非差模型与双差模型的定位精度比较

Difference of positioning precision for un-difference method and double difference method

为了分析高精度GNSS数据处理中常用的双差模型和非差模型定位性能的差异,选取ITRF核心站组成长度不同但相对位置长期不变的基线,对2013年全年的有效数据分别采用两种模型进行解算,分析两者的相对坐标差异。结果表明:全年数据的非差解与双差解相对坐标的三维偏差序列的标准差达到8.2 mm,非差解与双差解存在定位偏差;非差解的相对坐标全年数据时间序列的平均标准差是(5.6,4.5,5.4) mm,而双差解是(3.4,3.1,4.0) mm,双差模型的解算精度和稳定性整体优于非差模型;随基线的增长,双差模型的差异呈现累积性,而非差模型的差异基本无变化,如42 m超短基线STJ2-STJO非差解和双差解全年数据的标准差分别为(6.2,4.8,5.7) mm和(3.0,2.9,3.0) mm,而487 km长基线HERS-WSRT则是(5.7,4.5,5.4) mm和(4.7,2.8,4.7) mm。

In order to analyze the difference of the positioning performance of the double-difference (DD) model and the un-difference (UD) model which are commonly used in the high-precision GNSS data processing, the ITRF core stations are selected to form the baselines with different lengths but the relative positions remain immutably. Two models are used respectively to calculating the continuous valid data for all of 2013, and then the difference of relative coordinates are analyzed. The result shows that the standard deviation (STD) of the three-dimension deviation sequence of UD and DD reaches 8.2 mm, means that the DD model and UD model exist positioning deviation. The average STD of the relative coordinate time series of UD solution is (5.6, 4.5, 5.4) mm, while the DD solution is (3.4, 3.1, 4.0) mm, it should be rather obvious that the accuracy and stability of the DD model are better than the UD model. Along with the growth of the baseline, the difference of DD solution is cumulative, whereas the difference of UD solution is mainly no change, such as the STD of UD and DD of the 42 m short baseline STJ2-STJO are respectively (6.2,4.8,5.7) mm and (3.0,2.9,3.0) mm, and the 487 km long baseline HERS-WSRT are (5.7,4.5,5.4) mm and (4.7,2.8,4.7) mm.