Design And Research On Beidou Software Receiver

In recent years,BDS has entered into the global satellite navigation network with the rapid speed of development.The application scope of Beidou is throught in every military and civil aspects.The design of hardware receiver is more fixed,the user can not change parameters of the receiver to suit the needs of different kinds of navigation signal processing.Software receiver can flexibly analyze,simulate and implementate various kinds of algorithms.Therefore,it makes up the disadvantages of hardware receiver better.This article mainly focuses on the part of baseband siganl processing in beidou software receiver,including the research of acquisition,tracking of beidou intermediate frequency signal,demodulation of navigation message,positioning and calculating.This article firstly regards the signal system of beidou satellite navigation system as the research object,studing the signal in all levels.Modeling and simulation on carrier modulation,ranging code correlation as well as the navigation message encoding,analyzing the characteristics of beidou signal system.Comparing the difference in the design of software receiver and hardware receiver.A scheme of beidou B1 software receiver is proposed.In the study on technology of acquisition of beidou signal,the research on algorithm of acquisition of beidou signal is studied firstly.Designing appropriate acquisition algorithm according to the characteristics of the beidou signal.Analyzing the method of data processing,selection of parameter according to the characteristics of the beidou signals.Finally,simulation of acquisition of beidou signal relies on the establishment of actual acquisition algorithm model.In the study on technology of tracking of beidou signal,first of all,comparatively analyzing the characteristics of beidou signal system.Considering the change of the carrier frequency and ranging code phase,the carrier tracking loop of combination of the frequency lock loop and phase lock loop,the ranging code tracking loop of delay lock loop is established.Finally,the tracking loop is simulated.In the study on beidou navigation message demodulation,positioning and calculating,considering the unique encoding of beidou navigation message,demodulation of beidou navigation message by means of NH code demodulation,position synchronization,frame synchronization and BCH demodulation.Finally,calculating the satellite position and pseudorange and simulating the model of the positioning of receiver.