Navigation processing method and system based on low earth orbit satellite

Abstract

The invention provides a navigation processing method and system based on a low-orbit satellite, and belongs to the technical field of navigation, and the method comprises the steps: obtaining observation data based on a ground monitoring station, a GNSS receiver carried by the low-orbit satellite and a ground sensor; executing orbit determination solution and determining clock correction to form navigation information; encoding the navigation information, and uploading the navigation information to a low-orbit satellite through a ground data transmission station or an inter-satellite link; and the low-orbit satellite broadcasts the navigation information to the ground terminal in real time through the information broadcasting module. And the ground terminal receives navigation signals from the low-orbit satellite and the GNSS satellite, tracks and demodulates the navigation signals, and extracts navigation information. According to the invention, multivariate observation data of a ground monitoring station, a GNSS receiver carried by a low-orbit satellite and a ground sensor are integrated, and the accuracy and real-time performance of navigation information are improved through a precise orbit determination solution and clock error determination technology.

Description

Technical Field

[0001] The present invention belongs to the field of navigation technology, and in particular relates to a navigation processing method and system based on a low-orbit satellite. Background Art

[0002] With the development of global navigation technology, the demand for high-precision, high-reliability, and real-time navigation services is growing. Although traditional global navigation satellite systems (GNSS), such as GPS, GLONASS, Galileo, and BeiDou, can provide navigation services with global coverage, their positioning accuracy and convergence speed may be limited in certain application scenarios, such as in complex environments such as urban canyons and mountainous areas. In order to make up for this shortcoming, low-orbit satellite navigation is currently used to achieve navigation and positioning in complex environments such as urban canyons and mountainous areas.

[0003] However, the existing navigation and positioning methods can only obtain observation data in a single way, resulting in inaccurate navigation and positioning data and imprecise position. Since the clock error is not effectively determined, the clock error of the low-orbit satellite cannot be obtained, resulting in poor accuracy of time synchronization and unable to meet the high-precision requirements of real-time navigation. Summary of the invention

[0004] The present invention provides a navigation processing method based on low-orbit satellites, which integrates the multivariate observation data of ground monitoring stations, GNSS receivers carried by low-orbit satellites, and ground sensors, and also improves the accuracy and real-time performance of navigation information through precise orbit determination and clock error determination technology.

[0005] Methods include: S101: Obtain observation data based on ground monitoring stations, GNSS receivers on low-orbit satellites, and ground sensors; S102: Execute orbit determination and clock error determination to form navigation information; S103: Encode the navigation information and upload the navigation information to the low-orbit satellite through a ground data transmission station or an inter-satellite link; the low-orbit satellite broadcasts the navigation information to the ground terminal in real time through an information broadcast module; wherein the navigation information format is configured according to a preset format; S104: The ground terminal receives navigation signals from low-orbit satellites and GNSS satellites, tracks and demodulates the navigation signals, and extracts navigation information.

[0006] It should be further explained that in step S101, the observation data includes observation data of low-orbit satellites by ground monitoring stations, observation data of inter-satellite links between low-orbit satellites, and observation data of medium- and high-orbit navigation satellites.

[0007] It should be further explained that step S102 also includes: S1021: Processing the observation data by detecting cycle slips and eliminating gross errors; S1022: Obtaining the position sequence and clock error of the navigation satellite and the low-orbit satellite based on the navigation satellite broadcast ephemeris; S1023: Perform orbit integration based on the dynamic parameters of the navigation satellite and the low-orbit satellite, and obtain the initial orbit and state transfer matrix; S1024: Configure the joint orbit determination mode, set additional prior constraints on the parameters to be estimated, and use the least squares batch processing method to superimpose the normal equations of the epochs to solve the parameters to be estimated; S1025: perform orbit integration on navigation satellites and low-orbit satellites using dynamic parameter information to obtain orbit and observation value residuals; S1026: Perform observation value residual test. After the post-test residual is less than the preset residual threshold, double difference ambiguity fixation is performed to obtain an ambiguity fixation mark, and parameter estimation of the additional ambiguity fixation mark is performed again.

[0008] It should be further explained that, in step S1021, the Mw combination method is used to perform cycle slip detection on the ground monitoring station, the GNSS receiver carried by the low-orbit satellite, and the ground sensor to obtain the cycle slip detection result; Then the GF combination method is used to perform secondary cycle slip detection on the cycle slip detection results to obtain the secondary cycle slip detection results.

[0009] It should be further explained that, in step S101, a data communication link is established between the ground monitoring station, the low-orbit satellite and the ground sensor; The ground monitoring station is used to continuously observe low-orbit satellites and collect observation data including pseudorange and carrier phase; GNSS receivers continuously receive signals from medium and high orbit navigation satellites; A data processing center is also configured to receive and integrate all observation data.

[0010] It should be further explained that step S102 also includes: determining the orbital parameters of the low-orbit satellite based on a dynamic model and a numerical integration method; The orbit determination solution uses numerical integration method, combined with observation data and dynamic model, to carry out precise orbit determination solution for low-orbit satellites; Based on the precise orbit determination results, the orbit of the low-orbit satellite is predicted in the short term to meet real-time navigation needs.

[0011] It should be further explained that in the method, after completing the orbit determination and clock error determination, the encoding stage of the navigation information is entered; Encode orbit determination results, clock error information and navigation parameters to form a standard navigation information format; After the encoding is completed, the navigation information will be uploaded to the low-orbit satellite through the ground data transmission station or inter-satellite link; the information broadcasting module carried by the low-orbit satellite is used to broadcast the navigation information to the ground terminal in real time.

[0012] It should be further explained that step S104 also includes: the ground terminal tracks and demodulates the navigation signal, extracts navigation information, and uses the least square method or Kalman filtering method to solve the navigation signal to achieve positioning and time synchronization of the ground terminal.

[0013] It should be further noted that the method further includes: determining the number of orbital planes according to the coverage requirement and the number of satellites; Define the number of low-orbit satellites in each orbital plane to ensure the number of low-orbit satellites in each orbital plane; Determine the relative position of low-orbit satellites in the constellation by calculating the best phase factor to optimize inter-satellite links and signal coverage; Define coverage area and orbit inclination; Establish a navigation optimization model for multi-target low-orbit satellites; Set constraints on the number of satellites and orbital parameter ranges; Use the global search capability of genetic algorithms to find the optimal solution in the parameter space; The particle swarm algorithm is used to optimize the navigation optimization model of multi-target low-orbit satellites; the navigation optimization model of multi-target low-orbit satellites is adjusted.

[0014] According to another embodiment of the present application, a navigation processing system based on a low-orbit satellite is provided, the system comprising: Data observation component, which obtains observation data based on ground monitoring stations, GNSS receivers carried by low-orbit satellites, and ground sensors; Information processing components, used to perform orbit determination and determine clock errors to form navigation information; The coded navigation processing component is used to encode the navigation information and upload the navigation information to the low-orbit satellite through the ground data transmission station or the inter-satellite link; the low-orbit satellite broadcasts the navigation information to the ground terminal in real time through the information broadcast module; The ground terminal is used to receive navigation signals from low-orbit satellites and GNSS satellites, track and demodulate the navigation signals, and extract navigation information.

[0015] It can be seen from the above technical solutions that the present invention has the following advantages: The navigation processing method based on low-orbit satellites provided in this application is based on the precise orbit determination results and realizes the prediction of the orbit of low-orbit satellites. It also combines the dynamic model and real-time observation data to accurately predict the orbit changes of low-orbit satellites in the short term in the future, thereby meeting the high-precision requirements of real-time navigation.

[0016] The navigation processing method based on low-orbit satellites provided in this application improves the accuracy and real-time performance of navigation. By integrating the observation data of ground monitoring stations, GNSS receivers carried by low-orbit satellites, and ground sensors, the information required for navigation can be obtained, thereby improving the accuracy of navigation. The numerical integration method and precise orbit determination solution technology are used to determine the orbit of low-orbit satellites, ensuring the accuracy of navigation.

[0017] The present invention enhances the stability and reliability of the navigation system by introducing intersatellite link observation data. The existence of intersatellite links enables direct data transmission and calibration between low-orbit satellites, reduces dependence on ground facilities, and improves the adaptability of the navigation system in complex environments.

[0018] The navigation processing method based on low-orbit satellites provided in the present application effectively improves the accuracy of time synchronization by determining the clock error. The clock error of the low-orbit satellite can be more accurately calculated, thereby achieving more accurate time synchronization. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solution of the present invention, the accompanying drawings required for use in the description will be briefly introduced below. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0020] Figure 1 The flowchart of the navigation processing method based on low-orbit satellite is as follows; Figure 2 The present invention is a flowchart of an embodiment of a navigation processing method based on a low-orbit satellite; Figure 3 Schematic diagram of the navigation processing system based on low-orbit satellites. DETAILED DESCRIPTION

[0021] The low-orbit satellite-based navigation processing method provided in this application integrates multi-dimensional observation data from ground monitoring stations, GNSS receivers carried by low-orbit satellites, and ground sensors, and also significantly improves the accuracy and real-time performance of navigation information through precise orbit determination and clock error determination technology.

[0022] This application can realize the comprehensive fusion of observation data of low-orbit satellites, inter-satellite links between low-orbit satellites, and medium- and high-orbit navigation satellites by ground monitoring stations. This data fusion method can make full use of the advantages of various types of observation data and improve the reliability and accuracy of navigation information.

[0023] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0024] See also Figure 1 FIG. 1 is a flowchart of a navigation processing method based on a low-orbit satellite in a specific embodiment, the method comprising: S101: Obtain observation data based on ground monitoring stations, GNSS receivers on low-orbit satellites, and ground sensors.

[0025] In some embodiments, based on ground monitoring stations, GNSS receivers carried by low-orbit satellites and other related sensors, observation data including ground monitoring stations on low-orbit satellites, inter-satellite link observation data between low-orbit satellites, observation data of medium and high-orbit navigation satellites, etc. are obtained.

[0026] S102: Execute orbit determination and determine clock error to form navigation information.

[0027] In this embodiment, the observation data acquired by the ground monitoring station, the GNSS receiver onboard the low-orbit satellite, and the inter-satellite link equipment are jointly processed.

[0028] Optionally, the orbit determination solution can use a numerical integration method, combined with observation data and a dynamic model, to perform precise orbit determination solutions for low-orbit satellites.

[0029] This embodiment makes a short-term prediction (eg, 1-2 hours) of the orbit of the low-orbit satellite based on the precise orbit determination results to meet the real-time navigation needs.

[0030] In this embodiment, constraints may be set for clock error determination, that is, satellite clock error determination is performed using real-time observation data under the constraints of precise satellite orbits.

[0031] As for clock error calculation, Kalman filtering can be used to calculate the clock error of low-orbit satellites.

[0032] S103: Encode the navigation information and upload the navigation information to the low-orbit satellite through a ground data transmission station or an inter-satellite link; the low-orbit satellite broadcasts the navigation information to the ground terminal in real time through an information broadcast module; wherein the navigation information format is configured according to a preset format; In this embodiment, the precise orbit and clock error calculation results are encoded as navigation information. This ensures that the format of the navigation information complies with relevant standards and specifications, making it easier for users to receive and decode. The navigation information is uploaded to the low-orbit satellite through a ground data transmission station or an intersatellite link.

[0033] S104: The ground terminal receives navigation signals from low-orbit satellites and GNSS satellites, tracks and demodulates the navigation signals, and extracts navigation information.

[0034] In this embodiment, the ground user configures a compatible receiver to receive navigation signals from low-orbit satellites and GNSS satellites. The receiver tracks and demodulates the received signals to extract navigation information. The navigation information from the low-orbit satellites and GNSS satellites is fused and processed.

[0035] The navigation processing method based on low-orbit satellites provided in this application is based on the precise orbit determination results, and realizes the short-term prediction of the orbit of low-orbit satellites. It also combines the dynamic model and real-time observation data, and can accurately predict the orbit changes of low-orbit satellites in the short term in the future, thereby meeting the high-precision requirements of real-time navigation. Moreover, after the ground terminal receives the navigation signal, this embodiment uses advanced algorithms such as least squares method or Kalman filtering to solve the navigation signal. It can make full use of the redundant information of the observation data, improve the stability and accuracy of the solution, and realize high-precision positioning and time synchronization of the ground terminal.

[0036] Based on the above method, the following are specific steps for performing orbit determination and clock error determination to form navigation information, such as Figure 2 As shown, the specific steps include: S1021: Processing the observation data based on detecting cycle slips and eliminating gross errors.

[0037] In this embodiment, cycle slip detection is based on two assumptions: the phase measurement value of the GNSS signal changes continuously and the clock error of the satellite receiver changes slowly. Whether a cycle slip occurs is determined by comparing the phase measurement values ​​at two consecutive moments.

[0038] In this embodiment, the phase difference value can be calculated using the carrier phase measurement value of the GNSS signal. That is, the phase difference value and the wavelength of the GNSS signal are used to calculate the distance change corresponding to the phase difference value. If the distance change corresponding to the phase difference value exceeds a threshold of one wavelength, it is considered that a cycle slip has occurred.

[0039] In this embodiment, the gross errors can be eliminated by preprocessing the observed data and calculating the arithmetic mean and residual error. When calculating the standard deviation, a suitable interval is set. Errors exceeding the interval are regarded as gross errors and eliminated.

[0040] S1022: Obtain the position sequence and clock error of the navigation satellite and the low-orbit satellite based on the navigation satellite broadcast ephemeris.

[0041] This embodiment can receive broadcast ephemeris from navigation satellites at a ground receiving station. The broadcast ephemeris is decoded to extract the position sequence and clock error information of navigation satellites and low-orbit satellites. The extracted position sequence and clock error information are synchronized with the time system of the ground receiving station to ensure the accuracy and consistency of the data.

[0042] S1023: Perform orbital integration based on the dynamic parameters of the navigation satellite and the low-orbit satellite, and obtain the initial orbit and state transfer matrix.

[0043] In this embodiment, the determined dynamic parameters include the initial position, velocity, mass, thrust, etc. of the satellite. Based on the dynamic parameters, the motion equation of the satellite is established.

[0044] Optionally, the numerical integration method can be selected to use the Runge-Kutta method to solve the satellite's motion equation. The satellite's motion equation is then integrated using the numerical integration method to obtain the satellite's orbit sequence. During the integration process, the satellite's state changes are recorded and a state transfer matrix is ​​generated to describe the evolution of the satellite's state over time.

[0045] S1024: Configure the joint orbit determination mode, set additional prior constraints on the parameters to be estimated, and use the least squares batch processing method to superimpose the normal equations of the epochs to solve the parameters to be estimated.

[0046] This embodiment selects a suitable joint orbit determination method, such as centralized solution on the ground, autonomous solution on the satellite, etc. Determine the satellite position, velocity, clock error, etc. that need to be estimated, and set the prior constraints of these parameters. Then use the observation data and the dynamic model to construct the normal equation of the epoch. Superimpose the normal equations of multiple epochs to form a large linear equation system. Finally, the least squares batch processing method is used to solve the superimposed linear equation system to obtain the optimal estimate of the parameter to be estimated.

[0047] S1025: Use the dynamic parameter information to perform orbital integration on navigation satellites and low-orbit satellites to obtain orbital and observation value residuals.

[0048] This embodiment inputs known dynamic parameter information into the orbital integration model. The satellite's motion equation is integrated using a numerical integration method to obtain the satellite's orbital sequence. The orbital integration result is compared with the actual observation data to calculate the observation value residual.

[0049] S1026: Perform observation value residual test. After the post-test residual is less than the preset residual threshold, double difference ambiguity fixation is performed to obtain an ambiguity fixation mark, and parameter estimation of the additional ambiguity fixation mark is performed again.

[0050] This embodiment tests the calculated observation value residual to determine whether it meets the preset residual threshold requirement.

[0051] It should be noted that double-difference ambiguity fixing uses double-difference observations between signals from two different satellites received by two different observation stations to fix the ambiguity.

[0052] Among them, double difference observations can be calculated. The LAMBDA algorithm is used to search and fix the ambiguity of the double difference observations. The ambiguity fixation mark is obtained. After the ambiguity fixation mark is obtained, it is used as an additional constraint condition to re-estimate the parameters. The information required for navigation can be obtained more comprehensively, thereby improving the accuracy of navigation.

[0053] As another implementation of the present application, when constructing a low-orbit satellite navigation processing system, this embodiment establishes a data communication link between a ground monitoring station, a low-orbit satellite, and a ground sensor. The ground monitoring station is responsible for continuously observing the low-orbit satellite and collecting observation data including pseudorange and carrier phase. At the same time, the GNSS receiver carried by the low-orbit satellite also continuously receives signals from medium- and high-orbit navigation satellites to provide data support for subsequent orbit determination.

[0054] This embodiment may also be configured with a data processing center, which receives and integrates all observation data. The data processing center uses a high-performance computer cluster to ensure the real-time and accuracy of data processing.

[0055] After completing data preprocessing, this embodiment enters the orbit determination solution phase, and accurately determines the orbit of the low-orbit satellite based on the dynamic model and numerical integration method.

[0056] In the selection of numerical integration methods, this embodiment adopts a high-precision and high-efficiency integration algorithm to ensure the accuracy and real-time performance of orbit determination. By combining observation data and dynamic models, the orbit of low-orbit satellites can be accurately determined to meet the needs of real-time navigation.

[0057] In terms of clock error determination, this embodiment uses real-time observation data and a Kalman filter method to calculate the clock error of a low-orbit satellite under the constraints of the satellite orbit. This method can effectively improve the accuracy and stability of clock error determination and provide an accurate time reference for subsequent navigation information encoding and broadcasting.

[0058] After completing the orbit determination and clock error determination, the present embodiment enters the encoding phase of the navigation information. The orbit determination results, clock error information, and navigation parameters are encoded to form a standard navigation information format. The encoding process follows the preset format configuration specification to ensure the universality and compatibility of the navigation information.

[0059] After the encoding is completed, the navigation information will be uploaded to the low-orbit satellite through the ground data transmission station or intersatellite link. The information broadcast module carried by the low-orbit satellite is responsible for broadcasting the navigation information to the ground terminal in real time. During the broadcasting process, we use efficient modulation technology and error correction coding methods to ensure the transmission efficiency and reliability of navigation information.

[0060] The ground terminal of this embodiment, as the final user end of the navigation system, can receive navigation signals from low-orbit satellites and GNSS satellites. During the reception process, the ground terminal first tracks and demodulates the navigation signal to extract navigation information. Then, the navigation signal is solved using methods such as the least squares method or Kalman filtering to achieve positioning and time synchronization of the ground terminal.

[0061] In this way, the method can not only improve the accuracy and real-time performance of the navigation system, but also expand the coverage and application scenarios of the navigation system.

[0062] In this embodiment, the following implementation steps may be adopted when solving the orbit determination.

[0063] Collect observation data of low-orbit satellites by ground monitoring stations, observation data of inter-satellite links between low-orbit satellites, and observation data of medium- and high-orbit navigation satellites.

[0064] Establish a dynamic model. The dynamic model can accurately describe the motion state of low-orbit satellites in space.

[0065] Combining observation data and dynamic models, the numerical integration method is used to accurately determine the orbit of low-orbit satellites. Through iterative calculations, the satellite orbit parameters are continuously optimized until the preset accuracy requirements are met.

[0066] Based on the precise orbit determination results, the orbit of the low-orbit satellite is predicted in the short term. The prediction results can meet the real-time navigation needs and provide continuous and stable navigation services for ground terminals.

[0067] During the implementation of the low-orbit satellite navigation system, this embodiment broadcasts navigation information in real time and ensures accurate reception by ground terminals.

[0068] Specifically, the encoding of navigation information can ensure accurate transmission of information. After orbit determination and clock error determination are completed, the resulting navigation information needs to be configured and encoded according to a preset format. The orbit parameters, clock error data and other related navigation information obtained by the calculation are converted into a standardized data format for subsequent transmission and processing.

[0069] The encoded navigation information is uploaded to the low-orbit satellite through the ground data transmission station or intersatellite link. The ground data transmission station, as the communication hub between the ground and the satellite, can upload the navigation information to the satellite in real time. The intersatellite link realizes direct communication between satellites, so that the navigation information can be efficiently transmitted within the satellite network. During the upload process, it is necessary to ensure the real-time and accuracy of the information to meet the real-time update requirements of the navigation system.

[0070] The low-orbit satellite of this embodiment broadcasts navigation information to the ground terminal in real time through the information broadcast module. The ground terminal is the end user device of the navigation system. After receiving the navigation signal from the low-orbit satellite and the GNSS satellite, the ground terminal needs to track and demodulate the signal to extract the navigation information.

[0071] In terms of solving the navigation signal, the ground terminal can use the least square method or Kalman filtering method to solve the received navigation signal to improve the accuracy and stability of the solution. Through the navigation information obtained by the solution, the ground terminal can achieve accurate positioning and time synchronization functions to meet the needs of various application scenarios. In this way, it is ensured that the navigation information can be accurately transmitted and processed between the low-orbit satellite and the ground terminal.

[0072] On the basis of the above embodiments, in order to further improve the reliability of the low-orbit satellite-based navigation processing method provided in the above embodiments, as an implementable method, in one embodiment, the navigation processing method process may be optimized.

[0073] Specifically, in the optimization and implementation of low-orbit satellite navigation, the navigation of low-orbit satellites is constructed to ensure global signal coverage and improve positioning accuracy and convergence speed.

[0074] This embodiment can define the navigation configuration of the low-orbit satellite. The low-orbit satellite can consider the number of orbital planes, the number of satellites in each orbital plane, and the phase configuration between satellites, so as to meet the basic requirements of positioning solution.

[0075] This embodiment optimizes the parameters of low-orbit satellites. Specifically, it adjusts the orbital altitude and orbital inclination to find the best balance between signal coverage and positioning performance. The choice of orbital altitude directly affects the coverage and signal strength of the satellite, while the orbital inclination is related to the visibility of the satellite in different latitudes.

[0076] In the optimization process, a genetic algorithm is used to find the point that achieves the best balance between positioning performance, coverage multiplicity and construction cost. By setting a reasonable fitness function and constraints, it can be ensured that the optimization results meet the performance requirements.

[0077] This embodiment also constructs a correlation model between the equivalent geometric precision factor of the low-orbit satellite constellation and the probability of successful convergence of precise single-point positioning. The constellation configuration is adjusted according to the expected positioning performance and convergence speed. Through continuous iteration and optimization, a navigation processing method based on low-orbit satellites that has both global coverage and high-precision positioning services is finally obtained.

[0078] Specifically, the orbital parameters can be defined first. The number of orbital planes can be determined based on the coverage requirements and the number of satellites. Ensure that the number of satellites in each orbital plane is sufficient to provide continuous signal coverage. The relative positions of low-orbit satellites can be determined by calculating the optimal phase factor to optimize inter-satellite links and signal coverage.

[0079] Define the objective function and establish a multi-objective optimization model. Set constraints based on the actual limitations of satellite launch, operation and maintenance, including the number of satellites, orbit parameter range, etc.

[0080] The global search capability of genetic algorithms is used to find the optimal solution in the parameter space. The constellation parameters are gradually optimized through operations such as selection, crossover and mutation.

[0081] Finally, satellite toolkits such as STK can be used for simulation verification to evaluate the performance of the optimized low-orbit satellite parameters in actual operation.

[0082] For the genetic algorithm of this embodiment, the quality of low-orbit satellite individuals can be evaluated. Among them, the fitness function can be defined as the weighted sum of positioning performance, coverage multiplicity and construction cost. According to the fitness function value, excellent individuals are selected for inheritance. Part of the genes of two individuals are exchanged to generate new individuals. The genes of individuals are randomly changed with a certain probability to increase the diversity of the population.

[0083] The orbit calculation of low-orbit satellites can first calculate the period and speed of the satellite in a specific orbit. Evaluate the coverage area of ​​the satellite at different orbital altitudes. Analyze the visibility of the satellite to users at different orbital inclinations. Realize the construction and optimization of low-orbit satellite constellations.

[0084] Combined with the above optimization methods, in the optimization process of low-orbit satellites, the use of genetic algorithms can efficiently search in complex parameter spaces to find the global optimal solution or approximate optimal solution.

[0085] When implementing the genetic algorithm, a fitness function is defined. By setting the fitness function, the optimization result can be ensured. Then the population of the genetic algorithm is initialized, that is, a set of candidate low-orbit satellite configuration schemes. Each scheme contains key parameters such as orbital height and orbital inclination, which will be continuously adjusted during the optimization process.

[0086] In the main loop of the genetic algorithm, operations such as selection, crossover and mutation are performed to simulate the natural selection and genetic process. Through continuous iteration and optimization, the low-orbit satellite configuration method that maximizes the fitness function is gradually found. According to the optimization results of the genetic algorithm, the final low-orbit satellite configuration method is determined. The low-orbit satellite configuration method defines the parameters of each satellite's orbital height, orbital inclination, and phase configuration.

[0087] The following is an embodiment of a low-orbit satellite-based navigation processing system provided in an embodiment of the present disclosure. This system and the low-orbit satellite-based navigation processing methods of the above-mentioned embodiments belong to the same inventive concept. For details not fully described in the embodiment of the low-orbit satellite-based navigation processing system, please refer to the above-mentioned embodiment of the low-orbit satellite-based navigation processing method.

[0088] like Figure 3 As shown, the data observation component obtains observation data based on ground monitoring stations, GNSS receivers carried by low-orbit satellites, and ground sensors; Information processing components, used to perform orbit determination and determine clock errors to form navigation information; The coded navigation processing component is used to encode the navigation information and upload the navigation information to the low-orbit satellite through the ground data transmission station or inter-satellite link; the low-orbit satellite broadcasts the navigation information to the ground terminal in real time through the information broadcasting module.

[0089] The ground terminal is used to receive navigation signals from low-orbit satellites and GNSS satellites, track and demodulate the navigation signals, and extract navigation information.

[0090] The ground terminal of this embodiment may be a mobile terminal (MT), a mobile station (MS), a mobile unit (MU), a wireless unit, a remote unit, a user agent, a mobile client, etc. For example, the ground terminal may be a mobile phone, a smart screen device, a tablet computer, a wearable device, a digital camera, a vehicle-mounted device, an augmented reality (AR) device, a virtual reality (VR) device, a notebook computer, an ultra-mobile personal computer (UMPC), a netbook, a personal digital assistant (PDA), a laptop computer, etc., and this embodiment of the application does not limit this.

[0091] The ground terminal may include a processor, and the processor may include one or more processing units, such as a processor including a central processing unit (CPU), an application processor (AP), a modem processor, a graphics processor (GPU), an image signal processor (ISP), a controller, a memory, a video codec, a digital signal processor (DSP), a baseband processor, and / or a neural-network processing unit (NPU), etc. Different processing units may be independent devices or integrated into one or more processors.

[0092] The processor can be the nerve center and command center of the ground terminal. The processor can generate operation control signals according to instruction operation codes and timing signals to complete the control of fetching and executing instructions.

[0093] A memory may also be provided in the processor for storing instructions and data. In some embodiments, the memory in the processor is a cache memory. The memory may store instructions or data that the processor has just used or is cyclically used. If the processor needs to use the instruction or data again, it may be directly called from the memory. This avoids repeated access, reduces the waiting time of the processor, and thus improves system efficiency.

[0094] The ground terminal may also include an external memory interface, which may be used to connect an external memory card, such as a MicroSD card, to expand the storage capacity of the ground terminal. The external memory card communicates with the processor via the external memory interface 120 to implement a data storage function.

[0095] The internal memory of the ground terminal can be used to store computer executable program codes, which include instructions. The processor executes various functional applications and data processing of the ground terminal by running the instructions stored in the internal memory. The internal memory may include a program storage area and a data storage area. Among them, the program storage area can store an operating system, an application required for at least one function, etc. The data storage area can store data (such as audio data, phone book, etc.) created by the ground terminal during use. In addition, the internal memory may include a high-speed random access memory, and may also include a non-volatile memory, such as at least one disk storage device, a flash memory device, a universal flash storage (UFS), etc.

[0096] The wireless communication function of the ground terminal can be realized through an antenna, a mobile communication module, a wireless communication module, a modem processor, and a baseband processor.

[0097] The wireless communication module can provide wireless communication solutions applied to ground terminals, including wireless local area networks (WLAN) (such as wireless fidelity (Wi-Fi) networks), Bluetooth (BT), global navigation satellite system (GNSS), frequency modulation (FM), near field communication technology (NFC), infrared technology (IR), etc.

[0098] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A navigation processing method based on a low-orbit satellite, characterized in that: Methods include: S101: Obtain observation data based on ground monitoring stations, GNSS receivers on low-orbit satellites, and ground sensors; S102: Execute orbit determination and clock error determination to form navigation information; S103: Encode the navigation information and upload the navigation information to the low-orbit satellite through a ground data transmission station or an inter-satellite link; the low-orbit satellite broadcasts the navigation information to the ground terminal in real time through an information broadcast module; wherein the navigation information format is configured according to a preset format; S104: The ground terminal receives navigation signals from low-orbit satellites and GNSS satellites, tracks and demodulates the navigation signals, and extracts navigation information.

2. The low-orbit satellite-based navigation processing method according to claim 1, characterized in that: In step S101, the observation data includes observation data of low-orbit satellites by ground monitoring stations, observation data of inter-satellite links between low-orbit satellites, and observation data of medium- and high-orbit navigation satellites.

3. The low-orbit satellite-based navigation processing method according to claim 1, characterized in that: Step S102 also includes: S1021: Processing the observation data by detecting cycle slips and eliminating gross errors; S1022: Obtaining the position sequence and clock error of the navigation satellite and the low-orbit satellite based on the navigation satellite broadcast ephemeris; S1023: Perform orbit integration based on the dynamic parameters of the navigation satellite and the low-orbit satellite, and obtain the initial orbit and state transfer matrix; S1024: Configure the joint orbit determination mode, set additional prior constraints on the parameters to be estimated, and use the least squares batch processing method to superimpose the normal equations of the epochs to solve the parameters to be estimated; S1025: perform orbit integration on navigation satellites and low-orbit satellites using dynamic parameter information to obtain orbit and observation value residuals; S1026: Perform observation value residual test. After the post-test residual is less than the preset residual threshold, double difference ambiguity fixation is performed to obtain an ambiguity fixation mark, and parameter estimation of the additional ambiguity fixation mark is performed again.

4. The low-orbit satellite-based navigation processing method according to claim 3, characterized in that: In step S1021, the Mw combination method is used to perform cycle slip detection on the ground monitoring station, the GNSS receiver carried by the low-orbit satellite, and the ground sensor to obtain a cycle slip detection result; Then the GF combination method is used to perform secondary cycle slip detection on the cycle slip detection results to obtain the secondary cycle slip detection results.

5. The low-orbit satellite-based navigation processing method according to claim 1 or 3, characterized in that: In step S101, a data communication link is established between a ground monitoring station, a low-orbit satellite, and a ground sensor; The ground monitoring station is used to continuously observe low-orbit satellites and collect observation data including pseudorange and carrier phase; GNSS receivers continuously receive signals from medium and high orbit navigation satellites; A data processing center is also configured to receive and integrate all observation data.

6. The low-orbit satellite-based navigation processing method according to claim 1 or 3, characterized in that: Step S102 also includes: determining the orbital parameters of the low-orbit satellite based on a dynamic model and a numerical integration method; The orbit determination solution uses numerical integration method, combined with observation data and dynamic model, to carry out precise orbit determination solution for low-orbit satellites; Based on the precise orbit determination results, the orbit of the low-orbit satellite is predicted in the short term to meet real-time navigation needs.

7. The low-orbit satellite-based navigation processing method according to claim 1 or 3, characterized in that: In the method, after orbit determination and clock error determination are completed, the encoding stage of navigation information is entered; Encode orbit determination results, clock error information and navigation parameters to form a standard navigation information format; After the encoding is completed, the navigation information will be uploaded to the low-orbit satellite through the ground data transmission station or inter-satellite link; the information broadcasting module carried by the low-orbit satellite is used to broadcast the navigation information to the ground terminal in real time.

8. The low-orbit satellite-based navigation processing method according to claim 1 or 3, characterized in that: Step S104 also includes: the ground terminal tracks and demodulates the navigation signal, extracts navigation information, and uses a least square method or Kalman filter to solve the navigation signal to achieve positioning and time synchronization of the ground terminal.

9. The low-orbit satellite-based navigation processing method according to claim 1 or 3, characterized in that: The method also includes: determining the number of orbital planes according to coverage requirements and the number of satellites; Define the number of low-orbit satellites in each orbital plane to ensure the number of low-orbit satellites in each orbital plane; Determine the relative position of low-orbit satellites in the constellation by calculating the best phase factor to optimize inter-satellite links and signal coverage; Define coverage area and orbit inclination; Establish a navigation optimization model for multi-target low-orbit satellites; Set constraints on the number of satellites and orbital parameter ranges; Use the global search capability of genetic algorithms to find the optimal solution in the parameter space; The particle swarm algorithm is used to optimize the navigation optimization model of multi-target low-orbit satellites; the navigation optimization model of multi-target low-orbit satellites is adjusted.

10. A navigation processing system based on a low-orbit satellite, characterized in that: The system is used to implement the low-orbit satellite-based navigation processing method as described in any one of claims 1 to 9; Data observation component, which obtains observation data based on ground monitoring stations, GNSS receivers carried by low-orbit satellites, and ground sensors; Information processing components, used to perform orbit determination and determine clock errors to form navigation information; The coded navigation processing component is used to encode the navigation information and upload the navigation information to the low-orbit satellite through the ground data transmission station or the inter-satellite link; The low-orbit satellite broadcasts navigation information to the ground terminal in real time through the information broadcast module; The ground terminal is used to receive navigation signals from low-orbit satellites and GNSS satellites, track and demodulate the navigation signals, and extract navigation information.

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