Fig. 9From: Feasibility analysis of GNSS-based ionospheric observation on a fast-moving train platform (GIFT)Averaged carrier-to-noise density ratio (C/N0) with the standard deviation at different elevation angles for GPS in (a), GLONASS in (b), Galileo in (c), and BDS in (d) for the stationary receiver (blue line) and the moving receiver (red line). The error bars around the data points represent the ± 1σ standard deviationBack to article page