated in the inertial system. The coordinate origin of the Earth-centered inertial coordinate system is the Earth's center of mass; the z-axis points along the Earth's rotation axis to the conventional geodetic pole; the x-axis is in the equatorial plane and points to the vernal equinox; the y-axis conforms to the right-handed Cartesian coordinate system. In actual calculations, the coordinates in the above ECI are converted into actual geographical coordinates, and the rotation of the Earth during occultation is considered, which is related to the Julian day and the universal time (UT) of the occultation event. Then, the satellite position in Cartesian coordinates is converted from the ECI frame to the geodetic reference frame.

[0022] 2. Calculation of collision parameter Based on the assumptions of local spherical symmetry and the straight-line propagation of GNSS signals, the collision parameter characterizes the perpendicular distance from the Earth's center to the line connecting the LEO satellite and the GNSS occultation. The specific calculation formula of the collision parameter is as follows: (1) In the formula is the angle between the GNSS satellite and the LEO satellite with respect to the vector connecting the Earth's center; and are the geocentric radii vectors of the GNSS satellite and the LEO satellite, respectively. The TEC calculated by Equation (1) is the total electron content of the entire path from the GNSS satellite to the LEO satellite. However, since the maximum value of the collision parameter can only reach the LEO orbit altitude , the upper limit of integration can only be taken to , so the truly required TEC is the total electron content of the path from the inversion altitude to this section.

[0023] 3. Sorting of collision parameters and phase arrays Re-sort the collision parameters and phase arrays on both sides of the maximum collision parameter. Specifically as follows Figure 1As shown, samples with the maximum impact parameter are identified. When the collected data contains samples with positive elevation angles, the maximum impact parameter usually appears at the middle position of the impact parameter array. In the case where only negative elevation angle data is collected basically, the maximum impact parameter will be at or near the first sample (for a given occultation). Then, for the negative elevation angle data (occultation side) and positive elevation angle data (auxiliary side), the impact parameter and phase array (as well as time series) are reordered into separate arrays. The satellite position and tangent point coordinates are also reordered and stored on the occultation side. Eventually, all arrays are ordered such that the first sample is the one with the minimum impact parameter.

[0024] 4. Phase Calibration As follows Figure 2 As shown, it is necessary to check whether there is sufficient altitude range and time difference before performing phase calibration. First, find the occultations whose tangent point altitude covers the altitude range from 150 km (default value; can be changed in the parms file) below the satellite orbit altitude to 1 km (default value; can be changed in the parms file). If the data does not fall within this range, the occultation is excluded. If calibration is performed using the data on the auxiliary side (controlled by the input parameter in the parms file), the impact parameter range on the auxiliary side needs to cover the impact parameter on the occultation side, otherwise the occultation is discarded. In terms of checking the time difference, since the time interval may be related to large cycle slips, the time interval is checked for both the occultation side and the auxiliary side. The identification of the time difference depends on the sampling rate (the sampling rate must be correctly specified in the parms file), and if any time interval occultation is detected, the occultation will be discarded. To calibrate the phase, the phase data samples on the auxiliary side are spline interpolated onto the impact parameter grid on the occultation side. Among them, to correctly handle the functional form of the phase near the orbital altitude (square root form 0), the square of the phase is interpolated as a function of the impact parameter. Then, the phase data is calibrated according to the selected calibration mode (0 or 1 in the parms file). Calibration mode 1 includes subtracting the interpolated auxiliary phase data from the phase data on the occultation side. Assuming that the occultation plane and the low Earth orbit plane are close to coinciding and the ionosphere has no obvious change during data collection. Therefore, mode 1 calibration allows the estimation of the occultation TEC within the LEO orbit, that is, the TEC excluding the TEC between the GPS satellite altitude and the LEO altitude on the auxiliary side. When there is no data on the auxiliary side, calibration mode 0 can be selected, also known as quasi-calibration. This calibration method is slightly more complex than mode 1 calibration. When calibration mode 0 is selected, the observed phase of the maximum impact parameter is subtracted from the phase data of all samples on the occultation side.

[0025] 5. Occultation Correction Total Electron Content The calibrated occultation TEC (in TECU = 10 16 electron / m 2) Calculated from the calibrated phase is obtained as follows: (2) where and are the L1 and L2 carrier frequencies of GPS respectively. This form holds when is related to the L1 - L2 phase, which is the only available processing type at present (always select processing type = 0 in the parms input file).

[0026] Example 1: 1. Geodetic coordinate system conversion function Obtain the occultation ionospheric sounding data of Yunyao - 1 on March 20, 2025, convert the longitude in ECI to the actual geographic longitude, and considering the rotation of the Earth during the occultation, convert the satellite position in Cartesian coordinates from the ECI frame to the geodetic reference frame. By converting the longitude in ECI (Earth - centered inertial coordinate system) to the actual geographic longitude and considering the Earth's rotation to convert the satellite position from the ECI frame to the geodetic reference frame, it is possible to establish an accurate connection between the data and the actual geographical location of the Earth. This helps to more intuitively analyze the occultation ionospheric sounding data. For example, the ionospheric information detected by the satellite can be accurately corresponded to specific regions on the Earth, providing more accurate geolocation data support for radio wave correction of satellite positioning and navigation, space environment monitoring, etc., and improving the accuracy of research and applications.

[0027] 2. Maximum impact parameter sample identification function Identify the samples containing the maximum impact parameter and determine whether the parameter samples contain positive elevation angle samples. When the collected data contains samples with positive elevation angles, the maximum value of the impact parameter usually appears in the middle position of the impact parameter array. In the case where only negative elevation angle data is basically collected, the maximum impact parameter will be at or near the first sample (for a set occultation). This can accurately identify the samples containing the maximum impact parameter and determine whether they contain positive elevation angle samples, which helps to distinguish different types of occultation data collection situations. In different elevation angle data collection scenarios, it can quickly locate the position of the maximum impact parameter, providing key information for subsequent data processing and analysis, improving the pertinence and efficiency of data processing, and avoiding blindly searching for key parameters in complex data.

[0028] 3. Impact parameter and phase sequence sorting function For the negative elevation angle data (occultation side) and positive elevation angle data (auxiliary side), the impact parameter and the phase array (as well as the time series) are reordered into separate arrays. The satellite position and the tangent point coordinates are also reordered and stored on the occultation side. Eventually, all arrays are ordered such that the first sample is the one with the smallest impact parameter. The impact parameter, phase array, time series, satellite position, and tangent point coordinates are reordered so that all arrays are ordered and the first sample has the smallest impact parameter. Such a sorting method facilitates subsequent data processing and analysis. For example, when performing operations, ordered data can reduce the complexity of the algorithm, improve the calculation efficiency, and also facilitate data comparison and screening.

[0029] 4. Altitude Range Occultation Screening Function Find the occultations where the tangent point altitude covers the altitude range from 150 km (default value; can be changed in the parms file) below the satellite orbit altitude to 1 km (default value; can be changed in the parms file). If the data does not fall within this range, the occultation is excluded. If calibration is performed using the data from the auxiliary side (controlled by the input parameter in the parms file), the impact parameter range of the auxiliary side needs to cover the impact parameter of the occultation side; otherwise, the occultation is discarded. By screening occultations through setting the tangent point altitude range, data that does not meet the requirements can be excluded, reducing the interference of irrelevant data on the analysis results. Ensure that the data used for research and analysis is concentrated within a specific altitude range, improving the quality and validity of the data. At the same time, checking the impact parameter range of the auxiliary side data ensures the accuracy of data calibration and makes the analysis results more reliable.

[0030] 5. Time Difference Occultation Function Perform a time difference check on the data because the time interval may be related to large cycle slips, and the time interval check is performed on both the occultation side and the auxiliary side of the data. The identification of the time difference depends on the sampling rate (the sampling rate must be correctly specified in the parms file), and if any time interval occultation is detected, the occultation will be discarded. By performing a time difference check on the data, data problems related to large cycle slips can be discovered in a timely manner. Since cycle slips may affect the accuracy and continuity of the data, by discarding the occultation data with time interval problems, the quality of the analysis data can be guaranteed, avoiding incorrect conclusions caused by data errors, and improving the credibility of the research results.

[0031] 6. Spline Interpolation Function Spline interpolate the phase data of the auxiliary side onto the impact parameter grid of the occultation side. Among them, to correctly handle the functional form (square root form 0) of the phase close to the orbit altitude, the square of the phase is interpolated as a function of the impact parameter.

[0032] A 300-level regular height grid is defined to interpolate the orbital coordinates and tangent point coordinates.

[0033] In this way, the spline interpolation of the phase data on the auxiliary side is interpolated onto the impact parameter grid on the occultation side, and the orbital coordinates and tangent point coordinates are interpolated, which can establish a smoother connection between different data. In particular, interpolating the phase square can better handle the functional form close to the orbital height, improving the resolution and accuracy of the data. Defining a regular height grid for interpolation helps to unify the data format and scale, facilitating subsequent data analysis and comparison.

[0034] 7. Phase calibration function Calibrate the phase data according to the selected calibration mode (0 or 1 in the parms file). Calibration mode 1 includes subtracting the interpolated auxiliary phase data from the occultation side phase data. It is assumed that the occultation plane and the low Earth orbit plane are nearly coincident, and the ionosphere does not change significantly during data collection. Therefore, mode 1 calibration allows the estimation of the occultation TEC within the LEO orbit, that is, the TEC excluding the TEC between the GPS satellite height and the auxiliary side LEO height. When there is no data on the auxiliary side, calibration mode 0 can be selected, also known as quasi-calibration. This calibration method is slightly more complex than mode 1 calibration. When calibration mode 0 is selected, the observed phase of the maximum impact parameter is subtracted from the phase data of all samples on the occultation side. By providing two calibration modes for selection, flexible calibration can be performed according to different data situations. Calibration mode 1 can estimate the occultation TEC within the LEO orbit, excluding the TEC interference between the GPS satellite height and the auxiliary side LEO height, making the analysis result more focused on the ionospheric information in a specific area. Calibration mode 0 is applicable to the case without auxiliary side data. Although it is slightly more complex, it can ensure the calibration of phase data under different data conditions, improving the adaptability and accuracy of data processing.

[0035] 8. Occultation total electron content correction function The calibrated occultation TEC is obtained by calculating the occultation TEC using the calibrated phase ∆L. In this way, accurate occultation TEC data can be obtained, which is of great significance for studying the ionospheric electron density distribution, space weather changes, etc., providing more reliable basic data for ionospheric physics research and related applications.

[0036] Advantages and beneficial effects of the present invention: According to the positive relationship between the total ionospheric electron content and the additional time delay of radio wave propagation caused by the ionosphere, the present invention uses a calculation and correction method to obtain accurate total electron content from satellite-ground radio sounding ionospheric data, which is of great significance in aspects such as radio wave correction for satellite positioning and navigation, and space environment monitoring.

[0037] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for calculating and correcting the total electron content of ionospheric data detected by a space-based detector, characterized in that: It includes the following steps: S1. Geodetic coordinate system transformation; S2. Impact parameter calculation; S3. Sorting of impact parameters and phase arrays; S4. Phase calibration; S5. Occultation correction of the total electron content; In step S3, the sorting of impact parameters and phase arrays includes: S31. Identifying the sample with the maximum impact parameter and determining whether the parameter sample contains a positive elevation angle sample; S32. For the negative elevation angle data on the occultation side and the positive elevation angle data on the auxiliary side, re-sorting the impact parameters and phase arrays into separate arrays; S33. Re-sorting the satellite position and the tangent point coordinates and storing them on the occultation side; In step S4, the phase calibration includes: S41. Performing occultation screening within a height range according to the tangent point height and the satellite orbit height; S42. Performing occultation screening based on the time difference according to the sampling rate; S43. Spline interpolating the phase data samples on the auxiliary side onto the impact parameter grid on the occultation side; S44. Calibrating the phase data according to the selected calibration mode.

2. The method for calculating and correcting the total electron content of the ionosphere data detected by a space-based detector according to claim 1, wherein: In step S1, the geodetic coordinate system transformation includes: Geocentric inertial coordinate system: The origin of the coordinate system is the Earth's centroid, the z-axis points along the Earth's rotation axis towards the conventional geodetic pole, the x-axis lies in the equatorial plane and points towards the vernal equinox, and the y-axis conforms to the right-handed Cartesian coordinate system; S11. Estimating the position and velocity of the satellite orbiting the Earth in the geocentric inertial coordinate system; S12. Converting the coordinates in the geocentric inertial coordinate system to the actual geographic coordinates; S13. Converting the satellite position in Cartesian coordinates from the geocentric inertial coordinate system frame to the geodetic reference frame.

3. The method for calculating and correcting the total electron content of ionospheric data detected by a space-based detector according to claim 1, wherein: In step S2, the impact parameter calculation includes: Based on the assumptions of local spherical symmetry and the straight-line propagation of GNSS signals, the impact parameter characterizes the perpendicular distance from the Earth's center to the line connecting the LEO satellite and the GNSS occultation, and the calculation formula is as follows: (1)； In the formula, is the angle between the GNSS satellite and the LEO satellite with respect to the vector connecting the center of the Earth; and are the geocentric radius vectors of the GNSS satellite and the LEO satellite, respectively.

4. The total electron content calculation and correction method for ionospheric data detected by space-based detection according to claim 1, characterized in that: In step S5, the occultation correction of the total electron content includes: The calibrated occultation TEC is calculated from the calibrated phase as follows: (2)； In the formula, and are the L1 and L2 carrier frequencies of GPS respectively. This formula holds when is related to the L1 - L2 phase.

5. A method for calculating and correcting the total electron content of ionospheric data detected by a space-based detector, characterized in that: In step S31, the identification of the sample with the maximum impact parameter includes: If the collected data contains positive elevation angle samples, the maximum impact parameter is at the middle position of the impact parameter array; if only negative elevation angle data is collected, the maximum impact parameter is at or near the first sample.

6. The method for calculating and correcting the total electron content of the ionosphere detected by a space-based detector according to claim 1, wherein: In step S41, the occultation screening within a height range includes: S412. Finding the occultations where the tangent point height covers the default height range from 150 km below the satellite orbit height to 1 km and excluding the occultations outside this height range; S413. If the data on the auxiliary side is used for calibration, it is required that the impact parameter range on the auxiliary side includes the impact parameters on the occultation side, and the occultations that do not meet the requirements are excluded.

7. A method for calculating and correcting the total electron content of ionospheric data detected by a space-based detector, characterized in that: In step S42, the occultation screening based on the time difference includes: Performing a time interval check on both the occultation side and the auxiliary side. If any time interval is detected, the occultation is excluded.

8. A method for calculating and correcting the total electron content of ionospheric data detected by a space-based detector, characterized in that: In step S43, the spline interpolation includes: Interpolating the square of the phase as a function of the impact parameter.

9. The method for calculating and correcting the total electron content of ionospheric data detected by a space-based detector according to claim 1, characterized in that: In step S44, the calibration of the phase data includes: S441. Calibration mode 1 includes subtracting the interpolated auxiliary phase data from the phase data on the occultation side; S442. If there is no data on the auxiliary side, select to use calibration mode 0, and subtract the observed phase of the maximum impact parameter from the phase data of all samples on the occultation side.

10. A method for calculating and correcting the total electron content of ionospheric data detected by a space-based detector according to claim 3, characterized in that: The TEC calculated by formula (1) is the total electron content of the entire path from the GNSS satellite to the LEO satellite.

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