The Research On The Method Of Catching GPS Direct P(Y) Code

This paper describes the fundament of GPS, analyzes and compares all kinds of GPS P code acquisition method. Advantages that FFT realizes direct acquisition are presented and extending replicate overlap method (generalization of FFT method) that acquires the GPS P code directly is emphasized, the theory is verified by simulation. This paper also puts forward the project that acquire the GPS P code on the platform composed by FPGA and DSP with extend replicate overlap method, and estimate the wasted time.According to the characteristic that extend replicate overlap method can acquire the GPS P code directly, the restrain of narrow band interfering signal using this method is introduced, simulation and verification is accomplished. But the theoretic analysis of anti-jamming performance is not accomplished and still need further study.Acquiring GPS P code directly is very important in some special circumstance. Because it has high allowance of jamming and deceiving compare with C/A code, C/A code may be jammed completely, deceived or out of order in war, acquiring P code directly is the only one feasible method. So studying the method that acquire GPS P code directly is very important, and can supply technical fundament for our country's military satellite navigation receiver.