Combined positioning method and system of double-satellite-based real-time precise single-point positioning system

Abstract

The invention discloses a double-satellite-based real-time precise single-point positioning system combined positioning method, which synchronously receives and decodes real-time satellite orbits, clock correction and code deviation correction of PPP-B2b and HAS, and realizes real-time precise single-point positioning of a user side combined with GPS + BDS-3 + Galileo three systems through strategies such as orbital combination and clock correction optimization and switching. In the aspect of orbit correction, two satellite-based PPP orbit product references are unified through a Helmert similarity transformation model, and a combined orbit product is generated by adopting a weight adjustment strategy combining a priori fixed weight and a posterior fixed weight. In the aspect of the clock correction number, aiming at the problem that different satellite-based correction numbers are inconsistent in time reference, clock correction type consistency detection between a front epoch and a rear epoch is carried out, and ambiguity parameters of corresponding satellites are reset in time.

Description

Technical Field

[0001] The present invention belongs to the field of Beidou / GNSS precise data processing and high-precision satellite navigation and positioning, and particularly relates to a combined positioning method for a dual-satellite-based real-time precise point positioning (PPP) system based on Beidou PPP-B2b and Galileo HAS. Background Technique

[0002] The global satellite navigation system provides high-precision and high-frequency spatio-temporal information for human production and life, creating huge social and economic value. As an important high-precision positioning technology, Precise Point Positioning (PPP) technology has been limited to the post-processing mode for a long time since its first proposal in the 1990s due to certain delays in obtaining precise orbit, clock offset and other products. With the development of Internet communication technology, real-time PPP technology based on Internet communication links has been realized. At present, the International GNSS Service (IGS) has successively provided real-time satellite orbit and clock offset products and broadcast them to users through the Internet network. Although this real-time PPP solution has the advantages of low cost and global coverage, it needs to rely on ground communication network services and cannot be applied in areas with weak Internet infrastructure such as deserts and oceans. To solve this problem, some commercial companies currently use Geosynchronous Orbit (GEO) satellites to broadcast high-precision real-time precise correction products to users, but the commercial solutions are relatively expensive.

[0003] In recent years, major global satellite navigation systems have successively launched their respective high-precision PPP services, such as the Beidou-3 system (BDS-3) and the Galileo system. Currently, the BDS-3 and Galileo systems began to provide open and free real-time PPP services in 2020 and 2023 respectively, namely the PPP-B2b service based on the B2b signal and the Galileo High Accuracy Service (HAS) based on the E6-B signal. They use the navigation satellite signal as the correction broadcast channel, which is not affected by network fluctuations and interruptions. However, compared with the real-time service (RTS) transmitted over the Internet, the accuracy of satellite-based real-time orbits and clock offsets is relatively poor. On the other hand, the satellite systems and the number of satellites supported by a single augmentation system are limited, and it is difficult to further improve the positioning accuracy. Moreover, when applying a single satellite-based PPP correction product, it is prone to abnormal situations such as interruption and error of the correction product due to server failures, satellite broadcast links, and signal interference at the user end, resulting in an increased risk of real-time PPP positioning continuity. Therefore, how to integrate multiple satellite-based PPP precise products, optimize and fuse multi-satellite-based orbit and clock offset products, and achieve joint precise positioning is crucial for improving positioning accuracy, reliability, etc. Summary of the Invention

[0004] Aiming at the problems of insufficient accuracy, reliability, and continuity of current positioning using a single satellite-based PPP correction, the present invention designs a processing strategy for orbit and clock offset corrections in joint positioning, and proposes a method for satellite-based PPP positioning of the GPS+BDS-3+Galileo three systems by combining PPP-B2b and Galileo HAS, effectively improving the positioning service performance of the satellite-based PPP user terminal.

[0005] According to one aspect of the specification of the present invention, there is provided a method for joint positioning of a dual satellite-based real-time precise point positioning system, including:

[0006] Step 1, obtain and decode the PPP-B2b and Galileo HAS navigation augmentation message information received synchronously, perform time matching on the satellite-based augmentation orbit and clock offset corrections and the corresponding broadcast ephemeris orbit and clock products, and restore the complete precise satellite orbits and satellite clock products of all available satellites at the current epoch;

[0007] Step 2, construct a common satellite subset of the real-time correction products provided by Beidou PPP-B2b and Galileo HAS at the current epoch, and preprocess the orbit products of the common satellite subset to eliminate abnormal situations, and obtain the "clean" orbit products of the common satellite subset of the two satellite-based PPP systems;

[0008] Step 3: Generate the combined orbits of the common satellites based on the common satellite subset, and calculate the coordinate datum transformation parameters between the combined orbit products of the common satellite subset and the space-based PPP orbit products;

[0009] Step 4: Use the coordinate datum transformation parameters calculated in Step 3 to transfer the orbit products of all non-common satellites to the same coordinate reference frame as the combined orbit products of the common satellites;

[0010] Step 5: Correct the differences between the combined orbits and the B2b / HAS orbits to their respective satellite clock difference products;

[0011] Step 6: When the clock difference corrections used for the positioning of the dual space-based systems are switched, perform a consistency detection of the clock difference types between the previous and current epochs for the space-based satellite clock differences, and reset the ambiguities of the satellites that fail the detection;

[0012] Step 7: Use the corrected precise orbits and clock difference corrections provided in Step 5 and Step 6 to achieve precise positioning of the combined dual space-based PPP system.

[0013] As a further technical solution, Step 1 further includes:

[0014] Simultaneously receive the real-time corrections of both the PPP-B2b and HAS space-based PPP systems, including satellite orbit corrections, clock difference corrections, and code bias corrections;

[0015] After receiving the broadcast augmentation message, decode it according to the format to obtain different types of SSR corrections;

[0016] After decoding, match the correction products with the corresponding broadcast ephemeris through the data version number of the corrections to recover the real-time precise satellite orbits and satellite clock differences of all available satellites at the current epoch.

[0017] As a further technical solution, Step 2 further includes:

[0018] Adopt a method of mutual verification between the two products to detect orbit outliers. When the difference between the two space-based orbits in any direction exceeds the threshold, it is considered that there is an anomaly in the PPP-B2b orbit or the Galileo HAS orbit of the satellite.

[0019] As a further technical solution, Step 3 calculates the combined orbits of the common satellites and the coordinate datum transformation parameters between the combined orbits and the space-based PPP orbit products by the iterative weighted least squares method, and further includes:

[0020] The datum between different satellite orbit products is unified through the Helmert similarity transformation model. The parameters to be estimated for each epoch are the combined orbits of each satellite and the seven transformation parameters corresponding to each orbit product. Among them, the weights of the combined orbits are determined by combining the prior weight determination of product accuracy assessment and the posterior weight determination based on observations.

[0021] As a further technical solution, step 4 further includes:

[0022] Using the coordinate datum conversion parameters calculated in step 3, the orbit products of all non-common satellites are transferred to the same coordinate reference frame as the combined orbit product of the common satellite according to the Helmert similarity transformation model. Among them, the Helmert parameter transformation method realizes high-precision coordinate conversion by estimating a scale parameter, three translation parameters, and three rotation parameters.

[0023] As a further technical solution, step 5 further includes:

[0024] The calculation formula for correcting the orbit-clock consistency of the satellite-based satellite clock error is:

[0025]

[0026] In the formula, is the orbit-clock consistency correction of the real-time clock error product a, in seconds, and are the satellite coordinate vectors of a certain satellite-based orbit and the combined orbit respectively, represents the unit vector corresponding to the satellite-based orbit, and c is the speed of light in vacuum.

[0027] As a further technical solution, step 6 for detecting the consistency of the clock error types between epochs of the satellite-based satellite clock error further includes:

[0028] Mark the types of clock error corrections used by each GPS satellite in the current epoch i;

[0029] For each satellite within the subset, check whether the mark in the current epoch is the same as the mark in the previous epoch;

[0030] If they are the same, it means that the types of clock error corrections used by the satellite in the previous and current epochs are consistent; if they are different, it means that the types of clock error corrections used by the satellite in the previous and current epochs are inconsistent. At this time, reset the ambiguity parameters of the satellite.

[0031] According to one aspect of the specification of the present invention, a combined positioning system for a dual satellite-based real-time precise point positioning system is provided, including:

[0032] The first main module is used to acquire and decode the PPP-B2b and Galileo HAS navigation augmentation message information received synchronously, perform time matching on the satellite-based augmentation orbits and clock correction data with the corresponding broadcast ephemeris orbits and clock products, and restore the complete precise satellite orbits and satellite clock products of all available satellites at the current epoch;

[0033] The second main module is used to construct a common satellite subset of the real-time correction products provided by Beidou PPP-B2b and Galileo HAS at the current epoch, preprocess the orbit products of the common satellite subset, eliminate abnormal situations, and obtain the "clean" orbit products of the common satellite subsets of the two satellite-based PPP systems;

[0034] The third main module is used to generate the combined orbits of the common satellites based on the common satellite subset, and calculate the coordinate reference transformation parameters between the combined orbit products of the common satellite subset and the satellite-based PPP orbit products;

[0035] The fourth main module is used to use the calculated coordinate reference transformation parameters to transfer the orbit products of all non-common satellites to the same coordinate reference frame as the combined orbit products of the common satellites;

[0036] The fifth main module is used to correct the differences between the combined orbits and the B2b / HAS orbits to their respective satellite clock products;

[0037] The sixth main module is used to perform consistency detection of the clock types between epochs on the satellite-based satellite clocks and reset the ambiguities of the satellites that fail the detection when the clock correction data used for positioning in the dual satellite-based system changes;

[0038] The seventh main module is used to utilize the provided corrected precise orbits and clock correction data to achieve precise positioning of the combined dual satellite-based PPP system.

[0039] According to one aspect of the specification of the present invention, there is provided an electronic device, including a memory and a processor, the memory stores program instructions executed by the processor, and the processor calls the program instructions to execute the combined positioning method of the dual satellite-based real-time precise point positioning system described above.

[0040] According to one aspect of the specification of the present invention, there is provided a non-transitory computer-readable storage medium, the non-transitory computer-readable storage medium stores computer instructions, and the computer instructions cause the computer to execute the combined positioning method of the dual satellite-based real-time precise point positioning system described above.

[0041] In the actual application process of traditional satellite-based PPP systems, they are affected by factors such as server failures, signal blockage or interference at the user end, resulting in anomalies such as interruptions and errors in the actually received satellite-based corrections, which affect the service performance. Compared with the existing technologies, the beneficial effects of the present invention are as follows:

[0042] The present invention can use the orbit corrections of two satellite-based PPPs on the common satellite subset to cross-check each other, timely eliminate satellites with abnormal orbits, and can make full use of as many available satellites as possible in the solution, improving the GPS single-satellite availability, and enhancing the positioning accuracy and convergence speed. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings used in the description of the embodiments or the prior art. Obviously, the following-described drawings are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0044] Figure 1 It is a schematic diagram of the flow framework of the combined positioning method of the dual-satellite-based PPP system based on Beidou PPP-B2b and Galileo HAS provided by the embodiments of the present invention.

[0045] Figure 2 It is a time-series diagram of the real-time orbit errors of PPP-B2b and Galileo HAS of GPS satellites provided by the embodiments of the present invention.

[0046] Figure 3 It is a schematic diagram of the number of available satellites and PDOP values of the MIZU station in the single Beidou PPP-B2b, single Galileo HAS, and dual-satellite-based PPP modes provided by the embodiments of the present invention.

[0047] Figure 4 It is a schematic diagram of the dynamic positioning errors of the MIZU station in the single Beidou PPP-B2b, single Galileo HAS, and dual-satellite-based PPP modes provided by the embodiments of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0048] The present invention provides a combined positioning method for a dual-satellite-based PPP system based on Beidou PPP-B2b and Galileo HAS. This method realizes the combined real-time precise point positioning of the dual-satellite-based PPP system by synchronously receiving and processing the real-time orbits and clock corrections of PPP-B2b and Galileo HAS, and based on strategies such as orbit combination and clock correction switching.

[0049] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, 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 described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. In addition, the technical features in the various embodiments or single embodiments provided by the present invention are arbitrarily combined with each other to form a new technical solution. This combination is not restricted by the sequence of steps and / or the structural composition mode, but must be based on the ability of ordinary technicians in this field to achieve. When the combination of technical solutions is contradictory or cannot be achieved, it should be considered that this combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0050] like Figure 1 As shown, the present invention provides a dual-satellite-based PPP system joint positioning method based on Beidou PPP-B2b and Galileo HAS, comprising the following steps:

[0051] Step 1: Obtain and decode the synchronously received PPP-B2b and Galileo HAS navigation augmentation message information, time-match the satellite-based augmentation orbit and clock correction numbers with the corresponding broadcast ephemeris orbit and clock products, and restore the complete precise satellite orbits and satellite clock products of all available satellites in the current epoch.

[0052] Step 2: Construct a common satellite subset of the real-time correction products provided by BeiDou PPP-B2b and Galileo HAS in the current epoch, and pre-process the orbit products of the common satellite subset to remove abnormal conditions such as gross errors and jump values, and obtain the “clean” orbit products of the common satellite subsets of the two types of satellite-based PPP systems.

[0053] Step 3: Generate a combined orbit of the public satellite based on the public satellite subset, and calculate the coordinate reference conversion parameters between the combined orbit product of the public satellite subset and the satellite-based PPP orbit product.

[0054] Step 4: Using the coordinate reference conversion parameters calculated in step 3, the orbit products of all non-public satellites are converted to the same coordinate reference frame as the combined orbit products of the public satellites.

[0055] Step 5: Since there is a strong correlation between the satellite-based satellite clock error and the satellite orbit, in order to maintain consistency and self-consistency, the satellite-based satellite clock error needs to be corrected for orbit consistency, that is, the difference between the combined orbit and the B2b / HAS orbit is corrected to the respective satellite clock error products.

[0056] Step 6, when the clock error correction used in the dual satellite-based system positioning switches (i.e., using the Beidou PPP-B2b or the GPS clock error provided by Galileo HAS), there is a large difference in the time reference. It is necessary to perform consistency detection on the clock error types between the previous and current epochs of the satellite-based satellite clock error, and reset the ambiguity of the satellites that fail the detection.

[0057] Step 7, using the corrected precise orbits and clock error corrections provided in Step 5 and Step 6, the precise positioning of the combined dual satellite-based PPP system can be achieved.

[0058] Furthermore, in Step 1, it is required to simultaneously receive the real-time corrections of the two satellite-based PPP systems of PPP-B2b and HAS, including satellite orbit corrections, clock error corrections, and code bias corrections. After the user receives the broadcast enhanced message, different types of SSR corrections can be decoded according to the format. After decoding, the corrections product is matched with the corresponding broadcast ephemeris through the Issue Of Data (IOD) of the corrections to restore the real-time precise satellite orbits and satellite clock errors of all available satellites at the current epoch.

[0059] Furthermore, in Step 2, a common satellite subset of the real-time correction products provided by Beidou PPP-B2b and Galileo HAS at the current epoch is constructed, and abnormal data preprocessing is performed on the orbits of the common subset. The present invention adopts a method of mutual verification of the two products to detect orbit outliers. When the difference between the two satellite-based orbits in any direction exceeds the threshold Θ (set as the empirical value 1m in the present invention), it is considered that there is an abnormality in the PPP-B2b orbit or the Galileo HAS orbit of the satellite.

[0060] Furthermore, in Step 3, based on the common satellite subset of the PPP-B2b and Galileo HAS products, the coordinate reference conversion parameters between the combined orbit product of the common satellite subset and the satellite-based PPP orbit product are calculated. Specifically, the combined orbit of the common satellites is calculated by the iterative weighted least squares method, as well as the coordinate reference conversion parameters between the combined orbit and the satellite-based PPP orbit product. First, the Helmert similarity transformation model is used to unify the reference between different satellite orbit products, that is, the combined orbit and the Helmert transformation parameters of the combined orbit can be directly obtained by the one-step method. Its mathematical model is:

[0061]

[0062] In the formula, s represents the satellite, and represent the coordinates of the combined satellite orbit, They respectively represent the satellite orbits corresponding to product type a, where a represents Galileo HAS or PPP-B2b real-time products. The parameters to be estimated at each epoch are the combined orbits of each satellite and the seven transformation parameters corresponding to each orbit product.

[0063] Based on the above mathematical model, the linearized error equation for the i-th epoch is:

[0064]

[0065] Where, represents the design matrix, and l a,i represents the difference between the actual observation value and the estimated value. is the observation residual vector, and its specific expression can be written as:

[0066]

[0067] In the formula, M a , and are respectively the scale parameter, rotation parameter and translation parameter corresponding to the orbit product a (a is a PPP-B2b product or a Galileo HAS product). The initial value of the combined orbit is set as the average of the PPP-B2b and Galileo HAS orbits, and the initial value of the Helmert transformation parameter is calculated according to the transformation model. is the coefficient matrix of the combined orbit, and are respectively the coefficient matrices of the scale and rotation parameters, and E i is the 3×3 identity matrix and is the coefficient matrix of the translation parameter.

[0068] From the characteristics of in the error equation, it can be seen that the Helmert transformation parameters of the PPP-B2b or Galileo HAS satellite orbits relative to the combined orbit have the same coefficient matrix, and it is necessary to add a datum constraint in the model to separate the transformation parameters:

[0069]

[0070] Regarding the problem of weight determination in the orbit combination process, the present invention adopts a method that combines the prior weight determination of product accuracy evaluation and the posterior weight determination based on observation values. The specific method is as follows:

[0071] (1) Prior weight value: By evaluating the historical orbit data of Beidou PPP-B2b and Galileo HAS, the external conformity accuracy of the orbit products can be obtained, and the weights of the two orbit products in the combination algorithm are determined according to different accuracy levels, that is, the prior weight value is taken as the reciprocal of the ratio of the RMS of the average errors of the HAS orbit and the PPP-B2b orbit.

[0072] (2) Posterior weight: During each iteration, the weight is dynamically adjusted according to the residual value of each satellite. The present invention uses the following IGGIII equivalent weight function for adjustment:

[0073]

[0074] where p i and are respectively the initial weight and the adjusted weight of the i-th observation value, v' i is the standardized residual, and k0 and k1 are the critical values of the downweighting area and the rejection area, taking the empirical values 3 and 6 respectively.

[0075] Furthermore, in step 4, based on the transformation parameters obtained in step 3, the orbits of all non-common satellites are transformed to the same reference frame as the combined orbit of the common satellite subset according to the Helmert similarity transformation model. The Helmert seven-parameter transformation method realizes high-precision coordinate transformation by estimating a scale parameter, three translation parameters, and three rotation parameters. The Helmert transformation model between different satellite-based PPP real-time satellite orbit products is:

[0076]

[0077] where and respectively represent the satellite coordinates obtained from the reference product, and respectively represent the satellite coordinates obtained from the satellite-based PPP product to be transformed, s represents the satellite, and i represents the epoch. M, R k , T k (k = x, y, z) respectively represent the scale parameter, rotation parameter, and translation parameter corresponding to the product to be transformed.

[0078] Furthermore, in step 5, after completing the orbit combination, the differences between the combined orbit and the satellite-based orbits of PPP-B2b and Galileo HAS are corrected to their respective satellite-based clock difference products to ensure the consistency between the satellite-based orbit and the clock difference product. The calculation formula for this consistency correction amount is:

[0079]

[0080] where is the orbit-clock consistency correction amount of the real-time clock difference product a, in seconds. and are respectively the satellite coordinate vectors of a certain satellite-based orbit (the satellite orbit provided by PPP-B2b or Galileo HAS) and the combined orbit, Denote the unit vector corresponding to the satellite-based orbit, and \(c\) is the speed of light in vacuum. Then the corrected clock error can be expressed as:

[0081]

[0082] Furthermore, in step 6, consistency detection is performed on the clock error types of the satellite-based satellite clock between the previous and current epochs. First, mark the types of clock error corrections used by each GPS satellite in the current epoch \(i\). Then, for each satellite in the subset, check whether the mark in the current epoch is the same as that in the previous epoch. If they are the same, it means that the types of clock error corrections used by this satellite in the previous and current epochs are consistent and no special treatment is required; if they are different, it means that the types of clock error corrections used by this satellite in the previous and current epochs are inconsistent. At this time, reset the ambiguity parameter of this satellite.

[0083] Figure 2 The error sequences of the PPP-B2b real-time orbit of GPS satellites and the Galileo HAS real-time orbit are given. The left column in the figure represents the PPP-B2b real-time orbit, and the right column represents the Galileo HAS real-time orbit. The three rows from top to bottom are the radial error, tangential error, and normal error respectively. From the figure, the radial accuracy of the HAS satellite orbit is similar to that of the PPP-B2b orbit, both within 0.2 m, while the tangential and normal accuracies are significantly better than those of the PPP-B2b orbit, with smaller errors and more stable fluctuations. Therefore, based on the evaluation results of the accuracies of the two orbit products, a higher prior weight needs to be given to the HAS product during combination to ensure accuracy, and the prior weight value is taken as the reciprocal of the RMS ratio of the average errors of the HAS orbit and the PPP B2b orbit.

[0084] Figure 3 The number of available satellites and the PDOP variations of the MIZU station on DOY 020 in 2024 using the single Beidou PPP-B2b, single Galileo HAS, and dual satellite-based PPP modes are given. The method of the present invention is marked as the "Comb" mode. From the figure, the method of the present invention can utilize as many GPS satellites as possible. The average number of available satellites participating in the solution is 22.4, which is much higher than 14.6 and 13.6 in the single Beidou PPP-B2b and single Galileo HAS modes. At the same time, the PDOP value sequence of the method of the present invention is also significantly lower than that of any single satellite-based PPP system used alone.

[0085] Figure 4The dynamic PPP positioning errors of MIZU Station on DOY 020 in 2024 using single BeiDou PPP-B2b, single Galileo HAS, and dual-constellation PPP modes are given. The method of the present invention is marked as the "Comb" mode. From the figure, the fluctuations of the positioning error sequence of the method of the present invention are significantly reduced, with higher positioning accuracy and stability. There are certain jumps or fluctuations in the positioning results of single BeiDou PPP-B2b and single Galileo HAS in the E and U directions, while the method of the present invention can still maintain a relatively stable positioning result, and the maximum error fluctuation in the U direction does not exceed 0.3 m.

[0086] The implementation basis of each embodiment of the present invention is achieved through programmed processing by a device with processor functions. Therefore, in engineering practice, the technical solutions and functions of each embodiment of the present invention are encapsulated into various modules. Based on this actual situation, on the basis of the above embodiments, an embodiment of the present invention provides a combined positioning system for a dual-constellation real-time precise point positioning system, which is used to execute a combined positioning method for a dual-constellation real-time precise point positioning system in the above method embodiments.

[0087] The system includes: a first main module, configured to acquire and decode the PPP-B2b and Galileo HAS navigation augmentation message information received synchronously, perform time matching on the satellite-based augmentation orbits and clock correction parameters with the corresponding broadcast ephemeris orbits and clock products, and recover the complete precise satellite orbits and satellite clock products of all available satellites at the current epoch; a second main module, configured to construct a common satellite subset of the real-time correction products provided by BeiDou PPP-B2b and Galileo HAS at the current epoch, and preprocess the orbit products of the common satellite subset to eliminate abnormal situations, and obtain the "clean" orbit products of the common satellite subset of the two satellite-based PPP systems; a third main module, configured to generate a combined orbit of the common satellites based on the common satellite subset, and calculate the coordinate reference conversion parameters between the combined orbit products of the common satellite subset and the satellite-based PPP orbit products; a fourth main module, configured to use the calculated coordinate reference conversion parameters to transfer the orbit products of all non-common satellites to the same coordinate reference frame as the combined orbit products of the common satellites; a fifth main module, configured to correct the differences between the combined orbit and the B2b / HAS orbit to their respective satellite clock products; a sixth main module, configured to perform consistency detection of the clock types between adjacent epochs on the satellite-based satellite clocks when the clock correction parameters used for positioning in the dual-constellation system are switched, and reset the ambiguities of the satellites that fail the detection; a seventh main module, configured to use the provided corrected precise orbits and clock correction parameters to achieve precise positioning of the combined dual-constellation PPP system.

[0088] A combined positioning system of a dual satellite-based real-time precise point positioning system provided by an embodiment of the present invention addresses the problems of insufficient accuracy, reliability, and continuity in current positioning using a single satellite-based PPP correction. By using the aforementioned several modules, a processing strategy for orbit and clock correction in combined positioning is designed. Combining PPP-B2b and Galileo HAS for satellite-based PPP positioning of the three systems of GPS+BDS-3+Galileo effectively improves the positioning service performance of the satellite-based PPP user terminal.

[0089] It should be noted that the system embodiment provided by the present invention, in addition to being used to implement the method in the above method embodiment, is also used to implement the methods in other method embodiments provided by the present invention. The difference lies only in setting corresponding functional modules, and its principle is basically the same as that of the above system embodiment provided by the present invention. As long as those skilled in the art, based on the above system embodiment, refer to the specific technical solutions in other method embodiments, obtain corresponding technical means by combining technical features, and the technical solutions composed of these technical means, on the premise of ensuring the practicability of the technical solutions, improve the modules in the above system embodiment to obtain corresponding system-like embodiments for implementing the methods in other method-like embodiments.

[0090] Based on the same inventive concept as the foregoing embodiment, an embodiment of the present invention further provides an electronic device, including a memory and a processor. The memory stores program instructions executed by the processor, and the processor calls the program instructions to execute the combined positioning method of a dual satellite-based real-time precise point positioning system.

[0091] Based on the same inventive concept as the foregoing embodiment, an embodiment of the present invention further provides a non-transitory computer-readable storage medium. The non-transitory computer-readable storage medium stores computer instructions, and the computer instructions cause the computer to execute the combined positioning method of a dual satellite-based real-time precise point positioning system, including:

[0092] Step 1, acquire and decode the PPP-B2b and Galileo HAS navigation augmentation message information received synchronously, perform time matching on the satellite-based augmentation orbit and clock correction with the corresponding broadcast ephemeris orbit and clock products, and restore the complete precise satellite orbits and satellite clock products of all available satellites at the current epoch.

[0093] Step 2, construct a common satellite subset of the real-time correction products provided by Beidou PPP-B2b and Galileo HAS at the current epoch, and preprocess the orbit products of the common satellite subset to eliminate abnormal situations, and obtain the "clean" orbit products of the common satellite subset of the two satellite-based PPP systems.

[0094] Step 3: Generate the combined orbits of the common satellites based on the common satellite subset, and calculate the coordinate reference transformation parameters between the combined orbit products of the common satellite subset and the satellite-based PPP orbit products;

[0095] Step 4: Use the coordinate reference transformation parameters calculated in Step 3 to transfer the orbit products of all non-common satellites to the same coordinate reference frame as the combined orbit products of the common satellites;

[0096] Step 5: Correct the differences between the combined orbits and the B2b / HAS orbits to their respective satellite clock difference products;

[0097] Step 6: When the clock difference corrections used for dual satellite-based system positioning are switched, perform consistency detection of the clock difference types between epochs for the satellite-based satellite clock differences, and reset the ambiguities of the satellites that fail the detection;

[0098] Step 7: Use the corrected precise orbits and clock difference corrections provided in Steps 5 and 6 to achieve precise positioning of the combined dual satellite-based PPP system.

[0099] In summary, the present invention discloses a method for combined precise positioning of a dual satellite-based PPP system based on the Beidou-3 PPP-B2b service and the Galileo HAS service. This method synchronously receives and decodes the real-time satellite orbits, clock differences, and code bias corrections of PPP-B2b and HAS, and through strategies such as orbit combination and optimization and switching of clock difference corrections, realizes real-time precise point positioning of the user terminal combining the three systems of GPS+BDS-3+Galileo. In terms of orbit corrections, the benchmarks of the two satellite-based PPP orbit products are unified through the Helmert similarity transformation model, and a weight adjustment strategy combining prior weighting and posterior weighting is adopted to generate the combined orbit products. In terms of clock difference corrections, aiming at the problem of inconsistent time references for different satellite-based corrections, consistency detection of clock difference types between epochs is performed, and the ambiguity parameters of the corresponding satellites are reset in a timely manner. This multi-satellite-based PPP combined positioning method solves the influence of factors such as server failures and signal blockages at the user terminal on the positioning accuracy and continuity in the actual application process of the Beidou and Galileo satellite-based PPP systems, effectively weakens the error jumps caused by correction switching, and realizes a real-time satellite-based PPP user terminal service with a faster convergence speed, better positioning accuracy, and better continuity.

[0100] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the technical solutions of the embodiments of the present invention.

Claims

1. A combined positioning method for a dual-baseline real-time precise point positioning system, characterized in that include: Step 1: Obtain and decode the synchronously received PPP-B2b and Galileo HAS navigation augmentation message information, time-match the satellite-based augmentation orbit and clock correction number with the corresponding broadcast ephemeris orbit and clock error products, and restore the complete precise satellite orbit and satellite clock error products of all available satellites in the current epoch; Step 2: construct the common satellite subset of the real-time correction products provided by BeiDou PPP-B2b and Galileo HAS at the current epoch, and pre-process the orbit products of the common satellite subset to remove abnormalities and obtain the "clean" orbit products of the common satellite subsets of the two types of satellite-based PPP systems; Step 3, generating a combined orbit of the public satellite based on the public satellite subset, and calculating the coordinate reference conversion parameters between the combined orbit product of the public satellite subset and the satellite-based PPP orbit product; Step 4, using the coordinate reference conversion parameters calculated in step 3, the orbit products of all non-public satellites are converted to the same coordinate reference frame as the combined orbit products of the public satellites; Step 5: Correct the difference between the combined orbit and the B2b / HAS orbit to the respective satellite clock error products; Step 6: When the clock correction number used in the dual-satellite-based system positioning is switched, the clock correction type consistency between the previous and next epochs is checked for the satellite-based satellite clock correction, and the ambiguity of the satellite that fails the test is reset; Step 7, using the corrected precise orbit and clock corrections provided by steps 5 and 6, to achieve precise positioning of the joint dual-satellite-based PPP system.

2. The combined positioning method of a dual-satellite-based real-time precise point positioning system according to claim 1, characterized in that, The step 1 also includes: Simultaneously receive real-time corrections from both PPP-B2b and HAS satellite-based PPP systems, including satellite orbit corrections, clock corrections, and code deviation corrections; After receiving the broadcast enhanced message, different types of SSR correction numbers are obtained according to the format decoding; After decoding, the correction product is matched with the corresponding broadcast ephemeris by the data version number of the correction number to restore the real-time precise satellite orbits and satellite clock errors of all available satellites in the current epoch.

3. The combined positioning method of a dual satellite-based real-time precise point positioning system according to claim 1, characterized in that, The step 2 also includes: The method of mutual verification of the two products is adopted to detect orbital anomalies. When the difference between the two satellite-based orbits in any direction exceeds the threshold, it is considered that there is an anomaly in the PPP-B2b orbit or Galileo HAS orbit of the satellite.

4. The combined positioning method of a dual-satellite-based real-time precise point positioning system according to claim 1, wherein, The step 3 calculates the combined orbit of the public satellite and the coordinate reference conversion parameters between the combined orbit and the satellite-based PPP orbit product by iterative weighted least squares method, and also includes: The Helmert similarity transformation model is used to unify the benchmarks between different satellite orbit products. The parameters to be estimated at each epoch are the combined orbit of each satellite and the seven transformation parameters corresponding to each orbit product. The weight of the combined orbit is determined by combining the a priori weighting of product accuracy assessment and the a posteriori weighting based on observations.

5. A combined positioning method for a dual satellite-based real-time precise point positioning system according to claim 1, characterized in that, The step 4 also includes: Using the coordinate reference transformation parameters calculated in step 3, transform the orbit products of all non-common satellites to the same coordinate reference frame as the combined orbit product of the common satellites according to the Helmert similarity transformation model. Among them, the Helmert parameter transformation method realizes high-precision coordinate system transformation by estimating a scale parameter, three translation parameters, and three rotation parameters.

6. The combined positioning method of a dual-satellite-based real-time precise point positioning system according to claim 1, characterized in that, The said step 5 further includes: The calculation formula for correcting the consistency between the satellite-based satellite clock offset and the orbit clock is: In the formula, is the track clock consistency correction of the real-time clock error product a, in seconds, and are respectively the satellite coordinate vectors of a certain satellite-based orbit and the combined orbit, represents the unit vector corresponding to the satellite-based orbit, and c is the speed of light in vacuum.

7. The combined positioning method of a dual-satellite-based real-time precise point positioning system according to claim 1, wherein The said step 6 performs consistency detection of the clock offset types between the previous and current epochs for the satellite-based satellite clock offset, and further includes: Mark the types of clock offset corrections used by each GPS satellite in the current epoch i; For each satellite in the subset, check whether the mark in the current epoch is the same as the mark in the previous epoch; If they are the same, it means that the types of clock offset corrections used by this satellite in the previous and current epochs are consistent; if they are different, it means that the types of clock offset corrections used by this satellite in the previous and current epochs are inconsistent, and at this time, reset the ambiguity parameter of this satellite.

8. A combined positioning system for a dual satellite-based real-time precise point positioning system, characterized in that, It includes: The first main module is used to acquire and decode the PPP-B2b and Galileo HAS navigation augmentation message information received synchronously, perform time matching on the satellite-based augmentation orbit and clock offset corrections with the corresponding broadcast ephemeris orbit and clock products, and restore the complete precise satellite orbits and satellite clock products of all available satellites in the current epoch; The second main module is used to construct a subset of common satellites of the real-time correction products provided by Beidou PPP-B2b and Galileo HAS in the current epoch, and preprocess the orbit products of the subset of common satellites, eliminate abnormal situations, and obtain the "clean" orbit products of the subset of common satellites of the two satellite-based PPP systems; The third main module is used to generate the combined orbit of the common satellites based on the subset of common satellites, and calculate the coordinate reference transformation parameters between the combined orbit product of the subset of common satellites and the satellite-based PPP orbit product; The fourth main module is used to use the calculated coordinate reference transformation parameters to transform the orbit products of all non-common satellites to the same coordinate reference frame as the combined orbit product of the common satellites; The fifth main module is used to correct the differences between the combined orbit and the B2b / HAS orbit to their respective satellite clock products; The sixth main module is used to perform consistency detection of the clock offset types between the previous and current epochs for the satellite-based satellite clock offset when the clock offset corrections used for positioning in the dual satellite-based system change, and reset the ambiguity of the satellites that fail the detection; The seventh main module is used to realize precise positioning of the combined dual satellite-based PPP system by using the provided corrected precise orbits and clock offset corrections.

9. An electronic device, characterized in that, It includes a memory and a processor. The memory stores program instructions executed by the processor, and the processor calls the program instructions to execute a combined positioning method for a dual satellite-based real-time precise point positioning system according to any one of claims 1 to 7.

10. A non-transitory computer-readable storage medium, characterized in that The said non-transitory computer-readable storage medium stores computer instructions, and the computer instructions cause the computer to execute a combined positioning method for a dual satellite-based real-time precise point positioning system according to any one of claims 1 to 7.

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