Parameters Estimation And Simulation Of The Direct Sequence Spread Spectrum Signal

Nowadays, the Direct Sequence Spread Spectrum(DSSS) Signal has been widely used in military communications and civilian communications, and it has the following features: low emission power spectral density, low probability of intercept, to realize the function of Code Division Multiple Access (CDMA) and so on. Communications reconnaissance systems are difficult, since the spread spectrum communication system has the strong capabilities of anti-jamming and anti-interception. Accordingly, it is significant to detect the DSSS signal and estimate their parameters.First of all, we introduce the basic theory of direct sequence spread spectrum communication system and the characteristics of pseudo-random sequence, and then introduce the basic theories and estimation algorithms based on power spectral estimation, high-order cyclic cumulants and cyclic spectrum theory, which are used in the DS signal detection. The focal point is the blind detection and parameter estimation methods of direct sequence spread spectrum signal, the main work includes: Analysis of signal detection and carrier frequency estimation using power spectral estimation methods, and proposal that cumulants can improve the performance of power spectral estimation in low Signal to Noise Ratio(SNR), signal modulation recognition and carrier frequency estimation based on cyclic high-order cumulant, carrier frequency estimation using the cyclic spectrum theory; chip rate estimation based on cyclic auto correlation and cyclic spectrum theory. At last, we simulate these methods and compare the effects on estimation caused by SNR and signal lengths to prove the feasibility.