Abstract:

This paper deals with the issue of direct sequence spread spectrum (DSSS) signal interception and parameter estimation, and a novel algorithm based on delay-multiply and energy accumulation is proposed. This algorithm is derived from the fact that the accumulated energy reaches the maximum if information modulation and spread spectrum modulation are both removed from the received DSSS signal. Received samples are divided into continuous segments, signal energy is accumulated for all the segments, and the length of segment equals to the information interval when accumulated energy reaches the maximum. Consequently, the PN code and information sequence can also be extracted. The algorithm presents robust features since no prior knowledge and preset thresholds are required. In the condition of additional white Gaussian noise (AWGN), theoretical analysis and simulation results indicate that given a processing gain G_p dB, the proposed algorithm has good performance when the input  singal to noise ratio (SNR) is more than -G_p/2 dB.