Research And Implementation Of Key Technology For Baseband Signal Receiving And Processing Of Satellite-based Difference System

With the rapid development of information science and technology,satellite navigation plays an increasingly important role in the socio-economic development,meanwhile the demands for high-precision navigation information are also increasing from all works of life.In order to impro ve the accuracy of PVT(Positioning,Velocity,and Timing)service,the development of difference system and augmentation system for GPS(Global Positioning System)has been relatively mature.The BDS(Beidou Satellite Navigation System)designed and operated by China independently is also developing at a high speed to meet user's requirements of positioning accuracy.Augmentation service to BDS becomes an important way to meet the needs of high-precision PVT.Especially in the area without network signal coverage of China,to provide satellite-based differential broadcast is an indispensable method.NTSC(National Time Service Center,Chinese Academy of Sciences)carried out the C-band satellite broadcasting experiment of BDS GBAS(Ground Based Augmentation System)based on the transfer satellite navigation system.Based on the background of the C-band satellite broadcasting system,this thesis studies the technology for baseband signal receiving and processing of satellite-based difference system and analyzes and implements the technology with the practical engineering experiment.The main content is as follows,(1)This thesis studies on acquisition algorithm of satellite navigation signal and implements the fast acquisition of satellite-based differential signal based on the matched filter of Numen chip.(2)The tracking algorithm and synchronization algorithm of satellite-based differential signal are studied based on N umen chip.The core functions of differential signal receiver module is realized based ZSP compiler by Clanguage: receiving and decoding satel ite-based differential signal and transmitting the differential message.(3)In order to verify the implementation of receiving and processing functions of satellite-based differential baseband signal,two stages of experiment are designed: RF self-closed-loop differential signal broadcast test based on analog transponders;Differential signal broadcast experiment based on GEO satellite of transfer satellite navigation system.The results of experiment show that there is no error frame within 3 hour.(4)In order to improve the robustness of the tracking loop,the tracking algorithm implemented above is improved.The tracking algorithm based on Kalman filter is studied and simulated based on Matlab.The simulation results show that the tracking stability of the tracking loop is better than that of the traditional second order phase-locked loop under the condition of high dynamic and low carrier-to-noise density power ratio(C/N0).This thesis studies the related technology for baseband signal receiving and processing of satellite-based difference system,and the technology implemented in this thesis obtains the C-band satellite broadcasting experiment verification of BDS GBAS built by the NTSC.Therefore,the research results of this thesis can be used for receiver module for differential signal and provide some theoretical and practical engineering references.