Preliminary Results of a 61 km Ground-to-Ground Optical IM/DD Data Transmission Experiment

Kurzfassung

The German Aerospace Center (DLR) is currently performing an Optical Free-space Data Transmission Experiment along with the European Aeronautic Defence and Space Company (EADS), Germany and Contraves Space AG, Switzerland. The scope of this experiment is to verify the tracking capabilities of the OPTEL 02, a space-qualified optical terminal built by Contraves, and to demonstrate optical high data rate transmission through the atmosphere. Two laser diode transmitters at 980nm, each mounted on a theodolite for static pointing and laterally separated by about 4 meters, were placed on a mountain top in the German Alps at a height of 1620m. Either pseudo-noise pattern or video data was transmitted. The OPTEL 02, performing acquisition and tracking, is situated at the DLR site in Oberpfaffenhofen near Munich at 620m. An APD receiver front-end is connected to the OPTEL 02 in order to receive data up to 270 Mbps. The optical path length between Wallberg and Oberpfaffenhofen is 61km (about 38 miles). Either bit error rate measurements or video transmission can be performed. This paper presents the experimental setup used, link budget calculations for the particular scenario (including beam divergence, refraction, damping and scintillations), and finally the preliminary results of the experiment.