Inter-satellite time synchronization method and apparatus, satellite and storage medium

Abstract

The present disclosure provides an inter-satellite time synchronization method and apparatus, a satellite and a storage medium. The method comprises: a first satellite sending a first packet to at least one second satellite, the first packet carrying a sending timestamp; receiving first information and / or a second packet sent by the at least one second satellite.

Description

Inter-satellite time synchronization method, device, satellite and storage medium

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to Chinese patent application No. 202310034928.0 filed in China on January 10, 2023, the entire contents of which are incorporated herein by reference. Technical Field

[0003] The present disclosure relates to the field of communication technology, and in particular to a method, device, satellite, and storage medium for inter-satellite time synchronization. Background Art

[0004] Currently, low-orbit satellite networks can provide satellite services beyond the coverage area of ​​gateway stations. Satellite services such as navigation, remote sensing, and mapping require high-precision time synchronization. However, existing time synchronization technologies or protocols cannot synchronize time between networked satellites.

[0005] Summary of the Invention

[0006] To solve related technical problems, the embodiments of the present disclosure provide a method, device, satellite and storage medium for inter-satellite time synchronization.

[0007] The technical solution of the embodiment of the present disclosure is implemented as follows:

[0008] An embodiment of the present disclosure provides a method for inter-satellite time synchronization, which is applied to a first satellite. The method includes:

[0009] Sending a first message to at least one second satellite; the first message carries a sending timestamp;

[0010] Receive the first information and / or the second message sent by the at least one second satellite.

[0011] In the above solution, the first information includes the first difference and / or the reception timestamp of the first message; the first difference represents the difference between the reception timestamp of the first message and the corresponding transmission timestamp.

[0012] In the above solution, the second message carries a sending timestamp.

[0013] In the above solution, the method further includes:

[0014] Send corresponding second information to the at least one second satellite; wherein the second information includes a second difference and / or a receiving timestamp of the second message; the second difference represents a difference between the receiving timestamp of the second message and the corresponding sending timestamp.

[0015] In the above solution, the method further includes one of the following:

[0016] adjusting or calibrating the local time of the first satellite based on a first time offset between the first satellite and a second satellite;

[0017] When the number of second satellites is greater than or equal to 2, the local time of the first satellite is adjusted or calibrated based on a mean or a weighted average of first time offsets between the first satellite and different second satellites.

[0018] In the above solution, the method further includes:

[0019] A first time offset between the first satellite and the second satellite is determined based at least on a sending timestamp and / or a corresponding receiving timestamp of the first message and a sending timestamp and / or a corresponding receiving timestamp of the second message.

[0020] In the above solution, determining the first time offset between the first satellite and the second satellite includes:

[0021] Determine a first sending timestamp of the first message and / or a second sending timestamp of the second message based on the sending timestamp of the first message and / or the sending timestamp of the second message;

[0022] Determining a first time offset between the first satellite and the second satellite based on at least one of the following:

[0023] A first sending timestamp and a corresponding receiving timestamp;

[0024] A second sending timestamp and a corresponding receiving timestamp;

[0025] A first error correction value.

[0026] In the above solution, the first sending timestamp is the same as the second sending timestamp; or,

[0027] The difference between the first sending timestamp and the second sending timestamp is the minimum value among the third difference values; the third difference value is the difference between the sending timestamp of the first message and the sending timestamp of the second message.

[0028] In the above solution, both the first message and the second message are periodic messages.

[0029] In the above solution, the first satellite and the at least one second satellite are located in the same orbit, and the at least one second satellite is adjacent to the first satellite.

[0030] In the above solution, the first satellite and the at least one second satellite are located in different orbits; the first message and the second message are both transmitted during a period when the first satellite establishes a connection with the corresponding second satellite.

[0031] The method further comprises:

[0032] Receive Global Navigation Satellite System (GNSS) time;

[0033] The local time of the first satellite is updated based on the GNSS time.

[0034] In the above solution, the method further includes:

[0035] In the event that the first satellite does not receive GNSS time, the local time of the first satellite is maintained according to the local time frequency.

[0036] The present disclosure also provides a method for inter-satellite time synchronization, which is applied to a second satellite. The method includes:

[0037] receiving a first message sent by at least one first satellite; the first message carries a sending timestamp;

[0038] Sending the first information and / or the second message to the at least one first satellite.

[0039] In the above solution, the first information includes the first difference and / or the reception timestamp of the first message; the first difference represents the difference between the reception timestamp of the first message and the corresponding transmission timestamp.

[0040] In the above solution, the second message carries a sending timestamp.

[0041] In the above solution, the method further includes:

[0042] receiving second information sent by the first satellite; wherein,

[0043] The second information includes a second difference and / or a receiving timestamp of the second message; the second difference represents a difference between the receiving timestamp of the second message and the corresponding sending timestamp.

[0044] In the above solution, the method further includes one of the following:

[0045] adjusting or calibrating the local time of the second satellite based on a second time offset between the second satellite and the first satellite;

[0046] When the number of first satellites is greater than or equal to 2, the local time of the second satellite is adjusted or calibrated based on a mean or a weighted average of second time offsets between the second satellite and different first satellites.

[0047] In the above solution, the method further includes:

[0048] A second time offset between the second satellite and the first satellite is determined based at least on a sending timestamp and / or a corresponding receiving timestamp of the first message and a sending timestamp and / or a corresponding receiving timestamp of the second message.

[0049] In the above solution, determining the second time offset between the second satellite and the first satellite includes:

[0050] Determine, based on the sending timestamp of the first message and / or the sending timestamp of the second message, a third sending timestamp of the first message and / or a fourth sending timestamp of the second message;

[0051] Determining a second time offset between the second satellite and the first satellite based on at least one of the following:

[0052] A third sending timestamp and a corresponding receiving timestamp;

[0053] A fourth sending timestamp and a corresponding receiving timestamp;

[0054] a second error correction value.

[0055] In the above solution, the third sending timestamp is the same as the fourth sending timestamp; or,

[0056] The difference between the third sending timestamp and the fourth sending timestamp is the minimum value among the fourth difference values; the fourth difference value is the difference between the sending timestamp of the first message and the sending timestamp of the second message.

[0057] In the above solution, both the first message and the second message are periodic messages.

[0058] In the above solution, the at least one first satellite and the second satellite are located in the same orbit, and the second satellite is adjacent to the at least one first satellite.

[0059] In the above solution, the at least one first satellite and the second satellite are located in different orbits; the second message and the first message are both transmitted during the period when the second satellite establishes a connection with the corresponding first satellite.

[0060] In the above solution, the method further includes:

[0061] Receive GNSS time;

[0062] The local time of the second satellite is updated based on the GNSS time.

[0063] In the above solution, the method further includes:

[0064] In the event that the second satellite does not receive the GNSS time, the local time of the second satellite is maintained according to the local time frequency.

[0065] The present disclosure also provides an inter-satellite time synchronization device, including:

[0066] A first sending unit, configured to send a first message to at least one second satellite; the first message carries a sending timestamp;

[0067] The first receiving unit is configured to receive the first information and / or the second message sent by the at least one second satellite.

[0068] The present disclosure also provides an inter-satellite time synchronization device, including:

[0069] A second receiving unit is configured to receive a first message sent by at least one first satellite; the first message carries a sending timestamp;

[0070] The second sending unit is configured to send the first information and / or the second message to the at least one first satellite.

[0071] The embodiment of the present disclosure further provides a first satellite, including a first processor and a first communication interface, wherein:

[0072] The first communication interface is used to send a first message to at least one second satellite and receive the first information and / or second message sent by the at least one second satellite; wherein,

[0073] The first message carries a sending timestamp.

[0074] The embodiment of the present disclosure further provides a second satellite, including a second processor and a second communication interface, wherein:

[0075] The second communication interface is used to receive a first message sent by at least one first satellite, and send first information and / or a second message to the at least one first satellite; wherein,

[0076] The first message carries a sending timestamp.

[0077] An embodiment of the present disclosure further provides a satellite, comprising a processor and a memory for storing a computer program capable of running on the processor.

[0078] The processor is configured to execute the steps of any method on the first satellite side or the steps of any method on the second satellite side when running the computer program.

[0079] An embodiment of the present disclosure further provides a storage medium storing a computer program, wherein when the computer program is executed by a processor, the computer program implements the steps of any method on the first satellite side, or implements the steps of any method on the second satellite side.

[0080] In the inter-satellite time synchronization method, device, satellite, and storage medium provided by the embodiments of the present disclosure, a first satellite sends a first message to at least one second satellite; the first message carries a sending timestamp; the second satellite receives the first message sent by at least one first satellite and sends a first message and / or a second message to the at least one first satellite; the first satellite receives the first message and / or the second message sent by the at least one second satellite. In the above scheme, the first message and the second message are sent in parallel, which can avoid changes in transmission delay caused by multiple serial interactions or multiple handshakes that consume a lot of time, so that when the first satellite and / or the second satellite perform time synchronization, accurate time synchronization information can be obtained, thereby improving the accuracy of the time synchronization information. There is no master-slave relationship between the first satellite and the second satellite, which solves the problem of unstable satellite network topology and the inability to establish master-slave synchronization for a long time. BRIEF DESCRIPTION OF THE DRAWINGS

[0081] FIG1 is a schematic diagram of an implementation flow of a method for inter-satellite time synchronization according to an embodiment of the present disclosure;

[0082] FIG2 is a schematic diagram of an implementation flow of a method for inter-satellite time synchronization according to an embodiment of the present disclosure;

[0083] FIG3 is a schematic diagram of an interaction flow of an inter-satellite time synchronization method according to an embodiment of the present disclosure;

[0084] FIG4 is a schematic structural diagram of an inter-satellite time synchronization device according to an embodiment of the present disclosure;

[0085] FIG5 is a schematic structural diagram of an inter-satellite time synchronization device according to an embodiment of the present disclosure;

[0086] FIG6 is a schematic diagram of the structure of the first satellite according to an embodiment of the present disclosure;

[0087] FIG7 is a schematic diagram of the structure of the second satellite according to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0088] Time synchronization is the basis for the operation of many communication systems. For example, in mobile communication systems, base stations need to meet the requirement of high-precision time synchronization at the microsecond level, otherwise there will be interference between base stations. In related technologies, time synchronization can be achieved by installing satellite receivers at each base station; it can also be achieved based on terrestrial time synchronization technology, such as the Precision Time Protocol (PTP). Among them, PTP adopts a master-slave time synchronization mechanism: in a communication path, the master clock provides the source time for the synchronization of the next level of clock, that is, for the reference of the slave clock; the slave clock exchanges text messages with the master clock and corrects the local time according to the time provided by the master clock. The time synchronization topology and tracking relationship can be determined through the master-slave source selection algorithm.

[0089] With the development of integrated space-ground communications, intersatellite networking has become a hot topic in satellite network research. Low-orbit satellite networking can provide satellite services beyond the coverage area of ​​gateway stations. Satellite services such as navigation and positioning, remote sensing, and mapping require high-precision time synchronization information from satellites.

[0090] Currently, time synchronization information for individual satellites can be obtained through interaction with gateway stations or by installing GNSS receivers. However, when a large number of low-orbit satellites are networked, they may be unable to obtain time synchronization information from gateway stations when they orbit over areas where they cannot interact with gateway stations. Furthermore, the GNSS receivers installed on each satellite face challenges such as payload limitations and reception accuracy.

[0091] In summary, in the related art, a single satellite may fail to obtain time synchronization information, or the obtained time synchronization information may be inaccurate, and accurate time synchronization information cannot be obtained between satellites.

[0092] In addition, the existing ground time synchronization technology is only suitable for master-slave time synchronization determined by topological connections. Networked satellites cannot synchronize time using the existing time synchronization technology or time synchronization protocol for the following reasons:

[0093] 1. The topology of the satellite network will change over time, and it is impossible to establish a stable master-slave relationship;

[0094] 2. The existing time synchronization protocol is based on the handshake protocol (the two communicating parties send messages serially). During multiple interactions, a lot of time is consumed. The relative position relationship of the satellites has changed, resulting in changes in the transmission delay, which does not meet the time synchronization calculation basis under the fixed delay condition.

[0095] Based on this, in each embodiment of the present disclosure, a first satellite sends a first message to at least one second satellite; the first message carries a sending timestamp; the second satellite receives the first message sent by at least one first satellite, and sends a first message and / or a second message to the at least one first satellite; the first satellite receives the first message and / or the second message sent by the at least one second satellite. In the above scheme, the first message and the second message are sent in parallel, which can avoid changes in transmission delay caused by multiple serial interactions or multiple handshakes that consume a lot of time, so that when the first satellite and / or the second satellite perform time synchronization, accurate time synchronization information can be obtained, thereby improving the accuracy of the time synchronization information. There is no master-slave relationship between the first satellite and the second satellite, which solves the problem of unstable satellite network topology and the inability to establish master-slave synchronization for a long time.

[0096] The present disclosure will be described in further detail below with reference to the accompanying drawings and embodiments.

[0097] The present disclosure provides an inter-satellite time synchronization method, which is applied to a first satellite. As shown in FIG1 , the method includes:

[0098] Step 101: Send a first message to at least one second satellite.

[0099] The first message carries a sending timestamp.

[0100] Here, the sending timestamp carried by the first message is the sending timestamp of the first message. The at least one second satellite is connected to the first satellite. That is, the first satellite and the second satellite interact only when the connection exists.

[0101] The first satellite generally refers to any satellite, and the second satellite generally refers to a satellite connected to the first satellite. The number of second satellites connected to the first satellite is greater than or equal to 1. The number of first messages is greater than or equal to 1.

[0102] Step 102: Receive the first information and / or the second message sent by the at least one second satellite.

[0103] Here, the first information represents the relevant information of the first message. The second message may carry the relevant information of the first message, or may not carry the relevant information of the first message. When the first satellite receives the second message, it may record the receiving timestamp of the second message.

[0104] It should be noted that the first message and the second message can be sent by the second satellite in parallel. The first satellite sends the first message, and the second satellite sends the second message, and the two are executed in parallel.

[0105] In one embodiment, the first information includes a first difference and / or a reception timestamp of the first message; the first difference represents a difference between the reception timestamp of the first message and a corresponding transmission timestamp.

[0106] Here, the reception timestamp of the first message is recorded by the second satellite upon receipt of the first message. The first difference can be understood as the difference between the reception timestamp of the first message recorded by the second satellite and the transmission timestamp carried by the first message. The first difference corresponds one-to-one with the first message. The first difference can be used by the first satellite to determine the corresponding reception timestamp of the first message. For example, the first satellite can determine the reception timestamp of the first message based on the first difference corresponding to the first message and the transmission timestamp of the first message.

[0107] In one embodiment, the second message carries a sending timestamp.

[0108] Here, when the first satellite receives the second message, the reception timestamp of the second message is recorded. The reception timestamp of the second message may also be associated and stored with the transmission timestamp carried by the second message. The transmission timestamp carried by the second message is the transmission timestamp of the second message. The number of second messages sent by each second satellite is greater than or equal to one.

[0109] In one embodiment, both the first message and the second message are periodic messages.

[0110] Here, the first satellite periodically sends the first message, and the second satellite periodically sends the second message. The sending period of the first message is the same as or approximately the same as the sending period of the second message.

[0111] It should be noted that since the second message is periodic, the first satellite can obtain the second message's transmission period from the second satellite, and thereby obtain the second message's transmission time based on the second message's transmission period. In this way, even if the second message does not carry a transmission timestamp, the first satellite can still determine the first time offset between the first and second satellites based on the second message's reception timestamp and the second message's transmission time.

[0112] Of course, in the case where the second message carries a sending timestamp, the first satellite may determine the first time offset between the first satellite and the second satellite based on the receiving timestamp and the sending timestamp of the second message.

[0113] When performing time synchronization between satellites, the first satellite can perform time synchronization to adjust or calibrate the local time of the first satellite; the second satellite can also perform time synchronization to adjust or calibrate the local time of the second satellite. Since the second satellite can record the sending timestamp and receiving timestamp of each first message, to facilitate the second satellite's time synchronization, the first satellite can return the receiving timestamp and / or second difference corresponding to the second message sent by the second satellite to the second satellite. Based on this, in one embodiment, the method further includes:

[0114] Send corresponding second information to the at least one second satellite; wherein the second information includes a second difference and / or a receiving timestamp of the second message; the second difference represents a difference between the receiving timestamp of the second message and the corresponding sending timestamp.

[0115] Here, when the first satellite receives the second message sent by the second satellite, it sends the second information corresponding to the second satellite to the second satellite that sent the second message.

[0116] The second information corresponds to the second message in a one-to-one manner. The second difference can be understood as the difference between the receiving timestamp of the second message recorded by the first satellite and the sending timestamp carried by the second message.

[0117] The second difference value may be used by the second satellite to determine a corresponding reception timestamp of the second message. For example, the second satellite may determine a reception timestamp of the second message based on the second difference value corresponding to the second message and a transmission timestamp of the second message.

[0118] When the first satellite performs time synchronization, the first satellite may adjust or calibrate the local time of the first satellite based on the first time offset between the first satellite and the second satellite to improve the accuracy of the local time of the first satellite, so that the first satellite maintains time synchronization with the second satellite. Based on this, in one embodiment, the method further includes one of the following:

[0119] adjusting or calibrating the local time of the first satellite based on a first time offset between the first satellite and a second satellite;

[0120] When the number of second satellites is greater than or equal to 2, the local time of the first satellite is adjusted or calibrated based on a mean or a weighted average of first time offsets between the first satellite and different second satellites.

[0121] The first time offset is determined based on at least relevant information of the first message and relevant information of the second message sent by the second satellite.

[0122] Here, the first satellite determines a first time offset between the first satellite and the corresponding second satellite based on information related to the first message and information related to the second message sent by the second satellite. The information related to the first message includes a sending timestamp of the first message and the first information; and the information related to the second message includes a sending timestamp of the second message and a corresponding receiving timestamp.

[0123] In a case where the number of second satellites having a connection relationship with the first satellite is one, the local time of the first satellite is adjusted or calibrated based on a first time offset between the first satellite and the second satellite.

[0124] When the number of second satellites in a connection relationship with a first satellite is greater than or equal to two, a mean or weighted average of the first time offsets is determined based on first time offsets between the first satellite and different second satellites; and the local time of the first satellite is adjusted or calibrated based on the determined mean or weighted average. The different second satellites may be some or all of the second satellites in a connection relationship with the first satellite.

[0125] Before the first satellite performs time synchronization, it is necessary to first determine a first time offset between the first satellite and the second satellite. Based on this, in one embodiment, the method further includes:

[0126] A first time offset between the first satellite and the second satellite is determined based at least on a sending timestamp and / or a corresponding receiving timestamp of the first message and a sending timestamp and / or a corresponding receiving timestamp of the second message.

[0127] Here, the first satellite determines the sending timestamp and the corresponding receiving timestamp of the first message based on the sending timestamp of the first message and the corresponding first information; and determines a first time offset between the first satellite and the corresponding second satellite based at least on the sending timestamp and the corresponding receiving timestamp of the first message, and based on the sending timestamp and the corresponding receiving timestamp of the second message; the corresponding second satellite is the second satellite that sent the second message. In this case, the first message and the second message may be periodic messages or non-periodic messages.

[0128] Of course, when both the first message and the second message are periodic messages, and the sending period of the first message is the same as the sending period of the second message, when the sending time of the first message is the same as the sending time of the second message within the same period, the first satellite can determine the first time offset between the first satellite and the second satellite based at least on the sending timestamp of the first message and the receiving timestamp of the second message; when the sending time of the first message is the same as the sending time of the second message within the same period, and the first satellite obtains the receiving timestamp of the first message and the sending timestamp of the second message, the first satellite can also determine the first time offset between the first satellite and the second satellite based at least on the sending timestamp of the second message and the receiving timestamp of the first message; when the sending time of the first message is different from the sending time of the second message within the same period, the first satellite can determine the first time offset between the first satellite and the second satellite based at least on the sending timestamp of the first message and the sending timestamp of the second message.

[0129] In order to improve the accuracy of the first time offset determined by the first satellite, in one embodiment, determining the first time offset between the first satellite and the second satellite includes:

[0130] Determine a first sending timestamp of the first message and / or a second sending timestamp of the second message based on the sending timestamp of the first message and / or the sending timestamp of the second message;

[0131] Determining a first time offset between the first satellite and the second satellite based on at least one of the following:

[0132] A first sending timestamp and a corresponding receiving timestamp;

[0133] A second sending timestamp and a corresponding receiving timestamp;

[0134] A first error correction value.

[0135] Here, the first satellite determines, from the transmission timestamps of the first message and / or the transmission timestamps of the second message, a first transmission timestamp of the first message and / or a second transmission timestamp of the second message that meet a condition, wherein the condition at least includes that the first transmission timestamp and the second transmission timestamp are identical, closest to, or approximately equal to each other, and may further include that the difference between the first transmission timestamp and the corresponding reception timestamp is relatively close to, or approximately equal to, the difference between the second transmission timestamp and the corresponding reception timestamp.

[0136] For example, in the case where both the first message and the second message are periodic messages, when the sending time of the second message within the same period is the same as the sending time of the first message, for each period, the first sending timestamp is determined in the sending timestamp of the first message, and / or the second sending timestamp is determined in the sending timestamp of the second message; when the sending time of the second message within the same period is different from the sending time of the first message, for each period, the first sending timestamp and the second timestamp whose sending timestamps are closest to or approximately equal to each other are determined in the sending timestamp of the first message and the sending timestamp of the second message.

[0137] When the first sending timestamp of the first message is determined, the receiving timestamp corresponding to the first sending timestamp of the first message is determined based on the sending timestamp and the corresponding receiving timestamp of the first message; when the second sending timestamp of the second message is determined, the receiving timestamp corresponding to the second sending timestamp of the second message is determined based on the sending timestamp and the corresponding receiving timestamp of the second message.

[0138] After the first satellite determines the receiving timestamp corresponding to the first sending timestamp of the first message and the receiving timestamp corresponding to the second sending timestamp of the second message, the first satellite uses method one, method two, method three or method four to determine a first time offset between the first satellite and the second satellite.

[0139] Method 1:

[0140] A first time offset between a first satellite and a corresponding second satellite is determined based on a first sending timestamp and a corresponding receiving timestamp of the first message, or based on a second sending timestamp and a corresponding receiving timestamp of the second message.

[0141] For example, based on the difference between the first sending timestamp of the first message and the corresponding receiving timestamp or the absolute value of the difference, a first time offset between the first satellite and the corresponding second satellite is determined.

[0142] For another example, based on the difference or the absolute value of the difference between the second sending timestamp of the second message and the corresponding receiving timestamp, a first time offset between the first satellite and the corresponding second satellite is determined.

[0143] Method 2:

[0144] Based on the first sending timestamp and the corresponding receiving timestamp of the first message, and the first error correction value, a first time offset between the first satellite and the corresponding second satellite is determined; or based on the second sending timestamp and the corresponding receiving timestamp of the second message, and the first error correction value, the first time offset between the first satellite and the corresponding second satellite is determined.

[0145] It should be noted that the first error correction value is used to compensate for the error caused by the time consumed by data processing within the first satellite.

[0146] Method 3:

[0147] A first time offset between a first satellite and a corresponding second satellite is determined based on a first sending timestamp and a corresponding receiving timestamp of the first message, and a second sending timestamp and a corresponding receiving timestamp of the second message.

[0148] For example, a first absolute value of the difference between the second sending timestamp and the corresponding receiving timestamp is determined, and a second absolute value of the difference between the first sending timestamp and the corresponding receiving timestamp is determined; the second absolute value is subtracted from the first absolute value to obtain an absolute value difference; the absolute value difference is divided by 2 to obtain a first time deviation between the first satellite and the corresponding second satellite.

[0149] For another example, since the receiving timestamp of the same message is greater than the corresponding sending timestamp, the first satellite can subtract the difference between the receiving timestamp corresponding to the second sending timestamp and the second sending timestamp from the difference between the receiving timestamp corresponding to the first sending timestamp and the first sending timestamp to obtain a fifth difference; and divide the fifth difference by 2 to obtain a first time offset between the first satellite and the corresponding second satellite.

[0150] In actual application, when the first satellite is satellite A and the second satellite is satellite B, the formula [(T reA1 -T sendB1 )-(T reB1 -T sendA1 )] / 2, calculate the first time offset between the first satellite and the corresponding second satellite. Wherein, T sendA1 is the first sending timestamp of the first message, T reB1 is the receiving timestamp corresponding to the first sending timestamp of the first message; T sendB1 is the second sending timestamp of the second message, T reA1 It is the receiving timestamp corresponding to the second sending timestamp of the second message.

[0151] Method 4:

[0152] A first time offset between the first satellite and the corresponding second satellite is determined based on the receiving timestamp corresponding to the first sending timestamp, the second sending timestamp and the corresponding receiving timestamp, and the first error correction value.

[0153] For example, a first absolute value of the difference between the second transmission timestamp and the corresponding reception timestamp is determined, and a second absolute value of the difference between the first transmission timestamp and the corresponding reception timestamp is determined; the second absolute value is subtracted from the first absolute value to obtain an absolute value difference; the absolute value difference is divided by 2 to obtain a mean of the absolute values; the mean of the absolute values ​​is added to the first error correction value to obtain a first time deviation between the first satellite and the corresponding second satellite.

[0154] For another example, considering that the receiving timestamp of the same message is greater than the corresponding sending timestamp, the first satellite can subtract the difference between the receiving timestamp corresponding to the second sending timestamp and the second sending timestamp from the difference between the receiving timestamp corresponding to the first sending timestamp and the first sending timestamp to obtain a fifth difference; divide the fifth difference by 2 to obtain the average of the fifth differences; and add the average of the fifth differences to the first error correction value to obtain the first time deviation between the first satellite and the corresponding second satellite.

[0155] In actual application, when the first satellite is satellite A and the second satellite is satellite B, the formula [(T reA1 -T sendB1 )-(T reB1 -T sendA1 )] / 2+γ1, calculate the first time offset between the first satellite and the corresponding second satellite. γ1 is the first error correction value. The first error correction value can be a set value or can be set according to actual conditions.

[0156] Considering that satellite motion may cause a change in the transmission delay between the first satellite and the second satellite, thereby introducing a time error, in order to improve the accuracy of the first time offset determined by the first satellite, in one embodiment, the first sending timestamp is the same as the second sending timestamp; or,

[0157] The difference between the first sending timestamp and the second sending timestamp is the minimum value among the third difference values; the third difference value is the difference between the sending timestamp of the first message and the sending timestamp of the second message.

[0158] Here, the first satellite selects the same first sending timestamp and second sending timestamp from the sending timestamps of the first message and the second message, or selects the first sending timestamp and second sending timestamp with the smallest third difference.

[0159] The first satellite and the second satellite in a connection relationship may be located in the same orbit. In one embodiment, the first satellite and the at least one second satellite are located in the same orbit, and the at least one second satellite is adjacent to the first satellite.

[0160] Here, the first satellite may periodically broadcast a first message and receive a second message periodically broadcast by a second satellite. The same second satellite may be located before or after the first satellite.

[0161] The first satellite and the second satellite having a connection relationship may be located in different orbits. In one embodiment, the first satellite and the at least one second satellite are located in different orbits; the first message and the second message are both transmitted during the period when the first satellite establishes a connection with the corresponding second satellite.

[0162] When the first satellite is equipped with a GNSS receiver, the local time of the first satellite tracks the GNSS time. Based on this, in one embodiment, the method further includes:

[0163] Receive GNSS time;

[0164] The local time of the first satellite is updated based on the GNSS time.

[0165] Here, the first satellite may receive GNSS time through a GNSS receiver of the first satellite, and update the local time of the first satellite based on the GNSS time, so that the local time of the first satellite tracks the GNSS time.

[0166] When the first satellite does not have a GNSS receiver, the local time is maintained according to the local time frequency. Based on this, in one embodiment, the method further includes:

[0167] In the event that the first satellite does not receive GNSS time, the local time of the first satellite is maintained according to the local time frequency.

[0168] Here, the local time of the first satellite is updated according to the local time frequency.

[0169] Correspondingly, an embodiment of the present disclosure further provides a method for inter-satellite time synchronization, which is applied to a second satellite. As shown in FIG2 , the method includes:

[0170] Step 201: Receive a first message sent by at least one first satellite.

[0171] The first message carries a sending timestamp.

[0172] Here, upon receiving the first message, the second satellite may record the first message's reception timestamp; may also associate or store the first message's reception timestamp with the first message's transmission timestamp. The second satellite is connected to the first satellite, and the number of first satellites connected to the second satellite is greater than or equal to one. In other words, the second satellite interacts with the first satellite only while the connection exists. Step 202: Send the first message and / or the second message to the at least one first satellite.

[0173] Here, as described above, the first information represents the relevant information of the first message. The second message may carry the relevant information of the first message, or may not carry the relevant information of the first message.

[0174] It should be noted that the second satellite can send the second message and the first information corresponding to the first message to the first satellite in parallel.

[0175] In one embodiment, the first information includes a first difference and / or a reception timestamp of the first message; the first difference represents a difference between the reception timestamp of the first message and a corresponding transmission timestamp.

[0176] Here, the second satellite determines a first difference corresponding to the first message based on a reception timestamp of the first message and a transmission timestamp carried by the first message, and generates first information corresponding to the first message based on the first difference and / or the reception timestamp of the first message.

[0177] In one embodiment, the second message carries a sending timestamp.

[0178] The sending timestamp of the second message is used by the first satellite to determine a first time offset between the first satellite and the second satellite.

[0179] In one embodiment, both the first message and the second message are periodic messages.

[0180] The second satellite may obtain the sending period of the first message from the first satellite. The sending period of the second message may be the same as or different from the sending period of the first message.

[0181] Since the second satellite can record the sending timestamp and receiving timestamp of each first message, in order to facilitate the second satellite to perform time synchronization, the first satellite can return the receiving timestamp and / or second difference corresponding to the second message sent by the second satellite to the second satellite. Based on this, in one embodiment, the method further includes:

[0182] receiving second information sent by the first satellite; wherein,

[0183] The second information includes a second difference and / or a receiving timestamp of the second message; the second difference represents a difference between the receiving timestamp of the second message and the corresponding sending timestamp.

[0184] Here, the second satellite may record or store the associated sending timestamp of each second message and the corresponding receiving timestamp. The second satellite may determine the receiving timestamp of the second message based on the second difference value included in the second information and the sending timestamp of the second message.

[0185] When the second satellite performs time synchronization, the second satellite may adjust or calibrate the local time of the second satellite based on the second time offset between the second satellite and the first satellite to improve the accuracy of the local time of the second satellite, so that the second satellite maintains time synchronization with the first satellite. Based on this, in one embodiment, the method further includes one of the following:

[0186] adjusting or calibrating the local time of the second satellite based on a second time offset between the second satellite and the first satellite;

[0187] When the number of first satellites is greater than or equal to 2, the local time of the second satellite is adjusted or calibrated based on a mean or a weighted average of second time offsets between the second satellite and different first satellites.

[0188] The second time offset is determined based on at least relevant information of the first message and relevant information of the second message sent by the first satellite.

[0189] Here, the second satellite determines a second time offset between the second satellite and the corresponding first satellite based on the relevant information of the second message and the relevant information of the first message sent by the first satellite. The relevant information of the first message includes the first message's transmission timestamp and the first information; the relevant information of the second message includes the second message's transmission timestamp and the second information. The first information has a one-to-one correspondence with the first message, and the second information has a one-to-one correspondence with the second message.

[0190] In a case where the number of first satellites having a connection relationship with the second satellite is 1, the local time of the second satellite is adjusted or calibrated based on a second time offset between the second satellite and the first satellite.

[0191] When the number of first satellites having a connection relationship with the second satellite is greater than or equal to two, a mean or weighted average of the second time offsets is determined based on second time offsets between the second satellite and different first satellites; and the local time of the second satellite is adjusted or calibrated based on the determined mean or weighted average. The different first satellites may be some or all of the first satellites having a connection relationship with the second satellite.

[0192] Before the second satellite performs time synchronization, it is necessary to first determine the second time offset between the second satellite and the first satellite. Based on this, in one embodiment, the method further includes:

[0193] A second time offset between the second satellite and the first satellite is determined based at least on a sending timestamp and / or a corresponding receiving timestamp of the first message and a sending timestamp and / or a corresponding receiving timestamp of the second message.

[0194] Here, the second satellite obtains the transmission timestamp and corresponding reception timestamp of the first message; determines the transmission timestamp and corresponding reception timestamp of the second message based on the transmission timestamp of the second message and the corresponding second information; and determines a second time offset between the second satellite and the corresponding first satellite based at least on the transmission timestamp and corresponding reception timestamp of the first message, and based on the transmission timestamp and corresponding reception timestamp of the second message; the corresponding first satellite is the first satellite that sent the first message. In this case, the first message and the second message may be periodic messages or non-periodic messages.

[0195] Of course, when both the first message and the second message are periodic messages, and the sending period of the second message is the same as the sending period of the first message, when the sending time of the second message within the same period is the same as the sending time of the first message, the second satellite can determine the first time offset between the second satellite and the first satellite based at least on the sending timestamp of the second message and the receiving timestamp of the first message; when the sending time of the second message within the same period is the same as the sending time of the first message, and the second satellite obtains the receiving timestamp of the second message, the second satellite can also determine the first time offset between the second satellite and the first satellite based at least on the sending timestamp of the first message and the receiving timestamp of the second message; when the sending time of the second message within the same period is different from the sending time of the first message, the second satellite can determine the first time offset between the second satellite and the first satellite based at least on the sending timestamp of the second message and the sending timestamp of the first message.

[0196] In order to improve the accuracy of the second time offset determined by the second satellite, in one embodiment, determining the second time offset between the second satellite and the first satellite includes:

[0197] Determine, based on the sending timestamp of the first message and / or the sending timestamp of the second message, a third sending timestamp of the first message and / or a fourth sending timestamp of the second message;

[0198] Determining a second time offset between the second satellite and the first satellite based on at least one of the following:

[0199] A third sending timestamp and a corresponding receiving timestamp;

[0200] A fourth sending timestamp and a corresponding receiving timestamp;

[0201] a second error correction value.

[0202] Here, the second satellite determines, from the transmission timestamps of the first message and / or the transmission timestamps of the second message, a third transmission timestamp of the first message and / or a fourth transmission timestamp of the second message that meet a condition. The condition includes at least that the third transmission timestamp and the fourth transmission timestamp are identical, closest to, or approximately equal to each other, and may also include that the difference between the third transmission timestamp and the corresponding reception timestamp is relatively close to, or approximately equal to, the difference between the fourth transmission timestamp and the corresponding reception timestamp.

[0203] For example, in the case where both the first message and the second message are periodic messages, when the sending time of the second message within the same period is the same as the sending time of the first message, for each period, a third sending timestamp is determined in the sending timestamp of the first message, and / or a fourth sending timestamp is determined in the sending timestamp of the second message; when the sending time of the second message within the same period is different from the sending time of the first message, for each period, a third sending timestamp and a fourth timestamp whose sending timestamps are closest to or approximately equal to each other are determined in the sending timestamp of the first message and the sending timestamp of the second message.

[0204] When the third sending timestamp of the first message is determined, the receiving timestamp corresponding to the third sending timestamp of the first message is determined based on the sending timestamp and the corresponding receiving timestamp of the first message; when the fourth sending timestamp of the second message is determined, the receiving timestamp corresponding to the fourth sending timestamp of the second message is determined based on the sending timestamp and the corresponding receiving timestamp of the second message.

[0205] After the second satellite determines the receiving timestamp corresponding to the third sending timestamp of the first message and the receiving timestamp corresponding to the fourth sending timestamp of the second message, the second satellite uses method one, method two, method three or method four to determine the first time offset between the second satellite and the first satellite.

[0206] Method 1:

[0207] A first time offset between the second satellite and the corresponding first satellite is determined based on the third sending timestamp and the corresponding receiving timestamp of the first message, or based on the fourth sending timestamp and the corresponding receiving timestamp of the second message.

[0208] For example, based on the difference or the absolute value of the difference between the third sending timestamp of the first message and the corresponding receiving timestamp, the first time offset between the second satellite and the corresponding first satellite is determined.

[0209] For another example, based on the difference or the absolute value of the difference between the fourth sending timestamp of the second message and the corresponding receiving timestamp, the first time offset between the second satellite and the corresponding first satellite is determined.

[0210] Method 2:

[0211] Based on the third sending timestamp and the corresponding receiving timestamp of the first message, and the second error correction value, a first time offset between the first satellite and the corresponding second satellite is determined; or, based on the fourth sending timestamp and the corresponding receiving timestamp of the second message, and the second error correction value, the first time offset between the second satellite and the corresponding first satellite is determined.

[0212] It should be noted that the second error correction value is used to compensate for the error caused by the time consumed by the data processing inside the second satellite. The second error correction value and the first error correction value may be the same or different.

[0213] Method 3:

[0214] A second time offset between the second satellite and the corresponding first satellite is determined based on the third sending timestamp and the corresponding receiving timestamp of the first message, and the fourth sending timestamp and the corresponding receiving timestamp of the second message.

[0215] For example, determine the third absolute value of the difference between the fourth sending timestamp and the corresponding receiving timestamp, and determine the fourth absolute value of the difference between the third sending timestamp and the corresponding receiving timestamp; subtract the fourth absolute value from the third absolute value to obtain the absolute value difference; divide the absolute value difference by 2 to obtain the second time deviation between the second satellite and the corresponding first satellite.

[0216] For another example, since the receiving timestamp of the same message is greater than the corresponding sending timestamp, the second satellite can subtract the difference between the receiving timestamp corresponding to the fourth sending timestamp and the fourth sending timestamp from the difference between the receiving timestamp corresponding to the third sending timestamp and the third sending timestamp to obtain a sixth difference; and divide the sixth difference by 2 to obtain a second time offset between the second satellite and the corresponding first satellite.

[0217] In actual application, when the first satellite is satellite A and the second satellite is satellite B, the formula [(T reA2 -T sendB2 )-(T reB2 -T sendA2 )] / 2, calculate the second time offset between the second satellite and the corresponding first satellite. Wherein, T sendA2 is the third sending timestamp of the first message, T reB2 is the receiving timestamp corresponding to the third sending timestamp of the first message; TsendB2 is the fourth sending timestamp of the second message, T reA2 It is the receiving timestamp corresponding to the fourth sending timestamp of the second message.

[0218] Method 4:

[0219] A first time offset between the first satellite and the corresponding second satellite is determined based on the third sending timestamp and the corresponding receiving timestamp of the first message, the fourth sending timestamp and the corresponding receiving timestamp of the second message, and the second error correction value.

[0220] For example, a third absolute value of the difference between a fourth transmission timestamp and a corresponding reception timestamp is determined, and a fourth absolute value of the difference between the third transmission timestamp and the corresponding reception timestamp is determined; the fourth absolute value is subtracted from the third absolute value to obtain an absolute value difference; the absolute value difference is divided by 2 to obtain a mean of the absolute values; the mean of the absolute values ​​is added to the second error correction value to obtain a second time deviation between the second satellite and the corresponding first satellite.

[0221] For another example, considering that the receiving timestamp of the same message is greater than the corresponding sending timestamp, the second satellite can subtract the difference between the receiving timestamp corresponding to the fourth sending timestamp and the fourth sending timestamp from the difference between the receiving timestamp corresponding to the third sending timestamp and the third sending timestamp to obtain a sixth difference; divide the sixth difference by 2 to obtain the average of the sixth differences; and add the average of the sixth differences to the second error correction value to obtain a second time offset between the second satellite and the corresponding first satellite.

[0222] In actual application, when the first satellite is satellite A and the second satellite is satellite B, the formula [(T reA2 -T sendB2 )-(T reB2 -T sendA2 )] / 2+γ2, calculate the first time offset between the first satellite and the corresponding second satellite. γ2 is the second error correction value. The second error correction value can be a set value or can be set according to actual conditions.

[0223] In order to improve the accuracy of the determined second time offset, in one embodiment,

[0224] The third sending timestamp is the same as the fourth sending timestamp; or,

[0225] The difference between the third sending timestamp and the fourth sending timestamp is the minimum value among the fourth difference values; the fourth difference value is the difference between the sending timestamp of the first message and the sending timestamp of the second message.

[0226] Here, the second satellite selects the same third sending timestamp and fourth sending timestamp from the sending timestamps of the first message and the sending timestamps of the second message, or selects the third sending timestamp and fourth sending timestamp with the smallest fourth difference.

[0227] The first satellite and the second satellite in a connection relationship may be located in the same orbit. In one embodiment, the at least one first satellite and the second satellite are located in the same orbit, and the second satellite is adjacent to the at least one first satellite.

[0228] Here, the second satellite may periodically broadcast the second message and receive the first message periodically broadcast by the first satellite. The same first satellite may be located before or after the second satellite.

[0229] The second satellite and the first satellite having a connection relationship may be located in different orbits. In one embodiment, the at least one first satellite and the second satellite are located in different orbits; the second message and the first message are both transmitted during the period when the second satellite establishes a connection with the corresponding first satellite.

[0230] When the second satellite is equipped with a GNSS receiver, the local time of the second satellite tracks the GNSS time. In one embodiment, the method further includes:

[0231] Receive GNSS time;

[0232] The local time of the second satellite is updated based on the GNSS time.

[0233] Here, the second satellite may receive GNSS time through a GNSS receiver of the second satellite, and update the local time of the second satellite based on the GNSS time, so that the local time of the second satellite tracks the GNSS time.

[0234] When the second satellite does not have a GNSS receiver, the local time is maintained according to the local time frequency. Based on this, in one embodiment, the method further includes:

[0235] In the event that the second satellite does not receive the GNSS time, the local time of the second satellite is maintained according to the local time frequency.

[0236] Here, the local time of the second satellite is updated according to the local time frequency.

[0237] The present disclosure is further described in detail below with reference to application examples.

[0238] For satellites in the same orbit, each satellite periodically synchronizes time with the satellites preceding and following it. The specific implementation process is shown in steps 1 to 4. For satellites in different orbits, satellites interact and synchronize time according to steps 1 to 4 during the establishment of a connection.

[0239] Step 1: Each satellite periodically sends a first message to the satellite with which it has a connection. The first message carries a sending timestamp T send After receiving the first message, the satellite at the opposite end records the receiving timestamp T of the first message. re At the same time, the opposite satellite also periodically sends a second message to the satellite. Similarly, the second message carries a sending timestamp.

[0240] For example, as shown in FIG3 , satellite A has a connection relationship with satellite B and satellite C. Satellite A sends a first message to satellite B and satellite C respectively. The first message carries a sending timestamp T of the first message. sendA When satellite B receives the first message, it records the receiving timestamp T of the first message. reB When satellite C receives the first message, it records the reception timestamp T of the first message. reC .

[0241] Satellite B sends a second message to satellite A, and the second message carries the sending timestamp T of the second message. sendB When satellite A receives the second message sent by satellite B, it records the receiving timestamp T of the second message. reA-B .

[0242] Satellite C sends a second message to satellite A. The second message carries the sending timestamp T of the second message. sendC When satellite A receives the second message sent by satellite B, it records the receiving timestamp T of the second message. reA-C .

[0243] Step 2: When each satellite receives any message, it records the receiving timestamp T of the message. re , the message's (T re -T send ) and / or T re Sent to the sender of the message (here you can also send the T send and T re In short, we can conclude that (T re -T send ) and T re In this way, each satellite can obtain the first message (T re -T send ) and the second message (T re -Tsend ).

[0244] For example, in FIG3 , for the second message sent by satellite B to satellite A, satellite A can calculate (T reA-B -T sendB ), (T reA-B -T sendB ) and / or T reA-B Send to satellite B. For the second message sent by satellite C to satellite A, satellite A can calculate (T reA-C -T sendC ), (T reA-C -T sendC ) and / or T reA-C Sent to satellite C.

[0245] For another example, for the first message sent by satellite A to satellite B, satellite B can calculate (T reB -T sendA ), (T reB -T sendA ) and / or T reB Sent to satellite A.

[0246] For another example, for the first message sent by satellite A to satellite C, satellite C can calculate (T reC -T sendA ), (T reC -T sendA ) and / or T reC Sent to satellite A.

[0247] Step 3: Each satellite is based on the first message (T re -T send ) and the second message (T re -T send ) to calculate the time offset between itself and the other satellite.

[0248] In Figure 3, satellite A can be based on (T reA-B -T sendB ) and (T reB -T sendA ), calculate the time deviation between satellite A and satellite B; satellite A can be based on (T reA-C -T sendC ) and (T reC -T sendA ), calculate the time offset between satellite A and satellite C. Satellite B can be based on (T reB -T sendA ) and (T reA-B -T sendB ), calculate the time offset between satellite B and satellite A. Satellite C can be based on (TreC -T sendA ) and (T reA-C -T sendC ), calculate the time offset between satellite C and satellite A.

[0249] In actual application, the following formula is used to calculate the time deviation between the satellite and the other end.

[0250] [The first message (T re -T send )-(T of the second message re -T send )] / 2+error correction value.

[0251] Among them, the first message used to calculate the time deviation (T re -T send ) and the second message (T re -T send ), obtained by:

[0252] In the sending timestamp of the first message and the sending timestamp of the second message, the T of the first message that meets the set conditions is selected. send and T of the second message send For example, select the T of the first message with the same time send and T of the second message send Or, based on the difference between the sending timestamp of the first message and the sending timestamp of the second message, select the T of the first message with the smallest difference send and T of the second message send .

[0253] For example, when satellite B calculates the time offset between satellite B and satellite A, the T of the second message sent by satellite B is sendB and T of the first message sent by satellite A sendA Same, or T sendB With T sendA The difference between .

[0254] Step 4: Each satellite adjusts or calibrates its own local time based on the determined time offset.

[0255] In the case where any satellite has a connection relationship with only one satellite, the satellite adjusts or calibrates the local time of the satellite based on the time offset between the satellite and the one satellite with the connection relationship.

[0256] When any satellite has a connection relationship with at least two satellites, the satellite determines the time offset between the satellite and different satellites, and adjusts or calibrates the local time of the satellite based on the average or weighted average of the time offsets between the satellite and different satellites.

[0257] For example, in Figure 3, satellites B and C each have only one connected satellite A. Therefore, satellite B adjusts its local time based on the time offset between satellite B and satellite A; satellite C adjusts its local time based on the time offset between satellite C and satellite A.

[0258] For another example, in Figure 3, satellite B and satellite C are both connected to satellite A. Satellite A calculates a mean or weighted average based on the time deviation between satellite A and satellite B, and the time deviation between satellite A and satellite C; and adjusts the local time of satellite A based on the mean or weighted average.

[0259] Step 5: Some of the satellites in the network may be equipped with GNSS receivers to receive GNSS time. The local time of the satellites receiving GNSS time tracks the GNSS time, and the time deviation obtained according to steps 1 to 3 is used to adjust or calibrate the local time.

[0260] Step 6: For satellites without GNSS receivers, maintain the local time of the satellite according to the local time frequency, and use the time offset obtained in steps 1 to 3 to periodically adjust or calibrate the local time.

[0261] After each satellite obtains these error values ​​from surrounding satellites, it adjusts the local value after taking the weighted average of all error values.

[0262] In the inter-satellite time synchronization method, device, satellite, and storage medium provided by the embodiments of the present disclosure, a first satellite sends a first message to at least one second satellite; the first message carries a sending timestamp; the second satellite receives the first message sent by at least one first satellite and sends a first message and / or a second message to the at least one first satellite; the first satellite receives the first message and / or the second message sent by the at least one second satellite. In the above scheme, the first message and the second message are sent in parallel, which can avoid the change in transmission delay caused by multiple serial interactions and multiple handshakes that consume a lot of time, so that when the first satellite and / or the second satellite perform time synchronization, accurate time synchronization information can be obtained, thereby improving the accuracy of the time synchronization information. There is no master-slave relationship between the first satellite and the second satellite, which solves the problem of unstable satellite network topology and the inability to establish master-slave synchronization for a long time.

[0263] In order to implement the inter-satellite time synchronization method of the embodiment of the present disclosure, the embodiment of the present disclosure further provides an inter-satellite time synchronization device, which is provided on the first satellite, as shown in FIG4 , and includes:

[0264] The first sending unit 401 is configured to send a first message to at least one second satellite; the first message carries a sending timestamp;

[0265] The first receiving unit 402 is configured to receive the first information and / or the second message sent by the at least one second satellite.

[0266] In one embodiment, the first information includes a first difference and / or a reception timestamp of the first message; the first difference represents a difference between the reception timestamp of the first message and a corresponding transmission timestamp.

[0267] In one embodiment, the second message carries a sending timestamp.

[0268] In one embodiment, the apparatus further comprises:

[0269] The third sending unit is used to send corresponding second information to the at least one second satellite; wherein the second information includes a second difference and / or a receiving timestamp of the second message; the second difference represents the difference between the receiving timestamp of the second message and the corresponding sending timestamp.

[0270] In one embodiment, the apparatus further includes a first processing unit configured to perform one of the following:

[0271] adjusting or calibrating the local time of the first satellite based on a first time offset between the first satellite and a second satellite;

[0272] When the number of second satellites is greater than or equal to 2, the local time of the first satellite is adjusted or calibrated based on a mean or a weighted average of first time offsets between the first satellite and different second satellites.

[0273] In one embodiment, the apparatus further comprises:

[0274] The first determining unit is configured to determine a first time offset between the first satellite and the second satellite based at least on a sending timestamp and / or a corresponding receiving timestamp of the first message and a sending timestamp and / or a corresponding receiving timestamp of the second message.

[0275] In one embodiment, the first determining unit is specifically configured to:

[0276] Determine a first sending timestamp of the first message and / or a second sending timestamp of the second message based on the sending timestamp of the first message and / or the sending timestamp of the second message;

[0277] Determining a first time offset between the first satellite and the second satellite based on at least one of the following:

[0278] A first sending timestamp and a corresponding receiving timestamp;

[0279] A second sending timestamp and a corresponding receiving timestamp;

[0280] A first error correction value.

[0281] In one embodiment, the first sending timestamp is the same as the second sending timestamp; or,

[0282] The difference between the first sending timestamp and the second sending timestamp is the minimum value among the third difference values; the third difference value is the difference between the sending timestamp of the first message and the sending timestamp of the second message.

[0283] In one embodiment, both the first message and the second message are periodic messages.

[0284] In one embodiment, the first satellite and the at least one second satellite are located in the same orbit, and the at least one second satellite is adjacent to the first satellite.

[0285] In one embodiment, the first satellite and the at least one second satellite are located in different orbits; the first message and the second message are both transmitted during a period in which the first satellite establishes a connection with the corresponding second satellite.

[0286] In one embodiment, the apparatus further comprises:

[0287] A third receiving unit, configured to receive GNSS time;

[0288] A first updating unit is configured to update the local time of the first satellite based on the GNSS time.

[0289] In one embodiment, the apparatus further comprises:

[0290] The second updating unit is configured to maintain the local time of the first satellite according to the local time frequency when the first satellite does not receive the GNSS time.

[0291] In actual application, the first sending unit 401, the first receiving unit 402, the third sending unit and the third receiving unit can be implemented by a processor in the inter-satellite time synchronization device in combination with a communication interface; the first processing unit, the first determination unit, the first updating unit and the second updating unit can be implemented by a processor in the inter-satellite time synchronization device.

[0292] It should be noted that the inter-satellite time synchronization apparatus provided in the above embodiment is merely illustrated by the division of the aforementioned program modules when performing inter-satellite time synchronization. In actual applications, the aforementioned processing can be assigned to different program modules as needed, i.e., the internal structure of the apparatus can be divided into different program modules to perform all or part of the aforementioned processing. Furthermore, the inter-satellite time synchronization apparatus and the inter-satellite time synchronization method provided in the above embodiment are based on the same concept. The specific implementation process is detailed in the method embodiment and will not be further described here.

[0293] In order to implement the inter-satellite time synchronization method of the embodiment of the present disclosure, the embodiment of the present disclosure further provides an inter-satellite time synchronization device, which is provided on the second satellite, as shown in FIG5 , and includes:

[0294] The second receiving unit 501 is configured to receive a first message sent by at least one first satellite; the first message carries a sending timestamp;

[0295] The second sending unit 502 is configured to send the first information and / or the second message to the at least one first satellite.

[0296] In one embodiment, the first information includes a first difference and / or a reception timestamp of the first message; the first difference represents a difference between the reception timestamp of the first message and a corresponding transmission timestamp.

[0297] In one embodiment, the second message carries a sending timestamp; and the second satellite is connected to the first satellite.

[0298] In one embodiment, the apparatus further comprises:

[0299] The fourth receiving unit is configured to receive the second information sent by the first satellite; wherein,

[0300] The second information includes a second difference and / or a receiving timestamp of the second message; the second difference represents a difference between the receiving timestamp of the second message and the corresponding sending timestamp.

[0301] In one embodiment, the apparatus further includes a second processing unit configured to perform one of the following:

[0302] adjusting or calibrating the local time of the second satellite based on a second time offset between the second satellite and the first satellite;

[0303] When the number of first satellites is greater than or equal to 2, the local time of the second satellite is adjusted or calibrated based on a mean or a weighted average of second time offsets between the second satellite and different first satellites.

[0304] In one embodiment, the apparatus further comprises:

[0305] The second determining unit is configured to determine a second time offset between the second satellite and the first satellite based at least on a sending timestamp and / or a corresponding receiving timestamp of the first message and a sending timestamp and / or a corresponding receiving timestamp of the second message.

[0306] In one embodiment, the second determining unit is specifically configured to:

[0307] Determine, based on the sending timestamp of the first message and / or the sending timestamp of the second message, a third sending timestamp of the first message and / or a fourth sending timestamp of the second message;

[0308] Determining a second time offset between the second satellite and the first satellite based on at least one of the following:

[0309] A third sending timestamp and a corresponding receiving timestamp;

[0310] A fourth sending timestamp and a corresponding receiving timestamp;

[0311] a second error correction value.

[0312] In one embodiment, the third sending timestamp is the same as the fourth sending timestamp; or,

[0313] The difference between the third sending timestamp and the fourth sending timestamp is the minimum value among the fourth difference values; the fourth difference value is the difference between the sending timestamp of the first message and the sending timestamp of the second message.

[0314] In one embodiment, both the first message and the second message are periodic messages.

[0315] In one embodiment, the at least one first satellite and the second satellite are located in the same orbit, and the second satellite is adjacent to the at least one first satellite.

[0316] In one embodiment, the at least one first satellite and the second satellite are located in different orbits; and the second message and the first message are both transmitted during a period in which the second satellite establishes a connection with the corresponding first satellite.

[0317] In one embodiment, the apparatus further comprises:

[0318] A fourth receiving unit, configured to receive GNSS time;

[0319] A third updating unit is configured to update the local time of the second satellite based on the GNSS time.

[0320] In one embodiment, the apparatus further comprises:

[0321] The fourth updating unit is configured to maintain the local time of the second satellite according to the local time frequency when the second satellite does not receive the GNSS time.

[0322] In actual application, the second receiving unit 501, the second sending unit 502, the fourth receiving unit and the fourth receiving unit can be implemented by a processor in the inter-satellite time synchronization device in combination with a communication interface; the second processing unit, the second determination unit, the third updating unit and the fourth updating unit can be implemented by a processor in the inter-satellite time synchronization device.

[0323] It should be noted that the inter-satellite time synchronization apparatus provided in the above embodiment is merely an example of the division of the program modules described above when performing inter-satellite time synchronization. In actual applications, the above processing can be assigned to different program modules as needed, that is, the internal structure of the apparatus can be divided into different program modules to complete all or part of the above-described processing. Furthermore, the inter-satellite time synchronization apparatus provided in the above embodiment and the inter-satellite time synchronization method embodiment are based on the same concept. The specific implementation process is detailed in the method embodiment and will not be repeated here.

[0324] Based on the hardware implementation of the above program modules and in order to implement the method on the first satellite side of the embodiment of the present disclosure, the embodiment of the present disclosure further provides a first satellite, as shown in FIG6 , wherein the first satellite 600 includes:

[0325] The first communication interface 601 is capable of exchanging information with other network nodes;

[0326] The first processor 602 is connected to the first communication interface 601 to implement information exchange with other network nodes and is configured to execute the methods provided by one or more technical solutions of the first satellite side when running a computer program. The computer program is stored in the first memory 603.

[0327] Specifically, the first communication interface 601 is used to send a first message to at least one second satellite, and receive first information and / or a second message sent by the at least one second satellite; wherein the first message carries a sending timestamp.

[0328] In one embodiment, the first information includes a first difference and / or a reception timestamp of the first message; the first difference represents a difference between the reception timestamp of the first message and a corresponding transmission timestamp.

[0329] In one embodiment, the second message carries a sending timestamp.

[0330] In one embodiment, the first communication interface 601 is further configured to send corresponding second information to the at least one second satellite; wherein the second information includes a second difference and / or a receiving timestamp of the second message; and the second difference represents a difference between the receiving timestamp of the second message and the corresponding sending timestamp.

[0331] In one embodiment, the first processor 602 is configured to perform one of the following:

[0332] adjusting or calibrating the local time of the first satellite based on a first time offset between the first satellite and a second satellite;

[0333] When the number of second satellites is greater than or equal to 2, the local time of the first satellite is adjusted or calibrated based on a mean or a weighted average of first time offsets between the first satellite and different second satellites.

[0334] In one embodiment, the first processor 602 is further configured to determine a first time offset between the first satellite and the second satellite based at least on a sending timestamp and / or a corresponding receiving timestamp of the first message, and a sending timestamp and / or a corresponding receiving timestamp of the second message.

[0335] In one embodiment, the first processor 602 is specifically configured to:

[0336] Determine a first sending timestamp of the first message and / or a second sending timestamp of the second message based on the sending timestamp of the first message and / or the sending timestamp of the second message;

[0337] Determining a first time offset between the first satellite and the second satellite based on at least one of the following:

[0338] A first sending timestamp and a corresponding receiving timestamp;

[0339] A second sending timestamp and a corresponding receiving timestamp;

[0340] A first error correction value.

[0341] In one embodiment, the first sending timestamp is the same as the second sending timestamp; or,

[0342] The difference between the first sending timestamp and the second sending timestamp is the minimum value among the third difference values; the third difference value is the difference between the sending timestamp of the first message and the sending timestamp of the second message.

[0343] In one embodiment, both the first message and the second message are periodic messages.

[0344] In one embodiment, the first satellite and the at least one second satellite are located in the same orbit, and the at least one second satellite is adjacent to the first satellite.

[0345] In one embodiment, the first satellite and the at least one second satellite are located in different orbits; the first message and the second message are both transmitted during a period in which the first satellite establishes a connection with the corresponding second satellite.

[0346] In one embodiment, the first communication interface 601 is further configured to receive GNSS time;

[0347] The first processor 602 is further configured to update the local time of the first satellite based on the GNSS time.

[0348] In one embodiment, the first processor 602 is further configured to maintain the local time of the first satellite according to the local time frequency when the first satellite does not receive the GNSS time.

[0349] It should be noted that the specific processing process of the first processor 602 and the first communication interface 601 can be understood by referring to the above method.

[0350] In practice, the various components within first satellite 600 are coupled together via bus system 604. It will be appreciated that bus system 604 is used to enable communication between these components. In addition to a data bus, bus system 604 also includes a power bus, a control bus, and a status signal bus. However, for clarity, all of these buses are labeled as bus system 604 in FIG. 6 .

[0351] The first memory 603 in the embodiment of the present disclosure is used to store various types of data to support the operation of the first satellite 600. Examples of such data include any computer program used to operate on the first satellite 600.

[0352] The methods disclosed in the above embodiments of the present disclosure can be applied to the first processor 602 or implemented by the first processor 602. The first processor 602 may be an integrated circuit chip with signal processing capabilities. During implementation, each step of the above method can be completed by hardware integrated logic circuits or software instructions in the first processor 602. The above first processor 602 may be a general-purpose processor, a digital signal processor (DSP), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The first processor 602 can implement or execute the various methods, steps, and logic block diagrams disclosed in the embodiments of the present disclosure. A general-purpose processor may be a microprocessor or any conventional processor. The steps of the methods disclosed in conjunction with the embodiments of the present disclosure can be directly implemented and executed by a hardware decoding processor, or by a combination of hardware and software modules in the decoding processor. The software module may be located in a storage medium located in the first memory 603. The first processor 602 reads information in the first memory 603 and, in conjunction with its hardware, completes the steps of the above method.

[0353] In an exemplary embodiment, the first satellite 600 can be implemented by one or more application-specific integrated circuits (ASICs), DSPs, programmable logic devices (PLDs), complex programmable logic devices (CPLDs), field-programmable gate arrays (FPGAs), general-purpose processors, controllers, microcontrollers (MCUs), microprocessors, or other electronic components to perform the aforementioned method.

[0354] Based on the hardware implementation of the above program modules, and in order to implement the method on the second satellite side of the embodiment of the present disclosure, the embodiment of the present disclosure further provides a second satellite, as shown in FIG7 , wherein the second satellite 700 includes:

[0355] The second communication interface 701 is capable of exchanging information with other network nodes;

[0356] The second processor 702 is connected to the second communication interface 701 to implement information exchange with other network nodes and is configured to execute the methods provided by one or more technical solutions of the second satellite side when running a computer program. The computer program is stored in the second memory 703.

[0357] Specifically, the second communication interface 701 is used to receive a first message sent by at least one first satellite, and to send first information and a second message to the at least one first satellite; wherein the first message carries a sending timestamp.

[0358] In one embodiment, the first information includes a first difference and / or a reception timestamp of the first message; the first difference represents a difference between the reception timestamp of the first message and a corresponding transmission timestamp.

[0359] In one embodiment, the second message carries a sending timestamp.

[0360] In one embodiment, the second communication interface 701 is further configured to receive second information sent by the first satellite;

[0361] The second information includes a second difference and / or a receiving timestamp of the second message; the second difference represents a difference between the receiving timestamp of the second message and the corresponding sending timestamp.

[0362] In one embodiment, the second processor 702 is configured to perform one of the following:

[0363] adjusting or calibrating the local time of the second satellite based on a second time offset between the second satellite and the first satellite;

[0364] When the number of first satellites is greater than or equal to 2, the local time of the second satellite is adjusted or calibrated based on a mean or a weighted average of second time offsets between the second satellite and different first satellites.

[0365] In one embodiment, the second processor 702 is further configured to determine a second time offset between the second satellite and the first satellite based at least on a sending timestamp and / or a corresponding receiving timestamp of the first message, and a sending timestamp and / or a corresponding receiving timestamp of the second message.

[0366] In one embodiment, the second processor 702 is specifically configured to:

[0367] Determine, based on the sending timestamp of the first message and / or the sending timestamp of the second message, a third sending timestamp of the first message and / or a fourth sending timestamp of the second message;

[0368] Determining a second time offset between the second satellite and the first satellite based on at least one of the following:

[0369] A third sending timestamp and a corresponding receiving timestamp;

[0370] A fourth sending timestamp and a corresponding receiving timestamp;

[0371] a second error correction value.

[0372] In one embodiment, the third sending timestamp is the same as the fourth sending timestamp; or,

[0373] The difference between the third sending timestamp and the fourth sending timestamp is the minimum value among the fourth difference values; the fourth difference value is the difference between the sending timestamp of the first message and the sending timestamp of the second message.

[0374] In one embodiment, both the first message and the second message are periodic messages.

[0375] In one embodiment, the at least one first satellite and the second satellite are located in the same orbit, and the second satellite is adjacent to the at least one first satellite.

[0376] In one embodiment, the at least one first satellite and the second satellite are located in different orbits; and the second message and the first message are both transmitted during a period in which the second satellite establishes a connection with the corresponding first satellite.

[0377] In one embodiment, the apparatus further comprises:

[0378] The second communication interface 701 is further configured to receive GNSS time;

[0379] The second processor 702 is further configured to update the local time of the second satellite based on the GNSS time.

[0380] In one embodiment, the apparatus further comprises:

[0381] The second processor 702 further maintains the local time of the second satellite according to the local time frequency when the second satellite does not receive the GNSS time.

[0382] It should be noted that the specific processing procedures of the second processor 702 and the second communication interface 701 can be understood with reference to the above method.

[0383] In practice, the various components within second satellite 700 are coupled together via bus system 704. It will be appreciated that bus system 704 is used to enable communication between these components. In addition to a data bus, bus system 704 also includes a power bus, a control bus, and a status signal bus. However, for clarity, all of these buses are labeled as bus system 704 in FIG. 7 .

[0384] The second memory 703 in the embodiment of the present disclosure is used to store various types of data to support the operation of the second satellite 700. Examples of such data include any computer program used to operate on the second satellite 700.

[0385] The methods disclosed in the above embodiments of the present disclosure can be applied to or implemented by the second processor 702. The second processor 702 may be an integrated circuit chip with signal processing capabilities. During implementation, each step of the above method can be completed by hardware integrated logic circuits or software instructions in the second processor 702. The above second processor 702 may be a general-purpose processor, a DSP, or other programmable logic device, a discrete gate or transistor logic device, a discrete hardware component, etc. The second processor 702 can implement or execute the various methods, steps, and logic block diagrams disclosed in the embodiments of the present disclosure. A general-purpose processor may be a microprocessor or any conventional processor. The steps of the methods disclosed in the embodiments of the present disclosure can be directly implemented and executed by a hardware decoding processor, or by a combination of hardware and software modules in the decoding processor. The software modules may be located in a storage medium located in the second memory 703. The second processor 702 reads information from the second memory 703 and, in conjunction with its hardware, completes the steps of the above method.

[0386] In an exemplary embodiment, the second satellite 700 may be implemented by one or more ASICs, DSPs, PLDs, CPLDs, FPGAs, general-purpose processors, controllers, MCUs, Microprocessors, or other electronic components to perform the aforementioned methods.

[0387] It can be understood that the memory (first memory 603, second memory 703) of the embodiment of the present disclosure can be a volatile memory or a non-volatile memory, and can also include both volatile and non-volatile memories. Among them, the non-volatile memory can be a read-only memory (ROM), a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), an electrically erasable programmable read-only memory (EEPROM), a magnetic random access memory (FRAM), a flash memory, a magnetic surface memory, an optical disc, or a compact disc read-only memory (CD-ROM); the magnetic surface memory can be a disk memory or a tape memory. The volatile memory can be a random access memory (RAM), which is used as an external cache. By way of example and not limitation, many forms of RAM are available, such as Static Random Access Memory (SRAM), Synchronous Static Random Access Memory (SSRAM), Dynamic Random Access Memory (DRAM), Synchronous Dynamic Random Access Memory (SDRAM), Double Data Rate Synchronous Dynamic Random Access Memory (DDRSDRAM), Enhanced Synchronous Dynamic Random Access Memory (ESDRAM), SyncLink Dynamic Random Access Memory (SLDRAM), and Direct Rambus Random Access Memory (DRRAM).The memories described in the embodiments of the present disclosure are intended to include, but are not limited to, these and any other suitable types of memories.

[0388] In an exemplary embodiment, the present disclosure further provides a storage medium, namely, a computer storage medium, specifically, a computer-readable storage medium. For example, the storage medium includes a first memory 603 storing a computer program. The computer program can be executed by the first processor 602 of the first satellite 600 to perform the steps of the first satellite-side method described above. Another example includes a second memory 703 storing a computer program. The computer program can be executed by the second processor 702 of the second satellite 700 to perform the steps of the second satellite-side method described above. The computer-readable storage medium can be a memory such as FRAM, ROM, PROM, EPROM, EEPROM, Flash Memory, magnetic surface mount storage, optical disk, or CD-ROM.

[0389] It should be noted that: "first", "second", etc. are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence.

[0390] The term "and / or" as used herein simply describes an association relationship between associated objects, indicating that three possible relationships exist. For example, "A and / or B" can represent the existence of A alone, the simultaneous existence of A and B, and the existence of B alone. Furthermore, the term "at least one" as used herein refers to any combination of at least two of any one or more of a plurality. For example, "at least one of A, B, and C" can represent any one or more elements selected from the set consisting of A, B, and C.

[0391] In addition, the technical solutions described in the embodiments of the present disclosure can be arbitrarily combined without conflict.

[0392] The above description is merely a preferred embodiment of the present disclosure and is not intended to limit the scope of protection of the present disclosure.

Claims

1. A method for inter-satellite time synchronization, applied to a first satellite, the method comprising: sending a first message to at least one second satellite; The first message carries a sending timestamp; Receive the first information and / or the second message sent by the at least one second satellite.

2. The method according to claim 1, wherein The first information includes a first difference and / or a reception timestamp of the first message; the first difference represents a difference between the reception timestamp of the first message and a corresponding transmission timestamp.

3. The method according to claim 1, wherein The second message carries a sending timestamp.

4. The method according to claim 1, further comprising: Send corresponding second information to the at least one second satellite; wherein the second information includes a second difference and / or a receiving timestamp of the second message; the second difference represents a difference between the receiving timestamp of the second message and the corresponding sending timestamp.

5. The method according to claim 1, further comprising one of the following: adjusting or calibrating the local time of the first satellite based on a first time offset between the first satellite and a second satellite; When the number of second satellites is greater than or equal to 2, the local time of the first satellite is adjusted or calibrated based on a mean or a weighted average of first time offsets between the first satellite and different second satellites.

6. The method according to any one of claims 1 to 5, further comprising: A first time offset between the first satellite and the second satellite is determined based at least on a sending timestamp and / or a corresponding receiving timestamp of the first message and a sending timestamp and / or a corresponding receiving timestamp of the second message.

7. The method according to claim 6, wherein: The determining a first time offset between the first satellite and the second satellite includes: Determine a first sending timestamp of the first message and / or a second sending timestamp of the second message based on the sending timestamp of the first message and / or the sending timestamp of the second message; Determining a first time offset between the first satellite and the second satellite based on at least one of the following: A first sending timestamp and a corresponding receiving timestamp; A second sending timestamp and a corresponding receiving timestamp; A first error correction value.

8. The method according to claim 7, wherein: The first sending timestamp is the same as the second sending timestamp; or, The difference between the first sending timestamp and the second sending timestamp is the minimum value among the third difference values; the third difference value is the difference between the sending timestamp of the first message and the sending timestamp of the second message.

9. The method according to claim 1, wherein: Both the first message and the second message are periodic messages.

10. The method according to any one of claims 1 to 5, 7 to 9, wherein: The first satellite and the at least one second satellite are located in the same orbit, and the at least one second satellite is adjacent to the first satellite.

11. The method according to any one of claims 1 to 5 and 7 to 9, wherein: The first satellite and the at least one second satellite are located in different orbits; the first message and the second message are both transmitted during a period in which the first satellite establishes a connection with the corresponding second satellite.

12. The method according to any one of claims 1 to 5, 7 to 9, further comprising: Receive Global Navigation Satellite System GNSS time; The local time of the first satellite is updated based on the GNSS time.

13. The method according to any one of claims 1 to 5, 7 to 9, further comprising: In the event that the first satellite does not receive GNSS time, the local time of the first satellite is maintained according to the local time frequency.

14. A method for inter-satellite time synchronization, applied to a second satellite, the method comprising: receiving a first message sent by at least one first satellite; The first message carries a sending timestamp; Sending the first information and / or the second message to the at least one first satellite.

15. The method according to claim 14, wherein The first information includes a first difference and / or a reception timestamp of the first message; the first difference represents a difference between the reception timestamp of the first message and a corresponding transmission timestamp.

16. The method according to claim 14, wherein The second message carries a sending timestamp.

17. The method according to claim 14, further comprising: receiving second information sent by the first satellite; wherein, The second information includes a second difference and / or a receiving timestamp of the second message; the second difference represents a difference between the receiving timestamp of the second message and the corresponding sending timestamp.

18. The method according to claim 17, further comprising one of the following: adjusting or calibrating the local time of the second satellite based on a second time offset between the second satellite and the first satellite; When the number of first satellites is greater than or equal to 2, the local time of the second satellite is adjusted or calibrated based on a mean or a weighted average of second time offsets between the second satellite and different first satellites.

19. The method according to any one of claims 14 to 18, further comprising: A second time offset between the second satellite and the first satellite is determined based at least on a sending timestamp and / or a corresponding receiving timestamp of the first message and a sending timestamp and / or a corresponding receiving timestamp of the second message.

20. The method according to claim 19, wherein The determining a second time offset between the second satellite and the first satellite comprises: Determine, based on the sending timestamp of the first message and / or the sending timestamp of the second message, a third sending timestamp of the first message and / or a fourth sending timestamp of the second message; Determining a second time offset between the second satellite and the first satellite based on at least one of the following: A third sending timestamp and a corresponding receiving timestamp; A fourth sending timestamp and a corresponding receiving timestamp; a second error correction value.

21. The method according to claim 20, wherein The third sending timestamp is the same as the fourth sending timestamp; or, The difference between the third sending timestamp and the fourth sending timestamp is the minimum value among the fourth difference values; the fourth difference value is the difference between the sending timestamp of the first message and the sending timestamp of the second message.

22. The method according to claim 14, wherein Both the first message and the second message are periodic messages.

23. The method according to any one of claims 14 to 18, 20 to 22, wherein: The at least one first satellite and the second satellite are located in the same orbit, and the second satellite is adjacent to the at least one first satellite.

24. The method according to any one of claims 14 to 18, 20 to 22, wherein: The at least one first satellite and the second satellite are located in different orbits; the second message and the first message are both transmitted during a period when the second satellite establishes a connection with the corresponding first satellite.

25. The method according to any one of claims 14 to 18, 20 to 22, further comprising: Receive GNSS time; The local time of the second satellite is updated based on the GNSS time.

26. The method according to any one of claims 14 to 18, 20 to 22, further comprising: In the event that the second satellite does not receive the GNSS time, the local time of the second satellite is maintained according to the local time frequency.

27. An inter-satellite time synchronization device, comprising: A first sending unit, configured to send a first message to at least one second satellite; The first message carries a sending timestamp; The first receiving unit is configured to receive the first information and / or the second message sent by the at least one second satellite.

28. An inter-satellite time synchronization device, comprising: A second receiving unit, configured to receive a first message sent by at least one first satellite; The first message carries a sending timestamp; The second sending unit is configured to send the first information and / or the second message to the at least one first satellite.

29. A first satellite comprising a first processor and a first communication interface, wherein: The first communication interface is used to send a first message to at least one second satellite and receive the first information and / or second message sent by the at least one second satellite; wherein, The first message carries a sending timestamp.

30. A second satellite comprising a second processor and a second communication interface, wherein: The second communication interface is used to receive a first message sent by at least one first satellite, and send first information and / or a second message to the at least one first satellite; wherein, The first message carries a sending timestamp.

31. A satellite comprising a processor and a memory for storing a computer program capable of being executed on the processor, in, When the processor is used to run the computer program, it executes the steps of the method according to any one of claims 1 to 13, or executes the steps of the method according to any one of claims 14 to 26.

32. A storage medium having a computer program stored thereon, wherein when the computer program is executed by a processor, the computer program implements the steps of the method according to any one of claims 1 to 13, or implements the steps of the method according to any one of claims 14 to 26.

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