Research On Pseudo Code Indoor Positioning Based On FPGA

As the indoor areas of people's activities are increasingly enlarged and complicated,the demand for indoor positioning technology is becoming more and more obvious.The indoor positioning technology based on pseudo random code has the advantages of high positioning accuracy and no fuzzy distance,and it is very promising.Therefore,this paper designs and implements a pseudo-code indoor positioning system based on FPGA.The test result shows that the system can achieve high positioning accuracy and high reliability.Firstly,this paper studies pseudo-code synchronization technology.Pseudo-code synchronization technology is the theoretical basis for the realization of pseudo-code ranging or positioning,including synchronous capture and synchronous tracking,which is designed to measure the phase difference between receiving pseudo code and local pseudo-code.Based on the acquisition method of the matched filter,this paper improves the accuracy and reliability of the pseudo-code acquisition by the improvement of structure and the special consideration of sampling rate.The method of full digital analysis is used to analyze the pseudo-code tracking technology,which mainly includes the carrier loop and the code loop.The carrier loop is realized by digital phase-locked loop,and the realization principle and parameter setting method of each module are analyzed in detail.For the shortcomings of the tracking code phase of the traditional code loop,the method of increasing the relative branch path is proposed,and the coherence integrator and the non-coherent integrator are analyzed and designed in detail,the accuracy and real time of the code loop are improved effectively.On the basis of using pseudo-code synchronization technology,the architecture of the positioning system is proposed and the multi-objective measurement can be realized.The method of using Kalman filter to preprocess the measurement data is proposed to improve the stability of the positioning.Then,the positioning system is simulated and analyzed.This paper uses hardware description language Verilog to achieve the designed algorithm,and the ModelSim simulation tools for improved matched filter,carrier loop and code loop simulation,and the carrier loop and code loop joint simulation.Simulation analysis is the basis of hardware implementation,the performance of each module is evaluated in this process,and the design and related parameters are improved according to the simulation results.Finally,the hardware platform based on FPGA and AD9361 is tested.On the basis of the detailed introduction of hardware platform,the cable synchronization and wireless ranging testing were performed.The process of hardware testing mainly adjusts the loop parameters according to the test results to achieve results.The data processing effect of kalman filter is given,and the performance of the system is analyzed in detail according to the experimental results.The test has achieved the desired effect and proves the feasibility and reliability of the designed system.