A new differential code bias (C1–P1) estimation method and its performance evaluation

Abstract

The current satellite clock products are computed using the ionosphere-free phase (L1/L2) and code (P1/P2) observations. Thus, if users conduct undifferenced positioning using these clock products together with C1 and P2 observations, the differential code bias (DCB) (C1---P1) should be properly compensated. The influence of DCB (C1---P1) on the undifferenced ambiguity solutions is investigated. Based on the investigation, we propose a new DCB (C1---P1) estimation method. Using it, the satellite DCB (C1---P1) can be computed. A 30-day (DOY 205---234, 2012) dual-frequency GPS data set is processed to estimate the DCB (C1---P1). Comparing the estimated results with that of IGS DCB products, the accuracy is better than 0.13 m. The performances of DCB (C1---P1) in the code-based single-point positioning, precise point positioning (PPP) convergence and wide-lane uncalibrated phase delay (UPD) estimation are investigated using the estimated DCB (C1---P1). The results of the code-based single-point positioning show that the influence of DCB (C1---P1) on the up direction is more evident than on the horizontal directions. The accuracy is improved by 50 % and reaches to decimeter level with DCB (C1---P1) application. The performance of DCB (C1---P1) in PPP shows that it can accelerate PPP convergence through improving the accuracy of the code observation. The computed UPD values show that influence of DCB (C1---P1) on UPD of each satellite is different, and some values are larger than 0.3 cycles.