Airborne Laser Communication System with Automated Tracking

Xizheng Ke,Hanli Liang,Nicusor Iftimia

doi:10.1155/2021/9920368

Abstract

The acquisition, alignment, and tracking system is an important part of airborne laser communication and is the prerequisite and guarantee for the normal communication link. In order to solve the problem of automatic tracking of laser communication links in the airborne environment, the rapid capture, alignment, and tracking of beams between terminals are realized. This article proposes a stepping motor as a control servo system and a four-quadrant detector as an automatic tracking method for the detection unit. The pulse width modulation signal controls the rotation speed of the stepping motor and combines the position distribution of the light spot on the four-quadrant detector to achieve high-precision beam tracking. On this basis, indoor simulation experiments are carried out. After many experiments, the tracking accuracy is better than 2.5 μrad, which shows that the system can be applied to airborne laser communication, and it is verified that this method has good automatic tracking performance for airborne laser communication.

Highlights

As a type of free-space optical communication (FSO), unmanned aerial vehicle (UAV) airborne laser communication has the advantages of large communication capacity, good concealment, strong anti-electromagnetic interference ability, and small terminal size
Airborne laser communication is affected by environmental factors such as atmospheric turbulence and background light, but the relative movement of the UAV platform and the size of the equipment increase the difficulty of establishing a laser communication link [1, 2]
Automatic Tracking Control System Structure. e airborne laser communication automatic tracking control system is composed of a laser emitting unit, an aiming actuator, a through-hole four-quadrant detector, an amplifier, and a control unit. e experimental schematic diagram is shown in Figure 1. e direct light emitted by the laser on the ground side passes through the Cassegrain telescope and the collimating lens to emit parallel light, and after being transmitted through the atmospheric channel, it reaches the mirror surface controlled by the stepping motor on the UAV side [10]

Summary

Research Article Airborne Laser Communication System with Automated Tracking

Received March 2021; Revised April 2021; Accepted 17 May 2021; Published 25 May 2021. E acquisition, alignment, and tracking system is an important part of airborne laser communication and is the prerequisite and guarantee for the normal communication link. E pulse width modulation signal controls the rotation speed of the stepping motor and combines the position distribution of the light spot on the four-quadrant detector to achieve high-precision beam tracking. In order to solve the problem of automatic tracking of laser communication links in the airborne environment, the rapid capture, alignment, and tracking of beams between terminals are realized. On this basis, indoor simulation experiments are carried out. The tracking accuracy is better than 2.5 μrad, which shows that the system can be applied to airborne laser communication, and it is verified that this method has good automatic tracking performance for airborne laser communication

Introduction

Light signal Electric signal

Tp t

Experimental Study

Third quadrant Fourth quadrant