Page 91 - 卫星导航2021年第1-2合期

Shi et al. Satell Navig (2021) 2:5 Page 7 of 13

Number of visible satellites Number of visible satellites
6 m) 6 m)
Y ECI (×10 Y ECI (×10

X (×10 m) X (×10 m)
6
6
ECI ECI
a b

6 m) 6 m)
Y ECI (×10 Number of visible satellites Y ECI (×10 Number of visible satellites

X (×10 m) X (×10 m)
6
6
ECI ECI
c d
Fig. 5 The number of visible satellites of the spacecraft in GEO (0°) under diferent combinations: a BDS; b GPS + Galileo + GLONASS; c
GPS + Galileo + GLONASS + BDS (only MEO satellites); d GPS + Galileo + GLONASS + BDS

6 m) 6 m)
Y ECI (×10 Number of visible satellites Y ECI (×10 Number of visible satellites

6
X ECI (×10 m) X ECI (×10 m)
6
a b
Fig. 6 The number of visible satellites in scenario 4 for the spacecraft in a GEO at 125°; b GEO at 240°