天体测量技术及应用研究组知识库

Two data acquisition systems of the Lower Latitude Meridian Circle (LLMC) are described in this paper, of which one is based on a video CCD and the other is based on a scientific CCD. To determine the position of a celestial body absolutely and precisely, the LLMC is equipped with several precision measurement devices such as one precision clock, nine Reticon linear photodiode arrays, one video CCD, one scientific CCD, one rotary inductive synchronizer, and one grating linear displacement transducer. To control these devices properly and collect data from these devices orderly during observations, two data acquisition and control systems are developed. The one based on a video CCD is used to test the instrumental precision of the LLMC. The other based on a scientific CCD is used for normal observations, and is composed of three subsystems. We will illustrate the functions of the measurement devices in the two systems, discuss the methods of data acquisition, and present our thoughts about software programming in the paper.