Single-epoch fixing method for enhancing PPP-RTK ambiguity of regional foundation

Abstract

The invention provides a single-epoch fixing method for enhancing PPP-RTK ambiguity of regional foundation. The single-epoch fixing method comprises the following steps of: improving the ambiguity convergence time of a PPP-RTK method by carrying out optimizing ordering on the fixing feasibility of single-difference ambiguity between alternative satellites, respectively modeling for an observed value residual error of a CA / P1 pseudo-range and observed value residual errors of L1 and L2 phase positions by adopting a single-reference station processing mode based on a PPP-RTK technique, and realizing the single-epoch fixing of combined ambiguity of an ionization-free layer through step-by-step solving of the ambiguity in consideration of a linear constraint relationship between the high precision of a pseudo-range observed value, long wavelength of a wide-lane observed value, wide-lane ambiguity and L1 ambiguity after a user refines the models, thus the determination time of the PPP ambiguity is minimized, and the working efficiency of precisely locating the user is improved to the maximum degree.

Description

technical field [0001] The invention belongs to the field of global navigation systems, and relates to a precision point positioning (PPP) ambiguity fixing technology, in particular to a regional ground-enhanced PPP-RTK ambiguity single-epoch fixing method. Background technique [0002] The ambiguity and single epoch determination of precise single point positioning based on the regional ground-based augmentation network is a research hotspot and difficult problem in satellite navigation and positioning technology. "Network RTK method based on non-difference observation" proposed by Ge et al. [1] And the "CORS network-based PPP-RTK method" proposed by Teunissen and other scholars [2] provides feasibility to achieve this goal, however existing methods only model the residuals of carrier phase undifferenced observations at the reference station, since this information not only includes ionospheric delays, but also unmodeled tropospheric Delay, satellite orbit, satellite cloc...

AI Technical Summary

Problems solved by technology

"Network RTK method based on non-difference observation" proposed by Ge et al. [1] And the "CORS network-based PPP-RTK method" proposed by Teunissen and other scholars [2] provides feasibility to achieve this goal, however existing methods only model the residuals of carrier phase undifferenced observations at the reference station, since this information not only includes ionospheric delays, but also unmodeled tropospheric Delay, satellite orbit, satellite clock error and other errors, and the original pseudo-range ionosphere-free combination observation value (PC) can only eliminate the ionospheric delay effect, so the carrier phase observation value after the user's model correction is the same as the original PC pseudo-range There are inconsistencies in the residual errors contained in

This inconsistency is equivalent to adding a set of systematic deviations to the pseudorange observations, which affects the convergence speed and reliability of the carrier phase ambiguity solution

[0003] In addition, according to the "regional ground-based augmentation information single reference station modeling method" proposed by Li et al. [3] When , since the zenith tropospheric delay of the reference station requires long-term continuous observations to obtain a relatively stable estimate, the residual error Δztd of the zenith tropospheric delay will be converted into a delay error in the direction of the oblique path through the tropospheric delay mapping function, which will affect the precision Ionospheric combination ambiguity N for single point positioning IF The estimation accuracy of , which in turn leads to N IF and wide-lane ambiguity (N WL ) back-calculated L1 ambiguity (N L1 ) Deviation (ΔN IF ), or even calculation errors (as shown in formulas (a), (b), where f L1 , f L2 is the frequency of L1, L2 observations), and eventually leads to the generation of wrong regional ground-based enhancement information

Therefore, according to the PPP-RTK method, in order to ensure the reliability of the undifferenced ambiguity fixation results at the reference station, it is difficult to achieve rapid initialization of the ground-based augmentation system in the entire region

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