基于最小熵梯度的调频步进自聚焦算法  

A Novel Autofocus Algorithm Based on Minimum Entropy Gradient for Stepped Frequency Chirp

作　　者：柴振岭 刘琰 赵国清 龙杰 CHAI Zhen-ling;LIU Yan;ZHAO Guo-qing;LONG Jie(System Integrated Research and Development Center,Bejing Institute of Control&Electronics Technology,Beijing,100038)

机构地区：[1]北京控制与电子技术研究所系统综合研发中心,北京100038

出　　处：《计算机仿真》2020年第7期276-280,共5页Computer Simulation

摘　　要：针对调频步进信号的频域宽带合成处理中存在子带相位误差,导致子距离像主瓣展宽、旁瓣升高、分辨率降低,合成距离像栅瓣提高甚至图像畸变的问题,采用了一种以最小熵梯度为准则的方法,通过搜索估计完成校正。首先建立子带相位误差模型,然后根据BFGS算法构造熵梯度函数,并对相位误差模型系数进行迭代估计,最后构造相位误差校正因子进行校正。通过对点目标数据的仿真和实测数据的处理,结果显示子带相位误差对距离像的影响得到了有效的降低,达到了校正的目的,证实了该方法的有效性。For the difficulty of sub-band phase error in frequency-domain broadband synthesis of stepped frequency modulation signal,which leads to the widening of main lobe,the increase of side lobe,the decrease of resolution,the increaes of grating lobe and even the distortion of image,a novel algorithm based on minimum entropy gradient was proposed,and the correction was completed by searching and estimating.Firstly,the sub-band phase error model was established,then the entropy gradient function was constructed according to the BFGS algorithm,and the coefficients of the phase error model were estimated iteratively.Finally,the phase error correction factor was constructed to correct the error.Through the simulation of point target data and the processing of measured data,the results show that the influence of sub-band phase error on range profile has been effectively reduced,and the purpose of correction has been achieved,which shows the effectiveness of the method.

关 键 词：调频步进 频域宽带合成 相位误差 最小熵 梯度 

分 类 号：TN957[电子电信—信号与信息处理]