Analysis of the Global Multi-GNSS Network Processing Raw Observation Approach using BeiDou

Global Navigation Satellite System (GNSS) products are an integral part of a wide range of scientific and commercial applications such as precise orbit determination for low Earth orbit satellites, earthquake monitoring, GNSS reflectometry, tropospheric and ionospheric research, surveying and many more. These products, consisting of GNSS orbits, clocks, phase biases and more, are generated by the International GNSS Service (IGS) analysis centres by processing observations from a global network of ground stations to one or more GNSS constellations. The processing consists of a combined station position and GNSS satellite orbit determination using a least squares approach donated as global multi-GNSS processing.

Within the IGS 3rd reprocessing (repro3) campaign for the new release of the International Terrestrial Reference Frame (ITRF), Graz University of Technology (TUG), Working Group Satellite Geodesy has contributed as an Analysis Centre (AC) for global multi-GNSS processing. TUG has demonstrated high quality results on par with other ACs using its self-developed geodetic processing software Gravity Recovery Object Oriented Programming System (GROOPS). Within GROOPS the global multi-GNSS processing uses the raw observation approach. The raw observation approach uses all measurements as observed by the receivers without explicitly creating any linear combinations or differences. This allows the information contained in each individual observation to be fully exploited.

GROOPS has been shown to be capable of global multi-GNSS processing using GPS, Galileo and GLONASS. With more publicly available metadata for the BeiDou system, GROOPS has been further developed to use BeiDou within global multi-GNSS processing using the raw observation approach. Therefore, in this contribution we present the improvements in GROOPS global multi-GNSS processing using BeiDou and discuss the quality of the resulting orbit, station position time series, clock and phase bias products.