Handling and Estimation of GNSS Code Biases - Latest Developments at CODE

The Center for Orbit Determination in Europe (CODE) has been providing GPS P1-C1 differential code bias (DCB) values for the IGS community since 2001. With the consideration of GLONASS observations at CODE in 2003 GLONASS and GPS-GLONASS-intersystem biases were introduced (first for the ionosphere analysis and later also for the clock analysis). Another essential step was the consideration of GLONASS differential code-phase biases (DCPB) needed for successful GLONASS ambiguity resolution. Nowadays, with receivers capable to track more than four GNSS constellations, new frequencies and signals, the handling and adequate consideration of all relevant GNSS biases becomes more and more demanding. The change from a differential to an observable-specific, or pseudo-absolute bias parameterization is one of the important steps towards a flexible, expandable GNSS bias handling. This new approach allows us to deal with more complex GNSS analysis scenarios. In this contribution we will present the latest developments made at CODE regarding GNSS bias estimation.