A Hierarchical Acquisition Algorithm for High Dynamic Weak DSSS Signals

To solve the contradictions between Doppler frequency offset estimation accuracy and fast Fourier transform( FFT) operation points in classical acquisition algorithm for direct sequence spread spectrum( DSSS) signal in high dynamic environment with low signal- to- noise ratio( SNR),this paper proposes a two- stage noncoherent integration acquisition algorithm based on frequency offset compensation. This algorithm is based on the partial match filter combined with FFT( PMF- FFT). Firstly,Doppler frequency offset is compensated by coarse frequency offset estimation. Secondly,through adjusting subsequent PMF length and adopting the moving- average technique,the residual frequency offset is accurately estimated. Both analysis and simulation show that,compared with classical acquisition algorithm,the proposed algorithm can effectively enhance the accuracy of Doppler frequency offset estimation when FFT operation points are the same,and has higher detection performance in high dynamic environment.