The Multi-GNSS Experiment (MGEX) of the International GNSS Service (IGS) – Achievements, prospects and challenges

Montenbruck, Oliver; Steigenberger, Peter; Prange, Lars; Deng, Zhiguo; Zhao, Qile; Pérosanz, F.; Romero, Ignacio; Noll, Carey; Stürze, Andrea; Weber, Georg F.; Schmid, Ralf; MacLeod, Kenneth G.; Schaer, Stefan

doi:10.1016/j.asr.2017.01.011

Cited by 747 publications

(360 citation statements)

References 79 publications

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“…Results of RT orbit validation using SLR are mainly within the boundaries determined by the SLR validation of the final products obtained by Montenbruck et al (2017). The SD of SLR residuals for RT orbits is lower than for the final orbits by several millimeters for GLONASS and BeiDou IGSO, while SD for BeiDou GEO is even three times greater than the values for the final products.…”

Section: Orbit Validation Using Slrmentioning

confidence: 74%

Quality assessment of multi-GNSS orbits and clocks for real-time precise point positioning

2017

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Section: Orbit Validation Using Slrmentioning

confidence: 74%

Quality assessment of multi-GNSS orbits and clocks for real-time precise point positioning

2017

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“…Constant monitoring and independent validations are advised by both the MGEX and IGS authorities to help in the description of satellites' perturbations. Moreover, the existence of the orbit-modeling issues may reflect in dependencies between the orbit quality and the elevation angle of the Sun above the orbital plane, the elongation angle, or the latitude of the satellite with respect to the Sun [1]. However, the impact of those dependencies is still not fully understood and eliminated, so that the nature of the perturbations should be constantly investigated.…”

Section: Capabilities Of Govus With Respect To the Critical Issues Ofmentioning

confidence: 99%

“…Most of the current problems with the homogenous multi-GNSS orbit determination are related to the lack of proper models, which could entirely reduce the effects of most important non-gravitational accelerations such as SRP, antenna thrust and both thermal radiation from the Earth and Earth's albedo, as well as proper modeling of satellite attitudes for non-yaw-steering events [1,44,45]. Constant monitoring and independent validations are advised by both the MGEX and IGS authorities to help in the description of satellites' perturbations.…”

Section: Capabilities Of Govus With Respect To the Critical Issues Ofmentioning

confidence: 99%

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A New Online Service for the Validation of Multi-GNSS Orbits Using SLR

2017

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In the last decade, we have been witnessing a rapid development of the constellations of Global and Regional Navigation Satellite Systems (GNSS/RNSS). Besides the well-known GPS and GLONASS, newly developed systems such as Galileo, BeiDou, QZSS and NAVIC have become increasingly important. All satellites of new GNSS are equipped with laser retroreflector arrays (LRA) dedicated to Satellite Laser Ranging (SLR). SLR allows, e.g., an independent validation of microwave-based orbit products. Therefore, a fully operational online service called the multi-GNSS Orbit Validation Visualizer Using SLR (GOVUS) has been developed allowing for near real-time analysis of the quality of multi-GNSS orbits. The mean offsets of SLR residuals for Center for Orbit Determination in Europe (CODE) orbits in 2016 are at the level of −8, −38, −14, and −107 mm, for BeiDou, Galileo, GLONASS, and QZSS, respectively, with the standard deviations of 66, 36, 29, and 100 mm. Moreover, GOVUS can be used as a database containing information on equipment used at SLR stations and multi-GNSS satellite parameters. This paper includes a comprehensive description of the functionality and the structure of the developed service with exemplary analyses. The paper points out the most critical issues, limitations and challenges of multi-GNSS and SLR tracking network in the context of the SLR orbit validation. The goal of the paper and GOVUS itself is to determine: (1) what is the current quality of multi-GNSS orbits validated using SLR results; (2) what kinds of systematic errors can affect GNSS orbits and SLR observations; and (3) how to provide the online analysis tools to the broadest possible multi-GNSS community. The service has been officially operating since March 2017 as the Associate Analysis Center of the International Laser Ranging Service (ILRS ACC).

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“…Galileo satellite clocks provide Galileo system time (GST) [20,21], BeiDou satellite clocks refer to BeiDou time (BDT) [22][23][24], and GPS satellite clocks are relative to GPS time (GPST) [25][26][27][28][29]. After the International GNSS Service (IGS) started the "Multi GNSS Experiment" (MGEX) in 2012, combined satellite orbit and clock products with the same time scale have been provided by several analysis centers, including the ESA, GFZ, GENS, and CODE [16,17], which support newly developed GNSSs such as Galileo and BeiDou [30][31][32][33]. Therefore, the products satisfy the requirements for combining GPS, BeiDou, and Galileo for precise time and frequency transfer based on the CP approach.…”

Section: Introductionmentioning

confidence: 99%

Combining GPS, BeiDou, and Galileo Satellite Systems for Time and Frequency Transfer Based on Carrier Phase Observations

Zhang

et al. 2018

Remote Sensing

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Abstract:The carrier-phase (CP) technique based on the Global Navigation Satellite System (GNSS) has proved to be a useful spatial tool for remote and precise time transfer. In order to improve the robustness and stability of the time transfer solution for a time link, a new CP approach based on a combination of GPS, BeiDou (BDS), and Galileo satellite systems is proposed in this study. The mathematical model for the obtained unique time transfer solution is discussed. Three GNSS stations that can track GPS, BeiDou, and Galileo satellites were used, and two time links are established to assess the performance of the approach. Multi-GNSS time transfer outperforms single GNSS by increasing the number of available satellites and improving the time dilution of precision. For the long time link, with a geodetic distance of 7537.5 km, the RMS value of the combined multi-system solution improves by 18.8%, 59.4%, and 35.0% compared to GPS-only, BDS-only, and Galileo-only, respectively. The average frequency stability improves by 12.9%, 62.3%, and 36.0%, respectively. For the short time link, with a geodetic distance of 4.7 m, the improvement after combining the three GNSSs is 6.7% for GPS-only, 52.6% for BDS-only, and 38.2% for Galileo-only.

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The Multi-GNSS Experiment (MGEX) of the International GNSS Service (IGS) – Achievements, prospects and challenges

Cited by 747 publications

References 79 publications

Quality assessment of multi-GNSS orbits and clocks for real-time precise point positioning

Quality assessment of multi-GNSS orbits and clocks for real-time precise point positioning

A New Online Service for the Validation of Multi-GNSS Orbits Using SLR

Combining GPS, BeiDou, and Galileo Satellite Systems for Time and Frequency Transfer Based on Carrier Phase Observations

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