Correction method and system for satellite-ground time difference, product, equipment and storage medium

Abstract

The invention discloses a correction method, system, product and equipment for satellite-to-ground time difference and a storage medium, belongs to the technical field of remote sensing satellite measurement and control, and solves the problem that more accurate and effective data cannot be obtained due to the fact that remarkable abnormal satellite-to-ground time difference interference caused by factors such as error codes in original data is not considered in the prior art. And the accuracy of satellite-ground time difference correction is influenced. Acquiring and analyzing satellite telemetry of the target satellite to obtain on-satellite time of the target satellite and corresponding ground time; obtaining a satellite-ground time difference data set of the target satellite based on the on-satellite time of the target satellite and the corresponding ground time; processing the satellite-to-ground time difference of the target satellite to generate a centralized timing instruction, screening out an abnormal value of a satellite-to-ground time difference data set of the target satellite, and processing a normal value of the satellite-to-ground time difference data set of the target satellite to generate a uniform timing instruction; and uploading the target satellite to complete satellite-ground time difference correction. The satellite-ground time difference correction method is used for realizing rapid and accurate satellite-ground time difference correction.

Description

Technical Field

[0001] This invention relates to the field of remote sensing satellite telemetry and control technology, specifically to methods, systems, products, equipment, and storage media for correcting time differences between satellites and the ground. Background Technology

[0002] The time delay between satellite and ground stations refers to the time delay between satellite signal transmission from space and reception on the ground. In aerospace telemetry and control systems, accurate monitoring of this time delay is crucial, serving as a key link in ensuring system timing and positioning accuracy, and significantly impacting communication efficiency and measurement precision. In satellite telemetry and control systems, time synchronization primarily serves three functions: providing a unified time reference for measurement information; improving the accuracy of one-way ranging; and providing satellites with a high-precision frequency source reference.

[0003] However, due to the complex space environment and the satellite's approaching the end of its service life, the onboard navigation receiver may fail. In this situation, the satellite cannot obtain valid navigation receiver time information and correct its time. The time deviation caused by the onboard reference crystal oscillator gradually accumulates, requiring time calibration. Generally, centralized and uniform time calibration methods are used.

[0004] Centralized Time Synchronization: The satellite has the function of centralized time synchronization in both forward and reverse directions. When the navigation receiver fails for an extended period and the onboard time deviates from the actual time, the ground can adjust the time parameters in either the forward or reverse direction via remote control commands, based on the direction of the deviation. This allows the satellite management software to adjust the time of the time management unit based on the current onboard time, adding or subtracting the specified time parameters in the uplink commands to complete centralized time synchronization and correct the absolute error in satellite-to-ground time.

[0005] Uniform Time Calibration: The satellite possesses the capability for forward or reverse uniform time calibration. When the navigation receiver experiences prolonged failure and the onboard time periodically accumulates a time difference with the actual time due to deviations in the onboard reference crystal oscillator, the ground can use uplink forward or reverse uniform time calibration remote control commands to regularly increase or decrease the onboard time by a small time interval at specified intervals, thereby improving the accuracy of the accumulated onboard time. The satellite maintenance software continuously executes the uniform time calibration process until the ground uplink command prohibits uniform time calibration.

[0006] In the prior art, Chinese patent document CN116243584A discloses a "Method and System for Testing and Correcting the Time Difference Between a Geostationary Satellite and its Ground," which obtains the two-way transmission delay between the satellite and ground based on the remote control command transmission time of the ground-transmitted delay test command, the satellite's forwarding delay, and the telemetry data reception time of the ground test equipment. A first satellite-to-ground time difference is set based on the two-way transmission delay, the time of the time synchronization command transmission from the ground test equipment, and the time of the time synchronization command reception from the satellite. A second satellite-to-ground time difference is obtained based on the first transmission time and the first reception time of the second telemetry data. The satellite's time is then corrected based on the first satellite-to-ground time difference, the second satellite-to-ground time difference, and the two-way transmission delay. However, this technical solution does not consider the significant abnormal satellite-to-ground time difference interference caused by factors such as bit errors in the original data, which may lead to the inability to obtain more accurate and effective data, affecting the accuracy of satellite-to-ground time difference correction.

[0007] In the prior art, Chinese patent document CN116883617A discloses a "method and system for constructing a DEM of the permanently shadowed area of ​​the moon based on calibrated altimetry data." This method calculates the absolute value of the difference between the slope value of each grid cell and the median slope value within a certain window centered on that grid cell, and sets a threshold for the absolute value of the difference to filter outliers. However, this technical solution only discloses the use of the absolute value of the difference between the medians to distinguish between outliers and normal values, without disclosing the specific process for filtering outliers.

[0008] In summary, existing technologies suffer from the technical problem that they fail to consider significant abnormal satellite-to-ground time difference interference caused by factors such as bit errors in the original data, resulting in the inability to obtain more accurate and effective data and affecting the accuracy of satellite-to-ground time difference correction. Summary of the Invention

[0009] This invention solves the technical problem in the prior art that the significant abnormal satellite-to-ground time difference interference caused by factors such as bit errors in the original data cannot be considered, which leads to the inability to obtain more accurate and effective data and affects the accuracy of satellite-to-ground time difference correction.

[0010] The present invention provides a method for correcting satellite-to-ground time difference, comprising the following steps: Step 1: Acquire and parse the satellite telemetry data of the target satellite to obtain the satellite's onboard time and corresponding ground time; Step 2: Based on the onboard time of the target satellite and the corresponding ground time, obtain the satellite-to-ground time difference dataset of the target satellite; Step 3: Process the satellite-to-ground time difference of the target satellite, generate centralized time synchronization instructions, filter out outliers in the satellite-to-ground time difference dataset of the target satellite, process the normal values ​​in the satellite-to-ground time difference dataset of the target satellite, and generate uniform time synchronization instructions. Step 4: Based on centralized or uniform time synchronization instructions, upload the time difference to the target satellite to complete the satellite-to-ground time difference correction.

[0011] Furthermore, in one embodiment of the present invention, the processing of the satellite-to-ground time difference in step 3 specifically involves: A reference satellite is selected, and its average time difference between the satellite and the ground is obtained. The time difference between the target satellite's time difference and the reference satellite's average time difference between the satellite and the ground is used as the processing result to generate a centralized time synchronization command.

[0012] Furthermore, in one embodiment of the present invention, the outlier removal of the target satellite's satellite-to-ground time difference dataset in step 3 specifically involves: Step 31: Randomly select on-board time and ground time point pairs at different times in the satellite-to-ground time difference dataset of two sets of target satellites without repetition, construct a straight line equation, and distinguish normal values ​​from outliers in the other data in the satellite-to-ground time difference dataset of the target satellites based on the distance between the other data in the satellite-to-ground time difference dataset and the straight line formed by the straight line equation, and count the number of normal values. Step 32: Preset the number of iterations, iterate through step 31, select the case with the most normal values, and filter out the outliers at this time.

[0013] Furthermore, in one embodiment of the present invention, the step of distinguishing normal values ​​and outliers in the other data in the target satellite's satellite-to-ground time difference dataset based on the distance between other data in the target satellite's satellite-to-ground time difference dataset and the straight line formed by the straight line equation specifically involves: Obtain the median of the satellite-to-ground time difference dataset of the target satellite. Calculate the difference between each data point in the satellite-to-ground time difference dataset and the median to obtain a set S'. Use the median of set S' as a threshold to determine whether the distance between other data points in the satellite-to-ground time difference dataset and the straight line formed by the linear equation is greater than the threshold. If so, the data is an outlier; otherwise, it is a normal value.

[0014] Furthermore, in one embodiment of the present invention, step 3 involves processing the normal values ​​of the target satellite's satellite-to-ground time difference dataset to generate a uniform time synchronization command, specifically as follows: The normal values ​​are subjected to least squares linear fitting to obtain the fitted straight line equation. The fitted straight line equation is used as the processing result to generate a uniform time calibration command.

[0015] The present invention discloses a correction system for satellite-to-ground time difference, which is constructed based on the above method and includes the following modules: Module 1 acquires and parses the satellite telemetry data of the target satellite to obtain the satellite's onboard time and corresponding ground time. Module 2 obtains the satellite-to-ground time difference dataset based on the satellite's onboard time and corresponding ground time; Module 3 processes the satellite-to-ground time difference of the target satellite, generates centralized time synchronization instructions, filters out outliers in the satellite-to-ground time difference dataset of the target satellite, processes the normal values ​​in the satellite-to-ground time difference dataset of the target satellite, and generates uniform time synchronization instructions. Module 4, based on centralized or uniform time synchronization commands, uploads data to the target satellite to complete the satellite-to-ground time difference correction.

[0016] The computer program product described in this invention includes a computer program or instructions that, when executed by a processor, implement the aforementioned method for correcting satellite-to-ground time difference.

[0017] The electronic device of the present invention includes a processor, a communication interface, a memory, and a communication bus, wherein the processor, the communication interface, and the memory communicate with each other through the communication bus. Memory, used to store computer programs; When the processor executes a program stored in memory, it implements any of the above-described methods for correcting the time difference between satellite and ground.

[0018] The present invention provides a computer-readable storage medium storing a computer program, which, when executed by a processor, implements any of the aforementioned methods for correcting satellite-to-ground time differences.

[0019] This invention solves the technical problem in existing technologies where significant abnormal satellite-to-ground time difference interference caused by factors such as bit errors in the original data fails to be considered, resulting in the inability to obtain more accurate and effective data and affecting the accuracy of satellite-to-ground time difference correction. Specific beneficial effects include: 1. This invention proposes a method for correcting satellite-to-ground time difference. By processing the satellite-to-ground time difference of the target satellite using different methods, it generates centralized or uniform time correction commands to achieve satellite-to-ground time difference correction. To obtain more accurate time correction information, this invention filters out significant abnormal satellite-to-ground time difference interference caused by factors such as bit errors in the original data, making the fitting results more effective and improving the accuracy of satellite-to-ground time difference correction. 2. This invention proposes a correction method for satellite-to-ground time difference, which can achieve accurate correction of satellite-to-ground time difference for low-orbit satellites. It has a wide range of applications. Furthermore, by designing an on-board time correction method, it provides another source for obtaining on-board time, achieving double insurance, further extending the on-orbit life of satellites, acquiring more remote sensing data, creating economic value, and promoting the development of aerospace technology. This technology has been applied to the operational Jilin-1 satellite constellation, successfully rescuing satellites that had experienced navigation failures, enabling them to continue performing their missions. Attached Figure Description

[0020] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the following description of the embodiments taken in conjunction with the accompanying drawings, wherein: Figure 1 This is a flowchart of the correction method for satellite-to-ground time difference described in Implementation Method 1; Figure 2 This is a pseudocode diagram of the method for screening outliers and fitting satellite-to-ground time difference as described in Implementation Method 3. Detailed Implementation

[0021] Various embodiments of the present invention will now be clearly and completely described with reference to the accompanying drawings. The embodiments described with reference to the drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0022] Implementation Method 1: A method for correcting satellite-to-ground time difference, comprising the following steps: Step 1: Acquire and parse the satellite telemetry data of the target satellite to obtain the satellite's onboard time and corresponding ground time; Step 2: Based on the onboard time of the target satellite and the corresponding ground time, obtain the satellite-to-ground time difference dataset of the target satellite; Step 3: Process the satellite-to-ground time difference of the target satellite, generate centralized time synchronization instructions, filter out outliers in the satellite-to-ground time difference dataset of the target satellite, process the normal values ​​in the satellite-to-ground time difference dataset of the target satellite, and generate uniform time synchronization instructions. Step 4: Based on centralized or uniform time synchronization instructions, upload the time difference to the target satellite to complete the satellite-to-ground time difference correction.

[0023] For satellites with malfunctioning navigation receivers, time correction via ground-based methods is necessary to compensate for onboard reference crystal oscillator deviations, as the satellite's time cannot be corrected using the receiver. Traditional methods for satellite-to-ground time difference correction often overlook significant abnormalities caused by bit errors and other factors in the original data, resulting in inaccurate and ineffective data and affecting the precision of satellite-to-ground time difference correction.

[0024] To address the aforementioned problems, this embodiment provides a method for correcting satellite-to-ground time differences. For example... Figure 1 As shown, by tracking passing satellites, the ground station performs telemetry reception on satellites whose navigation receivers have failed, analyzes the on-board time in the telemetry, and calculates the satellite-to-ground time difference with the ground time when the corresponding frame is received. This serves as the basis for centralized and uniform time synchronization on the ground, filtering out significant abnormal satellite-to-ground time difference interference caused by factors such as bit errors in the original data, thereby obtaining more accurate and effective data.

[0025] Different satellite models have different telemetry formats, and the on-board time information, which includes microseconds, needs to be extracted from the telemetry data according to the corresponding telemetry protocol.

[0026] In this embodiment, the satellite telemetry received by the ground station has a time stamp encoding, which needs to be parsed into ground time information with microseconds according to the ground station protocol.

[0027] In this embodiment, the satellite-to-ground time difference is the satellite time minus its corresponding ground time.

[0028] Implementation Method Two: This implementation method further defines the satellite-to-ground time difference correction method described in Implementation Method One. In step 3, the satellite-to-ground time difference of the target satellite is processed, specifically as follows: A reference satellite is selected, and its average time difference between the satellite and the ground is obtained. The time difference between the target satellite's time difference and the reference satellite's average time difference between the satellite and the ground is used as the processing result to generate a centralized time synchronization command.

[0029] In this embodiment, a satellite with a normally functioning navigation receiver is selected as the reference satellite. Its average satellite-to-ground time difference over a period of time is calculated. The target satellite's average satellite-to-ground time difference is aligned with that of the reference satellite. The difference between the latest satellite-to-ground time difference of the target satellite and the average satellite-to-ground time difference of the reference satellite is calculated, and a centralized time synchronization command is generated for centralized time synchronization.

[0030] The reference satellite selected in this embodiment should have a properly functioning navigation receiver to ensure the accuracy of the satellite's on-board time.

[0031] In this embodiment, the time difference ΔT between the target satellite and the reference satellite is obtained by comparing the satellite time difference with that of the reference satellite. Centralized time calibration is then performed, that is, the on-board time is immediately increased or decreased by ΔT as compensation based on whether ΔT is positive or negative.

[0032] Implementation Method 3: This implementation method further defines the satellite-to-ground time difference correction method described in Implementation Method 1. Specifically, step 3, which involves filtering out outliers from the target satellite's satellite-to-ground time difference dataset, involves: Step 31: Randomly select on-board time and ground time point pairs at different times in the satellite-to-ground time difference dataset of two sets of target satellites without repetition, construct a straight line equation, and distinguish normal values ​​from outliers in the other data in the satellite-to-ground time difference dataset of the target satellites based on the distance between the other data in the satellite-to-ground time difference dataset and the straight line formed by the straight line equation, and count the number of normal values. Step 32: Preset the number of iterations, iterate through step 31, select the case with the most normal values, and filter out the outliers at this time.

[0033] Based on the distance between other data in the target satellite's satellite-to-ground time difference dataset and the straight line formed by the linear equation, the other data in the target satellite's satellite-to-ground time difference dataset are distinguished as normal values ​​and outliers, specifically as follows: Obtain the median of the satellite-to-ground time difference dataset of the target satellite. Calculate the difference between each data point in the satellite-to-ground time difference dataset and the median to obtain a set S'. Use the median of set S' as a threshold to determine whether the distance between other data points in the satellite-to-ground time difference dataset and the straight line formed by the linear equation is greater than the threshold. If so, the data is an outlier; otherwise, it is a normal value.

[0034] In step 3, the normal values ​​of the target satellite's satellite-to-ground time difference dataset are processed to generate a uniform time synchronization command, specifically as follows: The normal values ​​are subjected to least squares linear fitting to obtain the fitted straight line equation. The fitted straight line equation is used as the processing result to generate a uniform time calibration command.

[0035] This implementation method uses least-squares linear fitting to determine the rate of change of the satellite-to-ground time difference after outlier removal. When removing outliers, pairs of points (ground time, satellite time) are randomly selected from the original data without repetition. Normal and outlier values ​​are determined based on the distance between other data points and the straight line formed by the selected two points. The system fits the system to the normal values ​​when the most normal values ​​are obtained. Linear fitting is chosen because, firstly, plotting and observing the points shows that the linear function matches the actual trend of the satellite-to-ground time difference; secondly, the linear function aligns with the principle of uniform time synchronization. The specific steps for least-squares linear fitting of the satellite-to-ground time difference after outlier removal are as follows: Figure 2 The pseudocode is shown in the figure.

[0036] The original data consists of multiple sets of ground times and their corresponding satellite-to-ground time differences. Two sets are randomly selected without repetition. The equation of a straight line passing through these two sets of data is calculated, with ground time on the x-axis and satellite time on the y-axis. Then, using the median absolute deviation of the satellite-to-ground time difference as a benchmark, all data in the original data are distinguished as normal or outliers based on the straight line equation, and the number of normal values ​​is counted. This process is iterated multiple times, and the case with the most normal values ​​is selected. All normal values ​​at this point are considered valid data, and a least-squares linear fit is performed. The resulting straight line equation is the final fitted result.

[0037] This implementation method uses fitting to obtain the quantified result of the periodic variation in the satellite-to-ground time difference caused by factors such as crystal oscillators, i.e., the slope k. Based on the principle of uniform time synchronization, every Δt time interval, the satellite time needs to be increased or decreased by kΔt as compensation, depending on the sign of k, to ensure that the corrected satellite-to-ground time difference remains stable over the long term. Corresponding centralized and uniform time synchronization commands are generated according to the satellite-to-ground communication protocol, and these commands are promptly uploaded.

[0038] Implementation Method 4: A satellite-to-ground time difference correction system described in this implementation method is constructed based on the method described in Implementation Method 1 and includes the following modules: Module 1 acquires and parses the satellite telemetry data of the target satellite to obtain the satellite's onboard time and corresponding ground time. Module 2 obtains the satellite-to-ground time difference dataset based on the satellite's onboard time and corresponding ground time; Module 3 processes the satellite-to-ground time difference of the target satellite, generates centralized time synchronization instructions, filters out outliers in the satellite-to-ground time difference dataset of the target satellite, processes the normal values ​​in the satellite-to-ground time difference dataset of the target satellite, and generates uniform time synchronization instructions. Module 4, based on centralized or uniform time synchronization commands, uploads data to the target satellite to complete the satellite-to-ground time difference correction.

[0039] Implementation Method 5: A computer program product, comprising a computer program or instructions that, when executed by a processor, implement any of the above-described methods for correcting satellite-to-ground time differences.

[0040] Implementation Method Six: An electronic device, characterized in that it includes a processor, a communication interface, a memory, and a communication bus, wherein the processor, the communication interface, and the memory communicate with each other through the communication bus; Memory, used to store computer programs; When the processor executes a program stored in memory, it implements any of the above-described methods for correcting the time difference between satellite and ground.

[0041] Implementation Method Seven: A computer-readable storage medium, characterized in that the computer-readable storage medium stores a computer program, which, when executed by a processor, implements any of the above-described methods for correcting satellite-to-ground time differences.

[0042] The foregoing has provided a detailed description of the method, system, product, device, and storage medium for correcting satellite-to-ground time differences proposed in this invention. Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of this invention. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this invention. Therefore, the content of this specification should not be construed as a limitation of this invention.

Claims

1. A correction method for satellite-ground time difference, characterized in that, The method comprises the following steps: Step 1: obtaining and analyzing satellite telemetry of a target satellite to obtain on-satellite time of the target satellite and corresponding ground time; Step 2: obtaining a satellite-ground time difference data set of the target satellite based on the on-satellite time and the corresponding ground time; Step 3: processing the satellite-ground time difference of the target satellite to generate a centralized time correction instruction, screening out abnormal values in the satellite-ground time difference data set of the target satellite, processing normal values in the satellite-ground time difference data set of the target satellite to generate a uniform time correction instruction; Step 4: based on the centralized time correction instruction or the uniform time correction instruction, performing uplink injection on the target satellite to complete satellite-ground time difference correction.

2. The method of claim 1, wherein, In the step 3, the satellite-ground time difference of the target satellite is processed, specifically as follows: A reference satellite is selected to obtain an average satellite-ground time difference of the reference satellite, and a time difference between the satellite-ground time difference of the target satellite and the average satellite-ground time difference of the reference satellite is taken as a processing result to generate the centralized time correction instruction.

3. The method of claim 1, wherein the time difference is a satellite-ground time difference. In the step 3, the abnormal values in the satellite-ground time difference data set of the target satellite are screened out, specifically as follows: Step 31: randomly selecting two groups of on-satellite time and ground time point pairs at different times in the satellite-ground time difference data set of the target satellite without repetition to construct a straight line equation, and differentiating normal values and abnormal values in other data in the satellite-ground time difference data set of the target satellite according to distances between straight lines formed by the other data and the straight line equation, and counting the number of normal values; Step 32: presetting an iteration number, iteratively executing the step 31, and selecting a case with the largest number of normal values to screen out abnormal values at this time.

4. The method of claim 3, wherein the time difference is a satellite-ground time difference. In the step 31, the other data in the satellite-ground time difference data set of the target satellite are differentiated into normal values and abnormal values according to distances between straight lines formed by the other data and the straight line equation, specifically as follows: A median of the satellite-ground time difference data set of the target satellite is obtained, differences between each data in the satellite-ground time difference data set of the target satellite and the median are calculated to obtain a set S', a median of the set S' is taken as a threshold, and whether distances between straight lines formed by the other data in the satellite-ground time difference data set of the target satellite and the straight line equation are greater than the threshold is judged respectively, if yes, the data is an abnormal value, and if no, the data is a normal value.

5. The method of claim 1, wherein, In the step 3, the normal values in the satellite-ground time difference data set of the target satellite are processed to generate the uniform time correction instruction, specifically as follows: The normal values are subjected to least square linear fitting to obtain a fitted straight line equation, and the fitted straight line equation is taken as a processing result to generate the uniform time correction instruction.

6. A correction system for satellite-ground time difference, the system is constructed based on the method of claim 1, characterized in that, The method comprises the following modules: Module 1: obtaining and analyzing satellite telemetry of a target satellite to obtain on-satellite time of the target satellite and corresponding ground time; Module 2: obtaining a satellite-ground time difference data set of the target satellite based on the on-satellite time and the corresponding ground time; Module 3: processing the satellite-ground time difference of the target satellite to generate a centralized time correction instruction, screening out abnormal values in the satellite-ground time difference data set of the target satellite, processing normal values in the satellite-ground time difference data set of the target satellite to generate a uniform time correction instruction; Module 4: based on the centralized time correction instruction or the uniform time correction instruction, performing uplink injection on the target satellite to complete satellite-ground time difference correction.

7. A computer program product comprising computer programs or instructions, characterized in that, The computer program or instructions are executed by the processor to implement the correction method for the satellite-ground time difference according to any one of claims 1-5.

8. An electronic device, comprising: The computer readable storage medium stores a computer program, and the computer program is executed by the processor to implement the correction method for the satellite-ground time difference according to any one of claims 1-5. The computer readable storage medium stores a computer program, and the computer program is executed by the processor to implement the correction method for the satellite-ground time difference according to any one of claims 1-5. The computer readable storage medium stores a computer program, and the computer program is executed by the processor to implement the correction method for the satellite-ground time difference according to any one of claims 1-5.

9. A computer-readable storage medium, characterized in that, The computer readable storage medium stores a computer program, and the computer program is executed by the processor to implement the correction method for the satellite-ground time difference according to any one of claims 1-5.

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