Digital data transmission via troposcatter channels [Intro to following five papers]

The publication as a set of a series of papers prepared by, or under the direction of, a single author, albeit a recognized expert, requires an explanation and an introduction. Too infrequently does a sponsored study program permit investigation of a technical subject to the depth necessary for the development of an adequate treatment in technical paper form. Dr. Bello´s capability as a program manager in leading the study to a successful conclusion and the sympathetic support of the US Air Force Rome Air Development Center are evidenced by the detail of the five papers following in this Transactions. They complement each other in presenting an exhaustive treatment of the fundamental processes involved in digital data transmission via troposcatter channels. These papers present major contributions to solutions of the problems of digital troposcatter communications, with information which may affect the design of future systems. One paper is the first in open literature in which the concepts of modern communications theory are applied to optimum modem design for digital tropo. The analyses and computer simulation procedures, for calculating error performance of multifrequency, multiphase, adaptive bias systems, under conditions of additive noise with flat fading, and with frequency selective fading, are new and will be useful for workers in this field. Another paper contains a single, unifying treatment of the frequency and time-dependency of a tropo channel. In another, the definitions used in the development, if widely and commonly available, will provide a good basis for the advancement of tropo channel understanding. A concise compilation of the various modulation techniques, from the standpoint of power-bandwidth limitations is found in another paper. The analyses are complete, in particular, the discussion of modulation and detection techniques for tropo communications, which have been given a thorough and systematic treatment.