基于俯冲模型的频域距离走动校正NLCS-SAR成像算法

弹载SAR末制导阶段的高速、俯冲、大斜视等特点使得常规SAR成像算法失效，为此，该文首先建立了精确的俯冲SAR回波信号模型，并根据大斜视下距离徙动主要由距离走动构成这一特点，先行补偿距离走动以使大斜视成像转化为等效小斜视或正侧视成像，简化后期成像处理，而后再利用方位向非线性变标方法解决补偿距离走动带来的多普勒调频率随方位时间空变问题，使得同一距离门的方位压缩可在相同参数下进行，从而有效增大方位向的聚焦深度。仿真实验验证了算法的有效性。

NLCS-SAR Imaging Algorithm with Range-walk Correction in Frequency Domain Based on Dive Model

The ordinary SAR imaging algorithms are inapplicable to missile-borne terminal guidance SAR due to its properties of high-speed, dive and high-squint. Based on the precise SAR echo signal in dive model, this paper proposes a new imaging algorithm of pre-correcting range-walk in frequency domain to translate high-squint imaging into equivalent low-squint even zero-squint one to simplify imaging processing. The pre-correction of range-walk will cause the variation of Doppler rate with azimuth time, which can be solved effectively by the azimuth Non-Linear Chirp Scaling (NLCS) processing. Therefore, after the azimuth NLCS processing, the azimuth compression in the same range gate can be carried out with the same Doppler parameters so that the azimuth Depth of Focus (DOF) can be improved. Simulation experiments validate the effectiveness of this algorithm.