A method, device and medium for obtaining ionospheric delay

Abstract

The present application discloses a method, device and medium for obtaining ionospheric delay, and relates to the field of positioning technology. It includes: selecting a target reference station in a preset area and a common-view satellite corresponding to the target reference station; obtaining the actual ionospheric delay of the common-view satellite according to the data observed by the target reference station; obtaining the fitted ionospheric delay of the common-view satellite through a polynomial coefficient fitting model; when the difference between the actual ionospheric delay and the fitted ionospheric delay meets the first preset requirement, obtaining the ionospheric delay at each grid point in the preset area according to the fitted ionospheric delay. In the method of the present application, since the common-view satellite is a satellite that can be observed by the target reference station in the preset area, and the ionospheric delay of the common-view satellite within the preset area has a strong spatiotemporal correlation, the ionospheric delay at each grid point in the preset area can be obtained more accurately according to the common-view satellite corresponding to the target reference station, thereby improving the accuracy of positioning.

Description

Technical Field

[0001] The present application relates to the field of positioning technology, and in particular to a method, device and medium for obtaining ionospheric delay. Background Art

[0002] With the development of satellite navigation and positioning technology, the accuracy of satellite navigation and positioning is getting higher and higher. For satellites, when the electromagnetic wave signal sent by the satellite passes through the atmosphere, it will produce a propagation time delay due to refraction; for each reference station, due to the different distribution and density of the ionosphere over different regions, each reference station will have an ionospheric delay when receiving data from each satellite, and the existence of ionospheric delay will reduce the accuracy of satellite positioning.

[0003] It can be seen that how to obtain ionospheric delay more accurately to improve the accuracy of satellite positioning is a technical problem that people in this field urgently need to solve. Summary of the invention

[0004] The purpose of this application is to provide a method, device and medium for obtaining ionospheric delay, which are used to more accurately obtain ionospheric delay, thereby improving the accuracy of satellite positioning.

[0005] In order to solve the above technical problems, the present application provides a method for obtaining ionospheric delay, comprising:

[0006] Select a target reference station in a preset area and a common-view satellite corresponding to the target reference station;

[0007] Acquire the actual ionospheric delay of the common-view satellite according to the data observed by the target reference station;

[0008] Obtaining the fitted ionospheric delay of the common-view satellite through a polynomial coefficient fitting model;

[0009] When the difference between the actual ionospheric delay and the fitted ionospheric delay meets a first preset requirement, the ionospheric delay at each grid point in the preset area is obtained according to the fitted ionospheric delay.

[0010] Preferably, the step of selecting a target reference station within a preset area includes:

[0011] Determine all reference stations within the preset area;

[0012] Obtaining a phase deviation product corresponding to each of the reference stations;

[0013] Using the phase deviation product to perform ambiguity fixation at the corresponding reference station;

[0014] Acquire the reference station whose positioning accuracy after fixation meets the second preset requirement;

[0015] The reference station whose positioning accuracy after fixation meets the second preset requirement is used as the target reference station in the preset area.

[0016] Preferably, selecting the common-view satellite corresponding to the target reference station includes:

[0017] Obtaining all satellites observed by the target reference station;

[0018] Acquire the altitude angle of each satellite and the duration for which each satellite is observed by the target reference station;

[0019] Acquire a target satellite from the satellites; wherein the target satellite is the satellite whose altitude angle is greater than a threshold and / or whose duration is greater than a preset duration;

[0020] Obtaining the probability that the target reference station in the same period and the same area observes each of the target satellites;

[0021] Acquire the target satellite whose probability meets a third preset requirement;

[0022] The target satellite whose probability meets the third preset requirement is used as the common-view satellite corresponding to the target reference station.

[0023] Preferably, the acquiring the fitted ionospheric delay of the common-view satellite by a polynomial coefficient fitting model comprises:

[0024] Obtaining the longitude and latitude coordinates of the center point of the preset area and the longitude and latitude coordinates of each of the target reference stations;

[0025] Establishing a fitting ionospheric delay polynomial equation according to the latitude and longitude coordinates of the center point and the latitude and longitude coordinates of the target reference station;

[0026] Solving the fitting coefficients of the fitting ionospheric delay polynomial equation by the least square method to establish the polynomial coefficient fitting model;

[0027] The fitted ionospheric delay of the common-view satellite is obtained by fitting the polynomial coefficient model.

[0028] Preferably, after acquiring the ionospheric delay at each grid point in the preset area according to the fitted ionospheric delay, the method further comprises:

[0029] Obtaining a difference between the actual ionospheric delay and the fitted ionospheric delay;

[0030] Using the difference as the ionospheric delay residual of the common-view satellite;

[0031] Obtaining the longitude and latitude coordinates of each of the grid points;

[0032] The ionospheric delay residual of each grid point is obtained according to the latitude and longitude coordinates of each grid point and by using the inverse distance weighted interpolation method.

[0033] Preferably, after obtaining the ionospheric residual of each grid point according to the latitude and longitude coordinates of each grid point by an inverse distance weighted interpolation method, the method further comprises:

[0034] Acquire the signal frequency of the common-view satellite;

[0035] The pseudorange measurement value slant path ionospheric delay and the carrier phase measurement value slant path ionospheric delay of the common-view satellite on a preset reference grid are respectively obtained according to the signal frequency, the fitted ionospheric delay and the ionospheric delay residual of the common-view satellite.

[0036] Preferably, the obtaining, according to the signal frequency, the fitted ionospheric delay, and the ionospheric delay residual of the common-view satellite, respectively a pseudorange measurement value slant path ionospheric delay and a carrier phase measurement value slant path ionospheric delay of the common-view satellite on a preset reference grid comprises:

[0037] Obtaining the latitude and longitude information of the user;

[0038] Acquire the grid point closest to the user among the grid points in the preset area according to the latitude and longitude information of the user;

[0039] The pseudorange measurement value slant path ionospheric delay and the carrier phase measurement value slant path ionospheric delay of the common-view satellite at the grid point closest to the user are respectively obtained according to the signal frequency, the fitted ionospheric delay and the ionospheric delay residual of the common-view satellite.

[0040] In order to solve the above technical problems, the present application also provides a device for obtaining ionospheric delay, comprising:

[0041] A selection module, used to select a target reference station in a preset area and a common-view satellite corresponding to the target reference station;

[0042] A first acquisition module is used to acquire the actual ionospheric delay of the common-view satellite according to the data observed by the target reference station;

[0043] A second acquisition module is used to acquire the fitted ionospheric delay of the common-view satellite through a polynomial coefficient fitting model;

[0044] A third acquisition module is used to acquire the ionospheric delay at each grid point in the preset area according to the fitted ionospheric delay when the difference between the actual ionospheric delay and the fitted ionospheric delay meets a first preset requirement.

[0045] In order to solve the above technical problems, the present application also provides a device for obtaining ionospheric delay, comprising:

[0046] Memory for storing computer programs;

[0047] A processor is used to implement the steps of the above-mentioned method for obtaining ionospheric delay when executing the computer program.

[0048] In order to solve the above technical problems, the present application also provides a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the steps of the above-mentioned method for obtaining ionospheric delay are implemented.

[0049] The method for obtaining ionospheric delay provided by the present application includes: selecting a target reference station in a preset area and a common-view satellite corresponding to the target reference station; obtaining the actual ionospheric delay of the common-view satellite according to the data observed by the target reference station; obtaining the fitted ionospheric delay of the common-view satellite through a polynomial coefficient fitting model; and obtaining the ionospheric delay at each grid point in the preset area according to the fitted ionospheric delay when the difference between the actual ionospheric delay and the fitted ionospheric delay meets the first preset requirement. In the previous method of obtaining the ionospheric delay at the grid points in the preset area according to the ionospheric delay of all satellites, since all satellites may include satellites that cannot be observed by the reference station, the ionospheric delay at the grid points in the preset area obtained is inaccurate. In the method of the present application, since the common-view satellite is a satellite that can be observed by the target reference station in the preset area, and the ionospheric delay of the common-view satellite within the preset area has a strong temporal and spatial correlation, the ionospheric delay at each grid point in the preset area can be obtained more accurately according to the common-view satellite corresponding to the target reference station, thereby improving the accuracy of positioning.

[0050] In addition, the present application also provides a device for obtaining ionospheric delay and a computer-readable storage medium, which have the same or corresponding technical features as the above-mentioned method for obtaining ionospheric delay and have the same effects as above. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] In order to more clearly illustrate the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0052] Figure 1 A flowchart of a method for obtaining ionospheric delay provided in an embodiment of the present application;

[0053] Figure 2 A structural diagram of a device for obtaining ionospheric delay provided in one embodiment of the present application;

[0054] Figure 3 A structural diagram of a device for obtaining ionospheric delay provided in another embodiment of the present application;

[0055] Figure 4 A flowchart of a method for generating a PPP-RTK slant path ionospheric grid product provided in an embodiment of the present application. DETAILED DESCRIPTION

[0056] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0057] The core of this application is to provide a method, device and medium for obtaining ionospheric delay, which are used to more accurately obtain ionospheric delay, thereby improving the accuracy of satellite positioning.

[0058] The satellite navigation and positioning system usually consists of three parts: the ground control part, the space control part and the user device. The ground control part usually consists of a master control station, a ground antenna, a monitoring station and a communication auxiliary system. The master control station is responsible for managing and coordinating the work of the entire ground control system; the ground antenna injects search messages into the satellite under the control of the master control station; the monitoring station is the data automatic collection center; and the communication auxiliary system is responsible for the transmission of load data. The space control part contains multiple satellites. The user device part is mainly composed of a receiver and an antenna. The satellite continuously sends the current satellite's location coordinate information and the timestamp when the location coordinates are sent to the ground. After the user receives the location information and the corresponding timestamp sent by multiple satellites at the same time, the distance from the satellite can be calculated, and then the user's location can be determined. However, in the positioning process, due to the refraction of the satellite signal, that is, the electromagnetic wave signal, when passing through the atmosphere, a propagation time difference, that is, ionospheric delay, will be generated. Due to the existence of ionospheric delay, the accuracy of satellite positioning will be reduced. Therefore, it is necessary to calculate the ionospheric delay correction and then provide the correction to the user. The user can correct it to the observation amount for more accurate positioning. In order to achieve more accurate positioning, it is first necessary to obtain more accurate ionospheric delay. Since the slant path ionospheric delay of the common-view satellite has a strong temporal and spatial correlation, this feature is used in this application to screen out the common-view satellites of each station in the region, and use a gridded approach to model the slant path ionospheric delay, generating a grid product that can be used by users to achieve high-precision positioning.

[0059] In order to enable those skilled in the art to better understand the present application, the present application is further described in detail below in conjunction with the accompanying drawings and specific implementation methods. Figure 1 A flowchart of a method for obtaining ionospheric delay provided in an embodiment of the present application is shown in FIG. Figure 1 As shown, the method includes:

[0060] S10: Selecting a target reference station in a preset area and a common-view satellite corresponding to the target reference station.

[0061] In the satellite navigation and positioning system, in order to communicate with the satellite, a reference station is established on the ground side. In this embodiment, a reference station is established in a preset area, and the location of the preset area, the number of reference stations in the preset area, etc. are not limited, and are determined according to actual conditions. At present, when obtaining ionospheric delay, the ionospheric delay at the grid point in the preset area is usually obtained based on the ionospheric delay of all satellites. The quality of the slant path ionospheric product is closely related to the size of the grid area location and the number and distribution of stations in the area. In areas with medium and high latitudes, dense stations and small coverage, users can be provided with high-precision ionospheric delay correction information; however, in areas with low latitudes, sparse stations and wide coverage, the ionospheric delay of the same satellite at different stations varies greatly due to the active ionosphere, large station spacing or gross errors. The method of using all reference stations to perform inverse distance weighting on all visible satellites to obtain grid residual information will destroy the spatiotemporal characteristics of ionospheric delay and affect the accuracy of ionospheric products at grid points. At the same time, due to the problem of regional span, there are differences in the satellites that can be observed by different stations. For satellites that are not in common view between different stations, when the fitting coefficient is used to weight the inverse distance of the grid product, the fitting coefficient is not accurate because there are fewer stations that can observe the satellite, resulting in poor accuracy of the generated ionospheric grid product, which affects the user's positioning results.

[0062] In order to obtain the ionospheric delay more accurately, in this embodiment, as many reference stations as possible are used and reference stations that cannot be fixed or have low positioning accuracy are eliminated, that is, reference stations with high positioning accuracy are selected as target reference stations. After the target reference station is determined, satellites are selected according to the target reference station. However, all satellites may include satellites that cannot be observed by the reference station, resulting in inaccurate ionospheric delay. Therefore, in this embodiment, the ionospheric delay is obtained by using common view satellites, that is, satellites that can be observed by the target reference station in the preset area.

[0063] S11: Obtain the actual ionospheric delay of the common-view satellite based on the data observed by the target reference station.

[0064] The target reference station and the common-view satellite corresponding to the target reference station are obtained in the above steps. In order to obtain the slant path ionospheric grid product, it is first necessary to extract the high-precision slant path ionospheric delay station by station and satellite by satellite. Since the phase observation value is less affected by multipath and the observation value accuracy is high, it can be used to extract the slant path ionospheric delay, but the extraction accuracy is limited by the ambiguity resolution accuracy. The ambiguity in the geometry-free (GF) phase combination observation value is decomposed into wide lane and narrow lane ambiguity, and formula (1) is obtained:

[0065]

[0066] In formula (1), represents the phase observation value without geometric range, subscripts 1 and 2 represent the corresponding frequency, WL and NL represent the wide lane and narrow lane combination, λ and γ represent the wavelength and ionospheric mapping factor respectively, where are the real ambiguities on frequencies 1 and 2, respectively, including the effects of receiver and satellite hardware delays. It represents the corresponding form of real number (or integer cycle) ambiguity without the influence of receiver and satellite hardware delay; b r 、b s Represent the hardware delay of the receiver and the satellite respectively; I represents the slant path ionospheric delay on frequency 1. After the PPP ambiguity of the reference station is fixed, the non-differenced integer wide lane ambiguity and non-differenced integer narrow lane ambiguity with high accuracy can be obtained, and the high-precision slant path ionospheric delay can be extracted according to formula (1).

[0067] S12: Obtain the fitted ionospheric delay of the common-view satellite through the polynomial coefficient fitting model.

[0068] Select the regional center point and establish a polynomial based on the longitude and latitude relationship between the measuring station and the regional center point. The expression of the polynomial is shown in formula (2):

[0069] I=C 00 +C 01 (lat-lat0)+C 10 (lon-lon0)+C 11 (lat-lat0)(lon-lon0) (2)

[0070] In formula (2), lon and lat are the latitude and longitude of the modeling reference station, lon0 and lat0 are the latitude and longitude of the regional center, and C 00 , C 01 , C 10 , C 11 is the model coefficient.

[0071] S13: When the difference between the actual ionospheric delay and the fitted ionospheric delay meets the first preset requirement, the ionospheric delay at each grid point in the preset area is obtained according to the fitted ionospheric delay.

[0072] The polynomial coefficient fitting model fits the ionospheric delay of each common-view satellite on the reference station to obtain the fitted ionospheric delay, and the actual ionospheric delay is subtracted from the fitted ionospheric delay. When the difference meets the first preset requirement, it means that the fitted ionospheric delay data is available, so the ionospheric delay at the grid point in the preset area can be further obtained by the inverse distance weighted interpolation method based on the fitted ionospheric delay. There is no limit on the number of grids divided into the first preset requirement and the preset area, which is determined according to the actual situation.

[0073] The method for obtaining ionospheric delay provided in this embodiment includes: selecting a target reference station in a preset area and a common-view satellite corresponding to the target reference station; obtaining the actual ionospheric delay of the common-view satellite according to the data observed by the target reference station; obtaining the fitted ionospheric delay of the common-view satellite through a polynomial coefficient fitting model; and obtaining the ionospheric delay at each grid point in the preset area according to the fitted ionospheric delay when the difference between the actual ionospheric delay and the fitted ionospheric delay meets the first preset requirement. In the previous method of obtaining the ionospheric delay at the grid point in the preset area according to the ionospheric delay of all satellites, since all satellites may include satellites that cannot be observed by the reference station, the ionospheric delay at the grid point in the preset area obtained is inaccurate. In the method of this embodiment, since the common-view satellite is a satellite that can be observed by the target reference station in the preset area, and the ionospheric delay of the common-view satellite within the preset area has a strong temporal and spatial correlation, the ionospheric delay at each grid point in the preset area can be obtained more accurately according to the common-view satellite corresponding to the target reference station, thereby improving the accuracy of positioning.

[0074] In implementation, in order to select a suitable target reference station, a preferred implementation is that selecting a target reference station in a preset area includes:

[0075] Determine all reference stations within the preset area;

[0076] Obtain the phase deviation product corresponding to each reference station;

[0077] The phase deviation product is used to fix the ambiguity at the corresponding reference station;

[0078] Acquire a reference station whose positioning accuracy after fixation meets a second preset requirement;

[0079] The reference station whose positioning accuracy after fixation meets the second preset requirement is used as the target reference station in the preset area.

[0080] The phase deviation product received in real time is used to perform multi-system precise point positioning (PPP) partial ambiguity fixation at the reference station. The reference station whose positioning accuracy after fixation meets the second preset requirement is selected as the target reference station in the preset area. There is no limitation on the second preset requirement. In this embodiment, the phase deviation product received in real time is used to perform PPP partial ambiguity fixation at the reference station. Reference stations that cannot be fixed or whose positioning accuracy after fixation is worse than 10 cm horizontally and higher than 15 cm are eliminated, and the subsequent steps are not performed.

[0081] In the method for selecting target reference stations provided in this embodiment, reference stations with low positioning accuracy are eliminated, so that more accurate ionospheric delay can be obtained subsequently.

[0082] In the above steps, the target reference station is selected. For reference stations that can be fixed normally and pass the positioning accuracy test, the common-view satellites can be selected by checking satellite by satellite. A preferred implementation is that selecting the common-view satellites corresponding to the target reference station includes:

[0083] Get all satellites observed by the target reference station;

[0084] Obtain the altitude angle of each satellite and the duration for which the target reference station observes each satellite;

[0085] Acquire a target satellite from the satellites; wherein the target satellite is a satellite whose elevation angle is greater than a threshold and / or whose duration is greater than a preset duration;

[0086] Obtain the probability of each target satellite being observed by the target reference station in the same period and area;

[0087] Acquiring a target satellite with a probability that meets a third preset requirement;

[0088] The target satellite whose probability meets the third preset requirement is used as the common-view satellite corresponding to the target reference station.

[0089] When selecting common-view satellites, first obtain the satellites observed by the target reference station. Since all observed satellites may contain invalid satellites, such as satellites with an altitude angle (altitude angle refers to the angle between the line between the observation station and the satellite and the horizontal plane) lower than the threshold and a short continuous observation time, these invalid satellites need to be eliminated. There is no limit on the value of the threshold and the preset time. In this embodiment, satellites with an altitude angle lower than 12° and a continuous observation time of less than 5 minutes are eliminated. After eliminating invalid satellites from all satellites, the common-view satellites are further determined. The common-view satellites are selected based on the probability that the target reference station in the same period and area can observe the satellite. There is no limit on the value of the third preset requirement. In screening common-view satellites, satellites that can be observed by all stations in the same period and area are screened, while considering the most used satellites and the most reference stations (for some satellites, if more than 90% of the reference stations can observe them, they are also selected).

[0090] The method for selecting common-view satellites provided in this embodiment first eliminates invalid satellites, and then selects satellites that can be observed with a probability that meets the requirements from the invalid satellites as common-view satellites, so that the ionospheric delay can be obtained more accurately.

[0091] When obtaining the fitted ionospheric delay of the common-view satellite through the polynomial coefficient fitting model, the following steps are specifically included:

[0092] Obtain the latitude and longitude coordinates of the center point of the preset area and the latitude and longitude coordinates of each target reference station;

[0093] A fitting ionospheric delay polynomial equation is established according to the latitude and longitude coordinates of the center point and the latitude and longitude coordinates of the target reference station;

[0094] The fitting coefficients of the ionospheric delay polynomial equation are solved by the least square method to establish a polynomial coefficient fitting model;

[0095] The fitted ionospheric delay of the common-view satellite is obtained by fitting the model with polynomial coefficients.

[0096] First, the product accuracy of each satellite at each grid point is confirmed by the satellite ambiguity fixation when the PPP ambiguity is fixed in the above embodiment, and then the polynomial coefficients of the ionospheric delay are fitted satellite by satellite using the regional reference station according to the weight, and it is iterated until the conditions are met.

[0097] Among them, the polynomial coefficients are fitted according to formula (3), formula (4) and formula (5):

[0098] δI ai =C 00 (3)

[0099] δI ai=C 00 +C 01 (φ-φ0)+C 10 (λ-λ0) (4)

[0100] δI ai =C 00 +C 01 (φ-φ0)+C 10 (λ-λ0)+C 11 (φ-φ0)(λ-λ0) (5)

[0101] Formula (3), Formula (4) and Formula (5) are ionospheric polynomial fitting equation types, which are selected according to the number of effective reference stations. At present, Formula (5) is used as the polynomial fitting equation; when the number of reference stations is small and the area is small, such as a small area specially divided for the service level of a certain place, Formula (4) can be used as the polynomial fitting equation; Formula (3) is used when fitting at this station and is only used when testing a single station. Among them, δI ai is the ionospheric delay error at the reference station; C 00 , C 01 , C 10 , C 11 is the polynomial fitting coefficient; φ and λ are the latitude and longitude of the current reference station; φ0 and λ0 are the latitude and longitude of the center point in the region. The polynomial fitting coefficient can be solved by the least squares method, and the ionospheric delay of each common-view satellite of the reference station can be fitted by the polynomial coefficient fitting model.

[0102] In implementation, in order to obtain the accuracy of the grid points, a preferred implementation manner is that after obtaining the ionospheric delay at each grid point in the preset area according to the fitted ionospheric delay, the method for obtaining the ionospheric delay further includes:

[0103] Get the difference between the actual ionospheric delay and the fitted ionospheric delay;

[0104] The difference is taken as the ionospheric delay residual of the common-view satellite;

[0105] Get the longitude and latitude coordinates of each grid point;

[0106] The ionospheric delay residual of each grid point is obtained according to the latitude and longitude coordinates of each grid point through the inverse distance weighted interpolation method.

[0107] The ionospheric delay of each common-view satellite at the reference station is subtracted from the extracted ionospheric delay of each common-view satellite from the ionospheric delay of each common-view satellite fitted by the polynomial equation to obtain the ionospheric residual of each common-view satellite at the reference station. The grid point position can be obtained according to the regional grid point number, and the ionospheric residual of each grid point can be obtained by the inverse distance weighted interpolation method.

[0108] This embodiment provides that after the ionospheric delay at the grid point is obtained, the residual of each grid point is obtained, so that the user can understand the accuracy of the grid point.

[0109] In order to obtain the ionospheric delay product, a preferred implementation manner is that after obtaining the ionospheric residual of each grid point according to the latitude and longitude coordinates of each grid point by an inverse distance weighted interpolation method, the method for obtaining the ionospheric delay also includes:

[0110] Obtain the signal frequency of the common-view satellite;

[0111] According to the signal frequency, the fitted ionospheric delay and the ionospheric delay residual of the common-view satellite, the pseudo-range measurement value slant-path ionospheric delay and the carrier phase measurement value slant-path ionospheric delay of the common-view satellite on the preset reference grid are obtained respectively.

[0112] The slant path ionospheric delay of the pseudorange measurement value of satellite i on reference grid k can be calculated by formula (6), and the slant path ionospheric delay of the carrier phase measurement value is It can be calculated by formula (7):

[0113]

[0114]

[0115] In formula (6) and formula (7), f represents the frequency of the satellite signal; represents the slant path ionospheric delay of the pseudorange measurement value of satellite i at time t, in meters; is the slant path ionospheric delay of the carrier phase measurement of satellite i at time t, in meters; is the slant path ionospheric delay of satellite i calculated by the polynomial equation, in TECU; The slant path ionospheric delay residual of satellite i obtained by grid interpolation, in units of TECU; when there is no grid ionospheric residual information, it can be set to 0; when there is grid ionospheric residual information, it can be calculated using formula (8):

[0116]

[0117] In formula (8), w k is the weight of the grid involved in the interpolation calculation; is the slant path ionospheric delay residual of satellite i on grid k, in TECU; N is the number of grids, which can be 3 or 4.

[0118] In the method of this embodiment, a grid point ionospheric delay product is generated according to the signal frequency, the fitted ionospheric delay, and the ionospheric delay residual of the common-view satellite, so that the user can use the grid product to assist in positioning.

[0119] In implementation, in order to facilitate user positioning, a preferred implementation is that, according to the signal frequency, the fitted ionospheric delay, and the ionospheric delay residual of the common-view satellite, the pseudo-range measurement value slant path ionospheric delay and the carrier phase measurement value slant path ionospheric delay of the common-view satellite on the preset reference grid are respectively obtained, and the slant path ionospheric delay includes:

[0120] Get the user's latitude and longitude information;

[0121] Obtain the grid point closest to the user among the grid points in the preset area according to the user's latitude and longitude information;

[0122] According to the signal frequency, the fitted ionospheric delay and the ionospheric delay residual of the common-view satellite, the pseudo-range measurement value slant-path ionospheric delay and the carrier phase measurement value slant-path ionospheric delay of the common-view satellite at the grid point closest to the user are obtained respectively.

[0123] The method provided in this embodiment allows the user to obtain the slant path ionospheric delay of the reference station where he is located based on the grid point closest to him, thereby facilitating positioning.

[0124] In the above embodiments, the method for obtaining ionospheric delay is described in detail, and the present application also provides an embodiment corresponding to the device for obtaining ionospheric delay. It should be noted that the present application describes the embodiments of the device part from two perspectives, one is based on the perspective of functional modules, and the other is based on the perspective of hardware.

[0125] Figure 2 A structural diagram of an apparatus for obtaining ionospheric delay provided in an embodiment of the present application. This embodiment, based on the perspective of functional modules, includes:

[0126] A selection module 10 is used to select a target reference station in a preset area and a common-view satellite corresponding to the target reference station;

[0127] A first acquisition module 11 is used to acquire the actual ionospheric delay of the common-view satellite according to the data observed by the target reference station;

[0128] A second acquisition module 12 is used to acquire the fitted ionospheric delay of the common-view satellite through a polynomial coefficient fitting model;

[0129] The third acquisition module 13 is used to acquire the ionospheric delay at each grid point in the preset area according to the fitted ionospheric delay when the difference between the actual ionospheric delay and the fitted ionospheric delay meets the first preset requirement.

[0130] Since the embodiments of the apparatus part correspond to the embodiments of the method part, please refer to the description of the embodiments of the method part for the embodiments of the apparatus part, which will not be repeated here.

[0131] In the device for obtaining ionospheric delay provided by the present embodiment, a target reference station in a preset area and a common-view satellite corresponding to the target reference station are selected by a selection module; the actual ionospheric delay of the common-view satellite is obtained according to the data observed by the target reference station by a first acquisition module; the fitted ionospheric delay of the common-view satellite is obtained by a second acquisition module through a polynomial coefficient fitting model; and the ionospheric delay at each grid point in the preset area is obtained according to the fitted ionospheric delay by a third acquisition module when the difference between the actual ionospheric delay and the fitted ionospheric delay meets a first preset requirement. In the previous device for obtaining the ionospheric delay at the grid points in the preset area based on the ionospheric delay of all satellites, since all satellites may include satellites that cannot be observed by the reference station, the ionospheric delay at the grid points in the preset area is inaccurate. In the device of this embodiment, since the common-view satellites are satellites that can be observed by the target reference station in the preset area, and the ionospheric delays of the common-view satellites in the preset area have strong spatiotemporal correlation, the ionospheric delays at each grid point in the preset area can be obtained more accurately according to the common-view satellites corresponding to the target reference station, thereby improving the accuracy of positioning.

[0132] Figure 3 This is a structural diagram of a device for obtaining ionospheric delay provided by another embodiment of the present application. This embodiment is based on the hardware perspective, such as Figure 3 As shown, the device for obtaining ionospheric delay includes:

[0133] A memory 20, used for storing computer programs;

[0134] The processor 21 is used to implement the steps of the method for obtaining ionospheric delay mentioned in the above embodiment when executing the computer program.

[0135] The device for obtaining ionospheric delay provided in this embodiment may include but is not limited to a smart phone, a tablet computer, a laptop computer or a desktop computer.

[0136] Among them, the processor 21 may include one or more processing cores, such as a 4-core processor, an 8-core processor, etc. The processor 21 can be implemented in at least one hardware form of a digital signal processor (DSP), a field-programmable gate array (FPGA), and a programmable logic array (PLA). The processor 21 may also include a main processor and a coprocessor. The main processor is a processor for processing data in the awake state, also known as a central processing unit (CPU); the coprocessor is a low-power processor for processing data in the standby state. In some embodiments, the processor 21 may be integrated with a graphics processing unit (GPU), which is responsible for rendering and drawing the content to be displayed on the display screen. In some embodiments, the processor 21 may also include an artificial intelligence (AI) processor, which is used to process computing operations related to machine learning.

[0137] The memory 20 may include one or more computer-readable storage media, which may be non-transitory. The memory 20 may also include a high-speed random access memory, and a non-volatile memory, such as one or more disk storage devices, flash memory storage devices. In this embodiment, the memory 20 is at least used to store the following computer program 201, wherein, after the computer program is loaded and executed by the processor 21, it can implement the relevant steps of the method for obtaining ionospheric delay disclosed in any of the aforementioned embodiments. In addition, the resources stored in the memory 20 may also include an operating system 202 and data 203, etc., and the storage method may be temporary storage or permanent storage. Among them, the operating system 202 may include Windows, Unix, Linux, etc. The data 203 may include but is not limited to the data involved in the above-mentioned method for obtaining ionospheric delay, etc.

[0138] In some embodiments, the device for acquiring ionospheric delay may further include a display screen 22 , an input / output interface 23 , a communication interface 24 , a power supply 25 , and a communication bus 26 .

[0139] Those skilled in the art will understand that Figure 3 The structure shown in the figure does not constitute a limitation on the device for obtaining ionospheric delay, and may include more or fewer components than those shown in the figure.

[0140] The device for obtaining ionospheric delay provided in an embodiment of the present application includes a memory and a processor. When the processor executes the program stored in the memory, it can implement the following method: a method for obtaining ionospheric delay, with the same effect as above.

[0141] Finally, the present application also provides an embodiment corresponding to a computer-readable storage medium. The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the steps recorded in the above method embodiment are implemented.

[0142] It is understandable that if the method in the above embodiment is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application is essentially or the part that contributes to the prior art or all or part of the technical solution can be embodied in the form of a software product, and the computer software product is stored in a storage medium to execute all or part of the steps of the method described in each embodiment of the present application. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM), random access memory (RAM), disk or optical disk and other media that can store program code.

[0143] The computer-readable storage medium provided in the present application includes the above-mentioned method for obtaining ionospheric delay, and the effect is the same as above.

[0144] In order to make the technical personnel in this field better understand the present application scheme, the following is combined with the attached Figure 4 The present application is further described in detail with specific implementation methods. Figure 4 A flow chart of a PPP-RTK oblique path ionospheric grid product generation method provided in an embodiment of the present application. The key technology of high-precision fusion of Precise Point Positioning-Real-Time Kinematic (PPP-RTK) involves multiple aspects of satellite navigation and positioning technology, including real-time phase fractional deviation estimation, extraction and grid modeling of regional atmospheric enhancement correction numbers based on ground-based reference networks, and PPP fast ambiguity fixation. Among them, the regional enhancement correction numbers include ionosphere, troposphere generation methods and grid modeling research. PPP-RTK fast and precise positioning requires the enhancement of atmospheric delay information. Therefore, it is necessary to use the existing reference network to study the error characteristics of regional atmospheric correction numbers and grid modeling methods, and realize the extraction and modeling of regional atmospheric enhancement correction numbers. Users can obtain the atmospheric correction numbers of the corresponding area through their own location, and realize fast ambiguity fixation with the assistance of atmospheric products, and obtain centimeter-level positioning results in a short time. Such as Figure 4As shown, the method includes:

[0145] S14: Obtain regional reference station data stream, actual orbit, clock error, and UPD products;

[0146] S15: ionospheric delay extraction;

[0147] S16: Grid product generation;

[0148] S17: Obtain ionospheric grid products with high accuracy, high reliability and high continuity.

[0149] The ionospheric delay extraction in step S15 specifically includes the following steps:

[0150] S151: Regional reference station PPP ambiguity fix;

[0151] S152: Detection and elimination of phase difference satellites;

[0152] S153: Extract the slant path ionospheric delay estimation and determine the accuracy information station by station according to the principle of the maximum number of all measuring stations and the maximum number of commonly-viewed satellites.

[0153] The grid product generation in step S16 specifically includes the following steps:

[0154] S161: Fitting the ionospheric delay polynomial coefficients of each common-view satellite;

[0155] S162: Quality control (post-test residual inspection, etc.);

[0156] S163: Obtain the ionospheric delay product, residual value, and accuracy information of the grid point based on the principle of proximity.

[0157] In the method of this embodiment, PPP positioning with fixed ambiguity is performed on the reference stations in the area, the ionospheric delay of each satellite is extracted, and a polynomial model is fitted to obtain the slant path ionospheric product at each grid point; based on the number of common-view satellites and the number of stations of the stations in the area, satellites are selected in a scheme that utilizes the most stations and the most common-view satellites as much as possible, and the ionospheric grid products of these satellites are generated by utilizing the characteristic that the slant path ionospheric delays of satellites that can be common-viewed within a certain area have strong spatiotemporal correlation; while obtaining the ionospheric grid product, a residual value of each grid point is also generated to represent the accuracy of the grid point product, and the user can flexibly use the grid product more accurately according to the accuracy information to assist in positioning.

[0158] The above is a detailed introduction to a method, device and medium for obtaining ionospheric delay provided by the present application. The various embodiments in the specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same and similar parts between the embodiments can refer to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can refer to the method part description. It should be pointed out that for ordinary technicians in this technical field, without departing from the principles of the present application, several improvements and modifications can be made to the present application, and these improvements and modifications also fall within the scope of protection of the claims of the present application.

[0159] It should also be noted that, in this specification, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "comprise", "include" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the statement "comprises a ..." does not exclude the presence of other identical elements in the process, method, article or device including the element.

Claims

1. A method for obtaining ionospheric delay, It is characterized in that include: Select a target reference station in a preset area and a common-view satellite corresponding to the target reference station; Acquire the actual ionospheric delay of the common-view satellite according to the data observed by the target reference station; Obtaining the fitted ionospheric delay of the common-view satellite through a polynomial coefficient fitting model; When the difference between the actual ionospheric delay and the fitted ionospheric delay meets a first preset requirement, acquiring the ionospheric delay at each grid point in the preset area according to the fitted ionospheric delay; The step of acquiring the actual ionospheric delay of the common-view satellite according to the data observed by the target reference station comprises: Acquire the actual ionospheric delay of the common-view satellite according to the geometry-free range phase observation value observed by the target reference station; The obtaining the fitted ionospheric delay of the common-view satellite by fitting the model with polynomial coefficients comprises: Select the regional center point, establish a polynomial based on the longitude and latitude relationship between the measuring station and the regional center point, and obtain the fitted ionospheric delay based on the fitted ionospheric delay of each common-view satellite at the reference station; The acquiring the ionospheric delay at each grid point in the preset area according to the fitted ionospheric delay comprises: The ionospheric delay at the grid point in the preset area is obtained by using the inverse distance weighted interpolation method according to the fitted ionospheric delay; The calculation of the geometric range-free phase observation value is shown in formula (1): ；（1） In formula (1), It represents the phase observation value without geometric distance, and the subscripts 1 and 2 represent the corresponding frequency. Indicates a combination of wide lanes and narrow lanes; , are wavelength and ionospheric mapping factor respectively, where ; , are the real ambiguities on frequencies 1 and 2, respectively, including the effects of receiver and satellite hardware delays. , , , It represents the real number (or integer cycle) ambiguity of the corresponding form without the influence of the hardware delay of the receiver and the satellite end; , Respectively represent the hardware delay of the receiver and satellite end; represents the slant path ionospheric delay on frequency 1; The expression of the polynomial established based on the longitude and latitude relationship between the measuring station and the regional center point is shown in formula (2): ；（2） In formula (2), , are the latitude and longitude of the modeling reference station, , are the latitude and longitude of the center point of the region, , , , is the model coefficient.

2. The method for obtaining ionospheric delay according to claim 1, It is characterized in that The step of selecting a target reference station within a preset area includes: Determine all reference stations within the preset area; Obtaining a phase deviation product corresponding to each of the reference stations; Using the phase deviation product to perform ambiguity fixation at the corresponding reference station; Acquire the reference station whose positioning accuracy after fixation meets the second preset requirement; The reference station whose positioning accuracy after fixation meets the second preset requirement is used as the target reference station in the preset area.

3. The method for obtaining ionospheric delay according to claim 1 or 2, It is characterized in that Selecting the common-view satellite corresponding to the target reference station includes: Obtaining all satellites observed by the target reference station; Acquire the altitude angle of each satellite and the duration for which each satellite is observed by the target reference station; Acquire a target satellite from the satellites; wherein the target satellite is the satellite whose altitude angle is greater than a threshold and / or whose duration is greater than a preset duration; Obtaining the probability that the target reference station in the same period and the same area observes each of the target satellites; Acquire the target satellite whose probability meets a third preset requirement; The target satellite whose probability meets the third preset requirement is used as the common-view satellite corresponding to the target reference station.

4. The method for obtaining ionospheric delay according to claim 3, It is characterized in that The obtaining the fitted ionospheric delay of the common-view satellite by using a polynomial coefficient fitting model comprises: Obtaining the longitude and latitude coordinates of the center point of the preset area and the longitude and latitude coordinates of each of the target reference stations; Establishing a fitting ionospheric delay polynomial equation according to the latitude and longitude coordinates of the center point and the latitude and longitude coordinates of the target reference station; Solving the fitting coefficients of the fitting ionospheric delay polynomial equation by the least square method to establish the polynomial coefficient fitting model; The fitted ionospheric delay of the common-view satellite is obtained by fitting the polynomial coefficient model.

5. The method for obtaining ionospheric delay according to claim 4, It is characterized in that After acquiring the ionospheric delay at each grid point in the preset area according to the fitted ionospheric delay, the method further includes: Obtaining a difference between the actual ionospheric delay and the fitted ionospheric delay; Using the difference as the ionospheric delay residual of the common-view satellite; Obtaining the longitude and latitude coordinates of each of the grid points; The ionospheric delay residual of each grid point is obtained according to the latitude and longitude coordinates of each grid point and by using the inverse distance weighted interpolation method.

6. The method for obtaining ionospheric delay according to claim 5, It is characterized in that After obtaining the ionospheric residual of each grid point according to the latitude and longitude coordinates of each grid point by an inverse distance weighted interpolation method, the method further includes: Acquire the signal frequency of the common-view satellite; The pseudorange measurement value slant path ionospheric delay and the carrier phase measurement value slant path ionospheric delay of the common-view satellite on a preset reference grid are respectively obtained according to the signal frequency, the fitted ionospheric delay and the ionospheric delay residual of the common-view satellite.

7. The method for obtaining ionospheric delay according to claim 6, It is characterized in that The step of respectively obtaining the pseudorange measurement value slant path ionospheric delay and the carrier phase measurement value slant path ionospheric delay of the common view satellite on a preset reference grid according to the signal frequency, the fitted ionospheric delay, and the ionospheric delay residual of the common view satellite comprises: Get the user's latitude and longitude information; Acquire the grid point closest to the user among the grid points in the preset area according to the latitude and longitude information of the user; The pseudorange measurement value slant path ionospheric delay and the carrier phase measurement value slant path ionospheric delay of the common-view satellite at the grid point closest to the user are respectively obtained according to the signal frequency, the fitted ionospheric delay and the ionospheric delay residual of the common-view satellite.

8. A device for obtaining ionospheric delay, It is characterized in that include: A selection module, used to select a target reference station in a preset area and a common-view satellite corresponding to the target reference station; A first acquisition module is used to acquire the actual ionospheric delay of the common-view satellite according to the data observed by the target reference station; A second acquisition module is used to acquire the fitted ionospheric delay of the common-view satellite through a polynomial coefficient fitting model; A third acquisition module is used to acquire the ionospheric delay at each grid point in the preset area according to the fitted ionospheric delay when the difference between the actual ionospheric delay and the fitted ionospheric delay meets a first preset requirement; The first acquisition module is specifically used for: Acquire the actual ionospheric delay of the common-view satellite according to the geometry-free range phase observation value observed by the target reference station; The second acquisition module is specifically used for: Select the regional center point, establish a polynomial based on the longitude and latitude relationship between the measuring station and the regional center point, and obtain the fitted ionospheric delay based on the fitted ionospheric delay of each common-view satellite at the reference station; The acquiring the ionospheric delay at each grid point in the preset area according to the fitted ionospheric delay comprises: The ionospheric delay at the grid point in the preset area is obtained by using the inverse distance weighted interpolation method according to the fitted ionospheric delay; The calculation of the geometric range-free phase observation value is shown in formula (1): ；（1） In formula (1), It represents the phase observation value without geometric distance, and the subscripts 1 and 2 represent the corresponding frequency. Indicates a combination of wide lanes and narrow lanes; , are wavelength and ionospheric mapping factor respectively, where ; , are the real ambiguities on frequencies 1 and 2, respectively, including the effects of receiver and satellite hardware delays. , , , It represents the real number (or integer cycle) ambiguity of the corresponding form without the influence of the hardware delay of the receiver and the satellite end; , Respectively represent the hardware delay of the receiver and satellite end; represents the slant path ionospheric delay on frequency 1; The expression of the polynomial established based on the longitude and latitude relationship between the measuring station and the regional center point is shown in formula (2): ；（2） In formula (2), , are the latitude and longitude of the modeling reference station, , are the latitude and longitude of the center point of the region, , , , is the model coefficient.

9. A device for obtaining ionospheric delay, It is characterized in that include: Memory for storing computer programs; A processor, configured to implement the steps of the method for obtaining ionospheric delay as claimed in any one of claims 1 to 7 when executing the computer program.

10. A computer-readable storage medium, It is characterized in that The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the steps of the method for obtaining ionospheric delay according to any one of claims 1 to 7 are implemented.

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