CN110289903B - Satellite network autonomous time synchronization method and system based on link measurement - Google Patents

Satellite network autonomous time synchronization method and system based on link measurement Download PDF

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CN110289903B
CN110289903B CN201910566081.4A CN201910566081A CN110289903B CN 110289903 B CN110289903 B CN 110289903B CN 201910566081 A CN201910566081 A CN 201910566081A CN 110289903 B CN110289903 B CN 110289903B
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time service
satellite
synchronized
communication
synchronization
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CN110289903A (en
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陈曦
殷柳国
魏齐辉
匡麟玲
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Shanghai Qingshen Technology Development Co ltd
Tsinghua University
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Shanghai Qingshen Technology Development Co ltd
Tsinghua University
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S19/00—Satellite radio beacon positioning systems; Determining position, velocity or attitude using signals transmitted by such systems
    • G01S19/01—Satellite radio beacon positioning systems transmitting time-stamped messages, e.g. GPS [Global Positioning System], GLONASS [Global Orbiting Navigation Satellite System] or GALILEO
    • G01S19/13—Receivers
    • G01S19/20—Integrity monitoring, fault detection or fault isolation of space segment
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S19/00—Satellite radio beacon positioning systems; Determining position, velocity or attitude using signals transmitted by such systems
    • G01S19/01—Satellite radio beacon positioning systems transmitting time-stamped messages, e.g. GPS [Global Positioning System], GLONASS [Global Orbiting Navigation Satellite System] or GALILEO
    • G01S19/13—Receivers
    • G01S19/23—Testing, monitoring, correcting or calibrating of receiver elements
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B7/00—Radio transmission systems, i.e. using radiation field
    • H04B7/14—Relay systems
    • H04B7/15—Active relay systems
    • H04B7/185—Space-based or airborne stations; Stations for satellite systems
    • H04B7/1851—Systems using a satellite or space-based relay
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04J—MULTIPLEX COMMUNICATION
    • H04J3/00—Time-division multiplex systems
    • H04J3/02—Details
    • H04J3/06—Synchronising arrangements
    • H04J3/0635—Clock or time synchronisation in a network
    • H04J3/0638—Clock or time synchronisation among nodes; Internode synchronisation

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Remote Sensing (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Signal Processing (AREA)
  • Astronomy & Astrophysics (AREA)
  • Aviation & Aerospace Engineering (AREA)
  • Computer Security & Cryptography (AREA)
  • Synchronisation In Digital Transmission Systems (AREA)

Abstract

The invention provides a satellite network autonomous time synchronization method and a system based on link measurement, comprising the following steps: acquiring link connection information between a communication satellite to be synchronized and a plurality of time service nodes, wherein the plurality of time service nodes are nodes in a first satellite communication network; judging whether links exist between the communication satellite to be synchronized and the plurality of time service nodes or not based on the link connection information; if so, selecting a first time service node from the plurality of time service nodes, wherein the first time service node is the time service node with the highest first synchronization level information in the plurality of time service nodes, and the first synchronization level information is information which is determined by the first satellite communication network in advance according to the link connection relationship between the plurality of time service nodes and the time service master gateway station in the first satellite communication network and is used for representing the link connection relationship between the time service nodes and the time service master gateway station; and carrying out time service synchronous operation on the communication satellite to be synchronized by utilizing the first time service node. The dependence of satellite time service on a satellite navigation system is reduced.

Description

Satellite network autonomous time synchronization method and system based on link measurement
Technical Field
The invention relates to the technical field of satellite navigation time service, in particular to a satellite network autonomous time synchronization method and system based on link measurement.
Background
Spatio-temporal references are an important foundation for modern satellite networks.
In a satellite communication network system including a plurality of communication satellites, beam alignment and slot alignment between the satellites and ground terminals are generally performed until the satellites know positional information of each other and acquire high-precision mutual time synchronization, thereby improving communication efficiency to the maximum.
A basic mode for obtaining the space-time reference by the modern satellite network is to adopt a satellite navigation receiver, so that not only can ground and low-orbit communication satellites adopt the satellite navigation receiver to obtain the space-time reference, but also medium and high-orbit satellites can use a satellite-borne navigation receiver to perform positioning time service. However, this method is too dependent on the satellite navigation system, so that the communication satellite cannot be timed under the condition that the satellite navigation receiver cannot establish a connection with the ground gateway station.
Disclosure of Invention
In view of the above, an object of the present invention is to provide a method and a system for autonomous time synchronization of a satellite network based on link measurement, which can still perform time service operation on a communication satellite when a satellite-borne navigation receiver cannot establish a connection with a ground gateway station in a process of obtaining a space-time reference in a satellite communication network.
In a first aspect, an embodiment of the present invention provides a method for autonomous time synchronization of a satellite network based on link measurement, including: acquiring link connection information between a communication satellite to be synchronized and a plurality of time service nodes, wherein the plurality of time service nodes are nodes in a first satellite communication network, and the plurality of time service nodes comprise at least one of the following: gateway stations, communication satellites, user terminals; judging whether links exist between the communication satellite to be synchronized and the plurality of time service nodes or not based on the link connection information; if so, selecting a first time service node from the plurality of time service nodes, wherein the first time service node is a time service node with the highest first synchronization level information in the plurality of time service nodes, and the first synchronization level information is information which is determined by the first satellite communication network in advance according to the link connection relationship between the plurality of time service nodes and a time service master gateway station in the first satellite communication network and is used for representing the link connection relationship between the time service node and the time service master gateway station; and carrying out time service synchronization operation on the communication satellite to be synchronized by utilizing the first time service node.
Further, the method further comprises: if the fact that no link exists between the communication satellite to be synchronized and the plurality of time service nodes is judged, marking the communication satellite to be synchronized as a second time service node; and if the number of the satellites marked as the second time service nodes in the historical communication satellites to be synchronized is judged to be multiple, time service synchronization operation between the communication satellites to be synchronized and a second satellite communication network is achieved, wherein the second satellite communication network is a communication network formed by target historical communication satellites marked as the second time service nodes in the historical communication satellites to be synchronized.
Further, the method further comprises: the first satellite communication network determines first synchronization level information of the time service node based on a link connection relation between the time service node in the first satellite communication network and the time service master gateway station.
Further, the determining, by the first satellite communication network, the first synchronization level information of the time service node based on the link connection relationship between the time service node in the first satellite communication network and the time service master gateway station includes: dividing the link connection relation between each time service node in the first satellite communication network and the time service master gateway station into a plurality of first synchronization levels; setting corresponding identification information for each first synchronization level; and determining the identification information as first synchronization level information of the corresponding time service node.
Further, the implementation of the time service synchronization operation between the communication satellite to be synchronized and the second satellite communication network includes: acquiring clock statistical characteristics of the target historical communication satellite to be synchronized, wherein the clock statistical characteristics are used for representing the stability and the frequency deviation of a communication satellite load clock; determining a second synchronization level of the target historical satellite to be synchronized based on the clock statistical characteristics; if the second synchronization levels of the target historical communication satellites to be synchronized are different, selecting a third time service node in the second satellite communication network; the third time service node is a target historical communication satellite to be synchronized with the highest second synchronization level in the second satellite communication network; and carrying out time service synchronization operation on the communication satellite to be synchronized by utilizing the third time service node.
Further, if the second synchronization levels between the target historical communication satellites to be synchronized are the same, the method further includes: determining a third synchronization level of the target historical communication satellite to be synchronized by using a random number generation method; selecting a fourth time service node in the second satellite communication network; the fourth time service node is a target historical communication satellite to be synchronized with the highest third synchronization level in the second satellite communication network; and carrying out time service synchronization operation on the communication satellite to be synchronized by utilizing the fourth time service node.
Further, the acquiring the clock statistical characteristics of the target historical communication satellite to be synchronized comprises: comparing the local clock of the target historical satellite to be synchronized with an external clock reference to obtain a clock error, wherein the external clock reference comprises: second pulse output by the satellite navigation receiver; and calculating the variance and the mean of the clock errors, and taking the variance and the mean as the clock statistical characteristics of the target historical satellites to be synchronized.
Further, determining a second synchronization level for the target historical communications satellite to be synchronized based on the clock statistics comprises: determining a target value based on the mean and the variance, wherein the mean is a high-order value of the target value and the variance is a low-order value of the target value; and determining the target value as a second synchronization level of the target historical satellite to be synchronized.
In a second aspect, an embodiment of the present invention further provides a satellite network autonomous time synchronization system based on link measurement, including: the acquisition module is used for acquiring link connection information between a communication satellite to be synchronized and a plurality of time service nodes, wherein the plurality of time service nodes are nodes in a first satellite communication network, and the plurality of time service nodes comprise at least one of the following: gateway stations, communication satellites, user terminals; the link judgment module is used for judging whether links exist between the communication satellite to be synchronized and the plurality of time service nodes or not based on the link connection information; the first time service module is used for selecting a first time service node from the plurality of time service nodes if links exist between the communication satellite to be synchronized and the plurality of time service nodes, wherein the first time service node is a time service node with the highest first synchronization level information in the plurality of time service nodes, and the first synchronization level information is information which is determined by the first satellite communication network in advance according to the link connection relation between the plurality of time service nodes and a time service master gateway station in the first satellite communication network and is used for representing the link connection relation between the time service node and the time service master gateway station; the first time service module is further used for carrying out time service synchronization operation on the communication satellite to be synchronized by utilizing the first time service node.
Further, the system further comprises: the second time service module is used for marking the communication satellite to be synchronized as a second time service node if judging that no link exists between the communication satellite to be synchronized and the plurality of time service nodes; and if the number of the satellites marked as the second time service nodes in the historical communication satellites to be synchronized is judged to be multiple, time service synchronization operation between the communication satellites to be synchronized and a second satellite communication network is achieved, wherein the second satellite communication network is a communication network formed by target historical communication satellites marked as the second time service nodes in the historical communication satellites to be synchronized.
In the embodiment of the invention, link connection information between a communication satellite to be synchronized and a plurality of time service nodes is acquired, wherein the plurality of time service nodes are nodes in a first satellite communication network; judging whether links exist between the communication satellite to be synchronized and the plurality of time service nodes or not based on the link connection information; if so, selecting a first time service node from the plurality of time service nodes, wherein the first time service node is the time service node with the highest first synchronization level information in the plurality of time service nodes, and the first synchronization level information is information which is determined by the first satellite communication network in advance according to the link connection relationship between the plurality of time service nodes and the time service master gateway station in the first satellite communication network and is used for representing the link connection relationship between the time service nodes and the time service master gateway station; by utilizing the mode that the first time service node performs time service synchronous operation on the communication satellite to be synchronized, the technical effect that the communication satellite can still be subjected to time service operation under the condition that the satellite-borne navigation receiver cannot be connected with the ground gateway station in the process that the satellite communication network obtains the time-space reference is achieved.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
In order to make the aforementioned and other objects, features and advantages of the present invention comprehensible, preferred embodiments accompanied with figures are described in detail below.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.
Fig. 1 is a flowchart of a method for autonomous time synchronization of a satellite network based on link measurement according to an embodiment of the present invention;
fig. 2 is a flowchart of another autonomous time synchronization method for a satellite network based on link measurement according to an embodiment of the present invention;
fig. 3 is a flowchart of a method for determining first synchronization level information of a time service node according to an embodiment of the present invention;
fig. 4 is a schematic diagram of a first satellite communication network after implementing hierarchical time synchronization according to an embodiment of the present invention;
FIG. 5 is a schematic diagram illustrating a general principle of bidirectional contrast time service according to an embodiment of the present invention;
fig. 6 is a schematic diagram of a satellite network autonomous time synchronization system based on link measurement according to an embodiment of the present invention.
Detailed Description
To make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings, and it is apparent that the described embodiments are some, but not all embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of description and simplicity of description, but do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.
In addition, in the description of the embodiments of the present invention, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.
The first embodiment is as follows:
in accordance with an embodiment of the present invention, there is provided an embodiment of a method for autonomous time synchronization of a satellite network based on link measurements, it is noted that the steps illustrated in the flowchart of the accompanying drawings may be performed in a computer system such as a set of computer-executable instructions and that, although a logical order is illustrated in the flowchart, in some cases the steps illustrated or described may be performed in an order different than here.
Fig. 1 is a flowchart of a method for autonomous time synchronization of a satellite network based on link measurement according to an embodiment of the present invention, as shown in fig. 1, the method includes the following steps:
step S102, obtaining link connection information between a communication satellite to be synchronized and a plurality of time service nodes, wherein the plurality of time service nodes are nodes in a first satellite communication network, and the plurality of time service nodes comprise at least one of the following: gateway stations, communication satellites, user terminals.
Optionally, the first satellite communication network is a satellite communication network composed of M gateway stations, N communication satellites, and a plurality of user terminals, where M and N are positive integers greater than or equal to 1.
And step S104, judging whether links exist between the communication satellite to be synchronized and the plurality of time service nodes based on the link connection information.
And step S106, if so, selecting a first time service node from the plurality of time service nodes, wherein the first time service node is the time service node with the highest first synchronization level information in the plurality of time service nodes, and the first synchronization level information is information which is determined by the first satellite communication network in advance according to the link connection relationship between the plurality of time service nodes and the time service master gateway station and is used for representing the link connection relationship between the time service nodes and the time service master gateway station.
And S108, performing time service synchronization operation on the communication satellite to be synchronized by utilizing the first time service node.
Optionally, the communication satellite to be synchronized realizes time synchronization with the first time service node through bidirectional comparison time service.
In the embodiment of the invention, link connection information between a communication satellite to be synchronized and a plurality of time service nodes is acquired, wherein the plurality of time service nodes are nodes in a first satellite communication network; judging whether links exist between the communication satellite to be synchronized and the plurality of time service nodes or not based on the link connection information; if so, selecting a first time service node from the plurality of time service nodes, wherein the first time service node is the time service node with the highest first synchronization level information in the plurality of time service nodes, and the first synchronization level information is information which is determined by the first satellite communication network in advance according to the link connection relationship between the plurality of time service nodes and the time service master gateway station in the first satellite communication network and is used for representing the link connection relationship between the time service nodes and the time service master gateway station; by utilizing the mode that the first time service node performs time service synchronous operation on the communication satellite to be synchronized, the technical effect that the communication satellite can still be subjected to time service operation under the condition that the satellite-borne navigation receiver cannot be connected with the ground gateway station in the process that the satellite communication network obtains the time-space reference is achieved.
Optionally, as shown in fig. 2, the method provided in the embodiment of the present invention further includes:
step S110, if judging that no link exists between the communication satellite to be synchronized and the plurality of time service nodes, marking the communication satellite to be synchronized as a second time service node;
step S112, if the number of the satellites marked as the second time service nodes in the historical communication satellites to be synchronized is judged to be multiple, time service synchronization operation between the communication satellites to be synchronized and a second satellite communication network is achieved, wherein the second satellite communication network is a communication network formed by target historical communication satellites marked as the second time service nodes in the historical communication satellites to be synchronized.
Optionally, the communication satellite to be synchronized realizes time synchronization with the second satellite communication network through bidirectional comparison time service.
In the embodiment of the invention, links among a plurality of time service nodes in the first satellite communication network have bidirectional distance measurement and comparison time service functions, and the method for realizing hierarchical time synchronization can be realized by depending on the bidirectional distance measurement and comparison time service functions. Optionally, the method of hierarchical time synchronization comprises: the first satellite communication network determines first synchronization level information of the time service node based on a link connection relation between the time service node and a time service master gateway station in the first satellite communication network.
Specifically, as shown in fig. 3, the process of determining, by the first satellite communication network, the first synchronization level information of the time service node based on the link connection relationship between the time service node and the time service master gateway station in the first satellite communication network includes the following steps:
step S301, dividing the link connection relation between each time service node and the time service master gateway station in the first satellite communication network into a plurality of first synchronization levels.
Step S302, corresponding identification information is set for each first synchronization level.
Step S303, the identification information is determined as the first synchronization level information of the corresponding time service node.
Optionally, in step S112, a time service synchronization operation between the communication satellite to be synchronized and the second satellite communication network is implemented, which specifically includes the following steps:
step S1121, acquiring clock statistical characteristics of the target historical communication satellite to be synchronized, wherein the clock statistical characteristics are used for representing the stability and the frequency deviation of the communication satellite load clock.
Specifically, the local clock of the target historical satellite to be synchronized is compared with an external clock reference to obtain a clock error. Wherein the external clock reference comprises at least one of: the second pulse output by the satellite navigation receiver is synchronized to the clock of the time service node with higher synchronization level through bidirectional comparison time service.
And calculating the variance and the mean of the clock errors, and taking the variance and the mean as the clock statistical characteristics of the target historical satellites to be synchronized.
Specifically, after the load is powered on, the communication satellite compares the local clock with an external clock reference to obtain a clock error characteristic. The external clock reference may be a pulse per second output by the satellite navigation receiver or a clock of a time service node with a higher synchronization level when the time service is synchronized to a time service node with a higher synchronization level by bidirectional comparison. The communication satellite can obtain a time difference at each synchronization, or the time difference is the difference with the second pulse, or the synchronous time difference is obtained by time two-way comparison time service. The variance and mean of the time difference reflect the stability and frequency deviation of the communication satellite payload clock. Obviously, the smaller the variance and mean of the time difference, the higher the second synchronization level should be for the node. Therefore, one method of setting the second sync level is to set the second sync level to have a high order as the mean and a low order as the natural number of the variance.
Step S1122, a second synchronization level of the target historical satellite to be synchronized is determined based on the clock statistical characteristics.
Specifically, the target value is determined based on a mean value and a variance, wherein the mean value is a high-order value of the target value and the variance is a low-order value of the target value. And determining the target value as a second synchronization level of the target historical satellite to be synchronized.
Step S1123, judging whether the second synchronization levels of the target historical communication satellites to be synchronized are the same, if so, executing step S1124; if the same, step S1125 and step S1126 are executed.
Step S1124, selecting a third time service node in the second satellite communication network; the third time service node is a target history to-be-synchronized communication satellite with the highest second synchronization level in the second satellite communication network; and carrying out time service synchronous operation on the communication satellite to be synchronized by utilizing the third time service node. Optionally, when comparing the level of the second synchronization level, it is specified that the smaller the target value corresponding to the second synchronization level is, the higher the second synchronization level is.
Optionally, the communication satellite to be synchronized realizes time synchronization with the third time service node through bidirectional comparison time service.
Step S1125, a third synchronization level of the target historical communication satellite to be synchronized is determined by using a random number generation method. Specifically, a corresponding random number is generated for each target history communication satellite to be synchronized, wherein the random numbers corresponding to each target history communication satellite to be synchronized are different, and the generated random number is used as a third synchronization level of the target history communication satellite to be synchronized.
Step S1126, selecting a fourth time service node in the second satellite communication network; the fourth time service node is a target history to-be-synchronized communication satellite with the highest third synchronization level in the second satellite communication network; and carrying out time service synchronous operation on the communication satellite to be synchronized by utilizing the fourth time service node. Alternatively, when comparing the third synchronization level, it is specified that the smaller the random number corresponding to the third synchronization level, the higher the third synchronization level.
Optionally, the communication satellite to be synchronized realizes time synchronization with the fourth time service node through bidirectional comparison time service.
The autonomous time synchronization method for a satellite network based on link measurement according to the embodiment of the present invention is illustrated below. For example, fig. 4 is a schematic diagram of a first satellite communication network after implementing hierarchical time synchronization according to an embodiment of the present invention. As shown in fig. 4, dividing the link connection relationship between each time service node and the time service master gateway station in the first satellite communication network into a plurality of master synchronization levels (i.e. first synchronization level information), further comprises the following steps:
step S401, setting the synchronization level of a time service node in a first satellite communication network as a primary synchronization level (namely, first synchronization level information); a sub-synchronization level (i.e., second synchronization level information); third sync level } combination; one gateway station is selected as a time service master gateway station, the master synchronization level identification information is set to be 0 for the time service master gateway station, and the master synchronization level of the time service master gateway station is 0, namely the master synchronization level 0 in fig. 4. Optionally, the level 0 primary synchronization level is the highest primary synchronization level.
Step S402, the communication satellite communicating with the time service master gateway station synchronizes to the time service master gateway station by comparing the time service in two directions, and marks the master synchronization level identification information of the communication satellite communicating with the time service master gateway station as level 1, namely, master synchronization level 1 in FIG. 4.
Step S403, when the communication satellite to be synchronized and a plurality of known master synchronization level time service nodes have links and can perform synchronization through time service comparison, selecting the time service node with the highest master synchronization level to perform time service synchronization operation, and marking the communication satellite to be synchronized as an x +1 level master synchronization time service node according to the master synchronization level x of the time service node with the highest master synchronization level, wherein x is an integer greater than or equal to 0.
When comparing the master synchronization level, it is specified that the synchronization level of the master synchronization level x is higher than the synchronization level of the master synchronization level x + 1.
And S404, when the communication satellite to be synchronized can not be synchronized with any other time service node, marking the communication satellite to be synchronized as an M + N-level primary synchronization level time service node, and mutually synchronizing a plurality of M + N-level primary synchronization level time service nodes.
It should be noted that, the situation that the communication satellite to be synchronized cannot be synchronized with any other time service node occurs when all ground stations (i.e. gateway stations) are unavailable.
As can be seen from the above description, the autonomous time synchronization method for a satellite network based on link measurement according to the embodiment of the present invention solves the technical problem of time service synchronization of a communication satellite to be synchronized under the condition that link connections cannot be established between the communication satellite and all ground gateway stations by establishing a hierarchical synchronization level.
As shown in fig. 4, the method provided in the embodiment of the present invention further includes: the user terminal and the overhead communication satellite realize time synchronization with the communication satellite through bidirectional comparison time service so as to meet the requirements of a communication system.
Fig. 5 is a schematic diagram illustrating a general principle of bidirectional comparison time service according to an embodiment of the present invention. Bidirectional contrast time service is a common technology in a satellite network, and here, bidirectional contrast time service between a ground terminal and a communication satellite is taken as an example. Where the ground terminal represents a low priority synchronization source that needs to be in time with a high priority synchronization source, the communication satellite.
In the measurement process, the ground terminal sends a measurement request to the communication satellite, the communication satellite sends a measurement response after receiving the measurement request Dt2, the measurement response comprises Dt2, satellite time Ts and on-board time Ts of the starting time when the communication satellite receives the measurement request, and the ground terminal receives the measurement response at the ground time Tg. The ground terminal can obtain the following information after receiving the measurement response:
distance d between the star and the earthsg：
dsg(Dt4+ Dt1-Dt2) C/2, where C is the speed of light;
satellite-to-ground time difference Te:
Te＝Tg-(Ts+(Dt4+Dt1+Dt2)/2)。
after the ground terminal obtains the satellite-ground time difference, the ground terminal calibrates the time of the ground terminal and synchronizes with the satellite time as much as possible. During the measurement process, the communication satellite is in constant motion. The motion of the communication satellite may cause path asymmetry in the two-way comparison timing, i.e., the disparity between Dt1 and Dt3 in fig. 5. Dt1-Dt3 reflect the relative motion of the communication satellite and the ground terminal during the measured Dt3 time. Under the condition that the ground equipment does not move, the initial speed of the relative movement of the part can be calculated by the number of the tracks to be accurate to centimeter, therefore, the influence of the part can be effectively calculated, and the influence on the error of the final measurement is small. If the uplink and downlink adopt different frequencies, the influence of an ionized layer also exists, and a special correction formula is also provided. The specific method of bidirectional contrast timing varies in different implementations, but the basic principle does not change.
As can be seen from the above description, in the embodiment of the present invention, link connection information between a communication satellite to be synchronized and a plurality of time service nodes is obtained, where the plurality of time service nodes are nodes in a first satellite communication network; judging whether links exist between the communication satellite to be synchronized and the plurality of time service nodes or not based on the link connection information; if so, selecting a first time service node from the plurality of time service nodes, wherein the first time service node is the time service node with the highest first synchronization level information in the plurality of time service nodes, and the first synchronization level information is information which is determined by the first satellite communication network in advance according to the link connection relationship between the plurality of time service nodes and the time service master gateway station in the first satellite communication network and is used for representing the link connection relationship between the time service nodes and the time service master gateway station; by utilizing the mode that the first time service node performs time service synchronous operation on the communication satellite to be synchronized, the technical effect that the communication satellite can still be subjected to time service operation under the condition that the satellite-borne navigation receiver cannot be connected with the ground gateway station in the process that the satellite communication network obtains the time-space reference is achieved.
Example two:
the embodiment of the invention also provides a satellite network autonomous time synchronization system based on link measurement, which is mainly used for executing the satellite network autonomous time synchronization method based on link measurement provided by the embodiment of the invention, and the following specifically introduces the satellite network autonomous time synchronization system based on link measurement provided by the embodiment of the invention.
Fig. 6 is a schematic diagram of a satellite network autonomous time synchronization system based on link measurement according to an embodiment of the present invention, as shown in fig. 6, the system mainly includes: the system comprises an acquisition module 10, a link judgment module 20 and a first time service module 30.
Specifically, the obtaining module 10 is configured to obtain link connection information between a communication satellite to be synchronized and a plurality of time service nodes, where the plurality of time service nodes are nodes in a first satellite communication network, and the plurality of time service nodes include at least one of the following: gateway stations, communication satellites, user terminals.
And the link judgment module 20 is configured to judge whether links exist between the communication satellite to be synchronized and the multiple time service nodes based on the link connection information.
The first time service module 30 is configured to select a first time service node from the multiple time service nodes if links exist between the communication satellite to be synchronized and the multiple time service nodes, where the first time service node is a time service node with the highest first synchronization level information among the multiple time service nodes, and the first synchronization level information is information that is determined by the first satellite communication network in advance according to link connection relationships between the multiple time service nodes and a time service master gateway station in the first satellite communication network and is used for representing a link connection relationship between the time service node and the time service master gateway station.
The first time service module 30 is further configured to perform time service synchronization operation on the communication satellite to be synchronized by using the first time service node.
As shown in fig. 6, the system provided in the embodiment of the present invention further includes: a second time service module 40, configured to:
if the fact that no link exists between the communication satellite to be synchronized and the plurality of time service nodes is judged, the communication satellite to be synchronized is marked as a second time service node;
and if the number of the satellites marked as the second time service nodes in the historical communication satellites to be synchronized is judged to be multiple, time service synchronization operation between the communication satellites to be synchronized and a second satellite communication network is achieved, wherein the second satellite communication network is a communication network formed by target historical communication satellites marked as the second time service nodes in the historical communication satellites to be synchronized.
It is clear to those skilled in the art that, for convenience and brevity of description, the specific working processes of the system and the apparatus described above may refer to the corresponding processes in the foregoing method embodiments, and are not described herein again.
Unless specifically stated otherwise, the relative steps, numerical expressions, and values of the components and steps set forth in these embodiments do not limit the scope of the present invention.
The flowchart and block diagrams in the figures illustrate the architecture, functionality, and operation of possible implementations of systems, methods and computer program products according to various embodiments of the present invention. In this regard, each block in the flowchart or block diagrams may represent a module, segment, or portion of code, which comprises one or more executable instructions for implementing the specified logical function(s). It should also be noted that, in some alternative implementations, the functions noted in the block may occur out of the order noted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved. It will also be noted that each block of the block diagrams and/or flowchart illustration, and combinations of blocks in the block diagrams and/or flowchart illustration, can be implemented by special purpose hardware-based systems which perform the specified functions or acts, or combinations of special purpose hardware and computer instructions.
In the several embodiments provided in the present application, it should be understood that the disclosed system, apparatus and method may be implemented in other ways. The above-described embodiments of the apparatus are merely illustrative, and for example, the division of the units is only one logical division, and there may be other divisions when actually implemented, and for example, a plurality of units or components may be combined or integrated into another system, or some features may be omitted, or not executed. In addition, the shown or discussed mutual coupling or direct coupling or communication connection may be an indirect coupling or communication connection of devices or units through some communication interfaces, and may be in an electrical, mechanical or other form.
The units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of the embodiment.
In addition, functional units in the embodiments of the present invention may be integrated into one processing unit, or each unit may exist alone physically, or two or more units are integrated into one unit.
The functions, if implemented in the form of software functional units and sold or used as a stand-alone product, may be stored in a non-volatile computer-readable storage medium executable by a processor. Based on such understanding, the technical solution of the present invention may be embodied in the form of a software product, which is stored in a storage medium and includes instructions for causing a computer device (which may be a personal computer, a server, or a network device) to execute all or part of the steps of the method according to the embodiments of the present invention. And the aforementioned storage medium includes: a U-disk, a removable hard disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a magnetic disk or an optical disk, and other various media capable of storing program codes.
Finally, it should be noted that: the above-mentioned embodiments are only specific embodiments of the present invention, which are used for illustrating the technical solutions of the present invention and not for limiting the same, and the protection scope of the present invention is not limited thereto, although the present invention is described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: any person skilled in the art can modify or easily conceive the technical solutions described in the foregoing embodiments or equivalent substitutes for some technical features within the technical scope of the present disclosure; such modifications, changes or substitutions do not depart from the spirit and scope of the embodiments of the present invention, and they should be construed as being included therein. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims (9)

1. A satellite network autonomous time synchronization method based on link measurement is characterized by comprising the following steps:
acquiring link connection information between a communication satellite to be synchronized and a plurality of time service nodes, wherein the plurality of time service nodes are nodes in a first satellite communication network, and the plurality of time service nodes comprise at least one of the following: gateway stations, communication satellites, user terminals;
judging whether links exist between the communication satellite to be synchronized and the plurality of time service nodes or not based on the link connection information;
if so, selecting a first time service node from the plurality of time service nodes, wherein the first time service node is a time service node with the highest first synchronization level information in the plurality of time service nodes, and the first synchronization level information is information which is determined by the first satellite communication network in advance according to the link connection relationship between the plurality of time service nodes and a time service master gateway station in the first satellite communication network and is used for representing the link connection relationship between the time service node and the time service master gateway station;
and carrying out time service synchronization operation on the communication satellite to be synchronized by utilizing the first time service node.
2. The method of claim 1, further comprising:
if the fact that no link exists between the communication satellite to be synchronized and the plurality of time service nodes is judged, marking the communication satellite to be synchronized as a second time service node;
and if the number of the satellites marked as the second time service nodes in the historical communication satellites to be synchronized is judged to be multiple, time service synchronization operation between the communication satellites to be synchronized and a second satellite communication network is achieved, wherein the second satellite communication network is a communication network formed by target historical communication satellites marked as the second time service nodes in the historical communication satellites to be synchronized.
3. The method of claim 1, further comprising:
dividing the link connection relation between each time service node in the first satellite communication network and the time service master gateway station into a plurality of first synchronization levels;
setting corresponding identification information for each first synchronization level;
and determining the identification information as first synchronization level information of the corresponding time service node.
4. The method according to claim 2, wherein the implementing of the time service synchronization operation between the communication satellite to be synchronized and the second satellite communication network comprises:
acquiring clock statistical characteristics of the target historical communication satellite to be synchronized, wherein the clock statistical characteristics are used for representing the stability and the frequency deviation of a communication satellite load clock;
determining a second synchronization level of the target historical satellite to be synchronized based on the clock statistical characteristics;
if the second synchronization levels of the target historical communication satellites to be synchronized are different, selecting a third time service node in the second satellite communication network; the third time service node is a target historical communication satellite to be synchronized with the highest second synchronization level in the second satellite communication network;
and carrying out time service synchronization operation on the communication satellite to be synchronized by utilizing the third time service node.
5. The method of claim 4, wherein if the second synchronization level between the target historical satellites in communication to be synchronized is the same, the method further comprises:
determining a third synchronization level of the target historical communication satellite to be synchronized by using a random number generation method;
selecting a fourth time service node in the second satellite communication network; the fourth time service node is a target historical communication satellite to be synchronized with the highest third synchronization level in the second satellite communication network;
and carrying out time service synchronization operation on the communication satellite to be synchronized by utilizing the fourth time service node.
6. The method of claim 4, wherein obtaining clock statistics for the target historical communication-to-be-synchronized satellite comprises:
comparing the local clock of the target historical satellite to be synchronized with an external clock reference to obtain a clock error, wherein the external clock reference comprises: second pulse output by the satellite navigation receiver;
and calculating the variance and the mean of the clock errors, and taking the variance and the mean as the clock statistical characteristics of the target historical satellites to be synchronized.
7. The method of claim 6, wherein determining a second synchronization level for the target historical communication satellite to be synchronized based on the clock statistics comprises:
determining a target value based on the mean and the variance, wherein the mean is a high-order value of the target value and the variance is a low-order value of the target value;
and determining the target value as a second synchronization level of the target historical satellite to be synchronized.
8. A system for autonomous time synchronization of a satellite network based on link measurements, comprising:
the acquisition module is used for acquiring link connection information between a communication satellite to be synchronized and a plurality of time service nodes, wherein the plurality of time service nodes are nodes in a first satellite communication network, and the plurality of time service nodes comprise at least one of the following: gateway stations, communication satellites, user terminals;
the link judgment module is used for judging whether links exist between the communication satellite to be synchronized and the plurality of time service nodes or not based on the link connection information;
the first time service module is used for selecting a first time service node from the plurality of time service nodes if links exist between the communication satellite to be synchronized and the plurality of time service nodes, wherein the first time service node is a time service node with the highest first synchronization level information in the plurality of time service nodes, and the first synchronization level information is information which is determined by the first satellite communication network in advance according to the link connection relation between the plurality of time service nodes and a time service master gateway station in the first satellite communication network and is used for representing the link connection relation between the time service node and the time service master gateway station;
the first time service module is further used for carrying out time service synchronization operation on the communication satellite to be synchronized by utilizing the first time service node.
9. The system of claim 8, further comprising: a second time service module for
If the fact that no link exists between the communication satellite to be synchronized and the plurality of time service nodes is judged, marking the communication satellite to be synchronized as a second time service node;
and if the number of the satellites marked as the second time service nodes in the historical communication satellites to be synchronized is judged to be multiple, time service synchronization operation between the communication satellites to be synchronized and a second satellite communication network is achieved, wherein the second satellite communication network is a communication network formed by target historical communication satellites marked as the second time service nodes in the historical communication satellites to be synchronized.
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