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

2021 ◽  
Vol 13 (17) ◽  
pp. 3388
Author(s):  
Longjiang Tang ◽  
Jungang Wang ◽  
Huizhong Zhu ◽  
Maorong Ge ◽  
Aigong Xu ◽  
...  

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.

GPS Solutions ◽  
2020 ◽  
Vol 24 (2) ◽  
Author(s):  
Yongqiang Yuan ◽  
Xingxing Li ◽  
Yiting Zhu ◽  
Yun Xiong ◽  
Jiande Huang ◽  
...  

1994 ◽  
Vol 31 (5) ◽  
pp. 830-833 ◽  
Author(s):  
Yvonne Vigue ◽  
Stephen M. Lichten ◽  
Ron J. Muellerschoen ◽  
Geoff Blewitt ◽  
Michael B. Heflin

2020 ◽  
Author(s):  
Xinghan Chen ◽  
Maorong Ge ◽  
Harald Schuh

<p>Currently, with the rapid development of the third generation of BeiDou satellite system (BDS-3), the corresponding solar radiation pressure (SRP) forces should be well and soon modeled in order to enhance the performance of precise orbit determination (POD) and precise clock estimation (PCE) for high-precision applications. In this contribution, the BDS-3 post-processed and ultra-rapid PODs have been realized by fully exploiting data provided by the International GNSS Service (IGS). We firstly test the Center for Orbit Determination in Europe (CODE) SRP model (ECOM1) and ECOM2 models and notice a large disagreement of overlapping orbits at the boundary of two adjacent days within an eclipse period. The reason for this could be that the ECOM2 model is over-parameterized or an extra periodic SRP term should be considered. Furthermore, our numerical analyses confirm that the cosinus terms must be excluded and the fourth- and sixth-order SRP sinus terms are significant in the Sun direction for the SRP model of BDS-3 satellites. Therefore, a new SRP model is developed herein to improve BDS-3 orbits, especially for eclipse season. Using the new SRP model, the large fluctuations of 20 cm can be reduced to below 10 cm for the radial-track component of overlapping orbits over eclipse seasons and SLR residuals are improved by a factor of 2 compared to that of ECOM1 and ECOM2. For the predicted orbits, the improvement due to the new SRP model is also demonstrated and the mean offsets of overlapping orbit differences over the eclipse periods can be reduced from -9.3 cm, -18.9 cm, and 39.9 cm to -5.5 cm, 8.3 cm, and 12.7 cm in the radial, cross, and along directions, respectively.</p>


GPS Solutions ◽  
2021 ◽  
Vol 25 (2) ◽  
Author(s):  
Bingbing Duan ◽  
Urs Hugentobler

AbstractSolar radiation pressure (SRP) is the dominant non-gravitational perturbation for GPS satellites. In the IGS (International GNSS Service), this perturbation is modeled differently by individual analysis centers (ACs). The two most widely used methods are the Empirical CODE orbit Model (ECOM, ECOM2) and the JPL GSPM model. When using ECOM models, a box-wing model or other a priori models, as well as stochastic pulses at noon or midnight, are optionally adopted by some ACs to compensate for the deficiencies of the ECOM or ECOM2 model. However, both box-wing and GSPM parameters were published many years ago. There could be an aging effect going with time. Also, optical properties and GSPM parameters of GPS Block IIF satellites are currently not yet published. In this contribution, we first determine Block-specific optical parameters of GPS satellites using GPS code and phase measurements of 6 years. Various physical effects, such as yaw bias, radiator emission in the satellite body-fixed − X and Y directions and the thermal radiation of solar panels, are considered as additional constant parameters in the optical parameter adjustment. With all the adjusted parameters, we form an enhanced box-wing model adding all the modeled physical effects. In addition, we determine Block-specific GSPM parameters by using the same GPS measurements. The enhanced box-wing model and the GSPM model are then taken as a priori model and are jointly used with ECOM and ECOM2 model, respectively. We find that the enhanced box-wing model performs similarly to the GSPM model outside eclipse seasons. RMSs of all the ECOM and ECOM2 parameters are reduced by 30% compared to results without the a priori model. Orbit misclosures and orbit predictions are improved by combining the enhanced box-wing model with ECOM and ECOM2 models. In particular, the improvement in orbit misclosures for the eclipsing Block IIR and IIF satellites, as well as the non-eclipsing IIA satellites, is about 25%, 10% and 10%, respectively, for the ECOM model. Therefore, the enhanced box-wing model is recommended as an a priori model in GPS satellite orbit determination.


2020 ◽  
Author(s):  
Xiao Chang ◽  
Benjamin Männel ◽  
Harald Schuh ◽  
Roman Galas

<p>As one of the products of the International GNSS Service (IGS), precise orbits for Global Navigation Satellite Systems (GNSS) play an important role in many geoscientific applications. Currently, the precision and consistency of GNSS orbits are still limited by insufficient knowledge of spacecraft response to non-conservative perturbations, of which the solar radiation pressure (SRP) has the strongest influence. SRP modeling strategies adopted by IGS Analysis Centers (ACs) can be categorized: 1) analytical SRP model like the ROCK models (Fliegel et al. 1992), 2) empirical representation, for example by estimating ECOM parameters (Beutler et al. 1994, Springer et al. 1999a, and Arnold et al. 2015), and 3) the combination of both, hybrid empirical-physical SRP model such as adjustable box-wing model (e.g. Rodriguez-Solano et al. 2012). While empirical models fit the observations well, the loss of physical explanation may cause unexpected systematic errors. Uncertainties in the a-priori SRP models, which rely on the optical coefficients and surface structure of the satellites, can also degrade the determined orbit systematically. Using a hybrid model, i.e. estimation of empirical parameters on top of a-priori model, is expected to take the advantage of the existing satellite properties and to compensate for the inaccuracy related to the satellite properties based on observations. Thus, different hybrid models have to be tested for each constellation and block type.</p><p> </p><p>In this study, we assess the GNSS precise orbit determination (POD) based on different setups of a-priori models and ECOM parametrization. The results will be presented as follows: 1) first, the orbits difference introduced by a-priori model is analyzed by comparing orbit with the one based on pure ECOM models. 2) Second, the effect of a-priori models will be discussed by assessing the estimated ECOM parameters. 3) Third, the derived orbit will be compared with the final orbits of selected IGS ACs. 4) The effect of the selected SRP modeling strategy on geodetic parameters will be discussed with special focus on the estimated station coordinates.</p>


2021 ◽  
Author(s):  
Jie Li ◽  
Yongqiang Yuan ◽  
Shi Huang ◽  
Chengbo Liu ◽  
Jiaqing Lou ◽  
...  

<p>With the successful launch of the last Geostationary Earth Orbit (GEO) satellite in June 2020, China has completed the construction of the third generation BeiDou navigation satellites system (BDS-3). BDS-3 global services have been initiated in July 2020 with the constellation of 3 GEO, 3 Inclined Geosynchronous Orbit (IGSO) and 24 Medium Earth Orbit (MEO) satellites. In order to further improve the performance of BDS-3 services, the quality of BDS-3 precise orbit product needs further enhancements.</p><p>       The solar radiation pressure (SRP) is the main non-conservative orbit perturbation for GNSS satellites and is the key to improve BDS-3 precise orbit determination. In this study, we focus on the SRP models for BDS-3 satellites. Firstly, the widely used Extended CODE Orbit Model with five parameters (ECOM-5) is assessed. With one-year observations of 2020 from both iGMAS and MGEX networks, the five parameters of ECOM model (D0, Y0, B0, Bc and Bs) are estimated for each BDS-3 satellite. The D0 estimates show an obvious dependency on the elevation angle of the Sun above the satellite orbital plane (denoted as β). In addition, large variations can be noticed in eclipse seasons, which indicate the dramatic changes of SRP. The Y0 estimates vary from -0.6 nm/s<sup>2</sup> to 0.6 nm/s<sup>2</sup> for MEO, -1.0 to 1.0 nm/s<sup>2</sup> for IGSO and -1.0 to 1.5 nm/s<sup>2</sup> for GEO satellites. The B0 estimates of several satellites exhibit a clear dependency on the β angle. The largest variation of B0 appears at C45 and C46, changing from 1.0 nm/s<sup>2</sup> at 15 deg to 8.3 nm/s<sup>2</sup> at 64 deg, which implies that the solar panels of these two satellites may have an obvious rotation lag. To compensate the deficiencies of BDS-3 SRP modeling, we introduce several additional parameters into ECOM-5 model (e.g. introducing higher harmonic terms). The POD performances can be improved by about 10% and 40% for BDS-3 MEO/IGSO and GEO satellites, respectively.</p><p>       Except for the empirical model, we also study the semi-empirical SRP model such as the a priori box-wing model. Since the geometrical and optical properties from BDS-3 metadata are general and rough, we apply more detailed geometrical and optical coefficients for BDS-3 satellites. The POD performance can be improved by about 10% compared to empirical SRP models. Furthermore, considering Earth radiation pressure will have an impact of about 1.3 cm in radial component for MEO satellites.</p>


2019 ◽  
Vol 11 (24) ◽  
pp. 3024
Author(s):  
Yang Liu ◽  
Yanxiong Liu ◽  
Ziwen Tian ◽  
Xiaolei Dai ◽  
Yun Qing ◽  
...  

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.


GPS Solutions ◽  
2020 ◽  
Vol 25 (1) ◽  
Author(s):  
Radosław Zajdel ◽  
Krzysztof Sośnica ◽  
Grzegorz Bury

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.


2020 ◽  
Author(s):  
Heike Peter ◽  
Javier Berzosa ◽  
Jaime Fernández ◽  
Pierre Féménias

<p>The Copernicus POD (Precise Orbit Determination) Service is responsible for the generation of precise orbital products of the Copernicus Sentinel-1, -2, and -3 missions. In the near future, the processing setup of the Copernicus POD Service will be updated to state-of-the-art background models (geopotential, ocean tides and atmospheric gravity) and the use of single-receiver ambiguity fixing using CODE (Center for Orbit Determination in Europe) products.</p><p>In the current orbit parametrization of the six satellites, a solar radiation pressure coefficient is estimated for each daily arc. To provide long-term stability, in particular for the time series of the altimeter Sentinel-3 satellites, it would be preferable to use a constant solar radiation pressure coefficient in the processing. A reprocessing based on the updated models and set-up will be used to compute daily estimates of the solar radiation pressure coefficient for all satellites. The analysis may reveal satellite model deficiencies and might help to improve the satellite macro-models.</p><p>Mean values of the solar radiation pressure coefficients from the long-term series can be used on future operational processing. At the same time a refinement of the selection of the estimated orbit parameters might also be done if necessary, in particular the empirical accelerations. Impact on the orbit determination results and on the quality of the orbits is presented for all six satellites.</p>


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