Abstract: This paper discusses the accuracy of autonomous orbit deter- mination for near-earth satellites by using GPS and related issues.At first, a relation between the orbit accuracy and the equivalent 3-dimension posi- tion accuracy is established,the potential orbit accuracy which can be obtained by C/A-code users is calculated then by using this relation.Results show that a ten-meter level orbit accuracy can be achieved for onboard C/A-code users.

Key words: Global position system, Accuracy analysis, Method