BDS实时精密动态定位最优观测值弹性选取方法

Flexible observation selection of precise BDS real-time kinematic positioning

传统的BDS精密动态定位的处理方法通常是根据基线长度的经验阈值来确定采用原始观测值或无电离层(IF)组合观测值,而不同区域、不同时间的电离层延迟是不同的,在基线长度阈值固定的情况下很难得到最优解,尤其是在基线长度连续变化的动态定位中。本文提出了一种最优观测值弹性选取(FOS)方法用于动态基线的BDS实时定位,新方法基于不同观测值的测量噪声和双差观测值电离层残差的关系确定基线解的最优观测值。当电离层残差大于IF观测值测量噪声时,IF方法将优于原始B1观测值,反之,B1观测值将更优。静态测试结果表明,FOS方法的定位结果相对于B1方法在E、N、U方向上分别提高了约9.6%、7.5%和11.4%,相对于IF方法,精度分别提高了8.6%、9.9%和12.2%;相对于B1和IF方法,FOS方法在动态测试E、N、U方向上分别提高了11.1%、13.7%、17.0%和8.3%、10.7%、13.8%,模糊度固定率分别提高了16.9%和10.2%。

Conventional processing method of BDS precise kinematic positioning is usually based on the experience threshold of baseline length to determine to use the raw or the ionospheric-free(IF)combination observation.However,the ionospheric delay is different at different regions and different time,it is difficult to obtain the optimal solution with the fixed threshold of baseline length,especially in kinematic positioning with the continuously change of baseline length.In this paper,we presented a new method that is flexible observation selection(FOS)for BDS real-time positioning for baselines with a variable lengths.The FOS method is based on the noise of different observations of the receiver and the size of the double-difference ionospheric residuals,and determining the optimal observation of baseline solution by the relationship of the ionospheric delay residual and the measurement noise.When the ionospheric residual is greater than the observed noise of the IF observation,the results of the IF method are better than those of the raw B1 observations,otherwise the results of the B1 observations are better.The results in the static test show that the positioning performance of the FOS method in E,N,and U directions are improved by about 9.6%,7.5%and 11.4%with respect to the B1 method,respectively,while compared with the IF method are 8.6%,9.9%and 12.2%.The positioning bias in kinematic test of the FOS method compared with B1 and IF methods are improved by about 11.1%,13.7%,17.0%,and 8.3%,10.7%and 13.8%,respectively,and the ambiguity resolution(AR)rate are increased by 16.9%and 10.2%.