Evaluation of a FFT-Based Acquisition in Real Time Hardware and Software GNSS Receivers

The first step of the digital processing within a Global Navigation Satellite System (GNSS) receiver is the signal acquisition. The receiver has to detect the satellites in view, and for each of them, has to estimate the Doppler shift and the code phase of the received signal. In order to speed up the acquisition process, modern receivers use fast acquisition technique based on the Fast Fourier Transform (FFT). This paper presents the complexity evaluation of a FFT-based acquisition technique, suitable for new GNSS signals and for both software and hardware implementations. After the description of the algorithm, the focus will be on the comparison of the results obtained with a Xilinx FPGA board and a software receiver implemented on a general-purpose processor.