Inter-satellite time synchronization method, device and satellite

Abstract

The application provides an inter-satellite time synchronization method and device and a satellite, and relates to the technical field of satellite communication. The inter-satellite time synchronization method is applied to a first satellite, and the method comprises the following steps: obtaining first information, wherein the first information comprises a message sending timestamp, a message receiving timestamp and a message sending delay; obtaining a target clock difference according to the first information; and sending a target message carrying the target clock difference to a second satellite, so that the second satellite adjusts a clock of the second satellite according to the target clock difference. According to the application, the one-way delay between satellites is obtained through the first information, the target clock difference between the first satellite and the second satellite is calculated according to the one-way delay between satellites, and the target clock difference is sent to the second satellite, so that the second satellite adjusts its own clock according to the target clock difference, the inter-satellite time synchronization can be realized, the inter-satellite time synchronization error is reduced, and the accuracy of time synchronization is improved.

Description

Technical Field

[0001] This invention relates to the field of satellite communication technology, and in particular to a method, apparatus and satellite for inter-satellite time synchronization. Background Technology

[0002] With the rapid development of satellite communication technology, satellite networks are continuously improving their communication capabilities in terms of capacity, speed, latency, and reliability, enabling them to complement and coordinate with terrestrial fixed or mobile networks. Integrated space-ground networks have become a hot topic in global communication technology research in recent years and a key development direction for the information industry, considered one of the main architectural supporting technologies for 5G-A and 6G.

[0003] Satellites are classified into three categories based on their altitude above the Earth: Geostationary Earth Orbit (GEO) satellites, Medium Earth Orbit (MEO) satellites, and Low Earth Orbit (LEO) satellites. GEO satellites are mainly used for broadcasting, television, and communications; MEO satellites are mainly used for navigation and positioning; and LEO satellites, being closer to the Earth, have lower latency. GEO satellites are currently the mainstay of communication services and an important component of integrated space-ground networks. In recent years, however, thanks to advancements in satellite launch technology and reduced construction costs, a global surge in the deployment of LEO satellite internet has emerged in order to secure orbital and spectrum resources, making integrated space-ground networks one of the key evolutionary directions in the field of information infrastructure.

[0004] Low-Earth orbit (LEO) satellites are numerous and cover a wide area, serving as auxiliary augmentation systems for Global Navigation Satellite Systems (GNSS, such as BeiDou, GPS, and GLONASS), improving the accuracy and reliability of user positioning and timing. However, to provide positioning and timing functions, LEO satellites need time synchronization capabilities. Since the vast number of LEO satellites generally do not have stable atomic clocks, traditional time synchronization methods used between navigation satellites need improvement and optimization.

[0005] Existing inter-satellite two-way time synchronization methods involve sending time synchronization messages to each other at the same time that each satellite recognizes, in order to offset the asymmetry of two-way time delay caused by satellite motion. However, since the onboard clocks of low-orbit satellites are not stable enough, the same time recognized by each satellite may actually have a large deviation, which may result in a large two-way time delay and a large inter-satellite time synchronization error. Summary of the Invention

[0006] This invention provides a satellite time synchronization method, apparatus, and satellite to solve the problem of large inter-satellite time synchronization errors caused by existing inter-satellite two-way time synchronization methods.

[0007] To address the aforementioned technical problems, the embodiments of the present invention provide the following technical solutions:

[0008] In a first aspect, embodiments of the present invention provide a time synchronization method between satellites, applied to a first satellite, the method comprising:

[0009] Obtain first information, which includes message sending timestamp, message receiving timestamp, and message sending delay;

[0010] Based on the first information, the target clock difference is obtained;

[0011] Send a target message carrying the target clock difference to the second satellite so that the second satellite adjusts its clock according to the target clock difference;

[0012] Wherein, the message sending timestamp is the timestamp of the first satellite sending the first message to the second satellite;

[0013] The message reception timestamp is the timestamp at which the second satellite receives the first message;

[0014] The message transmission delay is the propagation delay of the first message.

[0015] Optionally, the message transmission delay includes: air interface transmission delay, air interface reception delay, and spatial transmission delay;

[0016] Wherein, the air interface transmission delay is the delay generated by the first message from the first timestamp plane to the air interface that transmits the first message; the first timestamp plane is the plane on which the first satellite timestamps the first message;

[0017] The air interface reception delay is the delay generated from the air interface where the first message is received to the second timestamp plane; the second timestamp plane is the plane on which the second satellite timestamps the message reception for the first message;

[0018] The spatial transmission delay is the delay of the first message being transmitted in space.

[0019] Optionally, obtaining the first information includes:

[0020] Based on the ephemeris of the first satellite and the ephemeris of the second satellite, determine the first moment indicated by the message transmission timestamp, the position coordinates of the first satellite and the position coordinates of the second satellite;

[0021] The spatial transmission delay is obtained based on the position coordinates of the first satellite and the position coordinates of the second satellite.

[0022] Optionally, the first information further includes the satellite relative displacement delay; obtaining the first information includes:

[0023] Based on the ephemeris of the first satellite and the ephemeris of the second satellite, determine the first moment indicated by the message transmission timestamp, and the velocity difference vector of the second satellite relative to the first satellite;

[0024] The relative displacement delay of the satellite is obtained based on the velocity difference vector.

[0025] Optionally, obtaining the first information includes:

[0026] Receive the message reception timestamp and the air interface reception delay sent by the second satellite via the second message.

[0027] Secondly, embodiments of the present invention also provide a satellite time synchronization method, applied to a second satellite, the method comprising:

[0028] Receive the target message carrying the target clock difference sent by the first satellite;

[0029] Adjust the clock of the second satellite according to the target clock difference;

[0030] The target clock bias is obtained by the first satellite based on the first information, which includes the message transmission timestamp, the message reception timestamp, and the message transmission delay.

[0031] The message transmission timestamp is the timestamp at which the first satellite sends the first message to the second satellite;

[0032] The message reception timestamp is the timestamp at which the second satellite receives the first message;

[0033] The message transmission delay is the propagation delay of the first message.

[0034] Optionally, the message transmission delay includes: air interface transmission delay, air interface reception delay, and spatial transmission delay;

[0035] Wherein, the air interface transmission delay is the delay generated by the first message from the first timestamp plane to the air interface that transmits the first message; the first timestamp plane is the plane on which the first satellite timestamps the first message;

[0036] The air interface reception delay is the delay generated from the air interface where the first message is received to the second timestamp plane; the second timestamp plane is the plane on which the second satellite timestamps the message reception for the first message;

[0037] The spatial transmission delay is the delay of the first message being transmitted in space.

[0038] Optionally, the first information may also include the satellite's relative displacement delay;

[0039] The satellite relative displacement delay is obtained based on the velocity difference vector of the second satellite relative to the first satellite at the first moment indicated by the message transmission timestamp.

[0040] The first moment indicated by the message transmission timestamp, the velocity difference vector between the second satellite and the first satellite is determined by the first satellite based on the ephemeris of the first satellite and the ephemeris of the second satellite.

[0041] Optionally, the method further includes:

[0042] The second message sends the message reception timestamp and the air interface reception delay to the first satellite.

[0043] Thirdly, embodiments of the present invention also provide an inter-satellite time synchronization device, applied to a first satellite, the device comprising:

[0044] The acquisition module is used to acquire first information, which includes message sending timestamp, message receiving timestamp, and message sending delay.

[0045] The processing module is used to obtain the target clock difference based on the first information;

[0046] The first transmitting module is used to send a target message carrying the target clock difference to the second satellite, so that the second satellite adjusts its clock according to the target clock difference;

[0047] Wherein, the message sending timestamp is the timestamp of the first satellite sending the first message to the second satellite;

[0048] The message reception timestamp is the timestamp at which the second satellite receives the first message;

[0049] The message transmission delay is the propagation delay of the first message.

[0050] Optionally, the message transmission delay includes: air interface transmission delay, air interface reception delay, and spatial transmission delay;

[0051] Wherein, the air interface transmission delay is the delay generated by the first message from the first timestamp plane to the air interface that transmits the first message; the first timestamp plane is the plane on which the first satellite timestamps the first message;

[0052] The air interface reception delay is the delay generated from the air interface where the first message is received to the second timestamp plane; the second timestamp plane is the plane on which the second satellite timestamps the message reception for the first message;

[0053] The spatial transmission delay is the delay of the first message being transmitted in space.

[0054] Optionally, the acquisition module includes:

[0055] The first determining unit is configured to determine, based on the ephemeris of the first satellite and the ephemeris of the second satellite, the first moment indicated by the message transmission timestamp, the position coordinates of the first satellite, and the position coordinates of the second satellite;

[0056] The first acquisition unit is used to obtain the spatial transmission delay based on the position coordinates of the first satellite and the position coordinates of the second satellite.

[0057] Optionally, the first information may also include the satellite's relative displacement delay;

[0058] The acquisition module includes:

[0059] The second determining unit is used to determine the first moment indicated by the message transmission timestamp and the velocity difference vector of the second satellite relative to the first satellite based on the ephemeris of the first satellite and the ephemeris of the second satellite.

[0060] The second acquisition unit is used to obtain the relative displacement delay of the satellite based on the velocity difference vector.

[0061] Optionally, the acquisition module includes:

[0062] The message receiving unit is used to receive the message receiving timestamp and the air interface receiving delay sent by the second satellite via the second message.

[0063] Fourthly, embodiments of the present invention also provide an inter-satellite time synchronization device, applied to a second satellite, the device comprising:

[0064] The first receiving module is used to receive the target message carrying the target clock difference sent by the first satellite;

[0065] An adjustment module is used to adjust the clock of the second satellite according to the target clock difference;

[0066] The target clock bias is obtained by the first satellite based on the first information, which includes the message transmission timestamp, the message reception timestamp, and the message transmission delay.

[0067] The message transmission timestamp is the timestamp at which the first satellite sends the first message to the second satellite;

[0068] The message reception timestamp is the timestamp at which the second satellite receives the first message;

[0069] The message transmission delay is the propagation delay of the first message.

[0070] Optionally, the message transmission delay includes: air interface transmission delay, air interface reception delay, and spatial transmission delay;

[0071] Wherein, the air interface transmission delay is the delay generated by the first message from the first timestamp plane to the air interface that transmits the first message; the first timestamp plane is the plane on which the first satellite timestamps the first message;

[0072] The air interface reception delay is the delay generated from the air interface where the first message is received to the second timestamp plane; the second timestamp plane is the plane on which the second satellite timestamps the message reception for the first message;

[0073] The spatial transmission delay is the delay of the first message being transmitted in space.

[0074] Optionally, the first information may also include the satellite's relative displacement delay;

[0075] The satellite relative displacement delay is obtained based on the velocity difference vector of the second satellite relative to the first satellite at the first moment indicated by the message transmission timestamp.

[0076] The first moment indicated by the message transmission timestamp, the velocity difference vector between the second satellite and the first satellite is determined by the first satellite based on the ephemeris of the first satellite and the ephemeris of the second satellite.

[0077] Optionally, the device further includes:

[0078] The message sending module is used to send the message reception timestamp and the air interface reception delay to the first satellite via a second message.

[0079] Fifthly, embodiments of the present invention also provide a satellite, which is a first satellite, comprising: a processor and a transceiver;

[0080] The processor is configured to acquire first information, the first information including message sending timestamp, message receiving timestamp, and message sending delay;

[0081] Based on the first information, the target clock difference is obtained;

[0082] The transceiver is used to send a target message carrying the target clock difference to the second satellite, so that the second satellite adjusts its clock according to the target clock difference;

[0083] Wherein, the message sending timestamp is the timestamp of the first satellite sending the first message to the second satellite;

[0084] The message reception timestamp is the timestamp at which the second satellite receives the first message;

[0085] The message transmission delay is the propagation delay of the first message.

[0086] Optionally, the message transmission delay includes: air interface transmission delay, air interface reception delay, and spatial transmission delay;

[0087] Wherein, the air interface transmission delay is the delay generated by the first message from the first timestamp plane to the air interface that transmits the first message; the first timestamp plane is the plane on which the first satellite timestamps the first message;

[0088] The air interface reception delay is the delay generated from the air interface where the first message is received to the second timestamp plane; the second timestamp plane is the plane on which the second satellite timestamps the message reception for the first message;

[0089] The spatial transmission delay is the delay of the first message being transmitted in space.

[0090] Optionally, the processor is specifically used for:

[0091] Based on the ephemeris of the first satellite and the ephemeris of the second satellite, determine the first moment indicated by the message transmission timestamp, the position coordinates of the first satellite and the position coordinates of the second satellite;

[0092] The spatial transmission delay is obtained based on the position coordinates of the first satellite and the position coordinates of the second satellite.

[0093] Optionally, the first information may also include the satellite's relative displacement delay;

[0094] The processor is specifically used for:

[0095] Based on the ephemeris of the first satellite and the ephemeris of the second satellite, determine the first moment indicated by the message transmission timestamp, and the velocity difference vector of the second satellite relative to the first satellite;

[0096] The relative displacement delay of the satellite is obtained based on the velocity difference vector.

[0097] Optionally, the transceiver is specifically used for:

[0098] Receive the message reception timestamp and the air interface reception delay sent by the second satellite via the second message.

[0099] Sixthly, embodiments of the present invention also provide a satellite, which is a second satellite, comprising: a processor and a transceiver;

[0100] The transceiver is used to receive target messages carrying the target clock difference sent by the first satellite;

[0101] The processor is configured to adjust the clock of the second satellite according to the target clock difference;

[0102] The target clock bias is obtained by the first satellite based on the first information, which includes the message transmission timestamp, the message reception timestamp, and the message transmission delay.

[0103] The message transmission timestamp is the timestamp at which the first satellite sends the first message to the second satellite;

[0104] The message reception timestamp is the timestamp at which the second satellite receives the first message;

[0105] The message transmission delay is the propagation delay of the first message.

[0106] Optionally, the message transmission delay includes: air interface transmission delay, air interface reception delay, and spatial transmission delay;

[0107] Wherein, the air interface transmission delay is the delay generated by the first message from the first timestamp plane to the air interface that transmits the first message; the first timestamp plane is the plane on which the first satellite timestamps the first message;

[0108] The air interface reception delay is the delay generated from the air interface where the first message is received to the second timestamp plane; the second timestamp plane is the plane on which the second satellite timestamps the message reception for the first message;

[0109] The spatial transmission delay is the delay of the first message being transmitted in space.

[0110] Optionally, the first information may also include the satellite's relative displacement delay;

[0111] The satellite relative displacement delay is obtained based on the velocity difference vector of the second satellite relative to the first satellite at the first moment indicated by the message transmission timestamp.

[0112] The first moment indicated by the message transmission timestamp, the velocity difference vector between the second satellite and the first satellite is determined by the first satellite based on the ephemeris of the first satellite and the ephemeris of the second satellite.

[0113] Optionally, the transceiver is further configured to:

[0114] The second message sends the message reception timestamp and the air interface reception delay to the first satellite.

[0115] In a seventh aspect, embodiments of the present invention also provide a satellite, which is a first satellite, including a memory, a processor, and a program stored in the memory and executable on the processor; when the processor executes the program, it implements the inter-satellite time synchronization method as described in any one of the first aspects.

[0116] Eighthly, embodiments of the present invention also provide a satellite, which is a second satellite, including a memory, a processor, and a program stored in the memory and executable on the processor; when the processor executes the program, it implements the inter-satellite time synchronization method as described in any one of the second aspects.

[0117] In a ninth aspect, embodiments of the present invention also provide a readable storage medium having a program stored thereon, which, when executed by a processor, implements the steps of the inter-satellite time synchronization method as described in any one of the first aspects; or, when executed by a processor, the program implements the steps of the inter-satellite time synchronization method as described in any one of the second aspects.

[0118] The beneficial effects of this invention are:

[0119] The present invention obtains first information including message sending timestamp, message receiving timestamp, and message sending delay. Using this first information, a target clock difference is obtained, i.e., the inter-satellite one-way delay is obtained. Based on the inter-satellite one-way delay, the target clock difference between the first satellite and the second satellite is calculated, and the target clock difference is sent to the second satellite. This allows the second satellite to adjust its own clock according to the target clock difference, thereby achieving inter-satellite time synchronization, reducing inter-satellite time synchronization errors, and improving the accuracy of time synchronization. Attached Figure Description

[0120] Figure 1A flowchart illustrating the inter-satellite time synchronization method applied to a first satellite provided in an embodiment of the present invention;

[0121] Figure 2 This diagram illustrates the propagation of the first message provided in an embodiment of the present invention between a first satellite and a second satellite.

[0122] Figure 3 This is a schematic diagram illustrating the message transmission between the master satellite and the slave satellite provided in an embodiment of the present invention.

[0123] Figure 4 A flowchart illustrating the inter-satellite time synchronization method for a second satellite provided in an embodiment of the present invention;

[0124] Figure 5 This is a schematic diagram of the structure of the inter-satellite time synchronization device applied to a first satellite provided in an embodiment of the present invention;

[0125] Figure 6 This is a schematic diagram of the structure of the inter-satellite time synchronization device applied to a second satellite provided in an embodiment of the present invention;

[0126] Figure 7 This represents one of the structural schematic diagrams of the first satellite provided in an embodiment of the present invention;

[0127] Figure 8 This represents one of the structural schematic diagrams of the second satellite provided in an embodiment of the present invention;

[0128] Figure 9 This is a second schematic diagram illustrating the structure of the first satellite provided in an embodiment of the present invention.

[0129] Figure 10 This is the second schematic diagram of the structure of the second satellite provided in an embodiment of the present invention. Detailed Implementation

[0130] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0131] This invention addresses the problem of large inter-satellite time synchronization errors caused by existing inter-satellite two-way time synchronization methods by providing an inter-satellite time synchronization method, device, and satellite.

[0132] like Figure 1 As shown, this embodiment of the invention provides a time synchronization method between satellites, applied to a first satellite, the method comprising:

[0133] Step 101: Obtain first information, which includes message sending timestamp, message receiving timestamp, and message sending delay;

[0134] Wherein, the message sending timestamp is the timestamp of the first satellite sending the first message to the second satellite;

[0135] The message reception timestamp is the timestamp at which the second satellite receives the first message;

[0136] The message transmission delay is the propagation delay of the first message.

[0137] It should be noted that both the first satellite and the second satellite are low-Earth orbit satellites, with the first satellite being the master satellite and the second satellite being the slave satellite.

[0138] The message transmission timestamp T1 is directly obtained by the first satellite. The message reception timestamp T2 is recorded by the second satellite after receiving the first message, and the second satellite then sends this timestamp back to the first satellite. The message transmission delay includes the delay of the first satellite transmitting the first message internally, the delay of the first message propagating in space, and the delay of the second satellite receiving the first message internally.

[0139] Step 102: Obtain the target clock difference based on the first information.

[0140] In this step, the one-way time delay between satellites is obtained based on the first information. Based on the one-way time delay between satellites, the target clock offset between the first satellite and the second satellite is calculated. This target clock offset is used to enable the second satellite to adjust its own clock offset.

[0141] Step 103: Send a target message carrying the target clock difference to the second satellite so that the second satellite adjusts its clock according to the target clock difference.

[0142] In this step, the first satellite sends a target message to the second satellite, which carries a target clock offset. The second satellite adjusts its own clock according to the target clock offset to achieve inter-satellite time synchronization. Furthermore, since this embodiment of the invention calculates the target clock offset through a one-way delay, it can reduce inter-satellite time synchronization errors and improve the accuracy of time synchronization.

[0143] Optionally, the message transmission delay includes: air interface transmission delay, air interface reception delay, and spatial transmission delay;

[0144] Wherein, the air interface transmission delay is the delay generated by the first message from the first timestamp plane to the air interface that transmits the first message; the first timestamp plane is the plane on which the first satellite timestamps the first message;

[0145] The air interface reception delay is the delay generated from the air interface where the first message is received to the second timestamp plane; the second timestamp plane is the plane on which the second satellite timestamps the message reception for the first message;

[0146] The spatial transmission delay is the delay of the first message being transmitted in space.

[0147] The message transmission delay includes the delay of the first message being transmitted internally by the first satellite, the delay of the first message propagating in space, and the delay of the first message being received internally by the second satellite. Specifically, the delay of the first message being transmitted internally by the first satellite is the delay measured and recorded by the first satellite from the plane where the first satellite sets the message transmission timestamp T1 (the first timestamp plane) to the air interface where the first satellite transmits the first message, i.e., the air interface transmission delay δ1. The delay of the first message propagating in space is the space transmission delay Delay1. The delay of the first message being received internally by the second satellite is the delay measured and recorded by the second satellite after receiving the first message, from the air interface where the first message is received by the second satellite to the plane where the second satellite sets the message reception timestamp T2 (the second timestamp plane), i.e., the air interface reception delay δ2.

[0148] Optionally, obtaining the first information includes:

[0149] Based on the ephemeris of the first satellite and the ephemeris of the second satellite, determine the first moment indicated by the message transmission timestamp, the position coordinates of the first satellite and the position coordinates of the second satellite;

[0150] The spatial transmission delay is obtained based on the position coordinates of the first satellite and the position coordinates of the second satellite.

[0151] The process of obtaining the spatial transmission delay Delay1 is explained in detail below:

[0152] Because low-Earth orbit satellites have relatively high relative speeds, please refer to [link / reference needed] for details regarding the relative motion between the first and second satellites. Figure 2 , Figure 2 This is a schematic diagram illustrating the propagation of the first message between the first and second satellites.

[0153] Based on the ephemeris of the first satellite and the second satellite, the first satellite calculates the position coordinates P of the first satellite at the first moment indicated by the message transmission timestamp T1. M1 The position coordinates P of the second satellite s1 And the velocity difference vector ΔV1 between the second satellite and the first satellite, based on the position coordinates P of the first satellite. M1 The position coordinates P of the second satellite s1The velocity difference vector ΔV1 between the second satellite and the first satellite, and the speed of light, are used to calculate the spatial transmission delay Delay1 according to the following formula:

[0154]

[0155] Where Delay1 represents spatial transmission delay, P M1 P represents the position coordinates of the first satellite. S1 Let represent the position coordinates of the second satellite, Δv1 represent the velocity difference vector between the second satellite and the first satellite, and c represent the speed of light.

[0156] This invention, in accordance with the characteristics of satellite links, improves the 1588 time synchronization method. The master satellite records its internal delay (air interface transmission delay), calculates the transmission delay of radio waves between the master and slave satellites (space transmission delay) based on ephemeris data, and then transmits its internal delay (air interface reception delay) to the master satellite to calculate the total transmission delay of the message (first message), which is the accurate one-way transmission delay of the first message. The accurate one-way transmission delay calculated by the master satellite can be directly used for clock difference calculation between the master and slave satellites, improving the accuracy of time synchronization between them.

[0157] Optionally, the first information further includes the satellite relative displacement delay; obtaining the first information includes:

[0158] Based on the ephemeris of the first satellite and the ephemeris of the second satellite, determine the first moment indicated by the message transmission timestamp, and the velocity difference vector of the second satellite relative to the first satellite;

[0159] The relative displacement delay of the satellite is obtained based on the velocity difference vector.

[0160] Because low-Earth orbit satellites have relatively high relative speeds, the relative wheel effect cannot be ignored for high time synchronization accuracy. Therefore, the first information described in this embodiment of the invention also includes a relative displacement delay Tr, which is calculated based on the velocity difference vector Δv1 between the second satellite and the first satellite. The velocity difference vector Δv1 between the second satellite and the first satellite is calculated by the first satellite based on the ephemeris of the first satellite and the second satellite. Specifically, the relative displacement delay Tr is calculated by the first satellite based on the velocity difference vector Δv1 and the speed of light according to the following formula:

[0161]

[0162] Where Δv1 represents the velocity difference vector between the second satellite and the first satellite, and c represents the speed of light.

[0163] If the first information also includes the satellite's relative displacement time delay, the target clock difference is obtained based on the first information, including:

[0164] The target clock difference is obtained based on the message sending timestamp, message receiving timestamp, message sending delay, and relative displacement delay.

[0165] The time difference between the message reception timestamp and the message transmission timestamp can be obtained by the following formula:

[0166] T2-T1=Delay1+δ1+δ2+offset+Tr Formula 3

[0167] Where T2 represents the message reception timestamp, T1 represents the message transmission timestamp, Delay1 represents the spatial transmission delay, δ1 represents the air interface transmission delay, δ2 represents the air interface reception delay, offset represents the target clock difference, and Tr represents the relative displacement delay.

[0168] Based on Formula 3 above, we can obtain Formula 4 as follows:

[0169] offset=Delay1+δ1+δ2-T2+T1+Tr Formula 4

[0170] Therefore, according to Formula 4 above, the first satellite can calculate the target clock difference between the first satellite and the second satellite based on the message transmission timestamp, message reception timestamp, message transmission delay, and relative displacement delay.

[0171] In summary, based on Formulas 1, 2, 3, and 4, we obtain Formula 5 as follows:

[0172]

[0173] In this embodiment of the invention, the master satellite combines relativistic effects with the total transmission delay of the message, as well as the message reception timestamp T2 and message transmission timestamp T1 of the first message, to calculate the target clock offset between the master satellite and the slave satellite, and sends it to the slave satellite to adjust its own clock.

[0174] In this embodiment of the invention, the master satellite uses the ephemeris of the master satellite and the slave satellite to calculate the relative motion velocity (velocity difference vector) of the slave satellite relative to the master satellite. Based on the velocity difference vector, the relative displacement time delay of the satellite is obtained, and the clock error caused by the relativistic effect of the satellite is compensated, thereby further improving the accuracy of time synchronization between the master satellite and the slave satellite.

[0175] Optionally, obtaining the first information includes:

[0176] Receive the message reception timestamp and the air interface reception delay sent by the second satellite via the second message.

[0177] Please see Figure 3 , Figure 3 This is a schematic diagram of message transmission between the master satellite and the slave satellite.

[0178] The master satellite (first satellite) sends a first message (Sync) to the slave satellite (second satellite). The first message carries a message transmission timestamp T1. The first satellite measures and records the time delay (air interface transmission delay δ1) from the plane where the first message is sent (timestamp T1) to the air interface where the first message was sent. The propagation delay of the first message in space is the space transmission delay Delay1. The second satellite receives the first message and records the message reception timestamp T2. The second satellite measures and records the time delay from the air interface where the first message was received to the air interface where the first message was sent. The second satellite sends a second message (Delay_req) to the first satellite, carrying the message reception timestamp T2 and the air interface reception delay δ2. The first satellite receives the second message, records the message reception timestamp T2 and the air interface reception delay δ2, calculates the target clock offset, and sends a target message (Delay_resp) to the second satellite, carrying the target clock offset. The second satellite adjusts its own clock according to the target clock offset.

[0179] like Figure 4 As shown, this embodiment of the invention also provides a satellite time synchronization method, applied to a second satellite, the method comprising:

[0180] Step 401: Receive the target message carrying the target clock difference sent by the first satellite;

[0181] The target clock bias is obtained by the first satellite based on the first information, which includes the message transmission timestamp, the message reception timestamp, and the message transmission delay.

[0182] The message transmission timestamp is the timestamp at which the first satellite sends the first message to the second satellite;

[0183] The message reception timestamp is the timestamp at which the second satellite receives the first message;

[0184] The message transmission delay is the propagation delay of the first message.

[0185] In this step, the first satellite obtains the one-way inter-satellite time delay based on the first information. Based on this delay, it calculates the target clock difference between the first and second satellites. This target clock difference is used to enable the second satellite to adjust its own clock difference. The first satellite then sends the target clock difference to the second satellite via a target message.

[0186] Step 402: Adjust the clock of the second satellite according to the target clock difference.

[0187] In this step, the second satellite adjusts its own clock according to the target clock difference to achieve inter-satellite time synchronization. Furthermore, since the embodiment of the present invention calculates the target clock difference through unidirectional time delay, it can reduce inter-satellite time synchronization errors and improve the accuracy of time synchronization.

[0188] Optionally, the message transmission delay includes: air interface transmission delay, air interface reception delay, and spatial transmission delay;

[0189] Wherein, the air interface transmission delay is the delay generated by the first message from the first timestamp plane to the air interface that transmits the first message; the first timestamp plane is the plane on which the first satellite timestamps the first message;

[0190] The air interface reception delay is the delay generated from the air interface where the first message is received to the second timestamp plane; the second timestamp plane is the plane on which the second satellite timestamps the message reception for the first message;

[0191] The spatial transmission delay is the delay of the first message being transmitted in space.

[0192] The message transmission delay includes the delay of the first message being transmitted internally by the first satellite, the delay of the first message propagating in space, and the delay of the first message being received internally by the second satellite. Specifically, the delay of the first message being transmitted internally by the first satellite is the delay measured and recorded by the first satellite from the plane where the first satellite timestamps the message transmission (first timestamp plane) to the air interface where the first satellite transmits the message, i.e., the air interface transmission delay. The delay of the first message propagating in space is the space transmission delay. The delay of the first message being received internally by the second satellite is the delay measured and recorded by the second satellite after receiving the first message, from the air interface where the first message is received by the second satellite to the plane where the second satellite timestamps the message reception (second timestamp plane), i.e., the air interface reception delay.

[0193] Optionally, the first information may also include the satellite's relative displacement delay;

[0194] The satellite relative displacement delay is obtained based on the velocity difference vector of the second satellite relative to the first satellite at the first moment indicated by the message transmission timestamp.

[0195] The first moment indicated by the message transmission timestamp, the velocity difference vector between the second satellite and the first satellite is determined by the first satellite based on the ephemeris of the first satellite and the ephemeris of the second satellite.

[0196] Since the relative motion speed of low-orbit satellites is relatively large, the relative wheel effect cannot be ignored for high time synchronization accuracy. Therefore, the first information described in this embodiment of the invention also includes a relative displacement delay, wherein the relative displacement delay is calculated based on the velocity difference vector between the second satellite and the first satellite. The velocity difference vector between the second satellite and the first satellite is calculated by the first satellite based on the ephemeris of the first satellite and the ephemeris of the second satellite.

[0197] Optionally, the method further includes:

[0198] The second message sends the message reception timestamp and the air interface reception delay to the first satellite.

[0199] The first satellite sends a first message to the second satellite, which carries a message transmission timestamp. The first satellite measures and records the time delay from the plane where the message transmission timestamp is applied to the air interface where the message was sent (air interface transmission delay). The second satellite receives the first message, records the message reception timestamp, measures and records the time delay from the air interface where the first message is received to the plane where the message reception timestamp is applied (air interface reception delay). The second satellite then sends a second message to the first satellite, which carries a message reception timestamp and the air interface reception delay.

[0200] like Figure 5 As shown, this embodiment of the invention also provides an inter-satellite time synchronization device, applied to a first satellite, the device comprising:

[0201] The acquisition module 501 is used to acquire first information, which includes message sending timestamp, message receiving timestamp and message sending delay;

[0202] Processing module 502 is used to obtain the target clock difference based on the first information;

[0203] The first transmitting module is used to send a target message carrying the target clock difference to the second satellite, so that the second satellite adjusts its clock according to the target clock difference;

[0204] Wherein, the message sending timestamp is the timestamp of the first satellite sending the first message to the second satellite;

[0205] The message reception timestamp is the timestamp at which the second satellite receives the first message;

[0206] The message transmission delay is the propagation delay of the first message.

[0207] Optionally, the message transmission delay includes: air interface transmission delay, air interface reception delay, and spatial transmission delay;

[0208] Wherein, the air interface transmission delay is the delay generated by the first message from the first timestamp plane to the air interface that transmits the first message; the first timestamp plane is the plane on which the first satellite timestamps the first message;

[0209] The air interface reception delay is the delay generated from the air interface where the first message is received to the second timestamp plane; the second timestamp plane is the plane on which the second satellite timestamps the message reception for the first message;

[0210] The spatial transmission delay is the delay of the first message being transmitted in space.

[0211] Optionally, the acquisition module 501 includes:

[0212] The first determining unit is configured to determine, based on the ephemeris of the first satellite and the ephemeris of the second satellite, the first moment indicated by the message transmission timestamp, the position coordinates of the first satellite, and the position coordinates of the second satellite;

[0213] The first acquisition unit is used to obtain the spatial transmission delay based on the position coordinates of the first satellite and the position coordinates of the second satellite.

[0214] Optionally, the first information may also include the satellite's relative displacement delay;

[0215] The acquisition module 501 includes:

[0216] The second determining unit is used to determine the first moment indicated by the message transmission timestamp and the velocity difference vector of the second satellite relative to the first satellite based on the ephemeris of the first satellite and the ephemeris of the second satellite.

[0217] The second acquisition unit is used to obtain the relative displacement delay of the satellite based on the velocity difference vector.

[0218] Optionally, the acquisition module 501 includes:

[0219] The message receiving unit is used to receive the message receiving timestamp and the air interface receiving delay sent by the second satellite via the second message.

[0220] It should be noted that the inter-satellite time synchronization device for the first satellite provided in this embodiment of the invention is a device capable of executing the above-described inter-satellite time synchronization method for the first satellite. Therefore, all embodiments of the above-described inter-satellite time synchronization method for the first satellite are applicable to this device and can achieve the same or similar technical effects.

[0221] like Figure 6 As shown, this embodiment of the invention also provides an inter-satellite time synchronization device, applied to a second satellite, the device comprising:

[0222] The first receiving module 601 is used to receive the target message carrying the target clock difference sent by the first satellite;

[0223] Adjustment module 602 is used to adjust the clock of the second satellite according to the target clock difference;

[0224] The target clock bias is obtained by the first satellite based on the first information, which includes the message transmission timestamp, the message reception timestamp, and the message transmission delay.

[0225] The message transmission timestamp is the timestamp at which the first satellite sends the first message to the second satellite;

[0226] The message reception timestamp is the timestamp at which the second satellite receives the first message;

[0227] The message transmission delay is the propagation delay of the first message.

[0228] Optionally, the message transmission delay includes: air interface transmission delay, air interface reception delay, and spatial transmission delay;

[0229] Wherein, the air interface transmission delay is the delay generated by the first message from the first timestamp plane to the air interface that transmits the first message; the first timestamp plane is the plane on which the first satellite timestamps the first message;

[0230] The air interface reception delay is the delay generated from the air interface where the first message is received to the second timestamp plane; the second timestamp plane is the plane on which the second satellite timestamps the message reception for the first message;

[0231] The spatial transmission delay is the delay of the first message being transmitted in space.

[0232] Optionally, the first information may also include the satellite's relative displacement delay;

[0233] The satellite relative displacement delay is obtained based on the velocity difference vector of the second satellite relative to the first satellite at the first moment indicated by the message transmission timestamp.

[0234] The first moment indicated by the message transmission timestamp, the velocity difference vector between the second satellite and the first satellite is determined by the first satellite based on the ephemeris of the first satellite and the ephemeris of the second satellite.

[0235] Optionally, the device further includes:

[0236] The message sending module is used to send the message reception timestamp and the air interface reception delay to the first satellite via a second message.

[0237] It should be noted that the inter-satellite time synchronization device for the second satellite provided in this embodiment of the invention is a device capable of executing the above-described inter-satellite time synchronization method for the second satellite. Therefore, all embodiments of the above-described inter-satellite time synchronization method for the second satellite are applicable to this device and can achieve the same or similar technical effects.

[0238] like Figure 7 As shown, this embodiment of the invention also provides a satellite, which is a first satellite, including: a processor 701 and a transceiver 702;

[0239] The processor 701 is used to acquire first information, the first information including message sending timestamp, message receiving timestamp and message sending delay;

[0240] Based on the first information, the target clock difference is obtained;

[0241] The transceiver 702 is used to send a target message carrying the target clock difference to the second satellite, so that the second satellite adjusts its clock according to the target clock difference;

[0242] Wherein, the message sending timestamp is the timestamp of the first satellite sending the first message to the second satellite;

[0243] The message reception timestamp is the timestamp at which the second satellite receives the first message;

[0244] The message transmission delay is the propagation delay of the first message.

[0245] Optionally, the message transmission delay includes: air interface transmission delay, air interface reception delay, and spatial transmission delay;

[0246] Wherein, the air interface transmission delay is the delay generated by the first message from the first timestamp plane to the air interface that transmits the first message; the first timestamp plane is the plane on which the first satellite timestamps the first message;

[0247] The air interface reception delay is the delay generated from the air interface where the first message is received to the second timestamp plane; the second timestamp plane is the plane on which the second satellite timestamps the message reception for the first message;

[0248] The spatial transmission delay is the delay of the first message being transmitted in space.

[0249] Optionally, the processor 701 is specifically used for:

[0250] Based on the ephemeris of the first satellite and the ephemeris of the second satellite, determine the first moment indicated by the message transmission timestamp, the position coordinates of the first satellite and the position coordinates of the second satellite;

[0251] The spatial transmission delay is obtained based on the position coordinates of the first satellite and the position coordinates of the second satellite.

[0252] Optionally, the first information may also include the satellite's relative displacement delay;

[0253] The processor 701 is specifically used for:

[0254] Based on the ephemeris of the first satellite and the ephemeris of the second satellite, determine the first moment indicated by the message transmission timestamp, and the velocity difference vector of the second satellite relative to the first satellite;

[0255] The relative displacement delay of the satellite is obtained based on the velocity difference vector.

[0256] Optionally, the transceiver 702 is specifically used for:

[0257] Receive the message reception timestamp and the air interface reception delay sent by the second satellite via the second message.

[0258] It should be noted that the satellite provided in the embodiments of the present invention is a satellite capable of executing the above-described inter-satellite time synchronization method applied to the first satellite. Therefore, all embodiments of the above-described inter-satellite time synchronization method applied to the first satellite are applicable to this satellite and can achieve the same or similar technical effects.

[0259] like Figure 8 As shown, this embodiment of the invention also provides a satellite, which is a second satellite, including: a processor 801 and a transceiver 802;

[0260] The transceiver 802 is used to receive target messages carrying the target clock difference sent by the first satellite;

[0261] The processor 801 is used to adjust the clock of the second satellite according to the target clock difference;

[0262] The target clock bias is obtained by the first satellite based on the first information, which includes the message transmission timestamp, the message reception timestamp, and the message transmission delay.

[0263] The message transmission timestamp is the timestamp at which the first satellite sends the first message to the second satellite;

[0264] The message reception timestamp is the timestamp at which the second satellite receives the first message;

[0265] The message transmission delay is the propagation delay of the first message.

[0266] Optionally, the message transmission delay includes: air interface transmission delay, air interface reception delay, and spatial transmission delay;

[0267] Wherein, the air interface transmission delay is the delay generated by the first message from the first timestamp plane to the air interface that transmits the first message; the first timestamp plane is the plane on which the first satellite timestamps the first message;

[0268] The air interface reception delay is the delay generated from the air interface where the first message is received to the second timestamp plane; the second timestamp plane is the plane on which the second satellite timestamps the message reception for the first message;

[0269] The spatial transmission delay is the delay of the first message being transmitted in space.

[0270] Optionally, the first information may also include the satellite's relative displacement delay;

[0271] The satellite relative displacement delay is obtained based on the velocity difference vector of the second satellite relative to the first satellite at the first moment indicated by the message transmission timestamp.

[0272] The first moment indicated by the message transmission timestamp, the velocity difference vector between the second satellite and the first satellite is determined by the first satellite based on the ephemeris of the first satellite and the ephemeris of the second satellite.

[0273] Optionally, the transceiver 802 is further configured to:

[0274] The second message sends the message reception timestamp and the air interface reception delay to the first satellite.

[0275] It should be noted that the satellite provided in the embodiments of the present invention is a satellite capable of executing the above-described inter-satellite time synchronization method applied to the second satellite. Therefore, all embodiments of the above-described inter-satellite time synchronization method applied to the second satellite are applicable to this satellite and can achieve the same or similar technical effects.

[0276] like Figure 9 As shown, this embodiment of the invention also provides a satellite, which is a first satellite, including: a processor 901; and a memory 903 connected to the processor 901 via a bus interface 902. The memory 903 is used to store programs and data used by the processor 901 when performing operations, and the processor 901 calls and executes the programs and data stored in the memory 903.

[0277] The transceiver 904 is connected to the bus interface 902 and is used to receive and send data under the control of the processor 901. Specifically, the processor 901 is used to read the program in the memory 903 and executes the following processes:

[0278] Obtain first information, which includes message sending timestamp, message receiving timestamp, and message sending delay;

[0279] Based on the first information, the target clock difference is obtained;

[0280] The transceiver 904 performs the following process:

[0281] Send a target message carrying the target clock difference to the second satellite so that the second satellite adjusts its clock according to the target clock difference;

[0282] Wherein, the message sending timestamp is the timestamp of the first satellite sending the first message to the second satellite;

[0283] The message reception timestamp is the timestamp at which the second satellite receives the first message;

[0284] The message transmission delay is the propagation delay of the first message.

[0285] Optionally, the message transmission delay includes: air interface transmission delay, air interface reception delay, and spatial transmission delay;

[0286] Wherein, the air interface transmission delay is the delay generated by the first message from the first timestamp plane to the air interface that transmits the first message; the first timestamp plane is the plane on which the first satellite timestamps the first message;

[0287] The air interface reception delay is the delay generated from the air interface where the first message is received to the second timestamp plane; the second timestamp plane is the plane on which the second satellite timestamps the message reception for the first message;

[0288] The spatial transmission delay is the delay of the first message being transmitted in space.

[0289] Optionally, the processor 901 is configured to:

[0290] Based on the ephemeris of the first satellite and the ephemeris of the second satellite, determine the first moment indicated by the message transmission timestamp, the position coordinates of the first satellite and the position coordinates of the second satellite;

[0291] The spatial transmission delay is obtained based on the position coordinates of the first satellite and the position coordinates of the second satellite.

[0292] Optionally, the first information may also include the satellite's relative displacement delay;

[0293] The processor 901 is used for:

[0294] Based on the ephemeris of the first satellite and the ephemeris of the second satellite, determine the first moment indicated by the message transmission timestamp, and the velocity difference vector of the second satellite relative to the first satellite;

[0295] The relative displacement delay of the satellite is obtained based on the velocity difference vector.

[0296] Optionally, the transceiver 904 is used for:

[0297] Receive the message reception timestamp and the air interface reception delay sent by the second satellite via the second message.

[0298] Among them, Figure 9In this context, the bus architecture can include any number of interconnected buses and bridges, specifically linking various circuits together, represented by one or more processors (processor 901) and memory (memory 903). The bus architecture can also link various other circuits such as peripheral devices, voltage regulators, and power management circuits, which are well known in the art and therefore will not be described further herein. The bus interface provides an interface. The transceiver 904 can be multiple elements, including transmitters and receivers, providing a unit for communicating with various other devices over a transmission medium. Processor 901 is responsible for managing the bus architecture and general processing, and memory 903 can store data used by processor 901 during operation.

[0299] like Figure 10 As shown, this embodiment of the invention also provides a satellite, which is a second satellite, including: a processor 1001; and a memory 1003 connected to the processor 1001 via a bus interface 1002. The memory 1003 is used to store programs and data used by the processor 1001 when performing operations, and the processor 1001 calls and executes the programs and data stored in the memory 1003.

[0300] The transceiver 1004 is connected to the bus interface 1002 and is used to receive and send data under the control of the processor 1001. Specifically, the processor 1001 is used to read the program in the memory 1003, and the transceiver 1004 executes the following processes:

[0301] Receive the target message carrying the target clock difference sent by the first satellite;

[0302] The processor 1001 performs the following procedures:

[0303] Adjust the clock of the second satellite according to the target clock difference;

[0304] The target clock bias is obtained by the first satellite based on the first information, which includes the message transmission timestamp, the message reception timestamp, and the message transmission delay.

[0305] The message transmission timestamp is the timestamp at which the first satellite sends the first message to the second satellite;

[0306] The message reception timestamp is the timestamp at which the second satellite receives the first message;

[0307] The message transmission delay is the propagation delay of the first message.

[0308] Optionally, the message transmission delay includes: air interface transmission delay, air interface reception delay, and spatial transmission delay;

[0309] Wherein, the air interface transmission delay is the delay generated by the first message from the first timestamp plane to the air interface that transmits the first message; the first timestamp plane is the plane on which the first satellite timestamps the first message;

[0310] The air interface reception delay is the delay generated from the air interface where the first message is received to the second timestamp plane; the second timestamp plane is the plane on which the second satellite timestamps the message reception for the first message;

[0311] The spatial transmission delay is the delay of the first message being transmitted in space.

[0312] Optionally, the first information may also include the satellite's relative displacement delay;

[0313] The satellite relative displacement delay is obtained based on the velocity difference vector of the second satellite relative to the first satellite at the first moment indicated by the message transmission timestamp.

[0314] The first moment indicated by the message transmission timestamp, the velocity difference vector between the second satellite and the first satellite is determined by the first satellite based on the ephemeris of the first satellite and the ephemeris of the second satellite.

[0315] Optionally, the transceiver 1004 is further configured to:

[0316] The second message sends the message reception timestamp and the air interface reception delay to the first satellite.

[0317] Among them, Figure 10 In this context, the bus architecture may include any number of interconnected buses and bridges, specifically linking various circuits together, represented by one or more processors (processor 1001) and memory (memory 1003). The bus architecture may also link together various other circuits such as peripheral devices, voltage regulators, and power management circuits, which are well known in the art and therefore will not be described further herein. The bus interface provides an interface. The transceiver 1004 may be multiple elements, including transmitters and receivers, providing a unit for communicating with various other devices over a transmission medium. The processor 1001 is responsible for managing the bus architecture and general processing, and the memory 1003 may store data used by the processor 1001 during operation.

[0318] In addition, specific embodiments of the present invention also provide a computer-readable storage medium having a computer program stored thereon, wherein when the program is executed by a processor, it implements the steps of the inter-satellite time synchronization method applied to a first satellite as described above, or implements the steps of the inter-satellite time synchronization method applied to a second satellite as described above.

[0319] In the several embodiments provided in this application, it should be understood that the disclosed methods and apparatus can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between devices or units may be electrical, mechanical, or other forms.

[0320] Furthermore, the functional units in the various embodiments of the present invention can be integrated into one processing unit, or each unit can be physically comprised separately, or two or more units can be integrated into one unit. The integrated unit described above can be implemented in hardware or in the form of hardware plus software functional units.

[0321] The integrated units implemented as software functional units described above can be stored in a computer-readable storage medium. These software functional units, stored in a storage medium, include several instructions that cause a computer device (which may be a personal computer, server, or network device, etc.) to execute some steps of the transmission and reception methods described in the various embodiments of this invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0322] The above describes the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications are also within the scope of protection of the present invention.

Claims

1. A method for time synchronization between satellites, characterized in that, Applied to a first satellite, the method includes: Obtain first information, which includes message sending timestamp, message receiving timestamp, and message sending delay. The first information also includes satellite relative displacement delay. Based on the first information, the target clock difference is obtained; Send a target message carrying the target clock difference to the second satellite so that the second satellite adjusts its clock according to the target clock difference; Wherein, the message sending timestamp is the timestamp of the first satellite sending the first message to the second satellite; The message reception timestamp is the timestamp at which the second satellite receives the first message; The message transmission delay is the propagation delay of the first message; The acquisition of the first information includes: Based on the ephemeris of the first satellite and the ephemeris of the second satellite, determine the first moment indicated by the message transmission timestamp, and the velocity difference vector of the second satellite relative to the first satellite; The relative displacement delay of the satellite is obtained based on the velocity difference vector.

2. The inter-satellite time synchronization method according to claim 1, characterized in that, The message transmission delay includes: air interface transmission delay, air interface reception delay, and spatial transmission delay; Wherein, the air interface transmission delay is the delay generated by the first message from the first timestamp plane to the air interface that transmits the first message; the first timestamp plane is the plane on which the first satellite timestamps the first message; The air interface reception delay is the delay generated from the air interface where the first message is received to the second timestamp plane; the second timestamp plane is the plane on which the second satellite timestamps the message reception for the first message; The spatial transmission delay is the delay of the first message being transmitted in space.

3. The inter-satellite time synchronization method according to claim 2, characterized in that, The acquisition of the first information includes: Based on the ephemeris of the first satellite and the ephemeris of the second satellite, determine the first moment indicated by the message transmission timestamp, the position coordinates of the first satellite and the position coordinates of the second satellite; The spatial transmission delay is obtained based on the position coordinates of the first satellite and the position coordinates of the second satellite.

4. The inter-satellite time synchronization method according to claim 2, characterized in that, The acquisition of the first information includes: Receive the message reception timestamp and the air interface reception delay sent by the second satellite via the second message.

5. A method for time synchronization between satellites, characterized in that, Applied to a second satellite, the method includes: Receive the target message carrying the target clock difference sent by the first satellite; Adjust the clock of the second satellite according to the target clock difference; The target clock bias is obtained by the first satellite based on the first information, which includes the message transmission timestamp, the message reception timestamp, and the message transmission delay. The first information also includes the satellite relative displacement delay. The message transmission timestamp is the timestamp at which the first satellite sends the first message to the second satellite; The message reception timestamp is the timestamp at which the second satellite receives the first message; The message transmission delay is the propagation delay of the first message; The satellite relative displacement delay is obtained based on the velocity difference vector of the second satellite relative to the first satellite at the first moment indicated by the message transmission timestamp. The first moment indicated by the message transmission timestamp, the velocity difference vector between the second satellite and the first satellite is determined by the first satellite based on the ephemeris of the first satellite and the ephemeris of the second satellite.

6. The inter-satellite time synchronization method according to claim 5, characterized in that, The message transmission delay includes: air interface transmission delay, air interface reception delay, and spatial transmission delay; Wherein, the air interface transmission delay is the delay generated by the first message from the first timestamp plane to the air interface that transmits the first message; the first timestamp plane is the plane on which the first satellite timestamps the first message; The air interface reception delay is the delay generated from the air interface where the first message is received to the second timestamp plane; the second timestamp plane is the plane on which the second satellite timestamps the message reception for the first message; The spatial transmission delay is the delay of the first message being transmitted in space.

7. The inter-satellite time synchronization method according to claim 6, characterized in that, The method further includes: The second message sends the message reception timestamp and the air interface reception delay to the first satellite.

8. A time synchronization device between satellites, characterized in that, Applied to a first satellite, the device includes: The acquisition module is used to acquire first information, which includes a message sending timestamp, a message receiving timestamp, and a message sending delay. The first information also includes a satellite relative displacement delay. The processing module is used to obtain the target clock difference based on the first information; The first transmitting module is used to send a target message carrying the target clock difference to the second satellite, so that the second satellite adjusts its clock according to the target clock difference; Wherein, the message sending timestamp is the timestamp of the first satellite sending the first message to the second satellite; The message reception timestamp is the timestamp at which the second satellite receives the first message; The message transmission delay is the propagation delay of the first message; The acquisition module includes: The second determining unit is configured to determine, based on the ephemeris of the first satellite and the ephemeris of the second satellite, the first moment indicated by the message transmission timestamp, and the velocity difference vector of the second satellite relative to the first satellite; The second acquisition unit is used to obtain the relative displacement delay of the satellite based on the velocity difference vector.

9. A time synchronization device between satellites, characterized in that, Applied to a second satellite, the device includes: The first receiving module is used to receive the target message carrying the target clock difference sent by the first satellite; An adjustment module is used to adjust the clock of the second satellite according to the target clock difference; The target clock bias is obtained by the first satellite based on the first information, which includes the message transmission timestamp, the message reception timestamp, and the message transmission delay. The first information also includes the satellite relative displacement delay. The message transmission timestamp is the timestamp at which the first satellite sends the first message to the second satellite; The message reception timestamp is the timestamp at which the second satellite receives the first message; The message transmission delay is the propagation delay of the first message; The satellite relative displacement delay is obtained based on the velocity difference vector of the second satellite relative to the first satellite at the first moment indicated by the message transmission timestamp. The first moment indicated by the message transmission timestamp, the velocity difference vector between the second satellite and the first satellite is determined by the first satellite based on the ephemeris of the first satellite and the ephemeris of the second satellite.

10. A satellite, said satellite being a first satellite, characterized in that, include: Processor and transceiver; The processor is configured to acquire first information, the first information including message transmission timestamp, message reception timestamp and message transmission delay, and the first information also includes satellite relative displacement delay; Based on the first information, the target clock difference is obtained; The transceiver is used to send a target message carrying the target clock difference to the second satellite, so that the second satellite adjusts its clock according to the target clock difference; Wherein, the message sending timestamp is the timestamp of the first satellite sending the first message to the second satellite; The message reception timestamp is the timestamp at which the second satellite receives the first message; The message transmission delay is the propagation delay of the first message; Specifically, the processor is used for: Based on the ephemeris of the first satellite and the ephemeris of the second satellite, determine the first moment indicated by the message transmission timestamp, and the velocity difference vector of the second satellite relative to the first satellite; The relative displacement delay of the satellite is obtained based on the velocity difference vector.

11. A satellite, wherein the satellite is a second satellite, characterized in that, include: Processor and transceiver; The transceiver is used to receive target messages carrying the target clock difference sent by the first satellite; The processor is configured to adjust the clock of the second satellite according to the target clock difference; The target clock bias is obtained by the first satellite based on the first information, which includes the message transmission timestamp, the message reception timestamp, and the message transmission delay. The first information also includes the satellite relative displacement delay. The message transmission timestamp is the timestamp at which the first satellite sends the first message to the second satellite; The message reception timestamp is the timestamp at which the second satellite receives the first message; The message transmission delay is the propagation delay of the first message; The satellite relative displacement delay is obtained based on the velocity difference vector of the second satellite relative to the first satellite at the first moment indicated by the message transmission timestamp. The first moment indicated by the message transmission timestamp, the velocity difference vector between the second satellite and the first satellite is determined by the first satellite based on the ephemeris of the first satellite and the ephemeris of the second satellite.

12. A satellite, said satellite being a first satellite, comprising a memory, a processor, and a program stored in said memory and executable on said processor; characterized in that, When the processor executes the program, it implements the inter-satellite time synchronization method as described in any one of claims 1 to 4.

13. A satellite, said satellite being a second satellite, comprising a memory, a processor, and a program stored in said memory and executable on said processor; characterized in that, When the processor executes the program, it implements the inter-satellite time synchronization method as described in any one of claims 5 to 7.

14. A readable storage medium having a program stored thereon, characterized in that, When the program is executed by the processor, it implements the steps in the inter-satellite time synchronization method as described in any one of claims 1 to 4; or, when the program is executed by the processor, it implements the steps in the inter-satellite time synchronization method as described in any one of claims 5 to 7.

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