A method and device for improving differential positioning performance of a GNSS navigation system

Abstract

The present invention relates to a method and device for improving the differential positioning performance of a GNSS navigation system, wherein the method comprises: obtaining original observations from a GNSS system and obtaining differential observation information from a reference end; constructing a single difference equation based on the original observations and the differential observation information; performing quality control processing on the single difference equation using the consistency between the GNSS systems to eliminate observations with pseudorange errors exceeding a threshold and observations with carrier tracking errors exceeding a threshold, and obtaining candidate observation satellites; selecting a satellite from the candidate observation satellites as a reference satellite to construct a double difference observation equation; and positioning based on the double difference observation equation. The present invention can improve the accuracy of carrier phase differential positioning as a whole.

Description

Technical Field

[0001] The present invention relates to the field of positioning and navigation technology, and in particular to a method and device for improving the differential positioning performance of a GNSS navigation system. Background Art

[0002] In traditional navigation and positioning algorithms, since the main navigation frequency bands of various systems are different, when performing positioning solutions, the observation quantities of each system can only be jointly calculated within the system, and then the positioning results are obtained by combining multiple systems.

[0003] Under the requirements of cooperation and coordination for compatibility and interoperability among global satellite navigation systems, the civil navigation frequencies of major satellite navigation systems are mainly concentrated on L1 (1575.420Mhz) and L5 (1176.450Mhz). This can simplify the design of receiver navigation chip terminals, effectively reduce resources and power consumption, and also provide new ideas for positioning solution methods.

[0004] Since the existing methods only process the observable quantities within the system, the number of observable satellites is limited. Especially in an obstructed environment, when there are only 2 to 3 observable satellites in a single system, the reliability of data processing is sharply reduced, the stability of floating-point solution / fixed solution positioning is reduced, and the positioning error becomes larger. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a method and device for improving the differential positioning performance of a GNSS navigation system, which can improve the positioning accuracy when a single system observes a small number of satellites.

[0006] The technical solution adopted by the present invention to solve the technical problem is: to provide a method for improving the differential positioning performance of a GNSS navigation system, comprising the following steps:

[0007] Acquire original observations from the GNSS system, and acquire differential observation information from a reference end, wherein the original observations and the differential observation information are subjected to the same preprocessing;

[0008] Constructing a single difference equation based on the original observations and the differential observation information;

[0009] Performing quality control processing on the single-difference equation by using the consistency between the GNSS systems to eliminate observations with pseudorange errors exceeding a threshold and observations with carrier tracking errors exceeding a threshold, thereby obtaining candidate observation satellites;

[0010] Selecting a satellite from the candidate observation satellites as a reference satellite to form a double difference observation equation;

[0011] Positioning is performed based on the double difference observation equation.

[0012] The obtaining of differential observation information from the reference end specifically includes: uniformly observing the navigation signals of the GNSS system satellites through the reference station receiver and generating differential original observation information, or generating multi-system differential original observation information by a virtual reference station obtained through joint processing of multiple base stations, or obtaining differential correction information through satellite-based augmentation satellites.

[0013] The single difference equation is the pseudorange and carrier single difference observation equation: in, represents the single-difference pseudorange observation, represents the single-difference satellite station distance, c represents the speed of light, Δdt r represents the difference between the receiving end clock error and the reference end clock error, ε p represents the pseudorange observation noise, represents the single-difference carrier phase observation, λ represents the carrier wavelength, represents the single-difference carrier initial ambiguity, ε Φ represents the carrier phase observation noise.

[0014] The positioning based on the double difference observation equation is specifically as follows:

[0015] Combined with the motion model of the receiving end, a floating-point solution filtering equation is established and filtering is performed;

[0016] Get the floating point solution filtering result and perform ambiguity integer search;

[0017] Through the searched integer ambiguity, the fixed solution double difference solution equation is established and the fixed solution is solved;

[0018] Obtain the fixed solution positioning result according to the fixed solution calculation result.

[0019] The GNSS system includes one or more of the following: the US Global Positioning System GPS, China's Beidou Satellite Navigation System BDS, Russia's Global Navigation Satellite System GLONASS, Europe's Galileo Satellite Navigation System GALILEO, India's Regional Navigation Satellite System IRNSS, and Japan's Quasi-Zenith Satellite System QZSS.

[0020] The technical solution adopted by the present invention to solve the technical problem is: to provide a device for improving the differential positioning performance of a GNSS navigation system, comprising:

[0021] An acquisition module, used to acquire original observations from the GNSS system and differential observation information from the reference end, wherein the original observations and differential observation information are subjected to the same preprocessing;

[0022] A construction module, used for constructing a single difference equation based on the original observations and differential observation information;

[0023] A quality control module, used to perform quality control processing on the single difference equation by using the consistency between the GNSS systems, so as to eliminate observations with pseudorange errors exceeding a threshold and observations with carrier tracking errors exceeding a threshold, and obtain candidate observation satellites;

[0024] A building module, used for selecting a satellite from the candidate observation satellites as a reference satellite to build a double difference observation equation;

[0025] A positioning module is used for positioning based on the double difference observation equation.

[0026] The acquisition module acquires the differential observation information from the reference end by uniformly observing the navigation signals of the GNSS system satellites through the reference station receiver and generating differential original observation information, or by generating multi-system differential original observation information from a virtual reference station obtained through joint processing of multiple base stations, or by acquiring differential correction information through satellite-based augmentation satellites.

[0027] The single difference equation is the pseudorange and carrier single difference observation equation: in, represents the single-difference pseudorange observation, represents the single-difference satellite station distance, c represents the speed of light, Δdt r represents the difference between the receiving end clock error and the reference end clock error, ε p represents the pseudorange observation noise, represents the single-difference carrier phase observation, λ represents the carrier wavelength, represents the single-difference carrier initial ambiguity, ε Φ represents the carrier phase observation noise.

[0028] The positioning module comprises:

[0029] Modeling and filtering unit, used to establish floating-point solution filtering equation and perform filtering processing in combination with the receiving end motion model;

[0030] A search unit, used to obtain floating point solution filtering results and perform ambiguity integer search;

[0031] An equation solving unit is used to establish a fixed solution double difference solving equation through the searched integer ambiguity and perform fixed solution solving;

[0032] The positioning unit is used to obtain a fixed solution positioning result according to the fixed solution calculation result.

[0033] The GNSS system includes one or more of the following: the US Global Positioning System GPS, China's Beidou Satellite Navigation System BDS, Russia's Global Navigation Satellite System GLONASS, Europe's Galileo Satellite Navigation System GALILEO, India's Regional Navigation Satellite System IRNSS, and Japan's Quasi-Zenith Satellite System QZSS.

[0034] Beneficial Effects

[0035] Due to the adoption of the above technical solution, the present invention has the following advantages and positive effects compared with the prior art: the method of cross-system joint processing of observations of the present invention improves the stability of data processing. In particular, in a severe occlusion environment, when there are too few satellites in a single system, the satellite observations of all other systems can be used for joint processing to increase the number of effective observations during processing, thereby achieving the purpose of improving positioning accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 is an application scenario diagram of the first embodiment of the present invention;

[0037] Figure 2 is a flow chart of a second embodiment of the present invention;

[0038] Figure 3 It is an application scenario diagram of the third embodiment of the present invention. DETAILED DESCRIPTION

[0039] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall within the scope limited by the appended claims of the application equally.

[0040] The first embodiment of the present invention relates to a method for improving the differential positioning performance of a GNSS navigation system, comprising the following steps: obtaining original observations from a GNSS system and obtaining differential observation information from a reference end; constructing a single-difference equation based on the original observations and the differential observation information; performing quality control processing on the single-difference equation using the consistency between the GNSS systems to eliminate observations whose pseudorange errors exceed a threshold and observations whose carrier tracking errors exceed a threshold, thereby obtaining candidate observation satellites; selecting a satellite from the candidate observation satellites as a reference satellite to form a double-difference observation equation; and performing positioning based on the double-difference observation equation.

[0041] Figure 1The main equipment and systems involved in this embodiment are briefly described, which is a typical GNSS multi-system joint high-precision real-time dynamic differential (Real Time Kinematic, referred to as RTK) positioning application scenario. The reference base station 1, here refers to the base station receiver, which can uniformly observe the navigation signals of the multi-system satellite 2 and generate differential original observation information, or the multi-system differential original observation information generated by the virtual reference station obtained by joint processing of multiple base stations. For the actual physical reference receiver, the original observation information of the base station needs to use the same signal link to process the navigation signals of the multi-system same-frequency point, so that the pseudo-range observation clock error and the carrier observation phase consistency can be obtained. For the mobile station receiver 3, the navigation signals of the multi-system satellite 2 can also be observed, and the pseudo-range observation and carrier observation can be obtained using the same signal link method. When the mobile station obtains the reference station data through the differential data stream, the method of this embodiment can be used to jointly process the observations of the multi-system same-frequency points, thereby improving the positioning stability and positioning accuracy of the floating point solution / fixed solution.

[0042] Figure 2 The implementation steps of this embodiment are described. Usually, the input of the GNSS positioning algorithm is the original observation data. First, step S01 is entered to pre-process the observation data and retain the correct and valid original observation data; then step S02 is entered, and the reference base station data is also pre-processed to complete the preliminary extraction of all input observations, retaining the correct and valid observations that can be differentially calculated by common observations. Then step S03 is entered to form a single difference equation. In the above case, the consistency of multi-system observations is used, and the deviations between the single difference equations of multiple systems have been eliminated.

[0043] The pseudorange and carrier observation equations are:

[0044]

[0045]

[0046] Then the pseudorange and carrier single difference observation equation is:

[0047]

[0048]

[0049] in, represents the pseudorange observation, represents the distance between satellite stations, c represents the speed of light, and dt r represents the station clock error, dt s represents the satellite clock error, represents the ionospheric delay, represents the tropospheric delay, εp represents the pseudorange observation noise, represents the carrier phase observation, λ represents the carrier wavelength, represents the initial ambiguity of the carrier, ε Φ represents the carrier phase observation noise, represents the single-difference pseudorange observation, Denotes the single-difference satellite station distance, Δdt r represents the difference between the receiving end clock error and the reference end clock error, ε p represents the pseudorange observation noise, represents the single-difference carrier phase observation, represents the single-difference carrier initial ambiguity, ε Φ represents the carrier phase observation noise.

[0050] In this embodiment, Δdt r That is, the difference between the mobile station clock error and the reference station clock error. The key factor for multi-system joint calculation is the consistency of the clock error difference in the single difference equation at the same frequency point. Since the same-frequency point processing of the observation is consistent, the clock error between the mobile station and the reference station receiver systems is the same, so the clock error difference is the same value. At this time, the consistency between the systems can be used to perform quality control on the observation, that is, enter step S04, and the multi-system pseudorange equation is combined with the weighted operation of the star kicking to obtain candidate satellites, mainly to eliminate the observation with large pseudorange error and the observation with excessive carrier tracking error, so as to improve the stability of subsequent solution and improve positioning accuracy.

[0051] Under the above conditions, step S05 is entered, and the multi-system observation quantity can select only one reference satellite from the candidate satellites, and then step S06 is entered to form a double-difference observation equation according to the selected reference satellite. Then step S07 is entered, and the floating-point solution filtering equation is established and filtered in combination with the receiver motion model. Step S08, the floating-point solution filtering result is obtained and the ambiguity is searched. Compared with the traditional method, since this embodiment has only one reference satellite, the input information after the double difference is more, and the floating-point solution positioning result can converge faster. In the case of severe occlusion, when the single-system observation quantity is insufficient, the traditional method is difficult to filter and maintain, and the multi-system joint solution method has the opportunity to maintain a high-precision floating-point solution positioning method. Under normal circumstances, the positioning result of the floating-point solution filtering equation can reach the decimeter level after convergence. During the filtering process, the integer ambiguity search will also be performed to obtain the correct integer ambiguity. Then, in step S09, a fixed solution double-difference solution equation can be established, and a centimeter-level high-precision positioning result can be obtained in step S10. The method of selecting only one reference satellite for multiple systems is also applicable to the double-difference fixed solution positioning method. When there are more satellite observations, it can provide more observation information, help control the quality of the observations, and improve positioning stability under occlusion or interference. When there are fewer satellite observations and a single system cannot continue to solve, there is an opportunity to continue high-precision positioning.

[0052] The second embodiment of the present invention also relates to a method for improving the differential positioning performance of a GNSS navigation system. The difference between the second embodiment and the first embodiment is that the present embodiment does not use a reference base station when acquiring differential observation information. Figure 3 Briefly describes the main equipment and systems involved in this implementation. Figure 1 In the typical GNSS high-precision RTK positioning application scenario, this implementation reduces the dependence on the reference base station. On the basis of the processing of the mobile station receiver 3 and the multi-system satellite 2, it adds support for the satellite-based augmentation satellite 4. From the above derivation, it can be seen that the key factor in the joint solution of multiple systems is to eliminate the deviation between systems. In the process of global promotion of major satellite navigation systems in the world, the requirements for cooperation and coordination of compatibility and interoperability among major navigation systems have been mentioned. In addition to unifying the navigation frequency points to simplify the receiver design, it is also required to broadcast the system time deviation between navigation systems in the telegram. When the accuracy of the system time deviation between systems is high enough, the system time deviation in the pseudorange and carrier single-difference observation equations can be achieved without the use of base station data. It can completely eliminate the dependence on the reference base station when the satellite-based augmentation satellite 4 obtains the differential correction information. After obtaining the differential correction information, the single-difference observation equation can be constructed in combination with the original observation. The subsequent steps are the same as the first implementation method and will not be repeated here. Figure 3In the scenario described, multi-system joint high-precision positioning solution is realized, thereby improving the positioning stability and positioning accuracy of the floating point solution / fixed solution in this application scenario.

[0053] The third embodiment of the present invention relates to a device for improving the differential positioning performance of a GNSS navigation system, including: an acquisition module for acquiring original observations from a GNSS system and differential observation information from a reference end, wherein the original observations and differential observation information are subjected to the same preprocessing; a construction module for constructing a single-difference equation based on the original observations and differential observation information; a quality control module for performing quality control processing on the single-difference equation using the consistency between the GNSS systems to eliminate observations with pseudorange errors exceeding a threshold and observations with carrier tracking errors exceeding a threshold, and obtaining candidate observation satellites; a construction module for selecting a satellite from the candidate observation satellites as a reference satellite to construct a double-difference observation equation; and a positioning module for positioning based on the double-difference observation equation. The GNSS system includes one or more of the following: the US Global Positioning System GPS, China's Beidou Satellite Navigation System BDS, Russia's Global Navigation Satellite System GLONASS, Europe's Galileo Satellite Navigation System GALILEO, India's Regional Navigation Satellite System IRNSS, and Japan's Quasi-Zenith Satellite System QZSS.

[0054] The acquisition module acquires the differential observation information from the reference end by uniformly observing the navigation signals of the GNSS system satellites through the reference station receiver and generating differential original observation information, or by generating multi-system differential original observation information from a virtual reference station obtained through joint processing of multiple base stations, or by acquiring differential correction information through satellite-based augmentation satellites.

[0055] The single difference equation is the pseudorange and carrier single difference observation equation: in, represents the single-difference pseudorange observation, represents the single-difference satellite station distance, c represents the speed of light, Δdt r represents the difference between the receiving end clock error and the reference end clock error, ε p represents the pseudorange observation noise, represents the single-difference carrier phase observation, λ represents the carrier wavelength, represents the single-difference carrier initial ambiguity, ε Φ represents the carrier phase observation noise.

[0056] The positioning module includes: a modeling and filtering unit, which is used to establish a floating-point solution filtering equation and perform filtering processing in combination with a receiving end motion model; a search unit, which is used to obtain a floating-point solution filtering result and perform an ambiguity integer search; an equation solving unit, which is used to establish a fixed solution double difference solution equation through the searched integer ambiguity and perform fixed solution solving; and a positioning unit, which is used to obtain a fixed solution positioning result according to the fixed solution solving result.

[0057] It is not difficult to find that the method of cross-system joint processing of observations of the present invention improves the stability of data processing. In particular, in a severe occlusion environment, when there are too few satellites in a single system, the satellite observations of all other systems can be used for joint processing to increase the number of observations to be processed, thereby achieving the purpose of improving positioning accuracy.

Claims

1. A method for improving the differential positioning performance of a GNSS navigation system, characterized in that: The following steps are involved: Acquire original observations from the GNSS system, and acquire differential observation information from the reference end, wherein the original observations and the differential observation information are preprocessed in the same manner, and acquiring the differential observation information from the reference end specifically comprises: uniformly observing the navigation signals of the GNSS system satellites through a reference station receiver and generating differential original observation information, or generating multi-system differential original observation information through a virtual reference station obtained through joint processing of multiple base stations, or acquiring differential correction information through a satellite-based augmentation satellite; A single difference equation is constructed based on the original observation quantity and the differential observation information; the single difference equation is a pseudorange and carrier single difference observation equation: in, represents the single-difference pseudorange observation, represents the single-difference satellite station distance, c represents the speed of light, Δdt r represents the difference between the receiving end clock error and the reference end clock error, ε p represents the pseudorange observation noise, represents the single-difference carrier phase observation, λ represents the carrier wavelength, represents the single-difference carrier initial ambiguity, ε Φ represents the carrier phase observation noise; The single difference equation is subjected to quality control processing by utilizing the consistency between the GNSS systems to eliminate observations with pseudorange errors exceeding a threshold and observations with carrier tracking errors exceeding a threshold, thereby obtaining candidate observation satellites, wherein: The consistency between the GNSS systems refers to the same clock difference between the mobile station and the reference station receivers; Selecting a satellite from the candidate observation satellites as a reference satellite to form a double difference observation equation; Positioning is performed based on the double difference observation equation.

2. The method for improving the differential positioning performance of a GNSS navigation system according to claim 1, characterized in that: The positioning based on the double difference observation equation is specifically as follows: Combined with the motion model of the receiving end, a floating-point solution filtering equation is established and filtering is performed; Get the floating point solution filtering result and perform ambiguity integer search; Through the searched integer ambiguity, the fixed solution double difference solution equation is established and the fixed solution is solved; Obtain the fixed solution positioning result according to the fixed solution calculation result.

3. The method for improving the differential positioning performance of a GNSS navigation system according to claim 1, characterized in that: The GNSS system includes one or more of the following: the US Global Positioning System GPS, China's Beidou Satellite Navigation System BDS, Russia's Global Navigation Satellite System GLONASS, Europe's Galileo Satellite Navigation System GALILEO, India's Regional Navigation Satellite System IRNSS, and Japan's Quasi-Zenith Satellite System QZSS.

4. A device for improving the differential positioning performance of a GNSS navigation system, characterized in that: include: An acquisition module is used to acquire original observations from the GNSS system and to acquire differential observation information from a reference end, wherein the original observations and the differential observation information are subjected to the same preprocessing; the acquisition module acquires the differential observation information from the reference end by: uniformly observing the navigation signals of the GNSS system satellites through a reference station receiver and generating differential original observation information, or generating multi-system differential original observation information generated by a virtual reference station obtained through joint processing of multiple base stations, or acquiring differential correction information through a satellite-based augmentation satellite; A construction module is used to construct a single difference equation based on the original observation quantity and the differential observation information; the single difference equation is a pseudorange and carrier single difference observation equation: in, represents the single-difference pseudorange observation, represents the single-difference satellite station distance, c represents the speed of light, Δdt r represents the difference between the receiving end clock error and the reference end clock error, ε p represents the pseudorange observation noise, represents the single-difference carrier phase observation, λ represents the carrier wavelength, represents the single-difference carrier initial ambiguity, ε Φ represents the carrier phase observation noise; A quality control module is used to perform quality control processing on the single difference equation by using the consistency between the GNSS systems to eliminate the observations whose pseudorange errors exceed the threshold and the observations whose carrier tracking errors exceed the threshold, and obtain candidate observation satellites; wherein the consistency between the GNSS systems refers to the same clock difference between the mobile station and the reference station receivers. A building module, used for selecting a satellite from the candidate observation satellites as a reference satellite to build a double difference observation equation; A positioning module is used for positioning based on the double difference observation equation.

5. The device for improving the differential positioning performance of a GNSS navigation system according to claim 4, characterized in that: The positioning module comprises: Modeling and filtering unit, used to establish floating-point solution filtering equation and perform filtering processing in combination with the receiving end motion model; A search unit, used to obtain floating point solution filtering results and perform ambiguity integer search; An equation solving unit is used to establish a fixed solution double difference solving equation through the searched integer ambiguity and perform fixed solution solving; The positioning unit is used to obtain a fixed solution positioning result according to the fixed solution calculation result.

6. The device for improving the differential positioning performance of a GNSS navigation system according to claim 4, characterized in that: The GNSS system includes one or more of the following: the US Global Positioning System GPS, China's Beidou Satellite Navigation System BDS, Russia's Global Navigation Satellite System GLONASS, Europe's Galileo Satellite Navigation System GALILEO, India's Regional Navigation Satellite System IRNSS, and Japan's Quasi-Zenith Satellite System QZSS.

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