Satellite selection method, user terminal, satellite navigation system and medium

Abstract

A satellite selection method, a user terminal, a satellite navigation system and a medium, relating to the technical field of satellite navigation, the method comprising: acquiring a current visual satellite list and a preferential access satellite list determined in advance according to prior information, the preferential access satellite list comprising identifiers of satellites whose uplink access capabilities are greater than a preset threshold; determining an intersection of the preferential access satellite list and the visual satellite list; and under the condition that the intersection is a non-empty set, determining the satellite with the highest elevation parameter in the intersection as the uplink access satellite of the user terminal. According to the invention, the access capability and the elevation parameter of the satellite are considered, the satellite with a high elevation parameter and poor access capability can be prevented from being used as the uplink access satellite, the satellite selection reliability of the user terminal is improved, and the failure rate of uplink access of the user terminal is reduced.

Description

Technical Field

[0001] The present invention relates to the field of satellite navigation technology, and in particular to a method for selecting satellites, a user terminal, a satellite navigation system and a medium. Background Art

[0002] Satellite navigation systems usually include multiple satellites, such as MEO (Medium Earth Orbit) satellites, IGSO (Inclined Geosynchronous Orbit) satellites, etc., which realize the two major functions of navigation positioning and communication data transmission through signal interaction with ground user terminals. They can provide positioning, navigation, timing, short message communication, search and rescue and other services within the working range.

[0003] In practice, the user uplink receivers of MEO (Medium Earth Orbit) satellites are in a large dynamic environment. The visibility time of MEO satellites relative to ground user terminals is short, and user terminals at different locations can see different satellites. When the access capability of the satellite-side user uplink receiver remains unchanged, only from the perspective of the user terminal, the variable factors that affect the user terminal's launch failure usually include: transmit power, transmit Doppler compensation, and uplink access satellite selection (selection of uplink access satellite) strategy. The existing satellite selection strategy is the "highest elevation angle" solution, that is, when the transmit power remains unchanged and the transmit Doppler compensation is corrected, the visible satellite with the highest elevation angle is selected as the uplink access satellite.

[0004] However, since the access capability of the satellite user uplink receiver is uncontrollable and only depends on the system design guarantee, in actual working conditions, the uplink access capabilities of different satellites vary in strength. The uplink access satellite with the highest elevation angle selected by the user terminal may have a weaker access capability, which may lead to the failure of the user terminal to access. Therefore, how to select satellites is directly related to the success rate of uplink data access of user terminals, and has a significant impact on the communication reliability of satellite navigation systems. Summary of the invention

[0005] Embodiments of the present application provide a method for selecting a star, a user terminal, a satellite navigation system, and a medium.

[0006] In a first aspect, an embodiment of the present application provides a method for satellite selection, which is applied to a user terminal in a satellite navigation system, the method comprising: obtaining a current visible satellite list and a priority access satellite list determined in advance based on prior information, the current visible satellite list including identifiers of satellites currently visible to the user terminal, and the priority access satellite list including identifiers of satellites whose uplink access capabilities are greater than a preset threshold; determining the intersection of the priority access satellite list and the visible satellite list; and when the intersection is a non-empty set, determining the satellite with the highest elevation parameter in the intersection as the uplink access satellite of the user terminal.

[0007] In a second aspect, an embodiment of the present application provides a user terminal, which is applied to a satellite navigation system. The satellite navigation system also includes multiple satellites. The user terminal determines an uplink access satellite among the multiple satellites based on the method for selecting satellites in the above embodiment, so as to communicate with the uplink access satellite.

[0008] In a third aspect, an embodiment of the present application provides a satellite navigation system, including a user terminal and multiple satellites; the user terminal determines an uplink access satellite among multiple satellites based on the method for selecting satellites in the above embodiment, and communicates with the accessed satellite.

[0009] In a fourth aspect, an embodiment of the present application provides a non-volatile computer storage medium, which stores a computer program. When the computer program is executed by a processor, the method for selecting stars in the above embodiment is implemented.

[0010] The method for selecting satellites in the embodiments of the present application, when selecting an uplink access satellite for a user terminal, filters out satellites with poor uplink access capabilities by determining in advance priority access satellites with strong uplink access capabilities based on prior information, and then performs an intersection operation on the priority access satellites and currently visible satellites, and selects the satellite with the highest elevation parameter from the intersection as the uplink access satellite for the user terminal, taking into account the satellite's own access capability and elevation parameter, and avoiding using a satellite with a high elevation parameter but poor access capability as an uplink access satellite, thereby improving the reliability of satellite selection by the user terminal, helping to reduce the failure rate of uplink access by the user terminal, and thus improving the communication reliability of the satellite navigation system.

[0011] Other features and advantages of the present application will be described in the following description, and partly become apparent from the description, or be understood by implementing the present application. Other advantages of the present application can be realized and obtained by the schemes described in the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The accompanying drawings are used to provide an understanding of the technical solution of the present application and constitute a part of the specification. Together with the embodiments of the present application, they are used to explain the technical solution of the present application and do not constitute a limitation on the technical solution of the present application.

[0013] Figure 1 A schematic diagram of the architecture of an embodiment of a satellite navigation system of the present application; Figure 2 A schematic diagram of a flow chart of an embodiment of a method for selecting stars in the present application; Figure 3 A schematic diagram of a process of obtaining a current visible satellite list in one embodiment of a method for selecting satellites in the present application; Figure 4 A schematic diagram of a flow chart of determining elevation parameters of visible satellites in one embodiment of a method for selecting satellites in the present application; Figure 5 A schematic diagram of a flow chart of an embodiment of a method for selecting stars in the present application; Figure 6 The following is a flow chart of another embodiment of the method for selecting stars of the present application. DETAILED DESCRIPTION

[0014] The present application describes multiple embodiments, but the description is exemplary rather than restrictive, and it is obvious to those skilled in the art that there may be more embodiments and implementations within the scope of the embodiments described in the present application. Although many possible feature combinations are shown in the drawings and discussed in the specific embodiments, many other combinations of the disclosed features are also possible. Unless specifically limited, any feature or element of any embodiment may be used in combination with any other feature or element in any other embodiment, or may replace any other feature or element in any other embodiment.

[0015] The present application includes and contemplates combinations of features and elements known to those of ordinary skill in the art. The embodiments, features and elements disclosed in the present application may also be combined with any conventional features or elements to form a unique invention scheme. Any features or elements of any embodiment may also be combined with features or elements from other invention schemes to form another unique invention scheme. Therefore, it should be understood that any feature shown and / or discussed in the present application may be realized individually or in any appropriate combination. Therefore, except for the limitations made according to the attached claims and their equivalents, the embodiments are not subject to other restrictions. In addition, various modifications and changes may be made within the scope of protection of the attached claims.

[0016] In addition, when describing representative embodiments, the specification may have presented the method and / or process as a specific sequence of steps. However, to the extent that the method or process does not rely on the specific order of the steps described herein, the method or process should not be limited to the steps of the specific order described. As will be understood by those of ordinary skill in the art, other sequences of steps are also possible. Therefore, the specific sequence of the steps set forth in the specification should not be interpreted as a limitation to the claims. In addition, the claims for the method and / or process should not be limited to the steps of performing them in the order written, and those skilled in the art can easily understand that these sequences can be changed and still remain within the spirit and scope of the embodiments of the present application.

[0017] Figure 1 A schematic diagram of the architecture of an embodiment of the satellite navigation system of the present application is shown as follows: Figure 1 As shown, the satellite navigation system includes a user terminal and multiple satellites. The user terminal determines an uplink access satellite from multiple satellites based on the method for selecting satellites in any of the following embodiments, and communicates with the accessed satellite.

[0018] In this embodiment, the satellite navigation system can be a global satellite navigation system (Global Navigation Satellite System, GNSS), for example, it can be the Global Positioning System (Navigation Satellite Timing and Ranging / Global Positioning System, GPS) established and developed by the United States, the Galileo satellite navigation system (Galileo) developed by European Union countries, and the Beidou-3 navigation system developed by China.

[0019] Typically, a satellite navigation system may include multiple satellites, such as MEO satellites and IGSO satellites, which can send downlink signals at preset frequencies and receive uplink signals sent by user terminals on the ground (on the surface and 1,000 kilometers above the surface).

[0020] The user terminal can be, for example, a vehicle-mounted positioning terminal installed in a car, a built-in positioning terminal in an aircraft, or a positioning module in a smart phone. After the user terminal uplinks to a satellite (such as a MEO satellite), it can send uplink signals to the connected satellite and receive downlink signals sent by the satellite. Through signal interaction with the satellite, the user terminal can obtain various services such as navigation positioning and communication data transmission provided by the satellite navigation system.

[0021] As an example, the satellite navigation system may be the BeiDou-3 satellite navigation system (BDS3), and the user terminal may be a GSMC (Global Short Message Communication Service) terminal. The space constellation of BDS3 uses more than 14 MEO satellites equipped with L-band user uplink receivers, and achieves uplink coverage for global users through intersatellite links. At the same time, it uses the downlink navigation B2b signals of 3 IGSO satellites and 24 MEO satellites to broadcast user downlink messages. GSMC provides three types of services, namely, message communication, position reporting, and emergency search and rescue, to licensed users (or authorized users) located on the surface and 1,000 kilometers above the surface. For authorized users, the GSMC service provides an on-board confirmation mechanism on satellites with uplink access capabilities, that is, after the user terminal selects an uplink access satellite, it can send an uplink application to the access satellite. When the access satellite receives it, the access satellite can notify the user terminal of the successful uplink application access through the downlink B2b channel with the broadcast message type MsgType4. Afterwards, the user terminal can interact with the access satellite to obtain various services of BDS3.

[0022] In this embodiment, the user terminal can select an uplink access satellite by the method for selecting a satellite in any of the following embodiments, and filter out satellites with poor uplink access capabilities by determining in advance the priority access satellites with stronger uplink access capabilities based on prior information, and then perform an intersection operation on the priority access satellites and the currently visible satellites, and then select the satellite with the highest elevation parameter from the intersection as the uplink access satellite of the user terminal. In this way, the satellite's own access capability and elevation parameter are taken into account, and a satellite with a higher elevation parameter but poorer access capability can be avoided as an uplink access satellite, thereby improving the reliability of the user terminal's satellite selection, helping to reduce the failure rate of the user terminal's uplink access, and thus improving the communication reliability of the satellite navigation system.

[0023] Figure 1 The user terminal in the satellite navigation system shown can use Figure 2 The process shown selects the uplink access satellite, such as Figure 2 As shown, the process includes the following steps.

[0024] Step 210: Obtain a current visible satellite list and a priority access satellite list determined in advance based on prior information.

[0025] The currently visible satellite list includes identifiers of satellites currently visible to the user terminal, and the priority access satellite list includes identifiers of satellites whose uplink access capabilities are greater than a preset threshold.

[0026] In this embodiment, the uplink access capability refers to the access capability of the satellite end user uplink receiver. For the same user terminal, the stronger the uplink access capability of the satellite, the higher the success rate of the user terminal applying for uplink access.

[0027] Prior information can characterize the strength of the satellite's uplink access capability. For example, the receive / transmit closed loop success rate between the user terminal and the satellite can be used as prior information. Accordingly, the preset threshold can be set according to the receive / transmit closed loop success rate to screen out satellites with strong uplink access capabilities, and generate a priority access satellite list based on the identification of the screened satellites. The satellite identification can be, for example, the unique number of the satellite.

[0028] The satellites currently visible to the user terminal (also called the current transiting satellites) indicate the satellites that the user terminal can currently access. The currently visible satellites can be identified based on the downlink signals (such as the BDS3 GSMC service downlink B2b frequency signal) received in real time by the user terminal and recorded in the visible satellite list.

[0029] In an optional example, the user terminal may be a GSMC terminal in BDS3, and the currently visible satellite and the priority access satellite may be MEO satellites in BDS3.

[0030] Step 220: Determine the intersection of the priority access satellite list and the visible satellite list.

[0031] In this embodiment, an intersection operation may be performed on the set of priority access satellites in the priority access satellite list and the currently visible satellites in the visible satellite list to determine the intersection of the priority access satellite list and the visible satellite list. The satellites in the intersection represent satellites that are currently visible to the user and have strong uplink access capabilities.

[0032] Step 230: When the intersection is a non-empty set, the satellite with the highest elevation parameter in the intersection is determined as the uplink access satellite of the user terminal.

[0033] As an example, when there is a satellite in the intersection of the priority access satellite list and the visible satellite list, the satellite can be directly used as the uplink access satellite of the user terminal; when there are multiple satellites in the intersection, the elevation parameters of each satellite can be calculated, and then the satellite with the highest elevation angle can be selected as the uplink access satellite of the user terminal. After that, the user terminal can send an uplink access application to the uplink access satellite. When the uplink access satellite receives the uplink access application through the on-board confirmation mechanism, it can notify the user terminal of the success of the uplink access application through the downlink B2b channel in a broadcast message, so that the user terminal can interact with the access satellite to obtain various services of BDS3.

[0034] Step 240: When the intersection is an empty set, a currently visible satellite with the highest elevation parameter is selected from the currently visible satellite list as the uplink access satellite of the user terminal.

[0035] In this embodiment, the priority access satellites with stronger uplink access capabilities are determined in advance based on prior information, and satellites with weaker uplink access capabilities are filtered out. Then, an intersection operation is performed on the priority access satellites and the currently visible satellites, and then the satellite with the highest elevation parameter is selected from the intersection as the uplink access satellite of the user terminal. In this way, the satellite's own access capability and elevation parameter are taken into account, and a satellite with a higher elevation parameter but poorer access capability can be avoided as an uplink access satellite, which improves the reliability of user terminal satellite selection and helps reduce the failure rate of user terminal uplink access, thereby improving the communication reliability of the satellite navigation system.

[0036] In some embodiments, the uplink access capability can be characterized by the receive / transmit closed-loop success rate, and the satellites in the priority access satellite list with uplink access capabilities greater than a preset threshold can be determined in the following manner: measuring the receive / transmit closed-loop success rate of the user terminal relative to each transit access satellite at a preset position; and determining the satellites with a receive / transmit closed-loop success rate greater than a preset success rate threshold as satellites with uplink access capabilities greater than the preset threshold (i.e., priority access satellites).

[0037] Afterwards, the identifiers of all priority access satellites may be recorded in a list to obtain a priority access satellite list.

[0038] Taking BDS3 as an example, the user terminal can be used to measure the receive / transmit closed loop success rate of each GSMC service satellite in BDS3 in real time at the preset location, and then compare the success rate threshold, and take the satellite with a success rate greater than the success rate threshold as the priority access satellite and record it in the priority access satellite list. Here, the success rate threshold can be 80%, 90% or other.

[0039] In this embodiment, the access capability of the satellite itself can be characterized by the receive / transmit closed-loop success rate, and satellites with a success rate greater than a success rate threshold are used as a priority access satellite list, which can filter out satellites with poor access capabilities, thereby avoiding using satellites with poor access capabilities as uplink access satellites for user terminals, which helps to improve the reliability of satellite selection by user terminals and reduce the failure rate of uplink access.

[0040] In some optional implementations of this embodiment, the following may be included: Step 200: pre-storing the priority access satellite list in a non-volatile memory in the user terminal.

[0041] As an example, after determining the priority access satellite list, the user terminal may store the priority access satellite list in a local flash memory, and when executing the above step 210, the priority access satellite list may be directly read from the flash memory.

[0042] In this embodiment, the priority access satellite list can be separated from the algorithm and stored separately in the non-volatile memory of the user terminal. The user terminal can read the priority access satellite list from the non-volatile memory more quickly when starting up or selecting a satellite.

[0043] In some embodiments, the current visible satellite list is provided by Figure 3 The process shown is obtained, such as Figure 3 As shown, the process includes the following steps.

[0044] Step 310: Perform message frame synchronization processing based on the currently received downlink frequency signal of the satellite.

[0045] Step 320: Identify the identifiers of currently visible satellites according to the uplink access capability message identifier of the currently received satellite, and record them in a list to obtain a list of currently visible satellites.

[0046] In this embodiment, the downlink frequency signal may be a signal sent by a satellite at a preset frequency, such as a downlink B2b signal sent by a MEO satellite in BDS3 at a B2b frequency.

[0047] As an example, the user terminal may be a GSMC terminal in BDS3, and according to the BDS3GSMC service downlink B2b frequency signal currently received by the GSMC terminal, the message frame synchronization processing is completed, so that the GSMC terminal can determine the starting position and the ending position of the data frame in the signal sent by the satellite, thereby parsing the original data from the signal. Afterwards, when the GSMC receives the uplink access capability message broadcast by the MEO satellite downlink B2b frequency (for example, it may be the original navigation message in the B-CNAV3 format), the satellite identifier can be parsed from the message, and then recorded as the identifier of the visible satellite in the current visible satellite list.

[0048] In this embodiment, message frame synchronization processing can be performed according to the downlink frequency signal received by the user terminal, and the identifier of the currently visible satellite can be parsed from the currently received uplink access capability message, so that the satellite currently visible to the user terminal can be accurately and quickly determined.

[0049] In some embodiments, Figure 4 The process shown determines the elevation parameters of the visible satellites, such as Figure 4 As shown, the process may include the following steps.

[0050] Step 410: Calculate the current position of the user terminal based on the downlink frequency signal of the visible satellite.

[0051] Step 420: Determine elevation parameters of visible satellites based on the current position of the user terminal and the ephemeris parameters of the visible satellites.

[0052] As an example, the user terminal can be a GSMC terminal in BDS3, which can calculate the current position of the user terminal based on the BDS3 GSMC service downlink B2b frequency signal currently received by the GSMC terminal, and then determine the elevation angle parameters of the satellite by combining the current position of the user terminal with the ephemeris parameters of the satellite that sends the downlink B2b frequency signal.

[0053] In this embodiment, the current position of the user terminal can be calculated based on the downlink frequency signal received by the user terminal, and the elevation parameters of the visible satellites can be determined in combination with the ephemeris parameters of the visible satellites, which helps to improve the calculation accuracy of the elevation parameters.

[0054] Figure 5 A flow chart of an embodiment of the method for selecting stars of the present application is shown as follows: Figure 5 As shown, the process may include the following steps.

[0055] Step 510: Obtain a current visible satellite list and a priority access satellite list determined in advance based on prior information.

[0056] Step 520: Determine the intersection of the priority access satellite list and the visible satellite list.

[0057] Step 530: When the intersection is a non-empty set, the satellite with the highest elevation parameter in the intersection is determined as the uplink access satellite of the user terminal.

[0058] Step 540: When the intersection is an empty set, a currently visible satellite with the highest elevation parameter is selected from the currently visible satellite list as the uplink access satellite of the user terminal.

[0059] In this embodiment, steps 510 to 540 correspond to the aforementioned steps 210 to 240 and are not described again here.

[0060] Step 550: Send an uplink application to the uplink access satellite to access the uplink access satellite.

[0061] Step 560: After accessing the uplink access satellite, when the communication with the uplink access satellite is disconnected, update the current visible satellite list and the intersection, and determine a new uplink access satellite to access the new uplink access satellite.

[0062] Taking BDS3 as an example, the user terminal (for example, a GSMC terminal) can send an uplink application to the uplink access satellite. The GSMC service of BDS3 can provide an on-board confirmation mechanism for the uplink access satellite. When the uplink application is accepted, the uplink access satellite can broadcast a message of MsgType4 through the downlink B2b channel to notify the user terminal that the uplink application access is successful. Subsequently, the user terminal can communicate with the uplink access satellite.

[0063] In practice, various factors may cause the user terminal to lose or be unable to see the downlink signal of the satellite, that is, the communication between the satellite and the user terminal is disconnected, and the user terminal may re-uplink to the satellite to obtain the corresponding service. At this time, the satellite currently visible to the user terminal has changed, for example, the uplink access satellite is no longer visible, and the currently visible satellite can be re-determined to update the current visible satellite list, and then step 520 is executed again to update the intersection of the priority access satellite list and the visible satellite list, and then a new uplink access satellite is selected through step 530 or step 540, and the new uplink access satellite is accessed through step 550.

[0064] In this embodiment, when the communication between the user terminal and the uplink access satellite is disconnected and an uplink access satellite needs to be reselected, the current visible satellite list and intersection can be updated, and a new uplink access satellite can be determined. This can maintain the continuity of satellite selection, help reduce the failure rate of uplink access of the user terminal, and thus improve the communication reliability of the satellite navigation system.

[0065] Figure 6 A flow chart of an embodiment of the method for selecting stars of the present application is shown as follows: Figure 6 As shown, the process may include the following steps.

[0066] Step 610: Obtain a current visible satellite list and a priority access satellite list determined in advance based on prior information.

[0067] Step 620: Determine the elevation parameters of visible satellites.

[0068] Step 630: The satellite with the largest elevation angle parameter among the visible satellites is selected as a candidate access satellite.

[0069] As an example, the user terminal can receive the downlink frequency signal in real time through Figure 3 The illustrated embodiment determines the current visible satellite list and Figure 4 The illustrated embodiment determines the elevation angle parameter of each visible satellite, and then selects the satellite with the largest elevation angle parameter among the visible satellites as a candidate access satellite.

[0070] In this embodiment, the elevation angle parameter of each visible satellite can be determined when the visible satellite is determined, which can reduce the number of repeated readings of data, help reduce the amount of calculation, and improve the timeliness of the elevation angle parameter.

[0071] Step 640: Determine the intersection of the priority access satellite list and the visible satellite list.

[0072] Step 650: When the intersection is an empty set, the candidate access satellite is used as the uplink access satellite of the user terminal.

[0073] In this embodiment, the intersection of the priority access satellite list and the visible satellite list is empty, indicating that the priority access satellites with stronger access capabilities are not visible to the user terminal at the current moment. At this time, according to the strategy of the largest elevation angle, the candidate access satellite with the largest elevation angle can be used as the uplink access satellite of the user terminal to ensure the reliability of the user terminal's satellite selection.

[0074] Step 660: When the intersection is a non-empty set, determine whether the intersection includes a candidate access satellite.

[0075] Step 670: When the intersection includes the candidate access satellite, use the candidate access satellite as the uplink access satellite of the terminal.

[0076] Step 680: When the intersection does not include the candidate access satellite, determine the satellite with the highest elevation parameter in the intersection and use it as the uplink access satellite of the terminal.

[0077] In some optional implementations of this embodiment, after determining the uplink access satellite through step 650 or step 660, step 670, and step 680, the process may also include the above-mentioned steps 550 and 560, so that the reliability of satellite selection can be maintained when reselecting the satellite.

[0078] An embodiment of the present application also provides a user terminal, which is applied to a satellite navigation system. The satellite navigation system also includes multiple satellites. The user terminal determines an uplink access satellite among the multiple satellites based on the method for selecting satellites in any of the above embodiments, so as to communicate with the uplink access satellite.

[0079] An embodiment of the present application also provides a non-volatile computer storage medium, which stores a computer program. In some embodiments, when the computer program is executed by a processor, the method of multi-model collaborative processing of security operation tasks in any of the above embodiments is implemented.

[0080] It will be appreciated by those skilled in the art that all or some of the steps, systems, and functional modules / units in the methods disclosed above may be implemented as software, firmware, hardware, and appropriate combinations thereof. In hardware implementations, the division between the functional modules / units mentioned in the above description does not necessarily correspond to the division of physical components; for example, a physical component may have multiple functions, or a function or step may be performed by several physical components in cooperation. Some or all components may be implemented as software executed by a processor, such as a digital signal processor or a microprocessor, or implemented as hardware, or implemented as an integrated circuit, such as an application-specific integrated circuit. Such software may be distributed on a computer-readable medium, which may include a computer storage medium (or non-transitory medium) and a communication medium (or transient medium). As is known to those skilled in the art, the term "computer storage medium" includes volatile and non-volatile, removable and non-removable media implemented in any method or technology for storing information (such as computer-readable instructions, data structures, program modules, or other data). Computer storage media include, but are not limited to, RAM, ROM, EEPROM, flash memory or other memory technology, CD-ROM, digital versatile disks (DVD) or other optical disk storage, magnetic cassettes, magnetic tapes, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to store the desired information and can be accessed by a computer. In addition, it is well known to those skilled in the art that communication media typically contain computer-readable instructions, data structures, program modules, or other data in a modulated data signal such as a carrier wave or other transport mechanism, and may include any information delivery media.

Claims

1. A method for selecting satellites, applied to a user terminal in a satellite navigation system, characterized in that: include: Acquire a current visible satellite list and a priority access satellite list determined in advance according to prior information, wherein the current visible satellite list includes identifiers of satellites currently visible to the user terminal, and the priority access satellite list includes identifiers of satellites whose uplink access capabilities are greater than a preset threshold; Determine the intersection of the priority access satellite list and the visible satellite list; In the case that the intersection is a non-empty set, the satellite with the highest elevation angle parameter in the intersection is determined as the uplink access satellite of the user terminal.

2. The method according to claim 1, characterized in that The satellite whose uplink access capability is greater than a preset threshold is determined in the following manner: Measuring the receiving / transmitting closed loop success rate of the user terminal relative to each transit access satellite at a preset position; A satellite whose receiving / transmitting closed-loop success rate is greater than a preset success rate threshold is used as a satellite whose uplink access capability is greater than the preset threshold.

3. The method according to claim 1, characterized in that Before obtaining the current visible satellite list and the priority access satellite list determined in advance according to prior information, the method further includes: The priority access satellite list is stored in advance in a non-volatile memory in the user terminal, so that the user terminal reads the priority access satellite list from the non-volatile memory.

4. The method according to claim 1, characterized in that: The current visible satellite list is obtained by: Based on the downlink frequency signal of the currently received satellite, the message frame synchronization processing is performed; According to the uplink access capability message identifier of the currently received satellite, the identifier of the currently visible satellite is identified and recorded in a list to obtain the currently visible satellite list.

5. The method according to claim 1, characterized in that: After determining the satellite with the highest elevation angle parameter in the intersection as the uplink access satellite of the user terminal, the method further includes: sending an uplink application to the uplink access satellite so as to access the uplink access satellite; and, After accessing the uplink access satellite, in the case where communication with the uplink access satellite is disconnected, the current visible satellite list and the intersection are updated, and a new uplink access satellite is determined so as to access the new uplink access satellite.

6. The method according to claim 1, characterized in that Before determining the intersection of the priority access satellite list and the visible satellite list, the method further includes: determining elevation parameters of the visible satellites, and selecting the satellite with the largest elevation parameter among the visible satellites as a candidate access satellite; and, In the case that the intersection is a non-empty set, determining the satellite with the highest elevation parameter in the intersection as the uplink access satellite of the user terminal includes: using the candidate access satellite as the uplink access satellite of the terminal.

7. The method according to claim 6, characterized in that When the intersection is a non-empty set, the satellite with the highest elevation parameter in the intersection is determined as the uplink access satellite of the terminal, including: judging whether the intersection includes the candidate access satellite; when the intersection includes the candidate access satellite, using the candidate access satellite as the uplink access satellite of the terminal.

8. A user terminal, applied to a satellite navigation system, wherein the satellite navigation system further comprises a plurality of satellites, characterized in that: The user terminal determines an uplink access satellite among the plurality of satellites based on the method for selecting satellites according to any one of claims 1 to 7, so as to communicate with the uplink access satellite.

9. A satellite navigation system, characterized in that: It comprises a user terminal and a plurality of satellites; the user terminal determines an uplink access satellite among the plurality of satellites based on the method for selecting satellites according to one of claims 1 to 7, and communicates with the accessed satellite.

10. A non-transitory computer storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, the method for selecting stars according to any one of claims 1 to 7 is implemented.

Images