长距离高精度GPS跨障碍高程传递的进一步研究

基于垂线偏差与高程基准无关的性质,由GPS水准实施垂线偏差的低通滤波,并精确估计其二次变化率,最终实现无重力数据的长距离、高精度跨障碍高程传递.对新方法的滤波及拟合过程进行数值分析,并将其截断误差转换为频域表达形式,再通过球谐函数建立代表误差与重力场阶方差的关系式.考虑到局部重力场的高频甚高频差异,根据GraaffHunfer经验公式和不同地形类别的代表误差统计值,将Tscherning-Rapp模型改造为区域阶方差模型,以精确估计具体地形条件下的代表误差.杭州湾大桥跨海高程控制测量的实验结果与模拟分析一致:31 km跨海高程传递成果与独立的一等几何水准比较,最大较差19mm,优于二等几何水准精度.

Further Studies of the Precise Long-distance GPS Height Transference across Obstacle

Based on the independence of vertical deflection and height datum, a new method was offered for the precise long-distance height transference across obstacle without gravity data, in which GPS leveling has become a low-pass filter for vertical deflection and its second order change rate has been evaluated accurately. Numerical analysis was done for filtering and fitting in the new method, and its truncation error was converted into frequency domain. Consequently, the correlation was acquired between the representation errors and the geopotential degree-variances through spherical harmonic expansion. Considering the difference of regional earth's gravity fields in high and very high frequency bands, the Tscherning-Rapp model was modified as regional geopotential degree-variance model in order to evaluate accurately the representation errors corresponding to all kinds of topography, by using "Graaff Hunfer" experiential formula and statistical coefficients of representation errors with topographic classifications. The experiment of height control survey across 31 km width was done for Hangzhou Bay Bridge. The result was in accordance with the simulation. It was compared with the first order leveling, and the maximum difference was 19 mm. The precision was higher than the second order leveling.