scholarly journals Evaluation of BDS-3 Orbit Determination Strategies Using Ground-Tracking and Inter-Satellite Link Observation

2020 ◽  
Vol 12 (16) ◽  
pp. 2647
Author(s):  
Yifei Lv ◽  
Tao Geng ◽  
Qile Zhao ◽  
Xin Xie ◽  
Feng Zhang ◽  
...  
Keyword(s):  
Orbit Determination ◽  
Precise Orbit Determination ◽  
Selection Strategy ◽  
Laser Ranging ◽  
Satellite Clock ◽  
Additional Measurement ◽  
Satellite Link ◽  
Geo Satellites ◽  
Similar Accuracy ◽  
Better Than

Dual one-way inter-satellite link (ISL) pseudoranges of BDS-3 satellites can be introduced as an additional measurement along with L-band pseudoranges and phases to improve the accuracy of precise orbit determination (POD). In the existing research, although the clock-free or geometry-free ISL observables are derived from the raw two one-way pseudoranges, only the clock-free observables are adopted for the ISL joint POD (Joint 1 POD) without considering the geometric-free observables. An improved joint (Joint 2 POD) strategy making full use of the clock-free and geometry-free observables is applied in this contribution. The orbits of ground-only POD, ISL-only POD, Joint 1 POD, and Joint 2 POD are comprehensively compared by the orbit overlapping differences, the Satellite Laser Ranging (SLR) residuals, and the characteristics of the satellite clock offsets estimated simultaneously. The comparisons prove that the performance of the Joint 2 POD strategy is better than that of the other three POD strategies regardless of the types of satellites. Moreover, this paper discusses ISL’s contribution to the station selection strategy in terms of the number and distribution. The experimental results show that, when there are more than 20 stations, each additional 10 stations contributes to a maximum of 7.5%, 3.9%, and 2.8% improvement on MEO, IGSO, and GEO satellites 3D accuracy, respectively. When the number of stations reaches 50, the precise orbits achieve similar accuracy to the results using 80 stations. In addition, after adding ISL data, the orbits estimated using 10 regional stations and 10 global stations are greatly improved, and the accuracy between them is only 0.9 cm in 3D errors.

scholarly journals Comparisons of CODE and CNES/CLS GPS satellite bias products and applications in Sentinel-3 satellite precise orbit determination

GPS Solutions ◽  
2021 ◽  
Vol 25 (4) ◽  
Author(s):  
Bingbing Duan ◽  
Urs Hugentobler
Keyword(s):  
Linear Combination ◽  
Orbit Determination ◽  
Fractional Part ◽  
Precise Orbit Determination ◽  
Satellite Orbit ◽  
Satellite Orbits ◽  
Satellite Clock ◽  
Analysis Center ◽  
Wide Lane ◽  
Total Difference

AbstractTo resolve undifferenced GNSS phase ambiguities, dedicated satellite products are needed, such as satellite orbits, clock offsets and biases. The International GNSS Service CNES/CLS analysis center provides satellite (HMW) Hatch-Melbourne-Wübbena bias and dedicated satellite clock products (including satellite phase bias), while the CODE analysis center provides satellite OSB (observable-specific-bias) and integer clock products. The CNES/CLS GPS satellite HMW bias products are determined by the Hatch-Melbourne-Wübbena (HMW) linear combination and aggregate both code (C1W, C2W) and phase (L1W, L2W) biases. By forming the HMW linear combination of CODE OSB corrections on the same signals, we compare CODE satellite HMW biases to those from CNES/CLS. The fractional part of GPS satellite HMW biases from both analysis centers are very close to each other, with a mean Root-Mean-Square (RMS) of differences of 0.01 wide-lane cycles. A direct comparison of satellite narrow-lane biases is not easily possible since satellite narrow-lane biases are correlated with satellite orbit and clock products, as well as with integer wide-lane ambiguities. Moreover, CNES/CLS provides no satellite narrow-lane biases but incorporates them into satellite clock offsets. Therefore, we compute differences of GPS satellite orbits, clock offsets, integer wide-lane ambiguities and narrow-lane biases (only for CODE products) between CODE and CNES/CLS products. The total difference of these terms for each satellite represents the difference of the narrow-lane bias by subtracting certain integer narrow-lane cycles. We call this total difference “narrow-lane” bias difference. We find that 3% of the narrow-lane biases from these two analysis centers during the experimental time period have differences larger than 0.05 narrow-lane cycles. In fact, this is mainly caused by one Block IIA satellite since satellite clock offsets of the IIA satellite cannot be well determined during eclipsing seasons. To show the application of both types of GPS products, we apply them for Sentinel-3 satellite orbit determination. The wide-lane fixing rates using both products are more than 98%, while the narrow-lane fixing rates are more than 95%. Ambiguity-fixed Sentinel-3 satellite orbits show clear improvement over float solutions. RMS of 6-h orbit overlaps improves by about a factor of two. Also, we observe similar improvements by comparing our Sentinel-3 orbit solutions to the external combined products. Standard deviation value of Satellite Laser Ranging residuals is reduced by more than 10% for Sentinel-3A and more than 15% for Sentinel-3B satellite by fixing ambiguities to integer values.

Design of Laser Ranging Device Using the Improved Photodetector and Its Usage in Geosynchronous Earth Orbit Navigation Satellite Orbit Determination

2020 ◽  
Vol 15 (12) ◽  
pp. 1508-1517
Author(s):  
Xiangfei Yin ◽  
Genyou Liu ◽  
Shilong Cao
Keyword(s):  
Orbit Determination ◽  
Silicon Substrate ◽  
Structural Parameters ◽  
Fdtd Method ◽  
Absorption Enhancement ◽  
Laser Ranging ◽  
Earth Orbit ◽  
Geo Satellites ◽  
Msm Photodetector ◽  
Regional Augmentation

The geosynchronous earth orbit (GEO) satellites have good coverage performance and are widely used in WAAS, BDS, CAPS and other regional augmentation and regional navigation systems. At the same time, the precise orbit determination and prediction of such satellites play a significant role in high-precision navigation and user real-time positioning. In order to obtain higher accuracy of orbit determination, the laser ranging device is improved by equipping with a silicon-substrate germanium MSM photodetector in this study. In addition, the surface plasmon resonance augmentation effect is further studied to further enhance the photoelectric performance of the silicon-substrate germanium MSM photodetector. The detector is connected to the OPA657. The corresponding pre-amplified circuit is further designed in this study so that the laser ranging device can be used for the orbit determination application of GEO navigation satellites. In the experiment, the designed silicon-substrate germanium MSM photodetector is tested firstly, the finite-different time-domain (FDTD) method is used to analyze the structure of the photodetector. Then, the effects of the structural parameters such as the grating period on the resonance augmentation of the designed photodetector are analyzed. The results reveal that the photodetector has the best performance at 1500 nm with the absorption enhancement factor of higher than 7. The GNSS combined with the laser ranging is used for comparing the orbit determination errors of GEO satellites. 10 laser observation stations are selected, some of which are equipped with the laser ranging device designed in this study and supply to various GEO satellites for information collection. The results show that GEO satellites have to be introduced to the system deviation when adding the laser ranging data, otherwise they will deviate from the orbit. In addition, the laser ranging device designed in this study can significantly reduce the deviation caused by the introduction of laser ranging data from GEO satellites compared with traditional laser ranging devices.

scholarly journals Integrated Precise Orbit Determination of Multi-GNSS and Large LEO Constellations

2019 ◽  
Vol 11 (21) ◽  
pp. 2514 ◽  
Author(s):  
Xingxing Li ◽  
Keke Zhang ◽  
Fujian Ma ◽  
Wei Zhang ◽  
Qian Zhang ◽  
...  
Keyword(s):  
Orbit Determination ◽  
Precise Orbit Determination ◽  
Global Network ◽  
Computational Time ◽  
Observation Data ◽  
Accuracy Improvement ◽  
Precise Orbit ◽  
Leo Satellites ◽  
Geo Satellites ◽  
Gnss Observations

Global navigation satellite system (GNSS) orbits are traditionally determined by observation data of ground stations, which usually need even global distribution to ensure adequate observation geometry strength. However, good tracking geometry cannot be achieved for all GNSS satellites due to many factors, such as limited ground stations and special stationary characteristics for the geostationary Earth orbit (GEO) satellites in the BeiDou constellation. Fortunately, the onboard observations from low earth orbiters (LEO) can be an important supplement to overcome the weakness in tracking geometry. In this contribution, we perform large LEO constellation-augmented multi-GNSS precise orbit determination (POD) based on simulated GNSS observations. Six LEO constellations with different satellites numbers, orbit types, and altitudes, as well as global and regional ground networks, are designed to assess the influence of different tracking configurations on the integrated POD. Then, onboard and ground-based GNSS observations are simulated, without regard to the observations between LEO satellites and ground stations. The results show that compared with ground-based POD, a remarkable accuracy improvement of over 70% can be observed for all GNSS satellites when the entire LEO constellation is introduced. Particularly, BDS GEO satellites can obtain centimeter-level orbits, with the largest accuracy improvement being 98%. Compared with the 60-LEO and 66-LEO schemes, the 96-LEO scheme yields an improvement in orbit accuracy of about 1 cm for GEO satellites and 1 mm for other satellites because of the increase of LEO satellites, but leading to a steep rise in the computational time. In terms of the orbital types, the sun-synchronous-orbiting constellation can yield a better tracking geometry for GNSS satellites and a stronger augmentation than the polar-orbiting constellation. As for the LEO altitude, there are almost no large-orbit accuracy differences among the 600, 1000, and 1400 km schemes except for BDS GEO satellites. Furthermore, the GNSS orbit is found to have less dependence on ground stations when incorporating a large number of LEO. The orbit accuracy of the integrated POD with 8 global stations is almost comparable to the result of integrated POD with a denser global network of 65 stations. In addition, we also present an analysis concerning the integrated POD with a partial LEO constellation. The result demonstrates that introducing part of a LEO constellation can be an effective way to balance the conflict between the orbit accuracy and computational efficiency.

scholarly journals Validation of the EGSIEM-REPRO GNSS Orbits and Satellite Clock Corrections

2020 ◽  
Vol 12 (14) ◽  
pp. 2322 ◽  
Author(s):  
Andreja Sušnik ◽  
Andrea Grahsl ◽  
Daniel Arnold ◽  
Arturo Villiger ◽  
Rolf Dach ◽  
...  
Keyword(s):  
Orbit Determination ◽  
Precise Orbit Determination ◽  
Satellite System ◽  
Satellite Orbits ◽  
Satellite Clock ◽  
Gps Satellites ◽  
Glonass Satellite ◽  
Global Navigation Satellite ◽  
Gravity Recovery ◽  
First Time

In the framework of the European Gravity Service for Improved Emergency Management (EGSIEM) project, consistent sets of state-of-the-art reprocessed Global Navigation Satellite System (GNSS) orbits and satellite clock corrections have been generated. The reprocessing campaign includes data starting in 1994 and follows the Center for Orbit Determination in Europe (CODE) processing strategy, in particular exploiting the extended version of the empirical CODE Orbit Model (ECOM). Satellite orbits are provided for Global Positioning System (GPS) satellites since 1994 and for Globalnaya Navigatsionnaya Sputnikovaya Sistema (GLONASS) since 2002. In addition, a consistent set of GPS satellite clock corrections with 30 s sampling has been generated from 2000 and with 5 s sampling from 2003 onwards. For the first time in a reprocessing scheme, GLONASS satellite clock corrections with 30 s sampling from 2008 and 5 s from 2010 onwards were also generated. The benefit with respect to earlier reprocessing series is demonstrated in terms of polar motion coordinates. GNSS satellite clock corrections are validated in terms of completeness, Allan deviation, and precise point positioning (PPP) using terrestrial stations. In addition, the products herein were validated with Gravity Recovery and Climate Experiment (GRACE) precise orbit determination (POD) and Satellite Laser Ranging (SLR). The dataset is publicly available.

scholarly journals Precise Orbit Determination of FY-3C with Calibration of Orbit Biases in BeiDou GEO Satellites

2018 ◽  
Vol 10 (3) ◽  
pp. 382 ◽  
Author(s):  
Qiang Zhang ◽  
Xiang Guo ◽  
Lizhong Qu ◽  
Qile Zhao
Keyword(s):  
Orbit Determination ◽  
Precise Orbit Determination ◽  
Precise Orbit ◽  
Geo Satellites

Signal Biases Calibration for Precise Orbit Determination of the Chinese Area Positioning System using SLR and C-Band Transfer Ranging Observations

2016 ◽  
Vol 69 (6) ◽  
pp. 1234-1246
Author(s):  
Cao Fen ◽  
Yang Xuhai ◽  
Li Zhigang ◽  
Chen Liang ◽  
Feng Chugang
Keyword(s):  
Orbit Determination ◽  
Precise Orbit Determination ◽  
Comparison Method ◽  
Positioning System ◽  
Delay Model ◽  
Precise Orbit ◽  
Percentage Improvement ◽  
Geo Satellites ◽  
Signal Biases

In C-Band transfer measuring systems, the Precise Orbit Determination (POD) precision of Geostationary Earth Orbit (GEO) satellites is limited by signal biases such as the station delay biases, transponder delay biases, the ionospheric delay model bias, etc. In order to improve the POD precision, the signal biases of the Chinese Area Positioning System (CAPS) are calibrated using Satellite Laser Ranging (SLR) and C-Band Transfer Ranging (CBTR) observations. Since the Changchun SLR site and C-Band station are close to each other, the signal biases of the Changchun C-Band station are calibrated using the co-location comparison method. Then the signal biases of the other two CAPS C-Band stations, located in Linton and Kashi, are calibrated using the combined POD method, with the signal biases of the Changchun C-Band station being fixed. After the signal biases are calibrated, the RMS of the line-of-sight residuals of the Changchun SLR observations decrease by 0·4 m, with the percentage improvement being 75·19%.

Research on the impact factors of GRACE precise orbit determination by dynamic method

2018 ◽  
Vol 12 (3) ◽  
pp. 249-257 ◽  
Author(s):  
Nan-nan Guo ◽  
Xu-hua Zhou ◽  
Kai Li ◽  
Bin Wu
Keyword(s):  
Orbit Determination ◽  
Precise Orbit Determination ◽  
Sampling Interval ◽  
Satellite Clock ◽  
Position Accuracy ◽  
Precise Orbit ◽  
Clock Error ◽  
Leo Satellites ◽  
Satellite Clock Error

Abstract With the successful use of GPS-only-based POD (precise orbit determination), more and more satellites carry onboard GPS receivers to support their orbit accuracy requirements. It provides continuous GPS observations in high precision, and becomes an indispensable way to obtain the orbit of LEO satellites. Precise orbit determination of LEO satellites plays an important role for the application of LEO satellites. Numerous factors should be considered in the POD processing. In this paper, several factors that impact precise orbit determination are analyzed, namely the satellite altitude, the time-variable earth’s gravity field, the GPS satellite clock error and accelerometer observation. The GRACE satellites provide ideal platform to study the performance of factors for precise orbit determination using zero-difference GPS data. These factors are quantitatively analyzed on affecting the accuracy of dynamic orbit using GRACE observations from 2005 to 2011 by SHORDE software. The study indicates that: (1) with the altitude of the GRACE satellite is lowered from 480 km to 460 km in seven years, the 3D (three-dimension) position accuracy of GRACE satellite orbit is about 3∼4 cm based on long spans data; (2) the accelerometer data improves the 3D position accuracy of GRACE in about 1 cm; (3) the accuracy of zero-difference dynamic orbit is about 6 cm with the GPS satellite clock error products in 5 min sampling interval and can be raised to 4 cm, if the GPS satellite clock error products with 30 s sampling interval can be adopted. (4) the time-variable part of earth gravity field model improves the 3D position accuracy of GRACE in about 0.5∼1.5 cm. Based on this study, we quantitatively analyze the factors that affect precise orbit determination of LEO satellites. This study plays an important role to improve the accuracy of LEO satellites orbit determination.

scholarly journals APPARILLO: a fully operational and autonomous staring system for LEO debris detection

2021 ◽  
Author(s):  
Paul Wagner ◽  
Tim Clausen
Keyword(s):  
Orbit Determination ◽  
Space Debris ◽  
Imaging System ◽  
Tracking System ◽  
Precise Orbit Determination ◽  
Ccd Camera ◽  
Low Earth Orbit ◽  
Laser Ranging ◽  
Distance Measurements ◽  
Initial Orbit Determination

AbstractFor safe operation of active space crafts, the space debris population needs to be continuously scanned, to avoid collisions of active satellites with space debris. Especially the low Earth orbit (LEO) shows higher risks of collisions due to the highest density of orbital debris. Laser ranging stations can deliver highly accurate distance measurements of debris objects allowing precise orbit determination and more effective collision avoidance. However, a laser ranging station needs accurate a priori orbit information to track an orbital object. To detect and track unknown orbital objects in LEO, here, a passive optical staring system is developed for autonomous 24/7 operation. The system is weather-sealed and does not require any service to perform observations. To detect objects, a wide-angle imaging system with 10° field of view equipped with an astronomical CCD camera was designed and set up to continuously observe the sky for LEO objects. The system can monitor and process several passing objects simultaneously without limitations. It automatically starts an observation, processes the images and saves the 2D angular measurements of each object as equatorial coordinates in the TDM standard. This allows subsequent initial orbit determination and handover to a laser tracking system. During campaigns at twilight the system detected up to 36 objects per hour, with high detection efficiencies of LEO objects larger than 1 m3. It is shown that objects as small as 0.1 m3 can be detected and that the estimated precision of the measurements is about 0.05° or 7 × the pixel scale.

scholarly journals GLONASS precise orbit determination with identification of malfunctioning spacecraft

GPS Solutions ◽  
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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