Ionized layer enhanced RTK positioning method and system based on single base station mode

Abstract

The invention provides an ionosphere enhanced RTK positioning service method based on a single base station mode, and relates to the field of RTK positioning service. In order to solve the problem that the ambiguity fixing effect is easy to occur in the traditional single-reference-station real-time positioning service when the ionosphere activity is violent, and also to consider that the unit price station service RTK equipment in the current market does not support receiving of external ionosphere data to carry out real-time ionosphere correction, the invention provides the following method: step 1, carrying out real-time ionosphere correction; and calculating the geometric distance difference between the stations to the same satellite. And 2, calculating the ionosphere difference between stations. And step 3, calculating a corrected observation value. By using the corrected observation value obtained by the invention to carry out real-time dynamic positioning, the influence of large fluctuation of ionosphere delay on a positioning result can be weakened in a solar activity violent period, and the positioning precision and ambiguity fixing effect of the RTK in a single base station mode are further improved. Meanwhile, the method only corrects the observation value of the base station, and does not need to additionally broadcast a correction number message in the transmission process.

Description

Technical Field

[0001] The present invention belongs to the field of RTK positioning services, and in particular to a single reference station mode RTK positioning service, and specifically 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 all walks of life. With the development of electronic information technology and network communication technology, GNSS data processing strategies are constantly updated. Among them, the Real-Time Kinematic (RTK) positioning technology has the characteristics of simple deployment, strong real-time performance and high positioning accuracy. It is a relatively mature real-time high-precision positioning solution. In areas with large geographical areas and sparse base stations, a single base station mode is often used to provide real-time RTK positioning services. However, this technology generally does not take into account the ionospheric differences between the base station and the mobile station during implementation. When the base station broadcasts observation value information to the mobile station, it does not process the ionospheric differences between the stations, that is, it assumes that there is no difference in the ionosphere above the base station and the mobile station. During the quiet period of the ionosphere, the centimeter-level high-precision positioning requirements can basically be met under open conditions. However, in years with high solar activity, the ionosphere is relatively active, and the ionosphere of the base station and the mobile station are quite different, which cannot be directly ignored, resulting in a serious decline in the positioning accuracy of the existing single base station RTK during the active ionosphere period. In order to improve the service capability of the single base station RTK during the active ionosphere, it is necessary to introduce an external ionosphere for correction. The existing long baseline post-calculation method is to eliminate the influence of ionospheric errors through an external ionospheric model, but the RTK user end lacks an ionospheric model reception and correction mechanism, and cannot perform real-time ionospheric acquisition and correction, and cannot be applied to real-time services. Summary of the invention

[0003] In order to solve the problems that the traditional real-time single reference station service has poor ambiguity fixing effect during the active ionosphere period, and cannot perform real-time ionospheric correction due to not supporting the reception of 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 stations, reflecting the ionospheric differences on the reference station observation values, and correcting the observation values ​​broadcast by the reference station, without changing the user-end service mode, the purpose of weakening the influence of the ionospheric differences between stations and improving the ambiguity fixing effect is achieved.

[0004] According to one aspect of the present invention, an ionospheric enhanced RTK positioning method based on a single reference station mode is provided, comprising: Calculate the difference in geometric distance between the base station and the mobile station relative to the same satellite; Calculate the inter-station ionospheric differences between the base station and the rover; Based on the calculated geometric distance differences between stations and the ionospheric differences between stations, the corrected observations are calculated.

[0005] As a further technical solution, the difference in geometric distance between the base station and the mobile station relative to the same satellite is calculated, including: Get the coordinates of the base station; The satellite's coordinates at a certain moment are calculated using the 15 orbital parameters broadcast in the broadcast ephemeris. The difference in geometric distance between the base station and the mobile station relative to the same satellite is calculated through the geometric relationship between the base station and the mobile station relative to the same satellite.

[0006] As a further technical solution, the inter-station ionospheric difference between the base station and the rover is calculated, including: Obtain the ionosphere of the base station and mobile station according to the ionosphere model; The ionosphere in the direction of the rover satellite ray is projected onto the same satellite ray direction of the base station to obtain the relative ionospheric delay at the base station and convert it into the delay that affects the satellite signal.

[0007] As a further technical solution, the method further includes: A local real-time ionospheric model is established to obtain the total electron content in the local signal transmission direction according to the positions of the mobile station and the base station.

[0008] According to one aspect of the present invention, an ionospheric enhanced RTK positioning system based on a single reference station mode is provided, comprising: A first calculation module is used to calculate the difference in geometric distance between the base station and the mobile station relative to the same satellite; The second calculation module is used to calculate the ionospheric difference between the base station and the mobile station; The third calculation module is used to calculate the corrected observation value based on the calculated geometric distance difference between stations and the ionospheric difference between stations.

[0009] According to one aspect of the present invention, there is provided a reference station configured with the ionospheric enhanced RTK positioning system based on the single reference station mode.

[0010] According to one aspect of the present invention, there is provided an ionospheric enhanced RTK positioning device based on a single reference station mode, which is applied to a reference station. The device comprises a memory and a processor, wherein 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.

[0011] According to one aspect of the present specification, a non-transitory computer-readable storage medium is provided, wherein the non-transitory computer-readable storage medium stores computer instructions, wherein the computer instructions enable the computer to execute the steps of the ionospheric enhanced RTK positioning method based on a single reference station mode.

[0012] Compared with the prior art, the present invention has the following beneficial effects: 1. The present invention proposes an ionospheric enhanced RTK positioning service method based on a 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 observation values, and correcting the observation values ​​broadcast by the reference station, the purpose of weakening the influence of the ionospheric differences between stations and improving the ambiguity fixing effect is achieved without changing the user-end service mode.

[0013] 2. Real-time dynamic positioning using the corrected observation values ​​obtained by the present invention can reduce the impact of large fluctuations in ionospheric delay on positioning results during periods of intense solar activity, and further improve the positioning accuracy and ambiguity fixing effect of single-reference station mode RTK.

[0014] 3. The method of the present invention only corrects the observation values ​​of the reference station, and there is no need to broadcast additional correction data messages during the transmission process. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, a brief introduction is given below to the drawings used in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0016] Figure 1 A schematic flow chart of an ionospheric enhanced RTK positioning method based on a single reference station mode is provided in an embodiment of the present invention.

[0017] Figure 2 A structural block diagram of an ionospheric enhanced RTK positioning system based on a single reference station mode provided in an embodiment of the present invention.

[0018] Figure 3A structural block diagram of an ionospheric enhanced RTK positioning device based on a single reference station mode provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0019] It should be noted that: The traditional real-time single base station service assumes that the ionosphere of the user and the base station is the same and does not perform ionospheric correction. During periods of active ionospheric activity, the single base station mode suffers from poor ambiguity fixation. At the same time, the real-time single base station service RTK equipment on the market does not support receiving external ionospheric data and cannot perform real-time ionospheric correction to improve positioning accuracy and fixation rate.

[0020] To this end, the present invention proposes an ionospheric enhanced RTK positioning service method based on a single base station mode, which takes into account the ionospheric differences between the base station and the mobile station, and reflects these differences in the observation values ​​of the base station. The ionospheric differences between stations are corrected by broadcasting the corrected original observation values. Without changing the user's operating mode, the ionospheric error correction is achieved, thereby improving the RTK positioning service capability of the single base station.

[0021] 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 inclusions, for example, a process, method, system, product or apparatus comprising a series of steps or units is not necessarily limited to the steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to these processes, methods, products or apparatuses.

[0022] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. In addition, the technical features in the various embodiments or single embodiments provided by the present invention are arbitrarily combined with each other to form a new technical solution. This combination is not restricted by the sequence of steps and / or the structural composition mode, but must be based on the ability of ordinary technicians in this field to achieve. When the combination of technical solutions is contradictory or cannot be achieved, it should be considered that this combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0023] The embodiment of the present invention provides an ionospheric enhanced RTK positioning method based on a single reference station mode. First, the geometric distance difference between the reference station and the mobile station relative to the same satellite is calculated; then, the ionospheric difference between the reference station and the mobile station is calculated; finally, based on the calculated geometric distance difference between the stations and the ionospheric difference between the stations, the corrected observation value is calculated. The embodiment of the present invention introduces an ionospheric model at the reference station end, interpolates the ionospheric difference between the stations, reflects the ionospheric difference on the reference station observation value, and corrects the observation value broadcast by the reference station. On the basis of not changing the user-end service mode, the purpose of weakening the influence of the ionospheric difference between the stations and improving the ambiguity fixing effect is achieved.

[0024] The reference station observation value described in the embodiment of the present invention includes two parts: pseudorange and carrier phase, both of which can interpolate ionospheric differences through ionospheric models to weaken the impact of ionospheric differences between stations.

[0025] See also Figure 1 The ionospheric enhanced RTK positioning method based on the single reference station mode provided in the embodiment of the present invention specifically includes the following steps: Step 1: Calculate the difference in geometric distances between stations to the same satellite. Before performing RTK solution, in order to ensure that the absolute position accuracy of the mobile station is high enough, a high-precision measurement method should be used to obtain the coordinates of the base station in advance. At the same time, the coordinates of the satellite at a certain moment can be calculated through the 15 orbital parameters broadcast in the broadcast ephemeris. Therefore, the difference in geometric distances between the base station and the mobile station relative to the same satellite can be calculated through the geometric relationship between the base station and the mobile station relative to the same satellite.

[0026] The process can be expressed as follows.

[0027]

[0028] Among them, the satellite position calculated by broadcast ephemeris is , the precise coordinates of the base station are , the coordinates of the mobile station are , is the geometric distance of the mobile station relative to the satellite, is the geometric distance of the base station relative to the satellite.

[0029] Step 2: Calculate the ionospheric difference between stations. After obtaining the ionospheres of the base station and the rover according to the ionosphere model, project the ionosphere in the direction of the rover satellite ray to the same satellite ray direction of the base station to obtain the relative ionospheric delay at the base station, which is then converted into the delay that affects the satellite signal.

[0030] Before this step, a local real-time ionosphere model should be established, and the total electron content in the local signal transmission direction can be obtained according to the positions of the mobile station and the base station. This process can be expressed as:

[0031] in, Represents the relative ionospheric delay in meters. represents the frequency of the original observations, represents the base station, represents a mobile station, Indicates the satellite number. Indicates the total electron content in the local signal transmission direction, referred to as the oblique total electron content. It represents the difference in the total slant electron content between the base station and the mobile station for the i-th satellite.

[0032] Step 3: Calculate the corrected observation value. Correct the difference in geometric distance and ionospheric difference to the observation value of the reference station, broadcast it to the user, and compensate the difference in ionospheric delay between stations on the observation value, thereby realizing ionospheric enhanced positioning service.

[0033] This step can be expressed as follows:

[0034] Among them, L represents the carrier phase observation value, P represents the pseudorange observation value, the superscript p represents the original observation value, and the superscript V represents the corrected observation value. Indicates the wavelength of the carrier signal.

[0035] The implementation basis of each embodiment of the present invention is to implement programmed processing through 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 reality, 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 the device is used to execute an ionospheric enhanced RTK positioning method based on a single reference station mode in the above method embodiment.

[0036] See also Figure 2 The system includes: a first calculation module for calculating the inter-station geometric distance difference between the base station and the mobile station relative to the same satellite; a second calculation module for calculating the inter-station ionospheric difference between the base station and the mobile station; and a third calculation module for calculating the corrected observation value based on the calculated inter-station geometric distance difference and inter-station ionospheric difference.

[0037] An ionospheric enhanced RTK positioning system based on a single reference station mode is provided in an embodiment of the present invention. The ionospheric enhanced RTK positioning system is designed to solve the problem that the ambiguity fixation effect of the traditional real-time single reference station service is poor during the ionosphere activity period, and the real-time ionosphere correction cannot be performed due to the failure to support the reception of external ionosphere data. Figure 2 Several modules in the system introduce an ionospheric model at the reference station end, interpolate the ionospheric differences between stations, reflect the ionospheric differences in the reference station observations, and correct the observations broadcast by the reference station. Without changing the user-end service mode, the impact of the ionospheric differences between stations is weakened and the ambiguity fixing effect is improved.

[0038] It should be noted that the system embodiment provided by the present invention is used to implement the methods in the above method embodiment as well as the methods in other method embodiments provided by the present invention. The only difference is that the corresponding functional modules are set. The principle is basically the same as the principle of the above system embodiment provided by the present invention. As long as the technical personnel in this field refer to the specific technical solutions in other method embodiments on the basis of the above system embodiment, obtain the corresponding technical means and the technical solutions composed of these technical means by combining the technical features, and on the premise of ensuring the practicality of the technical solutions, improve the modules in the above system embodiment to obtain the corresponding system class embodiments, which are used to implement the methods in other method class embodiments. For example: 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 in an embodiment of the present invention, the first calculation module is further used to execute the following instructions: Get the coordinates of the base station; The satellite's coordinates at a certain moment are calculated using the 15 orbital parameters broadcast in the broadcast ephemeris. The difference in geometric distance between the base station and the mobile station relative to the same satellite is calculated through the geometric relationship between the base station and the mobile station relative to the same satellite.

[0039] 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 in an embodiment of the present invention, the second calculation module is further used to execute the following instructions: Obtain the ionosphere of the base station and mobile station according to the ionosphere model; The ionosphere in the direction of the rover satellite ray is projected onto the same satellite ray direction of the base station to obtain the relative ionospheric delay at the base station and convert it into the delay that affects the satellite signal.

[0040] 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 in an embodiment of the present invention, the second calculation module is further used to execute the following instructions: A local real-time ionospheric model is established to obtain the total electron content in the local signal transmission direction according to the positions of the mobile station and the base station.

[0041] Based on the same inventive concept as the above-mentioned embodiment, the embodiment of the present invention further provides a reference station, which is equipped with the ionospheric enhanced RTK positioning system based on the single reference station mode. The embodiment of the present invention configures the ionospheric enhanced RTK positioning system based on the single reference station mode at the reference station end, introduces an ionospheric model, interpolates the ionospheric differences between stations, reflects the ionospheric differences on the reference station observation values, corrects the observation values ​​broadcast by the reference station, and achieves the purpose of weakening the influence of the ionospheric differences between stations and improving the ambiguity fixing effect without changing the user-end service mode.

[0042] See also Figure 3 Based on the same inventive concept as the above-mentioned embodiment, an 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. The processor calls the program instructions to execute the steps of the ionospheric enhanced RTK positioning method based on a single reference station mode.

[0043] In an 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 a volatile memory (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 an embodiment of the present invention may also be a circuit or any other device that can implement a storage function, for storing program instructions and / or data.

[0044] In the embodiments 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 device, a discrete gate or transistor logic device, or a discrete hardware component, and may implement or execute the methods, steps, and logic block diagrams disclosed in the embodiments of the present invention. A general-purpose processor may be a microprocessor or any conventional processor, etc. The steps of the method disclosed in the embodiments of the present invention may be directly embodied as being executed by a hardware processor, or may be executed by a combination of hardware and software modules in the processor.

[0045] Based on the same inventive concept as the above-mentioned embodiment, an embodiment of the present invention also provides a non-transitory computer-readable storage medium, wherein the non-transitory computer-readable storage medium stores computer instructions, and the computer instructions enable the computer to execute the steps of the ionospheric enhanced RTK positioning method based on a single reference station mode.

[0046] In summary, the present invention aims at the problem that the traditional single-reference station real-time positioning service is prone to poor ambiguity fixing effect during periods of intense ionospheric activity, and takes into account that the single-price station service RTK equipment on the market currently does 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 between stations to the same satellite. 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 dynamic positioning can weaken the impact of large fluctuations in ionospheric delay on positioning results 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, the method only corrects the observation value of the reference station, and there is no need to broadcast additional correction data messages during the transmission process.

[0047] 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 it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions 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: include: Calculate the difference in geometric distances between the base station and the mobile station relative to the same satellite, including: obtaining the coordinates of the base station; calculating the coordinates of the satellite at a certain moment through the 15 orbital parameters broadcast in the broadcast ephemeris; calculating the difference in geometric distances between the base station and the mobile station relative to the same satellite through the geometric relationship between the base station and the mobile station relative to the same satellite; Calculate the inter-station ionospheric differences between the base station and the rover; Based on the calculated geometric distance differences between stations and the ionospheric differences between stations, the corrected observations are calculated.

2. The ionospheric enhanced RTK positioning method based on a single reference station mode according to claim 1, characterized in that: Calculate the ionospheric differences between the base station and the rover, including: Obtain the ionosphere of the base station and mobile station according to the ionosphere model; The ionosphere in the direction of the rover satellite ray is projected onto the same satellite ray direction of the base station to obtain the relative ionospheric delay at the base station and convert it into the delay that affects the satellite signal.

3. The ionospheric enhanced RTK positioning method based on a single reference station mode according to claim 2, characterized in that: The method further comprises: A local real-time ionospheric model is established to obtain the total electron content in the local signal transmission direction according to the positions of the mobile station and the base station.

4. An ionospheric enhanced RTK positioning system based on a single reference station mode, characterized in that: include: The first calculation module is used to calculate the difference in geometric distances between the base station and the mobile station relative to the same satellite, including: obtaining the coordinates of the base station; calculating the coordinates of the satellite at a certain time through 15 orbital parameters broadcast in the broadcast ephemeris; and calculating the difference in geometric distances between the base station and the mobile station relative to the same satellite through the geometric relationship between the base station and the mobile station relative to the same satellite. The second calculation module is used to calculate the ionospheric difference between the base station and the mobile station; The third calculation module is used to calculate the corrected observation value based on the calculated geometric distance difference between stations and the ionospheric difference between stations.

5. A reference station, characterized in that: An ionospheric enhanced RTK positioning system based on a single reference station mode as described in claim 4 is configured.

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, and 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 described 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, which enable the computer to execute the steps of an ionospheric enhanced RTK positioning method based on a single reference station mode as described in any one of claims 1 to 3.

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