In synchronized-pseudolite navigation system (SPNS), precise time synchronization can be achieved by real-time synchronizing process that reduces clock drift error. It means that the system clock of slave pseudolites should track the master system clock continuously. The Proportional integral derivative (PID) control is a simple and powerful design strategy for a feedback system that tracks continuously phase offset between the system clocks of slave pseudolite and master pseudolite to time synchronization. In this paper the design approach of feedback system which controls the system clock frequency of the slave pseudolites for time synchronization of SPNS is proposed. In particular to optimize the gain of the PID controller, time and frequency response characteristics were analyzed based on the discrete plant model. In addition the limitation of the real-time synchronization system with feedback mechanism of the SPNS is also considered.

Keywords: pseudoilite navigation system, time sychronization, PID control