Satellite autonomous clock error estimation method, reference establishment method, device and product

Abstract

The invention relates to the technical field of spacecraft autonomous time keeping, and discloses a satellite autonomous clock error estimation method, a reference establishment method, a device and a product. The satellite autonomous clock error estimation method comprises the following steps: constructing a laser communication link between satellites based on a laser communication list; any satellite carrying an atomic clock with the precision not lower than E-16 magnitude is determined as a reference satellite; calculating a target clock difference between a target satellite and the reference satellite based on a first clock difference between adjacent satellites in the laser communication link; the target satellite is any satellite except the reference satellite in the navigation satellite constellation system; and the adjacent satellites directly communicate with each other through a laser communication link. By adopting the method, a navigation constellation system running in a high orbit can realize space-based autonomous high-precision clock error estimation and clock synchronization in a global range.

Description

Technical Field

[0001] The present application relates to the technical field of autonomous timekeeping for spacecrafts, and particularly to a method for estimating satellite autonomous clock offset, a method for establishing a reference, a device and a product. Background Art

[0002] Navigation satellites are widely used in multiple fields such as social economy, scientific research, traffic management, and disaster warning. The clock offset of the on-board atomic clocks carried by them directly affects the positioning accuracy of navigation satellites. In the context of multi-system integration, such as GPS (Global Positioning System), GLONASS (Global Navigation Satellite System), Galileo (Galileo Global Satellite Navigation System), and BDS (Beidou Navigation Satellite System), the robustness of satellite navigation positioning services also highly depends on satellite clock offset estimation. Therefore, the clock offset estimation of on-board atomic clocks is crucial.

[0003] The current methods for estimating the clock offset of satellite systems mainly calibrate the on-board atomic clocks by continuously communicating the satellites with ground control stations. However, during the communication with ground control stations, the signals need to penetrate the ionosphere and troposphere of the earth, and the signals are easily affected during transmission, resulting in delays, which affect the accuracy of clock offset estimation. Moreover, some signals are sensitive to weather conditions, making it difficult to ensure the stability and reliability of clock offset estimation. For example, laser signals are very sensitive to weather conditions, and weather conditions such as clouds, fog, and atmospheric turbulence may all affect the transmission of laser signals. In addition, the space-ground communication depends on the geographical distribution and density of ground control stations. For a global navigation constellation, if the ground control stations are unevenly distributed or there is a lack of CORS stations in some regions, it will affect the clock offset estimation of satellites in these regions, and the maintenance and operation costs of ground stations are also very high. Therefore, it is very difficult to achieve high-precision and stable constellation clock offset estimation. Summary of the Invention

[0004] In view of this, the present application aims to propose a method for estimating satellite autonomous clock offset, a method for establishing a reference, a device and a product, so as to achieve high-precision clock offset estimation of a navigation satellite constellation and improve the stability of clock offset estimation.

[0005] To achieve the above object, the technical solution of the present application is as follows:

[0006] A first aspect of an embodiment of the present application provides a method for autonomous satellite clock error estimation, which is applied to a navigation satellite constellation system. The navigation satellite constellation system includes multiple high-orbit satellites deployed globally; wherein, each satellite is equipped with an atomic clock, and at least one satellite is equipped with an atomic clock with an accuracy not lower than the E-16 level; the method includes:

[0007] Based on the laser communication list, construct laser communication links between each satellite;

[0008] Determine a satellite equipped with an atomic clock with an accuracy not lower than the E-16 level as a reference satellite; based on the first clock differences between adjacent satellites in the laser communication link, calculate the target clock difference between the target satellite and the reference satellite; the target satellite is any satellite other than the reference satellite in the navigation satellite constellation system; the adjacent satellites communicate directly through the laser communication link.

[0009] Optionally, before constructing the laser communication links between each satellite based on the laser communication list, it further includes:

[0010] Obtain the coordinates of each satellite, the geocentric coordinates, the height of the ionosphere, and the equatorial radius of the earth in the CGCS2000 coordinate system, and determine all visible satellites of each satellite; the communication link constructed between the satellite and the corresponding visible satellite is not affected by the ionosphere of the earth;

[0011] Sort all visible satellites of each satellite in ascending order of number to construct a visible list;

[0012] Traverse the visible lists of all satellites, and remove the numbers of the satellites that have been traversed before from each visible list to complete the update of the visible list;

[0013] Construct the laser communication list based on all updated visible lists, and set the communication time periods of every two adjacent satellites in the laser communication list.

[0014] Optionally, determining all visible satellites of each satellite includes:

[0015] Based on the equatorial radius of the earth and the height of the ionosphere, calculate the height of the ionosphere from the geocenter;

[0016] For a target satellite, based on the coordinates of the target satellite, the coordinates of a candidate satellite, and the geocentric coordinates, determine the height of the perpendicular intersection point of the line connecting the geocenter to the two satellites from the geocenter;

[0017] Compare the height of the intersection point of the vertical line from the candidate satellite to the center of the Earth with the height of the ionosphere from the center of the Earth. When the height of the intersection point of the vertical line from the candidate satellite to the center of the Earth is greater than the height of the ionosphere from the center of the Earth, determine that the candidate satellite is a visible satellite of the target satellite.

[0018] Optionally, the satellite autonomous clock error estimation method further includes:

[0019] Each satellite sends a measurement signal to its adjacent satellite and receives the measurement signal carrying the phase change amount returned by the adjacent satellite;

[0020] Each satellite performs frequency mixing and phase difference measurement on the returned measurement signal to calculate the corresponding distance observable;

[0021] Based on the distance observables corresponding to each satellite, calculate the first clock error between each satellite and its adjacent satellite.

[0022] Optionally, calculating the target clock error between the target satellite and the reference satellite based on the first clock error between adjacent satellites in the laser communication link includes:

[0023] For a target satellite, determine the target path between the target satellite and the reference satellite based on the laser communication list;

[0024] Accumulate the first clock errors between adjacent satellites in the target path to determine the target clock error between the target satellite and the reference satellite.

[0025] Optionally, determining the target path between the target satellite and the reference satellite based on the laser communication list includes:

[0026] Determine whether the reference satellite is an adjacent satellite of the target satellite;

[0027] If the reference satellite is an adjacent satellite of the target satellite, determine the laser communication link between the target satellite and the reference satellite as the target path;

[0028] If the reference satellite is not an adjacent satellite of the target satellite, search the laser communication list to obtain all satellites that enable the target satellite to communicate indirectly with the reference satellite, and determine the corresponding candidate paths; determine the candidate path with the smallest number of satellites as the target path.

[0029] Optionally, after constructing the laser communication links between satellites, it further includes:

[0030] Based on the laser communication list, detect all laser communication links at the first interval time to determine whether there is a disconnection; and, determine whether adjacent satellites are visible to each other;

[0031] In the case where any laser communication link is disconnected or any two adjacent satellites are not visible to each other, re-determine the visible satellites of each satellite and re-construct the laser communication links between the satellites.

[0032] According to the second aspect of the embodiments of the present application, there is provided a satellite autonomous clock error estimation device for implementing the steps in the method provided in the first aspect of the embodiments of the present application. The device is deployed in a navigation satellite constellation system, and the navigation satellite constellation system includes a plurality of high-orbit satellites deployed globally; wherein, each satellite is equipped with an atomic clock, and at least one satellite is equipped with an atomic clock with an accuracy not lower than the E-16 level; the device includes:

[0033] A link establishment module configured to construct laser communication links between the satellites based on the laser communication list;

[0034] A calculation module configured to determine a satellite equipped with an atomic clock with an accuracy not lower than the E-16 level as a reference satellite; calculate the target clock error between the target satellite and the reference satellite based on the first clock error between adjacent satellites in the laser communication link; the target satellite is any satellite other than the reference satellite in the navigation satellite constellation system; the adjacent satellites communicate directly through the laser communication link.

[0035] According to the third aspect of the embodiments of the present application, there is provided a reference establishment method applied to the navigation satellite constellation system in the method provided in the first aspect of the embodiments of the present application. The method includes:

[0036] Execute the method provided in the first aspect of the embodiments of the present application to obtain the target clock error between the target satellite and the reference satellite in the navigation satellite constellation system; the target satellite is any satellite other than the reference satellite in the navigation satellite constellation system;

[0037] Obtain the reference time output by the atomic clock carried by the reference satellite;

[0038] Based on the reference time and the target clock error, calibrate the atomic clock carried by the target satellite.

[0039] According to the fourth aspect of the embodiments of the present application, there is provided a reference establishment device for implementing the method provided in the third aspect of the embodiments of the present application, including:

[0040] The satellite autonomous clock error estimation device, time synchronization module and calibration module provided in the second aspect of the embodiments of the present application;

[0041] The time synchronization module is configured to obtain the reference time output by the atomic clock carried by the reference satellite;

[0042] The calibration module is configured to calibrate the atomic clock carried by the target satellite based on the reference time and the target clock difference.

[0043] According to a fifth aspect of the embodiments of the present application, there is provided a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the steps in the method provided in the first aspect or the third aspect of the embodiments of the present application are implemented.

[0044] According to a sixth aspect of the embodiments of the present application, there is provided an electronic device, including a memory, a processor, and a computer program stored on the memory and executable on the processor. When the computer program is executed by the processor, the steps in the method provided in the first aspect or the third aspect of the embodiments of the present application are implemented.

[0045] By using the satellite autonomous clock difference estimation method provided in the present application, a laser communication link is constructed between each satellite in the navigation satellite constellation system based on the laser communication list, and a satellite carrying a high-precision (not less than the E-16 level) clock source is used as the reference satellite. The clock source carried by the reference satellite is used as the time reference. Based on the clock differences (i.e., the first clock differences) between adjacent satellites in the laser communication link, the clock difference (i.e., the target clock difference) between any target satellite to be estimated for clock difference and the reference satellite is indirectly estimated, so as to realize the clock difference estimation of each satellite in the constellation system. Furthermore, based on the time provided by the clock source on the reference satellite and the clock differences between each satellite and the reference satellite, the calibration of the atomic clocks carried by each satellite is completed.

[0046] The method provided in the present application can realize space-based autonomous high-precision clock difference estimation in a navigation constellation system operating in a high orbit, as well as global clock synchronization and calibration. Specifically, the following beneficial effects exist:

[0047] (1) By using the high-precision clock source carried in the satellite system, a more stable time reference can be provided, without relying on any external time source (such as a ground clock source). Especially in special cases (such as the case where communication with a ground station is impossible), the satellite system can still rely on the space-based clock source to maintain high-precision time synchronization, thereby improving the robustness of the positioning service of the navigation satellite constellation system;

[0048] (2) Through the laser communication link constructed in the constellation system and the high-precision clock source carried on the reference satellite, high-precision time comparison and atomic clock calibration between satellites in different regions around the world can be realized, providing a precise time source for global navigation positioning and timing service applications;

[0049] (3) The inter-satellite laser communication link deployed in the high orbit (above 1000 km) is not affected by the Earth's ionosphere, clouds, fog, etc., and can achieve fast, high-precision, and stable clock difference estimation between adjacent satellites. Compared with the strategy of using the laser payload of low-orbit (below 1000 km) spacecraft to estimate the clock difference in the related technology, the real-time performance, efficiency, and accuracy of this solution are greatly improved;

[0050] (4) Since the clock difference estimation process is completely based on the inter-satellite communication method, it gets rid of the dependence on the geographical location and distribution of the ground control station, and reduces the maintenance and operation costs of the ground station. Description of the Drawings

[0051] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required to be used in the description of the embodiments of the present application will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0052] Figure 1 is a flowchart of a satellite autonomous clock difference estimation method proposed in an embodiment of the present application;

[0053] Figure 2 is a topological schematic diagram of constructing a laser communication link in an embodiment of the present application;

[0054] Figure 3 is a schematic diagram of determining visible satellites in an embodiment of the present application;

[0055] Figure 4 is a schematic diagram of a satellite autonomous clock difference estimation device proposed in an embodiment of the present application;

[0056] Figure 5 is a schematic diagram of finding a candidate path in an embodiment of the present application;

[0057] Figure 6 is a flowchart of a reference establishment method proposed in an embodiment of the present application;

[0058] Figure 7 is a schematic diagram of a reference establishment device proposed in an embodiment of the present application;

[0059] Figure 8 is a schematic diagram of an electronic device proposed in an embodiment of the present application. Detailed Embodiments

[0060] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are some, but not all, of the embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present application without making creative efforts shall fall within the protection scope of the present application.

[0061] It should be understood that the term "one embodiment" or "an embodiment" mentioned throughout the specification means that a particular feature, structure, or characteristic related to the embodiment is included in at least one embodiment of the present application. Therefore, the appearances of the phrase "in one embodiment" or "in an embodiment" throughout the specification do not necessarily refer to the same embodiment. In addition, these specific features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

[0062] In various embodiments of the present application, it should be understood that the sequence numbers of the following processes do not imply the order of execution, and the order of execution of each process should be determined by its function and internal logic, and should not constitute any limitation to the implementation process of the embodiments of the present application.

[0063] Exemplary embodiments will be described in detail herein, and examples thereof are shown in the accompanying drawings. When the following description refers to the accompanying drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present application. On the contrary, they are merely examples of devices and methods consistent with some aspects detailed in the present application.

[0064] It should be noted that, without conflict, the embodiments in the present application and the features in the embodiments may be combined with each other.

[0065] Traditional satellite clock bias estimation schemes include: ground-based radio two-way comparison method, ground-based laser two-way comparison, and joint solution of ground CORS station networks. Among them, the ground-based radio two-way comparison method measures the clock bias through the exchange of radio signals between the ground station and the satellite. Its disadvantage is that it is easily affected by ionospheric delay and tropospheric delay, reducing the accuracy of clock bias estimation. The ground-based laser two-way comparison method uses laser as the signal source. Compared with radio waves, laser has a higher frequency and a shorter wavelength, so it can provide higher measurement accuracy. However, the defect is that it is very sensitive to weather conditions. For example, clouds, fog, and atmospheric turbulence may all affect the propagation of laser signals, thus unable to ensure the stability and reliability of clock bias estimation. The method of joint solution of ground CORS station networks estimates satellite clock bias through a ground continuous operation reference station network. Its advantage is that it can provide continuous and real-time clock bias estimation. The single defect is that it seriously depends on the geographical distribution and density of ground control stations. If the ground stations are unevenly distributed globally or there is a lack of CORS stations in some regions, the accuracy of satellite clock bias estimation in these regions will be seriously affected. Moreover, the maintenance and operation costs of ground stations are also very high, adding difficulties to the implementation of the scheme.

[0066] In this application, a high-precision atomic clock carried by a reference satellite in a high-orbit navigation satellite constellation system is used as a space-based clock source. By constructing laser communication links between various satellites in the constellation system, two-way time comparison between adjacent satellites based on the laser communication links is realized. Then, the clock bias between adjacent satellites is estimated through the comparison results, and further indirectly reduced to the target clock bias between each satellite and the reference satellite. Thus, the time benchmark unification and atomic clock calibration of all satellites in the constellation system globally are achieved. Hereinafter, this application will be described in detail with reference to the accompanying drawings and in conjunction with embodiments.

[0067] Figure 1 It is a flowchart of a satellite autonomous clock bias estimation method proposed in an embodiment of this application. This method is applied to a navigation satellite constellation system, and the navigation satellite constellation system includes multiple high-orbit satellites deployed globally; among them, each satellite is equipped with an atomic clock, and at least one satellite is equipped with an atomic clock with an accuracy not lower than the E-16 level. As Figure 1 shown, the method includes:

[0068] S11: Based on the laser communication list, construct laser communication links between various satellites;

[0069] S12: Determine a satellite equipped with an atomic clock with an accuracy not lower than the E-16 level as a reference satellite; calculate the target clock difference between the target satellite and the reference satellite based on the first clock differences between adjacent satellites in the laser communication link; the target satellite is any satellite other than the reference satellite in the navigation satellite constellation system; adjacent satellites communicate directly through the laser communication link.

[0070] In this embodiment, each satellite in the constellation system is equipped with a laser link payload, which has high-precision measurement, fast information synchronization ability, and high-efficiency calculation ability. Considering that in the traditional method, when using the laser link for time synchronization measurement between the satellite and the ground clock source, a relatively high error accuracy can be achieved (the error standard deviation is lower than 0.05 ns), so in this embodiment, the laser payload is also selected for the communication link between satellites. Since the space-based laser inter-satellite link is not affected by the Earth's ionosphere and atmospheric environment, therefore, compared with the clock difference estimation between the satellite and the ground, the clock difference estimation using the inter-satellite laser link can achieve higher accuracy, and the advantage of using the inter-satellite laser link can ensure high-precision time comparison between satellites in different regions globally.

[0071] In this embodiment, a satellite equipped with an atomic clock with an accuracy not lower than the E-16 level is used as a reference satellite. Taking the BDS navigation satellite constellation system as an example, the BDS constellation system includes multiple high-orbit navigation satellites deployed in different regions globally. To achieve space-based autonomous clock difference estimation and clock synchronization, atomic clocks with an accuracy not lower than the E-16 level are deployed on one or more satellites in the constellation system. Given the high accuracy and stability of such atomic clocks, they can be used as a stable space-based time reference to provide a unified time reference for other satellites in the constellation system. The clock difference estimation of the constellation system first requires constructing a laser communication link between each satellite in the system. After the laser communication link is constructed, other satellites in the constellation system can be directly or indirectly connected to the reference satellite through the laser link. In the constructed laser communication network, two satellites that can communicate directly through the laser link are adjacent satellites to each other. For two adjacent satellites, the clock difference (i.e., the first clock difference) between the two satellites can be measured by the locally installed laser link payload. Based on the first clock differences between adjacent satellites in the laser communication link, the clock differences (i.e., the target clock differences) between each satellite and the reference satellite can be indirectly calculated. Furthermore, based on the target clock differences corresponding to each satellite, the clock synchronization and atomic clock calibration of each satellite in the navigation satellite constellation system can be quickly completed.

[0072] In the related solutions, the reference atomic clock is deployed on a low-orbit spacecraft, and the clock error estimation of high-orbit satellites is realized through the signal communication of ground-low orbit-high orbit. However, since the operating orbit of the low-orbit spacecraft is still within the ionosphere coverage, the signal transmission process is still inevitably affected by the ionosphere, resulting in reduced accuracy. Moreover, due to the low operating orbit of the low-orbit spacecraft, its anti-destruction ability is poor, and it is easily interfered with or damaged, unable to ensure the long-term provision of a stable clock reference. In this embodiment, the constellation system operates in a high orbit (about 20,000 kilometers), completely unaffected by the Earth's ionosphere and atmospheric factors, capable of achieving high-precision clock error estimation. Moreover, the satellites operating in high orbits have strong anti-destruction ability and can provide a safe and stable clock reference for a long time, ensuring the stable operation of the constellation system positioning service. This solution uses the inter-satellite laser link constructed in the constellation system to complete the high-precision clock error estimation between adjacent satellites and the indirect clock error estimation of each satellite and the reference satellite, realizing the space-based autonomous time comparison of navigation satellites globally. Since the atomic clock serving as the time reference is directly deployed in the high-orbit constellation system, the clock error estimation process does not require communication with the ground and can achieve long-term space-based autonomous clock error estimation and time synchronization.

[0073] As an implementation manner of this application, before constructing the laser communication links between each satellite based on the laser communication list, it further includes:

[0074] Obtain the coordinates of each satellite, the geocentric coordinates, the height of the ionosphere, and the Earth's equatorial radius in the CGCS2000 coordinate system, and determine all visible satellites of each satellite; the communication links constructed between the satellite and the corresponding visible satellites are not affected by the Earth's ionosphere;

[0075] Sort all the visible satellites of each satellite in ascending order of their numbers to construct a visible list;

[0076] Traverse the visible lists of all satellites, and remove the numbers of the satellites that have been traversed before from each visible list to complete the update of the visible list;

[0077] Construct the laser communication list based on all the updated visible lists, and set the communication time periods of every two adjacent satellites in the laser communication list.

[0078] In one embodiment, the on-orbit coordinates of satellites are used to construct the laser communication links in the constellation system through dynamic link establishment. Specifically, first, the on-orbit coordinates and geocentric coordinates of each satellite in the constellation system in the CGCS2000 coordinate system (China Geodetic Coordinate System 2000) are obtained, and the height of the Earth's ionosphere and the equatorial radius are acquired. Based on these data, the visible satellites of each satellite are determined. The visible satellites of a satellite are those that can observe each other, and the connection line between the visible satellites and this satellite completely avoids the Earth's ionosphere. Therefore, a communication link that is not affected by the ionosphere can be constructed between them. In this embodiment, each satellite in the constellation system has a unique number. After determining all the visible satellites of each satellite, a visible list is constructed based on all the visible satellites of each satellite, and all the visible satellites are sorted in ascending order according to the satellite numbers.

[0079] Then, traverse the visible lists corresponding to each satellite, and remove the numbers of the satellites that have been traversed before from the currently traversed visible list to complete the update of this visible list. Optionally, traverse each visible list in ascending order according to the satellite numbers. For example, the visible list ListA of the satellite numbered "01" includes the satellites numbered "02, 03, 05", and the visible list ListB of the satellite numbered "02" includes the satellites numbered "01, 04, 05". Then, when traversing ListA first and then ListB, since the numbers "01, 02, 05" have already appeared in the previous ListA, the satellite numbers that have appeared in ListA and the traversed satellite number "01" are excluded from ListB. That is, the numbers "01, 05" are removed from the visible list ListB, and only the number "04" is retained. Subsequently, when constructing the laser communication links, a laser link will be constructed respectively between the satellite numbered "01" and the 3 satellites numbered "02, 03, 05", and a laser link will be constructed between the satellite numbered "02" and the satellite numbered "04".

[0080] After traversing all the visible lists corresponding to all the satellites, a laser communication list is constructed based on the current visible lists corresponding to all the satellites, and subsequently, the laser communication network of the constellation system will be built based on this list.

[0081] Figure 2 It is a topological schematic diagram of constructing a laser communication link in an embodiment of the present application. As Figure 2 shown, referring to satellite S 0 and 3 visible satellites S j a laser communication link is constructed between them. For the reference satellite, there are still invisible satellites S i, these invisible satellites build laser links with other invisible satellites of the reference satellite or visible satellites of the reference satellite through their own visible lists. It is worth noting that based on the laser communication list, a satellite may build laser links with multiple other satellites at the same time. For example, Figure 2 Each S j Each satellite is linked to at least two satellites. In order to ensure that the laser signals sent by each satellite are not interfered during the transmission process and to improve the communication quality, after the laser communication list is constructed, the corresponding communication time period is also allocated to each adjacent satellite, staggering the communication time periods between multiple satellites connected to the same satellite to avoid conflicts. Specifically, the link establishment time allocation plan is carried out according to the number of satellites and the location of the satellites, and the laser communication list is synchronized to each satellite through the laser link.

[0082] The two-way time comparison between adjacent satellites in the entire constellation system is repeated according to a preset target period, and the clock error estimation and onboard atomic clock calibration of the entire constellation system are completed once in each period. In practical applications, the target period can be set to 7 sidereal days.

[0083] As an implementation of the present application, all visible satellites of each satellite are determined, including:

[0084] Calculating the height of the ionosphere from the center of the earth based on the earth's equatorial radius and the height of the ionosphere;

[0085] For a target satellite, based on the coordinates of the target satellite, the coordinates of a candidate satellite and the coordinates of the center of the earth, determine the height of the intersection of the perpendicular lines from the center of the earth to the two satellites from the center of the earth;

[0086] The height of the intersection of the vertical lines from the center of the earth is compared with the height of the ionosphere from the center of the earth. When the height of the intersection of the vertical lines from the center of the earth is greater than the height of the ionosphere from the center of the earth, the candidate satellite is determined to be a visible satellite of the target satellite.

[0087] In one embodiment, the visible satellites for each satellite are determined based on the altitude of the Earth's ionosphere. Figure 3 FIG. 1 is a schematic diagram of determining visible satellites in one embodiment of the present application. Figure 3 As shown in the figure, before building a laser link, it is necessary to determine whether the satellites are visible to each other through the on-orbit coordinates, geocentric coordinates, ionospheric height and equatorial radius of each satellite. The specific steps are as follows:

[0088] (1) In the CGCS2000 coordinate system, calculate the distance from the center of the Earth to the two satellites S i , S j The height of the intersection of the perpendicular lines between:

[0089] Assume E 0 represents the geocentric coordinates, and h i-max represents the maximum height at which the ionosphere affects the time comparison of the laser link. The spatial vector coordinates of satellite S i are Satellite S j has spatial vector coordinates of The perpendicular intersection point K of the line connecting the geocenter to vector S i to S j has vector coordinates of d which is obtained by the following formula: is obtained through the following formula:

[0090]

[0091] Furthermore, based on the geocentric coordinates E 0 to the vector coordinates of this point the perpendicular intersection point height d of the line connecting two satellites S i and S j is calculated (i.e., E 0 K d ). Among them

[0092] (2) Calculate the height of the ionosphere. Taking the equatorial radius of 6378.137 km and the distribution height of the ionosphere 1000 km above the ground, the height h i-max of the ionosphere = 6378.137 km + 1000 km;

[0093] (3) Compare the perpendicular intersection point height d of the line connecting two satellites S i and S j with the height h i-max of the ionosphere. If d > h i-max , it means that the line connecting the two satellites avoids the ionosphere, that is, if a laser communication link is built between the two satellites, it will not be affected by the ionosphere. Therefore, it is determined that satellite S j and satellite S i are mutually visible. On the contrary, if d ≤ h i-max , it means that the line connecting the two satellites is affected by the ionosphere (such as Figure 3 the satellites marked as non-visible), and the two are mutually non-visible, and a laser link cannot be built between them.

[0094] In this embodiment, all the visible satellites corresponding to the satellites are determined in the above manner, which can ensure that the subsequent laser communication link generated based on the visible satellites is not affected by the ionosphere, thereby ensuring the high precision of the subsequent clock difference estimation. A corresponding visible list is constructed for each satellite and sorted in ascending order according to the unique ID (number) of the satellite, and by traversing each visible list in turn, the planning of the laser links between all satellites is realized.

[0095] As an implementation manner of the present application, after constructing the laser communication links between satellites, it further includes:

[0096] Based on the laser communication list, all laser communication links are detected at a first time interval to determine whether there is a disconnection; and, it is determined whether adjacent satellites are visible to each other;

[0097] In the case where any laser communication link is disconnected or any two adjacent satellites are not visible to each other, the visible satellites of each satellite are re-determined, and the laser communication links between the satellites are re-constructed.

[0098] Since each satellite operates dynamically in its own orbit, during the movement of the satellites, the laser link may pass through the ionosphere, resulting in the influence of signal transmission and affecting the accuracy of clock offset estimation. In addition, the communication link between satellites may also be disconnected due to certain factors, such as the laser payload or the satellite being detected as unavailable due to a fault.

[0099] In order to ensure the stability and high accuracy of the clock offset estimation of the constellation system, in one embodiment, the laser links in the constellation system are periodically detected at a first time interval to determine whether each laser link can communicate normally, and, based on the coordinates of the current satellite, it is determined whether adjacent satellites (i.e., two satellites with a laser link therebetween) are still visible to each other. If there is any laser link disconnected, or any laser link passes through the ionosphere (i.e., any two adjacent satellites become invisible), the laser link construction process is re-executed, and all laser communication links are re-constructed in the constellation system based on the coordinates of the current satellites and the corresponding visible satellites.

[0100] In this embodiment, by periodically detecting the on / off status of the laser links and whether adjacent satellites are visible (i.e., whether the links are affected by the ionosphere), the dynamic link establishment and maintenance of the laser communication network in the constellation system are realized, and the factors reducing the clock offset estimation accuracy are quickly responded to through regular monitoring, thereby stably maintaining the high-precision clock offset estimation of the constellation system.

[0101] As an implementation manner of the present application, the satellite autonomous clock offset estimation method further includes:

[0102] Each satellite sends a measurement signal to its adjacent satellite and receives the measurement signal carrying the phase change amount returned by the adjacent satellite;

[0103] Each satellite performs mixing and phase difference measurement on the returned measurement signal to calculate the corresponding distance observable;

[0104] Calculate the first clock difference between each satellite and its adjacent satellites based on the distance observables corresponding to each satellite.

[0105] According to the laser communication list, beam two-way orientation is carried out one by one from near to far for one or more satellites that each satellite needs to establish a link with itself. After the beam orientation is completed, the establishment of the inter-satellite laser link is carried out. Subsequent inter-satellite clock difference estimation is based on this laser link. Specifically, the process of measuring and determining the first clock difference between adjacent satellites is as follows:

[0106] (1) Satellite S i Carry out distance observation of two satellites by measuring the phase difference with the adjacent satellite S j The satellite first sends a measurement signal to the satellite. After receiving the measurement signal, it will carry the phase change amount caused by the distance and then forward it to the satellite, and then obtain the distance amount through mixing and phase difference measurement;

[0107] (2) Based on the distance observables, calculate the time difference between satellite S i and S j Suppose satellite S sends a measurement signal to the navigation satellite S i at time t0. This signal arrives at satellite S j at time t1 and is then reflected. S j receives the reflected signal at time t2. The first clock difference between satellite S i and S i and S j can be calculated through the following formula

[0108]

[0109] where, represents the time difference between when satellite S i sends the measurement signal and the second pulse provided by the atomic clock carried on it; represents the time difference between satellite S j and the second pulse provided by the atomic clock carried on it at time t1; τ represents the round-trip time of the laser measurement signal measured by satellite S i , that is, t2 - t0.

[0110] As an implementation manner of the present application, based on the first clock differences between adjacent satellites in the laser communication link, calculating the target clock difference between the target satellite and the reference satellite includes:

[0111] For a target satellite, determine the target path between the target satellite and the reference satellite based on the laser communication list;

[0112] Accumulate the first clock difference between adjacent satellites in the target path to determine the target clock difference between the target satellite and the reference satellite.

[0113] In this embodiment, based on the first clock difference between adjacent satellites in the target path, the target clock differences between each satellite and the reference satellite are indirectly reduced. Specifically, assume that the visible satellites of the reference satellite S 0 are S j , and the inter-satellite clock difference between the two is measured The clock difference information can be quickly synchronized to the satellite S 0 invisible to the reference satellite S i through the laser link. For the satellite S that cannot be directly observed to S 0 but can be directly observed to S j , its target clock difference from the reference satellite S i is indirectly calculated by the following formula: 0 where

[0114]

[0115] represents the first clock difference measured between satellite S and S i ; represents the first clock difference measured between satellite S i and S j ;

[0116] represents the target clock difference between satellite S j and S 0 .

[0117] In one embodiment, when clock difference estimation is required for a target satellite, based on the constructed laser communication link, a laser path between the target satellite and the reference satellite is determined as the target path. For example, the target path from the target satellite "03" to the reference satellite "02" is determined as "03 - 01 - 02"; the target path from the target satellite "01" to the reference satellite "02" is determined as "01 - 02". After determining the target path, two-way time comparison is performed between adjacent satellites involved in the target path, and the corresponding first clock difference is calculated. For example, the first clock difference of the "03 - 01" link and the first clock difference of the "01 - 02" link are calculated. Finally, after the inter-satellite clock differences between adjacent satellites involved in the target path are all calculated, the first clock differences between adjacent satellites in the target path are accumulated, so as to indirectly reduce the target clock difference between the target satellite and the reference satellite. For example, the target clock difference from the target satellite "03" to the reference satellite "02" is the sum of the first clock difference of the "03 - 01" link and the first clock difference of the "01 - 02" link.

[0117] In this embodiment, after determining the target path of the target satellite, the time two-way comparison is performed based on the adjacent satellites involved in the target path to obtain the first clock difference, which can ensure that the data in the satellite clock difference estimation process is more timely, thereby further improving the accuracy of the clock difference estimation of each satellite in the constellation system.

[0118] In one embodiment, after constructing the laser communication link, the time two-way comparison is pre-performed between each adjacent satellite in the constellation system, and the first clock differences corresponding to all adjacent satellites in the constellation system are calculated and stored. When the clock difference of any satellite needs to be estimated subsequently, first, a laser path between the target satellite and the reference satellite is determined from the laser communication network of the constellation system as the target path. For example, the target path from the target satellite "03" to the reference satellite "02" is determined as "03-01-02"; the target path from the target satellite "01" to the reference satellite "02" is determined as "01-02". Then, according to the adjacent satellites in the target path, one or more corresponding first clock differences stored are obtained (for example, the first clock difference of the "03-01" link and the first clock difference of the "01-02" link), and the first clock differences between each adjacent satellite in the target path are accumulated, so as to indirectly reduce and obtain the target clock difference between the target satellite and the reference satellite.

[0119] In this embodiment, since the inter-satellite clock differences between the adjacent satellites involved in the target path have been pre-calculated, when estimating the clock difference of the target satellite, the stored data can be directly read for calculation, further improving the efficiency of the clock difference estimation and realizing the fast clock calibration of the constellation system. Moreover, since the target paths between different satellites and the reference satellite in the constellation system may overlap, by pre-calculating and storing the first clock differences of the adjacent satellites in the system, when the target paths of different satellites overlap subsequently, there is no need to repeatedly calculate the first clock differences of the overlapping parts, saving a large amount of computing resources.

[0120] As an implementation manner of the present application, determining the target path between the target satellite and the reference satellite based on the laser communication list includes:

[0121] Judging whether the reference satellite is an adjacent satellite of the target satellite;

[0122] If the reference satellite is an adjacent satellite of the target satellite, the laser communication link between the target satellite and the reference satellite is determined as the target path;

[0123] If the reference satellite is not an adjacent satellite of the target satellite, the laser communication list is searched to obtain all the satellites that enable the target satellite to communicate with the reference satellite indirectly, and the corresponding candidate paths are determined; the candidate path with the smallest number of satellites is determined as the target path.

[0124] In one embodiment, there are multiple laser paths between the target satellite and the reference satellite, and one laser path needs to be determined as the target path therefrom. In addition, since the target satellite may be an adjacent satellite of the reference satellite, for an adjacent satellite of the reference satellite, its target clock offset is the first clock offset between the target satellite and the reference satellite. Therefore, in this embodiment, when determining the target path, it is first determined whether the target satellite is an adjacent satellite of the reference satellite. If it is an adjacent satellite of the reference satellite, the laser link between the target satellite and the reference satellite is selected as the target path.

[0125] Figure 5 is a schematic diagram of finding a candidate path in an embodiment of the present application. As Figure 5 shown, the target satellite "05" is an adjacent satellite of the reference satellite 02, so the laser link "05-02" is determined as the target path of the target satellite "05".

[0126] If it is not an adjacent satellite of the reference satellite, a laser path with the fewest number of satellites is found as the target path of the target satellite. Specifically, all adjacent satellites of the reference satellite and all adjacent satellites of the target satellite are found from the laser communication list, so that the target satellite is connected to the adjacent satellite of the reference satellite through itself or its adjacent satellites, thereby determining all candidate paths. Since the larger the number of satellites in the laser path, the relatively greater the error in clock offset estimation, in order to minimize the clock offset error as much as possible, this solution selects a path with the fewest number of satellites from all candidate paths as the target path, reducing the number of adjacent satellites in the target path to further improve the estimation accuracy.

[0127] As Figure 5 shown, there are two candidate paths from the target satellite "03" to the reference satellite "02", namely "03-01-02" and "03-06-04-02". The path "03-01-02" with the fewest number of satellites is selected as the target path.

[0128] Based on the same inventive concept, an embodiment of the present application provides a satellite autonomous clock offset estimation device. Refer to Figure 4 , Figure 4 is a schematic diagram of a satellite autonomous clock offset estimation device 100 proposed in an embodiment of the present application. The device is deployed in a navigation satellite constellation system, and the navigation satellite constellation system includes multiple high-orbit satellites deployed globally; wherein, each satellite is equipped with an atomic clock, and at least one satellite is equipped with an atomic clock with an accuracy not lower than the E-16 level. As Figure 4 shown, the device includes:

[0129] A link establishment module 101, configured to construct laser communication links between various satellites based on a laser communication list;

[0130] A calculation module 102, configured to determine any satellite equipped with an atomic clock with a precision not lower than the E-16 magnitude as a reference satellite; calculate a target clock difference between a target satellite and the reference satellite based on a first clock difference between adjacent satellites in the laser communication link; the target satellite is any satellite other than the reference satellite in the navigation satellite constellation system; the adjacent satellites communicate directly through the laser communication link.

[0131] As an implementation manner of the present application, the device further includes a planning module, configured to perform the following steps:

[0132] Obtain the coordinates, geocentric coordinates, height of the ionosphere, and equatorial radius of the earth of each satellite in the CGCS2000 coordinate system, and determine all visible satellites of each satellite; the communication link established between the satellite and the corresponding visible satellite is not affected by the ionosphere of the earth;

[0133] Sort all visible satellites of each satellite in ascending order of number to construct a visible list;

[0134] Traverse the visible lists of all satellites, and remove the numbers of satellites that have been traversed before from each visible list to complete the update of the visible list;

[0135] Construct the laser communication list based on all updated visible lists, and set the communication time periods of every two adjacent satellites in the laser communication list.

[0136] As an implementation manner of the present application, the planning module, configured to determine all visible satellites of each satellite, specifically includes:

[0137] Calculate the height of the ionosphere from the geocenter based on the equatorial radius of the earth and the height of the ionosphere;

[0138] For a target satellite, determine the height of the perpendicular intersection point of the line connecting the geocenter to the two satellites from the geocenter based on the coordinates of the target satellite, the coordinates of a candidate satellite, and the geocentric coordinates;

[0139] Compare the height of the perpendicular intersection point of the line connecting the geocenter to the two satellites from the geocenter with the height of the ionosphere from the geocenter. If the height of the perpendicular intersection point of the line connecting the geocenter to the two satellites from the geocenter is greater than the height of the ionosphere from the geocenter, determine that the candidate satellite is a visible satellite of the target satellite.

[0140] As an implementation manner of the present application, the device further includes a measurement module, configured to perform the following steps:

[0141] Each satellite sends a measurement signal to its adjacent satellites and receives the measurement signal carrying the phase change amount returned by the adjacent satellites;

[0142] Each satellite performs frequency mixing and phase difference measurement on the returned measurement signal to calculate the corresponding distance observable;

[0143] Based on the distance observables corresponding to each satellite, calculate the first clock difference between each satellite and its adjacent satellites.

[0144] As an implementation manner of the present application, the calculation module 102 is configured to calculate the target clock difference between the target satellite and the reference satellite based on the first clock differences between adjacent satellites in the laser communication link, specifically including:

[0145] For a target satellite, determine the target path between the target satellite and the reference satellite based on the laser communication list;

[0146] Accumulate the first clock differences between adjacent satellites in the target path to determine the target clock difference between the target satellite and the reference satellite.

[0147] As an implementation manner of the present application, the calculation module 101 is configured to determine the target path between the target satellite and the reference satellite based on the laser communication list, specifically including:

[0148] Judge whether the reference satellite is an adjacent satellite of the target satellite;

[0149] If the reference satellite is an adjacent satellite of the target satellite, determine the laser communication link between the target satellite and the reference satellite as the target path;

[0150] If the reference satellite is not an adjacent satellite of the target satellite, search the laser communication list to obtain all satellites that enable the target satellite to communicate indirectly with the reference satellite, and determine the corresponding candidate paths; determine the candidate path with the smallest number of satellites as the target path.

[0151] As an implementation manner of the present application, the device further includes a monitoring module, which is configured to detect all laser communication links at a first interval time based on the laser communication list to judge whether there is a disconnection; and judge whether adjacent satellites can see each other;

[0152] The planning module is further configured to re-determine the visible satellites of each satellite and re-construct the laser communication links between each satellite in the case of disconnection of any laser communication link or non-visibility of any two adjacent satellites.

[0153] Based on the same inventive concept, an embodiment of the present application provides a reference establishment method, which is applied to the navigation satellite constellation system in the above embodiment. Figure 6 is a flowchart of the reference establishment method proposed in an embodiment of the present application. As Figure 6 shown, the method includes:

[0154] S21: Execute the satellite autonomous clock offset estimation method provided in the above embodiment to obtain the target clock offset between the target satellite and the reference satellite in the navigation satellite constellation system; the target satellite is any satellite in the navigation satellite constellation system other than the reference satellite;

[0155] S22: Obtain the reference time output by the atomic clock carried by the reference satellite;

[0156] S23: Calibrate the atomic clock carried by the target satellite based on the reference time and the target clock offset.

[0157] In this embodiment, taking the high-precision atomic clock carried on the reference satellite in the navigation satellite constellation system as the time reference, the clock offset estimation method provided in the above embodiment is used to determine the target clock offset between each satellite in the constellation system and the reference satellite. Furthermore, synchronize to each satellite in the constellation system with the atomic clock on the reference satellite as the time reference for local calibration, so as to achieve the unification of the global constellation time.

[0158] Based on the same inventive concept, an embodiment of the present application provides a reference establishment device. Figure 7 is a schematic diagram of the reference establishment device 200 proposed in an embodiment of the present application. As Figure 7 shown, the device includes: the satellite autonomous clock offset estimation device 100 provided in the above embodiment, a time synchronization module 201, and a calibration module 202;

[0159] The time synchronization module 201 is configured to obtain the reference time output by the atomic clock carried by the reference satellite;

[0160] The calibration module 202 is configured to calibrate the atomic clock carried by the target satellite based on the reference time and the target clock offset.

[0161] Based on the same inventive concept, an embodiment of the present application provides a readable storage medium, on which a computer program is stored, and when the computer program is executed by a processor, it implements the steps in the satellite autonomous clock offset estimation method described in any of the above embodiments of the present application.

[0162] Based on the same inventive concept, an embodiment of the present application provides an electronic device, refer to Figure 8 , Figure 8It is a schematic diagram of an electronic device proposed in an embodiment of the present application. The electronic device includes a memory, a processor, and a computer program stored on the memory and executable on the processor. When the computer program is executed by the processor, it implements the steps in the satellite autonomous clock error estimation method described in any of the above embodiments of the present application.

[0163] Regarding the device in the above embodiment, the specific manner in which each module performs operations has been described in detail in the embodiment related to the method, and will not be elaborated here.

[0164] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

[0165] For the method embodiments, for simplicity of description, they are all expressed as a series of action combinations. However, those skilled in the art should know that the present application is not limited by the described action sequence, because according to the present application, certain steps can be performed in other sequences or simultaneously. Secondly, those skilled in the art should also know that the embodiments described in the specification are all preferred embodiments, and the actions and components involved are not necessarily essential to the present application.

[0166] Those skilled in the art should understand that the embodiments of the present application can be provided as a method, a device, or a computer program product. Therefore, the embodiments of the present application can take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware aspects. Moreover, the embodiments of the present application can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk memories, CD-ROMs, optical memories, etc.) containing computer-usable program codes.

[0167] The embodiments of the present application are described with reference to the flowcharts and / or block diagrams of methods, terminal devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each flow and / or block in the flowchart and / or block diagram, as well as the combination of flows and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to the processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing terminal devices to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing terminal devices generate a device for implementing the functions specified in Figure 1 one flow or multiple flows and / or blocks Figure 1 one block or multiple blocks.

[0168] These computer program instructions can also be stored in a computer-readable memory that can direct a computer or other programmable data processing terminal device to work in a specific manner, such that the instructions stored in the computer-readable memory produce a manufacture including an instruction device that implements the functions specified in one process Figure 1 one process or multiple processes and / or blocks Figure 1 one block or multiple blocks.

[0169] These computer program instructions can also be loaded onto a computer or other programmable data processing terminal device, such that a series of operational steps are performed on the computer or other programmable terminal device to produce a computer-implemented process, and thus the instructions executed on the computer or other programmable terminal device provide steps for implementing the functions specified in one process Figure 1 one process or multiple processes and / or blocks Figure 1 one block or multiple blocks.

[0170] Although the preferred embodiments of the embodiments of the present application have been described, those skilled in the art can make additional changes and modifications once they learn the basic creative concepts. Therefore, the present application is construed to include the preferred embodiments and all changes and modifications that fall within the scope of the embodiments of the present application.

[0171] Finally, it should also be noted that in this text, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, such that a process, method, article or terminal device comprising a series of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article or terminal device. Without further limitation, an element defined by the statement "comprising an..." does not exclude the presence of additional identical elements in the process, method, article or terminal device comprising the element.

[0172] The satellite autonomous clock offset estimation method, reference establishment method, device and product provided by the present application have been introduced in detail above. Specific examples are used in this text to elaborate on the principle and implementation manner of the present application. The description of the above embodiments is only used to help understand the method and its core idea of the present application; at the same time, for those of ordinary skill in the art, according to the idea of the present application, there will be changes in the specific implementation manner and application scope. In summary, the content of this specification should not be construed as a limitation to the present application.

Claims

1. A satellite autonomous clock offset estimation method, characterized in that Applied to a navigation satellite constellation system, the navigation satellite constellation system includes multiple high-orbit satellites deployed globally; wherein, each satellite is equipped with an atomic clock, and at least one satellite is equipped with an atomic clock with an accuracy not lower than the E-16 level; the method includes: Based on the laser communication list, construct laser communication links between each satellite. Determine a satellite equipped with an atomic clock with an accuracy not lower than the E-16 level as a reference satellite; based on the first clock difference between adjacent satellites in the laser communication link, calculate the target clock difference between the target satellite and the reference satellite; the target satellite is any satellite other than the reference satellite in the navigation satellite constellation system; the adjacent satellites communicate directly through the laser communication link.

2. The satellite autonomous clock error estimation method according to claim 1, wherein Before constructing the laser communication links between each satellite based on the laser communication list, it further includes: Obtain the coordinates of each satellite, the geocentric coordinates, the height of the ionosphere, and the equatorial radius of the earth in the CGCS2000 coordinate system, and determine all visible satellites of each satellite; the communication link constructed between the satellite and the corresponding visible satellite is not affected by the ionosphere of the earth. Sort all visible satellites of each satellite in ascending order of their numbers to construct a visible list. Traverse the visible lists of all satellites, and remove the numbers of the satellites that have been traversed before from each visible list to complete the update of the visible list. Construct the laser communication list based on all updated visible lists, and set the communication time periods between every two adjacent satellites in the laser communication list.

3. The satellite autonomous clock error estimation method according to claim 2, characterized in that, Determine all visible satellites of each satellite, including: Based on the equatorial radius of the earth and the height of the ionosphere, calculate the height of the ionosphere from the geocenter. For a target satellite, based on the coordinates of the target satellite, the coordinates of a candidate satellite, and the geocentric coordinates, determine the height of the perpendicular intersection point of the line connecting the geocenter to the two satellites from the geocenter. Compare the height of the perpendicular intersection point from the geocenter with the height of the ionosphere from the geocenter. When the height of the perpendicular intersection point from the geocenter is greater than the height of the ionosphere from the geocenter, determine that the candidate satellite is a visible satellite of the target satellite.

4. The satellite autonomous clock offset estimation method according to claim 1, wherein, It further includes: Each satellite sends a measurement signal to its adjacent satellite and receives the measurement signal carrying the phase change amount returned by the adjacent satellite. Each satellite performs mixing and phase difference measurement on the returned measurement signal to calculate the corresponding distance observable. Based on the distance observables corresponding to each satellite, calculate the first clock difference between each satellite and its adjacent satellite.

5. The satellite autonomous clock offset estimation method according to claim 1, characterized in that Based on the first clock difference between adjacent satellites in the laser communication link, calculating the target clock difference between the target satellite and the reference satellite includes: For a target satellite, determine the target path between the target satellite and the reference satellite based on the laser communication list. Accumulate the first clock differences between adjacent satellites in the target path to determine the target clock difference between the target satellite and the reference satellite.

6. The satellite autonomous clock error estimation method according to claim 5, characterized in that Determining a target path between the target satellite and the reference satellite based on the laser communication list includes: Judging whether the reference satellite is an adjacent satellite of the target satellite; If the reference satellite is an adjacent satellite of the target satellite, determining the laser communication link between the target satellite and the reference satellite as the target path; If the reference satellite is not an adjacent satellite of the target satellite, searching the laser communication list to obtain all satellites that enable the target satellite to communicate with the reference satellite indirectly, and determining corresponding candidate paths; determining the candidate path with the smallest number of satellites as the target path.

7. The satellite autonomous clock offset estimation method according to any one of claims 2-6, characterized in that After constructing the laser communication links between the satellites, it further includes: Based on the laser communication list, detecting all laser communication links at a first interval time to judge whether there is a disconnection; and judging whether adjacent satellites are visible to each other; In the case where any laser communication link is disconnected or any two adjacent satellites are not visible to each other, re-determining the visible satellites of each satellite and reconstructing the laser communication links between the satellites.

8. A satellite autonomous clock error estimation device, characterized in that Deployed in a navigation satellite constellation system, the navigation satellite constellation system includes multiple high-orbit satellites deployed globally; wherein, each satellite is equipped with an atomic clock, and at least one satellite is equipped with an atomic clock with an accuracy not lower than the E-16 level; the device is used to execute the method according to any one of claims 1-7, including: A link establishment module, configured to construct laser communication links between the satellites based on the laser communication list; A calculation module, configured to determine a satellite equipped with an atomic clock with an accuracy not lower than the E-16 level as the reference satellite; calculating a target clock difference between the target satellite and the reference satellite based on the first clock difference between adjacent satellites in the laser communication link; the target satellite is any satellite in the navigation satellite constellation system other than the reference satellite; the adjacent satellites communicate directly through the laser communication link.

9. A method for establishing a reference, characterized in that, Applied to the navigation satellite constellation system according to any one of claims 1-7; the method includes: Executing the method according to any one of claims 1-7 to obtain the target clock difference between the target satellite and the reference satellite in the navigation satellite constellation system; the target satellite is any satellite in the navigation satellite constellation system other than the reference satellite; Obtaining the reference time output by the atomic clock carried by the reference satellite; Calibrating the atomic clock carried by the target satellite based on the reference time and the target clock difference.

10. A reference establishing device, characterized in that, For implementing the method according to claim 9, including: the satellite autonomous clock difference estimation device, time synchronization module and calibration module according to claim 8; The time synchronization module is configured to obtain the reference time output by the atomic clock carried by the reference satellite; The calibration module is configured to calibrate the atomic clock carried by the target satellite based on the reference time and the target clock difference.

11. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, it implements the steps in the method according to any one of claims 1-7 or the method according to claim 9.

12. An electronic device, comprising a memory, a processor, and a computer program stored on the memory and executable on the processor, characterized in that, When the processor executes the computer program, the steps in the method according to any one of claims 1 to 7 or the method according to claim 9 are implemented.

Images