Small Satellite Antenna To Find The Star And Measurement

This article studies the problems of the small-scale satellite antenna automatically searching satellite and auto-measuring the parameters of the antenna with the development of the study of technique towards antenna measurement. This study can directly serve in the modern long-range education system and the measure realm of satellite antenna. The first function of the study is searching satellites. The great majority of transferring information is by satellites in the modern long-range education system. So it is important for receiving station to search satellites fleetly and conveniently. The other function is auto-measuring the parameters of the satellite antenna, which is applicable to the antenna laboratory of the institutes.This article designs the system from two aspects of software and hardware. According to the automatic control theories, the hardware of the system is divided into the control equipments and the control object. The control object is the step motor which makes the antenna platform rotate. The functions of the software system include controlling the hardware, searching satellite and measuring the main parameters of the antenna. The software use Delphi 5. The intention of software controlling hardware is to get the test signal which is generated by A/D converter, and generates the controlling word which controls the motor to work.The algorithm of searching satellite is the most important. Searching satellite is to change the azimuth angle and pitching angle by making antenna circumrotate azimuth axis and pitching axis with controller, so antenna can point itself to different satellite according to the demands. If the antenna's direction departs from satellite, it can adjust antenna to track satellite signal automatically. According to tracking theory, automatic following can be divided into three systems: step-advance tracking, taper-scan tracking and single-pulse tracking. Today, while satellite's position precision improves and microcomputer develops with very fast speed, more and more Type B stations and minitype F3 stations employ step-advance tracking. According to the relation between searching step and adjusting step, step-advance following can be divided into four kinds: memory-extemum tracking, same-step-advance tracking,both-direction-search-equal-adjustment step tracking,both-direction-search-changeable-adjustment step tracking. In this system, by analyzing and comparing, we select the mode of both-direction-search-equal-adjustment step tracking.The first part of this text introduces the conspectus of the satellite antenna measurement, and primarily explains the concept of the main parameters. The second part gives the system's frame design. The third and fourth parts introduce the software and hardware design of the searching satellite subsystem in which includes the discussion of the searching satellite algorithm. The part of the fifth realizes the function of the antenna parameter's testing and measuring. The software realization of the radiation pattern is very important because it is the base of the other parameters of the antenna. The sixth part introduces the running and debugging circumferences, and also the lacks.Computer is used in antenna parameter measurement as a kind of high-powered information processor in modern time. This study makes the best of its powerful capability of logic judgment, calculation and information processing, and renders the measurement of antenna to a new level. The process of measure is more automatic and more reliable and the measurement of antenna is more precise. The operation is more simple and frank. So this study has certain practical expansion value.