Three satellites enhanced positioning method for AGNSS

In order to improve the positioning performance of assisted Global Navigation Satellite System (ANGSS) and to implement effective positioning with imperfect positioning condition, a position method was studied under the condition of only three visible satellites. In this 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 showed that the positioning performance was better with the interval of two observations increasing. When the length of interval time was 2 min, the positioning accuracy was up to 2.22 m under the condition of no overlapped satellites, and the accuracy was 3.21 m under overlapped one satellite, and the accuracy was 16.76 m under overlapped two satellites, and the accuracy was 38.72 m. The positioning accuracy could meet the needs of the users for position, and the AGNSS positioning performance was enhanced.