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IMPROVEMENT OF AUTOFOCUSING TECHNIQUE FOR RANK ONE PHASE ERROR ESTIMATION |
Li Liwei; Asif Raza; Mao Shiyi |
Dept. of Electron. Eng., Beijing University of Aeronautics and Astronautics Beijing 100083 |
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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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Received: 27 February 1998
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