GPS/GLONASS Combined Precise Point Positioning with Receiver Clock Modeling
GPS/GLONASS Combined Precise Point Positioning with Receiver Clock Modeling
复制标题
GPS/GLONASS 将精确单点定位与接收器时钟建模相结合
DOI：
10.3390/s150715478
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发表时间：
2015-07-01
期刊：
影响因子：
3.9
通讯作者：
Guo, Fei
中科院分区：
文献类型：
--
作者：
Wang, Fuhong;Chen, Xinghan;Guo, Fei
研究表明，接收机钟差建模可以降低接收机钟差、站高和对流层天顶延迟等参数之间的相关系数。将接收机钟差建模引入GPS/GLONASS组合精密单点定位（PPP）中，旨在更好地分离接收机钟差和台站坐标，从而提高定位精度。首先简要介绍了GPS/GLONASS观测方程、随机模型和接收机时钟模型等基本数学模型。然后，从几个IGS站配备高稳定性原子钟的数据集用于运动学PPP测试。为了研究PPP的性能，包括定位精度和收敛时间，用不同的方案处理了从这些IGS台站检索的为期一周（2014年1月1日至7日）的GPS/GLONASS数据。结果表明，定位精度以及收敛时间可以受益于接收机时钟建模。这在垂直分量上尤其明显。统计RMS表明，三维定位精度的平均提高高达30%-40%。有时，它甚至达到60%以上的特定车站。与GPS单点定位方法相比，无论是否对接收机钟差进行建模，GPS/GLONASS组合的单点定位方法的解都要好得多，表明在GPS卫星数量不足或几何条件较差的情况下，增加GLONASS卫星可以显著提高定位精度和可靠性。除了接收机时钟建模，不同的系统间定时偏差（ISB）模型的影响进行了研究。对于具有相当好的几何形状的足够数量的卫星的情况下，PPP性能不受ISB模型的严重影响，由于ISB和其他参数之间的低相关性。然而，ISB模型的细化削弱了坐标和ISB估计值之间的相关性，最终在观测条件较差的情况下提高了PPP性能。
Research has demonstrated that receiver clock modeling can reduce the correlation coefficients among the parameters of receiver clock bias, station height and zenith tropospheric delay. This paper introduces the receiver clock modeling to GPS/GLONASS combined precise point positioning (PPP), aiming to better separate the receiver clock bias and station coordinates and therefore improve positioning accuracy. Firstly, the basic mathematic models including the GPS/GLONASS observation equations, stochastic model, and receiver clock model are briefly introduced. Then datasets from several IGS stations equipped with high-stability atomic clocks are used for kinematic PPP tests. To investigate the performance of PPP, including the positioning accuracy and convergence time, a week of (1–7 January 2014) GPS/GLONASS data retrieved from these IGS stations are processed with different schemes. The results indicate that the positioning accuracy as well as convergence time can benefit from the receiver clock modeling. This is particularly pronounced for the vertical component. Statistic RMSs show that the average improvement of three-dimensional positioning accuracy reaches up to 30%–40%. Sometimes, it even reaches over 60% for specific stations. Compared to the GPS-only PPP, solutions of the GPS/GLONASS combined PPP are much better no matter if the receiver clock offsets are modeled or not, indicating that the positioning accuracy and reliability are significantly improved with the additional GLONASS satellites in the case of insufficient number of GPS satellites or poor geometry conditions. In addition to the receiver clock modeling, the impacts of different inter-system timing bias (ISB) models are investigated. For the case of a sufficient number of satellites with fairly good geometry, the PPP performances are not seriously affected by the ISB model due to the low correlation between the ISB and the other parameters. However, the refinement of ISB model weakens the correlation between coordinates and ISB estimates and finally enhance the PPP performance in the case of poor observation conditions.