A fast algorithm for long code direct acquisition

In GPS (Global Position System), direct acquisition of the GPS P(Y)-code is a two-dimension lengthy searching process in time and frequency dimension. CCPAZP-FFT (Circular Correlation by Partition And Zero Padding) uses FFT to achieve parallel correlation and frequency searching. In this way acquisition can be achieved very fast as it transfers two-dimensional search into parallel one-dimensional search. However, correlation points are still too much and Computation is heavy. This paper proposes an improvement algorithm of combination of CCPAZP-FFT and XFAST. This way Compares to CCPAZP-FFT is reduced by two thirds of the computation in order to achieve rapid long code acquisition.