A Fast Acquisition Algorithm Based on Two Stage Difference and Keystone Transform

Aiming at the problem of limited accumulation time and dynamic influence on coherent accumulation in the acquisition of very low signal-to-noise ratio(SNR) and high dynamic Direct Sequence Spread Spectrum (DSSS) signals, a fast acquisition algorithm based on two stage difference combined with keystone transform is proposed. Firstly, the algorithm uses the two stage differential delay autocorrelation method to eliminate the influence of data bit jump and carrier doppler frequency, so that the correlation accumulation time is no longer limited by data bits. Secondly, the keystone transform is used to solve the problem of pseudo-code phase walk caused by high dynamic in long time accumulation. Finally, the carrier Doppler frequency is calculated by difference. The simulation results show that the algorithm can effectively solve the problem of data bit jump and dynamic influence in long time accumulation of DSSS signal in very low SNR and high dynamic scene.