Strategic Analysis And Optimum Design Of Intersatellite Optical Communication ATP System

With the rapid development of science and technology,people's demand for high-capacity and high-speed information transmission is increasing day by day.Intersatellite optical communication,a new era of space communication technology,has begun to shine brilliantly.It has a wide range of application value and application prospects,and is a hot spot in the development and research of science and technology all over the world.Because of the changeable and complex space environment,long communication distance and narrow laser beam in intersatellite optical communication system,it is very difficult to establish a fast and efficient communication link,and the laser communication system has high tracking accuracy requirements.Therefore,acquisition,tracking and pointing(ATP)technology is the key to realize intersatellite optical communication.This paper introduces ATP control system and its component modules,the working principle of coarse tracking and fine tracking module and the technical specifications used in this paper are described.Expounds the control principle of double detector and single detector compound axis control system,establishes the mathematical model of motor,and designs and simulates the current loop,speed loop and position loop respectively.The mathematical model of fast steering mirror(FSM)is established,and the fine tracking loop is designed and simulated.By comparing and analyzing the performances of two kinds of compound axis control systems,the comparison results of double detector and single detector compound axis control systems are obtained.The two control systems have almost the same system performance in theory and have the same tracking effect when tracking the same given input signal under ideal conditions.In this paper,the influence of bandwidth ratio of coarse and fine tracking system on tracking accuracy is studied,and the limiting factors of bandwidth of fine tracking system are analyzed.The relationship between the bandwidth and the torque disturbance of the coarse tracking system is studied,Based on the theoretical analysis of the bandwidth optimization of the coarse tracking system,the simulation experiment of the bandwidth optimization of the coarse tracking system is designed,and the conclusion of the bandwidth optimization of the coarse tracking system is obtained.The relationship between control system bandwidth and signal power spectral density is studied,which provides a reference for designing system bandwidth accroding to signal power spectrum and system accuracy index.This paper completes the hardware design and control software design of ATP main control module and turntable servo module based on DSP and FPGA,and builds a complete experimental platform.The ATP control system is used to carry out the target scanning experiment and the scanning,acquisition and tracking experiment when the target is stationary and moving.The ATP control system achieves the high-precision acquisition and tracking of the moving target,and the tracking accuracy of the system reaches the expected design target.Target tracking experiments of double detector and single detector compound axis control systems are carried out,and the results of tracking experiments of the two systems are compared.The bandwidth optimization experiments of the fine tracking system and the coarse tracking system are carried out,which improves the tracking accuracy of the system and improves the system performance.