Same Rate Two-speed Tracking Imaging Ccd Camera Digital Control System

The CCD cameras with high performance have been widely used in astronomical observations.The techniques for observing moving objects or still objects independently have been mature.When both the moving objects(such as satellites or debris)and the still objects(such as stars)are observed at the same time via one same CCD camera,however, images of one kind of these two objects must be elongated in the most time.In order to solve this problem,we develop a novel imaging technique and a corresponding observation method.Photosensitive areas in some CCD arrays are physically divided into two zones or more.Based on these CCD arrays,we can implement our new idea,that is,one half of the photosensitive area is used to image the still objects in the stared mode,and another half to image the moving objects in drift scan mode.It means that we can track both moving objects and still objects at the same time without the elongation of their images on the same CCD frame.Thus the new technique is called Dual-Speed Tracking Imaging on Same Frame(DSTIS).In this paper,the operating principle of DSTIS CCD Camera has been introduced briefly. After some discussions on the request of a digital controller for the camera,the design philosophy and basic structure of the controller are presented in detail.According to the operating principle of the DSTIS CCD Camera,the digital controller is obligated to drive the camera working in several deferent modes.In order to make the mode-shift more effectively and conveniently,we decided to establish double-level(top-level and bottom-level)structure.The top-level mode is used to not only communicate with the peripheral device but also coordinate the bottom-level modes shift and provide various clock signals needed by the bottom-level modes.After much calculation we established four bottom-level operating modes.The four modes are stare mode,drift scan mode, stare-drift scan mode,drift scanning-frame transfer mode.The first two are used in tracking still objects(such as stars)and moving objects(such as satellites or debris)individually. The last two can track both still and moving objects at the same time without the elongation of their images on the same CCD frame.When the system adopt the forth mode,the shutter isn't needed any more for the photosensitive area which is used to track still objects.This characteristic of the forth mode must be laid particular stress on.The distant control interface is developed basing on Visual C++ 6.0.In this system,an exchange between the remote PC and the camera is via network with the TCP/IP and UDP protocol.In the design, the software and hardware which we select are:Quartusâ…¡and Niosâ…¡5.0,Visual C++ 6.0,a computer,a specially-made printed circuit,Agilent1693A logic analyzer.The simulation and testing results are also listed.Problems that were encountered during the simulation and testing has been analyzed in detail and solved successfully.By the results of the software simulation and hardware testing,the design has been certified correct.