随着Galileo卫星系统的全面建成,多频Galileo观测值提供了更低噪声和更长波长的观测值组合,从而为Galileo瞬时精密单点定位(precise point positioning,PPP)模糊度固定(ambiguity resolution,AR)提供良好的条件.从三频无电离层组合观测模型出发,重点分析了Galileo各个频点观测值组合的噪声放大因子,并基于 15个MGEX(multi-GNSS experiment)测站 10天的观测数据评估了不同频率组合的Galileo瞬时PPP-AR定位精度.结果表明:在位置精度衰减因子(position dilution of precision,PDOP)较差时(PDOP=2.3),采用Galileo E1/E5a/E6频率的瞬时PPP-AR在东、北和天方向的均方根(root mean square,RMS)分别为0.16 m、0.19 m和 0.45 m,与Galileo E1/E5a/E5b瞬时PPP-AR定位解相比,在3个方向分别提高了约40%、38%和32%.以上结果表明,采用Galileo E1/E5a/E6组合对瞬时PPP-AR的定位精度有较大提升,因此当用户的全球导航卫星系统(global navigation satellite system,GNSS)接收机能接收到Galileo E1/E5a/E6频点时,建议采用这三组频点进行定位.
Performance Evaluation of the Multi-frequency Galileo Precise Point Positioning with Instantaneous Ambiguity Resolution
With the full completion of the Galileo satellite system,the combination of observations with lower noise and longer wavelengths can be provided by multi-frequency Galileo observations.Therefore,it is possible to achieve Gali-leo instantaneous precision point positioning(PPP)with am-biguity resolution(AR).Based on the triple-frequency iono-sphere-free combination observation model,we analyze the noise amplification factors of Galileo observations with dif-ferent frequencies.Experimenting on the observation data from 15 multi-GNSS experiment(MGEX)stations in 10 days,the positioning performance of Galileo instantaneous PPP-AR is assessed with different frequency combination.When the position dilution of precision(PDOP)is weak(PDOP=2.3),the results indicate that the root mean square(RMS)of Galileo E1/E5a/E6 for east,north and up compo-nents are 0.16 m,0.19 m and 0.45 m,respectively.Com-pared with the solutions of Galileo E1/E5a/E5b,the Galileo E1/E5a/E6 shows an improvement of approximately 40%,38%and 32%for east,north and up components,respective-ly.Therefore,the Galileo E1/E5a/E6 can bring a significant improvement in the instantaneous PPP-AR,and we suggest that these three signals should be used for positioning if the Galileo E1/E5a/E6 can be tracked by the user's global navi-gation satellite system(GNSS)receiver.
precise point positioningGalileo navigation sys-temsingle epochinstantaneous ambiguity resolutionwide-lane ambiguity resolution
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