| With the rapid development of space technologies, there are more and more ontrackspacecrafts; however it would be extremely difficult for the allocation of available frequencyresources which used for the satellite TT&C (Tele-Tracking and Controlling) communicationsystem. It is an effective approach to both increasing utilization of frequency resources andutilizing equipment resources in the ground stations.One of the most important issues in communication system is synchronization. Thewhole system can be paralyzed if the synchronization goes wrong. Due to the worse andworse situation of space channels and the particularity of spaceborne SS synchronization, theTT&C system has higher requirement for spaceborne synchronization technology.This paper makes an in-depth research of synchronization technology in spaceborne SSreceiving process, including the acquisition and tracking of PN (Pseudo-Random) sequence,and the extraction of carriers. In the research of acquisition of PN sequence, the slidingcorrelator acquisition and matching filter acquisition are analyzed by their structure frame andperformance analysis. Additionally, designs an improved matched filter, there is no impact onthe performance of the acquisition, but reduces the complexity of the system, and save theenergy consumption.The research in tracking of PN sequence relates to DLL (Delay-Locked Loop), withperformance analysis and simulation model. In addition, the essay analyzed thesynchronization of carrier, by discussing the commonly used Squaring Loop and Costas Loop.There is a simple theoretical analysis of Squaring Loop and Costas Loop, and the simulationanalysis of Costas Loop.In the end, the whole spread spectrum communication system is simulated. Thesimulation results show that the designed synchronization structure is able to rapidlysynchronize PN sequence and carriers, and demodulates the required signals. The essayprovides a reference for thorough research of satellite spread spectrum TT&C system. |
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