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根据天文摄影中CCD的工作特性,提出了基于嵌入式技术制冷CCD相机的新方法,以ARM微处理器为硬件平台设计了嵌入式制冷CCD相机,并在低照度下的天文观测中取得了良好的效果。基于天文制冷CCD的具体特性和对信号数据输出的要求,选用CXD1267和AD9826分别设计CCD的列转移驱动时序和CCD的水平读出时序。通过微处理器定时中断,实现对CCD制冷温度的实时控制。分析了科学级CCD噪声的种类及来源,通过实验得到了温度、曝光时间与暗电流噪声的关系以及CCD的读出速率与读出噪声的关系。进而在硬件和软件上采取了相应的措施有效地降低了CCD的噪声。
According to the working characteristic of CCD in astronomy photography, a new method of CCD camera based on embedded technology is proposed. An embedded refrigeration CCD camera is designed based on ARM microprocessor, and the astronomical observation under low illumination is good Effect. Based on the specific characteristics of astronomical refrigerating CCD and the requirement of signal data output, CXD1267 and AD9826 were chosen to design the CCD column transfer driving timing and CCD horizontal readout timing respectively. Timer interrupt through the microprocessor to achieve real-time control of CCD refrigeration temperature. The types and sources of CCD noise are analyzed. The relationship between temperature, exposure time and dark current noise and the relationship between CCD readout rate and readout noise are obtained through experiments. Then in the hardware and software to take appropriate measures to effectively reduce the CCD noise.