An RTK positioning method for urban short baselines based on tri-frequency GNSS

Abstract

This invention provides an RTK positioning method based on a three-frequency GNSS short baseline in urban areas. The method includes acquiring double-difference pseudorange values ​​and double-difference carrier observations at different frequencies to determine the ultra-wide lane ambiguity; obtaining the wide lane ambiguity and calculating the double-difference geometric distance and the original ambiguity; identifying each satellite pair with fixed original ambiguity, dividing the satellite pairs into multiple subsets, each subset containing multiple satellite pairs, and randomly selecting one subset to calculate the rover position correction value; calculating the residuals corresponding to the double-difference equations of each satellite pair; if the residuals are less than a preset residual threshold, recording the double-difference equations of the satellite pairs as interior points of the subset, forming an interior point set of the subset; using the interior point set that satisfies preset rules as the target interior point set, and calculating the rover position correction value based on the double-difference geometric distance of each satellite pair in the target interior point set. This invention achieves high-precision positioning in urban environments by identifying and eliminating incorrectly fixed ambiguities, thus improving the reliability of positioning.

Description

Technical Field

[0001] This invention relates to the field of satellite positioning technology, and in particular to an RTK positioning method based on tri-frequency GNSS urban short baselines. Background Technology

[0002] With the development of intelligent transportation and autonomous driving, the application of vehicles in urban environments is constantly increasing. Accurate location determination is crucial for vehicles operating in urban environments. Precise location information not only provides reasonable navigation services but is also a prerequisite and guarantee for autonomous driving. Therefore, how to accurately and reliably determine the vehicle's location is fundamental to realizing intelligent transportation and autonomous driving, and it is also a current hot topic.

[0003] Global Navigation Satellite Systems (GNSS), as a core component of modern navigation systems, can provide rapid, high-precision positioning services at a relatively low cost. Their absolute position information can also provide error correction for other relative positioning sensors. However, in complex urban environments, the success rate and reliability of RTK (Real-Time Kinematic) high-precision positioning still face challenges due to signal interruptions and reflections.

[0004] The basic principle of RTK positioning is to first fix one antenna in an open area as a base station to reduce interference from multipath effects, and the coordinates of the base station are known. Another antenna is fixed at the user end, such as on a car roof. In RTK operation, using the known base station coordinates and observation data, double-difference calculations are used to suppress or eliminate observation errors of the rover station, such as atmospheric and satellite errors. The carrier phase ambiguity, after double-difference, recovers its integer characteristics. The process of resolving these integers using different methods is called integer ambiguity fixing. After the ambiguity is correctly fixed, the resulting positioning accuracy is two orders of magnitude higher than that of pseudorange positioning. Therefore, studying carrier phase positioning in urban areas has greater significance and potential.

[0005] Existing technologies using RTK positioning include: First, improving the accuracy of floating-point solutions through velocity assistance, thereby increasing the success rate of ambiguity fixation in urban environments; Second, applying some ambiguity fixation algorithms to urban environments, with verification results showing a significant improvement in the GNSS RTK ambiguity fixation rate in urban environments; Third, utilizing integrated navigation modes to improve the performance of urban RTK; Fourth, using a BDS / GPS RTK tightly coupled algorithm with centralized Kalman filtering, which improves both overall positioning accuracy and availability; Fifth, using a tightly coupled BeiDou / inertial / visual autonomous positioning algorithm in complex urban environments to improve availability. However, all of the above algorithms are based on the LAMBDA algorithm for ambiguity resolution. This algorithm has a high computational load, affecting its real-time operating efficiency. Furthermore, the LAMBD algorithm is a geometrically dependent algorithm, meaning that observations from different satellites can influence each other. Frequent non-line-of-sight and multipath errors in urban environments not only make it difficult to fix the ambiguity of their respective satellites but also affect the success rate of ambiguity fixation for other satellites. Therefore, in urban environments, geometrically independent models may be more suitable for RTK positioning.

[0006] A classic geometry-independent model is TCAR. In TCAR, the ultrawide ambiguity is first fixed using pseudorange observations, then the wide-lane ambiguity is fixed, and finally the original ambiguity is fixed to obtain a high-precision positioning solution. To address the insufficient accuracy of pseudorange in complex environments, existing technologies propose using inertial navigation systems (INS) instead of pseudorange observations to fix ultrawide ambiguity, and an improved TCAR method based on hierarchical small search space addition for short baselines. This method avoids errors caused by directly fixing ambiguities. Therefore, current GNSS RTK positioning algorithms in urban environments mainly include: geometry-related ambiguity fixing algorithms based on the LAMBDA algorithm; geometry-independent ambiguity fixing methods based on TCAR; and ambiguity fixing methods assisted by other sensors. After correctly resolving the ambiguities, RTK can achieve centimeter-level positioning accuracy.

[0007] However, in urban environments, the obstruction and reflection from buildings cause non-line-of-sight (NLS) and multipath errors in GNSS, significantly increasing the difficulty of ambiguity fixation. Traditional GNSS-based RTK algorithms not only require substantial computation but also carry the risk of ambiguity fixation errors within a single epoch, leading to significant positioning errors. Furthermore, the complex urban environment presents frequent cycle slips and interruptions in carrier signals, making it difficult to maintain fixed ambiguities. Even if ambiguities are correctly fixed, the process must be repeated after satellite signal loss. This process often places certain demands on the overall satellite observation quality, which is difficult to guarantee in urban environments. Therefore, the positioning accuracy and reliability for vehicles are insufficient in urban environments.

[0008] Therefore, existing technologies have shortcomings and need to be improved and developed. Summary of the Invention

[0009] This application provides an RTK positioning method based on a three-frequency GNSS urban short baseline to solve the technical problem of insufficient positioning accuracy and reliability of vehicles in urban environments in related technologies.

[0010] To achieve the above objectives, this application adopts the following technical solution:

[0011] The first aspect of this application provides an RTK positioning method based on a three-frequency GNSS urban short baseline, comprising:

[0012] Obtain double-difference pseudorange values ​​and double-difference carrier observations at different frequencies, and determine the ultra-wide lane ambiguity based on the double-difference pseudorange values ​​and double-difference carrier observations;

[0013] The wide alley ambiguity is obtained based on the ultra-wide alley ambiguity, and the double-difference geometric distance and the original ambiguity are calculated based on the ultra-wide alley ambiguity and the wide alley ambiguity.

[0014] Each satellite pair with a fixed original ambiguity is identified, the satellite pair is divided into multiple subsets, each subset includes multiple satellite pairs, and the rover position correction value corresponding to the subset is calculated based on the double difference geometric distance of the multiple satellite pairs in the subset;

[0015] The residuals corresponding to the double-difference equations of each satellite pair are calculated based on the mobile station position correction values ​​corresponding to the subset. If the residuals are less than a preset residual threshold, the double-difference equations of the satellite pairs are recorded as interior points of the subset, and an interior point set corresponding to the subset is formed.

[0016] The set of inliers that meet the preset rules is taken as the target inlier set. The final rover position correction value is calculated based on the double difference geometric distance of each satellite pair in the target inlier set.

[0017] Optionally, the step of acquiring double-difference pseudorange values ​​and double-difference carrier observations at different frequencies, and determining the ultra-wide lane ambiguity based on the double-difference pseudorange values ​​and double-difference carrier observations, includes:

[0018] Acquire the first frequency double-difference pseudorange value, the second frequency double-difference pseudorange value, and the third frequency double-difference pseudorange value, and acquire the first frequency double-difference carrier observation value, the second frequency double-difference carrier observation value, and the third frequency double-difference carrier observation value;

[0019] The initial geometric distance is obtained by averaging the first frequency double-difference pseudorange value, the second frequency double-difference pseudorange value, and the third frequency double-difference pseudorange value.

[0020] The second and third frequency wavelengths are obtained, and the ultrawide alley ambiguity is obtained based on the initial geometric distance, the second frequency double-difference carrier observation, the third frequency double-difference carrier observation, the second frequency wavelength, and the third frequency wavelength.

[0021] Optionally, the wide alley ambiguity is obtained based on the ultra-wide alley ambiguity, and the double-difference geometric distance and the original ambiguity are calculated based on the ultra-wide alley ambiguity and the wide alley ambiguity, including:

[0022] The ultra-wide lane wavelength is obtained based on the second and third frequency wavelengths;

[0023] The ultra-wide lane carrier observation is obtained based on the second frequency double-difference carrier observation, the third frequency double-difference carrier observation, the second frequency wavelength, and the third frequency wavelength;

[0024] The corrected geometric distance is obtained based on the ultra-wide lane wavelength, ultra-wide lane carrier observation, and ultra-wide lane ambiguity.

[0025] Obtain the first frequency wavelength, and based on the first frequency wavelength, the second frequency wavelength, the first frequency double-difference carrier observation, the second frequency double-difference carrier observation, and the corrected geometric distance, obtain the wide-lane ambiguity;

[0026] Based on the ultra-wide alley ambiguity, wide alley ambiguity, first frequency double-difference carrier observation, second frequency double-difference carrier observation, third frequency double-difference carrier observation, first frequency wavelength, second frequency wavelength, and third frequency wavelength, the double-difference geometric distance and the original ambiguity are obtained using the least squares method.

[0027] Optionally, determining each satellite pair with fixed original ambiguity, dividing the satellite pair into multiple subsets, each subset including multiple satellite pairs, and calculating the rover position correction value corresponding to the subset based on the double-difference geometric distance of the multiple satellite pairs in the subset, includes:

[0028] Each satellite and the master satellite with fixed original ambiguity are identified, and each satellite forms a satellite pair with the master satellite.

[0029] By randomly selecting three satellite pairs from all satellite pairs to form a subset, we obtain subsets with all different permutations and combinations.

[0030] The rover position correction value corresponding to the subset is calculated based on the double difference geometric distance of the three satellite pairs in any subset.

[0031] Optionally, the step of calculating the rover position correction value corresponding to the subset based on the double-difference geometric distance of the three satellite pairs in any subset includes:

[0032] Obtain the first unit vector pointing from the rover station to each satellite, and the second unit vector pointing from the rover station to the main satellite;

[0033] The double-difference equations for each satellite pair are determined based on the first unit vector, the second unit vector, and the double-difference geometric distance.

[0034] Calculate the relative position precision factor of each subset based on the first unit vector and the second unit vector;

[0035] If the relative position precision factor of the subset is less than the preset precision threshold, then the mobile station position correction value corresponding to the subset is calculated according to the double difference equation.

[0036] If the relative position precision factor of the subset is greater than or equal to the preset precision threshold, then the mobile station position correction value corresponding to the subset is not calculated.

[0037] Optionally, the step of using the set of inliers that satisfy preset rules as the target inlier set, and calculating the final rover position correction value based on the double-difference geometric distances corresponding to each satellite pair in the target inlier set, includes:

[0038] After obtaining the interior point sets corresponding to each subset, the interior point set with the largest number of interior points is taken as the target interior point set.

[0039] If the number of inliers in the target inlier set is greater than or equal to the first preset number threshold, the final rover position correction value is calculated based on the double difference geometric distances corresponding to each satellite pair in the target inlier set.

[0040] If the number of interior points in the target interior point set is less than the first preset threshold, no positioning output will be performed.

[0041] Optionally, the step of using the set of inliers that satisfy preset rules as the target inlier set, and calculating the final rover position correction value based on the double-difference geometric distances corresponding to each satellite pair in the target inlier set, includes:

[0042] When calculating the mobile station position correction value from any subset among multiple subsets and obtaining the current inner point set, if the number of inner points in the current inner point set is greater than the second preset number threshold, then the current inner point set is taken as the target inner point set, and the next subset is not selected.

[0043] The final rover position correction value is calculated based on the double-difference geometric distances of each satellite pair in the target inlier set.

[0044] A second aspect of this application provides an RTK positioning device based on a three-frequency GNSS urban short baseline, characterized in that it includes:

[0045] The acquisition module is used to acquire double-difference pseudorange values ​​and double-difference carrier observations at different frequencies, and to determine the ultra-wide lane ambiguity based on the double-difference pseudorange values ​​and double-difference carrier observations.

[0046] The first calculation module is used to obtain the wide alley ambiguity based on the ultra-wide alley ambiguity, and to calculate the double difference geometric distance and the original ambiguity based on the ultra-wide alley ambiguity and the wide alley ambiguity;

[0047] The determination module is used to determine each satellite pair with fixed original ambiguity, divide the satellite pair into multiple subsets, each subset including multiple satellite pairs, and calculate the rover position correction value corresponding to the subset based on the double difference geometric distance of the multiple satellite pairs in the subset;

[0048] The recording module is used to calculate the residuals corresponding to the double difference equations of each satellite pair based on the mobile station position correction values ​​corresponding to the subset. If the residuals are less than a preset residual threshold, the satellite pair is recorded to the interior point set corresponding to the subset.

[0049] The second calculation module is used to take the set of inliers that meet the preset rules as the target inlier set, and calculate the final rover position correction value based on the double difference geometric distance of each satellite pair in the target inlier set.

[0050] A third aspect of this application provides a terminal device, the terminal device including a memory, a processor, and an RTK positioning program based on a tri-frequency GNSS urban short baseline stored in the memory and executable on the processor. When the processor executes the RTK positioning program based on a tri-frequency GNSS urban short baseline, it implements the steps of the RTK positioning method based on a tri-frequency GNSS urban short baseline as described above.

[0051] A fourth aspect of this application provides a computer-readable storage medium storing an RTK positioning program based on a tri-frequency GNSS urban short baseline. When the RTK positioning program based on a tri-frequency GNSS urban short baseline is executed by a processor, it implements the steps of the RTK positioning method based on a tri-frequency GNSS urban short baseline as described above.

[0052] The beneficial effects of this invention are as follows: In this embodiment, double-difference pseudorange values ​​and double-difference carrier observations at different frequencies are obtained. The ultra-wide lane ambiguity is determined based on these values. Wide lane ambiguity is obtained based on the ultra-wide lane ambiguity, and double-difference geometric distance and original ambiguity are calculated based on the ultra-wide lane ambiguity and wide lane ambiguity. Each satellite pair with a fixed original ambiguity is determined, and the satellite pairs are divided into multiple subsets, each subset including multiple satellite pairs. The rover position correction value corresponding to each subset is calculated based on the double-difference geometric distance of the multiple satellite pairs within the subset. The residuals corresponding to the double-difference equations of each satellite pair are calculated based on the rover position correction values ​​corresponding to the subsets. If the residuals are less than a preset residual threshold, the double-difference equations of the satellite pairs are recorded as interior points of the subset, forming an interior point set corresponding to the subset. The interior point set satisfying a preset rule is used as the target interior point set, and the final rover position correction value is calculated based on the double-difference geometric distance of each satellite pair in the target interior point set. This invention achieves high-precision positioning in urban environments by identifying and eliminating ambiguities that are incorrectly fixed, thereby improving the reliability of positioning. Attached Figure Description

[0053] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the following description of the embodiments taken in conjunction with the accompanying drawings, wherein:

[0054] Figure 1 This is a flowchart of a preferred embodiment of the RTK positioning method based on tri-frequency GNSS urban short baseline in this invention.

[0055] Figure 2 This is a schematic diagram of urban RTK positioning in this invention.

[0056] Figure 3 This is a flowchart of a preferred embodiment of the RTK positioning method based on three-frequency GNSS urban short baseline in this invention.

[0057] Figure 4 This is a functional principle block diagram of a preferred embodiment of the RTK positioning device based on a three-frequency GNSS urban short baseline in this invention.

[0058] Figure 5 This is a functional principle block diagram of a preferred embodiment of the terminal device in this invention. Detailed Implementation

[0059] To make the objectives, technical solutions, and advantages of this invention clearer and more explicit, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0060] Traditional geometrically dependent models, such as the LAMBDA algorithm, theoretically offer the highest success rate in open areas. However, in urban environments, multipath and non-line-of-sight signals introduce significant errors in carrier and pseudorange observations. In geometrically dependent models, these large errors not only affect the floating-point ambiguity accuracy of the corresponding satellite but also further impact the floating-point ambiguity accuracy of other satellites. Secondly, frequent cycle slips and satellite signal interruptions degrade the performance of multi-epoch data processing or filtering. These common strategies for improving ambiguity fixing success rates are difficult to implement in urban environments. In contrast, geometrically independent models fix ambiguities individually for each satellite pair. Therefore, different ambiguity fixing processes are relatively independent, and ambiguity fixing errors in satellites contaminated by multipath or non-line-of-sight signals do not affect the ambiguity fixing of other normal satellites. Thus, geometrically independent models based on three-frequency signals, such as TCAR, have certain advantages in urban environments. In open areas, due to the better satellite signal quality, TCAR has a high success rate. Its fixed ambiguities can be used for positioning after slight processing or directly. However, in urban environments, non-line-of-sight reception and multipath errors result in pseudorange errors ranging from several meters to tens of meters, severely impacting the success rate of ambiguity fixation. Without identifying and eliminating these incorrectly fixed ambiguities, positioning accuracy and reliability cannot be guaranteed. Currently, there are no algorithms specifically designed to detect and eliminate these erroneous ambiguities. Therefore, accurately and reliably identifying and eliminating these incorrectly fixed ambiguities is a crucial problem that urgently needs to be solved to achieve high-precision, single-epoch positioning in urban environments.

[0061] This patent addresses the challenge of fixing ambiguities in urban environments by proposing a positioning algorithm based on a three-frequency combined GNSS double-difference model. Leveraging the high success rate of fixing ultra-wide lane ambiguities, it first fixes the ultra-wide lane ambiguity. Then, it updates the pseudorange using the fixed ultra-wide lane ambiguity, fixing the wide lane ambiguity. Finally, based on the fixed ultra-wide and wide lane ambiguities, it fixes the original carrier ambiguity. After all satellite pair ambiguities are fixed, a designed erroneous ambiguity detection and isolation technique is used to eliminate incorrectly fixed ambiguities. After eliminating incorrectly fixed ambiguities, high-precision positioning can be achieved. It can solve for high-precision positioning results in a single epoch with low computational complexity and high reliability, making it highly practical, especially in areas where GNSS signals are prone to interruption or where high-speed moving objects are present. It is expected to provide support for high-precision and high-reliability positioning services for urban vehicle navigation.

[0062] Please see Figure 1 The RTK positioning method based on tri-frequency GNSS urban short baselines described in this embodiment of the invention includes the following steps:

[0063] Step S100: Obtain the double-difference pseudorange value and double-difference carrier observation at different frequencies, and determine the ultra-wide lane ambiguity based on the double-difference pseudorange value and double-difference carrier observation.

[0064] like Figure 2 As shown, it is assumed that the baseline distance between antenna 1 and antenna 2 is very short. Antenna 1 serves as the base station, and antenna 2 is mounted on the vehicle roof as a slave antenna. Therefore, the atmospheric and satellite-end errors of antennas 1 and 2 can be completely eliminated by double difference. The key point of this application is to construct virtual carrier observations of different wavelengths, thereby fixing ambiguities step by step in order of wavelength from longest to shortest. Addressing the characteristics of GNSS signals being susceptible to interference and having a low success rate in ambiguity fixing in urban environments, a scheme for detecting and eliminating erroneous ambiguities is designed. After eliminating erroneously fixed ambiguities, accurate and reliable positions can be obtained in a single epoch. This algorithm has significant potential for dynamic positioning in urban environments.

[0065] In one embodiment of this application, step S100 specifically includes:

[0066] Step S110: Obtain the first frequency double-difference pseudorange value, the second frequency double-difference pseudorange value and the third frequency double-difference pseudorange value, and obtain the first frequency double-difference carrier observation value, the second frequency double-difference carrier observation value and the third frequency double-difference carrier observation value.

[0067] Step S120: Average the first frequency double-difference pseudorange value, the second frequency double-difference pseudorange value, and the third frequency double-difference pseudorange value to obtain the initial geometric distance;

[0068] Step S130: Obtain the second frequency wavelength and the third frequency wavelength, and obtain the ultrawide alley ambiguity based on the initial geometric distance, the second frequency double-difference carrier observation, the third frequency double-difference carrier observation, the second frequency wavelength, and the third frequency wavelength.

[0069] Specifically, a short-baseline three-frequency ambiguity resolution model is first constructed. For ease of description, the following derivation uses BDS as an example, with its three frequencies as follows: B1 (1561.098MHz), B2 (1207.14MHz), and B3 (1268.52MHz). The same logic applies to other satellite constellations. The double-differenced BDS satellite observation equation is:

[0070] P i =ρ+M i +ε i (1)

[0071] L i =ρ+m i +λ i N i +∈ i (2)

[0072] For ease of description, the double-difference operator is omitted; i represents frequency; P represents double-difference pseudorange value; L represents double-difference carrier observation; ρ is the geometric distance after double-difference; M represents multipath error on pseudorange; m represents multipath error on carrier; λ represents wavelength; N is integer ambiguity; ε represents random noise of pseudorange; and ∈ represents random noise of carrier.

[0073] Because of the short baseline, errors in the troposphere, ionosphere, satellite orbit, satellite clock, and receiver clock are all considered to be completely eliminated. Since multipath errors are difficult to model and have weak correlations between different frequencies, according to equation (1), the average geometric distance at different frequencies is... That is, the initial geometric distance can be estimated as:

[0074]

[0075] Wherein, P1 represents the double-difference pseudorange value of B1, that is, the double-difference pseudorange value of the first frequency; P2 represents the double-difference pseudorange value of B2, that is, the double-difference pseudorange value of the second frequency; and P3 represents the double-difference pseudorange value of B1, that is, the double-difference pseudorange value of the third frequency.

[0076] Based on the initial geometric distance, the ambiguity N of the ultra-wide aisle can be directly determined. (0，-1，1) :

[0077]

[0078] Where, round() means rounding to the nearest integer, L2 represents the second frequency double-difference carrier observation, L3 represents the third frequency double-difference carrier observation, λ2 represents the second frequency wavelength, and λ3 represents the third frequency wavelength.

[0079] like Figure 1 As shown, the RTK positioning method based on tri-frequency GNSS urban short baselines further includes the following steps:

[0080] Step S200: Obtain the wide alley ambiguity based on the ultra-wide alley ambiguity, and calculate the double-difference geometric distance and the original ambiguity based on the ultra-wide alley ambiguity and the wide alley ambiguity.

[0081] In one embodiment of this application, step S200 specifically includes:

[0082] Step S210: Obtain the ultra-wide lane wavelength based on the second frequency wavelength and the third frequency wavelength;

[0083] Step S220: Obtain the ultra-wide lane carrier observation based on the second frequency double-difference carrier observation, the third frequency double-difference carrier observation, the second frequency wavelength, and the third frequency wavelength;

[0084] Step S230: Obtain the corrected geometric distance based on the ultra-wide lane wavelength, ultra-wide lane carrier observation, and ultra-wide lane ambiguity;

[0085] Step S240: Obtain the first frequency wavelength, and obtain the wide lane ambiguity based on the first frequency wavelength, the second frequency wavelength, the first frequency double-difference carrier observation, the second frequency double-difference carrier observation, and the corrected geometric distance;

[0086] Step S250: Based on the ultra-wide alley ambiguity, wide alley ambiguity, first frequency double-difference carrier observation, second frequency double-difference carrier observation, third frequency double-difference carrier observation, first frequency wavelength, second frequency wavelength, and third frequency wavelength, the double-difference geometric distance and the original ambiguity are obtained using the least squares method.

[0087] Specifically, after obtaining the ambiguity of the ultra-wide aisle, a more accurate double-difference geometric distance is obtained. That is, it can be calculated:

[0088]

[0089] Where, λ (0，-1，1) It is an ultra-wide lane wavelength, which meets the requirements. l (0，-1，1) It is an ultra-wide lane carrier observation, the value of which is Note the l here. (0，-1，1) The unit is weeks, while the units for L2 and L3 are meters. (Obtained) Afterwards, the ambiguity N of the wide alley (1，-1，0) It can be calculated as follows:

[0090]

[0091] Where L1 represents the first frequency double-difference carrier observation, and λ1 represents the first frequency wavelength.

[0092] After obtaining the ambiguities of the ultrawide alley and the wide alley, we can obtain the following set of equations:

[0093]

[0094] Ignoring multipath errors, the integer least squares method can be used to obtain the final solution for the double-difference geometric distance and the original ambiguity.

[0095] like Figure 1 As shown, the RTK positioning method based on tri-frequency GNSS urban short baselines further includes the following steps:

[0096] Step S300: Determine each satellite pair with fixed original ambiguity, divide the satellite pair into multiple subsets, each subset including multiple satellite pairs, and calculate the mobile station position correction value corresponding to the subset based on the double difference geometric distance of the multiple satellite pairs in the subset.

[0097] Specifically, embodiments of this application construct an ambiguity detection and selection model. In open areas, the original ambiguity has a very high accuracy rate and can be used for direct positioning after simple filtering. However, in urban environments, due to interference from multipath and non-line-of-sight signals, the success rate of the original ambiguity is greatly reduced. If these erroneously fixed ambiguities are not eliminated, it will lead to huge positioning errors. Based on this, embodiments of this application design a further erroneous ambiguity detection and elimination method.

[0098] In one embodiment of this application, step S300 specifically includes:

[0099] Step S310: Determine each satellite and the master satellite with fixed original ambiguity, and form a satellite pair with the master satellite respectively;

[0100] Step S320: Randomly select three satellite pairs from all satellite pairs to form a subset, thus obtaining subsets with all different permutations and combinations;

[0101] Step S330: Calculate the rover position correction value corresponding to the subset based on the double difference geometric distance of the three satellite pairs in any subset.

[0102] Specifically, if n satellite pairs have their ambiguities fixed in the previous step, then:

[0103]

[0104] Among them, I1 to I n I represents the unit vector pointing from the rover station to each satellite. pivot This represents the unit vector pointing from the rover to the main satellite. ΔX = (Δx, Δy, Δz) is the position correction for the rover.

[0105] For ease of subsequent description, let

[0106] Since three satellite pairs are sufficient for positioning, the satellite pairs are first divided into different subsets, each containing three satellite pairs. The number of subsets is:

[0107]

[0108] The specific subsets are as follows:

[0109] {(1,2,3) (1,2,4) … (n-2,n-1,n)} (10)

[0110] Where (n-2, n-1, n) represents the (n-2), (n-1), and (n-n)th equations in equation (8).

[0111] In one embodiment, step S330 specifically includes:

[0112] Step S331: Obtain the first unit vector pointing from the rover station to each satellite, and the second unit vector pointing from the rover station to the main satellite;

[0113] Step S332: Determine the double-difference equations for each satellite pair based on the first unit vector, the second unit vector, and the double-difference geometric distance;

[0114] Step S333: Calculate the relative position precision factor of each subset based on the first unit vector and the second unit vector;

[0115] Step S334: If the relative position precision factor of the subset is less than the preset precision threshold, then calculate the mobile station position correction value corresponding to the subset according to the double difference equation.

[0116] Step S335: If the relative position precision factor of the subset is greater than or equal to the preset precision threshold, then the mobile station position correction value corresponding to the subset is not calculated.

[0117] Specifically, for any chosen subset (j, k, l), the corresponding double difference equation is:

[0118]

[0119] make The relative position precision factor can be expressed as:

[0120]

[0121] Here, `tr()` represents finding the trace of the matrix. When the relative position precision factor is large, the obtained position error is large. To improve efficiency, when the precision factor is too large (e.g., greater than 10), subsequent operations on the current subset are skipped. When the precision factor is small enough to meet the requirements, the mobile station position correction value ΔX can be obtained. jkl .

[0122] The embodiments of this application improve computational efficiency by calculating the relative position precision factor.

[0123] like Figure 1 As shown, the RTK positioning method based on tri-frequency GNSS urban short baselines further includes the following steps:

[0124] Step S400: Calculate the residuals corresponding to the double-difference equations of each satellite pair based on the mobile station position correction values ​​corresponding to the subset. If the residuals are less than a preset residual threshold, record the double-difference equations of the satellite pair as interior points of the subset and form the interior point set corresponding to the subset.

[0125] Specifically, ΔX jkl Substituting into equation (8), the corresponding residual is:

[0126] V n×1 =R n×1 -G n×1 ·ΔX jkl (13)

[0127] Among them, V n×1 =[v 1 v 2 … v n ] T This is the corresponding residual vector. If the residual corresponding to an equation is very small, it means that the equation fits the subset very well. All equations with residuals less than a preset residual threshold (e.g., 5cm) are collectively referred to as interior points. Since the residuals of the three equations in the subset are 0, the minimum number of interior points is 3.

[0128] For example, subset A obtains a rover position correction value 'a'. Based on this value, the residuals for each satellite pair are calculated. If the residual of satellite pair j-pivot is less than a preset residual threshold, then satellite pair j-pivot is recorded as an interior point of subset A. If the residual is greater than or equal to the preset residual threshold, it is not recorded as an interior point. After traversing all satellite pairs in this way, the interior point set of subset A is formed. Similarly, other subsets can also obtain their corresponding interior point sets.

[0129] like Figure 1 As shown, the RTK positioning method based on tri-frequency GNSS urban short baselines further includes the following steps:

[0130] Step S500: Take the set of inliers that meet the preset rules as the target inlier set, and calculate the final rover position correction value based on the double difference geometric distance of each satellite pair in the target inlier set.

[0131] In the first embodiment of this application, step S500 specifically includes:

[0132] Step S510a: After obtaining the interior point sets corresponding to each subset, take the interior point set with the largest number of interior points as the target interior point set.

[0133] Step S520a: If the number of inliers in the target inlier set is greater than or equal to the first preset number threshold, the final rover position correction value is calculated based on the double difference geometric distances corresponding to each satellite pair in the target inlier set.

[0134] Step S530a: If the number of interior points in the target interior point set is less than the first preset number threshold, then no positioning output is performed.

[0135] Specifically, after processing all subset variables, the set with the largest number of inliers is selected as the final result. These inliers are all considered to be correct fixed ambiguity double-difference equations. To improve reliability, the first preset threshold is set to 5. When the number of inliers is greater than or equal to 5, the final rover position correction value is determined using the least squares method:

[0136]

[0137] Among them, G inliners Let R be the matrix consisting of the difference between the unit vectors of the rover pointing to each satellite in the target's interior point set and the unit vector of the rover pointing to the main satellite. inliers This represents a matrix consisting of the double-difference geometric distances between satellites corresponding to interior points in the target interior point set. G represents inliers The transpose of the matrix. That is, I1 to I in formula (8). n This represents the unit vector pointing from the rover station to each satellite. In this embodiment, some satellites are filtered out, and only the double-difference equations corresponding to the in-point set of the target are used to calculate the final rover station position correction value. Then, based on the rover station position correction value, the approximate coordinates of the rover station receiver are corrected to a higher precision. For example, if the approximate position of the rover station receiver has a 3-meter error, this error is calculated according to the method of this embodiment, and a 3-meter correction is applied to this approximate position. The final result is thus closer to the true position of the rover station receiver.

[0138] If the number of inliers in the target inlier set is less than a preset threshold, no positioning output will be performed. Specifically, if the number of inliers is less than 5, the result is considered unreliable, and no positioning output will be performed to improve the reliability of the positioning.

[0139] In the second embodiment of this application, step S500 specifically includes:

[0140] Step S510b: When calculating the mobile station position correction value from any subset among multiple subsets and obtaining the current inner point set, if the number of inner points in the current inner point set is greater than the second preset number threshold, then the current inner point set is taken as the target inner point set, and the next subset is not selected.

[0141] Step S520b: Calculate the final rover position correction value based on the double-difference geometric distances corresponding to each satellite pair in the target point set.

[0142] Specifically, to save efficiency, this embodiment of the application selects one subset from multiple subsets to calculate the mobile station position correction value, thereby obtaining the inlier set of that subset. For example, if the second preset quantity threshold is set to 10, and the number of inlier sets is greater than 10, it means that the inlier set meets the requirements and can be used as the target inlier set. Therefore, there is no need to calculate other subsets, that is, there is no need to calculate the mobile station position correction value, residual, and inlier set of other subsets, thereby greatly saving computational efficiency.

[0143] The following is a specific example for illustration.

[0144] like Figure 3 As shown, step S1 involves obtaining the pseudorange and carrier phase output between the base station and the mobile station;

[0145] Step S2: Calculate the double-difference observations;

[0146] Step S3: Determine the ambiguity of the ultra-wide alleyway;

[0147] Step S4: Determine the ambiguity of the wide alleyway;

[0148] Step S5: Calculate the original ambiguity;

[0149] Step S6: Blur selection;

[0150] Step S7: Determine whether the set of interior points satisfies the preset rules; if not, proceed to step S8; if yes, proceed to steps S9 and S10.

[0151] Step S8: Unable to locate using carrier waves;

[0152] Step S9: Use the least squares method;

[0153] Step S10: Output the location solution.

[0154] In one embodiment, such as Figure 4 As shown, based on the above-described RTK positioning method using tri-frequency GNSS urban short baselines, this invention also provides a corresponding RTK positioning device based on tri-frequency GNSS urban short baselines, comprising:

[0155] The acquisition module 100 is used to acquire double-difference pseudorange values ​​and double-difference carrier observations at different frequencies, and to determine the ultra-wide lane ambiguity based on the double-difference pseudorange values ​​and double-difference carrier observations.

[0156] The first calculation module 200 is used to obtain the wide alley ambiguity based on the ultra-wide alley ambiguity, and to calculate the double difference geometric distance and the original ambiguity based on the ultra-wide alley ambiguity and the wide alley ambiguity;

[0157] The determination module 300 is used to determine each satellite pair with fixed original ambiguity, divide the satellite pair into multiple subsets, each subset including multiple satellite pairs, and calculate the mobile station position correction value corresponding to the subset based on the double difference geometric distance of the multiple satellite pairs in the subset;

[0158] The recording module 400 is used to calculate the residuals corresponding to the double difference equations of each satellite pair based on the mobile station position correction values ​​corresponding to the subset. If the residuals are less than a preset residual threshold, the satellite pair is recorded to the interior point set corresponding to the subset.

[0159] The second calculation module 500 is used to take the set of inliers that meet the preset rules as the target inlier set, and calculate the final rover position correction value based on the double difference geometric distance of each satellite pair in the target inlier set.

[0160] It should be noted that the foregoing explanation of the embodiment of the RTK positioning method based on tri-frequency GNSS urban short baseline also applies to the RTK positioning device based on tri-frequency GNSS urban short baseline in this embodiment, and will not be repeated here.

[0161] This invention discloses an RTK positioning device based on a three-frequency GNSS urban short baseline. It acquires double-difference pseudorange values ​​and double-difference carrier observations at different frequencies, determines the ultra-wide lane ambiguity based on these values, obtains the wide lane ambiguity based on the ultra-wide lane ambiguity, and calculates the double-difference geometric distance and original ambiguity based on the ultra-wide lane ambiguity and wide lane ambiguity. It identifies satellite pairs with fixed original ambiguities, divides these satellite pairs into multiple subsets, each subset including multiple satellite pairs, and calculates the rover position correction value corresponding to each subset based on the double-difference geometric distance of the multiple satellite pairs within each subset. It calculates the residuals corresponding to the double-difference equations of each satellite pair based on the rover position correction values ​​corresponding to the subsets. If the residuals are less than a preset residual threshold, the double-difference equations of the satellite pairs are recorded as interior points of the subset, forming an interior point set corresponding to the subset. The interior point set satisfying preset rules is used as the target interior point set, and the final rover position correction value is calculated based on the double-difference geometric distances corresponding to each satellite pair in the target interior point set. This invention achieves high-precision positioning in urban environments by identifying and eliminating ambiguities that are incorrectly fixed, thereby improving the reliability of positioning.

[0162] Figure 5 A schematic diagram of the structure of a terminal device provided in an embodiment of this application. The terminal device may include:

[0163] The memory 501, the processor 502, and the computer program stored on the memory 501 and capable of running on the processor 502.

[0164] When the processor 502 executes the program, it implements the RTK positioning method based on tri-frequency GNSS urban short baselines provided in the above embodiments.

[0165] Furthermore, the terminal equipment also includes:

[0166] Communication interface 503 is used for communication between memory 501 and processor 502.

[0167] The memory 501 is used to store computer programs that can run on the processor 502.

[0168] The memory 501 may include high-speed RAM memory, and may also include non-volatile memory, such as at least one disk storage device.

[0169] If the memory 501, processor 502, and communication interface 503 are implemented independently, they can be interconnected via a bus to communicate with each other. The bus can be an Industry Standard Architecture (ISA) bus, a Peripheral Component Interconnect (PCI) bus, or an Extended Industry Standard Architecture (EISA) bus, etc. Buses can be categorized as address buses, data buses, control buses, etc. For ease of representation, only one line is used in the diagram, but this does not imply that there is only one bus or one type of bus.

[0170] Optionally, in a specific implementation, if the memory 501, processor 502, and communication interface 503 are integrated on a single chip, then the memory 501, processor 502, and communication interface 503 can communicate with each other through an internal interface.

[0171] Processor 502 may be a central processing unit (CPU), an application specific integrated circuit (ASIC), or one or more integrated circuits configured to implement the embodiments of this application.

[0172] This embodiment also provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the above-described RTK positioning method based on tri-frequency GNSS urban short baselines.

[0173] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0174] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "N" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0175] Any process or method description in the flowchart or otherwise herein can be understood as representing a module, segment, or portion of code comprising one or N executable instructions for implementing custom logic functions or processes, and the scope of the preferred embodiments of this application includes additional implementations in which functions may be performed not in the order shown or discussed, including substantially simultaneously or in reverse order depending on the functions involved, as should be understood by those skilled in the art to which embodiments of this application pertain.

[0176] The logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as a ordered list of executable instructions for implementing logical functions, and can be embodied in any computer-readable medium for use by, or in conjunction with, an instruction execution system, apparatus, or device (such as a computer-based system, a processor-included system, or other system that can read and execute instructions from or in conjunction with such an instruction execution system, apparatus, or device). For the purposes of this specification, "computer-readable medium" can be any means that can contain, store, communicate, propagate, or transmit programs for use by or in conjunction with an instruction execution system, apparatus, or device. More specific examples (a non-exhaustive list) of computer-readable media include: an electrical connection having one or more wires (electronic device), a portable computer disk drive (magnetic device), random access memory (RAM), read-only memory (ROM), erasable and editable read-only memory (EPROM or flash memory), fiber optic devices, and portable optical disc read-only memory (CDROM). In addition, computer-readable media can even be paper or other suitable media on which programs can be printed, because programs can be obtained electronically by optically scanning paper or other media, then editing, interpreting or otherwise processing them as necessary, and then storing them in computer memory.

[0177] It should be understood that the various parts of this application can be implemented using hardware, software, firmware, or a combination thereof. In the above embodiments, the N steps or methods can be implemented using software or firmware stored in memory and executed by a suitable instruction execution system. If implemented in hardware, as in another embodiment, it can be implemented using any one or a combination of the following techniques known in the art: discrete logic circuits having logic gates for implementing logical functions on data signals, application-specific integrated circuits (ASICs) having suitable combinational logic gates, programmable gate arrays (PGAs), field-programmable gate arrays (FPGAs), etc.

[0178] Those skilled in the art will understand that all or part of the steps of the methods described in the above embodiments can be implemented by a program instructing related hardware, and the program can be stored in a computer-readable storage medium. When executed, the program includes one or a combination of the steps of the method embodiments.

[0179] Furthermore, the functional units in the various embodiments of this application can be integrated into a processing module, or each unit can exist physically separately, or two or more units can be integrated into a module. The integrated module can be implemented in hardware or as a software functional module. If the integrated module is implemented as a software functional module and sold or used as an independent product, it can also be stored in a computer-readable storage medium.

[0180] The storage medium mentioned above can be a read-only memory, a disk, or an optical disk, etc. Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of this application.

Claims

1. An RTK positioning method based on tri-frequency GNSS urban short baselines, characterized in that, include: Obtain double-difference pseudorange values ​​and double-difference carrier observations at different frequencies, and determine the ultra-wide lane ambiguity based on the double-difference pseudorange values ​​and double-difference carrier observations; The wide alley ambiguity is obtained based on the ultra-wide alley ambiguity, and the double-difference geometric distance and the original ambiguity are calculated based on the ultra-wide alley ambiguity and the wide alley ambiguity. Each satellite pair with a fixed original ambiguity is identified, the satellite pair is divided into multiple subsets, each subset includes multiple satellite pairs, and the rover position correction value corresponding to the subset is calculated based on the double difference geometric distance of the multiple satellite pairs in the subset; The residuals corresponding to the double-difference equations of each satellite pair are calculated based on the mobile station position correction values ​​corresponding to the subset. If the residuals are less than a preset residual threshold, the double-difference equations of the satellite pairs are recorded as interior points of the subset, and an interior point set corresponding to the subset is formed. The set of inliers that meet the preset rules is taken as the target inlier set. The final rover position correction value is calculated based on the double difference geometric distance of each satellite pair in the target inlier set. The process of determining each satellite pair with fixed original ambiguity, dividing the satellite pair into multiple subsets, each subset including multiple satellite pairs, and calculating the rover position correction value corresponding to the subset based on the double-difference geometric distance of the multiple satellite pairs in the subset includes: Each satellite and the master satellite with fixed original ambiguity are identified, and each satellite forms a satellite pair with the master satellite. By randomly selecting three satellite pairs from all satellite pairs to form a subset, we obtain subsets with all different permutations and combinations. Calculate the rover position correction value corresponding to the subset based on the double difference geometric distance of the three satellite pairs in any subset; The step of calculating the rover position correction value corresponding to the subset based on the double-difference geometric distance of three satellite pairs in any subset includes: Obtain the first unit vector pointing from the rover station to each satellite, and the second unit vector pointing from the rover station to the main satellite; The double-difference equations for each satellite pair are determined based on the first unit vector, the second unit vector, and the double-difference geometric distance. Calculate the relative position precision factor of each subset based on the first unit vector and the second unit vector; If the relative position precision factor of the subset is less than the preset precision threshold, then the mobile station position correction value corresponding to the subset is calculated according to the double difference equation. If the relative position precision factor of the subset is greater than or equal to the preset precision threshold, then the mobile station position correction value corresponding to the subset is not calculated.

2. The RTK positioning method based on tri-frequency GNSS urban short baselines according to claim 1, characterized in that, The process of acquiring double-difference pseudorange values ​​and double-difference carrier observations at different frequencies, and determining the ultra-wide lane ambiguity based on the double-difference pseudorange values ​​and double-difference carrier observations, includes: Acquire the first frequency double-difference pseudorange value, the second frequency double-difference pseudorange value, and the third frequency double-difference pseudorange value, and acquire the first frequency double-difference carrier observation value, the second frequency double-difference carrier observation value, and the third frequency double-difference carrier observation value; The initial geometric distance is obtained by averaging the first frequency double-difference pseudorange value, the second frequency double-difference pseudorange value, and the third frequency double-difference pseudorange value. The second and third frequency wavelengths are obtained, and the ultrawide alley ambiguity is obtained based on the initial geometric distance, the second frequency double-difference carrier observation, the third frequency double-difference carrier observation, the second frequency wavelength, and the third frequency wavelength.

3. The RTK positioning method based on tri-frequency GNSS urban short baselines according to claim 2, characterized in that, The wide alley ambiguity is obtained based on the ultra-wide alley ambiguity, and the double-difference geometric distance and original ambiguity are calculated based on the ultra-wide alley ambiguity and the wide alley ambiguity, including: The ultra-wide lane wavelength is obtained based on the second and third frequency wavelengths; The ultra-wide lane carrier observation is obtained based on the second frequency double-difference carrier observation, the third frequency double-difference carrier observation, the second frequency wavelength, and the third frequency wavelength; The corrected geometric distance is obtained based on the ultra-wide lane wavelength, ultra-wide lane carrier observation, and ultra-wide lane ambiguity. Obtain the first frequency wavelength, and based on the first frequency wavelength, the second frequency wavelength, the first frequency double-difference carrier observation, the second frequency double-difference carrier observation, and the corrected geometric distance, obtain the wide-lane ambiguity; Based on the ultra-wide alley ambiguity, wide alley ambiguity, first frequency double-difference carrier observation, second frequency double-difference carrier observation, third frequency double-difference carrier observation, first frequency wavelength, second frequency wavelength, and third frequency wavelength, the double-difference geometric distance and the original ambiguity are obtained using the least squares method.

4. The RTK positioning method based on tri-frequency GNSS urban short baselines according to claim 1, characterized in that, The step of using the set of inliers that meet preset rules as the target inlier set, and calculating the final rover position correction value based on the double-difference geometric distances corresponding to each satellite pair in the target inlier set, includes: After obtaining the interior point sets corresponding to each subset, the interior point set with the largest number of interior points is taken as the target interior point set. If the number of inliers in the target inlier set is greater than or equal to the first preset number threshold, the final rover position correction value is calculated based on the double difference geometric distances corresponding to each satellite pair in the target inlier set. If the number of interior points in the target interior point set is less than the first preset threshold, no positioning output will be performed.

5. The RTK positioning method based on tri-frequency GNSS urban short baselines according to claim 1, characterized in that, The step of using the set of inliers that meet preset rules as the target inlier set, and calculating the final rover position correction value based on the double-difference geometric distances corresponding to each satellite pair in the target inlier set, includes: When calculating the mobile station position correction value from any subset among multiple subsets and obtaining the current inner point set, if the number of inner points in the current inner point set is greater than the second preset number threshold, then the current inner point set is taken as the target inner point set, and the next subset is not selected. The final rover position correction value is calculated based on the double-difference geometric distances of each satellite pair in the target inlier set.

6. An RTK positioning device based on tri-frequency GNSS urban short baseline, characterized in that, include: The acquisition module is used to acquire double-difference pseudorange values ​​and double-difference carrier observations at different frequencies, and to determine the ultra-wide lane ambiguity based on the double-difference pseudorange values ​​and double-difference carrier observations. The first calculation module is used to obtain the wide alley ambiguity based on the ultra-wide alley ambiguity, and to calculate the double difference geometric distance and the original ambiguity based on the ultra-wide alley ambiguity and the wide alley ambiguity; The determination module is used to determine each satellite pair with fixed original ambiguity, divide the satellite pair into multiple subsets, each subset including multiple satellite pairs, and calculate the rover position correction value corresponding to the subset based on the double difference geometric distance of the multiple satellite pairs in the subset; The recording module is used to calculate the residuals corresponding to the double difference equations of each satellite pair based on the mobile station position correction values ​​corresponding to the subset. If the residuals are less than a preset residual threshold, the satellite pair is recorded to the interior point set corresponding to the subset. The second calculation module is used to take the set of inliers that meet the preset rules as the target inlier set, and calculate the final rover position correction value based on the double difference geometric distance of each satellite pair in the target inlier set. The process of determining each satellite pair with fixed original ambiguity, dividing the satellite pair into multiple subsets, each subset including multiple satellite pairs, and calculating the rover position correction value corresponding to the subset based on the double-difference geometric distance of the multiple satellite pairs in the subset includes: Each satellite and the master satellite with fixed original ambiguity are identified, and each satellite forms a satellite pair with the master satellite. By randomly selecting three satellite pairs from all satellite pairs to form a subset, we obtain subsets with all different permutations and combinations. Calculate the rover position correction value corresponding to the subset based on the double difference geometric distance of the three satellite pairs in any subset; The step of calculating the rover position correction value corresponding to the subset based on the double-difference geometric distance of three satellite pairs in any subset includes: Obtain the first unit vector pointing from the rover station to each satellite, and the second unit vector pointing from the rover station to the main satellite; The double-difference equations for each satellite pair are determined based on the first unit vector, the second unit vector, and the double-difference geometric distance. Calculate the relative position precision factor of each subset based on the first unit vector and the second unit vector; If the relative position precision factor of the subset is less than the preset precision threshold, then the mobile station position correction value corresponding to the subset is calculated according to the double difference equation. If the relative position precision factor of the subset is greater than or equal to the preset precision threshold, then the mobile station position correction value corresponding to the subset is not calculated.

7. A terminal device, characterized in that, The terminal device includes a memory, a processor, and an RTK positioning program based on a tri-frequency GNSS urban short baseline stored in the memory and executable on the processor. When the processor executes the RTK positioning program based on a tri-frequency GNSS urban short baseline, it implements the steps of the RTK positioning method based on a tri-frequency GNSS urban short baseline as described in any one of claims 1-5.

8. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores an RTK positioning program based on a tri-frequency GNSS urban short baseline. When the RTK positioning program based on a tri-frequency GNSS urban short baseline is executed by a processor, it implements the steps of the RTK positioning method based on a tri-frequency GNSS urban short baseline as described in any one of claims 1-5.

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