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| Minimizing Sum of Image Amplitudes Autofocus Algorithm |
| Liu Bi-dan①②; Han Song①; Wang Yan-fei① |
| ①Institute of Electronics, Chinese Academy of Science, Beijing 100190, China;②Graduate University of the Chinese Academy of Science, Beijing 100039, China |
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Abstract High resolution Synthetic Aperture Radar (SAR) imaging requires that the azimuth frequency modulation rate is accurately estimated. A new autofocus algorithm is presented which minimizing sum of amplitudes in this paper. This paper analyses the relationship between the image contrast function and the sum of amplitudes, when the matched function’s amplitude in azimuth direction is invariable. Based on the relationship between the image contrast function and the focus degree of the image, the minimizing sum of amplitudes autofocus algorithm is presented. The performance of this algorithm is verified by the computer simulation and RADARSAT-1 raw data imaging. Experimental results show that the algorithm has better convergence speed and estimation accuracy than traditional Map Drift (MD) auto focus algorithm. It has better convergence speed and less computation cost than the Contrast Optimization Autofocus Algorithm (COAA). It can be implemented by hardware easily and help to improve the performance of real time imaging processor.
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Received: 25 December 2007
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2009, Vol. 31 
