Clock synchronization protocol for distributed satellite networks

Several future space missions are being planned with large number of spacecrafts at low Earth orbit (LEO) and beyond where clock synchronization using GPS will partly be impossible or insufficient. Onboard local clock synchronization devices will be required to replace or augment the available GPS measurements to keep the clocks of the spacecrafts synchronized at low cost. Clock synchronization is very important for many applications, e.g. bi/multi-static SAR systems require clock synchronization for the accurate interferometric phase evaluation. This paper presents a method to relatively synchronize the clocks in such distributed satellite networks when GPS is not available.