Design and early development of a UAV terminal and a ground station for laser communications

摘要

A free-space laser communication system has been designed and partiallydeveloped as an alternative to standard RF links from UAV to ground stations.This project belongs to the SINTONIA program (acronym in Spanish for lowenvironmental-impact unmanned systems), led by BR&TE (Boeing Research andTechnology Europe) with the purpose of boosting Spanish UAV technology. AMEMS-based modulating retroreflector has been proposed as a communicationterminal onboard the UAV, allowing both the laser transmitter and theacquisition, tracking and pointing subsystems to be eliminated. This results inan important reduction of power, size and weight, moving the burden to theground station. In the ground station, the ATP subsystem is based on aGPS-aided two-axis gimbal for tracking and coarse pointing, and a fast steeringmirror for fine pointing. A beacon-based system has been designed, takingadvantage of the retroreflector optical principle, in order to determine theposition of the UAV in real-time. The system manages the laser power in anoptimal way, based on a distance-dependent beam-divergence control and bycreating two different optical paths within the same physical path usingdifferent states of polarization.