基于谱相关的干扰抑制滤波器研究

Interference Rejection in DSSS Based on Spectral Correlation Method

众多的扩频通信抗干扰技术往往把有用扩频信号近似看作平稳随机过程。事实上 ,由于伪码的周期性而导致的循环平稳是扩频信号的一个重要特征。基于一般循环平稳理论 ,详细分析了直接序列扩频信号的谱相关特性 ,并在此基础上讨论了谱相关抗干扰滤波器的设计方法及其自适应形式。该方法通过对被污梁扩频信号先频移、再滤波后相加得到其估值 ,充分利用其不同频谱处的相关性 ,避免了一般抗干扰方法中由干扰建模带来的模型不匹配问题。因此 ,谱相关抗干扰滤波器可用于宽带和窄带干扰抑制。

In a lot of antijamming techniques for direct spread spectrum system (DSSS), the DSSS signal is approximately considered as a stationary process. In fact, as the result of the period of a PN code, cyclostationarity is a key property of DSSS signal. Based on the theory of cyclostationary process, the spectral correlation properties of DSSS signal are analyzed in this paper. The method to design the spectral correlation antijamming filter is also proposed. In this method DSSS signal is estimated by summing up the filtered and frequency shifted versions of the observations and the spectral correlation of the DSSS signal is fully utilized. Effective to avoid the model unmatching, the method can be applied to the rejection of both wideband interference and narrowband interference. The results of computer simulation show the effectiveness of the method.