Analysis of the cross-talk systematic error in GPS observation of GRACE satellite and its impact on POD results

The systematic errors of GPS data from GRACE satellite are analyzed, and the nu merical results indicate that the multipath error is not significant while the occultation antenna is turned off. But when the occultation antenna is turned on, in the aft-looking hemi-sphere, there are clearly multipath-like systematic error in the code observations which is caused by the cross-talk between the prime POD and occultation antenna string, but the analysis indicate that the cross-talk systematic error in the carrier phase observations can be ignored. So in the orbit determination processing, the weight of the code observations are adjusting to reduce its impact on the POD results. The numerical results show that when the STD of the P(3) observation is greater than 4.0 m, the POD results can achieve the best preci-sion- which is 3.9 cm, 4.0 cm, and 3.4 cm in X, Y, Z respectively.