Troposcatter Propagation Tool

The emerging threat to SATCOM (through natural and hostile means) has resulted in a need to understand and exploit other long range Beyond Line Of Sight (BLOS) propagation options such as tropospheric scatter. While technological issues such as the large size, weight and power (SWaP) profile have been overcome in recent years, the lack of accurate propagation tools for deployment planning and operations have not.

Modern troposcatter systems tend to operate in C Band (4.4 - 5.0GHz) but variants are available in, S (~2GHz), X (~8GHz) and K (above 12GHz) -bands. These systems can potentially offer high bandwidths in excess of 100Mbps over geodesic distances in excess of 160km dependent upon climatic conditions.

The propagation mechanism for troposcatter systems depends on the operational scenario. Short range Beyond Visual Line of Sight (BVLOS) paths may rely on atmospheric ducting, diffraction, or refraction, whilst long range Beyond Line of Sight (BLOS) paths will be dominated by troposcatter i.e. scattering from refractive-index in-homogeneities.

Whilst the Troposcatter systems have benefitted from technological advances, the tropospheric propagation prediction tools have not developed to the same extent and most tools still use long term atmospheric data. In order to fully utilise troposcatter communications, therefore, it is imperative that deployed systems are supported by accurate propagation tools for mission planning and operations.

New propagation tools to support troposcatter systems must use novel data fusion methods and exploit real-time data to provide useful now-casts and forecasts information. In particular, they must correctly predict the performance of modern troposcatter modems in terms of quality of service and available bandwidth to ensure operational efficiency.

Importantly, for any propagation planning or analysis tools to work accurately, they must not only just consider troposcatter but incorporate other propagation modes such as; ducting and diffraction as well as the impact of terrain and ideally rain and sand side-scatter to provide a complete solutions.