TIREM/SEM Handbook.

Abstract : This document provides a description of the operation of the Terrain Integrated Rough Earth Model (TIREM) and the Spherical Earth Model (SEM), including the engineering formulations on which the models are based. Both models are modular programs with many common subroutines that conform with ANSI Fortran standards. TIREM and SEM can be used as independent propagation models for rough earth (with a known terrain profile) or smooth earth applications, respectively. Both models consider the effects of free space spreading, reflection, surface wave propagation, diffraction, tropospheric scatter propagation, and atmospheric absorption, as appropriate.