Real-time redundant GPS and Beidou dual-system PPP-B2b positioning method

Abstract

The application belongs to the technical field of satellite positioning. The application provides a real-time redundant GPS and Beidou dual-system PPP-B2b positioning method. The method comprises the following steps: acquiring GEO satellite PPP-B2b information of C59 and C61 in real time, correcting broadcast ephemeris data broadcast by GPS and Beidou satellites by using a redundant method, so as to obtain high-precision satellite orbit broadcast ephemeris, combining pseudo-code and carrier phase observation values sent by GPS satellites and Beidou satellites, and calculating clock difference in real time by using a PPP algorithm to obtain real-time positioning results. According to the embodiment of the application, PPP cannot be solved due to insufficient availability of PPP-B2b information in a continuous time period of observation data, so that the epoch of the solution is more complete.

Description

Technical Field

[0001] This disclosure relates to the field of satellite positioning technology, and in particular to a real-time redundant GPS and BeiDou dual-system PPP-B2b positioning method. Background Technology

[0002] The BeiDou-3 satellite navigation system was officially completed in 2020. Its geostationary orbit (GEO) satellites can broadcast PPP-B2b signals in real time. These PPP-B2b signals carry precise satellite information, which can be used to correct satellite orbits, thereby achieving more accurate precise point positioning (PPP). PPP-B2b technology solves the lag problem of traditional methods using post-hoc precise ephemeris for precise point positioning, and also overcomes many drawbacks such as network interruptions and lack of network infrastructure when broadcasting satellite correction data over a network.

[0003] However, the C59 satellite of the BeiDou-3 system broadcasts the same PPP-B2b information synchronously, which is unstable and sometimes results in signal loss. Summary of the Invention

[0004] To avoid the shortcomings of existing technologies, this invention provides a real-time redundant GPS and BeiDou dual-system PPP-B2b positioning method to solve the problem in existing technologies where the simultaneous broadcast of the same PPP-B2b information by the C59 satellite is unstable and signals are frequently lost.

[0005] According to embodiments of this disclosure, a real-time redundant GPS and BeiDou dual-system PPP-B2b positioning method is provided, the method comprising:

[0006] Acquire observational data, satellite ephemeris data, and B2b message data;

[0007] The position of each satellite at the observation time is calculated based on the observation data and the satellite ephemeris data;

[0008] Based on the redundancy method, the location is corrected using the B2b message data to obtain the corrected location;

[0009] The corrected position is precisely calculated using single-point positioning to obtain the target coordinates of the receiver.

[0010] Furthermore, the steps for acquiring observational data, satellite ephemeris data, and B2b message data include:

[0011] The receiver is used to acquire the observation data; wherein the observation data includes observation values ​​such as carrier phase and pseudorange;

[0012] The receiver is used to receive the satellite ephemeris data; wherein the satellite ephemeris data includes orbital information and time information for each satellite;

[0013] The receiver is used to receive B2b message data from the satellite; wherein the B2b message data includes satellite orbit corrections.

[0014] Furthermore, the PPP-B2b message includes the first PPP-B2b message information from the C59 satellite and the second PPP-B2b message information from the C61 satellite.

[0015] Furthermore, the step of calculating the position of each satellite at the observation time based on the observation data and the satellite ephemeris data includes:

[0016] Based on the observation data, the orbital parameters, the time information, the Earth's gravitational field, and the solar radiation pressure, the position of each satellite at the observation time is calculated.

[0017] Furthermore, the step of correcting the position using the B2b message based on the redundancy method to obtain the corrected position includes:

[0018] Determine whether the signal of the C59 satellite is missing or interfered with;

[0019] If the signal of the C59 satellite is intact or not interfered with, the position is corrected using the correction array in the first PPP-B2b message information of the C59 satellite;

[0020] If the signal of the C59 satellite is lost or interfered with, the position is corrected using the correction array in the second PPP-B2b message information of the C61 satellite.

[0021] Furthermore, the correction array includes:

[0022] Inter-symbol deviation correction and satellite orbit correction.

[0023] Furthermore, the step of performing precise single-point positioning calculation on the corrected position to obtain the target coordinates of the receiver includes:

[0024] The receiver parameters, tropospheric delay, ionospheric delay, and multipath effects at the corrected position are estimated using a Kalman filter and the least squares method.

[0025] The estimated results are subjected to residual testing. If the residual is greater than a preset threshold, it is judged as a gross error. After removing the gross error, the receiver parameters, the stromal delay, the ionospheric delay, and the multipath effect are re-estimated. If the residual is less than the threshold, the target coordinates of the receiver are output.

[0026] The technical solutions provided by the embodiments of this disclosure may include the following beneficial effects:

[0027] In the embodiments of this disclosure, the aforementioned real-time redundant GPS and BeiDou dual-system PPP-B2b positioning method achieves two main benefits. First, by using the real-time acquired PPP-B2b information from the C59 and C61 GEO satellites, a redundancy method is employed to correct the broadcast ephemeris data from GPS and BeiDou satellites, thereby obtaining high-precision satellite orbit broadcast ephemeris. Combined with the pseudocode and carrier phase observations transmitted by GPS and BeiDou satellites, the PPP algorithm is used to calculate the real-time positioning result. Second, this method avoids the inability to calculate PPP due to insufficient availability of PPP-B2b information within a continuous time period of observation data, thus ensuring a more complete epochal resolution. Attached Figure Description

[0028] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this disclosure and, together with the description, serve to explain the principles of this disclosure. It is obvious that the drawings described below are merely some embodiments of this disclosure, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort.

[0029] Figure 1 The diagram illustrates the steps of a real-time redundant GPS and BeiDou dual-system PPP-B2b positioning method in an exemplary embodiment of this disclosure.

[0030] Figure 2 A detailed flowchart of the real-time redundant GPS and BeiDou dual-system PPP-B2b positioning method in an exemplary embodiment of this disclosure is shown.

[0031] Figure 3 The PPP-B2b positioning error curve is shown in the positioning experiment of the exemplary embodiment of this disclosure. Detailed Implementation

[0032] Exemplary embodiments will now be described more fully with reference to the accompanying drawings. However, these exemplary embodiments can be implemented in many forms and should not be construed as limited to the examples set forth herein; rather, they are provided so that this disclosure will be more comprehensive and complete, and will fully convey the concept of the exemplary embodiments to those skilled in the art. The described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

[0033] Furthermore, the accompanying drawings are merely illustrative diagrams of embodiments of this disclosure and are not necessarily drawn to scale. The same reference numerals in the drawings denote the same or similar parts, and therefore repeated descriptions of them will be omitted. Some block diagrams shown in the drawings are functional entities and do not necessarily correspond to physically or logically independent entities.

[0034] This example implementation provides a real-time redundant GPS and BeiDou dual-system PPP-B2b positioning method. (See reference...) Figure 1 As shown, the real-time redundant GPS and BeiDou dual-system PPP-B2b positioning method may include steps S101 to S104.

[0035] Step S101: Acquire observation data, satellite ephemeris data, and B2b message data;

[0036] Step S102: Calculate the position of each satellite at the observation time based on the observation data and the satellite ephemeris data;

[0037] Step S103: Based on the redundancy method, the location is corrected using the B2b message data to obtain the corrected location;

[0038] Step S104: Perform precise single-point positioning calculation on the corrected position to obtain the target coordinates of the receiver.

[0039] The aforementioned real-time redundant GPS and BeiDou dual-system PPP-B2b positioning method achieves two key benefits. First, by acquiring real-time PPP-B2b information from GEO satellites C59 and C61, a redundancy method is used to correct the broadcast ephemeris data from GPS and BeiDou satellites, resulting in high-precision satellite orbit broadcast ephemeris. Combined with pseudocode and carrier phase observations transmitted by GPS and BeiDou satellites, the PPP algorithm is used to calculate the real-time positioning result. Second, it avoids the inability to calculate PPP due to insufficient availability of PPP-B2b information within continuous observation periods, thus ensuring a more complete epochal resolution.

[0040] Below, we will refer to Figures 1 to 3 The steps of the real-time redundant GPS and BeiDou dual-system PPP-B2b positioning method described in this example embodiment will be explained in more detail.

[0041] In step S101, as Figure 2 As shown, firstly, the receiver acquires observation data, including carrier phase and pseudorange observations. Simultaneously, the receiver obtains satellite ephemeris data from the navigation satellites, which includes satellite orbit and time information. Furthermore, the receiver also needs to obtain PPP-B2b messages from the C59 and C61 satellites, which contain high-precision parameters for correction.

[0042] Specifically, high-precision GNSS receivers are used to acquire observation data, including carrier phase and pseudorange measurements. This data reflects the distance information between the receiver and each satellite, serving as the basis for subsequent positioning calculations.

[0043] The receiver receives satellite ephemeris data from the BeiDou-3 navigation satellites. Ephemeris data includes orbital and time information for each satellite, accurately describing its spatial position at any given time. The acquired ephemeris data will be used to calculate the satellites' real-time positions.

[0044] The receiver receives PPP-B2b messages from both C59 and C61 satellites. These PPP-B2b messages contain high-precision satellite orbit corrections, obtained through precise measurements and calculations by ground monitoring stations. The PPP-B2b messages from C59 and C61 satellites differ in content, allowing the receiver to distinguish and process both types of messages.

[0045] In precise point positioning, the observation equations for the observation data can be divided into pseudorange observation equations and carrier phase observation equations, expressed as formula (1):

[0046]

[0047] Where: s represents the satellite; r represents the receiver; i represents the signal frequency; and These represent the carrier phase and pseudorange observations, respectively. dt is the distance from the satellite to the receiver. r dT is the receiver clock difference at the time the signal arrives at the receiver. s The satellite clock difference at the time the satellite transmits the signal; This indicates ionospheric delay caused by signal frequency. The frequency is f i The signal is delayed by the ionosphere in the propagation path; Let be the projection function of the signal from the satellite to the receiver. λ represents the zenith tropospheric delay of the receiver; i The frequency is f i The wavelength of the carrier phase observation, d r,iFor the receiver's hardware delay, Due to hardware latency at the satellite end, For the ambiguity of the carrier phase, and These represent the unrecovered errors in carrier phase and pseudorange, respectively.

[0048] Ionospheric delay, a major source of error in precise point positioning observations, can be corrected using an ionospheric-free model to address the delay caused by GNSS signals passing through the ionosphere. The following discussion uses a frequency of f... i and f j Taking the signal as an example, the corresponding dual-frequency deionization model is Equation (2):

[0049]

[0050] Substituting formula (1) into formula (2) yields formula (3):

[0051]

[0052] The variables in formula (3) can be expressed using formula (4):

[0053]

[0054] In step S102, as Figure 2 As shown, using the acquired satellite ephemeris data, the receiver calculates the approximate position of each satellite at the time of observation. This calculation needs to take into account the satellite's orbital parameters, time information, and other factors that may affect the satellite's position, such as the Earth's gravitational field and solar radiation pressure.

[0055] In step S103, as Figure 2 As shown, PPP-B2b messages were obtained from C59 and C61 satellites, containing satellite orbital corrections Δr. i (t).

[0056] Calculate satellite position r using ephemeris data i (t):

[0057]

[0058] in It is the initial satellite position provided in the ephemeris data.

[0059] The satellite positions are corrected based on the correction values ​​in the PPP-B2b message. The C59 satellite is the primary signal source; when the C59 signal is missing or interfered with, the C61 signal is switched on.

[0060] r i (t)=r i,C59(t)if available,elser i,C61 (t)

[0061] Specifically, corrections from PPP-B2b messages received from C59 and C61 satellites are used to correct the calculated satellite positions. Specifically, the receiver initially uses PPP-B2b information broadcast from C59 satellite for correction; when the C59 signal is missing or interfered with, it automatically switches to PPP-B2b information broadcast from C61 satellite for alternative correction. This method maximizes the availability and accuracy of the corrections.

[0062] The three methods for calculating PPP-B2b corrections are as follows:

[0063] (1) Inter-symbol deviation correction:

[0064] Due to the different satellite tracking modes, each observation contains a bias related to the signal tracking mode. When processing various signals of different frequencies synchronously, this bias needs to be eliminated first to achieve synchronous processing of various signals. The correction algorithm is shown in formula (5):

[0065]

[0066] In the formula: The observed values ​​are corrected for the sig signal; l sig The observations are directly captured by the SIG signal receiver; DCB sig This corresponds to the inter-symbol deviation of the signal.

[0067] (2) Satellite orbit corrections:

[0068] The orbital correction method uses the coarser satellite position and velocity calculated from the broadcast ephemeris, plus the orbital correction parameters broadcast in PPP-B2b, to obtain the precise ephemeris recovered by PPP-B2b.

[0069] The orbital correction information includes parameters such as the radial, tangential, and normal components of the orbital correction vector δO. The orbital correction values ​​are used to calculate the satellite position correction vector δX, and are also used in conjunction with the satellite position vector X calculated from the broadcast ephemeris. broadcast The corrected calculation formula is shown in formula (6):

[0070] X orbit =X broadcast -δX (6)

[0071] In formula (6), X orbit To achieve a more accurate satellite position after correction, X broadcastThe satellite position is calculated from the broadcast ephemeris. δX represents the satellite orbit correction, and the formula for calculating the δX correction is as follows:

[0072]

[0073]

[0074] e along =e cross ×e radial (9)

[0075] δX=[e radial e along e cross ]·δO (10)

[0076] In the above formula: r = X broadcast For broadcast ephemeris satellite position vectors; e is the satellite velocity vector for broadcast ephemeris; i δO is the direction unit vector, i = {radial, along, cross} corresponding to the radial, tangential, and normal directions respectively; δO is the track correction vector obtained from the PPP information, with the radial, tangential, and normal components in that order.

[0077] In step S104, as Figure 2 As shown, precise point positioning (PPP) calculation is performed using the corrected satellite position to obtain the receiver's accurate coordinates. This method not only improves positioning accuracy but also enhances the system's reliability and stability in various environments.

[0078] Specifically, the receiver parameters, stromal delay, ionospheric delay, and multipath effect in the corrected position are estimated using a Kalman filter and the least squares method. The estimation results are then subjected to residual testing. If the residual is greater than a preset threshold, it is judged as a gross error. After removing the gross error, the receiver parameters, stromal delay, ionospheric delay, and multipath effect are re-estimated. If the residual is less than the threshold, the target coordinates of the receiver are output.

[0079] Using precise satellite orbit data throughout the calculation process significantly improves the accuracy of the positioning results. By combining the PPP-B2b signals from C59 and C61 satellites, not only is positioning accuracy enhanced, but the stability and reliability of the system are also improved in various environments.

[0080] In a specific embodiment, an example experiment was conducted using IGS-based GAMG stations distributed across a certain country. The station receiver model was Sept Polarx5TR, the antenna type was LEIAR25.R4LEIT, and the date was specified in the original text. The experiment employed a BDS-3B1I / B3I ionospheric-free combination and a BDS-3B1I / B3I+GPS L1 / L2 ionospheric-free combination to study PPP-B2b redundancy positioning for C59 and C61, and used the IGS cycle solution results as a reference to obtain the following results: Figure 3 The results show the error in the three directions of northeast and sky.

[0081] Precise satellite positions are obtained by correcting the satellite positions calculated from the navigation messages using PPP-B2b products. Ionospheric delay is eliminated using a dual-frequency ionospheric-free combination to remove ionospheric effects, and an extended Kalman filter (EDF), a recursive filtering algorithm, is used for parameter estimation to estimate the system state and update the state and correct errors based on measurement data. IGS14.atx is also used to eliminate the phase center-to-centroid deviation.

[0082] from Figure 3 The positioning results show that the positioning convergence was completed after 30 minutes. The error after convergence fluctuated within 10cm. The solution epochs were complete and there were no missing solution phenomena.

[0083] The aforementioned real-time redundant GPS and BeiDou dual-system PPP-B2b positioning method achieves two key benefits. First, by acquiring real-time PPP-B2b information from GEO satellites C59 and C61, a redundancy method is used to correct the broadcast ephemeris data from GPS and BeiDou satellites, resulting in high-precision satellite orbit broadcast ephemeris. Combined with pseudocode and carrier phase observations transmitted by GPS and BeiDou satellites, the PPP algorithm is used to calculate the real-time positioning result. Second, it avoids the inability to calculate PPP due to insufficient availability of PPP-B2b information within continuous observation periods, thus ensuring a more complete epochal resolution.

[0084] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this disclosure. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. In addition, those skilled in the art can combine and integrate the different embodiments or examples described in this specification.

[0085] Other embodiments of this disclosure will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of this disclosure that follow the general principles of this disclosure and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of this disclosure are indicated by the appended claims.

Claims

1. A real-time redundant GPS and BeiDou dual-system PPP-B2b positioning method, characterized in that, The method includes: Acquire observation data, satellite ephemeris data, and PPP-B2b messages from the GPS and BeiDou systems; among which, the PPP-B2b messages include the first PPP-B2b message information from the C59 satellite and the second PPP-B2b message information from the C61 satellite. The position of each satellite at the time of observation is calculated based on observation data and satellite ephemeris data; Based on a redundancy method, the position is corrected using PPP-B2b messages to obtain a corrected position. Specifically, this includes: determining whether the C59 satellite signal is missing or interfered with; if the C59 satellite signal is intact or not interfered with, the position is corrected using the correction array in the first PPP-B2b message information of the C59 satellite; if the C59 satellite signal is missing or interfered with, the position is corrected using the correction array in the second PPP-B2b message information of the C61 satellite; wherein, the correction array includes inter-symbol offset correction and satellite orbit correction. A precise single-point positioning calculation is performed on the corrected position to obtain the target coordinates of the receiver.

2. The real-time redundant GPS and BeiDou dual-system PPP-B2b positioning method according to claim 1, characterized in that, The steps for acquiring observational data, satellite ephemeris data, and PPP-B2b messages include: The receiver is used to acquire observation data, which includes observations such as carrier phase and pseudorange. The receiver receives satellite ephemeris data; the satellite ephemeris data includes the orbital information and time information of each satellite. The receiver receives the PPP-B2b message from the satellite; the PPP-B2b message includes satellite orbit corrections.

3. The real-time redundant GPS and BeiDou dual-system PPP-B2b positioning method according to claim 2, characterized in that, The steps for calculating the position of each satellite at the observation time based on observation data and satellite ephemeris data include: Based on observation data, orbital parameters, time information, Earth's gravitational field, and solar radiation pressure, the position of each satellite at the observation time is calculated.

4. The real-time redundant GPS and BeiDou dual-system PPP-B2b positioning method according to claim 3, characterized in that, The step of performing precise single-point positioning calculation on the corrected position to obtain the target coordinates of the receiver includes: The receiver parameters, tropospheric delay, ionospheric delay, and multipath effects at the corrected position are estimated using a Kalman filter and the least squares method. The estimated results are subjected to residual testing. If the residual is greater than the preset threshold, it is judged as a gross error. After removing the gross error, the receiver parameters, stromal delay, ionospheric delay and multipath effect are re-estimated. If the residual is less than the threshold, the target coordinates of the receiver are output.

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