Study on constellation per-slot availability

Constellation per-slot availability is an important factor that influences availabilities of constellation and even the whole navigation system. In the paper, firstly, the structure and top parameters of satellite navigation system is studied. Secondly, process of constellation per-slot work is analyzed, which brings per-slot operation profile and single-satellite life profile, and based on the analysis results, per-slot service states are defined and classified. Thirdly, Markov model is proposed for calculating per-slot availability considering the influence of standby satellite on slot availability. Finally, with the actual data about GPS constellation, method for calculating per-slot availability is presented and discussed.