Hiroshi Akima

Abstract: The Geostationary Satellite Orbit Analysis Program (GSOAP) is computer software that analyzes system performance and mutual interference of comunication satellites using the geostationary satellite orbit. Calculation of the CIR (carrier-to-interference ratio) margins is n essential part of GSOAP. It involves a variety of technical problems, i.e., earth-station and satellite antenna radiation patterns, radio wave propagation models, and related problems such as the polarization angles of linearly polarized emissions, combining of the transmitting and receiving antenna gains, percent of the time for which the CIR is to be protected, and so forth. Various transponder arrangements in the satellites may contribute to the complexity of the calculation. Some of the methods for solving such problems are taken from the ITU (International Telecommunication Union) and CCIR (International Radio Consultative Committee) documents, while others have been developed in the present study. GSOAP is still under development. This report describes the technical basis for GSOAP, Version 2.

Keywords: geostationary satellite orbit; antenna gain pattern; carrier-to-interference ratio (CIR); CIR margin; GSOAP (Geostationary Satellite Orbit Analysis Program); radio wave propagation model

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