scholarly journals Towards the GEOSAT Follow-On Precise Orbit Determination Goals of High Accuracy and Near-Real-Time Processing

2006 ◽  
Author(s):  
Frank Lemoine ◽  
Nikita Zelensky ◽  
Douglas Chinn ◽  
Brian Beckley ◽  
John Lillibridge
Keyword(s):  
Real Time ◽  
Orbit Determination ◽  
Precise Orbit Determination ◽  
High Accuracy ◽  
Real Time Processing ◽  
Time Processing ◽  
Precise Orbit

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

scholarly journals Real-Time Kinematic Precise Orbit Determination for LEO Satellites Using Zero-Differenced Ambiguity Resolution

2019 ◽  
Vol 11 (23) ◽  
pp. 2815 ◽  
Author(s):  
Xingxing Li ◽  
Jiaqi Wu ◽  
Keke Zhang ◽  
Xin Li ◽  
Yun Xiong ◽  
...  
Keyword(s):  
Real Time ◽  
Ambiguity Resolution ◽  
Orbit Determination ◽  
Precise Orbit Determination ◽  
The Real ◽  
Precise Orbit ◽  
Ambiguity Fixing ◽  
Real Time Kinematic ◽  
Leo Satellites ◽  
Fixed Solution

The rapid growing number of earth observation missions and commercial low-earth-orbit (LEO) constellation plans have provided a strong motivation to get accurate LEO satellite position and velocity information in real time. This paper is devoted to improve the real-time kinematic LEO orbits through fixing the zero-differenced (ZD) ambiguities of onboard Global Navigation Satellite System (GNSS) phase observations. In the proposed method, the real-time uncalibrated phase delays (UPDs) are estimated epoch-by-epoch via a global-distributed network to support the ZD ambiguity resolution (AR) for LEO satellites. By separating the UPDs, the ambiguities of onboard ZD GPS phase measurements recover their integer nature. Then, wide-lane (WL) and narrow-lane (NL) AR are performed epoch-by-epoch and the real-time ambiguity–fixed orbits are thus obtained. To validate the proposed method, a real-time kinematic precise orbit determination (POD), for both Sentinel-3A and Swarm-A satellites, was carried out with ambiguity–fixed and ambiguity–float solutions, respectively. The ambiguity fixing results indicate that, for both Sentinel-3A and Swarm-A, over 90% ZD ambiguities could be properly fixed with the time to first fix (TTFF) around 25–30 min. For the assessment of LEO orbits, the differences with post-processed reduced dynamic orbits and satellite laser ranging (SLR) residuals are investigated. Compared with the ambiguity–float solution, the 3D orbit difference root mean square (RMS) values reduce from 7.15 to 5.23 cm for Sentinel-3A, and from 5.29 to 4.01 cm for Swarm-A with the help of ZD AR. The SLR residuals also show notable improvements for an ambiguity–fixed solution; the standard deviation values of Sentinel-3A and Swarm-A are 4.01 and 2.78 cm, with improvements of over 20% compared with the ambiguity–float solution. In addition, the phase residuals of ambiguity–fixed solution are 0.5–1.0 mm larger than those of the ambiguity–float solution; the possible reason is that the ambiguity fixing separate integer ambiguities from unmodeled errors used to be absorbed in float ambiguities.

Real-time precise orbit determination for BDS satellites using the square root information filter

GPS Solutions ◽  
2019 ◽  
Vol 23 (2) ◽  
Author(s):  
Xiaolei Dai ◽  
Yidong Lou ◽  
Zhiqiang Dai ◽  
Yun Qing ◽  
Min Li ◽  
...  
Keyword(s):  
Real Time ◽  
Orbit Determination ◽  
Precise Orbit Determination ◽  
Square Root ◽  
Precise Orbit ◽  
Information Filter

scholarly journals A Three-Step Method for Determining Unhealthy Time Period of GPS Satellite Orbit in Broadcast Ephemeris and Its Preliminary Applications for Precise Orbit Determination

2019 ◽  
Vol 11 (9) ◽  
pp. 1098 ◽  
Author(s):  
Fei Ye ◽  
Yunbin Yuan ◽  
Baocheng Zhang ◽  
Bingfeng Tan ◽  
Jikun Ou
Keyword(s):  
Real Time ◽  
Orbit Determination ◽  
Traditional Method ◽  
Precise Orbit Determination ◽  
Satellite Orbit ◽  
Step Method ◽  
Precise Orbit ◽  
Broadcast Ephemeris ◽  
Time Period ◽  
Time Periods

Abnormal information of satellite orbits inevitably appears in the broadcast ephemeris. Failure to obtain unhealthy information on GPS satellite orbits in precise orbit determination (POD) degrades GPS service performance. At present, the reliable unhealthy information published by the Center for Orbit Determination in Europe (CODE) is usually used, but it has at least one-day latency, and the current level of unhealthy information cannot fully meet the requirements of rapid and real-time geodetic applications, especially for non-IGS (International global navigation satellite systems (GNSS) Service) analysis centers and BeiDou navigation satellite system (BDS) users. Furthermore, the unhealthy orbit information detected by the traditional method, which is based on the synchronized pseudo-range residuals and regional observation network, cannot meet the requirement of setting separate sub-arcs in POD. In view of these problems, we propose a three-step method for determining unhealthy time periods of GPS satellite orbit in broadcast ephemeris during POD to provide reliable unhealthy information in near-real time. This method is a single-epoch solution, and it can detect unhealthy time periods in each sampling of observation in theory. It was subsequently used to detect unhealthy time periods for satellites G09 and G01 based on the 111 globally distributed tracking stations in the IGS. The performance of the new method was evaluated using cross-validation. Based on the test results, it detected an orbital leap for G09 in the broadcast ephemeris from 09:59:42 to 14:00:42 on 25 August 2017. Compared to the traditional method, the unhealthy start time using the three-step method was in better agreement with the information provided by CODE’s satellite crux files. G01 did not appear to have an orbital leap on the specified date, but it was misjudged by the traditional method. Furthermore, compared to the traditional method, the three-step method can perform unhealthy time period detection for a satellite all day long. In addition, precise orbit determination for unhealthy satellites is realized successfully with the unhealthy orbit arc information identified in this study. Compared to the CODE orbit, the root mean square and standard deviation of the new method for G09 are less than 2 cm, and the three-step method shows an improvement in accuracy compared with the traditional method. From the above results, it can be seen that this study can provide a feasible approach to meet the real-time unhealthy time period detection requirements of a satellite orbit in a broadcast ephemeris during POD. Furthermore, compared to waiting for updates of CODE’s satellite crux files or for accumulating delayed observation data, it has the potential to provide additional information in the process of generating ultra-rapid/real-time orbits.

scholarly journals TerraSAR-X precise orbit determination with real-time GPS ephemerides

2012 ◽  
Vol 50 (5) ◽  
pp. 549-559 ◽  
Author(s):  
M. Wermuth ◽  
A. Hauschild ◽  
O. Montenbruck ◽  
R. Kahle
Keyword(s):  
Real Time ◽  
Orbit Determination ◽  
Precise Orbit Determination ◽  
Precise Orbit

scholarly journals Real-Time Precise Orbit Determination for LEO between Kinematic and Reduced-Dynamic with Ambiguity Resolution

Aerospace ◽  
2022 ◽  
Vol 9 (1) ◽  
pp. 25
Author(s):  
Zhiyu Wang ◽  
Zishen Li ◽  
Ningbo Wang ◽  
Mainul Hoque ◽  
Liang Wang ◽  
...  
Keyword(s):  
Real Time ◽  
Ambiguity Resolution ◽  
Orbit Determination ◽  
Fixed Ratio ◽  
Precise Orbit Determination ◽  
Low Earth Orbit ◽  
Integer Ambiguity ◽  
The Real ◽  
Precise Orbit ◽  
Reduced Dynamic

The real-time integer-ambiguity resolution of the carrier-phase observation is one of the most effective approaches to enhance the accuracy of real-time precise point positioning (PPP), kinematic precise orbit determination (KPOD), and reduced-dynamic precise orbit determination (RPOD) for low earth orbit (LEO) satellites. In this study, the integer phase clock (IPC) and wide-lane satellite bias (WSB) products from CNES (Centre National d’Etudes Spatiales) are used to fix ambiguity in real time. Meanwhile, the three models of real-time PPP, KPOD, and RPOD are applied to validate the contribution of ambiguity resolution. Experimental results show that (1) the average positioning accuracy of IGS stations for ambiguity-fixed solutions is improved from about 7.14 to 5.91 cm, with an improvement of around 17% compared to the real-time float PPP solutions, with enhancement in the east-west direction particularly significant, with an improvement of about 29%; (2) the average accuracy of the estimated LEO orbit with ambiguity-fixed solutions in the real-time KPOD and RPOD mode is improved by about 16% and 10%, respectively, with respect to the corresponding mode with the ambiguity-float solutions; (3) the performance of real-time LEO RPOD is better than that of the corresponding KPOD, regardless of fixed- or float-ambiguity solutions. Moreover, the average ambiguity-fixed ratio can reach more than 90% in real-time PPP, KPOD, and RPOD.

Real-Time, Autonomous, Precise Orbit Determination Using GPS

Navigation ◽  
2001 ◽  
Vol 48 (3) ◽  
pp. 155-168 ◽  
Author(s):  
David B. Goldstein ◽  
George H. Born ◽  
Penina Axelrad
Keyword(s):  
Real Time ◽  
Orbit Determination ◽  
Precise Orbit Determination ◽  
Precise Orbit ◽  
Time Autonomous
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