Global navigation satellite system occultation sounder (GNOS) Fengyun-3C was launched successfully on September 23, 2013, which carried GPS/BDS receiver for the first time.This provides the convenience to study the enhancement results of low earth orbiter satellite (LEO) to BDS precise orbit determination (POD).First the data characteristics and code observation noise of GNOS are analyzed.Then the enhancement experiments in the case of global and regional ground observation stations layout are processed with four POD schemes: BDS single system, GPS/BDS double system, BDS single system with GNOS observations, GPS/BDS double system with GNOS observations.The precision of BDS orbits and clock are compared via overlapping arcs.Results show that in the case of global station layout the along directional precision of GEO satellite has the biggest improvement, with the improvement percentage 60%.Then the precision of cross direction and the along direction of remaining satellites shows the second biggest improvement.The orbit precision of only BDS POD in part of arcs some satellite even suffers a slight decline.The root mean square (RMS) of overlapping clock difference of visible arcs in GPS/BDS POD experiments is improved 0.1ns level.As to the experiments of regional station layout with 7 ground observation stations, the orbit and clock overlapping precision and orbit predicting precision are analyzed.Results show that the predicting precision of BDS GEO satellites in the along direction is improved 85%.The remaining also has a substantial improvement, with the average percentage 21.7%.RMS of overlapping clock difference of visible arcs is improved 0.5ns level.%首次搭载GPS/BDS双模接收机全球导航卫星掩星探测仪(GNOS)的风云三号C星于2013年9月23日的成功发射,为研究低轨卫星对BDS定轨增强提供了便利.本文首先对低轨卫星GNOS搭载的GPS/BDS双模接收机的观测数据进行统计,并分析了伪距测量精度.然后在全球测站、区域测站两种布局情况下,对无GNOS的BDS单系统定轨、无GNOS的GPS/BDS双系统定轨、有GNOS的BDS单系统定轨增强、有GNOS的GPS/BDS双系统定轨增强4种方案进行北斗轨道及钟差比较分析.结果表明,GNOS对北斗卫星轨道增强在全球测站下,GEO卫星切向精度提升最为显著,提升程度达60%,其次是法向和其他类型卫星切向,部分弧段个别GEO卫星径向精度稍有下降.双系统定轨增强中可视弧段钟差重叠精度RMS值有0.1ns量级改善.7个国内测站区域监测网的定轨试验中对轨道进行了预报,结果表明GNOS对北斗GEO卫星轨道预报精度切向提升达85%,其余方向及卫星有较大改善,平均21.7%.可视弧段钟差重叠精度RMS值有0.5ns量级改善.
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