摘要
星敏感器曝光时间是影响星敏感器星点定位精度的因素之一。建立星敏感器星点像移模型和CCD噪声影响模型,分析了星点质心定位精度与曝光时间的关系,并以CCD47-20为例,对星敏感器的曝光时间进行了优化。结果表明:对于6.5等星,当星点光斑像移速度为4.67pixels/s时,采用5×5窗口的亚像元质心算法,亚像元质心算法精度随曝光时间的延长而降低,CCD噪声对星点质心定位精度的影响随曝光时间的增加而减小;星敏感器的最佳曝光时间为200ms,此时的星点质心定位精度优于1/50pixel。
Exposure time＇has effect on position accuracy of star sensor. In this paper, motion model of star spot which is combined with the effect of CCD noise has been established. The centroid accuracy of the star spot affected by sub-pixels arithmetic and CCD noise were analyzed at different exposure time with CCD47-20 chip, and the optimum exposure time was calculated. The results show that the accuracy of arithmetic was degraded and the accuracy of star spot affected by CCD noise was decreased when the exposure time increased. The optimum exposure time is 200 ms when the motion rate is 4.67 pixels per second for a single star of 6.5 magnitude, and the star spot location accuracy is better than 1/50 pixel with 5×5 window.
出处
《光电工程》
CAS
CSCD
北大核心
2009年第12期22-26,共5页
Opto-Electronic Engineering
