Swarm低轨卫星星座的GPS接收机差分码偏差估计

GPS Differential Code Bias Estimation Using Swarm LEO Constellation Onboard Observations

    摘要
  • 摘要: 差分码偏差(differential code bias，DCB)是指由全球导航卫星系统(global navigation satellite system, GNSS)信号接收和发射硬件导致的频率相关的偏差项，对电离层估计有显著的影响，在利用GNSS观测数据提取电离层总电子含量时需要被精确修正，研究利用低轨卫星的星载GNSS观测数据估计DCB尤为重要。使用Swarm星座3颗卫星GPS接收机2016年1月的双频观测值，设计了独立估计和联合估计两种估计方案，采用附加限制条件的间接平差方法对GPS卫星以及星载接收机的DCB进行估计。以中国科学院和德国宇航中心的DCB产品作为参考，分析了两种估计方案的精度和稳定性，相较于独立估计方案，联合估计方案得到的GPS卫星DCB的稳定性较独立估计方案提高了16.6%，且与参考DCB具有更好的一致性。

     

    Abstract:
      Objectives  The differential code biases(DCBs) have a great influence on the estimation of ionosphere with GPS observations, which should be precisely calibrated when obtaining ionospheric slant total electron content (STEC). With the increasing number of low-orbit satellites, DCB estimation of low earth orbit (LEO) receivers becomes particularly important for the topside ionosphere research.
      Methods  Based on the onboard observations of GPS satellites by the Swarm constellation, two different estimation schemes for three satellites in constellation are designed, including individually estimation and combined estimation.
      Results  Taking the DCB products provided by Chinese Academy of Sciences (CAS) and Deutsches Zentrum für Luft - und Raumfahrt (DLR) as reference values , we analyze the accuracy and stability of these two strategies . Compared with the individual estimation strategy, the combined estimation strategy achieves more stable satellite DCB with a stability improvement of 16.6% for GPS satellites, and the satellite DCB presents better consistency with the reference DCB provided by the two analysis centers.
      Conclusions  Both strategies can be used to estimate DCB and the combined estimation strategy results in better performance.

     

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