scholarly journals Performance Comparison of KOMPSAT-5 Precision Orbit Determination with GRACE

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Kyoung-Min Roh ◽  
Yoola Hwang
Keyword(s):  
Orbit Determination ◽  
Hardware Design ◽  
Performance Comparison ◽  
Gps Receiver ◽  
Ring Antenna ◽  
Orbital Position ◽  
Grace Satellites ◽  
Precision Orbit Determination ◽  
Gravity Recovery ◽  
Reduced Dynamic

The Korean Multipurpose Satellite-5 (KOMPSAT-5) launched on 22 August 2013 was equipped with a global positioning system (GPS) receiver for precision orbit determination (POD). Even though the GPS receiver of KOMPSAT-5 shares the same heritage as the BlackJack receiver onboard in Gravity Recovery and Climate Experiment (GRACE) satellites, KOMPSAT-5 has a lower orbital position accuracy (~10 cm) compared with GRACE (~2 cm). The reduced dynamic and kinematic methods are applied for POD of KOMPSAT-5 and GRACE to investigate the GPS observation quality due to the satellite operation concept and hardware design. The results are analyzed in terms of the number of observations and their spatial distribution, GPS signal quality, and orbital position accuracies. The results show that the frequent attitude maneuvers of KOMPSAT-5 affect the quality of the GPS signals and solutions obtained from the kinematic method compared with that determined from the reduced-dynamic method. The onboard patch GPS antenna installed in KOMPSAT-5 and its geometrical position resulted in more erratic measurement residuals by 140% compared with the choke ring antenna of GRACE. The POD accuracy is dependent on the hardware design and regular attitude tilting for the synthetic aperture radar (SAR) imaging even though the same GPS receiver performances.

scholarly journals Sensitivity of the Gravity Model and Orbital Frame for On-board Real-Time Orbit Determination: Operational Results of GPS-12 GPS Receiver

2019 ◽  
Vol 11 (13) ◽  
pp. 1542
Author(s):  
Eunhyouek Kim ◽  
Seungyeop Han ◽  
Amer Mohammad Al Sayegh
Keyword(s):  
Real Time ◽  
Gravity Model ◽  
Orbit Determination ◽  
Low Earth Orbit ◽  
Observation Data ◽  
Gps Receiver ◽  
Champ Satellite ◽  
Earth Gravity ◽  
Earth Gravity Model ◽  
Gravity Recovery

This paper describes the sensitivity of both the orbital frame domain selection and the gravity model on the performance of on-board real-time orbit determination. Practical error sources, which affect the navigation solution of spaceborne global positioning system (GPS) receivers, are analyzed first. Then, a reasonable orbital frame (radial, in-track, cross-track (RIC)) is proposed to clearly represent the characteristics of the error in order to improve the performance of the orbit determination (OD) logic. In addition, the sensitivity of the gravity model affecting the orbit determination logic is analyzed by comparison with the precise orbit ephemeris (POE) of the Challenging Minisatellite Payload (CHAMP) satellite, and it is confirmed that the Gravity Recovery And Climate Experiment (GRACE) Gravity Model 03 (GGM03) outperforms the Earth Gravity Model 1996 (EGM96). The effects of both proposed orbit frames and the gravity model on the orbit determination logic are verified using a GPS simulator and observation data from the CHAMP satellite. Moreover, the practical performance of on-board real-time orbit determination logic is verified by updating the software of the spaceborne GPS receiver, GPS-12, on DubaiSat-2 operating at low Earth orbit (LEO). The results show that the position accuracy of on-board real-time orbit determination logic in GPS-12 is improved by 59%, from 12.6 m (1 σ) to 5.1 m (1 σ), after applying the proposed methods. The velocity accuracy is also improved by 57%, from 13.7 mm/s (1 σ) to 5.9 mm/s (1 σ).

scholarly journals Improving the GRACE Kinematic Precise Orbit Determination Through Modified Clock Estimating

Sensors ◽  
2019 ◽  
Vol 19 (19) ◽  
pp. 4347 ◽  
Author(s):  
Zhou ◽  
Jiang ◽  
Chen ◽  
Li ◽  
Liu
Keyword(s):  
Orbit Determination ◽  
Precise Orbit Determination ◽  
Radial Component ◽  
Allan Deviation ◽  
Gps Receiver ◽  
Gps Satellites ◽  
Grace Data ◽  
Global Positioning ◽  
The Stability ◽  
Gravity Recovery

Utilizing global positioning system (GPS) to determine the precise kinematic orbits for the twin satellites of the Gravity Recovery and Climate Experiment (GRACE) plays a very important role in the earth’s gravitational and other scientific fields. However, the orbit quality is highly depended on the geometry of observed GPS satellites. In this study, we propose a kinematic orbit determination method for improving the GRACE orbit quality especially when the geometry of observed GPS satellites is weak, where an appropriate random walk clock constraint between adjacent epochs is recommended according to the stability of on-board GPS receiver clocks. GRACE data over one month were adopted in the experimental validation. Results show that the proposed method could improve the root mean square (RMS) by 20–40% in radial component and 5–20% in along and cross components. For those epochs with position dilution of precision (PDOP) larger than 4, the orbits were improved by 50–70% in radial component and 17–50% in along and cross components. Meanwhile, the Allan deviation of clock estimates in the proposed method was much closer to the reported Allan deviation of GRACE on-board oscillator. All the results confirmed the improvement of the proposed method.

ICESat-2 Precision Orbit Determination Performance

2020 ◽  
Author(s):  
Taylor Thomas ◽  
Scott Luthcke ◽  
Teresa Pennington ◽  
Joseph Nicholas ◽  
David Rowlands ◽  
...  
Keyword(s):  
Orbit Determination ◽  
Primary Data ◽  
Time Interval ◽  
Gps Receiver ◽  
Laser Altimeter ◽  
Precise Position ◽  
Inertial Space ◽  
Nasa Goddard Space ◽  
Force Modeling ◽  
Precision Orbit Determination

<p>The Ice, Cloud, and land Elevation Satellite-2 (ICESat-2) mission launched on September 15<sup>th</sup>, 2018, with the primary goal of measuring ice sheet topographic change. The fundamental measurement used to achieve mission science objectives is the geolocation of individual photon bounce points. Geolocation is computed as a function of three complex measurements: (1) the position of the laser altimeter instrument in inertial space, (2) the pointing of each of the six individual laser beams in inertial space, and (3) the photon event round trip travel time observation measured by the Advanced Topographic Laser Altimeter System (ATLAS) instrument. ICESat-2 Precision Orbit Determination (POD) is responsible for computing the first of these; the precise position of the laser altimeter instrument.</p><p>ICESat-2 carries two identical on-board GPS receivers, both manufactured by RUAG Space. Tracking data collected by GPS receiver #1 is used as the primary data source for generating POD solutions. POD is performed using GEODYN, NASA Goddard Space Flight Center’s state-of-the-art orbit determination and geodetic parameter estimation software, and a reduced-dynamic solution strategy is employed. The GPS-based POD solutions are calibrated and validated using independent Satellite Laser Ranging (SLR) data from ground-based tracking stations.</p><p>ICESat-2 mission requirements state that the POD solutions must have a one-sigma radial accuracy of 3 cm over a 24-hour time interval. Here we show that early mission ICESat-2 POD performance is exceeding mission requirements. We describe in-depth the ICESat-2 spacecraft macro-model, used for non-conservative force modeling, and the results from tuning of the associated parameters. Lastly, we show the iterated GPS receiver antenna phase center variation map solution and assess its impact on POD performance.</p>

scholarly journals GPS Based Reduced-Dynamic Orbit Determination for Low Earth Orbiters with Ambiguity Fixing

2015 ◽  
Vol 2015 ◽  
pp. 1-11 ◽  
Author(s):  
Yang Yang ◽  
Xiaokui Yue ◽  
Jianping Yuan
Keyword(s):  
Orbit Determination ◽  
Precise Determination ◽  
Low Earth Orbit ◽  
Carrier Phase Ambiguity ◽  
Performance Results ◽  
Gravity Recovery ◽  
Leo Satellite ◽  
Gps Observations ◽  
Reduced Dynamic

With the ever-increasing number of satellites in Low Earth Orbit (LEO) for scientific missions, the precise determination of the position and velocity of the satellite is a necessity. GPS (Global Positioning System) based reduced-dynamic orbit determination (RPOD) method is commonly used in the post processing with high precision. This paper presents a sequential RPOD strategy for LEO satellite in the framework of Extended Kalman Filter (EKF). Precise Point Positioning (PPP) technique is used to process the GPS observations, with carrier phase ambiguity resolution using Integer Phase Clocks (IPCs) products. A set of GRACE (Gravity Recovery And Climate Experiment) mission data is used to test and validate the RPOD performance. Results indicate that orbit determination accuracy could be improved by 15% in terms of 3D RMS error in comparison with traditional RPOD method with float ambiguity solutions.

scholarly journals A Second-Order Time-Difference Position Constrained Reduced-Dynamic Technique for the Precise Orbit Determination of LEOs Using GPS

2021 ◽  
Vol 13 (15) ◽  
pp. 3033
Author(s):  
Hui Wei ◽  
Jiancheng Li ◽  
Xinyu Xu ◽  
Shoujian Zhang ◽  
Kaifa Kuang
Keyword(s):  
Orbit Determination ◽  
Dynamic Models ◽  
Precise Orbit Determination ◽  
Second Order ◽  
Time Difference ◽  
Error Sources ◽  
Precise Orbit ◽  
Unmodeled Dynamic ◽  
Reduced Dynamic

In this paper, we propose a new reduced-dynamic (RD) method by introducing the second-order time-difference position (STP) as additional pseudo-observations (named the RD_STP method) for the precise orbit determination (POD) of low Earth orbiters (LEOs) from GPS observations. Theoretical and numerical analyses show that the accuracies of integrating the STPs of LEOs at 30 s intervals are better than 0.01 m when the forces (<10−5 ms−2) acting on the LEOs are ignored. Therefore, only using the Earth’s gravity model is good enough for the proposed RD_STP method. All unmodeled dynamic models (e.g., luni-solar gravitation, tide forces) are treated as the error sources of the STP pseudo-observation. In addition, there are no pseudo-stochastic orbit parameters to be estimated in the RD_STP method. Finally, we use the RD_STP method to process 15 days of GPS data from the GOCE mission. The results show that the accuracy of the RD_STP solution is more accurate and smoother than the kinematic solution in nearly polar and equatorial regions, and consistent with the RD solution. The 3D RMS of the differences between the RD_STP and RD solutions is 1.93 cm for 1 s sampling. This indicates that the proposed method has a performance comparable to the RD method, and could be an alternative for the POD of LEOs.

scholarly journals Grace Signal Filtering as a Means of Determining Equivalent Water Thickness in Poland

2012 ◽  
Vol 19 (1) ◽  
Author(s):  
Monika Biryło ◽  
Jolanta Nastula
Keyword(s):  
Amplitude Ratio ◽  
Raw Data ◽  
Signal Filtering ◽  
Filtering Algorithm ◽  
Equivalent Water Thickness ◽  
Grace Satellites ◽  
Gravity Variations ◽  
Gravity Recovery

AbstractIn the paper an Equivalent Water Thickness (EWT) determination as a way of observing gravity variations is described. Since raw data acquired directly from Gravity Recovery and Climate Experiment - GRACE satellites is unsuitable for analysis due to stripes occurrence, a filtering algorithm must be used. In this paper, authors are testing two isotropic (Gauss, CNES/GRGS) filters and two anisotropic filters (Wiener- -Kolomogorov, ANS). Correlation, amplitude ratio, and modification were determined as well as maps were generated.

Comparison of the real-time Precise Orbit Determination for LEO between Kinematic and Reduced-Dynamic modes

Measurement ◽  
2021 ◽  
pp. 110224
Author(s):  
Zhiyu Wang ◽  
Zishen Li ◽  
Liang Wang ◽  
Ningbo Wang ◽  
Yang Yang ◽  
...  
Keyword(s):  
Real Time ◽  
Orbit Determination ◽  
Precise Orbit Determination ◽  
The Real ◽  
Precise Orbit ◽  
Reduced Dynamic
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