多子带STAP方法的角度模糊抑制性能分析

Performance Analysis of Angular Ambiguity Elimination for Multi-Subband STAP

在宽带多通道雷达系统中,常采用多子带空时自适应处理(Space-Time Adaptive Processing,STAP)方法以实现运动目标检测及参数估计。本文对多子带STAP方法在稀疏阵列中的角度模糊抑制性能进行了分析。建立了多子带STAP模型并结合方法的实现过程,首次给出多子带STAP改善因子(Improvement Factor,IF)的解析式,并说明由于不同中心频率IF对应的模糊凹口位置不同,多子带相干叠加能在一定程度上填平模糊凹口,减轻盲速现象。还给出信杂噪比损失(Signal-to-Interference-plus-Noise Ratio Loss,SINRLoss)的解析式,该表达式表明:各子带SINRLoss的峰值位置随中心频率变化,因此在多子带重组后虚假目标的输出弱于真实目标,从而减轻了重复检测现象。由此,多子带STAP方法能在一定程度上抑制天线稀疏放置引起的角度模糊,即减轻盲速和重复检测现象。本文还分析了多子带STAP方法的角度模糊抑制能力和雷达系统相对带宽之间的关系,结果表明:系统的相对带宽越大,多子带STAP方法的角度模糊抑制能力越强。对于理想条件下的四通道系统,若信号的相对带宽大于46.3%,该方法能完全消除角度模糊的影响。生成仿真的四通道超宽带合成孔径雷达(Synthetic Aperture Radar,SAR)稀疏阵列回波数据,进行运动目标检测和参数估计,从而验证了多子带STAP方法的角度模糊抑制能力。

The Multi-Subband Space-Time Adaptive Processing（STAP） is usually used in wideband multi-channel radar system to realize moving target detection and parameter estimation.This paper analyzes the performance of eliminating angular ambiguity for Multi-Subband STAP in sparse array.We set up the multi-subband STAP model firstly.And then the realization procedure of the method is exploited to derive the analytic form of multi-subband Improvement Factor（IF）.This analytic form indicates that due to the different ambiguous notches＇ positions of IF corresponding to the different central frequencies,these notches could be leveled up after correlated integration of multiple subbands,and thus the phenomenon of blind velocity could be alleviated.We also derive the analytic form of Signal-to-Interference-plus-Noise Ratio Loss（SINRLoss）.This expression demonstrates that because the positions of peaks of different subbands＇ SINRLoss vary with the central frequencies,the outputs of pseudo targets are weak than that of the true target after multiple subbands recombination,and thus the phenomenon of repeated detection could be suppressed.Thereby the method of Multi-Subband STAP can suppress the angular ambiguity caused by sparse array configure in a certain extent,which means the phenomena of blind velocity and repeated detection are released.The paper also analyzes the relationship between the method＇ s performance of eliminating angular ambiguity and the relative bandwidth of the radar system.The result shows that the larger the relative bandwidth of system is,the better the performance gets.As for a four-channel sparse array system with relative bandwidth larger than 46.3%in an ideal case,the effect of angular ambiguity can be eliminated totally via the Multi-Subband STAP method.The echo data of four-channel ultra-wide band Synthetic Aperture Radar（SAR） sparse array are simulated,and then an experiment of moving target detection and parameter estimation is carried on,which validates the performance of eliminating angular ambiguity of the method.