Tactical Satellite Communications Program: Program 591 and LES-5 Test Report

Testing with the Lincoln Experimental Satellite LES-5 with terminals on board aircraft, ships, submarines, and vehicles demonstrated the feasibility of using UHF repeater satellites to enhance the capability of tactical communication links for world-wide military forces. This report presents a summary of the results of the initial phase of the Tactical Satellite Communication Program TSCP involving Tri-Service participation in the technical and operational feasibility tests. Although the demonstrations were successful, there exists the need to improve terminal equipment with respect to antenna coverage and efficiency, smaller size and weight to meet installation needs, and more convenient message entry and display devices. Apart from the unexpected fast fading phenomenon observed on aircraft, which was easily compensated by the antimultipath diversity system used in aircraft and ship terminals, the characteristics of the propagation medium and sources of natural interference were found to be essentially as predicted. The coverage was generally limited at the horizon by fading at the high look angles by the antenna pattern. Uplink and downlink measurement RFI indicated general agreement with predicted levels based on known U. S. controlled ground-based transmitters. Effective use of simple antennas on aircraft, small ships, and submarines yielded the desired objective of low-cost antennas with broad coverage communication was maintained despite movement of the terminal. This makes the UHF band acceptable in a large number of applications where SHF operation is not presently feasible.