Implement and performance analysis of PN code acquisition based on FFT

Direct sequence spread spectrum (DS-SS) technique is more and more used in telemetering, telecontrol and communications today. Acquisition of PN code is the key technique as to ranging terminal and spread spectrum receiver. However, the large Doppler which low earth orbit satellites (LEOS) channel experiences can exceed several tens of kHz and makes the acquisition of PN code especially difficult, and the short time of LEOS passing the visual field necessitates quick acquisition of PN code. The conventional PN code acquisition scheme is based on carrier frequency and code phase 2-dimensional searches. The PFT-based approach reduces the 2-dimensional searches to 1-dimensional code phase search, so it largely accelerates the synchronization process compared to conventional technique and is more suitable for wide range of Doppler shift. The relation between the selection of parameters and the mean time of acquisition is analyzed and the experiment results that verify the theory analyses are introduced.