Signal Control in Optical Ground-to-Space Links

Kurzfassung

Optical Uplinks from Ground Stations to Receivers in Space suffer from atmospherically induced intensity scintillations and beam pointing jitter. These channel impairments limit the effective transmit aperture size and thus set a restriction to the link budget. Transmitter diversity helps to reduce Fading but at the expense of spectral efficiency and additional power. An artificial Laser Guide Star allows better knowledge of the atmospheric index-ofrefraction structure and thus - together with Adaptive Optics - complete uplink beam control seems possible in future. Another fading-reduction is withal offered from the sensitivity run of coherent- or APD-receivers in contrast to thermal-limited power detectors. This talk introduces the different techniques which have been investigated in theory and practice by the Optical Communication Groups of DLR-IKN.