A digital feedforward acquisition algorithm for DS-SS transmissions

This paper presents a new digital feedforward algorithm applicable in DS-SS signals acquisition when the PN code employed is not very long. The algorithm is at first developed in noise free environments, and then analyzed in the presence of a white Gaussian noise. As the acquisition time is fixed (T_acq=NT_c), the main parameter of interest is the acquisition error probability. A numerical computation shows that, when only one DFT sample is used, the results obtained are very poor. Therefore, an extended feedforward algorithm is developed, which uses all the samples of the DFT and makes a statistical mean. The results obtained using this extended algorithm are considerably better but it still needs to be followed by a second one, which use the a priori information to achieve a small acquisition time, while the acquisition probability is unitary