A Self-Adaptive Fast Direct Acquisition Approach for Long PN Code in the High Dynamic Circumstance

The direct P code acquisition plays an irreplaceable role in current GNSS system. Meanwhile, it is difficult to do the synchronization directly especially in the circumstance where the high dynamic range and the faintness of signal can’t be ignored. The Dual Channel approach and Dual Folding approach have been proposed to acquire the P code respectively in high dynamic situation and in low SNR situation, but the former one is not fast enough to synchronize P-code, and later one is easily influenced by Doppler Effect. To improve the detection performance with high dynamic range, a new method named Auto Switch Approach (AS) is proposed in this paper. By designing a shift module which responds to Code Doppler and SNR, this AS approach combines DF and DC to adapt to tougher situation with higher detection probability and less mean acquisition time than each single method. Numerical results demonstrate the enhancement of the proposed method. Keywords: synchronization, direct sequence spectrum, high dynamic range, code Doppler adaptive