A beidou ambiguity fixing detection method, system, product and medium

Abstract

This invention discloses a BeiDou ambiguity fixation detection method and system, belonging to the field of BeiDou satellite navigation and positioning. The method includes: acquiring real-time data streams from a BeiDou reference station for each satellite; calculating the ionospheric delay of each satellite, and selecting multiple sets of overlapping satellites and their corresponding trajectory overlap points, extracting the trajectory overlap point information; performing time compensation on the ionospheric delay of the second satellite in the trajectory overlap point information using a GIM global ionospheric model or a three-dimensional ionospheric model, respectively, to obtain the compensated delay of the second satellite in each overlapping satellite; determining whether the ambiguity fixation of each set of overlapping satellites is correct, and outputting the ambiguity fixation detection result of the BeiDou reference station based on the ambiguity fixation results of each set of overlapping satellites. This invention provides a BeiDou ambiguity fixation detection method and system to solve the technical problem of difficult accurate identification of ambiguity fixation errors in single-station scenarios.

Description

Technical Field

[0001] This invention relates to the field of BeiDou satellite navigation and positioning, and in particular to a BeiDou ambiguity fixation detection method, system, product, and medium. Background Technology

[0002] With the continuous development of BeiDou high-precision positioning technology, its application in surveying, navigation, deformation monitoring and other fields is becoming increasingly widespread. One of the core technologies for achieving high-precision positioning is the correct fixation of integer ambiguity, which aims to ensure the accuracy of ionospheric delay calculation, thereby guaranteeing the accuracy and reliability of the final positioning result.

[0003] Currently, mainstream ambiguity fixation detection methods mainly include those based on single-station residual analysis and those based on multi-station ionospheric continuity. Single-station residual analysis methods rely on the carrier phase residual or pseudorange residual of a single satellite for judgment. This method analyzes the observation residual sequence of a single satellite at a single station and determines whether the ambiguity is correctly fixed based on its statistical characteristics. However, this method only considers the observation quality of a single satellite and does not utilize the spatial correlation between the observation trajectories of different satellites within the same station, resulting in limited detection sensitivity. It is prone to missed or false positives when there is significant observation noise or ionospheric disturbance. Multi-station ionospheric continuity methods utilize regional multi-station observation data and detect ambiguity fixation errors by analyzing the spatial continuity of ionospheric delays. However, they rely on an additional network of reference stations, leading to high costs and complex deployment. Furthermore, they do not fully consider the strong ionospheric correlation characteristics at the intersection points of different satellite trajectories within a single station, resulting in insufficient detection efficiency and specificity. Therefore, the biggest drawback of existing ambiguity fixation detection methods is the low detection accuracy of single-station methods and the high cost of multi-station deployment, making it difficult to achieve high reliability while ensuring economic efficiency. Summary of the Invention

[0004] This invention provides a BeiDou ambiguity fixation detection method, system, product, and medium to solve the technical problem of difficulty in accurately identifying ambiguity fixation errors in single-station scenarios.

[0005] To address the aforementioned technical problems, embodiments of the present invention provide a BeiDou ambiguity fixation detection method, comprising: The system acquires real-time data streams from the BeiDou reference station for each satellite. The real-time data streams include carrier phases for each frequency band and pseudorange observations for each frequency band. The frequency bands include: B1 band, B2 band, and B3 band. Based on the real-time data stream, the ionospheric delay of each satellite is calculated, and multiple sets of overlapping satellites and their corresponding trajectory overlap points are selected. The trajectory overlap point information of each set of overlapping satellites is extracted, wherein the trajectory overlap point information includes: overlapping satellite number, first satellite transit time, first satellite ionospheric delay, second satellite transit time, and second satellite ionospheric delay. Based on the trajectory overlap point information of each group of overlapping satellites, the time compensation of the ionospheric delay of the second satellite in the trajectory overlap point information is performed by using the GIM global ionospheric model or the three-dimensional ionospheric model, respectively, to obtain the compensated delay of the second satellite in each group of overlapping satellites. Based on the ionospheric delay of the first satellite and the compensated delay of the second satellite in each group of overlapping satellites, it is determined whether the ambiguity fixation of each group of overlapping satellites is correct, and the ambiguity fixation detection result of the Beidou reference station is output according to the ambiguity fixation result of each group of overlapping satellites.

[0006] This invention constructs a high-precision single-station ionospheric delay observation sequence by accessing multi-frequency real-time data streams from BeiDou reference stations. By mining and extracting spatial overlap information of different satellite observation trajectories, a strong correlation constraint on ionospheric delay between satellites is established for the first time within a single-station framework. Precise compensation for time differences is performed using the GIM global ionospheric model or a three-dimensional ionospheric model, eliminating the interference of ionospheric time-varying factors on correlation judgment. Finally, the compensated delay is compared using a preset judgment formula, realizing a single-station ambiguity fixation detection method that is independent of multi-station networks and possesses both high precision and high reliability.

[0007] Furthermore, the process of filtering out multiple sets of overlapping satellites and their corresponding trajectory overlap points, and extracting the trajectory overlap point information for each set of overlapping satellites, includes: Based on satellite precise ephemeris or broadcast ephemeris data, the spatial coordinates of each satellite's trajectory are calculated. Iterate through all satellites and combine them in pairs, then filter out overlapping satellites and their corresponding trajectory overlap points based on preset judgment conditions. Based on the overlapping satellites and the trajectory overlap points, the trajectory overlap point information of each group of overlapping satellites is integrated and recorded.

[0008] This clarifies that the determination of the coincidence point depends on the actual observation trajectory coordinates of the satellite, rather than simple epoch alignment, ensuring that the found coincidence points have a high degree of consistency in physical space, and providing a reliable data foundation for subsequent detection based on ionospheric spatial correlation.

[0009] Furthermore, the calculation of the ionospheric delay of each satellite based on the real-time data stream includes: Based on the carrier phase of each frequency band and the pseudorange observations of each frequency band, the estimated ambiguity parameters of each satellite are obtained. Based on the estimated ambiguity parameters of each satellite, the ambiguity parameters are fixed to obtain the integer ambiguity of each satellite. Based on the integer ambiguity and the carrier phase of each frequency band, the ionospheric delay of each satellite is calculated.

[0010] This not only establishes a direct computational link between ambiguity fixation and ionospheric delay, ensuring that the calculation of ionospheric delay relies on fixed high-precision integer ambiguities, but also provides accurate and consistent data input for subsequent ionospheric correlation-based detection, improving the reliability and accuracy of false detection.

[0011] Further, based on the trajectory overlap point information of each group of overlapping satellites, time compensation is performed on the ionospheric delay of the second satellite in the trajectory overlap point information using the GIM global ionospheric model or a three-dimensional ionospheric model to obtain the compensated delay of the second satellite in each group of overlapping satellites, including: The ionospheric delay variation of the second satellite in each group of overlapping satellites is calculated using the GIM global ionospheric model or a three-dimensional ionospheric model. The ionospheric delay variation is caused by the time difference between the transit time of the first satellite and the transit time of the second satellite. When the transit time of the second satellite is greater than that of the first satellite, the ionospheric delay of the second satellite is subtracted from the change in ionospheric delay to obtain the compensated delay of the second satellite.

[0012] By introducing an external high-precision ionospheric model, the difference in ionospheric delay caused by the asynchronous passage of two satellites to the same spatial point is quantified. This compensation operation essentially compares the delay value of the later-arriving satellite with the time of the earlier-arriving satellite, eliminating the major interference factor of ionospheric time-varying characteristics. This allows the difference between the two delay values ​​to purely reflect the impact of systematic errors such as ambiguity fixation errors, greatly improving the accuracy and sensitivity of the detection.

[0013] Further, the calculation of the ionospheric delay change of the second satellite in each group of overlapping satellites using the GIM global ionospheric model or a three-dimensional ionospheric model includes: Based on the latitude and longitude of the reference station, the transit time of the first satellite and the transit time of the second satellite, the zenith ionospheric delay and accuracy information of each group of overlapping satellites are extracted from the GIM global ionospheric model or the three-dimensional ionospheric model at the corresponding time. The zenith ionospheric delay includes the zenith ionospheric delay of the first satellite and the zenith ionospheric delay of the second satellite, and the accuracy information includes the accuracy information of the first satellite and the accuracy information of the second satellite. Based on the trajectory overlap point information, the slant path delay change is calculated using the VMF3 mapping function to obtain the ionospheric delay change of the second satellite in each group of overlapping satellites.

[0014] This refines the calculation process for time compensation. By combining information such as station location and satellite elevation angle, a mapping function is used to convert the zenith delay provided by the model into the slant path delay variation along the actual signal propagation path. This process fully considers the spatial gradient effect of ionospheric delay and satellite observation geometry, making the calculated compensation amount more closely match the actual physical process, resulting in higher compensation accuracy and further reducing the interference of residual errors on the detection results.

[0015] Further, the step of determining whether the ambiguity fixation of each group of overlapping satellites is correct based on the ionospheric delay of the first satellite and the compensated delay of the second satellite in each group of overlapping satellites includes: Iterate through each group of overlapping satellites; When the ionospheric delay of the first satellite and the compensated delay of the second satellite in any group of overlapping satellites do not meet the preset judgment formula, it is determined that two satellites in the group of overlapping satellites have correctly fixed ambiguity. When the ionospheric delay of the first satellite and the post-compensated delay of the second satellite in any group of overlapping satellites satisfy the preset judgment formula, it is determined that two satellites in the group of overlapping satellites have ambiguity fixing errors, and the number of anomaly markers corresponding to the two satellites in the group of overlapping satellites is increased by one.

[0016] By traversing each group of overlapping satellites and marking anomalies one by one based on a preset judgment formula, the system can accumulate ambiguous fixation information point by point and satellite by satellite. Only when a satellite is marked as anomaly at multiple overlapping points is its ambiguous fixation ultimately determined to be incorrect. This effectively avoids the random errors caused by single-point misjudgments, improves the robustness and reliability of the detection results, and forms a progressive judgment logic from single-point comparison to multi-evidence integration.

[0017] Furthermore, the output of the ambiguity fixation detection result of the BeiDou reference station includes: Count the number of anomaly markers for each satellite; Satellites whose number of anomaly markers is greater than or equal to a first preset value are identified as anomalous satellites; The number of anomalous satellites was counted, and the proportion of anomalous satellites to the total number of observed satellites was calculated. If the ratio is greater than the second preset value, it is determined that the current Beidou reference station observation data is abnormal, the current determination process is stopped, and the device is prompted to be checked and the real-time data stream is re-acquired. If the ratio is less than or equal to the second preset value, it is determined that the current Beidou reference station observation data is generally normal, and the determination result of the ambiguity fixation error is valid. Output the ambiguity fixation detection results of the BeiDou reference station.

[0018] This adds a final system-level safety verification and feedback control step. After confirming the ambiguity fixation error of a single satellite through multi-point cross-validation, the system further performs an overall health assessment of all station observation data: by statistically analyzing the proportion of abnormal satellites and comparing it with a preset threshold. When the proportion of erroneous satellites exceeds the limit, the system can automatically identify potential large-scale ionospheric disturbances or equipment failures, and promptly interrupt the process, issue alarms, and guide operators to intervene. This avoids continuing meaningless calculations or outputting misleading conclusions when the data source is unreliable, ensuring the safety and reliability of the system in actual operation, forming a complete detection closed loop.

[0019] Another embodiment of the present invention provides a BeiDou ambiguity fixing detection system, comprising: The data acquisition module is used to acquire real-time data streams from each satellite of the BeiDou reference station. The real-time data streams include carrier phases of each frequency band and pseudorange observations of each frequency band. The frequency bands include: B1 band, B2 band, and B3 band. The overlap point extraction module is used to calculate the ionospheric delay of each satellite based on the real-time data stream, and to filter out multiple sets of overlapping satellites and their corresponding trajectory overlap points, and to extract the trajectory overlap point information of each set of overlapping satellites. The trajectory overlap point information includes: overlapping satellite number, first satellite transit time, first satellite ionospheric delay, second satellite transit time, and second satellite ionospheric delay. The time compensation module is used to compensate for the ionospheric delay of the second satellite in the trajectory overlap point information based on the trajectory overlap point information of each group of overlapping satellites, by using the GIM global ionospheric model or the three-dimensional ionospheric model, to obtain the compensated delay of the second satellite in each group of overlapping satellites. The result determination module is used to determine whether the ambiguity fixation of each group of overlapping satellites is correct based on the first satellite ionospheric delay and the second satellite post-compensation delay of each group of overlapping satellites, and output the ambiguity fixation detection result of the Beidou reference station according to the ambiguity fixation result of each group of overlapping satellites.

[0020] This invention achieves clear decoupling and efficient collaboration in the detection process through modular design. The data acquisition module ensures real-time access to multi-frequency raw observation data; the coincidence point extraction module combines satellite ephemeris with observation delay to accurately capture key nodes constrained by spatial correlation; the time compensation module utilizes an external ionospheric model to intelligently remove time-varying noise, improving data comparability; and the result judgment module integrates hierarchical decision logic to achieve reliable derivation from single-point anomalies to system conclusions. These modules are sequentially connected, forming an automated pipeline from data to decision, enabling the engineered implementation of fixed-ambiguity detection at single stations.

[0021] Furthermore, the overlap point extraction module filters out multiple sets of overlapping satellites and their corresponding trajectory overlap points, and extracts the trajectory overlap point information of each set of overlapping satellites, including: The overlap point extraction module calculates the trajectory spatial coordinates of each satellite based on satellite precise ephemeris or broadcast ephemeris data. Iterate through all satellites and combine them in pairs, then filter out overlapping satellites and their corresponding trajectory overlap points based on preset judgment conditions. Based on the overlapping satellites and the trajectory overlap points, the trajectory overlap point information of each group of overlapping satellites is integrated and recorded.

[0022] This clarifies that the determination of the coincidence point depends on the actual observation trajectory coordinates of the satellite, rather than simple epoch alignment, ensuring that the found coincidence points have a high degree of consistency in physical space, and providing a reliable data foundation for subsequent detection based on ionospheric spatial correlation.

[0023] Furthermore, the overlap point extraction module calculates the ionospheric delay of each satellite based on the real-time data stream, including: The overlap point extraction module obtains an estimate of the ambiguity parameters of each satellite based on the carrier phase of each frequency band and the pseudorange observation value of each frequency band. Based on the estimated ambiguity parameters of each satellite, the ambiguity parameters are fixed to obtain the integer ambiguity of each satellite. Based on the integer ambiguity and the carrier phase of each frequency band, the ionospheric delay of each satellite is calculated.

[0024] This not only establishes a direct computational link between ambiguity fixation and ionospheric delay, ensuring that the calculation of ionospheric delay relies on fixed high-precision integer ambiguities, but also provides accurate and consistent data input for subsequent ionospheric correlation-based detection, improving the reliability and accuracy of false detection.

[0025] Furthermore, the time compensation module, based on the trajectory overlap point information of each group of overlapping satellites, performs time compensation on the ionospheric delay of the second satellite in the trajectory overlap point information using either the GIM global ionospheric model or a three-dimensional ionospheric model, to obtain the compensated delay of the second satellite in each group of overlapping satellites, including: The time compensation module calculates the ionospheric delay change of the second satellite in each group of overlapping satellites using the GIM global ionospheric model or a three-dimensional ionospheric model. The ionospheric delay change is caused by the time difference between the transit time of the first satellite and the transit time of the second satellite. When the transit time of the second satellite is greater than that of the first satellite, the ionospheric delay of the second satellite is subtracted from the change in ionospheric delay to obtain the compensated delay of the second satellite.

[0026] By introducing an external high-precision ionospheric model, the difference in ionospheric delay caused by the asynchronous passage of two satellites to the same spatial point is quantified. This compensation operation essentially compares the delay value of the later-arriving satellite with the time of the earlier-arriving satellite, eliminating the major interference factor of ionospheric time-varying characteristics. This allows the difference between the two delay values ​​to purely reflect the impact of systematic errors such as ambiguity fixation errors, greatly improving the accuracy and sensitivity of the detection.

[0027] Furthermore, the time compensation module calculates the ionospheric delay change of the second satellite in each group of overlapping satellites using the GIM global ionospheric model or a three-dimensional ionospheric model, including: The time compensation module extracts the zenith ionospheric delay and accuracy information for each group of overlapping satellites from the GIM global ionospheric model or three-dimensional ionospheric model based on the latitude and longitude of the reference station, the transit time of the first satellite, and the transit time of the second satellite. The zenith ionospheric delay includes the zenith ionospheric delay of the first satellite and the zenith ionospheric delay of the second satellite, and the accuracy information includes the accuracy information of the first satellite and the accuracy information of the second satellite. Based on the trajectory overlap point information, the slant path delay change is calculated using the VMF3 mapping function to obtain the ionospheric delay change of the second satellite in each group of overlapping satellites.

[0028] This refines the calculation process for time compensation. By combining information such as station location and satellite elevation angle, a mapping function is used to convert the zenith delay provided by the model into the slant path delay variation along the actual signal propagation path. This process fully considers the spatial gradient effect of ionospheric delay and satellite observation geometry, making the calculated compensation amount more closely match the actual physical process, resulting in higher compensation accuracy and further reducing the interference of residual errors on the detection results.

[0029] Furthermore, the result determination module, based on the first satellite ionospheric delay and the compensated delay of the second satellite in each group of overlapping satellites, determines whether the ambiguity fixation of each group of overlapping satellites is correct, including: The result determination module traverses each group of overlapping satellites; When the ionospheric delay of the first satellite and the compensated delay of the second satellite in any group of overlapping satellites do not meet the preset judgment formula, it is determined that two satellites in the group of overlapping satellites have correctly fixed ambiguity. When the ionospheric delay of the first satellite and the post-compensated delay of the second satellite in any group of overlapping satellites satisfy the preset judgment formula, it is determined that two satellites in the group of overlapping satellites have ambiguity fixing errors, and the number of anomaly markers corresponding to the two satellites in the group of overlapping satellites is increased by one.

[0030] By traversing each group of overlapping satellites and marking anomalies one by one based on a preset judgment formula, the system can accumulate ambiguous fixation information point by point and satellite by satellite. Only when a satellite is marked as anomaly at multiple overlapping points is its ambiguous fixation ultimately determined to be incorrect. This effectively avoids the random errors caused by single-point misjudgments, improves the robustness and reliability of the detection results, and forms a progressive judgment logic from single-point comparison to multi-evidence integration.

[0031] Furthermore, the result determination module outputs the ambiguity fixation detection result of the BeiDou reference station, including: The result determination module counts the number of anomaly markers for each satellite; Satellites whose number of anomaly markers is greater than or equal to a first preset value are identified as anomalous satellites; The number of anomalous satellites was counted, and the proportion of anomalous satellites to the total number of observed satellites was calculated. If the ratio is greater than the second preset value, it is determined that the current Beidou reference station observation data is abnormal, the current determination process is stopped, and the device is prompted to be checked and the real-time data stream is re-acquired. If the ratio is less than or equal to the second preset value, it is determined that the current Beidou reference station observation data is generally normal, and the determination result of the ambiguity fixation error is valid. Output the ambiguity fixation detection results of the BeiDou reference station.

[0032] This adds a final system-level safety verification and feedback control step. After confirming the ambiguity fixation error of a single satellite through multi-point cross-validation, the system further performs an overall health assessment of all station observation data: by statistically analyzing the proportion of abnormal satellites and comparing it with a preset threshold. When the proportion of erroneous satellites exceeds the limit, the system can automatically identify potential large-scale ionospheric disturbances or equipment failures, and promptly interrupt the process, issue alarms, and guide operators to intervene. This avoids continuing meaningless calculations or outputting misleading conclusions when the data source is unreliable, ensuring the safety and reliability of the system in actual operation, forming a complete detection closed loop.

[0033] Another embodiment of the present invention also provides a computer program product, including a computer program or instructions, which, when executed by a device, implement the steps of the aforementioned BeiDou ambiguity fixing detection method.

[0034] Another embodiment of the present invention provides a computer-readable storage medium having a computer program stored thereon, wherein the computer program, when executed by a processor, implements the steps of any of the above-described BeiDou ambiguity fixing detection methods. Attached Figure Description

[0035] To more clearly illustrate the technical solution of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0036] Figure 1 This is a flowchart illustrating a BeiDou ambiguity fixing detection method provided in an embodiment of the present invention; Figure 2 This is a schematic diagram illustrating the specific implementation process of a BeiDou ambiguity fixing detection method provided in an embodiment of the present invention; Figure 3 This is a schematic diagram of a BeiDou ambiguity fixing detection device provided in an embodiment of the present invention. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0038] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the invention, are intended to cover non-exclusive inclusion.

[0039] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of the invention. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0040] See Figure 1 To address the technical problem of accurately identifying ambiguity fixation errors in single-site scenarios, an embodiment of the present invention provides a BeiDou ambiguity fixation detection method, comprising: S1, acquire the real-time data stream of each satellite from the Beidou reference station, wherein the real-time data stream includes the carrier phase of each frequency band and the pseudorange observation value of each frequency band, and the frequency bands include: B1 band, B2 band and B3 band.

[0041] The BeiDou reference station continuously collects multi-band observation data for each observable satellite, with each band covering at least the B1, B2, and B3 bands. For each band, it synchronously acquires carrier phase and pseudorange observation values, forming a complete observation sequence containing frequency, phase, and pseudorange information. This data stream is output in real time through the reference station receiver, ensuring the time synchronization and frequency consistency of the observations, providing high-precision, multi-frequency raw input for subsequent ambiguity fixing and ionospheric delay calculation.

[0042] S2, based on the real-time data stream, calculate the ionospheric delay of each satellite, and filter out multiple sets of overlapping satellites and their corresponding trajectory overlap points, extract the trajectory overlap point information of each set of overlapping satellites, wherein the trajectory overlap point information includes: overlapping satellite number, first satellite transit time, first satellite ionospheric delay, second satellite transit time, and second satellite ionospheric delay.

[0043] Among them, after obtaining the real-time data stream, first, based on the carrier phase and pseudorange observations of each frequency band, combined with the fixed integer ambiguity, the real-time ionospheric delay of each satellite is calculated through a dual-frequency or triple-frequency geometry-free combination model. Subsequently, the observation trajectories of each satellite in the station coordinate system are calculated according to the satellite ephemeris. By comparing the elevation angles and azimuth angles of different satellites at the same epoch or adjacent epochs, the trajectory coincidence points within the preset tolerance range are screened out. For each group of coincident satellites, their satellite numbers (S1, S2), the epoch time t1 when the first satellite passes through the coincidence point and the ionospheric delay of the first satellite, the passing time t2 of the second satellite and the ionospheric delay of the second satellite are extracted and recorded, forming a structured information table of trajectory coincidence points, providing a data basis for subsequent time compensation and difference comparison.

[0044] S3. Based on the trajectory coincidence point information of each group of the coincident satellites, the time compensation is respectively performed on the ionospheric delay of the second satellite in the trajectory coincidence point information through the GIM global ionospheric model or the three-dimensional ionospheric model, and the compensated delay of the second satellite in each of the coincident satellites is obtained.

[0045] Among them, for each group of trajectory coincidence point information, first, the passing time difference Δt = t2 - t1 between the second satellite and the first satellite is calculated. Subsequently, based on the GIM global ionospheric model or the three-dimensional ionospheric model, according to the station longitude and latitude and the times t1 and t2, the zenith direction ionospheric delay and its accuracy information are obtained, and combined with the elevation angle of the satellite at the coincidence point, it is converted into the slant path ionospheric delay through a mapping function such as VMF3. The change amount ΔI of the slant path ionospheric delay caused by Δt is calculated by using this model, and the time compensation is performed on the ionospheric delay of the second satellite: if t2 > t1, the compensated delay is calculated by subtracting the change amount of the slant path ionospheric delay from the ionospheric delay of the second satellite; if t2 < t1, the compensation logic is adjusted accordingly. The purpose of compensation is to eliminate the ionospheric time-varying influence caused by different observation times, making the ionospheric delays of the two satellites at the trajectory coincidence point directly comparable.

[0046] S4. Based on the ionospheric delay of the first satellite and the compensated delay of the second satellite of each group of the coincident satellites, it is respectively judged whether the ambiguity fixing of each group of the coincident satellites is correct, and according to the ambiguity fixing results of each group of the coincident satellites, the ambiguity fixing detection result of the Beidou reference station is output.

[0047] For each group of overlapping satellites, a judgment formula is used to determine whether the ambiguity fixation of the two satellites at the current overlap point is correct. If it is determined to be incorrect, the overlap point is marked as abnormal. Subsequently, the number of times each satellite is marked as abnormal across all overlap points is counted. If the number of abnormal overlap points for a satellite reaches or exceeds a preset threshold (the first preset value), the integer ambiguity fixation of that satellite is determined to be incorrect. Finally, the judgment results of all satellites are summarized. If the proportion of erroneous satellites to the total number of observed satellites does not exceed a set threshold (the second preset value), the current ambiguity fixation detection result of the BeiDou reference station is output as "normal"; otherwise, "data abnormal" is output, and a prompt is made to check the observation equipment or re-acquire data.

[0048] Furthermore, such as Figure 2 As shown, this application provides a specific implementation process for a BeiDou ambiguity fixing detection method. First, the real-time data stream from the BeiDou reference station is accessed to obtain multi-frequency carrier observations and pseudorange observations of all tracked BeiDou satellites. Based on the real-time data from the reference station, the integer ambiguity of all satellites is calculated and fixed. Then, the real-time ionospheric delay of each satellite is calculated using the fixed integer ambiguity and carrier phase observations. Next, the spatial coordinates of the observation trajectories of each satellite are calculated, and trajectory overlap points are selected. The satellite numbers, path times, and respective ionospheric delays corresponding to the overlap points are extracted. Then, time compensation is performed on the satellite delays at subsequent path overlap points. The change in ionospheric delay caused by the time difference is calculated using a global ionospheric model or a three-dimensional ionospheric model to eliminate the influence of dynamic ionospheric changes. Finally, the compensated delay is compared with the satellite delay at the first overlapping point to determine whether the ambiguity fixation is correct. If the difference exceeds the test threshold based on historical data statistics, the satellite's performance at other overlapping points is combined to determine that its integer ambiguity fixation is incorrect. The proportion of incorrect satellites is used to determine whether the observation data is abnormal, thus completing the detection of the correctness of ambiguity fixation in BeiDou high-precision positioning.

[0049] In one embodiment, multiple sets of overlapping satellites and their corresponding trajectory overlap points are selected, and the trajectory overlap point information of each set of overlapping satellites is extracted, including steps S201 to S203, each step of which is as follows: S201 calculates the spatial coordinates of each satellite's trajectory based on precise satellite ephemeris or broadcast ephemeris data.

[0050] Based on precise or broadcast ephemeris data from satellites, the orbital parameters in the ephemeris, such as Keplerian orbital elements or position and velocity vectors, are analyzed. Combined with time interpolation methods, the three-dimensional spatial coordinates (X, Y, Z) of each satellite at the corresponding epoch in the geocentric-ground coordinate system are calculated. Furthermore, the satellite coordinates are transformed to a station-centered coordinate system, thereby obtaining the real-time azimuth and elevation angles of each satellite relative to the station. This forms a continuous spatial coordinate sequence of its trajectory within the observation period, providing a geometric basis for subsequently identifying spatial overlap points between different satellite trajectories.

[0051] S202, traverse all satellites and combine them in pairs, and filter out overlapping satellites and their corresponding trajectory overlap points based on preset judgment conditions.

[0052] This process involves iterating through all observed satellites, pairing them up, and comparing the trajectory sequences of each pair within the same time period. Based on preset criteria, epochs that meet the criteria are selected as trajectory overlap points. The criteria are as follows: In the formula, , , respectively, represent the elevation angle and azimuth angle of satellite i observed from station A, and j represents the overlapping satellite.

[0053] Each coincidence point corresponds to a set of coincident satellites, including the first satellite S1 and the second satellite S2. The time of passage, azimuth angle, elevation angle and corresponding ionospheric delay of the two satellites at the point are recorded to form a set of coincidence points that can be used for subsequent correlation analysis.

[0054] S203, Based on the overlapping satellites and the trajectory overlap points, integrate and record the trajectory overlap point information of each group of overlapping satellites.

[0055] For each selected group of overlapping satellites (S1, S2) and its corresponding trajectory overlap point, the following information is integrated and recorded to form a structured trajectory overlap point information entry: overlapping satellite number, first satellite transit time t1, and first satellite ionospheric delay. The transit time t2 of the second satellite and the ionospheric delay of the second satellite All entries are organized into lists or tables according to satellite combinations and time sequence, forming a complete set of trajectory overlap point information, providing unified and clear data input for subsequent time compensation and difference comparison.

[0056] This embodiment first calculates the spatial coordinates of each satellite's trajectory using precise or broadcast ephemeris data, providing an accurate geometric basis for subsequent overlap point determination and ensuring the spatial rigor of the detection method. Second, by systematically traversing and comparing all satellite combinations pairwise, and filtering based on azimuth and elevation angle tolerance thresholds, it can automatically and reliably identify satellite pairs with spatial trajectory overlap characteristics and their corresponding epochs. This avoids the subjectivity and oversight of manual screening, improving the automation and repeatability of the detection. Finally, through structured information integration and recording, a clear and complete trajectory overlap point information table is formed, providing unified and standardized data input for subsequent time compensation, difference comparison, and multiple overlap point cross-validation. This enhances the systematic nature, traceability, and overall reliability of the entire ambiguity fixation error detection process.

[0057] In one embodiment, the ionospheric delay of each satellite is calculated based on the real-time data stream, including steps S301 to S303, each step of which is as follows: S301, Based on the carrier phase of each frequency band and the pseudorange observation value of each frequency band, the estimated ambiguity parameters of each satellite are obtained.

[0058] Based on carrier phase and pseudorange observations for each frequency band, observation equations are constructed using double-difference or non-difference observation models. Parameter estimation methods such as least squares and Kalman filtering are then used to calculate the floating-point solutions of ambiguity parameters for each satellite in real time. Furthermore, Lambda or other integer ambiguity search algorithms are employed to constrain and fix the floating-point solutions with integers, ultimately obtaining fixed integer ambiguity values ​​for each satellite in each frequency band. These values ​​serve as necessary inputs for subsequent high-precision ionospheric delay calculations.

[0059] S302, Based on the estimated ambiguity parameters of each satellite, the ambiguity parameters are fixed to obtain the integer ambiguity of each satellite.

[0060] Based on the floating-point estimates of the ambiguity parameters of each satellite and their variance-covariance matrix, an integer least squares search method, such as the Lambda algorithm, is used to search for and fix the optimal integer ambiguity combination within the integer domain. The reliability of the fixing results is verified using methods such as ratio testing. If the test passes, the corresponding fixed integer ambiguity value is determined as the final integer ambiguity for that satellite; if the test fails, the floating-point solution is retained or re-initialized. The fixed integer ambiguities serve as accurate known quantities for the subsequent ionospheric delay calculation of carrier phase observations, ensuring the accuracy of ionospheric delay calculation and the reliability of ambiguity error detection.

[0061] S303, based on the integer ambiguity and the carrier phase of each frequency band, the ionospheric delay of each satellite is calculated.

[0062] After obtaining the fixed integer ambiguity for each satellite, the ionospheric delay of each satellite is calculated using dual-frequency (e.g., B1, B2) or triple-frequency (B1, B2, B3) carrier phase observations. Taking dual-frequency as an example, the millimeter-precision ionospheric delay of satellite i at station A is calculated. The calculation formula is as follows: In the formula, , The frequencies of observations B1 and B2, , The wavelengths of observations B1 and B2 are... , The integer ambiguity of satellite B1 and B2 observations at station A. , These are the carrier observation values ​​for frequency points B1 and B2 of satellite i at station A.

[0063] This process relies on the correctness of the fixed ambiguity, which is a key input for subsequent ambiguity error detection based on trajectory overlap points.

[0064] This embodiment comprehensively utilizes carrier phase and pseudorange observations from multiple frequency bands to estimate ambiguity parameters, providing a high-precision, multi-frequency floating-point solution foundation for subsequent integer ambiguity fixing, thus enhancing the robustness and convergence speed of ambiguity resolution. Secondly, based on algorithms such as Lambda, rigorous integer fixing and verification of ambiguity parameters are performed to ensure accurate and reliable integer ambiguity, a crucial prerequisite for achieving millimeter-level ionospheric delay calculation. Finally, using the fixed integer ambiguity and the original carrier phase observations, the ionospheric delay of each satellite is calculated, ensuring that the calculation results accurately reflect the ionospheric information determined by the ambiguity fixing quality. This provides high-precision, high-reliability input data for subsequent correlation detection based on trajectory coincidence points, thereby guaranteeing the accuracy and effectiveness of ambiguity error detection from the source.

[0065] In one embodiment, based on the trajectory overlap point information of each group of overlapping satellites, time compensation is performed on the ionospheric delay of the second satellite in the trajectory overlap point information using the GIM global ionospheric model or a three-dimensional ionospheric model to obtain the compensated delay of the second satellite in each group of overlapping satellites, including steps S401 to S402, each step as follows: S401, the ionospheric delay change of the second satellite in each group of overlapping satellites is calculated using the GIM global ionospheric model or a three-dimensional ionospheric model, wherein the ionospheric delay change is caused by the time difference between the transit time of the first satellite and the transit time of the second satellite.

[0066] Specifically, based on the GIM global ionospheric model or three-dimensional ionospheric model, combined with the geographical coordinates of the station and the passing times t1 and t2 of the first and second satellites at the point of overlap, the change in ionospheric delay ΔI in this direction within the time difference Δt from t1 to t2 is calculated to characterize the delay difference caused by the time-varying characteristics of the ionosphere, providing a quantitative correction for subsequent time compensation of the delay of the second satellite.

[0067] S402, when the transit time of the second satellite is greater than the transit time of the first satellite, the ionospheric delay of the second satellite is subtracted from the change in ionospheric delay to obtain the compensated delay of the second satellite.

[0068] If the transit time t2 of the second satellite is greater than the transit time t1 of the first satellite, it indicates that the observation by the second satellite occurred at a later time when the ionospheric state may have changed. In this case, the change in ionospheric delay ΔI caused by the time difference Δt, calculated from the GIM or the three-dimensional ionospheric model, is subtracted from the ionospheric delay of the second satellite, i.e., compensation calculation is performed. In the formula, ΔI represents the ionospheric delay at time t2 for the second satellite, and ΔI is the change in ionospheric delay.

[0069] This operation aims to eliminate the time-varying differences in the ionosphere introduced by the observation time lag, so that the compensated delay is approximately equivalent to the ionospheric delay that the second satellite should exhibit if it observes at time t1, thereby ensuring that its delay is comparable to that of the first satellite under the same ionospheric conditions.

[0070] This embodiment, by introducing the GIM global ionospheric model or a three-dimensional ionospheric model, can accurately quantify the change in ionospheric delay caused by the time difference between the points where the two satellites' trajectories overlap. This effectively eliminates the influence of the time-varying characteristics of the ionosphere on delay correlation, thus significantly improving the comparability between observations at different times. Secondly, for cases where the second satellite's observation time is later, compensation is made by subtracting this change from the actual ionospheric delay, so that the compensated delay approximately restores the state at the same observation time as the first satellite, eliminating the systematic bias introduced by time lag. This compensation mechanism ensures that the ionospheric delays of the two satellites at their trajectory overlap points can be directly and fairly compared under the same ionospheric benchmark, significantly improving the accuracy and reliability of ambiguity fixation based on delay consistency judgments, and effectively reducing the risk of misjudgment and missed detection caused by dynamic changes in the ionosphere.

[0071] In one embodiment, the ionospheric delay variation of the second satellite in each group of overlapping satellites is calculated using the GIM global ionospheric model or a three-dimensional ionospheric model, including steps S501 to S502, each step of which is as follows: S501, based on the latitude and longitude of the reference station, the transit time of the first satellite and the transit time of the second satellite, extract the zenith ionospheric delay and accuracy information of the corresponding time for each group of overlapping satellites from the GIM global ionospheric model or the three-dimensional ionospheric model, wherein the zenith ionospheric delay includes the zenith ionospheric delay of the first satellite and the zenith ionospheric delay of the second satellite, and the accuracy information includes the accuracy information of the first satellite and the accuracy information of the second satellite.

[0072] Specifically, based on the precise latitude and longitude coordinates of the base station, and combining the transit times t1 and t2 of the first and second satellites in each group of overlapping satellites, the GIM global ionospheric model or the three-dimensional ionospheric model is queried. The zenith ionospheric delay corresponding to the station's location at time t1 is then extracted from the model. and its accuracy indicators (First satellite accuracy information), and zenith ionospheric delay at time t2. and its accuracy indicators (Second satellite accuracy information). These extracted zenith delay values ​​and accuracy information provide the basic input data for subsequent mapping of zenith delay to satellite slant paths and calculation of the ionospheric delay variation and its uncertainty caused by time differences.

[0073] S502, based on the trajectory overlap point information, the slant path delay change is calculated using the VMF3 mapping function to obtain the ionospheric delay change of the second satellite in each group of overlapping satellites.

[0074] Based on the satellite elevation angle recorded in the trajectory coincidence point information and the corresponding zenith ionospheric delay extracted from the GIM model, the VMF3 mapping function is used to calculate the slant path ionospheric delay changes of the first satellite at time t1 and the second satellite at time t2, respectively. The calculation formula is as follows: In the formula, This represents the ionospheric delay variation along the oblique path. The VMF3 mapping function value is derived from the satellite elevation angle. Calculations show that , These are the elevation angles when the first satellite passes through the point of coincidence and the elevation angles when the second satellite passes through the point of coincidence, respectively.

[0075] This change is directly used to compensate for the time delay of the second satellite's ionosphere, in order to eliminate the differences in ionospheric state caused by different observation times.

[0076] This embodiment extracts the zenith ionospheric delay and its accuracy information from the GIM or 3D ionospheric model based on the precise location of the base station and the respective transit times of the two satellites. This provides a spatiotemporally matched and accuracy-traceable model input for calculating the delay variation, enhancing the accuracy and reliability of the calculation. Secondly, using precise mapping functions such as VMF3, combined with the actual observed elevation angle information at the trajectory overlap point, the zenith delay is accurately converted into the slant path delay along the satellite's line-of-sight, thus realistically reflecting the ionospheric influence along the signal propagation path. By calculating the change in slant path delay between the two moments, this step achieves accurate modeling and quantification of the ionospheric time-varying effect, ensuring that the calculation of the time compensation amount conforms to both the spatial distribution characteristics of the ionosphere and the actual observed geometry, thereby effectively improving the accuracy and robustness of subsequent delay comparison and ambiguity error detection.

[0077] In one embodiment, based on the ionospheric delay of the first satellite and the compensated delay of the second satellite in each group of overlapping satellites, it is determined whether the ambiguity fixation of each group of overlapping satellites is correct, including steps S601 to S603, each step being as follows: S601, traverse the overlapping satellites in each group.

[0078] This traversal operation ensures that every pair of satellites with overlapping spatial trajectories is included in the detection process, evaluating all relevant information that may reflect the fixed quality of ambiguity without omission, and providing a complete and systematic data foundation for subsequent comprehensive statistics and judgment based on multiple sets of results.

[0079] S602, when the ionospheric delay of the first satellite and the compensated delay of the second satellite in any group of overlapping satellites do not meet the preset judgment formula, it is determined that two satellites in the group of overlapping satellites have correct ambiguity fixation.

[0080] For any group of overlapping satellites, if the absolute difference between the ionospheric delay of the first satellite and the compensated delay of the second satellite does not meet the conditions set by the preset judgment formula, it indicates that the ionospheric delays of the two satellites at the trajectory overlap point are highly consistent, which is in line with the expectation of strong ionospheric correlation. Therefore, it can be determined that the ambiguity fixation results for the two satellites in this group at the current overlap point are correct. The judgment formula is as follows: In the formula, This is the oblique path ionospheric delay variation, which is the accuracy information of the oblique path delay variation extracted from the GIM model.

[0081] This judgment supports the identification of each satellite as a normal satellite in subsequent multi-point statistics, thereby timely confirming and retaining the correct ambiguity fixation results during the detection process, and avoiding unnecessary suspicion or duplicate processing of normal satellites.

[0082] S603, when the ionospheric delay of the first satellite and the post-compensation delay of the second satellite in any group of overlapping satellites satisfy the preset judgment formula, it is determined that two satellites in the group of overlapping satellites have ambiguity fixing errors, and the number of anomaly markers corresponding to the two satellites in the group of overlapping satellites is increased by one.

[0083] In this study, for any group of overlapping satellites, if the absolute difference between the ionospheric delay of the first satellite and the compensated delay of the second satellite meets the conditions set by the preset judgment formula, it indicates that there is a significant inconsistency in the ionospheric delay of the two satellites at the trajectory overlap point, violating the expectation of strong ionospheric correlation. Based on this, it is inferred that at least one satellite in the group has a fixed ambiguity error. In this case, both satellites in the group are marked as anomalous at the current overlap point, and the anomalous marking count for each satellite is increased by one. This operation provides crucial counting basis for subsequent statistical determination of which specific satellite has a systematic error based on multiple overlap points.

[0084] This embodiment systematically traverses each group of overlapping satellites and compares them one by one, ensuring that all potential ambiguity fixation anomalies are included in the detection scope, avoiding omissions and improving the comprehensiveness of the detection. Secondly, it objectively judges delay differences based on a preset judgment formula, providing a clear correct or incorrect conclusion for each pair of satellites, with clear logic and easy automation. Most importantly, this method not only marks anomalies and accumulates the number of anomalies for the corresponding satellites when the judgment is incorrect, laying the foundation for subsequent statistical judgment based on multiple merging points; but also explicitly confirms the correctness when the judgment is correct. This helps maintain the credible state of normal satellites and avoids unnecessary subsequent processing of normal satellites due to single-point misjudgments. Overall, this step constructs refined and structured preliminary judgment results in a group-by-group and point-by-point manner, providing accurate and complete input data for the subsequent highly reliable final judgment based on multiple merging point statistics, thereby enhancing the rigor and reliability of the entire ambiguity fixation detection process.

[0085] In one embodiment, the ambiguity fixation detection result of the BeiDou reference station is output, including steps S701 to S706, each step of which is as follows: S701, count the number of anomaly markers for each satellite.

[0086] Among them, the number of times anomaly markers are counted for each satellite reflects the frequency of consistency anomalies when each satellite is compared with different paired satellites at multiple independent trajectory overlap points. It is the core quantitative indicator for identifying satellites that may have systematic ambiguity fixed errors, and provides a direct basis for subsequent final judgment through preset thresholds.

[0087] S702, satellites whose number of abnormal markers is greater than or equal to a first preset value are determined to be abnormal satellites.

[0088] The process compares the number of anomaly markers for each satellite with a preset value (e.g., 3). If the number of anomaly markers for a satellite is greater than or equal to this preset value, the satellite is considered an anomalous. This criterion is based on statistical principles, arguing that if a single satellite exhibits anomalies at multiple independent points of overlap, it indicates that its ambiguity fixation error is systematic and repetitive, rather than a random error. By setting this threshold, sporadic anomalies caused by accidental observation noise or local disturbances can be effectively filtered out, ensuring that the ultimately identified anomalous satellites do indeed have a high probability of ambiguity fixation problems, thereby improving the accuracy and reliability of error detection conclusions.

[0089] S703, count the number of abnormal satellites and calculate the proportion of abnormal satellites to the total number of observed satellites.

[0090] Among them, based on the statistically obtained number of abnormal satellites (denoted as N_error) and the total number of satellites currently observed by the BeiDou reference station (denoted as N_total), the proportion R of ambiguity-fixed error satellites is calculated according to the following formula: R = (N_error / N_total) × 100% The ratio R directly reflects the breadth of systematic errors in ambiguity fixation within the current observation dataset. A higher R value indicates that more satellites are affected, and the overall observation quality or ambiguity fixation reliability is more likely to be problematic; a lower R value indicates that the error is limited to only a few satellites, and the overall observation and fixation results remain basically reliable. This ratio is a key quantitative indicator for subsequently judging the overall data status of the base station and outputting the final detection conclusion.

[0091] S704, if the ratio is greater than the second preset value, it is determined that the current Beidou reference station observation data is abnormal, the current determination process is stopped, and the device is prompted to be checked and the real-time data stream is re-acquired.

[0092] If the calculated proportion R is greater than a second preset value (e.g., 20%), the overall observation data of the current BeiDou reference station is determined to be in an abnormal state. This situation indicates that the ambiguity fixing error is not an isolated phenomenon, but may originate from systemic factors such as large-scale signal anomalies, receiver malfunctions, severe ionospheric disturbances, or environmental interference. In this case, the current ambiguity fixing detection process is immediately stopped, a warning message indicating that the overall observation data is abnormal is output, and the operator is prompted to check the status of the receiving equipment, antenna connections, and observation environment. If necessary, the data acquisition process should be restarted to obtain a usable real-time data stream, thereby avoiding the failure of positioning results due to continued processing based on erroneous data.

[0093] S705, if the ratio is less than or equal to the second preset value, it is determined that the current Beidou reference station observation data is generally normal, and the determination result of the ambiguity fixation error is valid.

[0094] If the calculated proportion R is less than or equal to a second preset value (e.g., 20%), the overall BeiDou reference station observation data is considered to be in a normal state. This result indicates that although there may be individual satellite ambiguity fixing errors, the number of erroneous satellites is not significant, and the overall observation data quality and ambiguity fixing reliability still meet expectations. In this case, the judgment result of the current ambiguity fixing detection process remains valid, that is, it clearly identifies which specific satellites have ambiguity fixing errors and outputs a final valid detection result report, providing a reliable basis for data quality judgment and erroneous satellite exclusion for subsequent high-precision positioning calculations.

[0095] S706, output the ambiguity fixation detection result of the Beidou reference station.

[0096] The system outputs the ambiguity fixation detection results of the BeiDou reference station, specifically including: the current detection epoch, the total number of observed satellites, a list of satellite numbers identified as having ambiguity fixation errors and their abnormal overlap point statistics, the overall proportion of erroneous satellites (R), and the final data status conclusion derived from comparing R with a preset threshold, i.e., whether the data is normal or abnormal. If the status is normal, a list of reliable satellites that can be used for subsequent positioning calculations is also output; if the status is abnormal, an additional prompt message is provided, suggesting checking the equipment or re-collecting data. This result is presented in a structured report format, supporting log recording and real-time monitoring, providing a clear basis for data quality control and fault diagnosis in high-precision positioning systems.

[0097] This embodiment effectively distinguishes between random errors and systematic ambiguity fixation errors by statistically analyzing the number of anomaly markers for each satellite at multiple overlapping points and setting a first preset value as a judgment threshold, significantly improving the accuracy and robustness of identifying problematic satellites. Secondly, it further calculates the proportion of anomalous satellites to the total number of satellites and uses a second preset value as a criterion for overall data quality evaluation, realizing a complete link from single-satellite error detection to assessment of the overall observation status of the base station. This method can promptly terminate the process and issue a clear alarm when the proportion exceeds the limit, effectively preventing the continued use of erroneous information when data quality is unreliable; while when the proportion is normal, it confirms the validity of the detection results, ensuring the output of credible conclusions. The final structured detection results integrate satellite-level anomaly details and station-level quality status, providing a comprehensive, reliable, and operable decision-making basis for real-time quality control, fault diagnosis, and maintenance response of high-precision positioning systems, thereby enhancing the practical value and system reliability of the entire detection method.

[0098] Based on the same inventive concept, this application also provides a system for implementing the aforementioned BeiDou ambiguity fixing detection system. The solution provided by this system is similar to the solution described in the above method; therefore, the specific limitations in one or more BeiDou ambiguity fixing detection device embodiments provided below can be found in the limitations of the BeiDou ambiguity fixing detection method described above, and will not be repeated here.

[0099] In one exemplary embodiment, such as Figure 3 As shown, a BeiDou ambiguity fixation detection system is provided, including: The data acquisition module 801 is used to acquire real-time data streams from each satellite of the Beidou reference station. The real-time data streams include carrier phases of each frequency band and pseudorange observations of each frequency band. The frequency bands include: B1 band, B2 band, and B3 band. The overlap point extraction module 802 is used to calculate the ionospheric delay of each satellite based on the real-time data stream, and to filter out multiple sets of overlapping satellites and their corresponding trajectory overlap points, and to extract the trajectory overlap point information of each set of overlapping satellites. The trajectory overlap point information includes: overlapping satellite number, first satellite transit time, first satellite ionospheric delay, second satellite transit time, and second satellite ionospheric delay. The time compensation module 803 is used to compensate for the ionospheric delay of the second satellite in the trajectory overlap point information based on the trajectory overlap point information of each group of overlapping satellites, by using the GIM global ionospheric model or the three-dimensional ionospheric model, to obtain the compensated delay of the second satellite in each group of overlapping satellites. The result determination module 804 is used to determine whether the ambiguity fixation of each group of overlapping satellites is correct based on the first satellite ionospheric delay and the second satellite post-compensation delay of each group of overlapping satellites, and output the ambiguity fixation detection result of the Beidou reference station according to the ambiguity fixation result of each group of overlapping satellites.

[0100] This invention achieves clear decoupling and efficient collaboration in the detection process through modular design. The data acquisition module ensures real-time access to multi-frequency raw observation data; the coincidence point extraction module combines satellite ephemeris with observation delay to accurately capture key nodes constrained by spatial correlation; the time compensation module utilizes an external ionospheric model to intelligently remove time-varying noise, improving data comparability; and the result judgment module integrates hierarchical decision logic to achieve reliable derivation from single-point anomalies to system conclusions. These modules are sequentially connected, forming an automated pipeline from data to decision, enabling the engineered implementation of fixed-ambiguity detection at single stations.

[0101] Furthermore, the overlap point extraction module 802 filters out multiple sets of overlapping satellites and their corresponding trajectory overlap points, and extracts the trajectory overlap point information of each set of overlapping satellites, including: The overlap point extraction module 802 calculates the trajectory spatial coordinates of each satellite based on the satellite's precise ephemeris or broadcast ephemeris data. Iterate through all satellites and combine them in pairs, then filter out overlapping satellites and their corresponding trajectory overlap points based on preset judgment conditions. Based on the overlapping satellites and the trajectory overlap points, the trajectory overlap point information of each group of overlapping satellites is integrated and recorded.

[0102] This clarifies that the determination of the coincidence point depends on the actual observation trajectory coordinates of the satellite, rather than simple epoch alignment, ensuring that the found coincidence points have a high degree of consistency in physical space, and providing a reliable data foundation for subsequent detection based on ionospheric spatial correlation.

[0103] Furthermore, the overlap point extraction module 802 calculates the ionospheric delay of each satellite based on the real-time data stream, including: The overlap point extraction module 802 obtains the estimated ambiguity parameters of each satellite based on the carrier phase of each frequency band and the pseudorange observation value of each frequency band. Based on the estimated ambiguity parameters of each satellite, the ambiguity parameters are fixed to obtain the integer ambiguity of each satellite. Based on the integer ambiguity and the carrier phase of each frequency band, the ionospheric delay of each satellite is calculated.

[0104] This not only establishes a direct computational link between ambiguity fixation and ionospheric delay, ensuring that the calculation of ionospheric delay relies on fixed high-precision integer ambiguities, but also provides accurate and consistent data input for subsequent ionospheric correlation-based detection, improving the reliability and accuracy of false detection.

[0105] Further, the time compensation module 803, based on the trajectory overlap point information of each group of overlapping satellites, performs time compensation on the ionospheric delay of the second satellite in the trajectory overlap point information using the GIM global ionospheric model or a three-dimensional ionospheric model, respectively, to obtain the compensated delay of the second satellite in each group of overlapping satellites, including: The time compensation module 803 calculates the ionospheric delay change of the second satellite in each group of overlapping satellites using the GIM global ionospheric model or a three-dimensional ionospheric model. The ionospheric delay change is caused by the time difference between the transit time of the first satellite and the transit time of the second satellite. When the transit time of the second satellite is greater than that of the first satellite, the ionospheric delay of the second satellite is subtracted from the change in ionospheric delay to obtain the compensated delay of the second satellite.

[0106] By introducing an external high-precision ionospheric model, the difference in ionospheric delay caused by the asynchronous passage of two satellites to the same spatial point is quantified. This compensation operation essentially compares the delay value of the later-arriving satellite with the time of the earlier-arriving satellite, eliminating the major interference factor of ionospheric time-varying characteristics. This allows the difference between the two delay values ​​to purely reflect the impact of systematic errors such as ambiguity fixation errors, greatly improving the accuracy and sensitivity of the detection.

[0107] Furthermore, the time compensation module 803 calculates the ionospheric delay change of the second satellite in each group of overlapping satellites using the GIM global ionospheric model or a three-dimensional ionospheric model, including: The time compensation module 803 extracts the zenith ionospheric delay and accuracy information for each group of overlapping satellites from the GIM global ionospheric model or three-dimensional ionospheric model based on the latitude and longitude of the reference station, the transit time of the first satellite, and the transit time of the second satellite. The zenith ionospheric delay includes the zenith ionospheric delay of the first satellite and the zenith ionospheric delay of the second satellite, and the accuracy information includes the accuracy information of the first satellite and the accuracy information of the second satellite. Based on the trajectory overlap point information, the slant path delay change is calculated using the VMF3 mapping function to obtain the ionospheric delay change of the second satellite in each group of overlapping satellites.

[0108] This refines the calculation process for time compensation. By combining information such as station location and satellite elevation angle, a mapping function is used to convert the zenith delay provided by the model into the slant path delay variation along the actual signal propagation path. This process fully considers the spatial gradient effect of ionospheric delay and satellite observation geometry, making the calculated compensation amount more closely match the actual physical process, resulting in higher compensation accuracy and further reducing the interference of residual errors on the detection results.

[0109] Furthermore, the result determination module 804, based on the first satellite ionospheric delay and the compensated delay of the second satellite in each group of overlapping satellites, determines whether the ambiguity fixation of each group of overlapping satellites is correct, including: The result determination module 804 traverses each group of overlapping satellites; When the ionospheric delay of the first satellite and the compensated delay of the second satellite in any group of overlapping satellites do not meet the preset judgment formula, it is determined that two satellites in the group of overlapping satellites have correctly fixed ambiguity. When the ionospheric delay of the first satellite and the post-compensated delay of the second satellite in any group of overlapping satellites satisfy the preset judgment formula, it is determined that two satellites in the group of overlapping satellites have ambiguity fixing errors, and the number of anomaly markers corresponding to the two satellites in the group of overlapping satellites is increased by one.

[0110] By traversing each group of overlapping satellites and marking anomalies one by one based on a preset judgment formula, the system can accumulate ambiguous fixation information point by point and satellite by satellite. Only when a satellite is marked as anomaly at multiple overlapping points is its ambiguous fixation ultimately determined to be incorrect. This effectively avoids the random errors caused by single-point misjudgments, improves the robustness and reliability of the detection results, and forms a progressive judgment logic from single-point comparison to multi-evidence integration.

[0111] Furthermore, the result determination module 804 outputs the ambiguity fixation detection result of the BeiDou reference station, including: The result determination module 804 counts the number of anomaly markers for each satellite; Satellites whose number of anomaly markers is greater than or equal to a first preset value are identified as anomalous satellites; The number of anomalous satellites was counted, and the proportion of anomalous satellites to the total number of observed satellites was calculated. If the ratio is greater than the second preset value, it is determined that the current Beidou reference station observation data is abnormal, the current determination process is stopped, and the device is prompted to be checked and the real-time data stream is re-acquired. If the ratio is less than or equal to the second preset value, it is determined that the current Beidou reference station observation data is generally normal, and the determination result of the ambiguity fixation error is valid. Output the ambiguity fixation detection results of the BeiDou reference station.

[0112] This adds a final system-level safety verification and feedback control step. After confirming the ambiguity fixation error of a single satellite through multi-point cross-validation, the system further performs an overall health assessment of all station observation data: by statistically analyzing the proportion of abnormal satellites and comparing it with a preset threshold. When the proportion of erroneous satellites exceeds the limit, the system can automatically identify potential large-scale ionospheric disturbances or equipment failures, and promptly interrupt the process, issue alarms, and guide operators to intervene. This avoids continuing meaningless calculations or outputting misleading conclusions when the data source is unreliable, ensuring the safety and reliability of the system in actual operation, forming a complete detection closed loop.

[0113] In one embodiment, a computer program product is provided, including a computer program or instructions, which, when executed by a device, implement the steps of the aforementioned BeiDou ambiguity fixing detection method.

[0114] In one embodiment, a computer-readable storage medium is provided having a computer program stored thereon, which, when executed by a processor, implements the steps in the above method embodiments.

[0115] This technical solution deeply integrates the strong correlation of ionospheric delay at the coincidence points of BeiDou satellite trajectories with a global ionospheric model to construct a method for detecting ambiguity fixation errors based on single-station observation data. Its core advantage lies in overcoming the limitations of traditional methods that rely on single-satellite residual analysis or multi-station network deployment. It achieves efficient and accurate verification of ambiguity fixation correctness in a single-station scenario. Users can actively identify and locate satellites with ambiguity fixation errors by comparing the ionospheric delays of different satellites at the trajectory coincidence points in real time, combined with time difference compensation and multi-point cross-verification. This provides a reliable error detection mechanism for BeiDou high-precision positioning, achieving a leap from independent single-satellite judgment to multi-satellite collaborative verification. Simultaneously, this solution fully leverages the respective advantages of single-station observation in cost control, the physical consistency of satellite trajectory spatial correlation, and the time-varying compensation of the ionospheric model, addressing the shortcomings of traditional methods in terms of detection accuracy, deployment cost, and real-time performance.

[0116] For the device embodiments, since they basically correspond to the method embodiments, the relevant details can be found in the descriptions of the method embodiments. The device embodiments described above are merely illustrative; components described as separate parts may or may not be physically separate, and components shown as units may or may not be physical units, meaning they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this disclosure according to actual needs. Those skilled in the art can understand and implement this without any inventive effort.

[0117] The above embodiments merely illustrate several implementation methods of the embodiments of this application, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make several modifications and improvements without departing from the concept of the embodiments of this application, and these all fall within the protection scope of the embodiments of this application.

Claims

1. A method for fixed-resolution detection of BeiDou ambiguity, characterized in that, include: The BeiDou reference station acquires real-time data streams for each satellite, wherein the real-time data streams include carrier phases for each frequency band and pseudorange observations for each frequency band. Based on the real-time data stream, the ionospheric delay of each satellite is calculated, and multiple sets of overlapping satellites and their corresponding trajectory overlap points are selected. The trajectory overlap point information of each set of overlapping satellites is then extracted. Based on the trajectory overlap point information of each group of overlapping satellites, the time compensation of the ionospheric delay of the second satellite in the trajectory overlap point information is performed by using the GIM global ionospheric model or the three-dimensional ionospheric model, respectively, to obtain the compensated delay of the second satellite in each group of overlapping satellites. Based on the ionospheric delay of the first satellite and the compensated delay of the second satellite in each group of overlapping satellites, it is determined whether the ambiguity fixation of each group of overlapping satellites is correct, and the ambiguity fixation detection result of the Beidou reference station is output according to the ambiguity fixation result of each group of overlapping satellites.

2. The BeiDou ambiguity fixing detection method as described in claim 1, characterized in that, The process involves filtering out multiple sets of overlapping satellites and their corresponding trajectory overlap points, and extracting the trajectory overlap point information for each set of overlapping satellites, including: Based on satellite precise ephemeris or broadcast ephemeris data, the spatial coordinates of each satellite's trajectory are calculated. Iterate through all satellites and combine them in pairs, then filter out overlapping satellites and their corresponding trajectory overlap points based on preset judgment conditions. Based on the overlapping satellites and the trajectory overlap points, the trajectory overlap point information of each group of overlapping satellites is integrated and recorded.

3. The BeiDou ambiguity fixing detection method as described in claim 1, characterized in that, The calculation of the ionospheric delay of each satellite based on the real-time data stream includes: Based on the carrier phase of each frequency band and the pseudorange observations of each frequency band, the estimated ambiguity parameters of each satellite are obtained. Based on the estimated ambiguity parameters of each satellite, the ambiguity parameters are fixed to obtain the integer ambiguity of each satellite. Based on the integer ambiguity and the carrier phase of each frequency band, the ionospheric delay of each satellite is calculated.

4. The BeiDou ambiguity fixing detection method as described in claim 1, characterized in that, Based on the trajectory overlap point information of each group of overlapping satellites, time compensation is performed on the ionospheric delay of the second satellite in the trajectory overlap point information using either the GIM global ionospheric model or a three-dimensional ionospheric model to obtain the compensated delay of the second satellite in each group of overlapping satellites, including: The ionospheric delay variation of the second satellite in each group of overlapping satellites is calculated using the GIM global ionospheric model or a three-dimensional ionospheric model. The ionospheric delay variation is caused by the time difference between the transit time of the first satellite and the transit time of the second satellite. When the transit time of the second satellite is greater than that of the first satellite, the ionospheric delay of the second satellite is subtracted from the change in ionospheric delay to obtain the compensated delay of the second satellite.

5. The BeiDou ambiguity fixing detection method as described in claim 4, characterized in that, The ionospheric delay variation of the second satellite in each group of overlapping satellites, calculated using the GIM global ionospheric model or a three-dimensional ionospheric model, includes: Based on the latitude and longitude of the reference station, the transit time of the first satellite and the transit time of the second satellite, the zenith ionospheric delay and accuracy information of each group of overlapping satellites are extracted from the GIM global ionospheric model or the three-dimensional ionospheric model at the corresponding time. Based on the trajectory overlap point information, the slant path delay change is calculated using the VMF3 mapping function to obtain the ionospheric delay change of the second satellite in each group of overlapping satellites.

6. The BeiDou ambiguity fixing detection method as described in claim 1, characterized in that, The determination of whether the ambiguity fixation of each group of overlapping satellites is correct, based on the ionospheric delay of the first satellite and the compensated delay of the second satellite in each group of overlapping satellites, includes: Iterate through each group of overlapping satellites; When the ionospheric delay of the first satellite and the compensated delay of the second satellite in any group of overlapping satellites do not meet the preset judgment formula, it is determined that two satellites in the group of overlapping satellites have correctly fixed ambiguity. When the ionospheric delay of the first satellite and the post-compensated delay of the second satellite in any group of overlapping satellites satisfy the preset judgment formula, it is determined that two satellites in the group of overlapping satellites have ambiguity fixing errors, and the number of anomaly markers corresponding to the two satellites in the group of overlapping satellites is increased by one.

7. The BeiDou ambiguity fixing detection method as described in claim 6, characterized in that, The output of the ambiguity fixation detection result of the BeiDou reference station includes: Count the number of anomaly markers for each satellite; Satellites whose number of anomaly markers is greater than or equal to a first preset value are identified as anomalous satellites; The number of anomalous satellites was counted, and the proportion of anomalous satellites to the total number of observed satellites was calculated. If the ratio is greater than the second preset value, it is determined that the current Beidou reference station observation data is abnormal, the current determination process is stopped, and the device is prompted to be checked and the real-time data stream is re-acquired. If the ratio is less than or equal to the second preset value, it is determined that the current Beidou reference station observation data is generally normal, and the determination result of the ambiguity fixation error is valid. Output the ambiguity fixation detection results of the BeiDou reference station.

8. A BeiDou ambiguity fixation detection system, characterized in that, The system includes: The data acquisition module is used to acquire real-time data streams from each satellite of the BeiDou reference station. The real-time data streams include carrier phases of each frequency band and pseudorange observations of each frequency band. The frequency bands include: B1 band, B2 band, and B3 band. The overlap point extraction module is used to calculate the ionospheric delay of each satellite based on the real-time data stream, and to filter out multiple sets of overlapping satellites and their corresponding trajectory overlap points, and to extract the trajectory overlap point information of each set of overlapping satellites. The trajectory overlap point information includes: overlapping satellite number, first satellite transit time, first satellite ionospheric delay, second satellite transit time, and second satellite ionospheric delay. The time compensation module is used to compensate for the ionospheric delay of the second satellite in the trajectory overlap point information based on the trajectory overlap point information of each group of overlapping satellites, by using the GIM global ionospheric model or the three-dimensional ionospheric model, to obtain the compensated delay of the second satellite in each group of overlapping satellites. The result determination module is used to determine whether the ambiguity fixation of each group of overlapping satellites is correct based on the first satellite ionospheric delay and the second satellite post-compensation delay of each group of overlapping satellites, and output the ambiguity fixation detection result of the Beidou reference station according to the ambiguity fixation result of each group of overlapping satellites.

9. A computer-readable storage medium, characterized in that, The storage medium stores a computer program or instructions, which, when executed by a communication device, implement the BeiDou ambiguity fixing detection method as described in any one of claims 1-7.

10. A computer program product, comprising a computer program or instructions, characterized in that, When the computer program or instructions are executed by the communication device, the BeiDou ambiguity fixing detection method as described in any one of claims 1-7 is implemented.

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