在基于压缩感知的分布式多输入多输出(MIMO)成像雷达系统中,若成像目标不在事先划分的网格点上,即存在网格失配(Off鄄Grid)偏差时,成像结果将急剧恶化,文中针对该问题,分别在Off鄄Grid 偏差一阶和二阶近似下提出了行之有效的解决方法。文中首先建立了系统存在Off鄄Grid 偏差时的回波模型,在理想划分网格点的基础上,将Off鄄Grid 偏差看作未知数,分别进行一阶和二阶Taylor 展开,建立扰动模型,分析Off鄄Grid 偏差对成像结果的影响,最后给出了一种采用欠定系统局灶解法(FOCUSS)和约束总体最小二乘(CTLS)方法联合估计目标位置和散射系数的算法。与传统的基于压缩感知的成像方法相比,文中所提出的算法能够很好地解决网格失配问题,提高目标的反演精度。计算机仿真结果验证了所提方法的有效性。

In distributed MIMO radar system based on compressive sensing, if the imaging target is not positioned at the pre-discretized grid locations, that is to say, there exists Off-Grid deviation in the system, the imaging results will be deteriorated sharply.In order to solve this problem, an effective solution under one order and two order approximation of Off-Grid deviation respectively is proposed in this paper. The echo model when there exists Off-Grid deviation in the system is established first and then, based on the ideal discretized grid, the perturbation model is established by regarding the Off-Grid deviation as unknown and carrying out one order and two order Taylor expansion of it. After that, the influence of Off-Grid deviation on imaging result is analysed. Finally, the algorithm based on FOCUSS and CTLS is proposed to jointly estimate the target location and its scattering coefficient. Compared with the traditional imaging method based on compressive sensing, the algorithm proposed in this paper can solve the Off-Grid problem effectively and improve the inversion accuracy of target recovery. The effectiveness of the proposed algorithm is confirmed by several experimental results.

TN957.52