窄带干扰环境下DS-SS信号的细微特征分析

Particular Eigen-Structure of DS-SS Signals Under Narrow Band Interferences

通过对窄带干扰(NBI)条件下低信噪比直接序列扩频(DS-SS)信号的细微特征分析,得到了NBI特征波形和DS-SS扩频伪码(PN)的盲估计。首先按PN码周期和码速率(假设已获知)对接收DS-SS信号进行取样预处理形成观察向量集,接着用细微特征分析方法对该集合进行处理,最后可以估计出信号所夹杂的NBI特征波形和信号的PN码序列。为了减少所估计PN码的相位模糊性,本文在取样预处理时将取样时间窗口增大到PN码周期的二倍,结果使所估计的PN码或是原码或是反码,从而提高了估计准确性。同时利用所估计的NBI特征波形可消除原始信号所夹杂的NBI,而利用所估计的PN码序列则可以对DS-SS信号实施盲解扩处理。理论分析和数值结果表明,该方法有效,并能工作在较低的输入信噪比和信号干扰比环境下。

A modified approach based on eigen-analysis of direct sequence spread spectrum （DS-SS） signals under narrow band interferences （NBIs） is proposed. It can estimate the eigen-waveforms of NBIs and pseudo noise （PN） sequence of DS-SS signals blindly on the low signal noise ratio （SNR） and signal interference ratio （SIR） DS-SS signals. Some parameters, such as period and chip interval of the PN sequence, need to be known. Firstly, the received signal is divided into non-overlapplng temporal vectors according to two times of the period of the PN sequence, then the approach based on eigen-analysis is used to process the vectors one by one. Finally, the NBI eigen-waveforms and the PN sequences of the signals can be blindly estimated. Based on the estimated NBI eigen-waveforms and the PN sequences, NBIs can be rejected, and the DS-SS signals despreading without the PN code can be realized too. Theoretical analysis and experimental results show that the approach is effective and works well in the lower SNR and SIR ambient.