Research On The Acquisition Of The GPS Signals And The Jamming Of The GPS Receivers

In order to explore the anti-jamming performance and the effective jamming strategy that interfere the GPS receiver efficiently, this thesis make researches on the synchronization acquisition, the synchronization tracking loop and their performance under various jamming patterns of C/A code GPS receiver with the study of the structure of the GPS system, the architecture and characteristic of the GPS receiver. The main tasks are as follows:1) The performance characteristics of the two types of GPS signal acquisition method-Cyclic Correlation and Partial Matched Filter-Fast Fourier transform (PMF-FFT) are analyzed in detail. An acquisition algorithm based on cyclic correlation is given. This method can solve transition of navigation data. Through the MATLAB simulation and theoretical analysis, the acquisition sensitivity of both methods is studied under different conditions.2) By using C and MATLAB languages, simulation platform for GPS performance evaluation under jamming is established. It includes the GPS receiver synchronization acquisition module, synchronization tracking loop, and the module that determine the state of GPS receiver. It can be used to test the state of the GPS receivers under the effect of a variety jamming3) According to some the results of the test, the optimal parameters for some jamming signals are found out. Based on the characteristics of the results, an effective strategy is given to improve the efficiency of jamming.4) The nonlinear effects of the low-precision quantify of GPS signal is studied. Simulation results show that4bits quantization makes a little impact on the BER performance about0.1dB, while the quantization accuracy of the current military GPS receivers generally is not lower than4bits. So this nonlinear effect can not be used to improve the efficiency of the jamming pattern.