秩-相位誤差估計自聚焦方法的改進
IMPROVEMENT OF AUTOFOCUSING TECHNIQUE FOR RANK ONE PHASE ERROR ESTIMATION
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摘要: 本文提出了改進的秩-相位誤差(IROPE)估計自聚焦算法。與ROPE算法相比,IROPE有兩個優(yōu)點:(1)它基于的模型更符合實際,所以具有更好的魯棒性。(2)它對迭代過程初值的設定是近似準確的。本文通過近似分析證明,IROPE對相位誤差差分的估計是最大似然(ML)估計,而相位梯度自聚焦(PGA)算法是IROPE的一個子集,即在滿足一定條件時,IROPE和PGA對相位誤差的估計都是線性無偏最小方差估計(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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