高纬度BDS/GPS PPP中截止高度角最优选取

Optimal selection of the elevation cutoff angle in BDS/GPS PPP at high-latitude regions

针对高纬度地区单BDS定位中,可见卫星数数量少,卫星高度角低而无法提供稳定可用的定位导航服务的问题,提出通过选择最优的截止高度角,利用BDS和GPS的组合观测值来改善卫星观测条件及提高高纬度地区PPP的天顶对流层延迟估计精度和定位精度的方法。文中比较了5°、10°和15°截止高度角下的卫星观测条件,以及基于3种对流层延迟改正模型的PPP天顶对流层延迟估计精度和定位精度。结果表明:在5°截止高度角下,不仅可见卫星个数、卫星可视时间和观测数据量更多,天顶对流层延迟估计精度和高程定位精度也通常是最高的,且水平定位精度在2cm以内,高程定位精度在5cm以内。这一结论为将来高纬度地区的BDS/GPS定位研究提供了合适的截止高度角和精度参考。

Due to the lack of enough visible satellites and lower elevation angles between receiver and satellites in single BDS positioning,we select an optimal elevation cutoff angle,and then it is able to obtain more visible satellites,modify the geometric configuration of satellites constellation and improve the accuracies of the ZTD estimating and BDS/GPS PPP solutions with the combination of BDS and GPS observations.In this paper,the comprehensive influences of 5°,10°and 15°elevation cutoff angles are assessed for satellites constellation,ZTD estimating and BDS/GPS PPP solutions based on three tropospheric delay correction models.From experimental results,it is shown that:under elevation cutoff angle of 5°,not only the most valid observations,number of visible satellites and visible period of satellites can been obtained,but also the accuracies of modelbased ZTDs and BDS/GPS PPP solutions in vertical direction are always the best in general high-latitude circumstances,among them,the horizontal and vertical errors do not exceed 2cm and 5cm,respectively.This conclusion can provide suitable reference of elevation cutoff angle and positioning precision for high-latitude BDS/GPS researchers.