Design Of GPS Receiver Rf Front-end And Research On High Sensitive Acquisition Algorithm

GPS can be applied to positioning in most parts of the world,but it cannot achieve effective positioning without certain algorithm processing under some special conditions,such as indoors or high orbits in space.According to this,this paper will study the hardware design of the GPS receiver RF front-end and the acquisition algorithm under weak signal conditions,that is,the research on the high-sensitivity acquisition algorithm.The algorithm processing of the high-sensitivity receiver include three main modules: acquisition,tracking,and positioning solution.Acquisition is the first step of IF algorithm processing,and whether the signal can be captured is crucial.This paper mainly does two aspects of work: the hardware design of the GPS receiver RF front-end and the C/A code acquisition technology of the software receiver.Hardware design,Research on the gain magnification of RF design,the selection of digitization method and the design principle of RF structure,and with the support of this theory,a RF front-end solution with a down-conversion digital structure is designed.Through the guidance of the hardware solution,low noise is achieved.The device selection and circuit principle design work of amplifiers and mixer integrators,through the analysis of signal and power integrity in high-speed signal design,completed the engineering design of the RF front-end,and finally improved the layout design and analysis of the physical RF front-end hardware.The test results of the simulated intermediate frequency signal are presented.Software algorithms,The signal characteristics in the intermediate frequency phase of GPS signal processing are briefly described,and the basic principles of the receiver and the structure of the C/A code signal are introduced.On this basis,the causes of signal Doppler and carrier offset theory are analyzed.Various methods of signal acquisition on ordinary GPS receivers are studied,and the advantages and disadvantages of various time-domain and frequency-domain acquisition algorithms are analyzed to lay a theoretical foundation for the study of weak signal acquisition algorithms on high-sensitivity receivers.According to the RF front end designed before,the intermediate frequency data is collected as the data source for the research of the acquisition algorithm.Finally,this paper study the existing weak signal acquisition algorithms and their advantages and disadvantages,determine the advantages of the frequency domain differential coherent algorithm,and propose an optimization scheme for Doppler search,In order to meet the needs of high-sensitivity software receivers,giving a simulation comparison analysis before and after optimization of the frequency domain differential coherent algorithm.The improvement plan is planned to include carrier Doppler frequency shift compensation technology,which will reduce the sampling error caused by Doppler,improve the fault tolerance,accurately locate the Doppler frequency shift value in the case of weak sensitivity,improve the traditional differential coherence algorithm,and reduce the complexity of the phase-locked loop operation in the follow-up tracking phase.At the end of this article,the advantages and disadvantages of RF front-end design are analyzed,and the application scenarios and performance improvement ideas for improving the high-sensitivity capture algorithm are discussed.