Validation of Multi-Year Galileo Orbits Using Satellite Laser Ranging

Satellite laser ranging (SLR) observations provide an independent validation of the global navigation satellite system (GNSS) orbits derived using microwave measurements. SLR residuals have also proven to be an important indicator of orbit radial accuracy. In this study, SLR validation is conducted for the precise orbits of eight Galileo satellites covering four to eight years (the current longest span), provided by multiple analysis centers (ACs) participating in the multi-GNSS experiment (MGEX). The purpose of this long-term analysis (the longest such study to date), is to provide a comprehensive evaluation of orbit product quality, its influencing factors, and the effect of perturbation model updates on precise orbit determination (POD) processing. A conventional ECOM solar radiation pressure (SRP) model was used for POD. The results showed distinct periodic variations with angular arguments in the SRP model, implying certain defects in the ECOM system. Updated SRP descriptions, such as ECOM2 or the Box-Wing model, led to significant improvements in SLR residuals for orbital products from multiple ACs. The standard deviation of these residuals decreased from 8–10 cm, before the SRP update, to about 3 cm afterward. The systematic bias of the residuals was also reduced by 2–4 cm and the apparent variability decreased significantly. In addition, the effects of gradual SRP model updates in the POD were evident in orbit comparisons. Orbital differences between ACs in the radial direction were reduced from the initial 10 cm to better than 3 cm, which is consistent with the results of SLR residual analysis. These results suggest SLR validation to be a powerful technique for evaluating the quality of POD strategies in GNSS orbits. Furthermore, this study has demonstrated that perturbation models, such as SRP, provide a better orbit modeling for the Galileo satellites.

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GLONASS precise orbit determination with identification of malfunctioning spacecraft

GPS Solutions ◽

10.1007/s10291-021-01221-z ◽

2022 ◽

Vol 26 (2) ◽

Author(s):

Grzegorz Bury ◽

Krzysztof Sośnica ◽

Radosław Zajdel ◽

Dariusz Strugarek

Keyword(s):

Analytical Model ◽

Orbit Determination ◽

Precise Orbit Determination ◽

Systematic Errors ◽

Satellite Laser Ranging ◽

Laser Ranging ◽

Precise Orbit ◽

Similar Construction ◽

Wing Model ◽

The Impact

AbstractDue to the continued development of the GLONASS satellites, precise orbit determination (POD) still poses a series of challenges. This study examines the impact of introducing the analytical tube-wing model for GLONASS-M and the box-wing model for GLONASS-K in a series of hybrid POD strategies that consider both the analytical model and a series of empirical parameters. We assess the perturbing accelerations acting on GLONASS spacecraft based on the analytical model. All GLONASS satellites are equipped with laser retroreflectors for satellite laser ranging (SLR). We apply the SLR observations for the GLONASS POD in a series of GNSS + SLR combined solutions. The application of the box-wing model significantly improves GLONASS orbits, especially for GLONASS-K, reducing the STD of SLR residuals from 92.6 to 27.6 mm. Although the metadata for all GLONASS-M satellites reveal similar construction characteristics, we found differences in empirical accelerations and SLR offsets not only between GLONASS-M and GLONASS-M+ but also within the GLONASS-M+ series. Moreover, we identify satellites with inferior orbit solutions and check if we can improve them using the analytical model and SLR observations. For GLONASS-M SVN730, the STD of the SLR residuals for orbits determined using the empirical solution is 48.7 mm. The STD diminishes to 41.2 and 37.8 mm when introducing the tube-wing model and SLR observations, respectively. As a result, both the application of the SLR observations and the analytical model significantly improve the orbit solution as well as reduce systematic errors affecting orbits of GLONASS satellites.

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Initial Assessment of Precise Orbit Determination for Combined BDS-2 and BDS-3 Satellites

10.5194/egusphere-egu2020-22166 ◽

2020 ◽

Author(s):

Bingfeng Tan

Keyword(s):

Three Dimensional ◽

Precise Orbit Determination ◽

Satellite System ◽

Radial Component ◽

Satellite Laser Ranging ◽

Initial Assessment ◽

Laser Ranging ◽

Data Process ◽

Global Navigation Satellite ◽

New Generation

<p>By December 2019, twenty-four new-generation BeiDou (BDS-3) Medium Earth Orbit (MEO) satellites, three Inclined Geosynchronous Orbit (IGSO) satellites and one Geostationary Orbit (GEO) satellite have been launched, symbolizing its starting of global coverage.</p><p>The observations of a very limited number of 17 International GNSS (Global Navigation Satellite System) Monitoring and Assessment Service (iGMAS) stations and 80 IGS Multi-GNSS Experiment (MGEX) stations from October 2018 to October 2019 have been processed to determine the orbits of combined BDS-3 and BDS-2 satellites. All of the latest official BDS-2 and BDS-3 satellite phase center offsets (PCOs) and other satellite parameters were used in the data process. The internal consistency (daily boundary discontinuity) and satellite laser ranging (SLR) validations are conducted for the orbit validation. The average three-dimensional root-mean-square error (RMS-3D) of 24-hour overlapping arcs for BDS-2 and BDS-3 satellites is within 0.1m and 0.15m, respectively. Satellite laser ranging (SLR) validation reports that the orbit radial component for BDS-2 and BDS-3 satellites is within 0.1m. The orbit accuracy of BDS-3 is slightly lower than that of BDS-2 satellite presently.</p>

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A Priori Solar Radiation Pressure Model for BeiDou-3 MEO Satellites

Remote Sensing ◽

10.3390/rs11131605 ◽

2019 ◽

Vol 11 (13) ◽

pp. 1605 ◽

Cited By ~ 3

Author(s):

Xingyuan Yan ◽

Chenchen Liu ◽

Guanwen Huang ◽

Qin Zhang ◽

Le Wang ◽

...

Keyword(s):

A Priori ◽

Precise Orbit Determination ◽

Orbital Plane ◽

Solar Radiation Pressure ◽

The Body ◽

Systematic Variation ◽

Laser Ranging ◽

The Sun ◽

Wing Model ◽

Orbit Model

Due to the cuboid satellite body of BeiDou-3 satellites, the accuracy of their orbit showed a trend of systematic variation with the sun-satellite-earth angle (ε) using the Extend CODE Orbit Model (ECOM1). Therefore, an a priori cuboid box-wing model (named the cuboid model) is necessary to compensate ECOM1. Considering that the body-dimensions and optical properties of the BeiDou-3 satellites used to construct the box-wing model have not yet been fully released, the adjustable box-wing model (ABW) was used for precise orbit determination (POD). The a priori cuboid box-wing model was directly estimated by the precision radiation accelerations, obtained from ABW POD. When using ECOM1 model, for 14 < β < 40°, a linear systematic variation of D0 related to the elevation of the sun above the orbital plane (β-angle) with a slope of 0.048 nm/s2/°, was found for C30. After adding the cuboid model to assist ECOM1 (named Cuboid + ECOM1), the slope was reduced to 0.005 nm/s2/°, and for C20 satellite, the standard deviation (STD) of D0 was improved, from 1.28 to 0.85 nm/s2 (34%). For satellite laser ranging (SLR) validation, when using the ECOM1 model, the systematic variation with the ε angle was about 14 cm for C20 and C30. After using the Cuboid + ECOM1 model, the variation was significantly reduced to about 5 cm. For C20 and C21, compared with the ECOM1 model, the root mean square (RMS) of the ECOM2 and Cuboid + ECOM1 model was improved by about 0.54 (10.3%) and 0.43 cm (8.7%). For C29 and C30, the RMS of ECOM2 and Cuboid + ECOM1 model was improved for about 0.7 (10.9%) and 1.6 cm (25.6%). Finally, the RMS of the SLR residuals of 4.37 to 4.88 cm was achieved for BeiDou-3 POD.

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Impact of ECOM Solar Radiation Pressure Models on Multi-GNSS Ultra-Rapid Orbit Determination

Remote Sensing ◽

10.3390/rs11243024 ◽

2019 ◽

Vol 11 (24) ◽

pp. 3024

Author(s):

Yang Liu ◽

Yanxiong Liu ◽

Ziwen Tian ◽

Xiaolei Dai ◽

Yun Qing ◽

...

Keyword(s):

Solar Radiation ◽

Real Time ◽

Radiation Pressure ◽

Orbit Determination ◽

Precise Orbit Determination ◽

Solar Radiation Pressure ◽

Satellite System ◽

Ambiguity Fixing ◽

Global Navigation Satellite ◽

The Impact

The Global Navigation Satellite System (GNSS) ultra-rapid precise orbits are crucial for global and wide-area real-time high-precision applications. The solar radiation pressure (SRP) model is an important factor in precise orbit determination. The real-time orbit determination is generally less accurate than the post-processed one and may amplify the instability and mismodeling of SRP models. Also, the impact of different SRP models on multi-GNSS real-time predicted orbits demands investigations. We analyzed the impact of the ECOM 1 and ECOM 2 models on multi-GNSS ultra-rapid orbit determination in terms of ambiguity resolution performance, real-time predicted orbit overlap precision, and satellite laser ranging (SLR) validation. The multi-GNSS observed orbital arc and predicted orbital arcs of 1, 3, 6, and 24 h are compared. The simulated real-time experiment shows that for GLONASS and Galileo ultra-rapid orbits, compared to ECOM 1, ECOM 2 increased the ambiguity fixing rate to 89.3% and 83.1%, respectively, and improves the predicted orbit accuracy by 9.2% and 27.7%, respectively. For GPS ultra-rapid orbits, ECOM 2 obtains a similar ambiguity fixing rate as ECOM 1 but slightly better orbit overlap precision. For BDS GEO ultra-rapid orbits, ECOM 2 obtains better overlap precision and SLR residuals, while for BDS IGSO and MEO ultra-rapid orbits, ECOM 1 obtains better orbit overlap precision and SLR residuals.

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Geocenter coordinates derived from multi-GNSS: a look into the role of solar radiation pressure modeling

GPS Solutions ◽

10.1007/s10291-020-01037-3 ◽

2020 ◽

Vol 25 (1) ◽

Cited By ~ 1

Author(s):

Radosław Zajdel ◽

Krzysztof Sośnica ◽

Grzegorz Bury

Keyword(s):

Solar Radiation ◽

Radiation Pressure ◽

A Priori ◽

Great Majority ◽

Solar Radiation Pressure ◽

Satellite System ◽

Annual Variations ◽

Wing Model ◽

Geocenter Motion ◽

The Impact

Abstract The Global Navigational Satellite System (GNSS) technique is naturally sensitive to the geocenter motion, similar to all satellite techniques. However, the GNSS-based estimates of the geocenter used to contain more orbital artifacts than the geophysical signals, especially for the Z component of the geocenter coordinates. This contribution conveys a discussion on the impact of solar radiation pressure (SRP) modeling on the geocenter motion estimates. To that end, we process 3 years of GPS, GLONASS, and Galileo observations (2017–2019), collected by a globally distributed network of the ground stations. All possible individual system-specific solutions, as well as combinations of the available constellations, are tested in search of characteristic patterns in geocenter coordinates. We show that the addition of a priori information about the SRP-based forces acting on the satellites using a box-wing model mitigates a great majority of the spurious signals in the spectra of the geocenter coordinates. The amplitude of the 3 cpy (about 121 days) signal for GLONASS has been reduced by a factor of 8.5. Moreover, the amplitude of the spurious 7 cpy (about 52 days) signal has been reduced by a factor of 5.8 and 3.1 for Galileo and GPS, respectively. Conversely, the box-wing solutions indicate increased amplitudes of the annual variations in the geocenter signal. The latter reaches the level of 10–11 mm compared to 4.4 and 6.0 mm from the satellite laser ranging observations of LAGEOS satellites and the corresponding GNSS series applying extended empirical CODE orbit model (ECOM2), respectively. Despite the possible improvement in the GLONASS-based Z component of the geocenter coordinates, we show that some significant power can still be found at periods other than annual. The GPS- and Galileo-based estimates are less affected; thus, a combination of GPS and Galileo leads to the best geocenter estimates.

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Applications of satellite laser ranging and laser time transfer in BeiDou navigation satellite system

Optik ◽

10.1016/j.ijleo.2019.04.131 ◽

2019 ◽

Vol 188 ◽

pp. 251-262 ◽

Cited By ~ 2

Author(s):

Haifeng Zhang ◽

Zhien Cheng ◽

Mingliang Long ◽

Huarong Deng ◽

Wendong Meng ◽

...

Keyword(s):

Satellite System ◽

Satellite Laser Ranging ◽

Laser Ranging ◽

Navigation Satellite ◽

Time Transfer ◽

Beidou Navigation Satellite System

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Investigating the GALILEO and BeiDou orbit accuracy derived from rapid products

Academic Perspective Procedia ◽

10.33793/acperpro.03.01.62 ◽

2020 ◽

Vol 3 (1) ◽

pp. 316-321

Author(s):

Sermet Ogutcu ◽

Salih Alcay ◽

Omer Faruk Atiz

Keyword(s):

Orbit Determination ◽

Precise Orbit Determination ◽

Solar Radiation Pressure ◽

Satellite Orbit ◽

Satellite System ◽

Precise Orbit ◽

Yaw Attitude ◽

Global Navigation Satellite ◽

Cross Track ◽

Mean Square Errors

In recent years, the advances of the new Global Navigation Satellite System (GNSS) constellations including, Galileo and BeiDou (BDS), have undergone dramatic changes. Some analysis centers (ACs) produce precise orbit and clock products of Galileo and BeiDou constellations. Currently, three types of Galileo and BeiDou satellite orbit and clock products are available &ndash; namely, precise, rapid and ultra-rapid products &ndash;. Ultra-rapid and rapid products are generally used for time-constrained applications. Precise orbit determination (POD) of Galileo and BeiDou is much challenging compared with GPS and GLONASS constellations due to the officially undetermined receiver phase center offset (PCO), variations (PCV) of Galileo and BeiDou constellations and, also some other not well-defined factors such as yaw-attitude models and solar radiation pressure. In this study, GALILEO orbit accuracy is investigated using rapid products produced by Center for Orbit Determination in Europe (CODE) GeoForschungsZentrum (GFZ) and Wuhan University (WUHAN), while GFZ and WUHAN rapid products are used for BeiDou constellation only. One month (January) of data in 2020 is used to compute errors of radial, along-track, and cross-track components of Galileo and BeiDou orbit derived by rapid products compared with the CODE final Multi-GNSS Experiment (MGEX) product which is assumed as the reference product. The results show that no significant differences between the products are found for Galileo orbit. For BeiDou orbit, WUHAN rapid product produced the smaller root mean square errors (RMSEs) of orbit components compared with the GFZ rapid product.

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A Comparative Study on the Solar Radiation Pressure Modeling in GPS Precise Orbit Determination

Remote Sensing ◽

10.3390/rs13173388 ◽

2021 ◽

Vol 13 (17) ◽

pp. 3388

Author(s):

Longjiang Tang ◽

Jungang Wang ◽

Huizhong Zhu ◽

Maorong Ge ◽

Aigong Xu ◽

...

Keyword(s):

Solar Radiation ◽

High Precision ◽

Radiation Pressure ◽

Orbit Determination ◽

A Priori ◽

Precise Orbit Determination ◽

Solar Radiation Pressure ◽

International Gnss Service ◽

Precise Orbit ◽

Wing Model

For Global Positioning System (GPS) precise orbit determination (POD), the solar radiation pressure (SRP) is the dominant nongravitational perturbation force. Among the current SRP models, the ECOM and box-wing models are widely used in the International GNSS Service (IGS) community. However, the performance of different models varies over different GPS satellites. In this study, we investigate the performances of different SRP models, including the box-wing and adjustable box-wing as a priori models, and ECOM1 and ECOM2 as parameterization models, in the GPS POD solution from 2017 to 2019. Moreover, we pay special attention to the handling of the shadow factor in the SRP modeling for eclipsing satellites, which is critical to achieve high-precision POD solutions but has not yet been fully investigated. We demonstrate that, as an a priori SRP model, the adjustable box-wing has better performance than the box-wing model by up to 5 mm in the orbit day boundary discontinuity (DBD) statistics, with the largest improvement observed on the BLOCK IIR satellites using the ECOM1 as a parameterization SRP model. The box-wing model shows an insignificant orbit improvement serving as the a priori SRP model. For the eclipsing satellites, the three-dimensional (3D) root mean square (RMS) values of orbit DBD are improved when the shadow factor is applied only in the D direction (pointing toward to Sun) than that in the three directions (D, Y, and B) in the satellite frame. Different SRP models have comparable performance in terms of the Earth rotation parameter (ERP) agreement with the IERS EOP 14C04 product, whereas the magnitude of the length of day (LoD) annual signal is reduced when the shadow factor is applied in the D direction than in the three directions. This study clarifies how the shadow factor should be applied in the GPS POD solution and demonstrates that the a priori adjustable box-wing model combined with ECOM1 is more suitable for high-precision GPS POD solutions, which is useful for the further GNSS data analysis.

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