Direct Acquisition Technique for GPS P(Y)-Code

Direct and fast acquisition of the GPS P(Y)-code is desirable to military users for it can offer a higher tolerance to jamming and spoofing than C/A code. Therefore, it always attracts the interest of the researchers, but at the same time, direct P(Y)-code acquisition is difficult as its long period and high chip rate. An algorithm named odd and even folding acquisition search technique is proposed here. This method divides the local P code into odd and even reference sequences. Through some simple operation of folding and subtracting, the two sequences produce a sequence used as the new reference code sequence. Using the combined reference code, the search scope of code phase is enlarged as we expected. In addition, the sampling rate of incoming signal is reduced which benefits for the Doppler searching as the increasing of frequency searching precision. Description of odd and even folding acquisition search technique and preliminary simulation are given here. From the analysis and simulation results, we can draw a conclusion that this acquisition search technique is fitting for the direct acquisition of GPS P(Y)-code.