Optical communication groups at HAPCOS and their work:

German Aerospace Center DLR
Markus Knapek
E-Mail: Markus.Knapek@dlr.de
Tel: +49 8153 28-2879

HAPCOS Coordinator
Tim Tozer
University of York, UK
E-Mail: tct@ohm.york.ac.uk

 Free-Space Optical Communications on HAPs
Optical free space communication is favourable for high data-rate, long-range point-to-point links, where the terminal size, mass, and power is limited, as for example on aeronautical or space platforms. Main advantages lie in a significantly higher data rate and the lower power/ space requirements of optical links compared to RF.

One future application for optical links is the use on high altitude platforms (HAPs), which will be positioned at altitudes of about 20 to 30 km. Inter-platform links can have a range of at least 600km at these altitudes without cloud interferences.

HAPs do have the advantage of being more cost effective compared to satellites due to lower launch costs and also the possibility of easier maintenance and reconfiguration.

Applications Scenarios of Optical Links
Characteristics of Optical Free-Space Communications
  • Very high data-rates (several Gbps)
  • Small beam divergence minimizes free-space losses
  • Small, light terminals (few centimetres) with low power-consumption
  • No regulatory issues since systems do not interfere due to the small divergence angle
  • Tap-proof due to minimal signal foot-print on the ground
  • Dependence on clear sky. Can be solved by a distributed network of optical ground stations.