Autonomous station switching method and system for satellite data transmission

Abstract

The invention relates to a satellite data transmission autonomous station switching method and system, and the method comprises the steps: S1, obtaining autonomous station switching parameters, and carrying out the state setting before data transmission, the autonomous station switching parameters comprising a transmission sequence of a ground station, and a transmission time envelope and station switching time corresponding to the ground station, the transmission time envelope comprises starting time and ending time of ground station transmission; s2, satellite star time, satellite attitude information and satellite position information are obtained in real time, the off-axis angle of the ground station is calculated, the satellite position information comprises the satellite position corresponding to the current moment and one extrapolated switching time, and the satellite attitude information comprises the satellite attitude corresponding to the current moment and one extrapolated switching time; and S3, carrying out data transmission and station switching operation according to the ground station transmission sequence and a station switching rule based on an off-axis angle and station switching time requirements. The method can effectively solve the problem that the satellite multi-station data transmission needs complex ground planning in advance, so that the satellite can autonomously complete the multi-station relay data transmission work.

Description

Technical Field

[0001] The present invention relates to the technical field of satellite on-orbit data transmission, and particularly to a method for autonomous ground station switching of satellite data transmission. Background Art

[0002] In recent years, with the development of the space industry, satellite technology has become increasingly mature, the working hours of satellite payloads have been increasing day by day, and the amount of data generated in orbit is huge. When a satellite passes by every day, the amount of payload data to be transmitted is huge. Often, the receiving time of 1 ground station is not enough, which seriously affects the working efficiency of satellite on-orbit operation and control. Therefore, it is crucial for a satellite to have the ability of multi-station relay for data transmission. However, since the conventional multi-station relay for satellite data transmission requires multiple ground data transmission resources to be planned on the ground, and according to the satellite data transmission ground station switching strategy, the specific ground station switching time is determined, and then a program control instruction is generated and uploaded to the satellite and other series of cumbersome ground operation and control work, so during the on-orbit operation stage of the satellite, the frequency of using multi-station relay of the satellite is not high, resulting in less data transmission time and less data transmission volume of the satellite within a fixed time.

[0003] For example, a method and system for optimizing the data transmission guiding time based on multi-station data transmission provided by Chinese invention patent CN117930289A optimizes the multi-station data transmission guiding time for optimizing the data transmission relay time and relay opportunity of a satellite. However, this method is not highly versatile, cannot be applied to all satellite data transmission systems, and does not reduce the cumbersome ground operation and control work, nor does it realize the autonomous switching of ground stations of the satellite data transmission system.

[0004] Therefore, how to use the satellite data transmission system to achieve autonomous ground station switching is the main problem to be solved by the current satellite data transmission system. Summary of the Invention

[0005] In order to solve the above technical problems existing in the prior art, the purpose of the present invention is to provide a method for autonomous ground station switching of satellite data transmission, which can effectively solve the problem that complex ground planning in advance is required for multi-station data transmission of a satellite, so as to realize the autonomous completion of multi-station relay data transmission work by the satellite.

[0006] To achieve the above object of the invention, the present invention provides a method for autonomous ground station switching of satellite data transmission, including the following steps:

[0007] Step S1, obtaining autonomous ground station switching parameters and setting the state before data transmission. The autonomous ground station switching parameters include the transmission sequence of ground stations, the transmission time envelope corresponding to the ground stations, and the ground station switching time. The transmission time envelope includes the start time and end time of transmission by the ground station;

[0008] Step S2: Obtain the satellite time, satellite attitude information, and satellite position information in real time, and calculate the off-axis angle of the ground station. The satellite position information includes the satellite positions corresponding to the current moment and its extrapolation for one switching station time, and the satellite attitude information includes the satellite attitudes corresponding to the current moment and its extrapolation for one switching station time.

[0009] Step S3: Perform data transmission and switching station operations according to the ground station transmission sequence and the switching station rules based on the off-axis angle and switching station time requirements.

[0010] According to one technical solution of the present invention, the switching station rules based on the off-axis angle and switching station time requirements are as follows:

[0011] If the transmission time envelope of the currently transmitting ground station coincides with the transmission time envelope of the ground station to be transmitted, and the difference between the envelope end time of the ground station to be transmitted and the envelope start time of the currently transmitting ground station is less than the switching station time, the ground station to be transmitted is regarded as unavailable;

[0012] If the transmission time envelope of the currently transmitting ground station coincides with the transmission time envelope of the ground station to be transmitted, and the difference between the envelope end time of the ground station to be transmitted and the envelope start time of the currently transmitting ground station is greater than the switching station time, if the off-axis angle of the ground station to be transmitted is better than that of the currently transmitting ground station, immediately perform the switching station operation; otherwise, perform the normal switching station process;

[0013] The normal switching station process includes:

[0014] If the moment obtained by subtracting the switching station time from the envelope end time of the currently transmitting ground station is greater than the envelope end time of the ground station to be transmitted, perform the switching station operation when the current satellite time reaches the envelope end time of the currently transmitting ground station; otherwise, perform the switching station operation when the current satellite time reaches the moment obtained by subtracting the switching station time from the envelope end time of the currently transmitting ground station.

[0015] According to one technical solution of the present invention, in the step S1, the pre-data transmission state setting includes:

[0016] Record the number of ground stations that the satellite needs to transmit data to as N; record the time envelopes for the satellite to transmit data to the N ground stations as [t 11 , t 12 , [t 21 , t 22 , …, [t N1 , t N2 , where t 11 < t 21 < … < t N1 , t 12 < t 22 < … < t N2 ; record the currently transmitting ground station as P i, the value range of i is [1, N]; the ground station to be transmitted is denoted as P j , the value range of j is [2, N]; the current satellite time is denoted as T, the handover time is denoted as T1, and the ground station P corresponding to the satellite time T i 's off-axis angle is denoted as φ i-T , the ground station P corresponding to the satellite time T j 's off-axis angle is denoted as φ j-T ;

[0017] Set i = 1, j = 2, φ i = 0, φ j = 0.

[0018] According to a technical solution of the present invention, in the step S2, it further includes pre-pointing the beam of the data transmission antenna to the first ground station in the ground station transmission sequence according to the satellite position and attitude at the current moment and the longitude, latitude and altitude information of the first ground station in the ground station transmission sequence.

[0019] According to a technical solution of the present invention, in step S3, it specifically includes the following steps:

[0020] Step S31: Judge the satellite time. If T ≥ t i1 , then perform data transmission. If not, then repeat step S31;

[0021] Step S32: Judge the transmission time envelopes of the ground stations P i and P j . If t i2 ≥ t j1 , then execute step S33. If t i2 <t j1 , then execute step S37;

[0022] Step S33: Judge the specific time for switching the beam of the data transmission antenna. If t j2 >t i2 + T1, then execute step S34. If not, the satellite data transmission system will not enable the ground station P j to perform data transmission, j = j + 1, and execute step S35;

[0023] Step S34: At time T, perform a comparison of the off-axis angle budgets of the data transmission antenna pointing to the ground stations P i and P j at time T + T1. If φ j-(T+T1) <φ i-(T+T1) , then execute step S310. If not, then execute step S35;

[0024] Step S35: If T ≥ t i2 , then execute step S36. If not, then repeat step S35;

[0025] Step S36: If i < N and j ≤ N, then execute Step S37; otherwise, complete data transmission.

[0026] Step S37: If t i2 ≥ t j1 - T1, then execute Step S38; otherwise, execute Step S39.

[0027] Step S38: If T ≥ t i2 , then execute Step S310; otherwise, repeat Step S38.

[0028] Step S39: If T ≥ t j1 - T1, then execute Step S310; otherwise, repeat Step S39.

[0029] Step S310: Stop data transmission, switch the ground station, direct the data transmission antenna beam to ground station P j , and set i = j, j = j + 1, and then execute Step S31.

[0030] According to one technical solution of the present invention, the off-axis angle of the ground station is calculated based on the satellite position information and the satellite attitude information, and the calculation formula for the off-axis angle is:

[0031]

[0032] In the formula, X S , Y S and Z S are the components of the satellite on the X-axis, Y-axis, and Z-axis in the geocentric fixed coordinate system respectively, X G , Y G and Z G are the components of the ground station on the X-axis, Y-axis, and Z-axis in the geocentric fixed coordinate system respectively, r x , r y and r z are the components of the relative position vector between the satellite and the ground station on the X-axis, Y-axis, and Z-axis in the geocentric fixed coordinate system respectively, E r is the coordinate transformation matrix from the geocentric fixed coordinate system to the instantaneous mean equator geocentric coordinate system, P r is the coordinate transformation matrix from the instantaneous mean equator geocentric coordinate system to the epoch mean equator geocentric coordinate system, A c is the coordinate transformation matrix from the epoch mean equator geocentric coordinate system to the geocentric pericenter coordinate system, G n is the coordinate transformation matrix from the geocentric pericenter coordinate system to the satellite orbit coordinate system, L t is the transformation matrix from the satellite orbit coordinate system to the satellite body coordinate system, and the transformation sequence is to rotate the attitude angles around the x-axis, y-axis, and z-axis in sequence according to the 1-3-2 Euler angle rotation sequence from the satellite orbit coordinate system, Tx is the conversion matrix from the satellite body coordinate system to the antenna coordinate system.

[0033] According to one aspect of the present invention, there is provided an autonomous ground station switching system for satellite data transmission to implement the above method, including:

[0034] A satellite mission computer for obtaining satellite time information in real time and generating a satellite time broadcast;

[0035] A GNSS receiver for obtaining satellite position information in real time and generating a position broadcast;

[0036] An attitude control computer for obtaining satellite attitude information in real time and generating an attitude broadcast;

[0037] A satellite data transmission system connected to the satellite mission computer, the GNSS receiver, and the attitude control computer through a satellite bus, for performing data transmission and ground station switching operations through a data transmission antenna according to the satellite time broadcast, the position broadcast, the attitude broadcast, and autonomous ground station switching parameters.

[0038] Compared with the prior art, the present invention has the following beneficial effects:

[0039] The present invention has the following advantages:

[0040] The autonomous ground station switching method and system for satellite data transmission provided by the present invention can be applied to various situations of multiple data transmission ground resource time envelopes, realizing the autonomous switching of multiple ground stations by the satellite data transmission system, which can replace the ground planning in the conventional situation, greatly reducing the occupation of satellite on ground planning resources, and having the characteristics of strong operability and wide application range.

[0041] The present invention designs a ground station switching rule based on the off-axis angle and ground station switching time requirements. By calculating the off-axis angles of the satellite pointing to different ground stations, it realizes the automatic selection of a ground station with a good satellite-ground visible field for data transmission, ensuring good quality of the satellite-ground transmission signal.

[0042] The present invention has no restrictions on the type of satellite payload, the modulation type of the data transmission system, the frequency band and working mode of the data transmission system, and the system of the data transmission antenna, and can be applied to different types of satellite payloads, modulation types of the data transmission system, frequency bands and working modes of the data transmission system, and systems of the data transmission antenna, having strong applicability. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0044] Figure 1 Schematically showing the flowchart of the satellite data transmission autonomous station switching method provided in the embodiment of the present invention;

[0045] Figure 2 Schematically showing the specific flowchart of the satellite data transmission autonomous station switching method in the embodiment of the present invention;

[0046] Figure 3 Schematically showing the diagram of various data transmission ground resource time envelopes received by the data transmission system. Specific embodiments

[0047] The description of the embodiments of this specification should be combined with the corresponding drawings, and the drawings should be part of the complete specification. In the drawings, the shape or thickness of the embodiments can be enlarged, and simplified or convenient markings can be used. Furthermore, each part of the structure in the drawings will be described separately. It should be noted that the elements not shown or described in words in the drawings are in the forms known to those of ordinary skill in the art.

[0048] In the description of the embodiments herein, any reference to directions and orientations is only for the convenience of description and should not be construed as any limitation to the protection scope of the present invention. The following description of the preferred embodiments involves combinations of features, and these features may exist independently or in combination. The present invention is not particularly limited to the preferred embodiments. The scope of the present invention is defined by the claims.

[0049] As Figure 1 and Figure 2 shown, the present invention provides a satellite data transmission autonomous station switching method, including the following steps:

[0050] Step S1: Obtain autonomous station switching parameters and set the state before data transmission;

[0051] The autonomous station switching parameters include the transmission sequence of the ground station, the corresponding transmission time envelope of the ground station, and the station switching time. The transmission time envelope includes the start time and end time of the ground station transmission. The data of the autonomous station switching parameters comes from the program-controlled data block generated by the ground system or the satellite mission planning system.

[0052] In step S1, the state setting before data transmission includes:

[0053] Let the number of ground stations that the satellite needs to transmit data to be denoted as N; the time envelopes of the satellite's data transmission to the N ground stations are respectively denoted as [t 11 , t 12 , [t 21 , t 22 , …, [t N1 , t N2 , where t 11 < t 21 < … < t N1 , t 12 < t 22 < … < t N2 ; the currently transmitting ground station is denoted as P i , where i ranges from [1, N]; the ground station to be transmitted is denoted as P j , where j ranges from [2, N]; the current satellite time is denoted as T, the handover time (i.e., the time required for the satellite's data transmission antenna beam to switch) is denoted as T1, and the off-axis angle of the ground station P i corresponding to the satellite time T is denoted as φ i-T , and the off-axis angle of the ground station P j corresponding to the satellite time T is denoted as φ j-T ;

[0054] Set i = 1, j = 2, φ i = 0, φ j = 0.

[0055] Step S2, Obtain the satellite time, satellite attitude information, and satellite position information in real time and calculate the off-axis angle of the ground station;

[0056] The satellite time, satellite attitude information, and satellite position information are received in real time by the satellite data transmission system through the satellite bus from the time broadcast sent by the satellite on-board computer, the position broadcast sent by the GNSS receiver, and the attitude broadcast sent by the attitude control computer. Among them, the time, position, and attitude broadcasts are updated every second. The satellite position information includes the satellite position corresponding to the current moment and its extrapolation for a handover time, and the satellite attitude information includes the satellite attitude corresponding to the current moment and its extrapolation for a handover time.

[0057] In step S2, it also includes pre-pointing the beam of the data transmission antenna to the first ground station in the ground station transmission sequence according to the satellite position and attitude at the current moment and the longitude, latitude, and altitude information of the first ground station in the ground station transmission sequence.

[0058] The off-axis angle is the angle between the beam pointed by the satellite data transmission system and the satellite +Z axis. The off-axis angle of the ground station is calculated based on the satellite position information and satellite attitude information. The calculation formula for the off-axis angle is:

[0059]

[0060] wherein, X S , Y S and Z S are the components of the satellite on the X-axis, Y-axis and Z-axis respectively in the geodetic coordinate system, X G , Y G and Z G are the components of the ground station on the X-axis, Y-axis and Z-axis respectively in the geodetic coordinate system, r x , r y and r z are the components of the X-axis, Y-axis and Z-axis of the relative position vector between the satellite and the ground station respectively in the geodetic coordinate system, E r is the coordinate transformation matrix from the geodetic coordinate system to the instantaneous mean equator geocentric coordinate system, P r is the coordinate transformation matrix from the instantaneous mean equator geocentric coordinate system to the epoch mean equator geocentric coordinate system, A c is the coordinate transformation matrix from the epoch mean equator geocentric coordinate system to the geocentric apsidal coordinate system, G n is the coordinate transformation matrix from the geocentric apsidal coordinate system to the satellite orbit coordinate system, L t is the transformation matrix from the satellite orbit coordinate system to the satellite body coordinate system, and the transformation sequence is to rotate the attitude angles around the x-axis, y-axis and z-axis in turn according to the 1-3-2 Euler angle rotation sequence from the satellite orbit coordinate system, T x is the transformation matrix from the satellite body coordinate system to the antenna coordinate system.

[0061] Step S3: Perform data transmission and station switching operations according to the ground station transmission sequence and the station switching rules based on the off-axis angle and the station switching time requirements.

[0062] The station switching rules based on the off-axis angle and the station switching time requirements are as follows:

[0063] If the transmission time envelope of the currently transmitting ground station coincides with the transmission time envelope of the ground station to be transmitted, and the difference between the envelope end time of the ground station to be transmitted and the envelope start time of the currently transmitting ground station is less than the station switching time, the ground station to be transmitted is regarded as unavailable;

[0064] If the transmission time envelope of the currently transmitting ground station coincides with the transmission time envelope of the ground station to be transmitted, and the difference between the envelope end time of the ground station to be transmitted and the envelope start time of the currently transmitting ground station is greater than the station switching time, if the off-axis angle of the ground station to be transmitted is better than that of the currently transmitting ground station, immediately perform the station switching operation, otherwise perform the normal station switching process;

[0065] The normal station switching process includes:

[0066] If the time when the envelope end time of the current transmitting ground station minus the station switching time is greater than the envelope end time of the ground station to be transmitted, perform the station switching operation when the current satellite time reaches the envelope end time of the current transmitting ground station; otherwise, perform the station switching operation when the current satellite time reaches the time when the envelope end time of the current transmitting ground station minus the station switching time.

[0067] As Figure 3 shown, among the multiple telemetry ground resource time envelopes received by the satellite data transmission system, there are various situations such as the time envelope of the latter 1 ground resource overlapping severely with that of the previous 1 ground resource, resulting in the unavailability of the latter 1 ground resource; the time envelope of the latter 1 ground resource being close to that of the previous 1 ground resource, requiring a switch of the telemetry beam; and the time envelopes of the latter 1 ground resource and the previous 1 ground resource not overlapping, resulting in the need to wait after the beam switch of the data transmission system. Among them, t i1 is the start time of the satellite data transmission system receiving the data transmission from ground station i; t i2 is the end time of the satellite data transmission system receiving the data transmission from ground station i; t j1 is the start time of the satellite data transmission system receiving the data transmission from ground station j; t j2 is the end time of the satellite data transmission system receiving the data transmission from ground station j; T1 is the time for the satellite telemetry antenna beam to switch. The method provided by the present invention can automatically adapt to the above situations and realize the data transmission work of the satellite autonomously completing multi-station relay.

[0068] In step S3, it specifically includes the following steps:

[0069] Step S31: Judge the satellite time. If T≥t i1 , perform data transmission; if not, repeat step S31;

[0070] Step S32: Judge the transmission time envelopes of ground stations P i and P j . If t i2 ≥t j1 , execute step S33; if t i2 <t j1 , execute step S37;

[0071] Step S33: Judge the specific time for the telemetry antenna beam to switch. If t j2 >t i2 +T1, execute step S34; if not, the satellite data transmission system will not enable ground station P j to perform data transmission, j = j + 1, and execute step S35;

[0072] Step S34: At time T, point the telemetry antenna at time T + T1 to ground stations P i and Pj Off-axis angle budget comparison. If φ j-(T+T1) < φ i-(T+T1) , then execute step S310; otherwise, execute step S35.

[0073] Step S35: If T ≥ t i2 , then execute step S36; otherwise, repeat step S35.

[0074] Step S36: If i < N and j ≤ N, then execute step S37; otherwise, complete data transmission.

[0075] Step S37: If t i2 ≥ t j1 - T1, then execute step S38; otherwise, execute step S39.

[0076] Step S38: If T ≥ t i2 , then execute step S310; otherwise, repeat step S38.

[0077] Step S39: If T ≥ t j1 - T1, then execute step S310; otherwise, repeat step S39.

[0078] Step S310: Stop data transmission, switch the ground station, direct the data transmission antenna beam to ground station P j , and i = j, j = j + 1, and then execute step S31.

[0079] The present invention also provides a satellite data transmission autonomous station-switching system for implementing the above method, including:

[0080] A satellite mission computer for obtaining satellite time information in real time and generating a satellite time broadcast.

[0081] A GNSS receiver for obtaining satellite position information in real time and generating a position broadcast.

[0082] An attitude control computer for obtaining satellite attitude information in real time and generating an attitude broadcast.

[0083] A satellite data transmission system connected to the satellite mission computer, GNSS receiver, and attitude control computer through a satellite bus for performing data transmission and station-switching operations through a data transmission antenna according to the satellite time broadcast, position broadcast, attitude broadcast, and autonomous station-switching parameters.

[0084] In the present invention, the types of satellite payloads may be optical payloads, SAR payloads, etc., the modulation types of the data transmission system may be QPSK, 8PSK, etc.; the frequency bands of the data transmission system may be X-band, Ka-band, etc.; the working modes of the data transmission system may be playback, record-while-playing, real-time transmission, etc.; the systems of the data transmission antennas may be phased array antennas, horn antennas, etc. The present invention has strong applicability.

[0085] It should be noted that the above is the preferred embodiment of the present invention. It should be pointed out that although the preferred embodiments of the present invention have been described, for those skilled in the art of this technology, once the basic creative concept of the present invention is known, without departing from the principle described in the present invention, several improvements and refinements can still be made, and these improvements and refinements should also be regarded as the protection scope of the present invention. Therefore, the appended claims are intended to be construed as including the preferred embodiments and all changes and modifications falling within the scope of the embodiments of the present invention.

Claims

1. An autonomous station switching method for satellite data transmission, characterized in that Including the following steps: Step S1: Obtain the autonomous handover station parameters and set the state before data transmission. The autonomous handover station parameters include the transmission sequence of the ground station, the transmission time envelope corresponding to the ground station, and the handover station time. The transmission time envelope includes the start time and end time of the ground station transmission; Step S2: Real-time obtain the satellite time, satellite attitude information, and satellite position information, and calculate the off-axis angle of the ground station. The satellite position information includes the satellite position at the current moment and the satellite position extrapolated by one handover station time. The satellite attitude information includes the satellite attitude at the current moment and the satellite attitude extrapolated by one handover station time; Step S3: Perform data transmission and handover station operations according to the ground station transmission sequence and the handover station rules based on the off-axis angle and handover station time requirements.

2. The satellite data transmission independent station switching method according to claim 1, wherein The handover station rules based on the off-axis angle and handover station time requirements are as follows: If the transmission time envelope of the currently transmitting ground station coincides with the transmission time envelope of the ground station to be transmitted, and the difference between the envelope end time of the ground station to be transmitted and the envelope start time of the currently transmitting ground station is less than the handover station time, the ground station to be transmitted is regarded as unavailable; If the transmission time envelope of the currently transmitting ground station coincides with the transmission time envelope of the ground station to be transmitted, and the difference between the envelope end time of the ground station to be transmitted and the envelope start time of the currently transmitting ground station is greater than the handover station time, if the off-axis angle of the ground station to be transmitted is better than the off-axis angle of the currently transmitting ground station, immediately perform the handover station operation, otherwise perform the normal handover station process; The normal handover station process includes: If the moment obtained by subtracting the handover station time from the envelope end time of the currently transmitting ground station is greater than the envelope end time of the ground station to be transmitted, perform the handover station operation when the current satellite time reaches the envelope end time of the currently transmitting ground station, otherwise perform the handover station operation when the current satellite time reaches the moment obtained by subtracting the handover station time from the envelope end time of the currently transmitting ground station.

3. The satellite data transmission autonomous station switching method according to claim 1, wherein In the step S1, the state setting before data transmission includes: Let the number of ground stations that the satellite needs to transmit data to be denoted as N; the time envelopes of the satellite's data transmission to the N ground stations are respectively denoted as [t 11 , t 12 , [t 21 , t 22 , …, [t N1 , t N2 , where t 11 < t 21 < … < t N1 , t 12 < t 22 < … < t N2 ; the current ground station for transmission is denoted as P i , and the value range of i is [1, N]; the ground station to be transmitted is denoted as P j , and the value range of j is [2, N]; the current satellite time is denoted as T, the handover time is denoted as T1, and the off-axis angle of the ground station P i corresponding to the satellite time T is denoted as φ i-T , and the off-axis angle of the ground station P j corresponding to the satellite time T is denoted as φ j-T ; Set \(i = 1\), \(j = 2\), \(\varphi\) i \(= 0\), \(\varphi\) j \(= 0\).

4. The satellite data transmission autonomous station switching method according to claim 3, characterized in that In the step S2, it also includes pre-pointing the beam of the data transmission antenna to the first ground station in the ground station transmission sequence according to the satellite position and attitude at the current moment and the longitude, latitude, and altitude information of the first ground station in the ground station transmission sequence.

5. The satellite data transmission independent station switching method according to claim 4, characterized in that In step S3, it specifically includes the following steps: Step S31: Determine the satellite time. If T≥t i1 , data transmission is performed. Otherwise, step S31 is repeatedly executed; Step S32: Judge the transmission time envelopes of ground stations P i and P j and if t i2 ≥t j1 , then execute Step S33; if t i2 <t j1 , then execute Step S37; Step S33: Judge the specific time of the beam switching of the data transmission antenna. If t j2 > t i2 + T1, then execute Step S34. Otherwise, the satellite data transmission system will not enable the ground station P j to perform data transmission, j = j + 1, and execute Step S35; Step S34: At time T, direct the data transmission antenna at time T+T1 towards ground station P i and P j Perform off-axis angle budget comparison. If φ j-(T+T1) < φ i-(T+T1) , then execute step S310; otherwise, execute step S35 Step S35: If T≥t i2 , then execute Step S36; otherwise, repeat Step S35; Step S36: If i < N and j ≤ N, then execute step S37, otherwise, complete the data transmission; Step S37. If t i2 ≥ t j1 - T1, then execute Step S38; otherwise, execute Step S39. Step S38: If T≥t i2 , then execute Step S310; otherwise, repeat Step S38. Step S39: If T ≥ t j1 - T1, then execute step S310; otherwise, repeat step S39. Step S310: Stop data transmission, switch the ground station, and direct the data transmission antenna beam towards ground station P j , and i = j, j = j + 1, and then execute Step S31.

6. The satellite data transmission independent station switching method according to claim 3, wherein The off-axis angle of the ground station is calculated according to the satellite position information and the satellite attitude information. The calculation formula for the off-axis angle Φ is: where X S , Y S and Z S are the components of the satellite along the X-axis, Y-axis and Z-axis in the geodetic coordinate system respectively, X G , Y G and Z G are the components of the ground station along the X-axis, Y-axis and Z-axis in the geodetic coordinate system respectively, r x , r y and r z are the components of the relative position vector between the satellite and the ground station along the X-axis, Y-axis and Z-axis in the geodetic coordinate system respectively, Er is the coordinate transformation matrix from the geodetic coordinate system to the instantaneous mean equator geocentric coordinate system, P r is the coordinate transformation matrix from the instantaneous mean equator geocentric coordinate system to the epoch mean equator geocentric coordinate system, A c is the coordinate transformation matrix from the epoch mean equator geocentric coordinate system to the geocentric apsidal coordinate system, G n is the coordinate transformation matrix from the geocentric apsidal coordinate system to the satellite orbit coordinate system, L t is the transformation matrix from the satellite orbit coordinate system to the satellite body coordinate system. The transformation sequence is to rotate the satellite orbit coordinate system around the x-axis, y-axis and z-axis in turn according to the 1-3-2 Euler angle rotation sequence by the attitude angles, T x is the transformation matrix from the satellite body coordinate system to the antenna coordinate system.

7. A satellite data transmission autonomous station switching system for implementing the method according to any one of claims 1 to 6, characterized in that, Including: The on-board computer is used to obtain the satellite time information in real time and generate a satellite time broadcast; The GNSS receiver is used to obtain the satellite position information in real time and generate a position broadcast; The attitude control computer is used to obtain the satellite attitude information in real time and generate an attitude broadcast; The satellite data transmission system is connected to the on-board computer, the GNSS receiver, and the attitude control computer through the satellite bus, and is used to perform data transmission and handover station operations through the data transmission antenna according to the satellite time broadcast, the position broadcast, the attitude broadcast, and the autonomous handover station parameters.

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