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Precise Orbit Determination Of Leo Satellites Based On Dual-Frequency Gps
Published in Zhengming Wang, Dongyun Yi, Xiaojun Duan, Jing Yao, Defeng Gu, Measurement Data Modeling and Parameter Estimation, 2016
Zhengming Wang, Dongyun Yi, Xiaojun Duan, Jing Yao, Defeng Gu
SLR measures the distance from a laser tracking station to a satellite. It can achieve high accuracy of measurement because of the relatively small atmospheric effect on the laser pulse transmission. With all advances in modern tracking technology, the current measurement accuracy of SLR has reached 5-10 mm. SLR can provide precise, unambiguous distance observations from tracking stations to a satellite. By the fusion of these observations and the satellite orbit dynamic model, we can determine the satellite orbit. The main limitations of SLR systems are the sparse geographical distribution of tracking stations and the demanding weather conditions. Presently, there are more than 40 laser ranging stations located in the northern hemisphere, while there are fewer stations in the southern hemisphere [1].
On-orbit geometric calibration of satellite laser altimeters using infrared detectors and corner-cube retroreflectors
Published in International Journal of Digital Earth, 2023
Junfeng Xie, Ren Liu, Xiaomeng Yang, Fan Mo, Fangxu Zhang, Lirong Liu
A laser altimeter is affected by satellite jitter during the launch process, sudden changes in the orbital operating environment, and thermal effects during measurement, which lead to certain changes in satellite laser the pointing angle and ranging, resulting in a system error in the pointing angle and ranging. Assuming that the altitude of a satellite orbit is 500 km and the laser pointing angle error is 30 arcsec, there will be a laser footprint positioning error of 73 m, and when the footprint is on terrain with a slope of 1°, it will produce an elevation measurement error of 1.3 m (Luthcke et al. 2000). The satellite laser ranging error magnitude is usually small (decimeter level), which will directly contribute to errors in laser elevation measurements. On-orbit satellite laser geometric calibration is the main means of eliminating or reducing laser pointing angle and ranging errors and can improve satellite laser footprint positioning accuracy. In this way, high-precision laser data are provided for satellite lasers application in various fields, ensuring the accuracy and effectiveness of the application results.
Connected Geomatics in the big data era
Published in International Journal of Digital Earth, 2018
High-precision real-time navigation and positioning has always been an important issue for Geomatics. Nowadays, the direct real-time accuracy of the Global Positioning System is approximately 5 m. Many ground-based Continuously Operating Reference Stations (CORS) have been constructed to improve the real-time positioning accuracy to semi-meter level in recent years. However, it is very difficult to construct CORS in many parts of the world, especially in mountainous and oceanic areas. This means that global real-time precise LBS is not yet available. Using continuous records from on-board global navigation satellite system (GNSS) receivers equipped on LEO satellites, in combination with an existing ground-based augmentation system, the global real-time positioning precision of the existing satellite navigation system could be improved. However, the following problems must be solved: Correction of the navigation satellite’s ephemeris and clock errors based on observations of LEO satellites;Precision of the single-point positioning technique in combination with signals from LEO satellites/navigation satellites;Combined orbit determination algorithms for LEO and navigation satellites;Combined adjustment of inter-satellite laser ranging and navigation data;Optimal design of the LEO navigation constellation.
Improved orbit prediction of LEO objects with calibrated atmospheric mass density model
Published in Journal of Spatial Science, 2019
Junyu Chen, Jianli Du, Jizhang Sang
The great majority of satellites are launched into the LEO region with altitudes of 300–1500 km (Montenbruck and Gill 2012). The accuracy of satellite orbit determination can be a few centimetres when high-precision GNSS (Global Navigation Satellite System) and SLR (Satellite Laser Ranging) data are available, and such high accuracy is essential for many geodetic and geophysical applications, such as Earth gravitational model determination and reference frame determination (Reigber et al. 2004, Tapley et al. 2004, Montenbruck and Ramos-Bosch 2008).