Consistency and analysis of ionospheric observables obtained from three precise point positioning models

Xiang, Yan; Gao, Yang; Shi, Junbo; Xu, Chaoqian

doi:10.1007/s00190-019-01233-1

Cited by 24 publications

(17 citation statements)

References 20 publications

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“…It has been proven that the uncombined method is available for extracting the ionospheric observables and avoiding the effect of leveling errors [18,22,26,27]. Hence, the ionospheric observables obtained from uncombined PPP with float-ambiguity solutions are denoted as:…”

Section: Uncombined Ppp With Ambiguity Resolutionmentioning

confidence: 99%

Advantages of Uncombined Precise Point Positioning with Fixed Ambiguity Resolution for Slant Total Electron Content (STEC) and Differential Code Bias (DCB) Estimation

et al. 2020

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The determination of slant total electron content (STEC) between satellites and receivers is the first step for establishing an ionospheric model. However, the leveling errors, caused by the smoothed ambiguity solutions in the carrier-to-code leveling (CCL) method, degrade the performance of ionosphere modeling and differential code bias (DCB) estimation. To reduce the leveling errors, an uncombined and undifferenced precise point positioning (PPP) method with ambiguity resolution (AR) was used to directly extract the STEC. Firstly, the ionospheric observables were estimated with CCL, PPP float-ambiguity solutions, and PPP fixed-ambiguity solutions, respectively, to analyze the short-term temporal variation of receiver DCB in zero or short baselines. Then, the global ionospheric map (GIM) was modeled using three types of ionospheric observables based on the single-layer model (SLM) assumption. Compared with the CCL method, the slight variations of receiver DCBs can be obviously distinguished using high precise ionospheric observables, with a 58.4% and 71.2% improvement of the standard deviation (STD) for PPP float-ambiguity and fixed-ambiguity solutions, respectively. For ionosphere modeling, the 24.7% and 27.9% improvements for posteriori residuals were achieved for PPP float-ambiguity and fixed-ambiguity solutions, compared to the CCL method. The corresponding improvement for residuals of the vertical total electron contents (VTECs) compared with the Center for Orbit Determination in Europe (CODE) final GIM products in global accuracy was 9.2% and 13.7% for PPP float-ambiguity and fixed-ambiguity solutions, respectively. The results show that the PPP fixed-ambiguity solution is the best one for the GIM product modeling and satellite DCBs estimation.

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Section: Uncombined Ppp With Ambiguity Resolutionmentioning

confidence: 99%

Advantages of Uncombined Precise Point Positioning with Fixed Ambiguity Resolution for Slant Total Electron Content (STEC) and Differential Code Bias (DCB) Estimation

et al. 2020

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“…Table 1 briefly summarizes the strategies and assumptions of SLM ionospheric modeling. The ionospheric observables from the UPPP model are adopted to reduce the leveling errors when using the smoothed-code method [16,17].…”

Section: Strategies For Ionospheric Modelingmentioning

confidence: 99%

“…UPPP is the state-of-the-art method to reduce leveling errors [17]. Ionospheric observables from the two stations using the UPPP model on March 16 and 17, 2015 are shown in Figure 8.…”

Section: Ivh Impacts On Ionospheric Modelingmentioning

confidence: 99%

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An Enhanced Mapping Function with Ionospheric Varying Height

Xiang

Gao

2019

Remote Sensing

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Mapping function (MF) converts the line-of-sight slant total electron content (STEC) into the vertical total electron content (VTEC), and vice versa. In an MF, an essential parameter is the ionospheric effective height. However, the inhomogeneous ionosphere makes this height vary spatially and temporally, meaning it is not a global constant. In the paper, we review several mapping functions and propose a mapping function that utilizes the ionospheric varying height (IVH). We investigate impacts of the IVH on mapping errors and on the ionospheric modeling, as well as on the satellite and receiver differential code biases (DCBs). Our analysis results indicate that the mapping errors using IVH are smaller than those from the fixed height of 450 km. The integral height achieves smaller mapping errors than using a fixed height of 450 km, an improvement of about 8% when compared with the fixed height of 450 km. And 35% smaller mapping errors were found using HmF2 at the lower latitude. Also, the effects of IVH on the satellite DCBs are about 0.1 ns, and larger impacts on the receiver DCBs at 1.0 ns.

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“…Because the uncombined (UC) observation model is simple and unified, it has become a current focus of research. The UC model has been applied widely, such as in precision positioning (Zhang et al 2012;Li et al 2013), ionosphere modeling (Xiang et al 2019), and timing (Tu et al 2019). Many key issues, such as ambiguity resolution (AR) (Gu et al 2015;Li et al 2018), the third-frequency biases processing (Guo and Geng 2018;Pan et al 2019), and ionosphere model estimation (Zhao et al 2019), are being solved.…”

Section: Introductionmentioning

confidence: 99%

Uncombined precise orbit and clock determination of GPS and BDS-3

et al. 2020

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There is increasing concern about the uncombined (UC) observation model in the field of global navigation satellite system (GNSS). Based on the global positioning system (GPS) and the third-generation BeiDou navigation satellite system (BDS-3), this study processed the UC precision orbit determination (POD) for single and dual systems. First, a UC observation model suitable for multi-GNSS POD was derived, and the ionospheric-free (IF) combination observation model was presented. Although the ambiguity parameters of UC and IF strategies were different after reparameterization, the difference could be removed when processing ambiguity resolution, and the equivalence was proved theoretically. To demonstrate the accuracy of BDS-3 orbits fully, the observation data of approximately 1 month were selected for determining the precise orbit for global positioning system (GPS) only, BDS-3 only, and GPS/BDS-3 systems based on the UC and IF models. The orbit precision of BDS-3 satellites was validated by using metrics, including comparison with precision products released by Wuhan University, orbit boundary discontinuity, and satellite laser ranging (SLR) residuals. The results show that the orbit accuracies of the IF and UC models are almost the same, the difference in orbits is approximately several millimeters, and the clock difference is within 0.01 ns. The GPS/BDS-3 combined solution shows better accuracy compared to other solutions. The average accuracies in the R and 3D directions are approximately 4 and 15 cm, and the clock standard deviation is approximately 0.2 ns compared to external orbit product. The root mean square of SLR residuals is approximately 4 cm.

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Consistency and analysis of ionospheric observables obtained from three precise point positioning models

Cited by 24 publications

References 20 publications

Advantages of Uncombined Precise Point Positioning with Fixed Ambiguity Resolution for Slant Total Electron Content (STEC) and Differential Code Bias (DCB) Estimation

Advantages of Uncombined Precise Point Positioning with Fixed Ambiguity Resolution for Slant Total Electron Content (STEC) and Differential Code Bias (DCB) Estimation

An Enhanced Mapping Function with Ionospheric Varying Height

Uncombined precise orbit and clock determination of GPS and BDS-3

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