.dsss / Bpsk Signal Parameter Estimation Methods

Direct sequence spread spectrum (DSSS) communication systems have the characteristics of wide spectrum, low working Signal-to-Noise ratio (SNR), anti-interference, anti-multipath effect, capability of CDMA, LPI and LPD. They are increasingly replacing conventional communication forms and obtaining extensively applications in modern military and commercial communication systems, for example, CDMA communication system, GPS , measuring and control system, satellite chain, identification of friend or foe and etc. Therefore, corresponding DSSS electronic counter technique becomes a big problem to solve in electronic warfare domain.For the issue of blind parameter estimation of DSSS/BPSK signal damaged by strong additive white Gaussian noise (AWGN), this dissertation mainly researches on carrier doubler method (CDM), auto-correlation method (ACM), delay-and-multiply (DM) method and fourth-order cumulant 2-D slice method . The followings are the main research content in this dissertation:1.The carrier estimation theory of CDM and the reason of high difficulty on low SNR estimation are analyzed. In order to obtain lower SNR estimation, spectrum accumulation average technique (AAT) and cross-correlation accumulation technique (CCAT) are added to the output of CDM processing, several improved methods are proposed, and obtain lower SNR limitation effectively.2.The symbol period estimation theory of ACM is researched. Based on analysis on the generation mechanisms of auto-correlation peaks, ACM is combined with average technique in correlation domain. Average technique not only smoothes noise correlation lines, but also makes all potential positions of generating auto-correlation peaks generate auto-correlation peaks of DSSS/BPSK signal. The improved ACM obtain lower SNR limitation successfully.3.Chip rate estimation theory of DM method is studied. The research object of traditional DM method is the output of base-band DSSS/BPSK signal delay and multiplication processing or the base-band component of output of IF DSSS/BPSK signal delay and multiplication processing. By analysis, we have found that the output of IF DSSS/BPSK signal delay and multiplication processing is composed of...