Combined the characteristics of underwater DS/SS signals author simulated the ocean acoustics channels and used both the 2 methods to detect and estimate signals, finally compared the performance of 2 metho.

DSSS Signal Parameter Estimation;

In order to solve the problem of direct sequence spread spectrum signal s check and recognition,a blind estimate algorithm is proposed,it based on cyclic spectrum theory and matrix transform.

How to acquire the pseudo-random code type of DS-SS signals is an important problem in obtaining the information from the DS-SS signals.

The cyclostationary property of multipath DS signals is analyzed,the expressions of both the cyclic correlation function and cyclic spectrum are deduced,and a novel parameter estimation algorithm of DS signals is presented based on cyclic spectrum amplitude.

DS signal is a second order cyclostationary signal.

Based on this theory, the paper puts forward the DS signal detection method in non-cooperative communication.

One is the detection of low SNR DSSS signal and extraction of length of PN code, the other is detection of BPSK signal from multi signals.

A method of DSSS signal detect quickly in lower S/N is presented in this paper.

Based on the periodicity of DSSS signal’s short-time Fourier spectrum,this paper proposed a detection method of DSSS signal based on short-time Fourier transform(STFT)--periodical variance threshold searching method of periodical pulse.