Research On The Effect Of Pointing Accuracy On The Performance Of Inter-satellite Laser Communication Terminal

Space laser communication technology can effectively achieve high bit rate and secure communication in space.At present,countries such as the United States,Europe,Japan,and China have successfully implemented in-orbit satellite laser communication experiments using different detection systems.In the entire process of inter-satellite optical communication,the aqusition process is the key technology for the establishment and recovery of communication.The effect of pointing error on the acquisition process during the establishment of optical communication links has been studied in this thesis.Firstly,the host computer software of the star sensor is written,the satellite attitude is obtained by using the star sensor,and the establishment process of inter-satellite optical communication is analyzed,and the initial pointing model is established.Secondly,the error model of the relay optical branch is established,using MATLAB Carry out simulation analysis to analyze the relationship between pointing error and two-axis rotation angle.Finally,the effect of pointing error on the aquisition probability and average time is analyzed,a aquisition model is established,the aquisition process is simulated by Monte Carlo method,and the impact of pointing error on the aquisition probability and average time is analyzed.The main work content is as follows:(1)Analyzed the establishment process of optical communication link,introduced the working process of PAT system and composite axis control,established the initial pointing model and relay optical path model.The initial pointing model only needs to be used to analyze the influence of the coordinate conversion process on the pointing error.The relay optical path is divided into four branches: transmitting branch,catching branch,fine following branch,and receiving branch,adding the mirror error,and establishing error models respectively.(2)A model for analyzing the beam pointing error of the relay optical path of the PAT system is established.Firstly,the relay optical path of the PAT system is modeled,and the error transmission process of each branch of the relay optical path is analyzed according to the established model.After adding the influence of the assembly error,the angle of the pitch axis and the azimuth axis is analyzed when the two-dimensional turntable rotates.The impact on pointing error,so as to provide a basis for reducing pointing error.(3)In the presence of pointing errors,the scanning time and aquisition probability during the capture process of the inter-satellite laser link are studied,and the calculation expressions for the average scanning time and capture probability under the influence of pointing errors are given.According to the calculation expressions,MATLAB is used for simulation,and the changing laws of single-field scanning time,multi-field scanning time and capture probability are obtained in the presence of pointing errors.(4)The aqusition model is established,simulated by MATLAB software,and analyzed by Monte Carlo method.The aqusition probability changes under different random angle errors are analyzed,and the correctness of the capture model is verified.Based on the Monte Carlo method,the results are obtained under different pointing errors.,The capture probability changes with the number of scans.It can be concluded that when the number of scans is greater than 5,the capture probability is greater than99%,and the capture probability will not increase significantly as the number of scans increases.