Method and system for resolving ambiguity between reference stations of full-constellation Beidou mixed signal

Abstract

The invention discloses an inter-reference-station ambiguity resolving method and system for full-constellation Beidou mixed signals. According to the invention, independent ambiguity calculation is carried out on double-frequency and three-frequency signals of Beidou No.2 and No.3, so that reliable ambiguity information can be obtained under different frequency bands; and then, through effective combination and analysis of the ambiguity results, unified solution between the ambiguity results and the ambiguity results is realized. The mode of separating resolving and subsequent fusion not only optimizes the use efficiency of the signal, but also remarkably improves the accuracy of ambiguity resolving. The resolving strategy provided by the invention not only enhances the overall performance and reliability of the positioning system, but also effectively improves the accuracy of network RTK positioning. The method provides powerful support for the practical application of the Beidou ground-based augmentation system, and has important technical value, wide applicability and good market prospect. By optimizing the combined use of satellite signals, the method lays a solid foundation for the development of the satellite navigation technology in the future.

Description

Technical Field

[0001] The present invention relates to the field of satellite navigation technology, and in particular to a method for resolving ambiguity between reference stations in a Beidou satellite navigation system, and in particular to a method and system for resolving ambiguity between reference stations of a full-constellation Beidou mixed signal. Background Art

[0002] With the development of global satellite navigation systems, the BeiDou satellite navigation system has gradually become an important positioning service platform. The BeiDou-2 and BeiDou-3 satellite systems provide users with rich positioning information through different frequencies and signal characteristics. The BeiDou-2 system is widely used in the Asia-Pacific region, while the global networking capability of the BeiDou-3 system further enhances positioning accuracy.

[0003] There are many research results on the joint data processing methods for BeiDou-2 and BeiDou-3. Tang Weiming et al. proposed the IF TCAR reference station ambiguity determination method. For the BeiDou-2 triple-frequency long-distance reference station network ambiguity resolution, this method uses the known position of the reference station, the easily resolvable extra-wide lane (EWL) ambiguity and the IF phase combination to reliably fix the WL ambiguity, basically achieving 100% reliable fixation of the ambiguity. For details, please refer to the literature: Tang W, Shen M, Deng C, et al. 2018. Network-based triple-frequency carrier phase ambiguity resolutionbetween reference stations using BDS data for long baselines [J]. GPSSolutions, 22 (3): 73. Deng Chenlong et al. proposed a method for joint solution of BeiDou-2 and BeiDou-3 for short-range RTK positioning. This method uses the intra-system differential method to determine the ultra-wide lane and wide lane ambiguities of BDS-2 and BDS-3 respectively, and then uses the wide lane observations composed of B1I and B3I and the original observations to construct an error equation group to solve the original ambiguity, and finally realize the fusion positioning of BDS-2 and BDS-3. For details, please refer to the literature: Deng C, Qi S, Tang W, et al. 2022. Model comparison and performance analysis of multi-frequency precise positioning with the joint BDS-2 and BDS-3 system [J]. Advances in SpaceResearch, 69 (8): 3044-3058. In RTK terminal positioning, BDS2 and BDS3 can be used. The loose combination method can also be used. The tight combination method can also be used. However, on the server side, in order to ensure the consistency of the correction number, the correction data of BDS2 and BDS3 must be unified. Otherwise, the terminal can only use the loose combination method for solution.

[0004] However, due to the frequency difference between BeiDou-2 and BeiDou-3 satellites, there are certain challenges in jointly resolving the ambiguities of the two. Traditional ambiguity resolution methods are mostly targeted at a single satellite system, making it difficult to fully utilize the advantages of the joint system. In practical applications, how to effectively integrate the multi-frequency signals of BeiDou-2 and BeiDou-3 to achieve efficient and accurate ambiguity resolution has become the key to improving the quality of network RTK (real-time kinematic positioning) services.

[0005] Current research mainly focuses on signal processing and ambiguity fixation technology, but in practical applications, there are still problems such as low signal utilization efficiency and insufficient solution accuracy. Therefore, a new solution method is urgently needed to achieve effective integration of BeiDou-2 and -3 satellite signals and improve the overall performance and reliability of the positioning system. Summary of the invention

[0006] The present invention provides a method for inter-reference station ambiguity resolution based on BeiDou-2 and -3 satellites combined with BeiDou ground-based augmentation system, aiming to improve the positioning accuracy and reliability of the satellite navigation system. The core of this method is to make full use of the three-frequency signal advantages of BeiDou-2 and -3, and adopt an innovative solution strategy of "separation first, fusion later", which specifically includes the following steps: Step 1: Based on the MW combination rounding method, the ultra-wide lane ambiguity of the BeiDou-2 and BeiDou-3 systems are determined respectively; Step 2: Based on the ionosphere-free combined TCAR method, the wide lane ambiguity fixed values ​​of the BeiDou-2 and BeiDou-3 systems are determined respectively; Step 3, using the double-difference wide lane ambiguity determination method to obtain the wide lane ambiguity of the BeiDou-2 and BeiDou-3 joint system; Step 4, obtain the wide lane ambiguity fixed solution of the BeiDou-2 and BeiDou-3 joint system of the unified reference satellite through transformation; Step 5, for the BeiDou-2 and BeiDou-3 joint system with a unified reference satellite, the ionospheric-free combined ambiguity of the double difference B1I and B3I frequencies is determined based on Kalman filtering, and then combined with the wide lane ambiguity fixed solution to determine the original ambiguity of B1I of all satellites; where B1I and B3I are different frequency signals in BeiDou-2 and BeiDou-3 satellites.

[0007] Furthermore, the specific implementation of step 1 includes the following sub-steps: Step 1.1, establish the double-difference pseudo-range and phase observation values ​​of the BeiDou-2 and BeiDou-3 systems between the reference stations; Select the satellite with the highest elevation angle among the BeiDou-2 satellites The satellite with the highest altitude angle among the BeiDou-3 satellites As the reference satellite of each system, the non-combined pseudo-range observation values ​​of each system are obtained through double difference operation and phase observations ; In the formula, It is the double difference operator between different reference stations and between non-reference satellites and reference satellites. The subscripts 1, 2, and 3 represent three different signal frequencies respectively; Step 1.2, based on the double-difference pseudo-range and phase observation values ​​of step 1.1, calculate the double-difference pseudo-range combined virtual observation value And phase combination observations ;

[0008]

[0009] in , c is the speed of light, and is a constant; Step 1.3, calculate the ultra-wide lane ambiguity of the BeiDou-2 and BeiDou-3 systems respectively, the formula is as follows:

[0010] In the formula, The rounding operator.

[0011] Furthermore, in step 2, the ionosphere-free combined virtual observation value, the double differential ground-to-satellite distance and the tropospheric delay are used to calculate the ionosphere-free combined floating point ambiguity, and the fixed value of the wide lane ambiguity is obtained by multi-epoch smoothing; the specific implementation method is as follows: Step 2.1, using the double difference phase observations from step 1.1, construct two ionosphere-free combined observations:

[0012] In the formula, , and is a constant; Step 2.2: Determine the geometric distance between each satellite and the reference station based on the precisely known coordinates of the reference station and the calculated satellite positions. , where is the base station receiver coordinate, is the satellite coordinate, and then according to the double difference operator Get double differential ground distance ; Step 2.3: Use the Hopfield model to calculate the zenith tropospheric static delay ZHD and wet delay ZWD of each reference station, and then use the Niell projection function to calculate the projection function value of the static delay of each satellite. MF H and the projection function value of wet delay MF W , get the tropospheric delay of each satellite on the slant path , according to the double difference operator Get the double difference tropospheric delay ; Step 2.4, based on the ionosphere-free combined observations from step 2.1 and , double differential ground-to-ground distance in step 2.2 , double difference tropospheric delay in step 2.3 , calculate the floating point ambiguity corresponding to the ionosphere-free combination, the formula is as follows:

[0013] In the formula , is the wavelength corresponding to the ionosphere-free combination; Step 2.5, using the ionospheric-free combined floating ambiguity of step 2.4 and the ultra-wide lane ambiguity of step 1, calculate the floating wide lane ambiguity of BeiDou-2 and BeiDou-3 respectively :

[0014] In the formula,

[0015] Step 2.6, multi-epoch smoothing of the floating point wide lane ambiguity obtained in step 2.5, rounding to obtain a fixed value of the wide lane ambiguity, the formula is as follows:

[0016] In the formula, k is the epoch number, is the rounding operator, and the fixed values ​​of wide lane ambiguity of BeiDou-2 system and BeiDou-3 system are , .

[0017] Further, in step 3, the BeiDou-3 satellite is used as the reference satellite to form the pseudorange and phase observation values ​​of the double-difference B1I and B3I frequencies of the BeiDou-2 and BeiDou-3 joint system between the reference stations, and the initial value and fixed solution of the wide lane ambiguity are determined by using the ionosphere-free combined pseudorange and phase observation values, which specifically includes the following sub-steps: Step 3.1, BeiDou-3 satellite For reference satellites, pseudo-range observation values ​​of double difference B1I and B3I frequencies of BeiDou-2 and BeiDou-3 joint system are established between two reference stations and , phase observation value and ; Step 3.2, based on the double-difference pseudorange and phase observation values ​​in step 3.1, calculate the initial value of the wide-lane ambiguity of the BeiDou-2 and BeiDou-3 joint system; Step 3.3, based on the double difference phase observations in step 3.1, obtain the ionospheric-free combined pseudorange of the double difference B1I and B3I frequencies and phase observations , and then calculate the initial value of the wide-lane ambiguity of the BeiDou-2 and BeiDou-3 joint system; Step 3.4, calculate The double differential Earth-satellite distance of all satellites in the joint system is the reference satellite and double-difference tropospheric delay ; Step 3.5, based on the ionospheric-free combined pseudorange and phase observations of step 3.3, determine the first form of the ionospheric-free combined ambiguity:

[0018] According to the double differential ground-to-ground distance obtained in step 3.4 and double-difference tropospheric delay , determine the second form of the ionospheric-free combined ambiguity:

[0019] The wavelength of the ionosphere-free combination is compared with the two forms of ionosphere-free combination ambiguity to obtain the difference between the two forms of ionosphere-free combination ambiguity at this moment, and the standard deviation of the wide lane ambiguity before rounding the initial value in step 3.2 is calculated in turn. ; Step 3.6, taking the initial value of wide lane ambiguity obtained in step 3.2 as the center, is the search radius, and the wide lane ambiguity is searched. Different wide lane ambiguities are calculated. The corresponding residual; if the residual value is less than the wide lane combination wavelength half of , the corresponding wide-lane ambiguity is considered to be fixed; In step 3.7, the wide lane ambiguity is obtained by back-calculating the geometric distance and compared with the wide lane ambiguity determined in step 3.6. If the two are consistent, it is considered that the corresponding wide lane ambiguity has been correctly fixed.

[0020] Furthermore, in step 3.2, the initial value of the wide-lane ambiguity of the BeiDou-2 and BeiDou-3 joint system is calculated using the following formula:

[0021] The wavelength of the wide lane combination , pseudorange combination , phase combination ; , and is a constant, c is the speed of light, The rounding operator.

[0022] Further, in step 3.3, the ionospheric-free combined pseudorange of the double difference B1I and B3I frequencies is obtained and phase observations , the calculation formula is as follows:

[0023]

[0024] in, , and is a constant.

[0025] Furthermore, in step 3.5, the difference between the two forms of ionospheric-free combined ambiguity is first calculated: , and then use the previous k The difference of epochs , by calculating the root mean square of multiple epochs , the calculation formula is:

[0026] When the RMS Convergence, that is and hour, N is a constant, If it is a positive decimal less than 1, it will not be updated. , after convergence for , is the standard deviation of the ionospheric-free combined ambiguity; Ignore the phase observation noise, and assume that the double-difference pseudorange noise of B1I is 5 times that of B3I, that is, , according to the standard deviation of the ionospheric-free combined ambiguity Calculate double difference pseudorange noise :

[0027] In the formula, ; Then calculate the standard deviation of the wide lane ambiguity before rounding the initial value in step 3.2 :

[0028] In the formula, , , and is a constant.

[0029] Further, in step 4, the wide lane ambiguity of the BeiDou-2 and BeiDou-3 joint system of the unified reference satellite is obtained by transformation, where the BeiDou-3 satellite directly uses the wide lane ambiguity fixed value ; Specifically includes the following sub-steps: Step 4.1: Select a BeiDou-2 satellite from the satellite pair whose wide-lane ambiguity is correctly fixed in step 3. , the satellite must meet the following two conditions: (1) The satellite involved in the solution in step 2 must be a reference satellite or not. ; (2) The altitude and azimuth of the reference satellite The widelane ambiguity of the closest selected satellite pair is denoted by ; Step 4.2, transform the BeiDou-2 wide lane ambiguity fixed value obtained in step 2 to obtain is the fixed value of the wide lane ambiguity of the reference satellite; specifically: like , then the BeiDou-2 non-reference satellite in step 2 is relative to The wide lane ambiguity is fixed at , BeiDou-2 reference satellite relatively The wide lane ambiguity is fixed at ; like , first find the BeiDou-2 non-reference satellite calculated in step 2 Relative reference satellite The wide lane ambiguity fixed value , then the remaining non-reference satellites of BeiDou-2 are relative The wide lane ambiguity is fixed at , BeiDou-2 non-reference satellite relatively The wide lane ambiguity is fixed at ; BeiDou-2 reference satellite relatively The wide lane ambiguity is fixed at .

[0030] Further, in step 5, the ionospheric-free combined floating point ambiguity is determined by using Kalman filtering, and combined with the wide lane ambiguity, the B1I original ambiguity of all satellites is finally determined; specifically, the following sub-steps are included: Step 5.1, using the ionospheric-free combined phase observations constructed in step 3.3 , the double differential ground-to-ground distance obtained in step 3.4 and double-difference tropospheric delay , formed with The ionospheric-free combined phase observation equation of the BeiDou-2 and BeiDou-3 joint system is:

[0031] Determine the ionospheric-free combined floating point ambiguity through Kalman filtering ; Step 5.2: Use the relative position of BeiDou-2 satellite and BeiDou-3 satellite obtained in step 4 Wide Lane Ambiguity , combined with the ionospheric-free combined ambiguity determined in step 5.3 , determine the B1I raw ambiguities of all satellites:

[0032] , and is a constant; Step 5.3, smoothing the B1I floating point ambiguity obtained in step 5.2 over multiple epochs , rounded to get a fixed value of fuzziness, the formula is as follows:

[0033] is the rounding operator and k is the number of epochs.

[0034] Through the above steps, the method of the present invention realizes the effective integration of BeiDou-2 and BeiDou-3 satellite signals, improves the accuracy of network RTK positioning and the overall performance of the system, and has important technical value and broad application prospects.

[0035] The present invention also provides an inter-reference station ambiguity resolution system for a full-constellation Beidou hybrid signal, comprising: A processor and a memory, the memory is used to store program instructions, and the processor is used to call the stored instructions in the memory to execute the method described in the above technical solution.

[0036] The beneficial effects produced by the present invention are: 1. The present invention adopts the solution strategy of "separation first, fusion later", fully utilizes the advantages of the three-frequency signals of BeiDou-2 and BeiDou-3, improves the signal utilization efficiency, enables the system to perform effective positioning under a wider range of conditions, effectively eliminates the ambiguity inconsistency problem caused by signal frequency differences, enhances the reliability of the system, and ensures the stability of positioning services.

[0037] 2. The present invention provides an innovative technical solution for the practical application of the BeiDou Ground-Based Augmentation System, especially for the ambiguity resolution of the joint use of BeiDou-2 and BeiDou-3 satellites to improve positioning accuracy and system reliability. The present invention promotes the further development of satellite navigation technology and has important technical value and market potential. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 It is a method flow chart of an embodiment of the present invention.

[0039] Figure 2This is a diagram of a method for selecting the optimal BeiDou-2 satellite according to an embodiment of the present invention. DETAILED DESCRIPTION

[0040] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0041] The present invention provides an ambiguity resolution method between reference stations of BeiDou-2 and BeiDou-3 satellites in conjunction with BeiDou ground-based augmentation system. The method comprises: determining the ultra-wide lane ambiguities of BeiDou-2 and BeiDou-3 respectively based on the rounding method of MW combination (Melbourne-Wubeena combination, MW combination is a combined observation value algorithm proposed by Melbourne and Wubbena) (step 1); determining the wide lane ambiguity fixed values ​​of BeiDou-2 and BeiDou-3 respectively based on the TCAR method (Three carrier ambiguity resolution, three-frequency carrier ambiguity resolution) of ionosphere-free combination (step 2); determining the dual-frequency (B1I, B3I) wide lane ambiguity of BeiDou-2 and BeiDou-3 (step 3); selecting the optimal BeiDou-3 satellite as the reference satellite, unifying the wide lane ambiguities of BeiDou-2 and BeiDou-3 (step 4); determining the ionosphere-free combined ambiguities of B1I and B3I signals based on Kalman filtering, and then combining the wide lane ambiguity fixed values ​​to finally determine the original ambiguities of B1I of all satellites (step 5). Figure 1 and Figure 2 The embodiment of the present invention provides a method for resolving ambiguity between reference stations based on BeiDou-2 and -3 satellites combined with BeiDou ground-based augmentation system, which specifically includes the following steps: Step 1: Based on the MW combination rounding method, determine the ultra-wide lane ambiguity of BeiDou-2 and BeiDou-3 respectively.

[0042] Step 1.1, establish the double-difference pseudorange and phase observation values ​​of the BeiDou-2 and BeiDou-3 systems between the reference stations.

[0043] Select the satellite with the highest elevation angle among the BeiDou-2 satellites The satellite with the highest altitude angle among the BeiDou-3 satellites As the reference satellite of each system, the non-combined pseudo-range observation values ​​of each system are obtained through double difference operation and phase observations In the formula, is a double difference operator between different reference stations and between non-reference satellites and reference satellites. The subscripts 1, 2, and 3 represent three different signal frequencies. For the BeiDou-2 satellite, they are B1I, B2I, and B3I frequency signals, respectively; for the BeiDou-3 satellite, they are B1I, B2a, and B3I frequency signals, respectively.

[0044] Step 1.2, based on the double-difference pseudorange and phase observations of step 1.1, calculate the double-difference pseudorange combined observation value And phase combination observations :

[0045]

[0046] in , c The speed of light. , and for the BeiDou-2 system, ; For the BeiDou-3 system, .

[0047] Step 1.3, calculate the ultra-wide lane ambiguity of the BeiDou-2 and BeiDou-3 systems , the formula is as follows:

[0048] In the formula, The rounding operator.

[0049] Step 2: Based on the TCAR method of ionosphere-free combination, determine the fixed values ​​of wide lane ambiguity of BeiDou-2 and BeiDou-3 respectively.

[0050] Step 2.1, using the double difference phase observations from step 1.1, construct two ionosphere-free combined observations:

[0051] In the formula, for both BeiDou-2 and BeiDou-3, .

[0052] Step 2.2: Determine the geometric distance between each satellite and the reference station based on the precisely known coordinates of the reference station and the calculated satellite positions. , where is the base station receiver coordinate, is the satellite coordinate. Then according to the double difference operator Get double differential ground distance .

[0053] Step 2.3: Use the Hopfield model to calculate the zenith tropospheric static delay ZHD and wet delay ZWD of each reference station, and then use the Niell projection function to calculate the projection function value of the static delay of each satellite. MF H and the projection function value of wet delay MF W , get the tropospheric delay of each satellite on the slant path According to the double difference operator Get the double difference tropospheric delay .

[0054] Step 2.4, based on the ionosphere-free combined observations from step 2.1 and , double differential ground-to-ground distance in step 2.2 , double difference tropospheric delay in step 2.3 , calculate the floating point ambiguity corresponding to the ionosphere-free combination, the formula is as follows:

[0055] In the formula , is the wavelength corresponding to the ionosphere-free combination.

[0056] Step 2.5, using the ionospheric-free combined floating ambiguity of step 2.4 and the ultra-wide lane ambiguity of step 1, calculate the floating wide lane ambiguity of BeiDou-2 and BeiDou-3 respectively .

[0057]

[0058] In the formula,

[0059] Step 2.6: Multi-epoch smoothing of the floating-point wide-lane ambiguity obtained in step 2.5, rounding to obtain a fixed value of the wide-lane ambiguity , the formula is as follows:

[0060] In the formula, k is the epoch number. The fixed values ​​of wide lane ambiguity of BeiDou-2 system and BeiDou-3 system are respectively , .

[0061] Step 3: Use the double-difference wide-lane ambiguity determination method in the three-step method to obtain the wide-lane ambiguity of the BeiDou-2 and BeiDou-3 joint system.

[0062] Step 3.1, BeiDou-3 satellite For reference satellites, pseudo-range observation values ​​of double difference B1I and B3I frequencies of BeiDou-2 and BeiDou-3 joint system are established between two reference stations and , phase observation value and .

[0063] Step 3.2, based on the double-difference pseudorange and phase observation values ​​in step 3.1, calculate the initial value of the wide-lane ambiguity of the BeiDou-2 and BeiDou-3 joint system:

[0064] The wavelength of the wide lane combination , pseudorange combination , phase combination

[0065] Step 3.3, based on the double difference phase observations in step 3.1, obtain the ionospheric-free combined pseudorange and phase observations of the double difference B1I and B3I frequencies:

[0066]

[0067] Step 3.4, similar to steps 2.2 and 2.3, re-obtain The double differential Earth-satellite distance of all satellites in the joint system is the reference satellite and double-difference tropospheric delay .

[0068] Step 3.5, based on the ionospheric-free combined pseudorange and phase observations of step 3.3, determine the first form of the ionospheric-free combined ambiguity:

[0069] According to the double differential ground-to-ground distance obtained in step 3.4 and double-difference tropospheric delay , determine the second form of the ionospheric-free combined ambiguity:

[0070] Compare the two forms of ionospheric-free combined ambiguity and obtain the difference between the two forms of ionospheric-free combined ambiguity at this moment Then use the previous k The difference of epochs , by calculating the root mean square of multiple epochs , the calculation formula is:

[0071] When the RMS Convergence, that is and ( N It can be 50 or 100. When it is a positive decimal less than 1, it can be 0.5), it will no longer be updated. , after convergence for , is the standard deviation of the ionospheric-free combined ambiguity.

[0072] Ignore the phase observation noise, and assume that the double-difference pseudorange noise of B1I is 5 times that of B3I, that is, , which can be calculated based on the standard deviation of the ionospheric-free combined ambiguity Calculate double difference pseudorange noise :

[0073] In the formula, Then calculate the standard deviation of the initial value of the wide lane ambiguity in step 3.2 before rounding :

[0074] In the formula, .

[0075] Step 3.6, taking the initial value of wide lane ambiguity obtained in step 3.2 as the center, The search radius is the search radius for wide lane ambiguity. Calculate different wide lane ambiguities The corresponding residual is:

[0076] If the residual value is less than the wavelength of the wide lane combination half of , the corresponding widelane ambiguity is considered to be fixed.

[0077] Step 3.7, use the geometric distance to backcalculate the wide lane ambiguity:

[0078] And compare it with the wide lane ambiguity determined in step 3.6. If the two are consistent, it is considered that the corresponding wide lane ambiguity has been correctly fixed.

[0079] Step 4: Obtain the wide lane ambiguity fixed solution of the BeiDou-2 and BeiDou-3 joint system of the unified reference satellite through transformation. Among them, the BeiDou-3 satellite directly uses the wide lane ambiguity fixed value obtained in step 2 .

[0080] Step 4.1: Select a BeiDou-2 satellite from the satellite pair whose wide-lane ambiguity is correctly fixed in step 3. , the satellite must meet the following two conditions: (1) The satellite involved in the solution in step 2 must be a reference satellite or not. ; (2) The altitude and azimuth of the reference satellite The widelane ambiguity of the selected satellite pair is recorded as .

[0081] Step 4.2, transform the BeiDou-2 wide lane ambiguity fixed value obtained in step 2 to obtain is the fixed value of the wide lane ambiguity of the reference satellite. Specifically: like , then the BeiDou-2 non-reference satellite in step 2 is relative to The wide lane ambiguity is fixed at , BeiDou-2 reference satellite relatively The wide lane ambiguity is fixed at ; like , first find the BeiDou-2 non-reference satellite calculated in step 2 Relative reference satellite The wide lane ambiguity fixed value , then the remaining non-reference satellites of BeiDou-2 are relative The wide lane ambiguity is fixed at , BeiDou-2 non-reference satellite relatively The wide lane ambiguity is fixed at ; BeiDou-2 reference satellite relatively The wide lane ambiguity is fixed at .

[0082] Step 5: Unify For the BeiDou-2 and BeiDou-3 joint systems of reference satellites, the original ambiguities of B1I of all satellites are determined.

[0083] Step 5.1, using the ionospheric-free combined phase observations constructed in step 3.3 , the double differential ground-to-ground distance obtained in step 3.4 and double-difference tropospheric delay , formed with The ionospheric-free combined phase observation equation of the BeiDou-2 and BeiDou-3 joint system is:

[0084] Determine the ionospheric-free combined floating point ambiguity through Kalman filtering ; Step 5.2: Use the relative position of BeiDou-2 satellite and BeiDou-3 satellite obtained in step 4 Wide Lane Ambiguity , combined with the ionospheric-free combined ambiguity determined in step 5.3 , determine the B1I raw ambiguities of all satellites:

[0085] Step 5.3, similar to step 2.6, smoothes the B1I floating point ambiguity obtained in step 5.2 over multiple epochs , rounded to get a fixed value of fuzziness, the formula is as follows:

[0086] In specific implementation, the above process can use computer software technology to realize automatic operation of the process, and the system device that runs the method process of the present invention should also be within the protection scope of the present invention.

[0087] On the other hand, an embodiment of the present invention also provides an inter-reference station ambiguity resolution system for a full-constellation Beidou hybrid signal, including: A processor and a memory, the memory is used to store program instructions, and the processor is used to call the stored instructions in the memory to execute the method described in the above technical solution.

[0088] The specific embodiments described herein are merely examples of the spirit of the present invention. Those skilled in the art may make various modifications or additions to the specific embodiments described or replace them in similar ways, but they will not deviate from the spirit of the present invention or exceed the scope defined by the appended claims.

Claims

1. A method for resolving ambiguity between reference stations of a full-constellation Beidou hybrid signal, characterized in that: The following steps are involved: Step 1: Based on the MW combination rounding method, the ultra-wide lane ambiguity of the BeiDou-2 and BeiDou-3 systems are determined respectively; Step 2: Based on the ionosphere-free combined TCAR method, the wide lane ambiguity fixed values ​​of the BeiDou-2 and BeiDou-3 systems are determined respectively; Step 3, using the double-difference wide lane ambiguity determination method to obtain the wide lane ambiguity of the BeiDou-2 and BeiDou-3 joint system; Step 4, obtain the wide lane ambiguity fixed solution of the BeiDou-2 and BeiDou-3 joint system of the unified reference satellite through transformation; Step 5, for the BeiDou-2 and BeiDou-3 joint system with a unified reference satellite, the ionospheric-free combined ambiguity of the double difference B1I and B3I frequencies is determined based on Kalman filtering, and then combined with the wide lane ambiguity fixed solution to determine the original ambiguity of B1I of all satellites; where B1I and B3I are different frequency signals in BeiDou-2 and BeiDou-3 satellites.

2. The method for resolving ambiguity between reference stations of the full-constellation Beidou hybrid signal according to claim 1, characterized in that: The specific implementation of step 1 includes the following sub-steps: Step 1.1, establish the double-difference pseudo-range and phase observation values ​​of the BeiDou-2 and BeiDou-3 systems between the reference stations; Select the satellite with the highest elevation angle among the BeiDou-2 satellites The satellite with the highest altitude angle among the BeiDou-3 satellites As the reference satellite of each system, the non-combined pseudo-range observation values ​​of each system are obtained through double difference operation and phase observations ; In the formula, It is the double difference operator between different reference stations and between non-reference satellites and reference satellites. The subscripts 1, 2, and 3 represent three different signal frequencies respectively; Step 1.2, based on the double-difference pseudo-range and phase observation values ​​of step 1.1, calculate the double-difference pseudo-range combined virtual observation value And phase combination observations ; in , c is the speed of light, and is a constant; Step 1.3, calculate the ultra-wide lane ambiguity of the BeiDou-2 and BeiDou-3 systems respectively, the formula is as follows: In the formula, The rounding operator.

3. The method for resolving ambiguity between reference stations of the full-constellation Beidou hybrid signal according to claim 2, characterized in that: In step 2, the ionosphere-free combined virtual observations, double differential ground-to-satellite distances and tropospheric delays are used to calculate the ionosphere-free combined floating-point ambiguity, and the fixed value of the wide-lane ambiguity is obtained by multi-epoch smoothing; the specific implementation method is as follows: Step 2.1, using the double difference phase observations from step 1.1, construct two ionosphere-free combined observations: In the formula, , and is a constant; Step 2.2: Determine the geometric distance between each satellite and the reference station based on the precisely known coordinates of the reference station and the calculated satellite positions. , where is the base station receiver coordinate, is the satellite coordinate, and then according to the double difference operator Get double differential ground distance ; Step 2.3: Use the Hopfield model to calculate the zenith tropospheric static delay ZHD and wet delay ZWD of each reference station, and then use the Niell projection function to calculate the projection function value of the static delay of each satellite. MF H and the projection function value of wet delay MF W , get the tropospheric delay of each satellite on the slant path , according to the double difference operator Get the double difference tropospheric delay ; Step 2.4, based on the ionosphere-free combined observations from step 2.1 and , double differential ground-to-ground distance in step 2.2 , double difference tropospheric delay in step 2.3 , calculate the floating point ambiguity corresponding to the ionosphere-free combination, the formula is as follows: In the formula , is the wavelength corresponding to the ionosphere-free combination; Step 2.5, using the ionospheric-free combined floating ambiguity of step 2.4 and the ultra-wide lane ambiguity of step 1, calculate the floating wide lane ambiguity of BeiDou-2 and BeiDou-3 respectively : In the formula, Step 2.6, multi-epoch smoothing of the floating point wide lane ambiguity obtained in step 2.5, rounding to obtain a fixed value of the wide lane ambiguity, the formula is as follows: In the formula, k is the epoch number, is the rounding operator, and the fixed values ​​of wide lane ambiguity of BeiDou-2 system and BeiDou-3 system are , .

4. The method for resolving ambiguity between reference stations of the full-constellation Beidou hybrid signal according to claim 1, characterized in that: In step 3, the BeiDou-3 satellite is used as the reference satellite to form the pseudorange and phase observations of the double-difference B1I and B3I frequencies of the BeiDou-2 and BeiDou-3 joint system between the reference stations. The initial value and fixed solution of the wide lane ambiguity are determined by using the ionosphere-free combined pseudorange and phase observations, which specifically includes the following substeps: Step 3.1, BeiDou-3 satellite For reference satellites, pseudo-range observation values ​​of double difference B1I and B3I frequencies of BeiDou-2 and BeiDou-3 joint system are established between two reference stations and , phase observation value and ; Step 3.2, based on the double-difference pseudorange and phase observation values ​​in step 3.1, calculate the initial value of the wide-lane ambiguity of the BeiDou-2 and BeiDou-3 joint system; Step 3.3, based on the double difference phase observations in step 3.1, obtain the ionospheric-free combined pseudorange of the double difference B1I and B3I frequencies and phase observations , and then calculate the initial value of the wide-lane ambiguity of the BeiDou-2 and BeiDou-3 joint system; Step 3.4, calculate The double differential Earth-satellite distance of all satellites in the joint system is the reference satellite and double-difference tropospheric delay ; Step 3.5, based on the ionospheric-free combined pseudorange and phase observations of step 3.3, determine the first form of the ionospheric-free combined ambiguity: According to the double differential ground-to-ground distance obtained in step 3.4 and double-difference tropospheric delay , determine the second form of the ionospheric-free combined ambiguity: The wavelength of the ionosphere-free combination is compared with the two forms of ionosphere-free combination ambiguity to obtain the difference between the two forms of ionosphere-free combination ambiguity at this moment, and the standard deviation of the wide lane ambiguity before rounding the initial value in step 3.2 is calculated in turn. ; Step 3.6, taking the initial value of wide lane ambiguity obtained in step 3.2 as the center, is the search radius, and the wide lane ambiguity is searched. Different wide lane ambiguities are calculated. The corresponding residual; if the residual value is less than the wide lane combination wavelength half of , the corresponding wide-lane ambiguity is considered to be fixed; In step 3.7, the wide lane ambiguity is obtained by back-calculating the geometric distance and compared with the wide lane ambiguity determined in step 3.

6. If the two are consistent, it is considered that the corresponding wide lane ambiguity has been correctly fixed.

5. The method for resolving ambiguity between reference stations of the full-constellation Beidou hybrid signal according to claim 4, characterized in that: In step 3.2, the initial value of the wide-lane ambiguity of the BeiDou-2 and BeiDou-3 joint system is calculated using the following formula: The wavelength of the wide lane combination , pseudorange combination , phase combination ; , and is a constant, c is the speed of light, The rounding operator.

6. The method for resolving ambiguity between reference stations of the full-constellation Beidou hybrid signal according to claim 4, characterized in that: In step 3.3, the ionospheric-free combined pseudorange of the double difference B1I and B3I frequencies is obtained and phase observations , the calculation formula is as follows: in, , and is a constant.

7. The method for resolving ambiguity between reference stations of the full-constellation Beidou hybrid signal according to claim 4, characterized in that: In step 3.5, the difference between the two forms of ionospheric-free combined ambiguity is first calculated , and then use the previous k The difference of epochs , by calculating the root mean square of multiple epochs , the calculation formula is: When the RMS Convergence, that is and hour, N is a constant, If it is a positive decimal less than 1, it will not be updated. , after convergence for , is the standard deviation of the ionospheric-free combined ambiguity; Ignore the phase observation noise, and assume that the double-difference pseudorange noise of B1I is 5 times that of B3I, that is, , according to the standard deviation of the ionospheric-free combined ambiguity Calculate double difference pseudorange noise : In the formula, ; Then calculate the standard deviation of the wide lane ambiguity before rounding the initial value in step 3.2 : In the formula, , , and is a constant.

8. The method for resolving ambiguity between reference stations of the full-constellation Beidou hybrid signal according to claim 1, characterized in that: In step 4, the wide lane ambiguity of the BeiDou-2 and BeiDou-3 joint system of the unified reference satellite is obtained by transformation, among which the BeiDou-3 satellite directly adopts the wide lane ambiguity fixed value ; Specifically includes the following sub-steps: Step 4.1: Select a BeiDou-2 satellite from the satellite pair whose wide-lane ambiguity is correctly fixed in step 3. , the satellite must meet the following two conditions: (1) The satellite involved in the solution in step 2 must be a reference satellite or not. ; (2) The altitude and azimuth of the reference satellite The widelane ambiguity of the closest selected satellite pair is denoted by ; Step 4.2, transform the BeiDou-2 wide lane ambiguity fixed value obtained in step 2 to obtain is the fixed value of the wide lane ambiguity of the reference satellite; specifically: like , then the BeiDou-2 non-reference satellite in step 2 is relative to The wide lane ambiguity is fixed at , BeiDou-2 reference satellite relatively The wide lane ambiguity is fixed at ; like , first find the BeiDou-2 non-reference satellite calculated in step 2 Relative reference satellite The wide lane ambiguity fixed value , then the remaining non-reference satellites of BeiDou-2 are relative The wide lane ambiguity is fixed at , BeiDou-2 non-reference satellite relatively The wide lane ambiguity is fixed at ; BeiDou-2 reference satellite relatively The wide lane ambiguity is fixed at .

9. The method for resolving ambiguity between reference stations of the full-constellation Beidou hybrid signal according to claim 1, characterized in that: In step 5, the Kalman filter is used to determine the ionospheric-free combined floating point ambiguity, and combined with the wide lane ambiguity, the B1I raw ambiguity of all satellites is finally determined; specifically, the following sub-steps are included: Step 5.1, using the ionospheric-free combined phase observations constructed in step 3.3 , the double differential ground-to-ground distance obtained in step 3.4 and double-difference tropospheric delay , formed with The ionospheric-free combined phase observation equation of the BeiDou-2 and BeiDou-3 joint system is: Determine the ionospheric-free combined floating point ambiguity through Kalman filtering ; Step 5.2: Use the relative position of BeiDou-2 satellite and BeiDou-3 satellite obtained in step 4 Wide Lane Ambiguity , combined with the ionospheric-free combined ambiguity determined in step 5.3 , determine the B1I raw ambiguities of all satellites: , and is a constant; Step 5.3, smoothing the B1I floating point ambiguity obtained in step 5.2 over multiple epochs , rounded to get a fixed value of fuzziness, the formula is as follows: is the rounding operator and k is the number of epochs.

10. The inter-reference station ambiguity resolution system for the full constellation Beidou hybrid signal is characterized by: include: A processor and a memory, the memory is used to store program instructions, and the processor is used to call the stored instructions in the memory to execute the inter-reference station ambiguity resolution method for the full-constellation Beidou hybrid signal as described in any one of claims 1 to 9.

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