Research On Acquisition And Tracking Technology Of GNSS Software Receiver

Acquisition and tracking technology, the key technology for implementation of the global satellite navigation system (GNSS) receiver, aims at keeping local carrier frequency and phase of spread spectrum code generated at the receiver identical with satellite signal. Furthermore, navigation data can be demodulated, with which important parameters can be obtained for computing the pseudorange and position of the receiver.Firstly, the background of this dissertation and the development of four typical GNSS systems is introduced. Secondly, with GPS as an example, the characteristics of GNSS signal is analyzed, the structure of software receiver is presented, and the principle of acquisition and tracking technology is also discussed. Thirdly, the front-end design of GNSS receiver, which includes antenna, amplifiers, downconverter, and the characteristics of sampling circuit are discussed. Fourthly, based on the analysis of three general acquisition methods of GNSS software receiver and the spectrum of navigation signal, a improved parallel code phase search method is proposed and simulated with really captured signal of 8 satllites. The results show that the acquisition time is reduced. Fifthly, in the anlysis of the code and carrier tracking method, tracking channel of the GNSS receiver is designed and simulated using Matlab with actual satellite signal, the simulation results show that the designed tracking channel meets with the design requirements. Finally, the full paper is summarized, and the next step work is discussed.