Tests of Multibeam Scintillation Mitigation on Laser Uplinks

A report presents additional details about parts of the program of research and development that is the topic of the immediately preceding article. The report em- phasizes those aspects of the program that pertain to the use of multiple uplink laser beams in a ground-to-spacecraft optical communication system to reduce (relative to the case of a single uplink laser beam) the depth and frequency of occurrence of fades in the uplink signal received at the spacecraft.The underlying multibeam scintillation-mitigation concept was described in "Multiple-Beam Transmission for Optical Communication " (NPO- 20384), NASA Tech Briefs ,Vol.22,No.11 (November 1998), page 56. The report discusses the need for mitigating uplink scintillation; briefly describes the Optical Communications Telescope Laboratory and its role as the ground station in the research; summarizes prior experiments in uplink scintillation and multibeam mitigation of scintillation in ground-to-spacecraft laser communications; and describes key experiments planned to be performed in the next five years. The report then elaborates somewhat on the initial experiments, which are to be dedicated to understanding and perfecting the multibeam scintillation-mitigation strategy.