Feasibility Study of Decision Making for Terminal Switching Time of LEO Satellite Constellation Based on the SGP4 Model

 

 

Abstract: The high speed of low earth orbit (LEO) satellites makes the terminals at each beam tend to switch rapidly and frequently. The predictable trajectories of LEO satellites allow for predictable terminal switching, therefore a simple and highly accurate orbit prediction model is required to swiftly obtain accurate switching time. This study utilizes the simplified general perturbations (Version 4) (SGP4) model to predict the LEO satellite trajectory of WT-1, an LEO satellite developed independently by the 54th Research Institute of China Electronics Technology Group Corporation (CETC). The obtained prediction results are compared with the actual telemetry data of the WT-1, which gives the accuracy of the SGP4 predicted satellite trajectory within 1 km. The terminal entry/exit beam timing is simulated by using the SGP4 model-predicted orbit and the satellite’s own telemetry data. The simulation result shows that the error between the SGP4 model-predicted terminal entry/exit beam timing and the actual timing is less than 1 s. The influence of terminal motion on prediction is discussed. The results show that the error caused by the movement of the ground terminal on the prediction is less than 0.687 s, and the SGP4 model has a definitely practical value for terminal switching determination in the LEO constellation
Keywords: LEO; switching; SGP4; WT-1