Precise two way time synchronization for distributed satellite system

The satellite to satellite precise ranging and time synchronization are necessary to distributed satellite system (DSS) and autonomous formation flyer (AFF) application. In satellite formation flying, the range between a cluster of co-orbiting or constellation satellites is very close, they collaborate with each other and perform special scientific missions cooperatively, so they can be regarded as a large single conventional satellite or virtual satellite. To accomplish the special scientific missions, a much higher accuracy requirement is put forward for time synchronization and ranging measurement in the DSS and AFF. Firstly, a detailed description of the principle and key techniques of dual one-way ranging and time synchronization are presented. For further study, the simulation and performance evaluation of the equipment are discussed. Secondly, to adapt the condition of high dynamic in two-way observation module, the digital base-band processing algorithms of spread spectrum pseudo-code is investigated. Meanwhile, the signal generation and fast acquisition of spread spectrum signal are implemented. The methods of designing for code tracking loop, cycle slip detection, ambiguity resolution and carrier loop are also investigated. The results of simulation indicate that the accuracy of the terminal device is less than 0.2 m and 0.5 ns (1 sigma) in precise ranging and time synchronization. The time synchronization error is less than plusmn10 ns for a range less than 200 km in formation flying.