Design and Verification of Free Space Optical Communication Relay Between Ground and Tethered Ball

There are currently some deficiencies with microwave mobile relay networks,such as short relay distance, sluggish data transfer rate,high power consumption,and limited operating frequency. This paper builds a relay system using laser communication technology to complete real-time forwarding of infrared high-definition data within a distance of more than 20 km from the tethered aerostat and the ground base station. This experiment＇s success serves as a technical reference for the use of laser communication technology as an airborne communication relay station. A scanning acquisition scheme and attitude stability compensation scheme based on probability statistics are proposed to address the uncertain initial pointing angle and the external conditions of the rapid change of platform attitude. To avoid the complex integral calculation,this paper proposes a method based on the fourth-order Runge-Kutta to improve the algorithm＇s accuracy while ensuring the function＇s realization. The feedforward speed is introduced into the speed loop of the closed-loop tracking system based on the spatial position of the target and the change in its own attitude,which effectively improves the system＇s tracking stability. We plan to conduct experiments on relaying laser links in air-to-air networks in the future.