基于随机共振理论的双基ISAR弱信号提取及成像分析

Weak Signals Extraction and Imaging Analysis in Bistatic ISAR Systems Based on Stochastic Resonance

在双基地逆合成孔径雷达成像系统中,针对强背景噪声中的目标弱散射点探测和识别问题,基于能捕获目标强散射点的假设前提,提出了应用随机共振理论的弱散射点检测方法.首先对作解线调后的回波信号进行快时间轴变换处理,并对处理后的信号进行二次采样使其满足绝热近似条件;然后应用随机共振技术检测出代表瞬时距离差的弱周期信号频率,并通过循环检测和正负频率判断等后续处理提高系统的检测信噪比以及确定弱散射点的正确位置.最后对随机共振性能和双基ISAR成像进行了仿真.结果表明:随机共振能大幅提高弱周期信号的输出信噪比,应用在双基ISAR系统中能有效提高系统的信噪比增益和扩大雷达接收机的动态范围.

In the bistatic ISAR systems,in order to solve the problems of weak scatters detection and identification in strong noise background,the stochastic resonance（SR） was applied to extract the information of weak scatters.On the assumption that the strong scatters could be detected,the signals after de-chirp were disposed through transformation in fast time axis firstly,which made the signals satisfy the condition of adiabatic approximation;then the SR was used to detect the signal frequency that expressed the instantaneous range difference;after that,some processing were implemented to confirm the right positions of weak scatters and to improve the output signal-noise-ratio（SNR）.Numerical simulations shows that the SR can improve the SNR largely and enlarge the dynamic bound of radar receiver.