Combined Orbit Determination of Navigation Satellites with Cross-link Ranging Observations and Ground Tracking Observations

This paper discusses the mathematical models,simulation methods of observations,and methods of COD(combined orbit determination) of navigation satellites,which is based on cross-link ranging observations and ground tracking observations.A variety of simulations were processed with the software developed by ourselves in this paper,and the results indicate that the effect of adding ground stations and improving their geographical distribution on improving the accuracy of combined orbit determination is very limited.