Studies On Control Systems And Data Pre-processing Systems In The Lower Latitude Meridian Circle (LLMC)

The purpose of our studies in this thesis is to accomplish a project of the LLMC equipped with a scientific CCD. Some basic requirements for an azimuth, a vertical angle and a CCD tracking transmission control system after the CCD is attached to the LLMC are discussed in the thesis. Problems in the original systems are pointed out, and corresponding solutions for the problems are proposed. The former 2 control systems are improved and the last is implemented successfully in both hardware and software. A data acquisition system based on a video CCD used in the experiment and adjustment of the telescope is introduced, and some improvements on the system made by author are specially pointed out. A data pre-processing system based on the video CCD is described in detail. After the functions and characteristics of the 9 Reticon signals are anatomized, a new method used to process these Reticon signals is presented, which consists of a reticle/slit image searching algorithm, a self-estimation filtering algorithm and a single wave centering algorithm. The method provides the high precision measurement of the LLMC with a fundamental condition. After some basic requirements for the data acquisition system based on the scientific CCD are discussed, a solution including 3 sub-systems is proposed. Each sub-system is implemented successfully in both hardware and software. The data pre-processing system based on the scientific CCD is also described in the thesis. After the characteristics of the astronomical CCD image are dissected, a method meeting requirements of the LLMC is presented, which can automatically process many CCD images and observational objects in the images. In the method, an object searching algorithm, a centering algorithm and an algorithm to determine visual magnitude of objects have some distinctive features. A new test system in the LLMC is described in the last. Compared with the original system, the new one has many obvious advantages in the functions and the practicability.