Research And Implementation Of The BD-? Receiver Acquisition And Tracking Algorithm

With the development of information technology,satellite navigation has been widely applied in many fields of social life,and it has got developed growing rapidly especially in the military field.As an important member of the Global Navigation Satellite System,BD navigation satellite system is constructed and operated by our country totally.With the increasing development of the BD,the BD-II receiver system in the application on the condition of high-dynamic has become a research hotspot at home and abroad,getting more and more attention.Under the dynamic environment,BD-II satellite signals will produce large Doppler frequency offset and Doppler rate of change,however,the traditional technology of signal acquisition and tracking is unable to deal with the signal's dynamic problems,and the baseband-processing of dynamic signal has already been one of the key technologies and difficulties when designing the BD-II receiver.Therefore,the research of Beidou satellite signal's fast acquisition and stable tracking technology on high-dynamic condition is a very challenging and prospective research topic.The main contents of this thesis include:1.The thesis studies the BD-II system principle,the signal structure and the influence of the high dynamic on the received signal,then what problem need to deal with is given when signal is acquired and tracked under the dynamic environment.2.As for signal acquisition,the principle of several satellite signal acquisition algorithms are studied,including time-based serial sliding domain,code-phase of parallel,folding matched filter and multi-segment matched filter combined with FFT acquisition algorithms.Then simulation in Matlab is carried out to verify the algorithms' performance.The acquisition time and resource occupancy of different algorithms are compared and analyzed.Finally,a fast acquisition method of multi-segment matched filter combined with FFT is proposed,which is suitable for fast acquisition algorithm in high dynamic environment.3.As for signal tracking,the principle of the carrier tracking loop and the code tracking loop and the design of the loop parameters are discussed and compared.The dynamic adaptability and tracking error of the PLL,the FLL and the code loop are analyzed by Matlab simulation.This thesis puts forward a method of tracking in high dynamic environment.In the method,the four phase discriminator firstly tracts the frequency fast,then three-order PLL assisted by two-order FLL tracking is used for precise carrier tracking,and two-order code loop tracking assisted by carrier is designed.Then simulation in Matlab is carried out to verify the performance of the tracking algorithm.4.This thesis designs an acquisition and tracking algorithm based on FPGA hardware platform,and that means the multi-segment matched filter combined with FFT acquisition algorithm is designed and simulated on FPGA,with the three-order PLL assisted by two-order FLL tracking algorithm and two-order code loop tracking assisted by carrier tracking algorithm.The functions of signal acquisition and tracking are realized with simulation on Modelsim platform.And the results show that the function of signal acquisition and tracking is realized successfully.Generally speaking,by understanding the acquisition and tracking algorithms of BD-II signal,the thesis puts forward the fast acquisition algorithm and stable tracking method,the simulation in Matlab is to realize the prospective result.The whole BD-II baseband signal acquisition and tracking algorithms are implemented on the FPGA,which has significant reference meaning for the study of high dynamic BD-II receiver.