Time synchronization method and system based on satellite common view and time transfer

Abstract

The invention provides a time synchronization method and system based on satellite common view and time transfer, and belongs to the technical field of time synchronization, and the method comprises the following steps: confirming a GNSS system time source and at least two external wired time sources, and carrying out the credibility detection of the GNSS system time source; performing anti-cheating detection on the external wired time sources, confirming the priority, and sorting the external wired time sources based on the priority; when the time source of the GNSS system passes the credibility detection, the time source of the GNSS system is used as a main time source; when the time source of the GNSS system does not pass the credibility detection, selecting an external wired time source with the highest priority to replace the main time source; and calibrating a local endogenous time source of the master station based on the time signal of the master time source, generating master station synchronization time, and performing slave station time synchronization. According to the method, the GNSS system time source and the external wired time source are detected at the same time, the time source with the highest credibility is selected for synchronization, and the accuracy and safety of time synchronization are improved.

Description

Technical Field

[0001] This invention belongs to the field of time synchronization technology, specifically relating to a method and system based on satellite co-viewing and time synchronization. Background Technology

[0002] High-precision time synchronization is the cornerstone of critical infrastructure in modern communications, finance, power, and defense. Currently, mainstream technologies rely on Global Navigation Satellite Systems (GNSS) as the time source, as they provide globally covering UTC time signals with nanosecond-level accuracy. However, GNSS signals are susceptible to unintentional interference or malicious spoofing attacks, leading to time synchronization system failure or the provision of incorrect time, raising serious security concerns. When GNSS signals become unavailable due to obstruction, interference, or equipment malfunction, the system often lacks intelligent and reliable backup and switching mechanisms, making it difficult to guarantee the continuity of time services.

[0003] In the relevant technologies for recalibration when the time synchronization system fails, satellite common view and precise point positioning (PPP) technology are usually combined, or the wired time source is switched when GNSS fails. However, these solutions are usually just simple "master-backup" switching, lacking a refined and intelligent assessment of the quality of the time source. They cannot actively identify and avoid the risk of deception in complex electromagnetic environments, nor can they dynamically select the optimal solution from multiple available time sources. Therefore, there is an urgent need for a time synchronization method that combines high accuracy and security. Summary of the Invention

[0004] To address the problems in the prior art, this invention proposes a time synchronization method and system based on satellite common-view and time transfer. By performing reliability and anti-spoofing detection on the GNSS system time source and external wired time source, the most reliable time source is selected as the main time source, thereby improving the accuracy and security of the time synchronization process.

[0005] The technical solution of the present invention is as follows: In a first aspect, the present invention proposes a time synchronization method based on satellite common-view and time transfer, the method comprising the following steps: Identify the GNSS system time source and at least two external wired time sources, and perform a reliability test on the GNSS system time source; Perform anti-spoofing detection on external wired time sources and confirm their priorities, then sort the external wired time sources based on their priorities; When the GNSS system time source passes the reliability test, the GNSS system time source is used as the primary time source, and the external wired time source is used as the backup time source. When the GNSS system time source fails the reliability test, the highest priority external wired time source is selected from the backup time sources to replace the main time source. The local endogenous time source of the master station is calibrated based on the time signal of the main time source to generate the master station synchronization time, and the slave station time is synchronized according to the master station synchronization time.

[0006] Furthermore, the reliability detection of the GNSS system time source specifically includes the following steps: Obtain relevant signal parameters from the GNSS system time source. These relevant signal parameters should include at least the number of tracked satellites, signal-to-noise ratio, and accuracy factor. Obtain the rate of change of clock error output by the GNSS system time source over a continuous period of time; The time signal output by the GNSS system time source is compared in real time with the time signal output by at least one independent time source, and the absolute value of the time difference is calculated. The independent time source is another GNSS constellation time source or an external wired time source that can be used as a reference. If any of the following occurs, the GNSS system time source is deemed to have failed the reliability test: the relevant signal parameters are outside the preset range, the clock difference rate exceeds the maximum frequency drift of the local endogenous time source, or the absolute value of the time difference is higher than the preset deviation value.

[0007] Furthermore, the step of performing anti-spoofing detection on external wired time sources and confirming their priorities, and then sorting the external wired time sources based on their priorities, specifically includes the following steps: Identify the anti-spoofing factor for each external wired time source and obtain relevant information about external finite time sources; Calculate the weight score of the anti-fraud factor based on relevant information; Construct a priority weight model for external wired time sources based on anti-fraud factors and weight scores; The priority weights of external wired time sources are calculated based on the priority weight model; The priority of each external wired time source is determined based on the priority weight, and the external wired time sources are sorted in descending order of priority.

[0008] Furthermore, the anti-spoofing factors include identity authentication and integrity factors, transmission path security factors, data rationality factors, and historical behavior factors; The identity authentication and integrity factor score is assigned to Score1. The digital signature or encrypted authentication information of the time source protocol message is verified. If the verification is successful, Score1=0; if the verification fails, Score1=-20; if abnormal tampering is detected in the message during transmission, Score1=-15. The transmission path security factor score is assigned as Score2, which is determined by evaluating the physical and logical security of the transmission link. For leased lines or direct fiber optic connections, Score2 = +5; for logical tunnels passing through the public network, Score2 = -10; and for abnormal path changes or rerouting times, Score2 = -10. The data rationality factor score is assigned a value of Score3, which is calculated by determining the deviation between the received external wired time source signal and the predicted value of the disciplined local clock. Next, calculate the score for the data rationality factor. The score calculation formula is as follows: ; Where, Δt th The threshold set for hold capability based on the local clock and the maximum expected network jitter; max represents the maximum value function; The historical behavior factor score is assigned a value of Score4, which is determined by recording the frequency of recent credibility events from an external wired time source. If an authentication failure or path anomaly occurs within the most recent time window T, then Score4 = -10; if no anomaly occurs, then Score4 = 0.

[0009] Furthermore, the priority weight model is as follows: ; Where α is the smoothing factor, 0 < α < 1; w c The priority weight for the current calculation cycle; w p The priority weight of the previous calculation cycle; w max The full score is the weighted score; i The score for the i-th anti-fraud factor; Werght i The preset weight is the i-th anti-fraud factor, and the sum of the preset weights of all anti-fraud factors is 1. According to w c Perform state division: w c ≥75, the external wired time source is in good condition; 50≤w c <75, the external wired time source is in a degraded state; w c <50, the external wired time source is faulty; Backup failover occurs when the primary time source meets one of the following conditions: A. The primary time source is downgraded to a degraded or faulty state; B. There exists another healthy external wired time source with a higher priority than the current primary time source, and the difference between them is greater than H. Where H is the hysteresis threshold.

[0010] Furthermore, when the GNSS system time source fails the reliability test and the backup time sources do not meet the conditions to become the primary time source, the time signal output is maintained by the tamed local endogenous time source.

[0011] Furthermore, when the GNSS system time source is used as the primary time source, the local endogenous time source of the master station is calibrated by receiving and processing the first time signal of the GNSS system time source through the precision single-point positioning time transfer unit of the master station, and calculating the first time deviation between the local endogenous time source of the master station and the first time signal. The first time deviation is used as a feedback quantity, input into the closed-loop control loop, and the first control signal is output. The local endogenous time source is calibrated using the first control signal.

[0012] Furthermore, when an external wired time source is used as the primary time source, the calibration of the master station's local endogenous time source involves receiving the second time signal from the external wired time source through the master station's priority network interface, and calculating the second time deviation between the master station's local endogenous time source and the second time signal. The second time deviation is used as a feedback quantity, input into the closed-loop control loop, and the second control signal is output. The local endogenous time source is calibrated using the second control signal.

[0013] Furthermore, the step of synchronizing the slave station's time based on the master station's synchronization time involves exchanging the common-view data between the master station and the slave station, and calculating the relative clock difference between the master station and the slave station based on the common-view data and the master station's synchronization time. The slave station's local time is adjusted according to the relative clock difference to synchronize the slave station's time.

[0014] Secondly, the present invention provides a time synchronization system based on satellite common-view and time transfer, including a configuration module, a detection module and a time transfer module; The configuration module is used to confirm the GNSS system time and the external wired time source, and to perform a reliability test on the GNSS system time source; The detection module is used to perform anti-spoofing detection on external wired time sources and confirm their priorities, and sort the external wired time sources based on their priorities; the detection module is also used to use the GNSS system time source as the primary time source and the external wired time source as the backup time source when the GNSS system time source passes the reliability test; the detection module is also used to select the highest priority external wired time source from the backup time sources to replace the primary time source when the GNSS system time source fails the reliability test. The time transfer module is used to calibrate the local endogenous time source of the master station according to the time signal of the main time source, generate the master station synchronization time, and perform time synchronization of the slave station according to the master station synchronization time.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention confirms that multiple time sources are used for time synchronization by setting up a GNSS system time source and multiple external wired time sources. At the same time, it performs credibility detection and anti-spoofing detection on the GNSS system time source and multiple external wired time sources respectively, and selects the time source with the highest credibility as the main time source. When performing time synchronization, it no longer relies on a single time source. When the primary time source fails or its performance degrades, it can switch to the optimal backup time source for time synchronization based on priority, thereby improving the accuracy and security of the time synchronization process. Attached Figure Description

[0016] Figure 1 This is a flowchart of a time synchronization method based on satellite common view and time transfer. Detailed Implementation

[0017] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0018] Example 1 This embodiment provides a time synchronization method based on satellite common-view and time transfer, such as Figure 1 As shown, the method includes the following steps: Identify the GNSS system time source and at least two external wired time sources, and perform a reliability test on the GNSS system time source; Perform anti-spoofing detection on external wired time sources and confirm their priorities, then sort the external wired time sources based on their priorities; When the GNSS system time source passes the reliability test, the GNSS system time source is used as the primary time source, and the external wired time source is used as the backup time source. When the GNSS system time source fails the reliability test, the highest priority external wired time source is selected from the backup time sources to replace the main time source. The local endogenous time source of the master station is calibrated based on the time signal of the main time source to generate the master station synchronization time, and the slave station time is synchronized according to the master station synchronization time.

[0019] In this embodiment, the goal of time transfer is to synchronize the time from the master station to the slave station with high precision. In this process, high-precision time synchronization is achieved by using satellite common view. For GNSS system time sources, due to the weak GNSS signal, they are susceptible to unintentional interference or malicious deception attacks, which may cause the time synchronization system to fail or provide incorrect time, which may affect accuracy and security. Therefore, this application introduces an external wired time source to assist in time synchronization. The number of external wired time sources is at least two to achieve effective redundancy backup. The types of external wired time sources include one or more combinations of the following: Precision Time Protocol (PTP) sources received via Ethernet typically provide the highest accuracy for wired time synchronization and are used as the preferred backup source; Network Time Protocol (NTP) sources received via Ethernet are widely deployed in the Internet and local area networks, are easy to obtain, and are used as basic backups; Receive synchronous Ethernet clock signals through the physical layer link, which are used as the basis for high-precision frequency synchronization; In a preferred embodiment of this example, the external time source includes at least one PTP source and one NTP source; wherein the PTP source has a higher initial priority, and the NTP source serves as a basic backup.

[0020] Preferably, the credibility detection of the GNSS system time source includes the following steps: Obtain relevant signal parameters from the GNSS system time source. These relevant signal parameters should include at least the number of tracked satellites, signal-to-noise ratio, and accuracy factor. Obtain the rate of change of clock error output by the GNSS system time source over a continuous period of time; The time signal output from the GNSS system time source is compared in real time with the time signal output from at least one independent time source, and the absolute value of the time difference is calculated. If any of the following occurs, the GNSS system time source is deemed to have failed the reliability test: the relevant signal parameters are outside the preset range, the clock difference rate exceeds the maximum frequency drift of the local endogenous time source, or the absolute value of the time difference is higher than the preset deviation value.

[0021] The relevant signal parameters not being within the preset range include the number of tracked satellites being less than the preset number, the signal-to-noise ratio being lower than the preset signal-to-noise ratio, and the accuracy factor being higher than the preset threshold. The independent time source is another GNSS constellation, such as BeiDou or Galileo, or a highly reliable external wired time source.

[0022] In some embodiments, a quantification standard is added to the credibility detection process. When relevant signal parameters are not within the preset range, the clock difference change rate exceeds the maximum frequency drift of the local endogenous time source, or the absolute value of the time difference is higher than the preset deviation value, a deduction is applied to the quantification detection score. Finally, the credibility of the GNSS system time source is determined by the quantification result.

[0023] Preferably, the step of performing anti-spoofing detection on external wired time sources and confirming their priorities, and then sorting the external wired time sources based on their priorities, specifically includes the following steps: Identify the anti-spoofing factor for each external wired time source and obtain relevant information about the external wired time source; Calculate the weight score of the anti-fraud factor based on relevant information; Construct a priority weight model for external wired time sources based on anti-fraud factors and weight scores; The priority weights of external wired time sources are calculated based on the priority weight model; The priority of each external wired time source is determined based on the priority weight, and the external wired time sources are sorted in descending order of priority.

[0024] The specific steps for calculating the weighted score of the anti-deception factor based on relevant information are as follows: The type of anti-deception factor is identified, and the scoring rules for the anti-deception factor are determined based on the type of the anti-deception factor and the mapping table. The weight score of each anti-deception factor is determined based on the relevant information and the scoring rules. The mapping table stores the correspondence between factor types and the scoring rules.

[0025] The anti-spoofing factors include identity authentication and integrity factors, transmission path security factors, data rationality factors, and historical behavior factors. Each anti-spoofing factor has its own independent calculation rules. The scoring rules for each factor can be determined based on its type and a mapping table, which stores the correspondence between factor types and scoring rules. The mapping table can be stored in the memory of the relevant device and can be invoked when needed to confirm the calculation method.

[0026] The identity authentication and integrity factor needs to detect relevant information, such as verifying the digital signature or encrypted authentication information of the time source protocol message, and apply different values ​​according to the verification results, which are stored through a mapping table; In this embodiment, if the verification passes, Score1=0; if the verification fails, Score1=-20; if the detected message is abnormally tampered with during transmission, Score1=-15; Score1 is the score assigned to the identity authentication and integrity factor.

[0027] The transmission path security factor is assigned a value by evaluating the physical and logical security of the transmission link. For leased lines or direct fiber connections, Score2 = +5; for logical tunnels passing through the public network, Score2 = -10; and for abnormal path changes or rerouting times, Score2 = -10. Score2 is the score assigned to the transmission path security factor.

[0028] The data rationality factor is calculated by first determining the deviation between the received external wired time source signal and the docile local clock prediction. Next, calculate the score for the data rationality factor. The score calculation formula is as follows: ; Wherein, Score3 is the score of the data rationality factor; Δt th The threshold is set based on the hold capability of the local clock and the maximum expected network jitter. The larger the deviation, the higher the error; max represents the maximum value function. Set Δt th The value is 5ns, and when Δt is 3ns, The calculation result is -0.04, the max function takes the value 0, and Score3 = 0; Set Δt th The value is 5 ns, and when Δt is 8 ns, The calculation result is 0.06, the max function takes the value of 0.06, and Score3 = -0.06.

[0029] The historical behavior factor is assigned a value by recording the frequency of recent credibility events from an external wired time source. If an authentication failure or path anomaly occurs within the most recent time window T, then Score4 = -10; if no anomaly occurs, then Score4 = 0.

[0030] The calculation of the priority weight of the external wired time source based on the priority weight model includes the following steps: The weighted score is obtained by calculating the weighted score based on the anti-fraud factor. The weighted score sum is smoothed and corrected based on a preset smoothing factor to obtain the corrected result; The priority weight of the current calculation cycle is obtained based on the smoothing factor and the priority weight of the previous calculation cycle.

[0031] The priority weight model is as follows: ; Where α is the smoothing factor, 0 < α < 1; w c The priority weight for the current calculation cycle; w p The priority weight of the previous calculation cycle; w maxThe full score is the weighted score; i The score for the i-th anti-fraud factor; Werght i Let be the preset weight of the i-th anti-fraud factor, and the sum of the preset weights of all anti-fraud factors is 1.

[0032] Based on the priority weight model, the priority weight w for the current computing cycle is periodically calculated for each external wired time source. c w c The larger the value, the higher it appears in the sorting.

[0033] Preferably, before sorting the external wired time sources, the states are divided according to the values ​​of priority weights: w c ≥75 indicates that the external wired time source is in a healthy state and is qualified to become the primary time source; 50≤w c <75, the external wired time source is in a degraded state and can be used as a backup time source, but it is not recommended to upgrade it to the primary time source; w c <50, the external wired time source is faulty and has been temporarily removed from the available list.

[0034] Of all time sources that are in a healthy state, according to w c The values ​​are sorted in descending order, and the priority of external wired time sources is periodically calculated for real-time monitoring and switching of the primary time source. The current primary time source is switched over when one of the following conditions is met: A. The primary time source is downgraded to a degraded or faulty state; B. There exists another healthy external wired time source with a higher priority than the current primary time source, and the difference between them is greater than H. H is the hysteresis threshold, which prevents frequent time source switching when weights are close.

[0035] When the GNSS system time source fails the reliability test and all external wired time sources do not meet the conditions to become the primary time source, the highly stable local endogenous time source, which has been trained, maintains high-precision output in degraded mode and outputs a degraded signal to the outside.

[0036] Preferably, when the GNSS system time source is used as the primary time source, the calibration of the local endogenous time source of the master station is performed by receiving and processing the first time signal of the GNSS system time source through the PPP time transfer unit of the master station, calculating the first time deviation between the local endogenous time source of the master station and the first time signal; the first time deviation is used as a feedback quantity and input to the closed-loop control loop, such as a phase-locked loop or a Kalman filter, and outputting a control signal to calibrate the local endogenous time source.

[0037] Preferably, when an external wired time source is used as the primary time source, the calibration of the main station's local endogenous time source involves receiving a second time signal from the external wired time source via the main station's wired network interface. The second time signal includes at least a time protocol message. The second time signal is then parsed, time information is recovered, and a second time deviation between the main station's local endogenous time source and the second time signal is calculated. The second time deviation is used as a feedback quantity and input into the closed-loop control loop to output a second control signal. The local endogenous time source is calibrated using the second control signal to generate a master station synchronization time that is synchronized with the second time signal.

[0038] Preferably, the step of synchronizing the slave station's time based on the master station's synchronization time involves exchanging common-view data between the master station and the slave station, calculating the relative clock difference between the master station and the slave station based on the common-view data and the master station's synchronization time, and adjusting the slave station's local time based on the relative clock difference to perform slave station time synchronization.

[0039] Example 2 This embodiment provides a time synchronization system based on satellite common-view and time transfer, including: a configuration module, a detection module, and a time transfer module; The configuration module is used to confirm the GNSS system time source and the external wired time source, and to perform a reliability test on the GNSS system time source; The detection module is used to perform anti-spoofing detection on external wired time sources and confirm their priorities, and sort the external wired time sources based on their priorities; the detection module is also used to use the GNSS system time source as the primary time source and the external wired time source as the backup time source when the GNSS system time source passes the reliability test; the detection module is also used to select the highest priority external wired time source from the backup time sources to replace the primary time source when the GNSS system time source fails the reliability test. The time transfer module is used to calibrate the local endogenous time source of the master station according to the time signal of the main time source, generate the master station synchronization time, and perform time synchronization of the slave station according to the master station synchronization time.

[0040] It should be noted that the user information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data used for analysis, data stored, data displayed, etc.) involved in this application are all information and data authorized by the user or fully authorized by all parties, and the collection, use and processing of relevant information comply with relevant regulations.

[0041] The data involved in the various embodiments provided in this application includes at least one type of relational database and non-relational database; the processor involved in the various embodiments provided in this application may be a general-purpose processor, a central processing unit, a graphics processor, a digital signal processor, a programmable logic device, a quantum computing-based data processing logic device, etc.

[0042] The technical features of the above embodiments can be combined arbitrarily. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

Claims

1. A time synchronization method based on satellite common-view and time transfer, characterized in that, The method includes the following steps: Identify the GNSS system time source and at least two external wired time sources, and perform a reliability test on the GNSS system time source; Perform anti-spoofing detection on external wired time sources and confirm their priorities, then sort the external wired time sources based on their priorities; When the GNSS system time source passes the reliability test, the GNSS system time source is used as the primary time source, and the external wired time source is used as the backup time source. When the GNSS system time source fails the reliability test, the highest priority external wired time source is selected from the backup time sources to replace the main time source. The local endogenous time source of the master station is calibrated based on the time signal of the main time source to generate the master station synchronization time, and the slave station time is synchronized according to the master station synchronization time.

2. The time synchronization method based on satellite common-view and time transfer according to claim 1, characterized in that, The reliability detection of the GNSS system time source specifically includes the following steps: Obtain relevant signal parameters from the GNSS system time source. These relevant signal parameters should include at least the number of tracked satellites, signal-to-noise ratio, and accuracy factor. Obtain the rate of change of clock error output by the GNSS system time source over a continuous period of time; The time signal output by the GNSS system time source is compared in real time with the time signal output by at least one independent time source, and the absolute value of the time difference is calculated. The independent time source is another GNSS constellation time source or an external wired time source that can be used as a reference. If any of the following occurs, the GNSS system time source is deemed to have failed the reliability test: the relevant signal parameters are outside the preset range, the clock difference rate exceeds the maximum frequency drift of the local endogenous time source, or the absolute value of the time difference is higher than the preset deviation value.

3. The time synchronization method based on satellite common-view and time transfer according to claim 1, characterized in that, The process of performing anti-spoofing detection on external wired time sources and confirming their priorities, and then sorting the external wired time sources based on these priorities, specifically includes the following steps: Identify the anti-spoofing factor for each external wired time source and obtain relevant information about external finite time sources; Calculate the weight score of the anti-fraud factor based on relevant information; Construct a priority weight model for external wired time sources based on anti-fraud factors and weight scores; The priority weights of external wired time sources are calculated based on the priority weight model; The priority of each external wired time source is determined based on the priority weight, and the external wired time sources are sorted in descending order of priority.

4. The time synchronization method based on satellite common-view and time transfer according to claim 3, characterized in that, The anti-fraud factors include identity authentication and integrity factors, transmission path security factors, data rationality factors, and historical behavior factors. The identity authentication and integrity factor score is assigned to Score1. The digital signature or encrypted authentication information of the time source protocol message is verified. If the verification is successful, Score1=0; if the verification fails, Score1=-20; if abnormal tampering is detected in the message during transmission, Score1=-15. The transmission path security factor score is assigned as Score2, which is determined by evaluating the physical and logical security of the transmission link. For leased lines or direct fiber optic connections, Score2 = +5; for logical tunnels passing through the public network, Score2 = -10. If there are abnormal path changes or rerouting times, Score2 = -10; The data rationality factor score is assigned a value of Score3, which is calculated by determining the deviation between the received external wired time source signal and the predicted value of the disciplined local clock. Next, calculate the score for the data rationality factor. The score calculation formula is as follows: ； Where, Δt th The threshold set for the hold capability based on the local clock and the maximum expected network jitter; max represents the maximum value function; The historical behavior factor score is assigned a value of Score4, which is determined by recording the frequency of recent credibility events from an external wired time source. If an authentication failure or path anomaly occurs within the most recent time window T, then Score4 = -10; if no anomaly occurs, then Score4 = 0.

5. A time synchronization method based on satellite common-view and time transfer according to claim 3, characterized in that, The priority weight model is as follows: ； Where α is the smoothing factor, 0 < α < 1; w c The priority weight for the current calculation cycle; w p The priority weight of the previous calculation cycle; w max The full score is the weighted score; i The score for the i-th anti-fraud factor; Werght i The preset weight is the i-th anti-fraud factor, and the sum of the preset weights of all anti-fraud factors is 1. According to w c Perform state division: w c ≥75, the external wired time source is in good condition; 50≤w c <75, the external wired time source is in a degraded state; w c <50, the external wired time source is faulty; Backup failover occurs when the primary time source meets one of the following conditions: A. The primary time source is downgraded to a degraded or faulty state; B. There exists another healthy external wired time source with a higher priority than the current primary time source, and the difference between them is greater than H. Where H is the hysteresis threshold.

6. The time synchronization method based on satellite common-view and time transfer according to claim 1, characterized in that, When the GNSS system time source fails the reliability test and the backup time sources do not meet the conditions to become the primary time source, the time signal output is maintained by the tamed local endogenous time source.

7. The time synchronization method based on satellite common-view and time transfer according to claim 1, characterized in that, When the GNSS system time source is used as the main time source, the local endogenous time source of the master station is calibrated, and the first time signal of the GNSS system time source is received and processed through the precision single-point positioning time transfer unit of the master station, and the first time deviation between the local endogenous time source in the master station and the first time signal is calculated. The first time deviation is used as a feedback quantity, input into the closed-loop control loop, and the first control signal is output. The local endogenous time source is calibrated using the first control signal.

8. A time synchronization method based on satellite common-view and time transfer according to claim 1, characterized in that, When an external wired time source is used as the primary time source, the calibration of the master station's local endogenous time source involves receiving the second time signal from the external wired time source through the master station's priority network interface and calculating the second time deviation between the master station's local endogenous time source and the second time signal. The second time deviation is used as a feedback quantity, input into the closed-loop control loop, and the second control signal is output. The local endogenous time source is calibrated using the second control signal.

9. A time synchronization method based on satellite common-view and time transfer according to claim 1, characterized in that, The process of synchronizing the slave station's time based on the master station's synchronization time involves exchanging the shared data between the master and slave stations, and calculating the relative clock difference between the master and slave stations based on the shared data and the master station's synchronization time. The slave station's local time is adjusted according to the relative clock difference to synchronize the slave station's time.

10. A time synchronization system based on satellite common-view and time transfer, characterized in that, It includes a configuration module, a detection module, and a time transmission module; The configuration module is used to confirm the GNSS system time and the external wired time source, and to perform a reliability test on the GNSS system time source; The detection module is used to perform anti-spoofing detection on external wired time sources and confirm their priorities, and sort the external wired time sources based on their priorities; the detection module is also used to use the GNSS system time source as the primary time source and the external wired time source as the backup time source when the GNSS system time source passes the reliability test; the detection module is also used to select the highest priority external wired time source from the backup time sources to replace the primary time source when the GNSS system time source fails the reliability test. The time transfer module is used to calibrate the local endogenous time source of the master station according to the time signal of the main time source, generate the master station synchronization time, and perform time synchronization of the slave station according to the master station synchronization time.

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