Beidou PPP-B2b positioning compensation method and system

Abstract

The invention provides a Beidou PPP-B2b positioning compensation method and system, which are used in the field of satellite navigation, and the method comprises the steps: receiving a broadcast ephemeris, correcting the broadcast ephemeris according to a Beidou satellite PPP-B2b signal to obtain a PPP-B2b precise ephemeris, and obtaining a reference precise ephemeris; according to the PPP-B2b precise ephemeris and the reference precise ephemeris, a PPP-B2b satellite orbit error and a satellite clock error are obtained through calculation, and according to the PPP-B2b satellite orbit error and the satellite clock error, the Beidou satellite PPP-B2b global average SISRE is calculated; respectively calculating a difference SISRE sequence of each satellite epoch based on the global average SISRE of the PPP-B2b, and constructing an SISRE random model based on the difference SISRE sequence of each satellite epoch; the relation between PPP-B2b positioning precision and SISRE random model parameters is measured through experiments, and SISRE optimal process noise parameters are selected from an SISRE random model to compensate a PPP positioning model. According to the scheme, the convergence speed of PPP-B2b positioning can be increased.

Description

Technical Field

[0001] The present invention belongs to the field of satellite navigation technology, and in particular relates to a Beidou PPP-B2b positioning compensation method and system. Background Art

[0002] Using the PPP-B2b signals from three GEO satellites, BDS-3 provides users in China and surrounding areas with precise orbit, clock, and inter-symbol bias corrections for BDS-3 and other GNSS systems. This allows users to obtain centimeter- to decimeter-level position information. Experiments have shown that the precise PPP-B2b corrections effectively eliminate orbit and clock discontinuities caused by broadcast ephemeris updates. However, large satellite-specific non-zero mean biases reduce pseudorange accuracy. For example, the average signal-in-space ranging error (SISRE) STD for GPS and BDS-3 products from PPP-B2b over the two-year period from 2021 to 2023 was 0.22 ns and 0.13 ns, respectively. PPP-B2b's SISRE also exhibits satellite-specific biases consistent with the clock biases. The average root mean square error (RMS) for BDS-3 and GPS reached 0.5 m and 1.2 m, respectively.

[0003] Although PPP-B2b offers high accuracy, the constant bias in its clock error is absorbed into the pseudorange residuals and ambiguity parameters, resulting in a certain loss of positioning convergence speed. Currently, some publicly available technical solutions (publication number CN114966773B) correct the DCB differential code bias of each pseudorange observation based on PPP-B2b correction information. Satellite coordinate data and satellite clock error data are calculated based on the broadcast ephemeris navigation message. Satellite velocities are then derived from the broadcast ephemeris navigation message and observation files. The Doppler shift values ​​for each satellite and the initial receiver position are reconstructed. The target receiver position is analyzed based on all the satellite coordinate data, satellite clock error data, corrected pseudorange observations, carrier phase observations, and Doppler shift values. This approach can shorten PPP convergence time to a certain extent. However, it still does not address the problem of the constant bias in the clock error being absorbed into the pseudorange residuals and ambiguity parameters, which affects PPP-B2b positioning convergence speed. Summary of the Invention

[0004] In view of this, an embodiment of the present invention provides a BeiDou PPP-B2b positioning compensation method and system, which are used to solve the problem of slow convergence speed of current PPP-B2b positioning.

[0005] In a first aspect of an embodiment of the present invention, a BeiDou PPP-B2b positioning compensation method is provided, comprising: Receive broadcast ephemeris, correct the broadcast ephemeris according to the BeiDou satellite PPP-B2b signal to obtain PPP-B2b precise ephemeris, and obtain reference precise ephemeris; Based on the PPP-B2b precise ephemeris and the reference precise ephemeris, the PPP-B2b satellite orbit error and satellite clock error are calculated. Based on the PPP-B2b satellite orbit error and satellite clock error, the Beidou satellite PPP-B2b global average SISRE is calculated. Based on the PPP-B2b global average SISRE, the differential SISRE sequence of each satellite epoch is calculated, and the SISRE stochastic model is constructed based on the differential SISRE sequence of each satellite epoch. The relationship between the positioning accuracy of PPP-B2b and the parameters of the SISRE random model is measured experimentally, and the optimal process noise parameters of SISRE are selected in the SISRE random model to compensate the PPP positioning model.

[0006] In a second aspect of an embodiment of the present invention, a BeiDou PPP-B2b positioning compensation system is provided, including: The signal receiving module is used to receive the broadcast ephemeris, correct the broadcast ephemeris according to the Beidou satellite PPP-B2b signal to obtain the PPP-B2b precise ephemeris, and obtain the reference precise ephemeris; The error calculation module is used to calculate the PPP-B2b satellite orbit error and satellite clock error based on the PPP-B2b precise ephemeris and the reference precise ephemeris, and calculate the Beidou satellite PPP-B2b global average SISRE based on the PPP-B2b satellite orbit error and satellite clock error; The model building module is used to calculate the differential SISRE sequence of each satellite epoch based on the PPP-B2b global average SISRE, and to build a SISRE stochastic model based on the differential SISRE sequence of each satellite epoch; The positioning compensation module is used to measure the relationship between the PPP-B2b positioning accuracy and the SISRE random model parameters through experiments, and to select the SISRE optimal process noise parameters in the SISRE random model to compensate the PPP positioning model.

[0007] In a third aspect of an embodiment of the present invention, an electronic device is provided, comprising a memory, a processor, and a computer program stored in the memory and executable by the processor, wherein the processor implements the steps of the method described in the first aspect of the embodiment of the present invention when executing the computer program.

[0008] In a fourth aspect of an embodiment of the present invention, a computer-readable storage medium is provided, wherein the computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the steps of the method provided in the first aspect of the embodiment of the present invention are implemented.

[0009] In this embodiment of the present invention, a SISRE parameter is added to each satellite, random process modeling is performed on its epoch difference sequence, and appropriate process noise parameters are selected to compensate for the PPP model based on the PPP model's accuracy, thereby improving the PPP model's positioning convergence speed. Furthermore, this method is applicable to any PPP positioning model, allowing users to decide whether to use an ionosphere-free combination or a non-combination model. It effectively separates residual ephemeris and orbit errors, improving positioning accuracy and convergence. The additional computational and storage requirements are minimal, and the requirements for the receiver's internal chips are low. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments or descriptions of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0011] Figure 1 A schematic flow chart of a BeiDou PPP-B2b positioning compensation method provided in accordance with one embodiment of the present invention; Figure 2 A schematic diagram showing the relationship between the PPP positioning model accuracy and SISRE parameters provided in one embodiment of the present invention; Figure 3 A schematic structural diagram of a BeiDou PPP-B2b positioning compensation system provided by one embodiment of the present invention; Figure 4 The present invention provides a schematic structural diagram of an electronic device according to an embodiment of the present invention. DETAILED DESCRIPTION

[0012] In order to make the purpose, features, and advantages of the present invention more obvious and easy to understand, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described below are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0013] It should be understood that the terms "including" and similar expressions in the specification, claims, and drawings of the present invention are intended to cover non-exclusive inclusions. For example, a process, method, system, or apparatus comprising a series of steps or units is not limited to the listed steps or units. Furthermore, the terms "first" and "second" are used to distinguish between different objects and are not intended to describe a specific order.

[0014] See also Figure 1, a flowchart of a BeiDou PPP-B2b positioning compensation method provided by an embodiment of the present invention includes: S101, receiving broadcast ephemeris, correcting the broadcast ephemeris according to the Beidou satellite PPP-B2b signal to obtain PPP-B2b precise ephemeris, and obtaining reference precise ephemeris; PPP-B2b is a high-precision signal released by the Beidou system. It is broadcast by three Beidou geosynchronous orbit (GEO) satellites, providing high-precision services to users. Positioning receivers can receive PPP-B2b signals. The original PPP-B2b binary file is decoded and recovered according to the BDS-3 PPP-B2b ICD file to obtain the PPP-B2b precise ephemeris, which contains satellite orbit information, clock error information, and more.

[0015] The positioning receiver obtains CNAV ephemeris from the BDS-3 B1C signal and decodes LNAV ephemeris from the GPS L1 signal. For post-processing, the receiver obtains CNAV1 ephemeris from the BDS-3 official server ftp2.csno-tarc.cn and downloads GPS LNAV ephemeris from the IGS server.

[0016] Among them, the precise orbit and clock products of the same period are downloaded from the IGS Analysis Center as reference precise ephemeris.

[0017] S102. Calculate the PPP-B2b satellite orbit error and satellite clock error based on the PPP-B2b precise ephemeris and the reference precise ephemeris, and calculate the Beidou satellite PPP-B2b global average SISRE based on the PPP-B2b satellite orbit error and satellite clock error. The satellite orbit error and satellite clock error can be calculated based on the PPP-B2b precise ephemeris and the Beidou satellite ephemeris and GPS ephemeris of the same period. The precise ephemeris file can provide centimeter-level orbit accuracy, and the satellite clock error can be calculated based on the ground atomic clock and real-time satellite clock.

[0018] SISRE (signal-in-space ranging error) is the primary component of user equivalent ranging error, reflecting the impact of deviations in the navigation messages broadcast by satellites on user ranging. SISRE represents the RMS statistical value of the instantaneous SISRE for all points within the satellite's coverage area on the Earth's surface. It can be calculated based on the satellite's radial, tangential, and normal orbital errors and clock bias.

[0019] The PPP-B2b satellite orbit antenna phase center deviation is corrected according to formula (1): (1) Where, Indicates PPP-B2b ephemeris satellite Antenna phase center position, Indicates satellite Center of mass position, Indicates satellite PCO parameters, is the satellite attitude matrix, which is the nominal attitude of the satellite calculated based on the satellite position. represents the transpose of the satellite attitude matrix; The BeiDou-3 reference coordinate system (BDCS) maintains consistency with the CGCS2000 reference frame, using the 2000 epoch ITRF97. The deviation from the ITRF20 used in the reference precise ephemeris is at the centimeter level, significantly impacting orbit accuracy assessment. The orbit reference point for the reference precise ephemeris is the satellite's center of mass (CoM), while the reference point for the PPP-B2b ephemeris is the satellite's antenna phase center (APC). BDS-3 uses the B1I+B3I ionospheric-free combination, while GPS uses the L1+L2 ionospheric-free combination. Therefore, orbits must be corrected for the antenna phase center deviation before performing the interpolation.

[0020] The mean of the epoch clock error is taken as the system constant deviation and the mean of the epoch clock error is calculated according to formula (2): (2) Where, Indicates satellite navigation system of The satellite clock error of the satellite, 、 Satellite navigation systems of Satellite PPP-B2b clock error and reference clock error products, The number of satellites whose clock bias is valid at the current epoch.

[0021] After correcting for intersymbol bias during the PPP-B2b clock product recovery phase, the BDS-3 clock bias for the B1I / B3I IF combined benchmark and the GPS clock bias for the L1 / L2 IF combined benchmark were derived, maintaining consistency with the reference product clock bias. Furthermore, due to varying time constraints imposed during the clock error estimation phase, fixed time base differences still exist between clock error products from different institutions. This bias can be eliminated using the quadratic difference method, using the mean epoch clock bias as a systematic constant bias.

[0022] The PPP-B2b ground tracking stations are 12 reference stations in China. Frequent switching of the reference satellites selected for clock time will cause the clock error sequence to jump, affecting the authenticity of the clock error STD statistics. The quadratic difference sequence is smoothed by mean adjustment:

[0023]

[0024] Where, Indicates satellite The difference between the previous and next epochs of the clock error secondary difference; Among them, when the system The available satellite clock errors can be aligned and compensated when the secondary differences of the satellite clock errors have large jumps.

[0025] Specifically, the global average SISRE of each constellation satellite of PPP-B2b is calculated according to formula (3): (3) Where, PPP-B2b ephemeris satellite Global average SISRE, 、 Both represent weight factors, which are related to the satellite system and constellation type. For example, the values ​​for GPS are 0.98 and 1 / 49, the values ​​for BDS-3 medium earth orbit (MEO) satellite are 0.98 and 1 / 54, and the values ​​for IGSO are 0.99 and 1 / 126. For specific values, please refer to the literature (Multi-GNSSsignal-in-space range error assessment Methodology and results). 、 、 Represents PPP-B2b ephemeris satellite orbit errors in radial, tangential and normal components, Indicates PPP-B2b satellite The clock error component.

[0026] S103, calculating the differential SISRE sequence of each satellite epoch based on the PPP-B2b global average SISRE, and constructing a SISRE stochastic model based on the differential SISRE sequence of each satellite epoch; Epoch differencing is a technique that eliminates common errors by processing observation data from consecutive epochs. It is generally used in high-precision positioning. Its core goal is to improve positioning accuracy by eliminating systematic errors such as receiver clock errors and satellite clock errors through inter-epoch differencing. Based on the global average satellite SISRE, a sequence of SISRE differences for each satellite epoch can be obtained by performing a single epoch differencing. This sequence of SISRE differences can then be modeled using a stochastic process to produce a SISRE stochastic model, a non-deterministic mathematical model.

[0027] Optionally, the SISRE sequence of each satellite and its first-order epoch-differenced SISRE sequence are sequentially subjected to an ADF test, a Ljung-Box autocorrelation test with a predetermined lag order, and a KS test; According to the test results, the first-order epoch-differenced SISRE sequence is approximately modeled as a zero-mean Gaussian process, and the SISRE parameters are strongly constrained between epochs according to the random walk process.

[0028] The test results described above refer to the ADF test (testing time series stationarity), the autocorrelation test (determining whether the time series is a white noise process), and the KS test (determining whether the data follows a Gaussian distribution). These test results are actually discriminant results, that is, they determine which characteristic the SISRE sequence possesses. The ADF test determines whether the sequence is stationary, the autocorrelation test determines whether the time series can be considered a white noise process, and the KS test determines whether the data follows a Gaussian distribution. If the ADF test does not confirm stationarity, the SISRE sequence can be considered to have random walk characteristics. If the ADF test confirms stationarity, the autocorrelation test does not conform to the white noise distribution, and the KS test indicates a zero-mean Gaussian distribution, the SISRE sequence is considered to be a random walk process with a certain trend.

[0029] S104. Measure the relationship between the PPP-B2b positioning accuracy and the SISRE random model parameters through experiments, and select the SISRE optimal process noise parameters in the SISRE random model to compensate the PPP positioning model.

[0030] The process noise parameter is used to describe and simulate the noise characteristics of a real-world environment. In this embodiment, the process noise parameter is a parameter in the SISRE stochastic model. By conducting experimental analysis on PPP positioning accuracy and studying the impact of SISRE process noise on positioning accuracy, the optimal process noise parameter is selected to compensate for the PPP positioning model. The PPP (precise point positioning) positioning model, also known as the precise single-point positioning model, generally achieves positioning solutions using precise satellite orbit / clock products, error correction models, and parameter estimation methods.

[0031] For example, Figure 2 As shown, set the epoch time interval to the observation sampling time interval (such as 30s), with a value of 1mm / The epoch change is a step size traversal of 0-30 mm / SISRE process noise was used to test single-system positioning over a one-hour period, revealing the relationship between positioning accuracy and process noise. When a process noise value of 1 mm was selected, BDS-3 and GPS achieved optimal positioning accuracy. Compared to conventional PPP positioning results, the compensated PPP model achieved a maximum 3D accuracy improvement of approximately 5 cm.

[0032] In this embodiment, by introducing SISRE parameters on each satellite and accurately modeling the SISRE stochastic model, the residual ephemeris and clock errors can be separated from the position parameters, which not only improves the accuracy of the PPP positioning model, but also shortens the convergence time and greatly improves the applicability of PPP-B2b. It can decide whether to use the ionosphere-free combined or non-combined model. At the same time, the computational complexity and memory usage are small.

[0033] It can be understood that the global average SISRE in this embodiment captures the overall impact of satellite space segment errors on global user positioning. From the calculation formula coefficients, SISRE is primarily determined by radial orbit error and clock error. For the instantaneous SISRE at a specific user location, the spatial correlation of the satellite orbit and clock error projections is considered:

[0034] Where, The projection error of orbit and clock error in the user's line of sight direction; are the satellite orbit error vectors in the radial, tangential and normal directions; is the error projection matrix from the satellite-fixed system to the user's line of sight; is the clock error.

[0035] Nadir angle of the user-side observation signal in actual positioning satisfy , and is the radius of the earth and the altitude of the satellite orbit. Considering a smaller altitude angle threshold The signal nadir angle is further reduced to approximately . For each GNSS system, we can approximate As a result, the projected components of the tangential and normal orbit errors are significantly weakened. Therefore, the instantaneous SISRE at the user end is mainly determined by the radial orbit error and clock error, and has a similar non-zero mean bias characteristic to the global average SISRE.

[0036] Therefore, a PPP model based on SISRE compensation is proposed. Considering the stability of SISRE parameters, satellite-related Parameters, theoretically, can separate the user's line of sight residual orbit and clock error from the model residual.

[0037] Taking the non-combination model as an example, the adjusted non-combination PPP function model is: ; ; Where: and OMC (observed-minus-computed) representing pseudorange and carrier phase observations, is the correction of the user's position, is the first-order derivative of the satellite user distance at the approximate position, 、 represent the receiver clock error and satellite clock error respectively; and is the pseudorange hardware delay term at any non-reference frequency point, and denote the tropospheric projection function and the zenithal tropospheric residual wet delay, respectively; It represents the ionospheric delay caused by the first frequency signal after reforming during the propagation process; is the conversion coefficient between the ionospheric delay at other frequencies and the ionospheric delay at the first frequency; Frequency The integer ambiguity of the renormalized Its corresponding wavelength; 、 denote the observation noise of pseudorange and carrier phase observations, are the satellite-related SISRE compensation parameters.

[0038] It should be understood that the sequence numbers of the steps in the above embodiments do not imply a specific order of execution; the order of execution of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0039] Figure 3 A schematic structural diagram of a BeiDou PPP-B2b positioning compensation system provided in an embodiment of the present invention includes: The signal receiving module 310 is used to receive the broadcast ephemeris, correct the broadcast ephemeris according to the Beidou satellite PPP-B2b signal to obtain the PPP-B2b precise ephemeris, and obtain the reference precise ephemeris; The error calculation module 320 is used to calculate the PPP-B2b satellite orbit error and satellite clock error based on the PPP-B2b precise ephemeris and the reference precise ephemeris, and calculate the Beidou satellite PPP-B2b global average SISRE based on the PPP-B2b satellite orbit error and satellite clock error; Optionally, the calculating, based on the PPP-B2b precise ephemeris and the reference precise ephemeris, to obtain the PPP-B2b satellite orbit error and the satellite clock error further includes: Correct the PPP-B2b satellite orbit antenna phase center deviation according to formula (1): (1) Where, Indicates PPP-B2b ephemeris satellite Antenna phase center position, Indicates satellite Center of mass position, Indicates satellite PCO parameters, is the satellite attitude matrix, which is the nominal attitude of the satellite calculated based on the satellite position. represents the transpose of the satellite attitude matrix; The mean of the epoch clock error is taken as the system constant deviation and the mean of the epoch clock error is calculated according to formula (2): (2) Where, Indicates satellite navigation system of The satellite clock error of the satellite, 、 Satellite navigation systems of Satellite PPP-B2b clock error and reference clock error products, The number of satellites whose clock bias is valid at the current epoch.

[0040] The global average SISRE of each constellation satellite of PPP-B2b is calculated according to formula (3): (3) Where, PPP-B2b ephemeris satellite Global average SISRE, 、 Both represent weight factors, which are related to the satellite system and constellation type. 、 、 Represents PPP-B2b ephemeris satellite orbit errors in radial, tangential and normal components, Indicates PPP-B2b satellite The clock error component.

[0041] The model construction module 330 is used to calculate the differential SISRE sequence of each satellite epoch based on the PPP-B2b global average SISRE, and to construct a SISRE stochastic model based on the differential SISRE sequence of each satellite epoch; Optionally, the SISRE sequence of each satellite and its first-order epoch-difference SISRE sequence are sequentially subjected to an ADF test, a Ljung-Box autocorrelation test with a predetermined lag order, and a KS test; based on the test results, the first-order epoch-difference SISRE sequence is approximately modeled as a zero-mean Gaussian process, and the SISRE parameters are strongly constrained between epochs according to a random walk process.

[0042] The positioning compensation module 340 is used to measure the relationship between the PPP-B2b positioning accuracy and the SISRE random model parameters through experiments, and select the SISRE optimal process noise parameters in the SISRE random model to compensate the PPP positioning model.

[0043] Those skilled in the art will clearly understand that, for the convenience and brevity of description, the specific working processes of the above-described systems and modules can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0044] Figure 4 1 is a schematic diagram of the structure of an electronic device provided by an embodiment of the present invention. The electronic device is used to optimize the PPP model positioning. Figure 4 As shown, the electronic device 4 of this embodiment includes: a memory 410, a processor 420 and a system bus 430, and the memory 410 includes an executable program 4101 stored thereon. It can be understood by those skilled in the art that Figure 4 The electronic device structure shown in the figure does not constitute a limitation to the electronic device, and may include more or fewer components than shown in the figure, or combine certain components, or arrange the components differently.

[0045] The following combination Figure 4 A detailed introduction to the various components of electronic equipment: Memory 410 can be used to store software programs and modules. Processor 420 executes the software programs and modules stored in memory 410 to perform various functional applications and data processing of the electronic device. Memory 410 may primarily include a program storage area and a data storage area. The program storage area may store an operating system and at least one application required for a function (such as sound playback or image playback). The data storage area may store data generated based on the use of the electronic device (such as cached data). Memory 410 may also include high-speed random access memory and non-volatile memory, such as at least one disk storage device, flash memory device, or other volatile solid-state memory device.

[0046] The memory 410 includes an executable program 4101 for the interface generation method. The executable program 4101 can be divided into one or more modules / units. The one or more modules / units are stored in the memory 410 and executed by the processor 420 to implement PPP model positioning compensation, etc. The one or more modules / units can be a series of computer program instruction segments that can perform specific functions. The instruction segments are used to describe the execution process of the executable program 4101 in the electronic device 4. For example, the executable program 4101 can be divided into functional modules such as a signal receiving module, an error calculation module, a model construction module, and a positioning compensation module.

[0047] Processor 420 is the control center of the electronic device, connecting the various components of the entire electronic device using various interfaces and lines. By running or executing software programs and / or modules stored in memory 410 and accessing data stored in memory 410, it performs various functions of the electronic device and processes data, thereby monitoring the overall status of the electronic device. Optionally, processor 420 may include one or more processing units; preferably, processor 420 may integrate an application processor and a modem processor, wherein the application processor primarily processes the operating system, application programs, etc., and the modem processor primarily handles wireless communications. It is understood that the modem processor described above may not be integrated into processor 420.

[0048] The system bus 430 connects the various functional components within the computer and can transmit data, address information, and control information. It can be a PCI bus, an ISA bus, a CAN bus, or other types. Instructions from the processor 420 are transmitted to the memory 410 via the bus, and the memory 410 feeds data back to the processor 420. The system bus 430 is responsible for the exchange of data and instructions between the processor 420 and the memory 410. Of course, the system bus 430 can also connect to other devices, such as network interfaces and display devices.

[0049] In an embodiment of the present invention, the executable program executed by the processing 420 included in the electronic device includes: Receive broadcast ephemeris, correct the broadcast ephemeris according to the BeiDou satellite PPP-B2b signal to obtain PPP-B2b precise ephemeris, and obtain reference precise ephemeris; Based on the PPP-B2b precise ephemeris and the reference precise ephemeris, the PPP-B2b satellite orbit error and satellite clock error are calculated. Based on the PPP-B2b satellite orbit error and satellite clock error, the Beidou satellite PPP-B2b global average SISRE is calculated. Based on the PPP-B2b global average SISRE, the differential SISRE sequence of each satellite epoch is calculated, and the SISRE stochastic model is constructed based on the differential SISRE sequence of each satellite epoch. The relationship between the positioning accuracy of PPP-B2b and the parameters of the SISRE random model is measured experimentally, and the optimal process noise parameters of SISRE are selected in the SISRE random model to compensate the PPP positioning model.

[0050] Those skilled in the art will clearly understand that, for the convenience and brevity of description, the specific working processes of the above-described systems, devices, and modules can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0051] In the above embodiments, the description of each embodiment has its own focus. For parts that are not described or recorded in detail in a certain embodiment, reference can be made to the relevant description of other embodiments.

[0052] As described above, the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that the technical solutions described in the above embodiments can still be modified, or some of the technical features thereof can be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A BeiDou PPP-B2b positioning compensation method, characterized in that: include: Receive broadcast ephemeris, correct the broadcast ephemeris according to the BeiDou satellite PPP-B2b signal to obtain PPP-B2b precise ephemeris, and obtain reference precise ephemeris; Based on the PPP-B2b precise ephemeris and the reference precise ephemeris, the PPP-B2b satellite orbit error and satellite clock error are calculated. Based on the PPP-B2b satellite orbit error and satellite clock error, the Beidou satellite PPP-B2b global average SISRE is calculated. Based on the PPP-B2b global average SISRE, the differential SISRE sequence of each satellite epoch is calculated, and the SISRE stochastic model is constructed based on the differential SISRE sequence of each satellite epoch. The relationship between the positioning accuracy of PPP-B2b and the parameters of the SISRE random model is measured experimentally, and the optimal process noise parameters of SISRE are selected in the SISRE random model to compensate the PPP positioning model.

2. The method according to claim 1, characterized in that The step of calculating the PPP-B2b satellite orbit error and the satellite clock error based on the PPP-B2b precise ephemeris and the reference precise ephemeris further includes: Correct the PPP-B2b satellite orbit antenna phase center deviation according to formula (1): （1） Where, Indicates PPP-B2b ephemeris satellite Antenna phase center position, Indicates satellite Center of mass position, Indicates satellite PCO parameters, is the satellite attitude matrix, which is the nominal attitude of the satellite calculated based on the satellite position. represents the transpose of the satellite attitude matrix; The mean of the epoch clock error is taken as the system constant deviation and the mean of the epoch clock error is calculated according to formula (2): （2） Where, Indicates satellite navigation system of The satellite clock error of the satellite, 、 Satellite navigation systems of Satellite PPP-B2b clock error and reference clock error products, The number of satellites whose clock bias is valid at the current epoch.

3. The method according to claim 1, characterized in that Calculating the BeiDou satellite PPP-B2b global average SISRE based on the PPP-B2b satellite orbit error and the satellite clock error includes: The global average SISRE of each constellation satellite of PPP-B2b is calculated according to formula (3): （3） Where, PPP-B2b ephemeris satellite Global average SISRE, 、 Both represent weight factors, which are related to the satellite system and constellation type. 、 、 Represents PPP-B2b ephemeris satellite orbit errors in radial, tangential and normal components, Indicates PPP-B2b satellite The clock error component.

4. The method according to claim 1, wherein The constructing of the SISRE random model based on the SISRE sequence of satellite epoch differences includes: The SISRE sequence of each satellite and its first-order epoch-difference SISRE sequence are subjected to ADF test, Ljung-Box autocorrelation test with a predetermined lag order, and KS test in sequence. Based on the test results, the first-order epoch-difference SISRE sequence is approximately modeled as a zero-mean Gaussian process, and the SISRE parameters are strongly constrained between epochs according to the random walk process.

5. A BeiDou PPP-B2b positioning compensation system, characterized in that: include: The signal receiving module is used to receive the broadcast ephemeris, correct the broadcast ephemeris according to the Beidou satellite PPP-B2b signal to obtain the PPP-B2b precise ephemeris, and obtain the reference precise ephemeris; The error calculation module is used to calculate the PPP-B2b satellite orbit error and satellite clock error based on the PPP-B2b precise ephemeris and the reference precise ephemeris, and calculate the Beidou satellite PPP-B2b global average SISRE based on the PPP-B2b satellite orbit error and satellite clock error; The model building module is used to calculate the differential SISRE sequence of each satellite epoch based on the PPP-B2b global average SISRE, and to build a SISRE stochastic model based on the differential SISRE sequence of each satellite epoch; The positioning compensation module is used to measure the relationship between the PPP-B2b positioning accuracy and the SISRE random model parameters through experiments, and to select the SISRE optimal process noise parameters in the SISRE random model to compensate the PPP positioning model.

6. The system according to claim 5, characterized in that The calculation of satellite orbit error and satellite clock error based on the precise ephemeris file and the Beidou satellite ephemeris and GPS ephemeris of the same period also includes: Correct the PPP-B2b satellite orbit antenna phase center deviation according to formula (1): （1） Where, Indicates PPP-B2b ephemeris satellite Antenna phase center position, Indicates satellite Center of mass position, Indicates satellite PCO parameters, is the satellite attitude matrix, which is the nominal attitude of the satellite calculated based on the satellite position. represents the transpose of the satellite attitude matrix; The mean of the epoch clock error is taken as the system constant deviation and the mean of the epoch clock error is calculated according to formula (2): （2） Where, Indicates satellite navigation system of The satellite clock error of the satellite, 、 Satellite navigation systems of Satellite PPP-B2b clock error and reference clock error products, The number of satellites whose clock bias is valid at the current epoch.

7. The system according to claim 5, characterized in that Calculating the BeiDou satellite global average SISRE based on the satellite orbit error and the satellite clock error includes: The global average SISRE of each constellation satellite of PPP-B2b is calculated according to formula (3): （3） Where, PPP-B2b ephemeris satellite Global average SISRE, 、 Both represent weight factors, which are related to the satellite system and constellation type. 、 、 Represents PPP-B2b ephemeris satellite orbit errors in radial, tangential and normal components, Indicates PPP-B2b satellite The clock error component.

8. The system according to claim 5, characterized in that The constructing of the SISRE random model based on the SISRE sequence of satellite epoch differences includes: The SISRE sequence of each satellite and its first-order epoch-difference SISRE sequence are subjected to ADF test, Ljung-Box autocorrelation test with a predetermined lag order, and KS test in sequence. Based on the test results, the first-order epoch-difference SISRE sequence is approximately modeled as a zero-mean Gaussian process, and the SISRE parameters are strongly constrained between epochs according to the random walk process.

9. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein: When the processor executes the computer program, the steps of the Beidou PPP-B2b positioning compensation method as described in any one of claims 1 to 4 are implemented.

10. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed, the steps of the Beidou PPP-B2b positioning compensation method as described in any one of claims 1 to 4 are implemented.

Images