Satellite Ka-band inter-satellite link antenna phase center change calibration method and system

Abstract

The invention provides a satellite Ka wave band inter-satellite link antenna phase center change calibration method and system, and the method comprises the steps: collecting L wave band observation data and Ka wave band inter-satellite link observation data of a ground observation station, carrying out the gross error elimination, cycle slip detection, epoch normalization and combination, and generating a clock error-free and geometry-free observation quantity; analyzing the variation range of a nadir angle and an azimuth angle of the observation data, constructing a piecewise linear original PCV function model taking the nadir angle and the azimuth angle as independent variables, and synchronously resolving original PCV parameters of a satellite L / Ka wave band in a joint orbit determination process; decomposing the original PCV into a smooth PCV and a corresponding Z-direction PCO by adopting a least square separation technology, performing interpolation on a PCV value based on a discrete grid, and establishing a final PCV grid correction model; joint orbit determination error correction is introduced into the PCV correction model, a new round of joint orbit determination is carried out, the satellite L / Ka waveband PCO correction amount is calculated, and high-precision in-orbit calibration of the satellite Ka waveband inter-satellite link antenna phase center change is achieved.

Description

Technical Field

[0001] The present invention relates to the field of satellite positioning and navigation technology, and in particular to a method and system for calibrating phase center changes of satellite Ka-band inter-satellite link antennas. Background Art

[0002] To overcome the constraints imposed by the distribution of ground-based monitoring stations on the accuracy of satellite orbit and clock calculations, and the performance of navigation system services, my country independently developed Ka-band intersatellite ranging and communication technology, making BeiDou-3 the world's first satellite navigation system to achieve full-constellation intersatellite links. As the core equipment for intersatellite links, Ka-band phased array antennas require precise calibration of their antenna phase centers (i.e., the electromagnetic radiation equivalent point) to ensure high-precision ranging. However, during satellite in-orbit operation, factors such as fuel consumption can cause antenna phase center offsets (PCO) and phase center variations (PCV) to deviate significantly from ground-based calibration values. Existing ground-based calibration only provides initial PCO parameters and does not account for the effects of PCV in the on-orbit environment. This makes it difficult to accurately model measurement errors in intersatellite ranging data applications, hindering further improvements in overall system performance.

[0003] At present, there is no research on the on-orbit calibration of the phase center of the BeiDou-3 system's Ka-band inter-satellite link observations, but the L-band antenna phase center correction algorithm has become mature and can provide a reference for Ka-band calibration. L-band calibration usually relies on observation data from ground or low-orbit satellite tracking. While jointly solving the orbit, clock error and other geodetic parameters, it is necessary to overcome the high correlation between antenna parameters and parameters such as orbit, clock error and reference frame scale. In contrast, Ka-band inter-satellite ranging is a two-way link observation, which not only includes the antenna corrections of two satellites at the same time, but also because the nadir angle of inter-satellite observations has a large range of variation (up to The diversity of satellites in different orbit types and the number of satellites in different orbit types poses a greater challenge to PCV model construction. Furthermore, to achieve unified processing and deep integration of BeiDou satellite L-band satellite-to-ground data and Ka-band inter-satellite link data, Ka-band phase center corrections must be unified with L-band calibration results in the same Earth reference frame.

[0004] Therefore, it is necessary to propose a calibration method and system for the phase center variation of the satellite Ka inter-satellite link antenna. By fusing L / Ka multi-frequency observation data, a PCV model estimation method suitable for inter-satellite two-way observation values ​​is constructed, and the unification with the L-band earth reference frame is achieved, thereby improving the inter-satellite ranging accuracy and providing technical support for the high-precision application of the BeiDou system. Summary of the Invention

[0005] The present invention provides a method and system for calibrating the phase center change of satellite Ka-band inter-satellite link antennas, which are used to overcome the defects in the existing technology, realize high-precision on-orbit calibration, fill the gap in Ka-band antenna calibration, improve the inter-satellite link data processing error model, and lay the foundation for the deep fusion processing of BeiDou-3 satellite L-band satellite-to-ground and Ka inter-satellite link data.

[0006] In a first aspect, the present invention provides a method for calibrating a phase center variation of a satellite Ka-band intersatellite link antenna, comprising: Collect L-band observation data from ground stations, remove gross errors and detect cycle slips; collect Ka-band intersatellite link observation data, remove gross errors, perform epoch normalization and combination on the two-way observation data, and generate clock-error-free / geometry-free observation quantities for the resolved epochs; The nadir angle and azimuth variation ranges of L / Ka observation data were analyzed, and a piecewise linear function model of the PCV of the two antennas was constructed. Based on the L / Ka observation data, the original PCV parameters of the satellite L / Ka band were calculated while performing joint orbit determination. The smoothest PCV and the corresponding Z-PCO are separated from the original PCV parameters using the least squares separation method. A PCV grid correction model is established based on the PCV values ​​at discrete satellite nadir angles and azimuth angles. The established PCV grid correction model is applied to the joint orbit determination error correction, a new round of joint orbit determination is carried out and the PCO correction of the satellite L / Ka band is solved.

[0007] According to a method for calibrating the phase center variation of a satellite Ka-band intersatellite link antenna provided by the present invention, L-band observation data of a ground station is collected to remove gross errors and detect cycle slips, including:

[0008] in, Respectively represent the frequency, satellite and receiver serial number, Indicates the frequency satellites To the receiver The L-band pseudorange observation value of is the satellite centroid position represented by the vector; Correction for satellite antenna phase center; is the position of the receiver antenna phase center represented by a vector. The correction of the receiver antenna phase center is not considered here. It is the speed of light; and are the clock differences between the satellite and the receiver respectively; The tropospheric delay in the direction of the receiver zenith is expressed by Converting Zenith Tropospheric Delay to Satellite To the receiver The mapping function of the viewing direction; is the ionospheric delay; is the range correction for the change in antenna phase center, obtained by interpolating the grid point correction into the zenith angle and azimuth angle in the line of sight direction; Frequency The wavelength, is the ambiguity parameter corresponding to the frequency; and Indicates other systematic errors; and represent the measurement noise of pseudorange and carrier phase observations, respectively.

[0009] According to the present invention, a method for calibrating the phase center variation of a satellite Ka-band intersatellite link antenna is provided. The method collects intersatellite Ka-band link observation data, removes gross error data, performs epoch normalization and combination on the two-way observation data, and generates clock-error-free / geometry-free observation quantities for solving epochs, including: Determine a set of intersatellite link observations including the two satellites at their respective signal reception times and Ka-band distance observations obtained and , the observation equation is expressed as follows:

[0010]

[0011] Among them, the subscripts A and B indicate the satellite identifiers corresponding to the parameters; represents the satellite position vector; represents the speed of light; represents the satellite clock error at time t; and Respectively represent the PCO and PCV corrections of the corresponding satellites, and Respectively represent the hardware delay of Ka-band receiving and transmitting channels; represents the relativity correction; represents the measurement noise; The epoch normalization of intersatellite link data includes normalizing the bidirectional observation values ​​of the intersatellite link to the same reference time. The observation value normalization is achieved by correcting the changes in satellite position and clock error to obtain the intersatellite link observation value at the target time. and The original observation value received at the time is normalized to the target time The process is expressed as follows:

[0012]

[0013] wherein and denote the satellite position and clock variation, which are calculated by the following formula:

[0014]

[0015] The combined observation value of the inter-satellite link data is based on the bi-directional observation values normalized to the same time, and the two formulas are summed to eliminate the clock variation information of the satellite, and the result is as follows:

[0016] The above formula is used for orbit calculation of the satellite, and are respectively half of the transmission and reception delay and sum of the inter-satellite link equipment of satellite A and satellite B, which are calculated as constants together with the orbit parameters in precise orbit determination; The two formulas are subtracted to eliminate the position information of the satellite, and the result is as follows:

[0017]

[0018] The above formula only contains the difference between the satellite clock variation and the device delay of the Ka band, and the inter-satellite link observation value without orbit information is added in joint orbit determination, so as to reduce the influence of the orbit on the clock variation estimation, so as to adjust the clock variation parameter and indirectly optimize the orbit precision.

[0019] According to the satellite Ka band inter-satellite link antenna phase center variation calibration method provided by the application, the zenith angle and azimuth angle variation range of L / Ka observation data are analyzed, a segmented linear function model of two kinds of antenna PCVs is constructed, and the original PCV parameters of the satellite L / Ka band are calculated based on the L / Ka observation data in joint orbit determination, including: Suppose that the PCO vector of the satellite L or Ka antenna is , the PCV correction is , wherein is the zenith angle, is the azimuth angle, and the correction value of the station-satellite distance observation value caused by the satellite antenna PCO and PCV is represented as:

[0020] Considering that there is a correlation between PCO and PCV, and part of the PCO correction will be absorbed by the satellite clock variation or delay, the above formula is rewritten as:

[0021] In the above formula The original PCV is taken as a starting point; The original PCV is modeled by using a piecewise linear function with the zenith angle and the azimuth angle as independent variables, and the following equation is obtained:

[0022]

[0023]

[0024] wherein n is the number of each segmented point after the zenith angle is segmented, m is the number of each segmented point after the azimuth angle is segmented, n and m are used as subscripts to describe the position of the grid point, and are the original PCVs at the four corner points of the grid where the original PCV is located, the above equation gives the partial derivative corresponding to the original PCV parameter, and the original PCV estimation equation of the L / Ka band antenna is constructed by combining different types of observation data to solve the parameter. Considering the correlation between the antenna PCV parameter and the satellite clock error and the device time delay parameter, the following constraint equation is introduced to avoid rank deficiency of the normal equation:

[0025] wherein m is the number of the zenith angle segmented nodes, and n is the number of the azimuth angle segmented nodes, and the above constraint equation indicates that the sum of the original PCVs at all grid points of the satellite is zero.

[0026] According to the satellite Ka band inter-satellite link antenna phase center variation calibration method provided by the application, the least square separation method is used to separate the smoothest PCV and the corresponding Z-PCO from the original PCV parameter, and a PCV grid correction model is established according to the PCV values under the discrete zenith angle and azimuth angle of the satellite, including: The condition for determining that the least square method is used to separate the PCV and the PCO is that:

[0027] In the formula, k is a constant part in the formula, which is absorbed by the PCO estimation; The formula is taken as an estimated parameter in the above formula, , , , , The residual error of the least square fitting is the satellite antenna PCV related to the zenith angle and the azimuth angle, the PCV estimation is the value under the discrete zenith angle and azimuth angle, and the linear piecewise function interpolation is established with the zenith angle and the azimuth angle as independent variables to solve.

[0028] ​​​The application provides a satellite Ka-band inter-satellite link antenna phase center variation calibration method, which applies the established PCV grid correction model to joint orbit error correction, performs new joint orbiting and solves PCO correction of L / Ka-band of the satellite, including: The error influence of PCO on the line-of-sight direction in the orbiting is expressed in the inertial system as follows:

[0029] , , The unit vector of the star-fixed system coordinate axis in the inertial system is specifically expressed as: ; ;

[0030] Wherein and are the position vectors of the satellite and the sun in the inertial system respectively; The distance correction amount caused by the PCO of the satellite is :

[0031] is the unit direction vector in the inertial system, which is the direction vector from the satellite to the station in the star-ground observation and is the direction vector between the two satellites in the inter-satellite observation; The partial derivative of the L or Ka-band observation value to the PCO parameter is expressed as: ; ;

[0032] Each Ka-band inter-satellite link observation corresponds to two satellites, and the partial derivative of the PCO parameter of the satellite is obtained when the partial derivative of the PCO parameter of the satellite is solved, the PCO is taken as a to-be-estimated parameter in the precise orbiting data processing and is solved together with the satellite orbit and other parameters, and the PCO of each orbiting arc segment is estimated as a constant.

[0033] In the second aspect, the application further provides a satellite Ka-band inter-satellite link antenna phase center variation calibration system, which comprises: A data collection and preprocessing module is used for collecting L-band observation data of the ground station, performing rough error elimination and cycle slip detection, collecting inter-satellite Ka-band link observation data, eliminating rough error data, performing epoch normalization and combination on the bidirectional observation data, and generating clock error-free / geometry-free observation of the solving epoch; ​​An original PCV estimation module is configured to analyze the zenith and azimuth variation ranges of L / Ka observation data, construct a segmented linear function model of PCV of two kinds of antennas, and solve the original PCV parameters of the satellite L / Ka band based on the joint orbit determination of the L / Ka observation data. A PCV extraction module is configured to separate the smoothest PCV and the corresponding Z-PCO from the original PCV parameters by using a least square separation method, and establish a PCV grid correction model according to the PCV values of the satellite at discrete zenith and azimuth angles. A PCO estimation module is configured to apply the established PCV grid correction model to the joint orbit determination error correction, perform a new round of joint orbit determination, and solve the PCO correction of the satellite L / Ka band.

[0034] In a third aspect, the present application further provides an electronic device, which comprises a memory, a processor, and a computer program stored in the memory and executable on the processor, and the processor implements the satellite Ka band inter-satellite link antenna phase center variation calibration method according to any one of the above aspects when executing the program.

[0035] In a fourth aspect, the present application further provides a non-transitory computer readable storage medium, which stores a computer program, and the computer program is executable on a processor to implement the satellite Ka band inter-satellite link antenna phase center variation calibration method according to any one of the above aspects.

[0036] In a fifth aspect, the present application further provides a computer program product, which comprises a computer program, and the computer program is executable on a processor to implement the satellite Ka band inter-satellite link antenna phase center variation calibration method according to any one of the above aspects.

[0037] The satellite Ka band inter-satellite link antenna phase center variation calibration method and system provided by the present application first proposes a calibration method for the inter-satellite Ka band antenna phase center variation, fills the gap of the on-orbit calibration technology of the inter-satellite link phased array antenna phase center, effectively reduces the correlation between PCO, PCV and satellite orbit, clock error and other parameters through joint orbit determination of L band ground observation data and Ka band inter-satellite link data, and unifies the two kinds of data in the same earth reference frame, which not only improves the stability of parameter solution, but also lays a technical foundation for subsequent deep fusion processing of multi-source navigation data. The accurate Ka band antenna phase center variation model helps to improve the precision of precise orbit determination and clock error solution, and also provides the possibility for realizing the earth reference frame with millimeter level precision, which has important significance for the application of Beidou satellite in the field of earth science. BRIEF DESCRIPTION OF DRAWINGS

[0038] In order to more clearly illustrate the technical solutions of the present application or the prior art, the drawings needed to be used in the following embodiments or prior art description will be briefly introduced. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative effort.

[0039] Figure 1 is a flowchart of the satellite Ka-band inter-satellite link antenna phase center variation calibration method provided by the present application; Figure 2 is a flowchart of the antenna phase center variation calibration method provided by the present application; Figure 3 is a schematic diagram of the Beidou inter-satellite link establishment provided by the present application; Figure 4 is a structural schematic diagram of the satellite Ka-band inter-satellite link antenna phase center variation calibration system provided by the present application; Figure 5 is a structural schematic diagram of the electronic device provided by the present application. DETAILED DESCRIPTION

[0040] In order to make the objects, technical solutions and advantages of the present application clearer, the technical solutions in the present application will be described clearly and completely below in combination with the drawings in the present application. Obviously, the described embodiments are some embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative effort belong to the protection scope of the present application.

[0041] Figure 1 is a flowchart of the satellite Ka-band inter-satellite link antenna phase center variation calibration method provided by the present application, as shown in Figure 1 , including: Step 100: Collect L-band observation data of ground stations, and perform gross error elimination and cycle slip detection; collect inter-satellite Ka-band link observation data, eliminate gross error data, and perform epoch normalization and combination on two-way observation data to generate clock error-free / geometry-free observation data of the solving epoch; Step 200: Analyze the zenith angle and azimuth angle variation range of L / Ka observation data, construct a segmented linear function model of two kinds of antenna PCV, and based on the L / Ka observation data, perform joint orbit determination and original PCV parameter solving of the satellite L / Ka band at the same time; Step 300: Separate the smoothest PCV and the corresponding Z-PCO from the original PCV parameters by using the least square separation method, and establish a PCV grid correction model according to the PCV values of the satellite under discrete zenith angle and azimuth angle; Step 400: Apply the established PCV grid correction model to the joint orbit determination error correction, perform a new round of joint orbit determination, and solve the PCO correction of the satellite L / Ka band.

[0042] Specifically, the phase center variation calibration method for Beidou satellite Ka-band intersatellite link antenna proposed in the embodiment of the present invention has a data processing flow as follows: Figure 1 Shown, including: 1. Data Collection and Preprocessing L-band carrier and pseudorange observation data are collected from ground stations and subjected to gross error removal and cycle slip detection. Ka-band intersatellite link observation data are also collected and gross error data removed. The two-way observation data are epoch-normalized and combined to generate clock- and geometry-free observations.

[0043] The pseudorange and carrier observation equations of the L band here can be expressed as follows:

[0044] In the formula Respectively represent the frequency, satellite and receiver serial number, Indicates the frequency satellites To the receiver The L-band pseudorange observation value of is the satellite centroid position represented by the vector; Correction for satellite antenna phase center; is the receiver antenna phase center position represented by the vector. The receiver antenna phase center correction is not considered in this paper. It is the speed of light; and are the clock differences between the satellite and the receiver respectively; The tropospheric delay in the direction of the receiver zenith is expressed by is the transfer of zenith tropospheric delay to satellite To the receiver The mapping function of the viewing direction; is the ionospheric delay; It is the range correction value for the change in the antenna phase center, which is generally obtained by interpolating the grid point correction value into the zenith angle and azimuth angle in the line of sight direction; Frequency The wavelength, is the ambiguity parameter corresponding to the frequency; and Represents other systematic errors, such as antenna phase winding, relativistic effects, and tidal corrections, which can be corrected by the model; and represent the measurement noise of pseudorange and carrier phase observations, respectively.

[0045] The bi-directional observations of inter-satellite link are completed within 3 s, in which the satellite B receives the Ka-band signal transmitted by satellite A in the first 1.5 s and transmits the return signal in the last 1.5 s. Therefore, a set of inter-satellite link observations includes the two satellites at their respective signal receiving time and The obtained Ka-band range observations and The observation equation is expressed as follows:

[0046]

[0047] In the formula, the subscripts A and B represent the satellite identifiers corresponding to the parameters; represents the satellite position vector; represents the speed of light; represents the satellite clock error at time t; and represent the PCO and PCV corrections of the corresponding satellites, respectively, and represent the hardware time delays of the Ka-band receiving and transmitting channels, respectively; represents the relativistic correction; represents the measurement noise.

[0048] The epoch normalizing of inter-satellite link data refers to normalizing the bi-directional observations of inter-satellite link to the same reference time to facilitate data processing. The observation normalizing is achieved through the correction of satellite position and clock error changes to obtain the inter-satellite link observations at the target time. and The process of planning the original observations received at time t to the target time can be expressed as follows:

[0049]

[0050] In the formula, and represent the changes in satellite position and clock error, which can be calculated by the following formula:

[0051]

[0052] Moreover, the combined observations of inter-satellite link data are based on the bi-directional observations normalized to the same time, and the summation of the two equations can eliminate the satellite clock error information, and the result is as follows:

[0053] The above formula can be used for orbit determination of satellites, and respectively half of the satellite A, B inter-satellite link equipment transmission and reception delay and, in precise orbit determination will be as a constant with orbit parameters.

[0054] The difference between the two formulas can eliminate the satellite position information, the results are as follows:

[0055]

[0056] The above formula only contains the difference between the satellite clock error and the Ka band equipment delay, combined with the orbit determination of the inter-satellite link observation without orbit information, reduces the influence of the orbit on the clock error estimation to adjust the clock error parameter and indirectly optimize the orbit precision.

[0057] II. Construction of original PCV model and joint orbit determination Analyze the zenith angle and azimuth angle range of L-band and Ka-band observation data, and establish a segmented linear function model of the original PCV. Based on this model, estimate the original PCV parameters of the satellite L / Ka-band antenna while joint orbit determination.

[0058] In this step, the establishment of the segmented linear function model of the antenna PCV needs to introduce the concept of the original PCV, because the PCO and PCV parameters of the satellite antenna are highly correlated, and the PCO parameter will inevitably affect the estimation of PCV. Assuming that the PCO vector of the satellite L or Ka antenna is , the PCV correction is , where is the zenith angle, is the azimuth angle, then the correction value of the station-satellite distance observation value caused by the satellite antenna PCO and PCV can be expressed as:

[0059] Considering the correlation between PCO and PCV, and part of the PCO correction may be absorbed by the satellite clock error or delay, the above formula needs to be rewritten as:

[0060] In the above formula is the original PCV.

[0061] The segmented linear function with zenith angle and azimuth angle as independent variables is used to model the original PCV, which has

[0062]

[0063]

[0064] where n is the index of the sub-segment point in the zenith angle, m is the index of the sub-segment point in the azimuth angle, and n and m are used as subscripts to describe the position of the grid point. At the same time, 、 、 and are the original PCVs at the four corner points of the grid where is located. The above formula gives the partial derivative corresponding to the original PCV parameter, and combined with different types of observation data, the original PCV estimation equation of the L / Ka band antenna can be constructed to solve the parameters.

[0065] In addition, considering the correlation between the antenna PCV parameters and the satellite clock error and device time delay parameters, the following constraint equation is generally introduced to avoid rank deficiency of the normal equation:

[0066] where m is the number of zenith angle segmentation nodes, and n is the number of azimuth angle segmentation nodes. The above constraint equation indicates that the sum of the original PCVs at all grid points of the satellite is zero.

[0067] where the inter-satellite link data is generated by two satellites, the relative spatial position changes more, and there are obvious differences between different types of satellites. The inter-satellite link of different satellites of Beidou is shown in Figure 3 . For satellites on the same orbital plane, the zenith angle of the inter-satellite observation value remains fixed, and the zenith angle of the inter-satellite observation value of satellites on different orbital planes changes periodically with the satellite motion. Considering the scanning range limitation of the Ka band phased array antenna, the zenith angle range of the inter-satellite PCV modeling can reach .

[0068] III. PCV parameter separation and modeling The least squares method is used to separate the original PCV into smooth PCV and PCO in the Z direction. By calculating and interpolating on the discrete grid of the zenith angle and the azimuth angle, the final PCV correction model is generated.

[0069] In this step, the conditions for separating PCV and PCO by the least squares method are:

[0070] where k is the constant part in , which will be absorbed by the PCO estimation in step S4. To facilitate the solution, the above formula is , , , As the parameters to be estimated, the residuals of the least squares fitting are the PCVs of the satellite antenna, which are related to both the zenith angle and the azimuth angle. The PCVs are estimated at discrete zenith angles and azimuth angles, and in actual use, a linear piecewise function is established with the zenith angle and the azimuth angle as the independent variables to solve the PCVs.

[0071] Four, PCV model application and PCO correction estimation The PCV correction model described above is applied to the error correction of joint orbit determination, and the PCO correction values of the L / Ka band of the satellite are further calculated. According to the conversion of the inter-satellite link direction vector and the inertial system, the influence of the phase center correction on the observation value is calculated, and the orbit parameters are jointly calculated.

[0072] In this step, the error influence of PCO on the line-of-sight direction in the orbit determination can be expressed in the inertial system as follows:

[0073] wherein, , , is the unit vector of the coordinate axis of the satellite in the inertial system, which can be specifically expressed as: ; ;

[0074] wherein and are the position vectors of the satellite and the sun in the inertial system, respectively.

[0075] Then, the PCO of the satellite causes the distance correction amount of the satellite-to-ground or satellite-to-satellite :

[0076] wherein, is the unit direction vector in the inertial system, which is the direction vector from the satellite to the station in the satellite-to-ground observation, and is the direction vector between the two satellites in the satellite-to-satellite observation.

[0077] Then, the partial derivative of the L or Ka band observation value with respect to the PCO parameter can be expressed as: ; ;

[0078] It should be noted that each Ka band inter-satellite link observation corresponds to two satellites, and when the partial derivative of the PCO parameter of the satellite is calculated, the direction vectors of the two satellites are the same in size and opposite in direction. After obtaining the partial derivative of the PCO parameter of the satellite, the PCO can be estimated as a parameter to be estimated in the precise orbit determination data processing, and the PCO is estimated as a constant in each orbit determination arc segment.

[0079] The satellite Ka-band inter-satellite link antenna phase center variation calibration system provided by the present application is described below, and the satellite Ka-band inter-satellite link antenna phase center variation calibration system described below can be correspondingly referred to the satellite Ka-band inter-satellite link antenna phase center variation calibration method described above.

[0080] Figure 4 The satellite Ka-band inter-satellite link antenna phase center variation calibration system provided by the present application is described below, and the satellite Ka-band inter-satellite link antenna phase center variation calibration system described below can be correspondingly referred to the satellite Ka-band inter-satellite link antenna phase center variation calibration method described above. Figure 4 As shown in the structural schematic diagram of the satellite Ka-band inter-satellite link antenna phase center variation calibration system provided by the present application, it comprises: A data collection preprocessing module is configured to collect L-band observation data of a ground station, remove gross errors and detect cycle slips; collect inter-satellite Ka-band link observation data, remove gross error data, perform epoch normalization and combination on bidirectional observation data, and generate clock error-free / geometric error-free observation data of a solution epoch; An original PCV estimation module is configured to analyze the zenith angle and azimuth angle variation range of L / Ka observation data, construct a segmented linear function model of two kinds of antenna PCVs, and perform original PCV parameter solution of satellite L / Ka bands based on L / Ka observation data while performing joint orbit determination; A PCV extraction module is configured to separate the smoothest PCV and the corresponding Z-PCO from the original PCV parameters by using a least square separation method, and establish a PCV grid correction model according to the PCV values under discrete zenith angles and azimuth angles of a satellite; A PCO estimation module is configured to apply the established PCV grid correction model to joint orbit determination error correction, perform a new round of joint orbit determination, and solve PCO correction of satellite L / Ka bands.

[0081] Figure 5 An example of an electronic device is shown in the structural schematic diagram of the electronic device, as Figure 5As shown, the electronic device can include a processor 510, a communications interface 520, a memory 530, and a communications bus 540, wherein the processor 510, the communications interface 520, and the memory 530 complete mutual communication through the communications bus 540. The processor 510 can invoke the logical instructions in the memory 530 to execute the satellite Ka-band inter-satellite link antenna phase center variation calibration method, which includes collecting L-band observation data of a ground station, performing gross error elimination and cycle slip detection; collecting inter-satellite Ka-band link observation data, eliminating gross error data, performing epoch normalization and combination on bidirectional observation data, and generating clock error-free / geometric error-free observation; analyzing the zenith angle and azimuth angle variation range of the L / Ka observation data, constructing a segmented linear function model of the two kinds of antenna PCV, based on the L / Ka observation data, simultaneously performing joint orbit determination and satellite L / Ka band original PCV parameter solving; using the least squares separation method to separate the smoothest PCV and the corresponding Z-PCO from the original PCV parameters, and establishing a PCV grid correction model according to the PCV values of the satellite at discrete zenith angles and azimuth angles; applying the established PCV grid correction model to joint orbit determination error correction, performing a new round of joint orbit determination, and solving the PCO correction of the satellite L / Ka band.

[0082] In addition, the logical instructions in the memory 530 described above can be implemented in the form of a software function unit and sold or used as an independent product, which can be stored in a computer readable storage medium. Based on such understanding, the technical solutions of the present application or parts of the present application that essentially contribute to the prior art or parts of the technical solutions can be embodied in the form of a software product, which is stored in a storage medium, includes a plurality of instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the method described in various embodiments of the present application. The aforementioned storage medium includes a U disk, a mobile hard disk, a read-only memory (ROM, Read-Only Memory), a random access memory (RAM, Random Access Memory), a magnetic disk or an optical disk, and various program code storage media.

[0083] In another aspect, the present application also provides a computer program product, which comprises a computer program, the computer program being stored in a non-transitory computer readable storage medium, and the computer program being executable by a processor to enable a computer to perform the satellite Ka-band inter-satellite link antenna phase center variation calibration method provided by the above method, which comprises: collecting L-band observation data of ground stations; collecting inter-satellite Ka-band link observation data, eliminating gross error data, epoch normalizing and combining two-way observation data to generate clock error-free / geometry-free observation at the calculation epoch; analyzing the zenith angle and azimuth angle variation range of L / Ka observation data, constructing a segmented linear function model of the PCV of two kinds of antennas, and simultaneously performing joint orbit determination based on L / Ka observation data and original PCV parameter solving of the satellite L / Ka band; separating the smoothest PCV and the corresponding Z-PCO from the original PCV parameter by using the least square separation method; establishing a PCV grid correction model according to the PCV values of the satellite at discrete zenith angles and azimuth angles; applying the established PCV grid correction model to joint orbit determination error correction, performing a new round of joint orbit determination, and solving the PCO correction of the satellite L / Ka band.

[0084] In another aspect, the present application also provides a non-transitory computer readable storage medium, which stores a computer program, and the computer program is executable by a processor to implement the satellite Ka-band inter-satellite link antenna phase center variation calibration method provided by the above method, which comprises: collecting L-band observation data of ground stations; collecting inter-satellite Ka-band link observation data, eliminating gross error data, epoch normalizing and combining two-way observation data to generate clock error-free / geometry-free observation at the calculation epoch; analyzing the zenith angle and azimuth angle variation range of L / Ka observation data, constructing a segmented linear function model of the PCV of two kinds of antennas, and simultaneously performing joint orbit determination based on L / Ka observation data and original PCV parameter solving of the satellite L / Ka band; separating the smoothest PCV and the corresponding Z-PCO from the original PCV parameter by using the least square separation method; establishing a PCV grid correction model according to the PCV values of the satellite at discrete zenith angles and azimuth angles; applying the established PCV grid correction model to joint orbit determination error correction, performing a new round of joint orbit determination, and solving the PCO correction of the satellite L / Ka band.

[0085] The device embodiments described above are only schematic, wherein the units shown as separate components can or can not be physically separate, and the components shown as units can or can not be physical units, i.e., can be located in one place or distributed on multiple network units. Part or all of the modules can be selected according to actual needs to achieve the purpose of the present embodiment scheme. Those skilled in the art can understand and implement it without creative labor.

[0086] Those skilled in the art can clearly understand the implementation of the various embodiments by means of software and necessary general hardware platforms through the above description of the embodiments, and of course, the embodiments can also be implemented by hardware. Based on such understanding, the above technical solutions, essentially or in other words, the part of the prior art that makes a contribution, can be embodied in the form of a software product, which can be stored in a computer readable storage medium, such as a ROM / RAM, a magnetic disk, an optical disk, etc., and includes a number of instructions to make a computer device (which can be a personal computer, a server, or a network device, etc.) execute the methods described in the various embodiments or some parts of the embodiments.

[0087] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing examples, or make equivalent replacement for some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the various embodiments of the present application.

Claims

1. A method for calibrating phase center variations of a satellite Ka-band inter-satellite link antenna, characterized in that, Comprise: Collect L-band observation data of ground stations, and remove gross errors and detect cycle slips; Collect inter-satellite Ka-band link observation data, remove gross error data, and epoch-normalize and combine bi-directional observation data to generate clock error-free / geometric error-free observations at the solution epoch; Analyze the variation ranges of the zenith and azimuth angles of L / Ka observation data, construct piecewise linear function models of the PCVs of the two antennas, and solve the original PCV parameters of the satellites in L / Ka bands based on L / Ka observation data while jointly orbiting; Separate the smoothest PCV and corresponding Z-PCO from the original PCV parameters using the least squares separation method, and establish a PCV grid correction model according to the PCV values of the satellites at discrete zenith and azimuth angles; Apply the established PCV grid correction model to joint orbit error correction, perform a new round of joint orbiting, and solve the PCO correction of the satellites in L / Ka bands.

2. The method according to claim 1, wherein, Collecting L-band observation data of ground stations, eliminating gross errors and detecting cycle slips, including: where, f, s, r denote frequency, satellite and receiver number respectively, denote the L-band pseudorange observation from the th frequency bin of the th satellite to the th receiver; is the vector representation of the satellite's center of mass position; is the satellite antenna phase center correction; is the vector representation of the receiver antenna phase center position, the antenna phase center correction of the receiver is not considered here; is the speed of light; and are the satellite and receiver clock errors respectively; denotes the tropospheric delay in the zenith direction of the receiver, which is converted to the mapping function in the line-of-sight direction of the th satellite to the th receiver by ; is the ionospheric delay; is the distance correction value of the antenna phase center variation, which is obtained by interpolating the correction number of the grid point into the zenith angle and azimuth angle of the line-of-sight direction; is the wavelength of the frequency , is the ambiguity parameter corresponding to the frequency; and denote other systematic errors; and represent the measurement noise of the pseudorange and carrier phase observation respectively.

3. The method of claim 1, wherein, Collect inter-satellite Ka-band link observation data, remove gross error data, and epoch-normalize and combine bi-directional observation data to generate clock error-free / geometric error-free observations at the solution epoch, including: A set of inter-satellite link observations is determined including two satellites at respective signal reception times With Obtained Ka-band range observations And The observation equation is expressed as follows: Among them, the subscripts A and B indicate the satellite identifiers corresponding to the parameters; represents the satellite position vector; represents the speed of light; represents the satellite clock error at time t; and Respectively represent the PCO and PCV corrections of the corresponding satellites, and Respectively represent the hardware delay of Ka-band receiving and transmitting channels; represents the relativity correction; represents the measurement noise; The epoch normalizing of inter-satellite link data includes normalizing the inter-satellite link bidirectional observation values to the same reference time, and the observation value normalizing is achieved by correcting the satellite position and clock difference changes to obtain the inter-satellite link observation values at the target time, With The original observation values received at the time are planned to the target time The process is represented as follows: in and represents the satellite position and clock error changes, which are calculated using the following formula: The combined observation values of inter-satellite link data are based on bi-directional observation values normalized to the same time, and the sum of the two equations eliminates the clock error information of the satellite, as shown below: The above formula is used for orbit determination of satellites, and respectively half of the satellite A, B inter-satellite link equipment transmission and reception delay and, in precise orbit determination, it is solved as a constant together with the orbit parameters; The difference between the two equations eliminates the position information of the satellite, as shown below: The above formula only contains the difference between the satellite clock error and the device time delay in the Ka band. When jointly orbiting, the inter-satellite link observation values without orbital information are added to reduce the influence of the orbit on the clock error estimation, achieve the purpose of adjusting the clock error parameters and indirectly optimizing the orbit accuracy.

4. The method of claim 1, wherein, Analyze the variation ranges of the zenith and azimuth angles of L / Ka observation data, construct piecewise linear function models of the PCVs of the two antennas, and solve the original PCV parameters of the satellites in L / Ka bands based on L / Ka observation data while jointly orbiting, including: Assume the PCO vector of the satellite L or Ka antenna is and the PCV correction is where is the zenith angle, is the azimuth angle, then the correction to the station-satellite range observation caused by the PCO and PCV of the satellite antenna is represented as: Considering the correlation between PCO and PCV, and that part of the PCO correction will be absorbed by the satellite clock error or time delay, the above formula is rewritten as: In the above formula i.e. the original PCV; The piecewise linear function with zenith and azimuth angles as independent variables is modeled for the original PCV, resulting in: wherein n is the number of each segment point after the zenith angle is segmented, m is the number of each segment point after the azimuth angle is segmented, n and m are used as subscripts to describe the position of the grid point, , , and are the original PCVs at the four corner points of the grid where is located, the above formula gives the partial derivative corresponding to the original PCV parameter, and the original PCV estimation equation of the L / Ka band antenna is constructed by combining different types of observation data to solve the parameters. Considering the correlation between the antenna PCV parameters and the satellite clock error and device time delay parameters, the following constraint equation is introduced to avoid rank deficiency of the normal equation: Where m is the number of zenith angle segmentation nodes, and n is the number of azimuth angle segmentation nodes. The above constraint equation indicates that the sum of the original PCVs at all grid points of the satellite is zero.

5. The method of claim 1, wherein, Separate the smoothest PCV and corresponding Z-PCO from the original PCV parameters using the least squares separation method, and establish a PCV grid correction model according to the PCV values of the satellites at discrete zenith and azimuth angles, including: The condition for separating PCV and PCO using the least squares method is: where k is the constant part of absorbed by the PCO estimate; The above formula is , , , As the estimated parameters, the residual of the least square fitting is the satellite antenna PCV related to both the zenith angle and the azimuth angle, and the PCV estimation is the value at the discrete zenith angle and azimuth angle, and a linear piecewise function interpolation is established with the zenith angle and the azimuth angle as the independent variables to solve it.

6. The method of claim 1, wherein, Apply the established PCV grid correction model to joint orbit error correction, perform a new round of joint orbiting, and solve the PCO correction of the satellites in L / Ka bands, including: The error impact of PCO on the line-of-sight direction in the inertial system is represented as: wherein , , is a unit vector of the star-fixed coordinate axis in the inertial system, and is specifically represented as: ； ； wherein and respectively are the satellite and sun position vectors in the inertial frame. PCO of the satellite causes a range correction is: wherein, is the unit direction vector in the inertial system, which is the direction vector from the satellite to the station when observing the station, and is the direction vector between two satellites when observing the satellite. The partial derivative of the L or Ka band observation value with respect to the PCO parameter is represented as: ； ； Each Ka-band inter-satellite link observation corresponds to two satellites, and when the partial derivative of the PCO parameter of the satellite is calculated, the direction vectors of the two satellites are the same in size and opposite in direction. After obtaining the partial derivative of the PCO parameter of the satellite, the PCO is solved as a to-be-estimated parameter together with the satellite orbit and other parameters in the precise orbit determination data processing, and the PCO of each orbit determination arc segment is estimated as a constant.

7. A system for calibrating phase center variations of a satellite Ka-band inter-satellite link antenna, characterized in that, It comprises: a data collection preprocessing module for collecting L-band observation data of ground stations, performing gross error elimination and cycle slip detection; collecting inter-satellite Ka-band link observation data, eliminating gross error data, performing epoch normalization and combination on bidirectional observation data, and generating clock error-free / geometric error-free observation data for calculation epochs; an original PCV estimation module for analyzing the range of zenith angle and azimuth angle of L / Ka observation data, constructing a segmented linear function model of two kinds of antenna PCV, and simultaneously solving the original PCV parameters of the satellite L / Ka band based on the L / Ka observation data in joint orbit determination; a PCV extraction module for separating the smoothest PCV and the corresponding Z-PCO from the original PCV parameters by using the least square separation method, and establishing a PCV grid correction model according to the PCV values under the discrete zenith angle and azimuth angle of the satellite; a PCO estimation module for applying the established PCV grid correction model to the joint orbit determination error correction, performing a new round of joint orbit determination, and solving the PCO correction of the satellite L / Ka band.

8. An electronic device comprising a memory, a processor, and a computer program stored on the memory and executable on the processor, characterized in that, The processor executes the program to realize the satellite Ka-band inter-satellite link antenna phase center variation calibration method according to any one of claims 1 to 6. 9.A non-transitory computer-readable storage medium having stored thereon a computer program, characterized in that, The computer program is executed by the processor to realize the satellite Ka-band inter-satellite link antenna phase center variation calibration method according to any one of claims 1 to 6.

10. A computer program product comprising a computer program, characterized in that, The computer program is executed by the processor to realize the satellite Ka-band inter-satellite link antenna phase center variation calibration method according to any one of claims 1 to 6.

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