秩-相位误差估计自聚焦方法的改进
IMPROVEMENT OF AUTOFOCUSING TECHNIQUE FOR RANK ONE PHASE ERROR ESTIMATION
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摘要: 本文提出了改进的秩-相位误差(IROPE)估计自聚焦算法。与ROPE算法相比,IROPE有两个优点:(1)它基于的模型更符合实际,所以具有更好的鲁棒性。(2)它对迭代过程初值的设定是近似准确的。本文通过近似分析证明,IROPE对相位误差差分的估计是最大似然(ML)估计,而相位梯度自聚焦(PGA)算法是IROPE的一个子集,即在满足一定条件时,IROPE和PGA对相位误差的估计都是线性无偏最小方差估计(LUMV)。Abstract: This paper presents an improved rank one phase error estimation(ROPE) autofo-cusing technique. Compared with ROPE, the improved algorithm has two distinct advantages: first, its model is more actual, so its property of robustness is better; second, at the begining of its iteration process, the initialized valves are set up approximately. Through approximate analysis, this paper proves that the improved algorithm s estimation of phase error is maximum-likelihood (ML), and, under some special situaitons, its estimation is the same as that of phase gradient autofocus (PGA), which is linear unbiased minimum variance (LUMV) estimation. PGA is a subset of this improved autofocus algorithm. Finally, some simulation results are given.
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