SPLAT!
SPLAT! is a GNU GPL-licensed terrestrial radio propagation model application initially written for Linux but has since been ported for Windows and OS X. SPLAT! can use the Longley-Rice path loss and coverage prediction using the Irregular Terrain Model to predict the behaviour and reliability of radio links, and to predict path loss.
SRTM filenames refer to the latitude and longitude of the southwest corner of the topographic dataset contained within the file. Therefore, the region of interest must lie north and east of the latitude and longitude provided in the SRTM filename.