Design And Improvements Of Test System For Pico-Satellite

Micro-satellite has become more and more popular among researchers in the field of astronautics, whose advantages include its small size, lightness and relatively fast and low-cost R&D. However, these advantages in turn underscore unique challenges in testing micro-satellite systems to ensure their quality and reliability. Therefore, how to build a suitable satellite test system and devise a reasonable test protocol, become akey factor in the success of a satellite project.The author's research at Zhejiang University mainly focused on the design of testequipments for ZDPS-1A satellite, including earth station equipment, solar cell simulator and integrated test equipment. In addition, the author conducted a preliminary study of modeling methods for the pico-satellite test.ZDPS-1A earth station equipment was designed on the basis of software-defined radio with all the key parameters obtained through simulations and optimizations. The main functions such as modulation, demodulation and side-tone ranging were all successfully realized on FPGA.Based on the previous side-tone ranging system, the new system features better accuracy and credibility as a result of improved phase comparison method. Meanwhile, the noise sources are to be discussed in detail.We also designed a solar cell simulator with a simple hardware structure and ingenious software algorithm that can simulate the output of a real solar cell.In ZDPS-1A modeling, we treated the actual pico-satellite as a series of functional modules and the instructions received by the pico-satellite as information flow. We then fed them back to the test user for analysis. The purpose of modeling is to lay the foundations of computer-aided automatic test in the future.In summary, we have developed a series of test equipments and verified their feasibility, stability and reliability with vigorous experimentations. We believe that our equipments will offer a crucial solution to the increasingly sophisticated satellite testing tasks, and furthermore, greatly facilitate the technological advance and marketization in the area of pico-satellites. Our immediate goal involves establishing a theoretic model in order to rationalize our current test results, which will allow us to further improve both the efficiency and coverage of our testing system.