Researches On BD2/GPS Dual-mode Software Receivers

With the rapid development of global satellite navigation system,the navigation systemwhich compatibles with the American GPS,the Russian GLONASS,the Galileo and theChinese Compass is bound to become an important trend in the future.Comparing withsingle-system navigation receiver,multi-system satellite navigation receiver has morecoverage, such as high positioning accuracy,good reliability,a series of advantages,and so on.This paper mainly studies a kind of high dynamic two dual-mode navigation system receiverwhose performance can be compatible with GPS-L1and COMPASS-B1.Firstly,the paper analyzed carefully the basic structure of signal of the GPS-L1andBD2-B1,three capture methods which are common used in current are focused on.By theirgood or bad are compared,code phase in parallel capture is drawn to be the most fast amongthree capture methods,in order to improve the speed of capture further,this text makes animprovement basing on code phase in parallel capture.In the case of without affectingaccuracy,code phase in parallel capture algorithm using code phase in parallel and carrierfrequency in serial search is improved for code phase in parallel and carrier frequency infour road parallel search,the more,Matlab is used to simulate and verify the improvedcapture algorithm. By simulation result of improved capture is compared with simulationresult of code phase in parallel capture, it can be seen that improved capture can improve thespeed of signal capture effectively.Secondly,the paper designed the overall structure of the dual-mode receiver, anddual-mode generator,dual-mode selection algorithm of satellites,time and coordinatetransformation and the dual system solution conducted extensive research base model,sothat the receiver can meet the requirements of precise positioning under differentenvironmental conditions.Thirdly, basing on the need to meet the24-channel receiver,positioning requirements10Hz frequency,I designed a fast catching multiplexing module and a frame synchronizationmultiplexing module,thereby reducing FPGA resource utilization and by reducing DSPinterrupt service routine to improve DSP arithmetic operation efficiency and reduceoverhead.Finalily,the paper designed receiver RF front-end processing module and a basebandsignal processing unit and a PC software. PC software achieves mainly sending commands, constellation distribution,satellite signal-receiver trajectory,statistics,protocol analysis,real-time display,and can analysis received specific data.