Vehicle-mounted multi-antenna switching method and device for low-orbit internet satellite communication

Abstract

The invention provides a vehicle-mounted multi-antenna switching method and device for low-orbit internet satellite communication, and belongs to the technical field of satellite communication. According to the invention, the gain of each antenna component is read in a table look-up manner and is sorted to obtain the first sorted sequence, the received signal strength of each antenna component is obtained in a signal strength measurement manner and is sorted to obtain the second sorted sequence, and the received signal strength of each antenna component is calculated based on the relationship between the first sorted sequence and the second sorted sequence. According to the embodiment of the invention, whether the current antenna group works in the first working mode or the second working mode is determined, and a main antenna switching method is respectively given in the two working modes, so that the stability of communication signal quality in the two working modes is kept. According to the method, the antennas of the vehicle-mounted multi-antenna group can be quickly switched in a low-orbit satellite communication scene, and the stability of the quality of antenna communication signals in non-shielding and partially-shielding scenes is ensured.

Description

Technical Field

[0001] The present invention belongs to the technical field of satellite communications, and in particular, relates to a vehicle-mounted multi-antenna switching method and device for low-orbit Internet satellite communications. Background Art

[0002] Low-orbit satellites have high speeds, short visibility times, and high satellite sight line change rates, which place higher demands on ground antennas. In terms of vehicle-mounted antennas, multiple antenna groups are usually used to expand the antenna coverage airspace and improve the consistency of antenna gain in the entire airspace. The high sight line change rate of low-orbit satellites places new requirements on the antenna switching rate in the multiple antenna groups. In addition, when ground vehicles are in motion, satellite communication signals may be partially blocked, which will also affect the signal quality of low-orbit satellite communications.

[0003] The existing satellite communication multi-antenna switching solution simply switches antennas based on the geometric relationship between antenna elements and satellite line of sight, without considering the problem of partial antenna occlusion that may occur during the movement of ground vehicles. When the line of sight of some antennas in the antenna group is blocked by obstacles, the existing antenna switching solution will not be able to ensure normal communication with the satellite. Summary of the invention

[0004] In view of the above problems, the present invention proposes a vehicle-mounted multi-antenna switching method and device for low-orbit Internet satellite communications. The present invention reads the gain of each antenna component by table lookup and sorts to obtain a first sorting sequence, obtains the received signal strength of each antenna component by signal strength measurement and sorts to obtain a second sorting sequence, and determines whether the current antenna group works in the first working mode or the second working mode based on the relationship between the first sorting sequence and the second sorting sequence, and provides a switching method for the main antenna in the two working modes, so as to maintain the stability of the communication signal quality in both unobstructed (corresponding to the first working mode) and partially obstructed (corresponding to the second working mode).

[0005] The technical solution adopted by the present invention is:

[0006] A vehicle-mounted multi-antenna switching method for low-orbit Internet satellite communications includes the following processes:

[0007] Step 1, the antenna group including N antenna elements is powered on, and the position and attitude information of the antenna group is obtained by using the GNSS positioning unit and the inertial navigation unit fixedly connected to the antenna group coordinate system, where N≥5;

[0008] Step 2, turning on the central component of the antenna group, using the central component to search for satellites, and obtaining the satellite's ephemeris information;

[0009] Step 3: Based on the obtained satellite ephemeris and the position information and attitude information of the antenna group, obtain the satellite's line of sight elevation angle El in the installation coordinate system of each antenna element. i and the sight azimuth Az i , where i∈{1,2,...,N};

[0010] Step 4: Using the pre-stored gain pattern data of each antenna element, the gain G of each antenna element in the satellite line of sight direction is obtained by table lookup. i (El i ,Az i ), and for G i (El i ,Az i ) Sort from large to small to obtain the first sorting sequence, where i∈{1,2,...,N};

[0011] Step 5: Turn on N antenna elements and measure the actual signal strength P received by the receiving paths of the N antenna elements respectively. i , for P i Sort from large to small to obtain a second sorting sequence, where i∈{1,2,...,N}; use the antenna component corresponding to the maximum signal strength in the second sorting sequence as the main antenna to send and receive information communication with the satellite;

[0012] Step 6, determine the working mode of the antenna element: if the antenna element corresponding to the maximum gain in the first sorting sequence is the same as the antenna element corresponding to the maximum signal strength in the second sorting sequence, then determine that the antenna group works in the first working mode, otherwise the antenna group works in the second working mode.

[0013] Further, in step 6, when the antenna group operates in the first operating mode, the following process is performed:

[0014] Step 71: Mark each time of switching to the first working mode as the initial time t 0 , record the main antenna t 0 Gain G at the moment main0 , received signal strength P main0 , and the distance d between the antenna group and the satellite 0 ;

[0015] Step 72: At each time t, calculate the line-of-sight angles between all antenna elements and the satellite, and obtain the gain G of the main antenna by looking up the table. main (t) and the gains of the remaining antenna elements, and updating the first sorting sequence;

[0016] Step 73: At each time t, when the maximum gain in the first sorting sequence is equal to the gain G of the main antenna mainWhen the difference between (t) and (t) is greater than the first switching threshold G1, the antenna element corresponding to the maximum gain in the first sorting sequence is switched to the main antenna, and the new main antenna transmits and receives information communication with the satellite;

[0017] Step 74: Obtain the first received signal strength P′ of the main antenna at the current time t main (t), measure the actual received signal strength of the main antenna at the current time t, and calculate the actual received signal strength and the first received signal strength P′ main (t) The difference ΔP main (t), if |ΔP main (t)|>P1, the antenna group working mode is switched to the second working mode, where P1 is a preset second switching threshold.

[0018] Furthermore, in step 6, when the antenna group operates in the second operating mode, at each time t, the following process is performed:

[0019] Step 81, measure the actual received signal strength P of the main antenna main (t) and the actual received signal strengths of the remaining antenna elements, and updating the second sorting sequence;

[0020] Step 82: When the maximum actual received signal strength in the second sorting sequence is equal to the actual received signal strength P of the main antenna, main When the difference between (t) and (t) is greater than the third switching threshold P2, the antenna array element with the largest actual received signal strength in the second sorting sequence is switched to the main antenna, and the new main antenna transmits and receives information communication with the satellite;

[0021] Step 83, calculating the sight angles between all antenna components and the satellite, obtaining the gains of all antenna components by looking up a table, and updating the first sorting sequence;

[0022] Step 84, within a given period of time T, if the gain G of the main antenna main (t) continues to be the maximum value of the gains of all antenna elements in the first sorting sequence, the antenna group working mode is switched to the first working mode.

[0023] A vehicle-mounted multi-antenna switching device for low-orbit Internet satellite communications, comprising:

[0024] The antenna group includes N ≥ 5 antenna elements, and the N antenna elements are installed at different positions of an antenna array or a vehicle according to different orientation angles to achieve high-gain reception of satellite communication signals in corresponding directions;

[0025] An inertial navigation unit is strapdown-mounted with the antenna array or the current vehicle and is used to obtain the attitude of the antenna array or the vehicle;

[0026] A GNSS positioning unit, used to determine the position of the antenna array or the vehicle;

[0027] A data storage and query unit, used to store the gain pattern data of each antenna element, receive the query instruction of the control unit, and feedback the gain of the required antenna element at a given azimuth and elevation angle;

[0028] A power detection unit, used to detect the power strength of satellite signals received by receiving channels of different antenna elements in the antenna group;

[0029] Antenna switching switch, used to switch between receiving and transmitting paths of different antennas;

[0030] The control unit calculates the elevation angle and azimuth angle of the satellite's line of sight relative to each antenna element based on the information provided by the inertial navigation unit and the GNSS positioning unit, and accesses the data storage and query unit to obtain the antenna gain of the satellite's line of sight direction corresponding to all antenna elements, and accesses the power detection unit as needed to obtain the signal strength of each antenna element receiving channel, and then controls the antenna group to work in the first working mode or the second working mode according to the above-mentioned switching method, completes the antenna switching, determines the main antenna, and controls the main antenna to realize signal reception and transmission with the satellite.

[0031] Compared with the background technology, the present invention has the following advantages:

[0032] 1. The present invention obtains a first sorting sequence and a second sorting sequence by means of a directional pattern table lookup and a signal strength measurement method, and the initial working mode of the antenna can be determined based on the relationship between the two sequences; in the first working mode, only the actual received signal strength of the main antenna needs to be measured, and the gain of each antenna obtained by table lookup is combined to complete the determination of multi-antenna switching and working mode switching; in the second working mode, the switching of multiple antennas is achieved by real-time updating of the second sorting sequence, and the determination of working mode switching is further achieved by combining the gain of each antenna obtained by table lookup.

[0033] 2. The method proposed in the present invention can ensure efficient switching between vehicle-mounted multi-antenna array elements in low-orbit satellite communication scenarios, thereby ensuring consistency in signal quality during the communication process; in addition, the determination and switching of the first working mode and the second working mode can ensure the communication quality of the vehicle-mounted antenna under partial obstruction; finally, in the first working mode, only the actual received signal strength of the main antenna is measured without measuring the actual received signal strength of other antennas, which can effectively reduce hardware costs and processing resource consumption, and the antenna gain is retrieved by table lookup, which can quickly and accurately complete the judgment of the antenna switching conditions.

[0034] In summary, the present invention realizes the rapid switching of antennas of the vehicle-mounted multi-antenna group in the low-orbit satellite communication scenario, ensuring the stability of the antenna communication signal quality in unobstructed and partially obstructed scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is a structural schematic diagram of a vehicle-mounted multi-antenna switching device for low-orbit Internet satellite communications according to the present invention.

[0036] Figure 2 It is a schematic diagram of the layout of antenna components in an embodiment of the present invention.

[0037] Figure 3 It is a schematic diagram of the installation layout of a vehicle-mounted antenna component in an embodiment of the present invention.

[0038] Figure 4 It is a flow chart of a vehicle-mounted multi-antenna switching method for low-orbit Internet satellite communications of the present invention.

[0039] Figure 5 This is a working flow chart of the antenna group in the first working mode.

[0040] Figure 6 It is a working flow chart when the antenna group is in the second working mode. DETAILED DESCRIPTION

[0041] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work belong to the scope of protection of the present invention.

[0042] A vehicle-mounted multi-antenna switching device for low-orbit Internet satellite communications, comprising:

[0043] The antenna group 101 includes N ≥ 5 antenna elements, and the N antenna elements are installed at different positions of an antenna array or a vehicle according to different orientation angles to achieve high-gain reception of satellite communication signals in corresponding directions;

[0044] An inertial navigation unit 102 is strapdown-mounted with the antenna array or the current vehicle and is used to obtain the attitude of the antenna array or the vehicle;

[0045] A GNSS positioning unit 103, used to determine the position of the antenna array or the vehicle;

[0046] The data storage and query unit 104 is used to store the gain pattern data of each antenna element, and receive the query instruction of the control unit 107 to feedback the gain of the required antenna element at a given azimuth and elevation angle;

[0047] A power detection unit 105, used to detect the power strength of satellite signals received by receiving channels of different antenna elements in the antenna group;

[0048] Antenna switch 106, used to switch between receiving and transmitting paths of different antennas;

[0049] The control unit 107 calculates the line-of-sight elevation and line-of-sight azimuth of the satellite relative to each antenna component based on the information provided by the inertial navigation unit 102 and the GNSS positioning unit 103, and accesses the data storage and query unit 104 to obtain the antenna gain of the satellite line-of-sight direction corresponding to all antenna components, and accesses the power detection unit 105 as needed to obtain the signal strength of the receiving channel of each antenna component, thereby controlling the antenna group to operate in the first working mode or the second working mode, completing antenna switching, determining the main antenna, and controlling the main antenna to realize signal reception and transmission with the satellite.

[0050] like Figure 1 As shown, the vehicle-mounted multi-antenna switching device disclosed in this embodiment is mainly composed of an antenna group 101, an inertial navigation unit 102, a GNSS positioning unit 103, a data storage and query unit 104, a power detection unit 105, an antenna switching switch 106 and a control unit 107.

[0051] The antenna group 101 is composed of N≥5 antenna elements, which are used to realize the signal receiving and transmitting function between the antenna and the low-orbit satellite. When working, only one antenna element in the antenna group 101 sends a signal to the satellite at each time, and each antenna element can receive the signal sent by the satellite in turn under the control of the antenna switching switch 106. The antenna element adopts a circularly polarized microstrip antenna with single feed point coupling feeding, a double-layer patch design, and an inverted structure of the antenna radiation layer to form a double resonant circuit with the feeding layer, with two resonant frequencies, and the two resonant frequencies are appropriately close to form a double-peak resonant circuit to widen the antenna bandwidth.

[0052] In some implementations, the antenna elements in the antenna group 101 are installed in an integrated manner on the same antenna array, and different antenna elements on the array face different directions to achieve high-gain coverage of the entire airspace by the antenna group 101. Figure 2 As shown, an embodiment of the integrated layout of the antenna group is provided. Figure 2 There are five antenna elements, namely A1, A2, A3, A4 and A5, which are installed on the same antenna array A0 with different spatial orientations. The fixed coordinate system OX of the antenna array is defined in the figure.b Y b Z b , where the origin O is at the geometric center of the antenna array, OY b The axis coincides with the longitudinal axis of the antenna array A0, OZ b The axis is perpendicular to the antenna array A0, OX b The axis is perpendicular to the other two axes and forms a right-handed system. Each antenna element i, i∈{1,2,...,N} has its own fixed coordinate system, such as Figure 2 As shown, for any antenna element A, the Z axis of its fixed coordinate system passes through its geometric center and is perpendicular to the element plane, the X axis passes through a given reference point in the antenna plane, and the Y axis is perpendicular to the plane formed by the XZ axes, forming a right-handed system.

[0053] Figure 2 In the figure, antenna element A1 is located at the geometric center of antenna array A0, and its fixed coordinate system OX 1 Y 1 Z 1 The fixed coordinate system OX of the antenna array b Y b Z b coincidence; the Z axis of antenna elements A2 to A5 (Z 2 ~Z 5 ) are evenly distributed at an elevation angle of 45° relative to the antenna array A0. b Y b Z b This antenna element layout can ensure that the antenna gains of the four quadrants in the airspace have high consistency, so as to achieve high-gain coverage of the entire airspace by the antenna group.

[0054] In another embodiment, the antenna elements in the antenna group 101 are installed at different positions of the vehicle in a distributed manner, and different antenna elements face different directions to achieve high-gain coverage of the entire airspace by the antenna group 101. Figure 3 A distributed installation method of an antenna group 101 including 5 antenna elements on a vehicle is provided. In the figure, the antenna elements are numbered B1 to B5, where B1 is installed at the geometric center of the roof in a manner that the Z axis is perpendicular to the roof, and the four antennas B2 to B5 are installed at the four vertices of the roof in sequence, and the Z axis of each antenna is 45° relative to the roof plane and points to the left rear airspace, right rear airspace, right front airspace, and left front airspace of the vehicle in sequence.

[0055] The inertial navigation unit 102 is strapdown-mounted with the antenna array or the current vehicle to obtain the attitude of the antenna array or the vehicle, which is the attitude of the antenna array or the current vehicle relative to the station center coordinate system, and the coordinate axis of the station center coordinate system coincides with the local northeast sky direction. Combined with the installation matrix of each antenna element relative to the antenna array or the current vehicle, the attitude matrix of each antenna element relative to the station center coordinate system can be obtained in real time.

[0056] The GNSS positioning unit 103 is used to determine the position of the antenna array or the vehicle, and is not limited to the Beidou navigation system or the GPS navigation system or other available navigation systems. Using the GNSS positioning unit 103, the longitude λ of the antenna array or the current vehicle can be obtained. A , Latitude L A , height H A , which is used to construct the above-mentioned station center coordinate system.

[0057] The data storage and query unit 104 stores the gain pattern data of each antenna element and has a data query function. The gain pattern data is a plurality of three-dimensional data pairs in the form of (El, Az, G), indicating that a certain antenna element has a gain of G in the direction of azimuth Az and elevation El in its fixed coordinate system. The pattern data is pre-stored in the data storage and query unit 104 when the device leaves the factory. When the antenna group 101 is working, it receives a query instruction from the control unit 107 and returns the gain in the direction of the azimuth (El, Az) of a certain element that it has queried.

[0058] The power detection unit 105 is used to detect the power strength of the satellite signal received by the receiving channels of different antenna elements in the antenna group 101, and feed back the measurement results to the control unit 107. One end of the power detection unit 105 is connected to the antenna switching switch 106, which is used to receive the radio frequency signal received by the current antenna receiving path, down-convert the signal and sample it to obtain the baseband signal, calculate the instantaneous power value of the complex IQ baseband signal, and continuously measure the received signal for a period of time to obtain the average power of the current receiving channel.

[0059] The antenna switching switch 106 is used to switch between receiving and transmitting paths of different antennas. When the antenna group 101 is working, only one main antenna in the antenna group 101 will transmit signals to the satellite. Under the control of the control unit 107, the antenna switching switch 106 switches the main antenna between different antenna elements according to a given switching criterion. In addition, the antenna switching switch 106 is a one-pole N-throw switch, one end of which is connected to the power detection unit 105, and the other end is connected to the N antenna elements in the antenna group 101, so as to switch the radio frequency path between the N antenna elements and cooperate with the power detection unit 105 to complete the corresponding signal power measurement task. At each moment, the antenna switching switch 106 is only connected to one antenna element in the antenna group 101.

[0060] The control unit 107 is the control core of the antenna group 101. Based on the attitude and position information provided by the inertial navigation unit 102 and the GNSS positioning unit 103, combined with the installation matrix of each antenna component relative to the antenna array or the current vehicle, the attitude matrix of each antenna component relative to the station center coordinate system is obtained in real time. Further using the received satellite ephemeris information, the line of sight elevation angle and line of sight azimuth angle of the satellite relative to each antenna component can be obtained. After that, these two angles can be used as input to obtain the gain of each antenna component in the satellite line of sight direction from the data storage and query unit 104. In addition, the control unit 107 accesses the power detection unit 105 according to the pre-written main antenna switching and working mode switching measurement scheme, obtains the signal strength of the receiving channel of each antenna component, and then controls the antenna group 101 to work in the first working mode or the second working mode, and controls the antenna switching switch 106 to complete the main antenna switching, and controls the main antenna to realize signal reception and transmission with the satellite.

[0061] It should be understood that the device may further include additional frames not shown and / or the frames shown may be omitted, and the components shown may be implemented by hardware, software or a combination thereof, and the scope of the present application is not limited in this respect.

[0062] like Figure 4 As shown, a vehicle-mounted multi-antenna switching method for low-orbit Internet satellite communications includes the following steps:

[0063] Step 1: The antenna group including N≥5 antenna elements is powered on, and the position and attitude information of the antenna group is obtained by using a GNSS positioning unit and an inertial navigation unit fixedly connected to the antenna group coordinate system.

[0064] Specifically, the longitude λ of the antenna group can be obtained using the GNSS positioning unit. A , Latitude L A , height H A Position information. Based on the position information, the geocentric vector of the antenna group in the Earth-centered Earth-fixed coordinate system ECEF (Earth-centered Earth-fixed coordinate system) can be obtained. And the coordinate transformation matrix from the ECEF system to the aforementioned station center coordinate system As shown below:

[0065]

[0066] Using the specific force and angular velocity information measured by the inertial navigation unit, the above-mentioned antenna array surface fixed contact OX can be solved b Y b Z b The attitude matrix relative to the station center coordinate system Therefore, the coordinate transformation matrix from the ECEF system to the fixed connection of the antenna array surface can be obtained as follows: For each antenna element i, i∈{1,2,...,N} has its own installation matrix relative to the antenna array fixed connection In addition, the installation vector of the coordinate origin of the fixed-connection coordinate system of antenna element i relative to the fixed-connection origin of the antenna array surface is

[0067] Step 2: Only the central component of the antenna group is turned on, and satellite search is performed using the central component to obtain the satellite's ephemeris information.

[0068] Specifically, all antenna elements in the antenna group are omnidirectional antennas. The central element refers to the antenna closest to the geometric center of the antenna group. Generally speaking, the element is arranged toward the sky to receive satellite signals within the airspace. The above-mentioned satellite is the satellite corresponding to the beam that can provide the maximum receiving power for the central element. Generally speaking, the antenna group cannot work independently and needs to cooperate with the back-end satellite communication terminal to obtain and solve the satellite broadcast information to obtain the satellite's ephemeris information. The satellite's ephemeris information is configured in the broadcast message sent by the satellite.

[0069] Step 3: Based on the obtained satellite ephemeris and the position information and attitude information of the antenna group, obtain the satellite's line of sight elevation angle El in the installation coordinate system of each antenna element. i and the sight azimuth Az i , where i∈{1,2,...,N}.

[0070] Based on the ephemeris information obtained in step 2, the position vector of the satellite in the ECEF system can be calculated: Further combined with the antenna group attitude and position information obtained in step 1, the line of sight vector between antenna element i and the satellite in its fixed coordinate system can be obtained: for:

[0071]

[0072] The satellite line of sight azimuth Az of antenna element i is i and elevation angle El i It can be obtained by the following formula:

[0073]

[0074] Step 4: Using the pre-stored gain pattern data of each antenna element, the gain G of each antenna element in the satellite line of sight direction is obtained by table lookup. i (El i ,Az i ), and for G i (El i ,Az i) are sorted from large to small to obtain the first sorting sequence, where i∈{1,2,...,N}. The gain pattern data of each antenna element is stored in Figure 1 In the data storage and query unit 104, the control unit 107 obtains the gain of each antenna component in the satellite line of sight direction by accessing the data storage and query unit 104. The first sorting sequence represents the gain of each antenna component in the satellite line of sight direction at the current satellite position in descending order. Based on the descending order, the antenna with the largest gain can be screened out.

[0075] Step 5: Turn on all N antenna elements and measure the actual signal strength P received by the N antenna receiving paths respectively. i , for P i Sort from large to small to obtain the second sorting sequence, where i∈{1,2,...,N}; use the antenna element corresponding to the maximum signal strength in the second sorting sequence as the main antenna to send and receive information communication with the satellite. Figure 1 The antenna switch 106 controls the receiving channels of the N antenna elements to be opened in sequence, and uses the power detection unit 105 to measure the satellite signal strength P received by each channel. i The second sorting sequence is a descending order of the satellite signal strength received by each antenna element. At initial startup, the antenna element with the maximum signal strength measured in the second sorting sequence is used as the main antenna of antenna group 101 to complete the reception and transmission of satellite communication radio frequency signals.

[0076] Step 6, determine the working mode of antenna group 101: if the antenna element corresponding to the maximum gain in the first sorting sequence is the same as the antenna element corresponding to the maximum signal strength in the second sorting sequence, then it is determined that antenna group 101 works in the first working mode, otherwise antenna group 101 works in the second working mode. Here, the first working mode corresponds to the working scenario of the main antenna without obstruction. In this scenario, since the difference in the installation position of the antenna element is negligible relative to the distance from the satellite, the strength of the signal received by the antenna element is only related to the gain of the antenna element in the direction of the satellite line of sight. When the antenna element with the largest received signal strength in the second sorting sequence happens to be the antenna element with the largest gain in the first sorting sequence, it indicates that the communication link of the current antenna element is not blocked. Here, the second working mode corresponds to the working scenario of the main antenna being partially blocked. In this scenario, the element with the largest actual received signal strength in the antenna element is inconsistent with the element with the largest gain in the direction of the satellite line of sight, indicating that there is an obstruction on the communication link of the main antenna.

[0077] Further, Figure 5 The following are the steps to be performed when the antenna group works in the first working mode:

[0078] Step 71, mark each time of switching to the first working mode as the initial time t 0 , record the main antenna t 0 Gain G at the moment main0 , received signal strength P main0 , and the distance d between the antenna group and the satellite 0 ;

[0079] Step 72, at each time t, calculate the line of sight angle between all antenna elements and the satellite, and obtain the gain G of the main antenna by looking up the table. main (t) and the gains of the remaining antenna components, and update the first sorting sequence; the satellite's line of sight angle is calculated according to the method described in the aforementioned step S3.

[0080] Step 73: At each time t, when the maximum gain in the first sorting sequence is equal to the gain G of the main antenna main (t) is greater than the first switching threshold G1, the antenna component corresponding to the maximum gain in the first sorting sequence is switched to the main antenna, and the new main antenna communicates with the satellite for sending and receiving information. When the antenna is not blocked, as the satellite moves, the gain of each antenna component in the direction of the satellite's line of sight will gradually change, and accordingly, the first sorting sequence will also gradually change. When the satellite line of sight gain of the current main antenna is not the maximum gain in the antenna group 101, the main antenna should be switched, and the antenna component corresponding to the maximum satellite line of sight gain should be set as the main antenna. Furthermore, in order to prevent the main antenna from ping-pong switching between different antenna components, the first switching threshold G1 is introduced here. When the difference between the maximum gain and the gain of the current main antenna is greater than the first switching threshold G1, the main antenna is switched to the antenna component corresponding to the current maximum satellite line of sight gain.

[0081] Step 74, obtain the first received signal strength P′ of the main antenna at the current time t main (t), measure the actual received signal strength of the main antenna at the current time t, and calculate the actual received signal strength and the first received signal strength P′ main (t) The difference ΔP main (t), if |ΔP main (t)|>P1, the antenna group working mode is switched to the second working mode, where P1 is a preset second switching threshold.

[0082] In one embodiment, through the beamforming design of the onboard antenna array, it is possible to achieve that the transmission gain of different locations within the coverage range of a communication beam in the low-orbit satellite communication system is basically the same. In this case, the first received signal strength is set to the theoretical received signal strength of the main antenna. At this time, compared with the initial time t 0At time t, the theoretical value of the received signal strength of the main antenna is determined only by the change in the satellite-to-ground distance caused by the satellite movement and the change in the antenna element gain caused by the change in the satellite line of sight angle. At this moment, the theoretical received signal strength of the main antenna is P′ main (t) can be obtained by the following formula:

[0083] P′ main (t) = P main0 -ΔL(t)+ΔG main (t)

[0084] Where, ΔL(t) = 20log 10 (d(t) / d 0 ) is the change in path loss introduced by the relative motion of the antenna and the satellite, d(t) is the distance between the antenna and the satellite at the current moment, ΔG main (t) = G main (t)-G main0 is the gain change of the main antenna caused by the change of the satellite's sight angle. The actual received signal strength of the main antenna is given by Figure 1 The power detection unit 105 measures the power. Considering the influence of channel fading, multipath, rain attenuation and other factors in the satellite-to-ground communication link, in order to compensate for the model deviation caused by these factors, a second switching threshold P1 is set. When the actual received signal strength is equal to the first received signal strength P′ main (t) The difference ΔP main (t) satisfies |ΔP main (t)|>P1, it is determined that the communication link of the main antenna is blocked. At this time, the antenna group 101 will be switched to the second working mode. Here, the second working mode corresponds to the working scenario where the main antenna is partially blocked.

[0085] In other possible embodiments, the transmission gain of different positions within the coverage of a communication beam of the low-orbit satellite communication system is different due to the influence of the characteristics of the transmitting antenna. In this case, the first received signal strength is set to the actual received signal strength of the main antenna at a moment before the current moment t. The difference ΔP of the actual signal strength of the main antenna at two adjacent moments is calculated. main (t). Since the link state of the communication channel at two adjacent moments remains basically unchanged when there is no obstruction, if the difference ΔP main (t) is greater than the set second switching threshold P1, that is, it satisfies |ΔP main (t)|>P1, it indicates that the quality of the main antenna communication link has changed significantly between two adjacent moments, and it is determined that the main antenna communication link is blocked at this time. At this time, the antenna group 101 will be switched to the second working mode.

[0086] It should be understood that, in all the possible embodiments described above, the value of the second switching threshold P1 needs to be set differently according to specific scenarios.

[0087] Further, Figure 6 The following are the steps that need to be performed at each time t when the antenna group works in the second working mode:

[0088] Step 81, measure the actual received signal strength P of the main antenna main (t) and the actual received signal strength of the remaining antenna elements, and update the second sorting sequence. Figure 1 The antenna switch 106 controls the receiving channels of the N antenna elements to be turned on in sequence, and uses the power detection unit 105 to measure the satellite signal strength received by each channel, and updates the aforementioned second sorting sequence.

[0089] Step 82: When the maximum actual received signal strength in the second sorting sequence is equal to the actual received signal strength P of the main antenna, main (t) is greater than the third switching threshold P2, the antenna array element with the largest actual received signal strength in the second sorting sequence is switched to the main antenna, and the new main antenna transmits and receives information to and from the satellite. In the case of occlusion, the signal strength of each antenna receiving channel is measured in turn and sorted to determine the element with the best signal quality. The purpose of the third switching threshold P2 is to prevent the main antenna from ping-pong switching between different antenna elements. The value of the third switching threshold P2 needs to be set differently according to the specific scenario.

[0090] Step 83, calculate the sight angles between all antenna elements and the satellite, obtain the gains of all antenna elements by looking up the table, and update the first sorting sequence. The sight angles between each antenna element and the satellite in this step are calculated according to the aforementioned step 3, and the first sorting sequence is updated according to step 4.

[0091] Step 84, within a given period of time T, if the gain G of the main antenna main (t) continues to be the maximum value of the gains of all antenna elements in the first sorting sequence, then the antenna element mode is switched to the first working mode. In order to avoid ping-pong switching between the first working mode and the second working mode, thereby affecting the communication quality under obstruction, the time length T is introduced here. If the gain of the main antenna obtained according to step 3 and step 4 is continuously the same as the maximum value of the gains of all antenna elements in the first sorting sequence within a period of time T, it is determined that the current antenna is in an unobstructed state, and the antenna group 101 switches back to the first working mode. The value of T here needs to be set differently according to the specific scenario.

[0092] It should be noted that the above is only a preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A vehicle-mounted multi-antenna switching method for low-orbit Internet satellite communications, characterized in that: The process includes: Step 1, the antenna group including N antenna elements is powered on, and the position and attitude information of the antenna group is obtained by using the GNSS positioning unit and the inertial navigation unit fixedly connected to the antenna group coordinate system, where N≥5; Step 2, turning on the central component of the antenna group, using the central component to search for satellites, and obtaining the satellite's ephemeris information; Step 3: Based on the obtained satellite ephemeris and the position information and attitude information of the antenna group, obtain the satellite's line of sight elevation angle El in the installation coordinate system of each antenna element. i and the sight azimuth Az i , where i∈{1,2,...,N}; Step 4: Using the pre-stored gain pattern data of each antenna element, the gain G of each antenna element in the satellite line of sight direction is obtained by table lookup. i (El i ,Az i ), and for G i (El i ,Az i ) Sort from large to small to obtain the first sorting sequence, where i∈{1,2,...,N}; Step 5: Turn on N antenna elements and measure the actual signal strength P received by the receiving paths of the N antenna elements respectively. i , for P i Sort from large to small to obtain a second sorting sequence, where i∈{1,2,...,N}; use the antenna component corresponding to the maximum signal strength in the second sorting sequence as the main antenna to send and receive information communication with the satellite; Step 6, determine the working mode of the antenna group: if the antenna element corresponding to the maximum gain in the first sorting sequence is the same as the antenna element corresponding to the maximum signal strength in the second sorting sequence, then determine that the antenna group works in the first working mode, otherwise the antenna group works in the second working mode.

2. According to claim 1, a vehicle-mounted multi-antenna switching method for low-orbit Internet satellite communication is characterized in that: When the antenna group operates in the first operating mode in step 6, the following process is performed: Step 71: Mark each time of switching to the first working mode as the initial time t0, and record the gain G of the main antenna at time t0 main0 , received signal strength P main0 , and the distance d0 between the antenna group and the satellite; Step 72: At each time t, calculate the line-of-sight angles between all antenna elements and the satellite, and obtain the gain G of the main antenna by looking up the table. main (t) and the gains of the remaining antenna elements, and updating the first sorting sequence; Step 73: At each time t, when the maximum gain in the first sorting sequence is equal to the gain G of the main antenna main When the difference between (t) and (t) is greater than the first switching threshold G1, the antenna element corresponding to the maximum gain in the first sorting sequence is switched to the main antenna, and the new main antenna transmits and receives information communication with the satellite; Step 74: Obtain the first received signal strength P of the main antenna at the current time t m ' ain (t), measure the actual received signal strength of the main antenna at the current time t, and calculate the actual received signal strength and the first received signal strength P m ' ain (t) The difference ΔP main (t), if |ΔP main (t)|>P1, the antenna group working mode is switched to the second working mode, where P1 is a preset second switching threshold.

3. A vehicle-mounted multi-antenna switching method for low-orbit Internet satellite communications according to claim 1 or 2, characterized in that: When the antenna group operates in the second operating mode in step 6, at each time t, the following process is performed: Step 81, measure the actual received signal strength P of the main antenna main (t) and the actual received signal strengths of the remaining antenna elements, and updating the second sorting sequence; Step 82: When the maximum actual received signal strength in the second sorting sequence is equal to the actual received signal strength P of the main antenna, main When the difference between (t) and (t) is greater than the third switching threshold P2, the antenna array element with the largest actual received signal strength in the second sorting sequence is switched to the main antenna, and the new main antenna transmits and receives information communication with the satellite; Step 83, calculating the sight angles between all antenna components and the satellite, obtaining the gains of all antenna components by looking up a table, and updating the first sorting sequence; Step 84, within a given period of time T, if the gain G of the main antenna main (t) continues to be the maximum value of the gains of all antenna elements in the first sorting sequence, the antenna group working mode is switched to the first working mode.

4. A vehicle-mounted multi-antenna switching device for low-orbit Internet satellite communications, characterized in that: include: The antenna group includes N ≥ 5 antenna elements, and the N antenna elements are installed at different positions of an antenna array or a vehicle according to different orientation angles to achieve high-gain reception of satellite communication signals in corresponding directions; An inertial navigation unit is strapdown-mounted with the antenna array or the current vehicle and is used to obtain the attitude of the antenna array or the vehicle; A GNSS positioning unit, used to determine the position of the antenna array or the vehicle; A data storage and query unit, used to store the gain pattern data of each antenna element, receive the query instruction of the control unit, and feedback the gain of the required antenna element at a given azimuth and elevation angle; A power detection unit, used to detect the power strength of satellite signals received by receiving channels of different antenna elements in the antenna group; Antenna switching switch, used to switch between receiving and transmitting paths of different antennas; The control unit calculates the elevation angle and azimuth angle of the satellite's line of sight relative to each antenna element based on the information provided by the inertial navigation unit and the GNSS positioning unit, and accesses the data storage and query unit to obtain the antenna gain of the satellite's line of sight direction corresponding to all antenna elements, and accesses the power detection unit as needed to obtain the signal strength of each antenna element receiving channel, and then controls the antenna group to work in the first working mode or the second working mode according to the switching method in any one of claims 1 to 3, completes the antenna switching, determines the main antenna, and controls the main antenna to realize signal reception and transmission with the satellite.

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