SATELLITE CLOCK PARAMETER TWO-STEP FIT ALGORITHM FOR
PERIOD OF OUT-OF-VIEW
1) College of Navigation & Aerospace Engineering, Information Engineering University, Zhengzhou 450052
2) The Equipment Research Institute of the Second Missile Army, Beijing 100085
3) Beijing Global Information Application and Development Center, Beijing 100094
Abstract：Quadratic model is fitted with the nearest history data of 24 hours when the satellite is outofview, and is used to predict clock offset as soon as the satellite is in view. Based on the conventional fit algorithm, the best fit arcs are selected independently for the two fitting parameters of frequency bias and frequency drift according to their respective characteristics at different length of fitting arcs. A twostep fit is proposed using both longand shortterm data sets. The fit and prediction comparisons using the real clock offset data show that the prediction performance of twostep fit is better overall than the conventional method.
