Differential Code Bias Estimation using Multi-GNSS Observations and Global Ionosphere Maps

Abstract

Measurements of Global Navigation Satellite System (GNSS) receivers are affected by systematic offsets re- lated to group and phase delays of the signal generation and processing chain. The resulting code and phase biases depend on the transmission frequency and the employed signal modulation. Within this study differential code biases (DCBs) of legacy an d modernized GNSS signals are derived from pseudodrange observations of a global multi-GNSS receiver network. Global ionosphere maps (GIMs) are employed for th e correction of ionospheric path delays. Satellite and receiver-specific contributions are separated based on the a ssumption of additive biases and a zero-mean condition for the satellite biases within a constellation. Based on 6 months of data collected within the Multi-GNSS Experiment (M GEX) of the International GNSS Service (IGS), DCBs for the publicly available signals of GPS, Galileo and BeiDou have been deter- mined. The quality of the resulting DCB estimates is as- sessed and compared against group delay parameters transmitted by the GNSS providers as part of the broad- cast ephemeris data.