Research And Implementation On Tracking Loop Technologies Of Hop-spread Spectrum Communication System

Hop-spread spectrum communication system is a kind of modern communication system which uses hop-spread spectrum communication technology such as direct sequence spread spectrum DS and frequency hopping FH. The main research communication system in this thesis is a global navigation satellite system(GNSS) that use hop-spread spectrum communication technology. The implementing foundation of hop-spread spectrum technology is autocorrelation and mutually of pseudo-random code. In hop-spread spectrum communication system, the original narrow bandwidth of useful signal is expend to a wider bandwidth. This process is called spectrum spread. Hop-spread spectrum can make a big improvement on resisting disturbance of communication system, and it can strengthen data concealing.GNSS consists of three parts including space segment, ground segment and user facility, can provide users global, entire day, continuous, real-time and exact three-dimensional positioning service and testing service. At present, there are many GNSSs are being used, for example the GLONASS from Russia, GALILEO from Europe, and BEIDOU from China. Compared with signal GNSS, the combination of several GNSSs can achieve more accurate and better positioning and speed testing service. But that requires user facility receivers supporting different GNSSs. The signal of GNSS is high frequency signal transferring in high dynamic environment. The signal received by user receiver commonly has Doppler frequency shift and Doppler frequency shift change rate. And this requires designer carefully design the capturing and tracking part to make sure proper functioning of receiver.Besides researching principles of hop-spread spectrum communication system and GNSS, this paper mainly focuses on the tracking loop algorithm and implementation in navigation satellite system which uses the hop-spread spectrum communication technology. The main tasks of thesis are as follows:Firstly, I study the theory of hop-spread spectrum communication technology, especially the implementing foundation of hop-spread spectrum communication technology:the autocorrelation and mutually of pseudo-random code, and concrete implementation methods of direct sequence spread spectrum DS and frequency hopping FH.Secondly, I research the global navigation satellite system’s composition and related knowledge, focus on various algorithms of receiver tracking loop, and then compare and analyze their characteristics.Finally, according to previous researching results and combining the concrete parameter performance requirements of hop-spread spectrum global navigation satellite system in this project, I design tracking loop and do simulation. Ultimately it is implemented in QuartusⅡ integrated development environment of Altera Corporation.