基于综合时频分析的机动目标ISAR成像

传统的ISAR距离-多普勒成像算法基于目标平稳飞行假设。当目标作机动飞行时,转速和转轴经常是时变的,若用传统方法成像,会使图像模糊,甚至无法辨识。这时需要分距离单元进行时频分析,得到距离-瞬时多普勒图像。文中提出的综合平滑伪魏格纳分布克服了平滑伪魏格纳分布不能在时频分辨率和抑制交叉项两方面同时达到较好的缺点。最后以旁瓣电平、交叉项干扰抑制、方位分辨率损失等指标定量分析了两者的性能。仿真结果证实了文中方法在对机动目标成像中的优越性。

ISAR Imaging of Maneuvering Radar Targets Based on Combined Time-Frequency Analysis Method

When the target moves irregularly, the Doppler frequency of each scatterer and the imaging projection plane of a maneuvering target may change with time. The traditional RD algorithm is no longer suitable to the maneuvering target. In this case, time frequency analysis must be performed for every range cell to obtain range instantaneous Doppler (RID) image. The proposed combined smoothed pseudo Wigner Ville distribution (CSPWVD) is better than smoothed pseudo Wigner-Ville distribution (SPWVD). The SPWVD sacrifices time frequency resolution in order to remove cross terms, but CSPWVD can not only reduce the cross terms but also maintain good time-frequency resolution. Furthermore, we performed a statistical analysis to evaluate the improvement of the CSPWVD technique versus the SPWVD in term of sidelobe level (SLL), cross terms reduction (CTR) and azimuth resolution losses (RLs). Simulation data demonstrate that CSPWVD can get good radar imaging for maneuvering targets.