Satellite system time synchronization method and device

Abstract

This application discloses a satellite system time synchronization method and apparatus, applicable to the field of constellation management technology. The satellite system time synchronization method includes: performing joint clock error estimation based on the clock error calculation results of each satellite-to-ground observation pair and each inter-satellite observation pair, to obtain a joint clock error estimation result. Each satellite-to-ground observation pair is an observation combination consisting of a ground station and a first satellite, and each inter-satellite observation pair is an observation combination consisting of a second satellite and either a first satellite or another second satellite; transmitting the joint clock error estimation result to enable time synchronization of the satellite system. The satellite system time synchronization method and apparatus provided in this application, by integrating the time synchronization data of satellite-to-ground observation pairs and inter-satellite observation pairs and performing joint clock error estimation, solves the problem of accumulated errors that may be caused by local synchronization, achieving the effect of ensuring the consistency of the satellite system's time reference.

Description

Technical Field

[0001] This application relates to the field of constellation management technology, specifically to a satellite system time synchronization method and apparatus. Background Technology

[0002] Currently, low-Earth orbit (LEO) satellite systems, as an important supplement to terrestrial mobile communication systems, have become a core component of the integrated air-space-ground-sea information network. LEO satellites operate at lower orbits, have shorter transmission latency, and offer flexible networking capabilities, effectively addressing the problem of insufficient coverage in terrestrial communication networks. However, the normal operation of LEO satellite systems depends on network-wide time synchronization. Especially in complex communication environments, GPS or BeiDou signals may be unavailable, preventing the system from achieving time synchronization. Network-wide time synchronization plays a crucial role in ensuring communication coordination, information transmission accuracy, and system reliability within the LEO satellite system, directly impacting the service capabilities and operational efficiency of the integrated air-space-ground-sea information network. Therefore, ensuring time synchronization of LEO satellite systems in the absence of external timing signals has become a critical issue that urgently needs to be addressed. Summary of the Invention

[0003] To address at least some of the aforementioned technical problems, embodiments of this application provide a satellite system time synchronization method and apparatus.

[0004] On one hand, embodiments of this application provide a satellite system time synchronization method, including: performing joint clock error estimation based on the clock error calculation results of each satellite-ground observation pair and each inter-satellite observation pair, to obtain a joint clock error estimation result, wherein each satellite-ground observation pair is an observation combination consisting of a ground station and a first satellite, and each inter-satellite observation pair is an observation combination consisting of a second satellite and a first satellite or another second satellite; and transmitting the joint clock error estimation result to enable the satellite system to perform time synchronization.

[0005] In some embodiments, the first satellite is configured with a direct communication link to at least one ground station of the satellite system, while the second satellite is not configured with a direct communication link to the ground station of the satellite system.

[0006] In some embodiments, a direct communication link is configured between the first satellite constituting a satellite-to-ground observation pair and the ground station; a direct communication link is configured between the second satellite constituting an inter-satellite observation pair and the first satellite; and a direct communication link is configured between the two second satellites constituting an inter-satellite observation pair.

[0007] In some embodiments, the step of performing joint clock error estimation based on the clock error calculation results of each satellite-to-ground observation pair and each inter-satellite observation pair to obtain a joint clock error estimation result includes: selecting a clock from the ground station of the satellite system, the first satellite, and the second satellite as a reference clock; and performing joint clock error estimation relative to the reference clock based on the clock error calculation results of each satellite-to-ground observation pair and each inter-satellite observation pair to obtain a joint clock error estimation result.

[0008] In some embodiments, the step of performing joint clock error estimation relative to the reference clock based on the clock error calculation results of each satellite-to-ground observation pair and each inter-satellite observation pair of the satellite system to obtain the joint clock error estimation result includes: performing joint clock error estimation relative to the reference clock based on the clock error observation values ​​and clock error standard deviations of each satellite-to-ground observation pair and each inter-satellite observation pair to obtain the joint clock error estimation result.

[0009] In some embodiments, the step of performing joint clock error estimation relative to the reference clock based on the clock error observations and standard deviations of each satellite-to-ground observation pair and the clock error observations and standard deviations of each inter-satellite observation pair to obtain a joint clock error estimation result includes: constructing a clock error observation vector based on the clock error observations of each satellite-to-ground observation pair and the clock error observations of each inter-satellite observation pair; constructing a weight matrix based on the clock error standard deviations of each satellite-to-ground observation pair and the clock error standard deviations of each inter-satellite observation pair; constructing a design matrix based on the link establishment relationship between the first satellite and the ground station in each satellite-to-ground observation pair and the link establishment relationship between the second satellite and the first satellite or another second satellite in each inter-satellite observation pair; and performing joint clock error estimation relative to the reference clock based on the clock error observation vector, the weight matrix, and the design matrix to obtain a joint clock error estimation result, wherein the joint clock error estimation result includes clock error estimates of at least one of the following relative to the reference clock: the first satellite, the second satellite, and the ground station.

[0010] In some embodiments, sending the joint clock bias estimation result to enable time synchronization of the satellite system includes: sending the clock bias estimation value to the corresponding satellite, so that the satellite adjusts its clock based on the received clock bias estimation value, thereby enabling inter-satellite and / or satellite-to-ground time synchronization of the satellite system.

[0011] In some embodiments, sending the joint clock bias estimation result to enable time synchronization of the satellite system includes: sending the clock bias estimation value to the corresponding ground station, so that the ground station adjusts its clock based on the received clock bias estimation value, thereby enabling inter-satellite and / or satellite-to-ground time synchronization of the satellite system.

[0012] In some embodiments, before performing joint clock error estimation based on the clock error calculation results of each satellite-to-ground observation pair and each inter-satellite observation pair to obtain the joint clock error estimation result, the method further includes: monitoring the clock values ​​of satellites and / or ground stations in the satellite system; if the deviation between one of the clock values ​​and a reference value is greater than a deviation threshold, then obtaining the clock error calculation results of each satellite-to-ground observation pair and each inter-satellite observation pair.

[0013] In some embodiments, obtaining the clock bias calculation results of each satellite-to-ground observation pair and each inter-satellite observation pair of the satellite system includes: obtaining real-time two-way ranging data of each satellite-to-ground observation pair and real-time two-way ranging data of each inter-satellite observation pair; performing clock bias calculation on the satellite-to-ground observation pair based on the real-time two-way ranging data of the satellite-to-ground observation pair to obtain the clock bias calculation result of the satellite-to-ground observation pair; and performing clock bias calculation on the inter-satellite observation pair based on the real-time two-way ranging data of the inter-satellite observation pair to obtain the clock bias calculation result of the inter-satellite observation pair.

[0014] On the other hand, embodiments of this application provide a satellite system time synchronization device, including: a calculation module, used to perform joint clock error estimation based on the clock error calculation results of each satellite-ground observation pair and each inter-satellite observation pair, to obtain a joint clock error estimation result, wherein each satellite-ground observation pair is an observation combination consisting of a ground station and a first satellite, and each inter-satellite observation pair is an observation combination consisting of a second satellite and a first satellite or another second satellite; and a transmission module, used to transmit the joint clock error estimation result so that the satellite system can perform time synchronization.

[0015] This application also provides a computer device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the methods described in any of the above embodiments.

[0016] This application also provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the methods described in any of the above embodiments.

[0017] This application also provides a computer program product, which includes a computer program that, when executed by a processor, implements the methods described in any of the above embodiments.

[0018] The satellite system time synchronization method and apparatus provided in this application embodiment perform joint clock error estimation based on the clock error calculation results of each satellite-to-ground observation pair and each inter-satellite observation pair, obtaining a joint clock error estimation result. Each satellite-to-ground observation pair is an observation combination consisting of a ground station and a first satellite, and each inter-satellite observation pair is an observation combination consisting of a second satellite and either a first satellite or another second satellite. The joint clock error estimation result is transmitted to enable time synchronization of the satellite system. In this way, by integrating the time synchronization data of satellite-to-ground and inter-satellite observation pairs and performing joint clock error estimation, the cumulative error problem that may be caused by local synchronization is solved, achieving the effect of ensuring the consistency of the satellite system's time reference. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. In the drawings:

[0020] Figure 1 This is a schematic flowchart of a satellite system time synchronization method provided in an embodiment of this application.

[0021] Figure 2 This is a schematic diagram of the structure of a satellite system provided in one embodiment of this application.

[0022] Figure 3 This is a partial flowchart illustrating a satellite system time synchronization method provided in an embodiment of this application.

[0023] Figure 4 This is a partial flowchart illustrating a satellite system time synchronization method provided in an embodiment of this application.

[0024] Figure 5 This is a partial flowchart illustrating a satellite system time synchronization method provided in an embodiment of this application.

[0025] Figure 6 This is a partial flowchart illustrating a satellite system time synchronization method provided in an embodiment of this application.

[0026] Figure 7 This is a schematic diagram of the structure of a satellite system time synchronization device according to an embodiment of this application.

[0027] Figure 8 This is a schematic diagram of the physical structure of an electronic device provided in an embodiment of this application. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the embodiments of this application will be further described in detail below with reference to the accompanying drawings. Here, the illustrative embodiments and their descriptions are used to explain this application, but are not intended to limit this application. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of this application can be arbitrarily arranged.

[0029] The terms “first,” “second,” etc., used in this document are not intended to specifically refer to order or sequence, nor are they used to limit this application; they are merely used to distinguish elements or operations described using the same technical terms.

[0030] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0031] The term "and / or" as used in this document includes any or all of the items mentioned.

[0032] The satellite system time synchronization method provided in this application includes, but is not limited to, a computer.

[0033] To better understand this application, the research background of this application will be explained in detail below.

[0034] Currently, there is a method for achieving full-network time synchronization of low-Earth orbit (LEO) satellite systems using a two-way time comparison algorithm. This solves the problem of self-organized time synchronization when external timing signals such as GPS or BeiDou are unavailable. This scheme designs time synchronization frames to transmit nanosecond-level time accuracy over satellite-to-ground and inter-satellite links, ensuring the synchronization accuracy of the LEO satellite system and supporting time synchronization between satellites even without ground communication. However, this method has the following problems: inter-satellite synchronization uses a hop-by-hop transmission method, which becomes less efficient as the satellite constellation grows, especially in large-scale constellation management, potentially limiting the system's time synchronization speed; the synchronization process requires multiple repetitions to ensure accuracy, increasing communication burden and processing complexity, thus affecting the overall system efficiency; and when satellites are not visible to the ground, time synchronization depends on the stability of the inter-satellite links, and problems with the satellite-to-ground links may affect the reliability of the system's time synchronization.

[0035] To solve the above technical problems, Figure 1 This is a schematic flowchart of a satellite system time synchronization method provided in an embodiment of this application, as shown below. Figure 1 As shown in the embodiments of this application, the satellite system time synchronization method includes:

[0036] S1. Based on the clock error calculation results of each satellite-ground observation pair and each inter-satellite observation pair, a joint clock error estimation is performed to obtain a joint clock error estimation result. Each satellite-ground observation pair is an observation combination consisting of a ground station and a first satellite, and each inter-satellite observation pair is an observation combination consisting of a second satellite and a first satellite or another second satellite.

[0037] In step S1, the satellite system includes a ground station and a satellite, which work together to achieve a specific function; for example, such as Figure 2 The satellite system shown includes ground stations R1 and R2 and satellite S. 1 、S 2 、S 3 、S 4 Among them, a satellite-to-ground observation pair refers to an observation combination consisting of a ground station and a satellite, while an inter-satellite observation pair refers to an observation combination consisting of satellites. The satellites in the satellite system can be classified, with satellites belonging to the first category being called first satellites and satellites belonging to the second category being called second satellites.

[0038] The first satellite is paired with a ground station to form a satellite-to-ground observation pair. The second satellite is paired with the first satellite or another second satellite to form an inter-satellite observation pair. The clock bias calculation result for each satellite-to-ground observation pair can be obtained based on the two-way measurement data between the first satellite and the ground station constituting the pair. Similarly, the clock bias calculation result for each inter-satellite observation pair can be obtained based on the two-way measurement data between the two satellites constituting the pair.

[0039] After obtaining the clock bias calculation results for each satellite-to-ground observation pair and each inter-satellite observation pair, a joint clock bias estimation is performed by combining the clock bias calculation results of the satellite-to-ground observation pairs and the inter-satellite observation pairs to obtain a joint clock bias estimation result. The joint clock bias estimation result may include the clock bias estimates of each ground station and / or satellite in the satellite system.

[0040] S2. Send the joint clock error estimation result so that the satellite system can synchronize its time.

[0041] In step S2, the joint clock bias estimation result can be sent to various ground stations and / or satellites in the satellite system. For example, when the joint clock bias estimation result includes clock bias estimates of various ground stations and / or satellites in the satellite system, the clock bias estimates of various ground stations and / or satellites are sent to the corresponding ground stations and / or satellites respectively, so that the corresponding ground stations and / or satellites adjust their own clocks based on the received clock bias estimates. Thus, the time synchronization between satellites and / or between satellites and ground is achieved.

[0042] The satellite system time synchronization method provided in this application embodiment performs joint clock error estimation based on the clock error calculation results of each satellite-to-ground observation pair and each inter-satellite observation pair, obtaining a joint clock error estimation result. Each satellite-to-ground observation pair is an observation combination consisting of a ground station and a first satellite, and each inter-satellite observation pair is an observation combination consisting of a second satellite and either a first satellite or another second satellite. The joint clock error estimation result is transmitted to enable time synchronization of the satellite system. Thus, by integrating the time synchronization data of satellite-to-ground and inter-satellite observation pairs and performing joint clock error estimation, the cumulative error problem that may be caused by local synchronization is solved, achieving the effect of ensuring the consistency of the satellite system's time reference.

[0043] In some embodiments, a direct communication link is configured between the first satellite and at least one ground station of the satellite system, while no direct communication link is configured between the second satellite and the ground station of the satellite system. For example, such as Figure 2 As shown, satellite S 1 Direct communication links are configured between satellite S and ground stations R1 and R2 respectively. 2 A direct communication link is configured between it and ground station R2, therefore, Figure 2 In the satellite system shown, satellite S 1 、S 2 These are the first satellites, respectively. Also, for example... Figure 2 As shown, satellite S 3 、S 4 There are no direct communication links between satellite S and ground stations R1 and R2. 3 、S 4 These are the second satellites.

[0044] In some embodiments, a direct communication link is configured between the first satellite constituting a satellite-to-ground observation pair and the ground station; a direct communication link is configured between the second satellite constituting an inter-satellite observation pair and the first satellite; and a direct communication link is configured between the two second satellites constituting an inter-satellite observation pair. Specifically, in the satellite system, the first satellite with a direct communication link and the ground station can form a satellite-to-ground observation pair. For a second satellite without a direct communication link with the ground station, other satellites with direct communication links with that second satellite can form an inter-satellite observation pair. In this way, during time synchronization, compared to observation pairs without direct communication links, the accumulation of intermediate hop errors can be eliminated, and the dependence on intermediate nodes / networks can be reduced.

[0045] For example, such as Figure 2 As shown, satellite S 1 Together with ground station R1, they form a satellite-to-ground observation pair S 1 R1, Satellite S1 Together with ground station R2, they form a satellite-to-ground observation pair S 1 R2, Satellite S 2 Together with ground station R2, they form a satellite-to-ground observation pair S 2 R2; This yields three satellite-to-ground observation pairs S 1 R1, S 1 R2, S 2 R2; In addition, satellite S 3 With satellite S 4 Constitute an inter-satellite observation pair S 3 S 4 Satellite S 3 With satellite S 2 Constitute an inter-satellite observation pair S 3 S 2 This yields two inter-satellite observation pairs for S. 3 S 4 、S 3 S 2 .

[0046] like Figure 3 As shown, in some embodiments, step S1 above may specifically include:

[0047] S11. Select the clock of one of the ground station of the satellite system, the first satellite, and the second satellite as the reference clock;

[0048] In step S11, a clock from a satellite or a ground station in the satellite system can be selected as a reference clock, assuming that its clock difference is 0, or its value relative to GPS time is known.

[0049] S12. Based on the clock error calculation results of each satellite-to-ground observation pair and each inter-satellite observation pair, perform a joint clock error estimation relative to the reference clock to obtain the joint clock error estimation result.

[0050] In step S12, after a reference clock is selected, the clock bias of other satellites or ground stations in the satellite system will be estimated relative to this reference clock.

[0051] In some embodiments, step S12 may specifically include: performing a joint clock error estimation relative to the reference clock based on the clock error observation values ​​and clock error standard deviations of each satellite-to-ground observation pair and the clock error observation values ​​and clock error standard deviations of each inter-satellite observation pair, to obtain a joint clock error estimation result.

[0052] Specifically, each satellite-to-ground observation pair The clock error calculation results can include clock error observations and clock error standard deviations. Specifically, this can be done for each satellite-to-ground observation pair. Time synchronization was performed to obtain satellite data. and ground station Clock difference observations between At the same time, satellites were obtained and ground station Clock deviation and standard deviation between .For example, Figure 1 In the satellite system shown, the satellite-to-ground observation pairs can be calculated. Clock difference observations and clock bias and standard deviation The standard deviation of the clock error observations for each satellite-to-ground observation pair is calculated based on the clock error observations for each satellite-to-ground observation pair.

[0053] Similarly, each inter-satellite observation pair The clock error calculation results can include clock error observations and clock error standard deviations. Specifically, time synchronization can be performed on all inter-satellite observation pairs to obtain satellite... and satellite Clock difference observations between At the same time, satellites were obtained and satellite Clock deviation and standard deviation between .For example, Figure 2 In the satellite system shown, inter-satellite observation pairs can be calculated. Clock difference observations and clock bias and standard deviation The standard deviation of the clock error observations for each inter-satellite observation pair is calculated based on the clock error observations for each inter-satellite observation pair.

[0054] like Figure 4 As shown, in some embodiments, the step of performing joint clock error estimation relative to the reference clock based on the clock error observations and standard deviations of each satellite-to-ground observation pair and the clock error observations and standard deviations of each inter-satellite observation pair to obtain the joint clock error estimation result may specifically include:

[0055] S121. Construct a clock difference observation vector based on the clock difference observation values ​​of each satellite-to-ground observation pair and each inter-satellite observation pair in the satellite system.

[0056] In step S121, the clock difference observation vector Includes clock error observations for each satellite-to-ground observation pair and clock error observations for each inter-satellite observation pair:

[0057]

[0058] in:

[0059] Indicates satellite and ground station Clock difference observations between;

[0060] Indicates satellite and satellite The clock difference observations between them.

[0061] For example, for Figure 1 The satellite system shown in the figure has a clock bias observation vector. It can be represented as:

[0062] .

[0063] S122. Construct a weight matrix based on the standard deviation of clock error for each of the aforementioned star-ground observation pairs and the standard deviation of clock error for each of the aforementioned inter-satellite observation pairs;

[0064] In step S122, the weight matrix This can be a diagonal matrix, with the diagonal elements representing the weights corresponding to each clock error observation. For each satellite-to-ground observation pair, the weights corresponding to the clock error observations of that pair can be determined based on the standard deviation of the clock errors of that pair. Similarly, for each inter-satellite observation pair, the weights corresponding to the clock error observations of that pair can be determined based on the standard deviation of the clock errors of that pair. Therefore, the weight matrix... It can be represented as:

[0065]

[0066] in:

[0067] It is a star-ground observation pair The weights corresponding to the clock error observations;

[0068] Interstellar observation pairs The weights corresponding to the clock difference observations.

[0069] For example, regarding Figure 1 The satellite system shown has a weight matrix. It can be represented as:

[0070] .

[0071] S123. Construct a design matrix based on the link establishment relationship between the first satellite and the ground station in each of the said star-ground observation pairs and the link establishment relationship between the second satellite and the first satellite or another second satellite in each of the said inter-satellite observation pairs;

[0072] In step S123, design the matrix. To represent the linking relationship between a star and its location, or between stars, it can be represented as:

[0073]

[0074] Each column corresponds to a satellite or ground station, and each row represents the link relationship between satellites and ground stations, and between satellites. Satellite-to-ground observations correspond to "+1 (satellite) / -1 (ground station)", and inter-satellite observations correspond to "+1 (sender) / -1 (receiver)". If the observation involves satellite-to-ground synchronization, the relevant ground station (reference clock) does not participate in the estimation; if the observation involves inter-satellite synchronization, the design matrix will have columns related to the two satellites.

[0075] S124. Based on the clock error observation vector, weight matrix and design matrix, perform joint clock error estimation relative to the reference clock to obtain joint clock error estimation results, wherein the joint clock error estimation results include clock error estimates of at least one of the following relative to the reference clock: first satellite, second satellite, ground station.

[0076] In step S124, the formula for least squares can be used:

[0077]

[0078] The joint clock error estimation results were calculated. Joint clock bias estimation results This includes clock bias estimates for each satellite and each ground station, which are relative differences from a reference clock. For example, if ground stations are not involved in the estimation, the vector... The specific representation can be as follows:

[0079]

[0080] in, Indicates satellite Relative to reference clock (satellite) The estimated value of clock bias.

[0081] like : indicates satellite The clock is ahead of the reference clock, specifically by a certain amount of time. Second;

[0082] like : indicates satellite The clock runs slower than the reference clock, specifically by a certain amount of time. Second;

[0083] like : indicates satellite The clock is perfectly synchronized with the reference clock.

[0084] In some embodiments, step S2 above may specifically include: sending the clock bias estimate to the corresponding satellite, so that the satellite adjusts its clock based on the received clock bias estimate, thereby synchronizing the inter-satellite and / or satellite-to-ground time of the satellite system; and / or sending the clock bias estimate to the corresponding ground station, so that the ground station adjusts its clock based on the received clock bias estimate, thereby synchronizing the inter-satellite and / or satellite-to-ground time of the satellite system.

[0085] Specifically, to achieve high-precision time synchronization of the satellite system, the clocks of each satellite and / or ground station need to be adjusted based on the clock bias estimation results. Taking satellites as an example, the specific process can be as follows:

[0086] From the joint clock error estimation results Read the clock difference of each satellite relative to the reference clock. Then, each clock difference The received clock bias is transmitted to the corresponding satellites, which then adjust their local clocks based on the received clock bias. The clock bias adjustment principle is as follows:

[0087] if This indicates that the satellite The clock is running faster than the reference clock, so the clock needs to be set back. Second;

[0088] if This indicates that the satellite The clock runs slow compared to the reference clock, so it needs to be moved forward. Second;

[0089] if This indicates that the satellite The clock is synchronized with the reference clock and requires no adjustment.

[0090] After adjustment, each satellite clock will be synchronized with the reference clock. At this time, the clock synchronization status of the satellites in the entire satellite system is as follows:

[0091]

[0092] This means that the clock difference error between all satellite clocks in the satellite system is close to zero, achieving a minimum.

[0093] The process of adjusting the clock for the ground station is similar to that of adjusting the clock for the satellite, and will not be repeated here.

[0094] like Figure 5 As shown, in some embodiments, prior to step S1 above, the method may further include:

[0095] S01. Monitor the clock values ​​of satellites and / or ground stations in the satellite system;

[0096] In step S01, a monitoring strategy for the satellite system can be set to monitor the clock values ​​of satellites and / or ground stations in the satellite system in real time.

[0097] S02. If the deviation between the clock value and the reference value is greater than the deviation threshold, then obtain the clock difference calculation results of each satellite-to-ground observation pair and the clock difference calculation results of each inter-satellite observation pair of the satellite system.

[0098] In step S02, when new monitoring data reveals a significant change in the time deviation of one or more satellite / ground stations, the time synchronization process can be initiated rapidly. Specifically, a time deviation threshold can be defined. ,when When this occurs, a resynchronization process is triggered, in which... This represents the clock reference value (or the correct clock value). This indicates the detected clock value.

[0099] like Figure 6 As shown, in some embodiments, obtaining the clock error calculation results of each satellite-to-ground observation pair and each inter-satellite observation pair of the satellite system includes:

[0100] S021. Obtain real-time two-way ranging data of each satellite-to-ground observation pair and each inter-satellite observation pair of the satellite system.

[0101] In step S021, two-way ranging is performed between the satellite and the ground station of each satellite-to-ground observation pair to obtain two-way ranging data. Similarly, two-way ranging is performed between the two satellites of each inter-satellite observation pair to obtain two-way ranging data.

[0102] S022. Based on the real-time two-way ranging data of the star-ground observation pair, perform clock error calculation on the star-ground observation pair to obtain the clock error calculation result of the star-ground observation pair;

[0103] In step S022, for each satellite-ground observation pair, based on the two-way ranging data of the satellite-ground observation pair, clock error calculation is performed between the satellite and the ground station constituting the satellite-ground observation pair to obtain the clock error calculation result of the satellite-ground observation pair.

[0104] S023. Based on the real-time two-way ranging data of the inter-satellite observation pair, clock error calculation is performed on the inter-satellite observation pair to obtain the clock error calculation result of the inter-satellite observation pair.

[0105] In step S023, for each inter-satellite observation pair, based on the two-way ranging data of the inter-satellite observation pair, clock error calculation is performed between the two satellites constituting the inter-satellite observation pair to obtain the clock error calculation result of the inter-satellite observation pair.

[0106] It should be noted that this embodiment does not limit the execution order between the above steps S022 and S033. Step S022 can be executed before step S033, after step S033, or simultaneously with step S033.

[0107] To better understand this application, the following will be used as... Figure 2 Taking the satellite system shown as an example, the satellite system time synchronization method provided in this application embodiment will be described in detail.

[0108] Step 1: Satellite-to-ground time synchronization.

[0109] Sub-step 1.1: Obtain all visible ground station-satellite observation pairs (space-to-ground observation pairs) based on the ground station and satellite spatial coordinates. ,in, Indicates the number satellite, Indicates the number Ground stations. For example. Figure 2 In the satellite system shown, there are visible ground station-satellite observation pairs. .

[0110] Sub-step 1.2: For each visible ground station-satellite observation pair Perform time synchronization and obtain the synchronization result. , Indicates satellite and ground station The clock error observations between the values ​​were obtained, and the standard deviation of the clock error was calculated. Indicates satellite and ground station The standard deviation of the clock difference observations between them. For example, Figure 2 In the satellite system shown, the visible ground station-satellite observation pair can be solved. Clock difference observations and clock bias and standard deviation .

[0111] Step 2: Inter-satellite time synchronization.

[0112] Sub-step 2.1: Search for satellites in the constellation that do not have a direct communication link with the ground station (also known as out-of-line-of-sight satellites). For example in Figure 2 In the middle, satellite and satellite There is no direct communication link with the ground station, therefore the search results for external satellites are considered as .

[0113] Sub-step 2.2: Search for all satellite pairs (inter-satellite observation pairs) that can establish direct line communication with out-of-line-of-sight satellites. For example, for Figure 2 The satellite system in the middle, the satellite-to-satellite search results are .

[0114] Sub-step 2.3: Perform time synchronization on all satellite-to-satellite pairs to obtain the synchronization clock difference results. , indicating external satellites and satellite The clock error observations between the values ​​were obtained, and the standard deviation of the clock error was calculated. , indicating satellite and satellite The standard deviation of the clock difference observations between the two values. Figure 2 The satellite system shown can be used to solve for satellite-satellite observation pairs. Clock difference observations and clock bias and standard deviation .

[0115] Step 3: Perform joint observation processing based on the time synchronization results.

[0116] In step 3, the goal is to perform joint time synchronization processing on the entire constellation using the weighted least squares method based on the known time synchronization results between the satellite and the ground and between satellites, thereby eliminating deviations caused by measurement errors and achieving high-precision time synchronization for the entire constellation.

[0117] Sub-step 3.1: Basic formula of weighted least squares method

[0118] When performing weighted least squares estimation, a specific satellite or ground station in the satellite network is selected as a reference clock, assuming its clock bias is 0 or its value relative to GPS time is known. The clock biases of all other satellites and ground stations are estimated relative to this reference clock. Therefore, the reference clock bias is fixed at a known value, and the other clock biases are estimated using the least squares method.

[0119] The objective function of the weighted least squares method is:

[0120]

[0121] in: This represents the clock error observation value for each observation pair (space-to-ground or inter-space); This represents the estimated clock error relative to a reference clock (estimated clock error value). The weight of the observation is defined as ,in This represents the standard deviation of the corresponding clock error observations.

[0122] Sub-step 3.2: Setting the reference clock

[0123] Choose a satellite or ground station clock as the reference clock, assuming its clock bias is 0, i.e. Alternatively, its clock bias relative to a known value of GPS time. In this case, the reference clock is not included in the estimation, and the estimated clock biases of the remaining clocks are the differences relative to the reference clock.

[0124] For example, assuming ground station R1 is selected as the reference clock, then Clock bias estimates for all other ground stations and satellites ( ), It is an estimated value relative to the ground station R1.

[0125] Sub-step 3.3: Formula for calculating clock error estimate

[0126] By selecting a reference clock, the design matrix (also known as the design matrix) for joint observation processing can be simplified. The clock error estimate is derived in matrix form using the following weighted least squares method:

[0127]

[0128] in: This represents the clock difference vector relative to the reference clock that needs to be estimated; The design matrix is ​​constructed based on the link establishment relationship between the first satellite and the ground station in each of the said satellite-ground observation pairs, and the link establishment relationship between the second satellite and the first satellite or another second satellite in each of the said inter-satellite observation pairs. It is a weight matrix, with diagonal elements as follows: , , This represents the standard deviation of the corresponding clock error observations; It is a vector of clock bias observations, which includes clock bias observations obtained from satellite-to-ground synchronization and inter-satellite synchronization.

[0129] Sub-step 3.4: Setting clock bias weights

[0130] The formula for setting the clock error weight should be expressed as:

[0131]

[0132] Special, targeting Figure 2 The satellite system in question considers the following satellite-to-ground and inter-satellite observation pairs:

[0133] Space-to-ground synchronous observation pairs:

[0134] Clock difference observations Clock bias and standard deviation ;

[0135] Clock difference observations Clock bias and standard deviation ;

[0136] Clock difference observations Clock bias and standard deviation ;

[0137] Inter-satellite synchronous observation pairs:

[0138] Clock difference observations Clock bias and standard deviation ;

[0139] Clock difference observations Clock bias and standard deviation .

[0140] The weights for these clock error observations are as follows:

[0141]

[0142] Sub-step 3.5: Joint estimation process of clock bias

[0143] 1. Construct a vector of clock error observations. :

[0144] Clock difference observation vector Includes clock bias observations obtained from all satellite-to-ground and inter-satellite synchronizations:

[0145]

[0146] in: Indicates satellite and ground station Observations of the clock difference between the satellite and the ground;

[0147] Indicates satellite and satellite Inter-satellite clock bias observations.

[0148] For example, regarding Figure 2 Satellite systems in the middle, clock bias observation vector Represented as:

[0149] .

[0150] 2. Construct the weight matrix :

[0151] weight matrix This is a diagonal matrix, where the diagonal elements represent the weights of each clock error observation.

[0152]

[0153] in:

[0154] It is the weight of the satellite-to-ground synchronization clock difference observation;

[0155] It is the weight of the inter-satellite synchronization clock difference observation.

[0156] For example, regarding Figure 2 Satellite systems, weight matrix Represented as:

[0157]

[0158] 3. Construct a design matrix :

[0159] Design Matrix To represent the relationship between clock bias observations and actual clock biases of each satellite and ground station, a matrix is ​​designed. It can be represented as:

[0160]

[0161] Each column corresponds to a satellite or ground station, and each row represents the link relationship between satellites and ground stations, and between satellites. Satellite-to-ground observations correspond to "+1 (satellite) / -1 (ground station)", and inter-satellite observations correspond to "+1 (sender) / -1 (receiver)". If the observation involves satellite-to-ground synchronization, the relevant ground station (reference clock) does not participate in the estimation; if the observation involves inter-satellite synchronization, the design matrix will have columns related to the two satellites.

[0162] For example, regarding Figure 2 In the satellite system, since the clock of ground station R1 is used as the reference clock, the clock difference of ground station R1 is known ( Therefore, the column related to R1 can be omitted in the design matrix, and it can be represented as:

[0163]

[0164] Since the clock of ground station R1 is used as the reference clock, the above matrix H is the matrix obtained after omitting the columns related to R1. The original matrix is:

[0165]

[0166] Each column, from left to right, represents S. 1、S 2 、S 3 、S 4 R1, R2, the first row indicates that the ground station-satellite observation pair in step 1 has S 1 R1(+1(S) 1 ) / -1(R1)), the second line indicates that the ground station-satellite observation pair in step 1 has S 1 R2(+1(S) 1 ) / -1(R2)), the third line indicates that the ground station-satellite observation pair in step 1 has S 2 R2(+1(S) 2 ) / -1(R2)), the fourth line indicates that the satellite-satellite observation pair in step 2 has S 2 S 3 (+1(S)) 2 ) / -1(S 3 The fifth line indicates that the satellite-satellite observation pair in step 2 has S. 3 S 4 (+1(S)) 3 ) / -1(S 4 )).

[0167] 4. Joint clock bias estimation:

[0168] Using the formula of least squares:

[0169]

[0170] The clock bias estimates for all satellites were calculated. These clock differences are relative to a reference clock ( The relative differences between ).

[0171] Step 4: Final output of joint clock bias estimation results and time synchronization adjustment

[0172] Sub-step 4.1: Representation of the joint clock error estimation results

[0173] Due to reference clocks (e.g., ground stations) The clock error of the non-reference clock is 0, and the joint clock error estimation results will show the clock error of each non-reference clock relative to the reference clock.

[0174] The final joint clock error estimation results are as follows:

[0175]

[0176] in, Indicates ground station Relative to the reference clock ( The estimated value of clock bias, Indicates satellite Relative to the reference clock ( The estimated value of clock bias.

[0177] Sub-step 4.2: Physical meaning of clock error estimation results

[0178] Taking the estimated clock bias of a satellite as an example:

[0179] : indicates satellite The clock is ahead of the reference clock, specifically by a certain amount of time. Second;

[0180] : indicates satellite The clock runs slower than the reference clock, specifically by a certain amount of time. Second;

[0181] : indicates satellite The clock is perfectly synchronized with the reference clock;

[0182] The same applies to the clock error estimates for ground stations.

[0183] These clock bias estimates indicate the difference between the clock of each satellite or ground station and the reference clock.

[0184] Sub-step 4.3: Use clock difference estimation results for time synchronization adjustment

[0185] To achieve high-precision time synchronization across the entire constellation, the clocks of each satellite need to be corrected based on the clock bias estimation results. The adjustment steps are as follows:

[0186] 1. Clock error correction principle

[0187] if This indicates that the satellite The clock is running faster than the reference clock, so the clock needs to be set back. Second;

[0188] if This indicates that the satellite The clock runs slow compared to the reference clock, so it needs to be moved forward. Second;

[0189] if This indicates that the satellite The clock is synchronized with the reference clock and requires no adjustment.

[0190] 2. Adjustment process

[0191] Reading clock bias: from the clock bias vector Read the clock difference of each satellite or ground station relative to the reference clock. .

[0192] Calculate the adjustment amount: based on the clock bias results. Calculate the amount of clock correction that needs to be adjusted:

[0193] for In this case, the clock needs to be turned back;

[0194] for In this case, the clock needs to be moved forward.

[0195] Perform clock adjustment: for each satellite Adjust its local clock by either turning it back or turning it forward.

[0196] 3. Synchronization status after adjustment

[0197] After adjustment, all satellite and ground station clocks will be synchronized with the reference clock ( Synchronization: At this point, the clocks of the entire constellation are synchronized as follows:

[0198]

[0199] This means that the clock difference error between all clocks in the network is close to zero, thus minimizing the error.

[0200] Step 5: Feedback mechanism and dynamic adjustment.

[0201] Sub-step 5.1: After time synchronization is complete, dynamically adjust the constellation's time synchronization strategy based on feedback from real-time observation data. For example, if new observation data reveals significant changes in the time deviation of certain satellites, the synchronization process can be quickly restarted to ensure the continued accuracy of time synchronization. A time deviation threshold can be defined. ,when At that time, a resynchronization process is triggered.

[0202] Through the above process, the time synchronization of the entire constellation can be completed. Specifically, this manifests as follows:

[0203] Space-to-ground synchronization: Time synchronization between a ground station and a visible satellite;

[0204] Inter-satellite synchronization: Out-of-line-of-sight satellites synchronize with other satellites via inter-satellite links;

[0205] Joint synchronization: Based on the processing results of weighted least squares method, all satellite clocks are adjusted relative to the reference clock to ultimately achieve high-precision time synchronization of the entire constellation.

[0206] After adjustment, the time synchronization error of the entire constellation was minimized, and the clock errors between satellites or ground stations achieved optimal synchronization within the measurement error range.

[0207] As can be seen, the satellite system time synchronization method provided in this application combines satellite-to-ground and inter-satellite observations for joint time synchronization, solving the problem of high-precision time synchronization when satellites cannot have direct visual contact with ground stations. Utilizing inter-satellite communication links and joint estimation algorithms, high-precision time synchronization across the entire constellation is achieved, making it particularly suitable for the management and control of low-Earth orbit satellite constellations. By constructing a joint observation equation set for joint clock bias estimation, the problem of integrating satellite-to-ground and inter-satellite observation data is solved, achieving full utilization of all available observation information. By employing a weighted processing mechanism based on observation accuracy, the problem of differences in the quality of different observation data is solved, achieving the effect of optimizing overall synchronization accuracy. By using iterative solutions with weighted least squares, the problem of solving large-scale time synchronization problems is solved, achieving the effect of efficiently and accurately estimating the clock deviations of all satellites. By employing a dynamic adjustment mechanism, the problem of reduced synchronization accuracy caused by satellite clock drift is solved, achieving the effect of maintaining long-term stable high-precision time synchronization. By employing a global time synchronization correction method, the problem of accumulated errors that may be caused by local synchronization is solved, achieving the effect of ensuring the consistency of the time reference of the entire constellation system.

[0208] Figure 7 This is a schematic diagram of the structure of a satellite system time synchronization device according to an embodiment of this application, as shown below. Figure 7 As shown in the embodiment of this application, a satellite system time synchronization device includes:

[0209] The calculation module 21 is used to perform joint clock error estimation based on the clock error calculation results of each satellite-ground observation pair and each inter-satellite observation pair, and obtain the joint clock error estimation result. Each satellite-ground observation pair is an observation combination consisting of a ground station and a first satellite, and each inter-satellite observation pair is an observation combination consisting of a second satellite and a first satellite or another second satellite.

[0210] The transmitting module 22 is used to transmit the joint clock error estimation result so that the satellite system can synchronize its time.

[0211] The satellite system time synchronization device provided in this application performs joint clock error estimation based on the clock error calculation results of each satellite-to-ground observation pair and each inter-satellite observation pair, obtaining a joint clock error estimation result. Each satellite-to-ground observation pair is an observation combination consisting of a ground station and a first satellite, and each inter-satellite observation pair is an observation combination consisting of a second satellite and either a first satellite or another second satellite. The joint clock error estimation result is transmitted to enable time synchronization of the satellite system. Thus, by integrating the time synchronization data of satellite-to-ground and inter-satellite observation pairs and performing joint clock error estimation, the cumulative error problem that may be caused by local synchronization is solved, achieving the effect of ensuring the consistency of the satellite system's time reference.

[0212] The embodiments of the apparatus provided in this application can be used to execute the processing flow of the above-described satellite system time synchronization method embodiments. Its functions will not be repeated here, but can be referred to the detailed description of the above method embodiments.

[0213] Figure 8 This is a schematic diagram of the physical structure of an electronic device provided in an embodiment of this application, as shown below. Figure 8 As shown, the electronic device may include a processor 301, a communications interface 302, a memory 303, and a communication bus 304, wherein the processor 301, the communications interface 302, and the memory 303 communicate with each other via the communication bus 304. The processor 301 may call logical instructions in the memory 303 to execute the methods described in any of the above embodiments.

[0214] Furthermore, the logical instructions in the aforementioned memory 303 can be implemented as software functional units and, when sold or used as independent products, can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0215] This embodiment discloses a computer program product, which includes a computer program stored on a non-transitory computer-readable storage medium. The computer program includes program instructions, and when the program instructions are executed by a computer, the computer can perform the methods provided in the above-described method embodiments.

[0216] This embodiment provides a computer-readable storage medium storing a computer program that causes the computer to execute the methods provided in the above-described method embodiments.

[0217] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0218] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0219] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0220] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1A step that specifies a function in one or more boxes.

[0221] In the description of this specification, the references to terms such as "an embodiment," "a specific embodiment," "some embodiments," "for example," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0222] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of this application. It should be understood that the above descriptions are merely specific embodiments of this application and are not intended to limit the scope of protection of this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. A satellite system time synchronization method, characterized in that, include: Based on the clock error calculation results of each satellite-to-ground observation pair and each inter-satellite observation pair, a joint clock error estimation is performed to obtain a joint clock error estimation result. Each satellite-to-ground observation pair is an observation combination consisting of a ground station and a first satellite, and each inter-satellite observation pair is an observation combination consisting of a second satellite and a first satellite or another second satellite. The clock error calculation result of each satellite-to-ground observation pair is calculated based on the satellite-to-ground two-way ranging data of the first satellite and the ground station constituting the satellite-to-ground observation pair, and the clock error calculation result of each inter-satellite observation pair is calculated based on the inter-satellite two-way ranging data of the two satellites constituting the inter-satellite observation pair. The joint clock bias estimation results are sent to enable the satellite system to synchronize its time.

2. The method according to claim 1, characterized in that, The first satellite is configured with a direct communication link to at least one ground station of the satellite system, while the second satellite is not configured with a direct communication link to the ground station of the satellite system.

3. The method according to claim 2, characterized in that, A direct communication link is configured between the first satellite constituting a satellite-to-ground observation pair and the ground station. A direct communication link is configured between the second satellite and the first satellite that constitute an inter-satellite observation pair; A direct communication link is configured between the two second satellites that constitute an inter-satellite observation pair.

4. The method according to any one of claims 1 to 3, characterized in that, The joint clock error estimation is performed based on the clock error calculation results of each satellite-to-ground observation pair and each inter-satellite observation pair, resulting in a joint clock error estimation result, including: Choose one of the clocks from the ground station of the satellite system, the first satellite, and the second satellite as the reference clock; Based on the clock error calculation results of each satellite-to-ground observation pair and each inter-satellite observation pair, a joint clock error estimation relative to the reference clock is performed to obtain the joint clock error estimation result.

5. The method according to claim 4, characterized in that, The step involves performing a joint clock error estimation relative to the reference clock based on the clock error calculation results of each satellite-to-ground observation pair and each inter-satellite observation pair, to obtain the joint clock error estimation result, including: Based on the clock error observations and standard deviations of each satellite-to-ground observation pair and the clock error observations and standard deviations of each inter-satellite observation pair, a joint clock error estimation relative to the reference clock is performed to obtain the joint clock error estimation result.

6. The method according to claim 5, characterized in that, The step of performing a joint clock error estimation relative to the reference clock based on the clock error observations and standard deviations of each satellite-to-ground observation pair and the clock error observations and standard deviations of each inter-satellite observation pair, to obtain the joint clock error estimation result, includes: Based on the clock difference observation values ​​of each satellite-to-ground observation pair and each inter-satellite observation pair, a clock difference observation vector is constructed. A weight matrix is ​​constructed based on the standard deviation of clock error for each of the aforementioned satellite-to-ground observation pairs and the standard deviation of clock error for each of the aforementioned inter-satellite observation pairs; Based on the link establishment relationship between the first satellite and the ground station in each of the aforementioned space-to-ground observation pairs, and the link establishment relationship between the second satellite and the first satellite or another second satellite in each of the aforementioned inter-satellite observation pairs, a design matrix is ​​constructed; Based on the clock error observation vector, weight matrix, and design matrix, a joint clock error estimation is performed relative to the reference clock to obtain a joint clock error estimation result. The joint clock error estimation result includes at least one of the following clock error estimates relative to the reference clock: the first satellite, the second satellite, and the ground station.

7. The method according to claim 6, characterized in that, The step of transmitting the joint clock bias estimation result to enable the satellite system to synchronize time includes: The clock bias estimate is sent to the corresponding satellite, which then adjusts its clock based on the received clock bias estimate, thereby synchronizing the inter-satellite and / or satellite-to-ground time of the satellite system.

8. The method according to claim 6, characterized in that, The step of transmitting the joint clock bias estimation result to enable the satellite system to synchronize time includes: The clock bias estimate is sent to the corresponding ground station, which then adjusts its clock based on the received clock bias estimate, thereby synchronizing the inter-satellite and / or satellite-to-ground time of the satellite system.

9. The method according to any one of claims 1 to 3, characterized in that, Before obtaining the joint clock error estimation result by performing joint clock error estimation based on the clock error calculation results of each satellite-to-ground observation pair and each inter-satellite observation pair, the method further includes: Monitor the clock values ​​of satellites and / or ground stations in the satellite system; If the deviation between the clock value and the reference value is greater than the deviation threshold, then the clock difference calculation results of each satellite-to-ground observation pair and the clock difference calculation results of each inter-satellite observation pair of the satellite system are obtained.

10. The method according to claim 9, characterized in that, The acquisition of clock error calculation results for each satellite-to-ground observation pair and each inter-satellite observation pair of the satellite system includes: Acquire real-time two-way ranging data of each satellite-to-ground observation pair and each inter-satellite observation pair of the satellite system; Based on the real-time two-way ranging data of the star-ground observation pair, the clock error of the star-ground observation pair is calculated to obtain the clock error calculation result of the star-ground observation pair; Clock error calculation is performed on the inter-satellite observation pair based on the real-time two-way ranging data of the inter-satellite observation pair to obtain the clock error calculation result of the inter-satellite observation pair.

11. A time synchronization device for a satellite system, characterized in that, include: The calculation module is used to perform joint clock error estimation based on the clock error calculation results of each satellite-to-ground observation pair and each inter-satellite observation pair, and obtain the joint clock error estimation result. Each satellite-to-ground observation pair is an observation combination consisting of a ground station and a first satellite, and each inter-satellite observation pair is an observation combination consisting of a second satellite and a first satellite or another second satellite. The clock error calculation result of each satellite-to-ground observation pair is calculated based on the satellite-to-ground two-way ranging data of the first satellite and the ground station constituting the satellite-to-ground observation pair, and the clock error calculation result of each inter-satellite observation pair is calculated based on the inter-satellite two-way ranging data of the two satellites constituting the inter-satellite observation pair. The transmitting module is used to transmit the joint clock bias estimation results so that the satellite system can synchronize its time.

12. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements the method according to any one of claims 1 to 10.

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