A PPP-RTK positioning method, system, and terminal for multi-ephemeris availability scenarios

Abstract

This invention belongs to the field of satellite navigation and positioning technology, and discloses a PPP-RTK positioning method, system, and terminal for multi-ephemeris availability scenarios. The method acquires multi-source ephemeris products and raw GNSS observation data; during positioning service operation, it determines the availability status of precise ephemeris and PPP-B2b products, and executes corresponding ephemeris scenario processing steps based on the determination results to generate a complete correction product set, a compatible correction product set, or a simplified correction product set based on broadcast ephemeris; when the ephemeris scenario changes, it switches processing steps and inherits the solution state; and it outputs the correction product set to the positioning terminal for calculation. This invention can improve the continuity of positioning services.

Description

Technical Field

[0001] This invention belongs to the field of satellite navigation and positioning technology, and relates to a PPP-RTK positioning method, system and terminal for multi-ephemeris availability scenarios. Background Technology

[0002] As mobile platforms (including but not limited to ground vehicles, drones, and surface platforms) continue to expand their applications in precision agriculture, low-altitude economy, smart ports, and intelligent transportation, higher demands are being placed on high-precision positioning capabilities. These application scenarios generally require positioning services to be real-time, continuous, and with centimeter-level accuracy to support safe and efficient operations. Currently, high-precision positioning mainly relies on traditional Real-Time Kinematic (RTK) technology, Precise Point Positioning (PPP) technology, Network Real-Time Kinematic (NRTK) technology, and Precise Point Positioning-Real-Time Kinematic (PPP-RTK) technology. Traditional RTK technology typically requires the deployment of base stations within the target area, and its positioning accuracy rapidly decreases with increasing baseline distance, making it difficult to meet the continuous high-precision positioning requirements of large-scale mobile platforms. While PPP technology does not rely on regional base stations, it suffers from long convergence times and poor real-time performance, making it difficult to meet the mobile platforms' requirements for fast and highly reliable positioning. NRTK technology improves the coverage of RTK to some extent by constructing regional error correction models, but it still has problems such as high requirements for base station deployment density, easy spatiotemporal reference jumps caused by master station switching, limitations on user capacity due to two-way communication mechanisms, and data privacy risks.

[0003] In summary, existing PPP-RTK methods typically rely on a single ephemeris product or design separate processing flows for each ephemeris source. During positioning service operation, when ephemeris products such as precise ephemeris and BeiDou-3 Precise Point Positioning B2b (PPP-B2b) signal service products experience delays, interruptions, or unavailability, the product benchmarks, error modeling methods, and parameter estimation processing methods differ across ephemeris sources. Existing methods struggle to continuously switch between different ephemeris scenarios and maintain the continuity of the solution state. Furthermore, when both precise ephemeris and PPP-B2b products are unavailable, existing methods also struggle to generate a set of correction products based on broadcast ephemeris for the positioning terminal to continue solving, easily leading to positioning service interruptions, re-initialization, or decreased positioning continuity. Therefore, how to generate corresponding correction product sets based on the availability of multi-source ephemeris products during positioning service operation and maintain continuous positioning solution when ephemeris scenarios change is a pressing technical problem that needs to be solved. Summary of the Invention

[0004] The purpose of this invention is to solve the technical problem that existing PPP-RTK positioning services are unable to continuously generate a set of correction products adapted to the current ephemeris scenario due to changes in the availability of ephemeris products during operation, and are unable to maintain the continuity of positioning calculation when switching ephemeris scenarios. The invention provides a PPP-RTK positioning method, system and terminal for multi-ephemeris availability scenarios.

[0005] To achieve the above objectives, the present invention employs the following technical solution: In a first aspect, the present invention provides a PPP-RTK positioning method for multi-ephemeris availability scenarios, comprising the following steps: Acquire multi-source ephemeris products and raw GNSS observation data, wherein the multi-source ephemeris products include precise ephemeris, PPP-B2b products and broadcast ephemeris; During the operation of the location service, the availability status of the precise ephemeris and the PPP-B2b product is determined; Based on the discrimination result, the corresponding ephemeris scene processing steps are executed to generate a corresponding correction product set; wherein, the correction product set is one of a complete correction product set, a compatible correction product set, and a simplified correction product set; when the precise ephemeris is available, the complete correction product set is generated; when the precise ephemeris is unavailable but the PPP-B2b product is available, the compatible correction product set compatible with the complete correction product set is generated; when both the precise ephemeris and the PPP-B2b product are unavailable, the simplified correction product set without independent satellite orbit correction is generated based on the broadcast ephemeris; When the ephemeris scene changes, the corresponding ephemeris scene processing step is switched according to the discrimination result, and the solution state of the ephemeris scene before the switch is inherited. The generated calibration product set is output to the positioning terminal so that the positioning terminal can perform positioning calculations based on the calibration product set.

[0006] Furthermore, the availability status of the precise ephemeris and the PPP-B2b product is determined, including: The precise ephemeris and the PPP-B2b product are respectively used as ephemeris products to be judged, and the timeliness, continuity and integrity of the ephemeris products to be judged are judged. The timeliness determination includes: obtaining the product reception time and nominal time of the ephemeris product to be determined, calculating the time difference between the product reception time and the nominal time, and determining whether the ephemeris product to be determined meets the timeliness requirements based on the comparison result of the time difference and the preset timeliness threshold. The continuity determination includes: calculating at least one of the epoch missing rate, continuous interruption duration, and number of interruptions of the ephemeris product to be determined within a preset epoch window to obtain a continuity statistical result; comparing the continuity statistical result with the corresponding preset missing rate threshold, preset interruption duration threshold, or preset interruption number threshold; and determining that the ephemeris product to be determined meets the continuity requirement when the continuity statistical result meets the corresponding threshold requirement. The integrity determination includes: determining whether the ephemeris product to be determined meets the integrity requirements based on whether the product message of the currently received ephemeris product to be determined passes the verification, whether the necessary correction fields are complete, and whether the number of available satellites meets the preset minimum calculation requirements; When the ephemeris product to be identified meets the timeliness requirement, the continuity requirement, and the integrity requirement, the ephemeris product to be identified is determined to be usable.

[0007] Furthermore, the ephemeris scene processing steps are performed based on the PPP-RTK basic observation model; The PPP-RTK basic observation model is constructed through the following steps: Construct non-differential, non-combined GNSS observation equations based on the raw GNSS observation data; The parameters to be estimated in the non-differential non-combined GNSS observation equations are uniformly modeled and reorganized, and ionospheric constraint information is introduced to obtain the PPP-RTK basic observation model.

[0008] Furthermore, when the precise ephemeris is unavailable and the PPP-B2b product is available, a compatible calibration product set compatible with the complete calibration product set is generated, including: The product benchmark used in the PPP-B2b product is incorporated into the PPP-RTK basic observation model; Using the satellite orbit information, satellite clock bias information, and code offset information provided by the PPP-B2b product, the pseudorange observations and carrier phase observations in the raw GNSS observation data are corrected to obtain corrected observations in the PPP-B2b scenario; wherein, the parameters that have been provided by the PPP-B2b product and used for observation correction are no longer used as parameters to be estimated in subsequent calculations. The remaining parameters to be estimated in subsequent calculations are equivalently reorganized; Based on the corrected observations in the PPP-B2b scenario and the remaining parameters to be estimated after equivalent recombination, PPP-RTK calculation is performed to generate the compatible correction product set.

[0009] Furthermore, when the precise ephemeris is available, a complete set of calibration products is generated, including: The precise satellite-to-ground distance is calculated based on the precise ephemeris, and the precise satellite-to-ground distance is subtracted from the pseudorange observations and carrier phase observations in the original GNSS observation data to obtain the corrected observations under the precise ephemeris scenario. Based on the orbital difference between the precise satellite orbit provided by the precise ephemeris and the satellite orbit of the broadcast ephemeris at the corresponding time, the satellite orbit correction amount is determined, and satellite orbit correction data is generated based on the satellite orbit correction amount. Based on the corrected observations under the aforementioned precise ephemeris scenario, PPP-RTK calculations are performed to generate satellite clock error correction data, satellite code deviation correction data, satellite phase deviation correction data, ionospheric delay correction data, and tropospheric delay correction data. The complete set of correction products is formed based on the satellite orbit correction data, the satellite clock error correction data, the satellite code deviation correction data, the satellite phase deviation correction data, the ionospheric delay correction data, and the tropospheric delay correction data.

[0010] Furthermore, when both the precise ephemeris and the PPP-B2b product are unavailable, a simplified correction product set without independent satellite orbit correction is generated, including: The approximate satellite-to-ground distance is calculated based on the broadcast ephemeris, and the approximate satellite-to-ground distance is subtracted from the pseudorange observations and carrier phase observations in the original GNSS observation data to obtain the corrected observations under the broadcast ephemeris scenario. The orbital errors caused by insufficient accuracy of broadcast ephemeris orbits are incorporated into the satellite clock error parameters for unified modeling and estimation; Simplified PPP-RTK solution is performed based on the corrected observations under the broadcast ephemeris scenario to generate the simplified correction product set; The simplified correction product set includes satellite clock bias correction data, satellite code bias correction data, satellite phase bias correction data, ionospheric delay correction data, and tropospheric delay correction data.

[0011] Furthermore, the solution state includes the state parameters and their covariance information in the PPP-RTK solution; When the ephemeris scene changes, the solution state of the ephemeris scene before the switch is inherited, including: Inherit the state parameters and covariance information corresponding to the ephemeris scene before the switch; Based on the ephemeris scene processing steps switched to, the inherited state parameters and their covariance information are updated so that the positioning solution can continue on the basis of the existing solution state.

[0012] Furthermore, the positioning terminal performs positioning calculations based on the calibration product set, including: Parse the received calibration product set and identify the calibration data type and validity status contained in the calibration product set; Based on the completeness and validity of the calibration product set, select the corresponding positioning mode from PPP-RTK, PPP-AR, PPP and SPP positioning modes; When the data type or valid status of the received calibration product set changes, the current calibration information status is updated, and the positioning calculation is performed based on the selected positioning mode without re-initializing the positioning calculation process.

[0013] Secondly, the present invention provides a PPP-RTK positioning system for multi-ephemeris availability scenarios, comprising: The data acquisition unit is used to acquire multi-source ephemeris products and raw GNSS observation data. The multi-source ephemeris products include precise ephemeris, PPP-B2b products, and broadcast ephemeris. The ephemeris discrimination unit is used to determine the availability status of the precise ephemeris and the PPP-B2b product during the operation of the positioning service; The ephemeris scene processing unit is used to execute corresponding ephemeris scene processing steps based on the discrimination result and generate a corresponding correction product set; wherein, the correction product set is one of a complete correction product set, a compatible correction product set, and a simplified correction product set; when the precise ephemeris is available, the complete correction product set is generated; when the precise ephemeris is unavailable but the PPP-B2b product is available, the compatible correction product set compatible with the complete correction product set is generated; when both the precise ephemeris and the PPP-B2b product are unavailable, the simplified correction product set without independent satellite orbit correction is generated based on the broadcast ephemeris; The strategy switching unit is used to switch to the corresponding ephemeris processing step according to the discrimination result when the ephemeris scene changes, and inherit the solution state of the ephemeris scene before the switch. A calibration product output unit is used to output the generated calibration product set to the positioning terminal, so that the positioning terminal performs positioning calculation based on the calibration product set.

[0014] Thirdly, the present invention provides a PPP-RTK positioning terminal for multi-ephemeral availability scenarios, comprising: A communication module is used to receive a set of calibration products, which includes a complete set of calibration products generated based on a precise ephemeris, a compatible set of calibration products generated based on a PPP-B2b product, or a simplified set of calibration products generated based on a broadcast ephemeris without independent satellite orbit corrections. The data sensing module is used to parse the calibration product set and identify the calibration data types and valid statuses contained in the calibration product set. The core processing module is used to select the corresponding positioning mode from PPP-RTK, PPP-AR, PPP and SPP positioning modes according to the completeness and validity status of the calibration product set, and perform positioning calculation based on the selected positioning mode; When the set of calibration products changes, the core processing module updates the current calibration information status and performs the positioning calculation without re-initializing the positioning calculation process.

[0015] Compared with the prior art, the present invention has the following beneficial effects: The first aspect of this invention provides a PPP-RTK positioning method for multi-ephemeris availability scenarios. During the operation of the positioning service, the availability status of precise ephemeris and PPP-B2b products is determined, and corresponding ephemeris scenario processing steps are executed based on the determination results. Thus, a complete calibration product set is generated when precise ephemeris is available; a compatible calibration product set is generated when precise ephemeris is unavailable but PPP-B2b products are available; and a simplified calibration product set is generated based on broadcast ephemeris when both precise ephemeris and PPP-B2b products are unavailable, reducing the positioning service's dependence on a single ephemeris product. Furthermore, when the ephemeris scenario changes, this invention switches to the corresponding ephemeris scenario processing steps based on the determination results and inherits the solution state of the ephemeris scenario before the switch, allowing subsequent positioning solutions to continue based on the existing solution state. Therefore, this invention can continuously generate calibration product sets adapted to the current ephemeris scenario even when ephemeris products are delayed, interrupted, or unavailable, reducing the risk of positioning service interruption or re-initialization and improving the continuity and stability of the PPP-RTK positioning service under multi-ephemeris availability change conditions.

[0016] The second aspect of this invention provides a PPP-RTK positioning system for multi-ephemeris availability scenarios. This system acquires multi-source ephemeris products and raw GNSS observation data through a data acquisition unit. During positioning service operation, an ephemeris discrimination unit determines the availability status of precise ephemeris and PPP-B2b products. An ephemeris scene processing unit generates a complete, compatible, or simplified correction product set based on the discrimination results. A strategy switching unit switches the corresponding ephemeris scene processing steps and inherits the solution state when the ephemeris scene changes. These units cooperate to continuously generate correction product sets and inherit solution states, enabling the system to adjust processing strategies according to the real-time availability of ephemeris products, avoiding direct interruption of positioning services due to precise ephemeris anomalies. The generated correction product set is output to the positioning terminal through a correction product output unit. This invention provides the positioning terminal with correction information matching the current ephemeris scene, improving the availability, continuity, and operational stability of the PPP-RTK positioning service at the system level.

[0017] The third aspect of this invention provides a PPP-RTK positioning terminal for multi-ephemeris availability scenarios. This terminal receives a complete calibration product set, a compatible calibration product set, or a simplified calibration product set via a communication module. A data sensing module parses the calibration product set and identifies the calibration data types and valid states. A core processing module then selects a positioning mode based on the completeness and valid state of the calibration product set: PPP-RTK, PPP-AR (Precise Point Positioning Ambiguity Resolution), PPP, or SPP (Standard Point Positioning). Thus, the positioning terminal can adaptively select the corresponding positioning solution method based on different calibration product sets output by the service system, rather than relying on a fixed calibration product form. Furthermore, when the calibration product set changes, the core processing module updates the current calibration information state and performs positioning calculations without re-initializing the positioning calculation process. This allows the terminal to accept the ephemeris scene switching results from the service system, maintaining continuous output of positioning results and improving the adaptability and positioning continuity of the positioning terminal under changing calibration product set conditions. Attached Figure Description

[0018] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of the present invention and should not be considered as a limitation on the scope of protection. For those skilled in the art, other related drawings can be obtained based on these drawings without any creative effort.

[0019] Figure 1 This is a flowchart illustrating a PPP-RTK positioning method for multi-ephemeris availability scenarios provided in an embodiment of the present invention. Figure 2 This is a schematic diagram of the structure of a PPP-RTK positioning system for multi-ephemeris availability scenarios provided in an embodiment of the present invention; Figure 3 This is a schematic diagram of the structure of a PPP-RTK positioning terminal for multi-ephemeris availability scenarios provided in an embodiment of the present invention; Figure 4 This is a diagram showing the distribution of wide-area reference stations and the vehicle-mounted test area in an embodiment of the present invention; Figure 5 This is an error diagram of the actual vehicle-mounted test of the positioning terminal in this embodiment of the invention. Detailed Implementation

[0020] The present invention will be further described in detail below with reference to specific embodiments. It should be understood that the following embodiments are used to illustrate the technical solutions of the present invention, and not to limit the scope of protection of the present invention. Other implementation methods obtained by those skilled in the art based on the embodiments of the present invention without creative effort should all fall within the scope of protection of the present invention.

[0021] During the operation of PPP-RTK positioning services, the server typically needs to generate a set of correction products for the positioning terminal based on ephemeris products and raw GNSS observation data. If the ephemeris products are stable and available, the positioning terminal can perform positioning calculations based on continuously obtained correction product sets. However, in actual operation, precise ephemeris may fail to meet the current positioning calculation requirements due to data delays, transmission interruptions, product anomalies, or missing necessary fields. Although PPP-B2b products can serve as another source of ephemeris products, their product reference, correction information content, and parameter estimation processing methods are not entirely the same as those in precise ephemeris scenarios. When both precise ephemeris and PPP-B2b products are unavailable, the system also needs to consider how to utilize broadcast ephemeris to maintain the basic continuous operation of the positioning service.

[0022] Based on the above, if the positioning service relies on only a single ephemeris product, or uses independent processing procedures for different ephemeris sources, problems such as discontinuous generation of calibration product sets, inability to continue the solution state, and the need for re-initialization of the positioning terminal may easily occur when the availability status of the ephemeris product changes. To address this, this invention provides a PPP-RTK positioning method, system, and terminal for multi-ephemeris availability scenarios. During the operation of the positioning service, the availability status of precise ephemeris and PPP-B2b products is determined, and corresponding ephemeris scene processing steps are executed according to the determination result to generate a complete calibration product set, a compatible calibration product set, or a simplified calibration product set. When the ephemeris scene changes, the solution state of the ephemeris scene before the switch is inherited, allowing the positioning solution to continue based on the existing solution state.

[0023] In this embodiment of the invention, the precise ephemeris can be an external real-time precise ephemeris product, the PPP-B2b product can be a PPP-B2b correction product broadcast by the BeiDou system, and the broadcast ephemeris can be a conventional broadcast ephemeris broadcast by GNSS satellites. The raw GNSS observation data can include pseudorange observations and carrier phase observations from GNSS satellites, and may further include Doppler observations, signal-to-noise ratio observations, or other auxiliary observation information according to actual calculation requirements. It should be noted that the descriptions of precise ephemeris, PPP-B2b products, and broadcast ephemeris in this embodiment are only for describing the processing methods under different ephemeris sources and their varying availability, and do not limit the invention to specific ephemeris product formats or specific satellite systems.

[0024] Example 1 Figure 1 This is a flowchart illustrating a PPP-RTK positioning method for multi-ephemeris availability scenarios provided by an embodiment of the present invention. Figure 1 As shown, this method can be executed by a PPP-RTK positioning system, which may include a server-side processing unit and a positioning terminal processing unit. The server-side processing unit is used to acquire multi-source ephemeris products and raw GNSS observation data, determine the availability status of precise ephemeris and PPP-B2b products, and generate a corresponding correction product set based on the determination results. The positioning terminal processing unit is used to receive the correction product set and select the corresponding positioning mode to perform positioning calculation based on the completeness and validity status of the correction product set.

[0025] In this embodiment, the PPP-RTK positioning method for multi-ephemeris availability scenarios includes the following steps: S1, acquire multi-source ephemeris products and raw GNSS observation data.

[0026] The multi-source ephemeris products include precise ephemeris, PPP-B2b products, and broadcast ephemeris. The raw GNSS observation data includes pseudorange observations and carrier phase observations. As one implementation method, the raw GNSS observation data can be acquired from a base station, reference station network, or positioning terminal, or received from an external data interface. By simultaneously acquiring multi-source ephemeris products and raw GNSS observation data, a data foundation can be provided for subsequent PPP-RTK solution and correction product set generation under different ephemeris scenarios.

[0027] S2, during the operation of the positioning service, determine the availability status of the precise ephemeris and the PPP-B2b product.

[0028] Specifically, during the operation of the PPP-RTK positioning service, the system can determine the availability status of precise ephemeris and PPP-B2b products according to preset time intervals, positioning epochs, or product update cycles. The availability status can be determined based on the timeliness, continuity, and completeness of the ephemeris products. Through this determination process, the preferred ephemeris scenario for the current positioning service operation can be identified: the precise ephemeris scenario, the PPP-B2b scenario, or the broadcast ephemeris scenario.

[0029] S3, based on the discrimination result, execute the corresponding ephemeris scene processing steps to generate the corresponding correction product set.

[0030] Specifically, the calibration product set is one of a complete calibration product set, a compatible calibration product set, or a simplified calibration product set. When precise ephemeris is determined to be available, the PPP-RTK positioning system performs precise ephemeris scene processing steps to generate the complete calibration product set. When precise ephemeris is determined to be unavailable but PPP-B2b products are available, the PPP-RTK positioning system performs PPP-B2b scene processing steps to generate the compatible calibration product set, which is compatible with the complete calibration product set. When both precise ephemeris and PPP-B2b products are determined to be unavailable, the PPP-RTK positioning system performs broadcast ephemeris scene processing steps and generates the simplified calibration product set without independent satellite orbit correction based on the broadcast ephemeris.

[0031] In this embodiment, the PPP-RTK positioning service is not directly terminated when precise ephemeris is unavailable. Instead, the corresponding ephemeris scene processing steps are selected based on the currently available ephemeris products, so that the system can generate a set of calibration products for use by the positioning terminal under different ephemeris product availability conditions.

[0032] S4. When the ephemeris scene changes, switch to the corresponding ephemeris scene processing step according to the judgment result, and inherit the solution state of the ephemeris scene before the switch.

[0033] During the operation of the positioning service, the availability status of precise ephemeris, PPP-B2b products, and broadcast ephemeris may change over time. For example, if the precise ephemeris meets the availability requirements at the current epoch, the system uses the precise ephemeris scene processing steps. In subsequent operation, if the precise ephemeris experiences a delay or interruption, but the PPP-B2b product still meets the availability requirements, the system can switch to the PPP-B2b scene processing steps. During the switch, the system inherits the solution state of the ephemeris scene before the switch and continues subsequent calculations based on the inherited solution state, avoiding the need to reinitialize the positioning solution process due to changes in the ephemeris scene.

[0034] S5, the generated calibration product set is output to the positioning terminal so that the positioning terminal performs positioning calculation based on the calibration product set.

[0035] Specifically, after receiving the calibration product set, the positioning terminal can parse the calibration data types and validity states contained in the calibration product set, and select the corresponding positioning mode based on the completeness and validity states of the calibration product set. Thus, the positioning terminal can perform positioning calculations based on the calibration product set generated under the current ephemeris scenario.

[0036] This embodiment continuously determines the availability status of precise ephemeris and PPP-B2b products during the location service operation, and generates a complete correction product set, a compatible correction product set, or a simplified correction product set based on the determination results. This enables the PPP-RTK location service to continuously output correction product sets according to the actual availability status of the ephemeris products. When the ephemeris scene changes, this embodiment inherits the solution state of the ephemeris scene before the switch, allowing subsequent positioning solutions to continue based on the existing solution state. This reduces the risk of location service interruption or re-initialization due to ephemeris product delays, interruptions, or unavailability.

[0037] Example 2 This embodiment, based on Embodiment 1, further explains the process of determining the availability status of precise ephemeris and PPP-B2b products.

[0038] During the location service operation, the PPP-RTK positioning system uses precise ephemeris and PPP-B2b products as ephemeris products to be judged, and determines the availability status of these ephemeris products. The PPP-RTK positioning system can judge the ephemeris products to be judged from three aspects: timeliness, continuity, and completeness, to determine whether the ephemeris products to be judged can participate in the corresponding ephemeris scene processing steps during the current location service operation.

[0039] Specifically, the timeliness determination is used to determine whether the ephemeris product is still within the time range available for current positioning calculation. The PPP-RTK positioning system acquires the product reception time and nominal time of the ephemeris product, calculates the time difference between the product reception time and the nominal time, and compares this time difference with a preset timeliness threshold. When the time difference is not greater than the preset timeliness threshold, the corresponding ephemeris product is determined to meet the timeliness requirement; when the time difference is greater than the preset timeliness threshold, the corresponding ephemeris product is determined to not meet the timeliness requirement. The preset timeliness threshold can be set according to the real-time requirements of the positioning service, the ephemeris product update cycle, and the system operating environment.

[0040] Continuity determination is used to assess whether an ephemeris product is stably available over a continuous operating period. The PPP-RTK positioning system statistically analyzes the epoch missing rate, continuous interruption duration, and / or interruption frequency of the corresponding ephemeris product within a preset epoch window. The epoch missing rate represents the percentage of epochs in which the corresponding ephemeris product was not successfully received within the preset epoch window; the continuous interruption duration represents the duration during which the corresponding ephemeris product was continuously unreceived or unavailable; and the number of interruptions represents the number of times the corresponding ephemeris product transitioned from an available state to an unavailable state within the preset epoch window. The PPP-RTK positioning system statistically analyzes at least one of the epoch missing rate, continuous interruption duration, and interruption frequency of the ephemeris product to be determined within the preset epoch window to obtain continuity statistics. These statistics are then compared with corresponding preset missing rate thresholds, preset interruption duration thresholds, or preset interruption frequency thresholds. When all continuity statistics meet the corresponding threshold requirements, the ephemeris product to be determined is deemed to meet the continuity requirements. By determining continuity, we can avoid directly using ephemeris products that experience short-term, frequent interruptions or lack stability in the current ephemeris processing steps.

[0041] Integrity assessment is used to determine whether the information contained in an ephemeris product meets the basic requirements for the current calculation. The PPP-RTK positioning system determines whether the corresponding ephemeris product meets the integrity requirements based on whether the product message of the currently received ephemeris product passes verification, whether the necessary correction fields are complete, and whether the number of available satellites meets the preset minimum calculation requirements. The necessary correction fields can be determined according to the type of the corresponding ephemeris product. For example, for precise ephemeris products, fields related to determining satellite orbits and clock biases may be included; for PPP-B2b products, fields such as satellite orbit information, satellite clock bias information, and code offset information may be included. Meeting the preset minimum calculation requirements for the number of available satellites means that the number of satellites currently available for positioning calculation can support subsequent PPP-RTK calculations or corresponding downgraded positioning calculations. When the corresponding ephemeris product simultaneously meets the timeliness, continuity, and integrity requirements, the PPP-RTK positioning system determines that the ephemeris product is usable; when the corresponding ephemeris product does not meet any of the above requirements, the PPP-RTK positioning system determines that the ephemeris product is unusable. Therefore, the PPP-RTK positioning system can continuously determine the availability status of precise ephemeris and PPP-B2b products during the positioning service operation, and determine the ephemeris scene processing steps to be executed based on the judgment results.

[0042] For example, when precise ephemeris meets the timeliness, continuity, and integrity requirements, the PPP-RTK positioning system determines that the current processing step for the precise ephemeris scenario is to be used; when precise ephemeris is unavailable but the PPP-B2b product meets the timeliness, continuity, and integrity requirements, the PPP-RTK positioning system determines that the current processing step for the PPP-B2b scenario is to be used; when both precise ephemeris and the PPP-B2b product are unavailable, the PPP-RTK positioning system determines that the current processing step for the broadcast ephemeris scenario is to be used. Through the above discrimination method, the system can select the corresponding processing step based on the actual availability of the ephemeris product during the positioning service operation, providing a basis for judgment for the subsequent continuous generation of correction product sets.

[0043] Example 3 This embodiment further explains the PPP-RTK basic observation model based on Embodiments 1 and 2.

[0044] In this embodiment, the precise ephemeris scene processing step, the PPP-B2b scene processing step, and the broadcast ephemeris scene processing step are all executed based on the PPP-RTK basic observation model. By sharing the PPP-RTK basic observation model under different ephemeris scenes, the correction of observation values, parameter processing, and generation of calibration product sets from different ephemeris sources can have a unified model basis, thereby reducing the problem of discontinuous solution states caused by model differences when switching ephemeris scenes.

[0045] Specifically, the PPP-RTK positioning system is based on the non-differential, non-combined GNSS observation equations. It performs unified modeling and reorganization of the parameters to be estimated, and incorporates ionospheric constraint information to construct the non-differential, non-combined PPP-RTK basic observation model. The non-differential, non-combined GNSS observation equations are fundamental observation models in the field of GNSS precise positioning, used to describe the relationship between pseudorange and carrier phase observations and parameters such as receiver, satellite, atmospheric delay, hardware bias, and phase ambiguity. These equations can preserve the original observation information without linearly combining observations from different frequencies, facilitating subsequent adaptation of observations and parameters to be estimated according to different ephemeris scenarios.

[0046] After constructing the non-differential, non-combined GNSS observation equations, the PPP-RTK positioning system performs unified modeling and reorganization of the parameters to be estimated in these equations. Since there may be correlations or rank deficiencies among different parameters in the original observation equations, the system can transform the original parameters into estimable parameters by selecting a reference station and a reference satellite, and by combining the bias parameters. This yields a full-rank observation model suitable for PPP-RTK solutions, providing a unified parameter expression basis for subsequent parameter estimation and correction product set generation under different ephemeris scenarios.

[0047] Subscript Represents the selected reference station; with The parameters represent the estimable parameters after the full-rank observation equation. The new estimable parameters are specifically expressed as:

[0048] in, Indicates the receiver identifier; Indicates satellite identifier; Indicates frequency identification; and These represent the receiver and satellite clock bias, respectively. and These represent the zenith tropospheric delay and its projection function, respectively; Indicates ionospheric slack delay; , which is the ionospheric coefficient, specifically representing the ratio between the ionospheric delay at other frequencies and the first frequency; Indicates the first Frequency point wavelength; and These represent receiver and satellite code offsets, respectively. and These represent the receiver and satellite phase deviations, respectively. Indicates phase ambiguity; subscript and superscript These represent the selected reference station and reference satellite, respectively; and , and , They are respectively and The code bias parameters are decomposed into geometrically independent combinations and ionospheric de-combinations. During the parameter recombination process described above, the code bias parameters can be decomposed into geometrically independent combinations and ionospheric de-combinations, and estimated parameters can be determined by combining the reference station and reference satellite. This process ensures that the estimated parameters in the PPP-RTK basic observation model maintain an interpretable and updatable form in subsequent precise ephemeris scenarios, PPP-B2b scenarios, and broadcast ephemeris scenarios.

[0049] Based on the estimable parameters mentioned above, the PPP-RTK positioning system further incorporates ionospheric constraint information to form a non-differential, non-combined PPP-RTK basic observation model. The ionospheric constraint information is used to constrain the ionospheric slant delay parameters, enabling the basic observation model to improve the stability and convergence performance of subsequent PPP-RTK solutions while preserving the non-differential, non-combined observation structure. The non-differential, non-combined PPP-RTK basic observation model can be expressed as:

[0050] in, Represents the expectation operator; and These represent the corrected pseudorange and carrier phase observations, respectively, after deducting errors such as antenna phase center deviation, antenna phase center variation, phase entanglement, and solid moisture. The term representing the geometric distance from the satellite to the receiver characterizes the spatial geometric relationship between the satellite and the receiver, i.e., the satellite-to-ground distance. The remaining parameters are the same as previously defined.

[0051] The PPP-RTK basic observation model serves as a common model foundation for processing steps in different ephemeris scenarios: in the precise ephemeris scenario, the system generates a complete set of correction products based on this model; in the PPP-B2b scenario, the system incorporates the PPP-B2b product benchmark into the model and performs equivalent reorganization of the remaining parameters to be estimated; in the broadcast ephemeris scenario, the system performs simplified PPP-RTK calculations based on this model and generates a simplified set of correction products without independent satellite orbit corrections.

[0052] In this embodiment, the processing of different ephemeris scenarios is built on the same PPP-RTK basic observation model, so that the solution state can be inherited and updated around the same model base when switching ephemeris scenarios, thereby providing model support for continuous solution during the operation of the positioning service.

[0053] Example 4 This embodiment, based on embodiment 3, further explains the PPP-B2b scenario processing steps when precise ephemeris is unavailable but the PPP-B2b product is available.

[0054] During the operation of the positioning service, when the PPP-RTK positioning system determines, based on the availability status judgment result described in Example 2, that precise ephemeris is unavailable and the PPP-B2b product is available, the PPP-RTK positioning system executes the PPP-B2b scene processing step. This PPP-B2b scene processing step is used to correct the raw GNSS observation data using the satellite orbit information, satellite clock bias information, and code offset information provided by the PPP-B2b product in the absence of precise ephemeris, and to perform parameter adaptation processing based on the PPP-RTK basic observation model described in Example 3, in order to generate a compatible correction product set compatible with the complete correction product set.

[0055] Specifically, the PPP-RTK positioning system integrates the product reference used by the PPP-B2b product into the PPP-RTK basic observation model. As one implementation method, the PPP-B2b product can use the code deviation of the BDS B3I signal as the product reference. Since the product reference of the PPP-B2b product is not entirely the same as the reference reference of related parameters in the basic observation model under precise ephemeris scenarios, directly using the correction information provided by the PPP-B2b product for calculation can easily lead to inconsistencies in the meaning of parameters between different ephemeris scenarios. Therefore, this embodiment performs consistency processing on the parameters related to the PPP-B2b product reference in the PPP-RTK basic observation model, so that the correction information provided by the PPP-B2b product can be integrated into the same basic observation model.

[0056] At this point, the PPP-RTK basic observation equations are updated in the PPP-B2b scenario as follows:

[0057] in, and These represent the corrected pseudorange and carrier phase observations, respectively. Besides correcting system errors, they also correct the PPP-B2b product reference and correction information; [with...] The parameters represent the estimable parameters of the PPP-RTK basic observation equations after correction and equivalent recombination using the PPP-B2b product.

[0058] After integrating the product baseline, the PPP-RTK positioning system uses the satellite orbit information, satellite clock bias information, and code offset information provided by the PPP-B2b product to correct the pseudorange and carrier phase observations in the raw GNSS observation data, obtaining corrected observations for the PPP-B2b scenario. Specifically, satellite orbit information is used to correct satellite orbit-related errors, satellite clock bias information is used to correct satellite clock bias-related errors, and code offset information is used to correct code offset-related errors in the pseudorange observations. After these corrections, the parameters already provided by the PPP-B2b product and involved in the observation correction are no longer considered as parameters to be estimated in subsequent PPP-RTK calculations.

[0059] Building upon the above, the PPP-RTK positioning system performs equivalent recombination of the remaining parameters to be estimated in subsequent calculations. These remaining parameters may include those not directly provided by the PPP-B2b product and still requiring estimation through calculation, such as parameters related to phase deviation, ionospheric delay, tropospheric delay, or other error terms not directly corrected by the PPP-B2b product. By equivalent recombination of these remaining parameters, the expression of the parameters in the PPP-B2b scenario can remain compatible with the parameter structure corresponding to the complete calibration product set, thereby avoiding abrupt changes in the calibration product set structure due to variations in ephemeris sources.

[0060] The estimable parameters of the PPP-RTK basic observation equations, after correction and equivalent recombination using the PPP-B2b product, are specifically expressed as follows:

[0061] in, The code deviation of the BDS B3I signal is used as the product reference for BDS PPP-B2b; the meanings of the remaining parameters are consistent with the meanings of the corresponding parameters in the estimable parameter expressions after the non-differential non-combined GNSS observation equation and the full-rank observation equation.

[0062] The PPP-RTK positioning system performs PPP-RTK calculations based on corrected observations in the PPP-B2b scenario and the remaining parameters to be estimated after equivalent reconstruction, generating a compatible calibration product set. The compatibility of the compatible calibration product set with the complete calibration product set means that the compatible calibration product set maintains a correspondence with the complete calibration product set in terms of calibration data type, output format, or positioning terminal interface. This allows the positioning terminal to continue performing positioning calculations based on processing logic adapted to the complete calibration product set after receiving the compatible calibration product set.

[0063] As one implementation, in a PPP-B2b scenario, the compatible correction product set may include satellite orbit-related correction data, satellite clock bias-related correction data, and satellite code bias-related correction data provided or corrected based on PPP-B2b products. It may further include satellite phase bias correction data, ionospheric delay correction data, and tropospheric delay correction data calculated via PPP-RTK. Therefore, even when precise ephemeris is unavailable but PPP-B2b products are available, the system can still generate a correction product set for use by the positioning terminal and maintain compatibility with the complete correction product set in a precise ephemeris scenario.

[0064] Through the PPP-B2b scene processing steps described above, this embodiment does not simply use PPP-B2b products as a substitute input for precise ephemeris data. Instead, it integrates the PPP-B2b product benchmark into the PPP-RTK basic observation model and performs adaptation processing on the observed values ​​and remaining parameters to be estimated. Therefore, the system can continue to generate a compatible correction product set using PPP-B2b products when precise ephemeris data is unavailable, providing support for ephemeris scene switching and continuous calculation by the positioning terminal.

[0065] Example 5 This embodiment, based on embodiments 1 to 3, further explains the processing steps for a precise ephemeris scene when precise ephemeris is available.

[0066] During the operation of the positioning service, when the PPP-RTK positioning system determines that precise ephemeris is available based on the availability status judgment result described in Example 2, the PPP-RTK positioning system executes the precise ephemeris scene processing step. The precise ephemeris scene processing step utilizes the high-precision satellite orbit information provided by the precise ephemeris to perform PPP-RTK calculations and generate a complete correction product set. This complete correction product set is used to provide the positioning terminal with relatively complete correction data for satellite orbits, satellite clock bias, satellite code bias, satellite phase bias, ionospheric delay, and tropospheric delay.

[0067] Specifically, the PPP-RTK positioning system calculates the precise satellite-to-ground distance based on precise ephemeris data. This precise satellite-to-ground distance characterizes the geometric distance between the satellite and the receiver, determined based on the satellite orbit information provided by the precise ephemeris. Because precise ephemeris provides highly accurate satellite orbit information, the precise satellite-to-ground distance calculated based on it can be used to correct the geometric distance term in the raw GNSS observation data.

[0068] The PPP-RTK positioning system subtracts the precise satellite-to-ground distance from the pseudorange and carrier phase observations in the raw GNSS observation data to obtain corrected observations under the precise ephemeris scenario. These corrected observations are used in subsequent PPP-RTK calculations, ensuring that the subsequent parameter estimation process does not repeatedly estimate the geometric distance portion already determined by the precise ephemeris. This allows the calculation process to focus on estimating satellite clock errors, bias parameters, atmospheric delay parameters, and other parameters to be estimated.

[0069] Furthermore, the PPP-RTK positioning system determines a satellite orbit correction based on the orbital difference between the precise satellite orbit provided by the precise ephemeris and the satellite orbit of the broadcast ephemeris at the corresponding time. This satellite orbit correction characterizes the difference between the broadcast ephemeris satellite orbit and the precise satellite orbit. The PPP-RTK positioning system generates satellite orbit correction data based on the satellite orbit correction and outputs the satellite orbit correction data as part of a complete correction product set.

[0070] After obtaining corrected observations under precise ephemeris conditions, the PPP-RTK positioning system performs PPP-RTK calculations based on these corrected observations, generating satellite clock error correction data, satellite code offset correction data, satellite phase offset correction data, ionospheric delay correction data, and tropospheric delay correction data. These correction data are used to correct the corresponding satellite clock error, code offset error, phase offset error, ionospheric delay error, and tropospheric delay error during the positioning terminal's calculation process, respectively.

[0071] As one implementation method, the PPP-RTK positioning system can perform parameter estimation in a precise ephemeris scenario based on the PPP-RTK basic observation model described in Example 3, and generate the aforementioned correction data based on the parameter estimation results. Specifically, the precise satellite-to-ground distance is used to correct pseudorange and carrier phase observations. The satellite orbit correction is determined based on the orbit difference between the precise satellite orbit provided by the precise ephemeris and the satellite orbit of the broadcast ephemeris at the corresponding time. The satellite clock error correction data, satellite code deviation correction data, satellite phase deviation correction data, ionospheric delay correction data, and tropospheric delay correction data are generated based on the PPP-RTK calculation results.

[0072] The PPP-RTK positioning system forms a complete set of calibration products based on the satellite orbit correction data, satellite clock error correction data, satellite code deviation correction data, satellite phase deviation correction data, ionospheric delay correction data, and tropospheric delay correction data. This complete set of calibration products can be output to the positioning terminal according to a preset data format, enabling the positioning terminal to perform PPP-RTK positioning calculations based on this complete set of calibration products.

[0073] Through the aforementioned precise ephemeris scene processing steps, this embodiment generates a complete calibration product set when precise ephemeris is available, providing relatively complete calibration data for the positioning terminal. This complete calibration product set can also serve as a structural reference for compatible calibration product sets in PPP-B2b scenarios, ensuring that calibration product sets output under different ephemeris scenarios maintain a consistent relationship.

[0074] Example 6 This embodiment, based on embodiment 1, further explains the processing steps for a broadcast ephemeris scenario when both precise ephemeris and PPP-B2b products are unavailable.

[0075] During the operation of the positioning service, when the PPP-RTK positioning system determines, based on the availability status judgment result described in Example 2, that both the precise ephemeris and the PPP-B2b product are unavailable, the PPP-RTK positioning system executes the broadcast ephemeris scene processing step. This broadcast ephemeris scene processing step is used to continue performing simplified PPP-RTK calculations based on the broadcast ephemeris when precise ephemeris and PPP-B2b products are unavailable, and to generate a simplified correction product set without independent satellite orbit corrections, thereby maintaining the basic continuous operation of the positioning service.

[0076] Specifically, the PPP-RTK positioning system calculates the approximate satellite-to-ground distance based on broadcast ephemeris data. This approximate distance characterizes the geometric distance between the satellite and the receiver, determined based on the satellite orbit information provided by the broadcast ephemeris. Compared to precise ephemeris data, the satellite orbit accuracy provided by broadcast ephemeris data is lower; therefore, the satellite-to-ground distance calculated based on broadcast ephemeris data is the approximate distance.

[0077] The PPP-RTK positioning system subtracts the approximate satellite-to-ground distance from the pseudorange and carrier phase observations in the raw GNSS observation data to obtain corrected observations for the broadcast ephemeris scenario. This processing establishes a foundation of observations that can continue to participate in the calculation under the broadcast ephemeris scenario, enabling the system to perform subsequent simplified calculations even when precise ephemeris and PPP-B2b products are unavailable.

[0078] Furthermore, due to insufficient orbital accuracy in broadcast ephemeris scenarios, generating satellite orbital correction data separately may introduce unstable orbital correction results, affecting the reliability of the correction product set. Therefore, in this embodiment, the PPP-RTK positioning system does not generate independent satellite orbital correction data, but instead incorporates the orbital errors caused by insufficient broadcast ephemeris orbital accuracy into the satellite clock bias parameters for unified modeling and estimation.

[0079] Based on the above, the PPP-RTK positioning system performs simplified PPP-RTK calculations using corrected observations under broadcast ephemeris scenarios, generating a simplified correction product set. This simplified correction product set does not include independent satellite orbit corrections but may include satellite clock bias correction data, satellite code bias correction data, satellite phase bias correction data, ionospheric delay correction data, and tropospheric delay correction data. Specifically, the satellite clock bias correction data characterizes the satellite clock bias-related correction information after unified modeling and estimation under broadcast ephemeris scenarios; the satellite code bias correction data and satellite phase bias correction data are used to correct deviations related to pseudorange and carrier phase observations during the positioning terminal's calculation process, respectively; and the ionospheric delay correction data and tropospheric delay correction data are used to correct the propagation delay effects of the ionosphere and troposphere on GNSS observations, respectively.

[0080] As one implementation, the PPP-RTK positioning system can encapsulate the simplified calibration product set according to a data format adapted to both the complete calibration product set and the compatible calibration product set, enabling the positioning terminal to recognize that the simplified calibration product set does not contain independent satellite orbit correction data, and thereby select the corresponding positioning mode to perform positioning calculations.

[0081] Through the above-described broadcast ephemeris scene processing steps, this embodiment can still generate a simplified correction product set that the positioning terminal can continue to use based on the broadcast ephemeris when both precise ephemeris and PPP-B2b products are unavailable. Therefore, the system can maintain the output of the correction product set and the positioning calculation process even when the availability of multi-source ephemeris products is reduced, thus mitigating the risk of direct interruption of positioning services.

[0082] Example 7 This embodiment, based on embodiment 1, further explains the switching of processing steps and the inheritance process of solution state when the ephemeris scene changes.

[0083] During the operation of the positioning service, the availability status of precise ephemeris, PPP-B2b products, and broadcast ephemeris may change over time. Based on the availability status determination result described in Example 2, the PPP-RTK positioning system can switch the corresponding ephemeris scene processing steps between precise ephemeris scenes, PPP-B2b scenes, and broadcast ephemeris scenes.

[0084] For example, during the current operational phase, if the precise ephemeris meets the timeliness, continuity, and completeness requirements, the PPP-RTK positioning system executes the precise ephemeris scene processing step and generates a complete calibration product set. In subsequent operations, if the precise ephemeris experiences delays, interruptions, or insufficient completeness, while the PPP-B2b product meets the availability requirements, the PPP-RTK positioning system switches to the PPP-B2b scene processing step based on the new judgment result and generates a compatible calibration product set. As another example, if both the precise ephemeris and the PPP-B2b product are unavailable, the PPP-RTK positioning system switches to the broadcast ephemeris scene processing step and generates a simplified calibration product set.

[0085] During ephemeris scene switching, the PPP-RTK positioning system inherits the solution state of the ephemeris scene before the switch. The solution state can include state parameters and their covariance information in the PPP-RTK solution. The state parameters can include receiver position parameters, receiver clock error parameters, atmospheric delay parameters, bias parameters, ambiguity parameters, or other state variables involved in the PPP-RTK solution; the covariance information is used to characterize the uncertainty or estimation accuracy of the above state parameters.

[0086] Specifically, when the ephemeris scene changes, the PPP-RTK positioning system does not discard the solution results already obtained under the previous ephemeris scene. Instead, it inherits the state parameters and covariance information corresponding to the previous ephemeris scene. Subsequently, the PPP-RTK positioning system updates the inherited state parameters and covariance information according to the processing steps of the new ephemeris scene.

[0087] For example, when switching from a precise ephemeris scenario to a PPP-B2b scenario, the PPP-RTK positioning system can inherit the original state parameters and their covariance information, and combine this with the satellite orbit information, satellite clock bias information, and code offset information provided by the PPP-B2b product to adapt the observed values ​​and remaining parameters to be estimated, and continue to perform PPP-RTK calculations. When switching from a PPP-B2b scenario to a broadcast ephemeris scenario, the PPP-RTK positioning system can inherit the original state parameters and their covariance information, and follow the broadcast ephemeris scenario processing steps to incorporate the broadcast ephemeris orbit error into the satellite clock bias parameters for unified modeling and estimation, and continue to perform simplified PPP-RTK calculations.

[0088] During the aforementioned switching process, the PPP-RTK positioning system inherits and updates the solution state, enabling subsequent positioning calculations to continue based on the existing solution state, without needing to reinitialize the entire positioning calculation process every time the ephemeris scene changes. This reduces the risk of positioning result interruptions, positioning re-convergence, or discontinuous output of the correction product set due to changes in the availability of ephemeris products.

[0089] As one implementation method, the PPP-RTK positioning system can also output the ephemeris scene, correction data type and validity status corresponding to the current correction product set to the positioning terminal when outputting the correction product set, so that the positioning terminal can identify the changes in the current correction product set and perform the corresponding positioning calculation based on the current correction product set.

[0090] Through the above methods, this embodiment can switch processing steps and inherit the solution state when the ephemeris scene changes, so that the switching process between the precise ephemeris scene, the PPP-B2b scene and the broadcast ephemeris scene is continuous, thereby improving the stability of the positioning service under the condition of changes in the availability of multi-source ephemeris products.

[0091] Example 8 This embodiment, based on embodiment 1, further explains the process by which the positioning terminal performs positioning calculations based on the calibration product set.

[0092] In this embodiment, the positioning terminal receives a calibration product set output by the PPP-RTK positioning system. The calibration product set can be a complete calibration product set generated in a precise ephemeris scenario, a compatible calibration product set generated in a PPP-B2b scenario, or a simplified calibration product set generated in a broadcast ephemeris scenario. After receiving the calibration product set, the positioning terminal parses it to identify the types of calibration data and their valid states.

[0093] Specifically, the data type of the correction may include one or more of the following: satellite orbit correction data, satellite clock error correction data, satellite code deviation correction data, satellite phase deviation correction data, ionospheric delay correction data, and tropospheric delay correction data. The valid state can be used to characterize whether the corresponding correction data is currently available, such as whether it is within a valid time range, whether it has passed an integrity check, and whether it can meet the calculation requirements of the current positioning mode.

[0094] The positioning terminal selects the appropriate positioning mode from PPP-RTK, PPP-AR, PPP, and SPP positioning modes based on the completeness and validity of the calibration product set. As one implementation, when the calibration product set received by the positioning terminal contains complete and valid satellite orbit correction data, satellite clock error correction data, bias correction data, ionospheric delay correction data, and tropospheric delay correction data, the positioning terminal can select the PPP-RTK positioning mode. When the calibration product set received by the positioning terminal supports ambiguity fixing or phase deviation processing, but the integrity of the correction data is lower than that required for the PPP-RTK positioning mode, the positioning terminal can select the PPP-AR positioning mode. When the calibration product set received by the positioning terminal can only support precise single-point positioning calculations, the positioning terminal can select the PPP positioning mode. When the positioning terminal does not obtain a valid calibration product set that can be used for high-precision correction, the positioning terminal can select the SPP positioning mode.

[0095] During the positioning calculation process, when the data type or validity status of the calibration products received by the positioning terminal changes, the positioning terminal updates the current calibration information status. The current calibration information status may include the currently available calibration data types, the validity status of each calibration data point, the currently applicable positioning mode, and the corresponding positioning calculation parameters. Based on the updated current calibration information status, the positioning terminal selects or adjusts the positioning mode and continues to perform the positioning calculation without re-initializing the process.

[0096] For example, if a positioning terminal initially performs PPP-RTK positioning calculation based on a complete calibration product set, and subsequently receives a compatible calibration product set, the positioning terminal can update the current calibration information status and select PPP-RTK, PPP-AR, or PPP positioning mode based on the completeness and validity of the compatible calibration product set. As another example, if the positioning terminal receives a simplified calibration product set, it can select PPP or SPP positioning mode based on the available calibration data types in the simplified calibration product set. In these processes, the positioning terminal does not reinitialize the positioning calculation process; instead, it continues the calculation based on the existing positioning calculation status.

[0097] As one implementation method, such as Figure 3As shown, the positioning terminal may include a communication module, a data sensing module, and a core processing module. The communication module receives a calibration product set; the data sensing module parses the calibration product set, identifying the calibration data types and validity statuses contained within it; the core processing module selects the corresponding positioning mode from PPP-RTK, PPP-AR, PPP, and SPP positioning modes based on the completeness and validity status of the calibration product set, and performs positioning calculations based on the selected mode. When the calibration product set changes, the core processing module updates the current calibration information status and performs positioning calculations without re-initializing the positioning calculation process.

[0098] In this way, the positioning terminal can adaptively select the corresponding positioning mode based on different calibration product sets output by the server, and continue to perform positioning calculations by updating the current calibration information status when the calibration product set changes. Therefore, the positioning terminal can adapt to changes in the calibration product set after the server's ephemeris scene switching, ensuring continuous output of positioning results.

[0099] Example 9 This embodiment, based on embodiments 1 to 8, further illustrates the PPP-RTK positioning system for multi-ephemeris availability scenarios.

[0100] Figure 2 This is a schematic diagram of the structure of a PPP-RTK positioning system for multi-ephemeris availability scenarios provided in an embodiment of the present invention. Figure 2 As shown, the PPP-RTK positioning system provided in this embodiment includes a data acquisition unit, an ephemeris discrimination unit, an ephemeris scene processing unit, a strategy switching unit, and a calibration product output unit. Each of these units can be implemented through software, hardware, or a combination of both, and can be deployed in servers, edge computing devices, base station network processing platforms, or other computing devices with data processing capabilities.

[0101] The data acquisition unit is used to acquire multi-source ephemeris products and raw GNSS observation data. The multi-source ephemeris products include precise ephemeris, PPP-B2b products, and broadcast ephemeris; the raw GNSS observation data may include pseudorange observations and carrier phase observations from GNSS satellites. In one implementation, the data acquisition unit can receive precise ephemeris through an external data interface, acquire PPP-B2b products by receiving or decoding BeiDou PPP-B2b signals, and acquire broadcast ephemeris and raw GNSS observation data through GNSS receiving equipment or related data interfaces.

[0102] The ephemeris discrimination unit is used to determine the availability status of precise ephemeris and PPP-B2b products during the operation of the positioning service. Specifically, the ephemeris discrimination unit can perform timeliness discrimination, continuity discrimination, and integrity discrimination on precise ephemeris and PPP-B2b products respectively, as described in Embodiment 2, and determine the availability status of precise ephemeris and PPP-B2b products in the current positioning service operation based on the discrimination results.

[0103] The ephemeris scene processing unit is used to execute corresponding ephemeris scene processing steps based on the discrimination result output by the ephemeris discrimination unit, and to generate a corresponding correction product set. The correction product set can be one of a complete correction product set, a compatible correction product set, or a simplified correction product set. As one implementation, the ephemeris scene processing unit may include a precise ephemeris processing subunit, a PPP-B2b processing subunit, and a broadcast ephemeris processing subunit.

[0104] The precise ephemeris processing subunit is used to perform precise ephemeris scene processing steps when precise ephemeris is available. Specifically, the precise ephemeris processing subunit can calculate the precise satellite-to-ground distance based on the precise ephemeris, and subtract the precise satellite-to-ground distance from the pseudorange observations and carrier phase observations in the raw GNSS observation data to obtain the corrected observations under the precise ephemeris scene; it can also determine the satellite orbit correction amount based on the orbit difference between the precise satellite orbit provided by the precise ephemeris and the satellite orbit of the broadcast ephemeris at the corresponding time, and generate satellite orbit correction data; further, it performs PPP-RTK calculation based on the corrected observations under the precise ephemeris scene to generate a complete correction product set.

[0105] The PPP-B2b processing subunit is used to perform PPP-B2b scene processing steps when precise ephemeris is unavailable but the PPP-B2b product is available. Specifically, the PPP-B2b processing subunit can integrate the product benchmark used by the PPP-B2b product into the PPP-RTK basic observation model, and use the satellite orbit information, satellite clock bias information, and code offset information provided by the PPP-B2b product to correct the raw GNSS observation data, obtaining corrected observation values ​​under the PPP-B2b scene, and equivalently recombining the remaining parameters to be estimated in subsequent solutions. Thus, the PPP-B2b processing subunit can perform PPP-RTK solutions based on the corrected observation values ​​under the PPP-B2b scene and the equivalently recombined remaining parameters to be estimated, generating a compatible correction product set that is compatible with the complete correction product set.

[0106] The broadcast ephemeris processing subunit is used to perform broadcast ephemeris scene processing steps when neither precise ephemeris nor PPP-B2b products are available, and to generate a simplified correction product set without independent satellite orbit correction based on the broadcast ephemeris. Specifically, the broadcast ephemeris processing subunit can calculate the approximate satellite-to-ground distance based on the broadcast ephemeris, and subtract the approximate satellite-to-ground distance from the pseudorange observations and carrier phase observations in the raw GNSS observation data to obtain the corrected observations under the broadcast ephemeris scene. Due to the insufficient orbit accuracy of the broadcast ephemeris, the broadcast ephemeris processing subunit does not generate independent satellite orbit correction data, but instead incorporates the orbit error into the satellite clock error parameters for unified modeling and estimation, and performs simplified PPP-RTK calculation based on the corrected observations under the broadcast ephemeris scene to generate the simplified correction product set.

[0107] The strategy switching unit is used to switch to the corresponding ephemeris scene processing step based on the discrimination result output by the ephemeris discrimination unit when the ephemeris scene changes, and inherits the solution state of the ephemeris scene before the switch. The solution state may include the state parameters and their covariance information in the PPP-RTK solution. Specifically, the strategy switching unit can switch between precise ephemeris scenes, PPP-B2b scenes, and broadcast ephemeris scenes, and during the switching process, it provides the state parameters and their covariance information corresponding to the ephemeris scene before the switch to the ephemeris scene processing step after the switch, so that subsequent solutions can continue based on the existing solution state.

[0108] The calibration product output unit outputs the calibration product set generated by the ephemeris scene processing unit to the positioning terminal, enabling the positioning terminal to perform positioning calculations based on the calibration product set. As one implementation, the calibration product output unit can encapsulate a complete calibration product set, a compatible calibration product set, or a simplified calibration product set according to a preset data format and send the encapsulated calibration product set to the positioning terminal. The preset data format may include calibration data type, validity status, time identifier, satellite identifier, and corresponding calibration data content, enabling the positioning terminal to identify the completeness and validity status of the calibration product set.

[0109] Through the above system architecture, the PPP-RTK positioning system provided in this embodiment can adaptively execute corresponding ephemeris scene processing steps based on the availability of precise ephemeris and PPP-B2b products during the positioning service operation, and inherit the solution state of the ephemeris scene before the switch when the ephemeris scene changes. Therefore, the system can continuously generate a set of correction products adapted to the current ephemeris scene and provide correction information support for the positioning terminal to continuously perform positioning calculations.

[0110] Example 10 This embodiment describes the actual testing process and test results of the embodiments of the present invention, based on embodiments 1 to 9.

[0111] Figure 4 This is a map showing the distribution of wide-area reference stations and the vehicle-mounted test area in this embodiment of the invention. As one implementation method, this embodiment uses a wide-area reference station network to acquire raw GNSS observation data and generates a calibration product set based on the methods and systems described in Embodiments 1 to 9. The wide-area reference station network can be deployed over a large area, with each reference station receiving GNSS satellite signals and outputting raw observation data. The PPP-RTK positioning system performs corresponding ephemeris scene processing steps based on the raw observation data and multi-source ephemeris products to generate a calibration product set for use by the positioning terminal. This calibration product set can be one of a complete calibration product set, a compatible calibration product set, or a simplified calibration product set.

[0112] In this embodiment, the positioning terminal is installed on a vehicle-mounted platform and undergoes actual vehicle-mounted testing within the test area. During the test, the positioning terminal receives the calibration product set output by the PPP-RTK positioning system and selects the corresponding positioning mode to perform positioning calculation based on the completeness and validity status of the calibration product set. The test area, base station distribution, and vehicle-mounted test route can be found in [reference needed]. Figure 4 .

[0113] As one implementation method, during vehicle-mounted testing, the PPP-RTK positioning system can generate a complete calibration product set, a compatible calibration product set, or a simplified calibration product set based on the real-time availability of precise ephemeris, PPP-B2b products, and broadcast ephemeris. When the ephemeris scene changes, the system switches to the corresponding ephemeris scene processing step based on the judgment result, and inherits the solution state of the ephemeris scene before the switch. After receiving the calibration product set, the positioning terminal parses the calibration data type and validity status, and continues to perform positioning calculation based on the current calibration product set.

[0114] Figure 5 This is an error diagram of the actual vehicle-mounted test of the positioning terminal in this embodiment of the invention. Figure 5 This can be used to demonstrate the changes in positioning error of a positioning terminal in different directions during vehicle-mounted testing. As one implementation method, the northeast-to-sky direction error can be used to evaluate the positioning effect of the positioning terminal, where the eastward error, northward error, and skyward error are used to characterize the deviation of the positioning terminal's calculation results from the reference results in the corresponding directions.

[0115] In one test result of this embodiment, the root mean square errors of the positioning terminal in the three directions of northeast, zenith, and celestial were 0.39cm, 0.43cm, and 0.98cm, respectively, during the actual vehicle-mounted test. These results indicate that under the wide-area reference station network and vehicle-mounted test conditions described in this embodiment, the positioning terminal can obtain centimeter-level positioning results based on the calibration product set output by the PPP-RTK positioning system.

[0116] It should be noted that the above test results are used to illustrate the positioning effect of the method, system, and terminal described in the embodiments of the present invention in actual test scenarios, and do not constitute a limitation on the scope of protection of the present invention. Different test areas, base station deployment methods, satellite observation conditions, vehicle operating status, and ephemeris product availability may all lead to changes in the specific error results.

[0117] The above testing process demonstrates that the PPP-RTK positioning method, system, and terminal provided in this embodiment for multi-ephemeral availability scenarios can generate corresponding correction product sets based on the availability status of multi-source ephemeral products during actual positioning service operation, and enable the positioning terminal to perform positioning calculations based on the received correction product sets. Combined with the ephemeral scenario switching and calculation state inheritance process described in Embodiment 7, this invention can reduce the risk of positioning service interruption or re-initialization when the availability status of ephemeral products changes, thereby improving the continuity and stability of PPP-RTK positioning services.

[0118] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A PPP-RTK positioning method for multi-ephemeris availability scenarios, characterized in that, Includes the following steps: Acquire multi-source ephemeris products and raw GNSS observation data, wherein the multi-source ephemeris products include precise ephemeris, PPP-B2b products and broadcast ephemeris; During the operation of the location service, the availability status of the precise ephemeris and the PPP-B2b product is determined; Based on the discrimination result, the corresponding ephemeris scene processing steps are executed to generate a corresponding correction product set; wherein, the correction product set is one of a complete correction product set, a compatible correction product set, and a simplified correction product set; when the precise ephemeris is available, the complete correction product set is generated; when the precise ephemeris is unavailable but the PPP-B2b product is available, the compatible correction product set compatible with the complete correction product set is generated; when both the precise ephemeris and the PPP-B2b product are unavailable, the simplified correction product set without independent satellite orbit correction is generated based on the broadcast ephemeris; When the ephemeris scene changes, the corresponding ephemeris scene processing step is switched according to the discrimination result, and the solution state of the ephemeris scene before the switch is inherited. The generated calibration product set is output to the positioning terminal so that the positioning terminal can perform positioning calculations based on the calibration product set.

2. The PPP-RTK positioning method for multi-ephemeral availability scenarios according to claim 1, characterized in that, Determining the availability status of the precise ephemeris and the PPP-B2b product includes: The precise ephemeris and the PPP-B2b product are respectively used as ephemeris products to be judged, and the timeliness, continuity and integrity of the ephemeris products to be judged are judged. The timeliness determination includes: obtaining the product reception time and nominal time of the ephemeris product to be determined, calculating the time difference between the product reception time and the nominal time, and determining whether the ephemeris product to be determined meets the timeliness requirements based on the comparison result of the time difference and the preset timeliness threshold. The continuity determination includes: calculating at least one of the epoch missing rate, continuous interruption duration, and number of interruptions of the ephemeris product to be determined within a preset epoch window to obtain a continuity statistical result; comparing the continuity statistical result with the corresponding preset missing rate threshold, preset interruption duration threshold, or preset interruption number threshold; and determining that the ephemeris product to be determined meets the continuity requirement when the continuity statistical result meets the corresponding threshold requirement. The integrity determination includes: determining whether the ephemeris product to be determined meets the integrity requirements based on whether the product message of the currently received ephemeris product to be determined passes the verification, whether the necessary correction fields are complete, and whether the number of available satellites meets the preset minimum calculation requirements; When the ephemeris product to be identified meets the timeliness requirement, the continuity requirement, and the integrity requirement, the ephemeris product to be identified is determined to be usable.

3. The PPP-RTK positioning method for multi-ephemeral availability scenarios according to claim 1, characterized in that, The ephemeris scene processing steps are executed based on the PPP-RTK basic observation model; The PPP-RTK basic observation model is constructed through the following steps: Construct non-differential, non-combined GNSS observation equations based on the raw GNSS observation data; The parameters to be estimated in the non-differential non-combined GNSS observation equations are uniformly modeled and reorganized, and ionospheric constraint information is introduced to obtain the PPP-RTK basic observation model.

4. The PPP-RTK positioning method for multi-ephemeral availability scenarios according to claim 3, characterized in that, When the precise ephemeris is unavailable and the PPP-B2b product is available, a compatible calibration product set compatible with the complete calibration product set is generated, including: The product benchmark used in the PPP-B2b product is incorporated into the PPP-RTK basic observation model; Using the satellite orbit information, satellite clock bias information, and code offset information provided by the PPP-B2b product, the pseudorange observations and carrier phase observations in the raw GNSS observation data are corrected to obtain corrected observations in the PPP-B2b scenario; wherein, the parameters that have been provided by the PPP-B2b product and used for observation correction are no longer used as parameters to be estimated in subsequent calculations. The remaining parameters to be estimated in subsequent calculations are equivalently reorganized; Based on the corrected observations in the PPP-B2b scenario and the remaining parameters to be estimated after equivalent recombination, PPP-RTK calculation is performed to generate the compatible correction product set.

5. The PPP-RTK positioning method for multi-ephemeral availability scenarios according to claim 1, characterized in that, When the precise ephemeris is available, a complete set of calibration products is generated, including: The precise satellite-to-ground distance is calculated based on the precise ephemeris, and the precise satellite-to-ground distance is subtracted from the pseudorange observations and carrier phase observations in the original GNSS observation data to obtain the corrected observations under the precise ephemeris scenario. Based on the orbital difference between the precise satellite orbit provided by the precise ephemeris and the satellite orbit of the broadcast ephemeris at the corresponding time, the satellite orbit correction amount is determined, and satellite orbit correction data is generated based on the satellite orbit correction amount. Based on the corrected observations under the aforementioned precise ephemeris scenario, PPP-RTK calculations are performed to generate satellite clock error correction data, satellite code deviation correction data, satellite phase deviation correction data, ionospheric delay correction data, and tropospheric delay correction data. The complete set of correction products is formed based on the satellite orbit correction data, the satellite clock error correction data, the satellite code deviation correction data, the satellite phase deviation correction data, the ionospheric delay correction data, and the tropospheric delay correction data.

6. The PPP-RTK positioning method for multi-ephemeral availability scenarios according to claim 1, characterized in that, When both the precise ephemeris and the PPP-B2b product are unavailable, a simplified correction product set without independent satellite orbit corrections is generated, including: The approximate satellite-to-ground distance is calculated based on the broadcast ephemeris, and the approximate satellite-to-ground distance is subtracted from the pseudorange observations and carrier phase observations in the original GNSS observation data to obtain the corrected observations under the broadcast ephemeris scenario. The orbital errors caused by insufficient accuracy of broadcast ephemeris orbits are incorporated into the satellite clock error parameters for unified modeling and estimation; Simplified PPP-RTK solution is performed based on the corrected observations under the broadcast ephemeris scenario to generate the simplified correction product set; The simplified correction product set includes satellite clock bias correction data, satellite code bias correction data, satellite phase bias correction data, ionospheric delay correction data, and tropospheric delay correction data.

7. The PPP-RTK positioning method for multi-ephemeral availability scenarios according to claim 1, characterized in that, The solution state includes the state parameters and their covariance information in the PPP-RTK solution; When the ephemeris scene changes, the solution state of the ephemeris scene before the switch is inherited, including: Inherit the state parameters and covariance information corresponding to the ephemeris scene before the switch; Based on the ephemeris scene processing steps switched to, the inherited state parameters and their covariance information are updated so that the positioning solution can continue on the basis of the existing solution state.

8. The PPP-RTK positioning method for multi-ephemeral availability scenarios according to claim 1, characterized in that, The positioning terminal performs positioning calculations based on the calibration product set, including: Parse the received calibration product set and identify the calibration data type and validity status contained in the calibration product set; Based on the completeness and validity of the calibration product set, select the corresponding positioning mode from PPP-RTK, PPP-AR, PPP and SPP positioning modes; When the data type or valid status of the received calibration product set changes, the current calibration information status is updated, and the positioning calculation is performed based on the selected positioning mode without re-initializing the positioning calculation process.

9. A PPP-RTK positioning system for multi-ephemeral availability scenarios, characterized in that, include: The data acquisition unit is used to acquire multi-source ephemeris products and raw GNSS observation data. The multi-source ephemeris products include precise ephemeris, PPP-B2b products, and broadcast ephemeris. The ephemeris discrimination unit is used to determine the availability status of the precise ephemeris and the PPP-B2b product during the operation of the positioning service; The ephemeris scene processing unit is used to execute corresponding ephemeris scene processing steps based on the discrimination result and generate a corresponding correction product set; wherein, the correction product set is one of a complete correction product set, a compatible correction product set, and a simplified correction product set; when the precise ephemeris is available, the complete correction product set is generated; when the precise ephemeris is unavailable but the PPP-B2b product is available, the compatible correction product set compatible with the complete correction product set is generated; when both the precise ephemeris and the PPP-B2b product are unavailable, the simplified correction product set without independent satellite orbit correction is generated based on the broadcast ephemeris; The strategy switching unit is used to switch to the corresponding ephemeris processing step according to the discrimination result when the ephemeris scene changes, and inherit the solution state of the ephemeris scene before the switch. A calibration product output unit is used to output the generated calibration product set to the positioning terminal, so that the positioning terminal performs positioning calculation based on the calibration product set.

10. A PPP-RTK positioning terminal for multi-ephemeral availability scenarios, characterized in that, include: A communication module is used to receive a set of calibration products, which includes a complete set of calibration products generated based on a precise ephemeris, a compatible set of calibration products generated based on a PPP-B2b product, or a simplified set of calibration products generated based on a broadcast ephemeris without independent satellite orbit corrections. The data sensing module is used to parse the calibration product set and identify the calibration data types and valid statuses contained in the calibration product set. The core processing module is used to select the corresponding positioning mode from PPP-RTK, PPP-AR, PPP and SPP positioning modes according to the completeness and validity status of the calibration product set, and perform positioning calculation based on the selected positioning mode; When the set of calibration products changes, the core processing module updates the current calibration information status and performs the positioning calculation without re-initializing the positioning calculation process.

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