CN116203598A - Ionosphere modeling method, device and medium based on foundation and star-based enhanced fusion - Google Patents

Ionosphere modeling method, device and medium based on foundation and star-based enhanced fusion Download PDF

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CN116203598A
CN116203598A CN202310184489.1A CN202310184489A CN116203598A CN 116203598 A CN116203598 A CN 116203598A CN 202310184489 A CN202310184489 A CN 202310184489A CN 116203598 A CN116203598 A CN 116203598A
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satellite
ionosphere
station
delay
star
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杨克凡
张晋升
蒋可
潘国富
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Guangzhou Hi Target Surveying Instrument Co ltd
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S19/00—Satellite radio beacon positioning systems; Determining position, velocity or attitude using signals transmitted by such systems
    • G01S19/01—Satellite radio beacon positioning systems transmitting time-stamped messages, e.g. GPS [Global Positioning System], GLONASS [Global Orbiting Navigation Satellite System] or GALILEO
    • G01S19/13—Receivers
    • G01S19/35—Constructional details or hardware or software details of the signal processing chain
    • G01S19/37—Hardware or software details of the signal processing chain
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S19/00—Satellite radio beacon positioning systems; Determining position, velocity or attitude using signals transmitted by such systems
    • G01S19/01—Satellite radio beacon positioning systems transmitting time-stamped messages, e.g. GPS [Global Positioning System], GLONASS [Global Orbiting Navigation Satellite System] or GALILEO
    • G01S19/03—Cooperating elements; Interaction or communication between different cooperating elements or between cooperating elements and receivers
    • G01S19/07—Cooperating elements; Interaction or communication between different cooperating elements or between cooperating elements and receivers providing data for correcting measured positioning data, e.g. DGPS [differential GPS] or ionosphere corrections
    • G01S19/072—Ionosphere corrections
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
    • Y02A90/00—Technologies having an indirect contribution to adaptation to climate change
    • Y02A90/10—Information and communication technologies [ICT] supporting adaptation to climate change, e.g. for weather forecasting or climate simulation

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Abstract

The invention discloses an ionosphere modeling method, device and medium based on foundation and star-based enhanced fusion, wherein the method comprises the following steps: acquiring reference station coordinates, real-time observation data of a reference station, and satellite precise ephemeris, precise clock correction, DCB and UPD products; extracting ionospheric delay of a single-station observation satellite; subtracting the ionospheric delay of all satellites of the same station from the ionospheric delay of a reference satellite, performing reference satellite conversion, and simultaneously performing reference satellite conversion on all baseline solutions in the NRTK modeling area; and constructing an ionosphere model based on fusion of foundation enhancement and star-base enhancement by using a polynomial error compensation algorithm. According to the invention, the advantage that PPP single-station operation is not limited by the distance of the reference station is combined, high-precision ionosphere delay information is extracted for ionosphere modeling of NRTK, so that not only is the precision of NRTK ionosphere modeling improved, but also the service range of NRTK is enlarged, and the reference station sparse region can acquire high-precision positioning service, thereby reducing the construction cost of NRTK in a wide area.

Description

Ionosphere modeling method, device and medium based on foundation and star-based enhanced fusion
Technical Field
The invention relates to the technical field of satellite navigation, in particular to an ionosphere modeling method, device and medium based on foundation and satellite-based enhanced fusion.
Background
The Network RTK (NRTK) technology estimates an error model of a region through a Network composed of a plurality of reference stations, and provides correction data of a reference grid close to the user with data of a virtual reference station. The network is utilized to transmit data, thereby breaking through the limitation of distance and enabling the user terminals in the area to obtain the high-precision positioning result in real time.
The virtual reference station (Virtual Reference Station, VRS) technology is the most mature and most widely used NRTK technology at present, and the solution flow of the VRS technology is approximately: the calculation center carries out reference station network ambiguity fixing and baseline error calculation according to known coordinates of each reference station, satellite ephemeris, real-time observation data and the like; meanwhile, the rough coordinates of the user station are received, a virtual reference station is generated at the coordinates, the accurate known coordinates of the reference station and real-time observation data of the reference station are utilized to model troposphere delay and ionosphere delay of the position of the virtual reference station, so that a virtual observation value of the virtual reference station is constructed, and finally the virtual observation value or correction number is encoded into an RTCM differential message to be sent to a user for RTK positioning.
The core technology of NRTK is that a triangular network is constructed through a continuously running reference station, each triangular network is independently operated, namely three baseline double-difference ambiguities are calculated firstly, so that baseline double-difference ionosphere and troposphere atmosphere delay information is obtained, then an atmosphere error model is constructed, when a user logs in, a corresponding triangular network is selected according to the outline position of the user, then the ionosphere and the troposphere atmosphere correction number at the position are interpolated by using the atmosphere error linear interpolation parameters of the triangular network, and a virtual observation value is constructed, and further RTK service is provided. The main defects are:
firstly, the distance between NRTK reference stations is often more than 50km, and even reaches more than 200km in partial wide areas, in the ambiguity fixing process, because the base line is longer, the delay errors of an ionosphere and a troposphere are not completely eliminated by double difference operation, the fixed interference of the residual error on the double difference ambiguity is very large, the fixed interference can be fixed only after a long time, even the situation that the fixed interference can not occur, the error correction precision of a virtual reference station is seriously affected, and the service precision of the NRTK is further affected.
Second, when the outline position provided by the user is not in the triangle network, deviation can occur to the ionosphere atmospheric error correction interpolated by the linear interpolation model, thereby reducing the accuracy of the virtual observation value and affecting the positioning accuracy of the user.
Third, constructing foundation enhancement system under wide area condition, using conventional station construction scheme, requires large number of construction reference stations, and greatly increases construction cost and maintenance cost.
In view of this, improvements to existing ionosphere modeling methods are needed to improve positioning accuracy and reduce construction and maintenance costs.
Disclosure of Invention
Aiming at the defects, the invention aims to provide an ionosphere modeling method, device and medium based on foundation and star-based enhanced fusion, so as to solve the problems of lower positioning precision and higher construction cost and maintenance cost in the prior art.
Therefore, the ionosphere modeling method based on the fusion of foundation enhancement and star-based enhancement provided by the invention comprises the following steps:
acquiring data, including reference station coordinates, reference station real-time observation data, satellite precise ephemeris, precise clock error, DCB products and UPD products;
acquiring ionospheric delay of a single-station observation satellite by using the data;
subtracting the ionospheric delay of all satellites of the same station from the ionospheric delay of a reference satellite, performing reference satellite conversion, and simultaneously performing reference satellite conversion on all baseline solutions in the NRTK modeling area;
constructing an ionosphere model based on fusion of foundation enhancement and star-based enhancement by using polynomial error compensation, wherein the ionosphere model comprises the following components:
Figure BDA0004103311580000021
Figure BDA0004103311580000031
wherein: />
Figure BDA0004103311580000032
Ionospheric delay on the inclined path for the observation satellite s of station i, +.>
Figure BDA0004103311580000033
Coefficients of polynomial model, +.>
Figure BDA0004103311580000034
Geographic latitude and longitude at the puncture point for satellite s; phi (phi) 0 、λ 0 Modeling the geographical latitude and longitude of the regional center point for the NRTK ionosphere; ΔSTEC s And compensating the error of the grid point ionosphere residual error.
In the above method, preferably, the specific step of obtaining the ionospheric delay of the single-station observation satellite is as follows:
calculating a ambiguity floating solution by using an ionosphere-free PPP algorithm according to the reference station coordinates;
using UPD product, using inter-satellite single difference algorithm to fix ambiguity, obtaining inter-satellite single difference ambiguity fixing solution delta N 1 ,N 2 ；
Converting the geometric phase-free combination formula into an inter-satellite single difference form;
Figure BDA0004103311580000035
Figure BDA0004103311580000036
obtaining the inclined ionosphere delay of the corresponding satellite through the calculation of the following formula;
Figure BDA0004103311580000037
wherein: DCB (DCB) s Produced by DCBThe product is corrected and is added with->
Figure BDA0004103311580000038
Ionosphere delay floating solution for reference star.
In the above method, preferably, the ionospheric delay is extracted using the following geometric phase-free combination
Figure BDA0004103311580000039
Figure BDA00041033115800000310
Figure BDA00041033115800000311
Wherein: l (L) 1 、L 2 Respectively carrier wave f 1 And f 2 Phase observance of>
Figure BDA00041033115800000312
Figure BDA00041033115800000313
For ionospheric delay of corresponding frequency points, DCB r For receiver-side hardware delay, DCB s Lambda is the hardware delay of the satellite s end 1 、λ 2 For the wavelength of the corresponding frequency point, N 1 、N 2 Epsilon as the ambiguity of the corresponding frequency point L1 、ε L2 Is the observed noise of the corresponding frequency point phase observed quantity.
In the above method, preferably, the specific steps of converting the reference star are as follows:
setting a cut-off height angle to be 40 degrees, selecting all first group of public satellites for baseline fixed solutions in an NRTK modeling area, and simultaneously selecting a second group of public satellites of all reference stations when ionosphere delay is extracted;
acquiring an intersection set of the first group of public satellites and the second group of public satellites to obtain a third group of public satellites;
selecting a satellite with the highest altitude angle from a third group of public satellites as a reference satellite;
subtracting the ionospheric delay of all satellites of the same station from the ionospheric delay of the reference satellite to finish conversion of the reference satellite; and simultaneously performing reference star conversion on all baseline solutions in the NRTK modeling area.
In the above method, preferably, the specific steps of constructing the regional ionosphere model using polynomial error compensation are as follows:
estimating and obtaining polynomial coefficients of a regional ionosphere model by using ionosphere delay data of a single-station satellite through a least square parameter adjustment method;
calculating according to the polynomial coefficient to obtain ionospheric delay of each satellite of each reference station;
subtracting the ionospheric delay of each satellite of each reference station from the ionospheric delay of each satellite of the single-station observation satellite to obtain an ionospheric residual error of each satellite of each reference station;
acquiring grid point coordinates of all VRS in an NRTK modeling area, and searching a reference station with the radius within 200km by taking each grid point as a circle center;
interpolation is carried out by utilizing the ionospheric residual error and a reference station corresponding to each lattice point by using an inverse distance weighting algorithm to obtain ionospheric residual error compensation parameters of each lattice point;
counting the RMS value of ionosphere residual errors of all grid points of each satellite, and taking the RMS value as an internal coincidence precision quality factor of each satellite in a modeling area;
and generating VRS of each lattice point through a DCB product by using the polynomial coefficient of each satellite, the ionospheric delay of each satellite, the ionospheric residual error compensation parameter of each satellite of each lattice point and the ionospheric modeling precision quality factor of each satellite.
The invention also provides an ionosphere modeling device based on the fusion of foundation enhancement and star base enhancement, which is characterized by comprising the following components:
the data acquisition module is used for acquiring data, including reference station coordinates, reference station real-time observation data, satellite precise ephemeris, precise clock error, DCB products and UPD products;
the first calculation module is used for obtaining ionospheric delay of a single-station observation satellite by utilizing the data;
the reference star conversion module is used for subtracting the ionospheric delay of all satellites of the same station from the ionospheric delay of the reference star to finish the conversion of the reference star, and simultaneously carrying out the conversion of the reference star on all base line solutions in the NRTK modeling area;
the modeling module is used for constructing an ionosphere model based on fusion of foundation enhancement and star-based enhancement by using polynomial error compensation, wherein the ionosphere model comprises the following components:
Figure BDA0004103311580000051
Figure BDA0004103311580000052
wherein: />
Figure BDA0004103311580000053
For ionospheric delay of the observation satellite s of station i on an inclined path,
Figure BDA0004103311580000054
coefficients of polynomial model, +.>
Figure BDA0004103311580000055
Geographic latitude and longitude at the puncture point for satellite s; phi (phi) 0 、λ 0 Modeling the geographical latitude and longitude of the regional center point for the NRTK ionosphere; ΔSTEC s And compensating the error of the grid point ionosphere residual error.
In the above apparatus, preferably, the first calculation module includes:
the ambiguity fixing unit is used for calculating an ambiguity floating solution by using an ionosphere-free PPP algorithm according to the reference station coordinates; using UPD product, using inter-satellite single difference algorithm to fix ambiguity, obtaining inter-satellite single difference ambiguity fixing solution delta N 1 ,N 2 ；
Ionospheric delay extraction unit for extracting ionospheric delays using geometric phase-free combinations
Figure BDA0004103311580000056
The inclined ionosphere delay calculation unit is used for converting the geometric phase-free combination formula into an inter-satellite single difference form;
Figure BDA0004103311580000057
obtaining the inclined ionosphere delay of the corresponding satellite through the calculation of the following formula;
Figure BDA0004103311580000058
wherein: DCB (DCB) s Correction by DCB product, ++>
Figure BDA0004103311580000059
Ionosphere delay floating solution for reference star.
In the above apparatus, the reference star converting module includes:
the reference satellite acquisition unit is used for setting the cut-off height angle to be 40 degrees, selecting all first group of public satellites for baseline fixed solutions in the NRTK modeling area, and simultaneously selecting all second group of public satellites of the reference stations during ionosphere delay extraction; acquiring an intersection set of the first group of public satellites and the second group of public satellites to obtain a third group of public satellites; selecting a satellite with the highest altitude angle from a third group of public satellites as a reference satellite;
the conversion unit is used for subtracting the ionospheric delay of all satellites of the same station from the ionospheric delay of the reference satellite to finish conversion of the reference satellite; and simultaneously performing reference star conversion on all baseline solutions in the NRTK modeling area.
In the above apparatus, the modeling module includes:
the ionospheric delay and residual calculation unit is used for estimating and obtaining polynomial coefficients of the regional ionospheric model by using ionospheric delay data of the single-station satellite through a least square parameter adjustment method; calculating according to the polynomial coefficient to obtain ionospheric delay of each satellite of each reference station; subtracting the ionospheric delay of each satellite of each reference station from the ionospheric delay of each satellite of the single-station observation satellite to obtain an ionospheric residual error of each satellite of each reference station;
the reference station searching unit is used for acquiring grid point coordinates of all VRS in the NRTK modeling area, and searching reference stations with the radius within 200km by taking each grid point as a circle center;
the compensation calculation unit is used for interpolating to obtain the ionosphere residual error compensation parameter of each grid point by using the ionosphere residual error and the reference station corresponding to each grid point and using an inverse distance weighting algorithm; counting the RMS value of ionosphere residual errors of all grid points of each satellite, and taking the RMS value as an internal coincidence precision quality factor of each satellite in a modeling area;
the VRS generation unit is used for generating VRS of each lattice point by using polynomial coefficient of each satellite, ionosphere residual error compensation parameter of each satellite of each lattice point and ionosphere modeling precision quality factor of each satellite.
The invention also provides a computer readable medium having stored thereon a computer program which, when executed by a processor, implements an ionosphere modeling method based on a fusion of ground-based augmentation and star-based augmentation as described in the claims above.
According to the technical scheme, the ionosphere modeling method, device and medium based on foundation and star-based enhanced fusion, provided by the invention, solve the problems of lower ionosphere modeling precision and higher construction cost and maintenance cost when the NRTK (non-return-to-TK) is out of network or the baseline distance is longer in the prior art. The invention improves the ionosphere error correction precision of VRS, provides high-quality differential data for users, and solves the problem of poor positioning effect of the terminal caused by lower quality of VRS differential data in a wide area range. Compared with the prior art, the invention has the following beneficial effects:
firstly, extracting CORS base station ionosphere delay information in the prior art is to obtain an ambiguity fixed solution through baseline calculation, and then calculate dual-difference ionosphere and troposphere delay information of a baseline; the invention estimates the ionosphere delay information of a single base station by using the ionosphere-free combined PPP and phase geometric combination technology, does not need to build a base line, and is not limited by the distance of the base station.
Second, the existing ionosphere model uses the dual-difference ionosphere delay parameters of the base line in the triangular network to interpolate the ionosphere correction parameters at the VRS through the linear interpolation model; the model has the limitation, and the external interpolation precision of the triangular net is lower. The invention utilizes single-station ionosphere delay parameters, builds a regional ionosphere model through a polynomial error compensation model, interpolates ionosphere delay information of the regional ionosphere model according to the position information of the virtual observation station, and builds double-difference ionosphere delay correction with the ionosphere delay information of the main reference station, and when the virtual reference station is in a certain range outside the network, the regional ionosphere delay model can still provide relatively high-precision ionosphere delay correction for VRS.
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In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following description will make brief description and illustrations of the drawings used in the description of the embodiments of the present invention or the prior art. It is obvious that the drawings in the following description are only some embodiments of the present invention and that other drawings may be obtained from these drawings without inventive effort for a person of ordinary skill in the art.
FIG. 1 is a flowchart of an ionosphere modeling method based on fusion of foundation augmentation and star-based augmentation.
Detailed Description
The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention, and it is apparent that the embodiments described below are only some embodiments of the present invention, but not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without making any inventive effort are intended to fall within the scope of the present invention.
In order to make the explanation and the description of the technical solution and the implementation of the present invention clearer, several preferred embodiments for implementing the technical solution of the present invention are described below.
In this document, the terms "inner, outer", "front, rear", and "left, right" are expressions based on the usage status of the product, and it is apparent that the usage of the corresponding terms does not limit the scope of the present solution.
Referring to fig. 1, fig. 1 is a flowchart of an ionosphere modeling method based on fusion of foundation enhancement and star-based enhancement.
As shown in FIG. 1, the ionosphere modeling method based on fusion of foundation enhancement and star-based enhancement provided by the invention comprises the following steps:
step 110, obtain fixed reference station coordinates, reference station real-time observations and satellite ephemeris, precision clock bias, and DCB (Differential Code Bias differential code bias) product and UPD (Uncalibrated Phase Delays, uncalibrated phase hardware delay) product.
And 120, extracting an ionosphere of the single-station observation satellite by using the fixed reference station coordinates, the reference station real-time observation data, the satellite precise ephemeris, the precise clock difference, the UPD product and the UPD product. The method specifically comprises the following steps:
step 121, calculating an ambiguity floating solution by using an ionosphere-free PPP algorithm according to the reference station coordinates;
step 122, according to the UPD product, using the inter-satellite single difference algorithm to fix the ambiguity, and obtaining the inter-satellite single difference ambiguity fixing solution delta N 1 ,ΔN 2 ；
Step 123, extracting ionospheric delay using geometry-free phase combining
Figure BDA0004103311580000086
The geometric phase-free combination formula is as follows:
Figure BDA0004103311580000081
Figure BDA0004103311580000082
wherein: />
Figure BDA0004103311580000083
Respectively carrier wave f 1 And f 2 Phase observance of>
Figure BDA0004103311580000084
Figure BDA0004103311580000085
For ionospheric delay of corresponding frequency points, DCB r For receiver-side hardware delay, DCB s Lambda is the hardware delay of the satellite s end 1 、λ 2 For the wavelength of the corresponding frequency point, N 1 、N 2 Epsilon as the ambiguity of the corresponding frequency point L1 、ε L2 Is the observed noise of the corresponding frequency point phase observed quantity.
GF (phase no Geometry Free), r represents the reference station; s is the satellite observed by the reference station r; 1,2 are the frequency points f1 and f2 of satellite s, respectively.
Step 124, converting the geometric phase-free combination formula into the following inter-satellite single-difference form based on the fixed-fuzzy reference star as a reference because of the fixed-fuzzy ambiguity fixed solution based on the inter-satellite single-difference;
ΔL GF ＝(γ 2 -1)ΔI 1 +ΔDCB s +λ 1 ΔN 1 -λ 2 ΔN 2 +Δε L1 -Δε L2 ；
wherein DeltaN 1 ,ΔN 2 And (5) fixing the solution of the single-difference ambiguity between corresponding frequency point satellites.
Step 125, ionosphere floating solution with reference to the star
Figure BDA0004103311580000091
As a benchmark, the oblique ionospheric delay for the corresponding satellite is calculated by the following equation:
Figure BDA0004103311580000092
wherein: DCB (DCB) s Correction was performed by DCB product.
Step 130, converting the reference star. Because there is an inconsistent problem of reference stars when extracting ionospheric delay with reference stars for NRTK baseline solution, reference star conversion is required. The method comprises the following specific steps:
step 131, setting a cut-off height angle to be 40 degrees, selecting all first group of public satellites for baseline fixed solutions in an NRTK modeling area, and simultaneously selecting a second group of public satellites of all reference stations when ionosphere delay is extracted;
step 132, intersection sets are obtained for the first group of public satellites and the second group of public satellites, and a third group of public satellites are obtained;
step 133, selecting a satellite with the highest altitude angle from the third group of public satellites as a reference satellite;
step 134, subtracting the ionospheric delay of all satellites in the same station from the ionospheric delay of the reference satellite to complete the conversion of the reference satellite; and simultaneously performing reference star conversion on all baseline solutions in the NRTK modeling area.
In step 140, the ionosphere model based on the fusion of the foundation augmentation and the star-based augmentation is constructed by using polynomial error compensation as follows.
Figure BDA0004103311580000101
In the method, in the process of the invention,
Figure BDA0004103311580000102
the unit TECU is ionospheric delay of the observation satellite s of station i on an inclined path;
Figure BDA0004103311580000103
coefficients that are polynomials; />
Figure BDA0004103311580000104
True latitude and longitude, phi, for satellite s at the puncture point 0 、λ 0 Modeling the geographical latitude and longitude of the regional center point for the NRTK ionosphere; ΔSTEC s And compensating the error of the grid point ionosphere residual error. The method comprises the following specific steps:
step 141, assume first that the model ionospheric residual error is compensated ΔSTEC s 0, estimating an ionospheric model based on fusion of foundation augmentation and satellite-based augmentation by a least square parameter adjustment method by using ionospheric delay data of the single-station satellite obtained in the step 120Polynomial coefficients in the model.
Step 142, calculating the ionospheric delay STEC of each satellite of each reference station according to the polynomial coefficients 0 ；
Step 143, subtracting the ionospheric delay STEC of each satellite of the reference station from the extracted ionospheric delay 0 Obtaining an ionospheric residual error of each satellite of each reference station;
step 144, grid point coordinates of all VRS in the NRTK modeling area are obtained, and reference stations with the radius within 200km are searched by taking each grid point as a circle center;
step 145, interpolating the ionospheric residual error and the reference station corresponding to each lattice point by using an inverse distance weighting algorithm to obtain ionospheric residual error compensation parameters of each lattice point;
step 146, counting the RMS value of ionosphere residual errors of all grid points of each satellite, and taking the RMS value as an internal coincidence precision quality factor of each satellite in a modeling area;
step 147, polynomial coefficients for each satellite
Figure BDA0004103311580000105
Ionospheric delay STEC for each satellite 0 And (3) the ionosphere residual error compensation parameter of each satellite of each grid point, and the ionosphere modeling precision quality factor of each satellite is sent to a DCB product to generate VRS of each grid point.
Based on the method, the invention also provides an ionosphere modeling device based on the fusion of foundation enhancement and star base enhancement, which comprises the following steps:
the data acquisition module is used for acquiring data, including reference station coordinates, reference station real-time observation data, satellite precise ephemeris, precise clock error, DCB products and UPD products;
the first calculation module is used for obtaining ionospheric delay of a single-station observation satellite by utilizing the data;
the reference star conversion module is used for subtracting the ionospheric delay of all satellites of the same station from the ionospheric delay of the reference star to finish the conversion of the reference star, and simultaneously carrying out the conversion of the reference star on all base line solutions in the NRTK modeling area;
the modeling module is used for constructing an ionosphere model based on fusion of foundation enhancement and star-based enhancement by using polynomial error compensation, wherein the ionosphere model comprises the following components:
Figure BDA0004103311580000111
Figure BDA0004103311580000112
wherein: />
Figure BDA0004103311580000113
Ionospheric delay on the inclined path for the observation satellite s of station i, +.>
Figure BDA0004103311580000114
Coefficients of polynomial +.>
Figure BDA0004103311580000115
Geographic latitude and longitude at the puncture point for satellite s; phi (phi) 0 、λ 0 Modeling the geographical latitude and longitude of the regional center point for the NRTK ionosphere; ΔSTEC s And compensating the error of the grid point ionosphere residual error.
The ionosphere modeling method based on the foundation and star-based enhanced fusion can be realized as a computer software program. For example, the present invention also provides a computer readable medium having stored thereon a computer program which, when executed by a processor, implements the ionosphere modeling method described above based on ground-based and star-based enhanced fusion.
By combining the description of the specific embodiments, the ionosphere modeling method, the ionosphere modeling device and the ionosphere modeling medium based on the foundation and star-based enhanced fusion have the following advantages compared with the prior art:
firstly, the invention adopts PPP single base station operation, and can obtain high-precision ionosphere delay information after the ambiguity is fixed, thereby improving the extraction precision of the ionosphere delay information under the condition of medium-length base lines and being not limited by the distance of the base station.
Secondly, the ionosphere interpolation model constructed by the invention is an atmospheric model of the whole CORS network coverage area, enlarges the NRTK service range, and can still maintain the service precision when the virtual reference station is in a certain out-of-network range.
Thirdly, the invention can utilize fewer base stations to realize the service equivalent to the traditional NRTK, and reduces the construction cost of the NRTK in a wide area range.
Finally, it is also noted that the terms "comprises," "comprising," or any other variation thereof, as used herein, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one …" does not exclude the presence of other like elements in a process, method, article, or apparatus that comprises the element.
The present invention is not limited to the above-mentioned preferred embodiments, and any person who can learn the structural changes made under the teaching of the present invention can fall within the scope of the present invention if the present invention has the same or similar technical solutions.

Claims (10)

1. An ionosphere modeling method based on fusion of foundation enhancement and star base enhancement is characterized by comprising the following steps:
acquiring reference station coordinates, real-time observation data of a reference station, satellite precise ephemeris, precise clock error, DCB products and UPD products;
extracting ionospheric delay of a single-station observation satellite by using reference station coordinates, real-time observation data of the reference station, satellite precise ephemeris, precise clock error and DCB products;
subtracting the ionospheric delay of all satellites of the same station from the ionospheric delay of a reference satellite, performing reference satellite conversion, and simultaneously performing reference satellite conversion on all baseline solutions in the NRTK modeling area;
constructing an ionosphere model based on fusion of foundation enhancement and star-based enhancement by using polynomial error compensation, wherein the ionosphere model comprises the following components:
Figure FDA0004103311570000011
Figure FDA0004103311570000012
wherein: />
Figure FDA0004103311570000013
For ionospheric delay of the observation satellite s of station i on an inclined path,
Figure FDA0004103311570000014
coefficients of polynomial +.>
Figure FDA0004103311570000015
Geographic latitude and longitude at the puncture point for satellite s; phi (phi) 0 、λ 0 Modeling the geographical latitude and longitude of the regional center point for the NRTK ionosphere; ΔSTEC s And compensating the error of the grid point ionosphere residual error.
2. The method according to claim 1, characterized in that the specific step of obtaining the ionospheric delay of a single-station observation satellite is as follows:
calculating a ambiguity floating solution by using an ionosphere-free PPP algorithm according to the reference station coordinates;
using UPD product, using inter-satellite single difference algorithm to fix ambiguity, obtaining inter-satellite single difference fixed ambiguity delta N 1 ,N 2 ；
Converting the geometric phase-free combination formula into an inter-satellite single difference form;
Figure FDA0004103311570000016
Figure FDA0004103311570000017
obtaining the inclined ionosphere delay of the corresponding satellite by calculation according to the following formula
Figure FDA0004103311570000018
Figure FDA0004103311570000019
Wherein: DCB (DCB) s Correction by DCB product, ++>
Figure FDA0004103311570000021
Ionosphere delay floating solution for reference star.
3. The method of claim 1, wherein the ionospheric delay is extracted using a geometry-free phase combination of
Figure FDA0004103311570000022
Figure FDA0004103311570000023
Figure FDA0004103311570000024
Wherein: />
Figure FDA0004103311570000025
Respectively carrier wave f 1 And f 2 Phase observance of>
Figure FDA0004103311570000026
Figure FDA0004103311570000027
For frequency point f 1 Ionospheric delay, DCB r For receiver-side hardware delay, DCB s Lambda is the hardware delay of the satellite s end 1 、λ 2 For the corresponding frequency point f 1 And f 2 Wavelength of N 1 、N 2 For the corresponding frequency point f 1 And f 2 Is of the degree of ambiguity epsilon L1 、ε L2 For the corresponding frequency point f 1 And f 2 Observation noise of phase observables.
4. The method according to claim 1, characterized in that the specific step of converting the reference star is as follows:
setting a cut-off height angle to be 40 degrees, selecting all first group of public satellites for baseline fixed solutions in an NRTK modeling area, and simultaneously selecting a second group of public satellites of all reference stations when ionosphere delay is extracted;
acquiring an intersection set of the first group of public satellites and the second group of public satellites to obtain a third group of public satellites;
selecting a satellite with the highest altitude angle from a third group of public satellites as a reference satellite;
subtracting the ionospheric delay of all satellites of the same station from the ionospheric delay of the reference satellite to finish conversion of the reference satellite; and simultaneously performing reference star conversion on all baseline solutions in the NRTK modeling area.
5. The method of claim 1, wherein the specific steps of constructing the regional ionosphere model using polynomial error compensation are as follows:
estimating and obtaining polynomial coefficients of a regional ionosphere model by using ionosphere delay data of a single-station satellite through a least square parameter adjustment method;
calculating according to the polynomial coefficient to obtain ionospheric delay of each satellite of each reference station;
subtracting the ionospheric delay of each satellite of each reference station from the ionospheric delay of each satellite of the single-station observation satellite to obtain an ionospheric residual error of each satellite of each reference station;
acquiring grid point coordinates of all VRS in an NRTK modeling area, and searching a reference station with the radius within 200km by taking each grid point as a circle center;
interpolation is carried out by utilizing the ionospheric residual error and the reference station corresponding to each lattice point by using an inverse distance weighting algorithm to obtain a grid point ionospheric residual error compensation term delta STEC for each lattice point s ；
Counting the RMS value of ionosphere residual errors of all grid points of each satellite, and taking the RMS value as an internal coincidence precision quality factor of each satellite in a modeling area;
and generating VRS of each lattice point by using the polynomial coefficient of each satellite, the ionosphere residual error compensation parameter of each satellite of each lattice point and the ionosphere modeling precision quality factor of each satellite.
6. Ionosphere modeling device based on foundation augmentation and star-based augmentation fusion, characterized by comprising:
the data acquisition module is used for acquiring coordinates of a reference station, real-time observation data of the reference station, satellite precise ephemeris, precise clock error, DCB products and UPD products;
the first calculation module is used for obtaining ionospheric delay of a single-station observation satellite by utilizing the data;
the reference star conversion module is used for subtracting the ionospheric delay of all satellites of the same station from the ionospheric delay of the reference star to finish the conversion of the reference star, and simultaneously carrying out the conversion of the reference star on all base line solutions in the NRTK modeling area;
the modeling module is used for constructing an ionosphere model based on fusion of foundation enhancement and star-based enhancement by using polynomial error compensation, wherein the ionosphere model comprises the following components:
Figure FDA0004103311570000031
Figure FDA0004103311570000032
wherein: />
Figure FDA0004103311570000033
Ionospheric delay of an observation satellite s on an inclined path for station iThe delay is one which,
Figure FDA0004103311570000034
coefficients of polynomial +.>
Figure FDA0004103311570000035
Geographic latitude and longitude at the puncture point for satellite s; phi (phi) 0 、λ 0 Modeling the geographical latitude and longitude of the regional center point for the NRTK ionosphere; ΔSTEC s And compensating the error of the grid point ionosphere residual error.
7. The apparatus of claim 6, wherein the first computing module comprises:
the ambiguity fixing unit is used for calculating an ambiguity floating solution by using an ionosphere-free PPP algorithm according to the reference station coordinates; using UPD product, using inter-satellite single difference algorithm to fix ambiguity, obtaining inter-satellite single difference ambiguity fixing solution delta N 1 ,ΔN 2 ；
Ionospheric delay extraction unit for extracting ionospheric delays using geometric phase-free combinations
Figure FDA0004103311570000041
The inclined ionosphere delay calculation unit is used for converting a geometric phase combination formula without a fixed ambiguity reference star into an inter-star single difference form;
Figure FDA0004103311570000044
Figure FDA0004103311570000045
ionosphere delayed floating solution with reference star>
Figure FDA0004103311570000042
Obtaining the inclined ionospheric delay of the corresponding satellite by calculation with the following formula as a reference; />
Figure FDA0004103311570000043
Wherein: DCB (DCB) s Correction was performed by DCB product.
8. The apparatus of claim 7, wherein the reference star conversion module comprises:
the reference satellite acquisition unit is used for setting the cut-off height angle to be 40 degrees, selecting all first group of public satellites for baseline fixed solutions in the NRTK modeling area, and simultaneously selecting all second group of public satellites of the reference stations during ionosphere delay extraction; acquiring an intersection set of the first group of public satellites and the second group of public satellites to obtain a third group of public satellites; selecting a satellite with the highest altitude angle from a third group of public satellites as a reference satellite;
the conversion unit is used for subtracting the ionospheric delay of all satellites of the same station from the ionospheric delay of the reference satellite to finish conversion of the reference satellite; and simultaneously performing reference star conversion on all baseline solutions in the NRTK modeling area.
9. The apparatus of claim 7, wherein the modeling module comprises:
the ionospheric delay and residual calculation unit is used for estimating and obtaining polynomial coefficients of the regional ionospheric model by using ionospheric delay data of the single-station satellite through a least square parameter adjustment method; calculating according to the polynomial coefficient to obtain ionospheric delay of each satellite of each reference station; subtracting the ionospheric delay of each satellite of each reference station from the ionospheric delay of each satellite of the single-station observation satellite to obtain an ionospheric residual error of each satellite of each reference station;
the reference station searching unit is used for acquiring grid point coordinates of all VRS in the NRTK modeling area, and searching reference stations with the radius within 200km by taking each grid point as a circle center;
the compensation calculation unit is used for interpolating to obtain the ionosphere residual error compensation parameter of each grid point by using the ionosphere residual error and the reference station corresponding to each grid point and using an inverse distance weighting algorithm; counting the RMS value of ionosphere residual errors of all grid points of each satellite, and taking the RMS value as an internal coincidence precision quality factor of each satellite in a modeling area;
and the VRS generation unit is used for generating the VRS of each grid point by using the polynomial coefficient of each satellite, the ionosphere residual error compensation parameter of each satellite of each grid point and the ionosphere modeling precision quality factor of each satellite.
10. A computer readable medium, on which a computer program is stored which, when being executed by a processor, implements the ionosphere modeling method based on a fusion of ground-based augmentation and satellite-based augmentation as claimed in any one of claims 1 to 5.
CN202310184489.1A 2023-02-28 2023-02-28 Ionosphere modeling method, device and medium based on foundation and star-based enhanced fusion Pending CN116203598A (en)

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN116609799A (en) * 2023-07-20 2023-08-18 武汉大学 Generation method and device of centimeter-level oblique ionosphere delay product
CN116931007A (en) * 2023-08-31 2023-10-24 腾讯科技（深圳）有限公司 Ionosphere delay processing method, ionosphere delay processing device, ionosphere delay processing equipment and storage medium

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN116609799A (en) * 2023-07-20 2023-08-18 武汉大学 Generation method and device of centimeter-level oblique ionosphere delay product
CN116609799B (en) * 2023-07-20 2023-10-20 武汉大学 Generation method and device of centimeter-level oblique ionosphere delay product
CN116931007A (en) * 2023-08-31 2023-10-24 腾讯科技（深圳）有限公司 Ionosphere delay processing method, ionosphere delay processing device, ionosphere delay processing equipment and storage medium
CN116931007B (en) * 2023-08-31 2023-12-08 腾讯科技（深圳）有限公司 Ionosphere delay processing method, ionosphere delay processing device, ionosphere delay processing equipment and storage medium

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