Timing method, device, equipment and medium based on low-orbit communication and guidance fusion signal

Abstract

The application relates to a time service method, device and equipment based on a low-orbit navigation fusion signal and a medium. The method comprises the following steps: receiving multi-epoch observation data for Doppler positioning; based on a multi-epoch clock drift invariable assumption, a multi-epoch clock difference correlation model is constructed, a receiver position coordinate is combined, a multi-epoch pseudo-range observation equation set is constructed, a weighted multi-epoch weighted clock difference solving model is constructed according to comprehensive error estimation of different epochs, and weighted least square solving is performed; multi-epoch observation data is screened; multi-epoch weighted least square clock difference solving is performed again according to the screened multi-epoch observation data and the multi-epoch weighted clock difference solving model, a receiver clock difference at a starting moment of an optimized multi-epoch period and a receiver clock drift in the multi-epoch period are obtained, an optimized current-epoch receiver clock difference is calculated to correct a receiver local time, and time service is completed. The method can significantly improve time service precision and stability.

Description

Technical Field

[0001] The present application relates to the field of high-precision timing technology for satellite navigation, and in particular to a timing method, apparatus, device and medium based on low-orbit communication and guidance fusion signals. Background Art

[0002] Currently, the construction of multiple low-orbit satellite constellations has entered the stage of large-scale deployment. With their significant cost advantages and global coverage capabilities, low-orbit satellite constellations have demonstrated unique value in modern aerospace information systems. On the one hand, low-orbit systems have strong anti-destruction capabilities, low transmission latency, and low-power links. On the other hand, the low orbit altitude makes the satellite operation cycle short and the update speed fast. If combined with large-scale constellation deployment, it can significantly increase the number of visible satellites and optimize the spatial geometry. In the field of low-orbit navigation enhancement, the communication and navigation fusion technology architecture builds the independent positioning capability of the low-orbit system by multiplexing communication resources to broadcast dedicated ranging signals. The receiver can perform Doppler positioning by receiving the navigation message and related information broadcast by the communication time slot signal. Based on the positioning, the user can independently calculate the receiver clock error to correct the local time, synchronize the local time with the satellite system time, and achieve time synchronization. Among them, the accuracy of the receiver clock error calculation directly affects the accuracy of the timing.

[0003] Existing positioning and timing methods based on LEO communication and guidance fusion signals are generally applied to static receiver scenarios. Only one satellite is needed at the current epoch to obtain the receiver clock error. However, due to the low pseudo-range measurement accuracy of LEO communication and guidance fusion signals and large atmospheric delay correction errors, the code pseudo-range accuracy fluctuates greatly, and the timing results are prone to large jumps. In some conditions, the satellite data used may even contain anomalies, resulting in timing accuracy not meeting requirements. Therefore, this method is highly dependent on the quality of the current satellite data, has poor stability, and cannot guarantee timing accuracy. Summary of the Invention

[0004] Based on this, it is necessary to provide a timing method, device, equipment and medium based on low-orbit communication and guidance fusion signals that can significantly improve the timing accuracy and stability in response to the above technical problems.

[0005] A timing method based on a low-orbit communication-conduction fusion signal, the method comprising:

[0006] The receiver receives multi-epoch observation data of the low-orbit communication and guidance fusion signal and obtains the receiver position coordinates through Doppler positioning;

[0007] Based on the assumption that multi-epoch clock drift is constant, a multi-epoch clock error correlation model is constructed;

[0008] By combining the multi-epoch clock error correlation model and the receiver position coordinates, a multi-epoch pseudo-range observation equation set is constructed. The least squares solution of the multi-epoch pseudo-range observation equation set is weighted according to the comprehensive error estimates of different epochs in the clock error solution process. A multi-epoch weighted clock error solution model is constructed and a weighted least squares solution is performed.

[0009] Calculate the clock error based on single-epoch observation data, and screen the multi-epoch observation data by comparing the receiver clock error calculated from the single-epoch observation data with the receiver clock error calculated using weighted least squares.

[0010] The multi-epoch weighted least squares clock error solution is performed again based on the screened multi-epoch observation data and the multi-epoch weighted clock error solution model to obtain the optimized receiver clock error at the start time of the multi-epoch period and the receiver clock drift within the multi-epoch period. The optimized current epoch receiver clock error is calculated to correct the receiver local time and complete the timing.

[0011] In one embodiment, receiving multi-epoch observation data of a low-orbit communication-guidance fusion signal by a receiver and obtaining the receiver position coordinates by Doppler positioning includes:

[0012] The receiver receives multi-epoch observation data within a certain time span of the low-orbit communication and guidance fusion signal, including multiple sets of satellite positions, satellite velocities, Doppler frequency observations, pseudorange observations, and error correction parameters;

[0013] After receiving no less than 4 sets of observation data, the initial value search algorithm is used to obtain the initial value of the receiver position and the initial value of the receiver clock drift, and the Doppler positioning equation group is constructed in parallel. The three-dimensional position coordinates of the receiver and the receiver clock drift are obtained by solving them through the Newton iteration method.

[0014] In one embodiment, an initial value search algorithm is used to obtain an initial value of the receiver position and an initial value of the receiver clock drift, and a Doppler positioning equation group is constructed in parallel. The three-dimensional position coordinates of the receiver and the receiver clock drift are obtained by solving the equation group using the Newton iteration method, including:

[0015] A grid-based initial value search algorithm is used to divide the surface area covered by the signals of the satellites receiving the signal into equally spaced grids. Then, a least squares solution is performed on each grid to search for the initial values ​​of the receiver position and receiver clock drift.

[0016] Construct the receiver static instantaneous Doppler observation equation, which is expressed as:

[0017] ;

[0018] in, is the Doppler frequency, The three-dimensional position coordinates of the receiver and receiver clock drift The four-dimensional unknown number to be found, is the Doppler frequency measurement error, is the frequency of satellite signal transmission, is the satellite speed, is the satellite position coordinate, is the speed of light;

[0019] Considering the four-dimensional unknowns, after receiving at least 4 sets of observation data, the Doppler positioning equations are constructed and solved by the Newton iteration method to obtain the three-dimensional position coordinates of the receiver. and receiver clock drift .

[0020] In one embodiment, based on the multi-epoch clock drift invariance assumption, a multi-epoch clock error correlation model is constructed, including:

[0021] Assume that the selected l The receiver clock drift in a short period of time consisting of epochs Unchanged and is an unknown number, and a multi-epoch clock error correlation model is constructed, which is expressed as:

[0022] ;

[0023] in, For the i The receiver clock error at the epoch, is the initial value of the receiver clock error at the start of the selected multi-epoch period, The receiver receives the i The time of the epoch observation data, The time when the receiver receives the observation data at the start of the selected multi-epoch period, , , No. l This epoch is also called the current epoch.

[0024] In one embodiment, a multi-epoch pseudo-range observation equation set is constructed by combining a multi-epoch clock error correlation model and a receiver position coordinate; wherein the pseudo-range observation equation for a single epoch in the multi-epoch pseudo-range observation equation set is expressed as:

[0025] ;

[0026] in, For the i The pseudorange value measured by the epoch receiver and corrected by satellite clock error, ionospheric delay, and tropospheric delay, is the three-dimensional position coordinate of the receiver obtained by Doppler positioning solution, For thei The satellite position coordinates at the epoch, For the i Pseudorange measurement error of the epoch.

[0027] In one embodiment, the least squares solution of the multi-epoch pseudorange observation equations is weighted according to the comprehensive error estimates of different epochs in the clock error solution process, a multi-epoch weighted clock error solution model is constructed, and a weighted least squares solution is performed, including:

[0028] Estimated i The pseudo-range measurement error and atmospheric propagation error in the epoch clock error solution process are synthesized based on the square root method. i Comprehensive error of epoch , expressed as:

[0029] ;

[0030] in, Indicates the i The standard deviation of the pseudorange measurement error of a certain satellite in the epoch, is the parameter related to the receiver in pseudorange measurement, For the i The received signal carrier-to-noise ratio of the epoch; For the i The standard deviation of the atmospheric propagation error of a certain satellite in the epoch, For the i Satellite elevation angle at the epoch, a 、 b is the set experience value;

[0031] Construct a weight matrix based on the comprehensive error of each epoch , expressed as:

[0032] ;

[0033] in, Extract diagonal elements. Indicates the i The weight of a satellite in an epoch participating in the weighted least squares solution;

[0034] Convert the multi-epoch pseudorange observation equations into the least squares solution form and substitute them into the weight matrix , a multi-epoch weighted clock error solution model is constructed and expressed as:

[0035] ;

[0036] in, is a coefficient matrix, where the first column is the receiver clock error at the start of the selected multi-epoch period coefficients of the second column, and the superscript denotes matrix transpose, is the time of the epoch observation data received by the receiver, i ; is the observation residual vector;

[0037] The multi-epoch weighted clock difference solution model is weighted least squares solved, and the and are calculated, and the and are substituted into the multi-epoch clock difference correlation model, and the receiver clock difference solved by weighted least squares of each epoch is calculated; wherein, , is the total number of selected epochs.

[0038] In one embodiment, the clock difference is solved according to single-epoch observation data, and the multi-epoch observation data is screened by comparing the difference between the receiver clock difference solved by single-epoch observation data and the receiver clock difference solved by weighted least squares, including:

[0039] The clock difference is solved according to single-epoch observation data, which is represented as:

[0040] ;

[0041] wherein, represents the receiver clock difference solved by single-epoch observation data of the i epoch, is the pseudorange value measured by the receiver of the i epoch after satellite clock difference, ionospheric delay and tropospheric delay correction, is the three-dimensional position coordinates of the receiver solved by Doppler positioning, is the satellite position coordinates of the i epoch;

[0042] The absolute value of the difference between and the receiver clock difference solved by weighted least squares is compared with the relationship between the set threshold T , if , the observation data of the i epoch is eliminated, and a set of screened multi-epoch observation data is obtained.

[0043] A time service device based on low-orbit navigation and positioning fusion signals, the device comprising:

[0044] ​​The data receiving and positioning module is used to use the receiver to receive multi-epoch observation data of the low-orbit communication and guidance fusion signal and obtain the receiver position coordinates through Doppler positioning;

[0045] The clock error correlation modeling module is used to construct a multi-epoch clock error correlation model based on the multi-epoch clock drift invariance assumption;

[0046] The multi-epoch weighted clock error solution module is used to construct a multi-epoch pseudo-range observation equation set by combining the multi-epoch clock error correlation model and the receiver position coordinates. The least squares solution form of the multi-epoch pseudo-range observation equation set is weighted according to the comprehensive error estimate of different epochs in the clock error solution process, thereby constructing a multi-epoch weighted clock error solution model and performing weighted least squares solution.

[0047] The data screening module is used to calculate the clock error based on the single-epoch observation data and screen the multi-epoch observation data by comparing the receiver clock error obtained by the single-epoch observation data with the receiver clock error obtained by the weighted least squares method.

[0048] The clock error optimization and local time correction module is used to re-perform the multi-epoch weighted least squares clock error solution based on the screened multi-epoch observation data and the multi-epoch weighted clock error solution model, obtain the optimized receiver clock error at the start time of the multi-epoch period and the receiver clock drift within the multi-epoch period, and calculate the optimized current epoch receiver clock error to correct the receiver local time and complete the timing.

[0049] A computer device includes a memory and a processor, wherein the memory stores a computer program, and when the processor executes the computer program, the following steps are implemented:

[0050] The receiver receives multi-epoch observation data of the low-orbit communication and guidance fusion signal and obtains the receiver position coordinates through Doppler positioning;

[0051] Based on the assumption that multi-epoch clock drift is constant, a multi-epoch clock error correlation model is constructed;

[0052] By combining the multi-epoch clock error correlation model and the receiver position coordinates, a multi-epoch pseudo-range observation equation set is constructed. The least squares solution of the multi-epoch pseudo-range observation equation set is weighted according to the comprehensive error estimates of different epochs in the clock error solution process. A multi-epoch weighted clock error solution model is constructed and a weighted least squares solution is performed.

[0053] Calculate the clock error based on single-epoch observation data, and screen the multi-epoch observation data by comparing the receiver clock error calculated from the single-epoch observation data with the receiver clock error calculated using weighted least squares.

[0054] The multi-epoch weighted least squares clock error solution is performed again based on the screened multi-epoch observation data and the multi-epoch weighted clock error solution model to obtain the optimized receiver clock error at the start time of the multi-epoch period and the receiver clock drift within the multi-epoch period. The optimized current epoch receiver clock error is calculated to correct the receiver local time and complete the timing.

[0055] A computer-readable storage medium stores a computer program, which, when executed by a processor, implements the following steps:

[0056] The receiver receives multi-epoch observation data of the low-orbit communication and guidance fusion signal and obtains the receiver position coordinates through Doppler positioning;

[0057] Based on the assumption that multi-epoch clock drift is constant, a multi-epoch clock error correlation model is constructed;

[0058] By combining the multi-epoch clock error correlation model and the receiver position coordinates, a multi-epoch pseudo-range observation equation set is constructed. The least squares solution of the multi-epoch pseudo-range observation equation set is weighted according to the comprehensive error estimates of different epochs in the clock error solution process. A multi-epoch weighted clock error solution model is constructed and a weighted least squares solution is performed.

[0059] Calculate the clock error based on single-epoch observation data, and screen the multi-epoch observation data by comparing the receiver clock error calculated from the single-epoch observation data with the receiver clock error calculated using weighted least squares.

[0060] The multi-epoch weighted least squares clock error solution is performed again based on the screened multi-epoch observation data and the multi-epoch weighted clock error solution model to obtain the optimized receiver clock error at the start time of the multi-epoch period and the receiver clock drift within the multi-epoch period. The optimized current epoch receiver clock error is calculated to correct the receiver local time and complete the timing.

[0061] The above-mentioned timing method, device, equipment and medium based on low-orbit communication and guidance fusion signals have the following advantages compared with the existing technology:

[0062] 1. By combining multi-epoch observation data for timing, the timing jumps and anomalies that may be caused by single-epoch observation data can be avoided, thereby improving the stability of timing. At the same time, by considering the comprehensive error estimation of different epochs in the clock error solution process, a multi-epoch weighted clock error solution model is constructed and weighted least squares solution is performed. This can reduce the impact of epochs with low observation quality on the receiver clock error solution accuracy, thereby improving the receiver clock error solution and timing accuracy.

[0063] 2. By comparing the difference between the receiver clock error calculated from single-epoch observation data and the receiver clock error calculated by weighted least squares, we can further screen high-quality multi-epoch observation data for receiver clock error optimization and local time correction, further improving the timing accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0064] Figure 1 1. A flowchart of a timing method based on low-orbit communication and conduction fusion signals in one embodiment;

[0065] Figure 2 1. A schematic diagram of a specific implementation process of a timing method based on a low-orbit communication-conduction fusion signal in one embodiment;

[0066] Figure 3 This is a structural block diagram of a timing device based on low-orbit communication and conduction fusion signals in one embodiment;

[0067] Figure 4 FIG. 1 is a diagram showing the internal structure of a computer device in one embodiment. DETAILED DESCRIPTION

[0068] In order to make the purpose, technical solutions and advantages of this application more clear, the following further describes this application in detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0069] In one embodiment, Figure 1 and Figure 2 As shown, a timing method based on low-orbit communication-conduction fusion signals is provided, comprising the following steps:

[0070] Step S1: Utilize a receiver to receive multi-epoch observation data of a low-orbit communication-guidance fusion signal, and obtain the receiver position coordinates through Doppler positioning.

[0071] Since the low-orbit communication and guidance fusion signal is a time-slot signal, the satellite signal reception time is not synchronized. Therefore, the receiver first needs to receive multi-epoch observation data within a certain time span, and then calculate the initial value of the receiver position and perform Doppler positioning based on the Doppler effect principle to obtain the receiver position coordinates.

[0072] Step S2: Based on the assumption that multi-epoch clock drift is constant, a multi-epoch clock error correlation model is constructed.

[0073] The multi-epoch clock drift invariance assumption means that the receiver clock drift is constant within a short period of time consisting of multiple epochs including the current epoch. Based on this assumption, the multi-epoch clock error correlation can be modeled as a linear function, which helps to reduce the number of unknown parameters and improve the efficiency of subsequent receiver clock error calculation.

[0074] Step S3, by combining the multi-epoch clock error correlation model and the receiver position coordinates, a multi-epoch pseudo-range observation equation group is constructed, and the least squares solution form of the multi-epoch pseudo-range observation equation group is weighted according to the comprehensive error estimate of different epochs in the clock error solution process, to construct a multi-epoch weighted clock error solution model and perform weighted least squares solution.

[0075] Compared to existing methods that only calculate receiver clock errors based on observation data from a single satellite in the current epoch, the multi-epoch pseudorange observation equations constructed in this application can fully utilize multi-epoch observation data, avoiding the difficulty in meeting timing accuracy requirements when single-epoch observation data exhibits anomalies. Furthermore, a multi-epoch weighted clock error solution model is constructed based on the comprehensive error estimates for different epochs during the clock error solution process, and a weighted least squares solution is performed. This model can account for differences in the quality of receiver observation data from different satellites at different epochs, helping to reduce interference from low-quality observations and improve the accuracy of receiver clock error solutions.

[0076] Step S4, performing clock error calculation based on single epoch observation data, and screening multi-epoch observation data by comparing the difference between the receiver clock error calculated from the single epoch observation data and the receiver clock error calculated by weighted least squares.

[0077] If there are outliers in the selected multi-epoch data, there will be a deviation between the clock error calculated by weighted least squares and the clock error calculated by single-epoch observation data, which will affect the accuracy of the receiver clock error. Therefore, by eliminating abnormal observation data through data screening, the accuracy of the receiver clock error can be further optimized.

[0078] Step S5: Re-perform the multi-epoch weighted least squares clock error solution based on the filtered multi-epoch observation data and the multi-epoch weighted clock error solution model to obtain the optimized receiver clock error at the start of the multi-epoch period and the receiver clock drift within the multi-epoch period, and calculate the optimized current epoch receiver clock error to correct the receiver local time and complete the timing.

[0079] The above-mentioned timing method based on low-orbit communication and guidance fusion signals makes full use of multi-epoch observation data, and considers the differences in the quality of observation data of different epochs to perform weighted least squares solution of the receiver clock error, while eliminating possible abnormal observation data. Compared with traditional methods, it can significantly improve the timing accuracy and stability.

[0080] In one embodiment, step S1 specifically includes: first, using a receiver to receive multi-epoch observation data within a certain time span of a low-orbit communication and guidance fusion signal, including multiple sets of satellite positions, satellite velocities, Doppler frequency observations, pseudorange observations, and error correction parameters. Then, after receiving at least four sets of observation data, an initial value search algorithm is used to obtain initial values ​​for the receiver position and receiver clock drift. A set of Doppler positioning equations is then constructed and solved using the Newton iteration method to obtain the receiver's three-dimensional position coordinates and receiver clock drift.

[0081] Specifically, a grid-based initial value search algorithm is first used to divide the surface area covered by the signal of the satellite receiving the signal into equally spaced grids, and then the least squares solution is performed on each grid to search for the initial value of the receiver position and the initial value of the receiver clock drift.

[0082] Then the receiver static instantaneous Doppler observation equation is constructed as follows:

[0083] ;

[0084] in, is the Doppler frequency, The three-dimensional position coordinates of the receiver and receiver clock drift The four-dimensional unknown number to be found, is the Doppler frequency measurement error, is the frequency of satellite signal transmission, is the satellite speed, is the satellite position coordinate, The speed of light.

[0085] Considering the four-dimensional unknowns, after receiving at least 4 sets of observation data, the Doppler positioning equations are constructed and solved by the Newton iteration method to obtain the three-dimensional position coordinates of the receiver. and receiver clock drift .

[0086] In one embodiment, step S2 specifically includes: assuming that the selected l The receiver clock drift in a short period of time consisting of epochs Unchanged, a multi-epoch clock error correlation model is constructed, which is expressed as:

[0087] ;

[0088] in, For the i The receiver clock error at the epoch, is the initial value of the receiver clock error at the start of the selected multi-epoch period, The receiver receives the iTime of epoch observation data, Time of epoch observation data received by the receiver, , , the l epoch is also called the current epoch. It should be noted that although the receiver clock drift solution has been obtained by Doppler positioning in step S1 of the above-mentioned time service method based on low-orbit navigation fusion signals, using the receiver clock drift solution will affect the accuracy of the receiver clock difference solution due to the insufficient accuracy of the Doppler frequency measurement of the navigation fusion signals. Therefore, when modeling the multi-epoch clock difference, the receiver clock drift is still considered as an unknown quantity.

[0089] In one embodiment, step S3 specifically comprises:

[0090] First, by combining the multi-epoch clock difference correlation model and the receiver position coordinates, a multi-epoch pseudo-range observation equation set is constructed; wherein the pseudo-range observation equation of a single epoch in the multi-epoch pseudo-range observation equation set is expressed as:

[0091] ;

[0092] wherein, is the pseudo-range value measured by the receiver at the i epoch after being corrected by the satellite clock difference, ionospheric delay and tropospheric delay, is the three-dimensional position coordinates of the receiver obtained by Doppler positioning, is the satellite position coordinates at the i epoch, is the pseudo-range measurement error at the i epoch.

[0093] By solving the multi-epoch pseudo-range observation equation set composed of l pseudo-range observation equations, and can be obtained, and the receiver clock difference of the current epoch can be obtained by substituting the multi-epoch clock difference correlation model. Compared with the solution of single-epoch observation data, the joint multi-epoch observation data can avoid the time service jump and abnormality caused by single-epoch observation data, and improve the stability of time service.

[0094] Furthermore, considering that the main errors in the clock error solution process are receiver position error, pseudorange measurement error, and atmospheric propagation error, the receiver position, already determined through Doppler positioning, is a deterministic error in the clock error solution process, affecting all epoch data uniformly and thus not being considered for weighting. However, the accuracy of the receiver's pseudorange measurement error for different satellites and atmospheric propagation error varies at different epochs. Constructing a reasonable weighting matrix based on the multi-epoch pseudorange observation equations for the pseudorange measurement error and atmospheric propagation error in the clock error solution process can help improve clock error solution accuracy.

[0095] The pseudo-range measurement error mainly lies in the measurement accuracy of the code phase, which is highly correlated with the satellite signal reception quality. It can be obtained by estimating the receiver signal carrier-to-noise ratio in the clock error solution process. i The standard deviation of the pseudorange measurement error of a satellite in an epoch is expressed as:

[0096] ;

[0097] in, is the parameter related to the receiver in pseudorange measurement, For the i The received signal-to-noise ratio of the epoch.

[0098] In addition, the magnitude of atmospheric propagation errors such as ionospheric delay and tropospheric delay is highly correlated with the satellite elevation angle. Satellites with smaller elevation angles usually have larger atmospheric propagation errors. i The standard deviation of the atmospheric propagation error of a satellite in the epoch is , estimated using the elevation angle empirical sine function model, specifically expressed as:

[0099] ;

[0100] in, For the i Satellite elevation angle at the epoch, a 、 b The experience value set.

[0101] For the above two types of random errors, if we simplify the assumptions that they are independent of each other and obey the normal distribution, the square root method is more consistent with their statistical characteristics. i Comprehensive error of epoch Expressed as:

[0102] .

[0103] Specifically, according to the comprehensive error of each epoch, a weight matrix is ​​constructed , expressed as:

[0104] ;

[0105] in, Extract diagonal elements. Indicates the i The weight of a satellite in an epoch participating in the weighted least squares solution. This formula shows that the epoch with a larger comprehensive error has a lower weight assigned to it, which is beneficial to reducing the impact of epochs with low observation quality on the accuracy of clock error solution and improving timing accuracy.

[0106] Furthermore, the pseudorange observation equation of each epoch in the multi-epoch pseudorange observation equation group is converted into:

[0107] ;

[0108] The matrix form of the multi-epoch pseudorange observation equations can be established and expressed as:

[0109] ;

[0110] in, is the observation residual vector; is a coefficient matrix, where the first column is the receiver clock error at the start of the selected multi-epoch period The second column is the receiver clock drift The coefficient of Represents matrix transpose; is the parameter to be estimated.

[0111] According to the least squares solution formula, the least squares solution form of the multi-epoch pseudorange observation equations can be obtained, which is expressed as:

[0112] .

[0113] The weight matrix constructed above Substituting the least squares solution form of the multi-epoch pseudorange observation equations, the multi-epoch weighted clock error solution model is constructed and expressed as:

[0114] .

[0115] Performing weighted least squares solution on the multi-epoch weighted clock error solution model, we can calculate and , and and Substitute into the multi-epoch clock error correlation model and calculate the receiver clock error obtained by weighted least squares solution of each epoch ;in, , is the total number of epochs selected.

[0116] In one embodiment, step S4 specifically includes: performing clock error calculation based on single epoch observation data, expressed as:

[0117] ;

[0118] in, Indicates the i Epoch is the receiver clock error obtained by solving the single epoch observation data.

[0119] Compare one by one The receiver clock error obtained by weighted least squares solution The absolute value of the difference between the two and the set threshold T relationship, if , then remove the i The observation data of the epochs are filtered to obtain a set of multi-epoch observation data. The filtered multi-epoch observation data can further optimize the receiver clock error solution accuracy, thereby significantly improving the timing accuracy.

[0120] In one embodiment, Figure 3 As shown, a timing device based on low-orbit communication and guidance fusion signals is provided, comprising:

[0121] The data receiving and positioning module 301 is used to use a receiver to receive multi-epoch observation data of the low-orbit communication and guidance fusion signal, and obtain the receiver position coordinates through Doppler positioning.

[0122] The clock error correlation modeling module 302 is used to construct a multi-epoch clock error correlation model based on the multi-epoch clock drift invariance assumption.

[0123] The multi-epoch weighted clock error solution module 303 is used to construct a multi-epoch pseudo-range observation equation group by combining the multi-epoch clock error correlation model and the receiver position coordinates, and to weight the least squares solution form of the multi-epoch pseudo-range observation equation group according to the comprehensive error estimate of different epochs in the clock error solution process, to construct a multi-epoch weighted clock error solution model and perform weighted least squares solution.

[0124] The data screening module 304 is used to perform clock error calculation based on single-epoch observation data, and to screen multi-epoch observation data by comparing the difference between the receiver clock error calculated from the single-epoch observation data and the receiver clock error calculated by weighted least squares.

[0125] The clock error optimization and local time correction module 305 is used to re-perform the multi-epoch weighted least squares clock error solution based on the filtered multi-epoch observation data and the multi-epoch weighted clock error solution model, obtain the optimized receiver clock error at the start time of the multi-epoch period and the receiver clock drift within the multi-epoch period, and calculate the optimized current epoch receiver clock error to correct the receiver local time and complete the time synchronization.

[0126] For the specific limitations of the timing device based on the low-orbit communication and conduction fusion signal, please refer to the limitations of the timing method based on the low-orbit communication and conduction fusion signal above, which will not be repeated here. The various modules in the above-mentioned timing device based on the low-orbit communication and conduction fusion signal can be implemented in whole or in part by software, hardware and their combination. The above-mentioned modules can be embedded in or independent of the processor in the computer device in the form of hardware, or can be stored in the memory of the computer device in the form of software, so that the processor can call and execute the operations corresponding to the above modules.

[0127] In one embodiment, a computer device is provided. The computer device may be a terminal, and its internal structure diagram may be as follows: Figure 4 As shown. The computer device includes a processor, memory, network interface, display screen and input device connected via a system bus. The processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system and a computer program. The internal memory provides an environment for the operation of the operating system and computer program in the non-volatile storage medium. The network interface of the computer device is used to communicate with an external terminal via a network connection. When the computer program is executed by the processor, a timing method based on low-orbit communication and conduction fusion signals is implemented. The display screen of the computer device can be a liquid crystal display or an electronic ink display screen, and the input device of the computer device can be a touch layer covering the display screen, or a button, trackball or touchpad provided on the computer device housing, or an external keyboard, touchpad or mouse.

[0128] Those skilled in the art will understand that Figure 4 The structure shown in the figure is only a block diagram of a part of the structure related to the solution of the present application, and does not constitute a limitation on the computer device to which the solution of the present application is applied. The specific computer device may include more or fewer components than shown in the figure, or combine certain components, or have a different component arrangement.

[0129] In one embodiment, a computer device is provided, including a memory and a processor, wherein the memory stores a computer program, and when the processor executes the computer program, the following steps are implemented:

[0130] The receiver receives multi-epoch observation data of the low-orbit communication and guidance fusion signal and obtains the receiver position coordinates through Doppler positioning;

[0131] Based on the assumption that multi-epoch clock drift is constant, a multi-epoch clock error correlation model is constructed;

[0132] By combining the multi-epoch clock error correlation model and the receiver position coordinates, a multi-epoch pseudo-range observation equation set is constructed. The least squares solution of the multi-epoch pseudo-range observation equation set is weighted according to the comprehensive error estimates of different epochs in the clock error solution process. A multi-epoch weighted clock error solution model is constructed and a weighted least squares solution is performed.

[0133] Calculate the clock error based on single-epoch observation data, and screen the multi-epoch observation data by comparing the receiver clock error calculated from the single-epoch observation data with the receiver clock error calculated using weighted least squares.

[0134] The multi-epoch weighted least squares clock error solution is performed again based on the screened multi-epoch observation data and the multi-epoch weighted clock error solution model to obtain the optimized receiver clock error at the start time of the multi-epoch period and the receiver clock drift within the multi-epoch period. The optimized current epoch receiver clock error is calculated to correct the receiver local time and complete the timing.

[0135] In one embodiment, a computer-readable storage medium is provided, on which a computer program is stored. When the computer program is executed by a processor, the following steps are implemented:

[0136] The receiver receives multi-epoch observation data of the low-orbit communication and guidance fusion signal and obtains the receiver position coordinates through Doppler positioning;

[0137] Based on the assumption that multi-epoch clock drift is constant, a multi-epoch clock error correlation model is constructed;

[0138] By combining the multi-epoch clock error correlation model and the receiver position coordinates, a multi-epoch pseudo-range observation equation set is constructed. The least squares solution of the multi-epoch pseudo-range observation equation set is weighted according to the comprehensive error estimates of different epochs in the clock error solution process. A multi-epoch weighted clock error solution model is constructed and a weighted least squares solution is performed.

[0139] Calculate the clock error based on single-epoch observation data, and screen the multi-epoch observation data by comparing the receiver clock error calculated from the single-epoch observation data with the receiver clock error calculated using weighted least squares.

[0140] The multi-epoch weighted least squares clock error solution is performed again based on the screened multi-epoch observation data and the multi-epoch weighted clock error solution model to obtain the optimized receiver clock error at the start time of the multi-epoch period and the receiver clock drift within the multi-epoch period. The optimized current epoch receiver clock error is calculated to correct the receiver local time and complete the timing.

[0141] Those skilled in the art will understand that all or part of the processes in the above-mentioned embodiments can be implemented by instructing the relevant hardware through a computer program. The computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to memory, storage, database or other media used in the embodiments provided in this application may include non-volatile and / or volatile memory. Non-volatile memory may include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM) or flash memory. Volatile memory may include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in many forms such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), Synchronous Link DRAM (SLDRAM), Rambus direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM), etc.

[0142] The technical features of the above embodiments can be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0143] The above-described embodiments merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present application. It should be noted that a person skilled in the art may make various modifications and improvements without departing from the scope of the present application, and such modifications and improvements are all within the scope of protection of the present application.

Claims

1. A timing method based on low-orbit communication and guidance fusion signals, characterized in that: The method comprises: The receiver receives multi-epoch observation data of the low-orbit communication and guidance fusion signal and obtains the receiver position coordinates through Doppler positioning; Based on the assumption that multi-epoch clock drift is constant, a multi-epoch clock error correlation model is constructed; By combining the multi-epoch clock error correlation model and the receiver position coordinates, a multi-epoch pseudo-range observation equation group is constructed, and the least squares solution form of the multi-epoch pseudo-range observation equation group is weighted according to the comprehensive error estimates of different epochs in the clock error solution process, a multi-epoch weighted clock error solution model is constructed and a weighted least squares solution is performed; wherein the comprehensive error estimate is to estimate the pseudo-range measurement error and the atmospheric propagation error in the clock error solution process of each epoch, and the comprehensive error of each epoch is synthesized based on the square root method; Calculate the clock error based on single-epoch observation data, and screen the multi-epoch observation data by comparing the receiver clock error calculated from the single-epoch observation data with the receiver clock error calculated using weighted least squares. Re-performing a multi-epoch weighted least squares clock error solution based on the filtered multi-epoch observation data and the multi-epoch weighted clock error solution model to obtain an optimized receiver clock error at the start of the multi-epoch period and the receiver clock drift within the multi-epoch period, and calculating the optimized current epoch receiver clock error to correct the receiver local time, thereby completing the timing; Among them, the clock error is calculated based on the single epoch observation data, and the multi-epoch observation data is screened by comparing the difference between the receiver clock error calculated from the single epoch observation data and the receiver clock error obtained by weighted least squares, including: The clock error is calculated based on single epoch observation data and is expressed as: ； in, Indicates the i The receiver clock error is obtained by solving the single epoch observation data. For the i The pseudorange value measured by the epoch receiver and corrected by satellite clock error, ionospheric delay, and tropospheric delay, is the three-dimensional position coordinate of the receiver obtained by Doppler positioning solution, For the i Satellite position coordinates at the epoch; Compare one by one The receiver clock error obtained by weighted least squares solution The absolute value of the difference between the two and the set threshold T relationship, if , then remove the i The observation data of the epoch are obtained to obtain a set of filtered multi-epoch observation data.

2. The method according to claim 1, characterized in that The receiver receives multi-epoch observation data of the low-orbit communication and guidance fusion signal and obtains the receiver position coordinates through Doppler positioning, including: The receiver receives multi-epoch observation data within a certain time span of the low-orbit communication and guidance fusion signal, including multiple sets of satellite positions, satellite velocities, Doppler frequency observations, pseudorange observations, and error correction parameters; After receiving no less than 4 sets of observation data, the initial value search algorithm is used to obtain the initial value of the receiver position and the initial value of the receiver clock drift, and the Doppler positioning equation group is constructed in parallel. The three-dimensional position coordinates of the receiver and the receiver clock drift are obtained by solving them through the Newton iteration method.

3. The method according to claim 2, characterized in that The initial value search algorithm is used to obtain the initial value of the receiver position and the initial value of the receiver clock drift. The Doppler positioning equations are constructed in parallel and solved by the Newton iteration method to obtain the receiver's three-dimensional position coordinates and receiver clock drift, including: A grid-based initial value search algorithm is used to divide the surface area covered by the signals of the satellites receiving the signal into equally spaced grids. Then, a least squares solution is performed on each grid to search for the initial values ​​of the receiver position and receiver clock drift. Construct the receiver static instantaneous Doppler observation equation, which is expressed as: ； in, is the Doppler frequency, The three-dimensional position coordinates of the receiver and receiver clock drift The four-dimensional unknown number to be found, is the Doppler frequency measurement error, is the frequency of satellite signal transmission, is the satellite speed, is the satellite position coordinate, is the speed of light; Considering the four-dimensional unknowns, after receiving at least 4 sets of observation data, the Doppler positioning equations are constructed and solved by the Newton iteration method to obtain the three-dimensional position coordinates of the receiver. and receiver clock drift .

4. The method according to any one of claims 1 to 3, characterized in that Based on the assumption that multi-epoch clock drift is constant, a multi-epoch clock error correlation model is constructed, including: Assume that the selected l The receiver clock drift in a short period of time consisting of epochs Unchanged and is an unknown number, and a multi-epoch clock error correlation model is constructed, which is expressed as: ； in, For the i The receiver clock error at the epoch, is the initial value of the receiver clock error at the start of the selected multi-epoch period, The receiver receives the i The time of the epoch observation data, The time when the receiver receives the observation data at the start of the selected multi-epoch period, , , No. l This epoch is also called the current epoch.

5. The method according to claim 4, characterized in that By combining the multi-epoch clock error correlation model and the receiver position coordinates, a multi-epoch pseudo-range observation equation group is constructed; wherein the pseudo-range observation equation of a single epoch in the multi-epoch pseudo-range observation equation group is expressed as: ； in, For the i The pseudorange value measured by the epoch receiver and corrected by satellite clock error, ionospheric delay, and tropospheric delay, is the three-dimensional position coordinate of the receiver obtained by Doppler positioning solution, For the i The satellite position coordinates at the epoch, For the i Pseudorange measurement error of the epoch.

6. The method according to claim 5, characterized in that The least squares solution of the multi-epoch pseudorange observation equations is weighted according to the comprehensive error estimates of different epochs in the clock error solution process, and a multi-epoch weighted clock error solution model is constructed and a weighted least squares solution is performed, including: Estimated i The pseudo-range measurement error and atmospheric propagation error in the epoch clock error solution process are synthesized based on the square root method. i Comprehensive error of epoch , expressed as: ； in, Indicates the i The standard deviation of the pseudorange measurement error of a certain satellite in the epoch, is the parameter related to the receiver in pseudorange measurement, For the i The received signal carrier-to-noise ratio of the epoch; For the i The standard deviation of the atmospheric propagation error of a certain satellite in the epoch, For the i Satellite elevation angle at the epoch, a 、 b is the set experience value; Construct a weight matrix based on the comprehensive error of each epoch , expressed as: ； in, Extract diagonal elements. Indicates the i The weight of a satellite in an epoch participating in the weighted least squares solution; Convert the multi-epoch pseudorange observation equations into the least squares solution form and substitute the weight matrix , a multi-epoch weighted clock error solution model is constructed and expressed as: ； in, is a coefficient matrix, where the first column is the receiver clock error at the start of the selected multi-epoch period The second column is the receiver clock drift The coefficient of represents the matrix transpose, The receiver receives the i The time of the epoch observation data, ; is the observation residual vector; The multi-epoch weighted clock error solution model is solved by weighted least squares to obtain and , and and Substitute into the multi-epoch clock error correlation model and calculate the receiver clock error obtained by weighted least squares solution of each epoch ;in, , is the total number of epochs selected.

7. A timing device based on low-orbit communication and conduction fusion signals, characterized in that: The device comprises: The data receiving and positioning module is used to use the receiver to receive multi-epoch observation data of the low-orbit communication and guidance fusion signal and obtain the receiver position coordinates through Doppler positioning; The clock error correlation modeling module is used to construct a multi-epoch clock error correlation model based on the multi-epoch clock drift invariance assumption; A multi-epoch weighted clock error solution module is configured to construct a multi-epoch pseudo-range observation equation set by combining the multi-epoch clock error correlation model and the receiver position coordinates, and to weight the least squares solution form of the multi-epoch pseudo-range observation equation set according to the comprehensive error estimates of different epochs in the clock error solution process, thereby constructing a multi-epoch weighted clock error solution model and performing a weighted least squares solution; wherein the comprehensive error estimate is to estimate the pseudo-range measurement error and atmospheric propagation error in the clock error solution process of each epoch, and to synthesize the comprehensive error of each epoch based on the square root method; The data screening module is used to calculate the clock error based on the single-epoch observation data and screen the multi-epoch observation data by comparing the receiver clock error obtained by the single-epoch observation data with the receiver clock error obtained by the weighted least squares method. The clock error optimization and local time correction module is used to re-perform the multi-epoch weighted least squares clock error solution based on the filtered multi-epoch observation data and the multi-epoch weighted clock error solution model, obtain the optimized receiver clock error at the start time of the multi-epoch period and the receiver clock drift within the multi-epoch period, and calculate the optimized current epoch receiver clock error to correct the receiver local time and complete the timing; The data screening module is specifically used for: The clock error is calculated based on single epoch observation data and is expressed as: ； in, Indicates the i The receiver clock error is obtained by solving the single epoch observation data. For the i The pseudorange value measured by the epoch receiver and corrected by satellite clock error, ionospheric delay, and tropospheric delay, is the three-dimensional position coordinate of the receiver obtained by Doppler positioning solution, For the i Satellite position coordinates at the epoch; Compare one by one The receiver clock error obtained by weighted least squares solution The absolute value of the difference between the two and the set threshold T relationship, if , then remove the i The observation data of the epoch are obtained to obtain a set of filtered multi-epoch observation data.

8. A computer device comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the processor executes the computer program, the steps of the method according to any one of claims 1 to 6 are implemented.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 6 are implemented.

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