A distributed time synchronization method for inter-satellite networks based on integrated Kalman-consensus filters

Time synchronization plays a pivotal role in the rapidly expanding applications of distributed satellite systems. To achieve low-cost and high-precision time synchronization, this paper proposes a novel distributed time synchronization method for inter-satellite networks based on integrated Kalman-consensus (IKC) filters. Initially, each satellite is regarded as an intelligent agent, and the distributed time synchronization system framework and satellite time network topology (STNT) model are established. Subsequently, based on a precise clock model and a dynamic measurement model, each satellite agent carries out inter-satellite measurement and time difference estimation. Then, a distributed IKC time synchronization system and algorithm are proposed. It is demonstrated that the distributed consensus control algorithm is an optimal estimation, and the necessary condition for the stability is also identified. When the STNT is a strongly connected digraph or a connected undirected graph, and it is further balanced, the system can achieve global asymptotic average-consensus time synchronization. Experimental findings indicate that the proposed IKC algorithm delivers excellent time synchronization performance in terms of both convergence speed and steady-state precision. Notably, the entire satellite network can achieve sub-nanosecond-level time synchronization precision.