Disclosure of Invention
The invention aims to provide a satellite-based foundation enhanced integrated non-differential GNSS real-time PNT method and device, which are used for solving the problem that in the prior art, only a single error correction product is used for assisting a GNSS system in positioning and has limitation, so as to meet the positioning requirements of users in different scenes.
In order to achieve the aim of the invention, the invention adopts the following technical scheme:
The invention provides a satellite-based foundation enhanced integrated non-differential GNSS real-time PNT method, which comprises the following steps:
s100, acquiring a configuration file and an available external correction product; wherein the external correction product comprises a DCB product and an OSB product;
s200, selecting to enter a phase-dominant/code-only positioning mode according to the configuration file;
s300, obtaining a double-frequency phase and pseudo-range IF combination/single-frequency pseudo-range observation value according to the configuration file and the phase and pseudo-range/pseudo-range observation value of the corresponding frequency point; ;
S400, acquiring an available GNSS positioning error real-time correction product; the GNSS positioning error real-time correction product comprises a real-time precision product, a satellite-based enhanced product, a foundation enhanced product and broadcast ephemeris;
S500, correcting the positioning error of the GNSS according to the available external correction product, the double-frequency phase and pseudo-range IF combination/single-frequency pseudo-range observation value and the available GNSS positioning error real-time correction product so as to jointly enhance the positioning of the GNSS into a planet foundation; the positioning error of the GNSS comprises satellite orbit and clock error, atmospheric delay and satellite pseudo-range end hardware delay, wherein the atmospheric delay comprises troposphere delay and ionosphere delay.
Optionally, step S200 specifically includes:
S210, judging whether to use a phase observation value according to the configuration file;
s220, if yes, selecting to enter a phase-dominant positioning mode;
s230, if not, selecting to enter a code-only positioning mode.
Optionally, step S500 specifically includes:
s510, judging whether the available GNSS positioning error real-time correction product comprises a real-time precise product or not;
S511, if yes, correcting satellite orbit and clock error through the real-time precise product;
S512, if not, judging whether the available GNSS positioning error real-time correction product comprises a star-based enhanced product or not;
S513, if yes; correcting satellite orbit and clock error through the satellite-based enhanced product;
s514, if not, correcting satellite orbit and clock error through broadcast ephemeris;
s520, eliminating satellite pseudo-range end hardware delay according to the DCB product.
Optionally, after step S520, the method further includes:
s530, judging whether the available GNSS positioning error real-time correction product comprises a foundation enhancement product;
S531, IF yes, the foundation enhancement product is used for calculating to obtain and weaken troposphere delay, ionosphere delay is eliminated through the double-frequency phase and pseudo-range IF combined observation value, and the current epoch receiver coordinate is calculated through an EKF algorithm;
S532, IF not, calculating a dry delay part in the troposphere by using a Saastamoinen model, estimating a wet delay part in the troposphere as an unknown parameter, eliminating ionosphere delay by combining the observation values of the double-frequency phase and the pseudo-range IF, and calculating the current epoch receiver coordinates by using an EKF algorithm.
Optionally, step S531 specifically includes:
S5311, if so, calculating by using the foundation enhancement product to obtain and weaken troposphere delay;
S5312, eliminating ionospheric delay through the combined observation value of the double-frequency phase and the pseudo-range IF to obtain a function model I;
S5313, based on the function model I, taking the receiver coordinates as constant estimation, taking the receiver clock error as white noise estimation, taking the ambiguity as constant estimation, and calculating the current epoch receiver coordinates by using an EKF algorithm;
wherein, the first functional model is:
Wherein,S and r are the satellite and the receiver, respectively; Unit vectors for satellite to receiver; xr is the receiver three-dimensional position increment relative to the initial coordinates; receiver clock correction to account for pseudorange receiver end hardware delays; AndPseudo-range and phase observation values after double-frequency IF combination are respectively obtained; And dPseudo-range observed value/phase observed value-calculated value after IF combination; ambiguity parameters for accounting for phase receiver and satellite side hardware delays; AndPseudo-range and phase observation noise, respectively; tr is the receiver; ζr,IF and ζr,IF are receiver-side hardware delays in pseudo-range and phase, respectively; ζs,IF and ζs,IF are satellite side hardware delays in pseudorange and phase, respectively.
Optionally, step S532 specifically includes:
S5321, if not, calculating a dry delay part in the troposphere by using a Saastamoinen model, and estimating a wet delay part in the troposphere as an unknown parameter;
S5322, eliminating ionospheric delay through the combined observation value of the dual-frequency phase and the pseudo-range IF to obtain a function model II;
S5323, based on the function model II, using wet delay as random walk estimation, using receiver coordinates as constant estimation, using receiver clock difference as white noise estimation, using ambiguity as constant estimation, and using an EKF algorithm to calculate current epoch receiver coordinates;
the second function model is:
Wherein,The zenith delay ZTD is the troposphere; is a ZTD mapping function.
Optionally, after step S511, the method further includes:
S5111, judging whether the available external correction products comprise OSB products or not;
and S5112, if so, fixing the ambiguity by the OSB product.
Optionally, after step S520, the method further includes:
S540, judging whether the available GNSS positioning error real-time correction product comprises a foundation enhancement product or not;
S541, if yes, calculating and weakening atmospheric delay by using the foundation enhancement product according to the single-frequency pseudo-range observation value;
S542, if not, correcting troposphere delay by using a Saastamoinen model, correcting ionosphere delay by using a Klobuchar model, and calculating the current epoch receiver coordinate based on LS principle.
Optionally, step S542 specifically includes:
S5421, if not, correcting tropospheric delay by using a Saastamoinen model, and correcting ionospheric delay by using a Klobuchar model to obtain a function model III;
s5422, based on the function model III, estimating the three-dimensional coordinate and the clock difference of the receiver as unknown parameters, and calculating the coordinate of the receiver of the current epoch based on the LS principle;
the function model III is as follows:
Wherein,Xir,i is the receiver-side hardware delay on the pseudorange; For pseudorange observations-calculations on frequency i; noise is the pseudorange observations.
In a second aspect of the embodiments of the present invention, there is also provided a satellite-based foundation-enhanced integrated non-differential GNSS real-time PNT device, including:
The first acquisition module is used for acquiring the configuration file and the available external correction products; wherein the external correction product comprises a DCB product and an OSB product;
the mode selection module is used for selecting to enter a phase-dominant/code-only positioning mode according to the configuration file;
The observation value acquisition module is used for acquiring a double-frequency phase and pseudo-range IF combination/single-frequency pseudo-range observation value according to the configuration file and the phase and pseudo-range/pseudo-range observation value of the corresponding frequency point;
The second acquisition module is used for correcting the product in real time by the available GNSS positioning error; the GNSS positioning error real-time correction product comprises a real-time precision product, a satellite-based enhanced product, a foundation enhanced product and broadcast ephemeris;
The correction enhancing module is used for correcting the positioning error of the GNSS according to the available external correction product, the double-frequency phase and pseudo-range IF combination/single-frequency pseudo-range observation value and the available GNSS positioning error real-time correction product so as to enhance the combination of the GNSS positioning into the planet foundation; the positioning error of the GNSS comprises satellite orbit and clock error, atmospheric delay and satellite pseudo-range end hardware delay, wherein the atmospheric delay comprises troposphere delay and ionosphere delay.
The invention has the following beneficial effects: the satellite-based foundation enhancement integrated non-differential GNSS real-time PNT method comprehensively utilizes various error correction products, including broadcast ephemeris, real-time precision products, satellite-based enhancement products and foundation enhancement products, flexibly selects different positioning modes according to user requirements and acquired product data based on phase observation values or pseudo-range observation values, provides more accurate and reliable positioning results, meets various positioning requirements of users in different scenes, and overcomes the problems of the prior art, such as low positioning precision and single product use.
Detailed Description
The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to fig. 1-2 of the embodiments of the present invention, and it is obvious that the described embodiments are only some embodiments of the present invention, but not all embodiments. The technical means used in the examples are conventional means well known to those skilled in the art unless otherwise indicated.
In addition, the embodiments of the present invention and the features of the embodiments may be combined with each other without collision.
It should be noted that: like reference numerals and letters denote like items in the following figures, and thus once an item is defined in one figure, no further definition or explanation thereof is necessary in the following figures.
The following description will be given of a satellite-based foundation-enhanced integrated non-differential GNSS real-time PNT method applied in the implementation of the technology of the application:
Referring to fig. 1, fig. 1 is a flow chart of a satellite-based foundation enhancement integrated non-differential GNSS real-time PNT method according to an embodiment of the present application, the method includes the following steps:
s100, acquiring a configuration file and an available external correction product; wherein the external correction product comprises a DCB product and an OSB product;
PNT is an acronym for Positioning, navigation and Timing.
The DCB is a differential code Bias (DIFFERENTIAL CODE BIAS, DCB), and the OSB is a signal Bias (Observable-SPECIFIC SIGNAL Bias, OSB).
S200, selecting to enter a phase-dominant/code-only positioning mode according to the configuration file;
It should be noted that the satellite-based foundation enhancement integrated non-differential GNSS real-time PNT method provided by the application provides a positioning method based on a phase observation value and/or a pseudo-range observation value respectively.
The phase-dominant positioning mode is a positioning mode dominated by phase observation values, and the code-only positioning mode is a positioning mode based on pseudo-range observation values.
Technical solutions based on phase observations are typically used for locating application scenarios with high accuracy. The phase observation value has higher precision and stability, and the observation precision can reach 0.1mm. The phase observations are mainly used in phase-dominant phase-dominant positioning modes, such as precision single point positioning (Precise Point Positioning, PPP), which generally require precision or other external correction products to correct satellite orbits and clock errors to improve positioning accuracy. The phase-dominant positioning mode is suitable for applications requiring high-precision positioning, such as mapping, geological exploration, precision agriculture and the like.
Technical solutions based on pseudo-range observations are commonly used in common positioning application scenarios. Pseudorange observations have a large measurement range and low accuracy requirements and are susceptible to multipath effects and interference. Code-only positioning modes based on pseudorange observations typically employ single frequency observations for positioning, such as single point positioning (Single Point Positioning, SPP), which typically use empirical models to correct for atmospheric delays, and external correction products to correct for satellite orbit, clock errors, and pseudorange-side hardware delays. The code-only positioning mode is suitable for general positioning requirements, such as navigation, vehicle positioning, smart phone positioning and the like.
In practical application, a phase-dominant positioning mode is used to obtain higher positioning precision, so that the method is suitable for application scenes with higher precision requirements. And the code-only positioning mode can be used for realizing simpler and economical positioning, and is suitable for application scenes with relatively low requirements on precision. The specific choice of which scheme depends on the accuracy requirements of the application scenario and the available observation data and correction products.
S300, obtaining a double-frequency phase and pseudo-range IF combination/single-frequency pseudo-range observation value according to the configuration file and the phase and pseudo-range/pseudo-range observation value of the corresponding frequency point;
the above-mentioned dual-frequency phase and pseudo-range IF combined observed value is the ionosphere-free (Ionosphere Free, IF) combined observed value of the phase observed value and pseudo-range observed value.
Correspondingly, the phase-dominant positioning mode uses a phase observation value with phase dominant and a pseudo-range observation value to obtain a double-frequency phase and pseudo-range IF combined observation value; the code-only positioning mode obtains single frequency pseudorange observations using only pseudorange observations.
S400, acquiring an available GNSS positioning error real-time correction product; the GNSS positioning error real-time correction product comprises a real-time precision product, a satellite-based enhanced product, a foundation enhanced product and broadcast ephemeris;
Real-time precision products include precision ephemeris and precision clock-difference products. Star-based enhanced products include PPP products and star-based enhanced (SATELLITE BASED AUGMENTATION SYSTEM, SBAS) products.
S500, correcting the positioning error of the GNSS according to the available external correction product, the double-frequency phase and pseudo-range IF combination/single-frequency pseudo-range observation value and the available GNSS positioning error real-time correction product so as to jointly enhance the positioning of the GNSS into a planet foundation; the positioning error of the GNSS comprises satellite orbit and clock error, atmospheric delay and satellite pseudo-range end hardware delay, wherein the atmospheric delay comprises troposphere delay and ionosphere delay.
The satellite-based foundation enhancement integrated non-differential GNSS real-time PNT method comprehensively utilizes various error correction products, including broadcast ephemeris, real-time precision products, satellite-based enhancement products and foundation enhancement products, flexibly selects different positioning modes according to user requirements and acquired product data based on phase observation values or pseudo-range observation values, provides more accurate and reliable positioning results, meets various positioning requirements of users in different scenes, and overcomes the problems of the prior art, such as low positioning precision and single product use.
The following describes different positioning modes in different scenarios provided in this embodiment, and reference is made to fig. 2.
Further, step S200 specifically includes:
S210, judging whether to use a phase observation value according to the configuration file;
s220, if yes, selecting to enter a phase-dominant positioning mode;
s230, if not, selecting to enter a code-only positioning mode.
In one embodiment, step S500 includes:
s510, judging whether the available GNSS positioning error real-time correction product comprises a real-time precise product or not;
S511, if yes, correcting satellite orbit and clock error through the real-time precise product;
S512, if not, judging whether the available GNSS positioning error real-time correction product comprises a star-based enhanced product or not;
S513, if yes; correcting satellite orbit and clock error through the satellite-based enhanced product;
s514, if not, correcting satellite orbit and clock error through broadcast ephemeris;
s520, eliminating satellite pseudo-range end hardware delay according to the DCB product.
After step S520, the method steps of the different positioning modes are different, and the phase-dominant positioning mode method is described as follows:
further, after step S520, the method further includes:
s530, judging whether the available GNSS positioning error real-time correction product comprises a foundation enhancement product;
S531, IF yes, the foundation enhancement product is used for calculating to obtain and weaken troposphere delay, ionosphere delay is eliminated through the double-frequency phase and pseudo-range IF combined observation value, and the current epoch receiver coordinate is calculated through an EKF algorithm;
S532, IF not, calculating a dry delay part in the troposphere by using a Saastamoinen model, estimating a wet delay part in the troposphere as an unknown parameter, eliminating ionosphere delay by combining the observation values of the double-frequency phase and the pseudo-range IF, and calculating the current epoch receiver coordinates by using an EKF algorithm.
Real-time correction products fall into two categories, the first for correcting satellite orbit and clock error, including real-time precision products, satellite-based augmentation products, and broadcast ephemeris. The second category is for correcting atmospheric errors, including foundation enhancement products. Both types of products have respective use priorities, and in addition, both types of products have use priorities, namely, the first type is used first and then the second type is used.
The first type of correction products are real-time precision products, star-based enhanced products and broadcast ephemeris in sequence from large to small.
The method for correcting the atmospheric error includes parameterization, an empirical model, and an observation value combination in addition to the foundation enhancement product provided in the present embodiment. For example, parameterization is for tropospheric delay in phase-dominant positioning mode, empirical model is for tropospheric and ionospheric delay in code-only positioning mode, and observation combination is for ionospheric delay in phase-dominant mode.
The Saastamoinen model describes the characteristics and propagation effects of troposphere in terms of factors such as air temperature, pressure, water vapor condensate, etc. As an empirical model, it is mainly used to correct tropospheric delay.
The EKF algorithm is an Extended kalman filter (Extended KALMAN FILTER, EKF) algorithm.
Further, step S531 specifically includes:
S5311, if so, calculating by using the foundation enhancement product to obtain and weaken troposphere delay;
S5312, eliminating ionospheric delay through the combined observation value of the double-frequency phase and the pseudo-range IF to obtain a function model I;
S5313, according to the function model I, taking the receiver coordinates as constant estimation, taking the receiver clock error as white noise estimation, taking the ambiguity as constant estimation, and calculating the current epoch receiver coordinates by using an EKF algorithm;
wherein, after correcting the tropospheric delay, satellite orbit and clock error, the obtained functional model I is:
Wherein,S and r are the satellite and the receiver, respectively; Unit vectors for satellite to receiver; xr is the receiver three-dimensional position increment relative to the initial coordinates; receiver clock correction to account for pseudorange receiver end hardware delays; AndPseudo-range and phase observation values after double-frequency IF combination are respectively obtained; And dPseudo-range observed value/phase observed value-calculated value after IF combination; ambiguity parameters for accounting for phase receiver and satellite side hardware delays; AndPseudo-range and phase observation noise, respectively; tr is the receiver; ζr,IF and ζr,IF are receiver-side hardware delays in pseudo-range and phase, respectively; ζs,IF and ζs,IF are satellite side hardware delays in pseudorange and phase, respectively.
Step S532 specifically includes:
S5321, if not, calculating a dry delay part in the troposphere by using a Saastamoinen model, and estimating a wet delay part in the troposphere as an unknown parameter;
s5322, eliminating ionospheric delay through the combined observation value of the double-frequency phase and the pseudo-range IF to obtain a function model II;
S5323, based on the function model II, using wet delay as random walk estimation, using receiver coordinates as constant estimation, using receiver clock difference as white noise estimation, using ambiguity as constant estimation, and using an EKF algorithm to calculate current epoch receiver coordinates;
After the troposphere dry delay, satellite orbit and clock error are corrected, the obtained function model II is:
Wherein,The zenith delay ZTD is the troposphere; is a ZTD mapping function.
Further, after step S511, the method further includes:
Step S5111, judging whether the available external correction product comprises an OSB product;
and step 5112, if yes, fixing the ambiguity by the OSB product.
That is, if the satellite orbit and clock error is corrected by real-time precision products, the OSB products can be used to fix the ambiguity.
The code-only positioning mode method after step S520 is described below:
after step S520, the method further includes:
S540, judging whether the available GNSS positioning error real-time correction product comprises a foundation enhancement product or not;
S541, if yes, calculating and weakening atmospheric delay by using the foundation enhancement product according to the single-frequency pseudo-range observation value;
S542, if not, correcting troposphere delay by using a Saastamoinen model, correcting ionosphere delay by using a Klobuchar model, and calculating the current epoch receiver coordinate based on LS principle.
The step S542 specifically includes:
S5421, if not, correcting tropospheric delay by using a Saastamoinen model, and correcting ionospheric delay by using a Klobuchar model to obtain a function model III;
s5422, based on the function model III, estimating the three-dimensional coordinate and the clock difference of the receiver as unknown parameters, and calculating the coordinate of the receiver of the current epoch based on the LS principle;
the function model III is as follows:
Wherein,Xir,i is the receiver-side hardware delay on the pseudorange; For pseudorange observations-calculations on frequency i; noise is the pseudorange observations.
The Klobuchar model is an empirical model for attenuating ionospheric delay. It uses a single layer ionosphere model, calculated using ionosphere parameters in the broadcast ephemeris, to attenuate the ionosphere delay.
The Least Square (LS) principle is a Least squares principle for parameter estimation. In the positioning process, the LS principle can be used for estimating unknown parameters such as three-dimensional coordinates and clock errors of a receiver, and the principle obtains an optimal solution through iterative calculation by minimizing the sum of squares of residual errors between an observed value and a model calculated value.
For ease of understanding, the embodiments provided above are incorporated and fully described below:
in a first aspect, the present invention provides a satellite-based foundation-enhanced integrated non-differential GNSS real-time PNT method based on phase observations, as shown in the left part of fig. 2.
Conventional phase-dominated positioning modes, such as PPP mode, typically use IF combining for positioning. The function model of the method is that,
Wherein,Is the distance of the satellite to the receiver; tr and ts are receiver and satellite clock differences, respectively; Is a diagonal tropospheric delay; the unit is m, which is the ambiguity parameter.
However, the above formula cannot be directly solved because of the problem of rank deficiency, so that an external correction product and a real-time correction product for GNSS positioning errors are needed to correct satellite orbit errors, clock error and pseudo-range satellite end hardware delay. External correction products include DCB products and OSB products, GNSS positioning error real-time correction products include real-time precision products (precision ephemeris and precision clock error products), satellite based augmentation products (PPP products and SBAS products), ground based augmentation products, and broadcast ephemeris. The pseudo-range satellite end hardware delay is corrected by mainly using the DCB product. After correcting satellite orbit, clock error and pseudo-range satellite end hardware delay, EKF can be used for positioning calculation. Meanwhile, the foundation reinforcement product can better eliminate the atmospheric delay, so that the positioning precision is improved, and the convergence time is shortened. Therefore, the satellite-based foundation enhancement integrated non-differential GNSS real-time PNT method based on the phase observation value provided by the embodiment of the invention comprises the following steps:
Based on the obtained external correction product and the GNSS positioning error, the method comprises the following steps: firstly, judging whether a real-time precise product can be received, and if the real-time precise product can be received, entering a step 1.1; secondly, if no real-time precise product exists, judging whether a star-based enhanced product can be obtained, and if yes, entering a step 1.2; and finally, if the star-based enhanced product is not available, entering a step 1.3.
1.1 If the user can obtain the real-time precise product, the satellite orbit and clock error can be eliminated according to the real-time precise product. Judging whether a foundation enhancement product can be obtained or not, if so, calculating to obtain atmospheric delay by using the foundation enhancement product, eliminating the influence on troposphere delay, and calculating the coordinates of the current epoch receiver according to the EKF by using a function model I so as to form a PPP-RTK positioning mode; if the user can not obtain the foundation enhancement product, the function model II can be utilized to estimate the troposphere delay as an unknown parameter so as to form a PPP mode, and meanwhile, if the user can obtain the OSB product, the ambiguity fixing can be carried out so as to form a PPP-AR mode.
The PPP positioning mode is used for correcting satellite orbit errors and clock errors by receiving signals of a plurality of satellites and utilizing precise satellite orbit and clock error products, so that high-precision measurement of the position of the receiver is realized. Compared with the traditional differential positioning technology, PPP does not need an extra differential data source, and can provide high-precision position information on the global scale. The method is widely applied to the fields of precision mapping, geodetic survey, navigation, positioning and the like. The ambiguity parameters in PPP couple phase-side satellite hardware delays, resulting in ambiguity losing integer character, so the ambiguity in PPP is a floating solution. If an external product, such as an OSB product, is available, the integer nature of the ambiguity can be restored, thereby fixing the ambiguity and forming a PPP-AR (Ambiguity Resolution) mode.
The PPP-RTK positioning mode is a combined positioning mode based on PPP-AR technology and atmospheric correction. PPP-RTK can realize high-accuracy three-dimensional position calculation, is usually used in fields such as aviation, navigation, geographical mapping, etc.
1.2 If the user only gets the satellite based augmentation product, the satellite based augmentation product can be utilized to eliminate the effects of satellite orbit and clock bias. IF the foundation enhancement product can be obtained at the same time, the foundation enhancement product can be used for further weakening the influence of the atmospheric delay, in particular the tropospheric delay, and the ionospheric delay is eliminated by the double-frequency phase IF combination. After correction of tropospheric delay, satellite orbit and clock bias, the model is changed to a functional model one. The receiver coordinates are then resolved from the EKF to form a star-based enhanced PPP-RTK mode, i.e., (SBA-PPP-RTK) mode. If the foundation enhancement product cannot be obtained, the method is in a star-based enhanced PPP mode, namely (SBA-PPP) mode, a Saastamoinen model is utilized to calculate a dry delay part in a troposphere, and the wet delay part is used as an unknown parameter to estimate. Ionospheric delays are eliminated by double-frequency pseudo-range IF combining. After correction of tropospheric dry delay, satellite orbit and clock bias, the first functional model is changed to the second functional model.
1.3 If the user can not obtain real-time precise products and satellite-based enhanced products, the satellite orbit and clock error can be obtained by using broadcast ephemeris calculation. If the user cannot acquire the foundation enhancement product, the troposphere delay can only be used as a parameter to estimate, and the function model II is utilized to calculate according to the EKF, so that an efficient PPP mode, namely a EFFICIENT PPP, EPPP mode is formed; if the user can obtain the foundation enhancement product, the tropospheric delay can be better eliminated, and the first functional model is utilized to perform a solution according to the EKF, so as to form a EPPP mode of foundation enhancement, namely (GBA-EPPP) mode.
The SBA and GBA are respectively: (Satellite-Based Augmentation, SBA) Satellite-based augmentation; (group-Based Augmentation, GBA) foundation enhancement
In a second aspect, the present invention provides a satellite-based foundation-enhanced integrated non-differential GNSS real-time PNT method based on pseudorange observations, as shown in the right part of fig. 2.
IF combining amplifies the observations and the pseudorange observations are noisy, so pseudorange-based positioning modes, such as SPP mode, typically use single frequency observations for positioning. The function model is typically:
Wherein,Is the ionospheric delay on the ith frequency.
Similarly, because of the rank deficiency problem, the satellite orbit, clock bias and pseudo-range satellite end hardware delay need to be corrected by using an external correction product. Meanwhile, because the pseudo-range function model has fewer redundant observations, the troposphere and ionosphere delays are difficult to parameterize. Therefore, in order to improve the robustness of the model, an empirical model is often used to correct the atmospheric delay in the calculation process, but the model calculation result has lower accuracy. Therefore, the implementation of the invention provides a satellite-based foundation enhancement integrated non-differential GNSS real-time PNT method based on pseudo-range observation values, which comprises the following steps:
As above, according to the acquired real-time satellite orbit and clock error products, the following steps are entered: firstly, if the precise ephemeris product can be received, entering step 2.1; secondly, if no real-time precise product exists but a star-based enhanced product exists, the step 2.2 is carried out; and finally, if the star-based enhanced product is not available, entering a step 2.3.
2.1 If the user can obtain the real-time precise product, the satellite orbit and clock error can be eliminated according to the real-time precise product. If the user cannot obtain the foundation enhancement product, the Saastamoinen model can only be used for calculating the troposphere delay value, the Klobuchar model can be used for calculating the ionosphere delay value, and after the atmospheric delay, the satellite orbit and the clock difference are corrected, the function model can be changed into a function model III. The LS principle then solves to obtain receiver coordinates to form a high accuracy SPP (PRECISE SPP, PSPP) mode. If the user can obtain the foundation enhancement product, the atmospheric delay can be weakened better, so that the positioning precision is improved, and a PSPP (PSPP-RTK) mode of foundation enhancement is formed.
The PSPP mode is a high-precision single point positioning (PRECISE SINGLE Point Positioning) mode based on real-time precision products.
The PSPP-RTK mode is a PSPP mode for foundation reinforcement based on real-time precision products and foundation reinforcement products.
2.2 If the user only gets the satellite based augmentation product, the satellite based augmentation product can be used to eliminate the effects of satellite orbit and clock bias. If the foundation enhancement product cannot be obtained, the model is used for correcting the atmospheric delay, which is a satellite-based enhancement (SBAS) mode. If a foundation enhancement product is available, the effect of atmospheric delays can be further attenuated, thereby forming a satellite-based foundation synergistic enhancement (SBA-RTK) mode.
The SBA-RTK mode is a mode of satellite-based foundation collaborative enhancement based on a satellite-based enhanced product and a foundation enhanced product.
2.3 If the user can not obtain the real-time precise product and the satellite-based enhanced product, the satellite orbit and the clock error can be obtained by using the broadcast ephemeris calculation. If the user cannot acquire the foundation enhancement product, correcting the atmospheric delay by using an empirical model, and entering an SPP mode; if the user can obtain the foundation enhancement product, the atmosphere delay is corrected by using the foundation enhancement product, so that the foundation enhancement (GBAS) mode is entered.
The GBAS mode is a foundation enhancement (group-Based Augmentation System) mode based on the SPP mode, which uses foundation enhancement products to correct the atmosphere.
In a third aspect, the implementation of the present invention can meet various user needs of users in different scenes, including:
Different product data can be obtained by the user under different scenes. If the user is in a non-network condition, the user can receive the satellite-based augmentation correction and broadcast ephemeris data from the GEO satellite broadcast. Based on this, the user may choose to enter steps 1.2 and 1.3 or 2.2 and 2.3, operate SBAS-PPP and EPPP or SBAS and SPP modes based on the phase or pseudorange observations.
If the user is in the network condition, the user can receive the satellite-based enhanced product and the broadcast ephemeris, and can acquire the real-time precise product and the foundation enhanced product, and the user can freely select to enter various modes according to the acquired observation value and various product information and the first aspect and the second aspect.
In summary, the satellite-based foundation enhancement integrated non-differential GNSS real-time PNT method comprehensively utilizes various error correction products, including broadcast ephemeris, real-time precision products, satellite-based enhancement products and foundation enhancement products, flexibly selects different positioning modes according to user requirements and acquired product data based on phase observation values or pseudo-range observation values, provides more accurate and reliable positioning results, meets various positioning requirements of users in different scenes, and overcomes the problems of the prior art, such as low positioning precision and the shortages of an atmospheric delay weakening method.
Based on the same inventive concept, referring to fig. 3, an embodiment of the present invention further provides a satellite-based foundation-enhanced integrated non-differential GNSS real-time PNT device 200, including:
A first obtaining module 210 for obtaining a configuration file and an available external correction product; wherein the external correction product comprises a DCB product and an OSB product;
A mode selection module 220, configured to select to enter a phase-dominant/code-only positioning mode according to the configuration file;
an observation value obtaining module 230, configured to obtain a dual-frequency phase and pseudo-range IF combination/single-frequency pseudo-range observation value according to the configuration file and the phase and pseudo-range/pseudo-range observation values of the corresponding frequency points;
a second obtaining module 240, configured to correct the available GNSS positioning error in real time; the GNSS positioning error real-time correction product comprises a real-time precision product, a satellite-based enhanced product, a foundation enhanced product and broadcast ephemeris;
The correction enhancing module 250 is configured to correct the positioning error of the GNSS according to the available external correction product, the dual-frequency phase and pseudo-range IF combination/single-frequency pseudo-range observation value, and the available GNSS positioning error real-time correction product, so as to enhance the combination of positioning the GNSS into the planetary foundation; the positioning error of the GNSS comprises satellite orbit and clock error, atmospheric delay and satellite pseudo-range end hardware delay, wherein the atmospheric delay comprises troposphere delay and ionosphere delay.
It should be understood that, corresponding to the above-mentioned satellite-based foundation enhancement integrated non-differential GNSS real-time PNT method embodiment, the apparatus can perform the steps involved in the above-mentioned method embodiment, and specific functions of the apparatus may be referred to the above description, and detailed descriptions thereof are omitted herein as appropriate to avoid redundancy. The device includes at least one software functional module that can be stored in memory in the form of software or firmware (firmware) or cured in an Operating System (OS) of the device.
The above embodiments are only illustrative of the preferred embodiments of the present invention and are not intended to limit the scope of the present invention, and various modifications, alterations, and substitutions made by those skilled in the art to the technical solution of the present invention should fall within the scope of protection defined by the claims of the present invention without departing from the spirit of the present invention.