Design And Implementation Of GPS/BDS Dual Mode Software Receiver

With the continuous development of navigation technology,Global Navigation Satellite System(GNSS)has become a hot spot on competing countries.The U.S.Global Position System(GPS)has now been in operation for more than four decades and has wide coverage and high positioning accuracy.China's self-developed BeiDou Navigation Satellite System(BDS)has now implemented the stable positioning service function of the Asia Pacific region.With the rapid development of the navigation system navigation system,the navigation receiver technology also changes.The multi-mode and multi-frequency software receiver has become one of the hot spots in its development.In this paper,the baseband signal processing,navigation data analysis and positioning algorithm of GPS/BDS receiver are deeply researched.The design of GPS/BDS dual-mode software receiver is put forward under the development of navigation receiver.The GPS/BDS dual mode software receiver based on C++ is realized,and the satellite data is used to verify the positioning functions in various modes of GPS,BDS and GPS/BDS.Based on the research of GPS and BDS positioning principle,signal format and coordinate system,this paper presents the overall design of GPS/BDS dual-mode software receiver.Bit-operation algorithm and multi-threading technology are used in program design to improve data processing speed.In the process of baseband signal processing,Numerically Controlled Oscillator(NCO)is used to generate local carrier wave and pseudocodes.Intermediate frequency signal is captured using a linear serial algorithm.Carrier tracking is performed in the way of Frequency Locked Loop(FLL)assisted Phase Locked Loop(PLL).The Delay Locked Loop(DLL)is used for code tracking,and the carrier-assisted is used to increase the code tracking speed.Based on the calculation of GPS/BDS pseudorange and satellite position,the pseudo-range fusion algorithm is used to construct the pseudorange equation.The weighted least square method is used to solve the equation and finally the receiver position is obtained.In order to observe the data processing process of each channel,the positioning results and constellation information are displayed,and the human-machine interface based on the Allegro library is designed and implemented.In order to verify the positioning function of GPS/BDS dual mode software receiver,the GNSS signal gathered by intermediate frequency data acquisition unit is processed in GPS,BDS and GPS/BDS modes,which verifies the correctness of positioning results.