Development Of Container Low-orbit Satellite Monitoring Terminal Based On SGP4 Model

The increasing prosperity of the container transportation industry has greatly promoted the economic and trade exchanges between countries,at the same time,it also brings a series of problems,such as cargo theft,illegal personnel smuggling,drug crimes and so on.In order to avoid these problems,more and more experts and scholars regard the satellite communication technology as the main data transmission means to monitor the container in the whole supply chain,and develop container satellite monitoring terminal,but these monitoring terminal have the problems such as communication with blindness,communication blind area,large satellite antenna,high power consumption and less function.Based on these problems,an in-depth research on the application of ORBCOMM low orbit satellite communication technology and SGP4 model in the field of container monitoring is made.The main work of this paper is as follows:This paper has researched the overall architecture of the ORBCOMM low orbit satellite communication system,then the hardware composition and working principle of each part of the system are described,also the communication link establishment principle,channel selection mechanism,communication data types and data session flow are analyzed.This paper has studied the SGP4 model used for prediction of space flight objects' position,and has analyzed the content and meaning of this model's input and output,then the engineering application of the model is discussed,and the specific meaning of Two-Line Orbital Element is summarized.The specific methods of the conversion between the satellite coordinate system and the WGS-84 coordinate system is analyzed,the mathematical model for calculating azimuth and elevation angle of satellite is established by using the correlation theorem of the three faces,the method of azimuth angle corrected in WGS-84 coordinate system is summarized,and the satellite intelligent prediction algorithm based on SGP4 model is designed.This paper has summarized the characteristics of different application scenarios of container,and has designed the low power consumption control logic.Also it has summarized the characteristics of the container,and the integration of the low orbit satellitemonitoring terminal to the small microstrip antenna is completed.In this paper,the hardware design is realized by using Altium Designer 14.2 software,the software design is realized by using Keil uVision 4 software,and the design of intelligent satellite prediction algorithm is realized by using Microsoft Visual Studio 2008 software.This paper has manufactured the container satellite monitoring terminal based on the SGP4 model,then the test environment of the satellite intelligent prediction algorithm integrated in the container monitoring terminal is built,the terminal function and power consumption test platform is also built,and this paper has completed the test contents.The research results show that: the container low orbit satellite monitoring terminal based on SGP4 model,which is researched and developed in this paper,is equipped with the capability of container monitoring in the whole supply chain,also has more function,such as solar charging,empty load detection,and so on.The satellite intelligent prediction algorithm which integration in the terminal has the ability of predicting the arrival time of the ORBCOMM low orbit satellite and its prediction error is less than 1min.At the same time,the terminal has the characteristics of small size and low power consumption.