Real-time suppression method and system for multi-path error of three-frequency signal-to-noise ratio CORS station of Beidou

Abstract

This invention discloses a real-time method and system for suppressing multipath errors at a BeiDou three-frequency signal-to-noise ratio CORS station, belonging to the field of satellite navigation and engineering monitoring technology. The system includes a BeiDou continuously operating reference station subsystem, a communication subsystem, a data processing and control subsystem, and a surface displacement monitoring subsystem. It collects raw observation data from BeiDou three-frequency satellites; the data processing and control subsystem integrates adaptive cancellation logic linking the three-frequency signals and deformation data, extracts the deformation change period from the surface displacement monitoring data, converts it into a multipath interference frequency range and calculates the confidence level, and calculates dynamic weighting coefficients by combining the sensitivity thresholds of BeiDou B1, B2, and B3 signals to interference at different frequencies. Multipath errors are offset through weighted fusion, and the data is further optimized using corresponding algorithms; the surface displacement monitoring subsystem works in conjunction with the reference station subsystem to achieve engineering safety monitoring. This invention significantly improves the accuracy of multipath error suppression and adaptability to extreme scenarios.

Description

Technical Field

[0001] This invention relates to the field of BeiDou satellite navigation technology, specifically to a method and system for real-time suppression of multipath error at BeiDou three-frequency signal-to-noise ratio CORS stations. Background Technology

[0002] The BeiDou-3 system is a satellite navigation system independently developed by my country. It comprises multiple layers, including satellites, ground stations, and user terminals, providing comprehensive navigation services for aviation, marine, agriculture, and scientific research. In the BeiDou-3 system, orbiting Earth satellites are one of the main constellations responsible for navigation and transmission functions. However, due to the multipath effect of satellite signals, the pseudorange measurements of these orbiting Earth satellites have significant errors. This affects the accuracy and reliability of satellite navigation, especially in scenarios with extremely high monitoring accuracy requirements, such as pumped storage projects, where millimeter-level errors can lead to misjudgments of potential hazards.

[0003] Multipath effects are typically caused by signal reflection or refraction, leading to deviations from the true value in measurements, increasing pseudorange measurement errors, and reducing positioning accuracy. In complex environments, these errors can reach several meters or even tens of meters. To reduce such errors, existing technologies mainly employ three approaches: first, using high-precision receivers and choke coil antennas to suppress multipath signals at the hardware level; second, using data analysis techniques, such as smoothing algorithms, Kalman filtering, or wavelet transform, to identify and eliminate outlier data points; and third, combining geometric intensity indicators to assess the quality of the observation environment, selecting appropriate observation periods to reduce the impact of multipath, and simultaneously using carrier phase observations of satellite signals instead of pseudorange observations to improve positioning accuracy.

[0004] However, existing technologies have significant shortcomings in complex scenarios such as pumped storage engineering: First, hardware-level suppression schemes mostly employ fixed parameter designs, failing to address multipath interference variations caused by minor deformations of terrain or structures. Second, data processing algorithms and engineering monitoring data are independent and lack synergy, making it impossible to predict interference characteristics using monitoring data, resulting in delayed error suppression. Third, the utilization of BeiDou tri-frequency signals is limited to multi-frequency joint calculations, failing to fully exploit the differences in sensitivity of different frequency points to interference at different frequencies, leading to poor error suppression performance and low system stability in extreme obstruction scenarios. Therefore, there is an urgent need for a solution that requires no additional modules and can leverage existing systems to achieve high-precision real-time multipath error suppression. Summary of the Invention

[0005] The purpose of this invention is to provide a real-time method and system for suppressing multipath errors of BeiDou three-frequency signal-to-noise ratio CORS stations, which can improve the accuracy of multipath error suppression, adapt to interference changes in advance, and enhance the stability of extreme scenarios without adding new modules.

[0006] The above-mentioned technical objective of the present invention is achieved through the following technical solution: The BeiDou tri-frequency signal-to-noise ratio CORS station multipath error real-time suppression system includes: a BeiDou continuously operating reference station subsystem, a communication subsystem, a data processing and control subsystem, and a surface displacement monitoring subsystem; The BeiDou Continuous Operation Reference Station Subsystem is constructed based on the existing construction survey and control network points of the pumped storage project and is used to collect raw observation data from BeiDou tri-frequency satellites. The communication subsystem is used to realize bidirectional data transmission between the reference station subsystem and the data processing and control subsystem, and between the surface displacement monitoring subsystem and the data processing and control subsystem; The data processing and control subsystem is located in a remote equipment room. It is used to receive the raw observation data transmitted by the base station subsystem, process it through a multipath error suppression algorithm to generate differential correction data, and at the same time realize system operation monitoring, user management and information services. The surface displacement monitoring subsystem works in conjunction with the base station subsystem to acquire the three-dimensional coordinates and displacement data of the pumped storage engineering structures, thereby enabling engineering safety monitoring.

[0007] In a preferred embodiment, the BeiDou continuously operating reference station subsystem includes a multi-frequency, multi-constellation GNSS receiver and a choke antenna with dynamically adjustable parameters. The multi-frequency, multi-constellation GNSS receiver supports the reception of BeiDou B1, B2, and B3 tri-frequency signals. The equivalent impedance of the choke slot of the choke antenna can be dynamically adjusted, and the adjustment is based on the correlation results between the deformation data output by the surface displacement monitoring subsystem and the satellite signal characteristic data, which is used to specifically suppress multipath interference caused by minor deformations of terrain or structures.

[0008] In a preferred embodiment, the location of the BeiDou continuously operating reference station subsystem meets the following conditions: the distance from ground features prone to multipath effects is not less than 200m; it has satellite line-of-sight conditions with a horizon elevation angle of more than 10°; the distance from electromagnetic interference areas is not less than 200m; it is built on a stable block, avoiding areas with unstable geological structures and areas prone to flooding.

[0009] In a preferred embodiment, the multipath error suppression algorithm in the data processing and control subsystem includes a smoothing algorithm, a Kalman filter algorithm, and a wavelet transform algorithm, and integrates adaptive cancellation logic for the linkage of three-frequency signals and deformation data. The data processing and control subsystem first extracts the deformation data output by the surface displacement monitoring subsystem, including the displacement rate, cumulative displacement, and deformation change period of the deformation points. Based on a preset mapping rule, the deformation change period is converted into a multipath interference frequency range, and the confidence level of this range is calculated. Then, through spectrum analysis, the sensitivity thresholds of the BeiDou B1, B2, and B3 three-frequency signals to interference at different frequencies are determined. The sensitivity threshold for low-frequency interference in the 0.1-1Hz range for the B1 frequency point is -15dB, and for the B2 frequency point... The sensitivity threshold for 1-10Hz mid-frequency interference is -18dB, and the sensitivity threshold for 10-50Hz high-frequency interference at frequency B3 is -20dB. Dynamic weighting coefficients for the three-frequency signals are calculated based on the interference frequency range and confidence level. Weighted fusion is used to achieve complementary cancellation of interference signals at different frequencies. Finally, the appropriate error suppression algorithm is selected to optimize the data based on the complexity of the observation environment. Specifically, when the observation environment is complex, wavelet transform is used to decompose the signal and identify outliers. When the observation environment is simple and the data is continuous, Kalman filtering is used in conjunction with the dynamic model and the observation model to estimate state variables in real time. When the observation data is discontinuous, a smoothing algorithm is used to smooth the original observation data over time to remove short-term fluctuations.

[0010] In a preferred embodiment, the data processing and control subsystem further includes a geometric intensity index optimization module, which is used to calculate the DOP value, select time periods with lower DOP values ​​for observation, and combine satellite distribution information to avoid collecting data during periods of severe obstruction.

[0011] In a preferred embodiment, the surface displacement monitoring subsystem includes a GNSS displacement monitoring unit and a total station robot monitoring unit. The GNSS displacement monitoring unit includes at least one GNSS monitoring reference station located at a stable location outside the deformable body, and at least three GNSS monitoring stations located at the deformation points. The total station robot monitoring unit performs automatic measurements via remote command control, and its output deformation data is synchronously transmitted to the data processing and control subsystem. The deformation data includes the displacement rate, cumulative displacement, and deformation change period of the deformation points. The data processing and control subsystem establishes a mapping relationship between the deformation change period and the multipath interference frequency, outputs the interference frequency range and corresponding confidence parameters, and provides quantitative data support for the calculation of the adaptive weighting coefficients of the three-frequency signals.

[0012] In a preferred embodiment, the total station robot monitoring unit further includes a foldable total station protective cover, which is synchronously controlled to rise and fall via an icontrol-T communication module. The protection level is not lower than IP54, and the operating temperature range is -25~75℃.

[0013] In a preferred embodiment, the data processing and control subsystem includes a multi-constellation data processing module, a real-time quality inspection module, and a precise ephemeris processing module. The multi-constellation data processing module is equipped with a data parsing protocol, which can parse the raw observation data from GPS, GLONASS, and BeiDou systems, enabling joint processing of multi-constellation data or independent processing of single BeiDou data. The real-time quality inspection module is equipped with data quality assessment rules, which can perform real-time statistics and evaluation of the completeness rate, multipath effect parameters, cycle slip ratio, and SNR of the observation data. The precise ephemeris processing module is equipped with an ephemeris download interface and data retransmission logic, which can automatically download precise ephemeris data and use it for data processing. When the reference station and control center lose network connection, the module can automatically download the missing data from the reference station receiver and complete the retransmission after the network is restored.

[0014] In a preferred embodiment, the data processing and control subsystem is equipped with an interaction and management module based on a B / S architecture. This module includes an online map rendering unit, a user management unit, an alarm unit, a data management unit, and a log management unit. The online map rendering unit is configured with a map interface, capable of loading an online map and displaying the location information of base stations, monitoring stations, and user terminals. The user management unit is configured with registration and approval logic, permission allocation rules, and billing statistics algorithms, enabling user registration, hierarchical permission management, and statistics and calculations of usage time and traffic. The alarm unit is configured with SMS and email sending interfaces, capable of triggering SMS or email alarms based on preset thresholds. The data management unit is configured with data filtering and format conversion logic, allowing for customized filtering and downloading of observation data based on time, sampling interval, and data version, while also supporting the configuration of coordinate transformation parameters and batch coordinate transformation. The log management unit is configured with log entry and query logic, enabling the entry, storage, and conditional querying of operation and maintenance logs, inspection logs, and user login logs.

[0015] A real-time suppression method for multipath error of BeiDou tri-frequency signal-to-noise ratio CORS stations based on the aforementioned system includes the following steps: S1: Within the pumped storage project area, a BeiDou continuously operating reference station subsystem will be constructed according to the site selection requirements. The system will collect raw observation data from BeiDou tri-frequency satellites through a multi-frequency, multi-constellation GNSS receiver and a choke antenna with dynamically adjustable parameters. S2: The raw observation data is transmitted to the data processing and control subsystem via the communication subsystem. First, the output deformation data of the surface displacement monitoring subsystem, including the total station robot monitoring unit, is extracted, including the displacement rate, cumulative displacement, and deformation change period of the deformation point. Based on the preset mapping rules, the deformation change period is converted into a multipath interference frequency range and the confidence level is calculated. Then, the sensitivity thresholds of the Beidou B1, B2, and B3 signals to interference of different frequencies are determined through spectrum analysis. Dynamic weighting coefficients are calculated according to the interference frequency range and confidence level, and the three-frequency signals are weighted and fused to offset multipath errors. Finally, based on the fused data, the corresponding multipath error suppression algorithm is selected for further processing. The observation period is optimized in combination with the DOP value to generate differential correction data in standard format. S3: The GNSS displacement monitoring unit of the surface displacement monitoring subsystem acquires the three-dimensional coordinate data of the structure, and calculates the displacement value, settlement value, cumulative displacement value and displacement rate by combining the differential correction data generated by S2; at the same time, the surface displacement monitoring subsystem continuously outputs the updated deformation data and synchronously feeds it back to the data processing and control subsystem to recalculate the multipath interference frequency range and confidence level, so as to realize the real-time adjustment of the three-frequency signal adaptive weighting coefficient; S4: The data processing and control subsystem analyzes the monitoring data, monitors the system operation status in real time, triggers an alarm when the monitoring data exceeds the threshold, and provides navigation and positioning data services and coordinate transformation services to users.

[0016] Compared with the prior art, the present invention has the following beneficial effects: 1. Significantly improved multipath error suppression accuracy: This invention relies on the core feature of "adaptive cancellation logic of data processing and control subsystem integration of three-frequency signals and deformation data linkage". By mining the sensitivity differences of Beidou three-frequency signals to interference of different frequencies, and combining surface displacement monitoring data to calculate dynamic weighting coefficients to achieve interference complementary cancellation, it can significantly reduce the residual amount of multipath error in complex scenarios, and the suppression effect is far superior to existing conventional solutions. 2. Enhanced operational stability in extreme scenarios: Based on the core design of "BeiDou three-frequency signal acquisition + subsystem collaboration", even in extreme scenarios such as deep mountains and severe slope obstruction in pumped storage projects, where single-frequency signals are interfered with, the system can still ensure stable operation through multi-frequency signal weighted cancellation, effectively solving the problem of positioning and monitoring failure in extreme environments; 3. Collaborative optimization of error suppression and monitoring accuracy: Corresponding to the core feature of "two-way linkage between the surface displacement monitoring subsystem and the data processing and control subsystem", the surface displacement monitoring data provides quantitative support for multipath error suppression. The differential correction data after precise suppression feeds back into GNSS displacement monitoring, significantly improving the accuracy of deformation data calculation, forming a virtuous cycle of "monitoring-suppression-monitoring", and ensuring the accuracy and reliability of monitoring data for pumped storage projects. Attached Figure Description

[0017] Figure 1 This invention relates to a system architecture diagram of a real-time suppression system for multipath errors of a BeiDou tri-frequency signal-to-noise ratio CORS station.

[0018] Figure 2 This invention relates to a flowchart of a real-time suppression method for multipath error of a BeiDou three-frequency signal-to-noise ratio CORS station based on the system. Detailed Implementation

[0019] The present invention will now be described in further detail.

[0020] This specific embodiment is merely an explanation of the present invention and is not intended to limit the invention. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they are within the scope of the claims of the present invention. Example 1

[0021] Reference Figure 1The BeiDou Tri-Frequency Signal-to-Noise Ratio (SNR) CORS Station Multipath Error Real-Time Suppression System comprises: a BeiDou continuously operating reference station subsystem, a communication subsystem, a data processing and control subsystem, and a surface displacement monitoring subsystem. The BeiDou continuously operating reference station subsystem is constructed based on the existing construction survey control network of the pumped storage project and is used to collect raw observation data from BeiDou tri-frequency satellites. The communication subsystem enables bidirectional data transmission between the reference station subsystem and the data processing and control subsystem, and between the surface displacement monitoring subsystem and the data processing and control subsystem. The data processing and control subsystem is located in a remote equipment room and receives the raw observation data transmitted by the reference station subsystem. After processing the data using a multipath error suppression algorithm, it generates differential correction data and simultaneously provides system operation monitoring, user management, and information services. The surface displacement monitoring subsystem works in conjunction with the reference station subsystem to acquire the three-dimensional coordinates and displacement data of the pumped storage project structures, enabling project safety monitoring. In practice, the site selection and construction of the BeiDou continuously operating reference station subsystem are completed first, followed by the sequential deployment of the data transmission link of the communication subsystem, the software modules of the data processing and control subsystem, and the hardware... The system is equipped with various devices. Finally, the monitoring units of the surface displacement monitoring subsystem are deployed, and communication debugging between subsystems is completed. After debugging, the system is started. The base station subsystem continuously collects raw BeiDou three-frequency observation data, which is transmitted to the data processing and control subsystem via the communication subsystem. Simultaneously, the surface displacement monitoring subsystem collects the three-dimensional coordinates and displacement data of the structure and transmits them synchronously. The data processing and control subsystem processes the data based on a multi-path error suppression algorithm to generate differential correction data, which feeds back into the surface displacement monitoring subsystem to improve monitoring accuracy, ultimately achieving full-cycle safety monitoring of the pumped storage project. Through the collaborative design of multiple subsystems, this system breaks the limitation of existing technologies where base station data acquisition and engineering monitoring data are isolated. It achieves deep linkage between multi-path error suppression and engineering deformation monitoring, not only suppressing multi-path errors accurately in real time but also adapting the error suppression process to the interference changes caused by engineering deformation. This effectively solves the problems of lagging and insufficient targeting in existing technologies, ensuring that monitoring data remains highly accurate and reliable in scenarios like pumped storage projects where monitoring accuracy is extremely high, providing solid data support for engineering safety assessment and operation and maintenance decisions.

[0022] The BeiDou Continuous Operation Reference Station Subsystem is constructed based on the existing construction survey and control network points of the pumped storage project and is used to collect raw observation data from BeiDou tri-frequency satellites. The communication subsystem is used to realize bidirectional data transmission between the reference station subsystem and the data processing and control subsystem, and between the surface displacement monitoring subsystem and the data processing and control subsystem; The data processing and control subsystem is located in a remote equipment room. It is used to receive the raw observation data transmitted by the base station subsystem, process it through a multipath error suppression algorithm to generate differential correction data, and at the same time realize system operation monitoring, user management and information services. The surface displacement monitoring subsystem works in conjunction with the base station subsystem to acquire the three-dimensional coordinates and displacement data of the pumped storage engineering structures, thereby enabling engineering safety monitoring.

[0023] Furthermore, the BeiDou continuously operating reference station subsystem includes a multi-frequency, multi-constellation GNSS receiver and a choke antenna with dynamically adjustable parameters. The multi-frequency, multi-constellation GNSS receiver supports BeiDou B1, B2, and B3 tri-frequency signal reception. The equivalent impedance of the choke slot of the choke antenna can be dynamically adjusted based on the correlation results between deformation data output by the surface displacement monitoring subsystem and satellite signal characteristic data, used to specifically suppress multipath interference caused by minor deformations of terrain or structures. In specific execution, the multi-frequency, multi-constellation GNSS receiver and the choke antenna are precisely connected and fixed to the reference station bracket. The receiver parameters are configured to enable BeiDou B1, B2, and B3 tri-frequency signal reception. Simultaneously, a signal transmission link is established between the choke antenna and the data processing and control subsystem. The data processing and control subsystem receives surface displacement monitoring data in real time. The deformation data of the measurement subsystem and the satellite signal characteristic data transmitted by the receiver are correlated and analyzed to generate impedance adjustment commands, which are then sent to the built-in adjustment module of the choke antenna. The adjustment module drives the mechanical structure to adjust the equivalent impedance of the choke slot. This setting overcomes the shortcomings of existing fixed-parameter choke antennas that cannot adapt to environmental changes. It can dynamically adjust the impedance parameters according to the slight deformation of the terrain or structure, and specifically shield multipath interference signals from different sources and frequencies. This not only significantly improves the signal-to-noise ratio of the BeiDou tri-frequency raw observation data and reduces the introduction of invalid interference data, but also allows the anti-interference capability of the reference station subsystem to dynamically adapt to engineering deformation, avoiding the data quality degradation caused by the increased interference due to deformation. This provides a high-quality and highly stable raw data foundation for error suppression in subsequent data processing stages, further ensuring the accuracy of the final monitoring results.

[0024] Furthermore, the site selection of the BeiDou continuously operating reference station subsystem meets the following conditions: the distance from ground features prone to multipath effects is not less than 200m; it has satellite line-of-sight conditions with a horizon elevation angle of 10° or higher; the distance from electromagnetic interference zones is not less than 200m; it is established on a stable block, avoiding areas with unstable geological structures and areas prone to flooding; in specific implementation, candidate sites are first preliminarily screened using the distribution map of the pumped storage project construction survey control network, and then on-site surveys are conducted with equipment such as rangefinders and satellite line-of-sight instruments to measure the distance between the candidate sites and ground features prone to multipath effects such as tall buildings and trees. The horizon elevation angle line-of-sight is observed and recorded at different times using the satellite line-of-sight instrument, and the electromagnetic environment around the candidate sites is detected using an electromagnetic interference detector. By combining regional geological survey reports to confirm the geological stability of the sites and the existence of flooding risks, sites that meet all the conditions were finally determined and the base station subsystem was built. This site selection process avoids core risks such as multipath effects, electromagnetic interference, and damage to the natural environment from the source. Compared with existing schemes that arbitrarily select sites or only meet basic line-of-sight conditions, it can minimize the impact of external interference on the raw observation data, ensure the stability and accuracy of the raw observation data during the long-term operation of the base station subsystem, and reduce the difficulty of error suppression and computational load in subsequent data processing. It avoids system operation failures or data failures caused by improper site selection, and ensures that the base station subsystem can continuously provide reliable data acquisition support for pumped storage project monitoring.

[0025] Furthermore, the multipath error suppression algorithm in the data processing and control subsystem includes a smoothing algorithm, a Kalman filter algorithm, and a wavelet transform algorithm, and integrates adaptive cancellation logic for the linkage of three-frequency signals and deformation data. The data processing and control subsystem first extracts the deformation data output by the surface displacement monitoring subsystem, including the displacement rate, cumulative displacement, and deformation change period of the deformation points. Based on a preset mapping rule, the deformation change period is converted into a multipath interference frequency range, and the confidence level of this range is calculated. Then, through spectrum analysis, the sensitivity thresholds of the BeiDou B1, B2, and B3 three-frequency signals to interference at different frequencies are determined. The sensitivity threshold for low-frequency interference (0.1-1Hz) is -15dB for B1 frequency point, and for B2 frequency point, it is -15dB for 1-10Hz. The sensitivity threshold for intermediate frequency interference (IF) z is -18dB, and the sensitivity threshold for high-frequency interference (HF) at frequency B3 (10-50Hz) is -20dB. Dynamic weighting coefficients for the three-frequency signals are calculated based on the interference frequency range and confidence level. Weighted fusion is used to achieve complementary cancellation of interference signals at different frequencies. Finally, an appropriate error suppression algorithm is selected to optimize the data based on the complexity of the observation environment. Specifically, when the observation environment is complex, wavelet transform is used to decompose the signal and identify outliers. When the observation environment is simple and the data is continuous, Kalman filtering is used in conjunction with a dynamic model and an observation model to estimate state variables in real time. When the observation data is discontinuous, a smoothing algorithm is used to smooth the original observation data over time to remove short-term fluctuations. In practice… The data processing and control subsystem first initiates the data receiving process, synchronously acquiring deformation data from the surface displacement monitoring subsystem and raw three-frequency observation data from the reference station subsystem. It then calls a built-in mapping rule function to convert the deformation change period into an interference frequency range, and calculates the confidence level of this range using a statistical analysis algorithm. Subsequently, the spectrum analysis module performs spectral analysis on the three-frequency signals to determine the interference sensitivity threshold corresponding to each frequency point. Based on the interference frequency range, confidence level, and sensitivity threshold, a dynamic weighting coefficient for the three-frequency signals is generated using a weighted calculation model, and the three-frequency signals are then weighted and fused. Finally, the environment recognition module assesses the complexity of the observation environment, automatically matches and calls the corresponding error suppression algorithm to optimize the fused data. This execution process fully leverages the frequency characteristics and interference complementarity of BeiDou tri-frequency signals. Combined with engineering deformation data, it achieves proactive prediction and precise cancellation of multipath interference. This breaks through the limitations of existing technologies where multi-frequency signals are only used for joint calculation and algorithm selection is singular and fixed. It not only significantly improves the accuracy of data processing in complex environments and effectively reduces multipath error residue, but also adapts to different observation environments through adaptive matching of the algorithm. This avoids the processing shortcomings of a single algorithm in complex or discontinuous data scenarios, ensuring the universality and reliability of data processing. At the same time, it dynamically links the error suppression process with engineering deformation, further improving the pertinence and real-time performance of error suppression, and providing core technical support for the accurate generation of subsequent differential correction data. Furthermore, the data processing and control subsystem also includes a geometric intensity index optimization module. This module calculates the DOP value, selects observation periods with lower DOP values, and avoids periods of severe obstruction by considering satellite distribution. Specifically, the geometric intensity index optimization module receives satellite orbit data and observation data transmitted from the reference station subsystem in real time, calls the DOP value calculation algorithm to calculate relevant indicators such as position accuracy factor, horizontal accuracy factor, and vertical accuracy factor, and analyzes the satellite distribution at different times using a satellite distribution database. It then selects periods with lower DOP values ​​and less satellite obstruction, generates an optimal observation period table, and sends it to the main control module of the data processing and control subsystem. The main control module then... According to the time schedule, observation instructions are issued to the reference station subsystem, controlling the reference station subsystem to focus on collecting data during the optimal time period, avoiding periods with severe obstruction and high DOP values. This execution process can proactively avoid the impact of adverse observation environments on data acquisition. Compared with the existing technology of passively receiving data from all time periods and then filtering it later, it can not only significantly improve the effectiveness and accuracy of observation data and reduce the burden of collecting and processing invalid data, but also further reduce the probability of introducing multipath errors by prioritizing data collection during periods with reasonable satellite distribution and less interference. This provides high-quality data support for subsequent error suppression and data calculation, while improving the system's data processing efficiency, ensuring that differential correction data can be generated quickly and accurately, and guaranteeing the real-time requirements of engineering monitoring.

[0026] Furthermore, the surface displacement monitoring subsystem includes a GNSS displacement monitoring unit and a total station robot monitoring unit. The GNSS displacement monitoring unit includes at least one GNSS monitoring reference station located at a stable location outside the deformable body, and at least three GNSS monitoring stations located at the deformation points. The total station robot monitoring unit achieves automatic measurement through remote command control, and its output deformation data is synchronously transmitted to the data processing and control subsystem. The deformation data includes the displacement rate, cumulative displacement, and deformation change period of the deformation points. The data processing and control subsystem establishes a mapping relationship between the deformation change period and the multipath interference frequency, outputs the interference frequency range and corresponding confidence parameters, and provides quantitative data support for the calculation of the adaptive weighting coefficient of the three-frequency signal. In specific execution, GNSS monitoring reference stations are first deployed in stable areas outside the deformable body of the pumping station project, and at least three GNSS monitoring stations are evenly deployed at key deformation points such as the dam body and slopes to complete the equipment debugging and networking of the GNSS displacement monitoring unit. The total station robot monitoring unit is deployed in an area with a wide field of view that can cover all deformation points, and a remote control is configured. The control module establishes a communication connection with the data processing and control subsystem, setting automatic measurement intervals and measurement accuracy parameters. Upon startup, the GNSS displacement monitoring unit collects real-time three-dimensional coordinate data of deformation points, while the total station robot monitoring unit automatically completes deformation point measurements and outputs deformation data according to remote commands. Both types of data are transmitted to the data processing and control subsystem in real-time, where key parameters such as deformation change cycles are extracted to establish mapping relationships. This execution process, through collaborative monitoring by GNSS and the total station robot, achieves comprehensive and accurate acquisition of deformation data. Compared to a single monitoring method, this not only improves the coverage and reliability of deformation data but also provides accurate and real-time quantitative basis for calculating the adaptive weighting coefficients of the three-frequency signals. This ensures that the multipath error cancellation logic can accurately adapt to the interference changes caused by engineering deformation, guaranteeing the effectiveness of multipath error suppression from the data source. Simultaneously, the automatic measurement mode reduces manual intervention, improves monitoring efficiency, avoids errors caused by manual measurement, and ensures continuous and stable transmission of deformation data, providing core data support for the real-time error suppression and accurate monitoring of the entire system.

[0027] Furthermore, the total station robot monitoring unit also includes a foldable total station protective cover. The protective cover's lifting and lowering are synchronously controlled via an icontrol-T communication module. Its protection level is no lower than IP54, and its operating temperature range is -25~75℃. In practice, the foldable total station protective cover is mechanically connected to the total station robot monitoring unit. The icontrol-T communication module is connected to the protective cover's lifting drive mechanism and data processing and control subsystem. The lifting and lowering trigger conditions are configured. When the ambient temperature exceeds the -25~75℃ range, rain, snow, or sandstorms occur, or the total station robot monitoring unit stops measuring, the data processing and control subsystem sends a lifting command, driving the protective cover to rise via the icontrol-T communication module. Protection: When environmental conditions return to normal and measurements are required, a descent command is sent to fold the protective cover, without affecting the measurement field of view. This execution process effectively solves the problem that existing total station robots are susceptible to damage from extreme weather in complex outdoor environments such as pumped storage projects. Through the intelligent lifting and lowering protective cover design, it can specifically resist the erosion of harsh environments such as extreme temperatures, rain, snow, and sandstorms, significantly improving the service life and operational stability of the equipment in complex outdoor environments. At the same time, the automatic lifting and lowering of the protective cover does not affect normal measurement work, ensuring the continuity and reliability of deformation data acquisition, avoiding monitoring interruptions or data loss due to equipment failure, ensuring the integrity of the output data of the surface displacement monitoring subsystem, and providing stable data support for the continuous and effective operation of the multipath error suppression logic.

[0028] Furthermore, the data processing and control subsystem includes a multi-constellation data processing module, a real-time quality inspection module, and a precise ephemeris processing module. The multi-constellation data processing module is equipped with a data parsing protocol, capable of parsing raw observation data from GPS, GLONASS, and BeiDou systems, enabling joint processing of multi-constellation data or independent processing of a single BeiDou system. The real-time quality inspection module is equipped with data quality assessment rules, capable of real-time statistical evaluation of the completeness rate, multipath effect parameters, cycle slip ratio, and SNR of observation data. The precise ephemeris processing module is equipped with an ephemeris download interface and data retransmission logic, capable of automatically downloading precise ephemeris data for data processing. When the base station and control center experience network outages, it can automatically download missing data from the base station receiver and complete the retransmission after network recovery. In specific execution, after the multi-constellation data processing module starts, it loads a preset data parsing protocol, receives and parses raw observation data from multiple systems in real time, and selects between multi-constellation joint processing or independent processing mode based on user needs or system configuration. The real-time quality inspection module synchronously receives observation data and calculates data completeness according to preset quality assessment rules. Indicators such as integer ratio and multipath effect parameters are used to mark unqualified data and feed them back to the main data processing module. The precise ephemeris processing module automatically downloads precise ephemeris periodically through a preset ephemeris download interface, stores it in the local database, and uses it for data calculation. When a network outage is detected, a local caching mechanism is activated. After the network is restored, it automatically connects to the base station receiver to download the missing data, completing data retransmission and calculation completion. This execution process breaks through the limitations of existing data processing modules, which have single functions and poor fault tolerance. The multi-constellation calculation mode improves the flexibility and accuracy of data calculation and can adapt to different satellite signal coverage scenarios. The real-time quality inspection function can promptly remove unqualified data to avoid bad data affecting the final processing results and improve the reliability of data processing. The precise ephemeris processing and data retransmission functions ensure the integrity of data in special situations such as network outages and avoid monitoring interruptions caused by data loss. Overall, this setting significantly improves the fault tolerance, reliability, and adaptability of the data processing and control subsystems, ensuring that differential correction data can be generated accurately and continuously, providing a core guarantee for the accuracy and continuity of engineering monitoring.

[0029] Furthermore, the data processing and control subsystem is equipped with an interaction and management module based on a B / S architecture. This module includes an online map rendering unit, a user management unit, an alarm unit, a data management unit, and a log management unit. The online map rendering unit is configured with a map interface, capable of loading online maps and displaying the location information of base stations, monitoring stations, and user terminals. The user management unit is configured with registration and approval logic, permission allocation rules, and billing statistics algorithms, enabling user registration, hierarchical permission management, and statistics and calculation of usage time and traffic. The alarm unit is configured with SMS and email sending interfaces, capable of triggering SMS or email alerts based on preset thresholds. The data management unit is configured with data filtering and format conversion logic, allowing users to customize filtering and download observation data based on time, sampling interval, and data version. It also supports configuring coordinate transformation parameters and batch coordinate transformation. The log management unit is configured with log entry and query logic, enabling the entry, storage, and conditional querying of operation and maintenance logs, inspection logs, and user login logs. During execution, after the interaction and management module starts, the online map rendering unit loads the map interface and synchronizes the location data of the base station, monitoring station, and user terminal, updating and displaying the data on the map in real time. The user management unit receives user registration applications and completes the review according to the approval logic, allocating permissions accordingly. The system assigns operation permissions to different users and periodically calculates user usage time and data traffic according to a billing algorithm. The alarm unit receives monitoring data in real time, compares it with preset thresholds, and automatically sends alarm information via SMS and email when the data exceeds the threshold. The data management unit receives user data filtering requests, filters data by time, sampling interval, and other conditions, performs format conversion or coordinate conversion according to user needs, and provides download services. The log management unit records various log data in real time and supports users querying logs by time, log type, and other conditions. This execution process achieves visualized, precise operation and maintenance, and efficient data services for the system, compared to existing traditional management models. Online map rendering makes the location and operating status of equipment clear at a glance, improving the convenience of operation and maintenance; refined user management ensures the security and standardization of system use; real-time alarm function can promptly warn of engineering hazards or system failures, providing time guarantee for rapid response; flexible data management function meets the personalized data needs of different users and improves data utilization; complete log management ensures the traceability of system operation and maintenance, facilitating problem investigation and responsibility identification; overall, this setting significantly improves the system's usability, operation and maintenance efficiency and management standardization, reduces system operation and maintenance costs, and ensures that the entire monitoring system can operate stably and efficiently in the long term.

[0030] Furthermore, the data processing and control subsystem also includes an environmental perception collaborative correction module. This module accesses environmental sensor data from the vicinity of the base station subsystem via the communication subsystem. These environmental sensors include temperature and humidity sensors, air pressure sensors, precipitation sensors, and wind speed sensors, used to collect data on ambient temperature and humidity, atmospheric pressure, precipitation, and wind speed. The environmental perception collaborative correction module incorporates an environmental parameter-error impact correlation model, which quantifies the influence weight of environmental factors on multipath errors based on the collected environmental data, generates error correction compensation, and performs secondary correction on the dynamic weighting coefficients of the three-frequency signals. In practice, the environmental sensors are first deployed in an open area within a 10m radius of the base station subsystem to ensure that the sensor data accurately reflects the base station's observation environment. A real-time data transmission link is established between the sensors and the data processing and control subsystem via the communication subsystem. After the environmental perception collaborative correction module is activated, it receives real-time temperature, humidity, air pressure, precipitation, and wind speed data collected by the environmental sensors and calls the built-in environmental parameter-error impact correlation model. This model uses historical environmental data and the residual multipath error data... Regression analysis training yields the error impact weights corresponding to each environmental parameter. Error correction compensation is calculated based on these weights, and the dynamic weighting coefficients of the three-frequency signals already calculated by the data processing and control subsystems are adjusted a second time. When extreme environmental parameters are detected (e.g., precipitation ≥ 50 mm / h, wind speed ≥ 15 m / s), the weight of the environmental correction compensation is automatically increased to enhance the correction effect. This setting breaks through the limitations of existing technologies that rely solely on deformation data and satellite signal characteristics for error suppression. For the first time, it deeply integrates environmental perception data with multipath error suppression, accurately adapting to multipath error fluctuations caused by environmental factors such as temperature and humidity changes, atmospheric refraction, and precipitation obstruction. This not only further improves the accuracy of multipath error suppression in complex environments but also allows for early prediction of error change trends before extreme weather events, enabling proactive adjustments to error suppression. This solves the problem of lagging error suppression and sharp drops in accuracy in scenarios of sudden environmental changes, ensuring the system maintains high stability in diverse environmental conditions. It provides additional assurance for the all-weather, all-environmental accurate monitoring of pumped storage projects, producing an unexpected synergistic effect between environmental adaptation and error suppression.

[0031] This embodiment provides a BeiDou tri-frequency signal-to-noise ratio CORS station multipath error real-time suppression system, applied to a safety monitoring scenario of a pumped storage project. The specific structure is as follows: 1. Site Selection and Construction of the BeiDou Continuous Operation Reference Station Subsystem: Based on the existing construction survey control network of a pumped storage project, the reference station for the lower reservoir was selected as point II10, and the reference station for the upper reservoir was selected as point II05. The sites meet the following conditions: more than 200m away from tall buildings, trees, and other features that are prone to multipath effects; satellite line-of-sight conditions with a horizon elevation angle of more than 10°; more than 200m away from electromagnetic interference areas such as high-voltage lines; built on stable blocks; avoiding fault zones, landslide-prone areas, and flood-prone areas; the subsystem is equipped with a multi-frequency, multi-constellation GNSS receiver and a choke antenna with dynamically adjustable parameters. The GNSS receiver supports the reception of BeiDou B1, B2, and B3 tri-frequency signals. The choke antenna has a built-in adjustable impedance module for receiving data processing and parameter adjustment commands for the control subsystem.

[0032] 2. Surface Displacement Monitoring Subsystem Setup: This includes a GNSS displacement monitoring unit and a total station robot monitoring unit. The GNSS displacement monitoring unit sets up one GNSS reference station at a stable location outside the deformable body and deploys three GNSS monitoring stations on the dam surface as deformation point monitoring stations. The total station robot monitoring unit is equipped with an observation device on a hill opposite the dam, featuring a foldable total station protective cover. The cover's raising and lowering are synchronously controlled via an icontrol-T communication module, achieving an IP54 protection rating and stable operation in environments ranging from -25°C to 75°C. It achieves automatic measurement via remote command control, outputting data such as the displacement rate, cumulative displacement, and deformation change period of the deformation points.

[0033] 3. Communication Subsystem Setup: A wireless bridge is used to establish a data transmission link, enabling bidirectional data transmission between the BeiDou continuous operation reference station subsystem and the data processing and control subsystem, as well as between the surface displacement monitoring subsystem and the data processing and control subsystem. Among them, the total station robot monitoring unit selects a suitable mobile network to access the Internet based on the communication signals near the hill, ensuring the stability of data transmission. The transmission bandwidth is greater than 64KBPS, enabling 24-hour uninterrupted data transmission.

[0034] 4. Data processing and control subsystem construction: Located in a remote computer room, utilizing existing network facilities and the BeiDou data receiving and processing server of the dam monitoring system, a multi-constellation data processing module, a real-time quality inspection module, a precise ephemeris processing module, and an interaction and management module based on B / S architecture are built. The multi-constellation data processing module is configured with the original data parsing protocols of GPS, GLONASS, and BeiDou systems, enabling joint processing of multi-constellation data or independent processing of single BeiDou data. The real-time quality inspection module is configured with data quality assessment rules to perform real-time statistics and assessment of the completeness rate, multipath effect parameters, cycle slip ratio, and SNR of the observed data. The precision ephemeris processing module is equipped with an ephemeris download interface and data retransmission logic. It can automatically download precision ephemeris and use it for data calculation. When the base station and control center lose network connection, it can automatically download the missing data from the base station receiver and complete the retransmission after the network is restored. The online map rendering unit of the interaction and management module loads the online map and displays the location information of the base station, monitoring station, and user terminal; the user management unit realizes user registration approval, hierarchical permission management, and statistical calculation of usage time and traffic; the alarm unit configures SMS and email sending interfaces and triggers alarms according to preset thresholds; the data management unit supports custom filtering and downloading of observation data based on time, sampling interval, and data version, and also supports coordinate transformation parameter configuration and batch coordinate transformation; the log management unit realizes the input, storage, and conditional query of operation and maintenance logs, inspection logs, and user login logs.

[0035] In this embodiment, the specific implementation process of the three-frequency signal-deformed data linkage adaptive cancellation logic integrated in the data processing and control subsystem is as follows: The first step is to extract the deformation data output by the total station robot monitoring unit, where the deformation change period is T. Based on the preset mapping rule f=1 / T, the deformation change period is converted into a multipath interference frequency f. At the same time, the confidence level of this frequency range is calculated. The confidence level calculation adopts the evaluation method based on sample variance. The sample size is deformation data for 24 consecutive hours, and the confidence level threshold is set to 0.85. The second step is to determine the sensitivity thresholds of the BeiDou three-frequency signals through spectrum analysis: the sensitivity threshold of the B1 frequency point to low-frequency interference of 0.1-1Hz is -15dB, the sensitivity threshold of the B2 frequency point to mid-frequency interference of 1-10Hz is -18dB, and the sensitivity threshold of the B3 frequency point to high-frequency interference of 10-50Hz is -20dB. The third step is to calculate the dynamic weighting coefficient based on the interference frequency f and the confidence level. The weighted least squares method is used, and the weighting coefficient is positively correlated with the confidence level and negatively correlated with the signal sensitivity threshold. That is, the higher the confidence level and the lower the sensitivity threshold, the larger the weighting coefficient. The fourth step is to perform weighted fusion of the three-frequency signals based on the calculated weighting coefficients to achieve complementary cancellation of interference signals at different frequency points. Example 2

[0036] Reference Figure 2 The real-time suppression method for multipath error of BeiDou three-frequency signal-to-noise ratio CORS station based on the system described in Embodiment 1 includes the following steps: S1: Within the pumped storage project area, a BeiDou continuously operating reference station subsystem will be constructed according to the site selection requirements. The system will collect raw observation data from BeiDou tri-frequency satellites through a multi-frequency, multi-constellation GNSS receiver and a choke antenna with dynamically adjustable parameters. S2: The raw observation data is transmitted to the data processing and control subsystem via the communication subsystem. First, the output deformation data of the surface displacement monitoring subsystem, including the total station robot monitoring unit, is extracted, including the displacement rate, cumulative displacement, and deformation change period of the deformation point. Based on the preset mapping rules, the deformation change period is converted into a multipath interference frequency range and the confidence level is calculated. Then, the sensitivity thresholds of the Beidou B1, B2, and B3 signals to interference of different frequencies are determined through spectrum analysis. Dynamic weighting coefficients are calculated according to the interference frequency range and confidence level, and the three-frequency signals are weighted and fused to offset multipath errors. Finally, based on the fused data, the corresponding multipath error suppression algorithm is selected for further processing. The observation period is optimized in combination with the DOP value to generate differential correction data in standard format. S3: The GNSS displacement monitoring unit of the surface displacement monitoring subsystem acquires the three-dimensional coordinate data of the structure, and calculates the displacement value, settlement value, cumulative displacement value and displacement rate by combining the differential correction data generated by S2; at the same time, the surface displacement monitoring subsystem continuously outputs the updated deformation data and synchronously feeds it back to the data processing and control subsystem to recalculate the multipath interference frequency range and confidence level, so as to realize the real-time adjustment of the three-frequency signal adaptive weighting coefficient; S4: The data processing and control subsystem analyzes the monitoring data, monitors the system's operating status in real time, triggers an alarm when the monitoring data exceeds the threshold, and provides navigation and positioning data services and coordinate transformation services to the user. Specifically, the process proceeds as follows: First, after completing the construction of the S1 base station subsystem, the equipment is started and the sampling interval is set to begin collecting raw BeiDou three-frequency observation data. Second, the communication subsystem is started to establish a data transmission link, transmitting the raw observation data to the data processing and control subsystem in real time. Simultaneously, deformation data from the surface displacement monitoring subsystem is extracted, and interference frequency range conversion, confidence level calculation, sensitivity threshold determination, and weighting are completed. The first step involves data calculation and signal fusion. Based on the complexity of the observation environment, an algorithm is selected to process the data, and differential correction data is generated by combining the DOP value optimization results. The second step involves activating the GNSS displacement monitoring unit of the surface displacement monitoring subsystem to collect three-dimensional coordinate data of the structure. This data, combined with the differential correction data, is used to calculate various displacement parameters. Simultaneously, the updated deformation data is fed back to the data processing and control subsystem to achieve dynamic adjustment of the weighting coefficients. The third step involves the data processing and control subsystem analyzing the monitoring data and system operating parameters in real time. When displacement parameters exceed preset safety thresholds or system malfunctions, an alarm mechanism is triggered, and navigation and positioning data and coordinate transformation services are pushed to the user terminal.

[0037] This method deeply integrates engineering deformation monitoring with multipath error suppression through a closed-loop processing flow of "data acquisition - error suppression - data calculation - feedback optimization," overcoming the limitations of existing methods that rely on error suppression being disconnected from actual engineering scenarios and passively correcting errors. It not only achieves real-time and accurate suppression of multipath errors but also dynamically adjusts the error suppression strategy based on deformation data feedback, ensuring the error suppression process precisely adapts to the interference changes caused by engineering deformation. This significantly improves the system's adaptability to complex environments and deformation interference. Simultaneously, by combining the complementary advantages of three-frequency signals and adaptive algorithm selection, it effectively solves the problems of poor error suppression and data failure in extreme occlusion scenarios, ensuring the accuracy and continuity of pumped storage engineering monitoring. Furthermore, the entire process requires no additional hardware and can be implemented using existing engineering monitoring resources, reducing application costs. Ultimately, it provides high-quality, highly reliable monitoring data for the safety monitoring of pumped storage engineering, effectively avoiding misjudgments of engineering hazards due to data deviations, providing scientific and reliable data support for engineering operation and maintenance decisions, and ensuring the operational safety of critical infrastructure.

[0038] This embodiment provides a real-time suppression method for multipath error of BeiDou tri-frequency signal-to-noise ratio CORS stations based on the system of Embodiment 1. The specific steps are as follows: S1: In a certain pumped storage project area, a Beidou continuously operating reference station subsystem is constructed according to the site selection requirements of Example 1. The raw observation data of Beidou three-frequency satellites are collected through a multi-frequency multi-constellation GNSS receiver and a choke antenna with dynamically adjustable parameters, and the sampling rate is set to 1s. S2: The original observation data is transmitted to the data processing and control subsystem via the communication subsystem. First, the output deformation data of the surface displacement monitoring subsystem, including the total station robot monitoring unit, is extracted, including the displacement rate, cumulative displacement, and deformation change period of the deformation point. Based on the preset mapping rule f=1 / T, the deformation change period is converted into a multipath interference frequency range and the confidence level is calculated. Then, the sensitivity threshold of the Beidou B1, B2, and B3 signals to interference of different frequencies is determined by spectrum analysis. According to the interference frequency range and confidence level, the weighted least squares method is used to calculate the dynamic weighting coefficient, and the three-frequency signals are weighted and fused to offset the multipath error. Finally, the corresponding error suppression algorithm is selected for further processing based on the complexity of the observation environment: In this embodiment, the pumped storage project area has complex obstructions such as slopes and buildings, and the observation environment is complex. The wavelet transform algorithm is used to decompose the signal and identify anomalies. At the same time, the DOP value is calculated through the geometric strength index optimization module. The observation is carried out in the time period when the DOP value is lower than 3, avoiding the time period with severe obstruction in the morning and evening, and generating differential correction data in standard format. S3: The GNSS displacement monitoring unit of the surface displacement monitoring subsystem acquires the three-dimensional coordinate data of the dam structure, and calculates the displacement value, settlement value, cumulative displacement value and displacement rate by combining the differential correction data generated by S2; at the same time, the surface displacement monitoring subsystem outputs updated deformation data once an hour, and synchronously feeds it back to the data processing and control subsystem to recalculate the multipath interference frequency range and confidence level, so as to realize the real-time adjustment of the three-frequency signal adaptive weighting coefficient; S4: The data processing and control subsystem analyzes the monitoring data, monitors the operating status of each base station device, the transmission rate and packet loss rate of the communication link in real time, and triggers SMS and email alarms when the cumulative displacement in the monitoring data exceeds the preset threshold of 5mm, and provides navigation and positioning data services and coordinate conversion services to the operation and maintenance personnel.

[0039] In this embodiment, actual testing showed that the residual multipath error was 0.018m, the system stability rate was 99.6%, and the accuracy of the deformation data calculated by the GNSS displacement monitoring unit was 38% higher than that of the existing technology, fully meeting the millimeter-level safety monitoring requirements of pumped storage projects.

[0040] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or terminal device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or terminal device. Unless otherwise specified, an element defined by the phrase "comprising..." or "including..." does not exclude the presence of additional elements in the process, method, article, or terminal device that includes said element. Additionally, in this document, "greater than," "less than," "exceeding," etc., are understood to exclude the stated number; "above," "below," "within," etc., are understood to include the stated number.

[0041] The above description of the embodiments is provided to facilitate understanding and use of the present invention by those skilled in the art. It is obvious to those skilled in the art that various modifications can be easily made to the embodiments, and the general principles described herein can be applied to other embodiments without creative effort. Therefore, the present invention is not limited to the above embodiments. Improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the present invention should be within the protection scope of the present invention.

Claims

1. A real-time suppression system for multipath error of BeiDou tri-frequency CORS stations, characterized in that, include: The system includes a BeiDou continuously operating reference station subsystem, a communication subsystem, a data processing and control subsystem, and a surface displacement monitoring subsystem. The BeiDou Continuous Operation Reference Station Subsystem is constructed based on the existing construction survey and control network points of the pumped storage project and is used to collect raw observation data from BeiDou tri-frequency satellites. The communication subsystem is used to realize bidirectional data transmission between the reference station subsystem and the data processing and control subsystem, and between the surface displacement monitoring subsystem and the data processing and control subsystem; The data processing and control subsystem is located in a remote equipment room. It is used to receive the raw observation data transmitted by the base station subsystem, process it through a multipath error suppression algorithm to generate differential correction data, and at the same time realize system operation monitoring, user management and information services. The surface displacement monitoring subsystem works in conjunction with the base station subsystem to acquire the three-dimensional coordinates and displacement data of the pumped storage engineering structures, thereby enabling engineering safety monitoring.

2. The BeiDou tri-frequency signal-to-noise ratio CORS station multipath error real-time suppression system according to claim 1, characterized in that, The BeiDou continuously operating reference station subsystem includes a multi-frequency, multi-constellation GNSS receiver and a choke antenna with dynamically adjustable parameters. The multi-frequency, multi-constellation GNSS receiver supports the reception of BeiDou B1, B2, and B3 tri-frequency signals. The equivalent impedance of the choke slot of the choke antenna can be dynamically adjusted, and the adjustment is based on the correlation results between the deformation data output by the surface displacement monitoring subsystem and the satellite signal characteristic data, which is used to specifically suppress multipath interference caused by minor deformations of terrain or structures.

3. The BeiDou tri-frequency signal-to-noise ratio CORS station multipath error real-time suppression system according to claim 1, characterized in that, The site selection of the BeiDou continuously operating reference station subsystem meets the following conditions: the distance from ground features prone to multipath effects is not less than 200m; it has satellite line-of-sight conditions with a horizon elevation angle of more than 10°; the distance from electromagnetic interference areas is not less than 200m; it is built on a stable block, avoiding areas with unstable geological structures and areas prone to flooding.

4. The BeiDou tri-frequency signal-to-noise ratio CORS station multipath error real-time suppression system according to claim 1, characterized in that, The multipath error suppression algorithm in the data processing and control subsystem includes a smoothing algorithm, a Kalman filter algorithm, and a wavelet transform algorithm, and integrates adaptive cancellation logic for the linkage of three-frequency signals and deformation data. The data processing and control subsystem first extracts the deformation data output by the surface displacement monitoring subsystem, including the displacement rate, cumulative displacement, and deformation change period of the deformation points. Based on a preset mapping rule, the deformation change period is converted into a multipath interference frequency range, and the confidence level of this range is calculated. Then, through spectrum analysis, the sensitivity thresholds of the BeiDou B1, B2, and B3 signals to interference at different frequencies are determined. The sensitivity threshold for low-frequency interference (0.1-1Hz) is -15dB for B1 frequency and -15dB for B2 frequency. The sensitivity threshold for 10-50 Hz intermediate frequency interference is -18 dB, and the sensitivity threshold for 10-50 Hz high frequency interference at frequency B3 is -20 dB. Dynamic weighting coefficients for the three-frequency signals are calculated based on the interference frequency range and confidence level. Weighted fusion is used to achieve complementary cancellation of interference signals at different frequencies. Finally, the appropriate error suppression algorithm is selected to optimize the data based on the complexity of the observation environment. Specifically, when the observation environment is complex, wavelet transform is used to decompose the signal and identify outliers. When the observation environment is simple and the data is continuous, Kalman filtering is used in conjunction with the dynamic model and the observation model to estimate state variables in real time. When the observation data is discontinuous, a smoothing algorithm is used to smooth the original observation data over time to remove short-term fluctuations.

5. The BeiDou tri-frequency signal-to-noise ratio CORS station multipath error real-time suppression system according to claim 1, characterized in that, The data processing and control subsystem also includes a geometric intensity index optimization module, which is used to calculate the DOP value, select time periods with lower DOP values ​​for observation, and combine satellite distribution to avoid collecting data during periods of severe obstruction.

6. The BeiDou tri-frequency signal-to-noise ratio CORS station multipath error real-time suppression system according to claim 1, characterized in that, The surface displacement monitoring subsystem includes a GNSS displacement monitoring unit and a total station robot monitoring unit. The GNSS displacement monitoring unit includes at least one GNSS monitoring reference station located at a stable location outside the deformable body, and at least three GNSS monitoring stations located at the deformation points. The total station robot monitoring unit achieves automatic measurement through remote command control, and its output deformation data is synchronously transmitted to the data processing and control subsystem. The deformation data includes the displacement rate, cumulative displacement, and deformation change period of the deformation points. The data processing and control subsystem establishes a mapping relationship between the deformation change period and the multipath interference frequency, outputs the interference frequency range and corresponding confidence parameters, and provides quantitative data support for the calculation of the adaptive weighting coefficients of the three-frequency signals.

7. The BeiDou tri-frequency signal-to-noise ratio CORS station multipath error real-time suppression system according to claim 6, characterized in that, The total station robot monitoring unit also includes a foldable total station protective cover. The protective cover is raised and lowered synchronously through the icontrol-T communication module. The protection level is not lower than IP54 and the working temperature range is -25~75℃.

8. The BeiDou tri-frequency signal-to-noise ratio CORS station multipath error real-time suppression system according to claim 1, characterized in that, The data processing and control subsystem includes a multi-constellation data processing module, a real-time quality inspection module, and a precise ephemeris processing module. The multi-constellation data processing module is equipped with a data parsing protocol, which can parse raw observation data from GPS, GLONASS, and BeiDou systems, enabling joint processing of multi-constellation data or independent processing of single BeiDou data. The real-time quality inspection module is equipped with data quality assessment rules, which can perform real-time statistics and evaluation of the completeness rate, multipath effect parameters, cycle slip ratio, and SNR of observation data. The precise ephemeris processing module is equipped with an ephemeris download interface and data retransmission logic, which can automatically download precise ephemeris data for data processing. When the reference station and control center lose network connection, it can automatically download missing data from the reference station receiver and complete the retransmission after the network is restored.

9. The BeiDou tri-frequency signal-to-noise ratio CORS station multipath error real-time suppression system according to claim 1, characterized in that, The data processing and control subsystem is equipped with an interaction and management module based on a B / S architecture. The interaction and management module includes an online map rendering unit, a user management unit, an alarm unit, a data management unit, and a log management unit. The online map rendering unit is equipped with a map interface, which can load online maps and display the location information of base stations, monitoring stations, and user terminals; the user management unit is equipped with registration and review logic, permission allocation rules, and billing statistics algorithms, which can realize user registration, hierarchical permission management, and statistics and calculation of usage time and traffic; the alarm unit is equipped with SMS and email sending interfaces, which can trigger SMS or email alarms according to preset thresholds; the data management unit is equipped with data filtering and format conversion logic, which can customize the filtering and download of observation data according to time, sampling interval, and data version, and also supports the configuration of coordinate transformation parameters and batch coordinate transformation; the log management unit is equipped with log entry and query logic, which realizes the entry, storage, and conditional query of operation and maintenance logs, inspection logs, and user login logs.

10. A real-time suppression method for multipath error of BeiDou tri-frequency signal-to-noise ratio CORS stations based on the system described in any one of claims 1-9, characterized in that, Includes the following steps: S1: Within the pumped storage project area, a BeiDou continuously operating reference station subsystem will be constructed according to the site selection requirements. The system will collect raw observation data from BeiDou tri-frequency satellites through a multi-frequency, multi-constellation GNSS receiver and a choke antenna with dynamically adjustable parameters. S2: The raw observation data is transmitted to the data processing and control subsystem via the communication subsystem. First, the output deformation data of the surface displacement monitoring subsystem, including the total station robot monitoring unit, is extracted, including the displacement rate, cumulative displacement, and deformation change period of the deformation point. Based on the preset mapping rules, the deformation change period is converted into a multipath interference frequency range and the confidence level is calculated. Then, the sensitivity thresholds of the Beidou B1, B2, and B3 signals to interference of different frequencies are determined through spectrum analysis. Dynamic weighting coefficients are calculated according to the interference frequency range and confidence level, and the three-frequency signals are weighted and fused to offset multipath errors. Finally, based on the fused data, the corresponding multipath error suppression algorithm is selected for further processing. The observation period is optimized in combination with the DOP value to generate differential correction data in standard format. S3: The GNSS displacement monitoring unit of the surface displacement monitoring subsystem acquires the three-dimensional coordinate data of the structure, and calculates the displacement value, settlement value, cumulative displacement value and displacement rate by combining the differential correction data generated by S2; at the same time, the surface displacement monitoring subsystem continuously outputs the updated deformation data and synchronously feeds it back to the data processing and control subsystem to recalculate the multipath interference frequency range and confidence level, so as to realize the real-time adjustment of the three-frequency signal adaptive weighting coefficient; S4: The data processing and control subsystem analyzes the monitoring data, monitors the system operation status in real time, triggers an alarm when the monitoring data exceeds the threshold, and provides navigation and positioning data services and coordinate transformation services to users.

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