Radio link analysis using SPLAT!

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SPLAT! is a cross-platform, open-source software that can be used to analyze a radio link between two locations and to generate coverage maps of RF transmitters. Coverage maps are calculated using Longley-Rice Irregular Terrain Model (ITM) algorithm. SPLAT! can predict RF coverage for any frequencies between 20 MHz and 20 GHz. It is thus useful for ham radio, broadcast radio, terrestrial television and wireless networks.

To use SPLAT!, you need to know some parameters of the transmitter. These are the exact location (coordinates), antenna height, transmission frequency, polarization and effective radiated power (ERP). SPLAT! can then calculate both path loss and received signal strength.

The procedure of installing SPLAT! is described in a previous article. The point-to-point analysis calculates some useful parameters like: azimuth and elevation of receiving antenna, distance to transmitter, mode of propagation, received signal strength and density. You must also supply a receiver parameters file to SPLAT!. This will contain the location, antenna height and some other terrain parameters. SPLAT! will generate a report and a graph if you have Gnuplot installed.

SPLAT! height profile graph
SPLAT! height profile graph

Compile and setup RF coverage prediction software SPLAT!

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SPLAT! is a cross-platform, open-source software that can be used to analyze a radio link between two locations and to generate coverage maps of RF transmitters. Coverage maps are calculated using Longley-Rice Irregular Terrain Model (ITM) algorithm. SPLAT! can predict RF coverage for any frequencies between 20 MHz and 20 GHz. It is thus useful for ham radio, broadcast radio, terrestrial television and wireless networks.

SPLAT! uses data from SRTM elevation files. Although it is cross-platform, up-to-date binaries for Windows are hard to find. On the other hand, for Linux users, it is available in the repositories of the major distributions. This post will show you how to compile SPLAT! on Windows and Linux, how to obtain and convert elevation data and at last how to generate point-to-point and coverage prediction analysis.

There are two variants of SPLAT! based on the type of elevation data they use. SRTM3 files are 90 meters resolution, 3 arc-sec files. These are the "standard definition" files suitable for SPLAT! And there are SRTM1, 30 meters resolution, 1 arc-sec files that are considered "high definition" and are suitable for SPLAT! HD. I recommend SRTM3 (SD) files because the results are very good and processing time is not too high.

SPLAT! line-of-sight coverage
SPLAT! line-of-sight coverage