Research on Distributed Autonomous Time Reference Maintain Method of Navigation Constellation

Abstract

Satellite navigation system to provide users with high-precision positioning, navigation, and timing services, requires a uniform high-precision time reference. When the navigation system is operating in the normal mode, this reference is maintained by the ground and measured through the satellite–ground link and modifies the onboard clock parameters to ensure the uniformity of the entire system time reference. In the autonomous navigation mode, the navigation constellation to leave the ground support, need to maintain the time reference autonomously. This paper analyzes the maintenance method of autonomous time reference based on inter-satellite observation and designs a distributed autonomous time reference maintenance algorithm. The satellite clock error is used as the basic observation to compose the system measurement equation. According to the system state equation, each satellite uses Kalman filter to estimate and update its own clock parameters to maintain the constellation time reference. Simulation results show that the proposed algorithm can maintain the uniform time reference of navigation constellations.