Compare of navigation constellations´ GDOP with different construction

Based on the characteristics of the 2^nd BeiDou and GPS, three kinds of constellations constituted by MEO, GEO+IGSO+MEO and GEO+IGSO+LEO+MEO were simulated in this paper. Space geometry intensity of these constellations was compared during autonomous orbit determination and ground positioning. The results show that GDOP of MEO satellite has been improved in autonomous orbit determination after adding GEO, IGSO or LEO satellite where the total number of satellites remains the same. However, the geometry intensity of GEO and IGSO is relatively poor in the mean time. During the ground positioning, because GEO and IGSO are over China and surrounding, the positioning accuracy is improved in these areas and geometry intensity is weakened in other areas.