Study GPS Signal Simulation Based On MATLAB

This subject is in progressed to the study of the GPS system whole software simulation based on MATLAB, and puts forward GPS software simulator concept and design proposal based on MATLAB, and designed a completely GPS software simulation system successfully. The system use MATLAB/Simulink as the development platform, and the system consists of signal transmission modules, transmission channel module, receiver module, second processing module. The simulation module built achieved modularization, standardization, universalization, and easy to change the simulation steps, parameter settings, error checking and revision, the main researches are as following:1. Analysis the spreading codes:C/A-code/P-code's principles of the constitute and characteristics, and use MATLAB to simulation analysis its time/frequency domain and correlation. Proposed "hybridalgorithm" model.2. Propose GPS system simulation model based on MATLAB, and carried out the simulation research of GPS signal generation part. Primary study the simulation realization problem in the MATLAB of DSSS and BPSK modulation.3. Carried out the space transmitted simulation study by the GPS signals generated by the transmitter, focusing on simulate the signal's time domain and frequency domain waveform changes when received the Gaussian thermal noise.4. Complete the reception/sampling of signals, extracting the local frequency signal (IF). Given the characteristics of software simulation, presented and introducted "parallel despreading synchronization algorithm" and "parallel synchronous demodulation algorithm", achieved the GPS signal acquisition and tracking successfully.5. Due to the transmission channel subject to Gaussian noise, the receivied GPS signal which after despreading, demodulation, filtering still has distortion. Introduct the "Logical filtering algorithm to determine" new method to reprocessing the signal.6. Based on previous simulation, with MATLAB/M programming language as the development tool, and with the almanac-data which provided by the GPS receiver as the variable used to achieve the "reference point simulation" simulation of orientation, moved from "the signal waveform simulation"→"coordinate positioning simulation".