Research And Simulation Realization Of High Dynamic GPS Signal Capture Algorithm

GPS is a satellite navigation and positioning system which currently has themost clients and occupies an important position in the field of satellite navigation andpositioning. In the highly dynamic situations, signal carrier frequency will cause thelarger Doppler frequency shift and the rate of change due to the rapid relative motionbetween the GPS receiver and a satellite, affecting the accuracy of the GPS signalcapture. The capture of the signal is a problem in the study of GPS receiveralgorithms. In this paper, GPS navigation and positioning systems for highlydynamic environments as the research object, research suitable for GPS signalcapture algorithm, in order to further expand the GPS navigation application in highdynamic environment to provide theoretical support.In this paper, the characteristics of the signal under high dynamic environment,discusses the sliding correlation algorithms in time domain and FFT algorithm forfast capture, From the capture time and computation on the comparative analysis oftwo kinds of algorithm, fast capture proved FFT algorithm is more suitable forapplication in highly dynamic environments. Based on FFT fast capture algorithmtheory, the algorithm has been improved, Through the C/A code performancesimulation results verify the accuracy of the improved algorithm. For FPGA circuitdesign, this paper studies the capture circuit logic design related issues, thecompletion of the relevant module in FPGA implementations, these modules include:clock module carrier module, C/A code generator module, with an average samplingmodule, plural multiplier module, FFT/IFFT module and peak detection module. Inorder to save FPGA resources to reduce cost, we use IP core simplifies FFT/IFFTmodule and by using the adder reduce the number of real multiplier improve pluralmultiplier. The design using ISE development software simulation modules tocomplete development tasks, capture algorithm by using VHDL hardwaredescription language, the function of the related modules. This design applied under high dynamic situation, has a certain practicality,solving the interference caused by the Doppler effect on GPS signals, simplifying theGPS signal capture process, and reducing the computational complexity of signalcapture. High dynamic GPS signal acquisition algorithm research can provide areference for the relevant areas of the navigation system and has a certain practicalsignificance and application prospects.