Recommendations ITU-R P.617-4 and ITU-R P.526-14 are some of the few propagation recommendations that are publicly available for trans-horizon propagation modeling. They are recommendations used for modeling “tropo-links” kept current by the International Telecommunications Union (ITU).
Both recommendations provide background information and various prediction methods for calculating diffraction and tropospheric scatter loss. This document summarizes the implementation procedure undertaken by Spectrum Center, Inc. to incorporate both ITU-R P.617-4 and ITU-R P.526-14 for the purpose of modeling trans-horizon radio links into the Spectrum-E© commercial web application.
Figure 1: Spectrum-E Tropo-link Path Profile Report Screen
The document below outlines the mathematical and theoretical bases of these methods with references (where applicable). The process behind implementing these recommendations requires the interpretation and understanding of complex geometric relationships between the respective terrain morphology between transmitting and receiving radio stations. These relationships are translated into C/C++ language code, which is debugged, tested, and baselined. The baselining included an extensive correlation analysis between the implemented code and over 500 measured trans-horizon links from the U.S. Department of Commerce (DOC).