Application of Robust Estimation in Zero-difference Kinematical Orbit Determination of GPS-equipped Satellites

According to the special characteristics of zero-difference kinematical orbit determination of GPS-equipped satellites, it is proposed that the robust estimation should be applied in the orbit determination of these satellites. On the one hand, the observed values of every GPS satellite are preserved as far as possible and the stronger geometrical intensity of the satellite is kept so as to avoid the occurrence of singular solutions in the orbit determination; and on the other hand, the idea of equivalent weight can be used to decrease the effect of the poor-quality observed values on the accuracy of the orbit determination. A set of actually observed data of GPS of the CHAMP satellite are used to test and verify the feasibility and validity of the new scheme.