Abstract:A position method was studied under the condition of only three visible satellites in this paper in order to improve the positioning performance of assisted Global Navigation Satellite System (ANGSS) and to implement effective positioning with imperfect positioning condition. In the research

AGNSS positioning structure was used to capture satellite more quickly and to provide assisted data. The positioning results were calculated by the combination of double-observation data

then the influence of no overlapped satellites

overlapped satellites and the length of double-observation interval time on the dilution of precision (DOP)

positioning performance and confidence were analyzed. The positioning results were showed that the positioning performance was getting better and better with the interval of two observations increasing. When the length of interval time was 2min

the positioning accuracy was up to 2.22m under the condition of no overlapped satellites

and the accuracy was 3.21m under overlapped one satellite

and the accuracy was 16.76m under overlapped two satellites

and the accuracy was 38.72m. The positioning accuracy could meet the needs of the users for position

and the AGNSS positioning performance was enhanced.