Abstract
Precise point positioning (PPP) with ambiguity resolution (AR) can improve positioning accuracy and reliability. The narrow-lane (NL) AR solution can reach centimeter-level accuracy but there is a certain initialization time. In contrast, extra-wide-lane (EWL) or wide-lane (WL) ambiguity can be fixed instantaneously. However, due to the limited correction accuracy of the empirical atmospheric model, the positioning accuracy is only a few decimeters. In order to further improve the real-time performance of PPP while ensuring accuracy, we developed a multi-system multi-frequency uncombined PPP single-epoch EWL/WL/NL AR method with regional atmosphere modelling. In the proposed method, the precise atmosphere, including zenith wet-troposphere delay (ZWD) and the slant ionosphere, is extracted through multi-frequency stepwise AR, which then is both interpolated and broadcast to users. By adding regional atmosphere constraints, users can achieve single-epoch PPP AR with centimeter-level accuracy. To verify the algorithm, four sets of reference networks with different inter-station distances are used for experiments. With atmosphere constraints, the accuracy of the single-epoch WL solution can be improved from the decimeter level to a few centimeters, with an improvement of more than 90%, and the epoch fix rate can also be improved to varying degrees, especially for the dual-frequency case. Due to the enlarged noise of the EWL combination, its accuracy is at the decimeter level, while the accuracy of the WL/NL solution can reach several centimeters. However, reliable NL ambiguity-fixing tightly relies on atmosphere constraints with sufficiently high accuracy. When the modelling of the atmosphere correction is not accurate enough, the NL AR performance is degraded, although this situation can be improved to a certain extent through the multi-GNSS combination. In contrast, in this case, the WL ambiguity can be successfully fixed and can support the precise positioning with an accuracy of several centimeters.
Highlights
As a wide-area high-precision positioning technology, precise point positioning (PPP)has been widely used in deformation monitoring, precise timing, and other fields [1,2,3].it usually requires a long convergence time to achieve centimeter-level accuracy and leads to a poor real-time performance
Gu et al [16] and Li et al [17] extracted the EWL/WL/NL fractional cycle bias (FCB) of BeiDou Navigation Satellite System (BDS) through integer transformation and compared the ambiguity resolution (AR) performance of both the triple-frequency and dual-frequency case; the results showed that the accuracy of triple-frequency AR was higher in the initialization phase
In order to analyze the influence of regional atmosphere modelling on single-epoch PPP AR, four groups of networks were selected for experiments
Summary
As a wide-area high-precision positioning technology, precise point positioning (PPP)has been widely used in deformation monitoring, precise timing, and other fields [1,2,3].it usually requires a long convergence time to achieve centimeter-level accuracy and leads to a poor real-time performance. As a wide-area high-precision positioning technology, precise point positioning (PPP). Has been widely used in deformation monitoring, precise timing, and other fields [1,2,3]. It usually requires a long convergence time to achieve centimeter-level accuracy and leads to a poor real-time performance. Due to the strong correlation between various parameters, reliable AR requires tens of minutes [4,5]. These problems have become the bottleneck of the development of PPP technology. With the modernization of the Global Positioning System (GPS) and Global Navigation Satellite System (GLONASS), and the continuous improvement of Galileo, the BeiDou Navigation Satellite System (BDS)
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