针对卫星信号高遮挡导致的可视卫星数少于4颗和卫星几何图形强度不佳,引入实时序贯算法解决了常规单历元方法仅采用当前观测方程平差时法矩阵秩亏的问题。同时,在导出常规单历元方法允许实际变形量与载波波长关系的基础上,从组合观测值波长逐步精化的角度出发提出了基于宽巷/窄巷组合观测值的改进单历元方法。该方法采用宽巷组合在无需双差模糊度搜索情况下可实现0.5 m以上变形量的正确提取,通过窄巷组合减弱观测值误差。小湾2号山梁高边坡GPS变形监测应用表明,基于实时序贯平差和组合观测值改进的方法较常规单历元法降低了卫星观测视场要求,增大了允许变形量并提高了监测精度。
Applicable requirements of the conventional single-epoch method were analyzed from the accuracy of initial value,the number of visible satellites,and the range of permissible deformation.Then the improved single-epoch method,which can process normal equations with rank deficient,was proposed for precise deformation monitoring at the condition of poor satellite visibility and geometry strength based on real-time sequential adjustment.Meanwhile,a novel single-epoch methodology employed with GPS-Ⅲ wide-lane/narrow-lane combinations,which can estimate directly sub-m-level deformation without ambiguity searching,was presented for overcoming limited condition of small deformation requirement in the conventional single-epoch method.Dual-frequency GPS deformation monitoring application results of the Number Two steep slope at Xiaowan hydropower station showed that the modified single-epoch method,which improved deformation monitoring precision,reduced the requirement for satellite visibility and increased the range of permissible deformation using the sequential adjustment and dual-frequency wide-lane/narrow-lane combinations,was able to be well applied to precise deformation monitoring of engineering with limited conditions.