GPS Signal Acquisition Algorithm Simulation And Implementation

Global Position System is more and more close with people's life from start run till now. It has already been applied to various fields. Along with the launch of China's BeiDou second generation satellite, the Global Positioning System research has a new opportunity in our country. As the user interface of global positioning system, GPS receiver has the most closely related to the people, and is the focus of research in the meantime.The typical work order of GPS receiver is signal search and acquisition, signal tracking and then navigation solution. GPS signal search and acquisition is the foundation for signal processing of GPS receiver. The actual received GPS signal is not ideal for the GPS algorithm, and GPS signal simulator is expensive and inflexible. This thesis mainly study and analyses the search and acquisition of GPS signals, designs a GPS intermediate frequency signal source, simulates the search algorithm, and carried on a hardware realization of the search algorithm's main module.This thesis briefly describes constitute of the GPS system, analysis the GPS signal structure, introduces the hardware receiver and the software receiver, analysis the work principle of receiver. On this basis, the principle of GPS signals acquisition and search strategy to carry on the GPS signal are detailed analysis. Explain the parameters of GPS signal capture options, and then analyze the FFT-based time-domain parallel acquisition algorithm and the second fine frequency acquisition.A GPS intermediate frequency signal source is designed in this thesis. The signal source using Simulink module, can generates any satellite signals on L1 carrier frequency with strong flexibility and reusability by simple parameter settings. Designs GPS signal acquisition algorithm and programs it with Matlab. IF signal is generated using designed IF signal source. The acquisition simulation is carried out using the programmed algorithm. During simulation , the coarse frequency acquisition and fine frequency acquisition are analysis respectively. Different signal to noise ratios of gauss white noise GPS signal are acquiesced using different interval. The deviation trend of acquiesced frequency with the setting frequency is draw along the signal to noise ratio. Analyzing the effect of data jump to acquising.Based on the completion of the software simulation algorithm, using FPGA (Field Programmable Gate Array) technology implements the acquisition hardware. The main modules, C / A code generator, carrier NCO (Numeric Control Oscillator), butterfly processor address, a complex multiplier, peak detection module simulation, are programmed using Verilog HDL and simulated.