摘要
利用星敏感器进行白天大气层内观星,首先要解决的问题是强天空背景的干扰。通过对白天天空背景和不同光谱恒星的特点进行分析,提出了光谱滤波和偏振成像加形态学滤波和多帧图像累加的技术路线,综合利用光学方法和图像处理方法提高观测对比度和信噪比。给出了白天观星的信噪比模型,并在不同天空背景偏振度条件下,得出了G、K、M光谱恒星的0至5等星的单帧图像信噪比和对应的使CCD(Charge Coupled Device,电荷耦合器件)接近饱和的极限曝光时间。结果表明:星等值越低,天空背景偏振度越大,则信噪比越高;同等条件下,信噪比由小到大依次为G、K、M光谱恒星;而对于低信噪比的图像,通过多帧累加后可满足观测的要求。
To observe stars from the atmosphere in daytime with a star sensor,the interference of strong background is the first problem to be solved.The characteristics of the sky and stars are analyzed,and a technical approach using spectral filter,polarization imaging,morphological filter and multi-frame accumulation is proposed.The contrast and signal-to-noise ratio are improved by using optical method and image processing method.The signal-to-noise ratio model in daytime is given.In different sky polarization conditions,the signal-to-noise ratio and the max exposure time of G,K,M stars from magnitude 0to 5are obtained.The results show that the lower the magnitude,the higher the signal-to-noise ratio,and the higher the sky polarization,the higher the signal-to-noise ratio.Under the same conditions,the signal-to-noise ratios are in order of G,K and M from high to low.The low signalto-noise ratio images can be observed by using multi-frame accumulation.
出处
《飞行器测控学报》
CSCD
2015年第3期291-297,共7页
Journal of Spacecraft TT&C Technology
基金
航天科技创新基金(CASC2013)
关键词
星敏感器
光谱滤波
图像处理
信噪比
star sensor
spectral filtering
image processing
signal-to-noise ratio
