Evaluating the Performance of Two Inter-Frequency Code Bias (IFCB) Models in Combined Precise Point Positioning (PPP)

The main purpose of this article is to evaluate the comprehensive performance two inter-frequency code bias (IFCB) models using undifferenced and uncombined observations. These IFCB estimate parameters for each GLONASS satellite (EG model) a quadratic function frequency channels K (K = −7…6) (QF model). data sampled in 30 s from 140 stations IGS network on 1–7 September 2021, are used study. We analyze all combinations, including data, perspective positioning accuracy, convergence time, utilization. results show that accuracy these same combination comparable three directions both static kinematic modes under long-term observation; accuracies model combinations almost mode, GPS better than not mode. For some such as GLONSS-only GPS/GLONASS, time EG QF model, but improvement rate does exceed 22%. However, other GLONASS/BDS GLONASS/BDS/GALILEO, more 50%. utilization modes; however, without model. models), can achieve set thresholds directions, has From perspectives solution utilization, number estimated we suggest should be when performing combined PPP different combinations.