Calculation Andanalysis Of Electromagnetic Interference In Low Orbit Constellation Communicationsystem

The Internet of Things is an important part of the new generation of information technology,and also an important stage of development in the information age.But the terrestrial Internet of Things faces difficulties: limited resources;Greatly affected by the weather;Small system capacity.Human beings are gradually expanding the Internet of things to the sky,and the space information network has become a research hotspot.Due to the saturation of geostationary orbit resources,non-geostationary orbit satellite constellation plans have been put forward at home and abroad.Compared with high-orbit satellite,low-orbit satellite communication has less time delay and less signal attenuation,which will be beneficial to low-orbit constellation to suppress jamming of enemy high-orbit satellite communication on the military level.The main research contents of this paper are as follows:Firstly,the time system and space coordinate system involved in this paper are defined,and the transformation relationship between them is given.On this basis,the meaning of SGP4 analytical model and corresponding parameters of two-row elements are introduced,and compared with STK simulation.When the orbit accuracy is satisfied,two kinds of gain models of spacecraft covering antenna are established.The other type covers a large area of the beam.The coverage times and time of the antenna to the ground target were compared with the STK simulation,and it was found that the pointing accuracy also met the requirements of the simulation.Under the condition that the orbit precision and pointing precision meet,the design of low orbit constellation is carried out later,and the basic configuration design principle of two common low orbit constellations(Walker constellation and polar orbit constellation)is introduced.Based on the satellite visibility judgment model for ground targets,the evaluation indexes of low-orbit constellation coverage performance were established,including coverage time percentage,maximum coverage gap,coverage weight,and average coverage elevation Angle.Finally,the two constellations are simulated to analyze and compare their advantages and disadvantages.Here,the basic simulation conditions of this paper have been established.Then,three attenuation calculation models of link exposure,namely rain attenuation model,atmospheric absorption model and free space attenuation model,have been established for spacecraft and ground communication.Through simulation,it is found that the attenuation of free space has the greatest influence on communication,followed by the attenuation of rainfall,and finally,the attenuation of atmospheric absorption has the least influence on communication.Then,the performance of communication link is measured by performance indexes such as load/dry ratio,load/noise ratio and bit error rate.Finally,the low orbit constellation is used to model and simulate the pressurized interference of high orbit satellite.For two simulation scenarios of the same frequency interference.Firstly,the communication quality of high-orbit satellites subjected to interference from the same satellite and the same frequency beam is analyzed and compared under the conditions of monochromatic,three-color multiplexing and seven-color multiplexing.For the high orbit satellites with three colors multiplexing,the interference in the low orbit constellation with the same frequency is added.Second,the communication quality of the whole communication area is judged by the communication quality of a specific point in view of the interference situation when the high-orbit satellite is only equipped with an area covering antenna.