Acquisition speed-up engine for GNSS signals

In this paper we present the Acquisition Speed Up Engine (ACSE) algorithm, devised in 2007 by Thales Alenia Space in the framework of studies for the GIRASOLE receiver and implemented by Consorzio Pisa Ricerche. The algorithm is used to fast detect the presence of a CDMA signal in a time/frequency uncertainty domain. This is made possible with a serial/parallel approach and a modified FFT algorithm called Fast Fractional Fourier Transform. The ACSE algorithm solves in a very efficient way the trade-off between acquisition time, computational and implementation complexity. The concept was finally proved throughout the implementation on a Xilinx Virtex IV FPGA for a final occupation of 37.9% and a maximum implementation loss of 1 dB.