Discussion on Positioning Precision Improvement Plans of Twins-Satellites Navigation System in Low Latitude Area

Paper number

IAC-05-B3.P.02

Author

Mr. Weihua Ma, Northwestern Polytechnical University, China

Year

2005

Abstract

The current Chinese Twins-Satellites System (TSS) is a satellite communication and navigation system that consists of three satellites (two main satellites and one backup satellite) in Geostationary Earth Orbit (GEO) and one ground station, and provides positioning service for the users in mainland of China. But there are three main limitation with this system:1,it is a active system and its service delay time is long; 2, users must measure the altitude by themselves; 3, positioning precision in low latitude area is bad. Some mending plans has been put forward to solve the limitation 1 and 2, but unfortunately, the limitation 3 are often neglected. So the plans of improvement on the third limitation of TSS are discussed in this paper.

The four improvement plans based with the navigation information from TSS satellites, pseudo-satellites and altimeter are described, and the corresponding models of positioning calculation and navigation error are given firstly. It must be explained that pseudo-satellites are placed on aircraft such as unman air vehicles to enlarge the covering area and to use more freely than ground-based pseudo-satellites over ocean especially. Secondly, the Positioning Error Transfer Coefficient Matrix (PETCM) could be predigested because the magnitudes of user’s latitude and the inclinations of line-sights from the user to navigation satellites are small and big respectively in low latitude area. Thirdly, the key elements of predigested PETCM that effect the Geometric Dilution of Precision (GDOP) are analyzed, and then the GDOP changing character of each plan is concluded in theory easily. Finally, the digital simulations for each plan GDOP are finished.

The simulations results show that the plans with pseudo-satellites aiding the TSS could improve almost all users positioning precision except the ones whose latitude is same as the pseudo-satellite’s and have good application potential in low latitude area.

Abstract document

IAC-05-B3.P.02.pdf

Manuscript document

IAC-05-B3.P.02.pdf (🔒 authorized access only).

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