An ionospheric enhanced RTK positioning method and system based on a single reference station mode

Abstract

The present invention provides a method for ionospheric enhanced RTK positioning service based on a single reference station mode, which relates to the field of RTK positioning service. Aiming at the problem that the ambiguity fixing effect is poor in traditional single reference station real-time positioning service during periods of intense ionospheric activity, and taking into account that the current single reference station service RTK devices on the market do not support receiving external ionospheric data for real-time ionospheric correction, the following method is proposed: Step 1, calculate the geometric distance difference between stations for the same satellite. Step 2, calculate the ionospheric difference between stations. Step 3, calculate the corrected observation values. Using the corrected observation values obtained by the present invention for real-time kinematic positioning can weaken the influence of large fluctuations in ionospheric delay on the positioning result during periods of intense solar activity, and further improve the positioning accuracy and ambiguity fixing effect of the single reference station mode RTK. At the same time, this method only corrects the observation values of the reference station and does not require additional broadcast of correction messages during the transmission process.

Description

Technical Field

[0001] The present invention belongs to the field of RTK positioning services, and in particular relates to RTK positioning services in a single reference station mode, and specifically relates to an ionospheric enhanced RTK positioning method and system based on a single reference station mode. Background Art

[0002] At present, the Global Navigation Satellite System (GNSS) can provide accurate positioning, navigation, and timing services, and has been widely used in various industries. With the development of electronic information technology and network communication technology, GNSS data processing strategies have been continuously updated. Among them, the Real-Time Kinematic (RTK) positioning technology has the characteristics of simple deployment, strong real-time performance, and high positioning accuracy, and is a relatively mature real-time high-precision positioning solution. In areas with a large geographical area and sparse reference stations, a single reference station mode is often used to provide real-time RTK positioning services. However, in the implementation process of this technology, the ionospheric differences between the reference station and the rover station are generally not considered. When the reference station broadcasts the observed value information to the rover station, the ionospheric differences between the stations are not processed, that is, it is assumed that there are no differences in the ionosphere above the reference station and the rover station. During the quiet period of the ionosphere, the centimeter-level high-precision positioning requirements can basically be met under open conditions. However, in the high solar activity years, the ionosphere is relatively active, and the ionospheric differences between the reference station and the rover station are large and cannot be directly ignored, resulting in a serious decline in the positioning accuracy of the existing single reference station RTK during the active period of the ionosphere. To improve the service ability of the single reference station RTK during the active period of the ionosphere, it is necessary to introduce external ionospheric corrections. The existing long-baseline post-processing method eliminates the influence of ionospheric errors through an external ionospheric model. However, the RTK user terminal lacks an ionospheric model reception and correction mechanism, and cannot perform real-time ionospheric acquisition and correction, so it cannot be applied to real-time services. Summary of the Invention

[0003] To solve the problems of poor ambiguity fixing effect in traditional real-time single reference station services during the active period of the ionosphere and the inability to perform real-time ionospheric corrections due to the lack of support for receiving external ionospheric data, the present invention provides an ionospheric enhanced RTK positioning method and system based on a single reference station mode. By introducing an ionospheric model at the reference station end, interpolating the ionospheric differences between the stations, reflecting the ionospheric differences on the reference station observations, and correcting the observations broadcast by the reference station, the purpose of weakening the influence of the ionospheric differences between the stations and improving the ambiguity fixing effect is achieved without changing the service mode of the user terminal.

[0004] According to one aspect of the specification of the present invention, there is provided an ionospheric enhanced RTK positioning method based on a single reference station mode, including:

[0005] Calculate the difference in the geometric distance between the reference station and the rover station relative to the same satellite;

[0006] Calculate the ionospheric difference between the reference station and the rover station;

[0007] Based on the calculated difference in the geometric distance between the stations and the ionospheric difference between the stations, calculate the corrected observation value.

[0008] As a further technical solution, calculating the difference in the geometric distance between the reference station and the rover station relative to the same satellite includes:

[0009] Obtain the coordinates of the reference station;

[0010] Calculate the coordinates of the satellite at a certain moment through 15 orbital parameters broadcast in the broadcast ephemeris;

[0011] Calculate the difference in the geometric distance between the reference station and the rover station relative to the same satellite through the geometric relationship between the reference station and the rover station relative to the same satellite.

[0012] As a further technical solution, calculating the ionospheric difference between the reference station and the rover station includes:

[0013] Obtain the ionospheres of the reference station and the rover station according to the ionospheric model;

[0014] Project the ionosphere in the satellite ray direction of the rover station onto the same satellite ray direction of the reference station, obtain the relative ionospheric delay at the reference station, and convert it into the delay affecting the satellite signal.

[0015] As a further technical solution, the method further includes:

[0016] Establish a local real-time ionospheric model to obtain the total electron content in the local signal transmission direction according to the positions of the rover station and the reference station.

[0017] According to one aspect of the specification of the present invention, there is provided an ionospheric enhanced RTK positioning system based on a single reference station mode, including:

[0018] A first calculation module for calculating the difference in the geometric distance between the reference station and the rover station relative to the same satellite;

[0019] A second calculation module for calculating the ionospheric difference between the reference station and the rover station;

[0020] A third calculation module for calculating the corrected observation value based on the calculated difference in the geometric distance between the stations and the ionospheric difference between the stations.

[0021] According to one aspect of the specification of the present invention, a reference station is provided, which is configured with the ionospheric enhanced RTK positioning system based on the single reference station mode described above.

[0022] According to one aspect of the specification of the present invention, an ionospheric enhanced RTK positioning device based on the single reference station mode is provided, which is applied to a reference station. The device includes a memory and a processor. The memory stores program instructions executed by the processor, and the processor calls the program instructions to execute the steps of the ionospheric enhanced RTK positioning method based on the single reference station mode described above.

[0023] According to one aspect of the specification of the present invention, a non-transitory computer-readable storage medium is provided. The non-transitory computer-readable storage medium stores computer instructions, and the computer instructions cause the computer to execute the steps of the ionospheric enhanced RTK positioning method based on the single reference station mode described above.

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0025] 1. The present invention proposes an ionospheric enhanced RTK positioning service method based on the single reference station mode. By introducing an ionospheric model at the reference station end, interpolating the ionospheric differences between stations, reflecting the ionospheric differences on the reference station observations, correcting the observations broadcast by the reference station, and without changing the service mode of the user terminal, the purpose of weakening the influence of the ionospheric differences between stations and improving the ambiguity fixing effect is achieved.

[0026] 2. Using the corrected observations obtained by the present invention for real-time kinematic positioning can weaken the influence of the large fluctuations in ionospheric delay during intense solar activity on the positioning result, and further improve the positioning accuracy and ambiguity fixing effect of RTK in the single reference station mode.

[0027] 3. The method of the present invention only corrects the observations of the reference station and does not require additional broadcast of correction messages during the transmission process. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings used in the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0029] Figure 1 It is a schematic flow chart of an ionospheric enhanced RTK positioning method based on the single reference station mode provided by an embodiment of the present invention.

[0030] Figure 2It is a structural block diagram of an ionospheric enhanced RTK positioning system based on a single reference station mode provided by an embodiment of the present invention.

[0031] Figure 3 It is a structural block diagram of an ionospheric enhanced RTK positioning device based on a single reference station mode provided by an embodiment of the present invention. Detailed implementation manners

[0032] It should be noted that:

[0033] Traditional real-time single reference station services assume that the ionospheres of the user and the reference station are the same and do not perform ionospheric correction. During active ionospheric periods, the single reference station mode has problems with poor ambiguity fixing effects. At the same time, market real-time single reference station service RTK devices do not support receiving external ionospheric data and cannot perform real-time ionospheric correction to improve positioning accuracy and fixation rate.

[0034] For this reason, the present invention proposes an ionospheric enhanced RTK positioning service method based on a single reference station mode, which takes into account the ionospheric differences between the reference station and the rover station, and reflects this difference in the observations of the reference station. By broadcasting the corrected original observations, the correction of the inter-station ionospheric differences is realized, and the ionospheric error correction is achieved without changing the user's operation mode, thereby improving the single reference station RTK positioning service ability.

[0035] The terms "including" and "having" and any variations thereof in the specification and claims of the present invention and the above-mentioned drawings are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device that includes a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0036] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention. In addition, the technical features in each embodiment or a single embodiment provided by the present invention can be arbitrarily combined with each other to form a new technical solution. This combination is not restricted by the order of steps and / or the mode of structural composition, but must be based on the fact that those of ordinary skill in the art can implement it. When the combination of technical solutions results in contradictions or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0037] An embodiment of the present invention provides an ionospheric enhanced RTK positioning method based on a single reference station mode. First, calculate the difference in the geometric distance between the reference station and the rover with respect to the same satellite. Then, calculate the ionospheric difference between the reference station and the rover. Finally, based on the calculated difference in the geometric distance between the stations and the ionospheric difference between the stations, calculate the corrected observation value. By introducing an ionospheric model at the reference station end in the embodiment of the present invention, interpolating the ionospheric difference between the stations, reflecting the ionospheric difference onto the reference station observation value, and correcting the observation value broadcast by the reference station, the purpose of weakening the influence of the ionospheric difference between the stations and improving the ambiguity fixing effect is achieved without changing the service mode of the user terminal.

[0038] The reference station observation values in the embodiment of the present invention include two parts: pseudorange and carrier phase. Both can interpolate the ionospheric difference through the ionospheric model to weaken the influence of the ionospheric difference between the stations.

[0039] Please refer to Figure 1 , the ionospheric enhanced RTK positioning method based on a single reference station mode provided by the embodiment of the present invention specifically includes the following steps:

[0040] Step 1: Calculate the difference in the geometric distance between the stations for the same satellite. Before performing RTK solution, in order to ensure that the absolute position accuracy of the rover is high enough, the coordinates of the reference station should be obtained in advance using a high-precision measurement method. At the same time, the coordinates of the satellite at a certain moment can be calculated through 15 orbital parameters broadcast in the broadcast ephemeris. Therefore, the difference in the geometric distance between the reference station and the rover with respect to the same satellite can be calculated based on the geometric relationship between the reference station and the rover relative to the same satellite.

[0041] This process can be expressed in the following form.

[0042] (1)

[0043] Among them, the satellite position calculated from the broadcast ephemeris is , the precise coordinates of the reference station are , the coordinates of the rover are , is the geometric distance of the rover relative to the satellite, is the geometric distance of the reference station relative to the satellite.

[0044] Step 2: Calculate the ionospheric difference between the stations. After obtaining the ionospheres of the reference station and the rover according to the ionospheric model, project the ionosphere in the satellite ray direction of the rover onto the same satellite ray direction of the reference station to obtain the relative ionospheric delay at the reference station, and then convert it into the delay that affects the satellite signal.

[0045] Before performing this step, a local real-time ionospheric model should be established, and the total electron content in the local signal transmission direction can be obtained according to the positions of the rover station and the reference station. This process can be expressed as:

[0046]

[0047] Wherein, represents the relative ionospheric delay, with the unit of meter, represents the frequency of the original observation value, represents the reference station, represents the rover station, represents the satellite number, represents the total electron content in the local signal transmission direction, simply referred to as the slant total electron content, represents the difference in the slant total electron content between the reference station and the rover station for the i-th satellite.

[0048] Step 3: Calculate the corrected observation value. Correct the geometric distance difference and the ionospheric difference to the observation value of the reference station and broadcast it to the user, and compensate for the difference in the inter-station ionospheric delay on the observation value, so as to realize the ionospheric enhanced positioning service.

[0049] This step can be expressed in the following form:

[0050]

[0051] Wherein, L represents the carrier phase observation value, P represents the pseudorange observation value, the subscript p represents the original observation value, and the subscript V represents the corrected observation value, represents the wavelength of the carrier signal.

[0052] The implementation basis of each embodiment of the present invention is realized through programmed processing by a device with a processor function. Therefore, in engineering practice, the technical solutions and functions of each embodiment of the present invention are encapsulated into various modules. Based on this actual situation, on the basis of the above embodiments, an embodiment of the present invention provides an ionospheric enhanced RTK positioning system based on a single reference station mode, and this device is used to execute an ionospheric enhanced RTK positioning method based on a single reference station mode in the above method embodiment.

[0053] See Figure 2 , this system includes: a first calculation module, which is used to calculate the difference in the inter-station geometric distance between the reference station and the rover station relative to the same satellite; a second calculation module, which is used to calculate the inter-station ionospheric difference between the reference station and the rover station; a third calculation module, which is used to calculate the corrected observation value based on the calculated inter-station geometric distance difference and the inter-station ionospheric difference.

[0054] An ionospheric enhanced RTK positioning system based on a single reference station mode provided by an embodiment of the present invention aims at the problems that the ambiguity fixing effect is poor during the active ionosphere period in the traditional real-time single reference station service, and real-time ionospheric correction cannot be performed because it does not support receiving external ionospheric data. By using several modules in Figure 2 , an ionospheric model is introduced at the reference station end, the ionospheric difference between stations is interpolated, the ionospheric difference is reflected on the reference station observations, and the observations broadcast by the reference station are corrected. Without changing the service mode of the user end, the influence of the ionospheric difference between stations is weakened, and the purpose of improving the ambiguity fixing effect is achieved.

[0055] It should be noted that the system embodiment provided by the present invention is used not only to implement the method in the above method embodiment, but also to implement the methods in other method embodiments provided by the present invention. The difference is only in setting corresponding functional modules, and its principle is basically the same as that of the above system embodiment provided by the present invention. As long as those skilled in the art, on the basis of the above system embodiment, refer to the specific technical solutions in other method embodiments, obtain corresponding technical means by combining technical features, and the technical solutions composed of these technical means, and improve the modules in the above system embodiment on the premise of ensuring the practicability of the technical solutions, corresponding system-like embodiments are obtained to implement the methods in other method-like embodiments. For example:

[0056] Based on the content of the above system embodiment, as a preferred embodiment, in an ionospheric enhanced RTK positioning system based on a single reference station mode provided by an embodiment of the present invention, the first calculation module is further configured to execute the following instructions:

[0057] Obtain the coordinates of the reference station;

[0058] Calculate the coordinates of the satellite at a certain moment through 15 orbital parameters broadcast in the broadcast ephemeris;

[0059] Calculate the difference in the geometric distance between the reference station and the rover relative to the same satellite through the geometric relationship between the reference station and the rover relative to the same satellite.

[0060] Based on the content of the above system embodiment, as a preferred embodiment, in an ionospheric enhanced RTK positioning system based on a single reference station mode provided by an embodiment of the present invention, the second calculation module is further configured to execute the following instructions:

[0061] Obtain the ionospheres of the reference station and the rover according to the ionospheric model;

[0062] Project the ionosphere in the satellite ray direction of the rover to the same satellite ray direction of the reference station, obtain the relative ionospheric delay at the reference station, and convert it into the delay affecting the satellite signal.

[0063] Based on the content of the above system embodiments, as a preferred embodiment, in the embodiment of the present invention, an ionospheric enhanced RTK positioning system based on a single reference station mode is provided, and the second calculation module is further configured to execute the following instructions:

[0064] Establish a local real-time ionospheric model to obtain the total electron content of the local signal transmission direction according to the positions of the rover station and the reference station.

[0065] Based on the same inventive concept as the above embodiments, the embodiment of the present invention further provides a reference station configured with the ionospheric enhanced RTK positioning system based on a single reference station mode. In the embodiment of the present invention, the ionospheric enhanced RTK positioning system based on a single reference station mode is configured at the reference station end. By introducing an ionospheric model and interpolating the ionospheric differences between stations, the ionospheric differences are reflected on the reference station observations, and the observations broadcast by the reference station are corrected. Without changing the service mode of the user end, the purpose of weakening the influence of the ionospheric differences between stations and improving the ambiguity fixing effect is achieved.

[0066] Please refer to Figure 3 , based on the same inventive concept as the above embodiments, the embodiment of the present invention further provides an ionospheric enhanced RTK positioning device based on a single reference station mode, which is applied to a reference station. The device includes a memory and a processor. The memory stores program instructions executed by the processor, and the processor calls the program instructions to execute the steps of the ionospheric enhanced RTK positioning method based on a single reference station mode.

[0067] In the embodiment of the present invention, the memory may be a non-volatile memory, such as a hard disk drive (HDD) or a solid-state drive (SSD), etc., or may also be a volatile memory, such as a random-access memory (RAM). The memory is any other medium that can be used to carry or store the desired program code in the form of instructions or data structures and can be accessed by a computer, but is not limited thereto. The memory in the embodiment of the present invention may also be a circuit or any other device capable of implementing a storage function, for storing program instructions and / or data.

[0068] In an embodiment of the present invention, the processor may be a general-purpose processor, a digital signal processor, an application specific integrated circuit, a field programmable gate array, or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, and can implement or execute the various methods, steps, and logic block diagrams disclosed in the embodiments of the present invention. The general-purpose processor may be a microprocessor or any conventional processor, etc. The steps of the method disclosed in combination with the embodiments of the present invention can be directly embodied as being executed and completed by a hardware processor, or executed and completed by a combination of hardware and software modules in the processor.

[0069] Based on the same inventive concept as the above embodiments, the embodiments of the present invention further provide a non-transitory computer-readable storage medium, and the non-transitory computer-readable storage medium stores computer instructions, and the computer instructions cause the computer to execute the steps of the method for ionospheric enhanced RTK positioning based on a single reference station mode.

[0070] In summary of the above embodiments, the present invention aims at the problem that the ambiguity fixing effect is prone to be poor in the traditional single reference station real-time positioning service during the period of intense ionospheric activity, and also takes into account that the RTK devices of the single reference station service on the current market do not support receiving external ionospheric data for real-time ionospheric correction. The proposed method implements the following steps: Step 1: Calculate the geometric distance difference of the same satellite between stations. Step 2: Calculate the ionospheric difference between stations. Step 3: Calculate the corrected observation value. Using the corrected observation value obtained by the present invention for real-time kinematic positioning can weaken the influence of large fluctuations in ionospheric delay on the positioning result during the period of intense solar activity, and further improve the positioning accuracy and ambiguity fixing effect of the RTK in the single reference station mode. At the same time, this method only corrects the observation value of the reference station, and there is no need to broadcast correction message additionally during the transmission process.

[0071] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the technical solutions of the embodiments of the present invention.

Claims

1. An ionospheric enhanced RTK positioning method based on a single reference station mode, characterized in that, On the basis of not changing the service mode of the user terminal, weaken the influence of the inter-station ionospheric difference. The method includes: Calculate the inter-station geometric distance difference between the reference station and the rover station relative to the same satellite, including: obtaining the coordinates of the reference station; calculating the coordinates of the satellite at a certain moment through 15 orbital parameters broadcast in the broadcast ephemeris; calculating the inter-station geometric distance difference between the reference station and the rover station relative to the same satellite through the geometric relationship between the reference station and the rover station relative to the same satellite; Calculate the inter-station ionospheric difference between the reference station and the rover station; Based on the calculated inter-station geometric distance difference and inter-station ionospheric difference, calculate the corrected observation value, correct the geometric distance difference and ionospheric difference to the observation value of the reference station, broadcast it to the user, and compensate for the difference in inter-station ionospheric delay on the observation value. The observation value of the reference station includes two parts: pseudorange and carrier phase.

2. The ionospheric enhanced RTK positioning method based on a single reference station mode according to claim 1, wherein Calculate the inter-station ionospheric difference between the reference station and the rover station, including: Obtain the ionospheres of the reference station and the rover station according to the ionospheric model; Project the ionosphere in the satellite ray direction of the rover station to the same satellite ray direction of the reference station, obtain the relative ionospheric delay at the reference station, and convert it into the delay affecting the satellite signal.

3. The ionospheric enhanced RTK positioning method based on a single reference station mode according to claim 2, wherein The method further includes: Establish a local real-time ionospheric model to obtain the total electron content in the local signal transmission direction according to the positions of the rover station and the reference station.

4. An ionospheric enhanced RTK positioning system based on a single reference station mode, characterized in that, On the basis of not changing the service mode of the user terminal, weaken the influence of the inter-station ionospheric difference. The system includes: The first calculation module is used to calculate the inter-station geometric distance difference between the reference station and the rover station relative to the same satellite, including: obtaining the coordinates of the reference station; calculating the coordinates of the satellite at a certain moment through 15 orbital parameters broadcast in the broadcast ephemeris; calculating the inter-station geometric distance difference between the reference station and the rover station relative to the same satellite through the geometric relationship between the reference station and the rover station relative to the same satellite; The second calculation module is used to calculate the inter-station ionospheric difference between the reference station and the rover station; The third calculation module is used to calculate the corrected observation value based on the calculated inter-station geometric distance difference and inter-station ionospheric difference, correct the geometric distance difference and ionospheric difference to the observation value of the reference station, broadcast it to the user, and compensate for the difference in inter-station ionospheric delay on the observation value. The observation value of the reference station includes two parts: pseudorange and carrier phase.

5. A reference station, characterized in that, Configured with an ionospheric enhanced RTK positioning system based on a single reference station mode as claimed in claim 4.

6. An ionospheric enhanced RTK positioning device based on a single reference station mode, applied to a reference station, characterized in that, The device includes a memory and a processor. The memory stores program instructions executed by the processor. The processor calls the program instructions to execute the steps of an ionospheric enhanced RTK positioning method based on a single reference station mode as claimed in any one of claims 1 to 3.

7. A non-transitory computer-readable storage medium, characterized in that, The non-transitory computer-readable storage medium stores computer instructions, and the computer instructions cause the computer to execute the steps of an ionospheric enhanced RTK positioning method based on a single reference station mode as claimed in any one of claims 1 to 3.

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