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

TLDR

GNSS measurements are affected by systematic offsets from group and phase delays, and code and phase biases vary with transmission frequency and signal modulation. The study aims to derive differential code biases for legacy and modernized GNSS signals from pseudorange observations of a global multi‑GNSS receiver network. Using pseudorange data from a global multi‑GNSS receiver network, the authors correct ionospheric path delays with global ionosphere maps, separate satellite and receiver contributions by assuming additive biases and a zero‑mean satellite bias condition, and estimate DCBs for GPS, Galileo, and BeiDou over six months of MGEX data. The resulting DCB estimates are evaluated and found to be comparable to the group delay parameters provided by GNSS manufacturers in broadcast ephemeris data.

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.