A method, device and medium for estimating a real-time clock difference of a LEO satellite

Abstract

The embodiment of the application provides a LEO satellite real-time clock difference estimation method, device and medium, wherein the star-borne observation data of the LEO satellite, the orbit of the navigation satellite and the clock difference of the navigation satellite are acquired; the orbit prediction is performed according to the star-borne observation data, and the predicted orbit of the LEO satellite is obtained; the geometric distance between the LEO satellite and the navigation satellite is obtained according to the predicted orbit of the LEO satellite and the orbit of the navigation satellite; the satellite observation equation is constructed according to the star-borne observation data, the geometric distance and the clock difference of the navigation satellite; the satellite observation equation is solved, and the real-time clock difference of the LEO satellite is obtained; the satellite observation equation is obtained by fixing the predicted orbit of the satellite, the solving of a large number of dynamic parameters in the process of solving the satellite observation equation is avoided, the number of to-be-estimated parameters in the satellite observation equation is reduced, and the satellite clock difference solving efficiency is improved.

Description

Technical Field

[0001] This application relates to, but is not limited to, the field of satellites, and particularly to a method, device, and medium for estimating the real-time clock difference of LEO satellites. Background Technology

[0002] Global Navigation Satellite Systems (GNSS), such as GPS, BDS, and GALILEO, provide positioning, navigation, and timing (PNT) services. However, GNSS systems suffer from low accuracy in basic navigation services, severe signal attenuation, and slow convergence in precise positioning. Building a low-Earth orbit (LEO) navigation augmentation system based on LEO satellites can enhance the service capabilities of GNSS navigation systems and provide independent PNT services. LEO satellite clock bias products are a crucial component in providing PNT services for LEO navigation augmentation systems. Typically, LEO satellite clock bias is calculated together with the LEO satellite orbit, resulting in numerous parameters to be estimated and lengthy computation times. This fails to meet the real-time calculation requirements of LEO satellite clock bias and limits the ability of LEO navigation augmentation systems to provide real-time PNT services to users. Summary of the Invention

[0003] The following is an overview of the subject matter described in detail herein. This overview is not intended to limit the scope of the claims.

[0004] This application provides a method, device, and medium for estimating the real-time clock difference of LEO satellites.

[0005] An embodiment of the first aspect of this application provides a method for estimating the real-time clock difference of LEO satellites, characterized in that it includes:

[0006] Acquire onboard observation data of LEO satellites, navigation satellite orbits, and navigation satellite clock biases;

[0007] Based on the onboard observation data, orbit prediction is performed to obtain the predicted orbit of the LEO satellite;

[0008] The geometric distance between the LEO satellite and the navigation satellite is obtained based on the predicted orbit of the LEO satellite and the orbit of the navigation satellite.

[0009] The satellite observation equation is constructed based on the onboard observation data, the geometric distance, and the navigation satellite clock error.

[0010] Solve the satellite observation equations to obtain the real-time clock difference of the LEO satellite.

[0011] In certain embodiments of the first aspect of this application, the step of predicting the orbit based on the onboard observation data to obtain the predicted orbit of the LEO satellite includes:

[0012] The initial orbit and dynamic parameters of the LEO satellite were obtained from the onboard observation data using the least squares method.

[0013] The predicted orbit of the LEO satellite is obtained by integrating the orbit based on the initial orbit and dynamic parameters of the LEO satellite.

[0014] In certain embodiments of the first aspect of this application, after the orbit prediction is performed based on the onboard observation data to obtain the predicted orbit of the LEO satellite, the method further includes:

[0015] The predicted LEO satellite orbit is transformed to convert the predicted LEO satellite orbit with the centroid as the reference point to the predicted LEO satellite orbit with the phase center as the reference point.

[0016] In certain embodiments of the first aspect of this application, the onboard observation data includes pseudorange observations and phase observations, and the satellite observation equations include a first observation equation corresponding to the pseudorange observations and a second observation equation corresponding to the phase observations; the step of constructing the satellite observation equations based on the onboard observation data, the geometric distance, and the navigation satellite clock bias includes:

[0017] Based on the geometric distance, the ionospheric delay effect value, the speed of light value, and the navigation satellite clock error, a first observation equation corresponding to the pseudorange observation is constructed.

[0018] Based on the geometric distance, carrier phase wavelength, ionospheric delay effect value, speed of light value, ambiguity, and navigation satellite clock error, a second observation equation corresponding to the phase observation is constructed.

[0019] In certain embodiments of the first aspect of this application, after constructing the satellite observation equation based on the onboard observation data, the geometric distance, and the navigation satellite clock error, the method further includes:

[0020] The satellite observation equations are weighted according to a preset weighting principle, which is based on the elevation angle of the LEO satellite.

[0021] In certain embodiments of the first aspect of this application, solving the satellite observation equation to obtain the LEO satellite real-time clock difference includes:

[0022] Obtain the initial value of the LEO satellite clock bias;

[0023] The actual clock difference of the LEO satellite is obtained by solving the satellite observation equation based on the initial value of the LEO satellite clock difference using the sequential filtering method.

[0024] In certain embodiments of the first aspect of this application, the step of solving the satellite observation equation based on the initial value of the LEO satellite clock bias using a sequential filtering method to obtain the real-time clock bias of the LEO satellite includes:

[0025] The epochal states of LEO satellite clock errors are linked based on the state transition matrix;

[0026] Solve the satellite observation equations, and derive the actual LEO satellite clock error from the initial value of the LEO satellite clock error based on the epoch state of the associated LEO satellite clock error.

[0027] In certain embodiments of the first aspect of this application, after solving the satellite observation equations to obtain the real-time clock difference of the LEO satellite, the method further includes:

[0028] The accuracy of the real-time clock difference of the LEO satellite was evaluated by comparing the results of the post-event all-day solution and the overlapping clock difference comparison, and the accuracy evaluation results were obtained.

[0029] According to certain embodiments of the second aspect of this application, an electronic device is provided, the electronic device including a memory, a processor, a program stored in the memory and executable on the processor, and a data bus for implementing connection communication between the processor and the memory, wherein the program, when executed by the processor, implements the LEO satellite real-time clock difference estimation method as described above.

[0030] Some embodiments of the third aspect of this application provide a computer-readable storage medium storing computer-executable instructions for causing a computer to perform the LEO satellite real-time clock difference estimation method as described above.

[0031] The above scheme has at least the following beneficial effects: by acquiring onboard observation data of LEO satellites, navigation satellite orbits, and navigation satellite clock biases; by performing orbit prediction based on onboard observation data to obtain the predicted orbit of LEO satellites; by obtaining the geometric distance between LEO satellites and navigation satellites based on the predicted orbit of LEO satellites and the orbits of navigation satellites; by constructing satellite observation equations based on onboard observation data, geometric distances, and navigation satellite clock biases; by solving the satellite observation equations to obtain the real-time clock bias of LEO satellites; by fixing the predicted satellite orbits and then obtaining the satellite observation equations, the scheme avoids solving numerous dynamic parameters in the process of solving the satellite observation equations, reduces the number of parameters to be estimated in the satellite observation equations, and improves the efficiency of satellite clock bias calculation. Attached Figure Description

[0032] The accompanying drawings are used to provide a further understanding of the technical solutions of this application and constitute a part of the specification. They are used together with the embodiments of this application to explain the technical solutions of this application and do not constitute a limitation on the technical solutions of this application.

[0033] Figure 1 This is a flowchart illustrating the steps of the LEO satellite real-time clock difference estimation method provided in the embodiments of this application;

[0034] Figure 2 This is a sub-step diagram of step S200;

[0035] Figure 3 This is a sub-step diagram of step S400;

[0036] Figure 4 This is a flowchart of the weighting process;

[0037] Figure 5 This is a sub-step diagram of step S500;

[0038] Figure 6 This is a step-by-step diagram of the accuracy assessment process;

[0039] Figure 7 This is a diagram illustrating the accuracy of the results obtained by comparing the results obtained from the traditional LEO satellite real-time clock difference estimation method with the results obtained from the post-hoc all-day solution.

[0040] Figure 8 This is a diagram illustrating the accuracy of the results obtained by comparing the overlap clock difference with the traditional LEO satellite real-time clock difference estimation method.

[0041] Figure 9 This is a schematic diagram illustrating the accuracy of the results obtained by comparing the LEO satellite real-time clock difference estimation method provided in the embodiments of this application with the results obtained through post-hoc all-day solution comparison.

[0042] Figure 10 This is a schematic diagram illustrating the accuracy of the results obtained by comparing the LEO satellite real-time clock difference estimation method provided in the embodiments of this application with the overlapping clock difference comparison.

[0043] Figure 11 This is a comparison chart showing the time consumption of the LEO satellite real-time clock difference estimation method provided in the embodiments of this application and the traditional LEO satellite real-time clock difference estimation method. Detailed Implementation

[0044] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0045] It should be noted that although functional modules are divided in the device schematic diagram and a logical order is shown in the flowchart, in some cases, the steps shown or described may be performed in a different order than the module division in the device or the order in the flowchart. The terms "first," "second," etc., in the specification, claims, or the aforementioned drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence.

[0046] The embodiments of this application will be further described below with reference to the accompanying drawings.

[0047] An embodiment of this application provides a method for estimating the real-time clock difference of LEO satellites.

[0048] Reference Figure 1 The LEO satellite real-time clock difference estimation method includes, but is not limited to, the following steps:

[0049] Step S100: Obtain onboard observation data, navigation satellite orbits, and navigation satellite clock biases from the LEO satellite;

[0050] Step S200: Based on the onboard observation data, the orbit is predicted to obtain the predicted orbit of the LEO satellite;

[0051] Step S300: Obtain the geometric distance between the LEO satellite and the navigation satellite based on the predicted orbit of the LEO satellite and the orbit of the navigation satellite;

[0052] Step S400: Construct satellite observation equations based on onboard observation data, geometric distance, and navigation satellite clock bias;

[0053] Step S500: Solve the satellite observation equations to obtain the real-time clock difference of the LEO satellite.

[0054] In step S100, a receiver is set up on the LEO satellite above the ionospheric altitude to acquire onboard observation data, and the ground gateway station can download the onboard observation data.

[0055] Navigation satellite clock bias can be obtained through GNSS clock bias products; navigation satellite orbits can be obtained through GNSS ephemeris.

[0056] Reference Figure 2 For step S200, orbit prediction is performed based on onboard observation data to obtain the predicted orbit of the LEO satellite, including but not limited to the following steps:

[0057] Step S210: Obtain the initial orbit and dynamic parameters of the LEO satellite based on the onboard observation data using the least squares method;

[0058] Step S220: Perform orbit integration based on the initial orbit and dynamic parameters of the LEO satellite to obtain the predicted orbit of the LEO satellite.

[0059] In an inertial frame, the equations of motion for a LEO satellite can be expressed as: ;in, The coordinates of the LEO satellite, The velocity vector of the LEO satellite. Let t be the acceleration vector of the LEO satellite, t be time, and GM be the Earth's gravitational constant. In addition to the gravitational forces of the Earth and various celestial bodies, the main perturbation parameters considered by the LEO satellite include atmospheric drag, solar radiation pressure drag, and empirical forces, among others.

[0060] It is understood that this embodiment presents a method for obtaining the initial orbit and dynamic parameters of a LEO satellite from onboard observation data using the least squares method. However, this should not limit the method for obtaining the initial orbit and dynamic parameters of a LEO satellite from onboard observation data in this embodiment. In other embodiments, other methods may be selected.

[0061] Since both the obtained GNSS satellite orbits and LEO satellite predicted orbits are based on the centroid as the reference point, calculating the real-time clock difference of LEO satellites requires using the phase center as the reference point. This involves performing phase center correction on the GNSS satellite orbits and LEO satellite predicted orbits, i.e., performing coordinate system transformation on the GNSS satellite orbits and LEO satellite predicted orbits. This transforms the LEO satellite predicted orbits based on the centroid as the reference point into LEO satellite predicted orbits based on the phase center as the reference point, and the GNSS satellite orbits based on the centroid as the reference point into GNSS satellite orbits based on the phase center as the reference point.

[0062] The phase center is defined in the Earth-fixed frame. First, the orbit is converted to the inertial frame (CRS), and then back to the Earth-fixed frame. This conversion process can be represented as follows: ;in, This represents the transformation matrix from a star-solid frame to an inertial frame. This represents the transformation matrix from the inertial frame of reference to the Earth-fixed frame of reference.

[0063] For step S300, the geometric distance between the LEO satellite and the navigation satellite is obtained based on the predicted orbits of the LEO satellite and the navigation satellite. Specifically, the coordinates of the LEO satellite at time t can be obtained from the predicted orbits of the LEO satellite, and the coordinates of the GNSS satellite at time t can be obtained from the orbits of the navigation satellite. The geometric distance between the LEO satellite and the GNSS satellite is then calculated using the coordinates of the LEO satellite and the GNSS satellite. This geometric distance can be expressed as... ;in,( ) represents the coordinates of the LEO satellite, ( () represents the coordinates of the GNSS satellite.

[0064] That is, after fixing the LEO satellite orbit (short arc predicted orbit), the geometric distance between the LEO satellite and the GNSS satellite can be obtained. .

[0065] For step S400, the onboard observation data includes pseudorange observations and phase observations, and the satellite observation equations include a first observation equation corresponding to the pseudorange observations and a second observation equation corresponding to the phase observations.

[0066] Reference Figure 3 Satellite observation equations are constructed based on onboard observation data, geometric distance, and navigation satellite clock bias, including but not limited to the following steps:

[0067] Step S410: Construct the first observation equation for the corresponding pseudorange observation based on the geometric distance, the ionospheric delay effect value, the speed of light value, and the navigation satellite clock error;

[0068] Step S420: Construct the second observation equation for the corresponding phase observation based on the geometric distance, carrier phase wavelength, ionospheric delay effect value, speed of light value, ambiguity, and navigation satellite clock error.

[0069] The first observation equation can be expressed as: The second observation equation can be expressed as: ;in, For pseudo-distance observations (in cycles); Phase observations (in cycles); This refers to the geometric distance between LEO satellites and GNSS satellites. This represents the value of the ionospheric delay effect; This is the speed of light. For LEO satellite clock bias, For GNSS satellite clock bias, The carrier phase wavelength, For integer ambiguity; The pseudorange is an error term that can be modeled. This is an error term for the carrier phase that can be modeled. It is understandable that LEO satellites are located above the ionosphere, and their altitude is generally above 200 km, so the satellite observation equations do not contain tropospheric errors.

[0070] Values ​​related to ionospheric delay This can be mitigated by combining spaceborne observation data into ionosphere-free combinations. Furthermore, after fixing the LEO satellite orbit (short-segment predicted orbit), the geometric distance between LEO and GNSS satellites has been obtained. .

[0071] For the first observation equation, the first observation equation can be further simplified to: ;

[0072] For the second observation equation, the second observation equation can be further simplified to: .

[0073] The accuracy of the positioning equations for different types of observation data, such as pseudorange observations and phase observations, is not consistent; even for the same type of observation data, the accuracy will vary due to differences in data quality; therefore, it is necessary to weight the observation equations.

[0074] Because LEO satellite onboard observation data often suffers from significant multipath errors and observation noise at low elevation angles, it is necessary to weight the satellite observation equations based on the elevation angle of the LEO satellite.

[0075] Reference Figure 4 The weighting process includes, but is not limited to, the following steps:

[0076] Step S430: Weight the satellite observation equations according to the preset weighting principle, which is based on the elevation angle of the LEO satellite.

[0077] Specifically, the principle for determining authority is as follows: Among them, for pseudorange observations, The value is 1 m; for phase observations, The value is 1cm.

[0078] After weighting, the satellite observation equation can be further expressed as: ;in, The residuals of the observed values; Here is the coefficient matrix; x represents the ambiguity parameters and LEO satellite clock bias, which are the parameters to be estimated. This is the error term.

[0079] There are only two unknown parameters that need to be solved: the ambiguity parameter and the LEO satellite clock error.

[0080] Reference Figure 5 For step S500, the satellite observation equations are solved to obtain the real-time clock difference of the LEO satellite, including but not limited to the following steps:

[0081] Step S510: Obtain the initial values ​​of LEO satellite clock bias and ambiguity parameters;

[0082] Step S520: Solve the satellite observation equations using the sequential filtering method based on the initial values ​​of the LEO satellite clock bias and ambiguity parameters, and then obtain the real-time clock bias of the LEO satellite.

[0083] For step S510, the initial value of LEO satellite clock bias can be obtained through standard single point positioning (SPP) or clock bias prediction.

[0084] The initial value of the ambiguity parameter can be obtained using the following formula: ;in, The ambiguity parameter of the LEO satellite relative to the GNSS satellite numbered [number missing]; This represents the phase-free combination value; This refers to the geometric distance between LEO satellites and GNSS satellites. For LEO satellite clock bias, This refers to GNSS satellite clock bias.

[0085] For step S520, the satellite observation equations are solved using the sequential filtering method, which meets the requirements for both timeliness and accuracy. The sequential filtering algorithm is an improvement on the classic Kalman filtering algorithm.

[0086] When using the sequential filtering algorithm to solve the satellite observation equations, the observations are processed in epochal order. There is no need to store a large amount of historical information. The state transition matrix is ​​used to link the states of previous and subsequent epochs and to fully balance the relationship between the observations and the predicted states.

[0087] For example, for LEO satellite clock bias, the epoch states of LEO satellite clock bias are linked according to the state transition matrix; the actual LEO satellite clock bias is derived from the initial value of LEO satellite clock bias based on the linked epoch states of LEO satellite clock bias.

[0088] The parameters to be estimated for the nth epoch are based on the (n-1)th epoch: The covariance matrix for predicting the nth epoch based on the (n-1)th epoch is: In the formula, The parameter is the state transition matrix; This is the process noise matrix.

[0089] Therefore, the predicted state is: The actual observed value is: .

[0090] We can obtain the filtered solution for the time corresponding to the nth epoch: ; .

[0091] It is understood that this embodiment presents a sequential filtering method for solving the satellite observation equations, but this does not limit the method for solving the satellite observation equations in this application. In other embodiments, other estimation methods may be selected.

[0092] After calculating the LEO satellite real-time clock difference, the accuracy of the LEO satellite real-time clock difference needs to be evaluated.

[0093] Reference Figure 6 The accuracy assessment steps include, but are not limited to, the following:

[0094] Step S600: The accuracy of the real-time clock difference of the LEO satellite is evaluated by comparing the post-event all-day solution and the overlapping clock difference, and the accuracy evaluation result is obtained.

[0095] Among them, the post-hoc full-day precision clock error uses 24-hour data and is solved using the overall least squares algorithm. The clock error solution is stable, and the residual is only at the millimeter level, so it can be used as a comparison product.

[0096] Overlapping clock difference comparison compares two clock differences that have the same time. Although theoretically there is only one value for the clock difference, the data used to calculate the clock difference for the two periods are different, so there will be differences in the overlapping clock difference comparison, thus reflecting the accuracy of the clock difference product.

[0097] The following section compares the traditional LEO satellite clock bias estimation method with the LEO satellite clock bias estimation method proposed in this application.

[0098] Strategy 1 is the traditional LEO satellite clock error estimation method, which constructs observation equations based on onboard observation data and simultaneously solves for LEO satellite orbit and clock error data. The parameter estimation method adopts the overall least squares method.

[0099] Strategy 2 is the LEO satellite clock bias estimation method of this application.

[0100] Reference Figure 7 , Figure 8 , Figure 9 , Figure 10 and Figure 11 Regarding the accuracy of the calculation, Strategy 1's solution has an accuracy of 0.05 ns compared to the full-day post-hoc precise solution, and an overlap clock error comparison of 0.04 ns. Strategy 2's solution has an accuracy of 0.07 ns compared to the full-day post-hoc precise solution, and an overlap clock error comparison of 0.06 ns. Strategy 1 stores all data, lists the observation equations and normal equations, and then solves them together, resulting in a more stable solution. Strategy 2 only stores data from the previous epoch and the current epoch, achieving a similar accuracy to Strategy 1, both achieving high-precision calculations better than 0.10 ns. In terms of time consumption, Strategy 1 requires estimating the initial orbit and dynamic parameters, and performing calculations of variational equations, equations of motion, and orbital integrals, thus taking 49 seconds to calculate the 4-hour clock error. Furthermore, Strategy 1 requires accumulating a certain amount of observation data before calculating the LEO satellite clock error parameters, which cannot meet real-time requirements. Since the LEO satellite orbit is already obtained, Strategy 2 only needs to solve the ambiguity and LEO satellite clock error parameters, so it takes less time. Solving the 4-hour clock error only takes 5 seconds, which is significantly better than Strategy 1 and can meet the requirements for solving the real-time clock error.

[0101] Embodiments of this application also provide an electronic device. The electronic device includes a memory, a processor, a program stored in the memory and executable on the processor, and a data bus for communication between the processor and the memory. When the program is executed by the processor, it implements the LEO satellite real-time clock difference estimation method described above.

[0102] This electronic device can be any smart terminal, including tablet computers, in-vehicle computers, etc.

[0103] In general, for the hardware structure of electronic devices, the processor can be implemented using a general-purpose CPU (Central Processing Unit), microprocessor, application-specific integrated circuit (ASIC), or one or more integrated circuits, to execute relevant programs and implement the technical solutions provided in the embodiments of this application.

[0104] The memory can be implemented in the form of read-only memory (ROM), static storage device, dynamic storage device, or random access memory (RAM). The memory can store the operating system and other applications. When the technical solutions provided in the embodiments of this specification are implemented through software or firmware, the relevant program code is stored in the memory and called by the processor to execute the data monitoring method of the embodiments of this application.

[0105] Input / output interfaces are used to implement information input and output.

[0106] The communication interface is used to enable communication and interaction between this device and other devices. Communication can be achieved through wired means (such as USB, Ethernet cable, etc.) or wireless means (such as mobile network, WIFI, Bluetooth, etc.).

[0107] The bus transmits information between various components of a device, such as the processor, memory, input / output interfaces, and communication interfaces. The processor, memory, input / output interfaces, and communication interfaces communicate with each other within the device via the bus.

[0108] An embodiment of this application also provides a computer-readable storage medium storing computer-executable instructions for causing a computer to perform the LEO satellite real-time clock difference estimation method as described above.

[0109] It will be understood by those skilled in the art that all or some of the steps and systems in the methods disclosed above can be implemented as software, firmware, hardware, and suitable combinations thereof. Some or all of the physical components can be implemented as software executed by a processor, such as a central processing unit, digital signal processor, or microprocessor, or as hardware, or as an integrated circuit, such as an application-specific integrated circuit. Such software can be distributed on a computer-readable medium, which can include computer storage media (or non-transitory media) and communication media (or transient media). As is known to those skilled in the art, the term computer storage media includes volatile and non-volatile, removable and non-removable media implemented in any method or technology for storing information (such as computer-readable instructions, data structures, program modules, or other data). Computer storage media includes, but is not limited to, RAM, ROM, EEPROM, flash memory or other memory technologies, CD-ROM, digital versatile disc (DVD) or other optical disc storage, magnetic cartridges, magnetic tape, disk storage or other magnetic storage devices, or any other medium that can be used to store desired information and is accessible to a computer. Furthermore, it is well known to those skilled in the art that communication media typically contain computer-readable instructions, data structures, program modules, or other data in modulated data signals such as carrier waves or other transmission mechanisms, and may include any information delivery medium. In the foregoing description of this specification, references to terms such as "one embodiment," "another embodiment," or "some embodiments," etc., indicate that a specific feature, structure, material, or characteristic described in connection with an embodiment or example is included in at least one embodiment or example of this application. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0110] Those skilled in the art will understand that all or some of the steps in the methods disclosed above, as well as the functional modules / units in the systems and devices, can be implemented as software, firmware, hardware, or suitable combinations thereof.

[0111] The units described above as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0112] Furthermore, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0113] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes multiple instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods of the various embodiments of this application. The aforementioned storage medium includes various media capable of storing programs, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0114] In the several embodiments provided in this application, it should be understood that the disclosed apparatus and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of the units described above is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between apparatuses or units may be electrical, mechanical, or other forms.

[0115] Although embodiments of this application have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of this application, the scope of which is defined by the claims and their equivalents.

[0116] The above is a detailed description of the preferred embodiments of this application, but this application is not limited to the embodiments. Those skilled in the art can make various equivalent modifications or substitutions without departing from the spirit of this application, and these equivalent modifications or substitutions are all included within the scope defined by the claims of this application.

Claims

1. A method for estimating the real-time clock difference of LEO satellites, characterized in that, include: Acquire onboard observation data of LEO satellites, navigation satellite orbits, and navigation satellite clock biases; Based on the onboard observation data, orbit prediction is performed to obtain the predicted orbit of the LEO satellite; The geometric distance between the LEO satellite and the navigation satellite is obtained based on the predicted orbit of the LEO satellite and the orbit of the navigation satellite. The satellite observation equation is constructed based on the onboard observation data, the geometric distance, and the navigation satellite clock error. Solve the satellite observation equations to obtain the real-time clock difference of the LEO satellite.

2. The method for estimating the real-time clock difference of a LEO satellite according to claim 1, characterized in that, The process of predicting the orbit based on the onboard observation data to obtain the predicted orbit of the LEO satellite includes: The initial orbit and dynamic parameters of the LEO satellite were obtained from the onboard observation data using the least squares method. The predicted orbit of the LEO satellite is obtained by integrating the orbit based on the initial orbit and dynamic parameters of the LEO satellite.

3. A method for estimating the real-time clock difference of a LEO satellite according to claim 1 or 2, characterized in that, After obtaining the predicted orbit of the LEO satellite by performing orbit prediction based on the onboard observation data, the method further includes: The predicted LEO satellite orbit is transformed to convert the predicted LEO satellite orbit with the centroid as the reference point to the predicted LEO satellite orbit with the phase center as the reference point.

4. The method for estimating the real-time clock difference of a LEO satellite according to claim 1, characterized in that, The satellite-borne observation data includes pseudorange observations and phase observations, and the satellite observation equations include a first observation equation corresponding to the pseudorange observations and a second observation equation corresponding to the phase observations. The process of constructing satellite observation equations based on the onboard observation data, the geometric distance, and the navigation satellite clock bias includes: Based on the geometric distance, the ionospheric delay effect value, the speed of light value, and the navigation satellite clock error, a first observation equation corresponding to the pseudorange observation is constructed. Based on the geometric distance, carrier phase wavelength, ionospheric delay effect value, speed of light value, ambiguity, and navigation satellite clock error, a second observation equation corresponding to the phase observation is constructed.

5. The method for estimating the real-time clock difference of a LEO satellite according to claim 1, characterized in that, After constructing the satellite observation equation based on the onboard observation data, the geometric distance, and the navigation satellite clock error, the method further includes: The satellite observation equations are weighted according to a preset weighting principle, which is based on the elevation angle of the LEO satellite.

6. The method for estimating the real-time clock difference of a LEO satellite according to claim 1, characterized in that, Solving the satellite observation equations to obtain the real-time clock difference of the LEO satellite includes: Obtain initial values ​​for LEO satellite clock bias and ambiguity parameters; The satellite observation equation is solved using the sequential filtering method based on the initial values ​​of the LEO satellite clock bias and the ambiguity parameters to obtain the real-time clock bias of the LEO satellite.

7. The method for estimating the real-time clock difference of a LEO satellite according to claim 6, characterized in that, The step of solving the satellite observation equation based on the initial value of the LEO satellite clock bias using the sequential filtering method to obtain the real-time clock bias of the LEO satellite includes: The epochal states of LEO satellite clock errors are linked based on the state transition matrix; Solve the satellite observation equations, and derive the actual LEO satellite clock error from the initial value of the LEO satellite clock error based on the epoch state of the associated LEO satellite clock error.

8. The method for estimating the real-time clock difference of a LEO satellite according to claim 1, characterized in that, After solving the satellite observation equations to obtain the real-time clock difference of the LEO satellite, the method further includes: The accuracy of the real-time clock difference of the LEO satellite was evaluated by comparing the results of the post-event all-day solution and the overlapping clock difference comparison, and the accuracy evaluation results were obtained.

9. An electronic device, characterized in that, The electronic device includes a memory, a processor, a program stored in the memory and executable on the processor, and a data bus for enabling communication between the processor and the memory. When the program is executed by the processor, it implements the LEO satellite real-time clock difference estimation method as described in any one of claims 1 to 8.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer-executable instructions for causing a computer to perform the LEO satellite real-time clock difference estimation method as described in any one of claims 1 to 8.

Images