Estimation of BDS DCB Based on Closure Constraint

  Objectives  BeiDou navigation satellite system (BDS) is the only satellite navigation system that provides triple-frequency signals as a whole constellation of global navigation satellite system (GNSS). There are three kinds of differential code biases (DCBs): DCB_C2I-C7I, DCB_C2I-C6I and DCB_C7I-C6I. Theoretically, there are zero algebraic relationship among the three DCBs.

  Methods  Based on the zero algebraic relationship, BDS triple-frequency data of 2018 DOY 001-030 from multi-GNSS experiment (MGEX) stations are selected, and medium earth orbit (MEO) and inclined geosynchronous satellite orbit (IGSO) satellites are used as reference satellites to estimate three DCBs.

  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 the estimated DCB and the DCB time series of some typical satellites. It suggests that results derived from the proposed method are in good agreement with the reference values. And the experiment of standard point positioning (SPP) in BDS single frequency verifies the effect of DCB on accuracy of SPP.

  Conclusions  All the results demonstrate that the proposed method is applicable and scientific to the estimation of BDS DCBs.