Longley-Rice and ITU-P.1546 Combined: A New International Terrain-Specific Propagation Model

A new propagation model and software implementation combines the best of the NTIA-ITS Longley-Rice methodology and it´s Irregular Terrain Methodology (ITM) software implementation, a set of deterministic approximation equations derived from the empirical data in ITU-R P.1546 and other ITU Recommendations, and Snell´s Law and Beer´s Law, to create the first truly point-to-point, terrain-specific international radio reception signal strength prediction model. This implementation utilizes 3-arc-second Satellite Radar Terrain data that is available internationally, making this a propagation model that can be implemented internationally. This new model more fully implements the original Longley-Rice Tech Note 101 methodology that does the ITM. The core software of this model, the equivalent of the ITM core, is the Irregular Terrain with Obstructions Model, the ITWOM. This model is specific and accurate enough to be used for the interference studies for which it was developed, has been in continuous development since 2005, and has been in use for two years by Givens & Bell to produce FM vehicular reception studies for analog and digital (IBOC) reception. Source code for a basic version of the ITWOM, designed for 3-arc-second database use and limited to the minimum range of the ITM and P.1546 recommendations, will be released.