Optical Communication for High Altitude Platforms: the Stratospheric Optical Payload Experiment

Abstract

A high bitrate optical downlink was performed by the stratospheric optical payload experiment (STROPEX), a part of the EU CAPANINA project. The STROPEX objectives were to design and build the necessary hardware to demonstrate an optical backhaul downlink from a stratospheric platform to the ground and to carry out channel measurements on the link. A successful measurement campaign at ESRANGE, near Kiruna (Sweden), achieved all these objectives. The transportable optical ground station received an almost error free 1.25 Gbit/s data signal from the payload over a distance of 64.1 km with a bit error rate of better than 10-9. This paper gives an overview of the stratospheric optical payload experiment including the airborne free-space experimental laser terminal (FELT) and the transportable optical ground station (TOGS). Additionally, the successful measurement campaign is described and the operation of the experiment is discussed. Finally, selected measurements are presented highlighting significant data transmission results, pointing and tracking accuracy, and thermal subsystem effectiveness.