CN117930283B - Beidou ionosphere delay correction method and device based on low-orbit navigation satellite augmentation - Google Patents
Beidou ionosphere delay correction method and device based on low-orbit navigation satellite augmentation Download PDFInfo
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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
- G01S19/03—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
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- 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
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Abstract
The invention provides a Beidou ionosphere delay correction method and device based on low-orbit navigation satellite enhancement, comprising the following steps: determining an upper vertical ionosphere delay amount corresponding to the low-orbit navigation satellite based on the observation value of the low-orbit navigation satellite to the Beidou satellite through an inclined ionosphere delay descent correlation model; determining the whole-course vertical ionosphere delay amount corresponding to the low-orbit navigation satellite according to the upper vertical ionosphere delay amount through a scale factor expression; and correcting the inclined ionosphere delay of the user terminal based on the whole-course vertical ionosphere delay amount by using a vertical ionosphere correction model to obtain the user terminal-Beidou inclined ionosphere delay amount after the low-orbit navigation satellite enhancement correction. The invention can obviously improve the precision of ionosphere delay correction of the user terminal-Beidou satellite.
Description
Technical Field
The invention relates to the technical field of earth observation and navigation, in particular to a Beidou ionosphere delay correction method and device based on low-orbit navigation satellite enhancement.
Background
Nowadays, the low-orbit satellite at home and abroad enters the vigorous development period, and compared with Beidou and other navigation satellites, the low-orbit satellite has the advantages of wide coverage (capable of effectively covering two-pole areas), high running speed, high satellite geometric configuration change, low comprehensive cost and the like. Besides the fact that the low-orbit navigation satellite can downwards emit navigation signals to achieve an independent navigation positioning function, the low-orbit navigation satellite can be used as a 'Tian base station' to rapidly and stably monitor the Beidou satellite through the Beidou monitoring receiver.
The ionosphere delay error is an important error source in the Beidou navigation positioning system, and seriously affects the positioning precision, particularly the Beidou single-frequency positioning user, and the high-precision and high-reliability ionosphere delay can effectively improve the positioning precision and accelerate the convergence of precise single-point positioning. At present, a method for modeling a Beidou ionized layer by using Beidou ground monitoring stations has the problems of small distribution and non-uniformity of the ground monitoring stations, and the precision of ionosphere delay estimation and modeling of the areas is not high, so that the requirements of high precision and high reliability of positioning cannot be met; the ionosphere is an atmospheric layer area 60-2000 km away from the ground, low-orbit satellites usually run between the atmospheric layer areas, and Beidou satellites run in space areas above 20000km, and the method for modeling the ionosphere by using the low-orbit satellites cannot realize the estimation and modeling of the ionosphere delay from a ground user terminal to the whole path of the Beidou satellites. In addition, in conventional ionospheric delay estimation, there is a high correlation between the ionospheric delay and the hardware bias, and separation cannot be performed, and the two are usually combined and estimated, which affects the accuracy of ionospheric delay estimation. The low-orbit navigation satellite, the Beidou satellite and the space geometrical distribution of the user position can influence the user ionosphere delay correction, and in general, a plurality of position ionosphere delays are directly interpolated to correct the user, but the influence is not considered, so that the user ionosphere delay correction precision is reduced.
Disclosure of Invention
Therefore, the invention aims to provide a Beidou ionosphere delay correction method and device based on low-orbit navigation satellite enhancement, which can remarkably improve the precision of user terminal-Beidou satellite ionosphere delay correction.
In a first aspect, an embodiment of the present invention provides a low-orbit navigation satellite-based enhanced beidou ionosphere delay correction method, including:
determining an upper vertical ionosphere delay amount corresponding to a low-orbit navigation satellite based on an observation value of the low-orbit navigation satellite to a Beidou satellite through an inclined ionosphere delay descent correlation model; the inclined ionosphere delay-falling correlation model is constructed based on pseudo-range and carrier phase deviation caused by hardware bias errors of Beidou satellites and space-based receivers;
Determining the whole-course vertical ionosphere delay amount corresponding to the low-orbit navigation satellite according to the upper vertical ionosphere delay amount through a scale factor expression; the scale factor expression is constructed based on ionosphere space change characteristics and ionosphere peak value attributes;
Correcting the inclined ionosphere delay of the user terminal based on the whole-course vertical ionosphere delay amount by a vertical ionosphere correction model to obtain a Beidou inclined ionosphere delay amount of the user terminal subjected to low-orbit navigation satellite enhanced correction; the vertical ionosphere correction model is constructed based on a spatial geometrical relationship of tight coupling between a user terminal and a low-orbit navigation satellite and between the low-orbit navigation satellite and a Beidou satellite.
In one embodiment, the step of constructing the inclined ionosphere delay-down correlation model includes:
Constructing a low-orbit navigation-Beidou satellite observation equation, and carrying out differential combination on the low-orbit navigation-Beidou satellite observation equation to form a low-orbit navigation-Beidou differential combination observation equation;
Constructing an electronic total content calculation equation on an observation path based on the low-orbit navigation-Beidou satellite observation equation and the low-orbit navigation-Beidou differential combination observation equation; and in a steady observation time period, adding and averaging the low-rail navigation-Beidou differential combination observation equation;
Substituting the low-orbit navigation-Beidou differential combination observation equation subjected to addition and averaging treatment into an electronic total content calculation equation on the observation path to obtain an inclined ionosphere delay descent correlation model.
In one embodiment, the expression of the inclined ionospheric delay-down correlation model is as follows:
；
；
Wherein, For low-orbit navigation satellite pairObserved value of Beidou satelliteIs a frequency coefficient,For the upper vertical ionospheric delay amount corresponding to a low-orbit navigation satellite,Differential code deviation for receiver corresponding to space-based receiver,For satellite differential code deviation corresponding to low-orbit navigation satellite,Is an intermediate parameter,Is the earth radius,Is ionosphere equivalent height,For low orbit navigation satellite altitude,For low-orbit navigation satellite pairZenith angles of the Beidou satellites.
In one embodiment, the step of determining the upper vertical ionospheric delay amount corresponding to the low-orbit navigation satellite based on the observation value of the low-orbit navigation satellite to the Beidou satellite by using the inclined ionospheric delay-down correlation model comprises the following steps:
Constructing a related state equation and an observation equation;
Based on the relative state equation and the observation equation, iterating receiver differential code deviation and satellite differential code deviation at each time in a steady observation period;
Taking the receiver differential code deviation and the satellite differential code deviation at the appointed moment as a target receiver differential code deviation and a target satellite differential code deviation;
And inputting the observed value of the low-orbit navigation satellite to the Beidou satellite, the target receiver differential code deviation and the target satellite differential code deviation into the inclined ionosphere delay-falling correlation model to obtain the upper vertical ionosphere delay quantity corresponding to the low-orbit navigation satellite.
In one embodiment, the step of determining the global vertical ionospheric delay amount corresponding to the low-orbit navigation satellite according to the upper vertical ionospheric delay amount by a scale factor expression includes:
Determining a target scale factor value based on the electronic peak height, the height of the low-orbit navigation satellite and the elevation constant through a scale factor expression;
taking the ratio of the upper vertical ionospheric delay to the target scale factor value as the whole-course vertical ionospheric delay corresponding to the low-orbit navigation satellite;
The expression of the scale factor expression is as follows:
；
Wherein, Is the target proportion factor value,Is the base of natural logarithm,Is the electron peak height,Is the altitude of the low-orbit navigation satellite,Is an elevation constant.
In one embodiment, the number of low-orbit navigation satellites is a plurality; correcting the inclined ionosphere delay of the user terminal based on the whole-course vertical ionosphere delay amount by a vertical ionosphere correction model to obtain a user terminal-Beidou inclined ionosphere delay amount after low-orbit navigation satellite enhancement correction, wherein the method comprises the following steps of:
determining a low-orbit navigation reference satellite from the low-orbit navigation satellites based on the altitude angles corresponding to the low-orbit navigation satellites;
For other low-orbit navigation satellites except the low-orbit navigation reference satellite, fitting a coefficient estimation value of a vertical ionospheric correction model based on a whole-course vertical ionospheric delay difference value, a first longitude difference value and a first latitude difference value between the low-orbit navigation satellite and the low-orbit navigation reference satellite to obtain a target vertical ionospheric correction model; wherein the first longitude difference value and the first latitude difference value are used to characterize a spatial geometry relationship between the low-orbit navigation satellite and the low-orbit navigation reference satellite;
Inputting a second longitude difference value and a second latitude difference value between the user terminal and the low-orbit navigation reference satellite into the target vertical ionosphere correction model to obtain a whole-course vertical ionosphere delay amount difference value between the user terminal and the low-orbit navigation reference satellite; wherein the second longitude difference value and the second latitude difference value are used to characterize a spatial geometry relationship between the user terminal and the low-orbit navigation reference satellite;
and correcting the inclined ionosphere delay of the user terminal according to the whole-course vertical ionosphere delay difference between the user terminal and the low-orbit navigation reference satellite to obtain the enhanced and corrected user terminal-Beidou inclined ionosphere delay of the low-orbit navigation satellite.
In one embodiment, the expression of the target vertical ionospheric correction model is as follows:
；
Wherein, For the user terminalAnd the low-orbit navigation reference satelliteDifference in global vertical ionospheric delay between、Is a coefficient estimation value,For the user terminalWith the low-orbit navigation reference satelliteSecond longitude difference between,For the user terminalAnd the low-orbit navigation reference satelliteA second latitude difference value therebetween.
In a second aspect, an embodiment of the present invention further provides a low-orbit navigation satellite-based enhanced beidou ionosphere delay correction device, including:
The upper vertical ionospheric delay calculation module is used for determining the upper vertical ionospheric delay amount corresponding to the low-orbit navigation satellite based on the observation value of the low-orbit navigation satellite to the Beidou satellite through the inclined ionospheric delay descent correlation model; the inclined ionosphere delay-falling correlation model is constructed based on pseudo-range and carrier phase deviation caused by hardware bias errors of Beidou satellites and space-based receivers;
The whole-course vertical ionosphere delay calculation module is used for determining the whole-course vertical ionosphere delay amount corresponding to the low-orbit navigation satellite according to the upper vertical ionosphere delay amount through a scale factor expression; the scale factor expression is constructed based on ionosphere space change characteristics and ionosphere peak value attributes;
The ionosphere delay enhancement correction module is used for correcting the inclined ionosphere delay of the user terminal based on the whole-course vertical ionosphere delay amount through a vertical ionosphere correction model to obtain a user terminal-Beidou inclined ionosphere delay amount after low-orbit navigation satellite enhancement correction; the vertical ionosphere correction model is constructed based on a spatial geometrical relationship of tight coupling between a user terminal and a low-orbit navigation satellite and between the low-orbit navigation satellite and a Beidou satellite.
In a third aspect, an embodiment of the present invention further provides an electronic device comprising a processor and a memory storing computer-executable instructions executable by the processor to implement the method of any one of the first aspects.
In a fourth aspect, embodiments of the present invention also provide a computer-readable storage medium storing computer-executable instructions which, when invoked and executed by a processor, cause the processor to implement the method of any one of the first aspects.
According to the method and the device for correcting the ionospheric delay based on the low-orbit navigation satellite enhancement, which are provided by the embodiment of the invention, the ionospheric delay of the Beidou satellite is monitored based on a large number of uniformly distributed space-based receivers of the low-orbit navigation satellite, so that the problem of insufficient number of Beidou ground monitoring stations is effectively solved; the pseudo range and carrier phase deviation caused by the hardware bias errors of the Beidou satellite and the space-based receiver are finely considered, so that the correlation between ionosphere delay and hardware bias parameters and the influence of hardware bias on the ionosphere delay estimation accuracy are effectively reduced, and the estimation accuracy of the upper vertical ionosphere delay amount is improved; in addition, the influence of the spatial variation characteristic of the ionized layer and the attribute of the peak value of the ionized layer is comprehensively considered, so that the whole-course vertical ionized layer delay amount can be accurately calculated; furthermore, the spatial geometrical distribution relation among the low-orbit navigation satellite, the Beidou satellite and the user terminal is fully considered, and the accuracy of ionosphere delay correction of the user terminal-the Beidou satellite is further improved.
In order to make the above objects, features and advantages of the present invention more comprehensible, preferred embodiments accompanied with figures are described in detail below.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings that are needed in the description of the embodiments or the prior art will be briefly described, and it is obvious that the drawings in the description below are some embodiments of the present invention, and other drawings can be obtained according to the drawings without inventive effort for a person skilled in the art.
FIG. 1 is a schematic flow chart of a Beidou ionosphere delay correction method based on low-orbit navigation satellite augmentation, which is provided by an embodiment of the invention;
FIG. 2 is a general flow chart of a Beidou ionosphere delay correction method based on low-orbit navigation satellite augmentation, which is provided by an embodiment of the invention;
FIG. 3 is a flow chart of an upper vertical ionospheric delay and hardware bias estimation scheme in accordance with an embodiment of the present invention;
fig. 4 is a schematic structural diagram of a low-orbit navigation satellite system-based Beidou ionosphere delay correction device according to an embodiment of the present invention;
Fig. 5 is a schematic structural diagram of an electronic device according to an embodiment of the present invention.
Detailed Description
For the purpose of making the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the technical solutions of the present invention will be clearly and completely described in conjunction with the embodiments, and it is apparent that the described embodiments are some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
At present, the problem of lower ionospheric delay correction precision exists in the related art, and based on the problem, the implementation of the invention provides the Beidou ionosphere delay correction method and device based on low-orbit navigation satellite enhancement, which can remarkably improve the precision of ionosphere delay correction of a user terminal-a Beidou satellite.
For the convenience of understanding the present embodiment, first, a low-orbit navigation satellite-based enhanced beidou ionosphere delay correction method disclosed in the present embodiment is described in detail, referring to a flow chart of a low-orbit navigation satellite-based enhanced beidou ionosphere delay correction method shown in fig. 1, the method mainly includes the following steps S102 to S106:
Step S102, determining the upper vertical ionospheric delay amount corresponding to the low-orbit navigation satellite based on the observation value of the low-orbit navigation satellite to the Beidou satellite through the inclined ionospheric delay-down correlation model.
The inclined ionosphere delay-falling correlation model is constructed based on pseudo-range and carrier phase deviation caused by hardware bias errors of Beidou satellites and space-based receivers. In one example, a low-orbit navigation-Beidou differential combined observation equation can be formed on the basis of the low-orbit navigation-Beidou satellite observation equation, and then an inclined ionosphere delay descent correlation model is constructed by combining the low-orbit navigation-Beidou satellite observation equation and the low-orbit navigation-Beidou differential combined observation equation; and meanwhile, solving constant which is unchanged at any time in the whole steady observation period according to a relevant state equation and an observation equation corresponding to the low-orbit navigation satellite, taking the constant as a coefficient value of a delay-drop correlation model of the inclined ionosphere, substituting an observation value of the low-orbit navigation satellite on the Beidou satellite into the delay-drop correlation model of the inclined ionosphere, and obtaining the upper vertical ionosphere delay corresponding to the low-orbit navigation satellite.
And step S104, determining the whole-course vertical ionospheric delay amount corresponding to the low-orbit navigation satellite according to the upper vertical ionospheric delay amount by a scale factor expression.
The scale factor expression is constructed based on ionospheric space change characteristics and ionospheric peak value attributes. In one example, a scale factor expression may be constructed based on the ionosphere control change characteristic and the ionosphere peak value attribute, and the electronic peak value height, the height and the elevation constant of the low-orbit navigation satellite are substituted into the scale factor expression to obtain a target scale factor value, and the target scale factor value is used to adjust the upper vertical ionosphere delay amount, so as to obtain the full-course vertical ionosphere delay amount corresponding to the low-orbit navigation satellite.
And S106, correcting the inclined ionosphere delay of the user terminal based on the whole-course vertical ionosphere delay amount by using a vertical ionosphere correction model to obtain the Beidou inclined ionosphere delay amount of the user terminal after the enhancement correction of the low-orbit navigation satellite.
The vertical ionosphere correction model is constructed based on the space geometrical relationship of the tight coupling of the user terminal, the low-orbit navigation satellite and the Beidou satellite. In one example, a low-orbit navigation reference satellite is first selected; fitting a coefficient estimation value of the vertical ionospheric correction model based on the whole-course vertical ionospheric delay difference value, the first longitude difference value and the first latitude difference value between other low-orbit navigation satellites and the low-orbit navigation reference satellite to obtain a target vertical ionospheric correction model; and determining the delay amount of the Beidou inclined ionosphere of the user terminal after the enhancement correction of the low-orbit navigation satellite based on a second longitude difference value and a second latitude difference value between the user terminal and the low-orbit navigation reference satellite through a target vertical ionosphere correction model.
According to the low-orbit navigation satellite enhanced Beidou ionosphere delay correction method provided by the embodiment of the invention, the ionosphere delay of the Beidou satellites is monitored by the space-based receivers based on a large number of uniformly distributed low-orbit navigation satellites, so that the problem of insufficient number of Beidou ground monitoring stations is effectively solved; the pseudo range and carrier phase deviation caused by the hardware bias errors of the Beidou satellite and the space-based receiver are finely considered, so that the correlation between ionosphere delay and hardware bias parameters and the influence of hardware bias on the ionosphere delay estimation accuracy are effectively reduced, and the estimation accuracy of the upper vertical ionosphere delay amount is improved; in addition, the influence of the spatial variation characteristic of the ionized layer and the attribute of the peak value of the ionized layer is comprehensively considered, so that the whole-course vertical ionized layer delay amount can be accurately calculated; furthermore, the spatial geometrical distribution relation among the low-orbit navigation satellite, the Beidou satellite and the user terminal is fully considered, and the accuracy of ionosphere delay correction of the user terminal-the Beidou satellite is further improved.
For easy understanding, the embodiment of the present invention provides a specific implementation of a low-orbit navigation satellite-based enhanced beidou ionosphere delay correction method, referring to an overall flowchart of the low-orbit navigation satellite-based enhanced beidou ionosphere delay correction method shown in fig. 2, including: the method comprises the steps of (1) calculating the upper vertical ionospheric delay of the low-orbit navigation satellite, wherein the calculation comprises a low-orbit navigation-Beidou satellite observation equation, a low-orbit navigation-Beidou differential combination observation equation, an inclined ionospheric delay descent correlation model, a correlation state equation and an observation equation, and outputting the upper vertical ionospheric delay of the low-orbit navigation satellite; secondly, calculating the whole-process vertical ionosphere delay based on the scale factors, and outputting the whole-process vertical ionosphere delay amount; and thirdly, the user small-scale grid Beidou ionosphere delay enhancement correction is carried out, and the user terminal Beidou inclined ionosphere delay quantity is output. Specific:
(one) low-orbit navigation satellite upper vertical ionospheric delay calculation:
According to the method, correlation between pseudo-range and carrier phase deviation caused by hardware bias errors of Beidou satellites and antenna base stations and correlation between ionosphere delay and hardware bias are fully and finely considered, and the ionosphere and hardware bias errors are independently calculated, so that high-precision upper ionosphere delay is obtained.
See, in particular, steps 1A to 1D below:
step 1A, a low-orbit navigation-Beidou satellite observation equation is constructed, and the low-orbit navigation-Beidou satellite observation equation can be also called a low-orbit navigation-Beidou satellite double-frequency pseudo-range and carrier observation equation.
And (3) fine core errors, constructing a low-orbit navigation-Beidou satellite observation equation, wherein the equation is shown in the following formula 1:
；
In the method, in the process of the invention, 、、、Respectively two frequencies (/ >)And) Corresponding pseudo-range and carrier observation values; /(I)The distance between the two satellites is; /(I)Clock skew for the receiver; /(I)Is satellite clock error; /(I)Is a tropospheric delay; /(I)For frequencyIs a tilted ionospheric delay; Is an ionospheric scale factor; /(I) 、、、Wavelength and ambiguity corresponding to two frequencies; /(I)、、、The pseudo-range deviation of the receiver and the satellite corresponding to the two frequencies is respectively calculated; /(I)、、、Respectively corresponding to two frequencies, namely a receiver and satellite carrier deviation; /(I)、、、And the pseudo range and the carrier wave observation noise corresponding to the two frequencies are respectively obtained.
Wherein equation 2 is known:
；
In the method, in the process of the invention, To observe the total electron content in the path.
Step 1B, differential combination of observation equations is carried out, and the method is specifically as follows: and carrying out differential combination on the low-orbit navigation-Beidou satellite observation equation to form a low-orbit navigation-Beidou differential combination observation equation, which can also be called as a pseudo-range and carrier differential combination observation equation.
Differential combination is carried out based on a low-orbit navigation-Beidou satellite observation equation to form a low-orbit navigation-Beidou differential combination observation equation, and the equation is shown in the following formula 3:
；
Wherein, The differential code bias code of the space-based receiver; /(I)The differential code bias code is the differential code bias code of the low-orbit navigation satellite; /(I)The differential code phase deviation of the space-based receiver; /(I)Differential code phase deviation for low-orbit navigation satellite; collectively referred to as hardware bias,、、。
Step 1C, constructing an inclined ionosphere delay descent correlation model, which specifically comprises the following steps 1C-1 to 1C-3:
and step 1C-1, constructing an electronic total content calculation equation on an observation path based on a low-orbit navigation-Beidou satellite observation equation and a low-orbit navigation-Beidou differential combination observation equation.
In one example, equations 1,2 and 3 are combined to obtain the equation for calculating the total electron content in the observation path, as shown in equation 4 below:
；
In the method, in the process of the invention, 、, Representing pseudo-range and phase observations, respectively. The conditions are known a priori: /(I)、、、Is a constant that remains unchanged throughout the day.
And step 1C-2, adding and averaging the low-rail navigation-Beidou differential combination observation equation in a steady observation time period.
In one example, during a robust observation period,Is a constant. According to the prior known condition, the low-rail navigation-Beidou differential combination observation equation shown in the formula 3 is added and averaged in a robust observation period, so that the following formula 5 can be obtained:
；
Shifting equation 5 right and left can yield equation 6 as follows:
。
and step 1C-3, substituting the low-orbit navigation-Beidou differential combination observation equation subjected to the average treatment into an electronic total content calculation equation on an observation path to obtain an inclined ionosphere delay drop correlation model.
Is provided withAnd introducing the formula 6 into the formula 4 to construct a high-precision inclined ionosphere delay-down correlation model, wherein the high-precision inclined ionosphere delay-down correlation model is shown in the following formula 7:
；
during the robust observation period, let At moment, one low-orbit navigation satellite pair Beidou satelliteObserved valueThe method comprises the following steps: According to the delay conversion relation between vertical and inclined ionosphere （For the low-orbit satellite upper vertical ionospheric delay), the inclined ionospheric delay-reduction correlation model can be shown in equations 8 and 9 as follows:
；
Wherein:
；
Wherein, For low-orbit navigation satellite pairObserved value of Beidou satelliteIs a frequency coefficient,For the upper vertical ionospheric delay amount corresponding to a low-orbit navigation satellite,Differential code deviation for receiver corresponding to space-based receiver,For satellite differential code deviation corresponding to low-orbit navigation satellite,Is an intermediate parameter,Is the earth radius (the value is 6378.137 km),Is ionosphere equivalent height (value is 750 km)For low orbit navigation satellite altitude,For low-orbit navigation satellite pairZenith angles of the Beidou satellites.
Step 1D, vertical ionospheric delay calculation, specifically comprising the following steps 1D-1 to 1D-4:
And step 1D-1, constructing a related state equation and an observation equation.
At a certain moment, a certain low-orbit satellite simultaneously observesThe big Dipper satellites formThe observation equation matrix expression is shown in formula 10:
；
Wherein, ，Representing the identity matrix, the relevant state equation and observation equation are shown in the following equation 11:
；
Wherein, 、The state noise and the observation noise are respectively, and the covariance matrix corresponding to the state noise and the observation noise is/>, respectively、。Is a state matrix,For low-orbit navigation satellite pair Beidou satelliteObserved valueConstitutive observation matrix,Is a coefficient matrix.
And step 1D-2, iterating the receiver differential code deviation and the satellite differential code deviation at each time in the steady observation period based on the related state equation and the observation equation.
Referring to an upper vertical ionospheric delay and hardware bias estimation flow chart shown in fig. 3, comprising:
(1) Estimating a value according to the state matrix at the previous time AndDetermining state matrix predictive value/>, at current momentAnd according to the estimated value/>, at the previous timeCovariance matrix corresponding to state noiseAndDetermining a predicted value/>, at a current timeAnd according to the predicted value/>, of the current momentCoefficient matrixCovariance matrix/>, corresponding to observation noiseDetermination. The formula is as follows:
；
(2) According to the state matrix predicted value of the current moment 、Observation matrixCoefficient matrixDetermining state matrix estimation value/>, at current momentAnd according to the predicted value/>, of the current momentIdentity matrix、Coefficient matrixDetermining an estimate of the current moment. The formula is as follows:
。
Alternatively to this, the method may comprise, ，，，，Observed for low-orbit satellitesThe height angle of the big Dipper satellites,Representing a diagonal matrix.
By the iterative process shown in FIG. 2, the upper vertical ionospheric delay of the low-earth satellite at each moment in the robust observation period can be obtained 、。
And step 1D-3, taking the receiver differential code deviation and the satellite differential code deviation at the appointed moment as the target receiver differential code deviation and the target satellite differential code deviation.
In one example, the last time is、As a constant that is constant at any time throughout the robust observation period. />, last momentI.e. the difference code deviation of the target receiver, the last momentThe target satellite differential code deviation is obtained.
And step 1D-4, inputting the observed value of the low-orbit navigation satellite to the Beidou satellite, the target receiver differential code deviation and the target satellite differential code deviation into an inclined ionosphere delay-down correlation model to obtain an upper vertical ionosphere delay amount corresponding to the low-orbit navigation satellite.
In one example, the last time is、And the observation value of the low-orbit navigation satellite to the Beidou satelliteWith the formula 8, the upper vertical ionospheric delay/>, of the low-orbit navigation satellite at each moment in the steady observation period is further obtained through updating and correcting。
And (II) calculating the whole-process vertical ionosphere delay based on the scale factors. The method only estimates the upper delay amount of the vertical ionosphere between the low-orbit navigation satellite and the Beidou satellite, and for the whole-process vertical ionosphere delay, the embodiment of the invention provides a whole-process vertical ionosphere delay calculation method based on a scale factor. The specific calculation method of the whole-course vertical ionosphere delay comprises the following steps of 2A to 2B:
And 2A, determining a target proportion factor value based on the electronic peak height, the height of the low-orbit navigation satellite and the elevation constant through a proportion factor expression.
The expression of the scale factor expression is shown in the following equation 12:
；
Wherein, Is the target proportion factor value,Is the base of natural logarithm,Is the height of the electron peak (value 450 km)Is the altitude of the low-orbit navigation satellite,Is the elevation constant (taking the value of 100 km).
And 2B, taking the ratio of the upper vertical ionospheric delay to the target scale factor value as the whole-course vertical ionospheric delay corresponding to the low-orbit navigation satellite.
In one example, upper vertical ionospheric delayAnd global vertical ionospheric delayThe relationship of (2) is shown in the following equation 13:
；
the global vertical ionospheric delay for the location of the low-orbit navigation satellite can be calculated by equation 13.
And thirdly, user small-scale grid Beidou ionosphere delay enhancement correction. According to the embodiment of the invention, the small-scale satellite observed by a single station is selected by considering the space geometrical relationship of tight coupling between the user and the low-orbit satellite and between the low-orbit satellite and the Beidou satellite, so that a user small-scale grid Beidou ionosphere delay enhancement correction model is established, and the user-Beidou satellite ionosphere correction precision is further improved. See specifically steps 3A-3D below:
And 3A, determining a low-orbit navigation reference satellite from the low-orbit navigation satellites based on the altitude angle corresponding to the low-orbit navigation satellites.
In one example, the low-orbit navigation satellite with the largest altitude observed by the user may be referred to as the low-orbit navigation reference satellite.
And 3B, fitting a coefficient estimation value of the vertical ionospheric correction model to other low-orbit navigation satellites except the low-orbit navigation reference satellite based on the whole-course vertical ionospheric delay difference value, the first longitude difference value and the first latitude difference value between the low-orbit navigation satellite and the low-orbit navigation reference satellite to obtain the target vertical ionospheric correction model. Wherein the first longitude difference and the first latitude difference are used to characterize a spatial geometry between the low-orbit navigation satellite and the low-orbit navigation reference satellite.
In one embodiment, in the coverage area of the low-orbit navigation satellite, the ionosphere correction of any user terminal about Beidou can be obtained by calculating the user coordinates and the low-orbit navigation satellite coordinates, and the number of the selected user terminals observing the low-orbit navigation satellite is set asWhen the user-Beidou vertical ionosphere correction model is shown in the following formula 14:
；
In the method, in the process of the invention, ForLow-orbit navigation satellite and low-orbit navigation reference satelliteIs expressed as，、Respectively corresponding to the first longitude difference value and the first latitude difference value (/ >)），、Is the coefficient to be estimated.
When the observed low-orbit navigation satellite is greater than 3, the coefficient、The estimated value calculation formula of (2) is shown in the following formula 15:
，，。
The expression of the target vertical ionospheric correction model is as follows in equation 16:
；/>
Wherein, For user terminalWith low-orbit navigation reference satelliteDifference in global vertical ionospheric delay between、Is a coefficient estimation value,For user terminalWith low-orbit navigation reference satelliteSecond longitude difference between,For user terminalWith low-orbit navigation reference satelliteA second latitude difference value therebetween.
Step 3C, inputting a second longitude difference value and a second latitude difference value between the user terminal and the low-orbit navigation reference satellite into a target vertical ionosphere correction model to obtain a whole-course vertical ionosphere delay amount difference value between the user terminal and the low-orbit navigation reference satellite; wherein the second longitude difference value and the second latitude difference value are used to characterize a spatial geometry between the user terminal and the low-orbit navigation reference satellite.
Substituting the second longitude difference and the second latitude difference between the user terminal and the low-orbit navigation reference satellite into the above formula 16 to obtain the whole-course vertical ionospheric delay difference between the user terminal and the low-orbit navigation reference satellite in the coverage area of the low-orbit navigation satellite。
And 3D, correcting the inclined ionosphere delay of the user terminal according to the whole-course vertical ionosphere delay difference between the user terminal and the low-orbit navigation reference satellite to obtain the enhanced and corrected user terminal-Beidou inclined ionosphere delay of the low-orbit navigation satellite.
In one example, the following equation 17 may be used to determine the low-orbit navigation satellite-enhanced corrected user terminal-Beidou inclined ionosphere delay amount：
；
In the method, in the process of the invention,User terminal/>, calculated by ionosphere parameters broadcasted by Beidou satelliteIs of the gradient ionosphere delay,Is the earth radius (the value is the same as the above),For ionosphere the desired altitude (value 506.7 km),The zenith angle from the user to the Beidou satellite.
According to the embodiment of the invention, based on ionospheric delay monitoring of a large number of uniformly distributed low-orbit navigation satellites 'Tian base stations', the problem of insufficient number of Beidou ground monitoring stations is effectively solved; the provided vertical ionospheric delay calculation model (namely the process shown in the first step) at the upper part of the low-orbit navigation satellite can independently estimate the two, thereby effectively reducing the correlation between the ionospheric delay and the hardware bias parameter and the influence of the hardware bias on the ionospheric delay estimation precision and improving the ionospheric delay estimation precision; the provided whole-process vertical ionospheric delay calculation model (namely the process shown in the (II)) based on the scale factors realizes ionospheric monitoring and modeling of the whole path from the ground user terminal to the Beidou satellite, considers the space geometrical distribution relation of the low-orbit navigation satellite, the Beidou satellite and the user, establishes a small-scale grid Beidou ionospheric delay enhancement correction model (namely the process shown in the (III)) of the user, and further improves the ionospheric delay correction precision of the user-Beidou satellite.
Based on the above, the following objects can be achieved by the embodiments of the present invention: firstly, in order to reduce the correlation between ionospheric delay and hardware bias parameters and improve the ionospheric delay estimation precision, a vertical ionospheric delay calculation model at the upper part of a low-orbit navigation satellite is constructed, and the model finely considers the pseudo range and carrier phase deviation caused by hardware bias errors of a Beidou satellite and a space-based receiver and independently estimates the ionospheric delay and the hardware bias; secondly, aiming at the problem that the low-orbit navigation satellite cannot monitor and calculate the whole thin layer (whole path) of the ionosphere, in order to realize calculation of the whole vertical ionosphere delay, the embodiment of the invention provides a whole vertical ionosphere delay calculation method based on a scale factor, which not only considers the spatial variation characteristic of the ionosphere, but also considers the influence of the peak value attribute of the ionosphere, and can accurately calculate the whole vertical ionosphere delay; thirdly, in order to solve the problem that the whole-course vertical ionosphere delay correction using method and the influence of low-orbit navigation satellite, beidou satellite and user space geometrical distribution on ionosphere delay correction reliability are solved, the space geometrical relationship of tight coupling of the user-low-orbit navigation satellite and the low-orbit navigation satellite-Beidou satellite is fully considered, a Beidou ionosphere delay enhancement correction model of a small-scale grid of the user is established, and the ionosphere delay correction precision of the user-Beidou satellite is further improved.
In summary, the global limited ground monitoring station is adopted to model the Beidou ionosphere at present, so that the problem that the accuracy of ionosphere estimation and modeling is not high is highlighted, and the positioning accuracy of the Beidou satellite is affected. When the ionospheric delay is estimated by using the low-orbit navigation satellite observation information, the method for calculating the upper vertical ionospheric delay of the low-orbit navigation satellite fully considers the pseudo range and carrier phase deviation caused by the hardware bias error of the Beidou satellite and the antenna base station, reduces the high correlation influence of the ionospheric delay and the hardware bias, realizes the independent estimation of the ionospheric and the hardware bias error, and obtains the upper vertical ionospheric delay with high precision and high reliability. The vertical ionospheric delay calculated by the low-orbit navigation satellite only comprises the upper part where the low-orbit navigation satellite is located, the monitoring of the whole range of the vertical ionospheric can not be realized, and further the correction of the vertical ionospheric delay of the whole path from the ground user terminal to the Beidou satellite can not be realized. When the vertical ionosphere from the ground user terminal to the Beidou satellite is corrected, the low-orbit navigation satellite, the Beidou satellite and the space geometrical distribution of the user can bring influence to the delay correction of the user ionosphere.
On the basis of the foregoing embodiments, the embodiment of the present invention provides a low-orbit navigation satellite-enhanced beidou ionosphere delay correction device, referring to a structural schematic diagram of the low-orbit navigation satellite-enhanced beidou ionosphere delay correction device shown in fig. 4, the device mainly includes the following parts:
An upper vertical ionospheric delay calculation module 402, configured to determine an upper vertical ionospheric delay amount corresponding to the low-orbit navigation satellite based on an observation value of the low-orbit navigation satellite for the beidou satellite by using the inclined ionospheric delay descent correlation model; the inclined ionosphere delay-falling correlation model is constructed based on pseudo range and carrier phase deviation caused by hardware bias errors of Beidou satellites and space-based receivers;
The global vertical ionospheric delay calculation module 404 is configured to determine, according to a scale factor expression, a global vertical ionospheric delay amount corresponding to the low-orbit navigation satellite according to the upper vertical ionospheric delay amount; the scale factor expression is constructed based on ionosphere space change characteristics and ionosphere peak value attributes;
The ionospheric delay enhancement correction module 406 is configured to correct, through a vertical ionospheric correction model, an inclined ionospheric delay of the user terminal based on a full-course vertical ionospheric delay amount, to obtain a low-orbit navigation satellite-enhanced corrected user terminal-beidou inclined ionospheric delay amount; the vertical ionosphere correction model is constructed based on the space geometrical relationship of the tight coupling of the user terminal, the low-orbit navigation satellite and the Beidou satellite.
According to the Beidou ionosphere delay correction device based on low-orbit navigation satellite augmentation, which is provided by the embodiment of the invention, the ionosphere delay of the Beidou satellites is monitored by the space-based receivers based on a large number of uniformly distributed low-orbit navigation satellites, so that the problem of insufficient number of Beidou ground monitoring stations is effectively solved; the pseudo range and carrier phase deviation caused by the hardware bias errors of the Beidou satellite and the space-based receiver are finely considered, so that the correlation between ionosphere delay and hardware bias parameters and the influence of hardware bias on the ionosphere delay estimation accuracy are effectively reduced, and the estimation accuracy of the upper vertical ionosphere delay amount is improved; in addition, the influence of the spatial variation characteristic of the ionized layer and the attribute of the peak value of the ionized layer is comprehensively considered, so that the whole-course vertical ionized layer delay amount can be accurately calculated; furthermore, the spatial geometrical distribution relation among the low-orbit navigation satellite, the Beidou satellite and the user terminal is fully considered, and the accuracy of ionosphere delay correction of the user terminal-the Beidou satellite is further improved.
In one embodiment, the method further comprises a model building module for:
constructing a low-orbit navigation-Beidou satellite observation equation, and carrying out differential combination on the low-orbit navigation-Beidou satellite observation equation to form a low-orbit navigation-Beidou differential combination observation equation;
based on a low-orbit navigation-Beidou satellite observation equation and a low-orbit navigation-Beidou differential combination observation equation, constructing an electronic total content calculation equation on an observation path; and in a steady observation time period, adding and averaging the low-rail navigation-Beidou differential combination observation equation;
Substituting the low-orbit navigation-Beidou differential combination observation equation after the addition and averaging treatment into an electronic total content calculation equation on an observation path to obtain the inclined ionosphere delay-descent correlation model.
In one embodiment, the expression of the tilted ionospheric delay-down correlation model is as follows:
；
；
Wherein, For low-orbit navigation satellite pairObserved value of Beidou satelliteIs a frequency coefficient,For the upper vertical ionospheric delay amount corresponding to a low-orbit navigation satellite,Differential code deviation for receiver corresponding to space-based receiver,For satellite differential code deviation corresponding to low-orbit navigation satellite,Is an intermediate parameter,Is the earth radius,Is ionosphere equivalent height,For low orbit navigation satellite altitude,For low-orbit navigation satellite pairZenith angles of the Beidou satellites.
In one embodiment, the upper vertical ionospheric delay calculation module 402 is further configured to:
Constructing a related state equation and an observation equation;
Based on the relevant state equation and the observation equation, iterating the receiver differential code deviation and the satellite differential code deviation at each time in the steady observation period;
taking the receiver differential code deviation and the satellite differential code deviation at the designated moment as the target receiver differential code deviation and the target satellite differential code deviation;
And inputting the observed value of the low-orbit navigation satellite to the Beidou satellite, the differential code deviation of the target receiver and the differential code deviation of the target satellite into an inclined ionosphere delay-down correlation model to obtain the upper vertical ionosphere delay quantity corresponding to the low-orbit navigation satellite.
In one embodiment, the global vertical ionospheric delay calculation module 404 is further configured to:
Determining a target scale factor value based on the electronic peak height, the height of the low-orbit navigation satellite and the elevation constant through a scale factor expression;
Taking the ratio of the upper vertical ionospheric delay to the target scale factor value as the whole-course vertical ionospheric delay corresponding to the low-orbit navigation satellite;
the expression of the scale factor expression is as follows:
；
Wherein, Is the target proportion factor value,Is the base of natural logarithm,Is the electron peak height,Is the altitude of the low-orbit navigation satellite,Is an elevation constant.
In one embodiment, the number of low-orbit navigation satellites is a plurality; the ionospheric delay enhancement correction module 406 is also operative to:
Determining a low-orbit navigation reference satellite from the low-orbit navigation satellites based on the altitude corresponding to the low-orbit navigation satellites;
for other low-orbit navigation satellites except the low-orbit navigation reference satellite, fitting a coefficient estimation value of the vertical ionosphere correction model based on a whole-course vertical ionosphere delay amount difference value, a first longitude difference value and a first latitude difference value between the low-orbit navigation satellite and the low-orbit navigation reference satellite to obtain a target vertical ionosphere correction model; the first longitude difference value and the first latitude difference value are used for representing the space geometric relationship between the low-orbit navigation satellite and the low-orbit navigation reference satellite;
inputting a second longitude difference value and a second latitude difference value between the user terminal and the low-orbit navigation reference satellite into a target vertical ionosphere correction model to obtain a whole-course vertical ionosphere delay amount difference value between the user terminal and the low-orbit navigation reference satellite; the second longitude difference value and the second latitude difference value are used for representing the space geometrical relationship between the user terminal and the low-orbit navigation reference satellite;
And correcting the inclined ionosphere delay of the user terminal according to the whole-course vertical ionosphere delay difference between the user terminal and the low-orbit navigation reference satellite to obtain the enhanced and corrected user terminal-Beidou inclined ionosphere delay of the low-orbit navigation satellite.
In one embodiment, the expression for the target vertical ionospheric correction model is as follows:
；
Wherein, For user terminalWith low-orbit navigation reference satelliteDifference in global vertical ionospheric delay between、Is a coefficient estimation value,For user terminalWith low-orbit navigation reference satelliteSecond longitude difference between,For user terminalWith low-orbit navigation reference satelliteA second latitude difference value therebetween.
The device provided by the embodiment of the present invention has the same implementation principle and technical effects as those of the foregoing method embodiment, and for the sake of brevity, reference may be made to the corresponding content in the foregoing method embodiment where the device embodiment is not mentioned.
The embodiment of the invention provides electronic equipment, which comprises a processor and a storage device; the storage means has stored thereon a computer program which, when executed by the processor, performs the method of any of the embodiments described above.
Fig. 5 is a schematic structural diagram of an electronic device according to an embodiment of the present invention, where the electronic device 100 includes: a processor 50, a memory 51, a bus 52 and a communication interface 53, the processor 50, the communication interface 53 and the memory 51 being connected by the bus 52; the processor 50 is arranged to execute executable modules, such as computer programs, stored in the memory 51.
The memory 51 may include a high-speed random access memory (RAM, random Access Memory), and may further include a non-volatile memory (non-volatilememory), such as at least one magnetic disk memory. The communication connection between the system network element and at least one other network element is achieved via at least one communication interface 53 (which may be wired or wireless), and the internet, wide area network, local network, metropolitan area network, etc. may be used.
Bus 52 may be an ISA bus, a PCI bus, an EISA bus, or the like. The buses may be classified as address buses, data buses, control buses, etc. For ease of illustration, only one bi-directional arrow is shown in FIG. 5, but not only one bus or type of bus.
The memory 51 is configured to store a program, and the processor 50 executes the program after receiving an execution instruction, and the method executed by the apparatus for flow defining disclosed in any of the foregoing embodiments of the present invention may be applied to the processor 50 or implemented by the processor 50.
The processor 50 may be an integrated circuit chip having signal processing capabilities. In implementation, the steps of the above method may be performed by integrated logic circuitry in hardware in the processor 50 or by instructions in the form of software. The processor 50 may be a general-purpose processor, including a Central Processing Unit (CPU), a network processor (NetworkProcessor NP), etc.; but may also be a digital signal processor (DIGITAL SIGNAL Processing, DSP), application SPECIFIC INTEGRATED Circuit (ASIC), off-the-shelf Programmable gate array (Field-Programmable GATE ARRAY, FPGA) or other Programmable logic device, discrete gate or transistor logic device, discrete hardware components. The disclosed methods, steps, and logic blocks in the embodiments of the present invention may be implemented or performed. A general purpose processor may be a microprocessor or the processor may be any conventional processor or the like. The steps of the method disclosed in connection with the embodiments of the present invention may be embodied directly in the execution of a hardware decoding processor, or in the execution of a combination of hardware and software modules in a decoding processor. The software modules may be located in a random access memory, flash memory, read only memory, programmable read only memory, or electrically erasable programmable memory, registers, etc. as well known in the art. The storage medium is located in a memory 51 and the processor 50 reads the information in the memory 51 and in combination with its hardware performs the steps of the above method.
The computer program product of the readable storage medium provided by the embodiment of the present invention includes a computer readable storage medium storing a program code, where the program code includes instructions for executing the method described in the foregoing method embodiment, and the specific implementation may refer to the foregoing method embodiment and will not be described herein.
The functions, if implemented in the form of software functional units and sold or used as a stand-alone product, may be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention may be embodied essentially or in a part contributing to the prior art or in a part of the technical solution, in the form of a software product stored in a storage medium, comprising several instructions for causing a computer device (which may be a personal computer, a server, a network device, etc.) to perform all or part of the steps of the method according to the embodiments of the present invention. And the aforementioned storage medium includes: a usb disk, a removable hard disk, a Read-Only Memory (ROM), a random access Memory (RAM, random Access Memory), a magnetic disk, or an optical disk, or other various media capable of storing program codes.
Finally, it should be noted that: the above examples are only specific embodiments of the present invention, and are not intended to limit the scope of the present invention, but it should be understood by those skilled in the art that the present invention is not limited thereto, and that the present invention is described in detail with reference to the foregoing examples: any person skilled in the art may modify or easily conceive of the technical solution described in the foregoing embodiments, or perform equivalent substitution of some of the technical features, while remaining within the technical scope of the present disclosure; such modifications, changes or substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present invention, and are intended to be included in the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.
Claims (8)
1. The Beidou ionosphere delay correction method based on low-orbit navigation satellite augmentation is characterized by comprising the following steps of:
determining an upper vertical ionosphere delay amount corresponding to a low-orbit navigation satellite based on an observation value of the low-orbit navigation satellite to a Beidou satellite through an inclined ionosphere delay descent correlation model; the inclined ionosphere delay-falling correlation model is constructed based on pseudo-range and carrier phase deviation caused by hardware bias errors of Beidou satellites and space-based receivers;
Determining the whole-course vertical ionosphere delay amount corresponding to the low-orbit navigation satellite according to the upper vertical ionosphere delay amount through a scale factor expression; the scale factor expression is constructed based on ionosphere space change characteristics and ionosphere peak value attributes;
correcting the inclined ionosphere delay of the user terminal based on the whole-course vertical ionosphere delay amount by a vertical ionosphere correction model to obtain a Beidou inclined ionosphere delay amount of the user terminal subjected to low-orbit navigation satellite enhanced correction; the vertical ionosphere correction model is constructed based on a spatial geometrical relationship of tight coupling between a user terminal and a low-orbit navigation satellite and between a low-orbit navigation satellite and a Beidou satellite;
the construction step of the inclined ionosphere delay-down correlation model comprises the following steps:
Constructing a low-orbit navigation-Beidou satellite observation equation, and carrying out differential combination on the low-orbit navigation-Beidou satellite observation equation to form a low-orbit navigation-Beidou differential combination observation equation;
Constructing an electronic total content calculation equation on an observation path based on the low-orbit navigation-Beidou satellite observation equation and the low-orbit navigation-Beidou differential combination observation equation; and in a steady observation time period, adding and averaging the low-rail navigation-Beidou differential combination observation equation;
Substituting the low-orbit navigation-Beidou differential combination observation equation subjected to addition and averaging treatment into an electronic total content calculation equation on the observation path to obtain an inclined ionosphere delay drop correlation model;
the expression of the inclined ionospheric delay-down correlation model is as follows:
；
；
Wherein, For low-orbit navigation satellite pairObserved value of Beidou satelliteIs a frequency coefficient,For the upper vertical ionospheric delay amount corresponding to a low-orbit navigation satellite,For the receiver differential code bias corresponding to the space-based receiver,For satellite differential code deviation corresponding to low-orbit navigation satellite,Is an intermediate parameter,Is the earth radius,Is ionosphere equivalent height,For low orbit navigation satellite altitude,For low-orbit navigation satellite pairZenith angles of the Beidou satellites.
2. The method for correcting the delay of the Beidou ionosphere based on the enhancement of the low-orbit navigation satellite according to claim 1, wherein the step of determining the delay amount of the upper vertical ionosphere corresponding to the low-orbit navigation satellite based on the observation value of the low-orbit navigation satellite by tilting the ionosphere delay-down correlation model comprises the following steps:
Constructing a related state equation and an observation equation;
Based on the relative state equation and the observation equation, iterating receiver differential code deviation and satellite differential code deviation at each time in a steady observation period;
Taking the receiver differential code deviation and the satellite differential code deviation at the appointed moment as a target receiver differential code deviation and a target satellite differential code deviation;
And inputting the observed value of the low-orbit navigation satellite to the Beidou satellite, the target receiver differential code deviation and the target satellite differential code deviation into the inclined ionosphere delay-falling correlation model to obtain the upper vertical ionosphere delay quantity corresponding to the low-orbit navigation satellite.
3. The method for performing low-orbit navigation satellite based Beidou ionosphere delay correction based on low-orbit navigation satellite enhancement according to claim 1, wherein the step of determining the global vertical ionosphere delay amount corresponding to the low-orbit navigation satellite according to the upper vertical ionosphere delay amount by a scale factor expression comprises the following steps:
Determining a target scale factor value based on the electronic peak height, the height of the low-orbit navigation satellite and the elevation constant through a scale factor expression;
taking the ratio of the upper vertical ionospheric delay to the target scale factor value as the whole-course vertical ionospheric delay corresponding to the low-orbit navigation satellite;
The expression of the scale factor expression is as follows:
；
Wherein, Is the target proportion factor value,Is the base of natural logarithm,Is the electron peak height,Is the altitude of the low-orbit navigation satellite,Is an elevation constant.
4. The method for performing Beidou ionosphere delay correction based on low-orbit navigation satellite enhancement according to claim 1, wherein the number of the low-orbit navigation satellites is a plurality; correcting the inclined ionosphere delay of the user terminal based on the whole-course vertical ionosphere delay amount by a vertical ionosphere correction model to obtain a user terminal-Beidou inclined ionosphere delay amount after low-orbit navigation satellite enhancement correction, wherein the method comprises the following steps of:
determining a low-orbit navigation reference satellite from the low-orbit navigation satellites based on the altitude angles corresponding to the low-orbit navigation satellites;
For other low-orbit navigation satellites except the low-orbit navigation reference satellite, fitting a coefficient estimation value of a vertical ionospheric correction model based on a whole-course vertical ionospheric delay difference value, a first longitude difference value and a first latitude difference value between the low-orbit navigation satellite and the low-orbit navigation reference satellite to obtain a target vertical ionospheric correction model; wherein the first longitude difference value and the first latitude difference value are used to characterize a spatial geometry relationship between the low-orbit navigation satellite and the low-orbit navigation reference satellite;
Inputting a second longitude difference value and a second latitude difference value between the user terminal and the low-orbit navigation reference satellite into the target vertical ionosphere correction model to obtain a whole-course vertical ionosphere delay amount difference value between the user terminal and the low-orbit navigation reference satellite; wherein the second longitude difference value and the second latitude difference value are used to characterize a spatial geometry relationship between the user terminal and the low-orbit navigation reference satellite;
and correcting the inclined ionosphere delay of the user terminal according to the whole-course vertical ionosphere delay difference between the user terminal and the low-orbit navigation reference satellite to obtain the enhanced and corrected user terminal-Beidou inclined ionosphere delay of the low-orbit navigation satellite.
5. The low-orbit navigation satellite based enhanced beidou ionosphere delay correction method according to claim 4, wherein the expression of the target vertical ionosphere correction model is as follows:
；
Wherein, For the user terminalAnd the low-orbit navigation reference satelliteDifference in global vertical ionospheric delay between、Is a coefficient estimation value,For the user terminalAnd the low-orbit navigation reference satelliteSecond longitude difference between,For the user terminalAnd the low-orbit navigation reference satelliteA second latitude difference value therebetween.
6. Beidou ionosphere delay correction device based on low-orbit navigation satellite augmentation, and is characterized by comprising:
The upper vertical ionospheric delay calculation module is used for determining the upper vertical ionospheric delay amount corresponding to the low-orbit navigation satellite based on the observation value of the low-orbit navigation satellite to the Beidou satellite through the inclined ionospheric delay descent correlation model; the inclined ionosphere delay-falling correlation model is constructed based on pseudo-range and carrier phase deviation caused by hardware bias errors of Beidou satellites and space-based receivers;
The whole-course vertical ionosphere delay calculation module is used for determining the whole-course vertical ionosphere delay amount corresponding to the low-orbit navigation satellite according to the upper vertical ionosphere delay amount through a scale factor expression; the scale factor expression is constructed based on ionosphere space change characteristics and ionosphere peak value attributes;
The ionosphere delay enhancement correction module is used for correcting the inclined ionosphere delay of the user terminal based on the whole-course vertical ionosphere delay amount through a vertical ionosphere correction model to obtain a user terminal-Beidou inclined ionosphere delay amount after low-orbit navigation satellite enhancement correction; the vertical ionosphere correction model is constructed based on a spatial geometrical relationship of tight coupling between a user terminal and a low-orbit navigation satellite and between a low-orbit navigation satellite and a Beidou satellite;
the method also comprises a model construction module for:
Constructing a low-orbit navigation-Beidou satellite observation equation, and carrying out differential combination on the low-orbit navigation-Beidou satellite observation equation to form a low-orbit navigation-Beidou differential combination observation equation;
Constructing an electronic total content calculation equation on an observation path based on the low-orbit navigation-Beidou satellite observation equation and the low-orbit navigation-Beidou differential combination observation equation; and in a steady observation time period, adding and averaging the low-rail navigation-Beidou differential combination observation equation;
Substituting the low-orbit navigation-Beidou differential combination observation equation subjected to addition and averaging treatment into an electronic total content calculation equation on the observation path to obtain an inclined ionosphere delay drop correlation model;
the expression of the inclined ionospheric delay-down correlation model is as follows:
；
；
Wherein, For low-orbit navigation satellite pairObserved value of Beidou satelliteIs a frequency coefficient,For the upper vertical ionospheric delay amount corresponding to a low-orbit navigation satellite,For the receiver differential code bias corresponding to the space-based receiver,For satellite differential code deviation corresponding to low-orbit navigation satellite,Is an intermediate parameter,Is the earth radius,Is ionosphere equivalent height,For low orbit navigation satellite altitude,For low-orbit navigation satellite pairZenith angles of the Beidou satellites.
7. An electronic device comprising a processor and a memory, the memory storing computer-executable instructions executable by the processor, the processor executing the computer-executable instructions to implement the method of any one of claims 1 to 5.
8. A computer readable storage medium storing computer executable instructions which, when invoked and executed by a processor, cause the processor to implement the method of any one of claims 1 to 5.
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