The institute was responsible for the communications link design, experiment design and optimization of the ground station. The DLR spin-off Vialight Communications GmbH built the airborne terminal. New opto-mechanical tracking systems were developed and applied on flight and ground segment for link acquisition and stabilization. The flight tests were carried out at the end of November 2013 near the Airbus Defence & Space location in Manching, Germany. The campaign successfully demonstrated the maturity and readiness of laser communication for aircraft downlinks at a data rate of 1.25 Gbit/s. Performance could be measured at aircraft speeds up to Mach 0.7 and video data from an onboard camera was transmitted. Tracking accuracies of up to 20 rad rms for the airborne terminal and the ground station were achieved at instantaneous tracking errors below 60 rad and 40 rad, respectively. The tracking link worked up to a horizontal distance of 79 km and data transmission was possible up to 50 km. The experiment shows the maturity of aeronautical laser communications in a very challenging environment. Future aircraft may be equipped with that technology for the sake of passenger connectivity and payload data transmission, for example.
Free-space optical communication has the potential to meet the future growing demand of very high data-rates in aeronautical communication. Application scenarios are data links between aircraft, aircraft to satellites and aircraft to ground. The last one is the main focus of the DODfast (Demonstration of an Optical Data link fast) project. The goal of the project is to demonstrate a high data-rate optical downlink from a fast flying platform. Whereas this technology has already been successfully demonstrated using DLR’s turboprop aircraft Do228, the new innovation lies now in bringing the technology in a state to perform with a jetfighter as flight platform and DLR’s Transportable Optical Ground Station (TOGS) as the receiver on the ground. The biggest challenges in this demonstration compared to earlier scenarios are the higher speed and vibration of the aircraft body.
Based on DLR technology, the MLT (Micro Laser Terminal) is developed by ViaLight Communications and installed in the Avionic-Demonstrator-Tornado-Pod (ADT-Pod) which is attached at the center line of the aircraft. The ADT-Pod also hosts the data source: the surveillance camera and a special media converter, developed by the project principal Cassidian. The TOGS is equipped with an optical free-space receiver for the 1 GBit/s downlink and the necessary beacon laser for the optical tracking system. For the remote control of the MLT and GPS telemetry for the TOGS, a TM/TC system is also installed by Cassidian. This comprises one RF uplink (telecommand) and two downlinks (telemetry).
Name of project: DODfast (Demonstration of an Optical Data link fast)
Project partner: Cassidian, DLR, ViaLight Communications
Nov 2011 – Feb 2014