METHOD AND SYSTEM FOR SPREAD SPECTRUM SIGNAL ACQUISITION

摘要

A method (100) is described, for acquiring a direct sequence spread spectrum signal (s(t)), which is transmitted on a carrier frequency and is modulated with a code signal of length equal to Nc chips, for determining a code delay of said spread spectrum signal and a Doppler shift with respect to said carrier frequency, said determination being performed on a discrete two-dimensional space of M possible code delays and F possible frequency shifts, the method (100) comprising the following steps: - receiving and sampling (102) said spread spectrum signal in order to obtain a sampled spread spectrum signal; - performing a despreading operation (103) of said sampled spread spectrum signal with a local replica signal of said code signal, by performing said despreading for a plurality of possible code delays between said sampled signal and said replica signal; - performing a parallel frequency search (104, 105, 107, 108, 109) on the result of said despreading step, by performing a step (104) of computing a Fourier transform on said result. The Fourier transform is a fractional Fourier transform.