Positioning method based on single low-orbit communication satellite

Abstract

The invention provides a positioning method based on a single low-orbit communication satellite, and relates to the technical field of low-orbit satellite positioning, and the method comprises the steps: S1, obtaining the pseudo-range measurement values of low-orbit communication satellites at different moments; s2, carrying out the difference of the pseudo-range measurement values at adjacent moments, and obtaining a measurement residual error; s3, establishing a corresponding ground satellite terminal position solving equation set according to the measurement residual error, and solving to obtain a terminal position and a satellite geometric distribution factor; and S4, repeating the steps S1-S3, after each repeating, selecting a better satellite geometric distribution factor, determining a corresponding terminal position, judging whether random switching is carried out or not, and if random switching is carried out, accessing a new low-orbit communication satellite until convergence is carried out, thereby obtaining a converged terminal position. With the adoption of the scheme, the positioning precision of the single low-orbit satellite is improved.

Description

Technical Field

[0001] The present application relates to the field of low-orbit satellite positioning technology, and in particular to a method and system based on positioning of a single low-orbit communication satellite. Background Art

[0002] With the increasing demand for applications such as emergency services, the Internet of Things, and autonomous driving, it is becoming increasingly important to obtain spatial information to achieve communication and navigation. The location services provided by traditional cellular networks and global positioning systems (GNSS) cannot overcome the influence of factors such as weak signal power, susceptibility to interference, multipath, and non-line-of-sight, especially in densely populated urban areas, indoor places, forest canyons, and other scenes. Low-orbit satellites have the characteristics of low orbit, small road loss, and anti-interference, and have broad application prospects in communication and navigation and positioning services. Relying on resources such as satellite-to-ground links, satellite payloads, and ground terminals established by low-orbit communication satellites to achieve positioning solutions is one of the important technical means to realize the future 6G. Considering the power consumption, size, signal design, and single-channel transceiver limitations of most current satellite communication terminals, the positioning method based on a single low-orbit communication satellite is more compatible with the current satellite communication network, while providing navigation and positioning services.

[0003] At present, ground satellite communication terminals use signals broadcast by a single satellite to perform positioning, mainly using the azimuth angle information measured by the terminal and satellite antenna or using observations such as distance and Doppler to estimate the position. Due to the limitation of the terminal channel, antenna measurement usually requires measurement through multiple antenna units and receiving channels, so this positioning method is difficult to achieve. Positioning using the Doppler frequency shift between low-orbit satellites and ground satellite terminals also faces the problem of slow convergence speed. Summary of the invention

[0004] The present application aims to solve one of the technical problems in the related art at least to some extent.

[0005] To this end, the first purpose of this application is to propose a positioning method based on a single low-orbit communication satellite, so that the satellite communication terminal can overcome the limitation of the number of channels. During the connection with the low-orbit satellite, it can not only communicate, but also realize its own position solution. At the same time, the two-way link provided by the low-orbit communication satellite can be used to realize real-time information interaction, eliminate some errors in the satellite-to-ground link transmission, improve the convergence speed, and improve the positioning accuracy.

[0006] The second objective of this application is to propose a system based on positioning of a single low-orbit communication satellite.

[0007] To achieve the above-mentioned purpose, the first aspect embodiment of the present application proposes a method for positioning based on a single low-orbit communication satellite, including: step S1: obtaining pseudo-range measurement values ​​of low-orbit communication satellites at different times; step S2: differentiating the pseudo-range measurement values ​​at adjacent times to obtain measurement residuals; step S3: establishing a corresponding ground satellite terminal position solution equation group based on the measurement residuals, and solving the terminal position and the satellite geometric distribution factor; step S4: repeating steps S1-S3, and after each repetition, selecting a better satellite geometric distribution factor, determining the corresponding terminal position, and determining whether to perform random switching. If random switching is performed, access a new low-orbit communication satellite until convergence to obtain a converged terminal position.

[0008] Optionally, in one embodiment of the present application, obtaining low-orbit communication satellite pseudorange measurement values ​​at different times includes:

[0009] The two-way satellite-to-ground link provided by low-orbit communication satellite is used to achieve one-way two-way ranging.

[0010] Optionally, in one embodiment of the present application, obtaining low-orbit communication satellite pseudorange measurement values ​​at different times includes:

[0011] exist The position request command is initiated at any time by the low-orbit communication satellite. Always receive;

[0012] exist At this moment, the low-orbit communication satellite is received via T p The processing time is delayed. The telegrams carrying satellite position information are sent at all times;

[0013] The pseudorange measurement value in the above process is expressed as:

[0014]

[0015] Among them, δt UE and δt LEO are the clock differences between ground satellite terminals, low-orbit communication satellites and the world standard time, and c is the speed of light.

[0016] Optionally, in one embodiment of the present application, set is the pseudo-range measurement value at the k+1th moment, is the pseudorange measurement value at the kth moment, and the measurement residuals at the adjacent k+1th moment and kth moment are:

[0017]

[0018] The method further includes:

[0019] Obtain the measurement residuals at least three times to achieve self-position analysis.

[0020] Optionally, in one embodiment of the present application, the terminal position is:

[0021]

[0022] The satellite geometry distribution factor is:

[0023]

[0024] Among them, H LEO To measure the linear representation of the residual matrix for the ground satellite terminal position, is the pseudo-range measurement vector of the i-th low-orbit communication satellite obtained at the second moment, and They are the transformation matrix from the Earth-centered Earth-fixed coordinate system to the navigation coordinate system and the transformation matrix from the world geodetic coordinate system to the Earth-centered Earth-fixed coordinate system, and trace is the trace of the matrix.

[0025] Optionally, in one embodiment of the present application, step S4 further includes:

[0026] After each repetition, it is determined whether to perform random switching. If random switching is performed, a new low-orbit communication satellite is connected.

[0027] To achieve the above-mentioned purpose, a second embodiment of the present invention proposes a system based on positioning of a single low-orbit communication satellite, including a low-orbit communication satellite and a ground satellite terminal, and the system implements the above-mentioned method based on positioning of a single low-orbit communication satellite.

[0028] In the method and system based on positioning of a single low-orbit communication satellite in the embodiment of the present application, the ground satellite terminal requests the position from the satellite through the two-way satellite-to-ground link provided by the low-orbit communication satellite, receives and processes the information returned by the satellite, realizes one-way two-way ranging, eliminates the satellite-to-ground clock error, and solves the influence of clock drift; the ground satellite terminal adopts the differential positioning technology of adjacent time measurement values, differentiates the two ranging values ​​at adjacent times, obtains the measurement residual, and realizes its own position analysis by obtaining the differential measurement residual at least three times, overcomes the atmospheric error in the satellite-to-ground transmission link, and improves the positioning accuracy; the ground satellite terminal will use the satellite geometric distribution factor as the ground satellite terminal position update indicator, continuously update the measurement residual position information, improve its own position accuracy, and solve the problem of geometric configuration difference caused by single-satellite positioning and continuous measurement. Finally, the ground satellite terminal can achieve the optimal positioning accuracy of up to 299.5 meters within 3 minutes.

[0029] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through the practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The above and / or additional aspects and advantages of the present application will become apparent and easily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which:

[0031] Figure 1 A flowchart of a method for positioning based on a single low-orbit communication satellite provided in Embodiment 1 of the present application;

[0032] Figure 2 A schematic diagram of updating residual information of ground satellite terminal measurement according to an embodiment of the present application;

[0033] Figure 3 This is an example diagram of a ground satellite terminal performing 15 random switching satellite trajectories according to an embodiment of the present application;

[0034] Figure 4 This is an example diagram of a ground satellite terminal performing 19 random switching satellite trajectories according to an embodiment of the present application;

[0035] Figure 5 This is an example diagram of the north-direction positioning error of the ground satellite terminal according to an embodiment of the present application;

[0036] Figure 6 This is an example diagram of the eastward positioning error of the ground satellite terminal according to an embodiment of the present application;

[0037] Figure 7 This is an example diagram of the anteroposterior positioning error of the ground satellite terminal according to an embodiment of the present application. DETAILED DESCRIPTION

[0038] Embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present application, and should not be construed as limiting the present application.

[0039] The following describes the method and system based on single low-orbit communication satellite positioning according to an embodiment of the present application with reference to the accompanying drawings.

[0040] Figure 1 A flowchart of a method for positioning based on a single low-orbit communication satellite provided in Example 1 of the present application is provided, and the method is applied to a ground satellite terminal.

[0041] like Figure 1 As shown, the method based on positioning of a single low-orbit communication satellite includes the following steps:

[0042] Step S1: obtaining pseudo-range measurement values ​​of low-orbit communication satellites at different times;

[0043] In this embodiment, the ground satellite terminal uses the two-way satellite-to-ground link provided by the low-orbit communication satellite to achieve one-way two-way ranging, which can eliminate the clock error between the satellite and the terminal. The low-orbit communication satellite initiates a position request command at any time. Receive at any time, via T p The processing time is delayed. The ground satellite terminal sends messages carrying satellite position information at all times. The reception at the same time is regarded as a complete one-way two-way ranging process. The pseudo-range observation in this process can be expressed as:

[0044]

[0045] Among them, δt UE and δt LEO are the clock differences between the ground satellite terminal, the low-orbit communication satellite and the world standard time, c is the speed of light, and the physical layer processing delay T p The pseudo-range measurement value of the ground satellite terminal and the LEO satellite is finally eliminated by the system compensation method, which is ρ.

[0046] Step S2: Differentiate the pseudo-range measurement values ​​at adjacent moments to obtain the measurement residual;

[0047] In this embodiment, the satellite-to-ground transmission link is symmetrical in two adjacent measurements at a short time interval, and the ground satellite terminal eliminates the signal atmospheric transmission error by differentially measuring adjacent moments, thereby further improving the positioning accuracy.

[0048] set up: is the pseudo-range measurement value at the k+1th moment, is the pseudorange measurement value at the kth moment, and the measurement residuals between the adjacent k+1th moment and the kth moment can be expressed as:

[0049]

[0050] Finally, the ground satellite terminal can achieve its own position analysis result by obtaining differential measurement residuals at least three times.

[0051] Step S3: establishing a corresponding ground satellite terminal position solution equation group according to the measurement residual, and solving the terminal position and the satellite geometric distribution factor;

[0052] In this embodiment, the satellite geometric distribution factor is calculated as follows:

[0053]

[0054]

[0055] Among them, H LEO To measure the linear representation of the residual matrix for the ground satellite terminal position, is the pseudo-range measurement vector of the first low-orbit communication satellite obtained by the terminal at the second moment; and They are respectively the transformation matrix from the earth-centered, earth-fixed (ECEF) coordinate system to the navigation coordinate system (north east down, NED) coordinate system and the transformation matrix from the world geodetic system (1984 coordinate system, WGS-84) coordinate system to the ECEF coordinate system, and trace is the trace of the matrix.

[0056] Step S4: Repeat steps S1-S3. After each repetition, select a more optimal satellite geometric distribution factor, determine the corresponding terminal position, and determine whether to perform random switching. If random switching is performed, access a new low-orbit communication satellite until convergence to obtain a converged terminal position.

[0057] In this embodiment, in order to compensate for the shortcomings of continuous measurement of geometric configuration differences of a single satellite, the ground satellite terminal updates the position information based on the satellite geometric distribution factor (PDOP). Specifically, the ground satellite terminal selects the satellite geometric distribution factor by comparison, selects the measurement residuals with good satellite geometric distribution to form a new terminal position solution equation group, and updates the position solution result.

[0058] Figure 2 This is a schematic diagram of updating the residual information measured by the ground satellite terminal in this embodiment.

[0059] In this embodiment, the ground satellite terminal chooses whether to randomly switch the low-orbit communication satellite. If the switch is performed, the new low-orbit communication satellite is connected to continue observation. By repeating the above steps S1-S3, a converged ground satellite terminal position analysis result is obtained.

[0060] In the method for positioning based on a single low-orbit communication satellite in the embodiment of the present application, the ground satellite terminal requests the position from the satellite through the two-way satellite-to-ground link provided by the low-orbit communication satellite, receives and processes the information returned by the satellite, realizes one-way two-way ranging, eliminates the satellite-to-ground clock error, and solves the influence of clock drift; the ground satellite terminal adopts the differential positioning technology of adjacent measurement values, differentiates the two ranging values ​​at adjacent moments, obtains the measurement residual, and realizes its own position analysis by obtaining the differential measurement residual at least three moments, overcomes the atmospheric error in the satellite-to-ground transmission link, and improves the positioning accuracy; the ground satellite terminal will use the satellite geometric distribution factor as the ground satellite terminal position update indicator, continuously update the measurement residual position information, improve its own position accuracy, and solve the problem of geometric configuration difference caused by single-satellite positioning and continuous measurement. Finally, the ground satellite terminal can achieve the optimal positioning accuracy of up to 299.5 meters within 3 minutes.

[0061] Taking a group of low-orbit communication satellite related parameters as shown in Table 1 as an example, the positioning accuracy of a method based on positioning of a single low-orbit communication satellite provided in this embodiment is analyzed:

[0062] Table 1. Parameters of low-orbit communication satellites

[0063]

[0064]

[0065] The ENU coordinate system is established with the ground satellite terminal as the origin. Based on the above settings, a simulation experiment is conducted to obtain Figure 3 , Figure 4 The satellite trajectories of the ground satellite terminal 15 times of random switching and the satellite trajectories of the ground satellite terminal 19 times of random switching are further obtained. Figure 5 , Figure 6 , Figure 7 The terminal positioning accuracy results are shown.

[0066] according to Figure 3-7 It can be seen that the positioning error of the ground satellite terminal random switching strategy decreases step by step over time and gradually converges. In particular, when the positioning solution is performed on a terminal based on a small amount of observation data and a small number of switching times, the terminal's accuracy is significantly improved, with a kilometer-level enhancement. At the same time, under the condition of the same switching frequency of the terminal, the longer the continuous observation time, the higher the positioning accuracy.

[0067] In order to implement the above embodiments, the present application also proposes a system based on positioning of a single low-orbit communication satellite, including a low-orbit communication satellite and a ground satellite terminal, and the system implements the method described in the above embodiments.

[0068] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example" or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0069] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of this application, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0070] Any process or method description in a flowchart or otherwise described herein may be understood to represent a module, fragment or portion of code comprising one or more executable instructions for implementing the steps of a custom logical function or process, and the scope of the preferred embodiments of the present application includes alternative implementations in which functions may not be performed in the order shown or discussed, including performing functions in a substantially simultaneous manner or in the reverse order depending on the functions involved, which should be understood by technicians in the technical field to which the embodiments of the present application belong.

[0071] The logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as an ordered list of executable instructions for implementing logical functions, and can be embodied in any computer-readable medium for use by an instruction execution system, device or apparatus (such as a computer-based system, a system including a processor, or other system that can fetch instructions from an instruction execution system, device or apparatus and execute the instructions), or in combination with these instruction execution systems, devices or apparatuses. For the purpose of this specification, "computer-readable medium" can be any device that can contain, store, communicate, propagate or transmit a program for use by an instruction execution system, device or apparatus, or in combination with these instruction execution systems, devices or apparatuses. More specific examples of computer-readable media (a non-exhaustive list) include the following: an electrical connection with one or more wires (electronic device), a portable computer disk box (magnetic device), a random access memory (RAM), a read-only memory (ROM), an erasable and programmable read-only memory (EPROM or flash memory), a fiber optic device, and a portable compact disk read-only memory (CDROM). In addition, the computer-readable medium may even be paper or other suitable medium on which the program is printed, since the program may be obtained electronically, for example, by optically scanning the paper or other medium and then editing, interpreting or processing in other suitable ways if necessary, and then stored in a computer memory.

[0072] It should be understood that the various parts of the present application can be implemented by hardware, software, firmware or a combination thereof. In the above-mentioned embodiments, multiple steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented by hardware, as in another embodiment, it can be implemented by any one of the following technologies known in the art or their combination: a discrete logic circuit having a logic gate circuit for implementing a logic function for a data signal, a dedicated integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0073] A person skilled in the art may understand that all or part of the steps in the method for implementing the above-mentioned embodiment may be completed by instructing related hardware through a program, and the program may be stored in a computer-readable storage medium, which, when executed, includes one or a combination of the steps of the method embodiment.

[0074] In addition, each functional unit in each embodiment of the present application may be integrated into a processing module, or each unit may exist physically separately, or two or more units may be integrated into one module. The above-mentioned integrated module may be implemented in the form of hardware or in the form of a software functional module. If the integrated module is implemented in the form of a software functional module and sold or used as an independent product, it may also be stored in a computer-readable storage medium.

[0075] The storage medium mentioned above may be a read-only memory, a magnetic disk or an optical disk, etc. Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limiting the present application. A person of ordinary skill in the art may change, modify, replace and modify the above embodiments within the scope of the present application.

Claims

1. A positioning method based on a single low-orbit communication satellite, characterized in that: The method is applied to a ground satellite terminal, and the method comprises: Step S1: obtaining pseudo-range measurement values ​​of low-orbit communication satellites at different times; Step S2: Differentiate the pseudo-range measurement values ​​at adjacent moments to obtain the measurement residual; Step S3: establishing a corresponding ground satellite terminal position solution equation group according to the measurement residual, and solving the terminal position and the satellite geometric distribution factor; Step S4: Repeat steps S1-S3. After each repetition, select a more optimal satellite geometric distribution factor, determine the corresponding terminal position, and determine whether to perform random switching. If random switching is performed, access a new low-orbit communication satellite until convergence to obtain a converged terminal position.

2. The method according to claim 1, characterized in that The step of obtaining pseudo-range measurement values ​​of low-orbit communication satellites at different times includes: The two-way satellite-to-ground link provided by low-orbit communication satellite is used to achieve one-way two-way ranging.

3. The method according to claim 1, characterized in that The step of obtaining pseudo-range measurement values ​​of low-orbit communication satellites at different times includes: exist The position request command is initiated at any time by the low-orbit communication satellite. Always receive; exist At this moment, the low-orbit communication satellite is received via T p The processing time is delayed. The telegrams carrying satellite position information are sent at all times; The pseudorange measurement value in the above process is expressed as: Among them, δt UE and δt LEO are the clock differences between ground satellite terminals, low-orbit communication satellites and the world standard time, and c is the speed of light.

4. The method according to claim 3, characterized in that set up is the pseudo-range measurement value at the k+1th moment, is the pseudorange measurement value at the kth moment, and the measurement residuals at the adjacent k+1th moment and kth moment are: The method further comprises: Obtain the measurement residuals at least three times to achieve self-position analysis.

5. The method according to claim 1, characterized in that The terminal positions are: The satellite geometry distribution factor is: Among them, H LEO To measure the linear representation of the residual matrix for the ground satellite terminal position, is the pseudo-range measurement vector of the i-th low-orbit communication satellite obtained at the second moment, and They are the transformation matrix from the Earth-centered Earth-fixed coordinate system to the navigation coordinate system and the transformation matrix from the world geodetic coordinate system to the Earth-centered Earth-fixed coordinate system, and trace is the trace of the matrix.

6. A system based on positioning of a single low-orbit communication satellite, characterized in that: The system comprises a low-orbit communication satellite and a ground satellite terminal, and implements the method as claimed in claims 1-5.

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