Atmospheric Doppler Modelling for Open Loop Tracking in GPS-RO Receivers

One of the main challenges of the Open-Loop Signal Tracking method in GPS-RO space receivers, is Doppler prediction. Almost in all satellite communication systems, accurate carrier phase tracking under difficult conditions is depend on Doppler prediction accuracy. Obviously, there are several methods for producing a predicted Doppler model, and one of the earliest is Sokolovskiy. In this paper, we are analyzing the typical and operational atmospheric Doppler prediction models for the Open-Loop Signal Tracking of radio occultation, in satellite communications. A summary and comparison between these methods will be concluded in the end of this paper. finally we propose a prediction method can be used in national GPS-RO payloads for predicting atmospheric doppler based on combination of Sokolovsky and C.O. Ao methods.