无验潮测深中的GNSS定位影响因素分析及对策探讨

Analysis and Coping with the Effects of GNSS Positioning in Non-tidal Sounding

通过实测GNSS(global navigation satellite system)数据的动态差分后处理(post processed kinematic,PPK),对无验潮测深中的GNSS定位影响因素进行了分析,结果表明:(1)海面环境的多路径效应大于陆地环境,基准站多路径效应集中在0.15~0.3 m,而流动站则主要集中在0.3~0.5 m,对于多路径效应这类难以模型化的误差,可以通过观测环境的优化选择、GNSS接收机的软硬件升级和改良来削弱其影响。(2)粤港澳大湾区电离层较为活跃,尤其是在下午时段,当基准站距离船载移动站较远时,电离层影响的空间相关性明显降低,GNSSPPK定位方式无法很好地消减电离层延迟,测深结果受到影响较大,可以采取加设距离较近的基准站、合理安排作业时间等措施来缓解电离层延迟对GNSS定位的影响。

The non-tidal sounding method based on GNSS can improve the accuracy and efficiency of terrain surveying underwater.This paper processes the data and analyzes the main effects in GNSS positioning.The results show that:(1)The multipath effect of the base station is concentrated at 0.15~0.3 m,and the rover station is concentrated at 0.3~0.5 m,and the multipath effect of the sea surface environ⁃ment is greater than that of the land environment.Optimizing the observation environment and improving the software and hardware of GNSS receivers can be used to mitigate the im⁃pact of multipath effects which are difficult to be modeled.(2)The ionosphere is more active in the Guangdong-Hong Kong-Macao Greater Bay Area.When the reference station is far away from the shipborne mobile station,especially in the afternoon,the spatial correlation of the ionospheric influence is significantly reduced and the post processed kinematic posi⁃tioning method cannot effectively reduce the ionospheric delay,so that the sounding results are greatly affected.The effect of ionospheric delay in GNSS PPK positioning can be offset by adding closer reference stations,arranging work time reasonably or other processing technologies.