2. IMPROVING THE ACCURACY IN PROCESSING GNSS DATA BASED ON PRECISE EPHEMERIS

Tóm tắt

This paper presents for using precise ephemeris to improve point positioning accuracy when processing GNSS data. The experimental GNSS network locates in Dak Nong province. It consists of 13 points, of which 3 points are control points for coordinates and height. The shortest baseline of the GNSS network is 2.5 km, the longest is 68.5 km and the average is 34.3 km. The data of the GNSS network is processed in two ways: Option one is to use broadcast ephemeris; Option two is to use precise ephemeris. Research results show that the error of point positioning of option two is smaller than option one, respectively. The minimum value of this error is 0 mm, the maximum is 3 mm and the average is 1 mm. There is not much difference in the height error of the points when adjusting according to the two options. The biggest difference is 2 mm, the smallest is 0 mm and the average is 1 mm. The accuracy of the GNSS point positioning depends on how the data is processed. The accuracy of point positioning when using a precise ephemeris is higher than that of using a broadcast ephemeris. Currently, exacting precise ephemeris from the internet is easy. Precise ephemeris is updated quickly in the software. The accuracy and reliability of the adjustment results are high. Therefore, precise ephemeris should be used during GNSS data processing.