Low Complexity Bistatic Forward-looking SAR Extended NLCS Algorithm Based on Chirp-z Transform

Due to the special geometric configuration of transmitter and receiver, bistatic synthetic aperture radar (SAR) can image the forward-looking area with high resolution, and has important application value in the fields of precision guidance, autonomous landing, and enemy strike. However, bistatic forward-looking SAR has severe 2-D coupling in echo, and the imaging algorithm requires more complex processing flow. Although the extend nonlinear chirp scaling (ENLCS) algorithm can effectively solve the problem of space-variant migration and Doppler parameters under this configuration, it brings a certain amount of data redundancy in the process of mapping radar data from the echo domain to the image domain. Moreover, the azimuth processing of ENLCS is too long, causing a great increase in computational load and storage costs, and it is difficult to meet the real-time requirements of related fields. In order to reduce the computational complexity and data redundancy of the ENLCS algorithm and improve its efficiency of the real-time processing, this paper utilizes Chirp-z transform (CZT) structure to realize the Keystone transform (KT) without interpolation in the process of range cell migration correction (RCMC) to reduce the computational complexity. In addition, linear factor is added to the ENLCS equalization process, which significantly reduces the amount of redundancy in the data mapping process, and further accelerates the azimuth processing process of the algorithm, which is lower in overall operation and time-consuming than that of the original algorithm. The simulation experiment results verify the effectiveness and timeliness of the proposed algorithm.