Design And Implementation Of Narrowband Communication System For Small Satellites In Low Orbit

With the wide applications of satellite and space technology in various industries,small satellites have attracted more and more attention.Especially since the beginning of the new century,with the increase of human demand for space products,the demand for satellite applications has also increased rapidly,which further stimulates the development of small satellite industry.In order to expand the Chinese small-scale low-orbit general satellite platform and enhance our country's ability to support rapid launch and multi-functional integrated application methods,a new technology test satellite "Tiankun 1" was developed by The Second Academy of Aerospace Science and Technology of China.The satellite is an autonomous high-functional density small agile low-orbit satellite(LEO)platform.The system completed in this paper is one of the communication loads in the satellite: the narrowband communication system of small satellites in low orbit.Firstly,according to the mission requirement of LEO narrowband communication system,this thesis analyzes the overall design requirements of the system,especially the communication system design requirement(including the narrowband communication load,the requirements of ground communication terminal and communication antenna).According to the design requirements of the system,the parameters are calculated and simulated,the link loss is derived,the communication time and cycle of the satellite orbit are analyzed,in which the communication time is analyzed in detail combined with the realized communication protocol.On the basis,we completed the overall design of the narrowband communication system for small satellites in low orbit.Secondly,based on the practical engineering flow design procedure,the requirements of small satellite communication system are decomposed into the analysis of communication system perfromance metrics,general framework of narrowband communication load processor,reliability and thermal stability analysis.Then,the detailed analysis and design of operating frequency band and antenna,loss analysis of communication link,general frame design,structure design,interface design and power supply design,RF receiver channel design,RF transmission channel design,signal processing channel design,communication protocol design,communication link frame design,data transceiver flow design,communication chain flow design of communication device on on-orbit satellite and ground terminals are carried out.Through the actual communication load and the on-orbit test and debugging of the satellite and ground terminal,the thesis completes the verification and test of the actual system.The related test results show that,the thesis realizes the predetermined function of the system,and verifies the feasibility of the design and implementation of the paper.The related work of this paper has important reference and reference value for further perfecting the narrowband communication system of low orbit small satellites.