Initial Pointing Technology of Line of Sight and its Experimental Testing in Dynamic Laser Communication System

The initial pointing unit of the line of sight (LOS) operating in the open-loop mode is an important part of the space laser communication system, which directly determines the size of the field of uncertainty (FOU) and the length of the scan time. In this paper, the composition and working principle of the initial pointing of the LOS in the dynamic laser communication system are studied in detail. The initial pointing angle (IPA) of the LOS is derived by applying the principle of coordinate transformation, and the factors affecting the size of the FOU are analyzed. It is proposed to introduce the extended Kalman filtering technique into the initial pointing to reduce the size of the FOU. In the demonstration experiment of the dynamic laser communication (including airship-ship and aircraft-aircraft), the dual-antenna global positioning system/inertial navigation system composite device is applied to obtain position, attitude, and other parameters in real-time to realize the performance test of the initial pointing system. The size of the FOU is measured with a target-viewing camera, and the filtered and unfiltered results were compared.