Low-orbit fixed dilution of precision-based compass PPP-B2b positioning method and device

Abstract

The application discloses a kind of based on low orbit fixed enhancement Beidou PPP-B2b positioning method and device, belong to GNSS positioning technical field. Including: obtaining Beidou and low orbit satellite observation data;Decoding PPP-B2b enhancement signal, utilize its precise correction number to correct satellite orbit and clock error;Based on the data after modification constructs Beidou / low orbit fusion's precise point positioning model;In model solution, using low orbit ambiguity priority fixing strategy, utilize the advantage that low orbit satellite geometry changes fast, first its carrier phase integer ambiguity is fixed as integer;Fixed low orbit ambiguity is regarded as known constraint back substitution to fusion model, re-solution obtains receiver precise positioning result.The application effectively overcomes the problem that traditional PPP-B2b signal is easy to shield, and convergence time is long, significantly improves the continuity of positioning, convergence speed and accuracy.

Description

Technical Field

[0001] This invention relates to a method and device for enhancing BeiDou PPP-B2b positioning based on low-orbit fixed solution, belonging to the field of GNSS positioning technology. Background Technology

[0002] Global Navigation Satellite Systems (GNSS) are one of the core technologies for modern surveying, navigation, and high-precision positioning. With the full completion and operation of the BeiDou-3 system, BeiDou Precise Point Positioning (PPP) technology has been widely applied in many fields. BeiDou PPP-B2b service broadcasts precise orbit and clock correction information in real time via geostationary orbit (GEO) satellites, enabling users to achieve real-time high-precision positioning globally without the need for a terrestrial network. However, because GEO satellites are fixed above the equator, their signals are easily blocked in mid-to-high latitude regions, especially in complex environments such as urban canyons, mountains, and forests. Enhancement signals are easily obstructed by buildings or terrain, leading to a reduction in the number of satellites that PPP-B2b can process, data discontinuity, or interruption of enhancement information.

[0003] Furthermore, BeiDou PPP-B2b positioning still suffers from the inherent problem of "long convergence time" at the algorithm level. Because PPP technology relies on ambiguity floating-point estimation and high-precision orbital clock correction, its positioning solution typically requires a considerable amount of time (tens of minutes) to achieve centimeter-level accuracy. In dynamic or emergency scenarios, such as power line inspection, geological disaster monitoring, emergency communication, and unmanned system navigation, higher demands are placed on rapid convergence and highly reliable real-time positioning. Current BeiDou PPP-B2b solutions based on GEO broadcasting often struggle to guarantee consistently high accuracy and rapid response capabilities in these scenarios.

[0004] To address the aforementioned issues, the introduction of LEO satellites (low-Earth orbit satellites) provides a new technical approach to improving the performance of BeiDou PPP-B2b. LEO satellites operate at high speeds, have wide trajectory coverage, and their signal propagation paths change rapidly, enabling them to provide abundant geometric information in a short time, thereby effectively improving the observability and parameter decoupling characteristics of the PPP model. Simultaneously, the LEO constellation significantly increases the number of available satellites and improves the quality of spatial geometric distribution, maintaining the continuity and accuracy stability of the solution even when BeiDou PPP-B2b signals are blocked or interrupted.

[0005] However, existing research mainly focuses on the generation and application of BeiDou PPP-B2b precision products, while research on the joint positioning mechanism of LEO and PPP-B2b enhancement signals remains relatively insufficient. Especially during the PPP convergence phase, how to utilize the geometric enhancement characteristics brought about by the rapid movement of LEO to constrain or fix the BeiDou PPP-B2b floating-point ambiguity, thereby achieving rapid and high-precision positioning, remains a key issue facing current BeiDou precision positioning technology. Summary of the Invention

[0006] The purpose of this invention is to provide a positioning method and device based on low-orbit fixed solution enhancement of BeiDou PPP-B2b. By simulating and generating low-orbit multi-frequency ranging signals, decoding BeiDou PPP-B2b enhancement information in real time, constructing a precise single-point positioning model that integrates low-orbit and BeiDou, and using low-orbit ambiguity priority fixation to achieve rapid and precise positioning.

[0007] To achieve the above objectives / to solve the above technical problems, the present invention is implemented using the following technical solution.

[0008] In a first aspect, the present invention provides a method for enhancing BeiDou PPP-B2b positioning based on low-orbit fixed solution, comprising the following steps:

[0009] Acquire multi-source data including observations from BeiDou satellites and low-orbit satellites;

[0010] Decode the BeiDou PPP-B2b enhanced signal to obtain the precise correction number corresponding to the broadcast ephemeris, and perform orbit correction and clock error correction on the BeiDou satellite observation value and the low-orbit satellite observation value based on the precise correction number;

[0011] Based on the corrected BeiDou satellite observations and low-orbit satellite observations, a precise point positioning model integrating low-orbit and BeiDou is constructed.

[0012] Based on the precise single-point positioning model, a low-orbit ambiguity priority fixing strategy is adopted for parameter calculation; the integer ambiguity corresponding to the low-orbit satellite observation value is fixed as an integer first.

[0013] The fixed integer ambiguity of the low-orbit satellite is used as a known constraint and substituted into the precise single-point positioning model to solve for the precise positioning result of the receiver.

[0014] Furthermore, the low-Earth orbit satellite observations include simulated multi-frequency pseudorange and carrier phase.

[0015] The low-orbit satellite observations are generated based on the following non-differenced observation equation, expressed as follows:

[0016] ;

[0017] in, s , r These are the satellite number and the receiver number, respectively. For frequency number; Let i be the pseudorange generated between the r-th receiver and the s-th satellite at frequency i. Generate carrier phase observations for the r-th receiver and the s-th satellite at frequency i; Let be the geometric distance between the phase center of the s-th satellite antenna and the phase center of the r-th receiver antenna; be the speed of light in vacuum; , These are the clock bias of the r-th receiver and the clock bias of the s-th satellite, respectively. The tropospheric delay of the signal along the propagation path between the r-th receiver and the s-th satellite; Let the frequency of the signal be on the propagation path between the r-th receiver and the s-th satellite. Ionospheric delay; For frequency The carrier wavelength; Let be the integer ambiguity between the r-th receiver and the s-th satellite; For the r-th receiver frequency The pseudorange hardware delay; For the s-th satellite frequency The pseudorange hardware delay; For the r-th receiver frequency Phase hardware delay; For the s-th satellite frequency Phase hardware delay; The pseudorange observation noise generated for the r-th receiver and the s-th satellite, The carrier observation noise generated for the r-th receiver and the s-th satellite.

[0018] Furthermore, the decoding of the BeiDou PPP-B2b enhanced signal yields precise correction values ​​corresponding to the broadcast ephemeris. Based on these precise correction values, orbital and clock errors are corrected for the BeiDou satellite observations and low-Earth orbit satellite observations. Specifically, this includes:

[0019] Track correction, expressed as:

[0020] ;

[0021] in: These are the satellite positions and velocities calculated from the broadcast ephemeris; This refers to the orbital correction vector for BeiDou PPP-B2b. For the corrected precise satellite position, This refers to the position correction amount for the BeiDou PPP-B2b satellite after coordinate system transformation. This is the transformation matrix for transforming from the radial tangent method to the RAC coordinate system and then to the ECEF coordinate system. The radial unit transformation vector, The tangential unit transformation vector, For normal unit transformation vector, These are the correction components in the radial, tangential, and normal directions;

[0022] Clock bias correction, expressed as:

[0023] ;

[0024] in, Satellite clock bias calculated for broadcast ephemeris; Clock correction values ​​provided for BeiDou PPP-B2b augmentation information; It is the speed of light in a vacuum. This is the corrected satellite clock bias.

[0025] Furthermore, the construction of the precise point positioning model integrating low-orbit and BeiDou navigation systems specifically involves:

[0026] A dual-frequency, ionosphere-free combined observation equation is constructed, and an inter-system bias parameter is introduced to absorb the hardware delay differences between the BeiDou satellite system and the low-Earth orbit satellite system. The expression is as follows:

[0027] ;

[0028] in: , They represent the BeiDou satellite system and the low-Earth orbit satellite system, respectively. The pseudorange of the dual-frequency, ionosphere-free combination of the r-th receiver and the s-th satellite in the BeiDou satellite system. This represents the carrier phase observation value of the dual-frequency, ionosphere-free combination of the r-th receiver and the s-th satellite in the BeiDou satellite system. For the pseudorange of the dual-frequency, ionosphere-free combination of the r-th receiver and the s-th satellite in a low-Earth orbit satellite system. The carrier phase observations are from the dual-frequency, ionosphere-free combination of the r-th receiver and the s-th satellite in a low-Earth orbit satellite system. Let be the geometric distance between the r-th receiver and the s-th satellite in the BeiDou satellite system. Let be the geometric distance between the r-th receiver and the s-th satellite in the low-Earth orbit satellite system. It is the speed of light in a vacuum. The receiver clock bias after reparameterization. To reparameterize satellite clock bias in the BeiDou satellite system, To reparameterize satellite clock bias for low-Earth orbit satellite systems, The tropospheric delay is the inclined path delay between the r-th receiver and the s-th satellite in the BeiDou satellite system. Let r be the tropospheric delay along the inclined path between the r-th receiver and the s-th satellite in a low-Earth orbit satellite system. The discrepancy between the BeiDou satellite system and the low-orbit satellite system; It is a dual-frequency non-ionizing combined carrier wavelength; The ambiguity after reparameterization of the dual-frequency non-ionization combination of the r-th receiver and the s-th satellite in the BeiDou satellite system. Let be the ambiguity after reparameterization of the dual-frequency non-ionization combination of the r-th receiver and the s-th satellite in a low-Earth orbit satellite system. For the pseudorange of the r-th receiver and the s-th satellite in the BeiDou satellite system without ionosphere, For the pseudorange of the r-th receiver and the s-th satellite in a low-Earth orbit satellite system without ionosphere, The noise of the carrier phase observation between the r-th receiver and the s-th satellite in the BeiDou satellite system. The noise is the carrier phase observation value between the r-th receiver and the s-th satellite in the low-Earth orbit satellite system.

[0029] Furthermore, the parameter calculation based on the precise single-point positioning model employs a low-orbit ambiguity priority fixing strategy, prioritizing the integer fixing of the carrier phase ambiguity of low-orbit satellites; specifically including:

[0030] The precise single-point positioning model is used for joint solution calculation, and the ambiguity parameters are estimated using floating-point methods.

[0031] By constructing a wide-lane and Melbourne–Wübbena integrable combination, and combining it with the phase deviation correction number broadcast by Beidou PPP-B2b, the hardware delay and frequency-related deviation between systems are eliminated, making the ambiguity parameters after floating-point estimation closer to integers.

[0032] The least squares algorithm is used to solve the integer ambiguity of the carrier phase in low-orbit satellite observations to achieve fixed integer ambiguity of the carrier phase. The reliability of the solution is verified by combining ratio test and residual consistency test.

[0033] Furthermore, the receiver's precise positioning results include:

[0034] ;

[0035] in: For the receiver's precise positioning results, For the receiver's three-dimensional coordinates, The receiver clock bias after reparameterization. To account for the discrepancy between the BeiDou satellite system and the low-Earth orbit satellite system, The tropospheric delay is the inclined path delay between the r-th receiver and the s-th satellite. The ambiguity after reparameterization of the dual-frequency non-ionization combination of the r-th receiver and the s-th satellite in the BeiDou satellite system. Let be the ambiguity after reparameterization of the dual-frequency non-ionization combination of the r-th receiver and the s-th satellite in the low-Earth orbit satellite system.

[0036] Secondly, the present invention provides a BeiDou PPP-B2b rapid and precise positioning device based on low-orbit fixed solution enhancement, comprising:

[0037] The acquisition module is used to acquire multi-source data including BeiDou satellite observations and low-orbit satellite observations;

[0038] The correction module is used to decode the BeiDou PPP-B2b enhanced signal, obtain the precise correction number corresponding to the broadcast ephemeris, and perform orbit correction and clock error correction on the BeiDou satellite observation value and the low-orbit satellite observation value based on the precise correction number;

[0039] The module is used to build a precise point positioning model that integrates low-orbit and BeiDou satellite observations based on the corrected BeiDou satellite observations and low-orbit satellite observations.

[0040] The fixing module is used to perform parameter calculation based on the precise single-point positioning model using a low-orbit ambiguity priority fixing strategy; the integer ambiguity corresponding to the low-orbit satellite observation value is preferentially fixed as an integer.

[0041] The solution module is used to take the integer ambiguity corresponding to the fixed low-orbit satellite observations as known constraints, substitute it into the precise single-point positioning model, and solve it again to obtain the precise positioning result of the receiver.

[0042] Thirdly, the present invention provides a BeiDou PPP-B2b rapid and precise positioning system based on low-orbit fixed solution enhancement, comprising:

[0043] Memory, used to store computer programs / instructions;

[0044] A processor is used to execute the computer program / instructions to implement the steps of the above-described method for enhancing BeiDou PPP-B2b positioning based on low-orbit fixed solution.

[0045] Fourthly, the present invention provides a computer-readable storage medium having a computer program / instruction stored thereon, which, when executed by a processor, implements the steps of the low-orbit fixed solution-enhanced BeiDou PPP-B2b positioning method described in the first aspect.

[0046] Fifthly, the present invention provides a computer program product, including a computer program / instruction, which, when executed by a processor, implements the steps of the low-orbit fixed solution-enhanced BeiDou PPP-B2b positioning method described in the first aspect.

[0047] Compared with existing technologies, the beneficial effects achieved by this invention are as follows: This invention utilizes the characteristics of low-Earth orbit (LEO) satellites—high orbit speed and rich observation geometry—to introduce multi-frequency observations from LEO satellites on the basis of BeiDou PPP-B2b augmentation information. It constructs a precise single-point positioning model integrating LEO and BeiDou, and employs a LEO ambiguity-priority fixing strategy to achieve rapid integerization and high-precision solution of PPP ambiguities. Compared with existing BeiDou PPP-B2b methods that rely solely on GEO satellites to broadcast augmentation signals, this invention effectively overcomes the positioning interruption problem caused by signal blockage, significantly shortens convergence time, improves positioning accuracy and ambiguity fixing rate, and exhibits stronger continuity, stability, and real-time performance in complex environments. Attached Figure Description

[0048] Figure 1 This is a flowchart illustrating the BeiDou PPP-B2b positioning method based on low-orbit fixed solution enhancement provided in an embodiment of the present invention.

[0049] Figure 2 This is a schematic diagram comparing the positioning results of traditional PPP-B2b positioning and the positioning method of the present invention provided in the embodiments of the present invention. Detailed Implementation

[0050] It should be noted that PPP-B2b is an enhanced signal service broadcast by the BeiDou-3 system to China and surrounding areas via geostationary orbit satellites to achieve real-time precise point positioning.

[0051] The technical solution of the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the embodiments of the present invention and the specific features in the embodiments are detailed descriptions of the technical solution of the present invention, rather than limitations thereof. In the absence of conflict, the embodiments of the present invention and the technical features in the embodiments can be combined with each other.

[0052] The term "and / or" simply describes the relationship between related objects. There are three possible relationships: for example, A and / or B can be: A alone, both A and B, or B alone. Additionally, the character " / " generally indicates that the objects before and after it are in an "or" relationship.

[0053] Example 1

[0054] like Figure 1 The embodiment shown provides a low-orbit fixed solution-enhanced BeiDou PPP-B2b positioning method, including the following steps:

[0055] Step S101: Data acquisition.

[0056] The user's receiver simultaneously receives two types of signals:

[0057] Actual BeiDou satellite observations: pseudorange and carrier phase observations received from BeiDou-3 system B1C, B2b and other frequency points.

[0058] Low Earth Orbit (LEO) satellite observations: The receiver acquires multi-frequency pseudorange and carrier phase observations broadcast by LEO satellites through the LEO satellite signal receiving link;

[0059] In the verification phase of this embodiment, the low-Earth orbit satellite observations include simulated multi-frequency pseudorange and carrier phase, generated through software simulation. The low-Earth orbit satellite observations are generated based on the following non-differenced observation equation, expressed as:

[0060] ;

[0061] in, s , r These are the satellite number and the receiver number, respectively. For frequency number; Let i be the pseudorange generated between the r-th receiver and the s-th satellite at frequency i. Generate carrier phase observations for the r-th receiver and the s-th satellite at frequency i; Let be the geometric distance between the phase center of the s-th satellite antenna and the phase center of the r-th receiver antenna; be the speed of light in vacuum; , These are the clock bias of the r-th receiver and the clock bias of the s-th satellite, respectively. The tropospheric delay of the signal along the propagation path between the r-th receiver and the s-th satellite; Let the frequency of the signal be on the propagation path between the r-th receiver and the s-th satellite. Ionospheric delay; For frequency The carrier wavelength; Let be the integer ambiguity between the r-th receiver and the s-th satellite; For the r-th receiver frequency The pseudorange hardware delay; For the s-th satellite frequency The pseudorange hardware delay; For the r-th receiver frequency Phase hardware delay; For the s-th satellite frequency Phase hardware delay; The pseudorange observation noise generated for the r-th receiver and the s-th satellite, The carrier observation noise generated for the r-th receiver and the s-th satellite.

[0062] Geometric distance The calculation requires correcting the satellite coordinates and station coordinates using the antenna phase center offset (PCO) and phase center variation (PCV) of the satellite and receiver. The PCO and PCV of the LEO augmentation satellite and the simulated ground station are not considered in this step and are set to zero.

[0063] Tropospheric delay This includes both dry and wet delays. The dry delay is calculated using the Saastamoinen model combined with the Global Mapping Function (GMF), while the wet delay is not considered in this step. Ionospheric delay. The first-order ionospheric delay along the propagation path was calculated using the Global Ionosphere Maps (GIM) file published by the International GNSS Service (IGS) through temporal and spatial interpolation.

[0064] Step S102: Precision error correction.

[0065] The receiver decodes the BeiDou PPP-B2b enhanced signal stream broadcast by the BeiDou GEO satellite in real time and extracts the orbit correction and clock correction values.

[0066] The orbit correction information broadcast by PPP-B2b is expressed in an orbital coordinate system, including correction components in three directions: radial (R), tangential (A), and normal (C). When the correction number decoded by the receiver matches the IODN (Issue of Data Number) identifier of the broadcast ephemeris, the satellite orbit can be corrected, as expressed by:

[0067] ;

[0068] in: These are the satellite positions and velocities calculated from the broadcast ephemeris; This refers to the orbital correction vector for BeiDou PPP-B2b. For the corrected precise satellite position, This refers to the position correction amount for the BeiDou PPP-B2b satellite after coordinate system transformation. This is the transformation matrix for transforming from the radial tangent method to the RAC coordinate system and then to the ECEF coordinate system. The radial unit transformation vector, The tangential unit transformation vector, For normal unit transformation vector, These are the correction components in the radial, tangential, and normal directions, respectively.

[0069] This embodiment utilizes correction numbers. The satellite position r and velocity calculated by combining broadcast ephemeris Through coordinate transformation matrix The position correction δX in the Earth-centered Earth-fixed coordinate system is calculated, and the precise orbital position of the BeiDou satellite is finally obtained. This precision orbit also serves as a unified positional reference for processing low-orbit observation data.

[0070] This correction method enables real-time conversion from broadcast orbit to precise orbit, significantly improving the instantaneous accuracy of satellite position calculation. It can typically reduce orbital errors from the order of meters to the order of decimeters or even centimeters, providing precise geometric constraints for subsequent PPP high-precision positioning.

[0071] PPP-B2b signal synchronization provides satellite clock bias corrections based on broadcast ephemeris. After decoding and obtaining the correction parameters, the receiver can correct the satellite clock bias using the following formula:

[0072] ;

[0073] in, Satellite clock bias calculated for broadcast ephemeris; Clock correction values ​​provided for BeiDou PPP-B2b augmentation information; It is the speed of light in a vacuum. This is the corrected satellite clock bias;

[0074] This embodiment utilizes clock correction numbers. Correcting broadcast ephemeris clock bias This allows us to obtain the precise clock bias of the BeiDou satellites, and this precise time reference is also used to unify the time reference for low-orbit satellites.

[0075] By synchronously recovering orbit and clock error correction information, satellite state parameters equivalent to International GNSS Service (IGS) precision products can be generated, providing a high-precision input basis for the LEO / BeiDou fusion PPP model; combined with constant deviation compensation and LEO ambiguity fixation in subsequent steps, second-level PPP-B2b high-precision positioning can be achieved.

[0076] Step S103: Construct a precise single-point positioning model that integrates low-orbit orbit and BeiDou.

[0077] The precisely corrected BeiDou and LEO observations are combined into a unified observation model. Specifically, a dual-frequency, ionosphere-free combined observation equation is constructed, and an inter-system bias parameter is introduced to absorb the hardware delay differences between the BeiDou satellite system and the LEO satellite system. The observation equation is as follows:

[0078] ;

[0079] in: , They represent the BeiDou satellite system and the low-Earth orbit satellite system, respectively. The pseudorange of the dual-frequency, ionosphere-free combination of the r-th receiver and the s-th satellite in the BeiDou satellite system. This represents the carrier phase observation value of the dual-frequency, ionosphere-free combination of the r-th receiver and the s-th satellite in the BeiDou satellite system. For the pseudorange of the dual-frequency, ionosphere-free combination of the r-th receiver and the s-th satellite in a low-Earth orbit satellite system. The carrier phase observations are from the dual-frequency, ionosphere-free combination of the r-th receiver and the s-th satellite in a low-Earth orbit satellite system. Let be the geometric distance between the r-th receiver and the s-th satellite in the BeiDou satellite system. Let be the geometric distance between the r-th receiver and the s-th satellite in the low-Earth orbit satellite system. It is the speed of light in a vacuum. The receiver clock bias after reparameterization. To reparameterize satellite clock bias in the BeiDou satellite system, To reparameterize satellite clock bias for low-Earth orbit satellite systems, The tropospheric delay is the inclined path delay between the r-th receiver and the s-th satellite in the BeiDou satellite system. Let r be the tropospheric delay along the inclined path between the r-th receiver and the s-th satellite in a low-Earth orbit satellite system. The discrepancy between the BeiDou satellite system and the low-orbit satellite system; It is a dual-frequency non-ionizing combined carrier wavelength; The ambiguity after reparameterization of the dual-frequency non-ionization combination of the r-th receiver and the s-th satellite in the BeiDou satellite system. Let be the ambiguity after reparameterization of the dual-frequency non-ionization combination of the r-th receiver and the s-th satellite in a low-Earth orbit satellite system. For the pseudorange of the r-th receiver and the s-th satellite in the BeiDou satellite system without ionosphere, For the pseudorange of the r-th receiver and the s-th satellite in a low-Earth orbit satellite system without ionosphere, The noise of the carrier phase observation between the r-th receiver and the s-th satellite in the BeiDou satellite system. The noise is the carrier phase observation value between the r-th receiver and the s-th satellite in the low-Earth orbit satellite system.

[0080] It is a newly introduced parameter to be estimated in the model, used to absorb the hardware delay difference between the two system signals at the receiver end. The model combines the observation equations of Beidou and LEO to solve the same set of receiver state parameters.

[0081] Step S104: Prioritize fixing the ambiguity of the lower orbit.

[0082] The carrier phase and pseudorange observations of the dual-frequency ionosphere-free combination were obtained by solving the aforementioned fused PPP model, and the ambiguity parameters were estimated by floating point.

[0083] For low-Earth orbit satellites, we construct integrable combinations such as wide lane and Melbourne–Wübbena, and combine them with the phase deviation correction number broadcast by BeiDou PPP-B2b to eliminate hardware delays and frequency-related deviations between systems, making the ambiguity parameters after floating-point estimation closer to integers.

[0084] The integer least squares method is adopted to prioritize integer search in the subset of ambiguities of low-Earth orbit satellites. Since the geometry of low-Earth orbit satellites changes rapidly, their floating-point ambiguity solutions have high accuracy and low correlation, making them easier to fix correctly. The integer ambiguities of low-Earth orbit satellites have been fixed as known integers.

[0085] Additionally, the significant difference between the optimal integer solution and the suboptimal solution can be verified through ratio tests and residual consistency tests, ensuring the reliability of the fixed solution.

[0086] Step S105: Fixed solution enhancement positioning.

[0087] The fixed low-Earth orbit (LEO) satellite ambiguities from step S104 are used as precise known constants and substituted into the precise point positioning (S103) model. Because the number of parameters to be estimated in the precise S103 model is reduced, the model strength is greatly enhanced. The filtering calculation is then re-run, and the estimation accuracy of parameters such as receiver coordinates (X, Y, Z), receiver clock error dt_r, tropospheric delay T, inter-system bias (ISB), and BeiDou satellite ambiguities will rapidly improve. The strong constraints provided by fixing the LEO ambiguities will accelerate the convergence and fixation of BeiDou satellite ambiguities, ultimately achieving joint fixation of ambiguities across the entire system (BeiDou + LEO).

[0088] The final high-precision, converged positioning result is output, mainly including the receiver's three-dimensional coordinates (X, Y, Z) in the geocentric coordinate system, with an accuracy of up to the centimeter level.

[0089] like Figure 2 The results shown demonstrate that:

[0090] Number of available satellites: During the observation period, when only the BeiDou (BDS) system is used, the number of visible satellites is relatively small, remaining at around 6-9 (blue curve in the figure); however, after the introduction of LEO satellites for enhancement, the total number of available satellites increases significantly, stabilizing between 24-28 (red curve in the figure).

[0091] Positioning error: In the three directions of east, north, and sky, the positioning error of the method of the present invention (red curve) can converge and stabilize at the centimeter level more quickly, while the traditional method (blue curve) converges slowly and has a larger error, which shows the improvement effect of the present invention in terms of positioning convergence speed and positioning accuracy.

[0092] Example 2

[0093] This embodiment provides a BeiDou PPP-B2b rapid and precise positioning device based on low-orbit fixed solution enhancement, including:

[0094] The acquisition module is used to acquire multi-source data including BeiDou satellite observations and low-orbit satellite observations;

[0095] The correction module is used to decode the BeiDou PPP-B2b enhanced signal, obtain the precise correction number corresponding to the broadcast ephemeris, and perform orbit correction and clock error correction on the BeiDou satellite observation value and the low-orbit satellite observation value based on the precise correction number;

[0096] The module is used to build a precise point positioning model that integrates low-orbit and BeiDou satellite observations based on the corrected BeiDou satellite observations and low-orbit satellite observations.

[0097] The fixed module is used to perform parameter calculation based on the precise single-point positioning model using a low-orbit ambiguity priority fixing strategy, prioritizing fixing the integer ambiguity corresponding to the low-orbit satellite observation value as an integer.

[0098] The solution module is used to take the integer ambiguity corresponding to the fixed low-orbit satellite observations as known constraints, substitute it into the precise single-point positioning model, and solve it again to obtain the precise positioning result of the receiver.

[0099] Example 3

[0100] This embodiment provides a BeiDou PPP-B2b rapid and precise positioning system based on low-orbit fixed solution enhancement, including:

[0101] Memory, used to store computer programs / instructions;

[0102] A processor for executing the computer program / instructions to implement the steps of the method in Embodiment 1.

[0103] Example 4

[0104] This embodiment provides a computer-readable storage medium storing a computer program / instructions thereon, characterized in that, when the computer program / instructions are executed by a processor, they implement the steps of the method in Embodiment 1.

[0105] Example 5

[0106] This embodiment provides a computer program product, including a computer program / instruction, characterized in that the computer program / instruction, when executed by a processor, implements the steps of the method in Embodiment 1.

[0107] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0108] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0109] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0110] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0111] The embodiments of the present invention have been described above with reference to the accompanying drawings. However, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of the present invention without departing from the spirit and scope of the claims. All of these forms are within the protection scope of the present invention.

Claims

1. A method for enhancing BeiDou PPP-B2b positioning based on low-orbit fixed solution, characterized in that, Includes the following steps: Acquire multi-source data including observations from BeiDou satellites and low-orbit satellites; Decode the BeiDou PPP-B2b enhanced signal to obtain the precise correction number corresponding to the broadcast ephemeris, and perform orbit correction and clock error correction on the BeiDou satellite observation value and the low-orbit satellite observation value based on the precise correction number; Based on the corrected BeiDou satellite observations and low-orbit satellite observations, a precise point positioning model integrating low-orbit and BeiDou is constructed. Based on the precise single-point positioning model, a low-orbit ambiguity priority fixing strategy is adopted for parameter calculation, prioritizing the fixing of integer ambiguities corresponding to low-orbit satellite observations as integers; specifically including: The precise single-point positioning model is used for joint solution calculation, and the ambiguity parameters are estimated using floating-point methods. For low-Earth orbit satellites, a wide-lane and Melbourne–Wübbena integralizable combination is constructed, and combined with the phase deviation correction number broadcast by BeiDou PPP-B2b, the hardware delay and frequency-related deviation between systems are eliminated, making the ambiguity parameters after floating-point estimation closer to integers. The carrier phase integer ambiguity of the low-Earth orbit satellite observations is solved by the least squares algorithm to fix the integer ambiguity of the carrier phase. The reliability of the solution is verified by combining the ratio test and the residual consistency test. The fixed integer ambiguity corresponding to the low-Earth orbit satellite observations is used as a known constraint and substituted into the precise single-point positioning model to solve again, so as to obtain the precise positioning result of the receiver.

2. The positioning method based on low-orbit fixed solution enhancement of BeiDou PPP-B2b according to claim 1, characterized in that, The low-orbit satellite observations are generated based on the following non-differenced observation equation, expressed as follows: ； Where s and r are the satellite number and receiver number, respectively. For frequency number; Let i be the pseudorange generated between the r-th receiver and the s-th satellite at frequency i. Generate carrier phase observations for the r-th receiver and the s-th satellite at frequency i; Let be the geometric distance between the phase center of the s-th satellite antenna and the phase center of the r-th receiver antenna; c is the speed of light in vacuum; , These are the clock bias of the r-th receiver and the clock bias of the s-th satellite, respectively. The tropospheric delay of the signal along the propagation path between the r-th receiver and the s-th satellite; Let the frequency of the signal be on the propagation path between the r-th receiver and the s-th satellite. Ionospheric delay; For frequency The carrier wavelength; Let be the integer ambiguity between the r-th receiver and the s-th satellite; For the r-th receiver frequency The pseudorange hardware delay; For the s-th satellite frequency The pseudorange hardware delay; For the r-th receiver frequency Phase hardware delay; For the s-th satellite frequency Phase hardware delay; The pseudorange observation noise generated for the r-th receiver and the s-th satellite, The carrier observation noise generated for the r-th receiver and the s-th satellite.

3. The positioning method based on low-orbit fixed solution enhancement of BeiDou PPP-B2b according to claim 1, characterized in that, The decoding of the BeiDou PPP-B2b enhanced signal yields precise correction values ​​corresponding to the broadcast ephemeris. Based on these precise correction values, orbital and clock errors are corrected for the BeiDou satellite observations and low-Earth orbit satellite observations. Specifically, this includes: Track correction, expressed as: ； in: These are the satellite positions and velocities calculated from the broadcast ephemeris; This refers to the orbital correction vector for BeiDou PPP-B2b. For the corrected precise satellite position, This refers to the position correction amount for the BeiDou PPP-B2b satellite after coordinate system transformation. This is the transformation matrix for transforming from the radial tangent method to the RAC coordinate system and then to the ECEF coordinate system. The radial unit transformation vector, For tangential unit transformation vector, For normal unit transformation vector, These are the correction components in the radial, tangential, and normal directions; Clock bias correction, expressed as: ； in, Satellite clock bias calculated for broadcast ephemeris; Clock correction values ​​provided for BeiDou PPP-B2b augmentation information; It is the speed of light in a vacuum. This is the corrected satellite clock bias.

4. The positioning method based on low-orbit fixed solution enhancement of BeiDou PPP-B2b according to claim 1, characterized in that, The construction of the precise point positioning model integrating low-orbit and BeiDou systems specifically involves: A dual-frequency, ionosphere-free combined observation equation is constructed, and an inter-system bias parameter is introduced to absorb the hardware delay differences between the BeiDou satellite system and the low-Earth orbit satellite system. The expression is as follows: ； in: , They represent the BeiDou satellite system and the low-Earth orbit satellite system, respectively. The pseudorange of the dual-frequency, ionosphere-free combination of the r-th receiver and the s-th satellite in the BeiDou satellite system. This represents the carrier phase observation value of the dual-frequency, ionosphere-free combination of the r-th receiver and the s-th satellite in the BeiDou satellite system. For the pseudorange of the dual-frequency, ionosphere-free combination of the r-th receiver and the s-th satellite in a low-Earth orbit satellite system. The carrier phase observations are from the dual-frequency, ionosphere-free combination of the r-th receiver and the s-th satellite in a low-Earth orbit satellite system. Let be the geometric distance between the r-th receiver and the s-th satellite in the BeiDou satellite system. Let be the geometric distance between the r-th receiver and the s-th satellite in the low-Earth orbit satellite system. It is the speed of light in a vacuum. The receiver clock bias after reparameterization. To reparameterize satellite clock bias in the BeiDou satellite system, To reparameterize satellite clock bias for low-Earth orbit satellite systems, The tropospheric delay is the inclined path delay between the r-th receiver and the s-th satellite in the BeiDou satellite system. Let r be the tropospheric delay along the inclined path between the r-th receiver and the s-th satellite in a low-Earth orbit satellite system. The discrepancy between the BeiDou satellite system and the low-orbit satellite system; It is a dual-frequency non-ionizing combined carrier wavelength; The ambiguity after reparameterization of the dual-frequency non-ionization combination of the r-th receiver and the s-th satellite in the BeiDou satellite system. Let be the ambiguity after reparameterization of the dual-frequency non-ionization combination of the r-th receiver and the s-th satellite in a low-Earth orbit satellite system. For the pseudorange of the r-th receiver and the s-th satellite in the BeiDou satellite system without ionosphere, For the pseudorange of the r-th receiver and the s-th satellite in a low-Earth orbit satellite system without ionosphere, The noise of the carrier phase observation between the r-th receiver and the s-th satellite in the BeiDou satellite system. The noise is the carrier phase observation value between the r-th receiver and the s-th satellite in the low-Earth orbit satellite system.

5. The positioning method based on low-orbit fixed solution enhancement of BeiDou PPP-B2b according to claim 1, characterized in that, The receiver's precise positioning results include: ； in: For the receiver's precise positioning results, For the receiver's three-dimensional coordinates, The receiver clock bias after reparameterization. To account for the discrepancy between the BeiDou satellite system and the low-Earth orbit satellite system, The tropospheric delay is the inclined path delay between the r-th receiver and the s-th satellite. The ambiguity after reparameterization of the dual-frequency non-ionization combination of the r-th receiver and the s-th satellite in the BeiDou satellite system. Let be the ambiguity after reparameterization of the dual-frequency non-ionization combination of the r-th receiver and the s-th satellite in the low-Earth orbit satellite system.

6. A rapid and precise positioning device for BeiDou PPP-B2b based on low-orbit fixed solution enhancement, characterized in that, include: The acquisition module is used to acquire multi-source data including BeiDou satellite observations and low-orbit satellite observations; The correction module is used to decode the BeiDou PPP-B2b enhanced signal, obtain the precise correction number corresponding to the broadcast ephemeris, and perform orbit correction and clock error correction on the BeiDou satellite observation value and the low-orbit satellite observation value based on the precise correction number; The module is used to build a precise point positioning model that integrates low-orbit and BeiDou satellite observations based on the corrected BeiDou satellite observations and low-orbit satellite observations. The fixing module is used to perform parameter calculation based on the precise single-point positioning model using a low-orbit ambiguity priority fixing strategy, prioritizing fixing the integer ambiguity corresponding to the low-orbit satellite observations as integers; specifically including: The precise single-point positioning model is used for joint solution calculation, and the ambiguity parameters are estimated using floating-point methods. For low-Earth orbit satellites, a wide-lane and Melbourne–Wübbena integralizable combination is constructed, and combined with the phase deviation correction number broadcast by BeiDou PPP-B2b, the hardware delay and frequency-related deviation between systems are eliminated, making the ambiguity parameters after floating-point estimation closer to integers. The carrier phase integer ambiguity of low-orbit satellite observations is solved by the least squares algorithm to fix the integer ambiguity of the carrier phase. The reliability of the solution is verified by combining ratio test and residual consistency test. The solution module is used to take the integer ambiguity corresponding to the fixed low-orbit satellite observations as known constraints, substitute it into the precise single-point positioning model, and solve it again to obtain the precise positioning result of the receiver.

7. A rapid and precise positioning system for BeiDou PPP-B2b based on low-orbit fixed solution enhancement, characterized in that, include: Memory, used to store computer programs / instructions; A processor is configured to execute the computer program / instructions to implement the steps of the low-orbit fixed solution-enhanced BeiDou PPP-B2b positioning method as described in any one of claims 1-5.

8. A computer-readable storage medium having a computer program / instructions stored thereon, characterized in that, When the computer program / instruction is executed by the processor, it implements the steps of the BeiDou PPP-B2b positioning method based on low-orbit fixed solution enhancement as described in any one of claims 1-5.

9. A computer program product comprising a computer program / instructions, characterized in that, When the computer program / instruction is executed by the processor, it implements the steps of the BeiDou PPP-B2b positioning method based on low-orbit fixed solution enhancement as described in any one of claims 1-5.

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