共查询到20条相似文献，搜索用时 124 毫秒
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为了测试用于中国南极小望远镜阵的CCD控制器视频采样电路的性能并对其进行低温可靠性验证,设计了一款基于现场可编程门阵列的CCD视频波形发生器,它能产生CCD探测器输出的视频波形。上位机通过USB2.0接口与视频波形发生器进行指令通讯,可以改变波形的幅度、周期、上升沿时间以及叠加的噪声。通过设定不同参数的波形输入CCD控制器的视频采样电路,可以在不同温度下对电路的性能进行充分测试,不仅提高了测试效率而且有效地避免了安装CCD测试造成的风险。测试结果表明,CCD控制器的视频采样电路性能满足要求并可以在低至-80℃下稳定工作。 相似文献
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该文详细地介绍了相位校准单元的电路和数学原理以及测试结果。在电路原理部分主要介绍相位校准单元的工作原理、各个关键点的波形以及用隧道二极管产生梳状谱的典型电路。数学原理主要阐述了测量梳状谱的数学依据。最后给出了该相位校准单元的测试要求和测试结果。 相似文献
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针对被动型铷原子频标电路模块中由三极管等数量众多的分立元件搭建的9倍选频放大模拟电路和种类繁多的集成电路搭建的5.3125 MHz综合器电路,给出了数字化电路解决方案。在此新方案中,通过使用一种复杂可编程逻辑器件对锁相环进行编程控制,可以实现对10 MHz参考信号18倍频的精确控制;同时,利用该复杂可编程逻辑器件内部"虚拟"的集成电路对10MHz参考信号进行分频变换可以得到5.3125MHz信号。实际使用证明,这种设计方案具备易于集成、调试简单的优点,在替换原有模拟倍频、综合器功能电路后,成功实现整机锁定,各项性能指标均达到或优于原有水平,使整机向数字化、小型化迈出重要的一步。 相似文献
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《天文研究与技术》2020,(3)
星载氢原子钟具有频率稳定度高、频率漂移率低的优点,在卫星导航定位和频率计量中得到了广泛应用。星载氢原子钟的腔泡系统用于实现氢原子的量子跃迁及其信号采集,原子跃迁信号幅度直接决定了系统的信噪比,进而影响整机性能指标,所以腔泡系统是星载氢原子钟的核心组件。目前,星载氢原子钟腔泡系统主要采用直螺线管来产生原子跃迁所需的C场。由于星载氢原子钟物理部分的结构限制,直螺线管的磁场均匀度有进一步提高的空间。探讨使用多段线圈代替直螺线管用于产生C场的可行性。首先对多段线圈产生的磁场进行理论分析计算,同时使用ANSYS电磁场仿真软件对多段线圈的各项参数进行仿真和优化,包括各段长度、段数、间距以及匝数、内径和总长度等。然后优选磁场均匀度较好的线圈配置参数,可将C场的非均匀度由直螺线管约10%降低到多段线圈约1%。根据仿真优化结果建立了试验九段线圈,对比测试了原子跃迁信号增益,同时结合电路部分进行闭环测试,对频率稳定度指标进行了对比。实验结果表明,原子跃迁信号可有效提升,阿伦方差在中短稳(1～1 000 s)表现更好。此项工作为星载氢原子钟整机性能指标的进一步提升打下了基础。 相似文献
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《天文和天体物理学研究(英文版)》2014,(8)
In order to implement an observing strategy,image degradation that occurs during optical observation of space debris is ineluctable and has distinct characteristics. Image restoration is presented as a way to remove the influence of degradation in CCD images of space debris,based on assumed PSF models with the same FWHM as images of the object. In the process of image restoration,the maximum entropy method is adopted. The results of reduction using observed raw CCD images indicate that the precision in estimating positions of objects is improved and the effects of degradation are reduced. Improving the astrometry of space debris using image restoration is effective and feasible. 相似文献
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In order to improve the ability to find the faint and small celestial bodies in the solar system, a method of shifting and stacking images which improves the detection efficiency of faint moving objects is applied to process the sequential optical images. This method determines the existence of moving objects by using the method of false position to pre-estimate the apparent velocities of moving objects, then determines iteratively the accurate positions of moving objects based on the SNR (Signal-to-Noise Ratio) and elongation of stellar image. Using the sequential images of the China Near Earth Object Survey Telescope (CNEOST), we carry out an experiment and succeed in detecting asteroids fainter than 21 magnitude which are invisible on a single image. Thus, the feasibility of this method is verified. 相似文献
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大倾角地球同步轨道(GEO)卫星相对地面并非完全静止,其星下点做南北方向的"8"字周期运动,倾角越大运动范围越大.这会降低地面望远镜对其进行凝视观测时的有效曝光时间,无法获得较高的信噪比.对地球同步轨道的监测中,在硬件条件不变的前提下,提出亚像素图像平移叠加方法.根据目标的运动速度和相邻帧图像的时间间隔,在亚像素尺度平移并对齐多幅图像,使GEO目标星象在图像序列中的位置重合,通过叠加多幅序列图像来提高目标信噪比,从而达到提升整个系统探测能力的目的.实测图像叠加结果表明,该方法可以显著提高该类目标的信噪比.叠加5幅图像时,整数像素叠加图像的信噪比约为原图像的1.7倍,而亚像素叠加图像的信噪比是原图像的2倍左右. 相似文献
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《Chinese Astronomy and Astrophysics》2022,46(2):86-104
Geosynchronous satellite with big inclination is not completely stationary relative to the ground. Its sub-satellite point moves periodically in the north-south direction with ground track of shape like “8”. The larger the inclination angle is, the larger the range of motion is. Such effect makes the effective exposure time of Geosynchronous satellite limited when observe it by optical telescope with stare mode, and the SNR (Signal Noise Ratio) of Geosynchronous satellite image could not be increased with long exposure time. In the monitoring of Geosynchronous orbit without changing hardware, a method called sub-pixel translating superposition of successive frames of images is proposed. By translating and aligning images in the sub-pixel scale according to the moving speed of the object and the time interval of the adjacent frame images, the positions of the Geosynchronous satellite in the image sequences are coincident, and then by superposition of these translational images, the SNR of moving Geosynchronous objects and the detection capability of the whole system can be improved. Results of superposition of real observed images show that the method can remarkably improve the SNR of moving. When five images are superimposed, compared with the SNR of the original image, the SNR of the superimposed image by integer pixels is increased by around 1.7 times, and the SNR of the superimposed image by sub-pixel is increased by about 2 times. 相似文献
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SUN Rong-yu ZHAO Chang-yin PING Yi-ding XIONG Jian-ning ZHANG Chen 《Chinese Astronomy and Astrophysics》2012
In the observation of space objects with a full-frame transfer CCD camera, the camera shutter is often removed, and therefore the smeared images are produced, which affect seriously the object detection and location. Based on the difference of geometrical morphology between star images and smears, a mathematical morphology method is proposed to process the smeared images. By comparing the position accuracies of stars and space objects before and after processing, it is veri?ed that the morphological method can effectively remove the smears from astronomical images, and can signi?cantly improve the detection rates and position accuracies of stars and moving objects. The result indicates that this is an effective method to eliminate the smearing effect. 相似文献
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使用快速鲁棒性主成分分析(Fast Robust Principal Component Analysis,Fast RPCA)方法对日冕序列图像中的日冕喷流活动进行检测。检测的基本思路是利用快速鲁棒性主成分分析方法中低秩和稀疏分解的思想与日冕序列图像中有着变化尺度稍小且占比较大的随机变化背景成分、变化尺度较大且占比较小的日冕喷流的特点相结合,实现随机复杂多变的动态背景和稀疏运动目标之间的分离,从而检出作为前景变化的日冕喷流。采用太阳动力学天文台(Solar Dynamics Observatory,SDO)卫星的大气成像仪(Atmospheric Imaging Assembly,AIA)两组不同时间段、不同波段、不同观测位置的日冕序列图像作为研究对象。研究内容主要包括日冕序列图像的预处理、日冕喷流检测、快速鲁棒性主成分分析方法与帧间差分法的检测结果对比分析。实验结果表明,与帧间差分法相比,快速鲁棒性主成分分析方法能够检出强度较弱的日冕喷流,且提高了日冕喷流检测的准确度。 相似文献
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与传统CCD (Charge Coupled Device)相机相比, s COMS (scientific Complementary Metal Oxide Semiconductor)相机被广泛装备于超大天区巡天设备,与传统CCD相机不同的是sCMOS相机采用卷帘式快门,因此对其进行测光精度的分析工作是很有意义的.首先,将s CMOS相机拍摄的图像与UCAC2 (The Second U.S. Naval Observatory CCD Astrograph Catalog)星表进行匹对,识别图像中的UCAC2标准星.接着对图中的标准星进行测光并提取测光数据进行最小二乘直线拟合,获得了相应的系统转换系数并得到仪器星等至标准星等的转换公式.然后,将转化后的仪器星等和标准星等做差并计算相应的均方根误差.最后,利用计算得到的均方根误差评估sCMOS相机的测光精度,并将标准星按星等划分后,分析了相应的测光误差.计算结果表明在标准测光夜测量亮度亮于14等的星时,测光精度优于0.15 mag.通过实测精度分析可知卷帘快门sCOMS相机具有较高的测光精度,基本满足空间碎片巡天观测的要求. 相似文献