Assessment of BeiDou differential code bias variations from multi-GNSS network observations

S G Jin,D Li,R Jin

doi:10.5194/angeo-34-259-2016

Abstract

Abstract. The differential code bias (DCB) of global navigation satellite systems (GNSSs) affects precise ionospheric modeling and applications. In this paper, daily DCBs of the BeiDou Navigation Satellite System (BDS) are estimated and investigated from 2-year multi-GNSS network observations (2013–2014) based on global ionospheric maps (GIMs) from the Center for Orbit Determination in Europe (CODE), which are compared with Global Positioning System (GPS) results. The DCB of BDS satellites is a little less stable than GPS solutions, especially for geostationary Earth orbit (GEO) satellites. The BDS GEO observations decrease the precision of inclined geosynchronous satellite orbit (IGSO) and medium Earth orbit (MEO) DCB estimations. The RMS of BDS satellites DCB decreases to about 0.2 ns when we remove BDS GEO observations. Zero-mean condition effects are not the dominant factor for the higher RMS of BDS satellites DCB. Although there are no obvious secular variations in the DCB time series, sub-nanosecond variations are visible for both BDS and GPS satellites DCBs during 2013–2014. For satellites in the same orbital plane, their DCB variations have similar characteristics. In addition, variations in receivers DCB in the same region are found with a similar pattern between BDS and GPS. These variations in both GPS and BDS DCBs are mainly related to the estimated error from ionospheric variability, while the BDS DCB intrinsic variation is in sub-nanoseconds.

Highlights

With the rapid development and wide applications of global navigation satellite systems (GNSSs), more and more constellations and stations have been constructed, including the USA’s Global Positioning System (GPS), China’s BeiDou Navigation Satellite System (BDS), Russia’s GLObal NAvigation Satellite System (GLONASS), and the EU’s Galileo, as well as other regional systems (Jin et al, 2011, 2016; Montenbruck et al, 2014)
The high-precision ionospheric total electron content (TEC) can be estimated from dualfrequency GNSS carrier phase measurement, where differential code bias (DCB) is one of the main errors, which cannot be ignored for high-precision TEC estimation and positioning applications
For the ionospheric pierce point (IPP) location of the BDS line of sight (LOS), the approximate station coordinates are used from observation files and the precise orbit products are provided by the Wuhan University GNSS Research Center and the GeoForschungsZentrum (GFZ)

Summary

Introduction

With the rapid development and wide applications of global navigation satellite systems (GNSSs), more and more constellations and stations have been constructed, including the USA’s Global Positioning System (GPS), China’s BeiDou Navigation Satellite System (BDS), Russia’s GLObal NAvigation Satellite System (GLONASS), and the EU’s Galileo, as well as other regional systems (Jin et al, 2011, 2016; Montenbruck et al, 2014). One is that the total electron contents in the ionosphere are concentrated in a single thin layer at 300–500 km altitude corresponding to maximum electron density height, i.e., the single-layer model It is reasonable and convenient under most situations for TEC modeling and DCB estimation, except for anomalous ionospheric activities when the ionospheric variations are not homogeneous regionally. The long-term trend of GPS satellite DCB has proved to be related to the zero-mean condition (Zhong et al, 2016); it is still a debate, and may be related to ionospheric daily and annual variations. The BDS DCB variation characteristics are investigated and assessed from multi-GNSS network measurements obtained by the BETS and MGEX tracking stations

BETS and MGEX observations

DCB estimation based on GIMs

Results and discussion

Summary