LEO星座增强GNSS的精密单点定位初步分析

本文选取GPS系统和Iridium系统,采用数学仿真技术初步分析了LEO星座对GNSS在精密单点定位中的增强作用。在仿真了BJFS站GPS和Iridium观测数据的基础上进行Iridium增强GPS的伪动态下精密单点定位实验,结果表明:与GPS单系统相比,GPS+Iridium双系统的可视卫星数平均增加1.5颗,GDOP值和PDOP值降低0.25左右;Iridium增强GPS后PPP滤波矩阵的条件数快速减小,提升了PPP滤波矩阵的稳定性,提高了天顶U方向的定位精度,从而提高了三维的定位精度,PPP收敛时间缩短了30%以上;采用单差MW法固定PPP模糊度,分别以Ratio=1.5、3、5作为模糊度固定成功的指标,并与模糊度仿真值对比,PPP模糊度首次固定成功所需的时间缩短40%以上。

Precise Point Positioning Primary Analysis of GNSS Enhanced with LEO Constellation

This paper analyzes the LEO constellation’s enhancement effect on GNSS’s precise point positioning(PPP), adopting mathematical simulation technology and taking the GPS system and the Iridium system as examples. Based on the emulational observation data of the GPS and Iridium, taking BJFS station as an example, pseudo- kinematic precise point positioning experiment is performed. The test results show that, compared with the GPS single system, the number of visible satellites of the GPS+Iridium dual system increases by an average of 1.5. The GDOP value and the PDOP value decrease by about 0.25. With Iridium enhanced GPS, the condition number of PPP filtration matrix reduces rapidly and the stability of PPP filtration is promoted; the positioning accuracy of the zenith U-direction, along with the three-dimensional positioning accuracy; the PPP convergence time is shortened by 30% or more and single-difference MW method is adopted to fix the PPP ambiguity. With Ratio =1.5, 3, 5 as an index of ambiguity fixed successfully, and compared with the emulational value of ambiguity, the time required for the first successful fixing of PPP ambiguity is shortened by 40% or more.