Research On Baseband Processing Of Beidou Receiver

In recent years,Beidou as the representation of satellite navigation system is continuing to expand the application field.Under the background of expanding application in satellite navigation industry,the satellite navigation receiver is also constant development and change,and satellite navigation receiver is the foundation of its wide application,so the study of Beidou satellite navigation receiver technology has very important practical significance.While the base-band processing technology of Beidou signal is the core of Beidou receiver technology,its pros and cons directly affect the performance of the receiver,so in this paper,the base-band processing technology for Beidou receiver has been studied.Based on the B1 signal of Beidou second generation navigation satellite,the research on base-band processing technology of Beidou receiver is carried out.Base-band processing mainly covers two parts,namely acquisition and tracking of B1 signal.First,the acquisition algorithm of B1 signal is analyzed in this paper,through several experimental comparison,several parameters affecting the signal acquisition performance are analyzed.Considering the acquisition time and capture efficiency,the time domain serial search algorithm,Doppler frequency parallel acquisition algorithm,cyclic correlation algorithm based on FFT and matched filter acquisition algorithm are simulated and analyzed by MATLAB.After determining their advantages and disadvantages,we get a fast acquisition algorithm,namely,the algorithm of short-time correlation matched filter combination with FFT.Through making the actual acquisition of the BD-2 satellite B1 signal do simulation by MATLAB,we have captured different satellite numbers,verifying the feasibility of the algorithm.Second,the satellite signal of being captured successfully is tracked and analyzed,the tracking process includes two parts: carrier tracking loop and pseudo code tracking loop,the method of Costas loop and FLL joint tracking is used to track the carrier loop,and the thermal noise of the carrier tracking loop is analyzed,the non-coherent DLL is used to track the PN code loop.In addition,the carrier tracking loop and the pseudo code tracking loop are combined into a complete tracking loop,tracking the actual captured satellite signal by MATLAB simulation,the original navigation message is got.Finally,the design of short time correlation matched filter combine with FFT capture module is realized on FPGA,and some modules in tracking channel are designed and simulated by Modelsim.Then the Beidou receiver hardware verification platform is established,so the BD-2 satellite B1 signal acquisition and tracking are achieved,what's more,the positioning results of Beidou receiver is got and the correctness of positioning results is preliminarily verified.