Prediction algorithm of GLONASS almanac based on a model conversion

The prediction of GLONASS almanac is one of the key techniques of the production of the navigation message. By research the prediction algorithm of GLONASS almanac, a new prediction algorithm of GLONASS almanac based on a model conversion was presented. This algorithm uses the GLONASS precise orbit data of one day to fit a group of orbital elements with the least square estimation method. And then this group of orbital elements was converted to the GLONASS almanac parameters using an established almanac model conversion. Finally this algorithm has been validated through the precise orbit data generated by STK (satellite tool kit). Meanwhile, this algorithm was applied to the GLONASS navigation signal simulator, and the navigation signal was measured practically for long time using the 112T commercial receiver. The results show that the algorithm is simple and highly accurate, which can fully meet the almanac prediction accuracy requirement of navigation user.