| Abstract: | The use of optical communications for the high-data-rate links of the future European Data Relay System (EDRS) is receiving much attention. To confirm the feasibility of such communications links, an experimental system (SILEX) consisting of three satellites (two in geostationary orbit and one in low earth orbit) is planned for 1992 or 1993 to demonstrate both inter-orbit link (IOL) and intersatellite link (ISL) capabilities. A detailed feasibility study was performed from January to July 1987 under a European Space Agency (ESA) contract with Matra (France) as prime contractor, ANT (West Germany), Telespazio and Selenia Spazio (Italy) as subcontractors, and contributions from Berlin (France) and Dornier (West Germany). The system is based on GaAlAs semiconductor technology (0.8 μm) with silicon avalanche photodiodes (APDs) as detectors and arrays of charge-coupled devices (CCDs) for both acquisition and tracking sensors. The design will allow wavelength division multiplexing (WDM) and high-data-rate transmission to be demonstrated. The expected data rates are 120 Mb/s duplex for ISL, 1 Mb/s on the IOL forward link (GEO→LEO) and two to four simultaneous 60 or 120 Mb/s channels on the IOL return link (LEO→GEO). |
