联合MGEX和iGMAS观测网多模GNSS数据确定地球自转参数

Multi- GNSS Processing for Earth Rotation Parameter Determination Using MGEX and iGMAS Data

地球自转参数是卫星精密定轨、高精度深空导航与定位等必不可少的重要基础数据。本文给出了联合MGEX和iGMAS观测网多模GNSS数据确定极移和日长变化等地球自转参数的基本原理与算法。在随机模型方面，为合理确定不同卫星系统如GPS、GLONASS和BDS观测数据问的权比，给出了基于方差分量估计的权比调节方法。在函数模型方面，充分顾及与测站相关的系统间偏差ISB和与频率相关的频间偏差IFB影响，通过设定附加参数予以估计，并分析了这两类参数的估计精度和稳定性。利用2014年12月份MGEX和iGMAS观测网的GPS／GLONASS／BDS数据，进行了地球自转参数确定的初步试验。计算结果表明：联合MGEX和iGMAS观测网数据，可在一定程度上提高ERP的确定精度。iGMAS数据的加入在极移X分量上提高约13％，极移Y分量上提高约7．5％，日长变化的精度提高约9．8％。利用方差分量估计可合理确定不同导航系统观测数据的权比，较按等权处理模式获得的地球自转参数结果精度和可靠性更高。BDS、GPS、GLONASS间存在系统偏差，其大小因测站和频率而异，总体变化较为平稳，稳定度在分米量级。

Earth rotation parameters （ERPs） are important basic data for satellite precise orbit determination （POD） , high - precision space navigation and positioning. In this paper, the theory and algorithm of ERPs including polar motion （PM） and length of day （ LOD） determination are presented using MGEX and iGMAS Multi - GNSS data. In order to balance the contribution of BDS, GPS and GLONASS to ERP determination, the variance component estimation （VCE） is used to get reasonable weight of Multi - GNSS data. Inter - system Bias （ ISB ） and Inter - frequency Bias （ IFB ） are estimated and their stabilities are analyzed when combining MGEX and iGMAS data for the ERP determination. One month data of MGEX and iGMAS network from 01/12/2014 to 30/12/2014 is used for computation and comparison of Multi - GNSS ERP solution. The results show that the accuracy improvement of 13% , 7.5% and 9.8% on the x - component of PM, y - component of PM and LOD respectively, can be achieved to determine the ERPs using MGEX data when iGMAS data are included. The accuracy and reliability of ERPs solution are enhanced when VCE involved in the Multi -GNSS processing compared to those using the equal weight scheme. The results also show that the estimated ISB and IFB from Multi - GNSS processing are varied with different stations and frequencies, but they are very stable and wave in dm -level.